Method and device for coupling CCUS through stepped resource utilization of steel slag

Abstract

The invention relates to the technical field of comprehensive utilization of steel slag and carbon neutralization, in particular to a method and a device for coupling CCUS (Carbon Control US) in stepped resource utilization of the steel slag, and the method comprises the following steps: breaking the connection of an ore phase in the steel slag to form a plurality of independent particles in a manner of multi-stage calcium extraction and alkaline hydrolysis silicon dissolution; and then high-iron particles and low-iron particles with higher density and stronger magnetism are separated through gravity separation equipment and magnetic separation, and finally iron ore with smelting value is obtained. In addition, the extracted calcium solution can also be used for absorbing industrial tail gas to realize permanent mineralization of CO2. By optimizing the reaction sequence of calcium extraction liquid in first-stage ore dissolution and second-stage ore dissolution, two-stage parallel ore dissolution liquid flows are combined into a series flow, and the technological process is simplified.

Description

Technical Field

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

[0002] Steel slag is an industrial waste residue generated during the steelmaking process, with a production volume accounting for about 15%-20% of the steel production volume, which is extremely large. These steel slags not only occupy land resources but also cause dust pollution, and will pollute rivers and groundwater after rain. If they can be reasonably utilized, not only can the pollution problem be solved, but the steel slag can also be turned from waste into treasure. A part of the traditional domestic steel slag is used for foundation backfilling, road paving, cement raw materials, steel slag phosphate fertilizer, etc. With the increasingly strict environmental protection requirements, the use of steel slag has been prohibited in NY_T 525-2021 "Organic Fertilizer" and GB175-2023 "Common Portland Cement". This has greatly restricted the scope of this extensive steel slag resource utilization, so it is urgent to develop a low-cost cascaded steel slag resource utilization process.

[0003] Removing impurities from steel slag to obtain ore with a high iron content is an important direction for steel slag. Steel mills will use magnetic separation to re-smelt or send the iron blocks and parts with a relatively high iron content in the steel slag to the sintering section. Some manufacturers will also crush the roughly selected steel slag and conduct secondary magnetic separation at the same time. After physical method recovery and treatment, the steel slag still contains more than 10% iron content. Depending on the steel slag production process, the iron content of some steel slags can reach more than 25%. The steel slag contains a large amount of calcium and silicon elements, with CaO accounting for 35%-50% and SiO2 accounting for 10%-15%. In addition, the steel slag also contains elements such as phosphorus, magnesium, silicon, aluminum, and manganese. Although it is feasible in technology 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 route of steel slag ironmaking has never been able to be applied. In order to obtain iron ore that meets the steelmaking process, further removing calcium and silicon elements from the steel slag is the key to increasing the iron content.

[0004] Calcium components in steel slag usually exist in the form of free calcium oxide, calcium silicate, and composite oxides formed by other elements. Through some processes, part of the calcium elements can be extracted as raw materials for CCUS. In CN115820946B, more than 80% of the calcium elements in steel slag are extracted into the solution through a two-stage calcium extraction process with ammonium chloride, and combined with CO2 in the factory tail gas to prepare calcium carbonate, achieving the effect of mineralizing and fixing carbon. In CN111558606B, through the process of pressurizing with CO2 and the addition of auxiliaries, part of the calcium elements in steel slag are converted into calcium bicarbonate and dissolved in the solution and separated from the steel slag. Then, by adjusting the pH value of the calcium bicarbonate solution, calcium bicarbonate is converted into calcium carbonate products. However, none of the above processes further utilize the steel slag after calcium extraction. The main reason is that although the iron content is enriched after calcium extraction from the steel slag, the mineral phase of the steel slag remains intact, and the calcium silicate phase and calcium phosphate phase in it are still combined with high iron and cannot be separated. CN116622920B uses ammonium chloride solution to extract calcium first to break the mineral phase of the steel slag, then oxidizes divalent iron in the steel slag to magnetite by oxidation to increase the magnetism of iron-containing particles in the steel slag, and finally screens out particles with different magnetic intensities by adjusting the magnetic field strength. However, this method still cannot solve the problem that ferrite in most calcium-extracted steel slag adheres to other mineral phases, and only 15-27% of iron ore with a higher iron content can be selected.

[0005] Therefore, whether it is possible to further break the connection between high-iron-content particles and low-iron-content particles after calcium extraction from steel slag is the key to improving the recovery rate of iron ore.

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

[0007] The purpose of the present invention is to provide a method and device for coupling CCUS with the step-by-step resource utilization of steel slag, which can solve the above technical problems.

[0008] The present invention provides a method for coupling CCUS with the step-by-step resource utilization of steel slag. This method breaks the connection of the internal mineral phase of the steel slag to form multiple independent particles by means of multi-stage calcium extraction and alkali hydrolysis to dissolve silicon, and then separates high-iron particles with higher density and stronger magnetism from low-iron particles through gravity separation equipment and magnetic separation, finally obtaining iron ore with smelting value. In addition, the extracted calcium solution can also be used to absorb industrial tail gas to achieve the permanent mineralization of CO2.

[0009] This method includes the following steps:

[0010] S1. Primary ore dissolution: React the primary ore dissolution solution obtained from the S3 secondary ore dissolution step with the steel slag, extract the highly active calcium components in the steel slag into the ore dissolution solution, simultaneously remove metal impurity ions in the ore dissolution solution, and obtain the primary ore dissolution slag;

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

[0012] S3, Secondary ore dissolution: React the recycled calcium-extracting solution obtained from the S2 mineralization reaction step with the primary ore-dissolution slag obtained from the S1 primary ore-dissolution reaction step, extract the low-activity calcium components in the primary ore-dissolution slag into the primary ore-dissolving solution, remove metal impurity ions in the primary ore-dissolving solution, and obtain a secondary ore-dissolution slag;

[0013] The cyclic relationship of the whole process can be summarized as follows: The product (primary ore-dissolving solution) of S3 provides raw materials for S1, the recycled calcium-extracting solution generated after the reaction of the product (ore-dissolving solution) of S1 through S2 provides raw materials for S3, and S3 generates a new primary ore-dissolving solution to enter the next cycle. In this way, continuous cycling realizes the full utilization of calcium components in steel slag and the gradual removal of metal impurity ions in the ore-dissolving solution. At the same time, calcium carbonate products are produced using CO2 in industrial tail gas;

[0014] S4, Tertiary ore dissolution: Mix an alkaline solution with the secondary ore-dissolution slag and stir and heat it to remove silica gel and silicon dioxide in the secondary ore-dissolution slag and obtain a tertiary ore-dissolution slag;

[0015] S5, Silicon dioxide preparation: Carbonate the silicate solution obtained in the S4 step to obtain silicon dioxide and regenerate the alkaline solution at the same time;

[0016] S6, Quaternary ore dissolution: Remove the calcium carbonate component in the tertiary ore-dissolution slag and obtain a quaternary ore-dissolution slag;

[0017] S7, Gravity separation and magnetic separation: Remove low-iron components with low density and low magnetism, and classify the obtained iron ore into high-grade iron ore and low-grade iron ore.

[0018] Preferably, the step S1 specifically includes:

[0019] Mix the steel slag with the ore-dissolving solution and stir and heat it, maintain the pH value at 8 - 11, and extract the high-activity calcium components in the steel slag into the ore-dissolving solution;

[0020] Absorb the ammonia gas escaping during the reaction and obtain ammonia water;

[0021] Perform solid-liquid separation on the primary ore-dissolution slag and the ore-dissolving solution;

[0022] The step S2 specifically includes:

[0023] Perform a mineralization reaction on the ore-dissolving solution, recycled ammonia water, and industrial tail gas to obtain calcium carbonate and a recycled calcium-extracting solution;

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

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

[0026] Specifically, the step S3 includes:

[0027] Mix and stir the circulating calcium extraction solution with the primary ore digestion slag and heat it, maintain the pH value at 6 - 9, and extract the calcium component in the primary ore digestion slag into the primary ore digestion solution;

[0028] Cool the ammonia gas and water vapor distilled during the secondary ore digestion reaction to obtain ammonia water;

[0029] Perform solid - liquid separation on the secondary ore digestion slag and the primary ore digestion solution;

[0030] Adjust the ore digestion solution to a pH value of 7 - 10 with ammonia water to convert the impurity ions in the solution into hydroxides and remove them.

