A method and device for coupling steel slag step-by-step resource utilization and CCUS

Abstract

The present application relates to the technical field of steel slag comprehensive utilization and carbon neutralization, and particularly relates to a method and device for steel slag stepwise resource utilization coupled with CCUS, which breaks the connection of the internal mineral phase of the steel slag into multiple independent particles by means of multistage calcium extraction and alkali dissolution of silicon, then separates the high-iron particles with greater density and stronger magnetism from the low-iron particles through a gravity separation device and a magnetic separation device, and finally obtains iron ore with smelting value. In addition, the extracted calcium solution can also be used to absorb industrial tail gas to achieve permanent mineralization of CO2. By optimizing the reaction sequence of the calcium extraction liquid in the first-stage and second-stage mineral dissolution, the two-stage parallel mineral dissolution liquid streams are combined into a series stream, thereby simplifying the process flow.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of comprehensive utilization of steel slag and carbon neutralization, in particular to a method and device for steel slag gradient resource utilization coupled with CCUS. BACKGROUND

[0002] Steel slag is an industrial waste residue produced in the steelmaking process, with a production of about 15%-20% of the steel production, and the production is very large. These steel slags not only occupy land resources, but also cause dust pollution, and after rain, they will also pollute rivers and groundwater. If it can be reasonably utilized, not only the pollution problem can be solved, but also the steel slag can be turned into treasure. A part of the traditional domestic steel slag is used for foundation backfill, road paving, cement raw material, steel slag phosphate fertilizer, etc. With the increasingly stringent environmental protection requirements, NY_T 525-2021 "Organic Fertilizer" and GB175-2023 "General Portland Cement" have already prohibited the use of steel slag. This greatly limits the extensive use of steel slag resources, so it is urgent to develop a low-cost steel slag gradient resource utilization process.

[0003] Removing impurities from steel slag to obtain high-iron-content ore is an important direction of steel slag. Steel plants will use magnetic separation methods to recycle or remove the iron blocks and high-iron-content parts in the steel slag from the sintering section. Some manufacturers will also crush the steel slag after rough separation and perform secondary magnetic separation. After physical recovery and treatment, the steel slag still contains more than 10% iron content. According to the steel slag production process, the iron content of some steel slag can reach more than 25%. Steel slag contains a large amount of calcium and silicon, with CaO content of 35%-50% and SiO2 content of 10%-15%. In addition, steel slag also contains elements such as phosphorus, magnesium, silicon, aluminum, and manganese. Although it is feasible to extract ferrite from steel slag or remove calcium and silicon components from steel slag, the cost is obviously higher than directly using iron ore. Therefore, the steel slag ironmaking route has not been able to realize application. In order to obtain iron ore that meets the steelmaking process, more removal of calcium and silicon elements from steel slag is the key to improving the iron content.

[0004] The calcium component in the steel slag is usually in the form of free calcium oxide, calcium silicate, and other complex oxides formed by other elements. Part of the calcium elements can be extracted as raw materials for CCUS through some processes. CN115820946B extracts more than 80% of the calcium elements in the steel slag into the solution through a two-stage ammonium chloride extraction process, and combines them with CO2 in the plant tail gas to produce calcium carbonate, achieving the effect of mineralization and carbon sequestration. CN111558606B converts part of the calcium elements in the steel slag into calcium bicarbonate by adding a pressurized CO2 process and an additive, and separates the calcium bicarbonate from the steel slag. Then, the pH value of the calcium bicarbonate solution is adjusted to convert the calcium bicarbonate into calcium carbonate products. However, the above processes do not further utilize the steel slag after calcium extraction. The main reason is that although the iron content is enriched after calcium extraction, the mineral phase of the steel slag is still complete, and the silicon-calcium phase and the phosphorus-calcium phase are still combined with high-iron phase and cannot be separated. CN116622920B adopts a method of first extracting calcium with an ammonium chloride solution to break the mineral phase of the steel slag, and then oxidizing the divalent iron in the steel slag to magnetite to improve the magnetism of the iron-containing particles in the steel slag. Finally, particles with different magnetic strengths are screened out by adjusting the magnetic field strength. However, this method still cannot solve the problem of adhesion of most calcium-extracted steel slag iron oxide to other mineral phases, and can only select 15-27% of iron ore with high iron content.

[0005] Therefore, whether the connection between high-iron-content particles and low-iron-content particles can be further broken after calcium extraction from the steel slag is the key to improving the yield of iron ore.

[0006] In view of this, the present application is proposed. SUMMARY

[0007] The purpose of the present application is to provide a method and device for steel slag stepwise resource utilization coupled with CCUS, which can solve the above technical problems.

[0008] The present application provides a method for steel slag stepwise resource utilization coupled with CCUS. The method breaks the connection of the mineral phase in the steel slag by multi-stage calcium extraction and alkali dissolution of silicon to form a plurality of independent particles, and then separates high-iron particles with greater density and stronger magnetism from low-iron particles through a gravity separation device and a magnetic separator, and finally obtains iron ore with smelting value. In addition, the extracted calcium solution can also be used to absorb industrial tail gas to achieve permanent mineralization of CO2.

[0009] The method comprises the following steps:

[0010] S1, primary ore dissolution: reacting the primary ore dissolution solution obtained from the S3 secondary ore dissolution step with the steel slag to extract the high-activity calcium component in the steel slag into the ore dissolution solution, remove the metal impurity ions in the ore dissolution solution, and obtain a primary ore dissolution slag;

[0011] S2, mineralization reaction: reacting calcium ions in the ore-dissolving solution with CO2 in the industrial tail gas to obtain calcium carbonate and a circulating calcium-extracting solution;

[0012] S3, secondary ore-dissolving: reacting the circulating calcium-extracting solution obtained in the S2 mineralization reaction step with the primary ore-dissolving residue obtained in the S1 primary ore-dissolving reaction step to extract low-activity calcium components in the primary ore-dissolving residue into the primary ore-dissolving solution, remove metal impurities in the primary ore-dissolving solution, and obtain a secondary ore-dissolving residue;

[0013] The entire process can be summarized as follows: the product of S3 (the primary ore-dissolving solution) provides raw materials for S1, the circulating calcium-extracting solution obtained by reacting the product of S1 (the ore-dissolving solution) in S2 provides raw materials for S3, and S3 produces new primary ore-dissolving solution for the next cycle, thus realizing the full utilization of calcium components in the steel slag and the gradual removal of metal impurities in the ore-dissolving solution, while producing calcium carbonate from CO2 in the industrial tail gas;

[0014] S4, tertiary ore-dissolving: mixing and stirring an alkali solution with the secondary ore-dissolving residue and heating to remove silica and silicon gel in the secondary ore-dissolving residue and obtain a tertiary ore-dissolving residue;

[0015] S5, silica preparation: carbonating the silicate solution obtained in S4 to obtain silica and regenerate the alkali solution;

[0016] S6, quaternary ore-dissolving: removing calcium carbonate components in the tertiary ore-dissolving residue and obtaining a quaternary ore-dissolving residue;

[0017] S7, gravity separation and magnetic separation: removing low-density and low-magnetic low-iron components and classifying the obtained iron ore into high-grade iron ore and low-grade iron ore.

[0018] Preferably, the step S1 specifically comprises:

[0019] mixing and stirring the steel slag with the ore-dissolving solution and heating to maintain a pH value of 8-11 and extract high-activity calcium components in the steel slag into the ore-dissolving solution;

[0020] absorbing ammonia gas released during the reaction and obtaining ammonia water;

[0021] performing solid-liquid separation on the primary ore-dissolving residue and the ore-dissolving solution;

[0022] The step S2 specifically comprises:

[0023] mineralizing the ore-dissolving solution, the recovered ammonia water, and the industrial tail gas to obtain calcium carbonate and a circulating calcium-extracting solution;

[0024] performing solid-liquid separation on the calcium carbonate and the circulating calcium-extracting solution in the mineralization reaction solution;

[0025] The calcium carbonate is dried to obtain a calcium carbonate product.

