A process for the extraction of bismuth from bismuth-containing pressure oxidation conversion leach residue

Abstract

This invention provides a method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue, belonging to the field of non-ferrous metal metallurgical technology. In this invention, dilute sulfuric acid is added as a leaching agent to bismuth sulfide concentrate for mixing and slurry preparation, while a surfactant is added to obtain a mixed slurry. Oxygen is then introduced to perform oxygen pressure conversion leaching on the mixed slurry, yielding bismuth-containing oxygen pressure conversion leaching residue. This residue is then mixed with an alkaline solution for alkaline conversion and solid-liquid separation, yielding a conversion solution and bismuth oxide residue. Finally, the bismuth oxide residue is mixed with an acidic solution for acidic bismuth extraction and solid-liquid separation, yielding a bismuth-rich leachate and bismuth extraction residue. This invention converts bismuth sulfide into easily acid-soluble bismuth oxide, increasing the flexibility of the hydrometallurgical system selection for low-grade bismuth sulfide concentrate and enabling selective extraction of bismuth at ambient temperature and pressure. Compared to direct chlorination leaching of bismuth sulfide concentrate, the bismuth-rich leachate has a lower concentration of impurity ions such as iron, requiring less purification and impurity removal pressure.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal metallurgy, and in particular to a method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue. Background Technology

[0002] In nature, bismuth mainly exists in the form of bismuthite (Bi₂S₃), and low-grade, complex bismuth sulfide concentrates are typically processed using hydrometallurgical processes. Bismuthite is difficult to dissolve directly; therefore, the mainstream hydrometallurgical bismuth refining process utilizes bismuth and chloride ions to form soluble BiCl₂. n 3-n The characteristics of the (n=4,5,6…) complexes involve leaching bismuth ore with high-concentration hydrochloric acid under heating and oxidizing conditions. Oxidants used include O2, FeCl3, Cl2, chlorates, and nitric acid. The acidic leachate produces sponge bismuth or bismuth oxychloride through iron powder displacement or neutralization hydrolysis, which is then sent to the pyrometallurgical bismuth refining process, or purified and purified before being electrowinning to produce metallic bismuth. While the acidic chloride system can achieve bismuth leaching, it also suffers from drawbacks such as severe equipment corrosion, large wastewater generation, and a harsh operating environment. In particular, iron from bismuth sulfide concentrate easily leachs into the solution and accumulates during production, making leaching difficult and hindering normal production operations.

[0003] Patent CN 110343873 A proposes a method for atmospheric pressure oxygen-enriched leaching of bismuth sulfide concentrate using a methanesulfonic acid system. The method is characterized by using an iron-containing methanesulfonic acid solution as the leaching agent and oxygen as the oxidant, achieving effective leaching of bismuth below 100℃. The sulfur element in the concentrate exists primarily as elemental sulfur in the slag. This method avoids the problems of severe equipment corrosion, large wastewater discharge, and poor operating environment associated with traditional acidic chloride salt systems, and overcomes the drawbacks of low-concentration SO2 pollution in traditional pyrometallurgical processes. However, it has shortcomings such as long leaching time (15-30 h), high bismuth content in the slag (3.4-5.8%), and difficulty in separating bismuth from iron in the leachate.

[0004] Patent CN 110629043 A proposes a bismuth extraction method based on the phase transformation of bismuth sulfide ore. The method is characterized by using an iron-containing methanesulfonic acid solution as a phase-transforming agent to convert bismuth sulfide into basic bismuth sulfate under pressure oxidation. The phase-transformed residue (basic bismuth sulfate residue) is then directly subjected to acid leaching treatment, achieving selective bismuth leaching. Compared to patent CN 110343873 A, this method significantly shortens the bismuth leaching time and reduces the purification burden on impurities such as iron, lead, and silicon in the leaching solution. However, the problem of difficult removal of sulfate ions from the leaching solution and high bismuth content in the residue still exists.

