Method for separating ferrosilicon component in steel slag

Abstract

The invention relates to the technical field of comprehensive utilization of steel slag, in particular to a method for separating ferrosilicon components in steel slag, which comprises the following steps: placing the steel slag and ore dissolving liquid in a reactor with an in-situ high shearing function, and adjusting the pH value of the reaction liquid through an ammonia distillation process, so that calcium silicate and calcium ferrite in the steel slag react to generate silica gel and ferrite; calcium ions in the steel slag are extracted into the solution, and a calcium extraction solution is obtained; separating the calcium extraction liquid according to the solid density to obtain a high-iron turbid liquid with high density and a high-silicon turbid liquid with low density; and respectively filtering the high-iron turbid liquid and the high-silicon turbid liquid, transferring the obtained filtrate into a carbon dioxide trapping system, regenerating the filtrate into ore dissolving liquid for reuse, and sufficiently washing the obtained filter cake to respectively obtain high-iron steel slag and high-silicon steel slag. The method for separating the silicon iron component in the steel slag has the beneficial effects that the calcium extraction rate is remarkably increased, the steel slag component is optimized, resource recycling is achieved, waste is reduced, and sustainable development of the iron and steel industry is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of steel slag, and particularly to a method for separating silicon-iron components in steel slag. Background Art

[0002] In the process of steel production, steel slag, as an inevitable by-product in the steelmaking process, has a huge output, accounting for about 15% to 20% of the steel output. These wastes not only occupy precious land resources but also pose serious environmental problems such as dust pollution and water body (including rivers and groundwater) pollution. Therefore, exploring and realizing the effective resource utilization of steel slag is not only crucial for environmental protection but also an urgent need for realizing the circular economy of resources.

[0003] Traditionally, steel slag has been widely used in fields such as foundation backfilling, road construction, cement production, and phosphate fertilizer manufacturing. However, this extensive utilization method not only has a low added value but also greatly restricts its traditional resource utilization ways with the increasingly strict national environmental protection regulations. Therefore, developing low-cost and high-efficiency cascade resource utilization technologies for steel slag has become an urgent technical problem to be solved.

[0004] An important direction for the resource utilization of steel slag is to increase its iron content and obtain high-iron ore by removing impurities. Currently, domestic steel enterprises generally use magnetic separation technology to preliminarily process steel slag and recover the iron blocks and high-iron parts in it. Some manufacturers further crush and perform secondary magnetic separation on the roughly selected steel slag. Even so, the treated steel slag still contains more than 10% iron, and in some cases, it is even as high as more than 25%. In addition, steel slag is also rich in calcium (mainly in the form of CaO, with a content of up to 35% to 50%), silicon (the content of SiO2 is about 10% to 15%), and various elements such as phosphorus, magnesium, aluminum, and manganese. The presence of these elements affects the further increase of iron content.

[0005] In order to obtain iron ore that meets the requirements of steelmaking, the key lies in effectively removing calcium and silicon elements in steel slag. As a commonly used calcium extraction solution, ammonium chloride has been widely used in the extraction of calcium elements in steel slag, especially the extraction of free calcium oxide can be achieved at room temperature. However, for the calcium silicate component in steel slag, heating treatment is required to extract its calcium element to reduce free ammonia and lower the pH value of the solution, thereby promoting the decomposition of the calcium silicate phase. However, a large amount of silica gel components will be generated during this process. These silica gels are easy to wrap on the surface of steel slag particles or block the pores, not only reducing the extraction efficiency of calcium but also increasing the mixing degree of each component of steel slag due to the bonding effect of silica gel, making the separation of silicon-iron components more difficult.

[0006] In view of this, the present invention is specifically proposed. Summary of the Invention

[0007] The object of the present invention is to provide a method for separating silicon and iron components in steel slag, which can effectively inhibit the gelation of silica gel, enable more silica gel in the pores of steel slag to diffuse into the solution, thereby increasing the extraction rate of calcium in steel slag, reducing the ratio of calcium and silicon in steel slag, and improving the grade of iron ore.