[0026] The step S3 specifically comprises:

[0027] The calcium extraction liquid is mixed with the first-stage slag and heated with stirring, the pH value is kept at 6-9, and the calcium component in the first-stage slag is extracted into the primary slag solution;

[0028] The ammonia gas and water vapor evaporated in the secondary slag dissolution reaction are cooled to obtain ammonia water;

[0029] The secondary slag is subjected to solid-liquid separation with the primary slag solution;

[0030] The slag solution is adjusted to a pH value of 7-10 by the ammonia water, so that the impurity ions in the solution are converted into hydroxides and removed.

[0031] Preferably, the step S4 specifically comprises:

[0032] The alkali solution is mixed with the secondary slag and heated with stirring, and the silica gel and silicon dioxide component in the secondary slag is extracted into the silicate solution to obtain the tertiary slag;

[0033] The tertiary slag is subjected to solid-liquid separation with the silicate solution.

[0034] Preferably, the step S5 specifically comprises: carbonation of the silicate solution to obtain a silica gel and carbonate solution;

[0035] The silica gel and carbonate solution are subjected to solid-liquid separation;

[0036] The silica gel is dried and dehydrated to obtain silicon dioxide;

[0037] Calcium oxide or calcium hydroxide is added to the carbonate solution to regenerate the alkali solution and obtain calcium carbonate;

[0038] The calcium carbonate and the alkali solution are subjected to solid-liquid separation to obtain the calcium carbonate and the alkali solution;

[0039] The calcium carbonate is dried to obtain a calcium carbonate product.

[0040] Preferably, the step S6 specifically comprises:

[0041] The tertiary slag is loaded into a reactor, and CO2 is added to the reactor to convert the calcium carbonate in the tertiary slag into calcium bicarbonate dissolved in the solution;

[0042] H2O2 is additionally added to the tertiary slag dissolution reaction liquid to convert the divalent iron into magnetite to increase the magnetic properties of the iron ore phase;

[0043] The quaternary slag is subjected to solid-liquid separation with the calcium bicarbonate solution;

[0044] heating the calcium bicarbonate solution to decompose the calcium bicarbonate to obtain calcium carbonate and recover the released CO2;

[0045] solid-liquid separation of the calcium carbonate from the liquid phase;

[0046] drying the calcium carbonate and obtaining the calcium carbonate product.

[0047] Preferably, the step S7 specifically comprises:

[0048] adding the fourth-stage ore-dissolving slag into a gravity separation device to separate according to specific gravity to obtain high-density iron ore and low-density tailing slag;

[0049] passing the iron ore through a magnetic separator to separate the iron ore according to magnetism to obtain high-quality iron ore with an iron content of 50% or more and low-quality iron ore with an iron content of 40%-50%.

[0050] The application also provides a device for steel slag stepwise resource utilization coupled with CCUS, comprising:

[0051] a first-stage ore-dissolving unit connected to a liquid phase outlet from a second-stage ore-dissolving unit and obtaining a first-stage ore-dissolving slag and an ore-dissolving liquid;

[0052] a mineralization reaction unit connected to a liquid phase outlet of the first-stage ore-dissolving unit and an ammonia water recovery tank, used for mineralization reaction of CO2 in the plant tail gas and calcium ions in the first-stage mineralization liquid to convert into calcium carbonate products, and obtaining a circulating calcium extraction liquid;

[0053] a second-stage ore-dissolving unit connected to a solid phase outlet of the first-stage ore-dissolving unit and a liquid phase outlet of the mineralization unit, used for extracting most of the remaining calcium elements in the first-stage ore-dissolving slag into the primary ore-dissolving liquid, and obtaining a second-stage ore-dissolving slag;

[0054] a third-stage ore-dissolving unit connected to a solid phase outlet of the second-stage ore-dissolving unit, used for dissolving the generated orthosilicic acid in the ore-dissolving process, and obtaining a third-stage ore-dissolving slag;

[0055] a silicon dioxide unit connected to a liquid phase outlet of the third-stage ore-dissolving unit, used for carbonation of the dissolved silicate to obtain silica gel products, and simultaneously regenerating the obtained carbonate solution into a strong alkali solution, and obtaining calcium carbonate products;

[0056] a fourth-stage ore-dissolving unit connected to a solid phase outlet of the third-stage ore-dissolving unit, used for converting the calcium carbonate in the third-stage ore-dissolving slag into calcium bicarbonate to be removed from the solid phase and dissolved in the solution, and obtaining a fourth-stage ore-dissolving slag, and additionally converting the extracted calcium bicarbonate into calcium carbonate products;

[0057] a gravity separation and magnetic separation unit connected to a solid phase outlet of the fourth-stage ore-dissolving unit, used for separating out iron ore products with large density and high magnetism.

[0058] Preferably, the primary ore-dissolving unit comprises:

[0059] A primary ore-dissolving slurry tank, the liquid inlet of which is connected with the liquid outlet of the secondary ore-dissolving unit, and the steel slag is added into the primary ore-dissolving slurry tank through the solid feeding port, which is used to disperse the steel slag in the primary ore-dissolving liquid to form a uniform suspension;

[0060] A primary ore-dissolving reactor, which is connected with the bottom of the primary ore-dissolving slurry tank, and the reactor is provided with a steam heat exchange coil, which is used to remove impurities from the primary ore-dissolving liquid while extracting the high-activity calcium components in the steel slag;

[0061] An ammonia gas absorption tower, the bottom of which is connected with the gas outlet of the primary ore-dissolving reactor, which is used to absorb most of the ammonia gas released during the ore-dissolving reaction, and the tail gas is combined with the CO2 tail gas to enter the mineralization reaction system;

[0062] A primary ore-dissolving slag concentration tank, the top of which is connected with the bottom of the primary ore-dissolving reactor, which is used to increase the solid content of the primary ore-dissolving slag in the liquid phase;

[0063] A primary ore-dissolving slag plate-and-frame filter, which is connected with the bottom of the concentration tank, which is used to separate and wash the primary ore-dissolving slag from the ore-dissolving liquid, and the liquid outlet of which is combined with the supernatant of the primary ore-dissolving slag concentration tank to enter the mineralization unit;

[0064] A heat exchanger, which is connected with the liquid outlet of the primary ore-dissolving slag plate-and-frame filter, and the shell is connected with circulating cooling water, which is used to cool the ore-dissolving liquid;

[0065] The mineralization reaction unit comprises:

[0066] A mineralization reactor, which is connected with the liquid outlet of the primary ore-dissolving unit, and is connected with the ammonia recovery tank of the primary ore-dissolving unit and the secondary ore-dissolving unit, and the industrial tail gas is introduced into the reactor through the distributor at the bottom, which is used to react the calcium ions in the ore-dissolving liquid, ammonia water and CO2 in the industrial tail gas to obtain a calcium carbonate suspension;

[0067] A mineralization reaction liquid concentration tank, the top of which is connected with the liquid outlet of the mineralization reactor, which is used to increase the solid content of the calcium carbonate in the liquid phase;

[0068] A mineralization reaction liquid plate-and-frame filter, the inlet of which is connected with the bottom of the calcium carbonate concentration tank, and the liquid outlet of which is combined with the supernatant outlet of the calcium carbonate concentration tank to enter the secondary ore-dissolving unit, which is used to separate and wash the calcium carbonate from the circulating calcium extraction liquid, and the calcium carbonate is dried to obtain a calcium carbonate product;

[0069] The secondary ore-dissolving unit comprises:

[0070] The second-stage ore-dissolving reactor is connected with the bottom of the second-stage ore-dissolving pulp-making kettle, and a steam heat-exchange coil is arranged in the reactor, which is used for extracting calcium components in most of calcium silicate in the first-stage ore-dissolving slag and obtaining second-stage ore-dissolving slag;

[0071] The second-stage ore-dissolving reactor is connected with the bottom of the second-stage ore-dissolving pulp-making kettle, and a steam heat-exchange coil is arranged in the reactor, which is used for extracting calcium components in most of calcium silicate in the first-stage ore-dissolving slag and obtaining second-stage ore-dissolving slag;

[0072] The condenser is connected with the gas-phase outlet at the top of the second-stage ore-dissolving reactor, which is used for condensing water vapor evaporated in the reaction process and simultaneously absorbing ammonia gas escaped;

