Method for recovering antimony and bismuth in bismuth precipitation slag

Abstract

The invention provides a method for recovering antimony and bismuth in bismuth precipitation slag, which comprises the following steps: a) leaching: mixing the bismuth precipitation slag with a mixed leaching agent, carrying out microwave acid leaching after mixing, taking out after microwave acid leaching, and filtering to obtain antimony and bismuth leachate A; b) extracting, namely extracting the antimony-bismuth leaching solution A in extraction equipment by adopting an extracting agent, taking an upper oil phase as an extracting solution containing arsenic, antimony and bismuth, collecting raffinate and returning the raffinate to a leaching process for cyclic utilization; c) fractional precipitation: adding water or sodium hydroxide into the extract A, adjusting the pH value of the extract A, performing fractional precipitation of antimony and bismuth, and returning the extract to the extraction process for cyclic utilization; and d) eluting and drying to obtain antimony oxide precipitate or bismuth oxide precipitate. After recovery, bismuth oxide with the content of 99.1-99.5% is obtained from the bismuth precipitation slag, the recovery rate of bismuth oxide is 90% or above, antimony oxide with the content of 99.3-99.6% is obtained from the bismuth precipitation slag, and the recovery rate of antimony oxide can reach 85% or above.

Description

Technical Field

[0001] The present invention belongs to the field of hydrometallurgy, and particularly relates to a method for recovering antimony and bismuth from bismuth precipitation slag. Background Art

[0002] Bismuth and antimony are widely used in many fields such as metallurgy, chemical industry, medicine, semiconductors, etc., and have high comprehensive utilization value. However, their contents in nature are relatively low, mainly existing in the form of free metals and minerals. During the copper electrolysis process, antimony and bismuth accumulate as impurity elements and are finally removed in the form of bismuth precipitation slag. The main elemental composition of bismuth-containing materials is antimony, bismuth, and arsenic, which is an important secondary resource.

[0003] At present, there are few studies on the recycling methods of bismuth precipitation slag. The main recycled material is bismuth, and the main treatment methods are divided into pyrometallurgy and hydrometallurgical leaching. Among them, the hydrometallurgical leaching process mainly includes acid leaching process and alkali leaching process. The existing bismuth precipitation slag recovery methods all need to be improved. The main deficiencies are as follows: (1) mainly focusing on bismuth recovery and paying little attention to antimony recovery, resulting in waste of resources; (2) the pyrometallurgical process not only wastes a large amount of heat resources but also requires a huge site area; (3) the hydrometallurgical process has a large consumption of leaching agents, high recovery costs, and a risk of generating highly toxic arsine gas.

[0004] In view of the problems existing in the recycling of bismuth precipitation slag, some experts and scholars have proposed improvement measures. The patent with the application number CN201911128055.X proposes a process method for recovering bismuth from bismuth slag. Through the leaching of sulfuric acid, industrial salt, and aqueous solution, the leaching temperature is 80 - 90°C, and then bismuth is recovered by neutralization and hydrolysis and precipitated in the form of slag. Although effective recovery of bismuth can be achieved, the leaching temperature is high, the energy consumption is high, and highly toxic arsine gas is easily generated, making the operating environment harsh. The patent with the application number CN202311130229.2 proposes a process for separating and recovering lead and bismuth from high-bismuth lead. The bismuth-containing slag and lead anode slime are added to the leaching tank and stirred with hydrochloric acid. After adjusting the pH value with alkali in the leaching solution, filtration and separation are carried out to obtain bismuth hydroxide, antimony hydroxide, copper precipitate, and filtrate respectively, but there are problems of large consumption of acid-base reagents and high costs. Summary of the Invention

[0005] In view of the problems of high reagent costs, high process energy consumption, and waste of antimony resources in the existing recycling of bismuth precipitation slag, the present invention proposes a method for recovering antimony and bismuth from bismuth precipitation slag. Through microwave digestion method and mixed leaching agent method, metal leaching is strengthened to achieve complete leaching of antimony and bismuth during room-temperature leaching; through extraction method, arsenic, antimony, and bismuth are selectively extracted to effectively separate impurity ions, and at the same time, part of the high-acid extraction solution is recycled to reduce the dosage of acid leaching agent and subsequent sodium hydroxide regulator; through stepwise precipitation method, arsenic is separated, and antimony and bismuth are recovered respectively.