[0008] The present invention provides a method for separating silicon and iron components in steel slag, comprising the following steps:

[0009] S1. Place the steel slag and the ore-dissolving solution in a reactor with an in-situ high-shear function, and adjust the pH value of the reaction solution through an ammonia distillation process, so that the calcium silicate and calcium ferrite phases in the steel slag react to form silica gel and ferrite, and extract the calcium ions in the steel slag into the solution to obtain a calcium-extracted solution;

[0010] S2. Use a gravity separation device to separate the calcium-extracted solution according to the solid density to obtain a high-iron suspension with a high density and a high-silicon suspension with a low density;

[0011] S3. Filter the high-iron suspension and the high-silicon suspension respectively. The obtained filtrate is transferred to a carbon dioxide capture system and regenerated for reuse as the ore-dissolving solution. After the obtained filter cakes are fully washed, high-iron steel slag and high-silicon steel slag are obtained respectively.

[0012] In the method for separating silicon and iron components in the steel slag of the present invention, the steel slag is mainly composed of minerals such as tricalcium silicate, dicalcium silicate, dicalcium ferrite, and free calcium oxide, and also contains certain amounts of useful components such as metallic iron, magnesium oxide, and manganese oxide. By using a reactor with an in-situ high-shear function, strong shear force can be provided, which is helpful for the full mixing and reaction of the steel slag and the ore-dissolving solution. During the reaction process, first, the calcium ions of the free calcium oxide in the steel slag are extracted into the solution. In the initial stage of the reaction, the escape of ammonia may make the solution alkaline; as the reaction progresses, ammonia is gradually distilled out, and at the same time, the acidic components in the ore-dissolving solution react with the alkaline components in the steel slag to neutralize, and the pH value of the solution gradually decreases to an appropriate range. Under the appropriate acidic reaction conditions, the calcium silicate phase (such as tricalcium silicate, dicalcium silicate) reacts with the components in the ore-dissolving solution to form silica gel, and the calcium ferrite phase also reacts with the ore-dissolving solution to form ferrite. At this time, the reactor with an in-situ high-shear function can effectively prevent the generated silica gel from adhering to the surface of the steel slag and growing continuously to finally wrap the steel slag particles, affecting the calcium extraction rate. Further adding a polyhydroxy non-ionic surfactant can inhibit the gelation of silica gel, enable more silica gel in the pores of the steel slag to diffuse to the outside of the steel slag, which can not only improve the calcium extraction efficiency, but also reduce the adhesion between particles, improve the separation efficiency of subsequent processes, and increase the iron content of the iron ore.

[0013] Preferably, a surfactant is added to the ore-dissolving solution, and the surfactant includes any one or two of polyglycol polyhydroxy nonionic surfactants and fatty alcohol polyoxyethylene ethers composed of polyethylene glycol groups.

[0014] The reason for choosing any one or two of polyglycol polyhydroxy nonionic surfactants and fatty alcohol polyoxyethylene ethers as the surfactant added to the ore-dissolving solution of the present invention is that these two surfactants can help calcium silicate and calcium ferrite in the steel slag to contact and react more fully with the ore-dissolving solution by reducing the surface tension of the solution, thereby generating silica gel and ferrite, and effectively extracting calcium ions into the solution; in addition, in the solid-liquid separation stage, the surfactant also helps to improve the properties of the solid-liquid interface, making the high-iron suspension and high-silica suspension clearer during the separation process and improving the separation efficiency; finally, in the filtration and washing stages, the surfactant can reduce the friction between the filter cake and the filter medium, reduce the filtration resistance, and increase the filtration speed. At the same time, during the washing process, the surfactant helps to wash out impurities and residual solution in the filter cake more effectively, improving the washing effect.

[0015] Preferably, the polyglycol polyhydroxy nonionic surfactant of the present invention specifically includes any one or more of polyethylene glycol 300, polyethylene glycol 400, polyethylene glycol 600, and polyethylene glycol 1000.

[0016] Preferably, the addition amount of the surfactant is 0.01%-1% of the mass of the ore-dissolving solution, and preferably 0.1-0.6%.

