A high-efficiency iron smelting method based on magnetic separation pretreatment of copper slag

Abstract

The present application relates to steel and non-ferrous smelting slag comprehensive recovery and iron-making resource utilization comprehensive utilization technical field, disclose a kind of copper slag efficient iron-making method based on magnetic separation pretreatment, comprising: to molten iron-silicate base waste slag input by calcium carbide, sodium fluoride and phosphorus component consisting of conditioning agent, using sodium fluoride to build liquid diffusion field exposure reduction interface, induce calcium carbide and iron silicate in situ reduction to generate metal iron core;Heat treatment promotes iron core polymerization growth;Gradient cooling, using phosphorus component induces silicate matrix crystal transformation to generate expansion stress and break matrix;Grinding powder and weak magnetic separation, extract magnetic enrichment product, the present application breaks iron-oxygen-silicon chemical bond, realizes the conversion of combined state iron to independent metal state, achieves iron and gangue phase decoupling, using endogenous stress induction self-pulverization, reduce grinding energy consumption, output high-grade iron powder and simultaneously remove sulfur zinc impurities.

Description

Technical Field

[0001] This invention relates to an efficient ironmaking method for copper slag based on magnetic separation pretreatment, belonging to the technical field of comprehensive recycling and resource utilization of waste slag from iron and steel and non-ferrous smelting. Background Technology

[0002] The current mainstream technology uses direct magnetic separation after crushing to extract magnetic minerals from the slag and recover ferrite. During the cooling process of copper slag, crystallization occurs, and the iron element exists in the form of silicate minerals such as fir olivine. These minerals are weakly magnetic and are finely embedded with silicate gangue. Conventional crushing only reduces the physical particle size and makes it difficult to decouple the ferrite from the silicate lattice phase.

[0003] To obtain high-grade iron concentrate, ultrafine grinding consumes a lot of energy, and excessively fine powder results in dust loss during furnace smelting, creating a contradiction between utilization rate and processing cost. The technical bottleneck stems from passively adapting to the physical properties of copper slag rather than actively intervening. For example, Chinese invention patent CN109621276A discloses a method for treating arsenic in non-ferrous smelting waste acid from iron-rich copper slag. This technology utilizes the high iron content of copper slag to remove arsenic, achieving waste-to-waste treatment. The core relies on pre-grinding the copper slag to a particle size below 0.075mm to increase the specific surface area and maintain the arsenic removal reaction activity. This is based on external mechanical energy input and atmospheric pressure stirring. The mixing process does not change the state of ferrite in the silicate system. Subsequent solid-liquid separation still relies on conventional magnetic separation. It does not break the chemical bond energy of fir olivine at the atomic scale. Ferrite is in a submicron embedded state. The recycling process faces high grinding resistance and cannot achieve directional migration and coarse aggregation of ferrite. The industry has tried to increase the grinding depth to improve the dissociation rate. However, due to the chemical bond energy of fir olivine, physical crushing is difficult to change the chemical morphology of ferrite. The mechanical energy input benefits decrease with decreasing particle size. Controlled cooling is limited by melt viscosity and is difficult to drive iron atoms to migrate across phases and aggregate into nuclei, making it difficult to break the state of ferrite encapsulation in the silicate system.

