Method for gradient recovery of rare metals from coal gangue and simultaneous synthesis of sodalite

Abstract

The present application belongs to the technical field of secondary utilization of industrial solid waste resources, and particularly relates to a method for gradient recovery of rare metals from coal gangue and synchronous synthesis of sodalite. The method comprises the following steps: firstly, grinding and sieving the coal gangue, and then mixing the coal gangue with a chlorinating agent and an activating agent in a certain proportion; secondly, carrying out multi-stage gradient selective chlorination roasting at temperatures of 500-800 DEG C, 600-1000 DEG C and 800-1200 DEG C, respectively; thirdly, obtaining solid products of gallium chloride, titanium chloride and yttrium chloride by cooling and dust collecting the volatilized gas; and finally, realizing gradient asynchronous recovery and enrichment of gallium, titanium and yttrium, and synchronous conversion of tailings into environmental functional material sodalite, so as to realize high-value, whole-quantity and tailings-free full-component utilization of rare and dispersed coal gangue, and to have important significance for realizing whole-quantity utilization of coal gangue and sustainable development of the coal industry.

Description

Technical Field

[0001] This invention belongs to the field of secondary utilization technology of industrial solid waste resources, specifically relating to a method for gradient recovery of rare metals from coal gangue and simultaneous synthesis of sodalite. Background Technology

[0002] Currently, coal gangue is mainly used in power generation, building materials production, and land reclamation. Traditional processing and disposal methods not only lead to a significant waste of resources, but also result in a still low utilization rate of coal gangue. To achieve rational resource utilization and sustainable ecological development, the high-value and full-component utilization of coal gangue is urgently needed.

[0003] Sodalite, as a typical SOD-type aluminosilicate molecular sieve, exhibits broad application prospects and potential. In the removal of heavy metal ions from wastewater, sodalite's unique structure has proven to be remarkably effective. Simultaneously, by modulating the structure and function of sodalite, it can play an important role in high-tech fields such as semiconductors, hydrogen storage, and catalysts, or be applied to novel luminescent materials and as a matrix for immobilizing hazardous waste. The preparation of sodalite from silica-alumina minerals in coal gangue via a high-temperature solid-phase chlorination reaction is of significant importance and feasibility.

[0004] To fully recover rare and dispersed metals and aluminum-silicon components from coal gangue, a gradient chlorination roasting process using a compound chlorinating agent and activator was employed to simultaneously recover rare and dispersed metals during the preparation of sodalite. This preparation process not only achieves comprehensive recovery of rare and dispersed metals but also enables the quantification, full-component, and high-value utilization of coal gangue, providing an effective pathway for the efficient utilization of various components in coal gangue and offering significant environmental and economic benefits. However, a method for synthesizing sodalite through chlorination roasting of coal gangue while simultaneously recovering rare and dispersed metals has not yet been reported. Summary of the Invention

[0005] This invention addresses the problems of high cost, low efficiency, low added value, and complex processes in the current bulk utilization of coal gangue. It provides a method for recovering rare and dispersed metals from coal gangue through gradient chlorination roasting and simultaneously synthesizing sodalite. This method recovers high-value rare and dispersed metals from coal gangue and simultaneously activates it through chlorination to prepare sodalite, achieving high-value and bulk utilization of coal gangue. Compared with existing methods for resource recovery and utilization of coal gangue, this invention is simpler, more economical and environmentally friendly, and achieves more thorough comprehensive utilization of solid waste resources.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] A method for recovering rare and dispersed metals from coal gangue via gradient chlorination and simultaneously synthesizing sodalite includes the following steps:

[0008] (1) After mixing coal gangue with chlorinating agent and activator in proportion, the temperature is controlled at 500-800℃ for chlorination roasting, and gallium chloride volatile phase cooling particles are collected.

[0009] (2) After the chlorination roasting in step (1) is completed, control the temperature to 600-1000℃ and continue chlorination roasting, and collect the volatile phase cooling particles of titanium chloride.

[0010] (3) After the chlorination roasting in step (2) is completed, control the temperature to 800-1200℃ and continue the chlorination roasting, and collect the volatile phase cooling particulate matter yttrium chloride;

[0011] (4) After the chlorination roasting in step (3) is completed, collect the solid reaction product, sodalite.

[0012] In the above technical solution, under gradient chlorination temperature, kaolinite in coal gangue undergoes two stages: activation (kaolinite → aluminum silicate) and transformation (aluminum silicate → nepheline → sodalite).

[0013] Furthermore, in step (1), the chlorinating agent is selected from at least one of ferric chloride, calcium chloride, ammonium chloride, sodium chloride, carbon tetrachloride, and magnesium chloride.

[0014] Further, in step (1), the activator is selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, and potassium bicarbonate.