[0031] Preferably, the step S4 specifically includes:

[0032] Mix and stir the alkaline solution with the secondary ore digestion slag and heat it, and extract the silica gel and silicon dioxide components in the secondary ore digestion slag into the silicate solution to obtain a tertiary ore digestion slag;

[0033] Perform solid - liquid separation on the tertiary ore digestion slag and the silicate solution.

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

[0035] Perform solid - liquid separation on the silica gel and the carbonate solution;

[0036] Dry and dehydrate the silica gel to obtain silicon dioxide;

[0037] Add calcium oxide or calcium hydroxide to the carbonate solution to regenerate the alkaline solution and obtain calcium carbonate;

[0038] Perform solid - liquid separation on the calcium carbonate and the alkaline solution to obtain calcium carbonate and the alkaline solution;

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

[0040] Preferably, the step S6 specifically includes:

[0041] Load the tertiary ore digestion slag into a reactor and add CO2 to the reactor to convert the calcium carbonate in the tertiary ore digestion slag into calcium bicarbonate and dissolve it in the solution;

[0042] Add H2O2 additionally to the tertiary ore digestion reaction solution to convert divalent iron into magnetite to increase the magnetism of the iron ore phase;

[0043] Perform solid - liquid separation on the quaternary ore digestion slag and the calcium bicarbonate solution;

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

[0045] Perform solid-liquid separation on the calcium carbonate and the liquid phase;

[0046] Dry the calcium carbonate to obtain the calcium carbonate product.

[0047] Preferably, the step S7 specifically includes:

[0048] Add the quaternary ore-dissolving slag to the gravity separation equipment for separation according to specific gravity to obtain high-density iron ore and low-density tailing slag;

[0049] Pass the iron ore through a magnetic separator to select high-quality iron ore with an iron content of more than 50% and low-quality iron ore with an iron content of 40%-50% according to magnetism.

[0050] The present invention also provides a device for the cascaded resource utilization of steel slag coupled with CCUS, including:

[0051] A primary ore-dissolving unit, which is connected to the liquid phase outlet from the secondary ore-dissolving unit and obtains primary ore-dissolving slag and ore-dissolving liquid;

[0052] A mineralization reaction unit, which is connected to the liquid phase outlet of the primary ore-dissolving unit and the ammonia recovery storage tank, and is used to carry out a mineralization reaction on CO2 in the plant tail gas and calcium ions in the primary mineralization liquid to convert them into calcium carbonate products and obtain a circulating calcium extraction liquid;

[0053] A secondary ore-dissolving unit, which is connected to the solid phase outlet of the primary ore-dissolving unit and the liquid phase outlet of the mineralization unit, and is used to extract most of the remaining calcium elements in the primary ore-dissolving slag into the primary ore-dissolving liquid and obtain secondary ore-dissolving slag;

[0054] A tertiary ore-dissolving unit, which is connected to the solid phase outlet of the secondary ore-dissolving unit and is used to dissolve the metasilicic acid generated during the ore-dissolving process and obtain tertiary ore-dissolving slag;

[0055] A silicon dioxide unit, which is connected to the liquid phase outlet of the tertiary ore-dissolving unit and is used to carbonate the dissolved silicate to obtain silica gel products, and at the same time regenerate the obtained carbonate solution into a strong alkali solution and obtain calcium carbonate products;

[0056] A quaternary ore-dissolving unit, which is connected to the solid phase outlet of the tertiary ore-dissolving unit and is used to convert calcium carbonate in the tertiary ore-dissolving slag into calcium bicarbonate and dissolve it in the solution to remove it from the solid phase and obtain quaternary ore-dissolving slag. In addition, the extracted calcium bicarbonate is converted into calcium carbonate products;

[0057] A gravity separation and magnetic separation unit, which is connected to the solid phase outlet of the quaternary ore-dissolving unit and is used to separate iron ore products with high density and high magnetism.

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

[0059] A primary ore-dissolving pulping kettle, whose liquid-phase inlet is connected to the liquid-phase outlet of the secondary ore-dissolving unit. The steel slag is added into the primary ore-dissolving pulping kettle through the solid feeding port, and it 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 to the bottom of the primary ore-dissolving pulping kettle. The reaction kettle is equipped with steam heat exchange coils inside, and it is used to remove impurities from the primary ore-dissolving liquid and extract the highly active calcium components in the steel slag at the same time;

[0061] An ammonia absorption tower, whose bottom is connected to the gas outlet of the primary ore-dissolving reactor. It is used to absorb most of the ammonia released during the ore-dissolving reaction, and the tail gas is incorporated into the CO2 tail gas and enters the mineralization reaction system;

[0062] A primary ore-dissolving slag thickening kettle, whose top is connected to the bottom of the primary ore-dissolving reactor, and it 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 to the bottom of the thickening kettle, and it is used to separate and wash the primary ore-dissolving slag from the ore-dissolving liquid. Its liquid-phase outlet is merged with the supernatant of the primary ore-dissolving slag thickening kettle and sent to the mineralization unit;

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

[0065] The mineralization reaction unit includes:

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

[0067] A mineralization reaction liquid thickening kettle, whose top is connected to the liquid-phase outlet of the mineralization reactor, and it is used to increase the solid content of calcium carbonate in the liquid phase;

[0068] A mineralization reaction liquid plate and frame filter, whose inlet is connected to the bottom of the calcium carbonate thickening kettle. Its liquid-phase outlet is merged with the supernatant outlet of the calcium carbonate thickening kettle and sent to the secondary ore-dissolving unit, and it is used to separate and wash calcium carbonate from the circulating calcium extraction liquid phase. The calcium carbonate is dried to obtain calcium carbonate products;

[0069] The secondary ore-dissolving unit includes:

[0070] Secondary ore-dissolving pulping kettle. The primary ore-dissolving slag is added to the secondary ore-dissolving pulping kettle through solid feeding. Its top is connected to the outlet of the shell side of the heat exchanger. It is used to disperse the primary ore-dissolving slag in the circulating calcium-extracting liquid to form a uniform suspension.

[0071] Secondary ore-dissolving reactor, which is connected to the bottom of the secondary ore-dissolving pulping kettle. The reactor is equipped with steam heat exchange coils inside. It is used to extract the calcium component in most of the calcium silicate in the primary ore-dissolving slag and obtain the secondary ore-dissolving slag.

[0072] 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.

[0073] Secondary ore-dissolving slag thickening kettle, whose top is connected to the bottom of the secondary ore-dissolving reactor, and is used to increase the solid content of the secondary ore-dissolving slag in the liquid phase.

[0074] Secondary ore-dissolving slag plate-and-frame filter, which is connected to the bottom of the thickening kettle, and is used to separate and wash the primary ore-dissolving slag and the ore-dissolving liquid.

[0075] The said tertiary ore-dissolving unit includes:

[0076] Tertiary ore-dissolving pulping kettle. The secondary ore-dissolving slag is added to the tertiary ore-dissolving pulping kettle through the solid feeding port. Inside the reaction kettle, it is used to disperse the secondary ore-dissolving slag in the circulating calcium-extracting liquid to form a uniform suspension.

[0077] Alkaline hydrolysis reactor, which is connected to the bottom of the tertiary ore-dissolving pulping kettle. The alkaline hydrolysis reactor is equipped with water-vapor heat exchange coils inside. It is used to extract most of the orthosilicic acid in the secondary ore-dissolving slag.

