Method for comprehensively utilizing material containing calcium silicate or calcium silicate phase with high added value

Abstract

The invention discloses a method for comprehensively utilizing a material containing calcium silicate or calcium silicate phase with high added value, and belongs to the fields of comprehensive utilization of resources, solid waste recycling and mineral material processing. Various solid materials, by-products and waste materials containing calcium silicate or calcium silicate phases generated in the fields of ore extraction and processing, metallurgy, materials, chemical engineering, environment and the like are selected; comprising but not limited to one or more of common high-calcium fly ash, yellow phosphorus slag, red mud, blast furnace slag and artificially modified calcium silicate-containing or calcium silicate-containing materials as raw materials, nitric acid selective leaching is carried out, the leachate is heated and hydrolyzed, the hydrolysate is used for producing high-purity gypsum and regenerated nitric acid, and the high-purity gypsum and regenerated nitric acid are recycled. The regenerated nitric acid returns to the leaching process, and a solid phase obtained through hydrolysis is sequentially subjected to washing, drying, acid leaching and calcination to prepare white carbon black, porous silicon dioxide or high-purity silicon dioxide. The method has the advantages of mild process conditions and high added value of products, and can thoroughly solve the bottleneck problem in sustainable development in multiple fields.

Description

Technical Field

[0001] The invention belongs to the field of comprehensive resource utilization, solid waste resource recovery and mineral material processing, and specifically relates to a method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value. Background Art

[0002] The top five elements in the earth's crust are oxygen, silicon, aluminum, iron, and calcium, with contents of O (45.2%), Si (27.2%), Al (8%), Fe (5.8%), and Ca (5.06%), respectively. Although the content of calcium silicate ore in the earth's crust is not rich, it is very easy to produce calcium silicate or calcium silicate in human production activities. For example, calcium silicate in cement is the main component of cement, accounting for about 70% of the volume of cement. There are three common ways for calcium silicate or calcium silicate to be generated in human activities: First, hydrothermal reaction, which is to generate calcium silicate by mixing silicate, quicklime and water in a certain proportion and then hydrothermally reacting. Second, high-temperature calcination, calcium oxide and silicon dioxide are easily melted at high temperatures to generate calcium silicate or various calcium silicates. Third, limestone and silicon dioxide react to generate calcium silicate. First, limestone is calcined to obtain quicklime, and then quicklime and silicon dioxide react to generate calcium silicate. Therefore, a large amount of materials or solid wastes containing calcium silicate and / or calcium silicate are generated in the fields of ore mining, mineral processing, metallurgy, materials, chemical industry, etc., including but not limited to common high-calcium fly ash, yellow phosphorus slag, red mud, smelting slag, etc., and various materials containing calcium silicate and / or calcium silicate after artificial modification. In addition to containing a large amount of calcium and silicon resources, the above materials also contain a considerable amount of non-ferrous metals, rare earths, rare metals, etc., but most of them can only be stored as industrial solid waste or hazardous waste. This not only causes serious environmental pressure, but also leads to a large amount of resource waste.

[0003] In addition, my country's bulk solid wastes, such as coal gangue, gasification slag, fly ash, ore dressing tailings, smelting slag and other solid wastes, contain a large amount of aluminum, silicon and precious lithium, gallium, rare earth and other resources. The resource utilization of these solid wastes can reduce the exploitation of mineral resources. A large number of studies have been conducted on the recovery and utilization of valuable metal components from the above-mentioned bulk solid wastes, but it is difficult to effectively utilize the large amount of associated silicon elements, which will inevitably bring about certain secondary pollution. Therefore, the resource utilization of a large amount of silicon in the above-mentioned solid wastes is the main factor restricting the complete harmlessness and reduction of bulk industrial solid wastes. Under the current technical conditions, the utilization of silicon resources in the above-mentioned solid wastes mainly includes the preparation of silicon-based materials such as aerogel, hydrated calcium silicate, and white carbon black. Among them, the preparation processes of products such as aerogel and white carbon black have problems such as large differences in product performance, complex process flow, and difficulty in recycling alkaline media, making it difficult to achieve large-scale utilization. However, it is very easy and low-cost to prepare calcium silicate using the associated silicon element in the above materials. A large number of studies have confirmed that it is easy and low-cost to synthesize calcium silicate using the associated silicon resources that exist in large quantities in various bulk industrial solid wastes.