[0004] Therefore, the technical problem to be solved by this invention is how to address the issues of high energy consumption and low efficiency caused by the high stability of ferrite phases and the small particle size of precipitates, by using waste heat to trigger in-situ reduction reactions to induce phase reconstruction and polymerization growth, thereby relaxing the requirements for crushed particle size while ensuring the grade of iron concentrate, so that it meets the raw material standards for blast furnaces or electric furnaces in steel enterprises, and realizing the cross-industry resource utilization and synergistic deep comprehensive utilization of steel smelting waste slag and non-ferrous smelting slag. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A method for efficient ironmaking from copper slag based on magnetic separation pretreatment, comprising the following steps: Step 101: Obtain molten iron-containing silicate-based smelting waste slag at a temperature of 1250℃ to 1350℃; Step 102: A conditioning agent consisting of granular calcium carbide, sodium fluoride as an interfacial activity inducer, and a phosphorus-containing component as a phase change inducer is added to the iron-containing silicate-based smelting waste slag, and turbulent mixing is carried out using slag falling; wherein, sodium fluoride reduces the local viscosity of the primary silicate formed on the surface of the granular calcium carbide and constructs a dynamic liquid phase diffusion field migrating to the outside of the particles based on the surface tension gradient of the iron-containing silicate-based smelting waste slag melt, so as to expose the reduction reaction interface between the granular calcium carbide and the iron-containing silicate-based smelting waste slag melt; Step 103: The reduction reaction interface is used to induce an in-situ reduction reaction between granular calcium carbide and the iron silicate phase in the iron silicate-based smelting waste slag, so as to generate a metallic iron core and transform the iron silicate phase into a non-magnetic silicate matrix. Step 104: The iron-containing silicate-based smelting waste slag after the reaction is subjected to a heat treatment at 1100℃ to 1250℃ for 20 minutes to 60 minutes to construct a magnetic phase by polymer growth of metallic iron cores. Step 105 involves performing gradient cooling on the iron-containing silicate-based smelting waste slag after heat preservation, and using phosphorus-containing components to induce dicalcium silicate in the non-magnetic silicate matrix to undergo oxidation. Orientation The crystal form transformation of the type generates volume expansion shear stress to break the nonmagnetic silicate matrix; Step 106: Physically grind the crushed iron-containing silicate-based smelting waste slag to control the average particle size of the selected powder to be 150 micrometers to 250 micrometers. Step 107: Use a weak magnetic separation process with a magnetic field strength of 0.15T to 0.3T to perform magnetic separation on the powder to be selected and extract the magnetic enriched product.

[0006] Preferably, in step 102, the amount of sodium fluoride added is 0.3% to 0.8% of the mass of the iron silicate-based smelting waste slag; sodium fluoride is used to construct a superfluid film composed of low-melting-point primary silicates on the surface of granular calcium carbide, and the primary silicates are driven to diffuse into the melt body of the iron silicate-based smelting waste slag by the surface tension gradient, so as to peel off the solid product coating layer on the surface of granular calcium carbide, thereby maintaining the active reaction area of ​​the reduction reaction interface.

[0007] Preferably, the phosphorus-containing component is phosphate rock powder or phosphate slag; in step 105, the phosphorus-containing component is used to adjust the crystal stability region of dicalcium silicate, so that the non-magnetic silicate matrix undergoes endogenous stress cracking caused by volume expansion shear stress when cooled to below 500°C, so as to generate annular microcracks at the junction of the metallic iron core and the non-magnetic silicate matrix.

[0008] Preferably, the conditioning agent also includes anhydrous calcium sulfate as an embrittlement inducer, wherein the amount of anhydrous calcium sulfate added is 0.5% to 1.2% of the mass of the iron silicate-based smelting waste slag; at the end of the reduction reaction in step 103, the anhydrous calcium sulfate reacts with the granular calcium carbide to react with the residual carbon to carry out a redox reaction, so as to release sulfur dioxide and carbon dioxide microbubbles in situ before the iron silicate-based smelting waste slag melt solidifies.

[0009] Preferably, the conditioning agent also includes a sulfur-fixing agent, which is alumina or aluminum-containing aluminum ash; the sulfur-fixing agent reacts with the alkaline components in the iron-containing silicate-based smelting waste to generate calcium aluminate microcrystals with sulfur capacity, so as to capture sulfur elements in situ during the precipitation stage of metallic iron nuclei and solidify them into calcium sulfoaluminate phase, thereby blocking the enrichment of sulfur elements into magnetic phases.

[0010] Preferably, the average particle size of the granular calcium carbide is 2 mm to 5 mm; in step 102, the heat of chemical reaction released by the strong exothermic reaction of the granular calcium carbide in the molten iron silicate-based smelting waste slag is used to construct a local high-temperature reduction microzone, so as to reduce the zinc oxide in the iron silicate-based smelting waste slag and convert it into zinc vapor.