[0017] Preferably, the reactor with in-situ high-shear function includes a kettle-type reactor with a built-in high-speed emulsifier, a reaction kettle with one or more built-in high-speed emulsifiers and stirring function, and a reaction kettle with an external high-shear function device and stirring function. Among them, the external high-shear function devices include colloid mills, spin coaters, and emulsifying pumps, etc. By combining the reaction kettle with the high-shear device, the generated silica gel can be fully dispersed in the solution.

[0018] In addition, to further improve the extraction and dispersion effects, the reaction kettle is also equipped with a heating unit, such as a heating jacket. In order to achieve the function of ammonia evaporation, the reaction kettle is also equipped with a steam outlet, a condensation heat exchanger, and an ammonia absorption device, etc.

[0019] Preferably, the ore-dissolving solution is an ammonium chloride solution, and the concentration of the ammonium chloride solution is 80-200 g / L;

[0020] The particle size of the steel slag is 100-500 mesh, and preferably 200-400 mesh.

[0021] Preferably, in this technical solution, the mass-volume ratio of the steel slag to the ore-dissolving solution is 1 kg:(4 - 15) L.

[0022] Preferably, in this technical solution, the pH value of the reaction solution is adjusted to 5 - 10 in the ammonia distillation process. Among them, the first reaction stage is the pH decrease stage, and the controlled time is 1 - 6 h. The second reaction stage is the pH balance stage, and the controlled time is 1 - 4 h.

[0023] In the initial stage of the reaction (the first reaction stage), calcium ions of free calcium oxide in the steel slag are extracted into the solution. The escape of ammonia may make the solution alkaline. As the reaction proceeds, ammonia is gradually distilled out. At the same time, the acidic components in the ore-dissolving solution react with the alkaline components in the steel slag, causing the pH value of the solution to gradually decrease to an appropriate range. When the pH decreases to 6 - 7, the pH value is maintained in balance by controlling the ammonia distillation plastic. At this time, calcium silicate phases (such as tricalcium silicate and dicalcium silicate) react with the components in the ore-dissolving solution to form silica gel, and the calcium ferrite phase reacts with the ore-dissolving solution to form ferrite.

[0024] Preferably, in this technical solution, any one of gravity separation equipment such as a shaking table, a spiral chute, a jig, and a centrifugal concentrator can be used to separate the calcium-extracted solution according to the solid density.

[0025] Preferably, the high-iron steel slag is dried to obtain iron ore. The iron content of the iron ore is 45% - 50%, the calcium content is 14% - 20%, and the silicon content is 10% - 15%. It can be seen that the method of the present invention can greatly reduce the proportions of calcium and silicon in the steel slag and improve the grade of the iron ore.

[0026] The method for separating silicon and iron components in the steel slag of the present invention has at least the following beneficial effects:

[0027] In the present invention, steel slag and ore-dissolving solution are placed in a reactor with in-situ high-shear function, and the pH value of the reaction solution is adjusted by the ammonia distillation process. This not only promotes the chemical reaction of calcium silicate and calcium ferrite phases in the steel slag to generate silica gel and ferrite, but also effectively extracts calcium ions in the steel slag into the solution. Among them, the action of high shear force not only accelerates the process of chemical reaction, but also further reduces the size of steel slag particles through physical fragmentation, enabling more calcium ions to be released and extracted, thus significantly increasing the calcium extraction rate. Research shows that the calcium extraction rate of the present invention can be increased to 80-90%. In addition, under the action of high shear force, the fragmentation of steel slag particles separates the originally tightly bound iron phase and silicon phase. At the same time, the addition of surfactant promotes the diffusion of silica gel from the surface of steel slag particles, further reducing the silicon content in the steel slag. After the calcium extraction solution after extracting calcium ions undergoes density separation and filtration, the filtrate can be transferred to a carbon dioxide capture system (CCUS) for regeneration treatment, converted into ore-dissolving solution and reused in the ore-dissolving process, realizing the recycling of resources. At the same time, the obtained high-iron steel slag and high-silicon steel slag can also be further utilized as valuable resources, such as building materials, cement admixtures or extracting other useful elements, thereby improving the economic benefits of the resource utilization of steel slag. In the process of steel slag treatment in the present invention, in addition to the necessary ore-dissolving reaction, physical separation methods (such as density separation, filtration, etc.) are more adopted, avoiding the harmful wastes that may be generated in the traditional chemical treatment process. Therefore, the method for separating silicon and iron components in steel slag proposed by the present invention has multiple beneficial effects such as significantly increasing the calcium extraction rate, optimizing the composition of steel slag, realizing resource recycling, reducing waste generation and promoting the sustainable development of the iron and steel industry. Detailed Embodiments

[0028] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0029] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, 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.

