design of sodium carbonate production plant[comprehensive design project]

8/17/2019 DESIGN of Sodium Carbonate PRODUCTION PLANT[Comprehensive Design Project]

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DESIGN OF SODA ASH PRODUCTION PLANT

Comprehensive Design Project

Department of Chemical and Process Engineering

University of Moratuwa

Supervised by

Dr.Padma Amarasinghe

Group members

Danushka D.G. 050069L

Gunasekara D.T. 050137U

Jayakody J.R.U.C. 050166GMadurika B.N. 050254B

Weerasinghe D.T. 050472P


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COMPREHENSIVE DESIGN PROJECT

i

PREFACE

This report gives a narrative of our final year comprehensive design project, which is the

production of Soda ash from the sea water and lime stone mines exist in number of places in the

country. The project is the part of curriculum of the final year B.Sc. Engineering Degree program of

the University of Moratuwa and in essence it consists of basic description of such attempt made by

five undergraduate students of Chemical and process Engineering Department, University of

Moratuwa. The content of this report are outlined here.

Chapter 1 gives a brief introduction to the report and the finding from literature survey is given

in chapter 2. This was conducted to study about the soda ash production. It gives general information

about soda ash, how it began, history of the production, the types of production, uses in industrial

sectors, etc.

Designing of compatible, large scale industry in a developing country like Sri Lanka is a big

task. Especially with matching technology and feasibility to the project in such situation is a heavy

work. Chapter 3 consists of the evaluation of the complete feasibility study under technical

economical, market….sectors.

Under chapter 4, we discussed the how we select most appropriate process for the Sri Lanka

through the various operate processes in the world considering the pros and cons of several models.

Chapter 5 is focused on the process description. It begins with the feed selection; and mainly this

chapter contents based on each and every unit operation of the selected process. Equipment layout is

enlightened at the end of this chapter.

The site selection and the plant layout are given in chapter 6. Chapter 7 contains the particulars

of the environmental impact assessment. This contains the major environmental impact from the

sodium bicarbonate process plant and the how to carry out processes of the effluent management.

Full details of the safety measures intended for the plant is given on chapter 8. After that the

safety aspects considering equipment is expressed in detail.

Material balance and energy/ heat balance done on behalf of each unit operation selected isdiscussed in next two episodes chapter 9, 10. The overall material and energy flow sheets arranged for


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ii

the plant is summarized within too. The detailed calculations as well as the assumptions made have

been appended.

The final chapter is presenting the conclusion of this report a summing up of the whole project

with the benefits of the selected process and technologies are imparted in this chapter, as well how it

helped us improve our skill and knowledge. A list of abbreviations and the list of references are

appended at the end of the report.

28/10/2008


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iii

ACKNOWLEDGEMENT

When doing our Final year Comprehensive Design Project, we had to face many hardships and

challenges. It was with the help of many people that we were able to complete this project. We would

like to express our heartiest gratitude to all those people.

First of all we would like to grant our heartiest gratitude to our project coordinator, Dr. Padma

Amarasinghe, (lecturer- Chemical & Process Engineering department, University of Moratuwa) for all

the valuable advice, guidance, support and encouragement given through out the time. Dear Madam,

Thank you very much for spending your precious time to share your priceless knowledge with us, we

owe you a lot.

Then we express our gratitude to the department of Chemical and Process Engineering , all the

staff members of Chemical & Process Engineering department, including Dr. Jagath Premachandra

(head of the department), for all the assistance and big hearted support given toward while doing many

activities of this project and for including a design project in the final year syllabus. Thereby providing

us with a valuable opportunity to improve our knowledge and experience on doing a project, this will

come very useful when we go out to the industry as Chemical and Process Engineers.

We appreciate the support given by all the non academic staff of the Department of Chemical

and Process Engineering, especially the people who were in charge of the department of CAPD center,

for keeping it open at all hours so we could continue our work without interruption.

Then we would like to thank the staff of the Ceylon Glass Limited and the Holcim Lanka

limited for giving us permission to visit the glass plant and provide us necessary experience and

relevant data regarding this project.

Finally we thank all our colleagues of the department of Chemical and Process Engineering for

their help stimulating suggestions and encouragement.

Thanking You.

Group Members

Danushka D.G. : 050069L

Gunasekara D.T : 050137U

Jayakody J.R.U.C : 050166G

Madurika B.N. : 050254B

Weerasinghe.D.T. : 050472P


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iv

CONTENTS

PREFACE

i

ACKNOWLEDGEMENT iii

CONTENTS iv

CHAPTER 1: INTRODUCTION 1

CHAPTER 2: LITERATURE SURVEY 42.1. General Information 5

2.1.1. Other Names for Sodium Carbonate 5

2.1.2. Physical Properties of Sodium Carbonate 5

2.1.3. Hydrates of Sodium Carbonate 5

2.1.4. Chemical Properties of Sodium Carbonate 6

2.1.5. Grades and Specification of the Soda Ash 6

2.2. Uses of Na CO in Industrial Sectors2 3 7

2.2.1. Glass Industry 7

2.2.2. Detergent Industry 8

2.2.3. Metals and Mining 8

2.2.4. Steel Industry 8

2.2.5. Paper and Pulp 9

2.2.6. Textiles 9

2.2.7. Non-ferrous metallurgy industry 9

2.2.8. Chemical industry 9

2.2.9. Other Applications 9

2.3. Uses of NaHCO3 in Industrial Sectors 10

2.4. History of the Production 10

2.5. Overview about Type of Production 12

2.5.1. Le Blanc process 12

2.5.2. Solvay Process 14

2.5.3. Hou's Process 15

2.5.4. Dual process 15

2.6. Sodium Carbonate Minerals 15

2.6.1. Trona Based Process 16

2.6.1.1. Trona Products 17

2.6.1.2. Monohydrate Process 18

2.6.1.3. Sesquicarbonate Process 19

2.6.1.4. Alkali Extraction Process 20

2.6.2. Nahcolite based process 22


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2.7. International Scenario 22

2.8. Structure and Status of Indian Industry 23

CHAPTER 3: FEASIBILITY STUDY 243.1. Preliminary Study 25

3.2. Economical Feasibility 27

3.3. Market Feasibility 30

3.4. Technical Feasibility 31

3.5. Social Feasibility 33

CHAPTER 4: PROCESS SELECTION 354.1. Introduction 364.2. Comparison of Solvay process with Others Methods of Production 374.3. Process Selection Conclusions 40

