WO1998013126A1 - Process for oxidizing magnesium sulfite or magnesium hydrogen sulfite - Google Patents

Process for oxidizing magnesium sulfite or magnesium hydrogen sulfite Download PDF

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Publication number
WO1998013126A1
WO1998013126A1 PCT/FI1997/000564 FI9700564W WO9813126A1 WO 1998013126 A1 WO1998013126 A1 WO 1998013126A1 FI 9700564 W FI9700564 W FI 9700564W WO 9813126 A1 WO9813126 A1 WO 9813126A1
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Prior art keywords
magnesium
sulfite
oxidation
magnesium sulfate
process according
Prior art date
Application number
PCT/FI1997/000564
Other languages
French (fr)
Inventor
Esko Kari
Original Assignee
Kemira Agro Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kemira Agro Oy filed Critical Kemira Agro Oy
Priority to AU43862/97A priority Critical patent/AU4386297A/en
Publication of WO1998013126A1 publication Critical patent/WO1998013126A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05D—INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
    • C05D5/00—Fertilisers containing magnesium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/73—After-treatment of removed components
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C01F5/40—Magnesium sulfates

Definitions

  • the invention relates to a process for the production of anhydrous magnesium sulfate or magnesium sulfate hydrates by oxidizing magnesium sulfite or magnesium hydrogen sulfite obtained from a flue gas desulfurization process.
  • Magnesium sulfate appears in nature in the form of either a binary salt or hydrates. Magnesium sulfate is obtained as the neutralization product of the acid secondary streams of many processes.
  • a flue gas desulfurization process can be used for producing sulfur-containing compounds.
  • Sulfur dioxide can be recovered by means of magnesium oxide or magnesium hydroxide as magnesium sulfite or magnesium hydrogen sulfite, for example, by wet scrubbing.
  • Magnesium is an important nutrient in horticulture and agriculture.
  • the fertilizer industry uses large amounts of magnesium sulfate in fertilizers, either solution fertilizers or compound fertilizers.
  • the magnesium sulfate used in compound fertilizers must be either anhydrous magnesium sulfate or a magnesium sulfate hydrate which contains only a small amount of crystal water, i.e. natural or synthetic kieserite.
  • magnesium sulfate or lower hydrates of magnesium sulfate such as synthetic kieserite
  • known methods of flue gas desulfurization have produced magnesium sulfate heptahydrate, from which it has been necuney to remove the crystal water by heating to considerably higli temperatures.
  • the heating to high temperatures raises the dehydration costs too high for rendering profitable the recovery of magnesium sulfate in the form of an anhydrous or synthetic kieserite from the sulfur dioxide of flue gases.
  • magnesium sulfite which can be separated by filtration and contains three or six molecules of ciystal water or magnesium hydrogen sulfite, depending on the forming temperature and pH.
  • These magnesium sulfite salts may be partly oxidized already in the gas scrubber by the oxygen present in the flue gases to magnesium sulfate, which at the same time dissolves in water.
  • the oxidation can be prevented by adding known oxidation inhibitors. It is known that the water solubility of magnesium sulfate is better than that of magnesium sulfite. At 50 °C, magnesium sulfate dissolves in water 32 per cent, whereas magnesium sulflte dissolves only 0.8-0.9 per cent.
  • the magnesium sulfate (MgS0 -7H 2 0) obtained as the oxidation product dissolves in water.
  • the magnesium sulfate is crystallized out from the aqueous solution by evaporation and/or by a lowering of the temperature. Crystallization by evaporation is known to be expensive and requires extensive investment, since, owing to the dilute quality of the scmbber solution used, the water amounts to be evaporated are large.
  • the crystallized magnesium sulfate contains crystal water (MgS0 -7H 2 0), the removal of which further requires dehydration at high temperatures in order to remove the water of crystallization completely or to obtain lower magnesium sulfate hydrates.
  • the costs of evaporation and dehydration make the process unprofitable.
  • magnesium sulfate can be prepared at a considerably lower investment cost than previously.
