Method for recovering and extracting white carbon black from smelting slag

Abstract

The invention belongs to the technical field of waste residue, waste gas, waste water and three-waste synergistic utilization treatment, and relates to a method for recovering and extracting white carbon black from smelting slag. The method comprises the following steps: uniformly mixing slag tailings obtained after beneficiation of copper smelting slag with sodium bicarbonate, and then carrying out microwave roasting to obtain roasted slag containing sodium silicate, sodium zincate and sodium plumbate; the roasting slag and water are mixed for leaching treatment, and then solid-liquid separation is conducted to obtain leaching liquid and leaching slag; carbon dioxide is introduced into the leachate for one-step microwave carbon separation treatment, and one-step carbonized liquid is obtained; adding sodium chloride into the first-step carbonization solution, and introducing carbon dioxide to carry out second-step microwave carbon separation treatment to obtain second-step microwave carbon separation residues; and washing and drying the two-step microwave carbon residue to obtain the product. According to the method, only sodium bicarbonate and sodium chloride are used, and a microwave carbon separation technology is combined, so that the reaction process is strengthened and simplified, and a high-quality powdery white carbon black product can be directly and efficiently prepared.

Description

Technical Field

[0001] This invention belongs to the field of co-utilization and treatment technology of waste residue, waste gas and wastewater, and relates to a method for recovering and extracting silica from smelting slag. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Smelting slag (hereinafter referred to as copper smelting slag) generated during copper smelting is an important solid waste, which usually contains a certain amount of valuable metals such as copper and iron, as well as a large amount of silicon dioxide. Traditional methods of resource utilization of copper smelting slag mainly focus on recovering the metal components (such as copper) through methods such as mineral processing. However, the large amount of tailings generated after mineral processing, which is mainly composed of silicon dioxide, has limited high-value utilization channels and is mostly sold or stockpiled for disposal. This not only wastes silicon resources but also poses environmental risks.

[0004] Research indicates that the current method for recovering silica from copper smelting slag involves first forming the slag into pellets, then smelting, crushing, grinding, and water leaching. Subsequently, silica is produced using carbon fractionation, followed by deep carbon fractionation to produce sodium bicarbonate. However, further research has revealed several problems with this method: 1. The process is lengthy, the pelletizing equipment is complex, and the material requirements are stringent, necessitating the addition of reducing agents such as carbon powder and coal powder. This makes the process difficult to implement. 2. Using soda ash and sodium bicarbonate as the smelting fractions in the pelletizing process increases carbon dioxide emissions, contradicting carbon reduction goals. 3. Using sodium bicarbonate solution for carbon fractionation to produce silica and soda ash solution for deep carbon fractionation to produce sodium bicarbonate involves a variety of reagents. While sodium bicarbonate is recycled, the increasing impurities in the solution still present challenges for wastewater treatment. 4. Carbon fractionation using sodium bicarbonate solution first produces colloidal silica, which requires drying and grinding to obtain powdered silica. The grinding process increases the iron content, affecting the quality of the silica. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for recovering and extracting precipitated silica from smelting slag. This invention utilizes only sodium bicarbonate and sodium chloride, combined with microwave carbon separation technology, to enhance and simplify the reaction process, enabling the direct and efficient production of high-quality powdered precipitated silica. Furthermore, this invention co-processes carbon dioxide in the smelting acid tail gas during the preparation of high-value precipitated silica, thereby reducing carbon emissions during the smelting process.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, a method for recovering and extracting silica from smelting slag includes the following steps: The tailings of copper smelting slag after mineral processing are mixed evenly with sodium bicarbonate and then microwave roasted to obtain roasted slag containing sodium silicate, sodium zincate and sodium leadate. The roasted residue is mixed with water for leaching treatment, and then solid-liquid separation is performed to obtain leachate and leaching residue; Carbon dioxide is introduced into the leachate for one-step microwave carbonization treatment until the solution pH drops to 10.5~11.0, and solid-liquid separation is performed to obtain one-step carbonized liquid and one-step microwave carbonization residue. Sodium chloride was added to the first-step carbonization liquid and carbon dioxide was introduced for a second-step microwave carbonization treatment until the solution pH dropped to 8.8-9.2. After solid-liquid separation, a second-step carbonization liquid and a second-step microwave carbonization residue were obtained. The residue is obtained by washing and drying the residue after two-step microwave carbonization.

[0008] This invention uses sodium bicarbonate mixed with tailings and then microwave roasted. The main reactions occurring during the roasting process include: ; ; .

[0009] After the above reaction, the resulting roasting slag contains soluble sodium salts such as sodium silicate, sodium zincate, and sodium leadate. These soluble sodium salts, including sodium silicate, can be extracted from the roasting slag through subsequent leaching treatment. Microwave roasting is a heat treatment method that uses microwaves as the roasting heat source. During microwave roasting, the mixture of tailings and sodium bicarbonate is heated as the shaft moves forward, continuously producing roasting slag. Simultaneously, microwaves act as a dynamic catalyst at high temperatures, and Fe3O4 has strong microwave absorption properties. During microwave roasting, more cracks appear on the surface of the tailings, exposing more fresh surfaces, which can significantly shorten the roasting time and reduce the amount of reagents used. Microwave high-temperature sintering results in a significant phase transformation, with a more uniform distribution of silicon and iron, and the Fe3O4 in the tailings is oxidized to Fe2O3. Microwaves can penetrate to a depth of up to 300m into the tailings, completing the heating and catalytic process of the material layer. Therefore, microwave calcination can use a small amount of chemical reagents to convert silicates into soluble sodium salts such as sodium silicate more quickly and thoroughly, providing a foundation for the efficient preparation of high-quality powdered silica products.

