A method for directly leaching germanium from germanium-containing lignite

Abstract

The present application relates to a method for directly leaching germanium from germanium-containing lignite, which involves germanium precipitation technology. An embodiment of the present application provides a method for directly leaching germanium from germanium-containing lignite, which comprises directly leaching germanium from germanium-containing lignite by leaching treatment with thionyl chloride as a leaching agent. The method of the present application can efficiently and mildly leach germanium from germanium-containing lignite, and can realize comprehensive utilization of coal-based organic matter.

Description

TECHNICAL FIELD

[0001] The present application relates to germanium technology, and in particular to a method for directly leaching germanium from germanium-containing lignite. BACKGROUND

[0002] Germanium belongs to a rare metal and is widely used in high-tech fields such as infrared optics, optical fiber communication, semiconductors, solar cells, medicine, and catalysis, and is designated as a strategic resource. Germanium resources are scattered and distributed in various minerals and rocks, mainly associated with lignite and lead-zinc ore. Since industrial germanium is largely dependent on germanium-rich lignite, the rational development of germanium-rich lignite is an important guarantee for the safe supply of germanium. At present, there are still many challenges in the super-enrichment and extraction of germanium. The contradiction between increasing global demand for germanium and supply crisis is becoming increasingly prominent. The reason is not the scarcity of germanium resources, but the lack of effective, economic and environmentally friendly recovery processes.

[0003] Currently, the recovery of germanium in coal in the domestic industry is generally derived from fly ash produced during the combustion process. The combustion conditions have a significant impact on the subsequent extraction of germanium. In order to improve the recovery rate of germanium, part of the heat energy generated during combustion needs to be sacrificed to take into account the grade of germanium in fly ash, and the combustion of coal can also induce certain environmental problems, increasing carbon emissions, which is not consistent with the "double carbon" goal pursued by the country. In addition, as lignite rich in humic substances, a large amount of high-value-added humic substances is lost during direct combustion. Among the existing methods for extracting germanium from coal, the most widely used chlorination distillation method has been industrialized for more than 50 years, and the technology is relatively mature with low equipment complexity. However, high-concentration hydrochloric acid needs to be used in the leaching process to achieve selective dissolution and strengthen the dissolution process, which has problems such as high system acidity, large amount of waste acid production, and difficulty in harmless disposal of residues. In summary, it is imperative to develop a method for low-carbon and efficient leaching of germanium from germanium-containing lignite. SUMMARY

[0004] To overcome at least one of the above-mentioned deficiencies of the prior art, in a first aspect, an embodiment of the present application provides a method for directly leaching germanium from germanium-containing lignite, comprising leaching germanium from germanium-containing lignite by using thionyl chloride as a leaching agent.

[0005] According to an embodiment of the present application, the method comprises the following steps:

[0006] S1, providing a first mixture comprising germanium-containing lignite and thionyl chloride;

[0007] S2, leaching the first mixture to obtain a second mixture; and

[0008] S3, performing solid-liquid separation on the second mixture, and then performing rotary evaporation on the liquid phase to obtain a germanium-rich solid and regenerated thionyl chloride.

[0009] According to an embodiment of the present application, in the first mixture, the mass of the thionyl chloride is 5-20 times the mass of the germanium-containing lignite.

[0010] According to an embodiment of the present application, in the S2, the temperature of the leaching treatment is 5-135 DEG C.

[0011] According to an embodiment of the present application, in the S2, the time of the leaching treatment is 0.5-12 h.

[0012] According to an embodiment of the present application, in the S2, the stirring rate of the leaching treatment is 100-600 r / min.

[0013] According to an embodiment of the present application, the S3 comprises:

[0014] The second mixture is subjected to solid-liquid separation to obtain residual coal and thionyl chloride leaching solution, and the thionyl chloride leaching solution is subjected to rotary evaporation to obtain regenerated thionyl chloride and germanium-rich solid.

[0015] According to an embodiment of the present application, the residual coal is used as a precursor raw material of coal-based ammoniated modified nitrogen fertilizer.

[0016] According to an embodiment of the present application, the solid-liquid separation is performed by suction filtration or centrifugation.

[0017] According to an embodiment of the present application, the germanium-rich solid is used as a subsequent germanium extraction raw material.