  • a separate crystallizer for magnesium sulfate is not required, since the magnesium sulfite slu ⁇ y separated from the scmbber solution is oxidized in the process of the invention directly to synthetic magnesium sulfate.
  • the said gross formula includes, among other things, anhydrous magnesium sulfate, lower magnesium sulfate hydrates, lower magnesium hydroxide sulfate hydrates, and mixtures thereof.
  • lower is meant in this context at maximum approx. 6.
  • the magnesium sulfite or magnesium hydrogen sulfite to be oxidized is in a solid and/or slurry state.
  • the dry matter content of the magnesium sulfite or magnesium hydrogen sulfite is preferably above approx. 80% by weight.
  • the magnesium sulfite or magnesium hydrogen sulfite can be withdrawn from the scmbber directly in a solid state.
  • the oxidation of magnesium sulfite or magnesium hydrogen sulfite in solution can be prevented in the scmbber, before the substance is separated in a solid state, by using inhibitors, such as elemental sulfur or other known oxidation inhibitors.
  • Filter-moist magnesium sulfite slurry or magnesium hydrogen sulflte slurry is oxidized with either air or oxygen, at elevated pressure and temperature.
  • molecular oxygen can be used for the oxidation. It is also possible to finish the oxidation by means of oxygen peroxide or use only hydrogen peroxide for the oxidation.
  • Anhydrous magnesium sulfate, synthetic kieserite or a magnesium sulfate which contains only a small amount of crystal water is obtained by optimizing the pressure and the temperature during the oxidation.
  • the suitable pressure is approximately 150-1000 kPa, preferably approx. 200-700 kPa, and the suitable temperature is approx. 50-160 °C.
  • an acid can be added to the magnesium sulfite slurry in order to facilitate oxidation and to evaporate chlorides as HC1 gas.
  • Anhydrous magnesium sulfate and synthetic kieserite are suitable for use in compound fertilizers as a magnesium-containing ingredient.
  • the oxidation product contained in total 66% of oxidized product Mgi 33 S0 4 (OH)o . w,-0.33H 2 0, MgS0 4 -H 2 0 and MgS0 4 -6H 2 0; 44% of the product was unoxidized MgSO v 3H 2 0.
  • the reaction velocity was observed by closing the oxygen feed for 5 min at a time at intervals of 1/2 - 1 h and by monitoring the pressure drop in the reactor. The total reaction time was 3 hours. After the experiment, a large amount of water vapor emerged from the reactor. Vacuum drying was carried out in the reactor for 15 min immediately after the experiment. During the diying the temperature dropped to 80 °C. After the oxidation, the crystals were withdrawn from the reactor; the weighed amount was 307 g. The crystals were dry and did not cake. According to an X-ray analysis, 82% of the oxidation product consisted of a synthetic oxidation product of magnesium sulfide. MgS0 4 - 1.25H 2 0 and Mg ⁇ .. SO 4 (OH) 0 r.., * 0.33H 2 O, and additionally 14% consisted of MgS0 4 -6H 2 0. Only 4% of the product consisted of unoxidized initial substance, MgSO v 3H 2 0.
  • reaction velocity was observed by closing the oxygen feed for 5 min at a time at intervals of 1/2 - 1 h and by monitoring the pressure drop in the reactor. The total reaction time was 3 hours. After the experiment, a large amount of water vapor emerged from the reactor. Brief vacuum drying was earned out in the reactor immediately after the experiment. After the oxidation, the crystals were withdrawn from the reactor. They were moist. The ciystal sample was washed with ethanol and water. According to an X-ray analysis, 50% of the oxidation product consisted of a mixture of Mg 1 3-.SO 4 (OH) 0 fi r,-0.33H 2 O, MgS0 4 1.25H 2 0, MgS0 4 -6H 2 0, and
  • the unoxidized portion consisted of MgS0 3 -6H 0 37%, MgSOr7H 2 0 10%. and MgSO v 3H 2 0 3%.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Abstract

The invention relates to a process for the preparation of anhydrous magnesium sulfate or magnesium sulfate hydrates, wherein magnesium sulfite or magnesium hydrogen sulfite obtained from a flue gas desulfurization process is oxidized. According to the invention the magnesium sulfite or magnesium hydrogen sulfite is oxidized in a solid state or as a slurry, at elevated pressure and temperature, to magnesium sulfate having a gross formula of MgvSxHyOz, where v = 1-2, x = 1-2, y = 0-14, and z = 4-16.

