A method for recovering indium from zinc dust cementation residue

Abstract

The application provides a method for recovering indium from zinc powder displacement slag, which comprises the following steps: adding sulfuric acid into the zinc powder displacement slag to perform staged roasting, then performing stirring leaching, reduction, separation, extraction and stripping to realize the extraction of indium. The method can strengthen the decomposition of indium-containing phases in the zinc powder displacement slag through sulfuric acid roasting, optimize the material ratio of sulfuric acid and zinc displacement slag, control the pH value of the material liquid in a suitable range, and be beneficial to the subsequent reduction of Fe 3+ , and can significantly improve the effect of subsequent extraction. In addition, according to the distribution range of the particle size of the zinc displacement slag, the application also sets staged roasting to strengthen the decomposition effect of sulfuric acid on the zinc displacement slag, and improve the utilization rate of the zinc powder displacement slag and the indium leaching rate. Furthermore, the application optimizes the flow ratio, centrifugal speed and reaction order of the centrifugal extraction and stripping, so that the oil-water separation effect of the whole system is high, the labor intensity is low, the indium storage amount is small, and the cost is reduced. The recovery rate of indium in the zinc powder displacement slag can reach more than 95% by using the method.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal smelting, and more particularly to a method for recovering indium from zinc powder displacement slag. Background Technology

[0002] With the increasing demand in high-tech fields, indium's value as a strategic key metal is becoming increasingly prominent, playing a vital role in electronics, solar cells, defense, aerospace, and high-end information technology industries. Although indium exists as independent minerals, such as indium copper pyrolusite and indium iron pyrolusite, its reserves are extremely limited, with the vast majority dispersed within sulfide ores, especially sphalerite. my country has the world's largest indium reserves, with proven resources of nearly 20,000 tons, accounting for approximately 72% of the world's total. It is also the world's largest producer and exporter of indium. However, my country's indium smelting capacity and deep processing level still lag significantly behind those of other countries. How to efficiently recover indium from ore has always been a research hotspot in the metallurgical field, which is of significant strategic importance for safeguarding the national economy, national security, and technological development.

[0003] Since indium is primarily found in sphalerite, the main strategy for indium recovery is to first enrich it during zinc smelting and then recover it from the enriched material. Currently, zinc smelting methods are mainly hydrometallurgical processes, divided into two types: zinc concentrate roasting-hydrometallurgical leaching and zinc concentrate direct oxygen pressure leaching. Due to the different smelting processes, the enrichment and distribution of indium also vary. Indium-enriched materials mainly include iron ore slag, iron slag, intermediate leaching slag, and zinc powder replacement slag. However, it is worth noting that recovering indium from iron ore slag, iron slag, or intermediate leaching slag first requires placing it in a rotary kiln for high-temperature volatilization, causing indium to be enriched in zinc oxide dust, and then recovering indium from the zinc oxide dust. This increases the difficulty of indium recovery, and the overall indium volatilization recovery rate is not high, resulting in resource waste.

[0004] The recovery of indium from zinc powder replacement slag mainly employs conventional acid leaching, pressurized oxidative acid leaching, or a combination of both. However, these methods suffer from drawbacks such as low indium leaching rates, low indium concentrations in the leaching solution, and lengthy processing times. Therefore, it is imperative to find a more efficient method for leaching, separating, and recovering indium from zinc powder replacement slag. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a method for recovering indium from zinc powder replacement slag. By performing steps such as sulfation-graded roasting, stirring leaching, reduction, and centrifugal extraction-back-extraction on the zinc powder replacement slag, the recovery rate of indium is significantly improved.

[0006] The specific details of the invention are as follows:

[0007] In a first aspect, the present invention provides a method for recovering indium from zinc powder displacement slag, the method comprising:

[0008] The zinc powder replacement slag is crushed to a particle size of -200 mesh to -400 mesh, mixed with concentrated sulfuric acid, and calcined at a temperature of 150 to 400°C for 0.5 to 4 hours to obtain the calcined material; the mass ratio of the zinc powder replacement slag to concentrated sulfuric acid is 1:0.1 to 1.

[0009] Water is added to the calcined material, and the mixture is stirred and leached at a temperature of 25–90°C for 0.5–4 hours. The mixture is then filtered to obtain an indium-zinc-iron filtrate. The solid-liquid ratio of the calcined material to water is 1:3–10.

