Process of producing calcium sulfate crystal whiskers from chloride-containing wastewater generated in chloride process titanium dioxide production

Technical Field

The invention relates to a titanium dioxide Pomolio containing chloride waste water for the production of calcium sulfate whisker, in particular to a chlorination process titanium dioxide containing chloride waste water to produce calcium sulfate whisker at the same time the co-production of sodium chloride for recovery industry.

Background Art

Calcium sulfate whisker has excellent mechanical properties, good compatibility, excellent smoothness, the characteristics of good regeneration performance, are mainly applied to papermaking, $increasing of the composite material, friction material, environmental engineering filtering, asphalt modification and improve the adhesion of the coating and paint, the temperature resistance and insulating quality. At present, calcium sulfate whisker method is the production of gypsum as the raw material,   the manual control to the growth of single crystal form, has a uniform transverse cross-section, the appearance of the complete, perfect internal structure of the fibrous (whisker) single crystal.

Chlorination process titanium dioxide is the world's most advanced production techniques of, Pomolio Titanias high-grade product, little three waste, is friendly to the environment, are internally to encourage the development of the technology of producing titanium dioxide. However in Pomolio Titanias production process, in the course of producing titanium tetrachloride outputs chlorine slagging enriched, mainly contains FeCl₂, FeCl₃, AlCl₃, CaCl₂, MnCl₂ chloride, such as, the need for harmless processing. Usually chlorine slagging the innoxious treatment of the hair brush rotate counterclockwise with water, and adding lime to alkaline, pressure filtration, the filter residue component is Fe (OH)₃, Mn (OH)₂, mg (OH)₂, Al (OH)₃ and other industrial waste, the raw material of cement piles in or smoldered. Its alkaline filtrate containing mainly CaCl₂, NaCl and other soluble chloride. The high chloride waste water outside the building along the enterprises Titanias Pomolio being directly discharged to the sea water, industrial waste water or domestic injection region and urban waste water treatment by the secondary purification Cl^- standard emission; some have even the acidic hair brush rotate counterclockwise chlorine slaggingshui Yongye alkali neutralization, after solid-liquid separation, the evaporating of filtrate crystalline sodium chloride in the form of chloride. However, this kind of removing waste water mixes in the process technology feasible, but the lack of economy be difficult to implement. The DuPont Company of the United States the hair brush rotate counterclockwise chlorine slagging , acidic slag flushing water and not to directly perfused 2000m underground and is provided with a closed structure of the rock layer in processing technology, has also been gradually local denied. Titanium chloride-containing waste water by chlorination process so far no economically feasible, cost-effective processing technology.

Content of the invention

The invention aims to solve the technical problem of providing a simple process, low cost, have economic benefits, is friendly to the environment, can be industrial production of titanium dioxide by chlorination process containing chloride waste water for the production of calcium sulfate whisker.

Technical solution of this invention is:

A chlorination process titanium dioxide containing chloride waste water for the production of calcium sulfate whisker, the specific steps are as follows:

(1), the chloride-containing waste water of titanium dioxide Pomolio through the collecting, the thick, purification, after filtering, in the waste water Ca²⁺ content ≥ 50 g/l, Cl^- ≥ 100 g/l the content, the content of  Fe ≤ 20 PPM, Pb²⁺, Bi³⁺, Cd²⁺ ≤ 5 PPM the content, is stored for subsequent use;

(2), will be through the collecting waste water containing sodium sulfate, the thick, purification, after filtering, in the waste water SO₄^2- ≥ 50 g/l the content, the content of  Fe ≤ 20 PPM, Cr⁶⁺ ≤ 5 PPM the content, is stored for subsequent use; or anhydrous sodium sulfate into SO₄^2- concentration is 50 g/l -200 g/l spare solution;

(3), in accordance with the solution obtained in (1) in steps Ca²⁺ the solution obtained in (2) in steps SO₄^2- molar ratio of 1:1-1: 1.5 the step (1) solution (2) and the mixing step of the reaction, stirring, heated to the 60-100 the [...][...] , sulphuric acid to adjust to pH = 2-5; at the same time adding magnesium chloride as a growth promoter, states the magnesium chloride to the adding amount of the product of the weight of the calcium sulfate theory 3%, the reaction time is 20 min -60 min;

(4), in the crystallization tank aging, crystalline 4h-6h, to obtain calcium sulphate crystal;