[0006] The technical solution of the present invention is as follows: A method for recovering antimony and bismuth from bismuth precipitation slag, characterized in that it comprises the following steps: a) Leaching, mixing the bismuth precipitate slag with a mixed leaching agent prepared by HCl, NaCl and H2SO4 in a certain proportion, placing the mixture in a microwave tank after being fully mixed, and placing the microwave tank in a closed microwave digester for microwave acid leaching for 20 to 80 minutes, the leaching temperature is 25°C, the microwave frequency is 2450MHz, and after microwave acid leaching, the leaching solution A is taken out and filtered to obtain antimony bismuth leaching solution A; b) extraction, using an extractant to extract the antimony-bismuth leachate A in an extraction device, taking the upper oil phase as an extract containing arsenic, antimony and bismuth, adding an extractant and repeatedly extracting for 3 to 5 times, controlling the volume ratio of the phase O / A to be 1 / 2 to 1 / 3 for each extraction, and the extraction equilibrium time to be 3 to 10 minutes, finally obtaining the extract A after multiple extractions, collecting the aqueous phase raffinate in the lower layer during each extraction process, and returning the collected raffinate to the leaching process for recycling; c) step-by-step precipitation, adding water or sodium hydroxide to the extract A, adjusting the pH value of the extract A to 1.75-2.00, converting the antimony ions in the antimony-bismuth leachate A into antimony oxide precipitate, filtering and separating to obtain antimony oxide precipitate and extract B, further adding sodium hydroxide to the extract B to adjust its pH value to 2.27-2.75, converting the bismuth ions in the antimony-bismuth leachate A into bismuth oxide precipitate, filtering and separating to obtain bismuth oxide precipitate and extract C, and returning the extract C to the extraction process for recycling; d) eluting and drying. The separated antimony oxide precipitate or bismuth oxide precipitate is eluted with kerosene as a diluent and isooctyl alcohol as an additive, filtered and then dried.

[0007] In the above step a, in the mixed leaching agent, the HCl concentration is 50-100 g / L, the H2SO4 concentration is 100-150 g / L, and the NaCl concentration is 50 g / L.

[0008] In the above step a, the microwave working mode of the closed microwave digestion instrument is a pulse mode, and the pulse mode is an alternating mode with an interval time of 3 to 5 seconds and a microwave time of 3 to 5 seconds.

[0009] In the above step a, the liquid-to-solid mass ratio of the mixed leaching agent to the bismuth precipitated slag is 3:1.

[0010] In the above step b, the extractant is one or a mixture of tri-n-octylamine, N-hexyl isooctylamide, and tributyl phosphate.

[0011] The above-mentioned extractants, different types of the extractants are all prepared using the same volume ratio.

[0012] In the above step c, the main component of the extraction liquid C is the arsenic-containing organic phase. During the recycling process of the organic phase containing arsenic in the extraction liquid C, arsenic accumulates continuously. When the arsenic content accumulates to 50 - 60 g / L, it is removed by causticization.

[0013] In the present invention, through the microwave digestion reaction of the bismuth precipitation residue, the leaching temperature is carried out at room temperature, and antimony and bismuth in the bismuth precipitation residue are completely leached, improving the recovery rates of bismuth oxide and antimony oxide. The arsenic-containing substances in the bismuth precipitation residue will not generate highly toxic arsine gas at room temperature to affect the environment. By the extraction method, arsenic, antimony, and bismuth are selectively extracted, and through the fractional precipitation method, impurity ions are effectively separated, improving the contents of bismuth oxide and antimony oxide. After recovery, bismuth oxide with a content of 99.1 - 99.5% is obtained in the bismuth precipitation residue, and the recovery rate of bismuth oxide is over 90%. Antimony oxide with a content of 99.3 - 99.6% is obtained in the bismuth precipitation residue, and the recovery rate of antimony oxide can reach over 85%.