[0015] Furthermore, in steps (2), (3), and (4), the chlorination roasting time is 0.5 to 3 hours.

[0016] Furthermore, in step (1), the amount of chlorinating agent used is 5% to 30% of the mass of coal gangue.

[0017] Furthermore, in step (1), the amount of activator used is 15% to 45% of the mass of coal gangue.

[0018] Furthermore, in step (1), the coal gangue is clayey coal gangue containing rare and dispersed metals; the carbon content in the coal gangue is 2% to 15%; and the coal gangue includes one or more of the rare and dispersed elements Ti, Li, and Y.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. The method of the present invention can not only solve the problem of coal gangue accumulation, but also recover and utilize rare and dispersed metals and kaolinite in coal gangue in a high-value manner, fully recover and utilize all elemental components in coal gangue, and realize the high-value, whole-component, and tailless utilization of coal gangue.

[0021] 2. The method of this invention innovatively combines the chlorination roasting of coal gangue with the activation roasting process of coal gangue. By controlling the ratio of chlorinating agent to activating agent during the gradient chlorination process, it can not only realize the volatilization and recovery of rare and dispersed metals, but also simultaneously destroy the silica and kaolinite phase structure in coal gangue. The activated coal gangue chlorination tailings are used to prepare sodalite, which effectively reduces the high energy consumption and high cost caused by secondary roasting and simplifies the utilization process.

[0022] 3. The method of the present invention optimizes the composition of chlorinating agent and activator in the entire coal gangue recycling process, and all coal gangue and external raw materials can be converted into the final product. The raw material utilization rate is high, and no waste residue is generated. It forms a system for the full-element resource utilization of coal gangue, and achieves clean production and near-zero emissions in the coal gangue resource utilization process. Attached Figure Description

[0023] Figure 1 Flowchart of the process for recovering rare and dispersed metals and simultaneously synthesizing sodalite from coal gangue by gradient chlorination roasting in this invention.

[0024] Figure 2 Electron micrograph of the sodalite product of this invention

[0025] Figure 3 XRD fitting analysis diagram of the sodalite product of this invention

[0026] Figure 4 Physical image of the sodalite product of this invention Detailed Implementation

[0027] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0028] Example 1: Utilization of clayey coal gangue containing rare and dispersed metals gallium, titanium, and yttrium

[0029] The coal gangue in this embodiment is from a coal mine in Inner Mongolia Autonomous Region. The main minerals in this coal gangue are 78.86% kaolinite and 18.69% silicon dioxide, with a fixed carbon content of 13.15%, and it contains titanium, gallium, and yttrium rare metals, namely TiO2 3.21%, Ga 62.45 μg / g, and REY 264.69 μg / g, respectively.

[0030] like Figure 1 As shown, the method for recovering rare and dispersed metals from the above-mentioned coal gangue through gradient chlorination roasting and simultaneously synthesizing sodalite for full utilization specifically includes:

[0031] First, 50g of coal gangue was mixed with 8g of sodium chloride and 10g of sodium hydroxide and placed in a tube furnace. An air flow rate of 1L / min was introduced, and the reaction temperature was set at 700℃. The reaction was carried out for 1.5 hours, and 0.047g of volatile cooling particles 1, containing 15.30% gallium chloride, was collected. After the reaction, the reaction temperature was set at 900℃, and the reaction was carried out for 0.5 hours. 5.06g of volatile cooling particles 2, containing 70.44% titanium chloride, was collected. After the reaction, the reaction temperature was set at 1200℃, and the reaction was carried out for 1 hour. 0.083g of volatile cooling particles 3, containing 34.16% yttrium chloride, was collected. After the reaction was completed, the reaction products from the tube furnace were removed for analysis.

[0032] XRD patterns of the reaction products in the tubular furnace are shown below. Figure 3 As shown in the figure, the weighted graph variance factor R wp The variance factor Rp was 4.21%, with a value of 7.86%, indicating a good fit. The reaction product exhibited characteristic diffraction peaks of sodalite (PDF#37-0476) at 2θ = 14.190, 20.019, 24.640, 31.940, 35.059, 37.950, 43.270, 45.790, 58.839, 62.711, and 64.711°, indicating that the reaction product is sodalite, and that the diffraction peaks are strong, indicating good crystallinity and lattice stability.

[0033] Analysis and calculations show that the volatilization efficiencies of Ti, Ga, and REY are 93.5%, 91.6%, and 96.2%, respectively, and the purity of the solid product, sodalite, is 99.4%.

