Process for recovering thallium from high-fluorine and chlorine soot

Abstract

This application provides a process for recovering thallium from high-fluoride-chlorine flue dust, comprising the following steps: S1, mixing high-fluoride-chlorine flue dust with a calcium agent and granulating to obtain high-fluoride-chlorine flue dust particles; S2, feeding the high-fluoride-chlorine flue dust particles into a rotary kiln for roasting, and collecting the flue gas generated during roasting through a dust collection system to obtain high-thallium flue dust; S3, crushing and screening the high-thallium flue dust through a crushing and screening machine to obtain undersize material that meets the particle size requirements, adding the undersize material to an alkaline leaching tank containing sodium hydroxide solution for reaction and filtration to obtain thallium-containing alkaline leaching solution and alkaline leaching residue; The beneficial effects of this invention are that it can efficiently separate thallium from fluorine, chlorine and other impurity elements in high-fluoride-chlorine flue dust, reduce the difficulty of thallium recovery, not only stably obtain high-purity thallium ingots and ensure a high direct recovery rate of thallium, but also achieve comprehensive recovery of valuable metals such as zinc, and reduce the pollution of waste residue and wastewater to the environment.

Description

Technical Field

[0001] This application belongs to the field of resource comprehensive utilization technology, specifically relating to a process method for recovering thallium from high-fluoride chlorine flue dust. Background Technology

[0002] Thallium enters the system from the raw materials in the hydrometallurgical zinc smelting process, which mainly include primary zinc ore and secondary zinc resources. Most lead and zinc production globally is achieved through smelting sulfide lead-zinc ores. Thallium, as a typical rare element, rarely forms independent thallium deposits. It typically enters as a trace element in minerals such as galena, sphalerite, and chalcopyrite, and is prevalent in sulfide deposits, entering the environment along with the mining of the main minerals.

[0003] The main problems with thallium in non-ferrous smelting currently lie in the leaching and electrolysis systems. Excessive thallium content and its continuous accumulation can affect subsequent electrolysis processes. If not addressed promptly, it will reduce product quality and adversely impact technical and economic indicators. Thallium-containing concentrates, after roasting, leaching, and purification, mainly end up in the purification slag. In subsequent volatilization roasting, it primarily accumulates in the high-fluorine and chlorine-containing flue dust of multi-hearth furnaces. With increasingly stringent requirements for the transfer of thallium-containing materials, the environmental risks associated with transferring them via flue dust are growing.

[0004] In the existing technology, patent CN101818254A uses NaOH and Na2CO3 to perform two-stage alkaline washing on zinc oxide flue dust. After the alkaline washing solution is mixed, sodium sulfide is used to precipitate thallium. This cannot achieve the separation of thallium from fluorine and chlorine. Under certain conditions, thallium will form precipitates with fluorine and chlorine and be lost, resulting in a low thallium recovery rate.

[0005] Patent CN115449638A uses zinc oxide flue dust mixed with water to form a slurry. At a certain temperature, an oxidant, sodium hydroxide, or sodium carbonate is added to the slurry and stirred until homogeneous. The mixture is then filtered to obtain conversion residue and conversion liquid. Because the thallium content in zinc oxide flue dust is very low, generally below 0.5%, direct wet leaching would produce a large amount of leaching residue. This residue has a complex composition, is difficult to process, and is costly. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0007] To address the aforementioned problems, this application provides a process for recovering thallium from high-fluorine-chlorine flue dust, comprising the following steps: S1. Mix high-fluoride chlorine-containing fly ash with calcium agent and granulate to obtain high-fluoride chlorine-containing fly ash particles; S2. The high-fluorine-chlorine flue dust particles are fed into a rotary kiln for calcination. The flue gas generated during calcination is collected by a dust collection system to obtain high-thallium flue dust. S3. The high-thallium flue dust is crushed and screened by a crusher to obtain undersize material that meets the particle size requirements. The undersize material is added to an alkaline leaching tank containing sodium hydroxide solution for reaction and filtration to obtain thallium-containing alkaline leaching solution and alkaline leaching residue. S4. Add the thallium-containing alkali leaching solution to the sulfidation tank, then add sodium sulfide to the sulfidation tank to carry out the sulfidation precipitation reaction. After the reaction, filter to obtain thallium sulfide enriched slag and sulfidation liquid. S5. Add the thallium sulfide enriched residue to an acid leaching tank containing sulfuric acid solution for acid leaching. After the reaction, filter to obtain thallium-containing leachate and leaching residue. S6. The thallium-containing leachate is added to a zinc plate displacement tank to carry out a displacement reaction, thereby obtaining sponge thallium; S7. The sponge thallium is refined and melted to obtain thallium ingots.

[0008] Optionally, the high-fluoride chlorine-containing fly ash is mixed with a calcium agent and granulated with water to obtain high-fluoride chlorine-containing fly ash particles, including: The high-fluoride chlorine-containing flue dust and the calcium agent are fed into the disc of the granulator. The amount of calcium agent added is 11%-19% of the mass of the high-fluoride chlorine-containing flue dust. After uniformly spraying water onto the disc, granulation is carried out. After the particle size reaches the preset particle size, the high-fluoride chlorine-containing flue dust particles are obtained.

[0009] Optionally, the calcium agent is at least one of calcium oxide, quicklime, or calcium carbonate.

[0010] Optionally, the high-fluorine-chlorine flue dust particles are fed into a rotary kiln for calcination, and the flue gas generated during calcination is collected by a dust collection system to obtain high-thallium flue dust, comprising: The high-fluorine-chlorine ash particles are fed into a rotary kiln via a screw conveyor. The rotary kiln is calcined at a temperature of 500℃-800℃. The residence time of the high-fluorine-chlorine ash particles in the rotary kiln is 1-4 hours. While the high-fluorine-chlorine ash particles are being calcined, the dust collection system collects the flue gas generated during calcination.

