comparative study of different environmental techniques...

COMPARATIVE STUDY OF DIFFERENT ENVIRONMENTAL TECHNIQUES IN THE

SECTOR PRODUCING MAGNESIUM OXIDE FROM MAGNESIUM VIA DRY PROCESS

__________________________________________________

February, 2009

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INDEX

1. STUDY BACKGROUND, PURPOSE AND SCOPE 3

2. METHODOLOGY FOLLOWED AND RESULTS 5

3. FINAL CONCLUSIONS 10

4. ANNEX: CALCULATIONS AND INITIAL INFORMATION 11

4.1 Direct atmospheric emissions 12

4.1.1 SO2 and particles 12

4.1.2 CO2 14

4.2 Spills into water 18

4.3 Electricity consumption and indirect atmospheric emissions 20

4.4 Water consumption 21

4.5 Summary table 24

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1. STUDY BACKGROUND, PURPOSE AND SCOPE

Within the revision framework of the European Commission BREF

documents1, a specific section for magnesium oxide production known

as magnesia from magnesium carbonate (magnesite) via the dry

process is being included in the old BREF cement and lime sector.

Although this activity is not specifically included in the IPPC Directive, its

inclusion has been justified by the competent bodies due to the similarity

in the industrial processes followed in these three sectors, likewise its

consideration as a chemical industry under Directive IPPC Annex I

epigraph 4.2e) .

With references to the techniques described as Best Available

Techniques (BAT) for the sector object of the study, a comparative study

has been carried out to clarify to what extent and for which specific

purpose a certain technique may be considered a BAT, since the

drafting of the last BREF draft2 is considered too confusing and general.

Therefore, there would be regions where some environmental aspects

would be priority against others, yet not necessarily relevant in other

regions (e.g. in areas of southern Europe water availability and quality

are critical aspects, while this may not be so in northern Europe,

furthermore air quality is influenced by air currents carrying particles from

the Sahara desert, which does not occur in other regions). Thus, the

appropriateness of the BAT should be specified and provide sufficient

information for their application in different local ambits.

1 Further information see http://eippcb.jrc.es/

2 Draft Reference Document on Best Available Techniques in the Cement, Lime and

Magnesium Oxide Manufacturing Industries. February 2009.

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The study has been limited to the following combined techniques

because they are the ones which caused most doubts in the BREF draft:

� Electrostatic Precipitator (ESP) to reduce particle emissions

and Wet Scrubber (WS) to reduce SO2 emissions. Hereinafter,

ESP+WS.

� Fabric Filters (FF) to reduce particle emissions and Wet

Scrubber (WS) to reduce SO2 emissions after reheating the

waste gas current to increase its performance. Hereinafter,

FF+WSa.

� Fabric Filters (FF) to reduce particle emissions and Wet

Scrubber (WS) to reduce SO2 emissions, without reheating

gases. Hereinafter, FF+WSb.

� Fabric Filters (FF) to reduce particle emissions and dry Sorbent

Injection (dSI) to reduce SO2 emissions. Hereinafter, FF+dSI.

Study results are given for each of these techniques as a range covering

the spectrum of the different fuels used by the sector.

Information sources used for this study are cited throughout the report.

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2. METHODOLOGY FOLLOWED AND RESULTS

For each of the above techniques, emissions into air and water, plus the

following consumptions were obtained from the initial information3 to

provide information enabling clarification of the advantages and

inconveniences of the different techniques to determine the most

appropriate and in which situations:

� Emissions into air:

o SO2 emissions after gas purification in concentration

and mass units.

o Particle emissions ones after gas purification in

concentration and mass units.

o Direct CO2 emissions due to gas purification systems

in mass units. These emissions come from additional

fuel consumption (and also new SOs, NOx and CO

emissions would be produced) and chemical

reactions produced in the purification system in such

case.

o Indirect SOs and CO2 emissions due to gas electricity

consumption of gas purification systems in mass

units.

3 Information sources for the execution of this study are included in the annex. Generally, BREF

amendment drafts object of the study were used as sources, information from the industry

itself, IPCC Guidelines for National Greenhouse Gas Inventories and BREF “Economics and

Cross-Media Effects”. Furthermore, information from these sources was contrasted with

that included in the BREF “General Principles of Monitoring” and “Common Waste Water

and Waste Gas Treatment/Management Systems in the Chemical Sector”, with

importance given to any information supplied by the BREF object of study

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� Emissions into water due to gas purification in concentration

and mass units.