[0078] Tertiary ore-dissolving slag thickening kettle, whose top is connected to the bottom of the alkaline hydrolysis reactor, and is used to increase the solid content of the tertiary ore-dissolving slag in the liquid phase.

[0079] Tertiary ore-dissolving slag plate-and-frame filter, which is connected to the bottom outlet of the tertiary ore-dissolving slag thickening kettle. It is used for liquid-solid separation and washing of the tertiary ore-dissolving slag and the alkaline hydrolysis liquid to obtain the tertiary ore-dissolving slag and the alkaline hydrolysis liquid.

[0080] Preferably, the said silicon dioxide unit includes:

[0081] Carbonation reactor, which is connected to the liquid-phase outlet of the tertiary ore-dissolving unit. CO2 is introduced into the carbonation reactor through the gas distributor at the bottom of the reactor. It is used to convert the silicate and the remaining unreacted alkali in the alkaline hydrolysis liquid into silica gel and carbonate solution.

[0082] Centrifuge, which is connected to the outlet of the carbonation reactor; it is used for liquid-solid separation and washing of the silica gel and the carbonate solution. After the silica gel is dried, silica dioxide products are obtained.

[0083] An alkali solution regeneration reactor, which is connected to the liquid phase outlet of the centrifuge. Calcium hydroxide is added through the solid feed port of the strong alkali regeneration reactor, and it is used to convert most of the carbonates into calcium carbonate precipitates and the corresponding alkali solution.

[0084] A circulating alkali solution concentration kettle, whose top is connected to the bottom of the alkali solution regeneration reactor, and is used to increase the solid content of calcium carbonate in the liquid phase.

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

[0086] The four-stage ore dissolution unit includes:

[0087] A CO2 compressor, which is used to pressurize the CO2 gas.

[0088] A pressure ore dissolution reaction kettle. The three-stage ore dissolution slag is added into the reaction kettle through the solid inlet of the pressure ore dissolution reaction kettle. The hydrogen peroxide solution is introduced through the liquid phase inlet at the upper end of the reaction kettle, and 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 three-stage ore dissolution slag into calcium bicarbonate and dissolve it in the solution, and at the same time partially oxidize the divalent iron in the three-stage ore dissolution slag to magnetite.

[0089] A filter press, which is connected to the bottom outlet of the pressure ore dissolution reaction kettle and is equipped with a high-pressure gas inlet and recovery pipeline. It is used for the solid-liquid separation of the four-stage ore dissolution slag and the calcium bicarbonate solution, and obtains the four-stage ore dissolution slag and the calcium bicarbonate solution.

[0090] A calcium bicarbonate decomposition reaction kettle, which is connected to the liquid phase outlet of the filter press and is equipped with a CO2 recovery pipeline. The calcium bicarbonate decomposition reactor is internally provided with a water-vapor heat exchange coil. Saturated lime water is added through the liquid feed port 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.

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

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

[0093] A gravity separation device, which is connected to 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 slag, and obtains an iron ore suspension.

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

[0095] An iron ore thickening kettle, whose top is connected to the liquid phase outlet of a magnetic separator, is used to increase the solid content of low-grade iron ore in the liquid phase;

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

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

[0098] Beneficial effects:

[0099] In the present invention, by combining the chemical looping mineralization process of calcium extraction with ammonium chloride, the strong alkali solution silicon extraction process, the CO2 calcium carbonate dissolution process, and the gravity separation and magnetic separation processes, the problems of low iron ore recovery rate and low iron content in the ore during the resource utilization process of steel slag are completely solved. 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 for 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 first-stage ore dissolution and the second-stage ore dissolution, the two parallel ore dissolution liquid logistics are combined into a series logistics, simplifying the process flow. And no waste other than steel slag components is generated during the whole process, which is environmentally friendly. Description of the drawings

[0100] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0101] Figure 1 It is a block flow chart of the method for extracting high-quality iron ore coupled with CCUS using steel slag as a raw material provided by the present invention;

[0102] Figure 2 It is a schematic structural diagram of the first-stage ore dissolution unit in the device for extracting high-quality iron ore coupled with CCUS using steel slag as a raw material provided by the present invention;

[0103] Figure 3 It is a schematic structural diagram of the mineralization reaction unit in the device for extracting high-quality iron ore coupled with CCUS using steel slag as a raw material provided by the present invention;

[0104] Figure 4 It is a schematic structural diagram of the second-stage ore dissolution unit in the device for extracting high-quality iron ore coupled with CCUS using steel slag as a raw material provided by the present invention.

[0105] Figure 5 Schematic structural diagram of the three - stage ore dissolution unit in the device for extracting high - quality iron ore coupled with CCUS using steel slag as raw material provided by the present invention.

[0106] Figure 6 Schematic structural diagram of the four - stage ore dissolution unit in the device for extracting high - quality iron ore coupled with CCUS using steel slag as raw material provided by the present invention.

[0107] Figure 7 Schematic structural diagram of the gravity separation and magnetic separation unit in the device for extracting high - quality iron ore coupled with CCUS using steel slag as raw material provided by the present invention. Figure 8 Schematic structural diagram of the gravity separation and magnetic separation unit in the device for extracting high - quality iron ore coupled with CCUS using steel slag as raw material provided by the present invention.

[0108] Explanation of reference numerals: 100 - primary ore dissolution unit; 200 - mineralization unit; 300 - secondary ore dissolution unit; 400 - tertiary ore dissolution unit; 500 - silicon dioxide unit; 600 - quaternary ore dissolution unit; 700 - gravity separation and magnetic separation unit; R101 - primary ore dissolution reactor; T101 - ammonia absorption tower; V101 - primary ore dissolution pulping kettle; V102 - primary ore slag thickening kettle; F101 - primary ore slag plate - and - frame filter; R201 - mineralization reactor; V202 - mineralization reaction liquid thickening kettle; F201 - mineralization reaction liquid plate - and - frame filter; R301 - secondary ore dissolution reactor; R302 - primary ore dissolution liquid impurity removal reaction kettle; V301 - secondary ore dissolution pulping kettle; V302 - secondary ore slag thickening kettle; E301 - condenser; F301 - secondary ore slag plate - and - frame filter; F302 - impurity removal reaction liquid plate - and - frame filter; R401 - tertiary ore dissolution reactor; V401 - tertiary ore dissolution pulping kettle; V402 - tertiary ore slag thickening kettle; F401 - tertiary ore slag plate - and - frame filter; R501 - carbonation reactor; R502 - alkali solution regeneration reactor; V501 - circulating alkali solution thickening kettle; C501 - centrifuge; F501 - circulating alkali solution plate - and - frame filter; R601 - pressure ore dissolution reaction kettle; R602 - calcium bicarbonate decomposition reaction kettle; V601 - decomposition liquid thickening kettle; F601 - filter press; F602 - decomposition liquid plate - and - frame filter; S701 - gravity separation equipment; S702 - magnetic separator; V701 - iron ore thickening kettle; F701 - iron ore plate - and - frame filter. Detailed implementation manners

[0109] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some but not all of the embodiments of the present invention. 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.

[0110] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0111] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined. In addition, the terms "mounted", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0112] Figure 1 It is a block flow chart of a method for extracting high-quality iron ore coupled with CCUS using steel slag as a raw material provided in an embodiment of the present invention. As shown in the figure, a method for extracting high-quality iron ore coupled with CCUS using steel slag as a raw material provided by the present invention includes:

[0113] S1. Primary ore dissolution: Extract the highly active calcium components in the steel slag into the ore dissolution solution, and at the same time remove the metal impurity ions in the ore dissolution solution;

[0114] S2. Mineralization reaction: React the calcium ions in the ore dissolution solution with CO2 in the industrial tail gas to obtain calcium carbonate;

[0115] S3. Secondary ore dissolution: Extract the low-active calcium components in the primary ore dissolution slag into the primary ore dissolution solution, and remove part of the metal impurity ions in the primary ore dissolution solution;

[0116] S4, Tertiary ore dissolution: Remove silica gel and part of silicon dioxide from the secondary ore dissolution slag;

[0117] S5, Silicon dioxide preparation: Carbonate the silicate solution obtained in step S4 to obtain silicon dioxide, and at the same time regenerate the lye;

[0118] S6, Quaternary ore dissolution: Remove the calcium carbonate component from the tertiary ore dissolution slag;

[0119] S7, Gravity separation and magnetic separation: Remove the low-iron components with low density and low magnetism, and classify the obtained iron ore into high-grade iron ore and low-grade iron ore.