[0011] Optionally, the dust collection system includes a cartridge dust collector and an induced draft fan. The cartridge dust collector is connected to the rotary kiln via a pipeline, and the induced draft fan is installed on the pipeline.

[0012] Optionally, the high-thallium flue dust is crushed and screened using a crusher to obtain undersize material that meets the particle size requirements. The undersize material is then added to an alkaline leaching tank containing sodium hydroxide solution for reaction and filtration to obtain thallium-containing alkaline leaching solution and alkaline leaching residue, comprising: The high-thallium flue dust obtained from the dust collection system is crushed and screened by a crusher and screener. The undersize material that meets the particle size requirements is added to an alkaline leaching tank. Sodium hydroxide solution is first added to the alkaline leaching tank to control the pH of the solution to 8-11. Then the undersize material is added to react. The liquid-solid ratio of the reaction is 10:1-20:1, the reaction temperature is 60℃-80℃, and the reaction time is 1-3 hours. After the reaction is completed, the mixture is cooled to room temperature and filtered to obtain thallium-containing alkaline leaching solution and alkaline leaching residue.

[0013] Optionally, the thallium-containing alkaline leaching solution is added to the sulfidation tank, followed by the addition of sodium sulfide to carry out a sulfidation precipitation reaction. After the reaction, the mixture is filtered to obtain thallium sulfide-enriched slag and a post-sulfidation liquid, comprising: The thallium-containing alkali leaching solution is added to a sulfidation tank, and then sodium sulfide is added to the sulfidation tank to carry out the reaction. The amount of sodium sulfide added is 3-5 times the theoretical amount of the reaction. The reaction temperature is 30℃-50℃ and the reaction time is 20-40 minutes. After the reaction is completed, the solution is filtered to obtain the sulfidated liquid and the thallium sulfide enriched residue.

[0014] Optionally, the thallium sulfide enriched residue is added to an acid leaching tank containing sulfuric acid solution for acid leaching. After the reaction, the residue is filtered to obtain a thallium-containing leachate and leaching residue, comprising: The thallium sulfide enrichment residue is added to an acid leaching tank for acid leaching at a temperature of 60℃-80℃ for 3-5 hours. The concentration of sulfuric acid used in the acid leaching is 100g / L-140g / L. After acid leaching, the residue is filtered to obtain a thallium-containing leachate and leaching residue.

[0015] Optionally, the thallium-containing leachate is added to a zinc plate displacement tank to carry out a displacement reaction to obtain sponge thallium, comprising: The thallium-containing leachate was added to the zinc plate displacement tank for a displacement reaction at a temperature of 70℃-90℃, with an endpoint pH of 5-7 and a reaction time of 14-18 hours. Sponge thallium was obtained after the reaction.

[0016] Optionally, the sponge thallium is refined and melted to obtain thallium ingots, including: The sponge thallium is placed into a casting furnace for refining and casting to obtain thallium ingots.

[0017] Beneficial effects The process for recovering thallium from high-fluoride and chlorine-containing flue dust provided in the embodiments of the present invention can efficiently separate thallium from fluorine, chlorine and other impurity elements in high-fluoride and chlorine-containing flue dust, reduce the difficulty of thallium recovery, not only stably obtain high-purity thallium ingots and ensure a high direct recovery rate of thallium, but also realize the comprehensive recovery of valuable metals such as zinc, and reduce the pollution of waste residue and wastewater to the environment. Attached Figure Description

[0018] Figure 1 This is a flowchart of the present invention; Figure 2 This is a diagram showing the connection structure of the device according to the present invention.

[0019] The reference numerals in the attached figures are as follows: 1. Granulator; 2. Screw conveyor; 3. Rotary kiln; 4. Cartridge dust collector; 5. Crusher and screener; 6. Alkali leaching tank; 7. Sulfide leaching tank; 8. Acid leaching tank; 9. Zinc plate replacement tank; 10. Casting furnace. Detailed Implementation

[0020] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0024] See also Figure 1-2 As shown, according to an embodiment of this application, a process for recovering thallium from high-fluorine-chlorine flue dust is provided, comprising the following steps: S1. Mix high-fluoride chlorine-containing fly ash with calcium agent and granulate to obtain high-fluoride chlorine-containing fly ash particles; S2. The high-fluorine-chlorine flue dust particles are fed into rotary kiln 3 for roasting. The flue gas generated during roasting is collected by a dust collection system to obtain high-thallium flue dust. S3. The high-thallium flue ash is crushed and screened by the crusher 5 to obtain undersize material with the required particle size. The undersize material is added to the alkaline leaching tank 6 containing sodium hydroxide solution for reaction and filtration to obtain thallium-containing alkaline leaching solution and alkaline leaching residue. S4. Add the thallium-containing alkali leaching solution to the sulfidation tank 7, and then add sodium sulfide to the sulfidation tank 7 to carry out the sulfidation precipitation reaction. After the reaction, filter to obtain thallium sulfide enriched slag and sulfidation liquid. S5. Add the thallium sulfide enriched residue to the acid leaching tank 8 containing sulfuric acid solution for acid leaching. After the reaction, filter to obtain thallium-containing leachate and leaching residue. S6. The thallium-containing leachate is added to the zinc plate displacement tank 9 to carry out a displacement reaction to obtain sponge thallium; S7. The sponge thallium is refined and melted to obtain thallium ingots.

