CN108636980B - Zero-emission process for treating titanium chloride slag - Google Patents
Zero-emission process for treating titanium chloride slag Download PDFInfo
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- CN108636980B CN108636980B CN201810364367.XA CN201810364367A CN108636980B CN 108636980 B CN108636980 B CN 108636980B CN 201810364367 A CN201810364367 A CN 201810364367A CN 108636980 B CN108636980 B CN 108636980B
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- 238000000034 method Methods 0.000 title claims abstract description 66
- 239000002893 slag Substances 0.000 title claims abstract description 47
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 title claims abstract description 28
- 239000012528 membrane Substances 0.000 claims abstract description 88
- 239000007788 liquid Substances 0.000 claims abstract description 41
- 238000000926 separation method Methods 0.000 claims abstract description 26
- 150000003839 salts Chemical class 0.000 claims abstract description 22
- 238000001556 precipitation Methods 0.000 claims abstract description 21
- 239000012535 impurity Substances 0.000 claims abstract description 19
- 238000002386 leaching Methods 0.000 claims abstract description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 150000002500 ions Chemical class 0.000 claims abstract description 13
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 10
- 238000000108 ultra-filtration Methods 0.000 claims abstract description 9
- 229910001385 heavy metal Inorganic materials 0.000 claims abstract description 8
- 238000000746 purification Methods 0.000 claims abstract description 8
- 238000001471 micro-filtration Methods 0.000 claims abstract description 7
- 239000004566 building material Substances 0.000 claims abstract description 4
- 238000005374 membrane filtration Methods 0.000 claims abstract description 3
- 238000001728 nano-filtration Methods 0.000 claims description 52
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 37
- 238000001223 reverse osmosis Methods 0.000 claims description 31
- 239000002002 slurry Substances 0.000 claims description 25
- 239000000706 filtrate Substances 0.000 claims description 20
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 15
- 238000001914 filtration Methods 0.000 claims description 13
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 13
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 12
- 239000000919 ceramic Substances 0.000 claims description 12
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 10
- 238000000909 electrodialysis Methods 0.000 claims description 9
- 239000011780 sodium chloride Substances 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 5
- 230000001376 precipitating effect Effects 0.000 claims description 4
- 238000004062 sedimentation Methods 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 239000002994 raw material Substances 0.000 claims description 3
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims description 2
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 2
- 239000002033 PVDF binder Substances 0.000 claims description 2
- 239000004695 Polyether sulfone Substances 0.000 claims description 2
- 239000004743 Polypropylene Substances 0.000 claims description 2
- 239000004793 Polystyrene Substances 0.000 claims description 2
- 238000010306 acid treatment Methods 0.000 claims description 2
- 229910001422 barium ion Inorganic materials 0.000 claims description 2
- 229910001424 calcium ion Inorganic materials 0.000 claims description 2
- 238000005119 centrifugation Methods 0.000 claims description 2
- 230000005484 gravity Effects 0.000 claims description 2
- 229910010272 inorganic material Inorganic materials 0.000 claims description 2
- 239000011147 inorganic material Substances 0.000 claims description 2
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 2
- 230000014759 maintenance of location Effects 0.000 claims description 2
- 229910001437 manganese ion Inorganic materials 0.000 claims description 2
- 239000011368 organic material Substances 0.000 claims description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 2
- 229910001427 strontium ion Inorganic materials 0.000 claims description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 abstract description 23
- 239000007787 solid Substances 0.000 abstract description 12
- 239000004408 titanium dioxide Substances 0.000 abstract description 11
- 239000003513 alkali Substances 0.000 abstract description 10
- 239000004568 cement Substances 0.000 abstract description 3
- 239000002910 solid waste Substances 0.000 abstract description 3
- 239000012141 concentrate Substances 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 50
- 238000005660 chlorination reaction Methods 0.000 description 12
- 229910052782 aluminium Inorganic materials 0.000 description 10
- 229910052710 silicon Inorganic materials 0.000 description 10
- 229910021645 metal ion Inorganic materials 0.000 description 7
- 238000003756 stirring Methods 0.000 description 6
- 239000002351 wastewater Substances 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 239000012267 brine Substances 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 4
- 230000008025 crystallization Effects 0.000 description 4
- 238000006386 neutralization reaction Methods 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 4
- 229910052719 titanium Inorganic materials 0.000 description 4
- 239000010936 titanium Substances 0.000 description 4
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 238000003843 chloralkali process Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002006 petroleum coke Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 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
- 229910052788 barium Inorganic materials 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 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
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 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 1
- 229910001510 metal chloride Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000003204 osmotic effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B5/00—Operations not covered by a single other subclass or by a single other group in this subclass
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
- C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
- C02F2101/206—Manganese or manganese compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
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- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention belongs to the field of titanium dioxide post-treatment, and particularly discloses a zero-emission process for treating titanium chloride slag, which comprises the following steps: (1) alkaline leaching; (2) solid-liquid separation; (3) secondary precipitation; (4) microfiltration/ultrafiltration membrane filtration; (5) primary membrane purification; (6) membrane concentration; (7) secondary membrane purification; the process aims at treating heavy metal ion impurities and recovering chloride ions in the titanium chloride slag, converts solid waste residues into harmless solids for reusing in building materials such as tiles and cement, and then concentrates and purifies the harmless solids into light salt water for chlor-alkali industry through a membrane separation integrated process.
