Method for recycling and utilizing titanium dioxide waste acid in sulfuric acid production

Abstract

The application discloses a method for recycling and utilizing titanium white waste acid in sulfuric acid production, and comprises the following steps: S1, concentrating and purifying treatment, concentrating the titanium white waste acid to obtain acid liquid with a concentration of 35%-40%; S2, pretreatment of the acid liquid, cooling the acid liquid, and filtering and removing impurities after cooling; S3, diffusion dialysis treatment, the filtered waste acid and water enter a diffusion dialyzer from two sides of an anion homogeneous membrane, so that acid and salt in the waste acid are preliminarily separated; and S4, metal ion treatment, removing iron ion components in the sulfuric acid solution, and finally obtaining pure dilute sulfuric acid. The application finally obtains pure dilute sulfuric acid through treatment, and the pure dilute sulfuric acid is sent to a dry absorption process of sulfuric acid production to replace water for SO3 absorption and sulfuric acid dilution. Since ferrous ions and other metal ions are removed, the problem of dry tower and absorption tower blockage caused by ferrous sulfate crystallization does not occur, and the purpose of recycling and utilizing the waste acid is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of titanium white waste acid, and particularly relates to a recovery and utilization method of titanium white waste acid in sulfuric acid production. BACKGROUND

[0002] Due to the coexistence of free sulfuric acid and sulfate in the titanium white waste acid, most domestic titanium dioxide production enterprises mainly adopt the following two treatment processes: 1. Neutralization treatment and discharge of waste acid: waste acid is discharged to the sewage treatment process with waste water, and is treated by neutralization and aeration with limestone, lime and the like, and after treatment and pressing, the waste water is discharged up to the standard, and the waste residue (yellow gypsum) is transported to a dam opening for landfill; 2. Concentration and recycling of waste acid: the waste acid is treated by vacuum concentration, and the concentrated waste acid is precipitated after cooling to remove sulfate impurities, and the filtered concentrated waste acid with a concentration of 45-50% is produced, and the clarified concentrated waste acid is returned to the acidolysis process of the titanium dioxide production line as an initiating acid for recycling; in the first treatment process, due to the high content of ferrous sulfate and sulfuric acid in the waste acid, the input amount of neutralization treatment agent is greatly increased, and the working load of the neutralization and aeration system is also increased, and at the same time, the discharge amount of waste residue (yellow gypsum) after sewage treatment is almost doubled, which increases the waste residue treatment cost of the company; on the other hand, the neutralization treatment and discharge of waste acid causes waste of sulfur resources, which does not conform to the environmental protection concept of clean production and development of circular economy advocated by the state at present; from the perspective of emission reduction, consumption reduction and resource recovery, concentration and recycling of waste acid should be an effective method for titanium dioxide enterprises to recover a large amount of waste acid. However, direct concentration treatment of high-sulfate waste acid will cause problems such as system blockage, reduced heat exchange efficiency, severe abrasion of running equipment, and reduced production capacity of concentrated acid, due to the precipitation of a large amount of sulfate with the increase of acidity and temperature during the concentration process. At the same time, due to the difficulty in washing the sulfate scale layer precipitated under high temperature, the equipment and pipeline blockage is accelerated, and the time for clearing and unblocking is also greatly prolonged.

[0003] Therefore, it is necessary to relatively separate the free sulfuric acid and the sulfate in the waste acid, purify the waste acid, and obtain pure dilute sulfuric acid. SUMMARY

[0004] The present application aims to provide a recovery and utilization method of titanium white waste acid in sulfuric acid production to solve the problems in the background art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution:

[0006] A recovery and utilization method of titanium white waste acid in sulfuric acid production, comprising the following steps:

[0007] Step S1, concentration and purification treatment, the titanium white waste acid is treated by concentration to obtain an acid liquid with a concentration of 35%-40%;

[0008] Step S2, the pretreatment of the acid solution, the acid solution is cooled, and impurities are removed after cooling by filtration;

[0009] Step S3, diffusion dialysis treatment, the filtered waste acid and water are respectively introduced into the diffusion dialysis device from two sides of the anion homogeneous membrane, so that the acid and the salt in the waste acid are preliminarily separated;

