A method for treating titanium-containing waste liquid

Abstract

The present invention provides a method for treating titanium-containing waste liquid. The treatment method comprises the following steps: S1, pre-treating the titanium-containing waste liquid to obtain a titanium-containing aqueous solution; determining the titanium content in the titanium-containing aqueous solution, where the titanium content is calculated as a percentage by mass of titanium dioxide; S2, neutralizing the mixture to obtain a precipitate; the mixture comprises a titanium-containing aqueous solution, an alkaline substance, and seed crystals; the alkaline substance is used to control the pH value of the solution in the neutralization reaction to be 5-8; the amount of seed crystals added is 0.1%-10%; S3, post-treating the precipitate to obtain a titanium dioxide product. The method can effectively recover titanium from the titanium-containing waste liquid, improve resource utilization, and realize resource utilization of waste; the titanium-containing waste liquid is converted into a titanium dioxide product, the quality of the titanium dioxide product is stable, and the particle size meets the requirements; and the process operation of the method is simple, the equipment requirements are relatively low, and the processing cost is reduced.

Description

Technical Field

[0001] The invention relates to a resource treatment method for titanium-containing waste liquid. Background Art

[0002] In industries such as petrochemicals and catalyst production, such as the production of high-efficiency polypropylene catalysts, large amounts of titanium-containing waste liquids are generated. These waste liquids typically contain titanium compounds such as titanium tetrachloride and titanium (halogenated) alkoxides. Direct discharge of these waste liquids not only causes serious environmental pollution but also wastes titanium resources.

[0003] At present, the main methods for treating titanium-containing waste liquid include harmless treatment methods such as landfill and incineration, but these methods cannot achieve effective recycling of titanium resources; there are also other titanium recovery methods, such as: cold filtration to separate titanium tetrachloride, or vacuum distillation to recover titanium tetrachloride; but these methods have problems such as complex process, high cost, and unstable quality of recovered products.

[0004] Therefore, there is an urgent need to develop a method for recovering waste titanium-containing waste liquid that is efficient, low-cost and capable of producing high-quality titanium dioxide products. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies in titanium-containing waste liquids, such as low resource utilization and complex recovery processes, the present invention provides a method for treating titanium-containing waste liquids. This method effectively recovers titanium from the titanium-containing waste liquid, improving resource utilization and achieving waste resource utilization, with excellent environmental benefits. The titanium-containing waste liquid is converted into a titanium dioxide product with high economic value, stable quality, and meeting required particle size requirements. Furthermore, the method features simple process operations and relatively low equipment requirements, reducing treatment costs.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] The present invention provides a method for treating titanium-containing waste liquid, which comprises the following steps:

[0008] S1. Pretreating the titanium-containing waste liquid to obtain a titanium-containing aqueous solution; determining the titanium content in the titanium-containing aqueous solution, wherein the titanium content is expressed as a percentage by mass of titanium dioxide;

[0009] S2. neutralizing the mixture to obtain a precipitate; the mixture comprises the titanium-containing aqueous solution, an alkaline substance, and seed crystals; the alkaline substance is used to control the pH value of the solution in the neutralization reaction to be 5-8; the amount of the seed crystals added is 0.1%-10%, where % refers to the mass percentage of the seed crystals to the mass content of the titanium;

[0010] The seed crystals include titanium-containing solid powder, aluminum oxide, silicon dioxide or titanium-containing liquid solution;

[0011] S3. Post-processing the precipitate to obtain a titanium dioxide product.

[0012] In step S1 of the present invention, "the titanium content is calculated as the mass of titanium dioxide" can more accurately reflect the titanium content in the titanium-containing waste liquid; based on the titanium content, the amount of seed crystals added in the subsequent process is determined.

[0013] In some embodiments, in step S1, the pretreatment process includes: performing oil-water separation and then solid-liquid separation on the titanium-containing waste liquid.

[0014] In step S1 of the present invention, after the pretreatment, the obtained titanium-containing aqueous solution is a clear solution.