[0018] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0019] The method for directly leaching germanium from germanium-containing lignite according to the present application uses thionyl chloride as a leaching agent for leaching, and the germanium leaching rate can reach more than 99%. Compared with the traditional chlorination leaching, the reagent has a weak acid-base degree, and the conditions are relatively mild, the germanium leaching rate is effectively improved, and a large amount of waste acid is not generated, thereby reducing the environmental hazards of the leaching process. The product can be used as a precursor raw material of coal-based ammoniated modified nitrogen fertilizer, thereby reducing resource waste and environmental pollution caused by the combustion process.

[0020] The method for directly leaching germanium from germanium-containing lignite according to the present application has a coal yield of more than 95% after leaching operation, the coal-based organic matter can be effectively recovered, and the basic organic framework in the coal is not substantially damaged, and the residual coal can be used as a precursor raw material of coal-based ammoniated modified nitrogen fertilizer.

[0021] The method for directly leaching germanium from germanium-containing lignite according to the present application has a short technological process, high resource comprehensive utilization rate, and small environmental pollution, the leaching agent thionyl chloride can be recycled and reused, the lignite is used in a high-value and clean way, the cost is saved, the economic benefit is remarkable, the main single-mouth flask equipment used is mature and easy to be industrialized.

[0022] The method for directly leaching germanium from germanium-containing lignite according to the present application can efficiently and mildly leach germanium from germanium-containing lignite and realize comprehensive utilization of coal-based organic matter.

[0023] The technical solutions described above can be combined with each other to realize more preferred combination solutions. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated herein and constitute a part of the detailed description. It should be noted that the detailed description provided below and the accompanying drawings are only used to illustrate the specific embodiments of the present application, and should not be considered as a limitation of the present application.

[0025] wherein:

[0026] Figure 1 A process flow chart of the method for directly leaching germanium from germanium-containing lignite according to an embodiment of the present application;

[0027] Figure 2 A comparison of infrared spectrograms of the residual coal obtained in Example 1 of the present application and the raw germanium-containing lignite. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present application are described in detail below, wherein the accompanying drawings constitute a part of the present application and are used to explain the principles of the present application together with the embodiments of the present application, but are not used to limit the scope of the present application.

[0029] An embodiment of the present application provides a method for directly leaching germanium from germanium-containing lignite, which comprises directly leaching germanium from germanium-containing lignite by leaching treatment with thionyl chloride as a leaching agent.

[0030] The method for directly leaching germanium from germanium-containing lignite according to an embodiment of the present application comprises the following steps:

[0031] S1, providing a first mixture, wherein the first mixture comprises germanium-containing lignite and thionyl chloride;

[0032] S2, performing leaching treatment on the first mixture to obtain a second mixture; and

[0033] S3, the second mixture is subjected to solid-liquid separation, and then the liquid phase is subjected to rotary evaporation to obtain a germanium-rich solid and regenerated thionyl chloride.

[0034] In an embodiment, the second mixture is treated to obtain residual coal and a thionyl chloride leaching phase; the acid oxygen-containing functional groups of the residual coal are removed by hydroxyl chlorination, and can be used as a precursor raw material of a coal-based ammoniated modified nitrogen fertilizer; the germanium-rich solid is highly enriched in germanium and has a simple composition, which is beneficial to subsequent germanium recovery.

[0035] The method for directly leaching germanium from germanium-containing lignite according to an embodiment of the present application is a method for mild germanium precipitation by thionyl chloride dehydroxylation. The method has a high germanium leaching rate, can realize efficient dissolution of dispersed metal germanium, has mild leaching process conditions, and the leaching agent thionyl chloride can be recycled and reused. Compared with existing methods, the method reduces the consumption of reagents and reduces the environmental hazards of the leaching process. The residual coal can be used as a precursor raw material of a coal-based ammoniated modified nitrogen fertilizer, rather than being subjected to combustion treatment, thereby reducing resource waste caused by combustion treatment.

[0036] In an embodiment, the germanium-containing lignite can be germanium-rich lignite, germanium-rich coal ash, germanium-rich coal gangue, etc., and has a germanium content of 20 μg / g or more.

[0037] In an embodiment, in S1, the germanium-containing lignite and the leaching agent thionyl chloride can be uniformly mixed in a certain proportion. Considering that too much thionyl chloride increases the cost, and too little thionyl chloride has a low contact efficiency with the coal. Therefore, the mass of thionyl chloride can be 5 to 20 times the mass of the germanium-containing lignite, for example, 6 times, 8 times, 10 times, 12 times, 14 times, or 16 times.