CHAPTER 5: PROCESS DESCRIPTION 41

5.1. Main Chemical Reactions in Solvay process 42

5.2. Process Steps 44

5.2.1. Brine purification 44

5.2.2. Calcinations of limestone in kilns and the production of CO2 and milk of lime 45

5.2.3. Absorption of ammonia into purified brine 46

5.2.4. Carbonation of the ammoniated brine with CO2 to produce sodium bicarbonate 46

5.2.5. Separation of Sodium Bicarbonate from Mother Liquid 47

5.2.6. Recovery of the Ammonia using Milk of Lime 48

5.2.7. Calcinations of Sodium Bicarbonate to form Sodium Carbonate (light ash) 49

5.2.8. Densification of Sodium Carbonate to form Dense ash 49

5.3. Product (Soda Ash) Storage and Handling 50

5.4. Raw Materials 50

5.4.1. Brine 50

5.4.2. Limestone 51

5.4.3. Carbon for the Lime Kiln 51

5.4.4. Ammonia 52

5.4.5. Various additives 52

5.5. Utilities 53

5.5.1. Steam 53

5.5.2. Process water 53

5.5.3. Cooling waters 535.5.4. Electricity 54

5.6. Energy saving in the process 54


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5.6.1. Heat recovery 55

5.6.2. Energy Minimization 55

5.7. Process Flow Diagram 57

5.8. P & I Diagram 58

CHAPTER 6: SITE SELECTION & PLANT LAYOUT 596.1. Introduction 60

6.2. Site Selection Considerations 60

6.3. Plant layout 65

CHAPTER 7: ENVIRONMENTAL IMPACT ASSESSMENT 667.1. Gaseous Effluents 67

7.1.1. Particulate Dust 67

7.1.2. Carbon dioxide and monoxide 67

7.1.3. Nitrogen oxides 68

7.1.4. Sulfur oxides 68

7.1.5. Ammonia 68

7.1.6. Hydrogen sulfide 69

7.2. Gaseous Effluents Management 69

7.2.1. Calcinations of Limestone 69

7.2.2. Precipitation of Crude Sodium Bicarbonate 70

7.2.3. Filtration of the Bicarbonate 70

7.2.4. Conveying and Storage of Soda Ash 70

7.3. Liquid Effluents 71

7.3.1. Wastewater from Distillation 71

7.3.2. Wastewater from Brine Purification 72

7.4. Liquid Effluent Management 73

7.4.1. Liquid Effluent Treatments 73

7.4.1.1. Total Dispersion 74

7.4.1.2. Separation of the Suspended Solids and Liquid Dispersion 74

7.4.2. Liquid Effluent Discharge Management 75

7.5. Solid Effluents 76

7.6. Solid Materials Management 76

7.6.1. Limestone Fines 76

7.6.2. Grits from slaker 76

7.7. By-Products Recovery and Reuse 77


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7.7.1. Calcium Chloride 77

CHAPTER 8: SAFETY MEASURES 78

8.1. Plant Safety 79

8.2. General Plant Safety 79

8.3. Personal Safety 80

8.4. Safety Aspects of Equipments 81

8.4.1. Lime Kiln 81

8.4.2. NH3 Absorbing Unit 82

8.4.3. Carbonator Unit 82

8.4.4. NH3 Recovery Unit 82

8.4.5. Drier 83

8.4.6. Storage Vessels 84

8.4.6.1. Ammonia 84

8.4.6.2. Soda ash 84

8.4.6.3. Baking soda 84

8.4.6.4. Calcium Carbonate and Calcium Oxide 84

8.4.7. Pipelines 85

8.5. Safety Aspects of Chemical 85

8.5.1. Carbon Dioxide (CO )2 85

8.5.2. Ammonia (NH )3 86

8.5.3. Sodium Carbonate (Na CO )2 3 88

CHAPTER 9: MATERIAL BALANCE 91

9.1. Product specification 92

9.2. Components in Purified brine 92

9.3. Calculations for NH Absorption Unit3 93

9.4. Air Mixture 95

9.5. Gas Washing Tower with Purified Brine 96

9.6. Carbonator Unit 97

9.7. Filter 99

9.7.1. Calculation for residue solid 100

9.7.2. Calculation for permeate 100

9.8. Lime Kiln 101

9.9. Slaker of lime 103

9.10. Ammonia Recovery Unit 104


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9.11. Gas Cooler 107

9.12. Air Mixture (Before the Gas Cooler) 108

9.13. Dryer 109

9.14. Material Flow Sheet 111

CHAPTER 10: ENERGY BALANCE 112

10.1. Kiln Energy Balance 113

10.2. Energy Balance for Air Preheated 115

10.3. Calcinations of Crude Bicarbonate 116

10.4. CaCO3 Preheated 119

10.5. Air Mixer Energy Balance 120

10.6. Heat Balance for Gas Cooler 122

10.7. Slaking of Lime 123

10.8. Recovery of Ammonia Column Energy Balance 126

10.8.1. Find Outlet Temperature of the Cool Gas 127

10.8.2. Fine Quantity of Steam Consumption 128

10.9. Carbonation of Ammoniated Brine Column 130

CHAPTER 11: CONCLUSION 133

REFERENCE 135

CD CONTENTS

Excel Spreadsheets

Soft Copy Of Report


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Table & Figure

Table2.1: Market specifications of dense soda ash 7

Table2.2 : Worldwide capacity of soda ash manufacture 11

Table 2.3: Natural soda minerals occurred worldwide 16

Table 2.4: products of Trona 17

Table 4.1 a comparison of the Solvey and dual processes 40

Table5.1: Raw and purified brines (typical composition ranges) 51

Table 5.2: Typical compositions for coke to the lime kiln 52

Table 5.3: Soda ash process major Input/output levels 56

Table 7.1: Rough concentrations of the waste water from the distillation column 71

Table 7.2: Typical concentration wastewater from brine purification 72

Table 9.1- Soda ash specification 92

Table 9.2- Purified brine specification 92

Table 9.3- Residue solid composition 99

Table 10.1- a,b,c constant 113

Table 10.2- kiln inlet enthalpy 114

Table 10.3- kiln outlet enthalpy 114

Table 10.4- Air enthalpy change 115

Table 10.5- CaO enthalpy change 116

Table 10.6- flue gas enthalpy change 119

Table 10.7- Soda ash specification 123

Table 10.8- a, b, c constant for CaO 124

Figure 2.1: Distribution of soda ash by end use 7

Figure 2.2: Flow diagram of monohydrate process 18


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Figure2.3: Flow diagram of sesquicarbonate process 19

Figure 2.4: Flow diagram of alkali extraction process 21

Figure 3.1: Soda ash imports (2006) 25

Figure 3.2: Variation in soda ash imports 26

Figure5.1: Block diagram of the soda ash production plant 42

Figure5.2: Vertical shaft kiln for lime stone 46

Figure5.3: Process flow diagram 57

Figure5.4: P&I diagram

Figure 6.1- Mineral Map of Sri Lanka 63

Figure 6.2- Geographical map of proposed land 64

Figure 6.3- Plant layout 65

Figure 9.1- NH3 Absorption Unit 93

Figure 9.2- Air mixture before NH3 Absorption Unit 95

Figure 9.3- Gas washing tower with purified brine 96

Figure 9.4- Carbonator Unit 97

Figure 9.5- Filter 99

Figure 9.6- Lime Kiln 101

Figure 9.7- Slaker of lime 103

Figure 9.8- Ammonia Recovery Unit 104

Figure 9.9- Gas Cooler 107

Figure 9.10- Air mixture before gas cooler 108

Figure 9.11- Dryer 109

Figure 10.1- kiln 113

Figure 10.2- Air preheated 115

Figure 10.3- Dryer 117

Figure 10.4- Cyclone 119

Figure 10.5- Air mixture before gas cooler 120


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Figure 10.6- Gas cooler 122

Figure 10.7- Slaker 124

Figure 10.8- NH3 Recovery column 126

Figure 10.9- Carbonation column 130


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Chapter 1 INTRODUCTION

CHAPTER 01

1

INTRODUCTION

Sodium carbonate or soda ash is used in many

process industries such as in glass

manufacturing, Detergents & soaps, Metals and

mining, Paper and pulp and Textiles industries.

Raw materials for the manufacturing of sodium

carbonate are readily available and inexpensive.

Raw materials for the Sodium carbonate can be

obtained from sea water and lime stone mines

exist in number of places in the country……


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In developed areas of the world mainly in the western European countries and in North

America the annual dollar value of industrial mineral production has surpassed that for metals and

continues to grow rapidly. This is due to the fact of high income levels per capita consumption of

industrial mineral products in developed Countries exceeds that in developing countries. While in

developed countries industrial minerals and rocks provide inputs in many industrial processes, in some

developing countries with little industrial infrastructure significant portions of their foreign exchange

derive from exports of industrial minerals like Sri Lanka. Thus, industrial minerals are of great

economic value to developed and developing economies alike.

When we consider the Sri Lankan perspective as one of the developing countries the scenario

mentioned above applies without much deviation. Sri Lanka is a country which is rich in minerals and

natural resources, but these have not been utilized to an extent where they will contribute to the

country production and hence to its development. Sri Lanka as a county can capitalize on its exports if

it were to manufacture value added products from the existing resources instead of an economy based

on export of raw materials to industries in other countries.

Soda ash, the common name for sodium carbonate (Na2CO3), has significant economic

importance because of its applications in manufacturing glass, chemicals, detergents metals and

mining, paper and pulp, textiles industries and many other products. There are many evidences to show

that people have been using soda ash extracted from earth in crude form, in glass manufacturing

industries since ancient times. But the production of soda ash as an industry itself, emerged only

during the late 18th century.

Raw materials for the manufacturing of sodium carbonate are readily available and

inexpensive. Main raw materials can be obtained from sea water and lime stone mines exist in number

of places in Sri Lanka. So the purpose of our final year comprehensive design project is production of

sodium carbonate from brine and lime stone. The comprehensive design project is done as per the

requirement for the award of the B.Sc. (Honors) Engineering degree.

The literature survey that was conducted as part of the project included a thorough study on

several soda ash consuming and lime stone consuming industries in Sri Lanka. Since the Holcim

Cement plant in Palavi will have a considerable amount of relation to the proposed plant, as explained

in later chapters a brief study on its operations was also carried out.