Description

Process for oxidizing magnesium sulfite or magnesium hydrogen sulfite
The invention relates to a process for the production of anhydrous magnesium sulfate or magnesium sulfate hydrates by oxidizing magnesium sulfite or magnesium hydrogen sulfite obtained from a flue gas desulfurization process.
Magnesium sulfate appears in nature in the form of either a binary salt or hydrates. Magnesium sulfate is obtained as the neutralization product of the acid secondary streams of many processes. A flue gas desulfurization process (FGD) can be used for producing sulfur-containing compounds. Sulfur dioxide can be recovered by means of magnesium oxide or magnesium hydroxide as magnesium sulfite or magnesium hydrogen sulfite, for example, by wet scrubbing.
From US patent publications 5 270 026 and 4 996 032 there are known methods for the recovery of sulfur dioxide by means of magnesium hydroxide or magnesium oxide, first as magnesium sulfite by wet scrubbing. The magnesium sulfite is oxidized in an aqueous solution by means of air to a magnesium sulfate solution, to which lime is added in order to precipitate calcium sulfate and to foπn a magnesium hydroxide suspension, the aim being the recovery and/or recycling of a pure magnesium hydroxide or magnesium oxide.
Magnesium is an important nutrient in horticulture and agriculture. The fertilizer industry uses large amounts of magnesium sulfate in fertilizers, either solution fertilizers or compound fertilizers. The magnesium sulfate used in compound fertilizers must be either anhydrous magnesium sulfate or a magnesium sulfate hydrate which contains only a small amount of crystal water, i.e. natural or synthetic kieserite.
When the objective is to obtain anhydrous magnesium sulfate or lower hydrates of magnesium sulfate, such as synthetic kieserite, known methods of flue gas desulfurization have produced magnesium sulfate heptahydrate, from which it has been necessaiy to remove the crystal water by heating to considerably higli temperatures. The heating to high temperatures raises the dehydration costs too high for rendering profitable the recovery of magnesium sulfate in the form of an anhydrous or synthetic kieserite from the sulfur dioxide of flue gases.
From a gas scrubber, there is obtained either a magnesium sulfite which can be separated by filtration and contains three or six molecules of ciystal water or magnesium hydrogen sulfite, depending on the forming temperature and pH. These magnesium sulfite salts may be partly oxidized already in the gas scrubber by the oxygen present in the flue gases to magnesium sulfate, which at the same time dissolves in water. When necessary, the oxidation can be prevented by adding known oxidation inhibitors. It is known that the water solubility of magnesium sulfate is better than that of magnesium sulfite. At 50 °C, magnesium sulfate dissolves in water 32 per cent, whereas magnesium sulflte dissolves only 0.8-0.9 per cent. Since in known processes the oxidation of magnesium sulfite is carried out in an aqueous solution, the magnesium sulfate (MgS0 -7H20) obtained as the oxidation product dissolves in water. The magnesium sulfate is crystallized out from the aqueous solution by evaporation and/or by a lowering of the temperature. Crystallization by evaporation is known to be expensive and requires extensive investment, since, owing to the dilute quality of the scmbber solution used, the water amounts to be evaporated are large. The crystallized magnesium sulfate contains crystal water (MgS0 -7H20), the removal of which further requires dehydration at high temperatures in order to remove the water of crystallization completely or to obtain lower magnesium sulfate hydrates. The costs of evaporation and dehydration make the process unprofitable.
It is an object of the present invention to recover sulfur dioxide by means of magnesium oxide from flue gases, directly in a form usable in the fertilizer industry and in other chemical and paper making industry processes, whereby high costs of investment, evaporation and dehydration can be avoided. According to the invention, magnesium sulfate can be prepared at a considerably lower investment cost than previously. A separate crystallizer for magnesium sulfate is not required, since the magnesium sulfite sluπy separated from the scmbber solution is oxidized in the process of the invention directly to synthetic magnesium sulfate.