[0010] A reducing agent is added to the indium-zinc-iron filtrate to make Fe 3+ Reduced to Fe 2+ After the reaction, the sample was filtered to obtain Fe. 3+ Filtrate with a concentration of less than 0.1 g / L;

[0011] The filtrate is added to an extractant and a diluent for centrifugal extraction. The flow ratio of the centrifugal extraction is 1:3 to 7, the pH of the centrifugal extraction is 1.0, the number of centrifugal extraction stages is 2 to 4, and the centrifugation speed is 4000 to 7000 rpm, yielding an indium-loaded organic phase and a raffinate. The mass ratio of the extractant to the diluent is 10 to 30%: 70 to 90%. The extractant is P2O4, and the diluent is sulfonated kerosene.

[0012] A 3-5 mol / L hydrochloric acid solution is added to the indium-supported organic phase for centrifugal back-extraction. The flow ratio of the back-extraction is 3-7:1, the number of back-extraction stages is 2-4, and the centrifugation speed is 4000-6000 rpm to obtain an indium-containing back-extraction solution. A zinc plate is added to the indium-containing back-extraction solution for displacement, followed by alkali melting and ingot casting to obtain an indium ingot.

[0013] Optionally, the mass ratio of the zinc powder replacement slag to concentrated sulfuric acid is 1:0.3 to 0.7.

[0014] Optionally, the calcination is a staged calcination, comprising: calcining at a temperature of 180-240°C for 0.5-1.5 hours, and then calcining at a temperature of 230-300°C for 1.5-2 hours.

[0015] Optionally, the calcination is a staged calcination, comprising: calcining at a temperature of 200–220°C for 0.5–1.5 h, and then calcining at a temperature of 260–290°C for 1.5–2 h.

[0016] Optionally, the leaching temperature is 60-80°C, the leaching time is 0.5-2 hours, and the solid-liquid ratio of the calcined material to water is 1:3-5.

[0017] Optionally, the stirring is mechanical stirring; the stirring speed is 200-300 rpm.

[0018] Optionally, the zinc powder replacement slag contains, by mass percentage, 0.01-3% indium, 2-20% zinc, 1-10% iron, 3-15% silicon dioxide, 0.2-3% arsenic, and 0.2-1% cadmium.

[0019] Optionally, the reducing agent is one or more of zinc powder, iron powder, and zinc sulfide concentrate; the molar ratio of the iron content of the reducing agent to the zinc powder replacement slag is 1.0 to 3.6.

[0020] Optionally, the flow ratio of the centrifugal extraction is 1:5 to 7; the number of stages of the centrifugal back-extraction is 2 to 3; the centrifugation speed is 5000 to 7000 rpm; and the mass ratio of the extractant to the diluent is 15 to 25%: 75 to 85%.

[0021] Optionally, the flow ratio of the centrifugal back-extraction is 5 to 7:1; the number of stages of the centrifugal back-extraction is 2 to 3; and the centrifugation speed is 4000 to 5000 rpm.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] This invention provides a method for recovering indium from zinc powder replacement slag. The method involves adding sulfuric acid to the zinc powder replacement slag for staged roasting, followed by stirring leaching, adding a reducing agent, and separation extraction-back-extraction steps to extract indium. Compared to existing commonly used methods for recovering indium, this invention proposes a method for enhanced decomposition of indium-containing phases in zinc powder replacement slag through sulfation roasting, and optimizes the material ratio of sulfuric acid to zinc replacement slag to maintain the pH value of the solution within a suitable range, which is beneficial for subsequent Fe... 3+ The reduction also significantly improves the subsequent extraction effect, eliminating the need for additional neutralizing or alkaline agents to adjust the pH of the feed solution. Specifically, at a pH of 1-2, this invention also controls the amount of reducing agent to reduce the Fe content in the filtrate. 3+ The content is less than 0.1 g / L, avoiding Fe 3+ The interference with the indium extraction process ensured a high indium recovery rate and improved production efficiency.

[0024] Furthermore, based on the particle size distribution range in the zinc replacement slag, this invention incorporates a staged roasting process, first at a suitable low temperature and then at a high temperature. This enhances the decomposition effect of sulfuric acid on the zinc replacement slag, improving the utilization rate of the zinc powder replacement slag and the subsequent indium leaching rate, which can reach over 95%. This invention achieves the resource utilization of zinc powder replacement slag, yielding significant economic and environmental benefits and meeting the current requirements of green metallurgy for clean production.