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] The reactors used in the following Examples 1-4 are 10L stainless steel reaction kettles with an internal high-shear dispersion emulsifier, the rotation speed is adjustable from 100 to 3000 rpm / min, and the working head is of high-shear dispersion type. The reaction kettle is non-standard customized and is externally provided with an electric heating jacket.

[0032] The reactors used in Examples 5-8 are 10L stainless steel reaction kettles with an externally placed customized colloid mill, the rotation speed of the colloid mill is 2000 rpm / min, and the emulsification fineness is 50 μm.

[0033] The steel slag used in the embodiments and comparative examples of the present invention is all 350-mesh steel slag of Zhongtian Iron and Steel, in which the iron content (calculated as iron oxide) is 27.4%, the silicon content (calculated as silicon dioxide) is 10.9%, and the calcium content (calculated as calcium oxide) is 48%.

[0034] The iron content (calculated as iron oxide), silicon content (calculated as silicon dioxide), and calcium content (calculated as calcium oxide) described in the embodiments are all the results of measuring the content of substances by the XRF method and normalizing.

[0035] Example 1

[0036] S1. Weigh 1250 g of ammonium chloride and 30 g of polyethylene glycol 400 and dissolve them in 6.25 L of water to prepare a leaching solution. Weigh 1 kg of steel slag and add it to the reactor together with the leaching solution. Close the reactor, turn on the condensed water, and set the emulsifier to 800 rpm / min. When the temperature rises to 100 °C, adjust the emulsifier speed to 2000 rpm, and continue heating until the solution boils. As ammonia gas is distilled out, the pH value of the solution continuously decreases. Control the ammonia distillation rate. After 3 h, the pH of the solution decreases to 6-7. Maintain this pH value and continue ammonia distillation for 2 h to extract the calcium ions in the steel slag into the solution. The calcium extraction rate of the steel slag is 80%;

[0037] S2. After the reaction is completed and cooled to room temperature, pass the reaction solution into a wet jig. After screening, a high-iron suspension and a high-silicon suspension are obtained;

[0038] S3. Filter the high-iron suspension and the high-silicon suspension respectively. The obtained filtrates are combined and transferred to a carbon dioxide capture system and regenerated for reuse as a leaching solution. The obtained filter cakes are washed 3 times with 1.5 L of water to obtain high-iron steel slag and high-silicon steel slag respectively.

[0039] 451.6 g of iron ore was obtained by drying high-speed railway steel slag. Among them, the iron content (calculated as iron oxide) in the iron ore was 47.1%, the calcium content (calculated as calcium oxide) was 17%, and the silicon content (calculated as silicon dioxide) was 12.1%.

[0040] Example 2

[0041] S1. Weigh 1250 g of ammonium chloride and 30 g of polyethylene glycol 600, dissolve them in 7.5 L of water to prepare a mineral dissolution solution. Weigh 1 kg of steel slag and add it to the reactor together with the mineral dissolution solution. Seal the reactor, turn on the condensate water, and set the emulsifier to 800 rpm / min. When the temperature rises to 100 °C, adjust the emulsifier speed to 3000 rpm, and continue heating until the solution boils. As ammonia gas is distilled out, the pH value of the solution continuously decreases. Control the ammonia distillation rate. After 4 h, the pH of the solution decreases to 6 - 7. Maintain this pH value and continue ammonia distillation for 1 h to extract the calcium ions in the steel slag into the solution. The calcium extraction rate of the steel slag is 81%;

[0042] S2. After the reaction ends, cool it to room temperature, and pass the reaction solution into a wet jig. After screening, a high-iron suspension and a high-silicon suspension are obtained;

[0043] S3. Filter the high-iron suspension and the high-silicon suspension separately. The obtained filtrates are combined and transferred to a carbon dioxide capture system for regeneration and reuse as the mineral dissolution solution. The obtained filter cakes are washed 3 times with 1.5 L of water to obtain high-iron steel slag and high-silicon steel slag respectively.