[0005] Based on the shortcomings of the above-mentioned hydrometallurgical process for low-grade bismuth sulfide concentrate, this invention obtains bismuth-containing oxygen pressure conversion leaching residue by low-temperature oxygen pressure conversion leaching of bismuth sulfide concentrate, and then converts the bismuth-containing oxygen pressure conversion leaching residue into easily acid-soluble bismuth oxide, thereby increasing the flexibility of the hydrometallurgical system for bismuth sulfide concentrate and improving the selectivity of bismuth leaching. Summary of the Invention

[0006] The purpose of this invention is to provide a method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue, in order to solve the problems of severe equipment corrosion, large wastewater generation, harsh operating environment, low bismuth leaching selectivity, and difficulty in leaching solution filtration caused by the accumulation of iron in the leaching solution due to the circulation of iron in the leaching solution in the existing hydrometallurgical process for bismuth sulfide concentrate.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue, comprising the following steps: (1) Add dilute sulfuric acid leaching agent to bismuth sulfide concentrate for mixing and slurry preparation, and at the same time add surfactant to obtain mixed slurry; The bismuth sulfide concentrate is 97% bismuth sulfide concentrate with a particle size of less than 200 mesh. (2) Introduce oxygen to perform oxygen pressure conversion leaching on the mixed slurry to obtain bismuth-containing oxygen pressure conversion leaching residue; (3) Mix the bismuth-containing oxygen pressure conversion leaching residue with an alkaline solution for alkaline conversion and solid-liquid separation to obtain conversion liquid and bismuth oxide residue; (4) Mix the bismuth oxide slag and acidic solution to carry out acidic bismuth extraction and solid-liquid separation to obtain bismuth-rich leachate and bismuth extraction slag.

[0008] Preferably, in step (1), the concentration of the dilute sulfuric acid leaching agent is 60~100g / L; and the solid-liquid ratio during mixing and slurry preparation is 1kg:4~8L.

[0009] Preferably, in step (1), the surfactant comprises calcium lignosulfonate, sodium lignosulfonate or sodium dodecyl sulfate; the amount of surfactant added is 0.2 to 0.8% of the mass of bismuth sulfide concentrate.

[0010] Preferably, in step (2), the oxygen pressure conversion leaching temperature is 110~140℃, the oxygen partial pressure is 1.0~2.0MPa, the stirring rate is 700~1200rpm, and the time is 90~240min.

[0011] Preferably, in step (3), the alkaline solution comprises one or more of sodium hydroxide solution, ammonia water and sodium carbonate solution; the concentration of free alkali in the alkaline solution is 3.0~5.0 mol / L.

[0012] Preferably, in step (3), the solid-liquid ratio of the bismuth-containing oxygen pressure conversion leaching residue and the alkaline solution is 1 kg: 3~8 L.

[0013] Preferably, in step (3), the temperature of the alkaline transformation is 20~50℃, the stirring rate is 300~700rpm, and the reaction time is 10~60min.

[0014] Preferably, in step (4), the acidic solution includes one or more of methanesulfonic acid solution, hydrochloric acid solution and fluorosilicic acid solution; the concentration of free acid in the acidic solution is 2.0~4.5 mol / L; and the solid-liquid ratio of the bismuth oxide slag and the acidic solution is 1 kg: 3~8 L.

[0015] Preferably, in step (4), the temperature of the acidic bismuth extraction is 20~50℃, the stirring rate is 300~700rpm, and the reaction time is 10~60min.

[0016] Preferably, in step (4), the bismuth-rich leachate is sent to the bismuth recovery system; and the bismuth extraction residue is sent to the sulfur recovery system.

[0017] This invention draws upon the observation in elemental geochemistry that bismuthite combines more readily with oxygen than sphalerite. Based on practical and theoretical research in the pressure leaching production of sphalerite in the metallurgical field, it proposes a method to convert bismuth sulfide into sparingly soluble bismuth sulfate (which will further hydrolyze into sparingly soluble basic bismuth sulfate) and elemental sulfur through low-temperature oxygen pressure conversion leaching in a sulfuric acid system, and to convert pyrite into readily soluble ferric sulfate, thus achieving the morphological transformation of bismuthite and the initial separation of bismuth and iron. Furthermore, it creatively proposes to react the basic bismuth sulfate in the oxygen pressure conversion leaching residue with an alkaline solution at room temperature and pressure, transforming it into bismuth oxide, which is easily dissolved in acid at room temperature and pressure. This creates conditions for bismuth extraction using a non-chloride salt system; in addition, the mild acidic bismuth extraction environment also reduces the leaching of impurities such as iron.