(5), the calcium sulphate crystal vacuum filtration or centrifugal filtration, calcium sulfate crystal collected in the container and add concentration 1mol/L the H₂ SO₄ control is buffered in the pH 2-5 heating it with water to boil, hot filtering and washing with deionized water at the same time, the amount of deionized water, the weight of the calcium sulfate crystals 1 times -5 times, filtering to obtain the calcium sulfate whisker;

(6), the whisker into the fluidized bed dryer in the 60 the [...] -200 under [...] , drying and dewatering, the packaging is anhydrous calcium sulfate whisker;

(7), (5) are obtained after filtering the step of adding NaOH and acidic mother liquor to pH= 6.5-7, analyzes the medicinal preparation magnesium chloride salt for salting out evaporation crystallization industrial NaCl, the salting-out agent adding amount of magnesium chloride for the quality of the acid stock solution of 20%-40%;

(8), industrial crystallization in step (7) of NaCl neutral of magnesium chloride-containing mother liquor returning to the step (7) continue to conduct salting-out evaporation crystallization industrial NaCl, in neutral the mother liquor SO₄^2- ≥ 50 g/l in time, return to step (3) to replace part of the step (2) solution of sodium sulfate and fuelling medicinal preparation magnesium chloride , circulation preparing calcium sulfate crystal.

The waste water containing the production of sodium sulfate containing vanadium pentoxide Na₂ SO₄ waste water, or used for the production of sodium bichromate spinoffs Glauber's salt, or production haibo containing Na₂ SO₄ alternative processing and purification of the waste liquid.

Steps after filtering (5) the obtained acidic mother liquor returning back to step (3) can also be used for pH value of the solution is adjusted to replace sulfuric acid.

The chloride-containing waste water by chlorination method of the titanium dioxide is titanium dioxide containing calcium chloride by chlorination process the waste water as the main ingredient.

The beneficial effect of the invention:

Process is simple, low cost, containing calcium chloride by chlorination of titanium dioxide with the waste water producing five oxidation b the vanadium contains sodium sulfate waste water, with the economic benefits of the sodium sulfate whisker; the calcium sulfate whisker crystalline acidic stock solution is neutralized with an alkali, salting-out evaporation crystallization industrial NaCl, realize the closed cycle; the industrial production can be realized, so that comprehensive utilization of waste water, resource reclaiming valuable ingredient. Solves the problem that the chlorination process titanium dioxide containing chloride difficult problem of waste water treatment, further improve the chlorination process Titanias clean production level, more friendly to the environment.

Description of drawings

Figure 1 is the process flow diagram of the invention.

Mode of execution

Embodiment 1

(1), the waste water containing calcium chloride titanium dioxide Pomolio (mainly calcium chloride, sodium chloride) through the collecting, the thick, purification, after filtering, in the waste water Ca²⁺ content ≥ 50 g/l, Cl^- ≥ 100 g/l the content, the content of  Fe ≤ 20 PPM, Pb²⁺, Bi³⁺, Cd²⁺ ≤ 5 PPM the content, is stored for subsequent use;

(2), will be produced containing vanadium pentoxide Na₂ SO₄ through the collecting the waste water, the thick, purification, after filtering, in the waste water SO₄^2- ≥ 50 g/l the content, the content of  Fe ≤ 20 PPM, Cr⁶⁺ ≤ 5 PPM the content, is stored for subsequent use;

(3), in accordance with the solution obtained in (1) in steps Ca²⁺ the solution obtained in (2) in steps SO₄^2- molar ratio of 1 : 1.5 and the step (1) solution (2) mixing step of the reaction, stirring, heated to the 80 [...] , by adding sulfuric acid adjusted to pH = 4; at the same time adding magnesium chloride as a growth promoter, states the magnesium chloride to the adding amount of the product of the weight of the calcium sulfate theory 3%, the reaction time is 30 min;

(4), in the crystallization tank aging, crystalline 5h, to obtain calcium sulphate crystal;

(5), the calcium sulphate crystal vacuum filtration or centrifugal filtration, calcium sulfate crystal collected in the container and add concentration 1mol/L the H₂ SO₄ control is buffered in the pH 4 heating it with water to boil, hot filtering and washing with deionized water at the same time, the amount of deionized water, the weight of the calcium sulfate crystals 4 times, filtering to obtain the calcium sulfate whisker;

(6), the whisker into the fluidized bed dryer in the 60 under [...] , drying and dewatering, the packaging is anhydrous calcium sulfate whisker; through detection, to-diameter ratio of anhydrous calcium sulfate whisker   10-200, CaSO₄ content ≥ 98%  , white degrees ≥ 98%  , bulk density is ≤ 0.6g/cm³;

(7), the step (5) in the mother liquor, after filtering and adding NaOH to pH= 6.5, the quality of the adding amount of acid stock solution accounts for 30% of the magnesium chloride salting for salting out evaporation crystallization industrial NaCl;

(8), industrial crystallization in step (7) containing magnesium chloride NaCl neutral mother liquor returning to the step (7) continue to conduct salting-out evaporation crystallization industrial NaCl. When the neutral mother liquor SO₄^2- ≥ 50 g/l in time, return to step (3) to replace part of the solution obtained in step (2) prepare the calcium sulfate crystals and encourage medicinal preparation magnesium chloride.