[0025] In addition, this invention optimizes parameters such as the flow ratio, centrifugal speed, and reaction order of centrifugal extraction-back-extraction, resulting in high oil-water separation efficiency, low labor intensity, and low indium storage tank volume, which significantly reduces energy consumption and costs. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This diagram illustrates a method flow chart for recovering indium from zinc powder displacement slag according to an embodiment of the present invention.

[0028] Figure 2 A schematic diagram of the operation flow of the method for recovering indium from zinc powder replacement slag provided in an embodiment of the present invention is shown. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0030] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0031] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0032] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0033] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] Based on existing technologies for recovering indium from zinc powder replacement slag, which suffer from low indium recovery rates and complex processes, the inventors of this application, through repeated analysis, literature review, and experimental exploration, have reached the following conclusions: Under conventional acid leaching processes, the incomplete decomposition of the zinc replacement slag leads to a low indium leaching rate. Acid leaching followed by roasting can effectively improve the decomposition efficiency of the zinc powder replacement slag. However, the zinc powder replacement slag has a wide particle size distribution; smaller particles tend to fluidize at high temperatures, moving away from the high-temperature environment, resulting in a shorter roasting time and ineffective decomposition, leading to a low indium recovery rate (~90%). Larger particles require prolonged high-temperature roasting to achieve complete decomposition. Furthermore, the Fe in the indium leaching solution... 3+ Excessive concentration can also affect the indium extraction process, resulting in a low indium recovery rate. Therefore, this invention proposes a method for recovering indium from zinc powder replacement slag. Specifically, by subjecting the zinc powder replacement slag to sulfation-stage roasting, stirred leaching, reduction, and centrifugal extraction-back-extraction, the indium leaching rate is significantly improved, the extraction process is simplified, and production efficiency is increased. The specific implementation method is as follows:

[0035] In a first aspect, the present invention provides a method for recovering indium from zinc powder displacement slag. Figure 1 A schematic diagram of the method for recovering indium from zinc powder displacement slag provided in an embodiment of the present invention is shown, as follows: Figure 1 As shown, the method includes:

[0036] S1. The zinc powder replacement slag is crushed to a particle size of -200 mesh to -400 mesh, concentrated sulfuric acid is added and mixed evenly, and then roasted at a temperature of 150 to 400°C for 0.5 to 4 hours to obtain the roasted material; the mass ratio of the zinc powder replacement slag to concentrated sulfuric acid is 1:0.1 to 1.

[0037] In this specific step, the zinc powder replacement slag is first pulverized to a particle size of -200 mesh to -400 mesh, then mixed evenly with concentrated sulfuric acid. The mass ratio of zinc powder replacement slag to concentrated sulfuric acid is 1:0.1 to 1. The zinc powder replacement slag contains, by mass percentage: indium 0.01 to 3%, zinc 2 to 20%, iron 1 to 10%, silicon dioxide 3 to 15%, arsenic 0.2 to 3%, and cadmium 0.2 to 1%. Then, it is calcined at a temperature of 150 to 400°C for 0.5 to 4 hours to obtain the calcined material. The calcination process involves calcining at 180–240°C for 0.5–1.5 hours, followed by calcination at 230–300°C for 1.5–2 hours. Preferably, the mass ratio of zinc powder replacement slag to concentrated sulfuric acid is 1:0.3–0.7, and the calcination conditions are: calcination at 200–220°C for 0.5–1.5 hours, followed by calcination at 260–290°C for 1.5–2 hours. This method yields an ideal indium leaching rate of over 95%.

[0038] S2. Add water to the calcined material, stir and leach, the leaching temperature is 25-90℃, the leaching time is 0.5-4h, filter, and obtain indium-zinc-iron filtrate; the solid-liquid ratio of the calcined material to water is 1:3-10;

[0039] In this specific step, water is first added to the calcined material, and leaching is carried out with stirring for 0.5 to 4 hours at a leaching temperature of 25 to 90°C. The solid-liquid ratio of the calcined material to water is 1:3 to 10, and the stirring is mechanical, with a stirring speed of 200 to 300 rpm. Then, the mixture is filtered to obtain an indium-zinc-iron filtrate. Preferably, leaching with stirring for 0.5 to 2 hours at a leaching temperature of 60 to 80°C, and a solid-liquid ratio of the calcined material to water of 1:3 to 5, is more conducive to the leaching of indium.