[0034] Example 2: Utilization of clayey coal gangue containing rare and dispersed metals gallium and titanium

[0035] The coal gangue in this embodiment is from a coal mine in Inner Mongolia Autonomous Region. The main minerals in this coal gangue are 80.25% kaolinite and 17.28% silicon dioxide, with a fixed carbon content of 6.56%, and it contains titanium and gallium rare metals, namely TiO2 2.25% and Ga 72.63 μg / g.

[0036] The specific methods for recovering rare and dispersed metals and simultaneously synthesizing sodalite components from the above-mentioned gradient chlorination roasting of coal gangue include:

[0037] First, 100g of coal gangue, 10g of sodium chloride, and 15g of sodium hydroxide were mixed and placed in a tube furnace. An air flow rate of 1L / min was introduced, the reaction temperature was set to 600℃, and the reaction was carried out for 1 hour. 0.12g of volatile cooling particles 1 were collected, which contained 14.38% gallium chloride. After the reaction was completed, the reaction temperature was set to 800℃, and the reaction was carried out for 1 hour. 6.59g of volatile cooling particles 2 were collected, which contained 76.87% titanium chloride. After the reaction was completed, the reaction products in the tube furnace were taken out for analysis.

[0038] Analysis and calculations show that the volatilization efficiencies of Ti and Ga are 94.8% and 94.5%, respectively, and the purity of the solid product, sodalite, is 98.7%.

[0039] Example 3: Utilization of Yttrium-containing clayey coal gangue

[0040] The coal gangue in this embodiment was obtained from a coal mine in Shanxi Province, China. The Al2O3 content in the coal gangue sample reached 29.23%, and other major impurities were Fe2O3 (2.19%) and K2O (2.16%). The mass ratio of Al2O3 to SiO2 was 0.7388. The REY content in the coal gangue was 300.51 μg / g, reaching the critical utilization grade. Industrial analysis of the coal gangue showed that the volatile matter content reached 15.01%, mainly composed of carbon-containing organic volatiles and water vapor generated from the dehydroxylation of kaolinite. The fixed carbon content was 12.32%, which can provide reducing carbon components for chlorination roasting.

[0041] The specific methods for recovering rare and dispersed metals and simultaneously synthesizing sodalite components from the above-mentioned gradient chlorination roasting of coal gangue include:

[0042] 30g of coal gangue was mixed with 8g of NaCl and 10g of Na2CO3, ground, and sieved. The sieved mixture was then placed in a tube furnace and calcined for 3 hours at an air flow rate of 1L / min and a calcination temperature of 1000℃. 0.067g of volatile cooled particles were collected, containing 27.99% yttrium chloride. After the reaction was completed, the reaction products from the tube furnace were removed for analysis.

[0043] Analysis and calculation show that the volatility of REY is 93.4%, and the purity of the solid product, sodalite, is 99.2%.

[0044] The above description is only for better explaining the embodiments of the present invention and is not intended to limit them. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims

1. A method for recovering rare and dispersed metals from coal gangue via gradient chlorination and simultaneously synthesizing sodalite, characterized in that: Includes the following steps: (1) After mixing coal gangue with chlorinating agent and activator in proportion, the temperature is controlled at 500-800℃ for chlorination roasting, and gallium chloride volatile phase cooling particles are collected; (2) After the chlorination roasting in step (1) is completed, control the temperature to 600-1000℃ and continue the chlorination roasting, and collect the volatile phase cooling particles of titanium chloride; (3) After the chlorination roasting in step (2) is completed, control the temperature to 800-1200℃ and continue the chlorination roasting, and collect the volatile phase cooling particulate matter yttrium chloride; (4) After the chlorination roasting in step (3) is completed, collect the solid reaction product, sodalite; In step (1), the chlorinating agent is selected from at least one of ferric chloride, calcium chloride, ammonium chloride, sodium chloride, carbon tetrachloride, and magnesium chloride; the activating agent is selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, and potassium bicarbonate.

2. The method for recovering rare and dispersed metals from coal gangue by gradient chlorination and simultaneously synthesizing sodalite according to claim 1, characterized in that: In steps (2), (3), and (4), the chlorination roasting time is 0.5 to 3 hours.

3. The method for recovering rare and dispersed metals from coal gangue by gradient chlorination and simultaneously synthesizing sodalite according to claim 1, characterized in that: In step (1), the amount of chlorinating agent used is 5% to 30% of the mass of coal gangue.

4. The method for graded chlorination recovery of rare and dispersed metals from coal gangue and simultaneous synthesis of sodalite according to claim 1, characterized in that: In step (1), the amount of activator used is 15% to 45% of the mass of coal gangue.

5. The method for graded chlorination recovery of rare and dispersed metals from coal gangue and simultaneous synthesis of sodalite according to claim 1, characterized in that: In step (1), the coal gangue is clayey coal gangue containing rare and dispersed metals; the carbon content in the coal gangue is 2% to 15%.

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