[0073] The second-stage ore-dissolving slag concentration kettle is connected with the bottom of the second-stage ore-dissolving reactor, which is used for increasing the solid content of the second-stage ore-dissolving slag in the liquid phase;

[0074] The second-stage ore-dissolving slag plate-and-frame filter is connected with the bottom of the concentration kettle, which is used for separating and washing the first-stage ore-dissolving slag from the ore-dissolving liquid;

[0075] The third-stage ore-dissolving unit comprises:

[0076] The third-stage ore-dissolving pulp-making kettle is used for adding the second-stage ore-dissolving slag into the third-stage ore-dissolving pulp-making kettle through a solid feeding port, and dispersing the second-stage ore-dissolving slag in the circulating calcium-extracting liquid to form a uniform suspension liquid in the reaction kettle;

[0077] The alkali-dissociation reactor is connected with the bottom of the third-stage ore-dissolving pulp-making kettle, and a water vapor heat-exchange coil is arranged in the alkali-dissociation reactor, which is used for extracting most of orthosilicic acid in the second-stage ore-dissolving slag;

[0078] The third-stage ore-dissolving slag concentration kettle is connected with the bottom of the alkali-dissociation reactor, which is used for increasing the solid content of the third-stage ore-dissolving slag in the liquid phase;

[0079] The third-stage ore-dissolving slag plate-and-frame filter is connected with the bottom outlet of the third-stage ore-dissolving slag concentration kettle, which is used for separating and washing the third-stage ore-dissolving slag and the alkali-dissociation liquid, and obtaining the third-stage ore-dissolving slag and the alkali-dissociation liquid.

[0080] Preferably, the silicon dioxide unit comprises:

[0081] The carbonation reactor is connected with the liquid-phase outlet of the third-stage ore-dissolving unit, CO2 is introduced into the carbonation reactor through a gas distributor at the bottom of the carbonation reactor, which is used for converting the silicate in the alkali-dissociation liquid and the remaining unreacted alkali into silica gel and a carbonate solution;

[0082] The centrifuge is connected with the outlet of the carbonation reactor, which is used for separating and washing the silica gel and the carbonate solution, and obtaining the silicon dioxide product after drying the silica gel;

[0083] A lye regeneration reactor connected to the liquid outlet of the centrifuge, calcium hydroxide is added through the solid inlet of the lye regeneration reactor, which is used to convert most of the carbonate into calcium carbonate precipitate and corresponding lye;

[0084] A circulating lye concentration kettle connected to the bottom of the lye regeneration reactor, which is used to increase the solid content of calcium carbonate in the liquid phase;

[0085] A circulating lye plate and frame filter connected to the bottom of the lye regeneration concentration kettle, which is used for the liquid-solid separation and washing of calcium carbonate and circulating lye, and obtains calcium carbonate and lye solution, and the calcium carbonate is dried to obtain calcium carbonate product;

[0086] The fourth stage of ore dissolution unit includes:

[0087] A CO2 compressor for pressurizing CO2 gas;

[0088] A pressure ore dissolution reactor, the third stage of ore dissolution slag is added into the reactor through the solid inlet of the pressure ore dissolution reactor, hydrogen peroxide solution is introduced through the liquid inlet at the upper end of the reactor, and CO2 is introduced through the gas inlet at the upper end of the reactor, which is used to convert calcium carbonate in the third stage of ore dissolution slag into calcium bicarbonate dissolved in the solution, and simultaneously partially oxidize ferrous iron in the third stage of ore dissolution slag into magnetite;

[0089] A filter press connected to the bottom outlet of the pressure ore dissolution reactor, equipped with high-pressure gas introduction and recovery pipeline, which is used for the solid-liquid separation of the fourth stage of ore dissolution slag and calcium bicarbonate solution, and obtains the fourth stage of ore dissolution slag and calcium bicarbonate solution;

[0090] A calcium bicarbonate decomposition reactor connected to the liquid outlet of the filter press, equipped with a CO2 recovery pipeline, and the calcium bicarbonate decomposition reactor is internally provided with a water vapor heat exchange coil, saturated lime water is added through the liquid inlet at the upper end of the calcium bicarbonate decomposition reactor, which is used for the decomposition of calcium bicarbonate in the solution and the recovery of CO2;

[0091] A decomposition liquid plate and frame filter connected to the bottom outlet of the calcium bicarbonate decomposition reactor, which is used for the solid-liquid separation of calcium carbonate and decomposition liquid, and obtains calcium carbonate and decomposition liquid, and the calcium carbonate is dried to obtain calcium carbonate product.

[0092] Preferably, the gravity separation and magnetic separation unit includes:

[0093] A gravity separation device connected to the solid phase outlet of the filter press through a conveyor belt, which is used for the separation of heavy iron ore and light tailing slag, and obtains an iron ore suspension liquid;

[0094] A magnetic separator connected to the iron ore suspension liquid outlet of the gravity separation device, which is used for the separation of high-grade iron ore and low-grade iron ore, and obtains the suspension liquid of high-grade iron ore and low-grade iron ore;

[0095] Iron ore thickening kettle, the top is connected with the liquid phase outlet of the magnetic separator, which is used to improve the solid content of low-grade iron ore in the liquid phase;

[0096] Iron ore plate and frame filter press, connected with the bottom outlet of the iron ore thickening kettle, which is used to separate iron ore and dispersion liquid, and finally obtain low-grade iron ore.

[0097] The gravity separation equipment can be one of a shaking table, a spiral chute, a jigging machine and a centrifugal concentrator.

[0098] Beneficial effects:

[0099] The present application solves the problems of low iron ore yield and low iron content in the ore in the process of steel slag resource utilization by matching the chemical chain mineralization process of calcium extraction with ammonium chloride, the strong alkali solution silicon extraction process, the CO2 dissolution calcium carbonate process and the gravity separation and magnetic separation process. In addition, according to the different characteristics of the activity of calcium components in steel slag, the circulating calcium extraction liquid with the strongest hydrolysis ability is first used in the secondary ore dissolution reaction to ensure the calcium extraction rate of the secondary ore dissolution slag, and then the primary ore dissolution liquid with reduced calcium extraction ability is used to treat the steel slag with the highest activity. By optimizing the reaction sequence of the calcium extraction liquid in the primary and secondary ore dissolution, the two-stage parallel ore dissolution liquid streams are combined into a series stream, simplifying the process flow. And the whole process does not produce waste other than steel slag components, which is environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0100] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0101] Figure 1 The block flow chart of the method for extracting high-quality iron ore coupled with CCUS provided by the present application from steel slag as raw material;

[0102] Figure 2 The structural diagram of the primary ore dissolution unit in the device for extracting high-quality iron ore coupled with CCUS provided by the present application from steel slag as raw material;

[0103] Figure 3 The structural diagram of the mineralization reaction unit in the device for extracting high-quality iron ore coupled with CCUS provided by the present application from steel slag as raw material;

[0104] Figure 4 The structural diagram of the secondary ore dissolution unit in the device for extracting high-quality iron ore coupled with CCUS provided by the present application from steel slag as raw material.

[0105] Figure 5 A structure diagram of a three-stage ore dissolving unit in the device for extracting high-quality iron ore from steel slag as raw material and coupling CCUS is provided in the present application.

[0106] Figure 6 A structure diagram of a four-stage ore dissolving unit in the device for extracting high-quality iron ore from steel slag as raw material and coupling CCUS is provided in the present application.

[0107] Figure 7 A structure diagram of a heavy separation and magnetic separation unit in the device for extracting high-quality iron ore from steel slag as raw material and coupling CCUS is provided in the present application.

[0108] Figure 8 A structure diagram of a heavy separation and magnetic separation unit in the device for extracting high-quality iron ore from steel slag as raw material and coupling CCUS is provided in the present application.

