CN117819574A - Method for removing chromium in recovered NaCl brine in chloride slag - Google Patents
Method for removing chromium in recovered NaCl brine in chloride slag Download PDFInfo
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- CN117819574A CN117819574A CN202311731829.4A CN202311731829A CN117819574A CN 117819574 A CN117819574 A CN 117819574A CN 202311731829 A CN202311731829 A CN 202311731829A CN 117819574 A CN117819574 A CN 117819574A
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- brine
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- slag
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- 239000012267 brine Substances 0.000 title claims abstract description 108
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 title claims abstract description 108
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 title claims abstract description 80
- 239000011651 chromium Substances 0.000 title claims abstract description 41
- 239000002893 slag Substances 0.000 title claims abstract description 40
- 239000011780 sodium chloride Substances 0.000 title claims abstract description 40
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 title claims abstract description 33
- 238000000034 method Methods 0.000 title claims abstract description 31
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims abstract description 25
- 229910052804 chromium Inorganic materials 0.000 title claims abstract description 21
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 52
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 32
- 238000001914 filtration Methods 0.000 claims abstract description 30
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 26
- 150000001875 compounds Chemical class 0.000 claims abstract description 26
- 238000003756 stirring Methods 0.000 claims abstract description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000002002 slurry Substances 0.000 claims abstract description 15
- 239000004408 titanium dioxide Substances 0.000 claims abstract description 15
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000000292 calcium oxide Substances 0.000 claims abstract description 14
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000005660 chlorination reaction Methods 0.000 claims abstract description 13
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 13
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 13
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000000395 magnesium oxide Substances 0.000 claims abstract description 12
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims abstract description 12
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims abstract description 12
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims abstract description 12
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 11
- 239000000203 mixture Substances 0.000 claims abstract description 11
- 239000006227 byproduct Substances 0.000 claims abstract description 9
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 239000003513 alkali Substances 0.000 claims abstract description 4
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 3
- 238000000926 separation method Methods 0.000 claims abstract description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 39
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 26
- 239000002131 composite material Substances 0.000 claims description 26
- 229910001510 metal chloride Inorganic materials 0.000 claims description 13
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 13
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 13
- 239000000919 ceramic Substances 0.000 claims description 12
- 229960002089 ferrous chloride Drugs 0.000 claims description 12
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 claims description 12
- 238000003825 pressing Methods 0.000 claims description 12
- 239000000843 powder Substances 0.000 claims description 6
- 238000005374 membrane filtration Methods 0.000 claims description 4
- 230000003472 neutralizing effect Effects 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 2
- 239000001038 titanium pigment Substances 0.000 claims description 2
- 238000000108 ultra-filtration Methods 0.000 claims description 2
- 239000011550 stock solution Substances 0.000 abstract description 3
- 230000002035 prolonged effect Effects 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 21
- 150000003839 salts Chemical class 0.000 description 12
- 235000010215 titanium dioxide Nutrition 0.000 description 12
- 239000000428 dust Substances 0.000 description 11
- 239000012528 membrane Substances 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 229910052719 titanium Inorganic materials 0.000 description 6
- 239000010936 titanium Substances 0.000 description 6
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 5
- 239000005997 Calcium carbide Substances 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 2
- 239000002006 petroleum coke Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 239000001023 inorganic pigment Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 150000004692 metal hydroxides Chemical class 0.000 description 1
- 239000002480 mineral oil Substances 0.000 description 1
- 235000010446 mineral oil Nutrition 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000012463 white pigment Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/14—Purification
- C01D3/16—Purification by precipitation or adsorption
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/14—Purification
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a method for removing chromium in NaCl brine recovered from chloride slag, which comprises the following steps: (1) Adding alkali into the chloridized slag slurry which is a byproduct of titanium dioxide by a chloridizing method for neutralization, press filtration and separation, removing impurities and concentrating to obtain refined brine; (2) Adding a compound treating agent into the refined brine obtained in the step (1) and stirring to obtain a mixture; the compound treating agent is a mixture of any three or more of calcium oxide, magnesium oxide, silicon dioxide, aluminum oxide and ferric oxide and active carbon, or purified ash; the mass ratio of the compound treating agent to the refined brine is (0.01-0.1) to 1; (3) And (3) filtering and separating the mixture obtained in the step (2) to obtain refined brine with reduced chromium element content. After the refined brine prepared from the chloride slag which is a byproduct of titanium dioxide by the chlorination process is treated by adopting the compound treating agent, the chromium content in the refined brine is reduced to below 0.05mg/l, and the refined brine can be used as the stock solution of the electrolytic tank, so that the service life of the electrolytic tank is prolonged, and the power consumption is reduced.
