CN114262794A - Method for comprehensively extracting valuable components such as rare elements and organic matters from lignite - Google Patents
Method for comprehensively extracting valuable components such as rare elements and organic matters from lignite Download PDFInfo
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Abstract
The invention discloses a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, which mainly comprises the following steps: (1) crushing raw coal; (2) oxidation pretreatment, namely primarily releasing rare metals such as germanium, gallium, rare earth and the like contained in the lignite; (3) heating alkali treatment is carried out, rare metals in the lignite are deeply released, and alkali-soluble organic matters in the lignite are dissolved; (4) controlling the potential and carrying out acid treatment, precipitating acid-insoluble organic matters from the alkali treatment solution, and promoting the analysis of rare metals complexed by the organic matters; (5) waste water treatment and circulation, wherein the neutralization and circulation of residual acid liquor after rare metal extraction and residual alkali liquor in the alkali treatment process are carried out in the treatment process; according to the invention, on the premise of considering the production cost, rare metals in the lignite are extracted, meanwhile, the productization of residual organic matters in the lignite is realized, the residual solid is low in quantity and easy to be used as building materials, most of residual acid-base solution in the treatment process can be treated in the process and recycled, and the process flow has the advantages of low environmental pollution, high economic benefit and high comprehensive utilization rate of valuable components.
Description
Technical Field
The invention discloses a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, and relates to the technical field of comprehensive recovery and treatment of solid materials.
Background
Lignite is brown black low-grade coal with coalification degree between peat and bituminous coal, is humus coal formed by diagenetic action of peat, and has the lowest coalification degree. Lignite has the advantages of cleanness, low volatility and low sulfur, but has the disadvantages of high humidity, low ignition point and large carbon dioxide emission. The reserve of lignite resources in China is rich, about 2118 million tons accounts for about 13 percent of the reserve of coal in China, but the lignite is regarded as poor fuel due to the defects of high moisture, low heat value, easiness in spontaneous combustion and the like, and a non-fuel utilization technology of lignite is very necessary to be developed to realize high added value utilization of lignite.
Meanwhile, the lignite is rich in organic matter resources, and oxygen-containing chemicals can be obtained from the lignite. The humic acid in the organic matters can be used as a drilling mud regulator, an industrial water stabilizer, a cement water reducing agent, a boiler scale remover, an ore flotation agent, a waste gas and wastewater treatment agent, a compound fertilizer and the like, can be widely applied to various fields of agriculture, forestry, grazing, petroleum, chemical industry, building materials, medical sanitation, environmental protection and the like, shows strong vitality and has very wide prospect. In addition, organic matters in the lignite are easy to adsorb rare metals such as germanium, gallium, rare earth and the like. Taking germanium as an example, the reserve can be calculated when the content of germanium in the lignite is more than 20ppm, so that the lignite has a certain extraction value, the reserve of the germanium-containing lignite in inner Mongolia areas is large, the germanium grade can reach 100-200 ppm, the reserve of the germanium is estimated to exceed 4000 tons, and the reserve of the germanium is estimated to be 2177 tons in the lignite in Yunnan Shanghai, Shandong, Manhui and other Gal areas. Therefore, the comprehensive utilization of the lignite is enhanced, the comprehensive recycling of valuable resources such as rare elements, organic matters, mineral substances and the like in the lignite is enhanced, the utilization value of coal is improved, and the method has important practical significance.
However, the comprehensive utilization rate of valuable components in lignite is low at present, few researches on extraction of rare elements in raw lignite coal are carried out, most researches are carried out around extraction of germanium in soot and gallium in fly ash, the acid content is high in the wet extraction process at present, the cost is high, and the problems of low volatilization rate, long volatilization time and difficult guarantee of atmosphere exist in the pyrogenic extraction process at present. However, research on extracting rare earth from lignite is still in the beginning stage, and therefore, research and development of a method for comprehensively extracting valuable components such as rare elements and organic matters from lignite, which has high economic benefit and little environmental pollution, are urgently needed.