[0010] This invention involves leaching roasted slag followed by two microwave carbonization treatments: a one-step microwave carbonization and a two-step microwave carbonization. The one-step microwave carbonization, by controlling the amount of carbon dioxide added and the pH of the solution, mainly includes the following reactions: ; .

[0011] Through solid-liquid separation, impurities can be enriched and discharged from the system, ensuring that subsequent processing can efficiently produce high-quality silica products. In the one-step microwave carbonization process, which involves carbonization based on the formation of carbonate precipitation by introducing carbon dioxide, microwave-assisted treatment is applied. Microwaves enhance the interaction between the carbon dioxide and the introduced carbon dioxide during carbonization, generating localized high temperatures and pressures, thereby increasing the reaction rate and catalyzing the reaction. Simultaneously, the interaction with bubbles formed by carbon dioxide in the solution creates turbulence, breaking down the static liquid layer and generating uniform, fine "seed crystals" or initial gel particles, laying a good foundation for subsequent growth.

[0012] In the process of preparing precipitated silica from a one-step carbonization solution, the main purpose of the one-step microwave carbonization is to remove impurities. Therefore, microwaves are used to ensure good results, but the problem of low uniformity still exists. Directly adding acid can easily produce uneven agglomerates, especially if the one-step carbonization solution contains uniform, fine "seed crystals" or initial gel particles. The reaction is difficult to control, resulting in an underdeveloped pore structure and a tendency for the prepared precipitated silica to become dense. Particle size and dispersibility: Primary particles easily agglomerate, resulting in poor dispersibility; weak process control; and large fluctuations in product performance. Therefore, this invention employs a two-step microwave carbonization process, the main reactions of which are as follows: .

[0013] In the two-step microwave carbonization process, sodium chloride is added to adjust the colloidal stability. Microwaves can increase the reaction rate and act as a catalyst. The generated (SiO2·nH2O) is encapsulated in liquid, and under microwave irradiation, the liquid inclusions burst, forming finer and more uniform (SiO2·nH2O). The second microwave carbonization allows the initial particles formed in the first step to further grow and mature, completing the precipitation of all silicon. The two-step carbonization method produces products with high uniformity and narrow particle size and morphology distribution. It also results in a high and controllable specific surface area (reaching 100~400 μm). 2 (Above / g), the first step of nucleation is mostly microporous / mesoporous. The pore structure is well-developed and adjustable. Particle size and dispersibility: the primary particles are small, the aggregate structure is controllable, and it disperses well in the substrate. The process is highly controllable; products can be "customized" by controlling the pH, rate, and temperature of both steps.

[0014] In some implementations, the carbon dioxide used in the one-step and two-step microwave carbon separation processes originates from the flue gas generated during the smelting process. Specifically, the flue gas passes through an acid-generating system to produce smelting acid-generating tail gas (SO2, CO2, N2, H2O, O2). This tail gas is desulfurized and denitrified, and carbon dioxide is enriched to obtain carbon dioxide for microwave carbon separation. Compared to high-purity carbon dioxide, this carbon dioxide has a lower purity, and its impurities do not participate in the carbon separation reaction. It also helps to avoid excessive local acid concentrations during the carbon separation process, which can lead to large agglomerates.

[0015] In a second aspect, a system for recovering and extracting silica from smelting slag, for implementing the method described in the first aspect of the present invention, includes: Microwave roasting equipment is used for microwave roasting of materials made by mixing tailings and sodium bicarbonate. The leaching tank is configured to be connected to a water source and is used to leach out the roasting residue produced by the microwave roasting device. A one-step microwave carbonization reactor is used for one-step microwave carbonization treatment of the leachate from the leaching tank. A two-step microwave carbonization reactor is used to perform two-step microwave carbonization on the one-step carbonized liquid from the two-step microwave carbonization process.

[0016] In some implementations, a CO2 capture device for smelting acid production tail gas is also included, which is used to generate smelting acid production tail gas by passing the flue gas generated in the smelting process through the acid production system, desulfurizing and denitrifying the smelting acid production tail gas, enriching carbon dioxide, and thus obtaining carbon dioxide for microwave carbon separation.

[0017] The beneficial effects of this invention are as follows: 1. This invention uses sodium bicarbonate as a roasting aid and combines it with microwave roasting technology. By utilizing the bulk heating characteristics, dynamic catalytic effect, and selective absorption of magnetic minerals such as Fe3O4 by microwaves, the sodium salt conversion rate of silicates is significantly accelerated, the reaction efficiency is improved, and the amount of sodium bicarbonate used is greatly reduced. At the same time, the roasting process is made continuous and rapid.