� Electricity and water consumptions due to gas purification

systems in corresponding consumption units.

Other emissions or impacts were not considered since they caused no

doubts after drafting in the last BREF draft.

Thus, the following results were obtained as per the calculations and

initial information included in the annex:

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*Due to electricity consumption.

** Emissions may be greater. See section 4.1.1.

***Emissions may vary. See section 4.2. **** The amount consumed may vary. See section 4.4.

ESP + WS FF + WSa FF + WSb FF + dSI

mg/Nm3 < 35 < 20 < 20 < 20 Dust

kg/t MgO < 0.28 < 0.16 < 0.16 < 0.16

mg/Nm3 < 50 – 400 < 50 – 400** < 50 - 1200 < 50 - 1500

kg/t MgO < 0.40 – 3.20 < 0.40 – 3.20** < 0.40 – 9.60 < 0.40 – 12.0 SO2

kg/t MgO

indirect* 0.004 0.005 0.005 0.003

kg/t MgO 0 –

(8.97 – 16.28)

112.20 – 195.00

-

(121.17– 211.28)

0 –

(8.97 – 11.87) 0

CO2

kg/t MgO

indirect* 5.15 5.62 5.62 2.93

mg/l > 10000 > 10000 > 10000 0 SO4 2-

(waste

water)

kg/t MgO 19.50 – 35.40 19.50 –

35.40*** 19.50 – 28.80 0

EM

ISS

ION

S

Others -

Very relevant

CO trips due

to the ESP

NOx due to

the extra use

of fuel

- -

Electricity kWh/t

MgO 12.33 13.42 13.42 6.77

CO

NS

UM

PTI

ON

S

Water l/t MgO 1950 - 3540 1950 - 3540 1950 - 2880 0

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Below is a similar table indicating the relative differences between the

different techniques per environmental aspect, using as a base the

one(s) with lowest impact on each (should a technique have 0 impact,

the absolute values are expressed again.):




ESP + WS FF + WSa FF + WSb FF + dSI Optimum

mg/Nm3 + 75% Base Base Base Dust

kg/t MgO + 75% Base Base Base

FF + WSa

FF + WSb

FF + dSI

mg/Nm3 Base Base** + 0 – 200% + 0 –

275%

kg/t MgO Base Base** + 0 – 200% + 0 –

275%

ESP + WS

FF + WSa SO2

kg/t MgO

indirect* + 33% + 67% + 67% Base

kg/t MgO 0 –

(8.97 – 16.28)

112.20 – 195.00 -

(121.17 – 211.28)

0 –

(8.97 – 11.87) 0

FF + dSI

CO2 kg/t MgO

indirect* + 76% + 92% + 92% Base FF + dSI

mg/l > 10000 > 10000 > 10000 0 SO4 2-

(waste

water) kg/t MgO 19.50 – 35.40 19.50 – 35.40*** 19.50 – 28.80 0 FF + dSI

EM

ISS

ION

S

Others - CO trips NOx - - FF + WSb

FF + dSI

Electricity kWh/t

MgO + 82% + 98% + 98% Base FF + dSI

CO

NS

UM

PTI

ON

S

Water l/t MgO 1950 - 3540 1950 – 3540**** 1950 - 2880 0 FF + dSI

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Thus, we see the best techniques for SO2 emissions are combinations of

ESP and WS, and FF and WS with gas reheating.

Likewise the best techniques for particle emissions are all linked to FF.

Regarding CO2 emissions associated with the previous techniques, the

least contaminating (in relation to climate change) is the combination FF

+ dSI. Particularly contaminating would be the combination FF+WS with

gas reheating.

In relation to spills, as with the previous case, the technique with least

impact is the combination FF + dSI, with a great difference because it is

a dry process.

Finally, regarding electricity and water consumptions, the optimum

combination is FF + dSI as it consumes no water and consumes less

electricity.

Generally, one can see the combination FF+dSI has a lower impact on a

large number of environmental aspects, in some cases, very

significatively.

Moreover, application of these technologies makes emission control

monitory of the said pollutants necessary. In this sense, as included in the

last BREF draft, on-going monitoring is considered a BAT, as the practice

is virtually infallible, once contrasted and relatively economic4.

4 In the last BREF draft, Draft Reference Document on Best Available Techniques in the

Cement, Lime and Magnesium Oxide Manufacturing Industries. February 2009, on-going or

periodical monitoring is considered a BAT. In any event, advantages are clear at a very

low cost, on-going versus periodical monitory: real time information, workload modification

to influence emissions impossible, absolute representativeness, etc. Nevertheless,

periodical monitoring via sampling, on performing the corresponding laboratory analysis, is

more precise; and considered a necessary complement to on-going monitoring,

corroborated in the BREF “General Principles of Monitoring” July 2003, section 5.1.