Description
Technical Field
The invention relates to the technical field of recycling of chloride waste salt resources and purification of chlor-alkali chemical brine, in particular to a method for removing chromium in recovered NaCl brine in chloride slag.
Background
Titanium white is a white inorganic pigment, has the characteristics of optimal hiding power, whiteness, brightness, no toxicity and the like, is recognized as the white pigment with the best performance in the world at present, and is widely applied to industries of paint, plastics, papermaking, printing ink, chemical fiber, rubber, cosmetics and the like.
At present, the foreign titanium dioxide is mainly produced by using the titanium dioxide by a chlorination process, and the domestic titanium dioxide is mainly produced by using a sulfuric acid process, so that the titanium dioxide has the advantages of better product quality, less three wastes discharge, easy expansion of devices and the like based on the chlorination process, and becomes the development trend of the domestic titanium dioxide industry. The titanium dioxide (boiling type) is produced by a chlorination method, which is mainly characterized in that after titanium raw materials and petroleum coke are mixed, chlorination reaction is carried out in a chlorination furnace to generate a mixture containing titanium tetrachloride, and the mixture coming out of the top of the chlorination furnace is separated into slag and dust through a cyclone dust collector to obtain crude titanium tetrachloride; VOCl contained in crude titanium tetrachloride 3 Removing vanadium by reacting the same impurities with mineral oil and the like, and rectifying to obtain refined titanium tetrachloride; the refined titanium tetrachloride reacts with oxygen at high temperature to generate titanium dioxide base material, and then the high-grade rutile titanium dioxide is obtained after post-treatment. In the production process of titanium dioxide by the chlorination process, a large amount of dust collection slag is generated at the bottom of a cyclone separator in the chlorination section, and the solid slag mainly consists of metal chloride produced by chlorination reaction, high titanium slag without complete reaction and petroleum coke, and the main components not only comprise FeCl 2 、MgCl 2 、CaCl 2 And the like, are also enriched with salts of various metal impurities (aluminum, titanium, cobalt, chromium, manganese, arsenic, vanadium), most of which exist in the form of chlorides at high temperature, aluminum and silicon exist in the form of oxides, and unreacted carbon exists in the form of simple substances, which are known in the art as chloride slag. Neutralizing with caustic soda and sodium carbonate to form metal hydroxide and carbonate precipitate, press filtering to separate to form filter cake and coarse salt solution, refiningAnd (5) preparing refined brine serving as an electrolyte tank stock solution. However, domestic titanium raw materials are difficult to meet the production requirements of domestic chloride process enterprises due to high calcium and magnesium content, and high-quality titanium raw materials are required to be imported from abroad, but the foreign titanium raw materials have the problem that nonferrous metal elements exceed standards, such as manganese, chromium, aluminum and other metal elements. In the actual production process, the chromium content of the refined brine solution is still out of standard, and the operation of the electrolytic tank can be influenced by the out-of-standard chromium element.
Disclosure of Invention
The invention aims to provide a method for removing chromium in NaCl brine recovered from chloride slag.