[0004] Therefore, research and development of efficient resource utilization, harmless treatment, high value-added and green production process methods for various materials or solid wastes containing calcium silicate or calcium silicate can generate important economic value, environmental value and important practical significance. Summary of the invention

[0005] In view of the deficiencies of the above technical problems, the present invention proposes a method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value, comprising the following steps:

[0007] (1) Using materials containing calcium silicate and / or calcium silicate phase produced in various industrial fields as raw materials;

[0008] (2) grinding the raw materials selected in step (1) with larger lumps, and then leaching them with nitric acid at room temperature, and separating the solid and liquid after the leaching to obtain a leachate and a leaching residue;

[0009] (3) heating the leaching solution obtained in step (2) to carry out a chemical reaction, and after the reaction is completed, separating the solid and the liquid to obtain a solid phase and a liquid phase;

[0010] (4) adding sulfuric acid to the liquid phase obtained in step (3) for precipitation reaction, and after the precipitation is completed, the solid-liquid separation is performed to obtain the liquid phase and a high-purity gypsum product;

[0011] (5) adding sulfuric acid solution to the liquid phase obtained in step (4) for distillation, distilling to obtain steam and solid phase crystals, condensing the steam to obtain regenerated nitric acid, and returning the regenerated nitric acid to step (2) for leaching reaction;

[0012] (6) washing and drying the solid phase obtained in step (3) to obtain a dried solid phase, and returning the washing liquid obtained by solid-liquid separation in the washing process to the nitric acid leaching process in step (2);

[0013] (7) subjecting the solid phase obtained after drying in step (6) to acid leaching, and after the acid leaching is completed, solid-liquid separation is performed to obtain a leachate and a solid phase;

[0014] (8) The solid phase obtained in step (7) is calcined to obtain a silicon-based material. The silicon-based material is white carbon black, porous silicon dioxide or high-purity silicon dioxide.

[0015] As a preferred embodiment of the present invention, the material containing calcium silicate and / or calcium silicate is various solid materials, intermediate products, by-products and waste materials containing calcium silicate or calcium silicate phases produced in the fields of ore mining and processing, metallurgy, materials, chemical industry, energy, environment, etc. The chemical composition of the material containing calcium silicate and / or calcium silicate contains CaO and SiO2, including but not limited to common high-calcium fly ash, yellow phosphorus slag, red mud, blast furnace slag, various materials containing calcium silicate or calcium silicate artificially modified and synthesized, etc. More preferably, the material containing calcium silicate and / or calcium silicate is at least one of high-calcium fly ash, yellow phosphorus slag, red mud, blast furnace slag, materials containing calcium silicate or calcium silicate artificially modified and synthesized, and by-products.

[0016] As a preferred embodiment of the present invention, in step (2), the conditions for nitric acid leaching are: leaching temperature is 10-40°C, nitric acid volume concentration is 10%-50%, liquid-solid mass ratio is 10:1-3:1, and leaching time is 0.5-3h.

[0017] As a preferred embodiment of the present invention, in the step (3), the heating temperature is 60 to 100° C. and the heating time is 0.5 to 3 hours.

[0018] As a preferred embodiment of the present invention, in step (4), the mass concentration of the sulfuric acid solution is 50% to 98%, the volume ratio of the liquid to the sulfuric acid solution is 1:5 to 1:50, the precipitation reaction temperature is 10-100°C, and the time is 0.5-3h.

[0019] As a preferred embodiment of the present invention, in the step (5), the mass concentration of the sulfuric acid solution is 50% to 98%, the volume ratio of the sulfuric acid solution to the liquid phase is 1:2 to 1:10; and the distillation temperature is 80 to 100°C.

[0020] As a preferred embodiment of the present invention, the solvent used for washing is water or nitric acid solution. When water washing is used, the washing temperature is 10-100°C, the washing liquid-solid mass ratio is 8:1-3:1, the washing time is 0.5-3h, and the number of washing times is 1-3 countercurrent washing; when water washing is used, the volume concentration of the nitric acid solution is 3%-10%, and the other conditions are the same as water washing; the drying temperature is 100-300°C, and the drying time is 0.5-10h.

