Method for removing selenium and sulfur in precious metal acid leaching residues
By mixing the noble metal acid leaching residue and sulfuric acid and baking treatment at high temperature and high oxidation atmosphere, the problem of high selenium and sulfur content in the noble metal acid leaching residue is solved, and efficient recycling and purification of precious metals is achieved.
Patent Information
- Application Number
- CN202510565051.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-30
- Publication Date
- 2025-07-25
AI Technical Summary
In the existing methods, the high content of selenium and sulfur in the noble metal acid leach slags affects the recovery rate of precious metals and product quality.
By mixing the acid leach slag with sulfuric acid in a certain proportion, it is layered and sulfated and calcined in a high-temperature and high-oxidation atmosphere, the heating rate and temperature are controlled, and selenium and sulfur are removed step by step, and then water-soaked treatment is carried out to achieve separation of noble and low-cost metals.
Effectively reduce the selenium and sulfur content in the acid leach slag, improve the recovery and grade of precious metals, and achieve efficient enrichment and purification of precious metals.
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Figure CN120366578A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of nonferrous metallurgy and precious metal impurity removal, and particularly relates to a method for removing selenium and sulfur from precious metal acid leaching residue. Background Art
[0002] Because of their good physical and chemical properties, precious metals are widely used in industrial production and jewelry processing, especially in defense, chemical industry, petroleum refining, and electronics industries, where they are indispensable and important raw materials. In addition, precious metals play a very important role in the jewelry manufacturing industry. Precious metals have the advantages of small size, high value, stable chemical properties, and unchangeable quality and appearance, which makes precious metals such as gold and silver very useful in economic and social life.
[0003] The purification process can obtain high-grade and high-purity precious metal products by refining and purifying the precious metal concentrates. However, this process is also accompanied by the generation of waste liquid and waste residue. After testing, it was found that some waste liquid and waste residue contain a certain amount of precious metals, and the content is considerable and has recoverable value. Therefore, the chemical precipitation method can be used to treat these waste liquids and waste residues to achieve the concentration and enrichment of precious metals in the waste liquid, and finally the precipitate is mixed with the waste residue to form acid leaching residue. In the early stage, the precious metals in the acid leaching residue were extracted by wet method, and it was found that the selenium and sulfur content was high, which seriously affected the recovery rate of precious metals and product quality. Therefore, it is necessary to develop a method for removing selenium and sulfur from precious metal acid leaching residue. Summary of the invention
[0004] The purpose of the present invention is to provide a method for removing selenium and sulfur from precious metal acid leaching residues, so as to solve the problems of poor precious metal recovery rate and product quality in the existing methods.
[0005] The technical solution of the present invention is: a method for removing selenium and sulfur from precious metal acid leaching residue, comprising the following steps: Step 1: Evenly mix the acid leaching residue and sulfuric acid reagent at a solid-liquid ratio of 1:1-3, and spread the evenly mixed acid leaching residue flat and stacked in layers; Step 2: The acid leaching residues that are laid flat and stacked in layers are heated up, and the heating rate is maintained at 30-50°C / h from room temperature to 350°C. When the temperature rises to 350°C, the heating rate is maintained at 70-100°C / h to 650°C. When the temperature rises to 650°C, the temperature is naturally lowered after the constant temperature is maintained for 3 hours; Step 3: adding sulfuric acid to the acid leaching residue after natural cooling and performing sulfation roasting to obtain roasting ash, and then leaching the roasting ash in water to obtain a base metal solution and a precious metal enriched concentrate; Step 4: Purify the precious metal-enriched concentrate to obtain platinum group precious metals.
[0006] As a further improvement of the present invention, in step one, when stacking in layers, the thickness of the materials in each layer is uniform, the stacking height does not exceed 5 layers, and the layer spacing is maintained at 20 - 50 mm.
[0007] As a further improvement of the present invention, in step three, when performing sulfation roasting, it is carried out in a high - oxidation roasting atmosphere at a temperature of 350 - 650 °C and a material - acid ratio of 1:1 - 3.
[0008] The beneficial effects of the present invention are as follows: The acid - leaching residue contains precious metals such as gold, palladium, and platinum. In addition, it mainly contains impurities such as selenium, sulfur, zinc, iron, and silicon dioxide. When the acid - leaching residue is directly baked without adding acid and the temperature is raised to 650 °C and kept constant for 3 hours, although the content of selenium in the acid - leaching residue is reduced compared with the untreated acid - leaching residue (Se is 30.5%), there is still a considerable amount of selenium remaining in the acid - leaching residue. After the temperature - raising and constant - temperature treatment, the Se in the acid - leaching residue is 24.26%, showing a relative decrease. To better reduce the selenium and sulfur elements in the acid - leaching residue, it is necessary to first perform acid leaching and then oxidation roasting. Therefore, the liquid - to - material ratio is maintained at 1:1 - 3, and the furnace is in a high - temperature and high - oxidation atmosphere. By further strictly controlling the temperature change and through sulfation roasting, the selenium and sulfur in the acid - leaching residue are removed step by step to achieve the ideal situation.