[0015] In some embodiments, in step S1, the titanium-containing waste liquid includes titanium tetrachloride and titanium alkoxide.

[0016] In some embodiments, in step S1, the titanium-containing waste liquid includes waste liquid from producing polypropylene catalyst.

[0017] In some embodiments, in step S1, the titanium content of the titanium-containing waste liquid is 1% to 40%, where % refers to the percentage of the mass of titanium to the total mass of the titanium-containing waste liquid.

[0018] In a specific embodiment, the titanium content of the titanium-containing waste liquid is 5% to 15%, where % refers to the percentage of the mass of titanium to the total mass of the titanium-containing waste liquid.

[0019] In one embodiment, the titanium content of the titanium-containing waste liquid is 5% or 11%, where % refers to the percentage of the mass of titanium to the total mass of the titanium-containing waste liquid.

[0020] In some embodiments, in step S2, the titanium-containing solid powder includes anatase, rutile, or brookite.

[0021] In some embodiments, in step S2, the particle size of the titanium-containing solid powder is 20-50 nm.

[0022] In step S2 of the present invention, the aluminum oxide may be corundum, such as α-Al2O3 and γ-Al2O3.

[0023] In some embodiments, in step S2, the particle size of the aluminum oxide is 20-50 nm.

[0024] In step S2 of the present invention, the silicon dioxide may be quartz.

[0025] In some embodiments, in step S2, the particle size of the silicon dioxide is 20-50 nm.

[0026] In some embodiments, in step S2, the titanium-containing liquid solution comprises: a liquid obtained by direct reaction of the titanium-containing aqueous solution with the alkaline substance in step S1. The term "direct reaction" refers to a neutralization reaction between the titanium-containing aqueous solution and the alkaline substance without adding seed crystals.

[0027] In some embodiments, in step S2, when the seed crystal is a titanium-containing solid powder, aluminum oxide, or silicon dioxide, the amount of the seed crystal added is 0.1%-2%, where % refers to the mass percentage of the seed crystal to the mass percentage of the titanium content.

[0028] In some embodiments, in step S2, when the seed crystals are a liquid solution containing titanium, the amount of the seed crystals added is 1%-10%, where % refers to the mass percentage of the seed crystals to the mass percentage of the titanium content.

[0029] In some embodiments, in step S2, the timing of adding the seed crystals to the titanium-containing aqueous solution includes before the reaction, in the middle of the reaction, and in the late stage of the reaction, which correspond to the following conditions respectively: ① before adding the alkaline substance to the titanium-containing aqueous solution, the seed crystals are added; ② after adding the alkaline substance to the titanium-containing aqueous solution, when the reaction consumption of the alkaline substance reaches 1 / 2 (the solution is green at this time), the seed crystals are added; ③ after adding the alkaline substance to the titanium-containing aqueous solution, when the reaction consumption of the alkaline substance reaches 2 / 3, the seed crystals are added. The timing of adding the above seed crystals will affect the size of the precipitate particles, and thus affect the purity of the subsequent product; adding seed crystals before the neutralization reaction or before the neutralization reaction is complete can make the precipitate generated during the neutralization reaction of the alkaline substance easier to adhere, thereby increasing the precipitate particle size and making it easier to filter during post-processing, which helps to improve the titanium yield and product purity.

[0030] In some embodiments, in step S2, the alkaline substance includes sodium hydroxide or calcium hydroxide.

[0031] In some embodiments, in step S2, the alkaline substance comprises an alkaline solution; the concentration of the alkaline solution is 10%-30%, where % refers to the mass percentage of the solute in the alkaline solution to the mass percentage of the alkaline solution.

[0032] In step S2 of the present invention, the alkaline substance is used to adjust the pH value of the mixture; therefore, those skilled in the art should know that the amount of the alkaline substance added can be determined according to the pH value of the mixture.

[0033] In some embodiments, in step S2, when the alkaline substance is added to the titanium-containing aqueous solution, the temperature of the neutralization reaction is controlled to be 50-80°C.