[0021] As a preferred embodiment of the present invention, the acid leaching conditions in step (7) are: the leaching agent is at least one of sulfuric acid, nitric acid and hydrochloric acid, the acid volume concentration is 5% to 80%, the leaching reaction temperature is 50 to 200° C., the leaching liquid-solid mass ratio is 8:1 to 2:1, the leaching time is 0.5 to 3 hours, and the number of leaching reaction stages is 1 to 5 countercurrent leaching.

[0022] As a preferred embodiment of the present invention, in the step (8), the calcination conditions of the solid phase are: the calcination temperature is 700 to 2500° C., and the calcination time is 0.5 to 3 hours.

[0023] As a preferred embodiment of the present invention, the purity of the high-purity gypsum is above 80%, and can be as high as over 95%; the purity of the high-purity silicon dioxide is higher than 99%, and can be as high as over 99.99% to 99.9999%.

[0024] Principle of the present invention:

[0025] First, the raw material is selectively leached with nitric acid under mild conditions to extract silicon from calcium silicate or calcium silicate, and the valuable elements in the leached residue can be further separated and recovered. Secondly, the leachate is heated and hydrolyzed to crystallize and precipitate the silicon in the solid phase, and the separation, purification and recovery of silicon are achieved through further solid-liquid separation. The heating and hydrolysis of silicon in the solution does not require additional reagents and only requires heating. Thirdly, impurities in silica are removed by combining further acid leaching and impurity removal. Finally, the silicon oxide in the material is separated from other components and polymerized into silica again during the process of leaching, precipitation, and leaching and impurity removal. The crystal structure and microstructure will change during the process. Depending on the raw materials and the process conditions and parameters, the purity and pore structure of the final silica are different. Therefore, depending on the raw materials and the processing conditions and parameters, the final silica can be white carbon black, porous silica or high-purity silica. The hydrolyzate regenerates the nitric acid in the process to achieve the recycling of nitric acid, which is conducive to further reducing the cost of reagents.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention converts a large amount of silicon, calcium, etc. in materials containing calcium silicate or calcium silicate phases, including: a large amount of materials or solid wastes containing calcium silicate and / or calcium silicate phases generated in the fields of ore mining, mineral processing, metallurgy, materials, chemical industry, etc., including but not limited to common high-calcium fly ash, yellow phosphorus slag, red mud, smelting slag, etc., and various materials containing calcium silicate and / or calcium silicate after artificial modification, into high-value products or intermediate products through a mild reaction condition system. Compared with the traditional field, the present invention realizes the refined resource utilization of multiple components, can generate higher added value, and completely solves the sustainable development and environmental protection problems faced in multiple fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flow chart of a method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value.

[0028] Figure 2 This is the BET diagram of the mesoporous silica prepared in Example 3. DETAILED DESCRIPTION

[0029] The present invention is not limited to the following embodiments, and various modifications and improvements can be made without departing from the spirit and scope of the present invention. In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0030] A method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value, comprising the following steps:

[0031] (1) Using materials containing calcium silicate and / or calcium silicate produced in various industrial fields as raw materials, common ones include high-calcium fly ash, yellow phosphorus slag, red mud, blast furnace slag and various materials and by-products containing calcium silicate or calcium silicate after artificial modification, and selecting a mixture of one or more of them.

[0032] (2) The raw materials selected in step (1) are crushed and ground for larger pieces, and then leached with nitric acid at room temperature. After the leaching is completed, the solid and liquid are separated to obtain a leachate and a leaching residue.

[0033] (3) heating the leaching solution obtained in step (2) to carry out a chemical reaction, and after the reaction is completed, separating the solid and the liquid to obtain a solid phase and a liquid phase.

[0034] (4) The liquid phase obtained in step (3) is subjected to a precipitation reaction by adding a sulfuric acid solution, and after the precipitation is completed, the solid-liquid separation is performed to obtain a liquid phase and a high-purity gypsum product.

[0035] (5) adding sulfuric acid solution to the liquid phase obtained in step (4) for distillation, distilling to obtain steam and solid phase crystals, condensing the steam to obtain regenerated nitric acid, and returning the regenerated nitric acid to step (2) for leaching reaction.

[0036] (6) The solid phase obtained in step (3) is washed and dried in sequence to obtain a dried solid phase, and the washing liquid obtained by solid-liquid separation during the washing process is returned to the nitric acid leaching process of step (2).

[0037] (7) The solid phase obtained after drying in step (6) is subjected to acid leaching, and after the acid leaching is completed, the solid-liquid separation is performed to obtain a leachate and a solid phase.