[0040] S3. Add a reducing agent to the indium-zinc-iron filtrate to make Fe 3+ Reduced to Fe 2+ After the reaction, the sample was filtered to obtain Fe. 3 + Filtrate with a concentration of less than 0.1 g / L;

[0041] In this specific step, a reducing agent is added to the indium-zinc-iron filtrate to reduce the Fe... 3+ Reduced to Fe 2+ The reducing agent is one or more of zinc powder, iron powder, and zinc sulfide concentrate. The molar ratio of iron content in the reducing agent to the zinc powder-substituted slag is 1.0–3.6. After the reaction, the mixture is filtered to obtain Fe. 3+ Filtrate with a concentration of less than 0.1 g / L.

[0042] S4. Add an extractant and a diluent to the filtrate and perform centrifugal extraction. The flow ratio of the centrifugal extraction is 1:3 to 7, the pH of the centrifugal extraction is 1.0, the number of centrifugal extraction stages is 2 to 4, and the centrifugation speed is 4000 to 7000 rpm, to obtain an indium-loaded organic phase and raffinate. The mass ratio of the extractant to the diluent is 10 to 30%: 70 to 90%. The extractant is P2O4, and the diluent is sulfonated kerosene.

[0043] In specific implementation, an extractant and a diluent are added to the filtrate for centrifugal extraction. The extractant used in centrifugal extraction is P204, and the diluent is sulfonated kerosene. The flow ratio (volume ratio of organic phase to inorganic phase, O / A) of centrifugal extraction is 1:3-7, the pH of centrifugal extraction is 1.0, the number of centrifugal extraction stages is 2-4, and the centrifugation speed is 4000-7000 rpm, yielding an indium-loaded organic phase and raffinate. The mass ratio of P204 to sulfonated kerosene is 10-30%:70-90%. Preferably, when the flow ratio of centrifugal extraction is 1:5-7, the number of centrifugal extraction stages is 2-3, the centrifugation speed is 5000-7000 rpm, and the mass ratio of P204 to sulfonated kerosene is 15-25%:75-85%, the extraction effect is good, the impurity content is low, and the energy consumption is low.

[0044] S5. Add 3-5 mol / L hydrochloric acid solution to the indium-loaded organic phase for centrifugal back-extraction. The flow ratio of the centrifugal back-extraction is 3-7:1, the number of centrifugal back-extraction stages is 2-4, and the centrifugation speed is 4000-6000 rpm to obtain an indium-containing back-extraction solution. Add zinc plate to the indium-containing back-extraction solution for displacement, and then perform alkali melting and ingot casting to obtain indium ingots.

[0045] In this specific step, a 3-5 mol / L hydrochloric acid solution is added to the indium-loaded organic phase for centrifugal back-extraction. The hydrochloric acid solution is used as the extractant for centrifugal back-extraction. The flow ratio of the centrifugal back-extraction is 3-7:1, the number of stages is 2-4, and the centrifugation speed is 4000-6000 rpm, resulting in an indium-containing back-extraction solution. Preferably, when the flow ratio of the centrifugal back-extraction is 5-7:1, the number of stages is 2-3, and the centrifugation speed is 4000-5000 rpm, the back-extraction effect is good and the indium leaching rate is high. A zinc plate is added to the indium-containing back-extraction solution for displacement, followed by alkali melting and ingot casting to obtain indium ingots.

[0046] Traditional acid leaching processes for recovering indium from zinc powder replacement slag suffer from poor decomposition efficiency, complex procedures, and low indium leaching rates, resulting in significant application drawbacks. This invention employs a method of first acid dissolution followed by staged roasting, optimizing the roasting process to maximize the conversion of indium in the zinc powder replacement slag into sulfates. Simultaneously, it removes harmful impurities such as fluorine and chlorine, providing a high-quality feed solution for subsequent extraction processes. This effectively reduces sulfuric acid consumption and energy consumption in extraction-back-extraction, significantly improving the decomposition efficiency and utilization rate of the zinc replacement slag, greatly increasing the indium leaching rate, and simplifying the process flow.

[0047] To enable those skilled in the art to more clearly understand the present invention, the following embodiments will be used to describe in detail a method for recovering indium from zinc powder displacement slag according to the present invention.

