Treatment method of sulfuric acid process titanium dioxide acid waste

Abstract

The invention provides a treatment method of sulfuric acid process titanium dioxide acidic waste, the sulfuric acid process titanium dioxide acidic waste comprises acidic wastewater and titanium concentrate acidolysis slurry, and the method comprises the step of separately treating the acidic wastewater and the titanium concentrate acidolysis slurry. According to the method, the acid wastewater and the titanium concentrate acidolysis slurry are subjected to neutralization, sedimentation and squeezing treatment separately, so that the neutralization rate, the sedimentation rate and the sedimentation effect are improved, the consumption of a neutralizer is reduced, meanwhile, the product quality of titanium gypsum neutralized by the acid wastewater is improved (the content of sulfur trioxide is greater than or equal to 30%), and in addition, the yield of titanium is also increased.

Description

Technical Field

[0001] The invention belongs to the field of chemical process intensification and environmental protection, and specifically relates to a method for treating sulfuric acid process titanium dioxide acid waste. Background Art

[0002] China is the world's largest producer of titanium dioxide, accounting for more than 85% of the production capacity. Titanium dioxide production processes are mainly divided into sulfuric acid process and chlorination process, of which sulfuric acid process accounts for more than 50% of the production capacity, reaching 57.3%. As national environmental protection requirements become increasingly stringent, the key factor restricting the survival and development of sulfuric acid process titanium dioxide is how to deal with acidic waste.

[0003] The acidic wastes of titanium dioxide produced by the sulfuric acid process mainly include conventional acidic wastewater and acid hydrolysis sludge of titanium concentrate. Conventional acidic wastewater mainly comes from the acidic wastewater used for washing with metatitanic acid, and the acidic wastewater from washing equipment and sites. The acid hydrolysis sludge of titanium concentrate comes from the unreacted ore powder produced after the acid hydrolysis and sedimentation of titanium concentrate, and the reaction products of silicate and calcium sulfate solid substances. Conventional acidic wastewater usually contains 2% to 5% sulfuric acid (with a high acidity and a pH value less than 1), 0.5% to 1.2% Fe 2+ 、SO4 2− 、TiO 2+ 、Al 3+ Mg 2+ 、Ni 2 + , Mn 2+ There are many soluble impurities, as well as a small amount of insoluble impurities (≤0.3g / L). If the titanium dioxide acid waste with rich impurities and high sulfide and iron impurity content is not effectively treated or directly discharged, it will cause serious land pollution, pollute domestic water, groundwater and other water resources, and destroy the ecological balance.

[0004] In the existing technology, the treatment methods of sulfuric acid process titanium dioxide acid waste mainly include neutralization method, membrane treatment method, ASBR sulfate reducing bacteria (SRB) method, extraction method, etc. Due to the low technical maturity, high cost and complex operation of membrane treatment method, ASBR sulfate reducing bacteria (SRB) method and extraction method, they are rarely used.

[0005] Existing sulfuric acid titanium dioxide production enterprises generally use the neutralization method to treat acidic waste. Specifically, limestone or quicklime is used as a neutralizer, and for the convenience of operation, the titanium dioxide acid wastewater is mixed with the titanium concentrate acid hydrolysis sludge to neutralize to a pH value of 7-7.5, and the SO4 in the solution is 2− and Fe 2+It is converted into solid calcium sulfate and ferrous hydroxide, and after sedimentation and filtration, the wastewater is discharged in compliance with the standards. The solid residue after filtration is called titanium gypsum, in which the content of calcium sulfate dihydrate is about 70wt% to 75wt%, and the content of iron is about 7wt% to 10wt%. However, this method of mixing acidic wastewater and titanium concentrate acid hydrolysis sludge for treatment has the following disadvantages.

[0006] The vast majority of the titanium concentrate acid hydrolysis slurry is unreacted mineral powder and colloidal reaction products such as silicate and calcium sulfate. Colloidal silicate and calcium sulfate easily absorb fine impurity particles, which are difficult to settle and take a long time to settle. In addition, the turbidity of the filtrate obtained by squeezing is poor. The most critical thing is that the acid wastewater is mixed with the titanium concentrate acid hydrolysis slurry for neutralization, sedimentation and filtration, which will lead to a low sulfur trioxide content in titanium gypsum (<30%), which cannot meet the sulfur trioxide content requirements of cement manufacturers as a retarder.

[0007] In addition, during the neutralization process of acidic wastewater and titanium concentrate acid hydrolysis sludge, sulfuric acid method titanium dioxide production enterprises use stirring tanks for stirring neutralization. The neutralization process often requires a faster neutralization rate. In order to achieve this goal, the neutralizing agents limestone and quicklime have finer and smaller particle sizes. Due to the large amount of acidic waste treated and the fast reaction rate of limestone and quicklime with acidic waste, the neutralization product colloidal calcium sulfate easily wraps up the unreacted neutralizer, resulting in incomplete reaction of limestone and quicklime, increasing the consumption of neutralizing agents limestone and quicklime, and low sulfur trioxide content in titanium gypsum.

[0008] In short, the method of mixing acidic wastewater and titanium concentrate acid hydrolysis sludge for neutralization, sedimentation, and squeezing and filtering not only consumes a large amount of neutralizer and has a slow sedimentation rate of the neutralization product, but also obtains titanium gypsum of poor quality: titanium gypsum has a high water content, low sulfur trioxide content, low mechanical strength, and low purity, which results in a narrow range of titanium gypsum availability and is subject to many restrictive factors.