The technical scheme adopted for solving the technical problems is as follows: a method for removing chromium in NaCl brine from chloride slag, comprising the following steps:
(1) Adding alkali into the chloridized slag slurry which is a byproduct of titanium dioxide by a chloridizing method for neutralization, press filtration and separation, removing impurities and concentrating to obtain refined brine;
(2) Adding a compound treating agent into the refined brine obtained in the step (1) and stirring to obtain a mixture; the compound treating agent is a mixture of any three or more of calcium oxide, magnesium oxide, silicon dioxide, aluminum oxide and ferric oxide and active carbon, or purified ash; the mass ratio of the compound treating agent to the refined brine is (0.01-0.1) to 1;
(3) And (3) filtering and separating the mixture obtained in the step (2) to obtain refined brine with reduced chromium element content.
The tail gas generated by the closed calcium carbide furnace contains a large amount of dust, and the dust can be recycled by being treated by purifying equipment under the normal condition. During purification treatment, the tail gas is subjected to heat exchange, cooling and dust removal through an air cooler, then enters a bag-type dust remover for fine filtration, and solid dust collected through the heat exchanger and the bag-type dust remover is generally called as purification dust, and is called as purification dust for short; the purified ash contains a large amount of carbon powder, calcium oxide powder and a small amount of calcium carbide powder, sulfur, phosphorus and other substances.
Further, the composite treatment agent comprises the following components: 8-25% of active carbon, 58-65% of calcium oxide, 5-8% of silicon dioxide, 1-5% of magnesium oxide, 1-3% of aluminum oxide and 0-1% of ferric oxide.
Furthermore, the composite treating agent is powder, and the particle size in the powder is smaller than 200 meshes and accounts for more than 65 percent.
And (2) neutralizing the chloridized slag slurry of the by-product of the titanium pigment by the chloridizing method by adding an alkaline precipitant, separating crude brine by diaphragm filter pressing, and purifying and concentrating the crude brine to obtain refined brine.
Further, the alkaline precipitant added in the step (1) is caustic soda or sodium carbonate.
Further, the sodium chloride content in the crude brine in the step (1) is 50-110 g/l, and the pH is 6.5-8.5.
Further, the content of sodium chloride in the refined brine in the step (1) is 150-310 g/l, and the pH is 10-14.
Further, the ratio of ferrous chloride in the chloride slag of the byproduct of the titanium dioxide by the chlorination process in the step (1) to the metal chloride is more than or equal to 60 percent.
Further, the stirring time after the compound treating agent is added in the step (2) is 0.2-1 h.
And (3) filtering and separating in the step (2) by adopting ceramic membrane filtration or ultrafiltration membrane filtration.
The beneficial effects of the invention are as follows: after the refined brine prepared from the chloride slag which is a byproduct of titanium dioxide by the chlorination process is treated by adopting the compound treating agent, the chromium content in the refined brine is reduced to below 0.05mg/l, and the refined brine can be used as the stock solution of the electrolytic tank, so that the service life of the electrolytic tank is prolonged, and the power consumption is reduced.
Detailed Description
The invention is further illustrated below with reference to examples.
Example 1:
(1) The ferrous chloride in the chloride slag slurry accounts for 61% of the metal chloride, caustic soda and sodium carbonate are added to adjust the pH value to 7, coarse brine is obtained by filter pressing, and the sodium chloride content of the coarse brine is 55g/l;
(2) The crude brine is purified and concentrated to obtain refined brine, the content of sodium chloride in the refined brine is 250g/l, the pH is 13, and the Cr content is 0.49mg/l;
(3) Typical components of the composite treating agent comprise 22.7% of active carbon, 64.3% of calcium oxide, 6.5% of silicon dioxide, 3.4% of magnesium oxide, 2.2% of aluminum oxide and 0.9% of ferric oxide; the material granularity of the composite treating agent is less than 200 meshes and the material granularity accounts for 68 percent; adding the compound treating agent into refined salt water according to the mass ratio of 0.02:1, and stirring for 1h;
(4) After stirring, filtering and separating by adopting a ceramic membrane, wherein the Cr content of the refined brine after filtering is 0.03mg/l.