[0048] Figure 2 The diagram illustrates the operational flow of the method for recovering indium from zinc powder displacement slag provided by this invention. The zinc powder displacement slag is subjected to fine grinding, sulfation roasting, stirring leaching, reduction to remove trivalent iron, filtration, centrifugal extraction-back-extraction, displacement, alkali fusion, and casting to obtain the target indium ingot. The following embodiments are all implemented with reference to this operational flow diagram.

[0049] Example 1

[0050] The mass percentages of the components in the high-speed iron indium-zinc calcined ore from a zinc smelter in Guangxi are: Zn 54.4%, Fe 15.52%, In 0.093%. During the indium recovery process, zinc powder replacement slag was obtained. The zinc powder replacement slag is the slag produced after zinc powder replacement in the hydrometallurgical process of high-speed iron indium-zinc calcined ore. The mass percentages of the valuable components are: indium 0.01-3%, zinc 2-25%, iron 1-10%, silicon dioxide 3-15%, arsenic 0.2-3%, and cadmium 0.2-1%.

[0051] First, 1 kg of zinc powder replacement slag is finely ground to a particle size of -200 to -400 mesh. It is then mixed evenly with concentrated sulfuric acid at a mass ratio of 1:0.3 and placed in a muffle furnace. The mixture is roasted at 200℃ for 1 hour, followed by roasting at 280℃ for 1.5 hours to obtain the roasted material. This material is then leached in water at a stirring speed of 200-300 rpm, a leaching temperature of 60℃, and a leaching time of 0.5 hours. The solid-liquid ratio (g / mL) of the roasted material to water is 1:3. After leaching, solid-liquid separation is performed to obtain an indium-zinc-iron filtrate. Zinc sulfide concentrate is then added to the indium-zinc-iron filtrate for Fe... 3+ The reduction reaction resulted in a molar ratio of iron content of 2.6 between zinc sulfide concentrate and zinc powder replacement slag; the Fe content in the filtrate was... 3+The reaction was stopped and filtered after the ion concentration decreased to below 0.1 g / L, yielding a filtrate. The filtrate was collected and subjected to centrifugal extraction under the following conditions: extractant was P2O4, diluent was sulfonated kerosene, extractant concentration was 15%, extraction pH was 1.0, flow ratio (O / A) was 1:5, centrifugation speed was 4000 rpm, and the number of centrifugal extraction stages was 2, yielding an indium-loaded organic phase and raffinate. The raffinate was de-ironized to obtain a zinc-rich solution, which could be returned to the main process for zinc recovery. The indium-loaded organic phase was centrifuged and back-extracted to obtain an indium-containing back-extractant. The back-extractant was 3 mol / L hydrochloric acid solution, flow ratio (O / A) was 5:1, centrifugation speed was 4000 rpm, and the number of back-extracting stages was 2. The indium-rich back-extractant was replaced with a zinc plate to obtain sponge indium. The sponge indium was then alkali-fused and cast into ingots to obtain indium ingots.

[0052] The indium recovery rate was calculated to be 95.5%.

[0053] Example 2

[0054] The mass percentages of the components in the high-speed iron indium-zinc calcined ore from a zinc smelter in Guangxi are: Zn 54.4%, Fe 15.52%, In 0.093%. During the indium recovery process, zinc powder replacement slag was obtained. The zinc powder replacement slag is the slag produced after zinc powder replacement in the hydrometallurgical process of high-speed iron indium-zinc calcined ore. The mass percentages of the valuable components are: indium 0.01-3%, zinc 2-25%, iron 1-10%, silicon dioxide 3-15%, arsenic 0.2-3%, and cadmium 0.2-1%.

