Modification process and resource utilization method of crystallized carnallite in coal chemical industry

Abstract

The invention provides a modification process and resource utilization method of coal chemical industry crystal carnallite, the coal chemical industry crystal carnallite and alkaline solid waste are mixed to a wet material state, granulation is carried out through a ball press machine, complete mineralization is carried out in a carbon dioxide mineralization tank, modified crystal carnallite is obtained, and physical sealing of the crystal carnallite is preliminarily realized. And secondly, the modified crystal carnallite and the coal-based solid waste rich in the silicon-aluminum phase are co-treated, substances with gelling performance, such as ettringite, calcium silicate gel, calcium aluminate gel and fluorochlorodel salt, are generated through a hydration reaction, and finally permanent sealing of harmful substances in the crystal carnallite is achieved. The modified crystal carnallite is used as a filling aggregate to co-process coal-based solid waste to prepare the filling slurry which can be used for filling a coal mine goaf, so that low-cost filling of the goaf is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of hazardous industrial solid waste disposal, and specifically relates to a modification process of coal chemical crystalline miscellaneous salts and a resource utilization method thereof. Background Art

[0002] Coal chemical crystalline salts are obtained by evaporating and crystallizing high-salt wastewater from coal chemical industry. They have high-risk characteristics such as high inorganic salt ion concentration, complex organic pollutants and high content of heavy metal elements. Since the crystalline salts of high-salt wastewater after evaporation and crystallization are mainly in the form of sodium salt, potassium salt, magnesium salt and calcium salt, the current treatment method of coal chemical enterprises is usually in accordance with the treatment requirements of hazardous wastes, using physical, chemical, biological and other methods for pre-treatment, and changing its physical or chemical properties to achieve the purpose of reducing pollution hazards.

[0003] For example, a coal chemical company carried out rigid landfill disposal of crystallized salt. It first used high-strength low-permeability concrete to construct the landfill space, and then used high-density polyethylene (HPDE) materials for anti-seepage treatment, and finally achieved rigid landfill of crystallized salt. The use of rigid landfill to dispose of crystallized salt, the harmful substances in the crystallized salt cannot be sealed and fixed during the treatment process, which is poor in environmental protection and difficult to meet the requirements of industrial application. It does not conform to the concept of environmental protection development, and seriously restricts the high-quality development of enterprise technology. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a modification process of coal chemical crystalline miscellaneous salts and a method for resource utilization thereof. The modification of the crystalline miscellaneous salts realizes the permanent storage of harmful substances in the crystalline miscellaneous salts. At the same time, the modification of the crystalline miscellaneous salts can mineralize and seal CO2, realizing the long-term storage of CO2, helping to achieve the "dual carbon" goal, solving the hazardous solid waste characteristics of the crystalline miscellaneous salts, and synergistically disposing of coal-based solid waste to prepare all-solid waste filling materials (slurry cementitious materials), thereby realizing low-cost filling of coal mine goafs.

[0005] The present invention is implemented by adopting the following technical scheme: a modification process of coal chemical crystalline salt and a resource utilization method thereof, comprising the following steps:

[0006] Step 1: 10 to 30 parts by weight of coal chemical crystalline salt, 70 to 90 parts by weight of alkaline solid waste, and the rest of liquid water are mixed and stirred evenly at a liquid-to-solid ratio of 0.06 to 0.18 to form an alkaline solid waste-crystalline salt material in a wet state;

[0007] Step 2: feeding the alkaline solid waste-crystalline miscellaneous salt material prepared in step 1 into a briquetting machine to "granulate" the alkaline solid waste-crystalline miscellaneous salt to form an ellipsoidal material;

[0008] Step 3: Transport the ellipsoidal materials prepared in Step 2 to a carbon dioxide mineralization reaction tank for mineralization curing until the ellipsoidal materials are completely mineralized, obtaining modified crystalline mixed salts.

[0009] Step 4: Crush the modified crystalline mixed salts prepared in Step 3 to make their particle size ≤ 10 mm, and feed them into a mixer according to the mass ratio of modified crystalline mixed salts, gelling material, and coal-based solid waste of 1:(0.20 - 0.80):(0.30 - 0.80) and stir evenly to make a slurry with a mass concentration of 70% - 83% for filling in coal mine gob areas.

[0010] Preferably, in Step 1, the alkaline solid waste is composed of 10 - 30 parts by weight of modified magnesium slag, 10 - 30 parts by weight of carbide slag, 10 - 30 parts by weight of steel slag, 10 - 30 parts by weight of coal gasification slag, and 10 - 30 parts by weight of fly ash.