[0038] In an embodiment, in S2, considering that too high a temperature of the leaching treatment can cause decomposition of thionyl chloride, and too low a temperature cannot achieve efficient leaching. Therefore, the temperature of the leaching treatment can be 5 to 135°C, for example, 10°C, 30°C, 50°C, 70°C, 90°C, 100°C, 110°C, 120°C, or 130°C.

[0039] In an embodiment, in S2, considering that too long a leaching treatment time increases the time cost, and too short a leaching treatment time cannot completely leach germanium. Therefore, the leaching treatment time can be 0.5 to 12 h, for example, 1.5 h, 3.5 h, 5.5 h, 7.5 h, 9.5 h, or 11.5 h.

[0040] In an embodiment, in S2, the stirring rate of the leaching process is controlled to be 100-600 r / min, for example, 150 r / min, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 500 r / min, or 550 r / min, so as to ensure that the solid and liquid are in sufficient contact.

[0041] In an embodiment, in S2, a single-neck flask can be used as the container for the leaching process. Further, the first mixture can be placed in the single-neck flask, and the heating and stirring are started to heat the single-neck flask to the set temperature, and the leaching process is started.

[0042] In an embodiment, after the temperature in the single-neck flask is reduced to 20-28°C (for example, 22°C, 24°C, 25°C, or 26°C), the second mixture obtained by the leaching process is taken out of the single-neck flask.

[0043] In an embodiment, in S3, the second mixture can be subjected to solid-liquid separation by filtration or centrifugation to obtain a solid and a liquid. Further, the solid-liquid separation operation can be repeated 3-5 times, for example, 4 times.

[0044] In an embodiment, in S3, the obtained solid is washed with water and dried to obtain residual coal. The washing can be performed 3-6 times, for example, 4 times or 5 times. The liquid obtained by the separation and the solution obtained by washing the solid are both a germanium-rich solution. The germanium-rich solution is evaporated and dried to obtain a germanium-rich solid. The germanium-rich solid can be subjected to oxidation roasting to further enrich germanium, to obtain a germanium concentrate with simple composition and high germanium content. The germanium can be recovered by chlorination distillation.

[0045] The existing chlorination distillation technology generally uses coal fly ash produced by coal combustion as the raw material for germanium extraction. The leaching rate in the chlorination leaching process is low, a large amount of waste acid is produced, the germanium recovery rate is generally 40%-60%, and the combustion process pollutes the environment. In an embodiment of the present application, the germanium is directly leached from the germanium-containing lignite by using thionyl chloride as the leaching agent, and the germanium leaching rate can reach more than 99%. Compared with the traditional chlorination leaching, the reagent has a weak acid-base degree, the conditions are relatively mild, the germanium leaching rate is effectively improved, and a large amount of waste acid is not produced, thereby reducing the harm of the leaching process to the environment. The product can be used as a precursor raw material for coal-based ammoniated modified nitrogen fertilizer, thereby reducing resource waste and environmental pollution caused by the combustion process.

[0046] The method for directly leaching germanium from germanium-containing lignite according to an embodiment of the present application has a yield of the obtained coal of more than 95% after leaching operation, the coal-based organic matter can be effectively recovered, and the basic organic framework in the coal is not substantially damaged, and the residual coal can be used as a precursor raw material of coal-based ammoniated modified nitrogen fertilizer.

[0047] The method for directly leaching germanium from germanium-containing lignite according to an embodiment of the present application has a short process flow, high comprehensive utilization rate of resources, and small environmental pollution, the leaching agent thionyl chloride can be recycled and reused, the lignite is used in a high-value and clean manner, the cost is saved, the economic benefit is remarkable, and the main single-neck flask equipment used is mature and easy to be industrialized.

[0048] The method for directly leaching germanium from germanium-containing lignite according to an embodiment of the present application can efficiently and mildly leach germanium from germanium-containing lignite and realize comprehensive utilization of coal-based organic matter.

[0049] The method for directly leaching germanium from germanium-containing lignite according to an embodiment of the present application will be further described below in combination with the accompanying drawings and specific embodiments.