Description
Technical Field
The invention belongs to the field of titanium dioxide chemical industry by a chlorination process, and particularly relates to a zero-emission process for treating titanium chloride slag.
Background
At present, the methods for producing titanium dioxide mainly include a sulfuric acid method and a chlorination method. The sulfuric acid process is gradually replaced by the chlorination process due to long process, serious pollution and poor product quality.
In the current titanium dioxide production by a chlorination method, the main process comprises the following steps:
a. uniformly mixing a titanium raw material (such as high titanium slag) and a reducing agent (such as petroleum coke), then sending the mixture into a chlorination furnace, and introducing chlorine gas to carry out boiling chlorination at the temperature of 800-1000 ℃;
b. separating and purifying the crude titanium tetrachloride obtained after chlorination to remove impurities such as magnesium, iron, silicon, vanadium and the like to obtain refined titanium tetrachloride;
c. preheating and evaporating the prepared refined titanium tetrachloride liquid to convert the refined titanium tetrachloride liquid into a gas phase, and preheating to 300-500 ℃; meanwhile, a small amount of crystal type transforming agent (such as aluminum trichloride) is added into the vapor phase titanium tetrachloride to be mixed and enter an oxidation furnace to be rapidly mixed with oxygen preheated to more than 1300 ℃ in the oxidation furnace, and oxidation reaction is carried out at the temperature of 1300-1800 ℃ within less than 0.1 second to generate solid phase titanium dioxide;
d. then quickly removing the titanium dioxide solid powder from the reaction zone and quickly removing the heat of reaction;
e. and separating chlorine gas obtained by the reaction in the oxidation furnace through a filter, returning the chlorine gas to the chlorination furnace, synchronously pulping titanium dioxide particle powder collected by the filter into liquid, and sending the liquid to a post-treatment process to prepare the rutile type titanium dioxide finished product.
In the production process of titanium dioxide by a chlorination method, a large amount of dust collecting slag is generated at the bottom of a cyclone separator in a chlorination working section. It is reported that about 0.2 tons of solid slag is produced per 1t of titanium tetrachloride produced, and these solids are producedThe slag mainly comprises metal chloride produced by chlorination reaction, high titanium slag and petroleum coke which are not reacted completely, and the main components of the slag not only comprise KCl, NaCl and MgCl2、CaCl2And the like, and also enriches salts of various metal impurities (aluminum, iron, titanium, cobalt, chromium, manganese, arsenic and vanadium), wherein most of the salts exist in the form of chloride at high temperature, aluminum and silicon exist in the form of oxide, and unreacted carbon exists in the form of simple substance. If the waste residues are directly stacked in the open without being treated, a large amount of chloride in the waste residues is dissolved in water, and the environment is seriously polluted.
For the treatment of titanium chloride slag, no better method is available for foreign materials except for deep well landfill. Domestic enterprises mostly adopt lime slag formed by lime neutralization after water washing to be solidified and sent to a slag yard for stacking or landfill, and no effective method for carrying out harmless treatment or resource utilization on the slag exists at present.
