CN1162330C - Clean production method of potassium chromate - Google Patents
Clean production method of potassium chromate Download PDFInfo
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- CN1162330C CN1162330C CNB011416831A CN01141683A CN1162330C CN 1162330 C CN1162330 C CN 1162330C CN B011416831 A CNB011416831 A CN B011416831A CN 01141683 A CN01141683 A CN 01141683A CN 1162330 C CN1162330 C CN 1162330C
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- potassium chromate
- potassium
- iron slag
- chromite
- chromium
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- QLOKJRIVRGCVIM-UHFFFAOYSA-N 1-[(4-methylsulfanylphenyl)methyl]piperazine Chemical compound C1=CC(SC)=CC=C1CN1CCNCC1 QLOKJRIVRGCVIM-UHFFFAOYSA-N 0.000 title claims abstract description 67
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 87
- 239000013078 crystal Substances 0.000 claims abstract description 29
- 238000000034 method Methods 0.000 claims abstract description 27
- 239000000047 product Substances 0.000 claims abstract description 25
- 239000003513 alkali Substances 0.000 claims abstract description 16
- 239000007795 chemical reaction product Substances 0.000 claims abstract description 12
- 239000007788 liquid Substances 0.000 claims abstract description 9
- 239000002002 slurry Substances 0.000 claims abstract description 9
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 239000007800 oxidant agent Substances 0.000 claims abstract description 5
- 239000007791 liquid phase Substances 0.000 claims abstract description 4
- 229910052742 iron Inorganic materials 0.000 claims description 42
- 239000002893 slag Substances 0.000 claims description 41
- 150000001844 chromium Chemical class 0.000 claims description 18
- 238000005406 washing Methods 0.000 claims description 17
- 238000002386 leaching Methods 0.000 claims description 16
- 238000001914 filtration Methods 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- 238000002425 crystallisation Methods 0.000 claims description 10
- 230000008025 crystallization Effects 0.000 claims description 10
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims description 9
- KMUONIBRACKNSN-UHFFFAOYSA-N potassium dichromate Chemical compound [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O KMUONIBRACKNSN-UHFFFAOYSA-N 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 6
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 6
- 239000012452 mother liquor Substances 0.000 claims description 6
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims description 6
- XXQBEVHPUKOQEO-UHFFFAOYSA-N potassium superoxide Chemical compound [K+].[K+].[O-][O-] XXQBEVHPUKOQEO-UHFFFAOYSA-N 0.000 claims description 6
- 230000032683 aging Effects 0.000 claims description 5
- 230000001590 oxidative effect Effects 0.000 claims description 5
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 4
- 239000002535 acidifier Substances 0.000 claims description 4
- 239000003570 air Substances 0.000 claims description 4
- 239000007789 gas Substances 0.000 claims description 4
- 239000001569 carbon dioxide Substances 0.000 claims description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 3
- 150000007522 mineralic acids Chemical group 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 238000006864 oxidative decomposition reaction Methods 0.000 claims description 3
- 239000004323 potassium nitrate Substances 0.000 claims description 3
- 235000010333 potassium nitrate Nutrition 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- JTNCEQNHURODLX-UHFFFAOYSA-N 2-phenylethanimidamide Chemical compound NC(=N)CC1=CC=CC=C1 JTNCEQNHURODLX-UHFFFAOYSA-N 0.000 claims description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 2
- 229910052760 oxygen Inorganic materials 0.000 claims description 2
- 239000001301 oxygen Substances 0.000 claims description 2
- 235000015497 potassium bicarbonate Nutrition 0.000 claims description 2
- 239000011736 potassium bicarbonate Substances 0.000 claims description 2
- 229910000028 potassium bicarbonate Inorganic materials 0.000 claims description 2
- 229910000343 potassium bisulfate Inorganic materials 0.000 claims description 2
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 claims description 2
- 238000005191 phase separation Methods 0.000 claims 1
- 238000004321 preservation Methods 0.000 claims 1
- 230000035484 reaction time Effects 0.000 claims 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical class [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 abstract description 25
- 239000011651 chromium Substances 0.000 abstract description 22
- 229910052804 chromium Inorganic materials 0.000 abstract description 22
- 238000006243 chemical reaction Methods 0.000 abstract description 18