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3. FINAL CONCLUSIONS

The result of the analysis seems clear there is no technique which is more

appropriate and at the same valid for all the environmental aspects

studied. Therefore, it seems reasonable to assume a separate BAT should

be considered per environmental aspect, unmistakeably indicating its

advantages and disadvantages, i.e. greater efficacy in one or several

environmental aspects, and less efficacy in other or several other

environmental aspects-.

Thus local authorities involved in granting IPPC authorisations or licences,

which in practice are the main destination of BAT documents, or those

involved in any other process referring to BAT application will have

sufficient information to assess the various techniques as per local

conditioning factors (e.g. greater or lesser water availability, deep local

air quality, fuels available, etc.), and is clearly the natural purpose of the

BREF documents.

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4. ANNEX: CALCULATIONS AND INITIAL INFORMATION

Different calculations were performed for the four alternative techniques

object of this study:

� Combination of electrostatic precipitators and wet scrubber (ESP +

WS)

� Combination of fabric filter and wet scrubber, with additional heat

contribution5 (FF + WSa)

� Combination of fabric filter and wet scrubber (FF + WS b)

� Combination of fabric filter and dry sorbent injection (FF + dSI)

5 Pursuant to information provided by sector from laboratory tests and theoretical

calculations, since there are no real data, gas effluent exits at approximately 150ºC, at this

temperature wet scrubber performance would be 80% obtaining SO2 concentrations of

1200 mg/Nm3. To achieve 400 mg/Nm3es a performance of 95% is necessary, achieved at

approximately 400ºC, thus additional heating is required to increase gas effluent

temperature.

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4.1 Direct atmospheric emissions

4.1.1 SO2 and particles

Individual emissions of these pollutants were calculated as per

their respective concentrations (mg/Nm3) in gas effluent.

Concentration 6 (mg/Nm3) Alternative

Technique SO2 7 Particles

ESP + WS < 50 - 400 < 35

FF + WSa <50 - 400 < 20

FF + WSb < 50 - 1200 < 20

FF + dSI < 50 - 1500 < 20

From these concentrations knowing the total volume of gases

emitted per ton of magnesium oxide produced, the amount of

pollutant emitted per ton of product (kg/tMgO) can be

calculated as the result of the product of these values.

Pollutant concentration (mg/Nm3) * Volume gases emitted

(Nm3/tMgO) * 10 -6 kg/mg = Emitted pollutant quantity (kg/tMgO)

A total volume of gases emitted has been fixed at 8000

Nm3/tMgO, obtained as the mean interval value 4000 - 12000

6 Pursuant to information provided by sector from laboratory tests and theoretical

calculations. Additionally, concentrations of 35 mg/Nm3 and 20 mg/Nm3 for particles, and

50 - 400 mg/Nm3 for SO2 included as BAT AEL in the Draft Reference Document on Best

Available Techniques in the Cement, Lime and Magnesium Oxide Manufacturing

Industries. February 2009. Chapter 3, section 3.5.4.3, page 376 and section 3.5.5.4, page

378, respectively.

7 These ranges depend on raw material sulphur content and fuel used. Emissions of <50

mg/Nm3 can be achieved when raw material sulphur content is <0.10% and natural gas

used as fuel (low sulphur content). Whereas when using other fuel available on the market,

with a greater sulphur content and raw material with a sulphur percentage of >0.25 %,

emission levels may reach the high levels in the range.

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Nm3/tMgO indicated in the BREF draft for cement, lime and

magnesium oxide production8.

Thus, applying the previous formula for different concentrations

given, the following results are obtained:

Pollutant Concentration

(mg/Nm3)

Volume

gases

emitted

(Nm3/t MgO)

Quantity

(kg/t MgO)

50 8000 0.40

400 8000 3.20

1200 8000 9.60 SO2

1500 8000 12.0

35 8000 0.28 Particles

20 8000 0.16

Getting back to the different alternative techniques, the

quantities and concentrations of pollutants emitted are

included in the following table:


Magnesium Oxide Manufacturing Industries. February 2009. Chapter 3, section 3.3.3.1,

page 352.

