Method for recycling titanium-based arsenic removal agent

Abstract

The application discloses a method for recycling titanium-based arsenic removal agent, which comprises the following steps: (1) mixing a titanium-rich material with a sulfuric acid solution, and performing a roasting reaction to obtain roasting material A, which is used as the titanium-based arsenic removal agent for the first time; adding the titanium-based arsenic removal agent into an arsenic-containing liquid, and performing solid-liquid separation to obtain arsenic removal residue and arsenic removal liquid; (2) mixing the arsenic removal residue with the sulfuric acid solution and sulfur, and performing a reduction roasting reaction to obtain roasting material B; the gas released in the reaction is condensed to obtain a mixture of sulfuric acid and arsenous acid; (3) cooling the mixture of sulfuric acid and arsenous acid to below 10 DEG C, and performing centrifugal separation to obtain arsenic trioxide solid and a sulfuric acid solution; (4) mixing the arsenic removal liquid with a macroporous composite exchange resin, and performing a titanium removal reaction to obtain titanium-loaded resin and purified liquid; and (5) mixing the titanium-loaded resin with the arsenic-containing liquid, and separating resin particles from slurry containing titanium arsenate precipitate by using a solid-liquid separation device to obtain regenerated resin and titanium arsenate dilute slurry.

Description

Technical Field

[0001] This invention relates to the field of solution purification and impurity removal technology, specifically to a method for regenerating and recycling a titanium-based arsenic removal agent. Background Technology

[0002] Copper is a crucial material supporting the safe operation of my country's modern industrial system. Arsenic, a common by-product of copper ore, enters the copper refining electrolyte by up to 10% during the smelting process, forming a high-acid, high-arsenic solution. Arsenic not only significantly degrades the processing performance of cathode copper, leading to cracking during subsequent rolling and stretching, but also severely reduces its electrical and thermal conductivity, greatly limiting the application performance of copper materials in critical fields such as wires and cables, and heat dissipation components. Therefore, arsenic removal from the copper electrolyte is an indispensable step in the copper refining process.

[0003] To address the prominent problems of high energy consumption, low direct copper recovery rate, and release of highly toxic arsine in existing electrowinning methods, CN106086935B proposes converting titanium or zirconium compounds into water-insoluble and active titanates or zirconates through thermal alkaline activation as active impurity removers for arsenic removal from copper electrolytes. However, the regeneration process requires the use of caustic alkali, resulting in the presence of sodium or potassium titanate in the regenerated active impurity remover, which must be removed by acid washing to remove sodium or potassium ions. CN109022784B proposes converting a titanium-antimony mixture into an active impurity remover to co-precipitate and remove impurities such as arsenic, antimony, and bismuth from copper electrolytes. However, this step still involves alkaline arsenic removal, and acid washing is still required to remove sodium ions from the impurity remover to avoid sodium ions entering the copper electrolyte system. CN111304447B proposes pyrolyzing titanium arsenate at a high temperature of 850~1200℃ to achieve the separation of titanium and arsenic. However, the high-temperature process transforms titanium into stable rutile titanium dioxide, thus losing its arsenic removal activity. CN115786736A proposes adding titanium-containing or zirconium-containing compounds to the copper electrolyte to obtain a purified solution and arsenic-precipitated slag. However, the arsenic-precipitated slag still needs to be leached in an alkaline solution to remove arsenic, which poses a risk of introducing sodium ions into the copper electrolyte system. CN115874066A proposes adding titanium-containing or zirconium-containing compounds to the copper electrolyte to obtain a purified solution and arsenic-precipitated slag. The arsenic-precipitated slag is then subjected to high-temperature pyrolysis-carbon reduction at 600~1200℃ to obtain zirconium dioxide or titanium dioxide, with arsenic recovered as high-purity metallic arsenic. The zirconium dioxide and titanium dioxide obtained by this high-temperature process have stable structures, but their arsenic removal ability will be severely reduced.