[0010] Step S4, metal ion treatment, ammonium sulfate is generated after the separated acid is neutralized by adding ammonia water, and the pH of the system is controlled to precipitate positive titanate, which is recovered for titanium dioxide production;

[0011] Step S5, a certain amount of concentrated hydrochloric acid is added to the salt in the separated waste acid, and a complexation reaction is carried out with 1-ethyl-3-methyl imidazole, after heating and stirring, petroleum ether is used for extraction, full oscillation, static, and then a certain amount of 10% sodium hydroxide solution is added to the organic phase for back extraction, full oscillation, static, and separation, and then filtration is performed to obtain pure dilute sulfuric acid with low iron ion concentration.

[0012] Preferably, the concentration process in step S1 is that the metatitanic acid slurry after hydrolysis is filtered to produce waste acid with a concentration of 20%-30% which is filtered by a filter and then vacuum concentrated.

[0013] Preferably, the concentration of the waste acid produced by filtering the metatitanic acid slurry after hydrolysis is 25%.

[0014] Preferably, the concentration of the acid solution in step S1 is 38%.

[0015] Preferably, the temperature after cooling in step S2 is 0-40℃, and a 0.1 μm uniform pore membrane filter is used for filtration.

[0016] Preferably, the removal process of iron ions in step S5 is replaced by the following steps:

[0017] Ammonia water is added to the salt in the separated waste acid, the pH is controlled, and ferrous hydroxide precipitate is precipitated and removed by filtration; then an oxidizing agent is added in proportion, the remaining Fe 2+ is oxidized to Fe 3+ , the pH is adjusted, and ferric hydroxide precipitate is precipitated and removed to obtain a pure ammonium sulfate solution; the ammonium sulfate solution is concentrated, replacing the traditional mirabilite solution in the production process of precipitated barium sulfate, and a double decomposition reaction occurs with barium sulfide solution in proportion to produce barium sulfate precipitate and byproduct ammonium sulfide, which is washed, dried and crushed to produce the product of precipitated barium sulfate.

[0018] The sulfuric acid concentration of the pure dilute sulfuric acid in step S5 is 33%-35%, and the ferrous ion concentration is ≤300 mg / L.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] The present application firstly concentrates the waste acid, then filters the waste acid to remove impurities, preliminarily separates the acid from the salt in the waste acid, finally removes the iron ion component in the sulfuric acid solution through metal ion treatment, and finally obtains pure dilute sulfuric acid. The obtained pure dilute sulfuric acid is sent to the dry absorption process of sulfur-burning sulfuric acid production to replace water for SO3 absorption and sulfuric acid dilution. Since the metal ions such as ferrous ions are removed, the problems of dry tower and absorption tower blockage caused by ferrous sulfate crystallization do not occur, or the waste acid is recovered and utilized after being produced and separated by precipitation. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0022] The method for recycling and utilizing the titanium dioxide waste acid in sulfur-burning sulfuric acid production in the present embodiment comprises the following steps:

[0023] Step S1, concentration and purification treatment, the titanium dioxide waste acid is concentrated and treated to obtain an acid solution with a concentration of 35%-40%;

[0024] Step S2, acid solution pretreatment, the acid solution is cooled, and after cooling, the acid solution is filtered to remove impurities;

[0025] Step S3, diffusion dialysis treatment, the filtered waste acid and water enter the diffusion dialysis device from the two sides of the anion homogeneous membrane, so that the acid and the salt in the waste acid are preliminarily separated;

[0026] Step S4, metal ion treatment, after the separated acid is neutralized by adding ammonia water, ammonium sulfate is generated, and the pH of the system is controlled to precipitate positive titanic acid, which is recycled for titanium dioxide production;

[0027] Step S5, a certain amount of concentrated hydrochloric acid is added to the separated salt in the waste acid, and a complex reaction is carried out with 1-ethyl-3-methyl imidazole. After heating and stirring, petroleum ether is used for extraction, full oscillation, static, and layering. Then a certain amount of mass concentration of 10% sodium hydroxide solution is added to the organic phase for back extraction, full oscillation, static, layering, and filtration, so that pure dilute sulfuric acid with low iron ion concentration is obtained.