Pollutant ESP + WS FF + WSa FF + WSb FF + dSI

mg/N

m3 < 50 – 400 < 50 – 400 < 50 - 1200 < 50 - 1500

SO2 kg/t

MgO

< 0.40 –

3.20

< 0.40 –

3.20

< 0.40 –

9.60

< 0.40 –

12.0

mg/N

m3 < 35 < 20 < 20 < 20

Particles kg/t

MgO < 0.28 < 0.16 < 0.16 < 0.16

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In the case of the FF + WSa combination, the use of fuel to re-

heat the flue gases between the FF and the WS involves a new

SO2 source that should be treated in the WS to get the SO2

emission levels stated in the table, it is possible to get different

performances in the WS due to the S content in the fuel, so the

SO2 emissions could vary.

4.1.2 CO2

Some environmental techniques object of study produce direct

CO2 emissions. Thus in the wet scrubber case direct CO2

emissions are produced due to the chemical reaction

occurring in the wet scrubber to eliminate SO2:

SO2 + ½ O2 + 2H2O + MgCO3 � MgSO4�2H2O + CO2

Thus we can calculate the stoichiometric CO2 generated from

the amount of SO2 consumed in the wet scrubber:

Moles SO2 /t MgO = Moles CO2 /t MgO

Substituting the respective masses and molecular weights, the

following expression is obtained:

kg CO2/t MgO = kg SO2 /t MgO * PM CO2/ PM SO2

Where,

PM SO2 = 64 g/mol

PM CO2 = 44 g/mol

PM CO2 / PM SO2 = 44 / 64 = 0.69

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The following table shows the amounts of CO2 emitted due to

the process occurring in the wet scrubber, as per the different

amounts of SO2 calculated in the previous section:

SO2

Concentratio

n after WS

(mg/Nm3)

SO2

Concentrati

on before

WS

(mg/Nm3) 9

SO2 quantity

consumed

(kg/t MgO) 10

PM CO2

/

PM SO2

CO2 (kg/tMgO)

quantity

50 1675** 13.00 0.69 8.97

400 3350* 23.60 0.69 16.28

1200 3350* 17.20 0.69 11.87

* As per the reference at the foot of the page, the values showed are

intermediate cases of emissions not treated by “end of pipe” techniques,

minimised solely by primary measures. Therefore, in this study they are

assigned to those cases where final SO2 emission is 400 or 1200 mg/Nm3 (fuels

rich in S).

** As per the reference at the foot of the page, at least 50% of SO2 is from

raw material. Therefore, for the intermediate case showed, SO2 generated is

equal to 50% of 3350 mg/Nm3, i.e. 1675 mg/Nm3, assuming no contribution

from fuel or if so, it is insignificant. Therefore this value is assigned should the

final emission of SO2 (after purification) is 50 mg/Nm3, which is what

corresponds to the uses of fuels with low sulphur content.

Therefore, the additional amounts associated with each of the

four technologies studied would be as follows:



page 352, table 3.9. There are quoted SO2 emissions between 10-3350 mg/Nm3 and peaks

of 5000 mg/Nm3, corresponding to S low fuel and raw material; an intermediate situation,

and S rich fuel and raw material, respectively, without end of pipe treatment techniques.

In addition, in the same page it is quoted that up to a 50% of the SO2 emissions may come

from the S content in the fuel.

10 As with the previous sections, considering a volume of gases emitted at 8000Nm3/tMgO.

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For the combination FF + WSa, the use of fuel to heat gases

between FF and WS would involve a new emission of SO2

leading to more CO2 in the purification to reach levels

indicated.If using non-carbonated reactants there will be no

CO2 emissions.

Furthermore, in the second alternative technique proposed

(combination of fabric filter and wet scrubber, with additional

heat contribution) the CO2 emitted due to the fuel required to

elevate the temperature of the gaseous effluent must be

considered. This heat has been estimated at 2 GJ/t MgO by the

sector from laboratory tests and theoretical calculations. CO2

would vary depending on fuel used to obtain said energy

contribution. Thus considering CO2 emission factors of 56.1

kgCO2/GJ for natural gas and 97.5 kg CO2/GJ for pet coke11,

the amount of CO2 emitted per ton of magnesium oxide is:

� Gas natural � 56.1 kg CO2/GJ * 2 GJ/t MgO = 112.20 kg

CO2/t MgO

� Pet coke � 97.5 kg CO2/GJ * 2 GJ/t MgO = 195.00 kg

CO2/tMgO

11 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Volume 2, Chapter 1, pages

23 and 24.


