Method for preparing high-purity metal bismuth from methanesulfonic acid system bismuth sulfide concentrate

Abstract

The invention belongs to the technical field of hydrometallurgy, and particularly discloses a method for preparing high-purity metal bismuth from methanesulfonic acid system bismuth sulfide concentrate. The method comprises the following steps: weighing bismuth sulfide concentrate powder and a surfactant, putting the bismuth sulfide concentrate powder and the surfactant into a methanesulfonic acid solution, mixing and size mixing, pouring the mixture into a closed reaction kettle, carrying out autocatalytic oxygen pressure leaching reaction and solid-liquid separation, and collecting a leaching solution; adding a reducing agent to obtain a reducing solution; adding a saponified extracting agent, and separating to obtain a bismuth-loaded organic phase; adding a methanesulfonic acid solution as a stripping agent, and separating to obtain a bismuth stripping solution; adding a neutralizer, reacting, separating, and discarding supernatant to obtain bismuth hydrolysis residues; dissolving the bismuth methanesulfonate in a methanesulfonic acid solution to obtain a bismuth methanesulfonate acid leaching solution; and carrying out electro-deposition to obtain metal bismuth. The invention discloses a method for preparing high-purity metal bismuth from methanesulfonic acid system bismuth sulfide concentrate, the purity of the metal bismuth prepared through the method is 99.9% or above, and efficient and clean extraction of bismuth is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and particularly relates to a method for preparing high-purity metallic bismuth from bismuth sulfide concentrate in a methanesulfonic acid system. Background Art

[0002] The production process of metallic bismuth is mainly divided into two categories: pyrometallurgy and hydrometallurgy. Traditional pyrometallurgy mainly includes reduction smelting and precipitation smelting. Although the process is simple and the process control is convenient, it is generally prone to high energy consumption and large emissions of gaseous pollutants. It requires a complex exhaust gas purification system, resulting in high environmental costs. For example, when bismuth sulfide concentrate is processed by precipitation smelting, the sulfur element is easily converted into SO2, requiring additional equipment for desulfurization treatment. In addition, the smelting temperature is high (usually >1000°C), resulting in significant energy consumption.

[0003] Although new pyrometallurgical technologies developed in recent years, such as low-temperature alkaline smelting and bath smelting, have optimized the process to a certain extent, they still have limitations: low-temperature alkaline smelting requires a large amount of caustic soda, and the resulting molten salt slag is difficult to handle, which can easily cause secondary pollution; although bath smelting can achieve the coordinated recovery of lead and bismuth, the separation process of bismuth in crude lead is complicated and the metal recovery rate is low; although reduction solid sulfur smelting can produce metallic bismuth in one step, the process stability is insufficient, and the comprehensive utilization efficiency of associated metals (such as copper and iron) needs to be improved.

[0004] The wet bismuth refining process is suitable for low-grade, complex bismuth-containing materials and can achieve the coordinated recovery of bismuth and associated valuable metals. However, existing wet processes mostly rely on chloride or hydrochloric acid systems and have the following defects: Although the ferric chloride oxidation leaching process can achieve a bismuth leaching rate of over 98%, the iron ion cycle in the leachate accumulates seriously, requiring frequent treatment of iron-containing waste liquid, which puts great pressure on environmental protection; the chlorine oxidation leaching process requires the use of toxic and corrosive gases, which places extremely high requirements on equipment corrosion protection and sealing, and has high operational risks; although the slurry electrolysis method simplifies the process, impurities (such as copper and iron) in the leachate are easily accumulated in the system, resulting in insufficient purity of the cathode bismuth product, requiring regular open-circuit treatment of the liquid, which increases the complexity of the process. Summary of the Invention

[0005] The present invention aims to provide a method for preparing high-purity metallic bismuth from bismuth sulfide concentrate in a methanesulfonic acid system. The purity of the metallic bismuth prepared by the method is above 99.9%, thereby achieving efficient and clean extraction of bismuth.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A method for preparing high-purity metallic bismuth from bismuth sulfide concentrate in a methanesulfonic acid system comprises the following steps:

[0008] S1. Weigh bismuth sulfide concentrate powder and a surfactant, place them in a methanesulfonic acid solution, mix and slurry, pour them into a closed reactor, perform autocatalytic oxygen pressure leaching reaction, separate the solid and liquid, and collect the leachate;

[0009] S2, adding a reducing agent to the leachate obtained in S1 to obtain a reduced solution;

[0010] S3, adding the saponified extractant to the reduced solution obtained in S2, and separating to obtain a bismuth-loaded organic phase;

[0011] S4, adding a methanesulfonic acid solution as a stripping agent to the bismuth-loaded organic phase obtained in S3, and separating to obtain a bismuth stripping solution;

[0012] S5. Add a neutralizing agent to the bismuth stripping solution obtained in S4, react, separate, and discard the supernatant to obtain a bismuth hydrolysis residue;

[0013] S6, dissolving the bismuth hydrolysis residue obtained in S5 in a methanesulfonic acid solution to obtain a bismuth methanesulfonate acid leachate;

[0014] S7, electroplating the bismuth methanesulfonate acid leaching solution obtained in S6 to obtain metallic bismuth.

[0015] Preferably, in S1, the particle size of the bismuth sulfide concentrate powder is less than 75 μm.

[0016] Preferably, in S1, the surfactant includes one or more of lignin, lignin sulfonate, alkylbenzene sulfonate, anthracite, lignite, and o-phenylenediamine.

[0017] Preferably, in S1, the amount of the surfactant is 0.2%-2.0% of the mass of the bismuth sulfide concentrate powder.

[0018] Preferably, in S1, the methanesulfonic acid concentration is controlled to be 4-10 mol / L during the oxygen pressure leaching process.

[0019] Preferably, in S1, the oxygen pressure leaching reaction process conditions are specifically: reaction temperature is 80-180° C., oxygen partial pressure is 0.2 MPa-2.5 MPa, and reaction time is 60-180 min.

[0020] Preferably, in S2, the reducing agent is one of bismuth sulfide concentrate powder or bismuth powder.

[0021] Preferably, in S3, the extractant includes one or both of P204 and P507.

[0022] Preferably, in S3, the saponification reaction conditions are: saponification at 20-50° C. for 20-60 min, and a saponification degree of 30%-70%.

[0023] Preferably, in S5, the neutralizing agent includes one of ammonia water or distilled water.

[0024] Preferably, in S6, the acidity of the bismuth methanesulfonate acid leaching solution is less than 200 g / L.

[0025] In the autocatalytic oxygen pressure leaching process of bismuth sulfide concentrate, by controlling the acidity, temperature and oxygen partial pressure, FeS2 will partially dissolve into Fe 2+ ions, oxidized to Fe under the action of oxygen 3+ ions, Fe 3+ Ions act as reducing agents to dissolve Bi2S3 into Bi 3+ Entering the leachate, Fe 3+ Reduction to Fe 2+ At the same time, chalcopyrite will also partially dissolve, producing Fe 2+ ions and Cu 2+ The iron ions in the oxygen pressure leaching solution produced by this oxygen pressure process are in the form of Fe 2+ ions and Fe 3+ ions coexist. In order to avoid the bismuth extraction process with Fe 3+ Ion co-extraction, reducing agent needs to be added to the oxygen pressure leaching solution to reduce Fe 3+ ions are reduced to Fe 2+ ions. The main chemical reactions in the above process are as follows:

[0026] Bismuth sulfide concentrate autocatalytic oxygen pressure leaching process:

[0027] FeS2+O2+4H + =2Fe 2+ +4S 0 +2H2O

[0028] CuFeS2+O2+4H + =Fe 2+ +Cu 2+ +2S 0 +2H2O

[0029] CuFeS2+4Fe 3+ =5Fe 2+ +Cu 2+ +2S 0

[0030] CuFeS2+4O2=Fe 2+ +Cu 2+ +2SO4 2-

[0031] CuFeS2+4Fe 3+ +3O2+2H2O=5Fe 2+ +Cu2+ +2SO4 2- +4H +

[0032] 4Fe 2+ +O2+4H + =4Fe 3+ +2H2O

[0033] Bi2S3+24Fe 3+ +12H2O=2Bi 3+ +24H + +3SO4 2- +24Fe 2+

[0034] Bi2S3+6Fe 3+ =2Bi 3+ +3S+6Fe 2+

[0035] 2S 0 +3O2+2H2O=2SO4 2- +4H +

[0036] Reduction process of oxygen pressure leaching solution:

[0037] (1) Bismuth sulfide concentrate powder as a reducing agent

[0038] Bi2S3+24Fe 3+ +12H2O=2Bi 3+ +24H + +3SO4 2- +24Fe 2+

[0039] (2) Bismuth powder as a reducing agent

[0040] Bi+3Fe 3+ =Bi 3+ +3Fe 2+

[0041] Bi+3Cu 2+ =Bi 3+ +3Cu↓

[0042] Compared with the prior art, the present invention has the following advantages and technical effects:

[0043] The present invention discloses a method for preparing high-purity metallic bismuth from bismuth sulfide concentrate in a methanesulfonic acid system. The method adopts oxygen pressure acid leaching to replace the traditional pyrometallurgical smelting process, thereby solving the problem of atmospheric pollution in the heavy metal smelting process from the source. The environmentally friendly methanesulfonic acid is used as an oxygen pressure leaching agent, which has strong acidity, high solubility of bismuth salt, biodegradability and low toxicity, and meets the requirements of green metallurgy and sustainable metallurgical development.

[0044] The bismuth sulfide concentrate of the present invention is sequentially subjected to the steps of "oxygen pressure acid leaching-extraction-strip extraction-neutralization and hydrolysis-acid dissolution-electrodeposition" to obtain metallic bismuth with a purity of ≥99.9%, thereby realizing efficient and clean extraction of bismuth.

[0045] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a process flow chart for preparing high-purity metallic bismuth according to the present invention;

[0047] Figure 2 The characterization results of the metallic bismuth prepared in Example 1 are as follows, Figure 2 (a) is the XRD of the obtained metal bismuth, Figure 2 (b) is the SEM of the obtained metallic bismuth. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0049] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0050] Source of test materials:

[0051] In the present invention, unless otherwise specified, other test materials and instruments and equipment are conventional test materials in this field and can be purchased through commercial channels.

[0052] Examples 1-3 of the present invention are reference Figure 1 The process flow diagram is shown.

[0053] Example 1

[0054] A method for preparing high-purity metallic bismuth from bismuth sulfide concentrate in a methanesulfonic acid system comprises the following steps:

[0055] S1. Weigh bismuth sulfide concentrate powder with a particle size of less than 75 μm and 0.5 wt% calcium lignin sulfonate, place them in a 5 mol / L methanesulfonic acid solution, mix and slurry, pour them into a closed reactor, and carry out autocatalytic oxygen pressure leaching and stirring at 110° C. and an oxygen partial pressure of 1.0 MPa for 120 min, separate the solid and liquid, and collect the leachate;

[0056] S2, add bismuth sulfide concentrate powder to the leaching solution obtained in S1 to make Fe 3+ Reduction to Fe 2+ , to obtain a reducing solution;

[0057] S3, adding saponified P204 to the reduced solution obtained in S2 for separation, wherein the saponification conditions of P204 are a temperature of 40° C., a reaction time of 30 min, a saponification degree of 60%, discarding the aqueous phase, and obtaining a bismuth-loaded organic phase;