Embodiment 2

(1), the waste water containing calcium chloride titanium dioxide Pomolio (mainly calcium chloride, sodium chloride) through the collecting, the thick, purification, after filtering, in the waste water Ca²⁺ content ≥ 50 g/l, Cl^- ≥ 100 g/l the content, the content of  Fe ≤ 20 PPM, Pb²⁺, Bi³⁺, Cd²⁺ ≤ 5 PPM the content, is stored for subsequent use;

(2), a by-product of the production of sodium bichromate of mirabilite in waste water dissolved in the vanadium pentoxide, the thick, purifying, Cr⁶⁺ reduction generated after filtering chromium hydroxide, in the waste water SO₄^2- ≥ 100 g/l the content, the content of  Fe ≤ 20 PPM, Cr⁶⁺ ≤ 5 PPM the content, is stored for subsequent use;

(3), in accordance with the solution obtained in (1) in steps Ca²⁺ the solution obtained in (2) in steps SO₄^2- molar ratio of 1 : 1.15 the step (1) solution (2) and the mixing step of the reaction, stirring, heated to the 60 [...] , by adding sulfuric acid adjusted to pH = 2; at the same time adding magnesium chloride as a growth promoter, states the magnesium chloride to the adding amount of the product of the weight of the calcium sulfate theory 3%, the reaction time is 20 min;

(4), in the crystallization tank aging, crystalline 4h, to obtain calcium sulphate crystal;

(5), the calcium sulphate crystal vacuum filtration or centrifugal filtration, calcium sulfate crystal collected in the container and add concentration 1mol/L the H₂ SO₄ the pH buffer control in the 2 heating it with water to boil, hot filtering and washing with deionized water at the same time, the amount of deionized water, the weight of the calcium sulfate crystals 1 times, filtering to obtain the calcium sulfate whisker;

(6), the whisker into the fluidized bed dryer in the 200 [...] , drying and dewatering, the packaging is anhydrous calcium sulfate whisker;

(7), the step (5) in the mother liquor, after filtering and adding NaOH to pH= 7, the quality of the total addition amount of the acidic mother liquor 40% of magnesium chloride salting for salting out evaporation crystallization industrial NaCl; through detection, to-diameter ratio of anhydrous calcium sulfate whisker   10-200, CaSO₄ content ≥ 98%  , white degrees ≥ 98%  , bulk density is ≤ 0.5g/cm³;

(8), industrial crystallization in step (7) containing magnesium chloride NaCl neutral mother liquor returning to the step (7) continue to conduct salting-out evaporation crystallization industrial NaCl, in neutral the mother liquor SO₄^2- ≥ 50 g/l in time, return to step (3) to replace part of the solution (2) containing steps and encourage medicinal preparation magnesium chloride preparing calcium sulfate crystal.

Embodiment 3

(1), the waste water containing calcium chloride titanium dioxide Pomolio (mainly calcium chloride, sodium chloride) through the collecting, the thick, purification, after filtering, in the waste water Ca²⁺ content ≥ 50 g/l, Cl^- ≥ 100 g/l the content, the content of  Fe ≤ 20 PPM, Pb²⁺, Bi³⁺, Cd²⁺ ≤ 5 PPM the content, is stored for subsequent use;

(2), the sedimentation haibo the underflow waste liquid containing main Na₂ SO₄, the remaining Na₂ S₂ O₃, Na₂ SO₃, the S₂ O₃^-2, SO₃^-2 oxidation SO₄^2- the rear, through the collecting, the thick, purification, after filtering, in the waste water SO₄^2- ≥ 200 g/l the content, the content of  Fe ≤ 20 PPM, Cr⁶⁺ ≤ 5 PPM the content, is stored for subsequent use;

