阅读说明：本技术 一种制备高消色力金红石钛白粉的方法 (Method for preparing high-achromatism rutile titanium dioxide ) 是由 覃愿 许定文 李广欣 邓志军 梁燕华 郭小凤 杨曙光 覃进文 于 2020-03-31 设计创作，主要内容包括：本发明公开了一种制备高消色力金红石钛白粉的方法,包括如下步骤：在钛精矿中加入硫酸进行酸解,得钛悬浮液,在钛悬浮液加入马来酸酐—苯乙烯磺酸共聚物、木质素磺酸钠和聚合氯化铝组成的絮凝剂进行除杂处理,得精制钛液；在精制钛液加入金红石晶种和分散剂水解,得水解产物；将水解产物经水洗,再加入硫酸漂白,二次水洗,得浆液；在浆液中加入由磷酸盐溶液、乙酸锌溶液和硝酸钇溶液组成的盐溶液处理剂；再将浆液经压滤机压滤,然后将滤饼转窑煅烧,冷却,粉碎,得金红石钛白粉。本发明方法制得的钛白粉金红石含量达到98.5%以上,白度达到98%以上,Tcs值达到2034以上,Scx值达到4.21以上,且产品粒度分布均匀,分散性好,是优异的白色颜料。(The invention discloses a method for preparing high-achromatism rutile titanium dioxide, which comprises the following steps: adding sulfuric acid into the titanium concentrate for acidolysis to obtain a titanium suspension, and adding a flocculating agent consisting of maleic anhydride-styrene sulfonic acid copolymer, sodium lignosulfonate and polyaluminium chloride into the titanium suspension for impurity removal to obtain refined titanium liquid; adding rutile seed crystal and dispersant into the refined titanium liquid for hydrolysis to obtain hydrolysate; washing the hydrolysate with water, adding sulfuric acid for bleaching, and washing with water for the second time to obtain slurry; adding a salt solution treating agent consisting of a phosphate solution, a zinc acetate solution and a yttrium nitrate solution into the slurry; and carrying out filter pressing on the slurry by a filter press, then calcining a filter cake in a rotary kiln, cooling and crushing to obtain the rutile titanium dioxide. The rutile content of the titanium dioxide prepared by the method reaches more than 98.5 percent, the whiteness reaches more than 98 percent, the Tcs value reaches more than 2034, the Scx value reaches more than 4.21, and the product has uniform particle size distribution and good dispersibility and is an excellent white pigment.)

1. A method for preparing high-achromatism rutile titanium dioxide is characterized in that: the method comprises the following steps:

(1) adding sulfuric acid into the titanium concentrate for acidolysis to obtain a titanium suspension, adding a flocculating agent consisting of maleic anhydride-styrene sulfonic acid copolymer, sodium lignosulfonate and polyaluminium chloride into the titanium suspension for impurity removal, standing, pumping out the upper half part of a clear liquid, conveying the upper half part into a primary pressure filter, adding an adsorbent, performing pressure filtration, performing solid-liquid separation, allowing the liquid after pressure filtration to enter a vacuum crystallization system, removing ferrous sulfate heptahydrate through a disc separator, and adding the adsorbent for secondary pressure filtration to obtain a refined titanium liquid;

(2) adding water into the refined titanium liquid to adjust the refined titanium liquid to 200-400 g/L, heating to 94-98 ℃, stirring, adding rutile seed crystals and a dispersing agent, wherein the addition amount of the rutile seed crystals is 3-5% of the dry mass of titanium dioxide in the refined titanium liquid, heating to boiling, stopping heating for 30-60min, heating again to boiling, and finally preserving heat and micro pressure for 4-5h to obtain a hydrolysate;

(3) washing the hydrolysate with water until the content of iron ions is below 150ppm, adding sulfuric acid for bleaching, washing with water for the second time until the content of iron ions is below 50ppm to obtain slurry;

(4) adding a salt solution treatment agent into the slurry, wherein the salt solution treatment agent consists of a phosphate solution, a zinc acetate solution and a yttrium nitrate solution; stirring uniformly, then carrying out filter pressing on the slurry by a filter press, then calcining a filter cake in a rotary kiln, cooling and crushing to obtain the rutile titanium dioxide.

2. The method for preparing high-achromatism rutile titanium dioxide as claimed in claim 1, wherein: the mass ratio of the maleic anhydride-styrene sulfonic acid copolymer, the sodium lignosulfonate and the polyaluminium chloride in the flocculant is 3-5:1-3:1, and the adding amount of the maleic anhydride-styrene sulfonic acid copolymer, the sodium lignosulfonate and the polyaluminium chloride is 1-2% of the mass of the titanium concentrate.

3. The method for preparing high-achromatism rutile titanium dioxide as claimed in claim 1, wherein: the adsorbent consists of diatomite and a zeolite molecular sieve in a mass ratio of 1: 1-3; the adding amount of the adsorbent is 0.8-1.5% of the mass of the titanium concentrate.

4. The method for preparing high-achromatism rutile titanium dioxide as claimed in claim 1, wherein: the dispersant consists of an aluminum methacrylate-zirconium coupling agent, polyoxyethylene fatty amide and polyoxyethylene stearate.