[0038] (8) The solid phase obtained in step (7) is calcined to obtain a silicon-based material: white carbon black, porous silica or high-purity silica. The silicon oxide in the material is separated from other components and repolymerized into silicon dioxide during the leaching, precipitation and leaching removal process. The crystal structure and microstructure will change during the process. Depending on the raw materials and the process parameters, the purity and pore structure of the final silicon dioxide will vary. Therefore, depending on the raw materials and the processing parameters, the final silicon dioxide can be white carbon black, porous silica or high-purity silica.

[0039] (9) The leached residue obtained in step (2) can be further separated and the valuable components therein can be recovered.

[0040] (10) The solid phase crystals obtained in step (5) can be further separated and the valuable metals therein can be recovered.

[0041] (11) The leaching solution obtained in step (7) can be further separated and recovered to obtain valuable metals and regenerate the leaching agent.

[0042] In step (2) of the present invention, the reaction conditions of nitric acid leaching at room temperature are: the leaching reaction temperature is preferably 10-40°C, more preferably 20-40°C, and more preferably 25-35°C. The volume concentration of nitric acid is preferably 10%-50%, more preferably 20%-40%, and more preferably 20%-30%. The solid volume ratio of the leachate is preferably 10:1-3:1, more preferably 8:1-4:1, and more preferably 8:1-5:1. The leaching time is preferably 0.5-3h, more preferably 1-3h, and more preferably 1.5-2.5h.

[0043] In step (3) of the present invention, the heating conditions are as follows: the reaction temperature is preferably 60 to 100°C, more preferably 80 to 100°C, and more preferably 90 to 100°C; the reaction time is preferably 0.5 to 3h, more preferably 1 to 3h, and more preferably 1.5 to 3h.

[0044] In step (4) of the present invention, the conditions for adding sulfuric acid for precipitation reaction are: the mass concentration of the added sulfuric acid solution is preferably 50% to 98%, more preferably 70% to 98%, and more preferably 98%; the volume ratio of the sulfuric acid solution to the liquid phase to be precipitated is preferably 1:5 to 1:50, more preferably 1:8 to 1:40, and more preferably 1:8 to 1:20; the reaction temperature is preferably 10 to 100° C., more preferably 10 to 70° C., and more preferably 15 to 40° C.; the reaction time is preferably 0.5 to 3 h, more preferably 0.5 to 2 h, and more preferably 0.5 to 1.5 h.

[0045] In step (5) of the present invention, the conditions for adding sulfuric acid solution for reaction and performing nitric acid distillation regeneration are: the mass concentration of the added sulfuric acid solution is preferably 50% to 98%, more preferably 70% to 98%, and more preferably 98%; the volume ratio of sulfuric acid solution to liquid phase is preferably 1:2 to 1:10, more preferably 1:2 to 1:8, and more preferably 1:3 to 1:6; the reaction temperature is preferably 80 to 100° C., more preferably 85 to 100° C., and more preferably 85 to 95° C.

[0046] In step (6) of the present invention, the washing conditions are as follows: the solvent used for washing is preferably water or nitric acid solution, and water washing is more preferably used; the solvent is water as the solvent washing reaction temperature is preferably room temperature 10-100°C, more preferably 20-40°C, and more preferably 25-40°C. The washing liquid-to-solid mass ratio is preferably 8:1-3:1, more preferably 6:1-3:1, and more preferably 5:1-3:1. The washing time is preferably 0.5-3h, more preferably 1-3h, and more preferably 1-2h; the number of washings is preferably 1-3 countercurrent washings, more preferably 2-3 countercurrent washings, and more preferably 2 countercurrent washings; when nitric acid solution is used as the solvent for washing, the volume concentration of nitric acid is preferably 3%-10%, more preferably 3%-8%, and more preferably 3%-6%; the remaining conditions are the same as those for water washing.

[0047] In step (6) of the present invention, the drying conditions are as follows: the drying temperature is preferably 100-300°C, more preferably 120-200°C, and more preferably 130-180°C; the drying time is preferably 0.5-10h, more preferably 1-10h, and more preferably 2-10h.