[0058] S4, adding a 6 mol / L methanesulfonic acid solution as a stripping agent to the bismuth-loaded organic phase obtained in S3, and separating to obtain a bismuth stripping solution;

[0059] S5. Add commercially available ammonia water to the bismuth strip solution obtained in S4, react, separate, and discard the supernatant to obtain a bismuth hydrolysis residue;

[0060] S6, dissolving the bismuth hydrolysis residue obtained in S5 in a methanesulfonic acid solution to obtain a bismuth methanesulfonate acid leaching solution with an acidity of less than 200 g / L;

[0061] S7, electroplating the bismuth methanesulfonate acid leaching solution obtained in S6, wherein the specific process parameters of the electroplating are a current density of 180A / m 2 , temperature 45 ° C, and inter-electrode distance 4 cm to obtain metallic bismuth. The waste electrolyte can be returned to the leaching process to achieve the recycling of the leaching agent. The obtained metallic bismuth has a purity of 99.96%.

[0062] Example 2

[0063] A method for preparing high-purity metallic bismuth from bismuth sulfide concentrate in a methanesulfonic acid system comprises the following steps:

[0064] S1. Weigh bismuth sulfide concentrate powder with a particle size of less than 75 μm and 0.7 wt% sodium lignin sulfonate, place them in a 6 mol / L methanesulfonic acid solution, mix and slurry, pour them into a closed reactor, and carry out autocatalytic oxygen pressure leaching and stirring reaction at 120° C. and an oxygen partial pressure of 0.6 MPa for 150 min, separate the solid and liquid, and collect the leachate;

[0065] S2, add bismuth sulfide concentrate powder to the leaching solution obtained in S1 to make Fe 3+ Reduction to Fe 2+ , to obtain a reducing solution;

[0066] S3, adding saponified P507 to the reduced solution obtained in S2 for separation, wherein the saponification conditions of P507 are as follows: reacting at a temperature of 30° C. for 40 min, with a saponification degree of 50%, discarding the aqueous phase, and obtaining a bismuth-loaded organic phase;

[0067] S4, adding a 5 mol / L methanesulfonic acid solution as a stripping agent to the bismuth-loaded organic phase obtained in S3, and separating to obtain a bismuth stripping solution;

[0068] S5. Add distilled water to the bismuth strip solution obtained in S4, react, separate, and discard the supernatant to obtain a bismuth hydrolysis residue;

[0069] S6, dissolving the bismuth hydrolysis residue obtained in S5 in a methanesulfonic acid solution to obtain a bismuth methanesulfonate acid leaching solution having an acidity of less than 200 g / L;

[0070] S7, electroplating the bismuth methanesulfonate acid leaching solution obtained in S6, wherein the specific process parameters of the electroplating are a current density of 160A / m 2 , temperature 40 ° C, and inter-electrode distance 3 cm to obtain metallic bismuth. The waste electrolyte can be returned to the leaching process to achieve the recycling of the leaching agent. The obtained metallic bismuth has a purity of 99.97%.

[0071] Example 3

[0072] A method for preparing high-purity metallic bismuth from bismuth sulfide concentrate in a methanesulfonic acid system comprises the following steps:

[0073] S1. Weighing bismuth sulfide concentrate powder with a particle size of less than 75 μm and 0.8 wt% lignin, placing them in a 4.5 mol / L methanesulfonic acid solution, mixing and slurrying, pouring them into a closed reactor, and performing autocatalytic oxygen pressure leaching with stirring at 100° C. and an oxygen partial pressure of 0.2 MPa for 180 min, separating the solid and liquid, and collecting the leachate;

[0074] S2, add bismuth sulfide concentrate powder to the leaching solution obtained in S1 to make Fe 3+ Reduction to Fe 2+ , to obtain a reducing solution;

[0075] S3, adding saponified P204 to the reduced solution obtained in S2 for separation, wherein the saponification conditions of P204 are as follows: reacting at a temperature of 45° C. for 30 min, with a saponification degree of 45%, discarding the aqueous phase, and obtaining a bismuth-loaded organic phase;