5. The method for preparing high-achromatism rutile titanium dioxide as claimed in claim 5, wherein: the addition amount of the dispersant is 0.5 to 1.5 percent of the mass of the titanium dioxide in the slurry; the mass ratio of the aluminum methacrylate-zirconium coupling agent, the polyoxyethylene fatty amide and the polyoxyethylene stearate in the dispersing agent is 3-6:1-3: 3-6.

6. The method for preparing high-achromatism rutile titanium dioxide as claimed in claim 1, wherein: the addition amount of the phosphate solution in the salt solution treatment agent is 0.1-0.3% of the titanium dioxide in the slurry by the weight of phosphorus pentoxide, the addition amount of the zinc acetate solution is 0.3-0.5% of the titanium dioxide in the slurry by the weight of zinc oxide, and the addition amount of the yttrium nitrate solution is 0.01-0.1% of the titanium dioxide in the slurry by the weight of yttrium oxide.

7. The method for preparing high-achromatism rutile titanium dioxide as recited in claim 6, wherein: the phosphate is one or more of sodium hydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate and sodium hexametaphosphate.

8. The method for preparing high-achromatism rutile titanium dioxide as claimed in claim 1, wherein: and (4) the filter pressing is to press the slurry until the solid content is 50-60%.

9. The method for preparing high-achromatism rutile titanium dioxide as claimed in claim 1, wherein: the water pressure of the water washing is controlled to be 0.4-0.5MPa, and the flow rate is controlled to be 20-25 square/min.

10. The method for preparing high-achromatism rutile titanium dioxide as claimed in claim 1, wherein: the calcination is carried out by heating to 300-350 ℃, keeping the temperature for 0.5-1.0h, heating to 450-500 ℃, keeping the temperature for 1.0-1.5h, and then heating to 650-700 ℃ and keeping the temperature for 2-2.5 h.

Technical Field

The invention belongs to the technical field of titanium dioxide production, and particularly relates to a method for preparing high-achromatism rutile titanium dioxide.

Background

Titanium dioxide, i.e. titanium dioxide, is an important inorganic chemical raw material. Because of its non-toxicity, stable physical and chemical properties, it has excellent optical and electrical properties and excellent pigment performance, and can be extensively used in the fields of coating, printing ink, plastics, rubber, paper-making, chemical fibre, art pigment, daily cosmetics, enamel, ceramics and electronics, etc. The rutile type titanium dioxide is produced by a sulfuric acid method, wherein titanium iron powder and concentrated sulfuric acid are subjected to acidolysis reaction to generate an intermediate titanyl sulfate, the titanyl sulfate needs to be hydrolyzed into metatitanic acid and sulfuric acid, and the metatitanic acid is subjected to washing, calcining, crushing and other processes to obtain a titanium dioxide product with a rutile crystal structure. Rutile titanium dioxide is a white pigment with excellent stability, and is widely applied to internal and external wall latex paints, industrial coatings, composite inks, flexographic inks, laminated paper, plastic color master batches, powder coatings and the like.

In order to improve the performance of rutile titanium dioxide, the bleached metatitanic acid needs to be subjected to salt treatment, and then the rutile titanium dioxide is prepared by calcining. The traditional rutile salt treating agent is phosphoric acid and potassium carbonate, and the whiteness of the titanium dioxide can be improved by adding the phosphoric acid, so that the weather resistance of the titanium dioxide is improved, and the calcined titanium dioxide is soft and fragile; the whiteness of the titanium dioxide can be improved by adding the potassium carbonate, the agglomeration of small particles can be prevented, and the sintering of the fine particles in the calcining process is avoided. But the salt accelerator has poor improving effect on the color reducing power and the dispersibility of the titanium dioxide. In recent years, the global demand for rutile type titanium dioxide is continuously increased at a high speed, and with the continuous subdivision of the global titanium dioxide market, the demand is increased greatly due to the appearance of a large number of new products. Therefore, research on rutile titanium dioxide with high decolorization, high dispersibility and strong weather resistance is a demand of the current market.

Disclosure of Invention

The invention provides a method for preparing high-achromatism rutile titanium dioxide, aiming at solving the problems of poor achromatism, easy agglomeration and the like of the titanium dioxide. The rutile titanium dioxide prepared by the method has the advantages of high decolorization, good luster, good dispersibility, good stability and the like, and is wide in application range.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

a method for preparing high-achromatism rutile titanium dioxide comprises the following steps:

(1) adding sulfuric acid into the titanium concentrate for acidolysis to obtain a titanium suspension, adding a flocculating agent consisting of maleic anhydride-styrene sulfonic acid copolymer, sodium lignosulfonate and polyaluminium chloride into the titanium suspension for impurity removal, standing, pumping out the upper half part of a clear liquid, conveying the upper half part into a primary pressure filter, adding an adsorbent, performing pressure filtration, performing solid-liquid separation, allowing the liquid after pressure filtration to enter a vacuum crystallization system, removing ferrous sulfate heptahydrate through a disc separator, and adding the adsorbent for secondary pressure filtration to obtain a refined titanium liquid;