[0034] In some embodiments, in step S2, when adding the alkaline substance to the titanium-containing aqueous solution, the stirring speed is controlled to be 100-300 r / min.

[0035] In some embodiments, in step S2, water is added to the titanium-containing aqueous solution, and the ratio of the added mass of the water to the mass of the titanium-containing aqueous solution is (2-5):1.

[0036] In a specific embodiment, after the step of adding water to the neutralization reaction solution is completed, the reaction is continued for 30-40 minutes.

[0037] In step S2 of the present invention, when the pH value of the solution of the neutralization reaction is less than 4, the solution is strongly acidic, and the titanium in the titanium-containing aqueous solution is difficult to be completely converted, resulting in a low titanium yield; and when the pH value of the solution of the neutralization reaction is greater than 8, the alkaline substance will excessively react with the titanium-containing aqueous solution to generate impurities, affecting the purity of the product.

[0038] In some embodiments, in step S2, the pH value of the solution in the neutralization reaction is controlled to be 5.5-7.

[0039] In some embodiments, in step S3, the post-processing process includes solid-liquid separation and dry grinding in sequence.

[0040] In a specific embodiment, the solid-liquid separation comprises a step of filtration or centrifugation.

[0041] In some embodiments, the method for treating the titanium-containing waste liquid is carried out in a titanium-containing waste liquid treatment system; the titanium-containing waste liquid treatment system includes a pretreatment device, a neutralization reaction device, and a post-treatment device connected in sequence.

[0042] In a specific embodiment, the pretreatment device includes a filter and a component analyzer.

[0043] In a specific embodiment, the neutralization reaction device includes a reactor with a stirrer and a temperature control device.

[0044] In a specific embodiment, the post-processing device includes a solid-liquid separation unit, a drying unit and a grinding and classification unit; the solid-liquid separation unit includes a filter or a centrifuge, and the grinding and classification unit includes a grinder and a classifier.

[0045] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0046] The reagents and raw materials used in the present invention are commercially available.

[0047] The positive progress effect of the present invention is:

[0048] 1. Resource recycling: The present invention can effectively recycle titanium resources in waste titanium-containing waste liquid and convert it into titanium dioxide products with high economic value, thereby improving resource utilization.

[0049] 2. Simple process: The acid-base neutralization method is adopted, the process operation is simple, the equipment requirements are relatively low, and the processing cost is reduced.

[0050] 3. High product quality: By controlling the reaction conditions, titanium dioxide products with stable quality and particle size that meet the requirements can be produced. The purity of the titanium dioxide product can reach more than 95%.

[0051] 4. Significant environmental benefits: It reduces the pollution of waste titanium-containing waste liquid to the environment, realizes the resource utilization of waste, and has good environmental benefits. DETAILED DESCRIPTION

[0052] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0053] Example 1

[0054] This embodiment discloses a titanium-containing waste liquid treatment system.

[0055] The titanium-containing waste liquid treatment system comprises a pre-treatment device, a neutralization reaction device, and a post-treatment device connected in sequence;

[0056] The pre-treatment device includes a filter and a component analyzer;

[0057] The neutralization reaction device includes a reactor with an agitator and a temperature control device;

[0058] The post-processing device includes a solid-liquid separation unit, a drying unit and a grinding and classification unit; the solid-liquid separation unit includes a filter or a centrifuge, and the grinding and classification unit includes a grinder and a classifier.

[0059] Example 2

[0060] This embodiment discloses a method for treating titanium-containing waste liquid, which adopts the titanium-containing waste liquid treatment system as in Example 1 and includes the following steps:

[0061] Step S1: Preprocessing

[0062] 1000 L of titanium-containing waste liquid generated by a company during the production of polypropylene catalyst was collected. The oil phase was separated by a separator, and the solid impurities were removed by a filter to obtain a clarified titanium-containing aqueous solution. The clarified waste liquid was analyzed for its components using chemical analysis methods. The titanium-containing waste liquid contained titanium tetrachloride and titanium alkoxide, with a measured titanium content of 11% (calculated as a percentage by mass of titanium dioxide). The waste liquid also contained a certain amount of impurities such as chlorine.