Disclosure of Invention
The invention aims to provide a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite. Aiming at the problems of low comprehensive utilization rate of valuable components in the lignite, more acid content and higher cost in the wet extraction process of rare elements, and low volatilization rate, long volatilization time and difficult guarantee of atmosphere in the pyrogenic extraction process, the invention provides the process procedures of raw coal crushing, oxidation pretreatment, heating alkali treatment, potential control acid treatment, wastewater treatment and circulation on the premise of considering the production cost aiming at the characteristics of the lignite containing the rare elements, and provides a promising method for the comprehensive extraction of the valuable components such as the rare elements, organic matters and the like in the lignite.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, which mainly comprises the following steps:
(1) selection of raw materials
Selecting-80-mesh lignite as a raw material, wherein the raw material contains rare earth elements and/or rare metal elements; the rare metal element is at least one of germanium, gallium and vanadium;
(2) oxidative pretreatment
Mixing raw material lignite with an oxidation pretreatment agent with the mass concentration of 2% -10% according to the solid-to-liquid ratio of 1: 3-1: 8, preferably 1: 5-1: 8, and reacting for more than or equal to 0.5h after mixing; primarily releasing rare metal elements and/or rare earth elements contained in the lignite by mixing; after solid-liquid separation, obtaining a first-stage dissolution liquid and a first-stage dissolution residual solid;
(3) thermal alkali treatment
Mixing the first-stage dissolved residual solid obtained in the step (2) with an alkali solution with the mass concentration of 2% -5%, wherein the solid-liquid ratio is 1: 10-1: 20, the solution temperature is controlled to be 80-95 ℃, the treatment time is at least 0.5h, preferably 0.5-3.5 h, and further preferably 0.5 h-2 h, the rare metal elements and/or rare earth elements in the lignite are deeply released, and alkali-soluble organic matters in the lignite are dissolved; after solid-liquid separation, obtaining second-stage dissolved residual solid and second-stage dissolved liquid;
(4) potential controlled acid treatment
Adding a complexing agent with the mass ratio of 0.1-1% into the second-stage dissolving liquid obtained in the step (3), adding an acid solution with the mass concentration of 5-10%, controlling the pH value of the solution to be 1.5-2.0, promoting the analysis of rare metal elements and/or rare earth elements complexed by organic matters, and precipitating acid-insoluble organic matters; after solid-liquid separation, a third stage dissolution liquid and a third stage dissolution residual solid are obtained.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, which is characterized in that under the condition of no bubble generation, an oxidation pretreatment agent with the mass concentration of 2-10% is added into raw material lignite (the pretreatment agent is preferably slowly or dropwise added into the lignite in a mixing mode during industrial application), and the raw material lignite is reacted for 0.5-16 h, preferably 0.5-10 h at the temperature of 25-75 ℃. So as to primarily release rare metals such as germanium, gallium, rare earth and the like contained in the lignite; after solid-liquid separation, the first-stage dissolved liquid is a rare metal solution which can be used for continuously extracting rare metals, and the first-stage dissolved residual solid is continuously treated. In industrial application, because the water content of the lignite is usually 15% -35%, the water content can be reduced to below 13% by airing and other methods before crushing; and then crushing the dried lignite.