[0009] Therefore, the existing technology still has much room for improvement in terms of increasing the sulfur trioxide content in titanium gypsum (≥30%) and reducing the consumption of neutralizing agents limestone and quicklime. Summary of the invention

[0010] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for treating acidic wastes of titanium dioxide produced by the sulfuric acid process.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for treating acidic wastes of titanium dioxide produced by a sulfuric acid process. The acidic wastes of titanium dioxide produced by a sulfuric acid process include acidic wastewater and acid hydrolysis slurry of titanium concentrate. The method comprises separately treating the acidic wastewater and the acid hydrolysis slurry of titanium concentrate, wherein: Treatment of acidic wastewater involves the following steps: S10, performing primary neutralization treatment on the acidic wastewater to obtain primary neutralization material for wastewater; S20, performing secondary neutralization treatment on the primary neutralization material of the wastewater to obtain secondary neutralization material of the wastewater; S30, sequentially performing sedimentation and pressing treatments on the secondary neutralization materials of the wastewater to obtain acidic wastewater neutralizing titanium gypsum; Treatment of titanium concentrate acid slurry includes the following steps: S10′, performing a first treatment to remove soluble components from the titanium concentrate acid hydrolysis slurry to obtain the titanium concentrate acid hydrolysis slurry after the first treatment; S20′, performing a second treatment to remove soluble components from the titanium concentrate acid hydrolysis slurry after the first treatment to obtain the titanium concentrate acid hydrolysis slurry after the second treatment; S30′, performing mud neutralization treatment on the acid hydrolysis mud of the titanium concentrate after the second treatment to obtain a mud neutralized material; S40′, sequentially subjecting the slurry-neutralized material to sedimentation and pressing treatment to obtain titanium concentrate acid hydrolysis slurry-neutralized titanium gypsum.

[0012] In one embodiment, in step S10, the following steps are also included: S11, performing a wastewater primary wet ball milling neutralization treatment on the acidic wastewater to obtain a wastewater primary wet ball milling neutralization material; S12, performing a first-level stirring and neutralization treatment on the first-level wet ball milling neutralized material of the wastewater to obtain a first-level stirring and neutralized material of the wastewater; In step S20, the following steps are also included: S21, performing wastewater secondary wet ball milling neutralization treatment on the wastewater primary stirring neutralization material to obtain wastewater secondary wet ball milling neutralization material; S22, performing wastewater secondary stirring neutralization treatment on the wastewater secondary wet ball milling neutralization material to obtain wastewater secondary stirring neutralization material; In step S30, the following steps are also included: S31, sequentially performing sedimentation and pressing treatment on the secondary stirring and neutralization materials of the wastewater to obtain acidic wastewater neutralizing titanium gypsum; In step S10′, the following steps are also included: S11′, performing a primary pulping treatment on the acid hydrolysis slurry of the titanium concentrate to obtain a primary pulping material; S12′, performing a pressing process on the first pulping material to obtain a first pressing material and a first pressing filtrate; In step S20′, the following steps are also included: S21′, performing secondary pulping treatment on the primary pressed material to obtain secondary pulped material; S22′, performing secondary pressing on the secondary pulping material to obtain secondary pressing material and secondary pressing filtrate; In step 30', the following steps are also included: S31′, performing a three-time beating treatment on the secondary pressed material to obtain a three-time beating material; S32′, performing a mud wet ball milling neutralization treatment on the three-beating materials to obtain a mud wet ball milling neutralized material; S33′, performing a mud stirring and neutralization treatment on the mud wet ball mill neutralized material to obtain a mud stirring and neutralized material; S34′, sequentially subjecting the slurry agitation and neutralization materials to sedimentation and pressing treatments to obtain titanium concentrate acid hydrolysis slurry and titanium gypsum.

[0013] In one embodiment, in step S10, the neutralization time of the primary neutralization treatment of the wastewater is 0.5h to 1h, and the neutralization temperature is 50°C to 80°C; In step S20, the neutralization time of the secondary neutralization treatment of the wastewater is 2h to 4h, and the neutralization temperature is 50°C to 80°C; In step S30', the neutralization time of the mud neutralization treatment is 2 hours to 4 hours, and the neutralization temperature is 50°C to 80°C.

[0014] In one embodiment, in step S11 and step S12, the pH of the wastewater primary wet ball milling neutralization material and the wastewater primary stirring neutralization material are controlled to be 3.5-4.0 respectively; In step S21 and step S22, the pH of the wastewater secondary wet ball milling neutralization material and the wastewater secondary stirring neutralization material are controlled to be 7.0-7.5 respectively; In step S32' and step S33', the pH of the material neutralized by slurry wet ball milling and the material neutralized by slurry stirring are controlled to be 7.0-7.5 respectively.

[0015] In one embodiment, the neutralizer used in the primary neutralization treatment of wastewater in step S10 is limestone milk, and the neutralizer used in the secondary neutralization treatment of wastewater in step S20 and the sludge neutralization treatment in step S30' are both quicklime milk.

[0016] In one embodiment, the limestone milk is prepared by mixing limestone with existing titanium gypsum squeezing water, and the CaO content in the limestone is ≥50.4 wt %; The quicklime milk is prepared by quicklime and existing titanium gypsum squeezed water, and the CaO content in the quicklime is ≥85.0 wt %; wherein, The existing titanium gypsum has CaSO4•2H2O≥85.00% on a dry basis and a moisture content≤20%.

[0017] In one embodiment, the primary stirring and neutralization treatment of wastewater in step S12, the secondary stirring and neutralization treatment of wastewater in step S22, and the slurry stirring and neutralization treatment in step S33' are all carried out in a stirring tank and are treated by frame stirring, and the neutralization stirring speed is 250r / min to 500r / min.

