Valorization of Solid/Liquid Wastes: A Route to Green Industrial Process

by

Dr. R. S. Somani, Senior Principal Scientist

Discipline of Inorganic Materials & CatalysisCentral Salt & Marine Chemicals Research Institute

(Council of Scientific and Industrial Research)rssomani@csmcri.org

16th October, 2014

Successful Case studies at CSIR-CSMCRI

Value addition of solid waste generated in nitro-phosphate fertilizer plant

Preparation of sodium silicate, precipitated silica and Zeolite-A from waste generated during diamond mining

Recovery of Palladium from spent silica and spent catalysts

Production of Zeolite-A from alumina waste, effluent containing AlCl3 and low grade Bauxite

Precipitated Calcium carbonate from carbide lime waste

Preparation of Synthetic Hydrotalcites from effluents discharged by Dye manufacturing units

Value addition of solid waste generated in nitro-phosphate fertilizer plant

Nitro Phosphate Fertilizer Plant

Rock Phosphate

Phosphoric Acid + Calcium Nitrate + Nitric Acid + HF

Calcium Nitrate, Tetra hydrate

ChillingPhosphoric Acid

+

Nitric Acid

+

HF

60% Nitric Acid

In 60% Ammonium Nitrate solution

Dissolution

Ammonium Carbonate

solution

Byproduct Calcium Carbonate

Ammonia

Filtration

CAN

Filtration

ANP

Drawbacks of solid waste / by-product

• Off white color

(Whiteness Index 80 – 85%)

• Coarse particle size

(20 – 150 microns)

• High bulk density

(1.32 – 1.35 g/cc)

• Alkaline pH (7.5 – 8.5)

• Low purity (CaCO3, 80 – 85 %)

• Presence of P2O5 (1.5 – 2.5%)

• Impurities identified:

Ammonium nitrate, Calcium

nitrate, Calcium tri-phosphate and

Calcium fluoride

Semi-continuous pilot plant (10kg/h) for the

production of PCC & ACC

Nitro phosphate

Fertilizer Plant Fertilizer

CaCO3 rich Inorganic

solid waste

Rotary Screw Feeder

Rotary Calciner

Rotary Cooler

Grinder

Slaker

Carbonation Tower

Filter Press

Dryer

Pulvarizer PCC or ACC

Wet Cake

Slurry Tank

Fatty acid / salt

solution

Exhaust Gases

Scrubber

CO2 Recovery &

Compression system

Air

Product Application Advantages to Fertilizer industry

• Low Raw Material Cost.

• Integration with Existing Complex –

Lower cost vis-à-vis setting up New

Plant.

• Waste Utilisation – Long Term

Solution.

• Recycling & recovery of ammonium

nitrate.

Patents Granted: US6,790,424, US6,761,864, JP2005507357T, JP2005507356T,

EP1440037, EP1440038, WO03037796, WO03037795, CN1484616, DE60108910D,

DE60108990D

Preparation of sodium silicate, Precipitated silica and Zeolite-A (detergent builder) from waste

generated during diamond mining

For mining of 10 carats of diamond, about 100

tons of solid waste (Kimberlite) is generated.

In Panna mines itself, which is mining about

58,000 carat of diamond, around 0.6 million

tones of this waste is produced every year.

Furthermore, around ~4 million tons of

kimberlite is already available from Panna

mines accumulated during previous mining.

Typically kimberlite waste is having the chemical

composition SiO2 30 – 32%, Al2O3 2 – 5%, TiO2 5 –

8%, CaO 8 – 10%, MgO 20 – 24%, Fe2O3 5 – 11%,

LOI 13 – 15%.

The major components of kimberlite waste are

magnesia and silica. The XRD patterns of the

kimberlite shows the presence of serpentine,

quartz, calcite and chlorite as major phases and

hematite, magnetite and anatase as minor phases.

Preparation of Sodium silicate, Precipitated silica and Zeolite-A from residual silica recovered from

Kimberlite

Kimberlite Waste

Acid Treatment

Acid treated kimberlite waste

(Silica rich (70-72%) residue)

Sodium Silicate

Ppt. Silica

Filtrate containing acid

soluble impurity

Treatment with NaOH

Solid containing HCl

and NaOH insoluble

material Zeolite-A

Used for preparing

Magnesium compounds and

Pigment grade Iron Oxide

Patent granted: US 7,335,342; 7,560,093; 7,037,476

Recovery of Palladium from spent silica and catalysts

United States Patent 7,108,839( 2006); 7,473,406 ( 2009)

Zeolite-A from alumina waste, effluent containing AlCl3and low grade Bauxite

PCC from carbide lime waste

Properties of Precipitated Calcium Carbonate from Carbide lime waste

Vaterite phase of CaCO3

Preparation of Synthetic Hydrotalcites from effluents discharged by Dye manufacturing units

Properties CSMC

RI -

SHT

DHT-4A

Molar ratio MgO/ Al2O3 4.2 4.0-5.0

Specific surface area

(BET) m2/gm

12 5-15

Loss on drying (105C,

1hr, %wt)

0.4 0.5 max.

Heavy metals (as pb) <10pp

m

10ppm

max.

Particle size distribution ( by number )

Mean particle size

(surface weighted) m

0.45 0.4-0.7

Under 1 m 90% 85% min.

Over 5 m None None

pH of suspension

[2%(w/v)C2H5OH:H2O(1

:1)]

9.1 9.00.5

Bulk density gm/c.c. 0.3 0.33

Halogen scavenger grade SHT

Key Innovations

Use of waste bittern as Mg source.

Reduced energy consumption.

Process simplicity.

AlCl3 spent liquor from fine chemical industries can be used.

High acid absorption capacity of pharma grade SHT.

A plant, set up by M/s Heubach Color Pvt. Ltd;

using CSIR-CSMCRI technology to manufacture

1000 Tons per annum of Synthetic hydrotalcite was

inaugurated by company’s Chairman, Mr. Rainer

Heubach on 10th October 2012. The product SHT is

prepared using effluent streams containing

aluminum, alkali generated in copper pthalocyanin

organic pigment plant of the company, and bittern

containing magnesium. The product meets the

specification of benchmark products marketed by

reputed companies. SHT finds many industrial

applications including polymer additive as halogen

scavenger, fire retardant material, as antacid

adsorbent and catalyst. The requirement is met

through import hitherto. Patent has been filed.

Inauguration of 1000TPA plant for production of Synthetic hydrotalcite (SHT)from waste

streams

CSIR-CSMCRI