Preferably, the raw material lignite used in the step (2) of the present invention has a particle size of 80 to 200 mesh.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, wherein an oxidation pretreatment agent is formed by mixing an oxidant and a wetting defoaming agent, and the wetting defoaming agent accounts for 0.1-1%, preferably 0.1-0.8% and more preferably 0.2-0.5% of the total mass of the oxidation pretreatment agent; the oxidant is selected from one or more of hydrogen peroxide, perborate, persulfate, perphosphate, nitric acid, chlorate, hypochlorite and chlorine dioxide, the wetting defoaming agent is selected from one or more of tributyl phosphate, methanol and ethanol, the dosage of the wetting defoaming agent is not too much, and the solution is layered due to the excessive dosage of the tributyl phosphate, so that the element content in the aqueous solution is reduced; the detection result of rare elements is influenced by excessive using amount of methanol and ethanol, and tributyl phosphate and ethanol are preferred.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, wherein in the step (3), alkali solution used in the alkali heating treatment is one or more selected from sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, wherein at least one of tripolyphosphate, polyphosphate and pyrophosphate with the mass percentage of 10-30% is added into an alkaline solution.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, wherein the residual solid dissolved out in the second stage mainly comprises iron, silicon, calcium and aluminum and can be used for preparing building raw materials, and the dissolved liquid in the second stage is continuously treated.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, wherein in the step (4), a complexing agent is selected from one or more of pyrocatechol, N-hydroxyphthalimide, tartaric acid and hydroximic acid.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, which is characterized in that filter cake washing acid liquor or alkali liquor generated in the treatment processes from (2) to (4), residual solution after metal elements are extracted from first-stage dissolution liquor and residual solution after metal elements are extracted from third-stage dissolution liquor are neutralized according to the similarity degree of acid and alkali concentrations in the liquor until the pH value of the neutralized liquor reaches 5-8, and the clarified neutralized liquor is continuously returned to the process flow for recycling, so that the cost of chemicals for wastewater treatment is reduced, and low-concentration rare metals remaining in the liquor are circularly enriched. Through the treatment, on one hand, the medicament cost of wastewater treatment is reduced, and on the other hand, the residual low-concentration rare metal in the solution is circularly enriched. Thereby realizing the recycling of water and other substances.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, wherein when the mass content of germanium in raw materials is 100-110 ppm and the mass content of rare earth is 55-60ppm, the temperature is controlled to be 25-30 ℃ during oxidation pretreatment, and the subsequent process is matched; the leaching rate of germanium is more than 85%, the leaching rate of rare earth is more than 70%, and the yield of organic matters is 36-37%. The invention realizes the rapid and efficient dissolution of rare metals and rare earth metals at room temperature for the first time.
The invention relates to a method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite, wherein the dissolution rate of rare metals is more than or equal to 85 percent; the rare earth leaching rate is more than 70 percent.
After optimization, the method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite has the dissolution rate of the rare metals of more than or equal to 89%; the rare earth leaching rate is more than 75 percent.
After further optimization, the method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite has the dissolution rate of rare metals of more than or equal to 90 percent; the rare earth leaching rate is more than 80 percent.
After further optimization, the method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite has the dissolution rate of the rare metals of more than or equal to 93 percent; the leaching rate of rare earth is more than 85 percent.
Principles and advantages
The invention relates to a comprehensive extraction process designed on the basis of the composition characteristics of organic matters and mineral substances in lignite and the occurrence states of rare elements such as germanium, rare earth and the like. A part of germanium, rare earth and the like in the lignite are combined with organic matters, a part of germanium, rare earth and the like are adsorbed on clay minerals, and a small amount of germanium, rare earth and the like are combined in the minerals.
According to the method, rare elements such as germanium, rare earth and the like which are combined with organic matters and adsorbed on clay minerals are resolved from the organic matters and the clay minerals by adopting a proper oxidation and low acid leaching method, and in the process, in order to better wet lignite and reduce the influence of bubble accumulation in the oxidation process, an oxidant and a wetting defoaming agent are adopted as oxidation pretreatment agents, so that the contact angle of the lignite and the surface tension of the solution are reduced, the wetting performance of the lignite is improved, and the generation amount of bubbles is reduced; meanwhile, the pretreating agent is added into the lignite in a slow speed or dropwise adding mode, so that on one hand, the extraction rate of rare elements is improved, on the other hand, the sudden generation of bubbles is avoided, and the control of the process is facilitated. The obtained first-stage dissolution liquid is rare metal solution, has low impurity content, and can continuously extract rare metal.
The oxidation pretreatment process plays a role in resolving and releasing rare elements on one hand, and can also activate organic matters in a section of dissolved residual solids on the other hand. The solid is treated by heating alkali, most alkali-soluble organic matters in the solid can be dissolved, and meanwhile, rare metal elements which are tightly combined with the organic matters can be released to enter a second section of solution; the residual solid dissolved out in the second stage mainly contains iron, silicon, calcium and aluminum, and can be continuously processed to be used as an auxiliary raw material of building materials to prepare building materials, ceramsite, geopolymer and the like.