[0018] In one embodiment, in step S31, the sedimentation time is 12h to 24h, and in step S34', the sedimentation time is 24h to 48h; the sedimentation temperature is 25°C to 40°C, and the sedimentation stirring speed is 1r / min to 2r / min; In step S10′, step S20′ and step 30′, the beating time is 1 h to 2 h, and the beating stirring speed is 500 r / min to 1000 r / min; In step S31, step S10', step S20', step 30' and step 40', the pressed solid content is ≥ 80%.

[0019] In one embodiment, the primary pressing filtrate in step S12' and the secondary pressing filtrate in step S22' are both used as low-density titanium-containing water for leaching of solid phase matter from acid hydrolysis of titanium concentrate.

[0020] In one embodiment, the insoluble solid content in the acidic wastewater is ≤0.3g / L, the sulfuric acid concentration is 2wt%~5wt%, the sulfur trioxide content in the neutralized titanium gypsum in the acidic wastewater is ≥30%, and the neutralized titanium gypsum in the acidic wastewater is used as a raw material for cement retarder, and the neutralized titanium gypsum in the titanium concentrate acid hydrolysis slurry is used as a raw material for titanium concentrate acid hydrolysis.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are: The method for treating acidic waste of titanium dioxide produced by sulfuric acid process of the present invention separately neutralizes, settles and presses the acidic wastewater and the acidolysis sludge of titanium concentrate, thereby improving the neutralization rate, sedimentation rate and sedimentation effect. The two-stage neutralization process of "wet ball milling neutralization + stirring neutralization" is used to treat the acidic wastewater, which avoids the technical problem of insufficient reaction of the neutralizer due to being wrapped by calcium sulfate, thereby avoiding the additional increase in the amount of neutralizer, reducing the consumption of the neutralizer, and improving the product quality of the neutralized titanium gypsum in the acidic wastewater (sulfur trioxide content ≥ 30%). The acidolysis sludge of titanium concentrate is treated by two beatings and two presses, which not only reduces the consumption of the neutralizer, but also increases the yield of titanium. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 The schematic flow chart of the method for treating sulfuric acid titanium dioxide acid waste of the present invention; Figure 2 is a schematic flow chart of the treatment of acidic wastewater according to the present invention; Figure 3 The present invention is a schematic flow chart of treating the acid hydrolysis sludge of titanium concentrate. DETAILED DESCRIPTION

[0024] The following is a further detailed description of the embodiments of the present disclosure in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

[0025] The present disclosure provides these embodiments to make the present disclosure thorough and complete, and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0026] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0027] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present disclosure or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically limited.

[0028] like Figure 1 As shown, the present invention provides a method for treating acidic waste of titanium dioxide produced by a sulfuric acid process. The acidic waste of titanium dioxide produced by a sulfuric acid process includes acidic wastewater and acid hydrolysis sludge of titanium concentrate. The method includes separately treating the acidic wastewater and the acid hydrolysis sludge of titanium concentrate.

[0029] In one embodiment, treating acidic wastewater comprises the following steps: S10, performing primary neutralization treatment on the acidic wastewater to obtain primary neutralization material for wastewater, wherein the neutralizing agent used in the primary neutralization treatment for wastewater is limestone milk.

[0030] S20, performing secondary neutralization treatment on the primary neutralization material of the wastewater to obtain secondary neutralization material of the wastewater, wherein the neutralizing agent used in the secondary neutralization treatment of the wastewater is quicklime milk.

[0031] S30, sequentially sedimenting and pressing the wastewater secondary neutralization material to obtain acidic wastewater neutralizing titanium gypsum.

[0032] like Figure 2 As shown, in one embodiment, in step S10, the following steps are also included: S11, performing a wastewater primary wet ball milling neutralization treatment on the acidic wastewater to obtain a wastewater primary wet ball milling neutralization material.

[0033] S12, performing a first-level stirring neutralization treatment on the first-level wet ball milling neutralized material of the wastewater to obtain the first-level stirring neutralized material of the wastewater.

[0034] In one embodiment, in step S20, the following steps are also included: S21, subjecting the wastewater primary stirring neutralization material to wastewater secondary wet ball milling neutralization treatment to obtain wastewater secondary wet ball milling neutralization material.

[0035] S22, performing wastewater secondary stirring neutralization treatment on the wastewater secondary wet ball milling neutralization material to obtain wastewater secondary stirring neutralization material.

[0036] In one embodiment, in step S30, the following steps are also included: S31, the secondary stirring and neutralizing materials of the wastewater are sequentially subjected to sedimentation and pressing treatment to obtain acidic wastewater neutralizing titanium gypsum.

[0037] The acidic wastewater of the present invention mainly comprises water, free acid and soluble sulfate (such as ferrous sulfate, ferric sulfate, etc.), the insoluble solid content of the acidic wastewater of the present invention is ≤0.3g / L, and the sulfuric acid concentration is 2wt% to 5wt%. When treating the acidic wastewater, the present invention adopts a two-stage neutralization process of "primary wet ball milling neutralization + primary stirring neutralization + secondary wet ball milling neutralization + secondary stirring neutralization" and "wet ball milling neutralization + stirring neutralization", and neutralization is performed by neutralizing and grinding at the same time in the wet ball milling neutralization stage. The two-stage neutralization process can fully disperse the neutralizer wrapped by calcium sulfate, avoiding the agglomeration of the neutralizer limestone or quicklime during the neutralization process, so that the neutralizer can be fully reacted, reducing the additional consumption of the neutralizer limestone or quicklime due to insufficient utilization. The neutralization efficiency is high and the obtained acidic wastewater neutralized titanium gypsum is of high quality, which can meet the cement industry's requirements for the sulfur trioxide content of the raw material titanium gypsum as a cement retarder (sulfur trioxide content ≥30%).