The results of the design project for the commercial production of soda ash are presented. The

project has been performed in two stages. The first part concerns the feasibility of the project, literaturesurvey and the second part presents the detailed material and energy balances.


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From the investigation into project feasibility, it is proposed to construct a plant using the

Solvay process for the production of soda ash and will deliver 50 tons per day of 99.5(wt) Na 2CO3. It

is envisaged that this soda ash production facility will be located in Karadipuval near Puttalam. The

process has been tailor-made and designed to utilize limestone available locally at the North-Western

area of the country. Saturated brine from the adjacent lagoon is the other raw material utilized for the

proposed soda ash plant. Coke for the combustion of limestone in order to produce CO2 for the process

will have to be imported. It is hoped that this project makes a contribution to further the cause of

national development by provision of a viable, cost-effective, and environmental friendly solution.


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Chapter 2 LITRETURE SURVEY

CHAPTER 02

4

LITRETURE SURVEY

Soda ash has a number of diversified uses that touch

our lives every day. Glass manufacturing is the

largest application for soda ash whether it is in the

production of containers, fiberglass insulation, or flat

glass for the housing, commercial building etc.

As environmental concerns grow, demand increasesfor soda ash used in the removal of sulfur dioxide and

hydrochloric acid from stack gases. Chemical

producers use soda ash as an intermediate to

manufacture products that sweeten soft drinks,

relieve physical discomfort and improve foods and

toiletries, Household detergents and paper products

are a few other common examples of readily

identifiable products using soda ash………


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2.1 General Information

2.1.1 Other Names for Sodium Carbonate

Soda ash

Carbonate acid.

Disodium salt

Dry alkali

Molecular formula:

Na2CO3

2.1.2 Physical Properties of Sodium Carbonate

Specific Gravity : 2.53

Solubility in water(22°C) : 22g/100ml

Melting Point : 851.0°C

Boiling Point : Decomposes before melting

pH (1% aq. solution.) : 11.5

Sodium carbonate is an odorless, opaque white, crystalline or granular solid. It is soluble in

water and insoluble in alcohol, acetone, and ether. Sodium carbonate reacts exothermically with strong

acids evolving carbon dioxide. It corrodes aluminium, lead and iron.

2.1.3 Hydrates of Sodium Carbonate

The three known hydrates exist in addition to anhydrous sodium carbonate.

Sodium carbonate monohydrate ( Na2CO3.H2O )

This contains 85.48 % Na2CO3 and 14.52 % water of crystallization. It separates as small

crystals from saturated aqueous solutions above 35.4 °C, or it may be formed simply by wetting soda

ash with the calculated quantity of water at or above this temperature. It loses water on heating, and its

solubility decreases slightly with increasing temperature. In contact with its saturated solution it is

converted to Na2CO3 at 109 °C.


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Sodium carbonate heptahydrate ( Na2CO3.7H2O ),

This contains 45.7 % Na2CO3 and 54.3 % water of crystallization. It is of no commercial

interest because of its narrow range of stability, which extends from 32 °C to 35.4 °C.

Sodium carbonate decahydrate ( Na2CO3.10H2O ),

Commonly called sal soda or washing soda which usually forms large transparent crystals

containing 37.06 % Na2CO3 and 62.94 % water. It may be crystallized from saturated aqueous

solutions below 32.0 °C and above -2.1°C or by wetting soda ash with the calculated quantity of water

in this temperature range. The crystals readily effloresce in dry air, forming a residue of lower

hydrates, principally the monohydrate.

2.1.4 Chemical Properties of Sodium Carbonate

Sodium carbonate is hygroscopic. In air at 96 % R.H. (relative humidity) its weight can

increase by 1.5 % within 30 minutes. If sodium carbonate is stored under moist conditions, its

alkalinity decreases due to absorption of moisture and carbon dioxide from the atmosphere. Water

vapor reacts with sodium carbonate above 400 °C to form sodium hydroxide and carbon dioxide.

Sodium carbonate is readily soluble in water and the resulting solutions are alkaline, as expected a salt

formed from a strong base and weak acid. At 25 °C the pH of 1, 5 and 10 wt % solutions are 11.37,

11.58 and 11.70 respectively. Sodium carbonate reacts exothermically with chlorine above 150 °C to

form NaCl, CO2, O2 and NaClO4.

2.1.5 Grades and Specification of the Soda Ash

Soda ash is produced in two principal grades, known as light soda ash and dense soda ash.

These grades differ only in physical characteristics such as bulk density and size and shape of

particles, which influence flow characteristics and angle of repose. Dense soda ash has a bulk density

of 950 to 1100 kg/m3, may command a slightly higher price than the light variety, and is preferred for

glass manufacture because the lighter variety leads to frothing in the glass melt. Light soda ash having

a bulk density at 520 to 600 kg/m3, is the normal production item direct from the calcining furnace and

is preferred by the chemical and detergent industries. Other physical properties, as well as chemical

properties and properties of solutions, are common to both grades of soda ash.

All commercial grades are chemically similar. As density differences are the main distinguishing

feature, Table 2.1 shows the typical market specifications of dense soda ash.


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Chemical composition

Sodium Carbonate (Na2CO3) ≥ 99.8 %

Sodium Oxide (Na2O) ≥ 58.4 %

Sodium Sulfate (Na2SO4) ≤ 0.10 %

Sodium Chlorite (NaCl) ≤ 0.03 %

Iron (Fe) ≤ 0.0005% ( 5 ppm)

Bulk density (0.96-1.04 g/cm3)

Particle size 75 micron - 850 micron

Table2.1: Market specifications of dense soda ash

2.2 Uses of Na2CO3 in Industrial Sectors

Figure 2.1: Distribution of soda ash by end use

The distribution of soda ash by end use in 2007 was glass, 49%; chemicals, 27%; soap and

detergents, 10%; distributors, 5%; miscellaneous uses, 4%; flue gas desulfurization and pulp and

paper, 2% each; and water treatment, 1%.

2.2.1 Glass Industry

Soda ash is used in the manufacturing of flat and container glass. When mixed in proportion

with sand and calcium carbonate, heated to the right temperature and then cooled quickly, the end

result will be a glass that has an excellent level of durability and clarity. Na2CO3 as a network

modifier or fluxing agent, it allows lowering the melting temperature of sand and therefore reduces the

energy consumption.

7

http://www.wisegeek.com/what-is-calcium.htmhttp://www.wisegeek.com/what-is-calcium.htm


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Soda ash reduces the viscosity and acts as a fluxing agent in glass melting [soda-lime glass (flat

and container glass), fiber-glass, specialty glass (e.g. borosilicate glass)].

2.2.2 Detergent Industry

Soda ash is used in a large number of prepared domestic products: soaps, scouring powders,

soaking and washing powders containing varying proportions of sodium carbonate, where the soda ash

acts primarily as a builder or water softener. The addition of the soda ash prevents hard water from

bonding with the detergent, allowing for a more even distribution of the cleaning agent during the

washing cycle. In addition, soda ash has demonstrated an ability to help remove alcohol and grease

stains from clothing.

Sodium carbonate is a major raw material in the manufacture of sodium phosphates and sodium

silicates which are important components of domestic and industrial cleaners. Sodium carbonate is also

added to these detergents to produce formulations for heavy duty laundering and other specialized

detergents manufacture. Sodium carbonate may also be used for neutralizing fatty acids in the

production of soap.

2.2.3 Metals and Mining

Sodium carbonate is used for the production of metals in both the refining and smelting stages.

It is often used for producing a metal carbonate which can later be converted to the oxide prior to

smelting.

2.2.4 Steel Industry

Soda ash is used as a flux, a desulfurizer, dephosphorizer and denitrider. Aqueous soda ash

solutions are used to remove sulfur dioxide from combustion gases in steel desulfurization, flue gas

desulfurization (FGD) systems, forming sodium sulfite and sodium bicarbonate.

Na2CO3 + SO2 Na2SO3 + CO2

CO2 + Na2CO3 + H2O 2NaHCO3

2Na2CO3 + SO2 + H2O Na2SO3 + 2NaHCO3

8


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2.2.5 Paper and Pulp

Sodium carbonate solution is used for the production of sodium sulphite or bisulphite for the

manufacture of paper pulp by various sulphite processes.