[0018] 2. The method provided by this invention exhibits significant synergistic effects from microwave treatment. First, during the roasting stage, the strong penetrating power of microwaves ensures uniform heating of the material, induces mineral phase transformation, generates microcracks on the surface, and exposes fresh active surfaces, greatly promoting the formation of soluble sodium salts such as sodium silicate, laying the foundation for efficient leaching. Second, in the carbonization stage, microwave assistance is introduced in both steps: in the first carbonization step, microwaves catalyze the CO2 reaction, generate local high temperature and pressure, and form turbulence, which is conducive to the formation of uniform and fine silica gel "nuclei" and effectively separates and removes impurities such as zinc and lead; in the second carbonization step, microwaves cause liquid inclusions to burst, further refining and homogenizing silica hydrate particles, achieving controllable particle growth and maturation.

[0019] 3. The method provided by this invention employs a two-step microwave carbonization process, combined with precise pH control and the addition of sodium chloride to adjust colloidal stability. The resulting silica product has a high specific surface area (up to 100~400 m²). 2 It features a high density of micropores (over 1 g), a well-developed pore structure (adjustable micropore / mesopore), small primary particles, controllable agglomeration, and good dispersibility. Process parameters are flexible and adjustable, allowing for "customization" of product performance.

[0020] 4. The method of this invention achieves high-value-added resource utilization of copper smelting slag tailings, converting waste slag into high-grade silica products, while simultaneously recovering valuable metals such as zinc and lead. Utilizing treated CO2 from smelting flue gas as a carbon separation gas source enables resource recycling of waste gas, reducing raw material costs. Furthermore, the low-purity CO2 avoids gel agglomeration problems caused by localized over-acidity, promoting product uniformity. The entire process reduces solid waste emissions and achieves targeted removal of harmful elements and efficient extraction of silicon resources. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 This is a process flow diagram of the method provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the CO2 capture device for acid production tail gas in an embodiment of the present invention; wherein, 1, desulfurization combined tower, 2, primary circulation pump, 3, dilute acid storage tank, 4, hydrogen peroxide supply pump, 5, hydrogen peroxide storage tank, 6, secondary circulation pump, 7, secondary circulation tank, 8, tubular reactor, 9, booster fan, 10, denitrification combined tower, 11, absorption circulation pump, 12, sodium thiosulfate dosing pump, 13, reagent pump, 14, reagent storage tank, 15, electric heater, 16, hot air blower, 17, carbon monoxide and sulfur dioxide concentration detection device, 18, acid concentration detection device. Detailed Implementation

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Given that existing technologies make it difficult to recover and utilize silica in copper smelting slag tailings at high value, this invention proposes a method for recovering and extracting silica from smelting slag.

[0026] A typical embodiment of the present invention provides a method for recovering and extracting silica from smelting slag, comprising the following steps: The tailings of copper smelting slag after mineral processing are mixed evenly with sodium bicarbonate and then microwave roasted to obtain roasted slag containing sodium silicate, sodium zincate and sodium leadate. The roasted residue is mixed with water for leaching treatment, and then solid-liquid separation is performed to obtain leachate and leaching residue; Carbon dioxide is introduced into the leachate for one-step microwave carbonization treatment until the solution pH drops to 10.5~11.0, and solid-liquid separation is performed to obtain one-step carbonized liquid and one-step microwave carbonization residue. Sodium chloride was added to the first-step carbonization liquid and carbon dioxide was introduced for a second-step microwave carbonization treatment until the solution pH dropped to 8.8-9.2. After solid-liquid separation, a second-step carbonization liquid and a second-step microwave carbonization residue were obtained. The residue is obtained by washing and drying the residue after two-step microwave carbonization.

[0027] In some embodiments, during microwave calcination, the temperature is 400~500℃, the microwave frequency is 1800~2200MHz, the heating rate is 55~65℃ / min, and the calcination time is 18~22min. Studies have shown that the results are better under these microwave calcination conditions.

[0028] In some embodiments, during the leaching process, the liquid-to-solid ratio is 10-15:1, the temperature is 35-45°C, and the treatment time is 45-55 minutes. Studies have shown that the leaching effect is better under these conditions. The unit of liquid-to-solid ratio is "1".

[0029] In some embodiments, the leaching residue is dried and ground to obtain leaching residue powder, which is then smelted into high-purity iron. The high-purity iron described in this invention refers to iron with a purity of not less than 99.9%. Specifically, the leaching residue powder is smelted in a plasma furnace. A hydrogen-nitrogen mixed gas is ionized into plasma through a plasma nozzle under the action of high-frequency voltage and an electric arc, and then ejected from the plasma nozzle. The leaching residue powder is injected into the plasma flame region, where it is melted by the high-temperature plasma flame and reduced to high-purity iron at 900°C under nitrogen protection with hydrogen plasma. The reaction formula for this process includes: ; ; ; ; ; .

[0030] In some embodiments, the carbon dioxide used in the one-step and two-step microwave carbon separation processes originates from the flue gas generated during the smelting process. Specifically, the flue gas passes through an acid production system to generate smelting acid production tail gas. This tail gas is then desulfurized and denitrified, and enriched with carbon dioxide to obtain carbon dioxide for microwave carbon separation. This method can solve the problem of high-value utilization of CO2 from copper smelting acid production tail gas, achieving carbon neutrality through carbon capture and utilization.