Example 2:
(1) The ferrous chloride in the chloride slag slurry accounts for 65 percent of metal chloride, caustic soda and sodium carbonate are added to adjust the pH value to 6.5, coarse brine is prepared by filter pressing, and the sodium chloride content of the coarse brine is 63g/l;
(2) The crude brine is purified and concentrated to obtain refined brine, the content of sodium chloride in the refined brine is 296g/l, the pH value is 10, and the Cr content is 0.47mg/l;
(3) The compound treating agent is calcium carbide purifying ash; the material granularity of the composite treating agent is less than 200 meshes and the material granularity accounts for 65 percent; adding the compound treating agent into refined salt water according to a mass ratio of 0.05:1, and stirring for 0.2h;
(4) After stirring, filtering and separating by adopting a ceramic membrane, wherein the Cr content of the refined brine after filtering is 0.04mg/l.
Example 3:
(1) The ferrous chloride in the chloride slag slurry accounts for 61 percent of metal chloride, caustic soda and sodium carbonate are added to adjust the pH value to 7.2, coarse brine is prepared by filter pressing, and the sodium chloride content of the coarse brine is 76g/l;
(2) The crude brine is purified and concentrated to obtain refined brine, the content of sodium chloride in the refined brine is 310g/l, the pH value is 14, and the Cr content is 0.45mg/l;
(3) Typical components of the composite treating agent comprise 24.5% of activated carbon, 64.1% of calcium oxide, 6.2% of silicon dioxide, 2.6% of magnesium oxide, 1.8% of aluminum oxide and 0.8% of ferric oxide; the material granularity of the composite treating agent is less than 200 meshes and the material granularity accounts for 67 percent; adding the compound treating agent into refined salt water according to the mass ratio of 0.1:1, and stirring for 0.8h;
(4) After stirring, filtering and separating by adopting a ceramic membrane, wherein the Cr content of the refined brine after filtering is 0.03mg/l.
Example 4:
(1) The ferrous chloride in the chloride slag slurry accounts for 55 percent of metal chloride, caustic soda and sodium carbonate are added to adjust the pH value to 7.2, coarse brine is prepared by filter pressing, and the sodium chloride content of the coarse brine is 76g/l;
(2) The crude brine is purified and concentrated to obtain refined brine, the content of sodium chloride in the refined brine is 264g/l, the pH is 12, and the content of Cr is 0.54mg/l;
(3) Typical components of the composite treating agent comprise 18.2% of activated carbon, 63.1% of calcium oxide, 7.9% of silicon dioxide, 4.8% of magnesium oxide, 2.9% of aluminum oxide and 1.0% of ferric oxide; the material granularity of the composite treating agent is less than 200 meshes and the material granularity accounts for 68 percent; adding the compound treating agent into refined salt water according to a mass ratio of 0.02:1, and stirring for 0.5h;
(4) After stirring, filtering and separating by adopting a ceramic membrane, wherein the Cr content of the refined brine after filtering is 0.06mg/l.
Comparative example 1: (the compounding ratio of the composite treating agent is not within the preferable range)
(1) The ferrous chloride in the chloride slag slurry accounts for 67 percent of metal chloride, caustic soda and sodium carbonate are added to adjust the pH value to 8, coarse brine is prepared by filter pressing, and the sodium chloride content of the coarse brine is 85g/l;
(2) The crude brine is purified and concentrated to obtain refined brine, the content of sodium chloride in the refined brine is 283g/l, the pH value is 10, and the Cr content is 0.44mg/l;
(3) Typical components of the composite treating agent comprise 9.1% of active carbon, 45.3% of calcium oxide, 9.6% of silicon dioxide, 19.1% of magnesium oxide, 12.1% of aluminum oxide and 5.2% of ferric oxide; the material granularity of the composite treating agent is less than 200 meshes and the material granularity accounts for 64 percent; adding the compound treating agent into refined salt water according to the mass ratio of 0.09:1, and stirring for 0.5h;
(4) After stirring, filtering and separating by adopting a ceramic membrane, wherein the Cr content of the refined brine after filtering is 0.11mg/l.