2.2.6 Textiles

Sodium carbonate is widely used in the preparation of fibers and textiles. In wool processing it

is used during scouring and carbonizing to remove grease and dirt from wool. It is also used as a

neutralizer after treatment with acids.

2.2.7 Non-ferrous metallurgy industry

Treatment of uranium ores.

Oxidizing calcination of chrome ore.

Lead recycling from discarded batteries.

Recycling of zinc, aluminium.

2.2.8 Chemical industry

Soda ash is used in a large number of chemical reactions to produce organic or inorganic

compounds used in very different applications. It is used to manufacture many sodium-base inorganic

chemicals, including sodium bicarbonate, sodium chromates, sodium phosphates, and sodium silicates.

2.2.9 Other Applications

Production of various chemical fertilizers

Production of artificial sodium bentonites or activated bentonites

Manufacture of synthetic detergents

Organic and inorganic coloring industry

enameling industry

Petroleum industry

Fats, glue and gelatine industry, etc.


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2.3 Uses of NaHCO3 in Industrial Sectors

Sodium bicarbonate can also be manufactured by Solvay process.

Animal feeds to balance their diets to compensate for seasonal variations and meet specific

biological and rearing needs

Paper industry for paper sizing

Plastic foaming

Water treatment

Leather treatment

Flue gas treatment, especially in incinerators

Detergent and cleaning products such as washing powders and liquids, dishwashing products,

etc…

Drilling mud to improve fluidity

Fire extinguisher powder

Human food products and domestic uses: baking soda, effervescent drinks, toothpaste, fruit

cleaning, personal hygiene, etc.

Pharmaceutical applications: effervescent tablets, etc.

2.4 History of the Production

Before the advent of industrial processes, sodium carbonate, often-called soda ash, came

from natural sources, either vegetable or mineral. Soda made from ashes of certain plants or seaweed

has been known since antiquity.

At the end of the 18th century, available production was far below the growing demand due to

the soap and glass market. The French Academy of Science offered an award for the invention of a

practical process to manufacture soda ash. Nicolas Leblanc proposed a process starting from

common salt and obtained a patent in 1791.

The so-called Leblanc or black ash process was developed in the period 1825 till 1890. The

major drawback of this process was its environmental impact with the emission of large quantities of

HCl gas and the production of calcium sulfide solid waste which not only lost valuable sulfur but also produced poisonous gases. In 1861, Ernest Solvay rediscovered and perfected the process based

on common salt, limestone and ammonia.


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Competition between both processes lasted many years, but relative simplicity, reduced

operating costs and, above all, reduced environmental impact of the Solvay process ensured its

success. From 1885 on, Leblanc production took a downward curve as did soda ash price and by the

First World War, Leblanc soda ash production practically disappeared. Since then, the only production

process used in Western Europe as well as in main part of the world is the Solvay process.

In the meantime and mainly since the twenties, several deposits of minerals containing

sodium carbonate or bicarbonate have been discovered. Nevertheless the ore purity and the location of

these deposits, as well as the mining conditions of these minerals, have limited the effective number of

plants put into operation.

Worldwide capacity of soda ash manufacture

Table2.2 Worldwide capacity of soda ash manufacture

11


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2.5 Overview about Type of Production

Geographical location and site characteristics such as environmental matters, specific energy

resources, distribution methods, and trade barriers are key elements in a selection of processing

method. Soda ash is readily produced from either natural deposits or trona or by synthetic pathways.

Soda ash production methods are given below in historical sequence.

Le Blanc Process (synthetic soda ash)

Solvey Process (synthetic soda ash)

Dual and NA Processes (synthetic soda ash)

Monohydrate Process

Sesquicarbonate Process

Carbonation Process

Alkali Extraction Process

2.5.1 Le Blanc process

This process was invented by Nicolas Le Blanc, a French man, who in 1775, among several

others submitted an outline of a process for making soda ash from common salt, in response to an offer

of reward by the French academy in Paris. Le Blanc proposal was accepted and workable on a

commercial scale.

Reactions

2NaCl + H2SO Na2SO4 + 2HCL

4C + NaSO4 NaS + 4CO

Na2S + CaCO3 Na2CO3 + CaS

A mixture of equivalent quantities of salt and concentrated sulphuric acid is heated in cast iron

salt cake furnance. Hydrochloric acid gas is given off and sodium hydrogen sulphate is formed. The

gas is dissolved in water and the mixture is raked and transferred to the muffle bed reverbratory

furnance where it is subjected to stronger heat. Here sodium sulphate called salt cake is formed.

The cake is broken, mixed with coke and limestone and charged into black ash furnace. The

mass is heated and a porous grey mass know as black ash is withdrawn.

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The black ash is cursed and leached with water in the absence of air in a series of tanks. The

extract containing sodium carbonate, sodium hydroxide and many other impurities, is sprayed from the

top of a tower counter current to the flow of hot gases from the black-ash furnace.

This converts sodium hydroxide, aluminate, silicate, cyanate to sodium carbonate. The liquor is

concentrated in open pans until the solution is concentrated in open pans until the solution is

concentrated enough to precipitate sodium carbonate on cooling.

The product is calcined to get crude soda ash which is purified by recrystallisation. The liquor

remaining after removal of first crop of soda crystals is purified to remove iron and causticised with

lime to produce caustic soda. The mud remaining in the leaching tanks containing calcium sulphide is

suspended in water and lime kiln gas is passed through it. The following reaction occurs.

CaS + H2O + CO2 CaCO3 + H2S

The lean gas containing hydrogen sulphide is passed through another tank containing

suspension of calcium sulphide.

CaS + H2S Ca(SH)2

This solution is again treated with lime kiln gas liberating a gas rich in hydrogen sulphide.

Ca(SH)2 + CO2 + H2O CaCO3 + 2H2S

The hydrogen sulphide is burnt in limited supply of air in a special furnace in presence of

hydrated iron oxide as a catalyst to obtain sulphur.

H2S + 1/2O2 H2O + S

This sulphur is sublimed and collected.The hydrochloric acid produced by the Leblanc process

was a major source of air pollution, and the calcium sulfide byproduct also presented waste disposal

issues. However, it remained the major production method for sodium carbonate until the late 1880s.

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14

2.5.2 Solvay Process

In 1861, the Belgian industrial chemist Ernest Solvay developed a method to convert sodium

chloride to sodium carbonate using ammonia. The Solvay process centered on a large hollow tower. At

the bottom, calcium carbonate (limestone) was heated to release carbon dioxide:

CaCO3 → CaO + CO2

At the top, a concentrated solution of sodium chloride and ammonia entered the tower. As the

carbon dioxide bubbled up through it, sodium bicarbonate precipitated:

NaCl + NH3 + CO2 + H2O → NaHCO3 + NH4Cl

The sodium bicarbonate was then converted to sodium carbonate by heating it, releasing water

and carbon dioxide:

2 NaHCO3 → Na2CO3 + H2O + CO2

Meanwhile, the ammonia was regenerated from the ammonium chloride byproduct by treating

it with the lime (calcium hydroxide) left over from carbon dioxide generation:

CaO + H2O → Ca(OH)2

Ca(OH)2 + 2 NH4Cl → CaCl2 + 2 NH3 + 2 H2O

Because the Solvay process recycled its ammonia, it consumed only brine and limestone, and

had calcium chloride as its only waste product. This made it substantially more economical than the

Leblanc process, and it soon came to dominate world sodium carbonate production.


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15

2.5.3 Hou's Process

This process is developed by a Chinese chemist Hou Debang in 1930s. It is the same as the

Solvay process in the first few steps. But, instead of treating the remaining solution with lime, carbon

dioxide and ammonia is pumped into the solution, and sodium chloride is added until it is saturated at

40 °C. Then the solution is cooled down to 10 °C. Ammonium chloride precipitates and is removed by

filtration, the solution is recycled to produce more sodium bicarbonate. Hou's Process eliminates the

production of calcium chloride and the byproduct ammonium chloride can be used as a fertilizer.

2.5.4 Dual process

In this process ammonium chloride is produced as a co product in equivalent quantities anddiffers from conventional, Solvay process and it does not recycle ammonia.