[0031] In some embodiments, during the one-step microwave carbonization process, the temperature is 75~85℃, the microwave power is 550~650W, and the microwave frequency is 2.0~2.2GHz. Carbonization results are better under these conditions.

[0032] In some embodiments, during the two-step microwave carbonization process, the temperature is 75~85℃, the microwave power is 550~650W, and the microwave frequency is 2.0~2.2GHz. Carbonization is more effective under these conditions.

[0033] In some embodiments, during the two-step microwave carbonization process, after the solution pH drops to a set value, the reaction continues for 25-35 minutes. This ensures a complete reaction and further improves product uniformity.

[0034] Another embodiment of the present invention provides a system for recovering and extracting silica from smelting slag, for implementing the method described in the first aspect of the present invention, comprising: Microwave roasting equipment is used for microwave roasting of materials made by mixing tailings and sodium bicarbonate. The leaching tank is configured to be connected to a water source and is used to leach out the roasting residue produced by the microwave roasting device. A one-step microwave carbonization reactor is used for one-step microwave carbonization treatment of the leachate from the leaching tank. A two-step microwave carbonization reactor is used to perform two-step microwave carbonization on the one-step carbonized liquid from the two-step microwave carbonization process.

[0035] In some embodiments, a CO2 capture device for smelting acid production tail gas is further included, which is used to generate smelting acid production tail gas from the flue gas generated in the smelting process through the acid production system, and to desulfurize and denitrify the smelting acid production tail gas, enriching it with carbon dioxide, thereby obtaining carbon dioxide for microwave carbon separation. Specifically, its structure is as follows: Figure 2 As shown, it includes a desulfurization combined tower 1, a primary circulation pump 2, a dilute acid storage tank 3, a hydrogen peroxide supply pump 4, a hydrogen peroxide storage tank 5, a secondary circulation pump 6, a secondary circulation tank 7, a tubular reactor 8, a booster fan 9, a denitrification combined tower 10, an absorption circulation pump 11, a sodium thiosulfate dosing pump 12, a reagent pump 13, a reagent storage tank 14, an electric heater 15, a hot air blower 16, a carbon monoxide and sulfur dioxide concentration detection device 17, and an acid concentration detection device 18.

[0036] In some embodiments, the system further includes an iron smelting apparatus for smelting high-purity iron from leaching residue powder obtained by drying and grinding leaching residue. Specifically, the iron smelting apparatus is a plasma furnace.

[0037] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0038] Example 1: A method for recovering and extracting silica from smelting slag includes the following steps: (1) Smelting. Raw materials (copper concentrate, flux, etc.) are mixed and added to a smelting furnace to react and produce matte, smelting slag, flue gas, etc. After cooling and crushing, the smelting slag is ground and classified to achieve the degree of separation of useful mineral particles into individual particles, and slag concentrate is selected and slag tailings are produced. The flue gas is removed by a waste heat boiler, dust settling chamber, electrostatic precipitator and other dust removal processes and then enters the acid production system, which then produces smelting acid production tail gas.

[0039] (2) Microwave roasting. The composition of the tailings slag after copper smelting slag beneficiation is shown in the table below.

[0040] name Cu / % Fe / % S / % <![CDATA[SiO2 / %]]> <![CDATA[Al2O 3 / %]]> Sb / % Bi / % CaO / % MgO / % As / % Pb / % Zn / % <![CDATA[Fe3O4 / %]]> tailings 0.34 39.68 0.2 28.19 5.17 0.016 <0.01 2.34 0.6 0.21 0.098 1.17 13.9 The tailings and sodium bicarbonate are mixed evenly at a ratio of 4:1. The feed speed is adjusted, and the tailings are continuously fed into the microwave cavity of the continuous microwave dynamic roasting system. The microwave and rotation are turned on at the same time as the feed, so that the tailings are heated as they move forward with the rotating shaft. The temperature is controlled at 450℃, the microwave frequency is 1800MHz, the average heating rate is 59.5℃ / min, and the roasting time is 20min by adjusting the power of the magnetron. Roasted slag is produced continuously.

[0041] (3) CO2 capture from sulfuric acid production tail gas. The sulfuric acid production tail gas first undergoes desulfurization in a desulfurization combined tower, where sulfur is removed by sequential adsorption in an adsorption bed composed of hydrogen peroxide solution adsorbent. Then, it is pressurized by a blower and directly enters a denitrification combined tower, where most of the nitrogen is removed by sequential adsorption in an adsorption bed composed of sodium thiosulfate solution adsorbent, directly obtaining carbon dioxide-rich gas for microwave carbon separation. The adsorbent after adsorption saturation is regenerated by vacuum pumping, and the regenerated nitrogen-rich gas is stored in a liquid nitrogen storage tank for use in the production system.

[0042] (4) Leaching. The roasted residue is transported to the leaching tank, the pure water valve is opened, and the corresponding pure water is added at a liquid-to-solid ratio of 12:1. The steam valve is opened to heat the water to 40°C, and the mixture is stirred and reacted for 50 minutes. The leachate and leaching residue are obtained by filtration. The composition of the leaching residue is shown in the table below.