[0011] Preferably, the amount of conditioning agent added is 1.5% to 4.0% of the mass of iron-containing silicate-based smelting waste slag; in step 104, the polymerization rate of the magnetic phase is adjusted according to the Ostwald ripening model, which follows the following rules: ,in, For heat preservation treatment Average grain radius after time, The initial average grain radius, This refers to the interfacial tension between the magnetic phase and the non-magnetic silicate matrix. The diffusion coefficient of iron atoms in iron-containing silicate-based smelting waste slag. Let be the molar volume of iron. This represents the equilibrium solubility of the magnetic phase in a non-magnetic silicate matrix. The gas constant is... The temperature is the thermodynamic temperature for heat preservation treatment.

[0012] Preferably, in step 106, the iron-containing silicate-based smelting waste slag after shear stress crushing is fed into a ball mill and subjected to coarse grinding for 10 to 20 minutes without the addition of grinding aids, so as to achieve the separation of the metallic iron core from the non-magnetic silicate matrix by using the interfacial cracks generated by the volume expansion shear stress.

[0013] Preferably, step 107 employs a two-stage weak magnetic separation process. The magnetic field strength of the first-stage magnetic separation is 0.3T, used to extract coarse and fine powder containing gangue. The magnetic field strength of the second-stage magnetic separation is 0.15T, used to refine the coarse and fine powder to obtain iron-rich magnetic fine powder with a total iron content of not less than 90%.

[0014] Preferably, in step 105, the cooling rate of the gradient cooling is controlled at 10°C per minute to 30°C per minute, so that the non-magnetic silicate matrix generates shear stress sufficient to overcome the fracture toughness of the non-magnetic silicate matrix when passing through the crystal transformation temperature range, thereby achieving the self-pulverization state of the iron-containing silicate-based smelting waste slag.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In the comprehensive utilization of slag from iron and steel and non-ferrous smelting and the efficient ironmaking of copper slag, the reducing and alkaline properties of calcium carbide in high-temperature molten copper slag induce the breaking of ferro-silicon chemical bonds at the atomic scale, driving the transformation of iron from chemically bound ferrosilicon to physically independent metallic iron. The phase reconstruction mechanism releases ferrite from the long-chain silicate network in copper slag, and simultaneously transforms the residual silicate matrix into non-magnetic calcium iron garnet or dicalcium silicate phase. The phase decoupling mechanism changes the dependence of the magnetic separation process on the degree of mineral dissociation, achieving the separation of ferrite and gangue at a relatively coarse crushing particle size. This provides high-quality, low-impurity ironmaking raw materials for iron and steel enterprises, and constructs a closed loop for the comprehensive utilization of multi-element smelting slag through chemical purification and phase reconstruction in iron and steel smelting processes.

[0016] 2. During the melting and tempering stage, a migration aid is introduced to construct an unsteady, low-viscosity diffusion channel within the slag, overcoming the hindering effect of high-viscosity silicate melt on atomic migration. In the heat preservation and induction stage, the low-viscosity liquid phase environment, combined with the exothermic chemical reaction within the system, drives the directional migration and aggregation of micron-sized metallic iron nuclei, achieving coarsening of iron grains. The system's dynamics promote grain growth, resulting in metallic iron with clear phase boundaries, reducing the energy density requirements of subsequent crushing processes, and avoiding resource loss due to over-grinding.