[0044] 438.5 g of iron ore was obtained by drying high-iron steel slag. Among them, the iron content (calculated as iron oxide) in the iron ore was 48%, the calcium content (calculated as calcium oxide) was 16.4%, and the silicon content (calculated as silicon dioxide) was 11.2%.

[0045] Example 3

[0046] S1. Weigh 1250 g of ammonium chloride and 35 g of polyethylene glycol 1000, dissolve them in 8.75 L of water to prepare a mineral dissolution solution. Weigh 1 kg of steel slag and add it to the reactor together with the mineral dissolution solution. Seal the reactor, turn on the condensate water, and set the emulsifier to 800 rpm / min. When the temperature rises to 100 °C, adjust the emulsifier speed to 2000 rpm, and continue heating until the solution boils. As ammonia gas is distilled out, the pH value of the solution continuously decreases. Control the ammonia distillation rate. After 4 h, the pH of the solution decreases to 6 - 7. Maintain this pH value and continue ammonia distillation for 1 h to extract the calcium ions in the steel slag into the solution. The calcium extraction rate of the steel slag is 82%;

[0047] S2. After the reaction ends, cool it to room temperature, and pass the reaction solution into a wet jig. After screening, a high-iron suspension and a high-silicon suspension are obtained;

[0048] S3. Filter the high-iron suspension and high-silicon suspension separately. Combine the obtained filtrates and transfer them to a carbon dioxide capture system for regeneration into a leaching solution for reuse. Wash the obtained filter cakes 3 times with 1.5 L of water to obtain high-iron steel slag and high-silicon steel slag respectively.

[0049] Dry the high-iron steel slag to obtain 427.7 g of iron ore. Among them, the iron content (calculated as iron oxide) in the iron ore is 48.8%, the calcium content (calculated as calcium oxide) is 15.8%, and the silicon content (calculated as silicon dioxide) is 10.7%.

[0050] Example 4

[0051] S1. Weigh 1250 g of ammonium chloride and 40 g of polyethylene glycol 300 and dissolve them in 10 L of water to prepare a leaching solution. Weigh 1 kg of steel slag and add it to the reactor together with the leaching solution. Seal the reactor, turn on the condensed water, and set the emulsifier to 800 rpm / min. When the temperature rises to 100 °C, adjust the emulsifier speed to 3000 rpm, and continue heating until the solution boils. As ammonia gas is distilled out, the pH value of the solution continuously decreases. Control the ammonia distillation rate. After 4 h, the pH of the solution decreases to 6 - 7. Maintain this pH value and continue distilling ammonia for 1 h to extract the calcium ions in the steel slag into the solution. The calcium extraction rate of the steel slag is 81.5%;

[0052] S2. After the reaction, cool down to room temperature, and pass the reaction solution into a wet jig. After screening, obtain a high-iron suspension and a high-silicon suspension;

[0053] S3. Filter the high-iron suspension and high-silicon suspension separately. Combine the obtained filtrates and transfer them to a carbon dioxide capture system for regeneration into a leaching solution for reuse. Wash the obtained filter cakes 3 times with 1.5 L of water to obtain high-iron steel slag and high-silicon steel slag respectively.

[0054] Dry the high-iron steel slag to obtain 423.3 g of iron ore. Among them, the iron content (calculated as iron oxide) in the iron ore is 48.8%, the calcium content (calculated as calcium oxide) is 16.2%, and the silicon content (calculated as silicon dioxide) is 10.3%.