[0043] Sample Name Cu / % Fe / % <![CDATA[SiO2%]]> <![CDATA[Al2O3 / %]]> Pb / % Zn / % Na / % K / % Leaching residue 0.17 45.37 6.99 1.44 0.24 0.93 44.84 0.02 (5) Plasma reduction. The leaching residue is dried and ground to obtain leaching residue powder. The leaching residue powder is smelted in a plasma furnace. A hydrogen-nitrogen mixed gas is ionized into plasma through a plasma nozzle under the action of high-frequency voltage and electric arc and ejected from the plasma nozzle. The leaching residue powder is injected into the plasma flame area and melted by the high-temperature plasma flame. Under nitrogen protection at 900°C, it is reduced with hydrogen plasma to produce high-purity iron.

[0044] (6) One-step microwave carbonization: The leachate is introduced into a one-step microwave carbonization reactor at a reaction temperature of 80°C. Stirring and microwave catalysis are performed at a microwave power of 600W and a frequency of 2.1GHz. Smelting acid production tail gas is injected to capture CO2 gas (45%) until the solution pH drops to 10.8. Microwave carbonization is then stopped, and solid-liquid separation is achieved.

[0045] (7) Two-step microwave carbonization: The first-step carbonization liquid is introduced into the two-step microwave carbonization reactor. The reaction temperature is 80°C. Stirring and microwave catalysis are used. The microwave power is 600W and the frequency is 2.1GHz. CO2 gas (45%) is introduced and sodium chloride (0.2% of fumed silica) is added. The second microwave carbonization is carried out until the pH value of the solution drops to 9. The reaction is continued for 30 minutes. Microwave carbonization is stopped and solid-liquid separation is performed. The solid is washed in the washing tank.

[0046] (8) Drying. The washing residue is dried by a continuous belt dryer with controlled frequency and automatic temperature control mode. The drying temperature is 90℃ and the thickness of the material is controlled at 10mm. After 30 minutes of drying, powdered product white carbon black (SiO2·nH2O) is continuously produced. Its composition is shown in the table below.

[0047] name Cu / % Fe / % <![CDATA[SiO2 / %]]> Ca / % As / % Na / % K / % Pb / % Zn / % Al / % Cd / % precipitate 0.0039 0.063 94.36 <0.0010 <0.001 2.65 0.092 0.19 2.3 0.34 <0.0010 Example 2: A method for recovering and extracting silica from smelting slag includes the following steps: (1) Smelting. Raw materials (copper concentrate, flux, etc.) are mixed and added to a smelting furnace to react and produce matte, smelting slag, flue gas, etc. After cooling and crushing, the smelting slag is ground and classified to achieve the degree of separation of useful mineral particles into individual particles, and slag concentrate is selected and slag tailings are produced. The flue gas is removed by a waste heat boiler, dust settling chamber, electrostatic precipitator and other dust removal processes and then enters the acid production system, which then produces smelting acid production tail gas.

[0048] (2) Microwave roasting. The composition of the tailings slag after copper smelting slag beneficiation is shown in the table below.

[0049] name Cu / % Fe / % S / % <![CDATA[SiO2 / %]]> <![CDATA[Al2O 3 / %]]> Sb / % Bi / % CaO / % MgO / % As / % Pb / % Zn / % <![CDATA[Fe3O4 / %]]> tailings 0.33 0.25 39.22 36.44 5.23 0.019 <0.01 2.22 0.58 0.2 0.1 1.2 14.3 The tailings and sodium bicarbonate are mixed evenly at a ratio of 4:1.2. The feed speed is adjusted, and the tailings are continuously fed into the microwave cavity of the continuous microwave dynamic roasting system. The microwave and rotation are turned on at the same time as the feed, so that the tailings are heated as they move forward with the rotating shaft. The temperature is controlled at 420℃, the microwave frequency is 2100MHz, the average heating rate is 55.5℃ / min, and the roasting time is 18min by adjusting the power of the magnetron. Roasted slag is produced continuously.

[0050] (3) CO2 capture from sulfuric acid production tail gas. The sulfuric acid production tail gas first undergoes desulfurization in a desulfurization combined tower, where sulfur is removed by sequential adsorption in an adsorption bed composed of hydrogen peroxide solution adsorbent. Then, it is pressurized by a blower and directly enters a denitrification combined tower, where most of the nitrogen is removed by sequential adsorption in an adsorption bed composed of sodium thiosulfate solution adsorbent, directly obtaining carbon dioxide-rich gas for microwave carbon separation. The adsorbent after adsorption saturation is regenerated by vacuum pumping, and the regenerated nitrogen-rich gas is stored in a liquid nitrogen storage tank for use in the production system.

[0051] (4) Leaching. The roasted residue is transported to the leaching tank, the pure water valve is opened, and the corresponding pure water is added at a liquid-to-solid ratio of 10:1. The steam valve is opened to heat the water to 35°C, and the mixture is stirred for 55 minutes. The leaching solution and leaching residue are obtained by filtration. The composition of the leaching residue is shown in the table below.

[0052] Sample Name Cu / % Fe / % <![CDATA[SiO2%]]> <![CDATA[Al2O3 / %]]> Pb / % Zn / % Na / % K / % Leaching residue 0.12 45.19 5.01 0.25 0.17 0.62 48.63 0.01 (5) Plasma reduction. The leaching residue is dried and ground to obtain leaching residue powder. The leaching residue powder is smelted in a plasma furnace. A hydrogen-nitrogen mixed gas is ionized into plasma through a plasma nozzle under the action of high-frequency voltage and electric arc and ejected from the plasma nozzle. The leaching residue powder is injected into the plasma flame area and melted by the high-temperature plasma flame. Under nitrogen protection at 900°C, it is reduced with hydrogen plasma to produce high-purity iron.