[0028] The concentration process in step S1 is as follows: the hydrolyzed metatitanic acid slurry is filtered to produce waste acid with a concentration of 20%-30%, and then the waste acid is filtered through a filter and vacuum concentrated.

[0029] The waste acid slurry after hydrolysis is filtered to produce a waste acid with a concentration of 25%.

[0030] The concentration of the acid solution in step S1 is 38%.

[0031] The temperature after cooling in step S2 is 0-40℃, and the filtration uses a 0.1 μm uniform pore membrane filter.

[0032] The iron ion removal process in step S5 is replaced by the following steps:

[0033] Ammonia is added to the separated waste acid, the pH is controlled, ferrous hydroxide precipitate is precipitated, and the precipitate is removed by filtration; an oxidizing agent is then added in proportion to oxidize the remaining Fe 2+ to Fe 3+ , the pH is adjusted, ferric hydroxide precipitate is precipitated, and the precipitate is removed by filtration to obtain a pure ammonium sulfate solution; after the ammonium sulfate solution is concentrated, it replaces the traditional mirabilite solution in the production process of precipitated barium sulfate, and reacts with barium sulfide solution in proportion to produce barium sulfate precipitate and byproduct ammonium sulfide, which is washed, dried, and crushed to produce the precipitated barium sulfate product.

[0034] The sulfuric acid concentration of the pure dilute sulfuric acid in step S4 is 33%-35%, and the ferrous ion concentration is ≤300 mg / L. Embodiment

[0035] The method for recycling and utilizing titanium white waste acid in sulfuric acid production of sulfur, according to the embodiment, comprises the following steps:

[0036] Step S1, concentration and purification treatment, the titanium white waste acid is concentrated to obtain an acid solution with a concentration of 35%;

[0037] Step S2, pretreatment of the acid solution, the acid solution is cooled and filtered to remove impurities after cooling;

[0038] Step S3, diffusion dialysis treatment, the filtered waste acid and water enter the diffusion dialyzer from both sides of the anion homogeneous membrane, so that the acid and salt in the waste acid are preliminarily separated;

[0039] Step S4, metal ion treatment, ammonium sulfate is generated after the separated acid is neutralized with ammonia, and the pH of the system is controlled to precipitate metatitanic acid, which is recovered for titanium dioxide production;

[0040] Step S5, concentrated hydrochloric acid is added to the salt in the separated waste acid, and 1-ethyl-3-methylimidazole is chlorinated for complexation. After heating and stirring, petroleum ether is used for extraction, full oscillation, static, and layering. Then a certain amount of 10% sodium hydroxide solution is added to the organic phase for back extraction, full oscillation, static, layering, and filtration to obtain pure dilute sulfuric acid with low iron ion concentration.

[0041] The concentration process in step S1 is that the metatitanic acid slurry after hydrolysis is filtered to produce waste acid with a concentration of 20%, which is filtered through a filter and then vacuum concentrated.

[0042] The temperature of the cooling process in step S2 is 0-40℃, and the filtration is performed using a 0.1 μm uniform pore membrane filter.

[0043] The iron ion removal process in step S5 is replaced by the following steps:

[0044] Ammonia is added to the separated waste acid to control the pH, and ferrous hydroxide precipitate is precipitated and removed by filtration; then an oxidizing agent is added in proportion to oxidize the remaining Fe 2+ to Fe 3+ , adjust the pH, precipitate the ferric hydroxide precipitate, and remove it by filtration to obtain pure ammonium sulfate solution; after the ammonium sulfate solution is concentrated, it replaces the traditional mirabilite solution in the production process of precipitated barium sulfate, and reacts with barium sulfide solution in proportion to produce barium sulfate precipitate and byproduct ammonium sulfide, which is washed, dried and crushed to produce precipitated barium sulfate product.