- 238000011084 recovery Methods 0.000 abstract description 7
- 238000005516 engineering process Methods 0.000 abstract description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract 1
- 238000001354 calcination Methods 0.000 abstract 1
- 229910052799 carbon Inorganic materials 0.000 abstract 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 27
- 239000000243 solution Substances 0.000 description 21
- 239000000126 substance Substances 0.000 description 10
- 239000002994 raw material Substances 0.000 description 8
- 238000001704 evaporation Methods 0.000 description 5
- 239000011777 magnesium Substances 0.000 description 5
- PXLIDIMHPNPGMH-UHFFFAOYSA-N sodium chromate Chemical compound [Na+].[Na+].[O-][Cr]([O-])(=O)=O PXLIDIMHPNPGMH-UHFFFAOYSA-N 0.000 description 5
- 238000000354 decomposition reaction Methods 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000010413 mother solution Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910018134 Al-Mg Inorganic materials 0.000 description 1
- 229910018467 Al—Mg Inorganic materials 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 231100000086 high toxicity Toxicity 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229940072033 potash Drugs 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 1
- 235000015320 potassium carbonate Nutrition 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
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Abstract
The present invention relates to a clean production method for potassium chromate, which belongs to the field of a production method for chrome salts. The method comprises: chromite reacts with a stoichiometric oxidizing agent in a KOH liquid phase medium so as to obtain a mixed reaction product which comprises alkali liquid, chrome salts and iron residues, wherein the proportion by weight of the KOH and the chromite is 2:1 to 6:1; the mixed reaction product is leached, and coarse crystals of potassium chromate, iron residues and the alkali liquid of leached slurry are separated; a purified potassium chromate crystallizing product is obtained after the coarse crystals of potassium chromate are dissolved and crystallized, and impurities are removed. The reaction temperature of the method is 250 to 400 DEG C, a chromium recovery rate is more than 99%, and an iron residue content is 0.6 ton in each ton of products. Compared with a carbon alkali calcining technology adopted in industry at present, the reaction temperature is reduced by about 800 DEG C, the chromium recovery rate is increased by about 20%, and a chromium residue content is reduced to one fourth of the prior art.
Description
Technical Field
The invention belongs to the field of production methods of chromium salts, and particularly relates to a clean production method of potassium chromate.
Background
The potassium chromate is mainly used for enamel, tanning, dye, pigment, medicine, metal and anticorrosive and analytical reagent, and can also be used as raw material for preparing chromium series chemical products such as potassium dichromate, chromic oxide and chromic anhydride.
The production of chromium salt by using chromite is an important basic raw material industry crossed with chemical industry and metallurgy, and relates to a product with the national economy of more than 10%. The existing potassium chromate producing methods include potash roasting, neutralization, decomposition and double decomposition, which are referred to as "chromium salt productionprocess" in the monograph of thinking crisis. The production method of chromium salt series products is to use sodium chromate as raw material to prepare, and the existing sodium chromate production method at home and abroad is high-temperature oxidation roasting decomposition of chromite by sodium carbonate, water immersion, multi-stage evaporation crystallization, the reaction temperature of the method is up to 1100 ℃, the chromium recovery rate is less than 80 percent, the environment is seriously polluted, 2.5 to 3.0 tons of high-toxicity chromium slag are required to be discharged for producing each ton of chromium salt products, and the further development of the chromium salt industry in China is seriously restricted. Research on calcium-free and calcium-less roasting processes is carried out at home and abroad aiming at the problem of chromium slag, the research belongs to an improved technology of a roasting method, and although certain progress is made in the aspects of chromium slag discharge and chromium recovery rate, the current situations of low resource utilization rate and serious environmental pollution in chromium salt production cannot be broken through.