[0050] The calculation formula of the germanium leaching rate is:

[0051] m 残煤 m represents the mass of the residual coal, a 残煤 m represents the content of germanium in the residual coal, m 褐煤 m represents the mass of the lignite, a 褐煤 m represents the content of germanium in the lignite. The lignite refers to the germanium-containing lignite used as the raw material.

[0052] Example 1

[0053] The method for directly leaching germanium from germanium-containing lignite provided in this embodiment comprises the following steps:

[0054] S1, 5 g of germanium-containing lignite (germanium content 120 g / t) is weighed and uniformly mixed with thionyl chloride to obtain a first mixture; wherein the addition amount of thionyl chloride is 15 times the mass of the germanium-containing lignite;

[0055] S2, the first mixture is placed in a single-neck flask, heating and stirring are started, and the temperature is raised to 60 DEG C for leaching treatment, the stirring rate of the leaching treatment is 150 r / min, and the leaching time is 2 h, in this process, the germanium leaching enters the solution;

[0056] S3, after the leaching is completed, the mixture in the single-neck flask is taken out, and solid-liquid separation is repeatedly performed three times by suction filtration; the obtained solid after separation is washed with deionized water five times, and the residual coal is obtained after drying and weighing; the thionyl chloride leaching solution and the washing solution are respectively evaporated and dried to obtain a germanium-rich solid.

[0057] Figure 2 The infrared spectrum of the residual coal obtained in the present embodiment is compared with that of the raw material germanium-containing lignite. The infrared spectra of the two samples have high similarity, both reflecting the basic characteristics of lignite, indicating that the leaching of thionyl chloride on germanium-containing lignite does not destroy the basic organic framework in the coal.

[0058] The content of germanium in the residual coal after digestion is determined by ICP-OES, and the germanium leaching rate is calculated to be 99.22% according to formula (1); the mass of the residual coal is the mass of the recovered coal, and the coal recovery rate is 97.40%.

[0059] Example 2

[0060] The present embodiment provides a method for directly leaching germanium from germanium-containing lignite, comprising the following steps:

[0061] S1, take 10g of germanium-containing lignite (germanium content 120g / t) and uniformly mix with thionyl chloride to obtain a first mixture; wherein the addition amount of thionyl chloride is 8 times the weight of germanium-containing lignite;

[0062] S2, place the first mixture in a single-necked flask, start heating and stirring, and heat to 80℃ for leaching treatment; the stirring rate of leaching treatment is 400r / min, and the leaching time is 8h; in this process, germanium leaching enters the solution;

[0063] S3, after the leaching is completed, the mixture in the single-necked flask is taken out, and solid-liquid separation is repeated three times by suction filtration; the separated solid is washed with deionized water five times, and dried to obtain residual coal, which is weighed; the thionyl chloride leaching liquid and the washing liquid are evaporated and dried to obtain germanium-rich solid. The content of germanium in the residual coal after digestion is determined by ICP-OES, and the germanium leaching rate is calculated to be 99.39% according to formula (1); the mass of the residual coal is the mass of the recovered coal, and the coal recovery rate is 97.17%.

[0064] Example 3

[0065] The present embodiment provides a method for directly leaching germanium from germanium-containing lignite, comprising the following steps:

[0066] S1, take 10g of germanium-containing lignite (germanium content 120g / t) and uniformly mix with thionyl chloride to obtain a first mixture; wherein the addition amount of thionyl chloride is 8 times the weight of germanium-containing lignite;

[0067] S2, place the first mixture in a single-necked flask, start heating and stirring, and heat to 80℃ for leaching treatment; the stirring rate of leaching treatment is 400r / min, and the leaching time is 8h; in this process, germanium leaching enters the solution;

[0068] S3, after the end of leaching, the mixture in the single-necked flask was taken out, and solid-liquid separation was repeated three times by suction filtration; the obtained solid was washed with deionized water for five times, and dried to obtain residual coal, and the mass was weighed; the thionyl chloride leaching solution and the washing solution were evaporated and dried to obtain a germanium-rich solid. The content of germanium in the residual coal was determined by ICP-OES after digestion, and the germanium leaching rate was calculated according to formula (1) to be 99.58%; the mass of the residual coal was the mass of the recovered coal, and the coal recovery rate was 95.86%.