[0109] BRIEF DESCRIPTION OF DRAWINGS 100 - first-stage ore dissolving unit; 200 - mineralization unit; 300 - second-stage ore dissolving unit; 400 - three-stage ore dissolving unit; 500 - silicon dioxide unit; 600 - four-stage ore dissolving unit; 700 - heavy separation and magnetic separation unit; R101 - first-stage ore dissolving reactor; T101 - ammonia gas absorption tower; V101 - first-stage ore dissolving pulp preparation kettle; V102 - first-stage ore dissolving slag concentration kettle; F101 - first-stage ore dissolving slag plate-frame filter; R201 - mineralization reactor; V202 - mineralization reaction liquid concentration kettle; F201 - mineralization reaction liquid plate-frame filter; R301 - second-stage ore dissolving reactor; R302 - primary ore dissolving liquid impurity removal reaction kettle; V301 - second-stage ore dissolving pulp preparation kettle; V302 - second-stage ore dissolving slag concentration kettle; E301 - condenser; F301 - second-stage ore dissolving slag plate-frame filter; F302 - impurity removal reaction liquid plate-frame filter; R401 - three-stage ore dissolving reactor; V401 - three-stage ore dissolving pulp preparation kettle; V402 - three-stage ore dissolving slag concentration kettle; F401 - three-stage ore dissolving slag plate-frame filter; R501 - carbonation reactor; R502 - lye regeneration reactor; V501 - circulating lye concentration kettle; C501 - centrifuge; F501 - circulating lye plate-frame filter; R601 - pressure ore dissolving reaction kettle; R602 - calcium bicarbonate decomposition reaction kettle; V601 - decomposition liquid concentration kettle; F601 - filter press; F602 - decomposition liquid plate-frame filter; S701 - heavy separation equipment; S702 - magnetic separator; V701 - iron ore concentration kettle; F701 - iron ore plate-frame filter. DETAILED DESCRIPTION

[0110] The technical solutions of the present application will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of the present application.

[0111] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0112] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features referred to. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited. In addition, the terms "mounting", "connecting", "connecting" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0113] Figure 1 A block flowchart of a method for extracting high-quality iron ore coupled with CCUS using steel slag as raw material is provided for an embodiment of the present application. As shown in the figure, the method for extracting high-quality iron ore coupled with CCUS using steel slag as raw material provided by the present application comprises:

[0114] S1, primary ore dissolution: extracting high-activity calcium components in steel slag into ore dissolution liquid, while removing metal impurity ions in the ore dissolution liquid;

[0115] S2, mineralization reaction: reacting calcium ions in the ore dissolution liquid with CO2 in industrial tail gas to obtain calcium carbonate;

[0116] S3, secondary ore dissolution: extracting low-activity calcium components in the primary ore dissolution slag into primary ore dissolution liquid, and removing part of the metal impurity ions in the primary ore dissolution liquid;

[0117] S4, tertiary ore dissolution: removing silica gel and part of the silica in the secondary ore dissolution residue;

[0118] S5, silica preparation: carbonating the silicate solution obtained in S4 to obtain silica, and regenerating the lye;

[0119] S6, quaternary ore dissolution: removing the calcium carbonate component in the tertiary ore dissolution residue;

[0120] S7, gravity separation and magnetic separation: removing low-density and low-magnetic low-iron components, and grading the obtained iron ore into high-grade iron ore and low-grade iron ore.

[0121] Optionally, S1 primary ore dissolution obtains a primary ore dissolution residue, including:

[0122] Mixing and stirring the steel slag with the primary ore dissolution liquid in S3 and heating, keeping the pH value at 8-11, and extracting the high-activity calcium component in the steel slag into the ore dissolution liquid;

[0123] Absorbing the ammonia gas escaping in the reaction process and obtaining ammonia water;

[0124] Solid-liquid separation of the primary ore dissolution residue in the reaction liquid and the ore dissolution liquid;

[0125] Heat exchange of the ore dissolution liquid and the calcium extraction liquid in S2;

[0126] Optionally, S2 mineralization reaction obtains a calcium carbonate product, including:

[0127] Mineralization reaction of the ore dissolution liquid, recovered ammonia water, and industrial tail gas to obtain calcium carbonate and a calcium extraction liquid;

[0128] Solid-liquid separation of the calcium carbonate in the mineralization reaction liquid and the calcium extraction liquid;

[0129] Drying the calcium carbonate and obtaining a calcium carbonate product.

[0130] Optionally, S3 secondary ore dissolution, including:

[0131] Mixing and stirring the calcium extraction liquid and the primary ore dissolution residue and heating, keeping the pH value at 6-9, and extracting most of the calcium component in the primary ore dissolution residue into the primary ore dissolution liquid;

[0132] Cooling the ammonia gas and water vapor evaporated in the secondary ore dissolution reaction process to obtain ammonia water;

[0133] Solid-liquid separation of the secondary ore dissolution residue in the reaction liquid and the primary ore dissolution liquid;

[0134] Adjusting 20%-100% of the primary ore dissolution liquid to a pH value of 7-10, preferably 8-9, by ammonia water, so that the impurity ions in the solution are converted into hydroxides and removed;

[0135] The impurity-removing part of the primary ore-dissolving solution is subjected to solid-liquid separation to obtain a composite hydroxide and a primary impurity-removing ore-dissolving solution. The reaction solution is mixed with the primary ore-dissolving solution to be used in S1 primary ore-dissolving.

[0136] Optionally, S4 tertiary ore-dissolving includes:

[0137] The alkali solution is mixed with the secondary ore-dissolving residue and heated with stirring, and most of the silica gel and part of the silicon dioxide component in the secondary ore-dissolving residue is extracted into the silicate solution to obtain a tertiary ore-dissolving residue;

[0138] The tertiary ore-dissolving residue is subjected to solid-liquid separation with the silicate solution;

[0139] Optionally, S5 silicon dioxide preparation includes:

[0140] The silicate solution is carbonated to obtain silica gel and a carbonate solution;

[0141] The silica gel and the carbonate solution are subjected to solid-liquid separation;

[0142] The silica gel is dried and dehydrated to obtain silicon dioxide;

[0143] Calcium oxide or calcium hydroxide is added to the carbonate solution to regenerate the alkali solution and obtain calcium carbonate;

[0144] The calcium carbonate and the alkali solution are subjected to solid-liquid separation to obtain calcium carbonate and an alkali solution;

[0145] The calcium carbonate is dried to obtain a calcium carbonate product.

[0146] Optionally, S6 quaternary ore-dissolving includes:

[0147] The tertiary ore-dissolving residue is loaded into a reactor, and CO2 is added to the reactor. Under certain temperature and pressure, the calcium carbonate in the tertiary ore-dissolving residue is converted into calcium bicarbonate dissolved in the solution;

[0148] H2O2 is additionally added to the tertiary ore-dissolving reaction solution to convert part of the divalent iron into magnetite to increase the magnetic property of the iron ore phase;

[0149] The quaternary ore-dissolving residue is subjected to solid-liquid separation with the calcium bicarbonate solution;

[0150] The calcium bicarbonate solution is heated to decompose the calcium bicarbonate to obtain calcium carbonate and recover the released CO2;

[0151] The calcium carbonate is subjected to solid-liquid separation with the liquid phase;

[0152] The calcium carbonate is dried to obtain a calcium carbonate product.

[0153] Optionally, S7 reselection and magnetic separation includes:

[0154] The quaternary ore-dissolving slag is added into a gravity separation device to separate according to specific gravity to obtain high-density iron ore and low-density tailing slag.

[0155] The iron ore is separated by a magnetic separator to obtain high-quality iron ore with iron content of 50% or more and low-quality iron ore with iron content of 40%-50%.

[0156] Referring to Figures 2-7 The device of the embodiment of the present application can be used in the method of the embodiment of the present application. Part of the method of the embodiment of the present application can be used to understand and explain the device of the embodiment of the present application, and part of the device of the embodiment of the present application can also be used to understand and explain the method of the embodiment of the present application. The device of the embodiment of the present application comprises:

[0157] The primary ore-dissolving unit is connected with the liquid phase outlet from the secondary ore-dissolving unit, and obtains primary ore-dissolving slag and ore-dissolving liquid.

[0158] The mineralization reaction unit is connected with the liquid phase outlet of the primary ore-dissolving unit and the ammonia water recovery tank, and is used for mineralization reaction of CO2 in the plant tail gas and calcium ions in the primary mineralization liquid to convert into calcium carbonate product, and obtains circulating calcium extraction liquid.

[0159] The secondary ore-dissolving unit is connected with the solid phase outlet of the primary ore-dissolving unit and the liquid phase outlet of the mineralization unit, and is used for extracting most of the remaining calcium elements in the primary ore-dissolving slag into the primary ore-dissolving liquid, and obtains secondary ore-dissolving slag.