[0017] 3. The tempering component integrates phase transformation inducers or embrittlement agents, utilizing the volume effect of crystal transformation or the difference in thermal expansion coefficient during the cooling process of the silicate matrix. Microscopic shear stress cracks are pre-set at the interface between metallic iron grains and slag phase, transforming forced mechanical crushing into spontaneous pulverization and interface dissociation based on endogenous stress. The crushing force preferentially extends along the pre-set interface cracks, and the peeling dissociation produces iron concentrate powder with a clean surface and low gangue encapsulation. This achieves deep coupling between high-grade iron concentrate extraction and low-energy crushing operation, enhances the engineering applicability of copper slag as a high-value ironmaking raw material for steel enterprises, and achieves the synergistic and in-depth comprehensive utilization of various smelting wastes in steel enterprises and non-ferrous smelting industries. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the entire process of the efficient ironmaking method for copper slag based on magnetic separation pretreatment according to the present invention; Figure 2 This is a bar chart comparing the iron concentrate grade and recovery rate under different conditioning conditions according to the present invention. Figure 3 This is a schematic diagram of the functional modules and logical relationships of the copper slag phase reconstruction and decoupling system of the present invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are intended to explain and illustrate the present invention, rather than to limit the scope of protection of the present invention.

[0020] This invention provides a high-efficiency ironmaking method for copper slag based on magnetic separation pretreatment. A conditioning agent composed of granular calcium carbide, sodium fluoride as an interfacial activity inducer, and a phosphorus-containing component as a phase change inducer is added to molten iron-containing silicate-based smelting waste slag. The residual heat of the waste slag triggers an in-situ reduction reaction and directional phase reconstruction. This process demonstrates the active control and resource regeneration of the chemical structure of iron-containing silicate-based waste slag by steel enterprises. The method uses sodium fluoride to adjust the viscosity of the particle interface, constructs a liquid-phase diffusion field to expose the reduction interface, drives the transformation of iron elements from a chemically bound state to a metallic state, and promotes the polymerization and growth of metallic iron nuclei during the heat preservation process. Finally, the crystal transformation stress during the matrix cooling process achieves self-powdering and dissociation of the slag. The temperature is [temperature value missing]. ℃ to Molten iron-containing silicate-based smelting waste slag at ℃ is mixed with a conditioning agent by adding the agent and utilizing the turbulence generated during the slag discharge process. The conditioning agent contains granular calcium carbide, sodium fluoride, and phosphorus-containing components. The total amount of conditioning agent added is controlled within a certain percentage of the mass of the iron-containing silicate-based smelting waste slag. to The amount of sodium fluoride added to the conditioning agent is equal to the mass of the iron-containing silicate-based smelting waste slag. to At the reaction interface, sodium fluoride reduces the local viscosity of the primary silicates formed on the surface of particulate calcium carbide. Utilizing the surface tension gradient of the melt, a dynamic liquid-phase diffusion field migrating outwards from the particles is constructed. This diffusion field, composed of low-melting-point primary silicates, forms a micrometer-thick superfluid film. The interfacial tension drives the primary silicates to diffuse into the melt bulk, stripping away the solid product coating layer on the surface of the particulate calcium carbide and maintaining the active reaction contact area between the particulate calcium carbide and the waste melt. During this dynamic evolution, sodium fluoride dissolves on the surface of the particulate calcium carbide and significantly reduces the kinetic viscosity of the local liquid phase, thereby reducing the shear resistance in the reaction micro-region. The viscosity is reduced by more than two orders of magnitude, thus forming a low-viscosity liquid window on the particle surface. At the same time, the enrichment of fluoride ions at the interface leads to a local reduction in interfacial tension, generating an extremely high tension gradient between the fluoride and the melt mass far from the particle. The tangential stress formed by this gradient overcomes the viscous resistance at the microscale, driving the nascent silicate film rich in reaction products to migrate outward along the particle surface. This microscopic convection mechanism induced by the chemical potential gradient continuously carries the newly formed solid calcium silicate microcrystals away from the reaction interface, ensuring that calcium carbide is always in direct contact with the iron-containing silicate melt, thereby achieving microscopic self-cleaning of the reaction interface under a macroscopic high viscosity background.