Disclosure of Invention
The invention aims to overcome the defects of high energy consumption, serious environmental pollution and low yield of potassium chromate in the existing potassium chromate production method, and provides a clean production method of potassium chromate with industrial operability, so as to replace the existing high-temperature sodium-alkali roasting method, and replace sodium chromate with potassium chromate to be used as a raw material for producing other chromium series chemical products.
The method of the invention is based on the principle that chromite and air generate gas-liquid-solid multiphase oxidation reaction in KOH liquid medium at the temperatureof 250-400 ℃, trivalent chromium in the chromite is oxidized into hexavalent chromium, and potassium chromate is generated. The main reaction is as follows:
compared with the high-temperature oxidizing roasting process of the traditional roasting method, the reaction process and the transfer process of the chromite in the KOH liquid phase flowing medium are greatly enhanced, so that the chromium recovery rate is greatly improved at a lower reaction temperature, no inert auxiliary material is added in the reaction process, and the slag quantity is reduced. In addition, because the dissolution performance of each component of the chromium ore in a sub-molten salt medium is completely different from that of the high-temperature roasting process, the valuable components of the chromium ore are easy to comprehensively utilize, and a good premise is created for realizing the clean production of the chromium salt.
The clean production method of the potassium chromate comprises the following steps: the chromite is subjected to oxidative decomposition in a liquid phase flowing medium of KOH, and potassium chromate coarse crystals are separated from the leaching slurry and then purified to obtain a qualified potassium chromate product. The method comprises the following steps:
(1) reacting chromite with stoichiometric oxidant in KOH liquid medium at the reaction temperature of 250-400 ℃ for 1-6 hours to obtain a mixed reaction product containing alkali liquor, chromium salt and iron slag; wherein the weight ratio of KOH to ore is 2: 1-6: 1;
(2) leaching the mixed reaction product obtained in the step (1) with water, or low-alkalinity iron slag washing liquid obtained after washing the iron slag obtained in the step (1), or a mixture of the two to obtainleached slurry, wherein the temperature is 80-180 ℃;
(3) separating the leached pulp obtained in the step (2) to obtain potassium chromate coarse crystals, iron slag and alkali liquor respectively, wherein the separation temperature is 60-120 ℃;
(4) dissolving the potassium chromate coarse crystal obtained in the step (3) with water or the crystallization mother liquor obtained in the step (6) or a mixture of the two, and filtering to remove insoluble impurities such as iron slag and the like to obtain a potassium chromate solution;
(5) adjusting the pH value of the potassium chromate solution obtained in the step (4) to be 5-8 by using an acidifying agent, and separating and removing soluble impurities in the solution to obtain a pure potassium chromate solution.
(6) Further heating and evaporating the pure potassium chromate solution obtained in the step (5), preserving heat, aging, filtering and drying to obtain a pure potassium chromate crystal product and a crystallization mother liquor, and returning the crystallization mother liquor to the step (4) for dissolving the crude potassium chromate crystals.
The iron slag washing liquid in the step (2) is used for carrying out multi-stage countercurrent washing on the iron slag by using water, the stage number of the countercurrent washing is 3-5, the washing temperature is 50-90 ℃, and the obtained dry iron slag is uniform powder rich in iron and magnesium.
The dry iron slag obtained by the invention can be used as an iron-based raw material in the steel industry or the cement industry or used for preparing iron-based high value-added products after magnesium extraction.
The invention further returns the alkali liquor obtained in the step (3) to the step (1) for decomposing the chromite.
The oxidant in the step (1) is air, oxygen, potassium nitrate or potassium peroxide and the like.
The dissolving temperature of the step (4) is 30-90 ℃, and the concentration of potassium chromate is 20-50 wt%.