[0120] Optionally, the primary ore dissolution in S1 obtains a primary ore dissolution slag, including:

[0121] Mix the steel slag with the primary ore dissolution liquid described in S3, stir and heat, maintain the pH value at 8 - 11, and extract the highly active calcium component in the steel slag into the ore dissolution liquid;

[0122] Absorb the ammonia gas escaping during the reaction to obtain ammonia water;

[0123] Perform solid-liquid separation on the primary ore dissolution slag and the ore dissolution liquid in the reaction liquid;

[0124] Perform heat exchange on the ore dissolution liquid and the calcium extraction circulating liquid in S2;

[0125] Optionally, the mineralization reaction in S2 obtains a calcium carbonate product, including:

[0126] Perform a mineralization reaction on the ore dissolution liquid, the recycled ammonia water and the industrial tail gas to obtain calcium carbonate and a calcium extraction circulating liquid;

[0127] Perform solid-liquid separation on the calcium carbonate and the calcium extraction circulating liquid in the mineralization reaction liquid;

[0128] Dry the calcium carbonate to obtain a calcium carbonate product.

[0129] Optionally, the secondary ore dissolution in S3 includes:

[0130] Mix the calcium extraction circulating liquid with the primary ore dissolution slag, stir and heat, maintain the pH value at 6 - 9, and extract most of the calcium components in the primary ore dissolution slag into the primary ore dissolution liquid;

[0131] Cool the ammonia gas and water vapor evaporated during the secondary ore dissolution reaction to obtain ammonia water;

[0132] Perform solid-liquid separation on the secondary ore dissolution slag and the primary ore dissolution liquid in the reaction liquid;

[0133] Adjust 20% - 100% of the primary ore dissolution liquid to a pH value of 7 - 10, preferably 8 - 9, with ammonia water to remove the impurity ions in the solution as hydroxides;

[0134] Perform solid-liquid separation on the impurity removal part in the primary ore-dissolving solution to obtain composite hydroxide and primary impurity-removed ore-dissolving solution. After mixing this reaction solution with the primary ore-dissolving solution, it is used for the first-stage ore dissolution in S1.

[0135] Optionally, the third-stage ore dissolution in S4 includes:

[0136] Mix the alkali solution with the second-stage ore-dissolving slag and stir and heat it, and extract most of the silica gel and part of the silicon dioxide components in the second-stage ore-dissolving slag into the silicate solution to obtain the third-stage ore-dissolving slag;

[0137] Perform solid-liquid separation on the third-stage ore-dissolving slag and the silicate solution;

[0138] Optionally, the preparation of silicon dioxide in S5 includes:

[0139] Carbonate the silicate solution to obtain silica gel and carbonate solution;

[0140] Perform solid-liquid separation on the silica gel and the carbonate solution;

[0141] Dry and dehydrate the silica gel to obtain silicon dioxide;

[0142] Add calcium oxide or calcium hydroxide to the carbonate solution to regenerate the alkali solution and obtain calcium carbonate;

[0143] Perform solid-liquid separation on the calcium carbonate and the alkali solution to obtain calcium carbonate and the alkali solution;

[0144] Dry the calcium carbonate to obtain calcium carbonate product.

[0145] Optionally, the fourth-stage ore dissolution in S6 includes:

[0146] Load the third-stage ore-dissolving slag into a reactor and add CO2 into the reactor. Under certain temperature and pressure, convert the calcium carbonate in the third-stage ore-dissolving slag into calcium bicarbonate and dissolve it in the solution;

[0147] Add H2O2 additionally to the third-stage ore-dissolving reaction solution to convert part of the divalent iron into magnetite to increase the magnetism of the iron ore phase;

[0148] Perform solid-liquid separation on the fourth-stage ore-dissolving slag and the calcium bicarbonate solution;

[0149] Heat the calcium bicarbonate solution to decompose calcium bicarbonate to obtain calcium carbonate and recycle the released CO2;

[0150] Perform solid-liquid separation on the calcium carbonate and the liquid phase;

[0151] Dry the calcium carbonate to obtain calcium carbonate product.

[0152] Optionally, the gravity separation and magnetic separation in S7 includes:

[0153] Add the four - stage ore - melting slag into the gravity separation equipment for separation according to the specific gravity to obtain high - density iron ore and low - density tailing slag;

[0154] Pass the iron ore through a magnetic separator to select high - quality iron ore with an iron content of more than 50% and low - quality iron ore with an iron content of 40% - 50% according to magnetism.

[0155] See Figures 2 - 7 , this invention also provides a device for extracting high - quality iron ore coupled with CCUS using steel slag as raw material simultaneously in the embodiment. The device of the embodiment of this invention can be used for the method of the embodiment. Some contents of the method of the embodiment of this invention can be used to understand and explain the device of the embodiment of this invention, and some contents of the device of the embodiment of this invention can also be used to understand and explain the method of the embodiment of this invention. The device of the embodiment of this invention includes:

[0156] The first - stage ore - melting unit, which is connected to the liquid - phase outlet from the second - stage ore - melting unit, and obtains the first - stage ore - melting slag and ore - melting liquid.

[0157] The mineralization reaction unit, which is connected to the liquid - phase outlet of the first - stage ore - melting unit and the recovered ammonia water storage tank, is used to carry out a mineralization reaction between CO2 in the plant tail gas and calcium ions in the first - stage mineralized liquid to convert them into calcium carbonate products, and obtain a circulating calcium - extracting liquid.

[0158] The second - stage ore - melting unit, which is connected to the solid - phase outlet of the first - stage ore - melting unit and the liquid - phase outlet of the mineralization unit, is used to extract most of the remaining calcium elements in the first - stage ore - melting slag into the primary ore - melting liquid, and obtain the second - stage ore - melting slag.

[0159] The third - stage ore - melting unit, which is connected to the solid - phase outlet of the second - stage ore - melting unit. It is used to dissolve the orthosilicic acid generated during the ore - melting process and obtain the third - stage ore - melting slag.

[0160] The silicon dioxide unit, which is connected to the liquid - phase outlet of the third - stage ore - melting unit. It is used to carbonate the dissolved silicate to obtain silica gel products. At the same time, the obtained carbonate solution is regenerated into a strong alkali solution, and calcium carbonate products are obtained.

[0161] The fourth - stage ore - melting unit, which is connected to the solid - phase outlet of the third - stage ore - melting unit, is used to convert calcium carbonate in the third - stage ore - melting slag into calcium bicarbonate and dissolve it in the solution to remove it from the solid phase, and obtain the fourth - stage ore - melting slag. In addition, the extracted calcium bicarbonate is converted into calcium carbonate products.

[0162] The gravity separation and magnetic separation unit, which is connected to the solid - phase outlet of the fourth - stage ore - melting unit, is used to separate out iron ore products with higher density and higher magnetism.

[0163] Optionally, the first - stage ore - melting unit includes:

[0164] The first-stage ore-dissolving and pulp-making kettle has its liquid-phase inlet connected to the liquid-phase outlet of the second-stage ore-dissolving unit. Steel slag is added into the first-stage ore-dissolving and pulp-making kettle through the solid feed port. It is used to disperse the steel slag in the primary ore-dissolving liquid to form a uniform suspension.