[0025] In this technical solution, high-fluoride-chlorine flue dust is first mixed with calcium agent and granulated to obtain high-fluoride-chlorine flue dust particles. These particles are then fed into a rotary kiln 3 for calcination. The flue gas generated during calcination is collected by a dust collection system to obtain high-thallium flue dust. Subsequently, the high-thallium flue dust is crushed and screened by a crusher and screener 5 to obtain undersize material that meets the particle size requirements. The undersize material is added to an alkaline leaching tank 6 containing sodium hydroxide solution for reaction and filtration to obtain a thallium-containing alkaline leaching solution. The process involves adding thallium-containing alkaline leaching solution and sodium sulfide to a sulfidation tank 7 for a sulfidation precipitation reaction. After the reaction, the solution is filtered to obtain thallium sulfide-enriched slag and sulfidation liquid. The thallium sulfide-enriched slag is then added to an acid leaching tank 8 containing sulfuric acid solution for acid leaching. After the reaction, the solution is filtered to obtain thallium-containing leachate and leaching residue. The thallium-containing leachate is then added to a zinc plate displacement tank 9 for a displacement reaction to obtain sponge thallium. Finally, the sponge thallium is refined and smelted to obtain thallium ingots. This process can efficiently separate thallium from fluorine, chlorine, and other impurity elements in high-fluorine and chlorine flue dust, reducing the difficulty of thallium recovery. It can not only stably obtain high-purity thallium ingots and ensure a high direct recovery rate of thallium, but also achieve comprehensive recovery of valuable metals such as zinc, reducing the pollution of waste residue and wastewater to the environment.

[0026] In one feasible embodiment, high-fluoride chlorine-containing fly ash is mixed with a calcium agent and granulated with water to obtain high-fluoride chlorine-containing fly ash particles, comprising: The high-fluorine-chlorine flue ash and the calcium agent are fed into the disc of the granulator 1. The amount of calcium agent added is 11%-19% of the mass of the high-fluorine-chlorine flue ash. After uniformly spraying water onto the disc, granulation is carried out. After the particle size reaches the preset particle size, the high-fluorine-chlorine flue ash particles are obtained.

[0027] The calcium agent is at least one of calcium oxide, quicklime, or calcium carbonate.

[0028] In this technical solution, the raw material, high-fluorine chlorine-containing fly ash, is transferred to a disc granulator 1. The disc granulator 1 is turned on, and the high-fluorine chlorine-containing fly ash is added manually or mechanically to the disc of the granulator 1, where a calcium agent is one or more of calcium oxide, quicklime, and calcium carbonate. The amount of calcium agent added is 13%-17% of the mass of the high-fluorine chlorine-containing fly ash. A small amount of water is sprayed evenly into the disc, and the granulator 1 is started to granulate. The mixture is continuously stirred until the particle size reaches the preset requirement of 5mm-10mm. The granulator 1 is then turned off, and the high-fluorine chlorine-containing fly ash particles obtained after granulation are collected. By mixing calcium agent with high-fluorine and chlorine flue dust for granulation, on the one hand, the fluorine and chlorine elements in the flue dust can be fixed, avoiding the volatilization of fluorine and chlorine during subsequent roasting, which would cause equipment corrosion and environmental pollution; on the other hand, the granulated particles have good air permeability and are not easy to clump, which can ensure that the material is heated evenly during subsequent roasting in rotary kiln 3, improve the volatilization efficiency of thallium, and improve the efficient enrichment of thallium.

[0029] In one feasible embodiment, the high-fluorine-chlorine flue dust particles are fed into a rotary kiln 3 for calcination, and the flue gas generated during calcination is collected by a dust collection system to obtain high-thallium flue dust, comprising: The high-fluorine-chlorine ash particles are fed into a rotary kiln 3 via a screw conveyor 2. The rotary kiln 3 is roasted at a temperature of 500℃-800℃. The residence time of the high-fluorine-chlorine ash particles in the rotary kiln 3 is 1-4 hours. While roasting the high-fluorine-chlorine ash particles, the dust collection system collects the flue gas generated during roasting.

[0030] In this technical solution, the screw conveyor 2 is started to feed the high-fluorine and chlorine-containing flue dust particles obtained in S1 into the electrically heated rotary kiln 3 at a feed rate of 5000g / h-6000g / h for calcination. The calcination temperature of the electrically heated rotary kiln 3 is controlled at 500℃-800℃. Starting from the time the material is discharged normally from the rotary kiln 3, the total residence time of the material in the rotary kiln 3 is controlled to be 1-4h to ensure that the thallium in the high-fluorine and chlorine-containing flue dust is fully volatilized, and at the same time, the separation of thallium from fluorine and chlorine is achieved. The thallium-containing flue gas generated during the calcination process is collected by a dust collection system. After dust collection treatment, high-thallium flue dust is obtained, achieving efficient enrichment of thallium. The thallium grade in the raw high-fluorine and chlorine-containing flue dust can be effectively increased from about 0.5% to about 25%, achieving efficient enrichment and separation of thallium.

[0031] Understandably, using an electrically heated rotary kiln 3 for calcination allows for controllable temperature and material residence time, ensuring full volatilization of thallium while achieving effective separation of thallium from fluorine and chlorine, thus reducing interference from fluorine and chlorine in subsequent thallium recovery.

[0032] Understandably, the slag after roasting can be used for zinc recovery, improving raw material utilization and avoiding resource waste.

[0033] Understandably, this also includes a tail gas absorption tower, which is installed after the dust collection system. The tail gas absorption tower contains 30% liquid alkali. After 12 hours of production, the pH value of the liquid alkali is measured using a pH test. If the pH is <10, caustic soda flakes or liquid alkali are added in time.

[0034] In one feasible embodiment, the dust collection system includes a cartridge dust collector 4 and an induced draft fan. The cartridge dust collector 4 is connected to the rotary kiln 3 via a pipeline, and the induced draft fan is installed on the pipeline.