[0048] In step (7) of the present invention, the acid leaching reaction conditions are as follows: the leaching agent is preferably at least one of sulfuric acid, nitric acid and hydrochloric acid, more preferably sulfuric acid; the acid volume concentration is preferably 5% to 80%, more preferably 10% to 80%, more preferably 30% to 80%; the leaching reaction temperature is preferably 50 to 200° C., more preferably 80 to 200° C., more preferably 90 to 200° C.; the leaching liquid-solid ratio is preferably 8:1 to 2:1, more preferably 6:1 to 3:1, more preferably 5:1 to 3:1; the leaching time is preferably 0.5 to 3 h, more preferably 1 to 3 h, more preferably 1.5 to 3 h; the number of leaching reaction stages is preferably 1 to 5 countercurrent leaching, more preferably 2 to 3 countercurrent leaching.

[0049] In step (8) of the present invention, the calcination conditions of the solid phase obtained by acid leaching are: the calcination temperature is preferably 700-2500°C, more preferably 700-2300°C, and more preferably 700-2000°C; the calcination time is preferably 0.5-3h, and more preferably 1-3h.

[0050] The purity of the high-purity gypsum prepared by the present invention is above 80%, and can be as high as over 95%; the purity of the high-purity silicon dioxide prepared by the present invention is higher than 99%, and can be as high as over 99.99% to 99.9999%.

[0051] Example 1

[0052] A method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value, the specific steps of which are as follows:

[0053] (1) The raw material selected is a high-calcium fly ash, whose chemical composition is: CaO content 46.3%, Al2O3 content 12.9%, SiO2 content 28.7%, and other components content 12.1%. The high-calcium fly ash is ground to a particle size of less than -0.074 mm, and the ground high-calcium fly ash is leached with nitric acid at room temperature. The leaching reaction conditions are: leaching reaction temperature is 30°C, nitric acid volume concentration is 30%, leaching liquid solid volume ratio is 6:1, leaching time is 2h, and after the leaching reaction is completed, the leaching liquid and leaching residue are obtained by filtering for solid-liquid separation. The leaching residue can be used as an intermediate product to further recover the metal and non-metal valuable components therein.

[0054] (2) The leachate is heated to 90° C. for hydrolysis reaction. The hydrolysis reaction time is 2 h. After the reaction is completed, the hydrolysis solid phase and the hydrolysis liquid phase are obtained by filtration.

[0055] (3) The hydrolyzed solid phase is washed with water at a washing temperature of 25°C, a washing liquid-solid mass ratio of 4:1, and a washing time of 2 hours. After washing, solid-liquid separation is performed to obtain a washing liquid and a washed solid phase, and the washing liquid is returned to the nitric acid room temperature leaching step. The washed solid phase is heated and dried at a drying temperature of 150°C and a drying time of 3 hours.

[0056] (4) After drying, the solid phase is purified by acid leaching. The leaching agent for acid leaching is sulfuric acid, the acid volume concentration is 40%, the leaching reaction temperature is 90°C, the leaching liquid-solid ratio is 4:1, the leaching time is 2h, and the leaching reaction stage is 2-stage countercurrent leaching. After the acid leaching is completed, the solid and liquid are separated to obtain the acid leaching liquid and the acid leaching residue. The acid leaching residue after acid leaching is calcined at 800°C for 1h to obtain white carbon black. The obtained white carbon black includes the following chemical components TiO2, SiO2, Al2O3, CaO, MgO and Fe2O3 in the following mass percentages: 0.19%, 82.07%, 0.11%, 0.62%, 0.031%, 0.024%, respectively, and the remainder is other components. The purity of white carbon black is 99.2%. The acid leaching liquid can further recover the metal elements therein.

[0057] (5) The hydrolyzed liquid phase is subjected to precipitation reaction by adding sulfuric acid, wherein the mass concentration of the added sulfuric acid is 98%, the amount of sulfuric acid added is such that the volume ratio of sulfuric acid to the volume of the hydrolyzed liquid phase to be precipitated is 1:10, the precipitation reaction temperature is 30° C., the reaction time is 1 h, and after the reaction is completed, high-purity gypsum and a precipitated liquid phase are obtained by filtration. The high-purity gypsum includes the following chemical components in mass percentage: CaO content 31.80%, MgO content 0.081%, Al2O3 content 0.058%, TiO2 content 0.0028%, SiO2 content less than 0.02%, and the purity of the high-purity gypsum is 95%, which meets the product index requirements of high-purity gypsum.