[0004] In summary, the alkaline hydrolysis method for converting titanium arsenate to sodium arsenate inevitably introduces sodium ions into the alkaline hydrolysis residue, making it unsuitable for direct return to the copper electrolyte for arsenic removal. Furthermore, the acid washing process generates high-salt wastewater containing arsenic, increasing the burden on environmental remediation. High-temperature pyrolysis or reduction processes convert titanium into titanium dioxide, or even stable rutile titanium dioxide, which completely eliminates its arsenic removal activity. Therefore, the regeneration and recycling of titanium arsenate is a key bottleneck determining the industrial application of titanium-based arsenic removal agents. Summary of the Invention

[0005] The purpose of this invention is to provide a method for regenerating and recycling titanium-based arsenic removal agents. The method utilizes the reducing roasting of a sulfuric acid system to decompose titanium arsenate, causing arsenic to volatilize as arsenic trioxide, and converting titanium into a titanium-based arsenic removal agent soluble in acid, thereby achieving the purpose of regenerating and recycling the arsenic removal agent.

[0006] To achieve the above objectives, this invention proposes a method for regenerating and recycling a titanium-based arsenic removal agent, comprising the following steps: (1) Mix the titanium-rich material with sulfuric acid solution and calcine it at 200-300°C. The resulting calcined material A is used as the titanium-based arsenic removal agent for the first time. The titanium-based arsenic removal agent used in subsequent recycling uses the calcined material B prepared in step (2). Add the titanium-based arsenic removal agent to the arsenic-containing acid solution and / or the titanium arsenate slurry returned from step (5) to make the molar ratio of titanium to arsenic in the reaction system 0.5-1.5. Carry out the arsenic removal reaction at a certain temperature. After solid-liquid separation, arsenic-removed slag and arsenic-removed liquid are obtained.

[0007] (2) The arsenic-removed slag obtained in step (1) is mixed with sulfuric acid solution and sulfur in a certain proportion, and a reduction roasting reaction is carried out in the range of 250~500℃ to reduce and decompose titanium arsenate to obtain roasting material B. The gas released by the reaction is condensed to obtain a mixture of sulfuric acid and arsenous acid. Furthermore, titanium-rich material can also be added in step (2).

[0008] (3) Cool the mixture of sulfuric acid and arsenic trioxide obtained in step (2) to below 10°C, and then separate it by centrifugation to obtain solid arsenic trioxide and sulfuric acid solution. The sulfuric acid solution contains a small amount of arsenic trioxide. In order to achieve material closed loop and avoid the generation of arsenic-containing waste liquid, it is returned to step (2) for recycling.

[0009] (4) The arsenic-removed liquid obtained in step (1) is mixed with macroporous composite exchange resin and titanium removal reaction is carried out at room temperature to adsorb and remove the residual titanium in the arsenic-removed liquid, and titanium-supported resin and purified liquid are obtained.

[0010] (5) The titanium-loaded resin obtained in step (4) is mixed with arsenic-containing liquid and regenerated at room temperature to form titanium arsenate precipitate on the resin and detach it from the resin. The resin particles are separated from the slurry containing titanium arsenate precipitate by a solid-liquid separation device to obtain regenerated resin and titanium arsenate slurry.

[0011] Preferably, in step (1), the titanium dioxide content in the titanium-rich material is greater than 75%, and the concentration of the sulfuric acid solution is 50%~98%.

[0012] Preferably, in step (1), the molar ratio of sulfuric acid to titanium is 2 to 4, and the calcination reaction time is 30 to 90 minutes.

[0013] Preferably, in step (1), the arsenic concentration in the arsenic-containing acid solution is greater than 7 g / L, and the arsenic is in the pentavalent state, including but not limited to copper electrolyte, copper removal solution, and waste acid generated during heavy metal smelting.

[0014] Preferably, the temperature of the arsenic removal reaction in step (1) is 60~100℃ and the time is 30~120 minutes.

[0015] Preferably, in the mixture of step (2), the molar ratio of sulfuric acid to titanium is 2 to 4, and the molar ratio of sulfur to arsenic is 1 to 2.

[0016] Preferably, the reduction calcination reaction time in step (2) is 30 to 120 minutes.