[0053] (6) One-step microwave carbonization: The leachate is introduced into a one-step microwave carbonization reactor at a reaction temperature of 80°C. Stirring and microwave catalysis are performed at a microwave power of 550W and a frequency of 2GHz. Smelting acid production tail gas is injected to capture CO2 gas (42%) until the solution pH drops to 10.8. Microwave carbonization is then stopped, and solid-liquid separation is achieved.

[0054] (7) Two-step microwave carbonization: The first-step carbonization liquid is introduced into the two-step microwave carbonization reactor. The reaction temperature is 80°C. Stirring and microwave catalysis are used. The microwave power is 550W and the frequency is 2GHz. CO2 gas (42%) is captured from the tail gas of smelting acid production. Sodium chloride (0.2% of the amount of white carbon black) is added. The second microwave carbonization is carried out until the pH value of the solution drops to 9. The reaction is continued for 30 minutes. The microwave carbonization is stopped, and the solid and liquid are separated. The solid is washed in the washing tank.

[0055] (8) Drying. The washing residue is dried by a continuous belt dryer with controlled frequency and automatic temperature control mode. The drying temperature is 90℃ and the thickness of the material is controlled at 10mm. After 30 minutes of drying, powdered product white carbon black (SiO2·nH2O) is continuously produced. Its composition is shown in the table below.

[0056] name Cu / % Fe / % <![CDATA[SiO2 / %]]> Ca / % As / % Na / % K / % Pb / % Zn / % Al / % Cd / % precipitate 0.021 0.048 98.12 0.0047 0.0029 0.35 0.11 0.0093 0.61 0.72 <0.0010 Example 3: A method for recovering and extracting silica from smelting slag includes the following steps: (1) Smelting. Raw materials (copper concentrate, flux, etc.) are mixed and added to a smelting furnace to react and produce matte, smelting slag, flue gas, etc. After cooling and crushing, the smelting slag is ground and classified to achieve the degree of separation of useful mineral particles into individual particles, and slag concentrate is selected and slag tailings are produced. The flue gas is removed by a waste heat boiler, dust settling chamber, electrostatic precipitator and other dust removal processes and then enters the acid production system, which then produces smelting acid production tail gas.

[0057] (2) Microwave roasting. The composition of the tailings slag after copper smelting slag beneficiation is shown in the table below.

[0058] name Cu / % Fe / % S / % <![CDATA[SiO2 / %]]> <![CDATA[Al2O 3 / %]]> Sb / % Bi / % CaO / % MgO / % As / % Pb / % Zn / % <![CDATA[Fe3O4 / %]]> tailings 0.26 39.04 0.2 36.00 3.38 0.019 0.018 3.71 0.76 0.15 0.1 0.77 15.6 The tailings and sodium bicarbonate are mixed evenly at a ratio of 4:1.3. The feed speed is adjusted, and the tailings are continuously fed into the microwave cavity of the continuous microwave dynamic roasting system. The microwave and rotation are turned on at the same time as the feed, so that the tailings are heated as they move forward with the rotating shaft. The temperature is controlled at 450℃, the microwave frequency is 1900MHz, the average heating rate is 57℃ / min, and the roasting time is 21min by adjusting the power of the magnetron. Roasted slag is produced continuously.

[0059] (3) CO2 capture from sulfuric acid production tail gas. The sulfuric acid production tail gas first undergoes desulfurization in a desulfurization combined tower, where sulfur is removed by sequential adsorption in an adsorption bed composed of hydrogen peroxide solution adsorbent. Then, it is pressurized by a blower and directly enters a denitrification combined tower, where most of the nitrogen is removed by sequential adsorption in an adsorption bed composed of sodium thiosulfate solution adsorbent, directly obtaining carbon dioxide-rich gas for microwave carbon separation. The adsorbent after adsorption saturation is regenerated by vacuum pumping, and the regenerated nitrogen-rich gas is stored in a liquid nitrogen storage tank for use in the production system.

[0060] (4) Leaching. The roasted residue is transported to the leaching tank, the pure water valve is opened, and the corresponding pure water is added at a liquid-to-solid ratio of 11:1. The steam valve is opened to heat the water to 37°C, and the mixture is stirred for 47 minutes. The leachate and leaching residue are obtained by filtration. The composition of the leaching residue is shown in the table below.

[0061] Sample Name Cu / % Fe / % <![CDATA[SiO2%]]> <![CDATA[Al2O3 / %]]> Pb / % Zn / % Na / % K / % Leaching residue 0.11 47.86 4.08 0.62 0.19 0.27 46.86 0.01 (5) Plasma reduction. The leaching residue is dried and ground to obtain leaching residue powder. The leaching residue powder is smelted in a plasma furnace. A hydrogen-nitrogen mixed gas is ionized into plasma through a plasma nozzle under the action of high-frequency voltage and electric arc and ejected from the plasma nozzle. The leaching residue powder is injected into the plasma flame area and melted by the high-temperature plasma flame. Under nitrogen protection at 900°C, it is reduced with hydrogen plasma to produce high-purity iron.