[0165] The first-stage ore-dissolving reactor is connected to the bottom of the first-stage ore-dissolving and pulp-making kettle, and a steam heat-exchanging coil is installed inside the reaction kettle. It is used to remove impurities from the primary ore-dissolving liquid and extract the highly active calcium component in the steel slag at the same time.

[0166] The ammonia absorption tower has its bottom connected to the gas outlet of the first-stage ore-dissolving reactor. It is used to absorb most of the ammonia released during the ore-dissolving reaction. The tail gas is incorporated into the CO2 tail gas and enters the mineralization reaction system.

[0167] The first-stage ore-dissolving slag thickening kettle has its top connected to the bottom of the first-stage ore-dissolving reactor, and is used to increase the solid content of the first-stage ore-dissolving slag in the liquid phase.

[0168] The first-stage ore-dissolving slag plate-and-frame filtration unit is connected to the bottom of the thickening kettle, and is used to separate and wash the first-stage ore-dissolving slag from the ore-dissolving liquid. Its liquid-phase outlet is merged with the supernatant of the first-stage ore-dissolving slag thickening kettle and sent to the mineralization unit.

[0169] The heat exchanger is connected to the liquid-phase outlet of the plate-and-frame filtration unit, and circulating cooling water is introduced into the shell side. It is used to cool down the ore-dissolving liquid.

[0170] Optionally, the mineralization reaction unit includes:

[0171] The mineralization reactor is connected to the liquid-phase outlet of the first-stage ore-dissolving unit and to the ammonia recovery tank of the first-stage and second-stage ore-dissolving units. Industrial tail gas is introduced into the reactor from the bottom through a distributor. It is used to react calcium ions, ammonia water in the ore-dissolving liquid with CO2 in the industrial tail gas to obtain a calcium carbonate suspension.

[0172] The mineralization reaction liquid thickening kettle has its top connected to the liquid-phase outlet of the mineralization reactor, and is used to increase the solid content of calcium carbonate in the liquid phase.

[0173] The mineralization reaction liquid plate-and-frame filtration unit has its inlet connected to the bottom of the calcium carbonate thickening kettle, and its liquid-phase outlet is merged with the supernatant outlet of the calcium carbonate thickening kettle and sent to the second-stage ore-dissolving unit. It is used to separate and wash calcium carbonate from the circulating calcium-extracting liquid phase. The calcium carbonate is dried to obtain calcium carbonate products.

[0174] Optionally, the second-stage ore-dissolving unit includes:

[0175] The second-stage ore-dissolving and pulp-making kettle. The first-stage ore-dissolving slag is added into the second-stage ore-dissolving and pulp-making kettle through solid feeding, and its top is connected to the outlet of the shell side of the heat exchanger. It is used to disperse the first-stage ore-dissolving slag in the circulating calcium-extracting liquid to form a uniform suspension.

[0176] The secondary ore-dissolving reactor is connected to the bottom of the secondary ore-dissolving and pulping kettle, and steam heat exchange coils are installed inside the reactor. It is used to extract the calcium components in most of the calcium silicate in the primary ore-dissolving slag and obtain the secondary ore-dissolving slag.

[0177] The condenser 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 from it.

[0178] The secondary ore-dissolving slag thickening kettle 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 slag in the liquid phase.

[0179] The secondary ore-dissolving slag plate-and-frame filtration unit is connected to the bottom of the thickening kettle, and is used to separate and wash the primary ore-dissolving slag and the ore-dissolving liquid.

[0180] Optionally, the tertiary ore-dissolving unit includes:

[0181] The tertiary ore-dissolving and pulping kettle is connected to the liquid-phase outlet of the strong alkali plate-and-frame filtration. The secondary ore-dissolving slag is added to the tertiary ore-dissolving and pulping kettle through the solid feeding port. Inside the reaction kettle, it is used to disperse the secondary ore-dissolving slag in the circulating calcium extraction liquid to form a uniform suspension.

[0182] The alkali hydrolysis reactor is connected to the bottom of the tertiary ore-dissolving and pulping kettle. Steam-water heat exchange coils are installed inside the alkali hydrolysis reactor. It is used to extract most of the orthosilicic acid in the secondary ore-dissolving slag.

[0183] The tertiary ore-dissolving slag thickening kettle is connected to the bottom of the alkali hydrolysis reactor at the top, and is used to increase the solid content of the tertiary ore-dissolving slag in the liquid phase.

[0184] The tertiary ore-dissolving slag plate-and-frame filtration unit is connected to the bottom outlet of the tertiary ore-dissolving slag thickening kettle. It is used for liquid-solid separation and washing of the tertiary ore-dissolving slag and the alkali hydrolysis liquid to obtain the tertiary ore-dissolving slag and the alkali hydrolysis liquid.

[0185] Optionally, the silica unit includes:

[0186] The carbonation reactor is connected to the liquid-phase outlet of the tertiary ore-dissolving unit, and CO2 is introduced into the carbonation reactor through the gas distributor at the bottom of the reactor. It is used to convert the silicate and the remaining unreacted alkali in the alkali hydrolysis liquid into silica gel and carbonate solution.

[0187] The centrifuge is connected to the outlet of the carbonation reactor. It is used for liquid-solid separation and washing of the silica gel and the carbonate solution. After drying the silica gel, silica products are obtained.

[0188] The alkali solution regeneration reactor is connected to the liquid-phase outlet of the centrifuge. Calcium hydroxide is added through the solid feeding port of the alkali solution regeneration reactor. It is used to convert most of the carbonate into calcium carbonate precipitate and the corresponding alkali solution.

[0189] The circulating alkali liquor concentration kettle is connected to the bottom of the alkali liquor regeneration reactor at its top. It is used to increase the solid content of calcium carbonate in the liquid phase.

[0190] The circulating alkali liquor plate and frame filter press is connected to the bottom of the alkali regeneration and concentration kettle. It is used for liquid-solid separation and washing of calcium carbonate and strong alkali solution, and calcium carbonate and circulating alkali liquor are obtained. The calcium carbonate is dried to obtain calcium carbonate products;

[0191] Optionally, the four-stage ore dissolution unit includes:

[0192] The CO2 compressor is used to pressurize the CO2 gas;

[0193] The pressure ore dissolution reactor is connected to the liquid phase outlet of the decomposed calcium carbonate plate and frame filter. The three-stage ore dissolution slag is added into the reactor through the solid inlet of the pressure ore dissolution reactor. The hydrogen peroxide solution is introduced through the liquid phase inlet at the upper end of the reactor, and the CO2 is introduced through the gas inlet at the upper end of the reactor. It is used to convert calcium carbonate in the three-stage ore dissolution slag into calcium bicarbonate and dissolve it in the solution, and at the same time, partially oxidize divalent iron in the three-stage ore dissolution slag to magnetite.

[0194] The filter press is connected to the bottom outlet of the pressure ore dissolution reactor. It is equipped with high-pressure gas introduction and recovery pipelines. It is used for solid-liquid separation of the four-stage ore dissolution slag and calcium bicarbonate solution, and the four-stage ore dissolution slag and calcium bicarbonate solution are obtained.

[0195] 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 is internally provided with a water-vapor heat exchange coil. Saturated lime water is added through the liquid feed inlet at the upper end of the calcium bicarbonate decomposition reactor. It is used for the decomposition of calcium bicarbonate in the solution and the recovery of CO2.

[0196] The decomposed liquid plate and frame filter press is connected to the bottom outlet of the calcium bicarbonate decomposition reactor. It is used for solid-liquid separation of calcium carbonate and the decomposed liquid, and calcium carbonate and the decomposed liquid are obtained. The calcium carbonate is dried to obtain calcium carbonate products.

[0197] Optionally, the gravity separation and magnetic separation unit includes:

[0198] The gravity separation equipment is one of a shaking table, a spiral chute, a jigs, a centrifugal concentrator, etc. It is connected to the solid phase outlet of the filter press through a conveyor belt. It is used for the separation of heavy iron ore and light tailings slag to obtain an iron ore suspension.