[0009] Through sulfuric acid leaching, the materials and sulfuric acid are mixed evenly at a ratio of 1:1 - 3 and sulfation roasting is carried out in a high - temperature and high - oxidation atmosphere in the furnace. This can separate selenium, sulfur from other precious metals, not only enriching the precious metals but also effectively removing the impurity elements therein, changing the difficult problem of removing selenium and sulfur from the acid - leaching residue when no acid is added. This method of sulfation roasting with acid addition to the materials not only has a high efficiency of removing selenium and sulfur but also is beneficial to improving the enrichment rate and grade of precious metals in the ash residue, thus achieving the goal of high recovery rate of precious metals during the purification treatment of the ash residue.
[0010] The acid - leaching residue is mixed with sulfuric acid and evenly spread out in a layered stack to achieve uniform heating of the materials, so that the acid - leaching residue burns evenly and completely; by reasonably controlling and setting the temperature - raising endpoint value and the temperature - raising speed through experiments, the mixed materials are heated and baked at different temperature - raising speeds and temperatures, enabling the selenium and sulfur in the precious - metal slag to be effectively oxidized and volatilized, and the precious metals are enriched in the ash residue, further improving the subsequent treatment effect.
[0011] In a high - temperature and high - oxidation atmosphere, sulfation roasting is carried out on the acid - leached material with sulfuric acid added, so that selenium and sulfur are removed step by step in the form of SeO2 and SO2 gases respectively, and the alkali metals are converted into sulfates. By performing water - leaching treatment on the roasted slag, the separation of precious and base metals can be achieved, obtaining a base - metal solution and precious - metal enriched concentrate minerals, and the precious metals are further enriched in the concentrate slag, thus achieving the effect of impurity removal. Description of the Drawings
[0012] Figure 1 This is a schematic process flow diagram of the present invention. Detailed implementation manners
[0013] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments. The embodiments herein are only used to explain the present invention and are not used to restrict or limit the present invention.
[0014] In other words, the present invention covers any substitutions, modifications, equivalent methods and solutions made within the essence and scope of the present invention defined by the claims. Further, it is made easier for other researchers to understand through embodiments.
[0015] Embodiment 1 Step 1: Mix the acid leaching residue and sulfuric acid reagent in a solid-liquid ratio of 1:1, stir evenly, spread the evenly mixed acid leaching residue on a tray and stack it in layers; the thickness of each layer of material is uniform, the stacking height is 5 layers, and the layer spacing is maintained at 20 mm; Step 2: Heat up the acid leaching residue spread and stacked in layers, so that it maintains a heating rate of 30 °C / h from room temperature to 350 °C. When the temperature rises to 350 °C, maintain a heating rate of 70 °C / h to heat up to 650 °C. When the temperature rises to 650 °C, perform natural cooling after maintaining a constant temperature for 3 hours; Step 3: Carry out high-temperature oxidation roasting in an atmosphere with a material-acid ratio of 1:1 at a temperature of 350 °C on the acid leaching residue after natural cooling, add sulfuric acid for acid leaching and carry out sulfation roasting to obtain roasted ash residue, and perform water leaching on the roasted ash residue to obtain a base metal solution and a precious metal-enriched concentrate; Step 4: Purify the precious metal-enriched concentrate to obtain platinum group precious metals.
[0016] Under the process conditions of Embodiment 1, the proportions of selenium and sulfur in the roasted ash residue are 12.08% and 13.27% respectively, and the enrichment rates of gold, platinum and palladium are 173.22%, 188.16% and 174.35% respectively. After water leaching and filtering to separate base and precious metals from the roasted ash residue, the enrichment rates of gold, platinum and palladium are increased to 203.18%, 233.15% and 256.47% respectively. High-grade gold, platinum and palladium products are obtained by purifying the water leaching residue, and the recovery rates of gold, platinum and palladium are 92.15%, 94.63% and 92.37% respectively.
[0017] Embodiment 2 Step 1: Mix the acid leaching residue and sulfuric acid reagent in a solid-liquid ratio of 1:2, stir evenly, spread the evenly mixed acid leaching residue on a tray and stack it in layers; the thickness of each layer of material is uniform, the stacking height is 4 layers, and the layer spacing is maintained at 35 mm; Step 2: Heat up the acid-leached residues that are tiled and stacked in layers, and keep the heating rate at 40 °C / h from room temperature to 350 °C. When the temperature rises to 350 °C, keep the heating rate at 85 °C / h and heat up to 650 °C. When the temperature rises to 650 °C, let it cool down naturally after maintaining a constant temperature for 3 hours. Step 3: Carry out high-temperature oxidation roasting on the acid-leached residues after natural cooling in an atmosphere with a temperature of 500 °C and a material-acid ratio of 1:2, add sulfuric acid for acid leaching and carry out sulfation roasting to obtain roasted ash residues. Water-leach the roasted ash residues to obtain base metal solutions and precious metal-enriched fine minerals. Step 4: Purify the precious metal-enriched fine minerals to obtain platinum group precious metals.