[0062] (6) One-step microwave carbonization: The leachate is introduced into a one-step microwave carbonization reactor at a reaction temperature of 80°C. Stirring and microwave catalysis are performed at a microwave power of 600W and a frequency of 2.1GHz. Smelting acid production tail gas is injected to capture CO2 gas (47%) until the solution pH drops to 10.8. Microwave carbonization is then stopped, and solid-liquid separation is achieved.

[0063] (7) Two-step microwave carbonization: The first-step carbonization liquid is introduced into the two-step microwave carbonization reactor. The reaction temperature is 80℃. Stirring and microwave catalysis are used. The microwave power is 570W and the frequency is 2100GHz. CO2 gas (47%) is introduced and sodium chloride (0.2% of fumed silica) is added. The second microwave carbonization is carried out until the pH value of the solution drops to 9. The reaction is continued for 30 minutes. The microwave carbonization is stopped and the solid and liquid are separated. The solid is washed in the washing tank.

[0064] (8) Drying. The washing residue is dried by a continuous belt dryer with controlled frequency and automatic temperature control mode. The drying temperature is 90℃ and the thickness of the material is controlled at 10mm. After 30 minutes of drying, powdered product white carbon black (SiO2·nH2O) is continuously produced. Its composition is shown in the table below.

[0065] name Cu / % Fe / % <![CDATA[SiO2 / %]]> Ca / % As / % Na / % K / % Pb / % Zn / % Al / % Cd / % precipitate <0.0010 0.024 97.08 0.0086 0.002 <1.28 0.18 0.02 0.62 0.79 <0.0010 Example 4: A method for recovering and extracting silica from smelting slag, such as Figure 1 As shown, it includes the following steps: (1) Smelting. Raw materials (copper concentrate, flux, etc.) are mixed and added to a smelting furnace to react and produce matte, smelting slag, flue gas, etc. After cooling and crushing, the smelting slag is ground and classified to achieve the degree of separation of useful mineral particles into individual particles, and slag concentrate is selected and slag tailings are produced. The flue gas is removed by a waste heat boiler, dust settling chamber, electrostatic precipitator and other dust removal processes and then enters the acid production system, which then produces smelting acid production tail gas.

[0066] (2) Microwave roasting. Copper smelting slag tailings after mineral processing.

[0067] name Cu / % Fe / % S / % <![CDATA[SiO2 / %]]> <![CDATA[Al2O 3 / %]]> Sb / % Bi / % CaO / % MgO / % As / % Pb / % Zn / % <![CDATA[Fe3O4 / %]]> tailings 0.19 37.96 0.2 35.21 3.27 0.014 0.0061 2.14 0.48 0.12 0.036 0.56 19.82 The tailings and sodium bicarbonate are mixed evenly at a ratio of 4:1.4. The feed speed is adjusted, and the tailings are continuously fed into the microwave cavity of the continuous microwave dynamic roasting system. The microwave and rotation are turned on at the same time as the feed, so that the tailings are heated as they move forward with the rotating shaft. The temperature is controlled at 500℃, the microwave frequency at 2200MHz, the average heating rate at 65℃ / min, and the roasting time at 22min by adjusting the power of the magnetron. Roasted slag is produced continuously.

[0068] (3) CO2 capture from sulfuric acid production tail gas. The sulfuric acid production tail gas first passes through a desulfurization combined tower 1 for desulfurization, where sulfur is removed by sequential adsorption in an adsorption bed composed of hydrogen peroxide solution adsorbent. Then, it is pressurized by a blower and directly enters a denitrification combined tower, where most of the nitrogen is removed by sequential adsorption in an adsorption bed composed of sodium thiosulfate solution adsorbent, directly obtaining carbon dioxide-rich gas for microwave carbon separation. The adsorbent after adsorption saturation is regenerated by vacuum pumping, and the regenerated nitrogen-rich gas is stored in a liquid nitrogen storage tank for use in the production system.

[0069] (4) Leaching. The roasted residue is transported to the leaching tank, the pure water valve is opened, and the corresponding pure water is added at a liquid-to-solid ratio of 15:1. The steam valve is opened to heat the water to 45°C, and the mixture is stirred for 55 minutes. The leachate and leaching residue are obtained by filtration. The composition of the leaching residue is shown in the table below.

[0070] Sample Name Cu / % Fe / % <![CDATA[SiO2%]]> <![CDATA[Al2O3 / %]]> Pb / % Zn / % Na / % K / % Leaching residue 0.15 49.13 4.71 0.40 0.55 0.19 44.86 0.01 (5) Plasma reduction. The leaching residue is dried and ground to obtain leaching residue powder. The leaching residue powder is smelted in a plasma furnace. A hydrogen-nitrogen mixed gas is ionized into plasma through a plasma nozzle under the action of high-frequency voltage and electric arc and ejected from the plasma nozzle. The leaching residue powder is injected into the plasma flame area and melted by the high-temperature plasma flame. Under nitrogen protection at 900°C, it is reduced with hydrogen plasma to produce high-purity iron.