Aiming at the organic matters in the second section of dissolving liquid, the organic matters can be precipitated by adding acid to control the potential, and humic acid and the like can be continuously prepared by purification, but considering that the organic matters such as the humic acid and the like have strong adsorption capacity to rare elements such as germanium, rare earth and the like, a selective complexing agent needs to be added to compete and chelate the rare elements, the loss of the rare elements in the organic matter precipitation process is reduced, a third section of dissolving liquid containing the rare metal elements is obtained, and the rare metals are continuously extracted.
In order to consider the production cost of the process, the residual solution after the rare metals are extracted from the filter cake washing acid liquor or alkali liquor and the leaching liquor generated in each process step is neutralized according to the similar degree of the acid and alkali concentrations in the liquid, and the clarified neutralization liquor is continuously returned to the process flow for recycling, so that the cost of the wastewater treatment agent can be reduced, and the residual low-concentration rare metals in the solution can be circularly enriched.
The method has the advantages that rare metals in the lignite are extracted while the productization of residual organic matters in the lignite is realized aiming at the problems of high cost, heavy pollution and poor economical efficiency in the single extraction and utilization process of valuable components in the lignite, the residual solid is low in quantity and easy to build materials, most of residual acid-base solution in the treatment process can be treated in a flow and recycled, and the process flow has the advantages of low environmental pollution, high economic benefit and high comprehensive utilization rate of the valuable components.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a schematic diagram of a process flow for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Aiming at lignite internally containing 106ppm of germanium and 58ppm of rare earth, firstly crushing raw coal into small particles below 80 meshes, then slowly dripping an oxidation pretreatment agent which is formed by mixing hydrogen peroxide and methanol according to the mass ratio of 100:1 and has the mass concentration of 10% into the lignite, wherein the solid-liquid ratio is 1:3, the solution temperature is controlled at 25 ℃, stirring for 10 hours, and carrying out solid-liquid separation to obtain a first section of dissolution liquid containing rare elements, wherein the first section of dissolution liquid can be used for continuously extracting rare metals; washing the first stage residual solid after solid-liquid separation, adding 5% sodium hydroxide solution (10% of which is sodium tripolyphosphate) with a solid-liquid ratio of 1:10, controlling the solution temperature at 95 ℃, treating for 0.5h, and performing solid-liquid separation to obtain a second stage dissolved residual solid which can be continuously used for preparing building raw materials; adding tartaric acid and N-hydroxyphthalimide (the mass ratio is 1:1) which are 0.1 percent of the mass ratio into a second-stage dissolution liquid containing organic matters after solid-liquid separation as a complexing agent, continuously adding hydrochloric acid with the mass concentration of 10 percent, and controlling the final pH value of the solution to be 1.5; then carrying out solid-liquid separation to obtain the residual solid (organic solid) dissolved out in the third stage and the dissolved liquid in the third stage; after solid-liquid separation and washing of the separated organic matter, humic acid can be continuously prepared by purification, and rare elements can be continuously extracted from the third-stage dissolution liquid; and collecting the filter cake washing acid liquor, alkali liquor and residual solution after extracting rare metals in the technical process, neutralizing according to the similarity degree of the acid and alkali concentrations in the liquid, and returning the neutralized liquid as supplemented water to the process for recycling. In this example, the dissolution rate of germanium was 87.38%, the dissolution rate of rare earth was 71.43%, and the yield of organic matter was 37.06%.
Comparative example 1
The other conditions were the same as in example 1 except that: methanol is not added into the oxidation pretreating agent, the dissolution rate of germanium is 84.61%, the dissolution rate of rare earth is 65.77%, and the yield of organic matters is 35.82%.
Comparative example 2
The other conditions were the same as in example 1 except that: after washing the residual solid in the first stage, heating to alkali at 60 deg.C; finally, the dissolution rate of germanium is 83.03%, the dissolution rate of rare earth is 60.61%, and the yield of organic matters is 31.08%.
Comparative example 3
The other conditions were the same as in example 1 except that: only hydrochloric acid with the mass concentration of 10% is added into the second-stage dissolution liquid containing the organic matters after solid-liquid separation, and the final pH value of the solution is controlled to be 1.5; finally, the dissolution rate of germanium is 84.40%, the dissolution rate of rare earth is 66.13%, and the yield of organic matters is 34.43%.