CN106044799 discloses a method for treating titanium chloride slag and filtrate thereof, which is to neutralize the titanium chloride slag with alkali and wash the titanium chloride slag, neutralize and precipitate heavy metal ions, and recycle chloride ions in the form of sodium chloride for use in chlor-alkali industrial brine. The process combines the titanium dioxide process and the chlor-alkali process, not only recycles a large amount of chloride ions, but also treats and precipitates heavy metal ions, and is advanced. There are two problems, however: firstly, a large amount of slag is generated after acid dissolution, and the problem that the filter effect is poor and even water can not be discharged due to too strong and compact adhesion in the filter pressing process is solved; secondly, the pH of the primary filtrate is directly neutralized to more than 12 by adopting alkali for filtration, under the high-alkalinity condition, amphoteric substances such as aluminum, silicon and the like can be dissolved in alkali liquor, the concentration can be higher and higher along with the interception of the nanofiltration membrane, hydrolysis precipitation can occur on the membrane surface, the smooth proceeding of the membrane process is influenced, and the high aluminum and silicon concentration in the nanofiltration feeding results can cause the high aluminum and silicon content in the nanofiltration clear liquid, and the requirements of salt dissolving light salt water of the chlor-alkali process can not be met.
Application number 201710555832.3 discloses a zero discharge process of acid waste water of washing slag in the production process of titanium dioxide by a chlorination method. The method comprises the steps of adding alkali into acid titanium chloride slag wastewater for neutralization and filtration, performing reverse osmosis concentration, and then performing nanofiltration separation to remove multivalent metal ions to obtain brine with the salt content of 12% for electrolyzing caustic soda. The process adopts the idea of the previous patent, but the process of reverse osmosis concentration and nanofiltration membrane desalination seems to be more advanced. However, with careful jostling, several problems remain: firstly, a considerable part of impurity ions remained after the neutralization and precipitation, the pH value of the neutralization and precipitation in the process is 6.5-7, most of impurities such as Al, Si, Fe and the like are precipitated, but the precipitation of polyvalent metal ions such as Zn, Mn, Cu, Ni, Ba, Sr and the like is not complete, and a considerable part of impurity ions still remain in the mixed solution, so that the reverse osmosis concentration degree is limited. Secondly, the concentration of the concentrated salt water of the reverse osmosis membrane is less than 12%, a considerable part of impurity ions still exist in the inlet water of the reverse osmosis membrane due to the problem of pH of the neutralized precipitate, although the ultrafiltration membrane is arranged in front of the reverse osmosis membrane, the ultrafiltration membrane does not intercept ions in the solution, so that the concentration of multivalent metal ions in the inlet water of the reverse osmosis membrane is not reduced, the concentration of the impurity ions is continuously increased along with the concentration, carbonate ions and sulfate ions with high concentration in the solution form precipitate to separate out a membrane surface, the normal operation of the membrane process is influenced, and the concentration of the concentrated salt is not 12% at all. And thirdly, the operating pressure of reverse osmosis is 0.6-1 MPa, so the low pressure cannot counteract the osmotic pressure generated by 12% of salt concentration at all, namely concentrated effluent, and the two are nanofiltration after reverse osmosis, the salt concentration of the nanofiltration effluent is reduced by a certain amount in the nanofiltration process, and even if the salt concentration of a concentrated solution after reverse osmosis reaches 12%, the salt concentration after nanofiltration is lower than 12%.
Disclosure of Invention
The technical scheme of the process is an improved scheme provided for solving the problems in the process, firstly, the concentration of the polyvalent metal ions in the wastewater is further reduced through secondary precipitation, secondly, the polyvalent metal ions in the wastewater are intercepted by a nanofiltration membrane before concentration, so that the concentration of the polyvalent metal ions in the concentrated wastewater is very low, the concentration can reach or exceed 12%, thirdly, hydrochloric acid is adopted to adjust the pH value of the inlet water to be 3-6.5 before membrane concentration, and the risk of precipitation and crystallization in the concentration process is greatly reduced.