[0018] The beneficial effects of this invention are: (1) The present invention converts bismuth sulfide into bismuth oxide, which is easily soluble in acid, thereby increasing the flexibility of the selection of hydrometallurgical system for bismuth sulfide concentrate.

[0019] (2) The present invention achieves selective dissolution of bismuth at room temperature and pressure. Compared with direct chlorination leaching of bismuth sulfide concentrate, the concentration of iron ions in the bismuth-rich solution is lower and the purification and impurity removal pressure is lower.

[0020] (3) Compared with the bismuth concentrate leaching process of the methanesulfonic acid system, the present invention has a higher bismuth leaching rate and a lower bismuth content in the residue. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the present invention for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue; Figure 2 The images show the XRD patterns of the bismuth-containing oxygen pressure conversion leaching residue, bismuth oxide residue, and bismuth extraction residue in Example 1, where a is the bismuth-containing oxygen pressure conversion leaching residue, b is the bismuth oxide residue, and c is the bismuth extraction residue. Detailed Implementation

[0022] This invention provides a method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue, comprising the following steps: (1) Add dilute sulfuric acid leaching agent to bismuth sulfide concentrate for mixing and slurry preparation, and at the same time add surfactant to obtain mixed slurry; The bismuth sulfide concentrate is 97% bismuth sulfide concentrate with a particle size of less than 200 mesh. (2) Introduce oxygen to perform oxygen pressure conversion leaching on the mixed slurry to obtain bismuth-containing oxygen pressure conversion leaching residue; (3) Mix the bismuth-containing oxygen pressure conversion leaching residue with an alkaline solution for alkaline conversion and solid-liquid separation to obtain conversion liquid and bismuth oxide residue; (4) Mix the bismuth oxide slag and acidic solution to carry out acidic bismuth extraction and solid-liquid separation to obtain bismuth-rich leachate and bismuth extraction slag.

[0023] In this invention, in step (1), the concentration of the dilute sulfuric acid leaching agent is 60~100g / L, preferably 70~90g / L, and more preferably 80g / L; the solid-liquid ratio during mixing and slurry preparation is 1kg:4~8L, preferably 1kg:4~6L, and more preferably 1kg:5L.

[0024] In this invention, in step (1), the surfactant comprises calcium lignosulfonate, sodium lignosulfonate or sodium dodecyl sulfate, preferably calcium lignosulfonate; the amount of surfactant added accounts for 0.2 to 0.8% of the mass of bismuth sulfide concentrate, preferably 0.4 to 0.6%, and more preferably 0.5%.

[0025] In this invention, in step (2), the oxygen pressure conversion leaching temperature is 110~140℃, preferably 115~130℃, more preferably 125℃, the oxygen partial pressure is 1.0~2.0MPa, preferably 1.2~1.8MPa, more preferably 1.4~1.6MPa, and the time is 90~240min, preferably 120~180min, more preferably 150min.

[0026] In this invention, the alkaline solution comprises one or two of sodium hydroxide solution, ammonia solution, and sodium carbonate solution; the concentration of free alkali in the alkaline solution is 3.0~5.0 mol / L, preferably 3.0 mol / L, 4.0 mol / L, or 4.5 mol / L.

[0027] In this invention, in step (3), the solid-liquid ratio of the bismuth-containing oxygen pressure conversion leaching residue and the alkaline solution is 1kg:3~8L, preferably 1kg:3L, 1kg:4L, 1kg:5L, or 1kg:6L.

[0028] In this invention, in step (3), the temperature of the alkaline transformation is 20~50℃, preferably 25℃, 30℃, 35℃, 40℃, or 45℃, and the time is 10~60min, preferably 20min, 30min, 40min, or 50min.

[0029] In this invention, in step (4), the acidic solution comprises one or more of methanesulfonic acid solution, hydrochloric acid solution and fluorosilicic acid solution; the concentration of free acid in the acidic solution is 2.0~4.5 mol / L, preferably 2.25 mol / L, 3.0 mol / L, 3.5 mol / L, or 4.0 mol / L; the solid-liquid ratio of the bismuth oxide slag and the acidic solution is 1 kg:3~8 L, preferably 1 kg:3 L, 1 kg:4 L, 1 kg:5 L, or 1 kg:6 L.

[0030] In this invention, in step (4), the temperature of acidic bismuth extraction is 20~50℃, preferably 25℃, 30℃, 35℃, 40℃, or 45℃, and the time is 10~60min, preferably 20min, 30min, 40min, or 50min.