The characteristics of the invention are stated in the accompanying claims.
The major proportion of the product prepared according to the invention is made up of magnesium sulfate having the gross formula of MgvSxHyO , where v = 1-2, x = 1- 2, y = 0-14, and z = 4-16.
The said gross formula includes, among other things, anhydrous magnesium sulfate, lower magnesium sulfate hydrates, lower magnesium hydroxide sulfate hydrates, and mixtures thereof. By "lower" is meant in this context at maximum approx. 6. The magnesium sulfite or magnesium hydrogen sulfite to be oxidized is in a solid and/or slurry state. The dry matter content of the magnesium sulfite or magnesium hydrogen sulfite is preferably above approx. 80% by weight.
According to the invention, the magnesium sulfite or magnesium hydrogen sulfite can be withdrawn from the scmbber directly in a solid state. The oxidation of magnesium sulfite or magnesium hydrogen sulfite in solution can be prevented in the scmbber, before the substance is separated in a solid state, by using inhibitors, such as elemental sulfur or other known oxidation inhibitors. Filter-moist magnesium sulfite slurry or magnesium hydrogen sulflte slurry is oxidized with either air or oxygen, at elevated pressure and temperature. For example, molecular oxygen can be used for the oxidation. It is also possible to finish the oxidation by means of oxygen peroxide or use only hydrogen peroxide for the oxidation. Anhydrous magnesium sulfate, synthetic kieserite or a magnesium sulfate which contains only a small amount of crystal water is obtained by optimizing the pressure and the temperature during the oxidation. The suitable pressure is approximately 150-1000 kPa, preferably approx. 200-700 kPa, and the suitable temperature is approx. 50-160 °C.
According to the invention, before oxidation or dehydration an acid can be added to the magnesium sulfite slurry in order to facilitate oxidation and to evaporate chlorides as HC1 gas.
Anhydrous magnesium sulfate and synthetic kieserite are suitable for use in compound fertilizers as a magnesium-containing ingredient.
The invention is described below in closer detail with the help of working examples. It is clear, however, that the various applications of the invention are not limited to those presented below as examples but can be varied within the scope of the accompanying patent claims.
Example 1
404 g of MgSO_r3H20 crystals having a dry matter content of 88.5% were placed in a two-liter reactor. The reactor was closed and the temperature was raised to 106 °C. Oxygen was fed continuously into the reactor. During the oxygen feeding the pressure was approx. 580 kPa. The flowing of oxygen out of the reactor was prevented. The reaction velocity was tested intermittently by closing the oxygen feed for approx. five minutes at a time, in total five times. Thereupon the pressure dropped to approx. 470 kPa for two minutes. The temperature varied within 145- 152 °C. The total reaction time was 3 hours. When the valve was opened after the oxidation, a large amount of water vapor came out of the reactor. Vacuum drying was carried out at lowered pressure for 15 minutes, during which the temperature dropped from 140 °C to 80 °C. The crystals were completely dry. The yield was 323 g. An X-ray analysis of the product showed that 83% consisted of MgS04-5/4H20 and 17% of MgS04-6H20.
Example 2
306 g of MgSOr3H20 crystals having a dry matter content of 82.0% were placed in a two-liter reactor. The reactor was closed and the temperature was increased to 96 °C. Air was fed into the reactor continuously, during which the pressure varied within 610-630 kPa. Air flowed through the reactor, the outlet being approx. 4.5- 5 1/min. After approx. 1 h 20 in, the air flowing out was completely dry. The temperature varied within 140-133 °C. The crystals withdrawn from the reactor were completely dry, the weighed yield was 228 g. An X-ray analysis showed that approx. 50% of the product had oxidized to .synthetic kieserite MgS04-5/4H20.