In order to realize the purpose of the invention, the invention adopts the following technical scheme:
a zero-emission process for treating titanium chloride slag comprises the following steps:
(1) alkaline leaching: leaching the titanium chloride slag with sodium hydroxide lye to obtain chloride ions, precipitating heavy metal ions in the chloride ions, and adjusting the pH value to 5.5-6.5 to form slag slurry;
(2) solid-liquid separation: carrying out solid-liquid separation on the residue slurry to obtain filter residue and filtrate; the filter residue can be used as raw material for manufacturing building materials such as cement and tiles for recycling;
(3) secondary precipitation: adjusting the pH of the filtrate obtained by solid-liquid separation in the step (2) to 9-10 by using sodium carbonate and sodium hydroxide together, and further precipitating to remove heavy metal ions in the filtrate to form secondary slag slurry;
(4) microfiltration/ultrafiltration membrane filtration: filtering the secondary slag slurry in the step (3) by adopting a microfiltration/ultrafiltration membrane, returning the thick slurry to the step (1), and adjusting the pH of clear liquid to 3-6.5 by adopting hydrochloric acid for the next procedure;
(5) primary membrane purification: performing primary impurity removal filtration on the filtrate obtained after the acid treatment in the step (4) by using a primary nanofiltration membrane to obtain primary nanofiltration membrane concentrated solution and clear solution, and returning the nanofiltration concentrated solution to the step (1);
(6) and (3) membrane concentration: concentrating the nanofiltration clear liquid in the step (5) by using a reverse osmosis membrane or an electrodialysis membrane to obtain a concentrated liquid and a clear liquid, and returning the reverse osmosis clear liquid to the step (1);
(7) secondary membrane purification: and (3) removing impurities from the reverse osmosis concentrated solution by using a nanofiltration membrane to obtain a secondary nanofiltration membrane concentrated solution and a clear solution, wherein the nanofiltration clear solution can be used for dissolving salt water, and the nanofiltration concentrated solution is returned to the step (1).
In the above process, the solid-liquid separation process in step 2 adopts one or more solid-liquid separation means selected from filtration, centrifugation, gravity sedimentation or inclined plate sedimentation.
The membrane used in the step 4 is a microfiltration/ultrafiltration membrane, the material can be inorganic materials such as ceramics, metals and the like, or organic materials such as PES, PVDF, PS, PP and PTFE, and the aperture is 2 nm-1.5 um.
In the steps 5 and 7, the nanofiltration membrane is used for treating MgSO at the normal temperature of 0.75MPa4The retention rate is more than 96%.
In the step 6, the used concentration membrane is a reverse osmosis membrane or an electrodialysis membrane, and the rejection rate of the reverse osmosis membrane to NaCl is more than 98% under the pressure of 1.5MPa and the normal temperature.
Advantageous effects
The process aims at treating heavy metal ion impurities and recovering chloride ions in titanium chloride slag, converts solid waste slag into harmless solid for reusing in building materials such as tiles and cement and the like, and then concentrates and purifies the solid waste slag into light salt water for chlor-alkali industry through a membrane separation integrated process.
(1) The process improvement of secondary precipitation greatly reduces the concentration of polyvalent metal ions in titanium chloride slag wastewater, barium ions are reduced from 2.862 mg/L to 0.545 mg/L, manganese ions are reduced from 36.38 mg/L to 0.068 mg/L, calcium ions are reduced from 114 mg/L to 28.56 mg/L, magnesium ions are reduced from 53.81 mg/L to 31.15 mg/L, and strontium ions are reduced from 0.773 mg/L to 0.373 mg/L;
(2) through the purification of the nanofiltration membrane and the reduction of the pH value of the inlet water before concentration, the concentration of the concentrated membrane is greatly improved, the concentration can be concentrated by more than 10 times at most, the concentration of the brine can reach 122 g/L, the recovery rate of the brine is more than 90%, the membrane concentration process is stable, and the phenomenon of scaling and precipitation is avoided.
(3) Due to the improvement of the concentration process (including electrodialysis when necessary), the concentration of the saline in the concentrated solution is improved, so that the concentration of the salt in the nanofiltration effluent water still reaches 90-115 g/L after the final secondary nanofiltration membrane purification.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention.
The following examples were operated according to the process flow diagram as shown:
example 1
Leaching 60kg of titanium chloride slag by using sodium hydroxide alkali liquor, adjusting the pH value to 6, controlling the solid-liquid ratio to be 1: 15 (weight ratio), stirring and reacting for 10 hours to form neutralized slag slurry, performing solid-liquid separation on the neutralized slag slurry by using a plate-and-frame filter press or a centrifugal machine to obtain solid filter residue, and feeding the filtrate into a secondary precipitation process, wherein the content of sodium chloride in the neutralized filtrate is 5361 mg/L, the volume of the neutralized filtrate is 850L, and the contents of impurities Al and Si are 0.146 mg/L and 0.404 mg/L respectively;
secondary precipitation: adjusting the pH value of clear liquid obtained by the solid-liquid separation of the neutralized slurry by using a ceramic membrane to 10 by using sodium carbonate and sodium hydroxide together, stirring and reacting for 1h to form secondary slurry, filtering the secondary slurry by using a ceramic membrane, controlling the solid content in the concentrated solution to be 3%, returning the concentrated solution to an alkaline leaching process, adjusting the pH value of the clear liquid of the ceramic membrane to 4 by using hydrochloric acid, and then entering a membrane separation process;
the membrane separation process comprises the steps of filtering acid-exchanged filtrate by primary nanofiltration, controlling the operating pressure of the primary nanofiltration membrane to be 2.5-3.5 MPa to obtain primary nanofiltration membrane concentrated solution 165L and clear solution 585L, directly concentrating the primary nanofiltration membrane clear solution by reverse osmosis to obtain concentrated solution 30L when the salt content of the reverse osmosis concentrated solution reaches 12.2%, feeding the reverse osmosis clear solution into a secondary nanofiltration process when the reverse osmosis clear solution is used in an alkaline leaching process, controlling the operating pressure of the secondary nanofiltration to be 2.5-3 MPa to obtain secondary nanofiltration membrane concentrated solution 7.5L and clear solution 22.5L, wherein the salt content is 10.37%, the impurity content is 0.1 mg/L and 0.138 mg/L respectively, and the phenomenon of crystallization and precipitation caused by turbid concentrated solution does not occur in the whole membrane process.