[0055] Example 5

[0056] S1. Weigh 1250 g of ammonium chloride and 45 g of polyethylene glycol 400, dissolve them in 12.5 L of water to prepare a ore-dissolving solution. Weigh 1 kg of steel slag, add it to the reactor together with the ore-dissolving solution, seal the reactor, turn on the condensed water, and stir at a speed of 300 rpm / min. When the temperature rises to 100 °C, turn on the external circulation pump, pass the reaction solution through a colloid mill at a speed of 5 L / min and then return it to the reaction kettle, adjust the speed to 1500 rpm, continue heating until the solution boils. As ammonia gas is distilled out, the pH value of the solution continuously decreases. Control the ammonia distillation rate. After 4 h, the pH of the solution decreases to 6 - 7. Maintain this pH value and continue ammonia distillation for 1 h to extract calcium ions in the steel slag into the solution. The calcium extraction rate of the steel slag is 80.8%;

[0057] S2. After the reaction ends and cools down to room temperature, pass the reaction solution into a centrifugal ore separator. After screening, obtain a high-iron suspension and a high-silicon suspension;

[0058] S3. Filter the high-iron suspension and the high-silicon suspension separately. Combine the obtained filtrates and transfer them to a carbon dioxide capture system for regeneration and reuse as the ore-dissolving solution. Wash the obtained filter cakes 3 times with 1.5 L of water respectively to obtain high-iron steel slag and high-silicon steel slag.

[0059] Dry the high-iron steel slag to obtain 425.3 g of iron ore. Among them, the iron content (calculated as iron oxide) in the iron ore is 48.6%, the calcium content (calculated as calcium oxide) is 16.7%, and the silicon content (calculated as silicon dioxide) is 10%.

[0060] Example 6

[0061] S1. Weigh 1100 g of ammonium chloride and 35 g of polyethylene glycol 400, dissolve them in 8.75 L of water to prepare a ore-dissolving solution. Weigh 1 kg of steel slag, add it to the reactor together with the ore-dissolving solution, seal the reactor, turn on the condensed water, and stir at a speed of 300 rpm / min. When the temperature rises to 100 °C, turn on the external circulation pump, pass the reaction solution through a colloid mill at a speed of 4 L / min and then return it to the reaction kettle, adjust the speed to 1500 rpm, continue heating until the solution boils. As ammonia gas is distilled out, the pH value of the solution continuously decreases. Control the ammonia distillation rate. After 3 h, the pH of the solution decreases to 7. Maintain this pH value and continue ammonia distillation for 2 h to extract calcium ions in the steel slag into the solution. The calcium extraction rate of the steel slag is 78.1%;

[0062] S2. After the reaction ends and cools down to room temperature, pass the reaction solution into a centrifugal ore separator. After screening, obtain a high-iron suspension and a high-silicon suspension;

[0063] S3. Filter the high-iron suspension and high-silica suspension separately. The obtained filtrates are combined and transferred to a carbon dioxide capture system for regeneration into a ore-dissolving solution for reuse. The obtained filter cakes are washed 3 times with 1.5 L of water to obtain high-iron steel slag and high-silica steel slag respectively.

[0064] Dry the high-iron steel slag to obtain 474 g of iron ore. Among them, the iron content (calculated as iron oxide) in the iron ore is 47.2%, the calcium content (calculated as calcium oxide) is 18.4%, and the silicon content (calculated as silicon dioxide) is 10.8%.

[0065] Example 7

[0066] S1. Weigh 1370 g of ammonium chloride and 35 g of polyethylene glycol 400 and dissolve them in 8.75 L of water to prepare an ore-dissolving solution. Weigh 1 kg of steel slag and add it to the reactor together with the ore-dissolving solution. Seal the reactor, turn on the condensate water, and stir at a speed of 300 rpm / min. When the temperature rises to 100 °C, turn on the external circulation pump, pass the reaction solution through a colloid mill at a speed of 4 L / min and then return it to the reaction kettle. Adjust the speed to 1500 rpm, continue heating until the solution boils. As ammonia gas is distilled out, the pH value of the solution continuously decreases. Control the ammonia distillation rate. After 3 h, the pH of the solution decreases to 6. Keep this pH value and continue distilling ammonia for 2 h to extract the calcium ions in the steel slag into the solution. The calcium extraction rate of the steel slag is 82%;

[0067] S2. After the reaction, cool it to room temperature. Pass the reaction solution into a centrifugal ore separator. After screening, obtain a high-iron suspension and a high-silica suspension;

[0068] S3. Filter the high-iron suspension and high-silica suspension separately. The obtained filtrates are combined and transferred to a carbon dioxide capture system for regeneration into a ore-dissolving solution for reuse. The obtained filter cakes are washed 3 times with 1.5 L of water to obtain high-iron steel slag and high-silica steel slag respectively.