[0011] Preferably, in Step 1, the main components of the coal chemical industry crystalline mixed salts include sodium chloride and sodium sulfate.

[0012] Preferably, in Step 2, the size of the forming die of the briquetting machine is an ellipsoid of 30 mm × 40 mm, and the forming pressure of the briquetting machine is 10 - 30 MPa.

[0013] Preferably, in Step 3, the CO2 concentration in the carbon dioxide mineralization reaction tank is 99%, the temperature of the mineralization reaction tank is 20 - 50 °C, and the pressure of the mineralization reaction tank is 0 - 1 MPa.

[0014] Preferably, in Step 3, the coal-based solid waste is fly ash, coal combustion slag, and coal gasification slag.

[0015] Preferably, in Step 4, the gelling material is ordinary Portland cement.

[0016] Preferably, in Step 4, the main components of the hydration products generated during the solidification of the slurry include ettringite, calcium silicate gel, calcium aluminate gel, and Friedel's salt.

[0017] Preferably, the main component of the modified magnesium slag includes β-Ca2SiO4.

[0018] Preferably, in Step 2, the ellipsoidal materials formed by "granulation" are transported to a buffer bin through a belt, and the debris of the ellipsoidal materials is transported to a mixing bin through a return belt for stirring and recycling to complete the preparation of the alkaline solid waste - crystalline mixed salt materials in Step 1.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The key technology of "granulation - mineralization" modification for coal chemical crystallization miscellaneous salts is to mix alkaline solid waste and crystallization miscellaneous salts to a moist material state, perform "granulation" through a briquetting machine, and completely mineralize the ellipsoidal material obtained by "granulation" in a carbon dioxide mineralization reaction tank to achieve short - term physical sequestration of harmful substances in the crystallization miscellaneous salts.

[0021] 2. The modified crystallization miscellaneous salts are co - disposed with coal - based solid waste. The silicon - aluminum phase monomers dissolved from the coal - based solid waste under alkaline conditions chemically react with the inorganic salts in the modified crystallization miscellaneous salts to form substances with gelling properties, such as ettringite, calcium silicate gel, calcium aluminate gel, and Friedel's salt, etc., ultimately achieving the permanent sequestration of crystallization miscellaneous salts and harmful substances. The slurry prepared by mixing the modified crystallization miscellaneous salts and coal - based solid waste can be used for filling mined - out areas in coal mines, realizing low - cost filling of mined - out areas.

[0022] 3. During the modification process of crystallization miscellaneous salts, the mineralization and sequestration of CO2 by the alkaline solid waste - crystallization miscellaneous salts ellipsoidal material achieves long - term sequestration of CO2, contributing to the realization of the "dual - carbon" goal. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the process flow diagram of the modification process and its resource utilization method of the coal chemical crystallization miscellaneous salts of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following describes the embodiments of the present application in detail with reference to the drawings.

[0025] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0026] As Figure 1 shown, the embodiments of the present application provide a modification process and its resource utilization method for coal chemical crystallization miscellaneous salts, including the following steps:

[0027] Step 1: In the crystallization miscellaneous salt storage tank, mix and stir evenly according to the ratio of 10 - 30 parts by weight of coal chemical crystallization miscellaneous salts, 70 - 90 parts by weight of alkaline solid waste, and the rest is liquid water, with a liquid - solid ratio of 0.06 - 0.18 to form an alkaline solid waste - crystallization miscellaneous salt material in a moist material state; among them, there are two alkaline solid waste storage tanks, and the alkaline solid waste is composed of 10 - 30 parts by weight of modified magnesium slag, 10 - 30 parts by weight of carbide slag, 10 - 30 parts by weight of steel slag, 10 - 30 parts by weight of coal gasification slag, and 10 - 30 parts by weight of fly ash.

[0028] Optionally, in this embodiment, the main components of the coal chemical crystallization miscellaneous salts include sodium chloride and sodium sulfate. Optionally, in this embodiment, the alkaline solid waste can also be freely formulated according to the enrichment degree of local solid waste. Generally, the alkaline solid waste contains a large amount of alkaline oxides such as Na2O, CaO, and MgO.

[0029] Optionally, in this embodiment, the main component of the modified magnesium slag includes β-Ca2SiO4.

[0030] Step 2: Feed the alkaline solid waste-crystallization miscellaneous salt material in the wet material state prepared in Step 1 into a briquetting machine for "granulation" of the alkaline solid waste-crystallization miscellaneous salt material to form an ellipsoidal material.