[0038] The wet ball mill of the present invention adopts an acid-resistant and alkali-resistant polyurethane inner village structure, the grinding medium adopts acid-resistant and alkali-resistant zirconium oxide zirconium beads, the diameter of the zirconium beads is 0.6 cm to 0.8 cm, and the stirring tank adopts carbon steel lining anti-corrosion bricks.

[0039] In one embodiment, if Figure 1 As shown, the treatment of titanium concentrate acid hydrolysis slurry includes the following steps: S10′, performing a first treatment to remove soluble components from the titanium concentrate acid hydrolysis slurry to obtain the titanium concentrate acid hydrolysis slurry after the first treatment.

[0040] S20′, performing a second treatment to remove soluble components from the titanium concentrate acid hydrolysis slurry after the first treatment to obtain the titanium concentrate acid hydrolysis slurry after the second treatment.

[0041] S30′, performing mud neutralization treatment on the acid hydrolysis mud of the titanium concentrate after the second treatment to obtain mud neutralized material.

[0042] S40′, sequentially subjecting the slurry-neutralized material to sedimentation and pressing treatment to obtain titanium concentrate acid hydrolysis slurry-neutralized titanium gypsum.

[0043] like Figure 3 As shown, in one embodiment, in step S10′, the following steps are also included: S11′, performing a pulping treatment on the acid hydrolysis slurry of the titanium concentrate to obtain a primary pulping material.

[0044] S12′, performing a pressing process on the first pulping material to obtain a first pressing material and a first pressing filtrate.

[0045] In one embodiment, step S20′ further includes the following steps: S21′, performing secondary pulping treatment on the primary pressed material to obtain secondary pulped material.

[0046] S22′, performing secondary pressing on the secondary pulping material to obtain secondary pressing material and secondary pressing filtrate.

[0047] In one embodiment, step 30′ further includes the following steps: S31′, performing a three-time beating treatment on the secondary pressed material to obtain a three-time beating material.

[0048] S32′, subjecting the three-time beating materials to mud wet ball milling neutralization treatment to obtain mud wet ball milling neutralized materials.

[0049] S33′, subjecting the slurry wet ball mill neutralized material to slurry stirring and neutralization treatment to obtain slurry stirring and neutralized material.

[0050] S34′, sequentially subjecting the slurry agitation and neutralization materials to sedimentation and pressing treatments to obtain titanium concentrate acid hydrolysis slurry and titanium gypsum.

[0051] The main components of the titanium concentrate acid hydrolysis slurry of the present invention, in addition to water, are unreacted minerals insoluble in water and reaction products such as colloidal silica and calcium sulfate solids, as well as a small amount of soluble sulfates such as titanium oxysulfate and ferrous sulfate that are soluble in water. The embodiment of the present invention uses two pulping and two pressing processes of "one pulping process + one pressing process + two pulping processes + two pressing processes" to make the soluble components such as titanium oxysulfate and ferrous sulfate enter the first pressing filtrate in step S12' and the second pressing filtrate in step S22' respectively. The first pressing filtrate in step S12' and the second pressing filtrate in step S22' can be returned to the acid hydrolysis process as titanium-containing low-degree water and used in the titanium concentrate acid hydrolysis solid phase leaching process, thereby increasing the titanium yield.

[0052] In addition, since the acid components, especially the free sulfuric acid, and the sulfate content in the titanium concentrate acid hydrolysis slurry after two pulping and two pressing processes are low, only a small amount of quicklime, which has a better neutralizing effect on low-content sulfate, needs to be added for neutralization to achieve a better neutralization effect, thereby effectively reducing the consumption of the neutralizer. In addition, the colloidal silica and calcium sulfate in the titanium concentrate acid hydrolysis slurry are easy to adsorb impurity particles, and the sedimentation speed is slow during the sedimentation process. In the case of sedimentation of the titanium concentrate acid hydrolysis slurry alone, the sedimentation time can be extended, which is conducive to improving the sedimentation effect of the difficult-to-settle titanium concentrate acid hydrolysis slurry.

[0053] In one embodiment, in step S10, the neutralization time of the primary neutralization treatment of the wastewater is 0.5h to 1h, and the neutralization temperature is 50° C. to 80° C. In step S20, the neutralization time of the secondary neutralization treatment of the wastewater is 2h to 4h, and the neutralization temperature is 50° C. to 80° C. In step S30′, the neutralization time of the slurry neutralization treatment is 2h to 4h, and the neutralization temperature is 50° C. to 80° C.

[0054] In one embodiment, in step S11 and step S12, the pH of the wastewater primary wet ball mill neutralization material and the wastewater primary stirring neutralization material are controlled to be 3.5-4.0 respectively. In step S21 and step S22, the pH of the wastewater secondary wet ball mill neutralization material and the wastewater secondary stirring neutralization material are controlled to be 7.0-7.5 respectively. It should be understood by those skilled in the art that the sulfuric acid concentration of the acidic wastewater of the present invention and the concentration of sulfates such as ferrous sulfate and ferric sulfate that need to be neutralized are constant, and the acidic waste acid feed is stable, so the amount of neutralizer added is stable. If there is a fluctuation, the fluctuation will also be small and will not have a greater impact. Therefore, in step S10, the feed volume ratio of acidic wastewater to lime milk can be controlled according to the pH value of the wastewater primary wet ball mill neutralization material. In step S20, the feed volume ratio of acidic wastewater to quicklime milk can be controlled according to the pH value of the wastewater secondary wet ball mill neutralization material. Furthermore, when the pH value is within the control lower limit, the pH value can be adjusted by appropriately adjusting the amount of limestone milk or quicklime milk added to meet the neutralization process conditions.