(3), in accordance with the solution obtained in (1) in steps Ca²⁺ the solution obtained in (2) in steps SO₄^2- molar ratio of 1 : 1.25 (2) the step (1) and step reaction mixed solution, stirring, heated to the 100 [...] , by adding sulfuric acid adjusted to pH = 5; at the same time adding magnesium chloride as a growth promoter, states the magnesium chloride to the adding amount of the product of the weight of the calcium sulfate theory 3%, the reaction time is 60 min;

(4), in the crystallization tank aging, crystalline 5h, to obtain calcium sulphate crystal;

(5), the calcium sulphate crystal vacuum filtration or centrifugal filtration, calcium sulfate crystal collected in the container and add concentration 1mol/L   the H₂ SO₄ buffer control pH in the 5 heating it with water to boil, hot filtering and washing with deionized water at the same time, the consumption of the deionized water to calcium sulfate crystal weight 3 times, filtering to obtain the calcium sulfate whisker;

(6), the whisker into the fluidized bed dryer in the 200 under [...] , drying and dewatering, the packaging is anhydrous calcium sulfate whisker;

(7), the step (5) in the mother liquor, after filtering and adding NaOH to pH= 7, the quality of the adding amount of acid stock solution accounts for 30% of the magnesium chloride salting for salting out evaporation crystallization industrial NaCl; through detection, to-diameter ratio of anhydrous calcium sulfate whisker   10-200, CaSO₄ content ≥ 98%  , white degrees ≥ 98%, bulk density is ≤ 0.5g/cm³;

(8), step (7) when the industrial crystallization of NaCl neutral of magnesium chloride-containing mother liquor returning to the step (7) continue to conduct salting-out evaporation crystallization industrial NaCl; in neutral mother liquor SO₄^2- ≥ 50 g/l in time, return to step (3) to replace part of the solution (2) containing steps and encourage medicinal preparation magnesium chloride preparing calcium sulfate crystal.

Embodiment 4

(1), the waste water containing calcium chloride titanium dioxide Pomolio (mainly calcium chloride, sodium chloride) through the collecting, the thick, purification, after filtering, in the waste water Ca²⁺ content ≥ 50 g/l, Cl^- ≥ 100 g/l the content, the content of  Fe ≤ 20 PPM, Pb²⁺, Bi³⁺, Cd²⁺ ≤ 5 PPM the content, is stored for subsequent use;

(2), to prepare anhydrous sodium sulfate for SO₄^2- concentration is 200 g/l of sodium sulfate solution;

(3), in accordance with the solution obtained in (1) in steps Ca²⁺ the solution obtained in (2) in steps SO₄^2- molar ratio of 1:1 of the step (1) solution (2) and the mixing step of the reaction, stirring, heated to the 80 [...] , by adding sulfuric acid adjusted to pH = 3; at the same time adding magnesium chloride as a growth promoter, states the magnesium chloride to the adding amount of the product of the weight of the calcium sulfate theory 3%, the reaction time is 40 min;

(4), in the crystallization tank aging, crystalline 5h, to obtain calcium sulphate crystal;

(5), the calcium sulphate crystal vacuum filtration or centrifugal filtration, calcium sulfate crystal collected in the container and add concentration 1mol/L the H₂ SO₄ control is buffered in the pH 3 heating it with water to boil, hot filtering and washing with deionized water at the same time, the amount of deionized water, the weight of the calcium sulfate crystals 2 times, filtering to obtain the calcium sulfate whisker;

(6), the whisker is sent into the fluidized-bed drier 160 the under [...] , drying and dewatering, the packaging is anhydrous calcium sulfate whisker; through detection, to-diameter ratio of anhydrous calcium sulfate whisker   10-200, CaSO₄ content ≥ 98%  , white degrees ≥ 98%, bulk density is ≤ 0.5g/cm³;

(7), the step (5) in the mother liquor, after filtering and adding NaOH to pH= 7, the quality of the total addition amount of the acidic stock solution 20% of magnesium chloride salting for salting out evaporation crystallization industrial NaCl;

(8), industrial crystallization in step (7) containing magnesium chloride NaCl neutral mother liquor returning to the step (7) continue to conduct salting-out evaporation crystallization industrial NaCl, in neutral the mother liquor SO₄^2- ≥ 50 g/l in time, return to step (3) to replace part of the solution (2) containing steps and encourage medicinal preparation magnesium chloride preparing calcium sulfate crystal.

Embodiment 5

Embodiment 1-embodiment 4 containing chloride waste water by chlorination method of the titanium dioxide process for producing calcium sulfate whisker obtained in the step (5) the acid mother liquor after filtration return in the step (3) can also be used for pH value of the solution is adjusted to replace sulfuric acid, other with embodiment 1-embodiment 4.