[0017] Preferably, the macroporous composite exchange resin in step (4) includes a macroporous cation exchange resin and a macroporous anion exchange resin, with a weight ratio of 3 to 5 between the macroporous cation exchange resin and the macroporous anion exchange resin. The functional groups of the macroporous cation exchange resin include one or more of sulfonic acid groups, iminodiacetic acid groups, and aminophosphonic acid groups, and the functional groups of the macroporous anion exchange resin include one or more of quaternary ammonium groups, tertiary amine groups, and primary amine groups.

[0018] Preferably, the time for the detitanium removal reaction in step (4) is 1 to 5 hours.

[0019] Preferably, the regeneration reaction time in step (5) is 1 to 5 hours.

[0020] The technical principles employed in this invention are as follows: This invention transforms the titanium dioxide in the titanium-rich material into a titanium-based arsenic remover with arsenic removal activity during the calcination process.

[0021] When titanium-based arsenic removal agents are added to arsenic-containing acid solutions containing pentavalent arsenic, they react with arsenate ions to form titanium arsenate precipitate, thereby removing the arsenic.

[0022] During the reduction roasting reaction of arsenic-removed slag with sulfuric acid and sulfur, sulfur dioxide generated in situ by sulfuric acid and sulfur can reduce pentavalent arsenic to trivalent arsenic, thereby decomposing titanium arsenate and causing arsenic trioxide to volatilize into the gas phase, thus achieving arsenic-titanium separation.

[0023] The volatilized arsenic trioxide, along with sulfur trioxide and excess sulfuric acid, is absorbed by water, forming a mixture of sulfuric acid and arsenous acid. Under high acid and low temperature conditions, arsenous acid precipitates out to form arsenic trioxide.

[0024] When the molar ratio of titanium to arsenic in the arsenic removal reaction system of step (1) is high, a small amount of titanium will remain in the resulting arsenic-removed solution. In complex solutions, titanium can exist as a cation or undergo coordination reactions with other anions, existing as a complex anion. Therefore, a composite exchange resin combining cation and anion exchange resins is used to adsorb and remove the residual titanium, yielding a purified solution and a titanium-supported resin. The titanium-supported resin is mixed with an arsenic-containing acid solution, causing the titanium on the resin to react with arsenic to form titanium arsenate precipitate, which then detaches from the resin, thereby regenerating the composite exchange resin.

[0025] The beneficial effects achievable by this invention are as follows: The sulfuric acid-based reduction roasting process effectively solves three major problems in the regeneration of existing titanium-based arsenic removal agents: sodium ion introduction, high-temperature deactivation, and heavy environmental burden, significantly improving recycling efficiency and industrial feasibility. Compared to traditional alkaline regeneration technology, this method does not use caustic alkali throughout the process, eliminating the entry of sodium ions into the system at the source. This simplifies the process, avoids the generation of high-salt wastewater containing arsenic, and significantly reduces environmental treatment costs. Compared to high-temperature pyrolysis or reduction technologies requiring 850~1200℃, this invention controls the reduction roasting temperature at 250~500℃. This mild condition effectively prevents titanium from transforming into stable and inactive rutile titanium dioxide, thus ensuring that the regenerated titanium-based arsenic removal agent (roasting material B) has sustained high activity and can be recycled for a long time. During the regeneration process, arsenic volatilizes and is recovered in the form of arsenic trioxide, and the condensed sulfuric acid can be recycled, realizing the resource utilization of arsenic and internal reuse of the reagent. Meanwhile, the deep removal and regeneration of residual titanium through composite exchange resin further constitutes a dual cycle of titanium and resin, improving the overall material utilization rate. The entire process forms a closed loop of "arsenic removal - regeneration - resource recovery," with mild operating conditions, low energy consumption, and controllable costs. It can not only efficiently purify arsenic-containing acid solutions such as copper electrolytes, but also provide the industry with a green, economical, and sustainable arsenic removal technology path. Detailed Implementation

[0026] The present invention will be further illustrated by the following examples, but is not limited thereto.

[0027] Example 1 500g of titanium-rich material containing 93% titanium dioxide was mixed with a 98% sulfuric acid solution, with a sulfuric acid to titanium molar ratio of 2. The mixture was calcined at 200℃ for 90 minutes to obtain calcined material A, which was used as the initial titanium-based arsenic removal agent. Two liters of copper electrolyte containing 11.7g / L of arsenic were divided into five equal portions. Calcined material A was added to each portion according to different titanium-arsenic molar ratios, and arsenic removal reactions were carried out under different conditions. The experimental results are shown in Table 1.