[0055] In step S32' and step S33', the pH of the mud wet ball milling neutralized material and the mud stirring neutralized material are controlled to be 7.0-7.5 respectively. In one embodiment, the neutralizer used in the mud neutralization treatment in step S30' is quicklime milk. It should be understood by those skilled in the art that the feed volume ratio of the tertiary pulping material and quicklime milk in step S32' can be controlled according to the pH value of the mud wet ball milling neutralized material. In addition, when the pH value is at the control lower limit, the pH value can be adjusted by appropriately adjusting the amount of quicklime milk added to meet the neutralization process conditions.

[0056] In one embodiment, limestone milk is prepared by squeezing water from limestone and existing titanium gypsum, and the CaO content in the limestone is ≥50.4 wt %. Quicklime milk is prepared by squeezing water from quicklime and existing titanium gypsum, and the CaO content in the quicklime is ≥85.0 wt %. Existing titanium gypsum is titanium gypsum formed after neutralization of existing acidic wastewater, and the existing titanium gypsum has a dry basis of CaSO4•2H2O ≥85.00%, and a moisture content ≤20%.

[0057] In one embodiment, the primary stirring and neutralization treatment of wastewater in step S12, the secondary stirring and neutralization treatment of wastewater in step S22, and the slurry stirring and neutralization treatment in step S33′ are all carried out in a stirring tank and frame stirring is used to prevent solid materials from sinking to the bottom. The neutralization stirring speed is 250r / min to 500r / min.

[0058] In one embodiment, in step S31, the sedimentation time is 12h to 24h, and in step S34', the sedimentation time is 24h to 48h. It should be understood by those skilled in the art that the sedimentation process of the acidic wastewater is carried out simultaneously with the sedimentation process of the titanium concentrate acid hydrolysis slurry. The sedimentation temperature is 25°C to 40°C, and the sedimentation stirring speed is 1r / min to 2r / min. In steps S10', S20' and 30', the beating time is 1h to 2h, and the beating stirring speed is 500r / min to 1000r / min. In steps S31, S10', S20', 30' and 40', the solid content of the squeeze is ≥80%.

[0059] Since the titanium gypsum in the acid hydrolysis slurry of titanium concentrate contains a large amount of unreacted ore powder and reaction products such as silicate and calcium sulfate, if it is mixed with the titanium gypsum in acidic wastewater and stacked and mixed together as a cement retarder raw material, the sulfur trioxide content in the titanium gypsum in the acidic wastewater will be low and the quality of the titanium gypsum will be reduced. Therefore, the titanium gypsum in the acidic wastewater and the titanium gypsum in the acid hydrolysis slurry of titanium concentrate of the present invention are stacked separately and used for different purposes according to their respective characteristics. For example, the titanium gypsum in the acidic wastewater is used as a cement retarder raw material, and the titanium gypsum in the acid hydrolysis slurry of titanium concentrate is used as a titanium concentrate acid hydrolysis raw material. In addition, the sulfur trioxide content in the titanium gypsum in the acidic wastewater of the present invention is ≥30%.

[0060] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0061] Example 1 The acid wastewater from the sulfuric acid process titanium dioxide acid waste and the titanium concentrate acid hydrolysis sludge are treated separately.

[0062] Treatment of acidic wastewater (sulfuric acid concentration of 3.33wt%) includes the following steps: S10, performing primary neutralization treatment on the acidic wastewater to obtain primary neutralized wastewater material, step S10 further comprising the following steps: S11, performing a wastewater primary wet ball milling neutralization treatment on the acidic wastewater to obtain a wastewater primary wet ball milling neutralization material; S12, performing a first-level stirring neutralization treatment on the first-level wet ball milling neutralized material of the wastewater to obtain the first-level stirring neutralized material of the wastewater.

[0063] S20, performing secondary neutralization treatment on the primary neutralization material of the wastewater to obtain secondary neutralization material of the wastewater, and step S20 further includes the following steps: S21, performing wastewater secondary wet ball milling neutralization treatment on the wastewater primary stirring neutralization material to obtain wastewater secondary wet ball milling neutralization material; S22, performing wastewater secondary stirring neutralization treatment on the wastewater secondary wet ball milling neutralization material to obtain wastewater secondary stirring neutralization material.

[0064] S30, sequentially sedimenting and squeezing the wastewater secondary neutralization material to obtain acidic wastewater neutralized titanium gypsum, step S30 further includes the following steps: S31, the secondary stirring and neutralizing materials of the wastewater are sequentially subjected to sedimentation and pressing treatment to obtain acidic wastewater neutralizing titanium gypsum.

[0065] Treatment of titanium concentrate acid slurry includes the following steps: S10′, performing a first treatment to remove soluble components from the titanium concentrate acid hydrolysis slurry to obtain the titanium concentrate acid hydrolysis slurry after the first treatment, step S10′ further includes the following steps: S11′, performing a primary pulping treatment on the acid hydrolysis slurry of the titanium concentrate to obtain a primary pulping material; S12′, performing a pressing process on the first pulping material to obtain a first pressing material and a first pressing filtrate.

[0066] S20′, performing a second treatment to remove soluble components from the titanium concentrate acid hydrolysis slurry after the first treatment to obtain the titanium concentrate acid hydrolysis slurry after the second treatment, step S20′ further includes the following steps: S21′, performing secondary pulping treatment on the primary pressed material to obtain secondary pulped material; S22′, performing secondary pressing on the secondary pulping material to obtain secondary pressing material and secondary pressing filtrate.

