Method for preparing high-purity bismuth and recovering associated silver by taking bismuthite as raw material

Abstract

The invention relates to a method for preparing high-purity bismuth and recovering associated silver by using bismuthite as a raw material, which comprises the following steps: levigating bismuthite, adding into an acid solution, and heating for reaction to obtain leached residues and leached liquid; mixing an organic extraction agent with the leachate, extracting, and separating oil and water; supplementing acid into the raffinate and then returning to leach the bismuthite; mixing water with the extract liquor for reverse extraction, and filtering the obtained reverse extraction liquor to obtain bismuth-containing precipitates; mixing the bismuth-containing precipitate with an ammonia water solution, carrying out size mixing, and carrying out solid-liquid separation to obtain filtrate and filter residues; returning the filtrate to mix with the bismuth-containing precipitate for size mixing; washing and drying filter residues, and carrying out reduction reaction at high temperature to obtain high-purity bismuth; when the concentration of silver in the filtrate is larger than or equal to 1 g / L, hydrazine hydrate is added for a reaction, solid-liquid separation is conducted, silver powder is obtained, and tail liquid is returned to be used for bismuth-containing precipitate size mixing; by means of the method, bismuth in bismuthite can be efficiently extracted, and the purity of obtained bismuth is high and can reach 99.9% or above.

Description

Technical Field

[0001] The present invention relates to the technical field of non-ferrous metal extraction and metallurgy, and more particularly to a method for preparing high-purity bismuth using bismuthinite as a raw material and recovering associated silver. Background Art

[0002] Traditional pyrometallurgical bismuth smelting suffers from numerous challenges, including low bismuth resource utilization, severe low-concentration SO₂ flue gas pollution, high reagent consumption, and high processing costs. Consequently, researchers at home and abroad have developed hydrometallurgical processes, including ferric chloride leaching, chlorine selective leaching, and slurry electrolysis, to advance bismuth metallurgical technology. However, these processes still have drawbacks. For example, the ferric chloride leaching process uses iron powder to replace sponge bismuth, requiring chlorine oxidation to regenerate FeCl₃. This results in high raw material consumption, high wastewater discharge, and severe equipment corrosion. Chlorine selective leaching, which selectively leaches bismuth by controlling the system's potential, consumes a lot of chlorine, causes severe equipment corrosion, and creates harsh working conditions. While slurry electrolysis offers a short and simple process, it has poor adaptability to raw material fluctuations and high production costs, making it difficult to commercialize. Summary of the Invention

[0003] Based on the above technical problems existing in the prior art, the present invention provides a method for preparing high-purity bismuth using bismuthinite as raw material and recovering associated silver. This method can efficiently extract bismuth from bismuthinite, and the obtained bismuth has a high purity of up to 99.9%.

[0004] In order to achieve the above object, the technical solution of the present invention is as follows:

[0005] A method for preparing high-purity bismuth using bismuthinite as a raw material comprises the following steps:

[0006] S1, grinding bismuthite, then adding it to an acidic solution, heating it to react, and then separating the solid and liquid to obtain leaching residue and leachate;

[0007] S2, mixing an organic extractant with the leachate, extracting, and then separating oil and water to obtain a raffinate and an extract; adding acid to the raffinate and returning it to step S1 for leaching bismuthinite; mixing water with the extract for stripping, and filtering the obtained stripping solution to obtain a bismuth-containing precipitate;

[0008] S3, mixing the bismuth-containing precipitate with an ammonia solution to prepare a slurry, and performing solid-liquid separation to obtain a filtrate and a filter residue; the filtrate is recycled for mixing with the bismuth-containing precipitate to prepare a slurry; the filter residue is washed and dried, and then reacted in a reducing atmosphere at 700-900° C. to obtain high-purity bismuth;

[0009] S4. When the silver concentration in the filtrate recycled in step S3 is ≥1 g / L, hydrazine hydrate is added thereto for reaction, followed by solid-liquid separation to obtain silver powder and tail liquid, which is returned to step S3 for recycling and slurrying of bismuth-containing precipitation.

[0010] In some embodiments, in step S1, the acidic solution contains H + The concentration is 1-5 mol / L; preferably, H + The concentration is 1-3 mol / L.

[0011] In some embodiments, in step S1, the acidic solution is at least one of a hydrochloric acid solution and a sulfuric acid solution; or, the acidic solution includes an acid solution and a co-solvent, and the acid solution includes at least one of a hydrochloric acid solution and a sulfuric acid solution; and the co-solvent includes at least one of magnesium chloride and sodium chloride.