[0028] Table 1. Experimental results of arsenic removal reactions under different conditions. The arsenic-removed solutions obtained from the above five experiments were combined, mixed thoroughly, and then divided into five equal portions. Each portion was passed through an exchange column containing a different type of ion exchange resin to carry out a titanium removal reaction for one hour. The experimental results are shown in Table 2.

[0029] Table 2. Experimental results of titanium removal reaction under different conditions Example 2 120 grams of titanium-rich material containing 89% titanium dioxide was mixed with a 53% sulfuric acid solution, with a molar ratio of sulfuric acid to titanium of 3. The mixture was calcined at 250°C for 60 minutes to obtain calcined material A, which was used as the initial titanium-based arsenic removal agent. The calcined material A was then added to 3 liters of copper-removed liquid containing 22.3 g / L of arsenic. At this point, the molar ratio of titanium to arsenic in the reaction system was approximately 1.5. The reaction was carried out at 85°C for 120 minutes. After solid-liquid separation, arsenic-removed slag and arsenic-removed liquid were obtained. This step achieved an arsenic removal rate of 96.2% and a titanium loss rate of 3.9%.

[0030] The arsenic-removed slag was divided into four equal parts, and 96% sulfuric acid solution and sulfur were added to each part in a certain proportion. After mixing, the mixture was subjected to reduction roasting reaction under different conditions to obtain roasted material B. The arsenic volatilization rate was calculated based on the arsenic residue in roasted material B. The experimental results are shown in Table 3.

[0031] Table 3. Experimental results of reduction calcination reaction under different conditions Three liters of arsenic-removed liquid were passed through an exchange column composed of macroporous composite exchange resin. The resin in the exchange column consisted of 200 grams of macroporous quaternary ammonium anion exchange resin, 600 grams of macroporous sulfonic acid cation exchange resin, and 400 grams of macroporous imine diacetic acid cation exchange resin. The titanium removal reaction time was 5 hours, yielding a titanium-loaded resin. The titanium removal rate in this step was 97.9%.

[0032] The above-mentioned titanium-supported resin was divided into three equal parts and loaded into a resin column. A copper-degraded solution containing 22.3 g / L of arsenic was then introduced into each column at a flow rate of 1 L / h, and the reaction was terminated at different time points. The experimental results are shown in Table 4.

[0033] Table 4. Eluting rate of titanium at different regeneration reaction times Example 3 120 grams of titanium-rich material containing 91% titanium dioxide was mixed with a 79% sulfuric acid solution, with a sulfuric acid to titanium molar ratio of 4. The mixture was calcined at 300°C for 30 minutes to obtain calcined material A, which was used as the initial titanium-based arsenic removal agent. The calcined material A was then added to 4 liters of copper-removed liquid containing 22.3 g / L of arsenic. At this point, the molar ratio of titanium to arsenic in the reaction system was approximately 1.15. The reaction was carried out at 95°C for 120 minutes. After solid-liquid separation, arsenic-removed slag and arsenic-removed liquid were obtained. This step achieved an arsenic removal rate of 97.6% and a titanium dissolution rate of 2.8%.

[0034] With a sulfuric acid to titanium molar ratio of 3 and a sulfur to arsenic molar ratio of 1.5, the above-mentioned arsenic-removed slag was mixed with a 93% sulfuric acid solution and sulfur, and then subjected to a reduction roasting reaction at a temperature of 480℃ for 120 minutes. The gas released from the reduction roasting reaction was condensed to obtain a mixture of sulfuric acid and arsenous acid, which was further cooled to 5-8℃, then centrifuged and washed with a small amount of water to obtain solid arsenic trioxide and a sulfuric acid solution. The sulfuric acid concentration in the obtained sulfuric acid solution was 72%, and the residual arsenic trioxide concentration was 0.17%. This sulfuric acid solution can be recycled back to the reduction roasting reaction.