[0055] First, 1 kg of zinc powder replacement slag is finely ground to a particle size of -200 mesh to -400 mesh. It is then mixed evenly with concentrated sulfuric acid at a mass ratio of 1:0.4 and placed in a muffle furnace. The mixture is roasted at 210℃ for 0.5 h, followed by roasting at 270℃ for 1.5 h to obtain the roasted material. This roasted material is then leached in water with stirring at 200-300 rpm at 70℃ for 1 h, with a solid-liquid ratio (g / mL) of 1:4. After leaching, solid-liquid separation is performed to obtain an indium-zinc-iron filtrate. Iron powder is then added to the indium-zinc-iron filtrate for Fe... 3+ The reduction reaction, with the iron powder and zinc powder replacing the slag in a molar ratio of 1.8, resulted in Fe in the filtrate. 3+The reaction was stopped and filtered after the ion concentration decreased to below 0.1 g / L, yielding a filtrate. The filtrate was collected and subjected to centrifugal extraction under the following conditions: extractant was P2O4, diluent was sulfonated kerosene, extractant concentration was 20%, extraction pH was 1.0, flow ratio (O / A) was 1:6, centrifugation speed was 5000 rpm, and the number of centrifugal extraction stages was 2, yielding an indium-loaded organic phase and raffinate. The raffinate was de-ironized to obtain a zinc-rich solution, which could be returned to the main process for zinc recovery. The indium-loaded organic phase was centrifuged and back-extracted to obtain an indium-containing back-extractant. The back-extractant was 3 mol / L hydrochloric acid solution, flow ratio (O / A) was 6:1, centrifugation speed was 5000 rpm, and the number of back-extracting stages was 2. The indium-containing back-extractant was replaced with a zinc plate to obtain sponge indium. The sponge indium was then alkali-fused and cast into ingots to obtain indium ingots.

[0056] The indium recovery rate was calculated to be 97.1%.

[0057] Example 3

[0058] The mass percentages of the components in the high-speed iron indium-zinc calcined ore from a zinc smelter in Guangxi are: Zn 54.4%, Fe 15.52%, In 0.093%. During the indium recovery process, zinc powder replacement slag was obtained. The zinc powder replacement slag is the slag produced after zinc powder replacement in the hydrometallurgical process of high-speed iron indium-zinc calcined ore. The mass percentages of the valuable components are: indium 0.01-3%, zinc 2-25%, iron 1-10%, silicon dioxide 3-15%, arsenic 0.2-3%, and cadmium 0.2-1%.

[0059] First, 1 kg of zinc powder replacement slag is finely ground to a particle size of -200 to -400 mesh. It is then mixed evenly with concentrated sulfuric acid at a mass ratio of 1:0.5 and placed in a muffle furnace. The mixture is roasted at 220℃ for 1 hour, followed by roasting at 270℃ for 2 hours to obtain the roasted material. This roasted material is then leached in water with stirring at 200-300 rpm at 80℃ for 1.5 hours, with a solid-liquid ratio (g / mL) of 1:5. After leaching, solid-liquid separation is performed to obtain an indium-zinc-iron filtrate. Iron powder is then added to the indium-zinc-iron filtrate for Fe... 3+ The reduction reaction resulted in a slag with an iron content molar ratio of 2.8 between iron powder and zinc powder. The Fe content in the filtrate was... 3+The reaction was stopped and filtered after the ion concentration decreased to below 0.1 g / L, yielding a filtrate. The filtrate was collected and subjected to centrifugal extraction under the following conditions: extractant was P2O4, diluent was sulfonated kerosene, extractant concentration was 25%, extraction pH was 1.0, flow ratio (O / A) was 1:7, centrifugation speed was 6000 rpm, and the number of centrifugal extraction stages was 3, yielding an indium-loaded organic phase and raffinate. The raffinate was de-ironized to obtain a zinc-rich solution, which could be returned to the main process for zinc recovery. The indium-loaded organic phase was centrifuged and back-extracted to obtain an indium-containing back-extractant. The back-extractant was 4 mol / L hydrochloric acid solution, flow ratio (O / A) was 7:1, centrifugation speed was 6000 rpm, and the number of back-extracting stages was 3. The indium-rich back-extractant was replaced with a zinc plate to obtain sponge indium. The sponge indium was then alkali-fused and cast into ingots to obtain indium ingots.

[0060] The indium recovery rate was calculated to be 96.8%.

[0061] Example 4

[0062] The mass percentages of the components in the high-speed iron indium-zinc calcined ore from a zinc smelter in Guangxi are: Zn 54.4%, Fe 15.52%, In 0.093%. During the indium recovery process, zinc powder replacement slag was obtained. The zinc powder replacement slag is the slag produced after zinc powder replacement in the hydrometallurgical process of high-speed iron indium-zinc calcined ore. The mass percentages of the valuable components are: indium 0.01-3%, zinc 2-25%, iron 1-10%, silicon dioxide 3-15%, arsenic 0.2-3%, and cadmium 0.2-1%.