The acidifier is inorganic acid, acid gas, chromic anhydride, potassium dichromate, potassium bicarbonate or potassium bisulfate and the like; the inorganic acid is sulfuric acid, hydrochloric acid or nitric acid, etc.; the acid gas is carbon dioxide, sulfur dioxide or nitrogen oxide, etc.
The invention provides a clean production method for producing potassium chromate from chromite in KOH medium, and potassium chromate is used as a raw material for preparing other chromium series products. Compared with the existing industrial technology at home and abroad, the method for preparing other chromium series products by using sodium chromate produced by a high-temperature roasting method as a raw material has obvious superiority:
(1) the reaction temperature of the method is 250-400 ℃, the reaction temperature is reduced by about 800 ℃ compared with the traditional process, the energy consumption can be reduced by 30 percent, the chromium conversion rate is close to 100 percent, and the chromium recovery rate is more than 99 percent; the chromium recovery rate is improved by 10-20% compared with the prior industrialized technology, and the total chromium content of the iron slag is reduced to be less than or equal to 0.5%;
(2) the invention does not add any auxiliary material, the slag discharge is greatly reduced, and no dust and waste gas exist; the produced iron slag is 0.6 ton per ton of product, which is only 1/4 produced by the calcium roasting method, and the iron slag has simple components and is easy to be comprehensively utilized;
(3) the invention can realize the comprehensive utilization of other valuable elements Fe-Al-Mg of chromium ore besides the main element chromium;
(4) the alkali circulation and separation technology greatly reduces the production energy consumption, simplifies the production process, reduces the equipment investment, improves the industrial operability and reduces the production cost;
(5) the invention has mild reaction conditions and strong operability of industrial implementation;
(6) the potassium chromate product of the present invention has high chemical activity and no crystal water, and the performance of the potassium chromate product as a raw material for preparing other chromium series products is superior to that of sodium chromate.
Drawings
FIG. 1 is a schematic view of the process of the present invention.
Detailed description of the preferred embodiments
Example 1:
please refer to the attached drawings. Removing part of water from the KOH solution circularly returned to the reaction kettle, heating to 250 ℃, adding 95 percent of chromite with the particle size less than 200 meshes, adding potassium peroxide, and reacting for 6 hours under the condition of complete mixing, wherein the weight ratio of KOH to ore is 2: 1; obtaining a mixed reaction product containing alkali liquor, chromium salt and iron slag; conversion of chromiumThe rate is more than 99%. Leaching the mixed reaction product by using an iron slag washing solution, wherein the temperature after leaching is 80 ℃; separating potassium chromate coarse crystals from the leaching slurry at 60 ℃, and filtering and separating iron slag andalkali liquor; dissolving the potassium chromate coarse crystal in water, and filtering to remove a small amount of iron slag; adding carbon dioxide into the potassium chromate solution to adjust the pH value to 6, and separating and removing impurities to obtain a pure potassium chromate solution; evaporating, crystallizing, aging, filtering and drying the purified potassium chromate solution to obtain a crystallization mother solution and potassium chromate crystals, wherein the purity of the potassium chromate crystals is 99.8 percent, and the potassium chromate crystals contain 0.05 percent of Al, 0.02 percent of Fe0.02 percent of CO3 2-0.03 percent (calculated by simple substance) meets the requirement of qualified products. And carrying out three-stage countercurrent washing on the iron slag, wherein the iron slag after drying contains 0.060 percent of total chromium, 1.2 percent of K, 27.4 percent of total Fe and 13.5 percent of Mg (calculated by simple substances).