[0035] In this technical solution, the dust collection system includes a cartridge dust collector 4 and an induced draft fan to achieve efficient enrichment of thallium.

[0036] In one feasible embodiment, the high-thallium flue dust is crushed and screened by a crusher and screener 5 to obtain undersize material that meets the particle size requirements. The undersize material is then added to an alkaline leaching tank 6 containing sodium hydroxide solution for reaction and filtration to obtain thallium-containing alkaline leaching solution and alkaline leaching residue, including: The high-thallium flue dust obtained from the dust collection system is crushed and screened by the crusher and screener 5. The undersize material that meets the particle size requirements is added to the alkaline leaching tank 6. Sodium hydroxide solution is first added to the alkaline leaching tank 6 to control the pH of the solution to 8-11. Then the undersize material is added to react. The liquid-solid ratio of the reaction is 10:1-20:1, the reaction temperature is 60℃-80℃, and the reaction time is 1-3 hours. After the reaction is completed, the mixture is cooled to room temperature and filtered to obtain thallium-containing alkaline leaching solution and alkaline leaching residue.

[0037] In this technical solution, high-thallium flue dust is fed into a crushing and screening machine 5 for crushing and screening to obtain undersize material that meets the particle size requirements. The undersize material is then added to an alkaline leaching tank 6. Before addition, the alkaline leaching tank 6 contains a sodium hydroxide solution with a pH of 8-11. The undersize material is then added to the alkaline leaching tank 6, with a liquid-to-solid ratio of 10:1-20:1, a reaction temperature of 60-80℃, and a reaction time of 1-3 hours. This allows the thallium in the high-thallium flue dust to fully react with the sodium hydroxide, entering the solution as TlOH. Meanwhile, the zinc-containing material in the high-thallium flue dust reacts with the sodium hydroxide to form zinc hydroxide precipitate, and other impurities react with the sodium hydroxide to form corresponding hydroxide precipitates. After the reaction is complete, the mixture is cooled to room temperature and filtered for solid-liquid separation, yielding a thallium-containing alkaline leaching solution and alkaline leaching residue. The alkaline leaching residue is washed with water, dried, and then sent to a volatilization kiln for further processing to recover the metals. Screening by crushing and screening machine 5 can remove large particulate impurities from high-thallium flue dust, increase the specific surface area of ​​the material, ensure sufficient subsequent alkaline leaching reaction, and improve the leaching rate of thallium. Alkaline leaching with sodium hydroxide solution can allow thallium to enter the solution efficiently in the form of TlOH, while zinc and other impurity elements are converted into hydroxide precipitates, realizing the effective separation of thallium from impurities such as zinc, and obtaining high-purity thallium-containing alkaline leaching solution.

[0038] It is understandable that the particle size of the material passing through the screen is less than 5mm.

[0039] In one feasible embodiment, the thallium-containing alkaline leaching solution is added to the sulfidation tank 7, and then sodium sulfide is added to the sulfidation tank 7 to carry out a sulfidation precipitation reaction. After the reaction, the mixture is filtered to obtain thallium sulfide enriched slag and sulfidation liquid, comprising: The thallium-containing alkali leaching solution is added to the sulfidation tank 7, and then sodium sulfide is added to the sulfidation tank 7 to carry out the reaction. The amount of sodium sulfide added is 3-5 times the theoretical amount of the reaction. The reaction temperature is 30℃-50℃ and the reaction time is 20-40 minutes. After the reaction is completed, the solution is filtered to obtain the sulfidated liquid and the thallium sulfide enriched residue.

[0040] In this technical solution, the thallium-containing alkali leaching solution is transferred to a sulfidation tank 7. Sodium sulfide is added to the sulfidation tank 7, with the amount of sodium sulfide added being 3-5 times the theoretical amount for the thallium sulfidation reaction, ensuring sufficient precipitation of thallium in the thallium-containing alkali leaching solution. The sulfidation reaction temperature is 30℃-50℃, and the reaction time is 20-40 minutes. Stirring ensures that the sodium sulfide reacts fully with the thallium-containing alkali leaching solution, generating water-insoluble thallium sulfide precipitate. This enriches the thallium in the sulfidation slag, separating it from excess alkali, sodium salts, and other impurities in the solution. After the reaction is complete, solid-liquid separation is performed by filtration, yielding thallium sulfide-enriched slag and post-sulfidation liquid. The post-sulfidation liquid is then sent to a wastewater treatment plant for further treatment. By using sodium sulfide to precipitate thallium, the thallium precipitate is poorly soluble in water, which can achieve efficient separation of thallium from impurities such as excess alkali and sodium salt in the solution. The high precipitation rate ensures that almost all thallium is enriched in the sulfidation slag, and the thallium content in the sulfidation liquid is extremely low. It can meet the discharge standards after simple treatment, reducing environmental pollution.

[0041] In one feasible embodiment, the thallium sulfide enriched residue is added to an acid leaching tank 8 containing sulfuric acid solution for acid leaching. After the reaction, the residue is filtered to obtain a thallium-containing leachate and a leaching residue, comprising: The thallium sulfide enrichment residue is added to acid leaching tank 8 for acid leaching. The acid leaching temperature is 60℃-80℃, the acid leaching time is 3-5 hours, and the sulfuric acid concentration is 100g / L-140g / L. After acid leaching, the residue is filtered to obtain thallium-containing leachate and leaching residue.