[0063] First, 1 kg of zinc powder replacement slag is finely ground to a particle size of -200 mesh to -400 mesh. It is then mixed evenly with concentrated sulfuric acid at a mass ratio of 1:0.7 and placed in a muffle furnace. The mixture is roasted at 220℃ for 0.5 h, followed by roasting at 280℃ for 1.5 h to obtain the roasted material. This roasted material is then leached in water with stirring at 200-300 rpm at 80℃ for 2 h, with a solid-liquid ratio (g / mL) of 1:5. After leaching, solid-liquid separation is performed to obtain an indium-zinc-iron filtrate. Zinc powder is then added to the indium-zinc-iron filtrate for Fe... 3+ The reduction reaction, the molar ratio of iron content in zinc powder to zinc powder-displaced slag is 2, and the Fe in the filtrate is... 3+The reaction was stopped and filtered after the ion concentration decreased to below 0.1 g / L, yielding a filtrate. The filtrate was collected and subjected to centrifugal extraction under the following conditions: extractant was P2O4, diluent was sulfonated kerosene, extractant concentration was 25%, extraction pH was 1.0, flow ratio (O / A) was 1:5, centrifugation speed was 5000 rpm, and the number of centrifugal extraction stages was 3, yielding an indium-loaded organic phase and raffinate. The raffinate was de-ironized to obtain a zinc-rich solution, which could be returned to the main process for zinc recovery. The indium-loaded organic phase was centrifuged and back-extracted to obtain an indium-containing back-extractant. The back-extractant was 3 mol / L hydrochloric acid solution, flow ratio (O / A) was 5:1, centrifugation speed was 5000 rpm, and the number of back-extracting stages was 3. The indium-containing back-extractant was replaced with a zinc plate to obtain sponge indium. The sponge indium was then alkali-fused and cast into ingots to obtain indium ingots.

[0064] The indium recovery rate was calculated to be 98.3%.

[0065] Comparative Example 1

[0066] The mass percentages of the components in the high-speed iron indium-zinc calcined ore from a zinc smelter in Guangxi are: Zn 54.4%, Fe 15.52%, In 0.093%. During the indium recovery process, zinc powder replacement slag was obtained. The zinc powder replacement slag is the slag produced after zinc powder replacement in the hydrometallurgical process of high-speed iron indium-zinc calcined ore. The mass percentages of the valuable components are: indium 0.01-3%, zinc 2-25%, iron 1-10%, silicon dioxide 3-15%, arsenic 0.2-3%, and cadmium 0.2-1%.

[0067] First, 1 kg of zinc powder replacement slag is finely ground to a particle size of -200 mesh to -400 mesh. The slag is then mixed with concentrated sulfuric acid at a mass ratio of 1:0.7 and placed in a muffle furnace. The mixture is then roasted at 250℃ for 2 hours to obtain the roasted material. The roasted material is then leached in water with stirring at 200-300 rpm at 80℃ for 2 hours, with a solid-liquid ratio (g / mL) of 1:5. After leaching, solid-liquid separation is performed to obtain an indium-zinc-iron filtrate. Zinc powder is then added to the indium-zinc-iron filtrate for Fe... 3+ The reduction reaction, the molar ratio of iron content in zinc powder to zinc powder-displaced slag is 2, and the Fe in the filtrate is... 3+The reaction was stopped and filtered after the ion concentration decreased to below 0.1 g / L, yielding a filtrate. The filtrate was collected and subjected to centrifugal extraction under the following conditions: extractant was P2O4, diluent was sulfonated kerosene, extractant concentration was 25%, extraction pH was 1.0, flow ratio (O / A) was 1:5, centrifugation speed was 5000 rpm, and the number of centrifugal extraction stages was 3, yielding an indium-loaded organic phase and raffinate. The raffinate was de-ironized to obtain a zinc-rich solution, which could be returned to the main process for zinc recovery. The indium-loaded organic phase was centrifuged and back-extracted to obtain an indium-containing back-extractant. The back-extractant was 3 mol / L hydrochloric acid solution, flow ratio (O / A) was 5:1, centrifugation speed was 5000 rpm, and the number of back-extracting stages was 3. The indium-containing back-extractant was replaced with a zinc plate to obtain sponge indium. The sponge indium was then alkali-fused and cast into ingots to obtain indium ingots.

[0068] The indium recovery rate was calculated to be 91.2%.