[0069] The inventors have conducted a large number of researches in the research process, and some of the ineffective schemes are listed as follows:

[0070] Comparative Example 1

[0071] The present comparative example provides a method for directly leaching germanium from germanium-containing lignite, comprising the following steps:

[0072] S1, 6g of germanium-containing lignite (germanium content 120g / t) was weighed and uniformly mixed with thionyl chloride to obtain a first mixture; wherein the addition amount of thionyl chloride was 2 times the weight of the germanium-containing lignite.

[0073] S2, the first mixture was placed in a single-necked flask, and heating and stirring were started, and the temperature was raised to 145℃ for leaching treatment, the stirring rate of the leaching treatment was 50r / min, and the leaching time was 0.1h; in this process, germanium leaching entered the solution.

[0074] S3, after the end of leaching, the mixture in the single-necked flask was taken out, and solid-liquid separation was repeated three times by suction filtration; the obtained solid was washed with deionized water for five times, and dried to obtain residual coal, and the mass was weighed; the thionyl chloride leaching solution and the washing solution were evaporated and dried to obtain a germanium-rich solid. The content of germanium in the residual coal was determined by ICP-OES after digestion, and the germanium leaching rate was calculated according to formula (1) to be 65.53%; the mass of the residual coal was the mass of the recovered coal, and the recovery rate was 85.86%.

[0075] Comparative Example 2

[0076] The present comparative example provides a method for directly leaching germanium from germanium-containing lignite, comprising the following steps:

[0077] S1, 4g of germanium-containing lignite (germanium content 120g / t) was weighed and uniformly mixed with thionyl chloride to obtain a first mixture; wherein the addition amount of thionyl chloride was 1 times the weight of the germanium-containing lignite.

[0078] S2, the first mixture was placed in a single-necked flask, and heating and stirring were started, and the temperature was raised to 140℃ for leaching treatment, the stirring rate of the leaching treatment was 80r / min, and the leaching time was 0.2h; in this process, germanium leaching entered the solution.

[0079] S3, after the end of leaching, the mixture in the single-necked flask was taken out, and solid-liquid separation was repeated three times by suction filtration; the obtained solid was washed with deionized water for five times, and dried to obtain residual coal, which was weighed; the thionyl chloride leaching solution and the washing solution were evaporated and dried to obtain a germanium-rich solid. The content of germanium in the residual coal was determined by ICP-OES after digestion, and the germanium leaching rate was calculated according to formula (1) to be 63.47%; the mass of the residual coal was the mass of the recovered coal, and the coal recovery rate was 87.86%.

[0080] The above merely describes the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements easily thought of by those skilled in the art within the technical range disclosed by the present application should be encompassed within the protection scope of the present application.

Claims

1. A method for direct leaching of germanium from germanium-containing lignite, characterized in that, The germanium is leached from the germanium-containing lignite by leaching treatment with thionyl chloride as leaching agent; The method comprises the following steps: S1, providing a first mixture, wherein the first mixture comprises germanium-containing lignite and thionyl chloride; S2, subjecting the first mixture to leaching treatment to obtain a second mixture; and S3, subjecting the second mixture to solid-liquid separation to obtain residual coal and thionyl chloride leaching solution, and subjecting the thionyl chloride leaching solution to rotary evaporation to obtain regenerated thionyl chloride and germanium-rich solid; In the first mixture, the mass of the thionyl chloride is 5-20 times the mass of the germanium-containing lignite; In the S2, the temperature of the leaching treatment is 60-135°C, and the time of the leaching treatment is 0.5-12 h. In the S2, the stirring rate of the leaching treatment is 100-600 r / min. The germanium leaching rate is more than 99%, and the yield of the obtained coal is more than 95%.

2. The method of claim 1, wherein, In the first mixture, the mass of the thionyl chloride is 8-20 times the mass of the germanium-containing lignite.

3. The method of claim 1, wherein, In the S2, the temperature of the leaching treatment is 60-100°C.

4. The method of claim 1, wherein, In the S2, the time of the leaching treatment is 0.5-8 h.

5. The method of claim 1, wherein, In the S2, the stirring rate of the leaching treatment is 150-600 r / min.

6. The method of claim 1, wherein, The residual coal is used as a precursor raw material of coal-based ammoniated modified nitrogen fertilizer.

7. The method of claim 1, wherein, The solid-liquid separation is performed by suction filtration or centrifugation.

8. The method according to claim 6 or 7, characterized in that, The germanium-rich solid is used as a subsequent germanium extraction raw material.

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