[0063] Step S2, acid-base neutralization reaction

[0064] The clarified titanium-containing aqueous solution was transferred to a reactor and diluted with 3 times the amount of water. 0.1% seed crystals (% is the mass percentage of the added amount of seed crystals to the titanium dioxide) were weighed. The seed crystals were anatase solid powder with a particle size of 20-50 nm. The seed crystals were added before the neutralization reaction began.

[0065] Then, slowly add 10% sodium hydroxide solution to neutralize the mixture. Maintain the reaction temperature at 50°C and the stirring speed at 200 rpm. As the sodium hydroxide solution is added, a white precipitate gradually forms. When the pH of the solution reaches 7, stop adding the sodium hydroxide solution and continue stirring for 30 minutes.

[0066] Step S3: Post-processing

[0067] Precipitation and filtration: The mixture after the neutralization reaction is filtered through a filter to separate the solid and liquid to obtain a titanium-containing precipitate;

[0068] Drying and grinding: drying with a muffle furnace or other drying equipment for 2 hours, with the temperature controlled at 80-150°C; grinding the obtained titanium dioxide product with a grinder to obtain a titanium dioxide product.

[0069] After testing, the titanium dioxide content of this product reaches more than 95%, which meets the relevant quality standards.

[0070] Example 3

[0071] This embodiment discloses a method for treating titanium-containing waste liquid, which adopts the titanium-containing waste liquid treatment system as in Example 1 and includes the following steps:

[0072] Step S1: Preprocessing

[0073] 800 L of titanium-containing waste liquid generated by another catalyst manufacturer during the production of polypropylene catalyst was collected. The oil phase was separated through a separator, filtered and analyzed for composition. The titanium-containing waste liquid contained titanium tetrachloride and titanium alkoxide. The titanium content was measured to be 5% (calculated as a percentage by mass of titanium dioxide). The waste liquid also contained a certain amount of impurities such as chlorine.

[0074] Step S2, acid-base neutralization reaction

[0075] To the clarified titanium-containing wastewater, add twice its volume of water and a 15% calcium hydroxide emulsion. When the reaction reaches the intermediate stage and the calcium hydroxide consumption reaches half, the solution turns green. Then, add 2% silicon dioxide seed crystals (% represents the mass percentage of the added seed crystals relative to the titanium dioxide) with a particle size of 20-50nm. Maintain the reaction temperature at 70°C and stir at 250 rpm. Stop adding the calcium hydroxide emulsion when the solution's pH reaches 6, and continue stirring for 40 minutes.

[0076] Step S3: Post-processing

[0077] Precipitation washing: The mixture after the neutralization reaction is filtered to separate the solid and liquid to obtain a titanium-containing precipitate;

[0078] Drying and grinding: drying in a muffle furnace for 2 hours with the temperature controlled at 80-150°C; grinding the obtained titanium dioxide product through a grinder to obtain a titanium dioxide product.

[0079] After testing, the titanium dioxide content of this product reached more than 97%, which meets the relevant quality standards.

Claims

1. A method for treating titanium-containing waste liquid, characterized in that: It includes the following steps: S1. Pretreating the titanium-containing waste liquid to obtain a titanium-containing aqueous solution; determining the titanium content in the titanium-containing aqueous solution, wherein the titanium content is expressed as a percentage by mass of titanium dioxide; the pretreatment process comprising: performing oil-water separation and then solid-liquid separation on the titanium-containing waste liquid; S2. neutralizing the mixture to obtain a precipitate; the mixture comprises the titanium-containing aqueous solution, an alkaline substance, and seed crystals; the alkaline substance is used to control the pH value of the solution of the neutralization reaction to be 5.5-6; the amount of the seed crystals added is 0.1%-10%, where % refers to the mass percentage of the seed crystals to the mass content of the titanium content; The seed crystals include titanium-containing solid powder, aluminum oxide, silicon dioxide or titanium-containing liquid solution; The timing of adding the seed crystals to the titanium-containing aqueous solution satisfies one of the following conditions: ① After adding the alkaline substance to the titanium-containing aqueous solution, adding the seed crystal when the reaction consumption of the alkaline substance reaches 1 / 2; ② After adding the alkaline substance to the titanium-containing aqueous solution, adding the seed crystal when the reaction consumption of the alkaline substance reaches 2 / 3; S3. Post-processing the precipitate to obtain a titanium dioxide product.