[0014] In the present invention, the pulsed microwave method is uniquely adopted for microwave acid leaching, enabling high leaching efficiency of complete leaching of antimony and bismuth in the bismuth precipitation residue. This is because the bismuth precipitation residue is deposited at the anode during the copper electrolysis process and contains a large amount of substances with small pores. During the microwave acid leaching process of the bismuth precipitation residue, if only the microwave method is used, due to factors such as the tiny vibration and bubbles generated by the bismuth precipitation residue under the action of microwaves, it is difficult for the mixed leaching agent to penetrate deep into the small pores inside the bismuth precipitation residue. If only static acid leaching is used, although the mixed leaching agent can penetrate deep into the small pores inside the bismuth precipitation residue, it is difficult for the mixed leaching agent to diffuse from the inside to the outside, resulting in a long leaching time. After adopting the pulsed mode, when the mixed leaching agent is static, it can penetrate well into the small pores inside the bismuth precipitation residue. When it is dynamic, the mixed leaching agent that has penetrated deep into the small pores inside the bismuth precipitation residue accelerates the exchange of ion concentrations inside and outside through microwave vibration. Therefore, the pulsed microwave can well solve the leaching problem inside the bismuth precipitation residue with many small pores through the combination of one movement and one stillness. Description of the Drawings

[0015] Figure 1 It is the process flow chart of the present invention. Detailed Embodiments

[0016] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0017] The bismuth slag in this embodiment is obtained from the deposited slag formed at the anode during the copper electrolysis process, in which antimony and bismuth as impurity elements continuously accumulate. The bismuth slag is crushed and ground into a source for the implementation of the present invention. The bismuth slag is sampled and various contents in the bismuth slag are measured. By weight, the Bi2O3 content is 24.36%, the Sb2O3 content is 16.74%, the As2O3 content is 13.47%, and the rest are acid slag impurities.

[0018] In this embodiment, the leaching temperature is room temperature. In the specific implementation process, the present invention adopts 25° C. as the control temperature for room temperature implementation in order to better illustrate the implementation.

[0019] In order to make the above features and advantages of the present invention more clearly understood, the following embodiments are given for detailed description. The methods of the present invention are all conventional methods in the art unless otherwise specified.

[0020] Example 1 Method for recovering antimony and bismuth from bismuth precipitation slag Figure 1 The recycling process is carried out in the following steps: a) Leaching, taking 1.2 kg of the above-mentioned bismuth slag and 3.6 kg of mixed leaching agent, uniformly mixing the bismuth slag in the mixed leaching agent, and after fully mixing, placing the mixture in multiple 100 ml microwave jars, and placing the microwave jars in a closed microwave digester for microwave acid leaching for 60 minutes, the leaching temperature is 25° C., the microwave frequency is 2450 MHz, and after microwave acid leaching, the antimony bismuth leachate A is taken out and filtered to obtain the mixed leaching agent, the HCl concentration is 50 g / L, the H2SO4 concentration is 150 g / L, and the NaCl concentration is 50 g / L. The closed microwave digester uses a high-throughput closed microwave digester containing 40 jars, and the microwave working mode of the closed microwave digester is a pulse mode, and the pulse mode is an alternating mode of an interval time of 3 to 5 s and a microwave time of 3 to 5 s; b) Extraction, using an extractant to extract the antimony-bismuth leaching solution A in an extraction device, taking the upper oil phase as the extract containing arsenic, antimony and bismuth, adding the extractant and extracting repeatedly for 4 times, each time the extractant extraction control phase O / A volume ratio is 1 / 2, the extractant is a mixture of tri-n-octylamine and N-hexyl isooctylamide in a volume ratio of 1:1, the extraction equilibrium time is 10min, and finally obtaining the extract A after multiple extractions, collecting the lower aqueous phase raffinate during each extraction process, and returning the collected raffinate to the leaching process for recycling; c) Stepwise precipitation: Add water to the extraction solution A to adjust the pH value of the extraction solution A to 1.90, so that the antimony ions in the antimony-bismuth leaching solution A are transformed into antimony oxide precipitate. After filtration and separation, antimony oxide precipitate and extraction solution B are obtained respectively. Then add sodium hydroxide to the extraction solution B and adjust its pH value to 2.45, so that the bismuth ions in the antimony-bismuth leaching solution A are transformed into bismuth oxide precipitate. After filtration and separation, bismuth oxide precipitate and extraction solution C are obtained respectively. The extraction solution C is returned to the extraction process for recycling; d) Elution and drying: Use kerosene as the diluent and isooctanol as the additive to elute the separated antimony oxide precipitate or bismuth oxide precipitate. After filtration, it is dried to obtain 275.81 g of recovered bismuth oxide precipitate and 187.53 g of recovered antimony oxide precipitate after drying.