Comparative example 2: (crude brine is not in the preferred range)
(1) The ferrous chloride in the chloride slag slurry accounts for 64 percent of metal chloride, caustic soda and sodium carbonate are added to adjust the pH value to 5.5, coarse brine is prepared by filter pressing, and the sodium chloride content of the coarse brine is 98g/l;
(2) The crude brine is purified and concentrated to obtain refined brine, the content of sodium chloride in the refined brine is 256g/l, the pH is 13, and the Cr content is 0.47mg/l;
(3) The compound treating agent is calcium carbide purifying ash; the material granularity of the composite treating agent is less than 200 meshes and the material granularity accounts for 63 percent; adding the compound treating agent into refined salt water according to the mass ratio of 0.1:1, and stirring for 0.9h;
(4) After stirring, filtering and separating by adopting a ceramic membrane, wherein the Cr content of the refined brine after filtering is 0.09mg/l.
Comparative example 3: (no activated carbon was used in the composite treatment agent, the same as in example 1)
(1) The ferrous chloride in the chloride slag slurry accounts for 61% of the metal chloride, caustic soda and sodium carbonate are added to adjust the pH value to 7, coarse brine is obtained by filter pressing, and the sodium chloride content of the coarse brine is 55g/l;
(2) The crude brine is purified and concentrated to obtain refined brine, the content of sodium chloride in the refined brine is 250g/l, the pH is 13, and the Cr content is 0.49mg/l;
(3) Typical component contents of the composite treating agent are 74.3% of calcium oxide, 9.5% of silicon dioxide, 8.4% of magnesium oxide, 4.1% of aluminum oxide and 3.7% of ferric oxide; the material granularity of the composite treating agent is less than 200 meshes and the material granularity accounts for 68 percent; adding the compound treating agent into refined salt water according to the mass ratio of 0.02:1, and stirring for 1h;
(4) After stirring, filtering and separating by adopting a ceramic membrane, wherein the Cr content of the refined brine after filtering is 0.21mg/l.
Comparative example 4: (there are only two kinds of oxides in the composite treating agent, otherwise the same as in example 1)
(1) The ferrous chloride in the chloride slag slurry accounts for 61% of the metal chloride, caustic soda and sodium carbonate are added to adjust the pH value to 7, coarse brine is obtained by filter pressing, and the sodium chloride content of the coarse brine is 55g/l;
(2) The crude brine is purified and concentrated to obtain refined brine, the content of sodium chloride in the refined brine is 250g/l, the pH is 13, and the Cr content is 0.49mg/l;
(3) Typical component content of the composite treating agent is 25.7% of active carbon, 67.3% of calcium oxide and 7% of silicon dioxide; the material granularity of the composite treating agent is less than 200 meshes and the material granularity accounts for 68 percent; adding the compound treating agent into refined salt water according to the mass ratio of 0.02:1, and stirring for 1h;
(4) After stirring, filtering and separating by adopting a ceramic membrane, wherein the Cr content of the refined brine after filtering is 0.16mg/l.
Comparative example 5: (the amount of the composite treatment agent to be added is smaller than the range, otherwise the same as in example 1)
(1) The ferrous chloride in the chloride slag slurry accounts for 61% of the metal chloride, caustic soda and sodium carbonate are added to adjust the pH value to 7, coarse brine is obtained by filter pressing, and the sodium chloride content of the coarse brine is 55g/l;
(2) The crude brine is purified and concentrated to obtain refined brine, the content of sodium chloride in the refined brine is 250g/l, the pH is 13, and the Cr content is 0.49mg/l;
(3) Typical components of the composite treating agent comprise 22.7% of active carbon, 64.3% of calcium oxide, 6.5% of silicon dioxide, 3.4% of magnesium oxide, 2.2% of aluminum oxide and 0.9% of ferric oxide; the material granularity of the composite treating agent is less than 200 meshes and the material granularity accounts for 68 percent; adding the compound treating agent into refined salt water according to the mass ratio of 0.007:1, and stirring for 1h;
(4) After stirring, filtering and separating by adopting a ceramic membrane, wherein the Cr content of the refined brine after filtering is 0.10mg/l.