Example 2
Leaching 60kg of titanium chloride slag by using sodium hydroxide alkali liquor, adjusting the pH value to 6.5, controlling the solid-liquid ratio to be 1: 10 (weight ratio), stirring and reacting for 10 hours to form neutralized slag slurry, performing solid-liquid separation on the neutralized slag slurry by adopting a plate-and-frame filter press and a ceramic membrane together to obtain solid filter residue, and feeding the filtrate into a secondary precipitation process, wherein the content of sodium chloride in the neutralized filtrate is 8041 mg/L, the volume is 500L, and the contents of impurities Al and Si are 0.163 mg/L and 0.507 mg/L respectively;
secondary precipitation: adjusting the pH value of clear liquid obtained by the solid-liquid separation of the neutralized slurry ceramic membrane to 9.5 by using sodium carbonate and sodium hydroxide together, stirring and reacting for 2 hours to form secondary slurry, filtering the secondary slurry by using a ceramic membrane, controlling the solid content in the concentrated solution to be 2%, returning the concentrated solution to an alkaline leaching process, adjusting the pH value of the clear liquid of the ceramic membrane to 4.5 by using hydrochloric acid, and entering a membrane separation process;
the membrane separation process comprises the steps of firstly carrying out primary nanofiltration on filtrate after acid exchange, controlling the operating pressure of a primary nanofiltration membrane to be 2.5-3.5 MPa to obtain primary nanofiltration membrane concentrated solution 110L and clear solution 440L, directly carrying out reverse osmosis concentration on the primary nanofiltration membrane clear solution to obtain concentrated solution 30L when the salt content in the reverse osmosis concentrated solution reaches 11.5%, using the reverse osmosis clear solution as an alkaline leaching process, feeding the reverse osmosis concentrated solution into a secondary nanofiltration process, controlling the operating pressure of the secondary nanofiltration to be 2.5-3 MPa to obtain secondary nanofiltration membrane concentrated solution 6L and clear solution 24L, wherein the salt content is 9.8%, the impurity contents are respectively 0.105 mg/L and 0.23 mg/L, and the phenomenon of crystallization precipitation caused by turbid concentrated solution does not occur in the whole membrane process.
Example 3
Leaching 60kg of titanium chloride slag by using sodium hydroxide alkali liquor, adjusting the pH value to 5.5, controlling the solid-liquid ratio to be 1: 12 (weight ratio), stirring and reacting for 10 hours to form neutralized slag slurry, performing solid-liquid separation on the neutralized slag slurry by using a centrifugal machine to obtain solid filter residue, and feeding the filtrate into a secondary precipitation process, wherein the content of sodium chloride in the neutralized filtrate is 6701 mg/L, the volume is 700L, and the contents of impurities Al and Si are 0.12 mg/L and 0.38 mg/L respectively;
secondary precipitation: adjusting the pH value of clear liquid obtained by the solid-liquid separation of the neutralized slurry by using a ceramic membrane to be 9.5 by using sodium carbonate and sodium hydroxide together, stirring and reacting for 1h to form secondary slurry, filtering the secondary slurry by using a ceramic membrane, controlling the solid content in the concentrated solution to be 2.5%, returning the concentrated solution to an alkaline leaching process, adjusting the pH value of the clear liquid of the ceramic membrane to be 5 by using hydrochloric acid, and entering a membrane separation process;
the membrane separation process comprises the steps of filtering acid-exchanged filtrate by primary nanofiltration, controlling the operating pressure of the primary nanofiltration membrane to be 2.5-3.5 MPa to obtain primary nanofiltration membrane concentrated solution 140L and clear solution 560L, concentrating the primary nanofiltration membrane clear solution by reverse osmosis to 5% and then concentrating the reverse osmosis concentrated solution by electrodialysis, obtaining concentrated solution 25L when the salt content in the electrodialysis concentrated solution reaches 15%, using the reverse osmosis and electrodialysis clear solution as an alkaline leaching process, feeding the electrodialysis concentrated solution into a secondary nanofiltration process, controlling the operating pressure of the secondary nanofiltration to be 2.5-3 MPa to obtain secondary nanofiltration membrane concentrated solution 5L and clear solution 20L, wherein the salt content is 12%, the impurity contents are Al and Si contents of 0.093 mg/L and 0.12 mg/L respectively, and the phenomenon of crystallization and precipitation of the concentrated solution does not occur in the whole membrane turbidity process.