[0021] The exposed reduction reaction interface induces an in-situ reduction reaction between granular calcium carbide and ferrosilicate phases such as fir olivine in the waste residue, reducing bound ferrite to metallic iron nuclei. Simultaneously, the remaining components are transformed into non-magnetic silicate matrices such as dicalcium silicate or andradite. To address the challenge of magnetic separation of the precipitated metallic iron nuclei due to their small particle size, the waste residue after the reaction is subjected to... ℃ to The insulation treatment was carried out at ℃ for a period of time. minutes to Within this quasi-equilibrium temperature range, a magnetic phase was constructed using the directional migration and polymerization growth of metallic iron cores. The polymerization rate of the magnetic phase was adjusted according to the Ostwald ripening model, the expression of which is as follows: ,in, For heat preservation treatment Average grain radius after time, in units of ; The initial average grain radius, in units of ; The interfacial tension between the magnetic phase and the non-magnetic silicate matrix, in units of... ; The diffusion coefficient of iron atoms in the waste residue is given by . ; This is the molar volume of iron, in units of... ; The equilibrium solubility of the magnetic phase in a nonmagnetic silicate matrix, in units of ; Let be the gas constant, and take its numerical value as . ; The thermodynamic temperature of the insulation treatment, in units of . ; The insulation time is expressed in units of 1. Establish the iron atom diffusion coefficient based on high-temperature rotational viscosity gradient experimental calibration. With thermodynamic temperature The dynamic mapping library is constructed following an engineering-modified model of the Stokes-Einstein relation, i.e., the diffusion coefficient. With melt kinetic viscosity The diffusion coefficients exhibit an inverse relationship. In preliminary experiments, the macroscopic viscosity of copper slag melt under different temperature gradients was measured using a rotational viscometer. Simultaneously, the mean free path and transition frequency of iron atoms under corresponding operating conditions were calibrated using the tracer atom method, thereby determining the proportional correction coefficient for a specific slag system. In actual operation, by monitoring the real-time viscosity of the melt, the current diffusion coefficient can be retrieved from the mapping library and interpolated. This provides real-time physical input parameters for the dynamic solution of the aging model; high-temperature visual sensors embedded in the lining of the slag discharge bag capture real-time images of the metal iron core evolution, and the measured temperature is then incorporated into the Ostwald aging model. Solving for instantaneous grain radius ,like The magnetic separation capture threshold was not reached. Triggering the deceleration command of the slag-carrying electric flatcar extends the isothermal duration. Synchronous closed-loop regulation of the insulation cover opening degree to maintain temperature difference fluctuation below Within this range, the migration of iron atoms across phase boundaries is driven, completing the kinetic control loop of ferrite precipitation from the silicate matrix to its physical coarsening growth. During real-time image capture, the vision sensor works in conjunction with a narrow-band infrared filter, utilizing the significant difference in emissivity between the metallic iron core and the silicate matrix in the temperature range of 1100℃ to 1250℃ to filter out background noise generated by thermal radiation from the slag surface and identify the metallic precipitates on the liquid surface as high-brightness pixel feature points. In specific operation, the vision processing system performs median filtering on the captured grayscale image to eliminate the interference of microbubble shadows generated by the reduction reaction. Subsequently, an adaptive threshold segmentation algorithm is used to extract the contour boundary of the iron core, calculate the equivalent pixel area of ​​a single connected region, and combine the sensor's preset magnification and object distance parameters to calculate the projected area of ​​the iron core through spatial geometric mapping relationship. Then, based on the spherical assumption model, the instantaneous average grain radius R is obtained through inversion.