[0069] Dry the high-iron steel slag to obtain 441.8 g of iron ore. Among them, the iron content (calculated as iron oxide) in the iron ore is 49.6%, the calcium content (calculated as calcium oxide) is 16.1%, and the silicon content (calculated as silicon dioxide) is 9.4%.

[0070] Example 8

[0071] S1. Weigh 1500 g of ammonium chloride and 40 g of polyethylene glycol 400, dissolve them in 8.75 L of water to prepare a mineral digestion solution. Weigh 1 kg of steel slag and add it to the reactor together with the mineral digestion solution. Seal the reactor, turn on the condensed water, and stir at a speed of 300 rpm / min. When the temperature rises to 100 °C, turn on the external circulation pump, pass the reaction solution through a colloid mill at a speed of 4 L / min and then return it to the reaction kettle. Adjust the speed to 1500 rpm, continue heating until the solution boils. As ammonia gas is distilled out, the pH value of the solution continuously decreases. Control the ammonia distillation rate. After 3 h, the pH of the solution drops to 6. Maintain this pH value and continue ammonia distillation for 2 h to extract calcium ions in the steel slag into the solution. The calcium extraction rate of the steel slag is 81%;

[0072] S2. After the reaction, cool down to room temperature, pass the reaction solution into a centrifugal concentrator, and through screening, obtain a high-iron suspension and a high-silicon suspension;

[0073] S3. Filter the high-iron suspension and the high-silicon suspension separately. Combine the obtained filtrates and transfer them to a carbon dioxide capture system for regeneration and reuse as a mineral digestion solution. Wash the obtained filter cakes 3 times with 1.5 L of water respectively to obtain high-iron steel slag and high-silicon steel slag.

[0074] Dry the high-iron steel slag to obtain 425.5 g of iron ore. Among them, the iron content (calculated as iron oxide) in the iron ore is 49.6%, the calcium content (calculated as calcium oxide) is 16%, and the silicon content (calculated as silicon dioxide) is 9.2%.

[0075] Control Example 1

[0076] This control example is basically the same as Example 3, except that: no surfactant is added to the mineral digestion solution in this control example.

[0077] The calcium extraction rate of the steel slag in this control example is 70.1%;

[0078] Dry the high-iron steel slag obtained in this control example to obtain 528.1 g of iron ore. Among them, the iron content (calculated as iron oxide) in the iron ore is 41.2%, the calcium content (calculated as calcium oxide) is 22%, and the silicon content (calculated as silicon dioxide) is 16.1%.

[0079] Control Example 2

[0080] This control example is basically the same as Example 3, except that: the reactor used in this control example is a 10 L stainless steel reaction kettle equipped with a disk turbine stirrer inside.

[0081] Specifically, step S1 includes the following steps:

[0082] Weigh 1250 g of ammonium chloride and 35 g of polyethylene glycol 1000, dissolve them in 8.75 L of water to prepare a mineral digestion solution. Weigh 1 kg of steel slag, add it to the reactor together with the mineral digestion solution, seal the reactor, turn on the condensed water, and stir at a speed of 300 rpm / min. Heat the reactor until the solution boils. As ammonia gas is distilled out, the pH value of the solution continuously decreases. Control the ammonia distillation rate. After h, the pH of the solution decreases to 6 - 7. Maintain this pH value and continue ammonia distillation for 1 h to extract calcium ions in the steel slag into the solution. The calcium extraction rate of the steel slag is 67.8%.