(2) adding water into the refined titanium liquid to adjust the refined titanium liquid to 200-400 g/L, heating to 94-98 ℃, stirring, adding rutile seed crystals and a dispersing agent, wherein the addition amount of the rutile seed crystals is 3-5% of the dry mass of titanium dioxide in the refined titanium liquid, heating to boiling, stopping heating for 30-60min, heating again to boiling, and finally preserving heat and micro pressure for 4-5h to obtain a hydrolysate;

(3) washing the hydrolysate with water until the content of iron ions is below 150ppm, adding sulfuric acid for bleaching, washing with water for the second time until the content of iron ions is below 50ppm to obtain slurry;

(4) adding a salt solution treatment agent into the slurry, wherein the salt solution treatment agent consists of a phosphate solution, a zinc acetate solution and a yttrium nitrate solution; stirring uniformly, then carrying out filter pressing on the slurry by a filter press, then calcining a filter cake in a rotary kiln, cooling and crushing to obtain the rutile titanium dioxide.

Furthermore, the mass ratio of the maleic anhydride-styrene sulfonic acid copolymer, the sodium lignosulfonate and the polyaluminium chloride in the flocculant is 3-5:1-3:1, and the adding amount of the flocculant is 1-2% of the mass of the titanium concentrate.

Further, the adsorbent consists of diatomite and a zeolite molecular sieve in a mass ratio of 1: 1-3; the adding amount of the adsorbent is 0.8-1.5% of the mass of the titanium concentrate.

Further, the dispersant consists of an aluminum methacrylate-zirconium coupling agent, a polyoxyethylene fatty amide, and a polyoxyethylene stearate.

Further, the addition amount of the dispersing agent is 0.5-1.5% of the mass of the titanium dioxide in the slurry; the mass ratio of the aluminum methacrylate-zirconium coupling agent, the polyoxyethylene fatty amide and the polyoxyethylene stearate in the dispersing agent is 3-6:1-3: 3-6.

Furthermore, the addition amount of the phosphate solution in the salt solution treatment agent is 0.1-0.3% of the titanium dioxide in the slurry by the weight of phosphorus pentoxide, the addition amount of the zinc acetate solution is 0.3-0.5% of the titanium dioxide in the slurry by the weight of zinc oxide, and the addition amount of the yttrium nitrate solution is 0.01-0.1% of the titanium dioxide in the slurry by the weight of yttrium oxide.

Further, the phosphate is one or more of sodium hydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate and sodium hexametaphosphate.

Further, in the step (4), the filter pressing is to press the filtrate to a solid content of 50-60%.

Furthermore, the water pressure of the water washing is controlled to be 0.4-0.5MPa, and the flow rate is controlled to be 20-25 square/min.

Further, the calcination is carried out by heating to 350 ℃ for 0.5-1.0h, heating to 500 ℃ for 1.0-1.5h, and heating to 700 ℃ for 2-2.5 h.

Compared with the prior art, the invention has the advantages and beneficial effects that:

1. the rutile content of the titanium dioxide prepared by the method reaches more than 98 percent, the whiteness reaches more than 98 percent, the Tcs value reaches more than 2034, the Scx value reaches more than 4.21, and the product has uniform particle size distribution and good dispersibility and is an excellent white pigment.

2. According to the method, a flocculating agent consisting of maleic anhydride-styrene sulfonic acid copolymer, sodium lignosulfonate and polyaluminium chloride is used for removing impurities in the acidolysis process, and a method combining cationic and anionic flocculating agents is adopted, so that positively charged cationic metal impurities and negatively charged impurities can be effectively and stably removed, the impurity removing effect is remarkable, and the luster and whiteness of titanium white can be improved.

3. The method comprises the steps of washing the metatitanic acid particles by two times, washing iron by the first time to be less than 150ppm, bleaching and dissolving ferric ions in the metatitanic acid particles by adding sulfuric acid, reducing the ferric ions in the metatitanic acid particles by using the ferric titanium to become ferrous ions, and finally washing the metatitanic acid particles by two times to further clean the ferric ions. And by well controlling the pressure and flow of the washing water, on one hand, the washing efficiency is improved, on the other hand, the scouring force of water on metal ions is improved, the neutralization impurities of the metatitanic acid are reduced, and the iron content is controlled to be below 50 ppm.

4. The method takes the adsorbent consisting of the diatomite and the zeolite molecular sieve as the filter aid, improves the adsorption capacity to impurities, and improves the purity and the whiteness of the prepared titanium dioxide.

5. In the invention, a dispersant consisting of aluminum methacrylate-zirconium coupling agent, polyoxyethylene fatty amide and polyoxyethylene stearate is added in the hydrolysis process, so that the dispersibility of the titanium dioxide can be improved, and the problem of easy agglomeration of the existing titanium dioxide is solved.

6. The method uses phosphate solution, zinc acetate solution and yttrium nitrate solution to form salt treatment agent, which can control rutile content and improve the decolorization of titanium dioxide.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments. It should be emphasized that the following description is merely exemplary in nature and is not intended to limit the scope of the invention or its application.