[0018] Under the process conditions of Example 2, the proportions of selenium and sulfur in the roasted ash residues are 10.84% and 11.21% respectively, and the enrichment rates of gold, platinum, and palladium are 189.33%, 197.58%, and 184.26% respectively. After water-leaching and filtering the roasted ash residues to separate base and precious metals, the enrichment rates of gold, platinum, and palladium are increased to 254.78%, 295.28%, and 277.15% respectively. High-grade gold, platinum, and palladium products are obtained by purifying the water-leached residues, and the recovery rates of gold, platinum, and palladium are 93.48%, 95.41%, and 94.25% respectively.
[0019] Example 3 Step 1: Mix the acid-leached residues and sulfuric acid reagent evenly according to a solid-liquid ratio of 1:3, and tile the evenly mixed acid-leached residues on a tray and stack them in layers; the thickness of each layer of material is uniform, the stacking height is 5 layers, and the layer spacing is kept at 50 mm. Step 2: Heat up the acid-leached residues that are tiled and stacked in layers, and keep the heating rate at 50 °C / h from room temperature to 350 °C. When the temperature rises to 350 °C, keep the heating rate at 100 °C / h and heat up to 650 °C. When the temperature rises to 650 °C, let it cool down naturally after maintaining a constant temperature for 3 hours. Step 3: Carry out high-temperature oxidation roasting on the acid-leached residues after natural cooling in an atmosphere with a temperature of 650 °C and a material-acid ratio of 1:3, add sulfuric acid for acid leaching and carry out sulfation roasting to obtain roasted ash residues. Water-leach the roasted ash residues to obtain base metal solutions and precious metal-enriched fine minerals. Step 4: Purify the precious metal-enriched fine minerals to obtain platinum group precious metals.
[0020] Under the process conditions of Example 3, the proportions of selenium and sulfur in the calcined slag are 4.35% and 7.09% respectively, and the enrichment rates of gold, platinum and palladium are 235.48%, 254.12% and 237.39% respectively. After the calcined slag is subjected to water leaching and filtration to separate noble and base metals, the enrichment rates of gold, platinum and palladium are increased to 308.49%, 397.45% and 417.26% respectively. High-grade gold, platinum and palladium products are obtained by purifying the water leaching residue, and the recovery rates of gold, platinum and palladium are 97.39%, 99.18% and 97.25% respectively.
[0021] This production method first stirs and pre-treats the acid leaching residue and sulfuric acid reagent; then bakes the mixture at different heating rates and temperatures to oxidize and volatilize selenium and sulfur in the noble metal slag, and the noble metals are enriched in the slag; then the calcined slag generated in a high-temperature and high-oxidizing atmosphere is subjected to water leaching to separate noble and base metals, obtaining a base metal solution and a noble metal-enriched concentrate; finally, the noble metal-enriched concentrate is purified to obtain platinum group noble metals.
[0022] From the data comparison of Examples 1-3, it can be seen that this production method effectively reduces the contents of selenium and sulfur in the acid leaching residue and further enriches the noble metals by reasonably controlling the pretreatment method, roasting process, acid leaching method and subsequent treatment of the product. This makes the grades of Au, Pd and Pt in the material increase, there is no heavy metal pollution, it has a wide range of application fields and a high noble metal recovery rate, and it is suitable for industrial production.
Claims
1. A method for removing selenium and sulfur from precious metal acid leaching residues, characterized in that: It includes the following steps: Step 1: Mix the acid leaching residue and sulfuric acid reagent evenly according to a solid-liquid ratio of 1:1 - 3, and lay the evenly mixed acid leaching residue flat and stack it in layers; Step 2: Heat up the acid leaching residue that is laid flat and stacked in layers, so that it maintains a heating rate of 30 - 50 °C / h when the temperature is from room temperature to 350 °C. When the temperature rises to 350 °C, maintain a heating rate of 70 - 100 °C / h to heat up to 650 °C. When the temperature rises to 650 °C, conduct natural cooling after maintaining a constant temperature for up to 3 hours; Step 3: Acid leach the acid leaching residue after natural cooling with sulfuric acid and conduct sulfation roasting to obtain roasted ash residue. Leach the roasted ash residue with water to obtain a base metal solution and a precious metal enriched concentrate; Step 4: Purify the precious metal enriched concentrate to obtain platinum group precious metals.
2. The method for removing selenium and sulfur from noble metal acid leaching residues according to claim 1, characterized in that: In Step 1, when stacking in layers, the thickness of each layer of material is uniform, the stacking height does not exceed 5 layers, and the layer spacing is maintained at 20 - 50 mm.
3. A method for removing selenium and sulfur from precious metal acid leaching residues according to claim 1, characterized in that: In Step 3, when conducting sulfation roasting, it is carried out in a high oxidation roasting atmosphere at a temperature of 350 - 650 °C and a material-acid ratio of 1:1 - 3.