Example 3
400 g of MgSOy3H20 crystals having a dry matter content 81.4% were placed in a two-liter reactor. The reactor was closed and the temperature was raised to 105 °C, whereafter the reactor was rinsed with oxygen and was closed. During the rinse, water vapor emerged from the reactor. The oxygen line to the reactor was open and the reactor pressure in the experiment was 200-210 kPa. The temperature during the experiment was 120 °C - 130 °C. The reaction velocity was observed by closing the oxygen feed for approx. 5 min at a time at intervals of 1/2 - 1 hour and by monitoring the pressure drop in the reactor. The total reaction time was 3 hours. Vacuum drying was carried out in the reactor immediately after the experiment, for 10 min. During the drying, the temperature dropped only 10 °C. The crystals were dry and did not cake. According to an X-ray analysis, the oxidation product contained in total 66% of oxidized product Mgi 33S04(OH)o.w,-0.33H20, MgS04-H20 and MgS04-6H20; 44% of the product was unoxidized MgSOv3H20.
Example 4
400 g of MgS03-3H 0 crystals having a dry matter content 81.4% were placed in a two-liter reactor. The reactor was rinsed with oxygen immediately at the beginning of the run and was closed. During the heating step the reactor was kept closed and a pressure of 160-200 kPa prevailed in it, and the oxygen line was closed. During oxidation, the oxygen line to the reactor was open and the reactor pressure was regulated by means of the oxygen feeding pressure; in this experiment the reactor pressure was 400-430 kPa. The temperature during the experiment was 130 °C - 140 °C for two hours and 120 °C - 130 °C for one hour. The reaction velocity was observed by closing the oxygen feed for 5 min at a time at intervals of 1/2 - 1 h and by monitoring the pressure drop in the reactor. The total reaction time was 3 hours. After the experiment, a large amount of water vapor emerged from the reactor. Vacuum drying was carried out in the reactor for 15 min immediately after the experiment. During the diying the temperature dropped to 80 °C. After the oxidation, the crystals were withdrawn from the reactor; the weighed amount was 307 g. The crystals were dry and did not cake. According to an X-ray analysis, 82% of the oxidation product consisted of a synthetic oxidation product of magnesium sulfide. MgS04- 1.25H20 and Mgι .. SO4(OH)0 r..,*0.33H2O, and additionally 14% consisted of MgS04-6H20. Only 4% of the product consisted of unoxidized initial substance, MgSOv3H20.
Example 5
340 g of MgSOr3H20 crystals, together with 27 g of concentrated H2S04, were placed in a two-liter reactor. The diy matter content of the MgS03-3H 0 crystals was 81.4%. The reactor was rinsed with oxygen immediately at the beginning of the mn and was closed. During the heating step the reactor was kept closed and a pressure of 3 bar prevailed in it, and the oxygen line was closed. During oxidation, the oxygen line to the reactor was open and the reactor pressure was regulated by means of the oxygen feeding pressure; in this experiment the reactor pressure was 400 kPa. The temperature during the experiment was 120 °C - 130 °C. The reaction velocity was observed by closing the oxygen feed for 5 min at a time at intervals of 1/2 - 1 h and by monitoring the pressure drop in the reactor. The total reaction time was 3 hours. After the experiment, a large amount of water vapor emerged from the reactor. Brief vacuum drying was earned out in the reactor immediately after the experiment. After the oxidation, the crystals were withdrawn from the reactor. They were moist. The ciystal sample was washed with ethanol and water. According to an X-ray analysis, 50% of the oxidation product consisted of a mixture of Mg1 3-.SO4(OH)0 fir,-0.33H2O, MgS04 1.25H20, MgS04-6H20, and
Mg(OH)2(S04)2-3H20. The unoxidized portion consisted of MgS03-6H 0 37%, MgSOr7H20 10%. and MgSOv3H20 3%.