[0042] In this technical solution, thallium sulfide enriched slag is added to an acid leaching tank 8 pre-filled with sulfuric acid solution. The acid leaching temperature is 60℃-80℃, the acid leaching time is 3-5 hours, and the concentration of sulfuric acid is 100g / L-140g / L. This ensures that the thallium in the thallium sulfide enriched slag is fully dissolved into the solution, achieving separation of thallium from other insoluble impurities in the thallium sulfide slag. After the reaction is complete, solid-liquid separation is performed by filtration to obtain a thallium-containing leachate and leaching residue. The leaching residue is washed with water, dried, and then sent to a volatilization kiln for treatment to recover the metal. Through acidic leaching with sulfuric acid, the thallium in the thallium sulfide enriched slag can be fully dissolved into the solution, resulting in a high thallium leaching rate and achieving complete separation of thallium from insoluble impurities in the thallium sulfide slag. The high thallium concentration in the thallium-containing leachate further enhances the enrichment of thallium.

[0043] In one feasible embodiment, the thallium-containing leachate is added to the zinc plate displacement tank 9 to carry out a displacement reaction to obtain sponge thallium, comprising: The thallium-containing leachate was added to the zinc plate displacement tank 9 for displacement reaction. The reaction temperature was 70℃-90℃, the final pH was 5-7, and the reaction time was 14-18 hours. Sponge thallium was obtained after the reaction.

[0044] In this technical solution, a thallium-containing leachate is fed into a zinc plate displacement tank 9. A stirring device is activated, and the reaction temperature is controlled at 70℃-90℃, with a final pH of 5-7 and a reaction time of 14-18 hours. Utilizing the higher reactivity of zinc than thallium, thallium ions in the thallium-containing leachate are displaced and precipitated by the zinc plate, forming sponge thallium. After the reaction is complete, the zinc plate is removed, and the precipitated sponge thallium is collected. This displacement reaction, based on the difference in reactivity between zinc and thallium, is simple and inexpensive. The reaction temperature and pH are controllable, allowing for the conversion of almost all thallium in the thallium-containing leachate into sponge thallium, achieving preliminary purification of thallium.

[0045] In one feasible embodiment, the sponge thallium is refined and cast to obtain thallium ingots, comprising: The sponge thallium is placed into the casting furnace 10 for refining and casting to obtain thallium ingots.

[0046] In this technical solution, sponge thallium is fed into a casting furnace 10 for refining and casting. High-temperature casting removes trace impurities from the sponge thallium, further improving its purity. After refining and casting, the mixture is cooled to room temperature to obtain thallium ingots, achieving efficient recovery and high-purity purification of thallium from high-fluorine and chlorine flue dust. Refining and casting effectively removes trace impurities from the sponge thallium, significantly improving its purity and ultimately yielding high-purity thallium ingots. This achieves efficient recovery of thallium from high-fluorine and chlorine flue dust, facilitating its transportation and reducing environmental pollution during transport.

[0047] Example 1 For a high-fluoride chlorine-containing fly ash with a main chemical composition of Zn-36.35%, containing Tl-0.54%, containing F-0.77%, and containing Cl-5.09%, according to... Figure 1 The process involves the following steps: S1. Transfer the high-fluorine chlorine-containing fly ash to the pellet mill 1 using a trolley, turn on the pellet mill 1 switch, and add the high-fluorine chlorine-containing fly ash and calcium agent (one or more of calcium oxide, quicklime, and calcium carbonate) to the disc of the pellet mill 1 using a shovel. The amount of calcium agent added is 15% of the mass percentage of the high-fluorine chlorine-containing fly ash. After mixing, spread the mixture evenly on the disc of the pellet mill 1. Spray a small amount of clean water evenly onto the disc using a spray bottle. Continue pelletizing until the particle size reaches the preset requirements. Then, turn off the pellet mill 1 switch and add the pelletized high-fluorine chlorine-containing fly ash particles into the hopper of the screw conveyor 2.

[0048] S2. The high-fluorine-chlorine flue dust particles obtained in step S1 are fed into the electric rotary kiln 3 at a rate of 5000 g / h via screw conveyor 2. The calcination temperature of the electric rotary kiln 3 is controlled at 600℃. The total residence time of the material is controlled to be 2 hours from the start of normal discharge from the rotary kiln 3. During the calcination process, the filter cartridge dust collector 44 and the induced draft fan are turned on simultaneously to collect the thallium-containing flue gas generated during calcination, thus obtaining high-thallium flue dust. The main chemical components of this high-thallium flue dust are as follows: Zn-16.32%, Tl-25.64%, F-0.27%, Cl-1.09%.

[0049] S3. The high-thallium flue dust collected by the filter cartridge dust collector 4 in step S2 is sent to the crusher and screener 5 for screening to remove large particles. The screened material is then added to the alkaline leaching tank 6. A pre-prepared sodium hydroxide solution is first added to the alkaline leaching tank 6 to adjust the pH to 10. Then, the high-thallium flue dust is added to react, controlling the liquid-to-solid ratio at 15:1, the reaction temperature at 70℃, and the reaction time at 2 hours. After the reaction is complete, the mixture is cooled to room temperature and then separated by filtration to obtain thallium-containing alkaline leaching solution and alkaline leaching residue. The alkaline leaching residue is washed with water, dried, and then sent to a volatilization kiln for treatment. The main chemical components of the thallium-containing alkaline leaching solution are as follows: Tl - 14.23 g / L, F - 0.17 g / L, Cl - 0.65 g / L. The leaching rates of each element in the flue dust are: Tl leaching rate 91.37%, F leaching rate 79.99%, and Cl leaching rate 79.16%.

[0050] S4. The thallium-containing alkali leaching solution obtained in S3 is transferred to sulfidation tank 7. Sodium sulfide is added to the tank to carry out a sulfidation precipitation reaction. The amount of sodium sulfide added is 5 times the theoretical amount for thallium sulfidation reaction. The reaction temperature is controlled at 40℃ and the reaction time is 30min. After the reaction is completed, the solution is filtered to obtain the sulfidated liquid and the thallium sulfide-enriched residue. The sulfidated liquid is sent to a wastewater treatment plant for treatment. Its thallium content is 0.00064g / L, and the thallium precipitation rate is 99.89%.