The mother liquor from the carbonating system, containing ammonium chloride, unreacted salt

and traces of carbonate is ammoniated in ammonia absorber. The ammoniated mother liquor is passed

through a bed of salt in a salt dissolver. Exit liquor from the dissolver, saturated with salt, is gradually

cooled from 400 C to 10

0 C by evaporation under vacuum to separate ammonium chloride. The slurry

containing ammonium chloride is centrifuged and dried. The product is 98% pure and is marked as

ammonium chloride fertilizer with nitrogen content of 25%.The mother liquor obtained after the separation of ammonium chloride crystals is recycled to

the carbonation vessels placed in series. Carbon dioxide obtained from ammonia plant and the calciner

section of soda ash plant is injected in the carbonation vessels. There is provision of cooling coils in

the lower carbonation vessels. Sodium bicarbonate is formed. The growth of crystals, of sodium

bicarbonate is controlled by the supply of cooling water to cooling water to cooling coils in

carbonation vessels. Sodium bicarbonate is thickened in a thickener and centrifuged. The sodium bi

carbonate is calcined to soda ash.

2.6 Sodium Carbonate Minerals

Whereas the production of sodium carbonate from the ashes of plants in salty soil near the sea

is only of historical interest, extraction from soda-containing minerals, especially trona, is of

increasing importance. The natural soda minerals occurred in the world is given in the following table.


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16

Types of Natural soda minerals occurred worldwide

Mineral Chemical Name Chemical Composition % Na2CO3

content

Trona Natural sodium

sesquicarbonate

Na2CO3.NaHCO3.2H2O 70.3

Nahcolite Natural sodium bicarbonate NaHCO3 63.1

Bredeyit Natural sodium bicarbonate 47.1

Gaylusitte Natural sodium bicarbonate Na2CO3.CaCO3.5H2O 35.8

Pirrsonite Natural sodium bicarbonate Na2CO3.CaCO3.2H2O 43.8

Thermonatrite Sodium carbonate

monohydrate

Na2CO3.H2O 85.5

Natron Sodium carbonate

decahydrate

Na2CO3.10H2O 37.1

Burkeit - Na2CO3.2Na2SO4 27.2

Dawsonit - NaAl(CO3)(OH)2

35.8

Hankcite - Na2CO3.9Na2SO4.KCl 13.5

Sortite - Na2CO3.2CaCO3 34.6

Table 2.3: Natural soda minerals occurred worldwide

Only Trona and Nahcolite are the minerals those commercial interest. These Na2CO3

containing minerals were formed from the original rock by the erosive action of, air, water, heat, and

pressure, followed by chemical changes caused by the action of atmospheric carbon dioxide. The

carbonate containing salts formed were leached by water and then concentrated and crystallized by

evaporation.

2.6.1 Trona Based Process

The production of sodium carbonate from the ashes of plants in salty soil near the sea is only of

historical interest, extraction from soda-containing minerals, is of increasing importance. Trona,

hydrated sodium bicarbonate carbonate (Na2CO3.NaHCO3.2H2O), is mined in several areas of the

world.


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17

This underground dry Trona processing consists in several steps:

First Trona has to be mined by the room and pillar or long wall method mechanically.

As Trona is an impure sodium sesquicarbonate mineral (Na2CO

3·NaHCO

3·2H

2O), it has to be

calcined to produce a soda ash still containing all the impurities from the ore.

Next, calcined Trona is dissolved, the solution is settled and filtered to remove impurities

(insoluble and organics), and the purified liquor is sent to evaporators where sodium monohydrate

crystals precipitate.

The monohydrate slurry is concentrated in centrifuges before drying and transformation into dense

soda ash.

Deposits from Trona lakes and solution mined Trona are processed as follows:

Dissolving Trona in wells

Carbonation of the solution in order to precipitate sodium bicarbonate filtration of the slurry and

Calcination of the bicarbonate to get light soda ash , recycling of the carbon dioxide to the

carbonation

Light soda ash transformation into dense by the monohydrate method

Carbon dioxide make-up produced by burner off-gas enrichment

2.6.1.1 Trona Products

Various Forms of Sodium

Carbonate

Formula

Anhydrous sodium carbonate Na2CO3

Sodium carbonate monohydrate Na2CO3. H2O

Sodium carbonate heptahydrate Na2CO3 .7H2O

Sodium carbonate decahydrate Na2CO3 .10H2O

Caustic Soda ( NaOH )

Sodium Bicarbonate ( NaHCO3)

Sodium Derivatives

Table 2.4: products of Trona


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2.6.1.2 Monohydrate Process

Soda ash is generally produced from trona by monohydrate process that produces only dense

soda ash. The first FMC Wyoming Corporation plant using this process went into operation in late

1972. In this process, the trona ore is first converted to crude soda ash by calcination and all

subsequent operations are performed on the resulting carbonate solution, as given in following figure.

Figure 2.2: Flow diagram of monohydrate process

Crushed Trona is calcined in a rotary kiln to dissociate the ore and drive off the carbon dioxide

and water by the following reaction:

2 (Na2CO

3. NaHCO

3.2H

2O)

(s). 3 Na

2CO

3 (s)

+ 5 H2O + CO

2

The calcined material is combined with water to dissolve the soda ash and to allow separating

and discarding of the insoluble material such as shale or shortite by settling and /or filtration. The

resulting clear liquid is concentrated as necessary by triple-effect evaporators, and the dissolved soda

ash precipitates as crystals of sodium carbonate monohydrate, Na 2CO3.H2O. Other dissolved

impurities, such as sodium chloride or sodium sulfate, remain in solution.

The crystals and liquor are separated by centrifugation. The sodium carbonate monohydrate

crystals are calcined a second time to remove water of crystallization. The resultant finished product is

cooled, screened.

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2.6.1.3 Sesquicarbonate Process

An alternate method of soda ash production from trona is the sesquicarbonate process. This is

the original process, developed by FMC Wyoming Corporation and put in operation in 1953, for

producing pure soda ash from Wyoming trona.

Trona ore is leached in recycled mother liquor at as high a temperature as possible to maximize

the amount dissolved. The solution is then clarified, filtered and sent to a series of evaporative cooling

crystallizers where sodium sesquicarbonate (Na2CO3.NaHCO3.2H2O) is crystallized. Carbon is added

to the filters to control any crystal modifying organics. The purified sesquicarbonate crystals may be

calcined to produce a light soda ash product. Simplified flow diagram of sesquicarbonate process is

shown in following figure.

The mother liquor is recycled to the dissolvers. In a variation of the process, trona ore is

dissolved in hot water and the centrate is returned to the evaporator crystallizer (Haynes, 1997). This produced soda is the light soda ash. Densities similar to the monohydrate soda ash may be achieved by

subsequently heating the material to about 350 °C. Alternatively, soda ash can be converted to the

monohydrate and then calcined.

Figure2.3: Flow diagram of sesquicarbonate process

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2.6.1.4 Alkali Extraction Process

Alkali extraction process is mainly to dissolve crude trona in an aqueous sodium hydroxide

solution. In this process, trona is dissolved in an aqueous sodium hydroxide to obtain pregnant sodium

carbonate solution. This method is generally used for bicarbonate content that dissolves to be an

incongruent consisted in trona. The diluted solution has a composition of 2-7 % caustic soda.

Dissolution reaction is given as follows:

Na2CO3.NaHCO3.2H2O + NaOH 2 Na2CO3 + 3 H2O

The solution at 30 °C was filtered and the pregnant carbonate solution is heated, sufficient

water is evaporated to form slurry of sodium carbonate monohydrate crystals and aqueous sodium

carbonate. The slurry was filtered and the mother liquor was recycled to dissolve raw mineral. Theregeneration was done by adding sodium hydroxide to the mother liquor.

The monohydrate crystals were dried and calcined. The most important parameters in alkaline

extraction process are; the dissolution temperature, concentration of sodium hydroxide and evaporative

crystallization temperature. The appropriate temperatures for the dissolution and evaporative

crystallization are 30 °C and 100 °C respectively. The flow diagram of alkali extraction process is

shown in following figure.

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Figure 2.4: Flow diagram of alkali extraction process

In a trona bed, the effect of water on the solubility of sodium carbonate will decrease due to the

precipitated bicarbonate. In the conventional mining technique, bicarbonate can be converted to

carbonate with a pre-calcination stage. The problem associated with the presence of sodium

bicarbonate in trona deposits can be solved by applying of sodium hydroxide solution. The required

amount of sodium hydroxide is the stochiometric amount that is necessary to convert all of the

bicarbonate to carbonate. The aqueous sodium hydroxide solvent preferably contains 1-15 wt% NaOH.