[0199] The magnetic separator is connected to the iron ore suspension outlet of the gravity separation equipment. It is used for the separation of high-grade iron ore and low-grade iron ore, and suspensions of high-grade iron ore and low-grade iron ore are obtained.

[0200] An iron ore thickening kettle, whose top is connected to the liquid phase outlet of a magnetic separator, is used to increase the solid content of low-grade iron ore in the liquid phase.

[0201] An iron ore plate and frame filter press is connected to the bottom outlet of the iron ore thickening kettle. It is used to separate iron ore from the dispersion liquid to finally obtain low-grade iron ore.

[0202] The following further illustrates the solutions and effects of the method and device of the present invention in combination with specific embodiments.

[0203] In some examples, such as Figure 2 As shown, in the primary ore dissolution unit 100, steel slag 101, primary ore dissolution liquid 128, and part of the impurity-removed primary ore dissolution liquid 132 are added to the primary ore dissolution and pulping kettle V101 to prepare a dispersion liquid 102, which is then added to the primary ore dissolution reactor R101 for primary ore dissolution reaction. The obtained reaction liquid 106 enters the primary ore dissolution slag thickening kettle V102 to concentrate the solid concentration to 20%-30%, and then the concentrated liquid 107 is sent to the primary ore dissolution slag plate and frame filter press F101 for filtration and washing to obtain the primary ore dissolution slag filter cake 111, which goes to the secondary ore dissolution unit 300. The filtrate 108 is merged with the supernatant liquid 109 obtained from the primary ore dissolution slag thickening kettle V102 to form 110 and goes to the demineralization unit 200. The ammonia gas 103 generated by the primary ore dissolution reaction is absorbed through the ammonia gas absorption tower T101 to obtain ammonia water 104. The waste gas 105 is discharged to the waste gas treatment system.

[0204] In some embodiments of the present invention, such as Figure 2 As shown, in steps S1 and S2, a heat exchanger or a heat pump can be used to perform heat exchange between the high-temperature ore dissolution liquid obtained in step S1 and the low-temperature circulating calcium extraction liquid obtained in S2, and then it is cooled to a suitable temperature required for the mineralization reaction through a heat exchanger through which condensed water passes. The energy consumption in the ore dissolution process can be reduced through heat integration technology.

[0205] In some embodiments of the present invention, such as Figure 3 As shown, the demineralization unit 200 mixes the ammonia water and ammonia water mixed liquid 123 recovered from the secondary ore dissolution unit 300 with the ore dissolution liquid 110 obtained from the primary ore dissolution unit 100 and feeds it into the mineralization reactor R201. At the same time, the industrial tail gas 113 is introduced into the gas distributor at the bottom of R201 to perform a mineralization reaction with the liquid phase. The mineralization reaction liquid 115 is transported to the mineralization reaction liquid thickening kettle V201 to concentrate the solid concentration to 20%-30%, and then the concentrated liquid 117 is sent to the mineralization reaction liquid plate and frame filter press F201 for filtration and washing to obtain a calcium carbonate filter cake 120, which is dried and crushed to obtain calcium carbonate finished products. The filtrate 118 is merged with the supernatant liquid 116 obtained from the mineralization reaction liquid thickening kettle V201 to form a circulating calcium extraction liquid 119, which goes to the secondary ore dissolution unit 300.

[0206] In some embodiments of the present invention, such asFigure 4 As shown, the secondary ore dissolution unit 300 disperses the primary ore dissolution slag 111 from the primary ore dissolution unit 100 and the recycled calcium-extracted liquid 119 from the mineralization reaction unit 200 in the secondary ore dissolution pulping kettle V301 to prepare a dispersion liquid 121, which is added to the secondary ore dissolution reactor R201 for the primary ore dissolution reaction. The obtained reaction liquid 123 enters the secondary ore dissolution slag thickening kettle V302 to thicken the solid concentration to 20%-30%. Then, the thickened liquid 125 is sent to the secondary ore dissolution slag plate and frame filter F301 for filtration and washing to obtain the secondary ore dissolution slag filter cake 127, which goes to the tertiary ore dissolution unit 400. The filtrate 126 is merged with the supernatant 124 obtained from the secondary ore dissolution slag thickening kettle V302, and then 30% of the primary ore dissolution liquid 129 is taken to the primary ore dissolution liquid impurity removal reaction kettle R302. At the same time, ammonia water 130 is introduced to adjust the pH value to 8-9 to obtain a reaction liquid 131. After filtration and washing through the impurity removal reaction liquid plate and frame filter F302, a composite hydroxide 133 is obtained. The obtained primary ore dissolution liquid 132 after impurity removal goes to the primary ore dissolution unit 100. The remaining primary ore dissolution liquid 128 goes to the primary ore dissolution unit 100. The mixture of steam and ammonia gas generated during the secondary ore dissolution reaction is condensed by the condenser E301 to obtain ammonia water 122, which is merged with the ammonia water 104 obtained from the primary ore dissolution reaction to form the recycled ammonia water 123 and is transported to the mineralization reaction unit 200.

[0207] In some embodiments of the present invention, as Figure 4 shown, in step S3, all or part of the primary ore dissolution liquid goes to the ammonia water impurity removal process. Sending all of it to the ammonia water impurity removal can effectively ensure the removal of impurity ions in the ore dissolution liquid. However, in this process, the pH value needs to be adjusted to 9-10, which will cause more ammonia gas to be evaporated in step S1, increasing the ammonia evaporation energy consumption and the load of the T101 ammonia absorption tower. Only using part of the primary ore dissolution liquid for impurity removal will reduce the ammonia usage. Metal impurity ions will circulate and accumulate in the primary ore dissolution slag and the primary ore dissolution liquid, and the concentration will gradually increase. Therefore, in the process of removing impurities from part of the primary ore dissolution liquid, only the pH value needs to be adjusted to 8-9 to remove most of the metal impurity ions.

[0208] In some embodiments of the present invention, as Figure 5 shown, the tertiary ore dissolution unit 400 disperses the secondary ore dissolution slag from the secondary ore dissolution unit 300, the regenerated alkali liquid 154, and the supplementary alkali liquid 143 in the tertiary ore dissolution pulping kettle V401 for pulping. The obtained dispersion liquid 136 is added to the tertiary ore dissolution reactor R401 for the tertiary ore dissolution reaction. The obtained reaction liquid 137 enters the tertiary ore dissolution slag thickening kettle V402 to thicken the solid concentration to 20%-30%. Then, the thickened liquid 139 is sent to the tertiary ore dissolution slag plate and frame filter F401 for filtration and washing to obtain the tertiary ore dissolution slag filter cake 142, which goes to the quaternary ore dissolution unit 600. The filtrate 140 is merged with the supernatant 138 obtained from the tertiary ore dissolution slag thickening kettle V402 to obtain a silicate solution 141.

[0209] In some embodiments of the present invention, as Figure 6 shown, the silica unit 500 simultaneously adds the silicate solution 141 from the three-stage ore-dissolving unit 400 and the CO2 gas 144 into the carbonation reactor R501 for reaction to obtain the carbonation reaction liquid 146. The unreacted gas 145 enters the tail gas treatment system. The carbonation reaction liquid 146 is subjected to solid-liquid separation and washing by the centrifuge C501 to obtain silica gel 147, which is sent to the drying unit to obtain silica products. The obtained carbonate solution 148 is added to the alkali solution regeneration reactor R502 to react with calcium hydroxide 149. The obtained reaction liquid 150 enters the circulating alkali solution concentration kettle V501 to concentrate the solid concentration to 20%-30%, and then the concentrated liquid 152 is sent to the circulating alkali solution 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 solution concentration kettle V501 are combined into 154 and sent to the three-stage ore-dissolving unit 400.