[0067] S30′, performing mud neutralization treatment on the acid hydrolysis mud of the titanium concentrate after the second treatment to obtain a mud neutralized material, step S30′ further includes the following steps: S31′, performing a three-time beating treatment on the secondary pressed material to obtain a three-time beating material; S32′, performing a mud wet ball milling neutralization treatment on the three-beating materials to obtain a mud wet ball milling neutralized material; S33′, performing a mud stirring and neutralization treatment on the mud wet ball mill neutralized material to obtain a mud stirring and neutralized material; S34′, sequentially subjecting the slurry agitation and neutralization materials to sedimentation and pressing treatments to obtain titanium concentrate acid hydrolysis slurry and titanium gypsum.

[0068] S40′, sequentially subjecting the slurry-neutralized material to sedimentation and pressing treatment to obtain titanium concentrate acid hydrolysis slurry-neutralized titanium gypsum.

[0069] In step S10, the neutralization time of the primary neutralization treatment of the wastewater is 0.5 h, and the neutralization temperature is 80° C. In step S20, the neutralization time of the secondary neutralization treatment of the wastewater is 2 h, and the neutralization temperature is 80° C. In step S30′, the neutralization time of the sludge neutralization treatment is 2 h, and the neutralization temperature is 80° C.

[0070] In step S11 and step S12, the pH of the wastewater primary wet ball milling neutralized material and the wastewater primary stirring neutralized material are controlled to be 3.5 respectively. In step S21 and step S22, the pH of the wastewater secondary wet ball milling neutralized material and the wastewater secondary stirring neutralized material are controlled to be 7.0 respectively. In step S32' and step S33', the pH of the mud wet ball milling neutralized material and the mud stirring neutralized material are controlled to be 7.0 respectively.

[0071] The neutralizer used in the primary neutralization treatment of wastewater in step S10 is limestone milk, and the CaO content in limestone is 50.4 wt %. The neutralizer used in the secondary neutralization treatment of wastewater in step S20 and the slurry neutralization treatment in step S30′ is quicklime milk, and the CaO content in quicklime is 85.0 wt %.

[0072] The primary stirring and neutralization treatment of wastewater in step S12, the secondary stirring and neutralization treatment of wastewater in step S22, and the slurry stirring and neutralization treatment in step S33' are all carried out in a stirring tank and are treated by frame stirring, and the neutralization stirring speed is 250r / min.

[0073] In step S31, the sedimentation time is 12 hours. In step S34', the sedimentation time is 24 hours, the sedimentation temperature is 40°C, and the sedimentation stirring speed is 1 r / min. In steps S10', S20' and 30', the beating time is 1 hour, and the beating stirring speed is 1000 r / min.

[0074] In step S31, step S10', step S20', step 30' and step 40', the solid content of the pressing is 80%. The sulfur trioxide content in the acidic wastewater and the titanium gypsum is 32.02%.

[0075] Example 2 The difference between Example 2 and Example 1 is that: In step S10, the neutralization time of the primary neutralization treatment of the wastewater is 0.8 h, and the neutralization temperature is 65° C. In step S20, the neutralization time of the secondary neutralization treatment of the wastewater is 3 h, and the neutralization temperature is 65° C. In step S30′, the neutralization time of the sludge neutralization treatment is 3 h, and the neutralization temperature is 65° C.

[0076] In step S11 and step S12, the pH of the wastewater primary wet ball milling neutralized material and the wastewater primary stirring neutralized material are controlled to be 3.8 respectively. In step S21 and step S22, the pH of the wastewater secondary wet ball milling neutralized material and the wastewater secondary stirring neutralized material are controlled to be 7.2 respectively. In step S32' and step S33', the pH of the mud wet ball milling neutralized material and the mud stirring neutralized material are controlled to be 7.2 respectively.

[0077] The primary stirring and neutralization treatment of wastewater in step S12, the secondary stirring and neutralization treatment of wastewater in step S22, and the slurry stirring and neutralization treatment in step S33' are all carried out in a stirring tank and are treated by frame stirring, and the neutralization stirring speed is 350r / min.

[0078] In step S31, the sedimentation time is 18 hours. In step S34', the sedimentation time is 36 hours, the sedimentation temperature is 35°C, and the sedimentation stirring speed is 1.5 r / min. In steps S10', S20' and 30', the beating time is 1.5 hours, and the beating stirring speed is 700 r / min.

[0079] In step S31, step S10', step S20', step 30' and step 40', the pressed solid content is 85%. The sulfur trioxide content in the acidic wastewater and titanium gypsum is 33.54%.

[0080] Example 3 The difference between Example 3 and Example 1 is that: In step S10, the neutralization time of the primary neutralization treatment of the wastewater is 1 hour, and the neutralization temperature is 50° C. In step S20, the neutralization time of the secondary neutralization treatment of the wastewater is 4 hours, and the neutralization temperature is 50° C. In step S30′, the neutralization time of the sludge neutralization treatment is 4 hours, and the neutralization temperature is 50° C.

[0081] In step S11 and step S12, the pH of the wastewater primary wet ball milling neutralized material and the wastewater primary stirring neutralized material are controlled to be 4.0 respectively. In step S21 and step S22, the pH of the wastewater secondary wet ball milling neutralized material and the wastewater secondary stirring neutralized material are controlled to be 7.5 respectively. In step S32' and step S33', the pH of the mud wet ball milling neutralized material and the mud stirring neutralized material are controlled to be 7.5 respectively.

[0082] The primary stirring and neutralization treatment of wastewater in step S12, the secondary stirring and neutralization treatment of wastewater in step S22, and the slurry stirring and neutralization treatment in step S33' are all carried out in a stirring tank and are treated by frame stirring, and the neutralization stirring speed is 500r / min.

[0083] In step S31, the sedimentation time is 24 hours. In step S34', the sedimentation time is 48 hours, the sedimentation temperature is 25°C, and the sedimentation stirring speed is 2 r / min. In steps S10', S20' and 30', the beating time is 2 hours, and the beating stirring speed is 500 r / min.