2. The method for treating titanium-containing waste liquid according to claim 1, wherein: Step S1 satisfies one or more of the following conditions: ① The titanium-containing waste liquid includes titanium tetrachloride and titanium alkoxide; ② The titanium-containing waste liquid includes waste liquid from the production of polypropylene catalyst; ③ The titanium content of the titanium-containing waste liquid is 1% to 40%, where % refers to the percentage of the mass of titanium to the total mass of the titanium-containing waste liquid.

3. The method for treating titanium-containing waste liquid according to claim 1, wherein: In step S2, the seed crystal satisfies one or more of the following conditions: ① The titanium-containing solid powder includes anatase, rutile or brookite; ② The particle size of the titanium-containing solid powder is 20-50 nm; ③ The particle size of the aluminum oxide is 20-50 nm; ④ The particle size of the silicon dioxide is 20-50 nm; ⑤ The titanium-containing liquid solution includes: a liquid obtained by directly reacting the titanium-containing aqueous solution and the alkaline substance in step S1; ⑥ When the seed crystal is a titanium-containing solid powder, aluminum oxide or silicon dioxide, the amount of the seed crystal added is 0.1%-2%, where % refers to the mass percentage of the seed crystal to the mass percentage of the titanium content; ⑦ When the seed crystal is a liquid solution containing titanium, the amount of the seed crystal added is 1%-10%, and % refers to the mass percentage of the seed crystal to the mass percentage of the titanium content.

4. The method for treating titanium-containing waste liquid according to claim 1, wherein: In step S2, the alkaline substance satisfies one or both of the following conditions: ① The alkaline substance includes sodium hydroxide or calcium hydroxide; ② The alkaline substance includes an alkaline solution; the concentration of the alkaline solution is 10%-30%, and % refers to the mass percentage of the solute in the alkaline solution.

5. The method for treating titanium-containing waste liquid according to claim 1, wherein: Step S2 satisfies one or more of the following conditions: ① When adding alkaline substance to the titanium-containing aqueous solution, the temperature of the neutralization reaction is controlled to be 50-80° C.; ② When adding the alkaline substance to the titanium-containing aqueous solution, the stirring speed is controlled to be 100-300 r / min; ③ Add water to the titanium-containing aqueous solution, with the ratio of the added mass of the water to the mass of the titanium-containing aqueous solution being (2-5):

1.

6. The method for treating titanium-containing waste liquid according to claim 5, wherein: After the step of adding water to the neutralization reaction solution is completed, the reaction is continued for 30-40 minutes.

7. The method for treating titanium-containing waste liquid according to claim 1, wherein: In step S3, the post-processing process includes solid-liquid separation and dry grinding in sequence.

8. The method for treating titanium-containing waste liquid according to any one of claims 1 to 7, characterized in that: The method for treating the titanium-containing waste liquid is carried out in a titanium-containing waste liquid treatment system; The titanium-containing waste liquid treatment system comprises a pretreatment device, a neutralization reaction device, and a post-treatment device which are connected in sequence.

9. The method for treating titanium-containing waste liquid according to claim 8, wherein: The titanium-containing waste liquid treatment system meets one or more of the following conditions: ① The pretreatment device includes a filter and a component analyzer; ② The neutralization reaction device includes a reactor with an agitator and a temperature control device; ③ The post-processing device includes a solid-liquid separation unit, a drying unit and a grinding and classification unit; the solid-liquid separation unit includes a filter or a centrifuge, and the grinding and classification unit includes a grinder and a classifier.