[0160] The tertiary ore-dissolving unit is connected with the solid phase outlet of the secondary ore-dissolving unit, and is used for dissolving the generated orthosilicic acid in the ore-dissolving process, and obtains tertiary ore-dissolving slag.

[0161] The silicon dioxide unit is connected with the liquid phase outlet of the tertiary ore-dissolving unit, and is used for carbonizing the dissolved silicate to obtain silica gel product. At the same time, the obtained carbonate solution is regenerated into strong alkali solution, and calcium carbonate product is obtained.

[0162] The quaternary ore-dissolving unit is connected with the solid phase outlet of the tertiary ore-dissolving unit, and is used for converting calcium carbonate in the tertiary ore-dissolving slag into calcium bicarbonate to be dissolved in the solution and removed from the solid phase, and obtains quaternary ore-dissolving slag. In addition, the extracted calcium bicarbonate is converted into calcium carbonate product.

[0163] The gravity separation and magnetic separation unit is connected with the solid phase outlet of the quaternary ore-dissolving unit, and is used for separating out iron ore product with large density and high magnetism.

[0164] Optionally, the primary ore-dissolving unit comprises:

[0165] A primary ore-dissolving slurry-making tank, the liquid phase inlet of which is connected with the liquid phase outlet of the secondary ore-dissolving unit, and the steel slag is added into the primary ore-dissolving slurry-making tank through the solid feeding port. It is used to disperse the steel slag in the primary ore-dissolving liquid to form a uniform suspension.

[0166] A primary ore-dissolving reactor, which is connected with the bottom of the primary ore-dissolving slurry-making tank, and a steam heat exchange coil is arranged in the reactor. It is used to remove impurities from the primary ore-dissolving liquid and extract high-activity calcium components in the steel slag.

[0167] An ammonia gas absorption tower, the bottom of which is connected with the gas outlet of the primary ore-dissolving reactor, which is used to absorb most of the ammonia gas released in the ore-dissolving reaction process. The tail gas is combined with the CO2 tail gas to enter the mineralization reaction system.

[0168] A primary ore-dissolving slag concentration tank, the top of which is connected with the bottom of the primary ore-dissolving reactor, which is used to increase the solid content of the primary ore-dissolving slag in the liquid phase.

[0169] A primary ore-dissolving slag plate-and-frame filter, which is connected with the bottom of the concentration tank, which is used to separate and wash the primary ore-dissolving slag from the ore-dissolving liquid. The liquid phase outlet is combined with the supernatant of the primary ore-dissolving slag concentration tank and enters the mineralization unit.

[0170] A heat exchanger, which is connected with the liquid phase outlet of the plate-and-frame filter, and the shell is connected with circulating cooling water. It is used for cooling the ore-dissolving liquid.

[0171] Optionally, the mineralization reaction unit comprises:

[0172] A mineralization reactor, which is connected with the liquid phase outlet of the primary ore-dissolving unit, and is connected with the ammonia recovery tank of the primary ore-dissolving unit and the secondary ore-dissolving unit. The industrial tail gas is introduced into the reactor through the distributor at the bottom. It is used to react the calcium ions in the ore-dissolving liquid, ammonia water and CO2 in the industrial tail gas to obtain a calcium carbonate suspension.

[0173] A mineralization reaction liquid concentration tank, the top of which is connected with the liquid phase outlet of the mineralization reactor, which is used to increase the solid content of the calcium carbonate in the liquid phase.

[0174] A mineralization reaction liquid plate-and-frame filter, the inlet of which is connected with the bottom of the calcium carbonate concentration tank, and the liquid phase outlet is combined with the supernatant outlet of the calcium carbonate concentration tank and enters the secondary ore-dissolving unit. It is used to separate and wash the calcium carbonate from the circulating calcium extraction liquid. The calcium carbonate is dried to obtain a calcium carbonate product.

[0175] Optionally, the secondary ore-dissolving unit comprises:

[0176] A secondary ore-dissolving slurry-making tank, the primary ore-dissolving slag is added into the secondary ore-dissolving slurry-making tank through the solid feeding port, and the top of which is connected with the shell outlet of the heat exchanger. It is used to disperse the primary ore-dissolving slag in the circulating calcium extraction liquid to form a uniform suspension.

[0177] A secondary ore-dissolving reactor, which is connected to the bottom of the secondary ore-dissolving pulp-making kettle, and has a steam heat-exchange coil inside. It is used to extract calcium components from most of the calcium silicate in the primary ore-dissolving residue, and to obtain secondary ore-dissolving residue.

[0178] A condenser, which is connected to the gas-phase outlet at the top of the secondary ore-dissolving reactor. It is used to condense the water vapor evaporated during the reaction and simultaneously absorb the ammonia gas escaping.

[0179] A secondary ore-dissolving residue concentration kettle, which is connected to the bottom of the secondary ore-dissolving reactor at the top, and is used to increase the solid content of the secondary ore-dissolving residue in the liquid phase.

[0180] A secondary ore-dissolving residue plate-and-frame filter, which is connected to the bottom of the concentration kettle, and is used to separate and wash the primary ore-dissolving residue from the ore-dissolving liquid.

[0181] Optionally, the tertiary ore-dissolving unit comprises:

[0182] A tertiary ore-dissolving pulp-making kettle, which is connected to the liquid-phase outlet of the strong-alkali plate-and-frame filter, and has a solid-feeding port for adding the secondary ore-dissolving residue into the kettle. Inside the kettle, it is used to disperse the secondary ore-dissolving residue in the circulating calcium-extracting liquid to form a uniform suspension.

[0183] An alkaline hydrolysis reactor, which is connected to the bottom of the tertiary ore-dissolving pulp-making kettle. Inside the reactor, there is a water-steam heat-exchange coil. It is used to extract most of the orthosilicic acid from the secondary ore-dissolving residue.

[0184] A tertiary ore-dissolving residue concentration kettle, which is connected to the bottom of the alkaline hydrolysis reactor at the top, and is used to increase the solid content of the tertiary ore-dissolving residue in the liquid phase.

[0185] A tertiary ore-dissolving residue plate-and-frame filter, which is connected to the bottom outlet of the tertiary ore-dissolving residue concentration kettle. It is used to separate and wash the tertiary ore-dissolving residue and the alkaline hydrolysis liquid, and to obtain the tertiary ore-dissolving residue and the alkaline hydrolysis liquid.

[0186] Optionally, the silicon dioxide unit comprises:

[0187] A carbonation reactor, which is connected to the liquid-phase outlet of the tertiary ore-dissolving unit, and has a gas distributor at the bottom for introducing CO2 into the reactor. It is used to convert the silicates in the alkaline hydrolysis liquid and the remaining unreacted alkali into silica gel and a carbonate solution.

[0188] A centrifuge, which is connected to the outlet of the carbonation reactor. It is used to separate and wash the silica gel and the carbonate solution. After drying the silica gel, the silicon dioxide product is obtained.

[0189] An alkali-liquid regeneration reactor, which is connected to the liquid-phase outlet of the centrifuge. Calcium hydroxide is added into the reactor through the solid-feeding port. It is used to convert most of the carbonates into calcium carbonate precipitate and the corresponding alkali liquid.

[0190] A circulating lye concentration kettle, the top of which is connected with the bottom of a lye regeneration reactor. It is used to increase the solid content of calcium carbonate in the liquid phase.

[0191] A circulating lye plate-and-frame filter, which is connected with the bottom of the lye regeneration concentration kettle. It is used for the liquid-solid separation and washing of calcium carbonate and strong alkali solution, and obtains calcium carbonate and circulating lye, and the calcium carbonate is dried to obtain calcium carbonate product.

[0192] Optionally, the fourth-stage ore-dissolving unit comprises:

[0193] A CO2 compressor, which is used to pressurize CO2 gas.