[0012] In some embodiments, in step S1, the temperature of the acid leaching reaction is 80-95°C.

[0013] In some embodiments, in step S1, the acid leaching reaction time is 1-5 hours.

[0014] In some embodiments, in step S1, the bismuthinite is ground to -200 mesh and then added to the acidic solution.

[0015] In some embodiments, in step S1, the solid-to-liquid ratio of the bismuthinite to the acidic solution is 1 g: 1-10 mL.

[0016] In some embodiments, in step S2, the organic extractant is at least one of TBP, TOP, and N235.

[0017] In some embodiments, in step S2, during the stripping process, the ratio of the organic phase to the aqueous phase is 1-4:2.

[0018] In some embodiments, in step S3, the concentration of the ammonia solution is 10 wt%-20 wt%.

[0019] In some embodiments, in step S3, the solid-to-liquid ratio of the bismuth-containing precipitate to the ammonia water is 1 g:2-10 mL.

[0020] In some embodiments, in step S3, the reducing atmosphere is one of a hydrogen atmosphere and a carbon monoxide atmosphere; preferably, it is a hydrogen atmosphere.

[0021] In some embodiments, in step S3, the reduction reaction time is 1-5 hours.

[0022] In some embodiments, the bismuth content in the bismuthinite is 15-25 wt%, the silver content is 180-250 g / t, and the bismuth content in the leaching residue is less than 0.5 wt%.

[0023] In some embodiments, the purity of the high-purity bismuth is 99.9%-99.99%.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention uses bismuthinite as raw material, and uses an acid leaching method to leach the raw ore to obtain a filtrate and a filter residue. Then, an extraction and stripping method is used to obtain a bismuth-containing precipitate, which is then washed with ammonia water to remove impurities. The filter residue obtained after impurity removal is then subjected to a reduction reaction to obtain high-purity bismuth with a purity of ≥99.9%. The method of the present invention can effectively extract bismuth from bismuthinite, and the process flow is short and the extraction efficiency is high, providing a new approach to the extraction and metallurgy of bismuthinite. In addition, the solution obtained after ammonia washing and separation is reduced with hydrazine hydrate to obtain silver powder, achieving bismuth extraction and recovery of associated silver, improving the comprehensive utilization of bismuthinite and realizing the comprehensive utilization of mineral resources. DETAILED DESCRIPTION

[0026] The following description sets forth numerous specific details to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific implementations disclosed below.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] The bismuthinite concentrate used in the following examples of the present invention was sourced from Chenzhou, Hunan Province, and the bismuth content in the concentrate was 23.6 wt % and the silver content was 218 g / t. The reagents and materials used in the examples, unless otherwise specified, were purchased through ordinary commercial channels or prepared by conventional methods.

[0029] Example 1

[0030] A method for preparing high-purity bismuth using bismuthinite as a raw material and recovering associated silver comprises the following steps:

[0031] S1, grinding bismuthinite to -200 mesh and adding it to an acidic solution at a solid-liquid ratio of 1kg:5L, heating to 90°C for reaction for 3h, and then separating the solid and liquid to obtain leaching residue and leachate; wherein the acidic solution includes hydrochloric acid and sodium chloride, H+ The concentration is 3 mol / L;

[0032] S2, mixing and extracting the organic extractant N235 with the leachate, and then separating the oil and water to obtain a raffinate and an extract; adding acid to the raffinate and returning it to step S1 for leaching bismuthinite; mixing water with the extract for stripping, controlling the phase ratio (O / A) of the stripping to be 1:1, and filtering the obtained stripping solution to obtain a bismuth-containing precipitate;

[0033] S3, mixing the bismuth-containing precipitate with a 10 wt% ammonia solution at a liquid-solid ratio of 1 kg:3 L to prepare a slurry, and separating the solid and liquid to obtain a filtrate and a filter residue; the filtrate is recycled for mixing with the bismuth-containing precipitate to prepare a slurry; the filter residue is washed and dried, and then reacted in a hydrogen atmosphere at 800° C. for 4 hours to obtain high-purity bismuth;

[0034] S4. When the silver concentration in the filtrate recycled in step S3 is ≥1 g / L, hydrazine hydrate is added to the filtrate for reaction, followed by solid-liquid separation to obtain silver powder and tail liquid; the tail liquid is returned to step S3 for recycling and slurry preparation of bismuth-containing precipitation.