[0210] In some embodiments of the present invention, as Figure 7 shown, the four-stage ore-dissolving unit 600 adds the three-stage ore-dissolving slag 142 from the three-stage ore-dissolving unit 400, high-pressure CO2 gas 156, and hydrogen peroxide solution 167 into the pressure ore-dissolving reactor R601 for four-stage ore-dissolving reaction. The obtained four-stage ore-dissolving reaction liquid 158 is transported to the filter press F601 for pressure filtration and washing. The obtained four-stage ore-dissolving slag 159 is sent to the gravity separation and magnetic separation unit 700. The obtained calcium bicarbonate solution 160 is transported to the calcium bicarbonate decomposition kettle R602 for heating decomposition. The obtained calcium carbonate suspension 162 is transported to the decomposition liquid concentration kettle V601 to concentrate the calcium carbonate concentration to 20%-30%, and then the concentrated liquid 164 is sent to the decomposition liquid plate and frame filter 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 kettle V601 are combined into 166 for wastewater treatment. The CO2 gas 161 released during the reaction in the calcium bicarbonate decomposition kettle R602 is combined with the CO2 discharged from the pressure relief of the ore-dissolving reactor R601 and the filter press F601 to form 157 and sent to the tail gas treatment.

[0211] In some embodiments of the present invention, the CO2 tail gas 157 can be mixed into the industrial tail gas 113 in the mineralization reaction unit 200 for absorption to increase the net CO2 emission reduction of the whole set of devices.

[0212] In some embodiments of the present invention, the CO2 tail gas 157 can be used as the CO2 gas 144 for the carbonation reaction in the silica unit 500 to increase the net CO2 emission reduction of the whole set of devices.

[0213] In some embodiments of the present invention, a part of the CO2 tail gas 157 can be pressurized by a compressor and then mixed into the high-pressure CO2 gas 156 in the silica unit 500 for the four-stage ore dissolution reaction. The purge gas is preferentially used for the carbonation reaction in the silica unit 500, and the excess tail gas is mixed into the industrial tail gas 113 in the mineralization reaction unit 200 for absorption. This can make full use of high-concentration CO2 and at the same time increase the net CO2 emission reduction of the entire device.

[0214] In some embodiments of the present invention, such as Figure 7 shown, the calcium bicarbonate decomposition liquid 166 has fewer impurities and dissolves more CO2, and can be used to prepare a hydrogen peroxide solution 167 and return it to the pressure ore dissolution reaction kettle R601 for recycling, thereby reducing the amount of wastewater treatment, reducing CO2 emissions, and improving the economic benefits of the entire device.

[0215] In some embodiments of the present invention, such as Figure 8 shown, the gravity separation and magnetic separation unit 700 adds the four-stage ore dissolution slag and the dispersion liquid 177 from the four-stage ore dissolution unit 600 to the gravity separation equipment S701 for separation. The obtained light tailings 169 are naturally settled, the liquid goes to waste liquid treatment, and the solid goes to solid waste treatment. The obtained coarse iron ore dispersion liquid 170 is sent to the magnetic separator S702. The iron ore 171 with higher magnetism is separated from it, washed, and then dried to obtain high-grade iron ore. The remaining low-grade iron ore dispersion liquid 172 is sent to the iron ore thickening kettle V701 to thicken the solid concentration to 20%-30%, and the thickened liquid 174 is sent to the iron ore plate and frame filter F701 for filtration and washing to obtain a low-grade iron ore filter cake 178, which is sent to solid drying to obtain low-grade iron ore, and the filtrate 175 is merged with the supernatant 173 obtained from the iron ore thickening kettle V701 to be 176 for wastewater treatment.

[0216] In some embodiments of the present invention, such as Figure 8 shown, after the light tailings 169 are naturally settled, the dispersion liquid is returned to the inlet of the gravity separation and magnetic separation unit 700 as part of the dispersion liquid 177, thereby reducing the amount of wastewater treatment, reducing the consumption of additives, and improving the economic benefits of the entire device.

[0217] In some embodiments of the present invention, such as Figure 8 shown, the obtained wastewater 176 can be returned to the inlet of the gravity separation and magnetic separation unit 700 as part of the dispersion liquid 177, thereby reducing the amount of wastewater treatment, reducing the consumption of additives, and improving the economic benefits of the entire device.

[0218] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than 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 described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the step-by-step resource utilization of steel slag coupled with CCUS, characterized in that, It includes the following steps: S1. Primary ore dissolution: React the primary ore dissolution solution obtained from the S3 secondary ore dissolution step with steel slag, extract the highly active calcium components in the steel slag into the ore dissolution solution, simultaneously remove the metal impurity ions in the ore dissolution solution, and obtain primary ore dissolution slag; S2. Mineralization reaction: React the calcium ions in the ore dissolution solution with CO2 in industrial tail gas to obtain calcium carbonate and obtain a recycled calcium extraction solution; S3. Secondary ore dissolution: React the recycled calcium extraction solution obtained from the S2 mineralization reaction step with the primary ore dissolution slag obtained from the S1 primary ore dissolution reaction step, extract the low-active calcium components in the primary ore dissolution slag into the primary ore dissolution solution, remove the metal impurity ions in the primary ore dissolution solution, and obtain secondary ore dissolution slag; S4. Tertiary ore dissolution: Mix the alkali solution with the secondary ore dissolution slag and stir and heat it to remove silica gel and silicon dioxide in the secondary ore dissolution slag and obtain tertiary ore dissolution slag; S5. Silicon dioxide preparation: Carbonate the silicate solution obtained in the S4 step to obtain silicon dioxide and regenerate the alkali solution simultaneously; S6. Quaternary ore dissolution: Remove the calcium carbonate component in the tertiary ore dissolution slag and obtain quaternary ore dissolution slag; S7. Gravity separation and magnetic separation: Remove the low-iron components with low density and low magnetism and classify the obtained iron ore into high-grade iron ore and low-grade iron ore.

2. The method for the step-by-step resource utilization of steel slag coupled with CCUS according to claim 1, wherein The specific steps of S1 include: Mix the steel slag with the ore dissolution solution and stir and heat it, maintain the pH value at 8 - 11, and extract the highly active calcium components in the steel slag into the ore dissolution solution; Absorb the ammonia gas evolved during the reaction and obtain ammonia water; Perform solid-liquid separation on the primary ore dissolution slag and the ore dissolution solution; The specific steps of S2 include: Perform a mineralization reaction on the ore dissolution solution, recycled ammonia water and industrial tail gas to obtain calcium carbonate and a recycled calcium extraction solution; Perform solid-liquid separation on the calcium carbonate and the recycled calcium extraction solution in the mineralization reaction solution; Dry the calcium carbonate and obtain calcium carbonate products; The specific steps of S3 include: Mix the recycled calcium extraction solution with the primary ore dissolution slag and stir and heat it, maintain the pH value at 6 - 9, and extract the calcium components in the primary ore dissolution slag into the primary ore dissolution solution; Cool the ammonia gas and water vapor distilled out during the secondary ore dissolution reaction to obtain ammonia water; Perform solid-liquid separation on the secondary ore dissolution slag and the primary ore dissolution solution; Adjust the ore dissolution solution to a pH value of 7 - 10 with ammonia water to convert the impurity ions in the solution into hydroxides and remove them.

3. The method for coupling CCUS with the step-by-step resource utilization of steel slag according to claim 1 is characterized in that, The specific steps of S4 include: Mix the alkali solution with the secondary ore dissolution slag and stir and heat it, and extract the silica gel and silicon dioxide components in the secondary ore dissolution slag into the silicate solution and obtain tertiary ore dissolution slag; Perform solid-liquid separation on the tertiary ore dissolution slag and the silicate solution.

4. The method for the stepped resource utilization of steel slag coupled with CCUS according to claim 1, characterized in that The specific steps of S5 include: Carbonate the silicate solution and obtain silica gel and a carbonate solution; Perform solid-liquid separation on the silica gel and the carbonate solution; Dry and dehydrate the silica gel to obtain silicon dioxide; Add calcium oxide or calcium hydroxide to the carbonate solution to regenerate the alkali solution and obtain calcium carbonate; Perform solid-liquid separation on the calcium carbonate and the alkali solution to obtain calcium carbonate and the alkali solution; Dry the calcium carbonate and obtain calcium carbonate products.