Comparative example 6: (the amount of the composite treatment agent to be added is greater than the range, otherwise the same as in example 1)
(1) The ferrous chloride in the chloride slag slurry accounts for 61% of the metal chloride, caustic soda and sodium carbonate are added to adjust the pH value to 7, coarse brine is obtained by filter pressing, and the sodium chloride content of the coarse brine is 55g/l;
(2) The crude brine is purified and concentrated to obtain refined brine, the content of sodium chloride in the refined brine is 250g/l, the pH is 13, and the Cr content is 0.49mg/l;
(3) Typical components of the composite treating agent comprise 22.7% of active carbon, 64.3% of calcium oxide, 6.5% of silicon dioxide, 3.4% of magnesium oxide, 2.2% of aluminum oxide and 0.9% of ferric oxide; the material granularity of the composite treating agent is less than 200 meshes and the material granularity accounts for 68 percent; adding the compound treating agent into refined salt water according to the mass ratio of 0.2:1, and stirring for 1h;
(4) After stirring, filtering and separating by adopting a ceramic membrane, wherein the Cr content of the refined brine after filtering is 0.05mg/l.
Claims (10)
1. A method for removing chromium in NaCl brine from chloride slag, which is characterized by comprising the following steps:
(1) Adding alkali into the chloridized slag slurry which is a byproduct of titanium dioxide by a chloridizing method for neutralization, press filtration and separation, removing impurities and concentrating to obtain refined brine;
(2) Adding a compound treating agent into the refined brine obtained in the step (1) and stirring to obtain a mixture; the compound treating agent is a mixture of any three or more of calcium oxide, magnesium oxide, silicon dioxide, aluminum oxide and ferric oxide and active carbon, or purified ash; the mass ratio of the compound treating agent to the refined brine is (0.01-0.1) to 1;
(3) And (3) filtering and separating the mixture obtained in the step (2) to obtain refined brine with reduced chromium element content.
2. The method for removing chromium from the recycled NaCl brine in the chloride slag according to claim 1, wherein: the compound treating agent comprises the following components: 8-25% of active carbon, 58-65% of calcium oxide, 5-8% of silicon dioxide, 1-5% of magnesium oxide, 1-3% of aluminum oxide and 0-1% of ferric oxide.
3. The method for removing chromium from the recycled NaCl brine in the chloride slag according to claim 1 or 2, characterized in that: the composite treating agent is powder, and the particle size in the powder is smaller than 200 meshes and accounts for more than 65 percent.
4. The method for removing chromium from NaCl brine recovered from a slag chloride according to claim 1, wherein: and (2) neutralizing the chloridized slag slurry of the by-product of the titanium pigment by the chloridizing method by adding an alkaline precipitant, separating crude brine by diaphragm filter pressing, and purifying and concentrating the crude brine to obtain refined brine.
5. The method for removing chromium from NaCl brine recovered from chloride slag according to claim 4, wherein: the alkaline precipitant added in the step (1) is caustic soda or sodium carbonate.
6. The method for removing chromium from NaCl brine recovered from chloride slag according to claim 4, wherein: the sodium chloride content in the crude brine in the step (1) is 50-110 g/l, and the pH value is 6.5-8.5.
7. The method for removing chromium from NaCl brine recovered from chloride slag according to claim 4, wherein: the content of sodium chloride in the refined brine in the step (1) is 150-310 g/l, and the pH value is 10-14.
8. The method for removing chromium from NaCl brine recovered from a slag chloride according to claim 1, wherein: the ratio of ferrous chloride in the chloride slag of the byproduct titanium dioxide by the chlorination process in the step (1) to the metal chloride is more than or equal to 60 percent.
9. The method for removing chromium from NaCl brine recovered from a slag chloride according to claim 1, wherein: and (3) stirring for 0.2-1 h after adding the compound treating agent in the step (2).
10. The method for removing chromium from NaCl brine recovered from a slag chloride according to claim 1, wherein: and (3) filtering and separating in the step (3) by adopting ceramic membrane filtration or ultrafiltration membrane filtration.
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