[0021] In step b, the concentration of Na + in the raffinate is measured by flame photometry, and the NaCl concentration (unit: g / L) in the raffinate is calculated and converted. The concentration of SO4 2- in the raffinate is calculated and converted to obtain the H2SO4 concentration (unit: g / L) in the raffinate after titration with Ba(OH)2. Filter the raffinate after Ba(OH)2 titration, and add an appropriate amount of nitric acid to keep the raffinate acidic. Then further titrate the Cl - molar concentration in the raffinate with AgNO3 solution. Subtract the molar concentration of Na - from the molar concentration of Cl + and convert it to obtain the HCl concentration (unit: g / L) in the original raffinate. When the raffinate is returned to the leaching process for recycling, the raffinate is adjusted to the concentration of the mixed leaching agent used in step a by adding NaCl, sulfuric acid solution and hydrochloric acid solution.

[0022] The contents of antimony oxide and bismuth oxide in the bismuth precipitation residue and the antimony oxide and bismuth oxide in the dried bismuth oxide precipitate and antimony oxide precipitate obtained after recovery are determined by atomic absorption spectrometry (AAS).

[0023] The recovery rate of bismuth oxide is calculated by dividing the mass of the recovered bismuth oxide precipitate by the actual weight of bismuth oxide in the bismuth precipitation residue determined by sampling and measuring the bismuth oxide content in the bismuth precipitation residue.

[0024] The recovery rate of antimony oxide is calculated by dividing the mass of the recovered antimony oxide precipitate by the actual weight of antimony oxide in the bismuth precipitation residue determined by sampling and measuring the antimony oxide content in the bismuth precipitation residue.

[0025] Specific process reference numbers for the antimony-bismuth recovery method of the bismuth precipitation residue, as well as the contents and recovery rates of antimony oxide and bismuth oxide, are shown in Table 1.

[0026] The formulation ratio of the mixed leaching agent and the extraction agent used in the implementation process refers to Table 2. In Table 2, different types of extraction agents are prepared with the same volume ratio. For example, the mixed extraction agent composed of tri-n-octylamine and N-hexyl isooctanamide is mixed at a volume ratio of 1:1.

[0027] For Examples 2 to 5, the method for recovering antimony and bismuth from bismuth-deposited slag is the same as that in Example 1. The implementation process parameters, the content and recovery rate of antimony trioxide and bismuth trioxide are shown in Table 1 for reference, and the formulation ratio of the mixed leaching agent and the extraction agent used in the implementation refers to Table 2 for reference.

[0028] For Comparative Examples 1 to 2, compared with the method for recovering antimony and bismuth from bismuth-deposited slag in Example 1, the difference lies in that the acid leaching method is normal acid leaching, that is, there is no microwave method during the normal acid leaching process. The implementation process parameters, the content and recovery rate of antimony trioxide and bismuth trioxide are shown in Table 1 for reference.

[0029] Table 1

[0030] Table 2

[0031] The implementation results of Examples 1 to 5 show that through the normal-temperature microwave acid leaching of bismuth-deposited slag and the extraction method, antimony and bismuth in the bismuth-deposited slag can be recovered well. After recovery, the recovery rate of bismuth trioxide is over 90%, and the recovery rate of antimony trioxide can reach over 85%. For Comparative Examples 1 to 2, due to the absence of microwave acid leaching, antimony and bismuth in the bismuth-deposited slag cannot be completely leached at normal temperature. The recovery rate of bismuth trioxide is lower than 85%, and the recovery rate of antimony trioxide is lower than 80%. In Comparative Example 2, even though the acid leaching time was significantly increased compared with Comparative Example 1, the improvement in the recovery rates of bismuth trioxide and antimony trioxide was not obvious.

[0032] In Examples 1, 3, and 5 of the present embodiment, pulse microwave acid leaching is used, and the recovery rate of bismuth trioxide is also better than that of normal microwave acid leaching in Examples 2 and 4, indicating that using pulse microwave can better improve the leaching rate of antimony and bismuth in bismuth-deposited slag. Antimony and bismuth in the small pores inside the bismuth-deposited slag are completely leached through pulse microwave, and the leaching efficiency is high. After the pulse mode, the mixed leaching agent can be in a static state and penetrate well into the deep small pores inside the bismuth-deposited slag. When in a dynamic state, the mixed leaching agent that has penetrated into the deep small pores inside the bismuth-deposited slag accelerates the ion concentration exchange between the inside and the outside through microwave vibration. Therefore, pulse microwave can well solve the leaching problem inside the small pores of bismuth-deposited slag through the combination of dynamic and static states.