Example 2:
please refer to the attached drawings. Removing part of water from the KOH solution circularly returned to the reaction kettle, heating to 320 ℃, adding 95% of chromite with the particle size less than 200 meshes, introducing air, and reacting for 3 hours under the condition of complete mixing, wherein the weight ratio of KOH to ore is 4: 1, so as to obtain a mixed reaction product containing alkali liquor, chromium salt and iron slag; the chromium conversion rate is more than 99 percent. Leaching the mixed reaction product by using an iron slag washing solution, wherein the temperature after leaching is 140 ℃; separating potassium chromate coarse crystals from the leaching slurry at 110 ℃, and filtering and separating iron slag and alkali liquor; dissolving the potassium chromate coarse crystal in water, and filtering to remove a small amount of iron slag; adding potassium dichromate into the potassium chromate solution to adjust the pH value to 7, and filtering and separating to remove impurities to obtain a pure potassium chromate solution; evaporating, crystallizing, aging, filtering and drying the purified potassium chromate solution to obtain a crystallization mother solution and potassium chromate crystals, wherein the purity of the potassium chromate crystal product is 99.7 percent, and the potassium chromate crystal product contains 0.06 percent of Al, 0.03 percent of Fe and 0.03 percent of CO3 2-0.03 percent (calculated by simple substance) meets the requirement of qualified products. Five-stage reversal of the iron slagAfter the iron slag is washed by flow and dried, the total chromium content of the iron slag is 0.090 percent, the K content is 0.8 percent, the total Fe content is 25.4 percent, and the Mg content is 15.5 percent (calculated by simple substances).
Example 3:
please refer to the attached drawings. After part of water in the KOH solution circularly returned to the reaction kettle is removed, the temperature is raised to 400 ℃, and 95 percent of the KOH solution is addedAdding potassium nitrate into chromite with the particle size less than 200 meshes, and reacting for 1 hour under the condition of complete mixing, wherein the weight ratio of KOH to ore is 6: 1, so as to obtain a mixed reaction product containing alkali liquor, chromium salt and iron slag; the chromium conversion rate is more than 99 percent. Leaching the mixed reaction product by using an iron slag washing solution, wherein the temperature after leaching is 180 ℃; separating potassium chromate coarse crystals from the leaching slurry at 120 ℃, and filtering and separating iron slag and alkali liquor; adding water into the potassium chromate coarse crystals to dissolve the potassium chromate coarse crystals in the crystallization mother liquor in the embodiment 2, and filtering to remove a small amount of iron slag; adding chromic anhydride into the potassium chromate solution to adjust the pH value to 8, filtering and separating to remove impurities to obtain a pure potassium chromate solution; evaporating, crystallizing, aging, filtering and drying the purified potassium chromate solution to obtain a crystallization mother solution and potassium chromate crystals, wherein the purity of the potassium chromate crystal product is 99.8 percent, and the potassium chromate crystal product contains 0.04 percent of Al, 0.02 percent of Fe and CO3 2-0.04 percent (calculated by simple substance) to meet the requirement of qualified products. And carrying out three-stage countercurrent washing on the iron slag, wherein the iron slag after drying contains 0.040% of total chromium, 0.6% of K, 26.8% of total Fes and 11.3% of Mg (calculated by simple substances).
Claims (8)
1. A clean production method of potassium chromate is characterized by comprising the following steps: the chromite is subjected to oxidative decomposition in a liquid phase flowing medium of KOH, and potassium chromate coarse crystals are separated from the leaching slurry and then purified to obtain a potassium chromate product, wherein the method comprises the following steps:
1) chromite reacts with stoichiometric oxidant in a liquid medium of KOH to obtain a mixed reaction product containing alkali liquor, chromium salt and iron slag; wherein the weight ratio of KOH to ore is 2: 1-6: 1; the oxidant is air, oxygen, potassium nitrate or potassium peroxide;
2) leaching the mixed reaction product obtained in the step 1) with water, or iron slag washing liquid obtained after washing the iron slag obtained in the step 1), or a mixture of the two to obtain leaching slurry;
3) carrying out phase separation on the leaching slurry obtained in thestep 2) to respectively obtain potassium chromate coarse crystals, iron slag and alkali liquor;
4) dissolving the potassium chromate coarse crystal obtained in the step 3) with water, and filtering to remove insoluble impurities to obtain a potassium chromate solution;
5) adjusting the pH value of the potassium chromate solution obtained in the step 4) to 5-8 by using an acidifying agent, and separating and removing soluble impurities in the solution to obtain a pure potassium chromate solution; the acidifier is inorganic acid, acid gas, chromic anhydride, potassium dichromate, potassium bicarbonate or potassium bisulfate; the acid gas is carbon dioxide, sulfur dioxide or nitrogen oxide.