CO2 kg/tMgO 8.97 –

16.28

8.97 –

16.28 8.97 – 11.87 0

of 24

With all this, the following table shows the different direct CO2

emissions associated with each of the four alternative

techniques object of analysis:

Moreover, there are other CO2 sources in the production

process apart from these techniques, which are magnesite d

(MgCO3) decomposition in CO2 , magnesium oxide (MgO), and

the fuel used for it. To produce one ton of magnesium oxide,

1,092 tons of CO2 are emitted due to decarbonation12. On the

other hand, approximately 0.4 – 1.3 tCO2/t MgO are emitted due

to combustion of different fuels, the lowest values being

associated with use or natural gas or similar and the highest

with pet coke or similar13. Therefore, depending on the fuel type

used, direct CO2 emissions associated with the magnesium

oxide production will range between 1.49 – 2.39 tCO2/t MgO (1490

– 2390 kgCO2/t MgO).


Magnesium Oxide Manufacturing Industries. February 2009. Chapter 3, section 3.3.1, page

350.



page 352.


WS 8.97 – 16.28 8.97 – 16.28 8.97 – 11.87 0

Additio

nal heat0

112.20 –

195.00 0 0

CO2

Kg/t MgO

Total 8.97 – 16.28 121.17 – 211.28 8.97 – 11.87 0

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4.2 Spills into water

Spills are only generated when using the wet scrubber. During the

process occurring inside the same, pollutants are transferred from

gaseous to water phase, SO2 transforming into sulphates (SO42-) which

are poured into the corresponding one. The chemical reaction which

occurs during the process is the following (considering the use of a

carbonate by way of example, used in the cement section of the BREF

draft object of study14):

SO2 + ½ O2 + 2H2O + XCO3 � XSO4�2H2O + CO2

From the amount of SO2 removed from the gaseous effluent and

calculated in previous sections, we can find out the sulphate

generated via stoichiometric calculation:

Moles SO2 /t MgO = Moles SO4 2- /t MgO

And expressed as masses and molecular weights would be as follows:

Kg SO4 2- /t MgO = kg SO2 /t MgO * PM SO4 2- / PM SO2

Where,

PM SO2 = 64 g/mol

PM SO4 2- = 96 g/mol

PM SO4 2- / PM SO2 = 96 / 64 = 1.5

14 Nevertheless, other reactants like calcium oxide or hydroxide or magnesium oxide. In case

of using calcium sources as reactants, calcium sulphate (gypsum, but not pure) -less

soluble- would be generated, leading to a solid waste that should be managed

according to waste laws. In case of using magnesium sources as reactants, magnesium

sulphate would be generated –very soluble- leading to an aqueous spill.

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The following table shows the amounts of sulphates spilled as per the

different amounts of SO2 captured in the wet scrubber and previously

calculated:

SO2

concentration

after WS

(mg/Nm3)

SO2 amount

consumed in

WS (kg/t MgO)

PM SO4 2- /

PM SO2

SO4 2 - (kg/tMgO)

amount

50 13.00 1.5 19.50

400 23.60 1.5 35.40

1200 17.20 1.5 28.80

Thus, the spills associated with each of the four technologies studied

would be as follows:

In the case of combination FF + WSa, use of fuel to heat gases between

FF and WS would involve a new emission of SO2 leading to more SO42-

after purification to reach levels indicated for final SO2 emission.

Furthermore, pursuant to information provided by the sector from

laboratory tests and theoretical calculations, the concentration of

sulphates in the spill would be > 10000 mg/l due to wet scrubber use,

using magnesium carbonate or magnesium oxide as a reactant. This

value may vary with other reactants.


SO4 2 -

kg/t

MgO

19.50 –

35.40

19.50 –

35.40 19.50 – 28.80 0

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4.3 Electricity consumption and indirect atmospheric emissions

The following table shows approximate consumptions for the different

Technologies applied. Due to lack of data regarding magnesium oxide

production, those similar to cement production taken from chapter 1,

sections 1.4.8.1 and 1.4.8.3, pages 154 and 158, respectively from the

Draft Reference Document on Best Available Techniques in the

Cement, Lime and Magnesium Oxide Manufacturing Industries.

February 2009; have been supposed.

Technology Consumption

(kWh/t MgO)15

Consumption (GJ/t

MgO)

ESP 4.15 0.015

FF 5.24 0.019

WS 8.18 0.029

dSI 1.53 0.006

Applying said consumptions to the four alternative techniques, the

following results were obtained:



page 154 and section 1.4.8.3, page 158.