Comparative example 4
The other conditions were the same as in example 1 except that: and (3) adding 0.1% tartaric acid serving as a complexing agent into the second-stage leaching solution containing the organic matters after solid-liquid separation, continuously adding hydrochloric acid with the mass concentration of 10%, and controlling the final pH value of the solution to be 3.5, wherein finally, the leaching rate of germanium is 83.58%, the leaching rate of rare earth is 63.39%, and the yield of the organic matters is 32.29%.
Example 2
Aiming at lignite internally containing 212ppm of germanium and 89ppm of rare earth, firstly crushing raw coal into small particles below 200 meshes, then slowly dripping an oxidation pretreatment agent which is formed by mixing nitric acid and tributyl phosphate according to the mass ratio of 1000:1 and has the mass concentration of 2% into the lignite, wherein the solid-liquid ratio is 1:8, the solution temperature is controlled at 75 ℃, the treatment time is 0.5h, and a first-stage dissolution liquid containing rare elements is obtained after solid-liquid separation and can be used for continuously extracting rare metal; washing the first-stage residual solid after solid-liquid separation, adding 2% potassium hydroxide solution (30% of which is sodium pyrophosphate), wherein the solid-liquid ratio is 1:20, the solution temperature is controlled at 80 ℃, the treatment time is 2 hours, and the second-stage dissolved residual solid is obtained after solid-liquid separation and can be continuously used for preparing building raw materials; adding catechol and hydroximic acid (in a mass ratio of 4:1) which are 1% in mass ratio into the two-stage dissolution liquid containing the organic matters after solid-liquid separation as complexing agents, continuously adding hydrochloric acid with a mass concentration of 5%, controlling the final pH value of the solution to be 2.0, continuously purifying the precipitated organic matters after solid-liquid separation and washing to prepare humic acid, and continuously extracting rare elements from the three-stage dissolution liquid; and collecting the filter cake washing acid liquor, alkali liquor and residual solution after extracting rare metals in the technical process, neutralizing according to the similarity degree of the acid and alkali concentrations in the liquid, and returning the neutralized liquid as supplemented water to the process for recycling. In this example, the dissolution rate of germanium was 92.13%, the dissolution rate of rare earth was 81.86%, and the yield of organic matter was 41.25%.
Example 3
Aiming at some lignite containing 159ppm of germanium and 160ppm of rare earth in Yunnan, firstly crushing raw coal into small particles below 100 meshes, then slowly dripping an oxidation pretreatment agent which is formed by mixing sodium perborate, sodium persulfate, sodium superphosphate and ethanol according to the mass ratio of 30:60:15:1 and has the mass concentration of 5% into the lignite, wherein the solid-liquid ratio is 1:5, the solution temperature is controlled at 25 ℃, the treatment time is 3.5 hours, and a section of dissolution liquid containing rare elements is obtained after solid-liquid separation and can be used for continuously extracting rare metal; washing the first-stage residual solid after solid-liquid separation, adding 3% sodium carbonate solution (20% of which is sodium polyphosphate) at a solid-liquid ratio of 1:15, controlling the solution temperature at 90 ℃, treating for 1.0h, and performing solid-liquid separation to obtain a second-stage dissolved residual solid which can be continuously used for preparing building raw materials; adding tartaric acid with the mass ratio of 1% into the second-stage dissolution liquid containing the organic matters after solid-liquid separation as a complexing agent, continuously adding hydrochloric acid with the mass concentration of 10%, controlling the final pH value of the solution to be 1.5, continuously purifying the precipitated organic matters after solid-liquid separation and washing to prepare humic acid, and continuously extracting rare elements from the third-stage dissolution liquid; and collecting the filter cake washing acid liquor, alkali liquor and residual solution after extracting rare metals in the technical process, neutralizing according to the similarity degree of the acid and alkali concentrations in the liquid, and returning the neutralized liquid as supplemented water to the process for recycling. In this example, the dissolution rate of germanium was 89.46%, the dissolution rate of rare earth was 75.19%, and the yield of organic matter was 35.12%.