5. The method for the step-by-step resource utilization of steel slag coupled with CCUS according to claim 1, characterized in that The specific steps of S6 include: Load the tertiary ore dissolution slag into a reactor and add CO2 to the reactor to convert the calcium carbonate in the tertiary ore dissolution slag into calcium bicarbonate and dissolve it in the solution; Extra H2O2 is added to the tertiary ore-dissolving reaction solution to convert divalent iron into magnetite, increasing the magnetism of the iron ore phase; The quaternary ore-dissolving slag is separated from the calcium bicarbonate solution by solid-liquid separation; The calcium bicarbonate solution is heated to decompose calcium bicarbonate to obtain calcium carbonate and recover the released CO2; The calcium carbonate is separated from the liquid phase by solid-liquid separation; The calcium carbonate is dried to obtain a calcium carbonate product.

6. The method for the step-by-step resource utilization of steel slag coupled with CCUS according to claim 1, wherein, The specific steps of step S7 include: The quaternary ore-dissolving slag is added to a gravity separation device for separation according to specific gravity to obtain high-density iron ore and low-density tailing slag; The iron ore is passed through a magnetic separator to select high-quality iron ore with an iron content of more than 50% and low-quality iron ore with an iron content of 40%-50% according to magnetism.

7. An apparatus for the cascaded resource utilization of steel slag coupled with CCUS, characterized in that It includes: A primary ore-dissolving unit, which is connected to the liquid phase outlet of the secondary ore-dissolving unit and obtains primary ore-dissolving slag and ore-dissolving solution; A mineralization reaction unit, which is connected to the liquid phase outlet of the primary ore-dissolving unit and the ammonia recovery storage tank; A secondary ore-dissolving unit, which is connected to the solid phase outlet of the primary ore-dissolving unit and the liquid phase outlet of the mineralization unit; A tertiary ore-dissolving unit, which is connected to the solid phase outlet of the secondary ore-dissolving unit; A silica unit, which is connected to the liquid phase outlet of the tertiary ore-dissolving unit; A quaternary ore-dissolving unit, which is connected to the solid phase outlet of the tertiary ore-dissolving unit; A gravity separation and magnetic separation unit, which is connected to the solid phase outlet of the quaternary ore-dissolving unit.

8. The device for the stepped resource utilization of steel slag coupled with CCUS according to claim 7, characterized in that, The primary ore-dissolving unit includes: A primary ore-dissolving pulping kettle, whose liquid phase inlet is connected to the liquid phase outlet of the secondary ore-dissolving unit, and the steel slag is added to the primary ore-dissolving pulping kettle through a solid feeding port; A primary ore-dissolving reactor, which is connected to the bottom of the primary ore-dissolving pulping kettle, and a steam heat exchange coil is installed in the reaction kettle; An ammonia absorption tower, whose bottom is connected to the gas outlet of the primary ore-dissolving reactor; A primary ore-dissolving slag thickening kettle, whose top is connected to the bottom of the primary ore-dissolving reactor; A primary ore-dissolving slag plate and frame filter, which is connected to the bottom of the thickening kettle, and its liquid phase outlet is merged with the supernatant of the primary ore-dissolving slag thickening kettle and sent to the mineralization unit; A heat exchanger, which is connected to the liquid phase outlet of the primary ore-dissolving slag plate and frame filter, and circulating cooling water is introduced into the shell layer; The mineralization reaction unit includes: A mineralization reactor, which is connected to the liquid phase outlet of the primary ore-dissolving unit, is connected to the ammonia recovery tanks of the primary ore-dissolving unit and the secondary ore-dissolving unit, and industrial tail gas is introduced into the reactor from the bottom through a distributor; A mineralization reaction liquid thickening kettle, whose top is connected to the liquid phase outlet of the mineralization reactor; A mineralization reaction liquid plate and frame filter, whose inlet is connected to the bottom of the calcium carbonate thickening kettle, and its liquid phase outlet is merged with the supernatant outlet of the calcium carbonate thickening kettle and sent to the secondary ore-dissolving unit; The secondary ore-dissolving unit includes: A secondary ore-dissolving pulping kettle, the primary ore-dissolving slag is added to the secondary ore-dissolving pulping kettle through solid feeding, and its top is connected to the shell layer outlet of the heat exchanger; A secondary ore-dissolving reactor, which is connected to the bottom of the secondary ore-dissolving pulping kettle, and a steam heat exchange coil is installed in the reactor; A condenser, which is connected to the gas phase outlet at the top of the secondary ore-dissolving reactor; A secondary ore-dissolving slag thickening kettle, whose top is connected to the bottom of the secondary ore-dissolving reactor; A secondary ore-dissolving slag plate and frame filter, which is connected to the bottom of the thickening kettle; The tertiary ore-dissolving unit includes: A tertiary ore-dissolving pulping kettle, and the secondary ore-dissolving slag is added to the tertiary ore-dissolving pulping kettle through a solid feeding port; An alkali hydrolysis reactor, which is connected to the bottom of the three-stage ore dissolution and pulping kettle, and a steam-water heat exchange coil is installed inside the alkali hydrolysis reactor; A three-stage ore dissolution slag thickening kettle, the top of which is connected to the bottom of the alkali hydrolysis reactor; A three-stage ore dissolution slag plate and frame filter, which is connected to the bottom outlet of the three-stage ore dissolution slag thickening kettle.

9. The device for coupling CCUS with the step-by-step resource utilization of steel slag according to claim 7, wherein The silica unit includes: A carbonation reactor, which is connected to the liquid phase outlet of the three-stage ore dissolution unit, and CO2 is introduced into the carbonation reactor through a gas distributor at the bottom of the reactor; A centrifuge, which is connected to the outlet of the carbonation reactor; An alkali solution regeneration reactor, which is connected to the liquid phase outlet of the centrifuge, and calcium hydroxide is added through the solid feeding port of the strong alkali regeneration reactor; A circulating alkali solution thickening kettle, the top of which is connected to the bottom of the alkali solution regeneration reactor; A circulating alkali solution plate and frame filter, which is connected to the bottom of the alkali regeneration thickening kettle; The four-stage ore dissolution unit includes: A CO2 compressor, which is used to pressurize the CO2 gas; A pressure ore dissolution reaction kettle, the three-stage ore dissolution slag is added into the reaction kettle through the solid inlet of the pressure ore dissolution reaction kettle, the hydrogen peroxide solution is introduced through the liquid phase inlet at the upper end of the reaction kettle, and CO2 is introduced through the gas inlet at the upper end of the reaction kettle; A filter press, which is connected to the bottom outlet of the pressure ore dissolution reaction kettle and is equipped with a high-pressure gas inlet and recovery pipeline; A calcium bicarbonate decomposition reaction kettle, which is connected to the liquid phase outlet of the filter press and is equipped with a CO2 recovery pipeline. A steam-water heat exchange coil is installed inside the calcium bicarbonate decomposition reactor, and saturated lime water is added through the liquid feeding port at the upper end of the calcium bicarbonate decomposition reaction kettle; A decomposition liquid plate and frame filter, which is connected to the bottom outlet of the calcium bicarbonate decomposition reaction kettle.

10. The device for coupling CCUS with the step-by-step resource utilization of steel slag according to claim 7, wherein The gravity separation and magnetic separation unit includes: A gravity separation device, which is connected to the solid phase outlet of the filter press through a conveyor belt; A magnetic separator, which is connected to the iron ore suspension outlet of the gravity separation device; An iron ore thickening kettle, the top of which is connected to the liquid phase outlet of the magnetic separator; An iron ore plate and frame filter press, which is connected to the bottom outlet of the iron ore thickening kettle.

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