Electricity

consumption ESP + WS FF + WSa FF + WSb FF + dSI

kwh/t MgO 12.33 13.42 13.42 6.77

GJ/t MgO 0.044 0.048 0.048 0.025

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Furthermore, indirect emissions associated with previous electricity

consumption were calculated. In this sense for the generation of 1GJ of

electricity in Europe 0.10 kg SO2/GJ and 117 kg CO2/GJ 16 are emitted

Multiplying these data for each alternative technique electricity

consumption, the indirect emissions of SO2 and CO2 associated with

each are obtained.

Electricity consumption (GJ/t MgO) * kg pollutant issued/GJ =

= Contaminating amount issued (kg/tMgO)

Results obtained shown in the following table:

4.4 Water consumption

Water only consumed in wet scrubber. Consumption depends on

multiple factors mainly associated with the amount of SO2, the reactant

16 Reference Document on Best Available Techniques on Economics and Cross-Media Effects.

Annex 8, page 110.

Alternative

technique ESP + WS FF + WSa FF + WSb FF + dSI

Consumption

GJ/t MgO 0.044 0.048 0.048 0.025

kg SO2/GJ 0.10 0.10 0.10 0.10

kg CO2/GJ 117 117 117 117

SO2 kg/t MgO

0.004 0.005 0.005 0.003

CO2

kg/t MgO 5.15 5.62 5.62 2.93

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used and its purification performance, which as seen may be variable.

Therefore, to calculate the consumption, a constant sulphate

concentration in the corresponding effluent > 10000 mg SO4 2 - / l 17 was

used and the amount (kg/t MgO) of spilled sulphates calculated

beforehand. This supposition would be schematically represented as

follows:

Thus, the necessary water volume to achieve said concentration.

Water volume (l/t MgO) = kg SO4 2 - spills/t MgO * 10 -6 kg/mg / 10000

mgSO4 2 - /l

Amount SO4 2 – spilled

(kg/t MgO)

Concentration SO4 2 -

(mg SO4 2 -/l)

Water volume

(l/t MgO )

19.50 > 10000 > 1950

35.40 > 10000 > 3540

28.80 > 10000 > 2880

Thus water consumptions associated to each of the four Technologies

studied would be as follows:

17 Data provided by sector from laboratory tests and theoretical calculations, for the use of

magnesium carbonate or magnesium oxide as a reactant in WS.

Water entry

Recirculated water

WSSpill

(fixed at 10000 mgSO4 2 -/l)

Water entry

Recirculated water

WSSpill

(fixed at 10000 mgSO4 2 -/l)

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As already mentioned, in the case of FF + WSa it could mean an even

greater amount of SO2 to be purified and as such water consumption in

the WS.

In any event, as indicated consumption depends on reactant used in

the WS, its efficiency, etc. Nevertheless, the datum provided may be

considered a valid reference for the effects of comparing different

techniques.

Water

Consumption ESP + WS FF + WSa FF + WSb FF + dSI

l/t MgO 1950 - 3540 1950 - 3540 1950 - 2880 0

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4.5 Summary table

The results of all the calculations made are included below.




ESP + WS FF + WSa FF + WSb FF + dSI

mg/Nm3 < 35 < 20 < 20 < 20 Dust

kg/t MgO < 0.28 < 0.16 < 0.16 < 0.16

mg/Nm3 < 50 – 400 < 50 – 400** < 50 - 1200 < 50 - 1500

kg/t MgO < 0.40 – 3.20 < 0.40 – 3.20** < 0.40 – 9.60 < 0.40 – 12.0 SO2

kg/t MgO

indirect 0.004 0.005 0.005 0.003

kg/t MgO 0 –

(8.97 – 16.28)

112.20 – 195.00

-

(121.17– 211.28)

0 –

(8.97 – 11.87) 0 CO2

kg/t MgO

indirect* 5.15 5.62 5.62 2.93

mg/l > 10000 > 10000 > 10000 0 SO4 2-

(waste

water)

kg/t MgO 19.50 – 35.40

19.50 –

35.40*** 19.50 – 28.80 0

EM

ISS

ION

S

Others -

Very relevant

CO trips due

to the ESP

NOx due to

the extra use

of fuel

- -

Electricity kWh/t

MgO 12.33 13.42 13.42 6.77

CO

NS

UM

PTI

ON

S

Water l/t MgO 1950 - 3540 1950 – 3540**** 1950 - 2880 0

comparative study of different environmental techniques...

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