[0031] Optionally, in this embodiment, the size of the briquetting machine forming die is an ellipsoid of 30mm×40mm, and the forming pressure of the briquetting machine is 10-30 MPa. The briquetting machine adopts the 850-type strong dry powder briquetting machine of Henan Guoxin Group Co., Ltd.

[0032] Optionally, in this embodiment, the ellipsoidal material formed by "granulation" is conveyed to a buffer bin through a belt, and the debris of the ellipsoidal material is conveyed to a mixing bin through a return belt for mixing, and the preparation of the alkaline solid waste-crystallization miscellaneous salt material in Step 1 is completed by circulation.

[0033] Step 3: Convey the ellipsoidal material prepared in Step 2 to a carbon dioxide mineralization reaction tank through a belt for mineralization curing until the ellipsoidal material is completely mineralized to obtain modified crystallization miscellaneous salts. At this point, the "granulation-mineralization" modification of the crystallization miscellaneous salts has been completed.

[0034] Optionally, in this embodiment, the manufacturer of the mineralization reaction tank is Jiangsu Haoyu Special Equipment Manufacturing Co., Ltd. Among them, the CO2 concentration in the carbon dioxide mineralization reaction tank is 99%, the temperature that can be adjusted in the mineralization reaction tank is 20-50°C, and the pressure that can be adjusted in the mineralization reaction tank is 0-1 MPa. The completely mineralized ellipsoidal material has high mechanical properties, extremely low porosity and a dense microstructure, realizing the physical sequestration of inorganic salt ions, organic pollutants and heavy metal elements in the crystallization miscellaneous salts. At the same time, the mineralization sequestration of CO2 by the alkaline solid waste realizes the long-term sequestration of CO2, contributing to the realization of the "dual carbon" goal.

[0035] According to Steps 2 and 3, the specific experimental data for the modification of crystallization miscellaneous salts are as follows:

[0036] Table 1 Experimental schemes of different embodiments

[0037] Experiment number Crystalline miscellaneous salts Alkaline solid waste Liquid-solid ratio Mineralization time C0 100％ / 0.18 24h C1 30％ 70％ 0.18 24h C2 30％ 70％ 0.18 6h C3 30％ 70％ 0.06 24h

[0038] Carry out the "granulation - mineralization" modification experiment on the crystalline miscellaneous salts in coal chemical industry according to the experimental scheme in Table 1. Extract the leachate of the modified crystalline miscellaneous salts with different experimental numbers respectively, and test the total dissolved solids (TDS) and dichromate oxygen demand (CODCr) of the leachate of the modified crystalline miscellaneous salts to evaluate the modification effect of the crystalline miscellaneous salts.

[0039] Table 2 Experimental results of different embodiments

[0040] Experiment number TDS (mg / L) CODCr (mg / L) C0 53630.00 114.319 C1 2274.00 31.134 C2 12492.00 83.036 C3 2908.00 32.330

[0041] It can be seen from the experimental results that the "granulation - mineralization" of the crystalline miscellaneous salts mixed with alkaline solid waste can realize the solidification and sequestration of harmful substances in the crystalline miscellaneous salts.

[0042] Step 4: Crush the modified crystalline miscellaneous salts prepared in Step 3 to make their particle size ≤ 10 mm, and send them into a mixer through each storage bin and weighing hopper according to the mass ratio of modified crystalline miscellaneous salts, gelling material and coal - based solid waste of 1:(0.20 - 0.80):(0.30 - 0.80) and stir evenly to make a slurry with a mass concentration of 70% - 83%. After the reaction, a slurry gelling material for filling the underground working face is obtained.

[0043] Optionally, in this embodiment, the coal - based solid waste is fly ash, and the mass percentages of each component in the fly ash are as follows:

[0044] SiO2: 40.36, Al2O3: 16.22, Fe2O3: 12.54, Na2O: 8.92, Ca0: 7.81, Cl: 5.12, SO3: 2.68, K2O: 1.78, MgO: 0.98, TiO2: 20.97, others: 0.98, and the gelling material is ordinary Portland cement.