[0084] In step S31, step S10', step S20', step 30' and step 40', the pressed solid content is 85%. The sulfur trioxide content in the acidic wastewater and titanium gypsum is 32.67%.

[0085] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, the acidic wastewater in the sulfuric acid process titanium dioxide acid waste and the titanium concentrate acid hydrolysis sludge are mixed together for neutralization treatment.

[0086] Acidic wastewater and titanium concentrate acid hydrolysis sludge were subjected to primary stirring and neutralization treatment (lime milk was used as the neutralizer) to obtain primary stirring and neutralization material (pH was controlled at 3.5). The primary stirring and neutralization material was subjected to secondary stirring and neutralization treatment (quicklime milk was used as the neutralizer) to obtain secondary stirring and neutralization material (pH was controlled at 7.0). The secondary stirring and neutralization material was settled and pressed to obtain titanium gypsum. The neutralization time of the primary stirring and neutralization treatment was 0.5h, and the neutralization temperature was 80℃. The neutralization time of the secondary stirring and neutralization treatment was 2h, and the neutralization temperature was 80℃. The settling time of the secondary stirring and neutralization material was 36h, the settling temperature was 40℃, and the settling stirring speed was 1r / min. The solid content of the squeezed material was 80%.

[0087] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that in Comparative Example 2, the acidic wastewater in the sulfuric acid process titanium dioxide acid waste and the titanium concentrate acid hydrolysis sludge are mixed together for neutralization treatment.

[0088] The acidic wastewater and the acid hydrolysis sludge of titanium concentrate were subjected to primary stirring and neutralization treatment (the neutralizer was limestone milk), and the primary stirring and neutralization material was obtained (the pH was controlled at 3.8). The primary stirring and neutralization material was subjected to secondary stirring and neutralization treatment (the neutralizer was quicklime milk), and the secondary stirring and neutralization material was obtained (the pH was controlled at 7.2). The secondary stirring and neutralization material was settled and pressed to obtain titanium gypsum. The neutralization time of the primary stirring and neutralization treatment was 0.8h, and the neutralization temperature was 65℃. The neutralization time of the secondary stirring and neutralization treatment was 3h, and the neutralization temperature was 65℃. The settling time of the secondary stirring and neutralization material was 48h, the settling temperature was 35℃, and the settling stirring speed was 1.5r / min. The solid content of the squeezed material was 85%.

[0089] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that in Comparative Example 3, the acidic wastewater in the sulfuric acid process titanium dioxide acid waste and the titanium concentrate acid hydrolysis sludge are mixed together for neutralization treatment.

[0090] The acidic wastewater and the acid hydrolysis sludge of titanium concentrate were subjected to primary stirring and neutralization treatment (the neutralizer was limestone milk), and the primary stirring and neutralization material was obtained (the pH was controlled to be 4.0). The primary stirring and neutralization material was subjected to secondary stirring and neutralization treatment (the neutralizer was quicklime milk), and the secondary stirring and neutralization material was obtained (the pH was controlled to be 7.5). The secondary stirring and neutralization material was settled and pressed to obtain titanium gypsum. The neutralization time of the primary stirring and neutralization treatment was 1h, and the neutralization temperature was 50℃. The neutralization time of the secondary stirring and neutralization treatment was 4h, and the neutralization temperature was 50℃. The settling time of the secondary stirring and neutralization material was 60h, the settling temperature was 25℃, and the settling stirring speed was 2r / min. The solid content of the squeezed material was 85%.

[0091] The sulfur trioxide content in the neutralized titanium gypsum in the acidic wastewater obtained in Examples 1 to 3 and the titanium gypsum obtained in Comparative Examples 1 to 3, as well as the corresponding output, were measured, and the consumption of limestone and quicklime in the above Examples and Comparative Examples, as well as the neutralization cost were counted. The results are shown in Table 1.

[0092] Table 1 Comparison of results of examples and comparative examples

[0093] Note: The price of limestone is RMB 121 / ton, and the calcium oxide content is 50.4%. The price of quicklime is RMB 415 / ton, and the calcium oxide content is 85.0%. Titanium gypsum is calculated on a dry basis, and the settling time of the neutralized material is calculated based on the longest settling time of the neutralized material.

[0094] As can be seen from Table 1, the method of separately treating the acidic wastewater in the acidic waste and the titanium concentrate acid hydrolysis sludge of the present invention can reduce the consumption of quicklime, sedimentation time, neutralization cost per ton of titanium dioxide, and the output of titanium gypsum per ton of titanium dioxide, and increase the sulfur trioxide content in titanium gypsum.

[0095] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for treating acidic wastes of titanium dioxide produced by sulfuric acid process, characterized in that: The acid waste of titanium dioxide produced by the sulfuric acid process includes acid wastewater and acid hydrolysis sludge of titanium concentrate. The method includes separately treating the acid wastewater and the acid hydrolysis sludge of titanium concentrate, wherein: Treatment of acidic wastewater involves the following steps: S10, performing primary neutralization treatment on the acidic wastewater to obtain primary neutralization material for wastewater; S20, performing secondary neutralization treatment on the primary neutralization material of the wastewater to obtain secondary neutralization material of the wastewater; S30, sequentially performing sedimentation and pressing treatments on the secondary neutralization materials of the wastewater to obtain acidic wastewater neutralizing titanium gypsum; Treatment of titanium concentrate acid slurry includes the following steps: S10′, performing a first treatment to remove soluble components from the titanium concentrate acid hydrolysis slurry to obtain the titanium concentrate acid hydrolysis slurry after the first treatment; S20′, performing a second treatment to remove soluble components from the titanium concentrate acid hydrolysis slurry after the first treatment to obtain the titanium concentrate acid hydrolysis slurry after the second treatment; S30′, performing mud neutralization treatment on the acid hydrolysis mud of the titanium concentrate after the second treatment to obtain a mud neutralized material; S40′, sequentially subjecting the slurry-neutralized material to sedimentation and pressing treatment to obtain titanium concentrate acid hydrolysis slurry-neutralized titanium gypsum.