[0045] The sulfuric acid concentration of the pure dilute sulfuric acid in step S4 is 33%, and the ferrous ion concentration is ≤300 mg / L. Embodiment

[0046] The method for recycling and utilizing titanium white waste acid in sulfuric acid production of sulfur, comprising the following steps:

[0047] Step S1, concentration and purification treatment, the titanium white waste acid is concentrated to obtain an acid solution with a concentration of 40%;

[0048] Step S2, pretreatment of the acid solution, the acid solution is cooled and filtered to remove impurities;

[0049] Step S3, diffusion dialysis treatment, the filtered waste acid and water enter the diffusion dialysis device from the two sides of the anion homogeneous membrane, so that the acid and salt in the waste acid are preliminarily separated;

[0050] Step S4, metal ion treatment, ammonium sulfate is generated after the separated acid is neutralized with ammonia, and the pH of the system is controlled to precipitate titanium hydroxide, which is recovered for titanium dioxide production;

[0051] Step S5, add concentrated hydrochloric acid to the salt in the separated waste acid, and perform complexation reaction with 1-ethyl-3-methyl imidazole, then extract with petroleum ether after heating and stirring, fully shake, stand still, separate the layers, then add a certain amount of 10% sodium hydroxide solution to the organic phase for back extraction, fully shake, stand still, separate the layers, and filter to obtain pure dilute sulfuric acid with low iron ion concentration.

[0052] The concentration process in step S1 is to filter the hydrolyzed metatitanic acid slurry to produce waste acid with a concentration of 30% and then perform vacuum concentration after filtration.

[0053] The temperature of the cooled solution in step S2 is 0-40℃, and the filtration is performed using a 0.1 μm uniform pore membrane filter.

[0054] The iron ion removal process in step S5 is replaced by the following steps:

[0055] Ammonia is added to the separated waste acid, the pH is controlled, and ferrous hydroxide precipitate is precipitated and removed by filtration; then an oxidizing agent is added in proportion to oxidize the remaining Fe 2+ to Fe 3+ , adjust the pH, precipitate the iron hydroxide precipitate, and remove it by filtration to obtain pure ammonium sulfate solution; after concentration of the ammonium sulfate solution, replace the traditional mirabilite solution in the production process of precipitated barium sulfate, and react with barium sulfide solution in proportion to produce barium sulfate precipitate and byproduct ammonium sulfide, which is washed, dried and crushed to produce precipitated barium sulfate product.

[0056] The sulfuric acid concentration of the pure dilute sulfuric acid in step S4 is 35%, and the ferrous ion concentration is ≤300 mg / L. Embodiment

[0057] The method for recycling and utilizing titanium white waste acid in sulfuric acid production of sulfur, comprising the following steps:

[0058] Step S1, concentration and purification treatment, the titanium white waste acid is concentrated to obtain an acid solution with a concentration of 38%;

[0059] Step S2, pretreatment of the acid solution, the acid solution is cooled and filtered to remove impurities after cooling;

[0060] Step S3, diffusion dialysis treatment, the filtered waste acid and water enter the diffusion dialysis device from the two sides of the anion homogeneous membrane, so that the acid and salt in the waste acid are preliminarily separated;

[0061] Step S4, metal ion treatment, ammonium sulfate is generated after neutralization of the separated acid by adding ammonia water, and the pH of the system is controlled to precipitate titanium orthophosphate precipitate, which is recovered for titanium dioxide production;

[0062] Step S5, add concentrated hydrochloric acid to the salt in the separated waste acid, and perform complexation reaction with 1-ethyl-3-methylimidazole, then extract with petroleum ether after heating and stirring, fully shake, stand still, separate the layers, then add a certain amount of 10% sodium hydroxide solution to the organic phase for back extraction, fully shake, stand still, separate the layers, and filter to obtain pure dilute sulfuric acid with low iron ion concentration.

[0063] The concentration process in step S1 is that the metatitanic acid slurry after hydrolysis is filtered to produce waste acid with a concentration of 25% which is filtered through a filter and then vacuum concentrated.

[0064] The temperature of the cooling process in step S2 is 0-40℃, and the filtration is performed using a 0.1 μm uniform pore membrane filter.

[0065] The iron ion removal process in step S5 is replaced by the following steps:

[0066] Ammonia water is added to the separated waste acid, the pH is controlled, ferrous hydroxide precipitate is precipitated, and the precipitate is removed by filtration; an oxidizing agent is then added in proportion, the remaining Fe 2+ is oxidized to Fe 3+ , the pH is adjusted, ferric hydroxide precipitate is precipitated, and the precipitate is removed by filtration to obtain a pure ammonium sulfate solution; the ammonium sulfate solution is concentrated and replaces the Glauber's salt solution in the traditional barium sulfate production process, and a double decomposition reaction occurs with the barium sulfide solution in proportion to produce barium sulfate precipitate and byproduct ammonium sulfide, which is washed, dried and crushed to produce the precipitated barium sulfate product.