[0031] In this invention, in step (4), the bismuth-rich leachate is sent to the bismuth recovery system; the bismuth extraction residue is sent to the sulfur recovery system.

[0032] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0033] Example 1

[0034] Low-grade bismuth sulfide concentrate was ground to ensure that 97% of the particles were less than 200 mesh. Then, a dilute sulfuric acid solution with a concentration of 80 g / L was added at a solid-liquid ratio of 1 kg: 5 L to mix and prepare the slurry. 0.5% calcium lignosulfonate was added and mixed evenly to obtain a mixed slurry. The mixed slurry was transferred to a reactor, which was sealed. The stirring device was turned on and the stirring speed was controlled at 1000 rpm. Oxygen was introduced and the oxygen partial pressure was controlled at 1.4 MPa. The temperature was raised to 125°C and oxygen pressure conversion leaching was performed at this temperature for 150 min. After the leaching was completed, the temperature and pressure in the reactor were lowered to normal and the solid and liquid were separated to obtain bismuth-containing oxygen pressure conversion leaching residue. The composition of the low-grade bismuth sulfide concentrate and the bismuth-containing oxygen pressure conversion leaching residue were analyzed, and the results are shown in Table 1.

[0035]

[0036] Weigh 20.00 g of the bismuth-containing oxygen pressure conversion leaching residue and mix it with a 4 mol / L sodium hydroxide solution at a solid-liquid ratio of 1 kg: 5 L. Perform alkaline conversion for 50 min at 30 °C and a stirring speed of 600 rpm, followed by solid-liquid separation to obtain conversion solution and bismuth oxide residue. Dry the bismuth oxide residue at 60 °C and then mix it with a 3 mol / L methanesulfonic acid solution at a solid-liquid ratio of 1 kg: 5 L. Leach the residue at 30 °C and a stirring speed of 300 rpm for 40 min to obtain bismuth-rich solution and bismuth extraction residue. The bismuth leaching rate is 98.45%, the iron content in the bismuth-rich solution is 0.11 g / L, and the bismuth content in the bismuth extraction residue is 2.15%.

[0037] Phase analysis was performed on the bismuth-containing oxygen pressure conversion leaching residue, bismuth oxide residue, and bismuth extraction residue from Example 1. The results are as follows: Figure 2 As shown, it can be seen that low-grade bismuth sulfide concentrate is transformed into (Bi2O(OH)2)SO4 through oxygen pressure conversion leaching, and then into Bi2O3 after alkaline conversion. After acidic bismuth extraction, the bismuth oxide dissolves, and its diffraction peaks disappear.

[0038] Example 2

[0039] Using the bismuth-containing oxygen pressure conversion leaching residue from Example 1, 20.00 g of the bismuth-containing oxygen pressure conversion leaching residue was weighed and mixed with 5 mol / L ammonia water at a solid-liquid ratio of 1 kg: 8 L. The mixture was subjected to alkaline conversion for 20 min at 40°C and a stirring speed of 700 rpm, followed by solid-liquid separation to obtain conversion solution and bismuth oxide residue. The bismuth oxide residue was dried at 60°C and then mixed with 2.25 mol / L methanesulfonic acid solution at a solid-liquid ratio of 1 kg: 7 L. The mixture was leached for 20 min at 50°C and a stirring speed of 600 rpm to obtain bismuth-rich solution and bismuth extraction residue. The bismuth leaching rate was 98.87%, the iron content in the bismuth-rich solution was 0.09 g / L, and the bismuth content in the bismuth extraction residue was 1.98%.

[0040] Example 3

[0041] Using the bismuth-containing oxygen pressure conversion leaching residue from Example 1, 20.00 g of the bismuth-containing oxygen pressure conversion leaching residue was weighed and mixed with a 4 mol / L free alkali solution of sodium hydroxide and sodium carbonate at a solid-liquid ratio of 1 kg:3 L. The mixture was subjected to alkaline conversion for 50 min at 25°C and a stirring speed of 300 rpm, followed by solid-liquid separation to obtain conversion solution and bismuth oxide residue. The bismuth oxide residue was dried at 60°C and then mixed with a 4.5 mol / L fluorosilicic acid solution at a solid-liquid ratio of 1 kg:4 L. The mixture was leached for 30 min at 35°C and a stirring speed of 500 rpm to obtain bismuth-rich solution and bismuth extraction residue. The bismuth leaching rate was 97.86%, the iron content in the bismuth-rich solution was 0.14 g / L, and the bismuth content in the bismuth extraction residue was 2.46%.