Claims

Claims
1. A process for the preparation of anhydrous magnesium sulfate or magnesium sulfate hydrates by oxidizing magnesium sulfite or magnesium hydrogen sulfite obtained from a flue gas desulfurization process, characterized in that the mag- nesium sulflte or magnesium hydrogen sulflte is oxidized in a solid state or as a sluny, at elevated pressure and temperature, to magnesium sulfate having a gross formula of MgvSxHvOz, where v = 1-2, x = 1 -2, y = 0- 14, and z -~ 4-16.
2. A process according to Claim 1, characterized in that the diy matter content of the solid or slurry-form magnesium sulfite or magnesium hydrogen sulfite is above 80% by weight.
3. A process according to Claim 1, characterized in that the oxidation is carried out by means of air.
4. A process according to Claim 1, characterized in that the oxidation is caπied out by means of molecular oxygen.
5. A process according to Claim 1, characterized in that the oxidation is carried out entirely or at least in part by means of hydrogen peroxide.
6. A process according to Claim 1 , characterized in that the oxidation is carried out by means of air and hydrogen peroxide.
7. A process according to Claim 1 , characterized in that the oxidation is carried out at a temperature of 50- 160 °C.
8. A process according to Claim 1, characterized in that the oxidation is carried out in a reactor at a pressure of 150-1000 kPa, preferably a pressure of 200-700 kPa.
9. A process according to any of Claims 1-8, characterized in that the obtained magnesium sulfate hydrate is a synthetic kieserite.
10. A process according to any of Claims 1, 2 or 8, characterized in that the oxidation of solution-form magnesium sulfite or magnesium hydrogen sulfite obtained from the desulfurization process is prevented, before the separation of a solid or slurry-form magnesium sulfite or magnesium hydrogen sulflte and its oxidation to anhydrous magnesium sulfate or magnesium sulfate hydrate, by using an inhibitor, such as elemental sulfur or any other known oxidation inhibitor.
1 1. The use of magnesium sulfate prepared by the process according to any of Claims 1 - 10 in fertilizers.
PCT/FI1997/000564 1996-09-23 1997-09-22 Process for oxidizing magnesium sulfite or magnesium hydrogen sulfite WO1998013126A1 (en)

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AU43862/97A AU4386297A (en) 1996-09-23 1997-09-22 Process for oxidizing magnesium sulfite or magnesium hydrogen sulfite

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FI963765 1996-09-23
FI963765A FI102959B1 (en) 1996-09-23 1996-09-23 A process for oxidizing magnesium sulfite or magnesium hydrogen sulfite

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102078750A (en) * 2010-12-10 2011-06-01 清华大学 Recovery method of magnesium oxide flue gas desulfurization product
CN103387247A (en) * 2012-05-09 2013-11-13 中节能六合天融环保科技有限公司 Process for preparing magnesium sulfate heptahydrate and liquid sulfur dioxide by comprehensively utilizing magnesium desulfurization byproducts
CN103386311A (en) * 2012-05-09 2013-11-13 中节能六合天融环保科技有限公司 Catalyst for promoting magnesium sulfite oxidized to magnesium sulfate, and preparation method thereof

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2659860C2 (en) * 1975-03-31 1982-06-09 Hyogo Prefectural Government, Kobe Process for the production of calcium sulphate in the form of whisker-shaped anhydrite II crystals
EP0505607A1 (en) * 1991-03-26 1992-09-30 Dravo Lime Company Sulfur dioxide removal process with gypsum and magnesium hydroxide production
EP0604701A1 (en) * 1992-12-31 1994-07-06 Dravo Lime Company Method of sulfur dioxide removal from gaseous streams with alpha hemihydrate gypsum product formation

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2659860C2 (en) * 1975-03-31 1982-06-09 Hyogo Prefectural Government, Kobe Process for the production of calcium sulphate in the form of whisker-shaped anhydrite II crystals
EP0505607A1 (en) * 1991-03-26 1992-09-30 Dravo Lime Company Sulfur dioxide removal process with gypsum and magnesium hydroxide production
EP0604701A1 (en) * 1992-12-31 1994-07-06 Dravo Lime Company Method of sulfur dioxide removal from gaseous streams with alpha hemihydrate gypsum product formation

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102078750A (en) * 2010-12-10 2011-06-01 清华大学 Recovery method of magnesium oxide flue gas desulfurization product
CN103387247A (en) * 2012-05-09 2013-11-13 中节能六合天融环保科技有限公司 Process for preparing magnesium sulfate heptahydrate and liquid sulfur dioxide by comprehensively utilizing magnesium desulfurization byproducts
CN103386311A (en) * 2012-05-09 2013-11-13 中节能六合天融环保科技有限公司 Catalyst for promoting magnesium sulfite oxidized to magnesium sulfate, and preparation method thereof

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FI102959B (en) 1999-03-31
FI102959B1 (en) 1999-03-31
FI963765A (en) 1998-03-24
FI963765A0 (en) 1996-09-23

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