[0194] A pressure ore-dissolving reaction kettle, which is connected with the liquid phase outlet of the calcium carbonate decomposition plate-and-frame filter. The third-stage ore-dissolving residue is added into the reaction kettle through the solid inlet of the pressure ore-dissolving reaction kettle, the hydrogen peroxide solution is introduced through the liquid phase inlet at the upper end of the reaction kettle, and the CO2 is introduced through the gas inlet at the upper end of the reaction kettle. It is used to convert the calcium carbonate in the third-stage ore-dissolving residue into calcium bicarbonate dissolved in the solution, and simultaneously partially oxidize the ferrous iron in the third-stage ore-dissolving residue into magnetite.

[0195] A filter press, which is connected with the bottom outlet of the pressure ore-dissolving reaction kettle. It is provided with a high-pressure gas introduction and recovery pipeline. It is used for the solid-liquid separation of the fourth-stage ore-dissolving residue and the calcium bicarbonate solution, and obtains the fourth-stage ore-dissolving residue and the calcium bicarbonate solution.

[0196] A calcium bicarbonate decomposition reaction kettle, which is connected with the liquid phase outlet of the filter press and is provided with a CO2 recovery pipeline. The calcium bicarbonate decomposition reaction kettle is provided with a water vapor heat exchange coil. The saturated lime water is added through the liquid inlet at the upper end of the calcium bicarbonate decomposition reaction kettle. It is used for the decomposition of calcium bicarbonate in the solution and the recovery of CO2.

[0197] A decomposition liquid plate-and-frame filter, which is connected with the bottom outlet of the calcium bicarbonate decomposition reaction kettle. It is used for the solid-liquid separation of calcium carbonate and decomposition liquid, and obtains calcium carbonate and decomposition liquid. The calcium carbonate is dried to obtain calcium carbonate product.

[0198] Optionally, the gravity separation and magnetic separation unit comprises:

[0199] The gravity separation equipment is one of a shaking table, a spiral chute, a jigging machine and a centrifugal concentrator, which is connected with the solid phase outlet of the filter press through a conveyor belt. It is used for the separation of heavy iron ore and light tailing residue, and obtains an iron ore suspension liquid.

[0200] A magnetic separator, which is connected with the iron ore suspension liquid outlet of the gravity separation equipment. It is used for the separation of high-grade iron ore and low-grade iron ore, and obtains the suspension liquid of high-grade iron ore and low-grade iron ore.

[0201] Iron ore thickening kettle, the top is connected with the liquid phase outlet of the magnetic separator, is used for improving the solid content of low-grade iron ore in the liquid phase.

[0202] Iron ore plate and frame filter, connected with the bottom outlet of the iron ore thickening kettle. It is used for separating iron ore and dispersion liquid, and finally obtaining low-grade iron ore.

[0203] The scheme and effect of the method and device of the present application are further illustrated below in combination with specific examples.

[0204] In some examples, as shown in Figure 2 The primary ore dissolving unit 100 is added to the primary ore dissolving pulp kettle V101 with steel slag 101, primary ore dissolving liquid 128 and part of the impurity removal primary ore dissolving liquid 132 to form dispersion liquid 102 which is added to the primary ore dissolving reactor R101 for primary ore dissolving reaction. The obtained reaction liquid 106 enters the primary ore dissolving slag thickening kettle V102 to thicken the solid concentration to 20%-30%, and then the thickened liquid 107 is sent to the primary ore dissolving slag plate and frame filter F101 for filtration and washing to obtain the primary ore dissolving slag filter cake 111 which is sent to the secondary ore dissolving unit 300. The filtrate 108 is combined with the supernatant 109 obtained from the primary ore dissolving slag thickening kettle V102 to form 110 which is sent to the mineralization unit 200. The ammonia gas 103 generated in the primary ore dissolving reaction is absorbed by the ammonia gas absorption tower T101 to obtain ammonia water 104. The waste gas 105 is discharged to the waste gas treatment system.

[0205] In some embodiments of the present application, as shown in Figure 2 The steps S1 and S2 can adopt the form of heat exchanger or heat pump to exchange heat between the high-temperature ore dissolving liquid obtained in S1 and the low-temperature calcium recycling liquid obtained in S2, and then the obtained liquid is cooled to the appropriate temperature required for mineralization reaction through the heat exchanger with condensed water. Through heat integration technology, the energy consumption in the ore dissolving process can be reduced.

[0206] In some embodiments of the present application, as shown in Figure 3 The mineralization unit 200 mixes the mixed liquid 123 of ammonia water recovered from the primary ore dissolving unit 100 and ammonia water recovered from the secondary ore dissolving unit 300 with the ore dissolving liquid 110 obtained from the primary ore dissolving unit 100 and then inputs the mixed liquid into the mineralization reactor R201, and at the same time, the industrial tail gas 113 is input into the gas distributor at the bottom of R201 to perform mineralization reaction with the liquid phase. The mineralization reaction liquid 115 is transported to the mineralization reaction liquid thickening kettle V201 to thicken the solid concentration to 20%-30%, and then the thickened liquid 117 is sent to the mineralization reaction liquid plate and frame filter F201 for filtration and washing to obtain the calcium carbonate filter cake 120 which is dried and crushed to obtain the finished product of calcium carbonate. The filtrate 118 is combined with the supernatant 116 obtained from the mineralization reaction liquid thickening kettle V201 to form the calcium recycling liquid 119 which is sent to the secondary ore dissolving unit 300.

[0207] In some embodiments of the present application, asFigure 4 As shown, the secondary ore dissolving unit 300 disperses the primary ore dissolving slag 111 from the primary ore dissolving unit 100 and the circulating calcium extraction liquid 119 from the mineralization reaction unit 200 in the secondary ore dissolving slurry preparation vessel V301 to form a dispersion liquid 121, which is then added to the secondary ore dissolving reactor R201 for primary ore dissolving reaction. The resulting reaction solution 123 is fed into a secondary slag concentration reactor V302 to concentrate the solids to 20%-30%. The concentrated solution 125 is then sent to a secondary slag plate and frame filter press F301 for filtration and washing to obtain a secondary slag filter cake 127, which is then sent to the tertiary slag dissolving unit 400. The filtrate 126 is combined with the supernatant 124 obtained from the secondary slag concentration reactor V302, and 30% of the primary slag dissolving solution 129 is taken and sent to a primary slag dissolving solution impurity removal reactor R302. Simultaneously, ammonia water 130 is introduced to adjust the pH to 8-9, resulting in reaction solution 131. This is then filtered and washed by the impurity removal reaction solution plate and frame filter press F302 to obtain composite hydroxide 133. The resulting impurity-removed primary slag dissolving solution 132 is sent to the primary slag dissolving unit 100. The remaining primary slag dissolving solution 128 is sent to the primary slag dissolving unit 100. The mixture of steam and ammonia generated during the secondary ore-dissolving reaction is condensed by condenser E301 to obtain ammonia water 122, which is then combined with ammonia water 104 obtained from the primary ore-dissolving reaction to form recovered ammonia water 123, which is then transported to the mineralization reaction unit 200.

[0208] In some embodiments of the present invention, such as Figure 4 As shown, in step S3, all or part of the primary ore-dissolving solution is sent to the ammonia water purification process. Complete removal with ammonia water effectively ensures the removal of impurities from the ore-dissolving solution; however, this process requires adjusting the pH to 9-10, which will cause more ammonia gas to be distilled in step S1, increasing energy consumption for ammonia distillation and the load on the T101 ammonia absorption tower. Using only a portion of the primary ore-dissolving solution for purification reduces ammonia usage. Metal impurities accumulate and gradually increase in concentration during circulation in the primary ore-dissolving slag and primary ore-dissolving solution. Therefore, in the purification process of a portion of the primary ore-dissolving solution, adjusting the pH to 8-9 is sufficient to remove most of the metal impurities.

[0209] In some embodiments of the present invention, such as Figure 5 As shown, in the tertiary ore dissolving unit 400, the secondary ore dissolving slag from the secondary ore dissolving unit 300 is dispersed with regenerated alkali solution 154 and supplementary alkali solution 143 in the tertiary ore dissolving pulping tank V401 for pulping. The resulting dispersion 136 is added to the tertiary ore dissolving reactor R401 for tertiary ore dissolving reaction. The resulting reaction liquid 137 enters the tertiary ore dissolving slag concentration tank V402 to concentrate the solids to 20%-30%. The concentrated liquid 139 is sent to the tertiary ore dissolving slag plate and frame filter F401 for filtration and washing to obtain the tertiary ore dissolving slag filter cake 142, which is then sent to the quaternary ore dissolving unit 600. The filtrate 140 is combined with the supernatant 138 obtained from the tertiary ore dissolving slag concentration tank V402 to obtain the silicate solution 141.