[0069] In the experimental results of Example 4 and Comparative Example 1, the roasting processes were different, but other conditions were the same. It can be seen that Example 4, using sulfation-stage roasting, achieved an indium recovery rate of 98.3%, while Comparative Example 1, without staged roasting, had an indium recovery rate of only 91.2%. This indicates that sulfation-stage roasting can effectively improve the indium recovery rate.

[0070] This invention provides a method for recovering indium from zinc powder replacement slag. Through sulfation and staged roasting of the zinc powder replacement slag, and with optimized processes, after steps including stirring leaching, reduction, separation extraction-back-extraction, the indium leaching rate can reach over 95%. Staged roasting enhances the decomposition effect of sulfuric acid on the zinc replacement slag, improving the utilization rate of the zinc powder replacement slag and the subsequent indium leaching rate.

[0071] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0072] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0073] The above provides a detailed description of a method for recovering indium from zinc powder replacement slag provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for recovering indium from zinc powder displacement slag, characterized in that, The method includes: The zinc powder replacement slag is crushed to a particle size of 200 to 400 mesh, mixed with concentrated sulfuric acid, and calcined at a temperature of 150 to 400°C for 0.5 to 4 hours to obtain the calcined material; the mass ratio of the zinc powder replacement slag to concentrated sulfuric acid is 1:0.1 to 1. Water is added to the calcined material, and the mixture is stirred and leached at a temperature of 25–90°C for 0.5–4 h. The mixture is then filtered to obtain an indium-zinc-iron filtrate. The solid-liquid ratio of the calcined material to water is 1:3–10. A reducing agent is added to the indium-zinc-iron filtrate to make Fe 3+ Reduced to Fe 2+ After the reaction, the sample was filtered to obtain Fe. 3+ Filtrate with a concentration of less than 0.1 g / L; The filtrate is subjected to centrifugal extraction with an extractant and a diluent at a flow ratio of 1:3 to 7, a pH of 1.0, 2 to 4 extraction stages, and a centrifugation speed of 4000 to 7000 rpm, yielding an indium-loaded organic phase and raffinate. The mass ratio of the extractant to the diluent is 10 to 30% to 70 to 90%. The extractant is P2O4, and the diluent is sulfonated kerosene. A 3–5 mol / L hydrochloric acid solution was added to the indium-supported organic phase for centrifugal back-extraction. The flow ratio of the back-extraction was 3–7:1, the number of back-extraction stages was 2–4, and the centrifugation speed was 4000–6000 rpm, to obtain an indium-containing back-extraction solution. A zinc plate was added to the indium-containing back-extraction solution for displacement, followed by alkali melting and ingot casting to obtain an indium ingot. The roasting is a staged roasting, which includes: roasting at a temperature of 200-220℃ for 0.5-1.5 h, and then roasting at a temperature of 260-290℃ for 1.5-2 h.

2. The method according to claim 1, characterized in that, The mass ratio of the zinc powder replacement slag to concentrated sulfuric acid is 1:0.3 to 0.

7.

3. The method according to claim 1, characterized in that, The leaching temperature is 60–80°C, and the leaching time is 0.5–2 h; the solid-liquid ratio of the calcined material to water is 1:3–5.

4. The method according to claim 1, characterized in that, The stirring is mechanical stirring; the stirring speed is 200-300 rpm.

5. The method according to claim 1, characterized in that, The zinc powder replacement slag contains, by mass percentage, 0.01–3% indium, 2–20% zinc, 1–10% iron, 3–15% silicon dioxide, 0.2–3% arsenic, and 0.2–1% cadmium.

6. The method according to claim 1, characterized in that, The reducing agent is one or more of zinc powder, iron powder, and zinc sulfide concentrate; the molar ratio of the iron content of the reducing agent to the zinc powder replacement slag is 1.0 to 3.

6.

7. The method according to claim 1, characterized in that, The flow ratio of the centrifugal extraction is 1:5 to 7; the number of centrifugal extraction stages is 2 to 3; the centrifugation speed is 5000 to 7000 rpm; and the mass ratio of the extractant to the diluent is 15 to 25%: 75 to 85%.

8. The method according to claim 1, characterized in that, The flow ratio of the centrifugal back-extraction is 5 to 7:1; the number of stages of the centrifugal back-extraction is 2 to 3; and the centrifugation speed is 4000 to 5000 rpm.

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