2. The method of claim 1, further comprising: and a step 6) is further carried out after the step 5), wherein the pure potassium chromate solution obtained in the step 5) is heated and evaporated, heat preservation, aging, filtering and drying are carried out, a pure potassium chromate crystal product and a crystallization mother liquor are obtained, and the crystallization mother liquor is returned to the step 4) and used for dissolving the potassium chromate coarse crystals.
3. The method of claim 1, further comprising: the iron slag washing liquid in the step 2) is used for carrying out multi-stage countercurrent washing on the iron slag by using water, the number of stages of the countercurrent washing is 3-5, and the washing temperature is 50-90 ℃.
4. The method of claim 1, further comprising: and returning the alkali liquor obtained in the step 3) to the step 1) for decomposing the chromite.
5. The method of claim 1, further comprising: the oxidative decomposition temperature of the chromite in the step 1) is 250-400 ℃, and the reaction time is 1-6 hours.
6. The method of claim 1, further comprising: the temperature after leaching in the step 2) is 80-180 ℃.
7. The method of claim 1, further comprising: the separation temperature of the step 3) is 60-120 ℃.
8. The method of claim 1, further comprising: the dissolving temperature of the step 4) is 30-90 ℃, and the concentration of potassium chromate is 20-50 wt%.
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| CNB011416831A CN1162330C (en) | 2001-10-08 | 2001-10-08 | Clean production method of potassium chromate |
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| CNB011416831A CN1162330C (en) | 2001-10-08 | 2001-10-08 | Clean production method of potassium chromate |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US7220394B2 (en) * | 2002-10-30 | 2007-05-22 | Council Of Scientific And Industrial Research | Process for simultaneous recovery of chromium and iron from chromite ore processing residue |
| WO2004083123A1 (en) * | 2003-03-19 | 2004-09-30 | Institute Of Process Engineering Chinese Academy Of Sciences | Method for production of alkali metal chromates |
| CN101481144B (en) * | 2008-01-09 | 2011-04-20 | 中国科学院过程工程研究所 | Clean production method for preparing potassium chromate from chromic iron |
| CN102092786B (en) * | 2009-12-10 | 2014-04-02 | 中国科学院过程工程研究所 | Method for cleanly preparing vanadium oxides |
| CN102127654B (en) * | 2010-01-13 | 2013-01-23 | 中国科学院过程工程研究所 | Method for decomposing chromium-containing vanadium slag by using sodium hydroxide molten salt |
| CN101817560A (en) * | 2010-04-07 | 2010-09-01 | 中国科学院过程工程研究所 | Methods for removing calcium and magnesium alkaline-earth metal ions contained in chromate solution by adopting ion exchange resin |
| CN102139921A (en) * | 2011-01-27 | 2011-08-03 | 重庆昌元化工有限公司 | Preparation method for producing chromate by continuous liquid-phase oxidation reaction tower |
| CN103183384B (en) * | 2013-03-29 | 2016-08-10 | 中国科学院过程工程研究所 | The method that a kind of preroast strengthening sub-molten salt decomposes chromite |
| CN104195346B (en) * | 2014-09-15 | 2017-04-12 | 中国科学院过程工程研究所 | Clean process method for efficiently extracting chromium in extracted vanadium tailings |
| CN109456151A (en) * | 2017-09-06 | 2019-03-12 | 靳跃春 | The method for preparing the oxidant containing Cr VI |
| CN107963913A (en) * | 2017-11-10 | 2018-04-27 | 中国天辰工程有限公司 | The wash mill and washing methods of a kind of ulexite |
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2001
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