[0042] Example 4

[0043] Using the bismuth-containing oxygen pressure conversion leaching residue from Example 1, 20.00 g of the bismuth-containing oxygen pressure conversion leaching residue was weighed and mixed with a 3 mol / L sodium hydroxide solution at a solid-liquid ratio of 1 kg:4 L. The mixture was subjected to alkaline conversion at 45°C and a stirring speed of 500 rpm for 20 min, followed by solid-liquid separation to obtain a conversion solution and bismuth oxide residue. The bismuth oxide residue was dried at 60°C and then mixed with a 3.5 mol / L hydrochloric acid solution at a solid-liquid ratio of 1 kg:3 L. The mixture was leached at 50°C and a stirring speed of 700 rpm for 20 min to obtain a bismuth-rich solution and bismuth extraction residue. The bismuth leaching rate was 98.36%, the iron content in the bismuth-rich solution was 0.19 g / L, and the bismuth content in the bismuth extraction residue was 2.23%.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue, characterized in that, Includes the following steps: (1) Add dilute sulfuric acid leaching agent to bismuth sulfide concentrate for mixing and slurry preparation, and at the same time add surfactant to obtain mixed slurry; The bismuth sulfide concentrate is 97% bismuth sulfide concentrate with a particle size of less than 200 mesh. (2) Introduce oxygen to perform oxygen pressure conversion leaching on the mixed slurry to obtain bismuth-containing oxygen pressure conversion leaching residue; (3) Mix the bismuth-containing oxygen pressure conversion leaching residue with an alkaline solution for alkaline conversion and solid-liquid separation to obtain conversion liquid and bismuth oxide residue; (4) Mix the bismuth oxide slag and acidic solution to carry out acidic bismuth extraction and solid-liquid separation to obtain bismuth-rich leachate and bismuth extraction slag.

2. The method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue according to claim 1, characterized in that, In step (1), the concentration of the dilute sulfuric acid leaching agent is 60~100g / L; the solid-liquid ratio during mixing and slurry preparation is 1kg:4~8L.

3. The method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue according to claim 2, characterized in that, In step (1), the surfactant comprises calcium lignosulfonate, sodium lignosulfonate or sodium dodecyl sulfate; the amount of surfactant added is 0.2 to 0.8% of the mass of bismuth sulfide concentrate.

4. The method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue according to any one of claims 1 to 3, characterized in that, In step (2), the oxygen pressure conversion leaching temperature is 110~140℃, the oxygen partial pressure is 1.0~2.0MPa, the stirring rate is 700~1200rpm, and the time is 90~240min.

5. The method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue according to claim 4, characterized in that, In step (3), the alkaline solution comprises one or more of sodium hydroxide solution, ammonia water and sodium carbonate solution; the concentration of free alkali in the alkaline solution is 3.0~5.0 mol / L.

6. The method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue according to claim 2, 3, or 5, characterized in that, In step (3), the solid-liquid ratio of the bismuth-containing oxygen pressure conversion leaching residue and the alkaline solution is 1 kg: 3~8 L.

7. The method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue according to claim 6, characterized in that, In step (3), the temperature of the alkaline transformation is 20~50℃, the stirring rate is 300~700rpm, and the time is 10~60min.

8. The method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue according to claim 5 or 7, characterized in that, In step (4), the acidic solution includes one or more of methanesulfonic acid solution, hydrochloric acid solution and fluorosilicic acid solution; the concentration of free acid in the acidic solution is 2.0~4.5 mol / L; the solid-liquid ratio of the bismuth oxide slag and the acidic solution is 1 kg: 3~8 L.

9. The method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue according to claim 8, characterized in that, In step (4), the acidic bismuth extraction temperature is 20~50℃, the stirring rate is 300~700rpm, and the reaction time is 10~60min.

10. The method for extracting bismuth from bismuth-containing oxygen pressure conversion leaching residue according to claim 9, characterized in that, In step (4), the bismuth-rich leachate is sent to the bismuth recovery system; the bismuth extraction residue is sent to the sulfur recovery system.

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