[0033] Samples of the recovered bismuth oxide and recovered antimony oxide from Examples 1 to 3 were taken for acid digestion, and after dilution, the mass contents of Bi2O3, Sb2O3 and As2O3 were further determined by atomic absorption spectrometry (AAS). The results are shown in Table 3.

[0034] Table 3

[0035] The implementation results show that for the recovered bismuth oxide after recovery, the mass content of bismuth oxide is 99.1 - 99.5%, and for the recovered antimony oxide after recovery, the mass content of antimony oxide is 99.3 - 99.6%. Moreover, in the recovered bismuth oxide or recovered bismuth oxide, the content of arsenic oxide is ≤ 0.06%. This indicates that the arsenic-containing harmful impurities in the bismuth precipitation residue are enriched in the extraction liquid C during the extraction process, which facilitates further causticization and removal after accumulation, achieving the purpose of waste liquid treatment and avoiding environmental pollution by arsenic compounds.

[0036] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for recovering antimony and bismuth from bismuth precipitation slag, characterized in that: The steps include: a) Leaching, mixing the bismuth precipitate slag with a mixed leaching agent prepared by HCl, NaCl and H2SO4 in a certain proportion, placing the mixture in a microwave tank after being fully mixed, and placing the microwave tank in a closed microwave digester for microwave acid leaching for 20 to 80 minutes, the leaching temperature is 25°C, the microwave frequency is 2450MHz, and after microwave acid leaching, the leaching solution A is taken out and filtered to obtain antimony bismuth leaching solution A; b) extraction, using an extractant to extract the antimony-bismuth leachate A in an extraction device, taking the upper oil phase as an extract containing arsenic, antimony and bismuth, adding an extractant and repeatedly extracting for 3 to 5 times, controlling the volume ratio of the phase O / A to be 1 / 2 to 1 / 3 for each extraction, and the extraction equilibrium time to be 3 to 10 minutes, finally obtaining the extract A after multiple extractions, collecting the aqueous phase raffinate in the lower layer during each extraction process, and returning the collected raffinate to the leaching process for recycling; c) step-by-step precipitation, adding water or sodium hydroxide to the extract A, adjusting the pH value of the extract A to 1.75-2.00, converting the antimony ions in the antimony-bismuth leachate A into antimony oxide precipitate, filtering and separating to obtain antimony oxide precipitate and extract B, further adding sodium hydroxide to the extract B to adjust its pH value to 2.27-2.75, converting the bismuth ions in the antimony-bismuth leachate A into bismuth oxide precipitate, filtering and separating to obtain bismuth oxide precipitate and extract C, and returning the extract C to the extraction process for recycling; d) eluting and drying. The separated antimony oxide precipitate or bismuth oxide precipitate is eluted with kerosene as a diluent and isooctyl alcohol as an additive, filtered and then dried.

2. A method for recovering antimony and bismuth from bismuth precipitated slag according to claim 1 or claim 2, characterized in that: In step a, in the mixed leaching agent, the HCl concentration is 50-100 g / L, the H2SO4 concentration is 100-150 g / L, and the NaCl concentration is 50 g / L.

3. The method for recovering antimony and bismuth from bismuth precipitated slag according to claim 1, characterized in that: In step a, the microwave working mode of the closed microwave digestion instrument is pulse mode.

4. The method for recovering antimony and bismuth from bismuth precipitated slag according to claim 4, characterized in that: The pulse mode is an alternating mode with an intermittent time of 3 to 5 seconds and a microwave time of 3 to 5 seconds.

5. The method for recovering antimony and bismuth from bismuth precipitated slag according to claim 1, characterized in that: The liquid-to-solid mass ratio of the mixed leaching agent to the bismuth precipitated slag is 3:

1.

6. The method for recovering antimony and bismuth from bismuth precipitated slag according to claim 1, characterized in that: In step b, the extractant is one or a mixture of tri-n-octylamine, N-hexyl isooctylamide, tributyl phosphate.

7. The method for recovering antimony and bismuth from bismuth-precipitated slag according to claim 6, characterized in that: Different types of the extractants are all prepared using the same volume ratio.

8. The method for recovering antimony and bismuth from bismuth-precipitated slag according to claim 1, characterized in that: In step c, the extract C is mainly composed of an arsenic-containing organic phase. Arsenic in the extract C is continuously accumulated during the organic phase circulation process. When the arsenic accumulates to a content of 50-60 g / L, it is removed by causticization.

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