[0051] S5. The thallium sulfide enriched residue obtained in S4 is added to acid leaching tank 8 for acid leaching. The leaching temperature is controlled at 80℃, the leaching time is 3h, and the sulfuric acid concentration is 140g / L. After acid leaching, the residue is filtered to obtain thallium-containing leachate and leaching residue. The leaching residue is washed with water, dried, and then sent to a volatilization kiln for treatment. The thallium content of the thallium-containing leachate is 95.05g / L, and the thallium leaching rate is 93.56%.

[0052] S6. The thallium-containing leachate obtained in step 5 is added to the zinc plate displacement tank 9 for displacement reaction. The reaction temperature is controlled at 90℃, the final pH value is about 6, and the reaction time is 18h. After the reaction is completed, sponge thallium is obtained. The sponge thallium contains 92.51% thallium, and the thallium displacement rate is 99.89%.

[0053] S7. The sponge thallium obtained in S6 is sent to the casting furnace 10 for refining and casting to obtain thallium ingot products.

[0054] Results of this round of experiments: According to calculations, the direct recovery rate of Tl from high-fluorine-chlorine flue dust to thallium sulfide enriched slag is 88.69%, the total direct recovery rate from high-fluorine-chlorine flue dust to thallium ingot is 85.31%, and the thallium content of the obtained thallium ingot is 99.95%.

[0055] Example 2 For a high-fluoride chlorine-containing fly ash with a main chemical composition of Zn-36.35%, containing Tl-0.54%, containing F-0.77%, and containing Cl-5.09%, according to... Figure 1 The process involves the following steps: S1. Transfer the high-fluorine-chlorine flue dust to the side of the disc granulator 1 using a trolley, turn on the switch of the granulator 1, and add the high-fluorine-chlorine flue dust and calcium agent (one or more of calcium oxide, quicklime, and calcium carbonate) into the disc of the granulator 1 using a shovel. The amount of calcium agent added is 17% of the mass of the high-fluorine-chlorine flue dust. After mixing, spread the mixture evenly on the disc of the granulator 1. Spray a small amount of clean water evenly into the disc using a spray bottle. Continue granulating until the particle size reaches the preset requirements. Then, turn off the switch of the granulator 1 and add the granulated high-fluorine-chlorine flue dust particles into the hopper of the screw conveyor 2.

[0056] S2. The high-fluorine-chlorine flue dust particles obtained in step S1 are fed into the electric rotary kiln 3 at a rate of 5000 g / h via screw conveyor 2. The calcination temperature of the electric rotary kiln 3 is controlled at 700℃. The total residence time of the material is controlled to be 3 hours from the start of normal discharge from the rotary kiln 3. During the calcination process, the filter cartridge dust collector 4 and the induced draft fan are turned on simultaneously to collect the thallium-containing flue gas generated during calcination, thus obtaining high-thallium flue dust. The main chemical components of this high-thallium flue dust are as follows: Zn-17.14%, Tl-23.78%, F-0.26%, Cl-1.05%.

[0057] S3. The high-thallium flue dust collected by the filter cartridge dust collector 4 in step S2 is sent to the crusher and screener 5 for screening to remove large particles. The screened material is then added to the alkaline leaching tank 6. A pre-prepared sodium hydroxide solution is first added to the alkaline leaching tank 6 to adjust the pH to 9. Then, the high-thallium flue dust is added to react, controlling the liquid-to-solid ratio at 15:1, the reaction temperature at 80℃, and the reaction time at 1.5h. After the reaction is completed, the mixture is cooled to room temperature and then separated by filtration to obtain thallium-containing alkaline leaching solution and alkaline leaching residue. The alkaline leaching residue is washed with water, dried, and then sent to a volatilization kiln for treatment. The main chemical components of the thallium-containing alkaline leaching solution are as follows: Tl - 13.88 g / L, F - 0.16 g / L, Cl - 0.58 g / L. The leaching rates of each element in the flue dust are: Tl leaching rate 90.54%, F leaching rate 78.58%, and Cl leaching rate 79.44%.

[0058] S4. The thallium-containing alkali leaching solution obtained in S3 is transferred to sulfidation tank 7. Sodium sulfide is added to the tank to carry out a sulfidation precipitation reaction. The amount of sodium sulfide added is 5 times the theoretical amount for thallium sulfidation reaction. The reaction temperature is controlled at 50℃ and the reaction time is 30 min. After the reaction is completed, the solution is filtered to obtain the sulfidated liquid and the thallium sulfide-enriched residue. The sulfidated liquid is sent to a wastewater treatment plant for treatment. Its thallium content is 0.00058 g / L, and the thallium precipitation rate is 99.98%.

[0059] S5. The thallium sulfide enriched residue obtained in S4 is added to acid leaching tank 8 for acid leaching. The leaching temperature is controlled at 60℃, the leaching time at 5h, and the sulfuric acid concentration at 140g / L. After acid leaching, the residue is filtered to obtain thallium-containing leachate and leaching residue. The leaching residue is washed with water, dried, and then sent to a volatilization kiln for treatment. The thallium content of the thallium-containing leachate is 96.12g / L, and the thallium leaching rate is 94.33%.

[0060] S6. The thallium-containing leachate obtained in step S5 is added to the zinc plate displacement tank 9 for displacement reaction. The reaction temperature is controlled at 90℃, the final pH value is about 6, and the reaction time is 18h. After the reaction is completed, sponge thallium is obtained. The sponge thallium contains 93.47% thallium, and the thallium displacement rate is 99.94%.