[0045] Optionally, in this embodiment, the slurry gelling material is transported to the filling working face (underground) through a filling pump and a conveying pipeline. To prevent the harmful substances in the modified crystalline miscellaneous salt inclusions in the slurry gelling filling material from migrating outward and causing leakage, utilize the characteristic that the silicon - aluminum phase monomers dissolve in the alkaline condition in the coal - based solid waste (such as fly ash). The silicon - aluminum phase monomers react chemically with the inorganic salts in the modified crystalline miscellaneous salts to generate substances with gelling properties, such as ettringite, calcium silicate gel, calcium aluminate gel, and fluorchloride salt, etc., finally realizing the permanent sequestration of the crystalline miscellaneous salts and their harmful substances, and at the same time realizing the low - cost filling of the goaf in the coal mine.

[0046] It should be noted that the above - listed are only several specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and can have other deformations. All deformations directly derived or indirectly extended by those skilled in the art from the disclosed content of the present invention should be considered within the protection scope of the present invention.

Claims

1. A modification process for crystalline miscellaneous salts in coal chemical industry and its resource utilization method, characterized in that, It includes the following steps: Step 1: Mix and stir evenly according to the ratio of 10 - 30 parts by weight of coal chemical crystallization miscellaneous salt, 70 - 90 parts by weight of alkaline solid waste, and the rest being liquid water, with a liquid-solid ratio of 0.06 - 0.18 to form an alkaline solid waste-crystallization miscellaneous salt material in a moist material state; Step 2: Feed the alkaline solid waste-crystallization miscellaneous salt material prepared in Step 1 into a briquetting machine for "granulation" of the alkaline solid waste-crystallization miscellaneous salt to form an ellipsoidal material; Step 3: Transport the ellipsoidal material prepared in Step 2 to a carbon dioxide mineralization reaction tank for mineralization curing until the ellipsoidal material is completely mineralized to obtain modified crystallization miscellaneous salt; Step 4: Crush the modified crystallization miscellaneous salt prepared in Step 3 so that its particle size ≤ 10 mm, and feed it into a mixer according to the mass ratio of modified crystallization miscellaneous salt, cementitious material, and coal-based solid waste of 1:(0.20 - 0.80):(0.30 - 0.80) and stir evenly to make a slurry with a mass concentration of 70% - 83% for filling in the mined-out area of coal mines.

2. The modified process and resource utilization method of the coal chemical crystallization miscellaneous salt according to claim 1, characterized in that, In Step 1, the alkaline solid waste is composed of 10 - 30 parts by weight of modified magnesium slag, 10 - 30 parts by weight of carbide slag, 10 - 30 parts by weight of steel slag, 10 - 30 parts by weight of coal gasification slag, and 10 - 30 parts by weight of fly ash.

3. The modified process and resource utilization method of the coal chemical crystallization miscellaneous salt according to claim 1, characterized in that, In Step 1, the main components of the coal chemical crystallization miscellaneous salt include sodium chloride and sodium sulfate.

4. The modified process and resource utilization method of coal chemical crystallization miscellaneous salts according to claim 1, characterized in that, In Step 2, the size of the briquetting machine forming die is an ellipsoid of 30 mm × 40 mm, and the forming pressure of the briquetting machine is 10 - 30 MPa.

5. The modified process and resource utilization method of coal chemical crystallization miscellaneous salts according to claim 1, characterized in that, In Step 3, the CO2 concentration in the carbon dioxide mineralization reaction tank is 99%, the temperature of the mineralization reaction tank is 20 - 50 °C, and the pressure of the mineralization reaction tank is 0 - 1 MPa.

6. The modified process and resource utilization method of coal chemical crystallization miscellaneous salts according to claim 1, characterized in that, In Step 3, the coal-based solid waste is fly ash, coal combustion slag, and coal gasification slag.

7. A modification process and resource utilization method for coal chemical crystallization miscellaneous salts according to claim 1, characterized in that, In Step 4, the cementitious material is ordinary Portland cement.

8. A modification process and resource utilization method for crystallized miscellaneous salts in coal chemical industry according to claim 1, characterized in that, In Step 4, the main components of the hydration products generated during the solidification of the slurry include ettringite, calcium silicate gel, calcium aluminate gel, and Friedel's salt.

9. The modified process and resource utilization method of the coal chemical crystallization miscellaneous salt according to claim 2, characterized in that, The main component of the modified magnesium slag includes β-Ca2SiO4.

10. The modified process and resource utilization method of coal chemical crystallization mixed salts according to claim 1, characterized in that, In Step 2, the ellipsoidal material formed by "granulation" is transported to a buffer bin through a belt, and the debris of the ellipsoidal material is transported to a mixing bin through a return belt for stirring and recycling to complete the preparation of the alkaline solid waste-crystallization miscellaneous salt ellipsoidal material in Step 1.

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