[0083] After the reaction, cool it to room temperature. Pass the reaction solution into a centrifugal ore separator, screen it, and filter to obtain high - iron steel slag and high - silicon steel slag;

[0084] In this control example, 580.2 g of iron ore is obtained by drying the high - iron steel slag. Among them, the iron content (calculated as iron oxide) in the iron ore is 40.8%, the calcium content (calculated as calcium oxide) is 23.4%, and the silicon content (calculated as silicon dioxide) is 15.6%.

[0085] Table 1 shows the steel slag treatment results of the above - mentioned examples and control examples.

[0086] Table 1 Steel Slag Treatment Results

[0087]

[0088]

[0089] As can be seen from Table 1, during the process of calcium extraction from steel slag, timely dispersing the generated silica gel into the solution significantly promotes the improvement of the calcium extraction rate. After re - sorting, the iron content in the high - iron steel slag obtained by the present invention is significantly higher than that of the control example, further confirming that the present invention achieves the separation effect of the generated silica gel component and steel slag at the particle scale during the calcium extraction process.

[0090] Finally, it should be noted that: the above - mentioned embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for separating silicon-iron components from steel slag, characterized in that, It includes the following steps: S1. Place the steel slag and the ore-dissolving solution in a reactor with in-situ high-shear function, and adjust the pH value of the reaction solution through the ammonia distillation process, so that the calcium silicate and calcium ferrite phases in the steel slag react to generate silica gel and ferrite, and extract the calcium ions in the steel slag into the solution to obtain a calcium-extracted solution; S2. Use a gravity separation device to separate the calcium-extracted solution according to the solid density to obtain a high-iron suspension with a high density and a high-silica suspension with a low density; S3. Filter the high-iron suspension and the high-silica suspension respectively. The obtained filtrate is transferred to a carbon dioxide capture system and regenerated into an ore-dissolving solution for reuse. After the obtained filter cake is fully washed, high-iron steel slag and high-silica steel slag are obtained respectively.

2. The method for separating ferrosilicon components from steel slag according to claim 1, characterized in that, A surfactant is added to the ore-dissolving solution, and the surfactant includes any one or two of a polyethylene glycol polyhydroxy nonionic surfactant and a fatty alcohol polyoxyethylene ether composed of polyethylene glycol groups.

3. The method for separating ferrosilicon components from steel slag according to claim 2, characterized in that, The polyethylene glycol polyhydroxy nonionic surfactant includes any one or more of polyethylene glycol 300, polyethylene glycol 400, polyethylene glycol 600, and polyethylene glycol 1000.

4. The method for separating silicon-iron components in steel slag according to claim 2, characterized in that, The addition amount of the surfactant is 0.01%-1% of the mass of the ore-dissolving solution.

5. The method for separating silicon-iron components in steel slag according to claim 1, wherein The reactor with in-situ high-shear function includes a kettle-type reactor with a built-in high-speed emulsifier, a reaction kettle with one or more built-in high-speed emulsifiers and stirring function, and a reaction kettle with an external high-shear function device and stirring function.

6. The method for separating ferrosilicon components from steel slag according to claim 1, wherein The ore-dissolving solution is an ammonium chloride solution, and the concentration of the ammonium chloride solution is 80-200 g / L; The particle size of the steel slag is 100-500 mesh.

7. The method for separating ferrosilicon components in steel slag according to claim 1, characterized in that, The mass-volume ratio of the steel slag to the ore-dissolving solution is 1 kg:(4-15) L.

8. The method for separating silicon-iron components in steel slag according to claim 1, wherein The ammonia distillation process adjusts the pH value of the reaction solution to 5-10. Among them, the first reaction stage is the pH drop stage, and the control time is 1-6 h. The second reaction stage is the pH balance stage, and the control time is 1-4 h.

9. According to the method for separating silicon and iron components in steel slag according to claim 1, the gravity separation device includes any one of a shaking table, a spiral chute, a jig, and a centrifugal concentrator.

10. The method for separating ferrosilicon components in steel slag according to claim 1, characterized in that, The high-iron steel slag is dried to obtain iron ore. The iron content of the iron ore is 45%-50%, the calcium content is 14%-20%, and the silicon content is 10%-15%.

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