Using an excess of sodium hydroxide causes unreacted NaOH to remain in the solution and this effect

decreases the solubility of sodium carbonate.

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22

2.6.2 Nahcolite based process

A Nahcolite deposit has been found in several places in the world.

Nahcolite is processed as follows:

By solution mining (wells, with injection of hot mother liquor returned from the surface facilities),

Nahcolite is separated.

As nahcolite is an impure sodium bicarbonate mineral (NaHCO3), it must be treated.

The hot solution is decarbonated by heating. Then the solution is sent to settling and filtration.

Next, the purified liquor is sent to evaporators where sodium monohydrate precipitates.

The slurry is concentrated by centrifugation and the monohydrate crystals transformed to soda ash

by drying. The mother liquor is sent back to the solution mining

2.7 International Scenario

The present global capacity of soda ash is 37.0 million tones per annum and the long term

growth rate is 1.5-2%.

The major technology suppliers for the soda ash plant are:

Solvay and Cie SA, Belgium

AKZO-ZOUT Chemie BV, Netherlands

Asahi Chemical Industry, Japan

Polimex Cheepok, Poland

Technology Exports Divn, DSTA, China

The basic process for the manufacturer of soda ash has not undergone much change since last

130 years. Developments however are taking place in the following areas:

Process technology

Operation technology

Improvement of quality

New product from waste


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2.8 Structure and Status of Indian Industry

The manufacture of soda ash in India started in 1932 at in Gujarat with an installed capacity of

50 tons per day.

This was followed by the entry of another Chemicals manufacturing plant at Mithapur in

Gujarat in 1894 with an installed capacity of 100 tons per day. In a span of 50 years it has grown to be

the biggest soda ash unit in the country with daily capacity of 2000 tones.

In the same region in Gujarat, two more soda ash plants came up after-wards. First one was

commissioned in 1959 with a capacity of 200 tons per day which has been expanded to 800 tons per

day. Second one was commissioned in 1988 with a capacity of 1200 tons per day. All these four units

in Saurashtra in Gujarat are based on Solvay process.

Three units are operating on the modified Solvay process (Dual Process) in which ammonium

chloride is the co-product. The first plant based on this technology was set up in 1959 at Varansai, with

an installed capacity of 120 tons per day. The two other units operating on Dual process are at a

capacity of 200 tons per day. The present installed capacity of six soda ash manufacturing units is

17.09 lakh tones.


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Chapter 3 FEASIBILITY STUDY

CHAPTER 03

24

FEASIBILITY STUDY

The feasibility analysis is a preliminary study

undertaken to determine a project's viability or

the discipline of planning, organizing, and

managing resources to bring about the

successful completion of specific project goals

and objectives. The results of this study are used

to make a decision whether or not to proceed

with the project. In the case of the soda ash plant

an analysis of possible alternative solutions and

scenarios that has an impact on the proposed

was done and recommendations have been made

on the best alternative.


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25

3.1 Preliminary Study

As a preliminary study of the prospective soda ash plant a simple feasibility analysis has been

summarized in this chapter. The main objective of this feasibility is to explore the economical aspects

of the process and other concerns like environmental, technical, social issues that may arise as a result.

It can be said that the necessity of the plant is primarily based on final out come of the plant

and the market availability for its products. The bulk of the soda ash imported into the country is

primarily for the consumption of the glass industry. The main player in the present glass industry in Sri

Lanka is ‘Ceylon Glass’ with a daily consumption of almost 20 Metric Tones per day. A considerable

growth in the consumption of Soda ash can be seen within this single entity itself.

SODA ASH IMPORTS (2006)

Country QuantityKg

Value Rs.

Bulgaria 619000 17120020

China 975407 28721920

India - 9342

India 4089598 101802615

Iran 83284 2643973

Japan 1 4282

Kenya 792000 15948728

Malaysia 1 9510

Pakistan 100000 3496878Romania 440000 13901583

Singapore 725350 19914608

Taiwan 78 26244

Turkey 36000 960489

U.K. 469 824657

Ukraine 175000 3573407

Total 8,036,188 208958256

Avg price of 1kg of imported Na2CO3

(Rs) 26.00

Average consumption per day 22016.95342 kg

22.01695342 MT

Figure 3.1: Soda ash imports (2006)

When we consider the total soda consumption based on the amount imported to the country it can be

clearly seen from the above graph (figure 3.1)that an average of almost 40 MT (2008)is consumed

daily. Also a considerable increase in the amount demanded per year is depicted in the figure 3.2.

Therefore a daily production capacity of 50 MT on a continuous basis is justifiable.


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Variation of Soda ash imports

0

5

10

15

20

25

30

35

40

45

2004 2005 2006 2007 2008

year

M T / d a y

Figure 3.2: Variation in soda ash imports

The present average imported price per kg of soda ash is `23`1. The cost incurred for the

production of a single kg based on the raw material costs, maintenance and operation costs and other

overheads will be far less than the importing price because of the availability of CaCO3 deposits in Sri

Lanka at a considerable degree of purity, availability of skilled workers at considerably lower wage

rates and mainly due to the avoidance of cost for freight services. But the lower price in itself doesn’t

justify the high capital cost that has to be incurred for the implementation and construction of soda ash

plant based on the Solvay process. A further in-depth analysis with considerations of strength of export

market, pay back period, etc has to be taken into account.

26

When we consider the importing scenario there are considerable fluctuations in the demand for

soda ash and related products. It was noted that most of the soda ash imported to the country is in the

form of high dense soda ash. This is because high dense soda ash is one of the main raw materials of

the glass industry and most of the soda ash imported to the country is consumed by the same industry.

A main factor for the increased price of the imported soda ash in to the country is because of the fact

that different local companies import soda separately in small amounts and because of the cost

incurred for the freight services. Also as mentioned above the unstructured importing from various

suppliers and the unavailability of an agent to handle the soda import has led to higher prices. Another

factor that would lead to higher prices when importing is because of levies and taxes that has been

imposed on imported products and charges at the customs. Since soda is being imported to the country

at a higher price the related industries face restrictions in implementation and expansion because they

have a huge problem of

the market share because of the high final cost.


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27

The main raw materials for the production of soda ash from the Solvay process are Brine and

Calcium Carbonate. When we consider the availability of these raw materials in Sri Lanka, brine is

present in the form of sea water all around the country and Calcium Carbonate can be obtained from

sand stone or Dolomite reserves present throughout the country. Pure Miocene sand stone can be found

in the land strip stretching from Puttalam to the Jaffna peninsula. Dolomite reserves are present to the

middle of the country. Areas well known in this aspect is present in the Matale district. Also Calcium

Carbonate can be found in the form of coral reefs in various parts of the costal belt in Sri Lanka though

this is not an environmental friendly and feasible option. Also sea shells that is present in the costal

areas is a good form of Calcium Carbonate but this is not a viable and secure raw material source for a

soda ash production facility of the proposed scale. Therefore it can be concluded with confidence that

a local soda ash production plant will be able to get the essential raw materials easily. Therefore based

on this preliminary feasibility analysis it can be said that building a soda ash plant in Sri Lanka would be profitable.

In addition to the facts highlighted and discussed above, the feasibility has been further divided

and analyzed as economical, legal and administrative; market feasibility as part of the initial

evaluations and technical, social and environmental feasibilities have been analyzed as a measure of

viability when work is in progress.

3.2 Economical Feasibility

• Impact on local industry- Soda ash is one of the most important raw materials for the

manufacturing as well as process industry. It can be used as a raw material for the production

of glass, polymers, etc. Also it is extensively used in the process industry as a raw material in

the production of various chemicals, fertilizers, etc. When soda ash is available locally at a

lower price and most importantly in form of a continuous, secure supply there would be a

considerable boom in the above mentioned industries. Also since the there would be

developments in industries that are in parallel with this industry. For example saturated brine is

required as a raw material in the Solvay process. Hence a salt production facility in the area can

be utilized to provide saturated brine.

• Impact on economy of area- As studied and evaluated under chapter 5 the location of the soda

ash plant is designated as Karadipuval site in Puttalam. The Holcim Lanka cement plant and itsquarry is located in the puttalam district. The Aruwakkaru Limestone Quarry site of Holcim

Lanka Ltd is used to extract limestone to produce cement in Palavi plant of Holcim Lanka (pvt)


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28

ltd. This is the only quarry in operation to extract limestone which is 150 km away from

capital city Colombo of Sri Lanka. Other than few industries the area presently can be

considered as remote or rural. With the establishment of the soda ash plant and the completion

of Norochcholai coal power plant the area will comprise of 3 main industries and would be

similar to an industrial zone. The Norochcholai coal power plant already has many

infrastructure developments which include the development of a port. The development of such

industries will lead to considerable development of the facilities, economy and availability of

jobs in the area.