2. The processing method according to claim 1, characterized in that: In step S10, the following steps are also included: S11, performing a wastewater primary wet ball milling neutralization treatment on the acidic wastewater to obtain a wastewater primary wet ball milling neutralization material; S12, performing a first-level stirring and neutralization treatment on the first-level wet ball milling neutralized material of the wastewater to obtain a first-level stirring and neutralized material of the wastewater; In step S20, the following steps are also included: S21, performing wastewater secondary wet ball milling neutralization treatment on the wastewater primary stirring neutralization material to obtain wastewater secondary wet ball milling neutralization material; S22, performing wastewater secondary stirring neutralization treatment on the wastewater secondary wet ball milling neutralization material to obtain wastewater secondary stirring neutralization material; In step S30, the following steps are also included: S31, sequentially performing sedimentation and pressing treatment on the secondary stirring and neutralization materials of the wastewater to obtain acidic wastewater neutralizing titanium gypsum; In step S10′, the following steps are also included: S11′, performing a primary pulping treatment on the acid hydrolysis slurry of the titanium concentrate to obtain a primary pulping material; S12′, performing a pressing process on the first pulping material to obtain a first pressing material and a first pressing filtrate; In step S20′, the following steps are also included: S21′, performing secondary pulping treatment on the primary pressed material to obtain secondary pulped material; S22′, performing secondary pressing on the secondary pulping material to obtain secondary pressing material and secondary pressing filtrate; In step 30', the following steps are also included: S31′, performing a three-time beating treatment on the secondary pressed material to obtain a three-time beating material; S32′, performing a mud wet ball milling neutralization treatment on the three-beating materials to obtain a mud wet ball milling neutralized material; S33′, performing a mud stirring and neutralization treatment on the mud wet ball mill neutralized material to obtain a mud stirring and neutralized material; S34′, sequentially subjecting the slurry agitation and neutralization materials to sedimentation and pressing treatments to obtain titanium concentrate acid hydrolysis slurry and titanium gypsum.

3. The processing method according to claim 1, characterized in that: In step S10, the neutralization time of the primary neutralization treatment of the wastewater is 0.5h to 1h, and the neutralization temperature is 50°C to 80°C; In step S20, the neutralization time of the secondary neutralization treatment of the wastewater is 2h to 4h, and the neutralization temperature is 50°C to 80°C; In step S30', the neutralization time of the mud neutralization treatment is 2 hours to 4 hours, and the neutralization temperature is 50°C to 80°C.

4. The processing method according to claim 2, characterized in that: In step S11 and step S12, the pH of the wastewater primary wet ball milling neutralization material and the wastewater primary stirring neutralization material are controlled to be 3.5-4.0 respectively; In step S21 and step S22, the pH of the wastewater secondary wet ball milling neutralization material and the wastewater secondary stirring neutralization material are controlled to be 7.0-7.5 respectively; In step S32' and step S33', the pH of the material neutralized by slurry wet ball milling and the material neutralized by slurry stirring are controlled to be 7.0-7.5 respectively.

5. The processing method according to claim 1, characterized in that: The neutralizer used in the primary neutralization treatment of wastewater in step S10 is limestone milk, and the neutralizer used in the secondary neutralization treatment of wastewater in step S20 and the sludge neutralization treatment in step S30' are both quicklime milk.

6. The processing method according to claim 5, characterized in that: Limestone milk is prepared by mixing limestone with existing titanium gypsum squeezed water, and the CaO content in the limestone is ≥50.4 wt %; The quicklime milk is prepared by quicklime and existing titanium gypsum squeezed water, and the CaO content in the quicklime is ≥85.0 wt %; wherein, The existing titanium gypsum has CaSO4•2H2O≥85.00% on a dry basis and a moisture content≤20%.

7. The processing method according to claim 2, characterized in that: The primary stirring and neutralization treatment of wastewater in step S12, the secondary stirring and neutralization treatment of wastewater in step S22, and the slurry stirring and neutralization treatment in step S33' are all carried out in a stirring tank and are treated by frame stirring, and the neutralization stirring speed is 250r / min to 500r / min.

8. The processing method according to claim 2, characterized in that: In step S31, the sedimentation time is 12h to 24h, and in step S34', the sedimentation time is 24h to 48h; the sedimentation temperature is 25°C to 40°C, and the sedimentation stirring speed is 1r / min to 2r / min; In step S10′, step S20′ and step 30′, the beating time is 1 h to 2 h, and the beating stirring speed is 500 r / min to 1000 r / min; In step S31, step S10', step S20', step 30' and step 40', the pressed solid content is ≥ 80%.

9. The processing method according to claim 2, characterized in that: The first pressing filtrate in step S12' and the second pressing filtrate in step S22' are both used as titanium-containing low-density water for leaching of solid phase matter from the acid hydrolysis of titanium concentrate.

10. The processing method according to claim 1, characterized in that: The insoluble solid content in the acidic wastewater is ≤0.3g / L, the sulfuric acid concentration is 2wt%~5wt%, the sulfur trioxide content in the neutralized titanium gypsum in the acidic wastewater is ≥30%, and the neutralized titanium gypsum in the acidic wastewater is used as a raw material for cement retarder, and the neutralized titanium gypsum in the titanium concentrate acid hydrolysis slurry is used as a raw material for titanium concentrate acid hydrolysis.

Images