[0061] S7. The sponge thallium obtained in S6 is sent to the casting furnace 10 for refining and casting to obtain thallium ingot products.

[0062] Results of this round of experiments: According to calculations, the direct recovery rate of Tl from high-fluorine-chlorine flue dust to thallium sulfide enriched slag is 87.47%, the total direct recovery rate from high-fluorine-chlorine flue dust to thallium ingot is 86.58%, and the thallium content of the obtained thallium ingot is 99.94%.

[0063] Example 3 For a high-fluoride chlorine-containing fly ash with a main chemical composition of Zn-36.35%, containing Tl-0.54%, containing F-0.77%, and containing Cl-5.09%, according to... Figure 1 The process involves the following steps: S1. Transfer the high-fluorine chlorine-containing fly ash to the pellet mill 1 using a trolley, turn on the pellet mill 1 switch, and add the high-fluorine chlorine-containing fly ash and calcium agent (one or more of calcium oxide, quicklime, and calcium carbonate) to the disc of the pellet mill 1 using a shovel. The amount of calcium agent added is 13% of the mass of the high-fluorine chlorine-containing fly ash. After mixing, spread the mixture evenly on the disc of the pellet mill 1. Spray a small amount of clean water evenly onto the disc using a spray bottle. Continue pelletizing until the particle size reaches the preset requirements. Then, turn off the pellet mill 1 switch and add the pelletized high-fluorine chlorine-containing fly ash particles into the hopper of the screw conveyor 2.

[0064] S2. The high-fluorine-chlorine flue dust particles obtained in step S1 are fed into the electric rotary kiln 3 at a rate of 6000 g / h via screw conveyor 2. The calcination temperature of the electric rotary kiln 3 is controlled at 800℃. The total residence time of the material is controlled to be 4 hours, starting from the time the material is discharged normally from the rotary kiln 3. During the calcination process, the cartridge dust collector 4 and the induced draft fan are turned on simultaneously to collect the thallium-containing flue gas generated during calcination, thus obtaining high-thallium flue dust. The main chemical composition of this high-thallium flue dust is as follows: Zn-15.33%, Tl-26.88%, F-0.25%, Cl-1.14%.

[0065] S3. The high-thallium flue dust collected by the filter cartridge dust collector 4 in step S2 is sent to the crusher and screener 5 for screening to remove large particles. The screened material is then added to the alkaline leaching tank 6. A pre-prepared sodium hydroxide solution is first added to the alkaline leaching tank 6 to adjust the pH to 10. Then, the high-thallium flue dust is added to react, controlling the liquid-to-solid ratio at 15:1, the reaction temperature at 60℃, and the reaction time at 3 hours. After the reaction is completed, the mixture is cooled to room temperature and separated by filtration to obtain thallium-containing alkaline leaching solution and alkaline leaching residue. The alkaline leaching residue is washed with water, dried, and then sent to a volatilization kiln for treatment. The main chemical components of the thallium-containing alkaline leaching solution are as follows: Tl - 13.46 g / L, F - 0.17 g / L, Cl - 0.59 g / L. The leaching rates of each element in the flue dust are: Tl leaching rate 91.25%, F leaching rate 80.14%, and Cl leaching rate 79.77%.

[0066] S4. The thallium-containing alkali leaching solution obtained in S3 is transferred to sulfidation tank 7. Sodium sulfide is added to the tank to carry out a sulfidation precipitation reaction. The amount of sodium sulfide added is 5 times the theoretical amount for thallium sulfidation reaction. The reaction temperature is controlled at 50℃ and the reaction time is 40min. After the reaction is completed, the solution is filtered to obtain the sulfidated liquid and the thallium sulfide-enriched residue. The sulfidated liquid is sent to a wastewater treatment plant for treatment. Its thallium content is 0.00048g / L and the thallium precipitation rate is 99.98%.

[0067] S5. The thallium sulfide enriched residue obtained in S4 was added to acid leaching tank 8 for acid leaching. The leaching temperature was controlled at 60℃, the leaching time at 3h, and the sulfuric acid concentration at 120g / L. After acid leaching, the residue was filtered to obtain thallium-containing leachate and leaching residue. The leaching residue was washed with water, dried, and then sent to a volatilization kiln for treatment. The thallium-containing leachate contained 94.98g / L of thallium, and the thallium leaching rate was 92.41%.

[0068] S6. The thallium-containing leachate obtained in step S5 is added to the zinc plate displacement tank 9 for displacement reaction. The reaction temperature is controlled at 90℃, the final pH value is about 6, and the reaction time is 17h. After the reaction is completed, sponge thallium is obtained. The sponge thallium contains 93.11% thallium and the thallium displacement rate is 99.75%.

[0069] S7. The sponge thallium obtained in S6 is sent to the casting furnace 10 for refining and casting to obtain thallium ingot products.

[0070] Results of this round of experiments: According to calculations, the direct recovery rate of Tl from high-fluorine-chlorine flue dust to thallium sulfide enriched slag is 86.89%, the total direct recovery rate from high-fluorine-chlorine flue dust to thallium ingot is 84.94%, and the thallium content of the obtained thallium ingot is 99.94%.