[0035] After testing, the purity of the high-purity bismuth obtained in this embodiment was 99.95%, and the bismuth recovery rate was 97.2%; the purity of the silver powder was 99.9%, and the silver recovery rate was 92.1%.

[0036] Example 2

[0037] A method for preparing high-purity bismuth using bismuthinite as a raw material and recovering associated silver comprises the following steps:

[0038] S1, grinding bismuthinite to -200 mesh and adding it to an acidic solution at a solid-liquid ratio of 1kg:5L, heating to 95°C for reaction for 3h, and then separating the solid and liquid to obtain leaching residue and leachate; wherein the acidic solution includes hydrochloric acid and sodium chloride, H + The concentration is 3 mol / L;

[0039] S2, mixing and extracting the organic extractant N235 with the leachate, and then separating the oil and water to obtain a raffinate and an extract; adding acid to the raffinate and returning it to step S1 for leaching bismuthinite; mixing water with the extract for stripping, controlling the phase ratio (O / A) of the stripping to be 1:2, and filtering the obtained stripping solution to obtain a bismuth-containing precipitate;

[0040] S3, mixing the bismuth-containing precipitate with a 15 wt% ammonia solution at a liquid-solid ratio of 1 kg:2.5 L to prepare a slurry, and separating the solid and liquid to obtain a filtrate and a filter residue; the filtrate is recycled for mixing with the bismuth-containing precipitate to prepare a slurry; the filter residue is washed and dried, and then reacted in a hydrogen atmosphere at 800° C. for 4 hours to obtain high-purity bismuth;

[0041] S4. When the silver concentration in the filtrate recycled in step S3 is ≥1 g / L, hydrazine hydrate is added to the filtrate for reaction, followed by solid-liquid separation to obtain silver powder and tail liquid; the tail liquid is returned to step S3 for recycling and slurry preparation of bismuth-containing precipitation.

[0042] After testing, the purity of the high-purity bismuth obtained in this embodiment was 99.97%, and the bismuth recovery rate was 97.1%; the purity of the silver powder was 99.9%, and the silver recovery rate was 91.8%.

[0043] Example 3

[0044] A method for preparing high-purity bismuth using bismuthinite as a raw material and recovering associated silver comprises the following steps:

[0045] S1. Grind bismuthinite to -200 mesh and add it to an acidic solution at a solid-liquid ratio of 1kg:10L. Heat to 95°C for 3h. Then separate the solid and liquid to obtain leaching residue and leachate. The acidic solution includes hydrochloric acid and sodium chloride. H + The concentration is 3 mol / L;

[0046] S2, mixing and extracting the organic extractant TBP with the leachate, and then separating the oil and water to obtain a raffinate and an extract; adding acid to the raffinate and returning it to step S1 for leaching bismuthinite; mixing water with the extract for stripping, controlling the phase ratio (O / A) of the stripping to be 1:2, and filtering the obtained stripping solution to obtain a bismuth-containing precipitate;

[0047] S3, mixing the bismuth-containing precipitate with a 15 wt% ammonia solution at a liquid-solid ratio of 1 kg:3 L to prepare a slurry, and separating the solid and liquid to obtain a filtrate and a filter residue; the filtrate is recycled for mixing with the bismuth-containing precipitate to prepare a slurry; the filter residue is washed and dried, and then reacted in a hydrogen atmosphere at 900° C. for 4 hours to obtain high-purity bismuth;

[0048] S4. When the silver concentration in the filtrate recycled in step S3 is ≥1 g / L, hydrazine hydrate is added to the filtrate for reaction, followed by solid-liquid separation to obtain silver powder and tail liquid; the tail liquid is returned to step S3 for recycling and slurry preparation of bismuth-containing precipitation.

[0049] After testing, the purity of the high-purity bismuth obtained in this embodiment was 99.96%, and the bismuth recovery rate was 97.8%; the purity of the silver powder was 99.9%, and the silver recovery rate was 92.6%.

[0050] Example 4

[0051] A method for preparing high-purity bismuth using bismuthinite as a raw material and recovering associated silver comprises the following steps:

[0052] S1, grinding bismuthinite to -200 mesh and adding it to an acidic solution at a solid-liquid ratio of 1kg:8L, heating to 95°C for reaction for 3h, and then separating the solid and liquid to obtain leaching residue and leachate; wherein the acidic solution includes hydrochloric acid and sodium chloride, H + The concentration is 3 mol / L;

[0053] S2, mixing and extracting the organic extractant N235 with the leachate, and then separating the oil and water to obtain a raffinate and an extract; adding acid to the raffinate and returning it to step S1 for leaching bismuthinite; mixing water with the extract for stripping, controlling the phase ratio (O / A) of the stripping to be 1:2, and filtering the obtained stripping solution to obtain a bismuth-containing precipitate;