[0076] S4, adding a 5.5 mol / L methanesulfonic acid solution as a stripping agent to the bismuth-loaded organic phase obtained in S3, and separating to obtain a bismuth stripping solution;

[0077] S5. Add distilled water to the bismuth strip solution obtained in S4, react, separate, and discard the supernatant to obtain a bismuth hydrolysis residue;

[0078] S6, dissolving the bismuth hydrolysis residue obtained in S5 in a methanesulfonic acid solution to obtain a bismuth methanesulfonate acid leaching solution having an acidity of less than 200 g / L;

[0079] S7, electroplating the bismuth methanesulfonate acid leaching solution obtained in S6, wherein the specific process parameters of the electroplating are a current density of 170A / m 2 , temperature 35 ° C, and interelectrode distance 4 cm to obtain metallic bismuth. The waste electrolyte can be returned to the leaching process to achieve the recycling of the leaching agent. The obtained metallic bismuth has a purity of 99.95%.

[0080] The bismuth metal provided in Example 1 was characterized, and the results were as follows: Figure 2 .

[0081] Depend on Figure 2 As shown in (a), the X-ray of the cathode product corresponds to the standard card of metallic bismuth (PDF 85-1329), and the product is metallic bismuth.

[0082] Depend on Figure 2 As can be seen from (b), the metal bismuth particles are uniform and arranged in a staggered manner.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing high-purity metallic bismuth from bismuth sulfide concentrate in a methanesulfonic acid system, characterized in that: The following steps are involved: S1. Weigh bismuth sulfide concentrate powder and a surfactant, place them in a methanesulfonic acid solution, mix and slurry, pour them into a closed reactor, perform autocatalytic oxygen pressure leaching reaction, separate the solid and liquid, and collect the leachate; S2, adding a reducing agent to the leachate obtained in S1 to obtain a reduced solution; S3, adding the saponified extractant to the reduced solution obtained in S2, and separating to obtain a bismuth-loaded organic phase; S4, adding a methanesulfonic acid solution as a stripping agent to the bismuth-loaded organic phase obtained in S3, and separating to obtain a bismuth stripping solution; S5. Add a neutralizing agent to the bismuth stripping solution obtained in S4, react, separate, and discard the supernatant to obtain a bismuth hydrolysis residue; S6, dissolving the bismuth hydrolysis residue obtained in S5 in a methanesulfonic acid solution to obtain a bismuth methanesulfonate acid leachate; S7, electroplating the bismuth methanesulfonate acid leaching solution obtained in S6 to obtain metallic bismuth.

2. The method according to claim 1, characterized in that In S1, the particle size of the bismuth sulfide concentrate powder is less than 75 μm.

3. The method according to claim 1, characterized in that In S1, the surfactant includes one or more of lignin, lignin sulfonate, alkylbenzene sulfonate, anthracite, lignite, and o-phenylenediamine.

4. The method according to claim 1, characterized in that In S1, the amount of the surfactant is 0.2%-2.0% of the mass of the bismuth sulfide concentrate powder.

5. The method according to claim 1, characterized in that: In S1, the methanesulfonic acid concentration is controlled to be 4-10 mol / L during the oxygen pressure leaching process.

6. The method according to claim 1, characterized in that In S1, the oxygen pressure leaching reaction process conditions are specifically: reaction temperature is 80-180° C., oxygen partial pressure is 0.2 MPa-2.5 MPa, and reaction time is 60-180 min.

7. The method according to claim 1, characterized in that: In S2, the reducing agent is one of bismuth sulfide concentrate powder or bismuth powder.

8. The method according to claim 1, characterized in that: In S3, the extractant includes one or both of P204 and P507.

9. The method according to claim 1, characterized in that: In S6, the acidity of the bismuth methanesulfonate acid leaching solution is less than 200 g / L.

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