[0067] The sulfuric acid concentration of the pure dilute sulfuric acid in step S4 is 34%, and the ferrous ion concentration is ≤300 mg / L.

[0068] The above pure dilute sulfuric acid is sent to the dry absorption process of sulfuric acid production to replace water for SO3 absorption and sulfuric acid dilution, and since the ferrous ions and other metal ions are removed, the problem of dry tower and absorption tower blockage caused by ferrous sulfate crystallization does not occur.

[0069] It is apparent to those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the present application should be defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the claims.

[0070] Furthermore, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the present specification is described in this way only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method for recovering and utilizing waste titanium dioxide acid in sulfuric acid production, characterized in that, Includes the following steps: Step S1: Concentration and purification treatment. The waste acid from titanium dioxide is concentrated to obtain an acid solution with a concentration of 35%-40%. Step S2, acid pretreatment, involves cooling the acid solution and then filtering it to remove impurities after cooling; Step S3, diffusion dialysis treatment: the filtered waste acid and water enter the diffusion dialysis unit from both sides of the anion homogeneous membrane, so that the acid and salt in the waste acid are initially separated. Step S4, metal ion treatment: after separation, the acid is neutralized by adding ammonia water to generate ammonium sulfate, and the pH of the system is controlled to precipitate orthotitanic acid, which is then recovered for use in titanium dioxide production. Step S5: Add concentrated hydrochloric acid to the salt in the separated waste acid and perform a complexation reaction with 1-ethyl-3-methylimidazolium chloride. After heating and stirring, extract with petroleum ether, shake thoroughly, let stand, separate into layers, and then add a certain amount of 10% sodium hydroxide solution to back-extract the organic phase. Shake thoroughly, let stand, separate into layers, and filter to obtain pure dilute sulfuric acid with low iron ion concentration.

2. The method for recovering and utilizing titanium dioxide waste acid in sulfuric acid production according to claim 1, characterized in that, The concentration process in step S1 is as follows: the waste acid with a concentration of 20%-30% generated by filtering the hydrolyzed metatitanic acid slurry is filtered and then vacuum concentrated.

3. The method for recovering and utilizing titanium dioxide waste acid in sulfuric acid production according to claim 2, characterized in that, The waste acid concentration generated by filtering the hydrolyzed metatitanic acid slurry is 25%.

4. The method for recovering and utilizing titanium dioxide waste acid in sulfuric acid production according to claim 1, characterized in that, The concentration of the acid solution in step S1 is 38%.

5. The method for recovering and utilizing titanium dioxide waste acid in sulfuric acid production according to claim 1, characterized in that, In step S2, the temperature after cooling is 0-40℃, and a 0.1μm uniform pore membrane filter is used for filtration.

6. The method for recovering and utilizing titanium dioxide waste acid in sulfuric acid production according to claim 1, characterized in that, The iron ion removal process in step S5 is replaced by the following steps: Ammonia water is added to the salt in the separated waste acid to control the pH, precipitating ferrous hydroxide. The precipitate is then removed by filtration. An oxidant is then added in a specific ratio to remove the remaining Fe. 2+ Oxidized to Fe 3+ Adjust the pH to precipitate ferric hydroxide, filter to remove the precipitate, and obtain a pure ammonium sulfate solution. After concentrating the ammonium sulfate solution, it replaces the sodium sulfate solution in the traditional barium sulfate precipitate production process and reacts with the barium sulfide solution in a certain proportion to produce barium sulfate precipitate and the byproduct ammonium sulfide. After washing, drying and pulverizing, the precipitated barium sulfate product is obtained.

7. The method for recovering and utilizing titanium dioxide waste acid in sulfuric acid production according to claim 1, characterized in that, The pure dilute sulfuric acid in step S5 has a sulfuric acid concentration of 33% to 35% and a ferrous ion concentration of ≤300 mg / L.