[0054] S3, mixing the bismuth-containing precipitate with a 20 wt% ammonia solution at a liquid-solid ratio of 1 kg:2 L to prepare a slurry, and separating the solid and liquid to obtain a filtrate and a filter residue; the filtrate is recycled for mixing with the bismuth-containing precipitate to prepare a slurry; the filter residue is washed and dried, and then reacted in a hydrogen atmosphere at 900° C. for 4 hours to obtain high-purity bismuth;

[0055] S4. When the silver concentration in the filtrate recycled in step S3 is ≥1 g / L, hydrazine hydrate is added to the filtrate for reaction, followed by solid-liquid separation to obtain silver powder and tail liquid; the tail liquid is returned to step S3 for recycling and slurry preparation of bismuth-containing precipitation.

[0056] After testing, the purity of the high-purity bismuth obtained in this embodiment was 99.97%, and the bismuth recovery rate was 97.5%; the purity of the silver powder was 99.9%, and the silver recovery rate was 92.3%.

[0057] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing high-purity bismuth using bismuthinite as raw material and recovering associated silver, characterized in that: The following steps are involved: S1, grinding bismuthite, then adding it to an acidic solution, heating it to react, and then separating the solid and liquid to obtain leaching residue and leachate; S2, mixing an organic extractant with the leachate, extracting, and then separating oil and water to obtain a raffinate and an extract; adding acid to the raffinate and returning it to step S1 for leaching bismuthinite; mixing water with the extract for stripping, and filtering the obtained stripping solution to obtain a bismuth-containing precipitate; S3, mixing the bismuth-containing precipitate with an ammonia solution to prepare a slurry, and performing solid-liquid separation to obtain a filtrate and a filter residue; the filtrate is recycled for mixing with the bismuth-containing precipitate to prepare a slurry; the filter residue is washed and dried, and then reacted in a reducing atmosphere at 700-900° C. to obtain high-purity bismuth; S4. When the silver concentration in the filtrate recycled in step S3 is ≥1 g / L, hydrazine hydrate is added thereto for reaction, followed by solid-liquid separation to obtain silver powder and tail liquid, which is returned to step S3 for recycling and slurrying of bismuth-containing precipitation.

2. The method for preparing high-purity bismuth and recovering associated silver using bismuthinite as raw material according to claim 1, characterized in that: In step S1, H + The concentration is 1-5mol / L.

3. The method for preparing high-purity bismuth and recovering associated silver using bismuthinite as raw material according to claim 1, characterized in that: In step S1, the acidic solution is at least one of a hydrochloric acid solution and a sulfuric acid solution; or, the acidic solution includes an acid solution and a co-solvent, the acid solution includes at least one of a hydrochloric acid solution and a sulfuric acid solution; the co-solvent includes at least one of magnesium chloride and sodium chloride.

4. The method for preparing high-purity bismuth using bismuthinite as raw material and recovering associated silver according to claim 1, characterized in that: In step S1, the temperature of the acid leaching reaction is 80-95°C.

5. The method for preparing high-purity bismuth and recovering associated silver using bismuthinite as raw material according to claim 1, characterized in that: In step S2, the organic extractant is at least one of TBP, TOP, and N235.

6. The method for preparing high-purity bismuth using bismuthinite as raw material and recovering associated silver according to claim 1, characterized in that: In step S2, during the stripping process, the ratio of the organic phase to the aqueous phase is 1-4:

2.

7. The method for preparing high-purity bismuth and recovering associated silver using bismuthinite as raw material according to claim 1, characterized in that: In step S3, the concentration of the ammonia solution is 10-20 wt%.

8. The method for preparing high-purity bismuth and recovering associated silver using bismuthinite as raw material according to claim 1, characterized in that: In step S3, the solid-liquid ratio of the bismuth-containing precipitate to the ammonia water is 1 g:2-10 mL.

9. The method for preparing high-purity bismuth and recovering associated silver using bismuthinite as raw material according to claim 1, characterized in that: The bismuth content in the bismuthinite is 15-25 wt%, the silver content is 180-250 g / t, and the bismuth content in the leaching residue is less than 0.5 wt%.

10. The method for preparing high-purity bismuth and recovering associated silver using bismuthinite as raw material according to any one of claims 1 to 9, characterized in that: The purity of the high-purity bismuth is 99.9%-99.99%.