[0058] (6) Sulfuric acid is further added to the precipitated liquid phase and distilled. The mass concentration of the added sulfuric acid is 98%. The amount of sulfuric acid added is such that the volume ratio of sulfuric acid to the volume of the liquid phase to be precipitated is 1:4. The distillation temperature is 80° C. After distillation, steam and a crystalline solid phase are obtained. The steam is condensed to obtain dilute nitric acid, which is returned to the leaching process. Under the same conditions, the regenerated nitric acid and the new nitric acid have the same leaching effect. The crystalline solid phase obtained by distillation can further recover the valuable components therein.

[0059] Example 2

[0060] A method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value, the specific steps of which are as follows:

[0061] (1) In this embodiment, the raw material selected is a yellow phosphorus slag, and its chemical composition is: CaO content 46.78%, SiO2 content 41.01%, MgO content 1.03%, Al2O3 content 3.65%, Fe2O3 content 0.056%, P2O5 content 3.07%, and other components content 4.404%. The yellow phosphorus slag is ground to a particle size of -0.074 mm, accounting for 100%. The ground yellow phosphorus slag is leached with nitric acid at room temperature. The leaching reaction conditions are: leaching reaction temperature 25°C, nitric acid volume concentration 25%, leachate solid volume ratio 7:1, leaching time 2h, and after the leaching reaction is completed, the leachate and leachate are separated by filtration to obtain leachate and leachate. The leachate can be used as an intermediate product to further recover the metal and non-metal valuable components therein.

[0062] (2) The leachate is heated to 95° C. for hydrolysis reaction. The hydrolysis reaction time is 2 h. After the reaction is completed, the hydrolysis solid phase and the hydrolysis liquid phase are obtained by filtration.

[0063] (3) The hydrolyzed solid phase is washed with water at a washing temperature of 25°C, a washing liquid-solid mass ratio of 4:1, and a washing time of 2 hours. After washing, solid-liquid separation is performed to obtain a washing liquid and a washed solid phase, and the washing liquid is returned to the nitric acid room temperature leaching step. The washed solid phase is heated and dried at a drying temperature of 150°C and a drying time of 5 hours.

[0064] (4) After drying, the hydrolyzed solid phase is purified by acid leaching. The leaching agent for acid leaching is sulfuric acid, the acid volume concentration is 70%, the leaching reaction temperature is 150°C, the leaching liquid-solid ratio is 4:1, the leaching time is 2h, and the number of leaching reaction stages is 3-stage countercurrent leaching. After the acid leaching is completed, the solid-liquid separation is performed to obtain the leachate and the solid phase. The purity of the silicon dioxide in the obtained acid leached solid phase is as high as 99.99%. The solid phase obtained by acid leaching is calcined at 2000°C for 2h to obtain high-purity quartz, and the leachate can be further used to recover the metal elements therein.

[0065] (5) The hydrolyzed liquid phase is subjected to precipitation reaction by adding sulfuric acid, wherein the mass concentration of the added sulfuric acid is 98%, the amount of sulfuric acid added is such that the volume ratio of sulfuric acid to the volume of the hydrolyzed liquid phase to be precipitated is 1:10, the precipitation reaction temperature is 25° C., the reaction time is 1 h, and after the reaction is completed, high-purity gypsum and a precipitated liquid phase are obtained by filtration. The high-purity gypsum includes the following chemical components in mass percentage: CaO content 32.01%, MgO content 0.072%, Al2O3 content 0.051%, SiO2 content less than 0.018%, which meets the product index requirements of high-purity gypsum, and the purity of the high-purity gypsum is above 93.5%.

[0066] (6) Sulfuric acid is further added to the precipitated liquid phase and distilled. The mass concentration of the added sulfuric acid is 98%. The amount of sulfuric acid added is such that the volume ratio of sulfuric acid to the volume of the liquid phase to be precipitated is 1:4. The distillation temperature is 90° C. After distillation, steam and a crystalline solid phase are obtained. The steam is condensed to obtain dilute nitric acid, which is returned to the leaching process. Under the same conditions, the regenerated nitric acid and the new nitric acid have the same leaching effect. The crystalline solid phase obtained by distillation can further recover the valuable components therein.