[0035] After reduction roasting, roasted material B was obtained. Based on the arsenic residue in roasted material B, the arsenic volatilization rate was calculated to be 97.8%. Three liters of copper-removed liquid containing 22.3 g / L of arsenic were taken and divided into three equal portions. Roasted material B was added to the copper-removed liquid according to different molar ratios of titanium to arsenic, and each portion was subjected to an arsenic removal reaction at 95°C for 100 minutes. After solid-liquid separation, arsenic-removed slag and arsenic-removed liquid were obtained. The experimental results of the arsenic removal reaction are shown in Table 5.

[0036] Table 5. Experimental results of arsenic removal reaction under different conditions The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for regenerating and recycling a titanium-based arsenic removal agent, characterized in that, Includes the following steps: (1) Mix the titanium-rich material with sulfuric acid solution and calcine it in the range of 200~300℃. The calcined material A is used as the titanium-based arsenic removal agent for the first time. The titanium-based arsenic removal agent used in subsequent recycling is the calcined material B prepared in step (2). Add the titanium-based arsenic removal agent to the arsenic-containing acid liquid and / or the titanium arsenate slurry returned in step (5) so that the molar ratio of titanium to arsenic in the reaction system is 0.5~1.

5. Carry out the arsenic removal reaction at a certain temperature. After solid-liquid separation, arsenic removal slag and arsenic removal liquid are obtained. The arsenic concentration in the arsenic-containing acid liquid is greater than 7g / L and the valence state of arsenic is pentavalent. It includes one or more of the copper electrolyte, copper removal liquid and waste acid generated in the heavy metal smelting process. (2) The arsenic-removing slag obtained in step (1) is mixed with sulfuric acid solution and sulfur in proportion, and a reduction roasting reaction is carried out in the range of 250~500℃ to reduce and decompose titanium arsenate to obtain roasting material B. The gas released by the reaction is condensed to obtain a mixture of sulfuric acid and arsenous acid. When the arsenic-removing slag is mixed with sulfuric acid solution and sulfur in proportion, the molar ratio of sulfuric acid to titanium is 2~4, and the molar ratio of sulfur to arsenic is 1~2. (3) Cool the mixture of sulfuric acid and arsenic trioxide obtained in step (2) to below 10°C, and separate it by centrifugation to obtain solid arsenic trioxide and sulfuric acid solution. The sulfuric acid solution is returned to step (2) for recycling. (4) The arsenic-removed liquid obtained in step (1) is mixed with macroporous composite exchange resin and titanium removal reaction is carried out at room temperature to adsorb and remove the residual titanium in the arsenic-removed liquid, and titanium-supported resin and purified liquid are obtained. (5) The titanium-loaded resin obtained in step (4) is mixed with arsenic-containing liquid and regenerated at room temperature to form titanium arsenate precipitate on the resin and detach it from the resin. The resin particles are separated from the slurry containing titanium arsenate precipitate by a solid-liquid separation device to obtain regenerated resin and titanium arsenate slurry.

2. The method as described in claim 1, characterized in that, In step (1), the titanium dioxide content in the titanium-rich material is greater than 75%, and the concentration of the sulfuric acid solution is 50%~98%.

3. The method as described in claim 1, characterized in that, In step (1), the molar ratio of sulfuric acid to titanium is 2 to 4, and the calcination reaction time is 30 to 90 minutes.

4. The method as described in claim 1, characterized in that, The temperature of the arsenic removal reaction in step (1) is 60~100℃ and the time is 30~120 minutes.

5. The method as described in claim 1, characterized in that, The reduction calcination reaction time in step (2) is 30 to 120 minutes.

6. The method as described in claim 1, characterized in that, The macroporous composite exchange resin in step (4) includes macroporous cation exchange resin and macroporous anion exchange resin. The weight ratio of macroporous cation exchange resin to macroporous anion exchange resin is 3 to 5. The functional groups of the macroporous cation exchange resin include one or more of sulfonic acid group, iminodiacetic acid group and aminophosphonic acid group. The functional groups of the macroporous anion exchange resin include one or more of quaternary ammonium group, tertiary amine group and primary amine group.

7. The method as described in claim 1, characterized in that, The time for the detitanium removal reaction in step (4) is 1 to 5 hours.

8. The method as described in claim 1, characterized in that, The regeneration reaction in step (5) takes 1 to 5 hours.

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