[0071] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A process for recovering thallium from high fluorine and chlorine soot, characterized in that, Includes the following steps: S1. Mix high-fluoride chlorine-containing fly ash with calcium agent and granulate to obtain high-fluoride chlorine-containing fly ash particles; S2. The high-fluorine-chlorine flue dust particles are fed into a rotary kiln (3) for roasting. The flue gas generated during roasting is collected by a dust collection system to obtain high-thallium flue dust. S3. After crushing and screening the high thallium flue dust through a crusher and screener (5), the undersize material with the required particle size is obtained. The undersize material is added to an alkaline leaching tank (6) containing sodium hydroxide solution for reaction and filtration to obtain thallium-containing alkaline leaching solution and alkaline leaching residue. S4. Add the thallium-containing alkali leaching solution to the sulfidation tank (7), and then add sodium sulfide to the sulfidation tank (7) to carry out the sulfidation precipitation reaction. After the reaction, filter to obtain thallium sulfide enriched slag and sulfidation liquid. S5. Add the thallium sulfide enriched residue to the acid leaching tank (8) containing sulfuric acid solution for acid leaching. After the reaction, filter to obtain thallium-containing leachate and leaching residue. S6. The thallium-containing leachate is added to the zinc plate displacement tank (9) to carry out a displacement reaction to obtain sponge thallium; S7. The sponge thallium is refined and melted to obtain thallium ingots.

2. The process for recovering thallium from high fluoro-chlorine soot according to claim 1, characterized in that, High-fluoride chlorine-containing fly ash is mixed with calcium agent and then granulated with water to obtain high-fluoride chlorine-containing fly ash particles, including: The high-fluoride chlorine-containing fly ash and the calcium agent are fed into the disc of the granulator (1). The amount of calcium agent added is 11%-19% of the mass of the high-fluoride chlorine-containing fly ash. After uniformly spraying water onto the disc, granulation is carried out. After the particle size reaches the preset particle size, the high-fluoride chlorine-containing fly ash particles are obtained.

3. The process for recovering thallium from high-fluoride chlorine flue dust according to claim 2, characterized in that, The calcium agent is at least one of calcium oxide, quicklime, or calcium carbonate.

4. The process for recovering thallium from high-fluoride and chlorine-containing flue dust according to claim 1, characterized in that, The high-fluorine-chlorine flue dust particles are fed into a rotary kiln (3) for calcination. The flue gas generated during calcination is collected by a dust collection system to obtain high-thallium flue dust, comprising: The high-fluorine-chlorine ash particles are fed into a rotary kiln (3) via a screw conveyor (2). The rotary kiln (3) is calcined at a temperature of 500℃-800℃. The residence time of the high-fluorine-chlorine ash particles in the rotary kiln (3) is 1-4 hours. While the high-fluorine-chlorine ash particles are calcined, the dust collection system collects the flue gas generated during calcination.

5. The process for recovering thallium from high-fluoride chlorine flue dust according to claim 4, characterized in that, The dust collection system includes a cartridge dust collector (4) and an induced draft fan. The cartridge dust collector (4) is connected to the rotary kiln (3) through a pipeline, and the induced draft fan is installed on the pipeline.

6. The process for recovering thallium from high-fluoride chlorine flue dust according to claim 1, characterized in that, The high-thallium flue dust is crushed and screened by a crusher and screener (5) to obtain undersize material that meets the particle size requirements. The undersize material is added to an alkaline leaching tank (6) containing sodium hydroxide solution for reaction and filtration to obtain thallium-containing alkaline leaching solution and alkaline leaching residue, including: The high-thallium flue dust obtained from the dust collection system is crushed and screened by a crusher and screener (5). The undersize material that meets the particle size requirement is added to an alkaline leaching tank (6). Sodium hydroxide solution is first added to the alkaline leaching tank (6) to control the pH of the solution to 8-11. Then the undersize material is added to react. The liquid-solid ratio of the reaction is 10:1-20:1, the reaction temperature is 60℃-80℃, and the reaction time is 1-3 hours. After the reaction is completed, the mixture is cooled to room temperature and filtered to obtain thallium-containing alkaline leaching solution and alkaline leaching residue.

7. The process for recovering thallium from high-fluoride chlorine flue dust according to claim 1, characterized in that, The thallium-containing alkali leaching solution is added to the sulfidation tank (7), and then sodium sulfide is added to the sulfidation tank (7) to carry out a sulfidation precipitation reaction. After the reaction, the mixture is filtered to obtain thallium sulfide enriched slag and sulfidation liquid, including: The thallium-containing alkali leaching solution is added to the sulfidation tank (7), and sodium sulfide is added to the sulfidation tank (7) to carry out the reaction. The amount of sodium sulfide added is 3-5 times the theoretical amount of the reaction, the reaction temperature is 30℃-50℃, and the reaction time is 20-40 minutes. After the reaction is completed, the solution is filtered to obtain the sulfidation liquid and the thallium sulfide enriched residue.

8. The process for recovering thallium from high-fluoride chlorine flue dust according to claim 1, characterized in that, The thallium sulfide enriched residue is added to an acid leaching tank (8) containing sulfuric acid solution for acid leaching. After the reaction, the residue is filtered to obtain a thallium-containing leachate and a leaching residue, comprising: The thallium sulfide enrichment residue is added to an acid leaching tank (8) for acid leaching. The acid leaching temperature is 60℃-80℃, the acid leaching time is 3-5 hours, and the sulfuric acid concentration is 100g / L-140g / L. After acid leaching, the residue is filtered to obtain thallium-containing leachate and leachate residue.

9. The process for recovering thallium from high-fluoride chlorine flue dust according to claim 1, characterized in that, The thallium-containing leachate is added to a zinc plate displacement tank (9) to carry out a displacement reaction, resulting in sponge thallium, comprising: The thallium-containing leachate was added to the zinc plate displacement tank (9) for displacement reaction. The reaction temperature was 70℃-90℃, the final pH was 5-7, and the reaction time was 14-18 hours. Sponge thallium was obtained after the reaction.

10. The process for recovering thallium from high-fluoride-chlorine flue dust according to claim 1, characterized in that, The sponge thallium is refined and melted to obtain thallium ingots, comprising: The sponge thallium is placed into a casting furnace (10) for refining and casting to obtain thallium ingots.

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