[0071] (6) One-step microwave carbonization: The leachate is introduced into a one-step microwave carbonization reactor at a reaction temperature of 85°C. Stirring and microwave catalysis are performed at a microwave power of 650W and a frequency of 2.2GHz. Smelting acid production tail gas is injected to capture CO2 gas (40%) until the solution pH drops to 10.8. Microwave carbonization is then stopped, and solid-liquid separation is achieved.

[0072] (7) Two-step microwave carbonization: The first-step carbonization liquid is introduced into the two-step microwave carbonization reactor. The reaction temperature is 80°C. Stirring and microwave catalysis are used. The microwave power is 650W and the frequency is 2.2GHz. Smelting acid tail gas is injected to capture CO2 gas (40%). Sodium chloride (0.2% of precipitated silica) is added. The second microwave carbonization is carried out until the pH value of the solution drops to 9. The reaction is continued for 30 minutes. Microwave carbonization is stopped. Solid and liquid are separated. The solid is washed in the washing tank.

[0073] (8) Drying. The washing residue is dried by a continuous belt dryer with controlled frequency and automatic temperature control mode. The drying temperature is 90℃ and the thickness of the material is controlled at 10mm. After 30 minutes of drying, powdered product white carbon black (SiO2·nH2O) is continuously produced. Its composition is shown in the table below.

[0074] name Cu / % Fe / % <![CDATA[SiO2 / %]]> Ca / % As / % Na / % K / % Pb / % Zn / % Al / % Cd / % precipitate 0.0039 0.037 99.40 <0.0010 0.0051 <0.0010 <0.0010 0.0092 0.2 0.34 <0.0010 The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recovering and extracting silica from smelting slag, characterized in that, Includes the following steps: The tailings of copper smelting slag after mineral processing are mixed evenly with sodium bicarbonate and then microwave roasted to obtain roasted slag containing sodium silicate, sodium zincate and sodium leadate. The roasted residue is mixed with water for leaching treatment, and then solid-liquid separation is performed to obtain leachate and leaching residue; Carbon dioxide is introduced into the leachate for one-step microwave carbonization treatment until the solution pH drops to 10.5~11.0, and solid-liquid separation is performed to obtain one-step carbonized liquid and one-step microwave carbonization residue. Sodium chloride was added to the first-step carbonization liquid and carbon dioxide was introduced for a second-step microwave carbonization treatment until the solution pH dropped to 8.8-9.

2. After solid-liquid separation, a second-step carbonization liquid and a second-step microwave carbonization residue were obtained. The residue is obtained by washing and drying the residue after two-step microwave carbonization.

2. The method as described in claim 1, characterized in that, During microwave roasting, the temperature is 400~500℃, the microwave frequency is 1800~2200MHz, the heating rate is 55~65℃ / min, and the roasting time is 18~22min.

3. The method as described in claim 1, characterized in that, During the leaching process, the liquid-to-solid ratio is 10~15:1, the temperature is 35~45℃, and the treatment time is 45~55min.

4. The method as described in claim 1, characterized in that, The leaching residue is dried and ground to obtain leaching residue powder, which is then smelted into high-purity iron. Preferably, the leaching residue powder is smelted in a plasma furnace, where a hydrogen-nitrogen mixed gas is ionized into plasma through a plasma nozzle under the action of high-frequency voltage and electric arc and ejected from the plasma nozzle.

5. The method as described in claim 1, characterized in that, The carbon dioxide used in the one-step and two-step microwave carbon separation processes comes from the flue gas generated in the smelting process; preferably, the flue gas passes through an acid production system to generate smelting acid production tail gas, which is then desulfurized, denitrified, and enriched with carbon dioxide to obtain carbon dioxide for microwave carbon separation.

6. The method as described in claim 1, characterized in that, In the one-step microwave carbonization process, the temperature is 75~85℃, the microwave power is 550~650W, and the microwave frequency is 2.0~2.2GHz; Alternatively, in the two-step microwave carbonization process, the temperature is 75~85℃, the microwave power is 550~650W, and the microwave frequency is 2.0~2.2GHz.

7. The method as described in claim 1, characterized in that, During the two-step microwave carbonization process, after the solution pH drops to the set value, the reaction continues for 25-35 minutes.

8. A system for recovering and extracting silica from smelting slag, characterized in that, To implement the method of claim 1, the method comprises: Microwave roasting equipment is used for microwave roasting of materials made by mixing tailings and sodium bicarbonate. The leaching tank is configured to be connected to a water source and is used to leach out the roasting residue produced by the microwave roasting device. A one-step microwave carbonization reactor is used for one-step microwave carbonization treatment of the leachate from the leaching tank. A two-step microwave carbonization reactor is used to perform two-step microwave carbonization on the one-step carbonized liquid from the two-step microwave carbonization process.

9. The system as claimed in claim 8, characterized in that, It also includes a CO2 capture device for smelting acid production tail gas, which is used to generate smelting acid production tail gas by passing the flue gas generated in the smelting process through the acid production system, desulfurizing and denitrifying the smelting acid production tail gas, enriching carbon dioxide, and thus obtaining carbon dioxide for microwave carbon separation.

10. The system as claimed in claim 8, characterized in that, It also includes an iron smelting apparatus for smelting high-purity iron from leaching residue powder obtained by drying and grinding leaching residue; preferably, the iron smelting apparatus is a plasma furnace.

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