• Reduction of Imports- When we consider in a macro scale there will be considerable amount

of savings when the production of Sri Lanka is increased. This in tern will benefit the country

as a whole because of increase in GDP, reduction of unemployment, drop of inflation, increase

of local currency.

• Opportunity for export- There are several industries that consumes soda ash as a raw

material. Also there is a high demand for soda ash in neighboring India and other south Asian

countries. Though India is one of the major producers of soda ash in the world it utilizes the

Dual purpose method to cater the fertilizer demand in the country and most of the plants aresited north of the country. Also the dual purpose method leads to higher cost for the soda ash

because NH3 used in the process is of high cost. Therefore there would be considerable market

for soda ash produced in Sri Lanka in the south Indian region. Also there would be

considerable demand for end products like glass that is made from soda ash throughout the

south Asian region.

• Increase of production- The availability of locally produced soda ash will lead to a boom in

the soda related industries. This would lead to the possibility of expanding local industries and

emerging of new ones. Such an increase of production, production capacity and availability of

raw materials would make Sri Lanka attractive to investors.

• Production costs- As mentioned earlier the availability of raw materials locally for the

production of soda ash in Sri Lanka itself will lead to reduction production cost. Also the

availability of skilled workers and manpower at a relatively lower wage rates comparative to

that of other soda ash producing European counterparts will lead to reduced cost. But it needs


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29

to be noted that the other overhead costs in Sri Lanka would be somewhat higher because of

high electricity tariffs and condition of infrastructure.

• Incentives and levies imposed on the industry- Presently there are various levies and taxes

imposed on imported goods. But Ceylon glass which is involved with importing most of the

soda ash into the country for its production activities has a considerable concession as part of

the agreement with the government when it was taken over by an Indian company. Even

though this is the case if soda ash is produced locally the government would impose taxes on

imported soda ash to promote the local producer.

• Government support- Since a soda ash production plant is a huge production facility and it

would be involved with providing jobs for considerable amount of people the government is

likely to act in favor of the local soda ash producer. Government support at a considerable

degree would be required because purchasing of land in the proposed area under Chapter 6,

establishment of infrastructure support, environmental impact mitigations, obtaining quarrying

rights for limestone, provision of security from terrorist threats etc would require government

intervention and support.

• Security- As discussed later in Chapter 5 the most suitable location for the proposed soda ash

plant is at Karadipuval in Puttalam. Though more pure Miocene Limestone deposits are

available in the Jaffna Peninsula, it will not be a likely option because of the terrorist activities

present in the area and the on-going war effort. When we consider the site at Puttalam a secure

security situation has been prevailing for several years. Also a tight security parameter

presently has been set in the area which would be further strengthened once the Norochcholai

coal power plant has been commissioned. Therefore it can be said that the security threat or

risk is minimum.

• Inflation and its impact- The present inflation rate of the country is very high. Therefore this

would negatively impact on the project at the construction and maintenance phases because

most of the equipment would have to be imported. But once the plant is running the soda

produced and sold locally would not be severely affected. But the competitive edge of soda ash

that is to be exported would be lost.


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30

• Regional impact- A major administrative and management issue that would affect the

functioning of the plant is the environmental concerns and waste management. When the plant

has necessary control measure in-place, which is used successfully in other parts of the world,

this threat can be avoided.

• Impact from other main industries in the area (Holcim) - An administrative issue that the

company involved will have to face is when obtaining quarrying rights to the limestone quarry.

At present Holcim Lanka is involved with quarrying activities at Aruwakkaru. Since this site

has already been reserved by the cement company obtaining quarrying rights and reserving of

limestone deposits would be necessary.

When we consider the economical evaluation as a whole after considering lagal and

administrative issues the implications are positive. But since this is a preliminary feasibility

analysis of the project in-depth cost and benefit analysis are not possible. But when viewing the

above facts and considering the economical parameters, it can be said with certainty that the

expected outcome would be positive.

3.3 Market Feasibility

• Market trends – Presently there is considerable market trend towards the development of soda

and salt related industries in Sri Lanka. This will result in a huge demand for soda ash which is

being used as raw material. Also there is tremendous potential for the development of the glass

industry. For instance Ceylon Glass moved from their conventional plant at Ratmalana and

built a new one at Horana to cater the increasing demand. Therefore it can be said with

confidence that there would be considerable demand for locally produced soda ash with the

expected boost in industry.

• Allowance for expansion- As mentioned in the economic feasibility and later on in the site

layout selection there is considerable potential for expansion. The present demand for soda ash

is about 40 MT/day. The proposed plant has a capacity of 50MT/day with an allowance of 10

MT/day. In the event of a huge increase in the market a new plant or an expansion of the plant

itself would be required. The land selected under the latter chapter of site selection has

allowance for such an expansion.


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31

• Sales generation- As highlighted above the current market price for soda ash is around Rs 25.

According to the present economic evaluation it can be said that a kg of soda ash can be

produced from a cost of around Rs 8 which means that the gross profit is considerably high.

• Pay back - As mentioned above the gross profit per kg of soda ash sold is high. Therefore it can

be said that the payback would be less event though a thorough evaluation with a detailed

financial statements would be required for in order to estimate the payback accurately.

• Sales and marketing concerns- At present there won’t be any marketing concerns because

there are no other players in this industry. The only competitor would be soda ash importers.

But there are no big importers that have specialized in this business, currently in Sri Lanka.

Also since the government is biased towards the development of the local industry there would

be restrictions on imports once the plant has commenced production. Also since the no of

consumers if Soda ash is less a highly costly marketing campaign would be meaningless.

• Distribution network – As mentioned above since the consumers of soda ash is less the ideal

distribution network would be a one-to-one system. For example when soda ash for the glass

company can be sold to the Ceylon glass (pvt) ltd directly without the involvement of

intermediates and complex sales networks. This would benefit the producer as well as the

consumer because of simplicity and high profitability.

3.4 Technical Feasibility

• Infrastructure requirement- The proposed plant with a capacity of 50 MT/day would require

considerable amount of infrastructure and utility processes. Normally Solvay process plants are

considered to be some of the biggest plants in the world. The plant would require a road

network, railroad or durable road to transport limestone from the quarry, uninterrupted

electricity, basic water supply and process water, etc. The producers would have to build the

internal road network as required. In the event of building a rail network for the transportation

of limestone from the quarry the company would require the assistance of the governments.

The case would-be the same if the plan to transport limestone from the quarry to the plant in

Lorries and vehicles because a road with reinforced layer would be required. The plant could

fulfill its power requirement by means of electricity from the National grid and power

generated from steam/cogeneration at the plant. The plant can fulfill its domestic water


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32

requirement from the National water supply lines. But the process would require extensive

amounts of process water. Since the use of treated and purified salt water for this purpose

would not be feasible the need will have to be met by water from dug wells or stream/river.

• Geological aspects- A process plant of this scale would require a strong foundation. Therefore

the stability of the bedrock on which the plant is sited, is of importance. The land of Puttalam

area consists of hard, moisture free soil. It has already been proved that the bedrock in the

Puttalam area is one of the best to locate process plants by the survey done for the

Norochcholai coal power plant. This is a positive aspect. But the soil in the area, especially in

places near the lagoon and the salt production plants the soil consist of salts which might be

harmful to the plant. By adopting necessary coatings on surfaces and having corrosion

allowances this problem can be solved.

• Availability of skilled workers and professionals for maintenance of plant- At present the

district of Puttalm doesn’t comprise of a considerable skilled and professional workforce.

Hence the human force requirement will have to be met by resident workers from other areas of

the country. But it is possible to obtain unskilled laborers from the area for the plant

construction activities and maintenance when the plant has been commissioned.

• Availability of construction companies- At present Sri Lankan Process development

companies doesn’t have the experience and capacity for the construction of a Solvay plant with

a daily capacity of 50MT. Hence the assistance of process plant construction companies abroad

with experience in similar construction activities will be required.

• Availability of expert consultancy firms- At present there are companies that have extensive

amounts of technical expertise regarding the Solvay process. Some of them are given below.