[0210] In some embodiments of the present invention, such as Figure 6 As shown, in the silica unit 500, silicate solution 141 and CO2 gas 144 from the tertiary ore-dissolving unit 400 are simultaneously added to the carbonation reactor R501 for reaction to obtain carbonation reaction liquid 146. Unreacted gas 145 enters the tail gas treatment system. After solid-liquid separation and washing in centrifuge C501, silica gel 147 is obtained and sent to the drying unit to obtain silica product. The resulting carbonate solution 148 is added to the alkali regeneration reactor R502 to react with calcium hydroxide 149. The resulting reaction liquid 150 enters the circulating alkali concentration tank V501 to concentrate the solid concentration to 20%-30%. The concentrated liquid 152 is sent to the circulating alkali plate and frame filter F501 for filtration and washing to obtain calcium carbonate filter cake 155 for solid drying. The filtrate 153 and the supernatant 151 obtained from the circulating alkali concentration tank V501 are combined into 154 and sent to the tertiary ore-dissolving unit 400.

[0211] In some embodiments of the present invention, such as Figure 7 As shown, the fourth-stage ore-dissolving unit 600 adds the third-stage ore-dissolving slag 142, high-pressure CO2 gas 156, and hydrogen peroxide solution 167 from the third-stage ore-dissolving unit 400 to the pressure ore-dissolving reactor R601 for a fourth-stage ore-dissolving reaction. The resulting fourth-stage ore-dissolving reaction liquid 158 is sent to the filter press F601 for pressure filtration and washing. The resulting fourth-stage ore-dissolving slag 159 is sent to the gravity separation and magnetic separation unit 700. The resulting calcium bicarbonate solution 160 is sent to the calcium bicarbonate decomposition reactor R602 for heating and decomposition. The resulting calcium carbonate suspension 162 is sent to the decomposition liquid concentration reactor V601 to concentrate the calcium carbonate concentration to 20%-30%. The concentrated liquid 164 is then sent to the decomposition liquid plate and frame filter press F602 for filtration and washing to obtain calcium carbonate filter cake 167 for solid drying. The filtrate 165 and the supernatant 163 obtained from the decomposition liquid concentration reactor V601 are combined into 166 for wastewater treatment. The CO2 gas 161 released from the reaction in the calcium bicarbonate decomposition kettle R602 is combined with the CO2 released from the depressurization of the ore melting reactor R601 and the filter press F601 and sent to the tail gas treatment.

[0212] In some embodiments of the present invention, CO2 tail gas 157 can be mixed into industrial tail gas 113 in mineralization reaction unit 200 for absorption, thereby increasing the net CO2 emission reduction of the entire device.

[0213] In some embodiments of the present invention, CO2 tail gas 157 can be used in CO2 gas 144 used in the carbonation reaction in the silicon dioxide unit 500, thereby increasing the net CO2 emission reduction of the entire device.

[0214] In some embodiments of the present application, part of the CO2 tail gas 157 can be mixed into the high-pressure CO2 gas 156 in the silicon dioxide unit 500 after being pressurized by a compressor, and used for the fourth-stage ore-dissolving reaction. The exhaust gas is preferentially used for the carbonation reaction in the silicon dioxide unit 500, and the excess tail gas is mixed into the industrial tail gas 113 in the ore-dissolving reaction unit 200 for absorption. In this way, the high-concentration CO2 can be fully utilized, and the CO2 net emission of the entire device can be improved.

[0215] In some embodiments of the present application, as shown in Figure 7 The calcium bicarbonate decomposition solution 166 has less impurities and dissolves more CO2, and can be used to prepare a hydrogen peroxide solution 167 and returned to the pressure ore-dissolving reaction kettle R601 for recycling, thereby reducing the wastewater treatment amount, reducing CO2 emission, and improving the economic benefit of the entire device.

[0216] In some embodiments of the present application, as shown in Figure 8 The heavy separation and magnetic separation unit 700 adds the fourth-stage ore-dissolving slag from the fourth-stage ore-dissolving unit 600 and the dispersion liquid 177 into the heavy separation device S701 for separation. The obtained light tailings 169 are subjected to natural sedimentation, and the liquid is subjected to waste liquid treatment, and the solid is subjected to solid waste treatment. The obtained coarse iron ore dispersion liquid 170 is sent into the magnetic separator S702. The iron ore 171 with high magnetism is separated therefrom, washed, and dried to obtain high-grade iron ore. The remaining low-grade iron ore dispersion liquid 172 is sent into the iron ore thickening kettle V701, the solid concentration is thickened to 20%-30%, the thickened liquid 174 is sent into the iron ore plate and frame filter F701 for filtration and washing to obtain low-grade iron ore filter cake 178, the solid is dried to obtain low-grade iron ore, and the filtrate 175 is combined with the supernatant 173 obtained from the iron ore thickening kettle V701 to obtain 176 for wastewater treatment.

[0217] In some embodiments of the present application, as shown in Figure 8 The light tailings 169 are subjected to natural sedimentation, and the dispersion liquid is returned to the inlet of the heavy separation and magnetic separation unit 700 as part of the dispersion liquid 177, thereby reducing the wastewater treatment amount, reducing the consumption of additives, and improving the economic benefit of the entire device.

[0218] In some embodiments of the present application, as shown in Figure 8 The obtained wastewater 176 can be returned to the inlet of the heavy separation and magnetic separation unit 700 as part of the dispersion liquid 177, thereby reducing the wastewater treatment amount, reducing the consumption of additives, and improving the economic benefit of the entire device.

[0219] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; 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 application.

Claims

1. A method for the cascade resource utilization of steel slag coupled with CCUS, characterized in that, Includes the following steps: S1, Primary Dissolving: The primary dissolving solution obtained from the secondary dissolving step S3 is mixed with steel slag and stirred and heated, maintaining a pH of 8-11, to extract the highly active calcium component from the steel slag into the dissolving solution; the ammonia gas released during the reaction is absorbed to obtain ammonia water; at the same time, metal impurities in the dissolving solution are removed, and the primary dissolving slag is separated from the dissolving solution to obtain the primary dissolving slag; S2. Mineralization reaction: Calcium ions in the molten mineral solution react with CO2 in industrial tail gas to obtain calcium carbonate and a recycled calcium extraction solution. S3, Secondary Dissolution: The recycled calcium extraction solution obtained from the S2 mineralization reaction step is mixed with the primary dissolution slag obtained from the S1 primary dissolution reaction step and stirred and heated to maintain a pH of 6-9. The low-activity calcium component in the primary dissolution slag is extracted into the primary dissolution solution. The ammonia gas and water vapor distilled during the secondary dissolution reaction are cooled to obtain ammonia water. Metal impurities in the primary dissolution solution are removed. The secondary dissolution slag is separated from the primary dissolution solution to obtain secondary dissolution slag. The pH of the dissolution solution is adjusted to 7-10 using ammonia water to convert impurities in the solution into hydroxides for removal. S4. Tertiary dissolution: The alkaline solution is mixed with the secondary dissolution slag and stirred and heated to remove the silica from the secondary dissolution slag and obtain the tertiary dissolution slag. S5. Preparation of silicon dioxide: Carbonate the silicate solution obtained in step S4 to obtain silicon dioxide, while regenerating the alkali solution. S6, Quaternary dissolution: Remove the calcium carbonate component from the tertiary dissolution slag to obtain the quaternary dissolution slag; S7. Gravity separation and magnetic separation: Remove low-density, low-magnetic low-iron components and classify the resulting iron ore into high-grade iron ore and low-grade iron ore.

2. The method for cascaded resource utilization of steel slag coupled with CCUS according to claim 1, characterized in that, Step S2 specifically includes: The mineralizing solution, recovered ammonia water and industrial tail gas are reacted to produce calcium carbonate and recycled calcium extraction solution. The calcium carbonate in the mineralization reaction solution and the circulating calcium extraction solution are separated into solid and liquid components. Calcium carbonate is dried to obtain the calcium carbonate product.