Comparative example 5
The other conditions were the same as in example 2 except that: tartaric acid with the mass concentration of 0.5 percent is not added into the second-stage leaching solution containing the organic matters after the solid-liquid separation to serve as a complexing agent, the leaching rate of the germanium is 80.11 percent, the leaching rate of the rare earth is 62.37 percent, and the yield of the organic matters is 34.09 percent.
Example 4
Aiming at certain lignite containing 576ppm of germanium, 230ppm of vanadium and 208ppm of rare earth in Yunnan, firstly crushing raw coal into small particles below 200 meshes, then slowly dripping an oxidation pretreatment agent which is formed by mixing sodium chlorate, sodium hypochlorite, chlorine dioxide and ethanol according to the mass ratio of 20:70:10:1 and has the mass concentration of 6% into the lignite, wherein the solid-liquid ratio is 1:4, the solution temperature is controlled at 55 ℃, the treatment time is 3.0h, and a first-stage dissolution liquid containing rare elements is obtained after solid-liquid separation and can be used for continuously extracting rare metals; washing the first-stage residual solid after solid-liquid separation, adding 2% potassium carbonate solution (30% of which is sodium triphosphate) with a solid-liquid ratio of 1:12, controlling the solution temperature at 85 ℃, treating for 1.5h, and performing solid-liquid separation to obtain a second-stage dissolved residual solid which can be continuously used for preparing building raw materials; adding N-hydroxyphthalimide with the mass ratio of 0.5 percent into the second-stage dissolution liquid containing the organic matters after the solid-liquid separation as a complexing agent, continuously adding hydrochloric acid with the mass concentration of 5 percent, controlling the final pH value of the solution to be 2.0, continuously purifying the precipitated organic matters after the solid-liquid separation and washing to prepare humic acid, and continuously extracting rare elements from the third-stage dissolution liquid; and collecting the filter cake washing acid liquor, alkali liquor and residual solution after extracting rare metals in the technical process, neutralizing according to the similarity degree of the acid and alkali concentrations in the liquid, and returning the neutralized liquid as supplemented water to the process for recycling. In this example, the dissolution rate of germanium was 93.54%, the dissolution rate of vanadium was 70.13%, the dissolution rate of rare earth was 86.71%, and the yield of organic matter was 36.25%.
While the invention has been described with reference to specific preferred embodiments and examples, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A method for comprehensively extracting valuable components such as rare elements, organic matters and the like from lignite is characterized by mainly comprising the following steps:
(1) selection of raw materials
Selecting-80-mesh lignite as a raw material, wherein the raw material contains rare earth elements and/or rare metal elements; the rare metal element is at least one of germanium, gallium and vanadium;
(2) oxidative pretreatment
Mixing raw material lignite with an oxidation pretreatment agent with the mass concentration of 2% -10% according to the solid-to-liquid ratio of 1: 3-1: 8, and reacting for more than or equal to 0.5h after mixing; primarily releasing rare metal elements and/or rare earth elements contained in the lignite by mixing; after solid-liquid separation, obtaining a first-stage dissolution liquid and a first-stage dissolution residual solid;
(3) thermal alkali treatment
Mixing the first-stage dissolved residual solid obtained in the step (2) with an alkali solution with the mass concentration of 2% -5%, wherein the solid-liquid ratio is 1: 10-1: 20, the solution temperature is controlled at 80-95 ℃, the treatment time is 0.5-2 h, rare metal elements and/or rare earth elements in the lignite are deeply released, and alkali-soluble organic matters in the lignite are dissolved; after solid-liquid separation, obtaining second-stage dissolved residual solid and second-stage dissolved liquid;
(4) potential controlled acid treatment
Adding a complexing agent with the mass ratio of 0.1-1% into the second-stage dissolving liquid obtained in the step (3), adding an acid solution with the mass concentration of 5-10%, controlling the pH value of the solution to be 1.5-2.0, promoting the analysis of rare metal elements and/or rare earth elements complexed by organic matters, and precipitating acid-insoluble organic matters; after solid-liquid separation, a third stage dissolution liquid and a third stage dissolution residual solid are obtained.