Claims (4)
1. A zero-emission process for treating titanium chloride slag is characterized by comprising the following steps: the method comprises the following steps:
(1) alkaline leaching: leaching the titanium chloride slag with sodium hydroxide lye to obtain chloride ions, precipitating heavy metal ions in the chloride ions, and adjusting the pH value to 5.5-6.5 to form slag slurry;
(2) solid-liquid separation: carrying out solid-liquid separation on the residue slurry to obtain filter residue and filtrate;
(3) performing secondary precipitation, namely adjusting the pH value of the filtrate obtained by solid-liquid separation in the step (2) to 9-10 by using sodium carbonate and sodium hydroxide together, further precipitating and removing heavy metal ions in the filtrate to form secondary slag slurry, wherein after the secondary precipitation, barium ions are reduced to 0.545 mg/L from 2.862 mg/L, manganese ions are reduced to 0.068 mg/L from 36.38 mg/L, calcium ions are reduced to 28.56 mg/L from 114 mg/L, magnesium ions are reduced to 31.15 mg/L from 53.81 mg/L, and strontium ions are reduced to 0.373 mg/L from 0.773 mg/L;
(4) microfiltration/ultrafiltration membrane filtration: filtering the secondary slag slurry in the step (3) by adopting a microfiltration/ultrafiltration membrane, returning the thick slurry to the step (1), and adjusting the pH of clear liquid to 3-6.5 by adopting hydrochloric acid for the next procedure;
(5) primary membrane purification: performing primary impurity removal filtration on the filtrate obtained after the acid treatment in the step (4) by using a primary nanofiltration membrane to obtain primary nanofiltration membrane concentrated solution and clear solution, and returning the nanofiltration concentrated solution to the step (1);
(6) and (3) membrane concentration: concentrating the nanofiltration clear liquid obtained in the step (5) by using a reverse osmosis membrane or an electrodialysis membrane to obtain a concentrated liquid and a clear liquid, returning the reverse osmosis clear liquid to the step (1), wherein the used concentration membrane is the reverse osmosis membrane or the electrodialysis membrane, and the rejection rate of the reverse osmosis membrane to NaCl is more than 98% at 1.5MPa and normal temperature;
(7) secondary membrane purification: removing impurities from the reverse osmosis concentrated solution by using a nanofiltration membrane to obtain a secondary nanofiltration membrane concentrated solution and a clear solution, wherein the nanofiltration clear solution can be used for dissolving salt water, and the nanofiltration concentrated solution is returned to the step (1);
in the steps (5) and (7), the nanofiltration membrane is used for MgSO 2 at the normal temperature and 0.75MPa4The retention rate is more than 96%.
2. The zero-emission process for treating titanium chloride slag according to claim 1, which is characterized in that: the filter residue in the step (2) can be reused as a raw material for manufacturing building materials.
3. The zero-emission process for treating titanium chloride slag according to claim 1, which is characterized in that: the solid-liquid separation process in the step (2) adopts one or a combination of solid-liquid separation means of filtration, centrifugation, gravity sedimentation or inclined plate sedimentation.
4. The zero-emission process for treating titanium chloride slag according to claim 1, which is characterized in that: the membrane used in the step (4) is a microfiltration/ultrafiltration membrane, is made of ceramic and metal inorganic materials, and can also be made of PES, PVDF, PS, PP and PTFE organic materials, and the aperture is 2 nm-1.5 um.
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