Solvay and Cie SA, Belgium

AKZO-ZOUT Chemie BV, Netherlands

Asahi Chemical Industry, Japan

Polimex Cheepok, Poland

The technical assistance of such a consultancy provider will be required to oversee the

construction activities and provide process consultancy when the plant has been commissioned.


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• Fabrication concerns- Presently Sri Lanka has the capacity for fabricating most of the process

vessels required for the plant. Other equipment that cannot be produced locally will have to be

imported or fabricated and shipped to Sri Lanka.

• Imported equipment transportation- The port that has been built at Norochcholai is to be

used as a transportation channel for the imported equipment of the Norochcholai Coal Power

Plant. The same port can be used when bringing Heavy process equipment or vessels for the

proposed soda ash plant.

3.5 Social Feasibility

• Social condition of people- The living standard of an average resident in the area is low. Most

of the population is farmers. The proposed plant will not have a huge impact on the residents of

the area since not much farming is done or vegetation is present in the chosen area. It cannot be

said that the plant will be involved to a great extent in uplifting the living standards of these

people, but there are certain direct and indirect means related to the activities of the plant

through which the local population can thrive and earn an extra income.

• Resettlement and rehabilitation- This will not be a problem because the land chosen is a

piece of bare land. Therefore no concern of this matter would be required. But in the event of

placing rail lines from the existing one from the Holcim factory to the quarry, acquiring of

certain land plots from the residents will be required. But even in this case resettlement or

rehabilitation will not be a concern because this project will not need land from a process of

nationalization.

• Social resistance- The construction of the plant will definitely have to face public pressure and

cultural resistance, as quite evident from other projects of this sort. The pressure would mainly

be based on environmental issues, pollution and waste disposal. These resistances can be

subdued to a certain degree by implementation of the best available pollution control

techniques and waste management principles and increasing public awareness regarding them.

This scenario as whole will not affect the decision of implementation of the plant.

• Health and safety concerns- As mentioned above with the implementation of the best

available practices and by designing process vessels according to standards the risk of a


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disaster occurring due to failure can be avoided. By having a good training programme in-place

and by recruiting skilled and experienced workers there would not be a risk of health and

safety. Then it would not be a concern in the feasibility concern.

• Employment- One of the positive implications of the plant on the surrounding community is

the increase in job opportunities. These jobs can be in the form direct or indirect means. For

instance with the start of construction activities of the plant many laborers (both skilled and

unskilled), will be recruited from the area. Once the plant is complete and has been

commissioned people across a diverse range will get job opportunities. In recruiting of

recruiting such people the priority will be given to the locals in the area because the company

will then not have to bear accommodation and transport costs. Also with the establishment of a

new plant various businesses would come into being, whose activities are not directly related to

the operation of the plant. For example many new shops and stores would be established by

external people to cater the needs of the employees, suppliers, etc. This would result in the

provision of employment as well as flow of money into the area. But on the plant’s perspective

relying on employees from the adjacent areas alone, will not be sufficient because the lack of

skilled workers and professionals in the area will affect the operations of the plant. Therefore

the company will have to provide transport and accommodation to a certain degree to attract

employees with the necessary traits from other parts of the country.

• Local industry- At present in the Puttalam district, there are industries and commercial entities

that will directly benefit from the proposed soda ash plant at Karadipuval. For instance the

heavily spread saltern industries in the area discharge the Mother Liquor from the tanks after

salt has crystallized. But since this mother liquor with saturated Sodium Chloride is a raw

material for the soda ash industry the salterns can earn an income from their effluent. Also the

Holcim cement factory can benefit immensely by leasing out their assets like the quarry, rail

carriages, kiln for hazardous waste disposal, etc. Also the jetty/port that is being built in the

area can benefit from the activities of the plant. Other than these industries small commercial

entities like suppliers, caterers, transporters, etc also will get a new market onto which they can

expand their business.


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Chapter 4 PROCESS SELECTION

CHAPTER 04

35

PROCESS SELECTION

The selection of an appropriate process is an

important decision, all the subsequent work

depends upon this choice. Although the selection

can be changed or modified at a latter stage, at

least before the plant is built, such a decision

results in a serious waste of time and

money……….


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4.1 Introduction

The stepping stone for the chemical revolution begun in Europe with the introduction of the

Leblanc process for the production of Soda by Leblanc in 1790. This industry used as raw materials,

salt, sulfur, limestone, saltpeter, coal, air, and water; its products were the alkalis, sodium carbonate

and sodium hydroxide. Cheap alkalis brought to the ordinary citizen those luxuries which had formerly

been enjoyed only by the rich and powerful: glass for bringing light into dark places, paper for

bringing the printed word into proletarian homes, and soap for bringing sanitation into cities oppressed

by filth and disease.

A highlight of the developments in the soda ash industry was witnessed when the Belgian

industrial chemist Ernest Solvay (in 1861), developed a method to convert sodium chloride to sodium

carbonate using ammonia. Other than the Leblanc and Solvay process there have been various

developments in the soda ash industry during the last 100 years. The processes that are present used for

the production of soda ash are given below.

Leblanc Process

Solvay Process

Dual Process

Akzo Dry Lime Process

New Ashai ( NA) Process

Akzo Zoul Chemie Method

Nepheline syenite process

Carbonation of caustic soda

Also Trona and nahcolite based process are used in different countries but this is not an option

in the Sri Lankan context because the island does not have soda ash reserves which can be mined and

processed under these methods to yield soda ash for consumption. In other words Trona and Nahcolite

processes are used for processing soda ash reserves to remove impurities within them. Also there are

some plants operating under the ‘Nepheline syenite process’ and ‘Carbonation of caustic soda’

method. But it is not possible to obtain soda ash of good quality from the Nepheline syenite process

and this would lead to additional cost for purification processes as demanded by soda ash consuming

industries. Also carbonization of caustic soda is not feasible for Sri Lanka at present because it is

dependent on imports to fulfill caustic soda requirements.


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4.2 Comparison of Solvay process with Others Methods of Production

As mentioned above in the introduction, Leblanc process was the industrial process for the

production of soda ash used throughout the 19th century. It involved two stages: Production of sodium

sulfate from sodium chloride, followed by reaction of the sodium sulfate with coal and calcium

carbonate to produce sodium carbonate. The Leblanc process was a batch process in which sodium

chloride was subjected to a series of treatments, eventually producing sodium carbonate.It is also

noteworthy that in addition to valuable alkalis, the Leblanc process produced two waste products,

hydrogen chloride and calcium sulfide. Acidic hydrogen chloride gas was sent up the chimney, after

which it decimated vegetation in the vicinity of an alkali works. Insoluble calcium sulfide was

conveniently disposed of in heaps where the vegetation used to be. Unfortunately, when calcium

sulfide reacts with rain water it farts out noxious hydrogen sulfide.

Hence alkali manufacturers based on Leblanc process became popular targets for lawsuits and

government regulations. The British Alkali Act of 1863, for example, required the absorption of 95%

of the hydrogen chloride produced by the salt cake furnace. This was easily accomplished, hydrogen

chloride being quite soluble in water; the waste gas was sent up through a stone tower filled with coke;

water dribbling down through the tower absorbed the hydrogen chloride, producing aqueous

hydrochloric acid.

In addition to hydrogen chloride which can be presently considered as valuable product own its

own account and after Henry Deacon in1868 introduced a process for turning waste hydrogen chloride

into bleaching powder, which could be utilized in paper and textiles industry, calcium sulfide produced

is a problem for soda manufacturers using the Leblanc process. This (calcium sulfide produced)

became a persistent problem owing to the twin problems of stinking heaps of tank waste, and the loss

of valuable sulfur. It is noteworthy at this point that pure source of Sulfur is not present in Sri Lanka.

An alternative to sulfur is sulfur dioxide which was obtained during the latter stages of the soda

industry from roasted from pyrites, which alternatively would have to be imported to Sri Lanka. Also

whatever the source may be, it will eventually end up as calcium sulfide waste. The only positive

solution for the disposal of calcium sulfide lies in the fact that it could be converted into sodium

thiosulfate, used by photographers to fix photographs but this cannot be considered as a feasible

option. Also at present there is a method of recovering sulfur from tank waste owing to the discoveries

of Alexander Chance in 1887. But these slight improvements would adversely affect the effi

design of sodium carbonate production plant[comprehensive design project]

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