2. The method for comprehensively extracting valuable components such as rare elements and organic matters from lignite according to claim 1, which is characterized in that:
adding an oxidation pretreating agent with the mass concentration of 2-10% into the raw material lignite under the condition of no bubble generation, and reacting for 0.5-16 h, preferably 0.5-10 h at the temperature of 25-75 ℃. So as to primarily release rare metals such as germanium, gallium, rare earth and the like contained in the lignite; after solid-liquid separation, the first-stage dissolved liquid is a rare metal solution which can be used for continuously extracting rare metals, and the first-stage dissolved residual solid is continuously treated.
3. The method for comprehensively extracting valuable components such as rare elements and organic matters from lignite according to claim 1, which is characterized in that: the oxidation pretreating agent is formed by mixing an oxidant and a wetting defoaming agent, wherein the wetting defoaming agent accounts for 0.1-1% of the total mass of the oxidation pretreating agent; the oxidant is selected from one or more of hydrogen peroxide, perborate, persulfate, perphosphate, nitric acid, chlorate, hypochlorite and chlorine dioxide, and the wetting defoaming agent is selected from one or more of tributyl phosphate, methanol and ethanol.
4. The method for comprehensively extracting valuable components such as rare elements and organic matters from lignite according to claim 1, which is characterized in that: the alkali solution used in the alkali heating treatment in the step (3) is one or more selected from sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.
5. The method for comprehensively extracting valuable components such as rare elements and organic matters from lignite according to claim 1, which is characterized in that: at least one of tripolyphosphate, polyphosphate and pyrophosphate with the mass percentage of 10-30% is added into the alkaline solution.
6. The method for comprehensively extracting valuable components such as rare elements and organic matters from lignite according to claim 1, which is characterized in that: in the step (4), the complexing agent is selected from one or more of catechol, N-hydroxyphthalimide, tartaric acid and hydroximic acid.
7. The method for comprehensively extracting valuable components such as rare elements and organic matters from lignite according to claim 1, which is characterized in that:
and (3) washing acid liquor or alkali liquor of the filter cakes generated in the treatment processes from (2) to (4), and residual solution after the metal element is extracted from the first section of dissolving liquid and residual solution after the metal element is extracted from the third section of dissolving liquid, neutralizing according to the similar degree of acid and alkali concentrations in the liquid until the pH value of the neutralized liquid is 5-8, and continuously returning the clarified neutralized liquid to the process flow for recycling, so that the cost of the wastewater treatment agent is reduced, and residual low-concentration rare metal in the solution is circularly enriched.
8. The method for comprehensively extracting valuable components such as rare elements and organic matters from lignite according to claim 1, which is characterized in that:
the first-stage dissolving liquid is a solution containing rare metal elements and/or rare earth elements and is used for continuously extracting the rare metal elements and/or the rare earth elements, and the first-stage dissolving residual solids are used for continuously treating.
9. The method for comprehensively extracting valuable components such as rare elements and organic matters from lignite according to any one of claims 2 to 8, wherein the method comprises the following steps:
the dissolution rate of rare metals is more than or equal to 85 percent; the rare earth leaching rate is more than 70 percent.
10. The method for comprehensively extracting valuable components such as rare elements and organic matters from lignite according to claim 9, which is characterized in that: the dissolution rate of rare metals is more than or equal to 89 percent; the rare earth leaching rate is more than 75 percent.
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| US4094753A (en) * | 1977-06-01 | 1978-06-13 | Cominco Ltd. | Recovery of gallium from gallium compounds |
| CN101423536A (en) * | 2008-12-02 | 2009-05-06 | 昆明理工大学 | Method for preparing humic acid and salt thereof by oxidation and degradation of brown coal |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4094753A (en) * | 1977-06-01 | 1978-06-13 | Cominco Ltd. | Recovery of gallium from gallium compounds |
| CN101423536A (en) * | 2008-12-02 | 2009-05-06 | 昆明理工大学 | Method for preparing humic acid and salt thereof by oxidation and degradation of brown coal |
Non-Patent Citations (2)
| Title |
|---|
| KUPPUSAMY, VK ET AL: "Simultaneous Extraction of Clean Coal and Rare Earth Elements From Coal Tailings Using Alkali-Acid Leaching Process", 《JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME》 * |
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