[0067] Example 3

[0068] A method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value, the specific steps of which are as follows:

[0069] (1) In this embodiment, the raw material selected is a hot liquid blast furnace slag, and its chemical composition is: CaO content 33.12%, SiO2 content 31.99%, MgO content 9.08%, Al2O3 content 13.82%, K2O content 0.39%, Na2O content 0.71%, CaF2 content 1.23%, TiO2 content 1.39%, rare earth content 0.81%, TFe content 1.11%, and other components content 6.35%. The hot liquid blast furnace slag is water quenched and ground to a particle size of -0.045 mm, accounting for 100%. The ground blast furnace slag is leached with nitric acid at room temperature. The leaching reaction conditions are: leaching reaction temperature 30°C, nitric acid volume concentration 30%, leaching liquid solid volume ratio 7:1, leaching time 2h, and after the leaching reaction is completed, it is filtered for solid-liquid separation to obtain leachate and leaching slag. The leached residue is used as an intermediate product to further recover the valuable metal and non-metal components therein.

[0070] (2) The leachate is heated to 95° C. for hydrolysis reaction. The hydrolysis reaction time is 2 h. After the reaction is completed, the hydrolysis solid phase and the hydrolysis liquid phase are obtained by filtration.

[0071] (3) The hydrolyzed solid phase is washed with water at a washing temperature of 25° C., a washing liquid-to-solid mass ratio of 4:1, and a washing time of 2 h. After washing, solid-liquid separation is performed to obtain a washing liquid and a washed solid phase, and the washing liquid is returned to the nitric acid room temperature leaching process; the washed solid phase is heated and dried at a drying temperature of 150° C. and a drying time of 3 h.

[0072] (4) After drying, the hydrolyzed solid phase is purified by acid leaching. The leaching agent for acid leaching is sulfuric acid, the acid volume concentration is 40%, the leaching reaction temperature is 100°C, the leaching liquid-solid ratio is 4:1, the leaching time is 2 hours, and the leaching reaction stage is 2-stage countercurrent leaching. After the acid leaching is completed, the solid-liquid separation is performed to obtain the acid leaching solution and mesoporous silica. The leaching solution can further recover the metal elements therein.

[0073] The chemical multi-element analysis results of the obtained mesoporous silica are as follows: SiO2 content is 99.5%, Al2O3 content is 0.08%, CaO content is 0.05%, MgO content is 0.06%, Fe2O3 content is 0.03%, and the remainder is inevitable impurities. Figure 2 The BET analysis results of the obtained mesoporous silica showed that the BET specific surface area of ​​the obtained mesoporous silica was 552.1689 m 2 / g, pore volume is 0.756234cm 3 / g, the average pore size is The type of adsorption isotherm obtained by measurement shows that the adsorption isotherm belongs to type IV H2 type, which is bounded by H 2a Type and H 2b Type, closer to H 2b This result indicates that the pore structure of the material is complex, which may include typical "ink bottle" pores, tubular pores with uneven pore size distribution, and interstitial pores of densely packed spherical particles. 2a Hysteresis loops of this type are common in silica gels and some ordered three-dimensional mesoporous materials. 2b Type relative to H 2a For the type, the size distribution of the pore neck width is much wider, which is common in mesoporous foam silicon (MCFs) and some ordered mesoporous silicon materials after hydrothermal treatment. Therefore, it can be determined that the material belongs to mesoporous material.

[0074] (5) The hydrolyzed liquid phase is subjected to precipitation reaction by adding sulfuric acid, wherein the mass concentration of the added sulfuric acid is 98%, the amount of sulfuric acid added is such that the volume ratio of sulfuric acid to the volume of the liquid phase to be precipitated is 1:10, the precipitation reaction temperature is 25° C., the reaction time is 1 h, and after the reaction is completed, high-purity gypsum and a precipitated liquid phase are obtained by filtration. The high-purity gypsum includes the following chemical components in mass percentage: CaO content 31.09%, MgO content 0.078%, Al2O3 content 0.031%, SiO2 content less than 0.019%, which meets the product index requirements of high-purity gypsum, and the purity of the high-purity gypsum is 98%.

[0075] (6) Sulfuric acid is further added to the precipitated liquid phase and distilled. The mass concentration of the added sulfuric acid is 98%. The amount of sulfuric acid added is such that the volume ratio of sulfuric acid to the volume of the liquid phase to be precipitated is 1:4. The distillation temperature is 90° C. After distillation, steam and a crystalline solid phase are obtained. The steam is condensed to obtain dilute nitric acid, which is returned to the leaching process. Under the same conditions, the regenerated nitric acid and the new nitric acid have the same leaching effect. The crystalline solid phase obtained by distillation can further recover the valuable components therein.