3. The method for coupled CCUS for the cascade resource utilization of steel slag according to claim 1, characterized in that, Step S4 specifically includes: The alkaline solution was mixed with the secondary dissolving slag and stirred and heated. The silica component in the secondary dissolving slag was extracted into the silicate solution to obtain the tertiary dissolving slag. The tertiary slag and silicate solution are subjected to solid-liquid separation.

4. The method for coupled CCUS for the cascade resource utilization of steel slag according to claim 1, characterized in that, Step S5 specifically includes: carbonating the silicate solution to obtain a silica gel and carbonate solution; Solid-liquid separation of silica gel and carbonate solution; Silica is obtained by drying and dehydrating silica gel. Adding calcium oxide or calcium hydroxide to a carbonate solution regenerates the alkaline solution and yields calcium carbonate. Calcium carbonate and an alkaline solution are separated into solid and liquid components to obtain calcium carbonate and an alkaline solution. Calcium carbonate is dried to obtain the calcium carbonate product.

5. The method for coupled CCUS for the cascade resource utilization of steel slag according to claim 1, characterized in that, Step S6 specifically includes: The tertiary slag is loaded into the reactor and CO2 is added to the reactor to convert the calcium carbonate in the tertiary slag into calcium bicarbonate, which then dissolves in the solution. Adding H2O2 to the tertiary ore dissolving reaction solution converts ferrous iron into iron(III) oxide, increasing the magnetism of the iron ore phase. The fourth-stage molten slag and calcium bicarbonate solution were separated into solid and liquid components. Heating a calcium bicarbonate solution decomposes the calcium bicarbonate to obtain calcium carbonate, and the released CO2 is recovered. Solid-liquid separation of calcium carbonate from liquid phase; Calcium carbonate is dried to obtain the calcium carbonate product.

6. The method for coupled CCUS for the cascade resource utilization of steel slag according to claim 1, characterized in that, Step S7 specifically includes: The fourth-stage molten slag is added to the gravity separation equipment and separated according to specific gravity to obtain high-density iron ore and low-density tailings slag. The iron ore is passed through a magnetic separator to separate high-quality iron ore with an iron content greater than 50% and low-quality iron ore with an iron content of 40%-50% based on magnetic properties.

7. An apparatus for implementing the steel slag cascade resource utilization coupled with CCUS according to claim 1, characterized in that, include: The primary ore-dissolving unit is connected to the liquid phase outlet from the secondary ore-dissolving unit, and yields primary ore-dissolving slag and ore-dissolving liquid; The mineralization reaction unit is connected to the liquid phase outlet of the primary ore-dissolving unit and the ammonia recovery storage tank. The secondary ore-dissolving unit is connected to the solid phase outlet of the primary ore-dissolving unit and the liquid phase outlet of the mineralization reaction unit. The tertiary ore-dissolving unit is connected to the solid phase outlet of the secondary ore-dissolving unit; The silica unit is connected to the liquid phase outlet of the tertiary ore-dissolving unit; The fourth-level ore-dissolving unit is connected to the solid phase outlet of the third-level ore-dissolving unit; The gravity and magnetic separation unit is connected to the solid phase outlet of the fourth-stage ore-dissolving unit.

8. The device for the cascade resource utilization of steel slag coupled with CCUS according to claim 7, characterized in that, The primary ore-dissolving unit includes: The liquid phase inlet of the primary ore melting and slurry preparation vessel is connected to the liquid phase outlet of the secondary ore melting unit. Steel slag is added to the primary ore melting and slurry preparation vessel through the solid feed port. The primary ore melting reactor is connected to the bottom of the primary ore melting and slurry preparation vessel, and the reactor has a built-in steam heat exchange coil. The bottom of the ammonia absorption tower is connected to the gas outlet of the primary ore-dissolving reactor. The top of the primary slag dissolving and concentration kettle is connected to the bottom of the primary slag dissolving reactor. A primary slag plate and frame filter is connected to the bottom of a primary slag concentration reactor. Its liquid phase outlet is combined with the supernatant of the primary slag concentration reactor in a demineralization reaction unit. The heat exchanger is connected to the liquid phase outlet of the primary slag plate and frame filter press, and circulating cooling water is introduced into the shell layer. The mineralization reaction unit includes: The mineralization reactor is connected to the liquid phase outlet of the primary ore-dissolving unit and to the ammonia recovery tanks of the primary and secondary ore-dissolving units. Industrial tail gas is introduced into the reactor from the bottom through a distributor. The top of the mineralization reaction solution concentration vessel is connected to the liquid phase outlet of the mineralization reactor; The plate and frame filter press for mineralization reaction liquid has its inlet connected to the bottom of the mineralization reaction liquid concentration kettle, and its liquid phase outlet is combined with the supernatant outlet of the mineralization reaction liquid concentration kettle to go to the secondary ore dissolving unit. The secondary ore-dissolving unit includes: The secondary ore melting and slurry preparation vessel is fed with solid feed from the primary ore melting slag, and its top is connected to the outlet of the heat exchanger shell. A secondary ore-dissolving reactor is connected to the bottom of a secondary ore-dissolving pulping vessel, and the reactor has a built-in steam heat exchange coil. A condenser, which is connected to the top gas phase outlet of the secondary smelting reactor; The top of the secondary slag dissolving and concentration kettle is connected to the bottom of the secondary slag dissolving reactor; A secondary slag dissolving plate and frame filter press, which is connected to the bottom of a secondary slag dissolving concentration kettle; The three-stage ore-dissolving unit includes: The secondary ore-dissolving slag is added to the tertiary ore-dissolving pulping kettle through the solid feed port; The alkaline hydrolysis reactor is connected to the bottom of the three-stage ore dissolving and pulping kettle, and the alkaline hydrolysis reactor has a built-in water-steam heat exchange coil. The top of the three-stage slag concentration reactor is connected to the bottom of the alkaline hydrolysis reactor. The three-stage slag plate and frame filter is connected to the bottom outlet of the three-stage slag concentration kettle.

9. The device for cascaded resource utilization of steel slag coupled with CCUS according to claim 7, characterized in that, The silicon dioxide unit includes: The carbonation reactor is connected to the liquid phase outlet of the three-stage ore-dissolving unit, and CO2 is introduced into the carbonation reactor through the gas distributor at the bottom of the reactor. A centrifuge, which is connected to the outlet of the carbonation reactor; The alkaline regeneration reactor is connected to the liquid phase outlet of the centrifuge, and calcium hydroxide is added through the solid feed port of the alkaline regeneration reactor. The top of the circulating alkali concentration vessel is connected to the bottom of the alkali regeneration reactor. A circulating alkali plate and frame filter press, which is connected to the bottom of the circulating alkali concentration vessel; The fourth-level ore-dissolving unit includes: A CO2 compressor is used to pressurize CO2 gas. In the pressure ore melting reactor, the slag from the third stage of ore melting is added into the reactor through the solid inlet, hydrogen peroxide solution is introduced through the liquid phase inlet at the top of the reactor, and CO2 is introduced through the air inlet at the top of the reactor. The filter press is connected to the bottom outlet of the pressure smelting reactor and is equipped with high-pressure gas inlet and outlet pipelines; The calcium bicarbonate decomposition reactor is connected to the liquid phase outlet of the filter press and is equipped with a CO2 recovery pipeline. The calcium bicarbonate decomposition reactor has a built-in water vapor heat exchange coil, and saturated lime water is added through the liquid inlet at the top of the calcium bicarbonate decomposition reactor. The decomposition liquid plate and frame filter is connected to the bottom outlet of the calcium bicarbonate decomposition reactor.

10. The device for cascaded resource utilization of steel slag coupled with CCUS according to claim 7, characterized in that, The reselection and magnetic separation unit includes: The gravity separation equipment is connected to the solid phase outlet of the filter press via a conveyor belt; A magnetic separator, which is connected to the iron ore suspension outlet of a gravity separation device; The top of the iron ore concentration kettle is connected to the liquid phase outlet of the magnetic separator; The iron ore plate and frame filter press is connected to the bottom outlet of the iron ore concentration kettle.

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