[0076] The above is the entire content of the present invention. Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the protection scope of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value, characterized in that: The steps include: (1) selecting at least one of materials containing calcium silicate and / or calcium silicate as raw material; (2) grinding the raw material selected in step (1), and then leaching with nitric acid at room temperature, and separating the solid and liquid after leaching to obtain a leachate and a leaching residue; (3) heating the leaching solution obtained in step (2) to carry out a chemical reaction, and after the reaction is completed, separating the solid and the liquid to obtain a solid phase and a liquid phase; (4) adding sulfuric acid solution to the liquid phase obtained in step (3) for precipitation reaction, and after the precipitation is completed, solid-liquid separation is performed to obtain the liquid phase and high-purity gypsum; (5) adding sulfuric acid solution to the liquid phase obtained in step (4) for distillation, distilling to obtain steam and solid phase crystals, condensing the steam to obtain regenerated nitric acid, and returning the regenerated nitric acid to step (2) for leaching reaction; (6) washing and drying the solid phase obtained in step (3) to obtain a dried solid phase, and returning the washing liquid obtained by solid-liquid separation in the washing process to the nitric acid leaching process in step (2); (7) subjecting the dried solid phase obtained in step (6) to acid leaching, and after the acid leaching is completed, solid-liquid separation is performed to obtain a leachate and a solid phase; (8) The solid phase obtained in step (7) is calcined to obtain a silicon-based material.

2. The method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value according to claim 1, characterized in that: In the step (1), the material containing calcium silicate and / or calcium silicate is various solid materials, intermediate products, by-products or waste materials containing calcium silicate or calcium silicate phases produced in the fields of ore mining and processing, metallurgy, materials, chemical industry, energy and environment; the chemical components of the material containing calcium silicate and / or calcium silicate include CaO and SiO2.

3. The method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value according to claim 1, characterized in that: In the step (2), the conditions for nitric acid leaching are: leaching temperature of 10-40° C., nitric acid volume concentration of 10%-50%, liquid-solid mass ratio of 10:1-2:1, and leaching time of 0.5-3 h.

4. The method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value according to claim 1, characterized in that: In the step (3), the heating temperature is 60 to 100° C. and the heating time is 0.5 to 3 hours.

5. The method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value according to claim 1, characterized in that: In the step (4), the mass concentration of the sulfuric acid solution is 50% to 98%, the volume ratio of the liquid phase to the sulfuric acid solution is 1:5 to 1:50, the temperature of the precipitation reaction is 10 to 100° C., and the time is 0.5 to 3 hours.

6. The method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value according to claim 1, characterized in that: In the step (5), the mass concentration of the sulfuric acid solution is 50% to 98%, the volume ratio of the sulfuric acid solution to the liquid phase is 1:2 to 1:10; and the distillation temperature is 80 to 100°C.

7. The method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value according to claim 1, characterized in that: In the step (6), the washing solvent is water or nitric acid solution, the washing temperature is 10-100°C, the washing liquid-solid mass ratio is 8:1-3:1, the washing time is 0.5-3h, and the number of washing times is 1-3 times of countercurrent washing; the volume concentration of the nitric acid solution is 3%-10%; the drying temperature is 100-300°C, and the drying time is 0.5-10h.

8. The method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value according to claim 1, characterized in that: The acid leaching conditions in step (7) are as follows: the leaching agent is at least one of sulfuric acid, nitric acid and hydrochloric acid, the acid volume concentration is 5% to 80%, the leaching reaction temperature is 50 to 200° C., the leaching liquid-solid mass ratio is 8:1 to 2:1, the leaching time is 0.5 to 3 hours, and the number of leaching reaction stages is 1 to 5 countercurrent leaching.

9. The method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value according to claim 1, characterized in that: In the step (8), the calcination temperature is 700 to 2500° C., and the calcination time is 0.5 to 3 hours.

10. The method for comprehensive utilization of materials containing calcium silicate or calcium silicate phase with high added value according to claim 1, characterized in that: The silicon-based material is white carbon black, porous silicon dioxide or high-purity silicon dioxide; the purity of the high-purity silicon dioxide is higher than 99%; the purity of the high-purity gypsum is higher than 80%.

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