[0022] Gradient cooling is applied to the insulated waste residue, with the cooling rate controlled at [temperature range]. ℃ per minute to At a temperature of ℃ per minute, the phosphorus-containing component in the conditioning agent is used to adjust the crystal stability region of dicalcium silicate in the non-magnetic silicate matrix. The phosphorus-containing component is selected from phosphate rock powder, and its content is adjusted according to the silica content in the slag. The waste slag is cooled to ℃. During processes below ℃, phosphorus-containing components induce dicalcium silicate to undergo oxidation. Orientation A crystal form transformation of type 1 produces approximately to The volume expansion generates multiaxial shear stress and induces annular microcracks at the interface between the metallic iron core and the nonmagnetic silicate matrix, triggering self-pulverization and dissociation of the waste residue. The pulverized waste residue is then physically ground, and the grinding time is controlled to maintain the average particle size of the selected powder within a certain range. micrometers to Micrometers, utilizing pre-existing interfacial cracks to achieve the separation of the metallic iron core from the substrate, using a magnetic field strength of to A two-stage weak magnetic separation process is used to extract magnetically enriched products from the powder to be processed. The first stage of magnetic separation adopts... The magnetic field strength is used to extract coarse and fine powder containing gangue, and the second stage of magnetic separation is adopted. The magnetic field strength is used for the fine selection of coarse and fine powders, ultimately obtaining a total iron grade greater than or equal to The iron-rich magnetic powder; the conditioner also contains alumina and particles with a diameter of [missing information]. millimeters to Millimeter-sized granular calcium carbide, with alumina as a sulfur-fixing agent, reacts with the alkaline components in the waste slag to generate calcium aluminate microcrystals with sulfur capacity. During the iron nucleus precipitation stage, sulfur is captured in situ and solidified into calcium sulfoaluminate phase, preventing sulfur from enriching into magnetic phases. The granular calcium carbide undergoes a strong exothermic reaction in the waste slag melt, and the released reaction heat constructs a local high-temperature reduction microzone inside the slag, inducing the reduction of zinc oxide in the waste slag and its conversion into zinc vapor for removal.

[0023] Example 1: When processing wastewater discharged from a non-ferrous smelting furnace at a temperature of... ℃ and the mass fraction of silicon dioxide is higher than In the specific working conditions of molten iron-containing silicate-based smelting waste slag, because the molten iron-containing silicate-based smelting waste slag exhibits a state of... to The kinetic viscosity of the region, the solid reducing agent is instantly coated by the primary calcium silicate solid phase layer generated on the surface of the melt and forms a material diffusion barrier. Under this condition, the metallic iron nuclei in the slag after natural cooling are highly dispersed in the silicate matrix at the submicron scale, which makes the subsequent physical separation process require huge grinding energy consumption and makes it difficult to achieve physical desorption of magnetic phases from gangue. In order to cope with the material exchange bottleneck caused by the closed reduction interface, a certain percentage of the slag mass is added to the molten iron-containing silicate-based smelting waste slag. granular calcium carbide, and its slag mass Sodium fluoride, acting as an interfacial activity inducer, reduces the local viscosity of primary silicates formed on the surface of granular calcium carbide. Based on the interfacial tension gradient generated by local temperature differences within the melt, a dynamic liquid-phase diffusion field migrating outwards from the particles is constructed. This self-cleaning mechanism continuously strips away reaction residues and exposes the active reduction interface, allowing the granular calcium carbide to convert ferrite in the slag into metallic iron cores in situ. Simultaneously, a non-magnetic silicate matrix containing dicalcium silicate is generated. Addressing the challenge of recovering the generated fine metallic iron cores through physical means, the iron-containing silicate-based smelting waste slag after the reaction is treated... Isothermal treatment at ℃, by extending the holding time to Minutes were used to construct a magnetic phase through the polymerization growth of metallic iron cores in a quasi-equilibrium state. The evolution of its grain radius followed the following rules: ,in, For heat preservation treatment Average grain radius after time, in units of ; The initial average grain radius, in units of ; The interfacial tension between the magnetic phase and the non-magnetic silicate matrix, in units of... ; This is the iron atom diffusion coefficient, in units of... ; This is the molar volume of iron, in units of... ; The equilibrium solubility of the magnetic phase in a nonmagnetic silicate matrix, in units of ; Let be the gas constant, and take the value of . ; Thermodynamic temperature, unit: ; The duration of heat preservation is expressed in units of... This process achieves coarsening growth of ferrite by driving the migration of iron atoms across phase boundaries.

[0024] During the cooling stage, the phosphorus-containing component introduced into the conditioning agent as a phase change inducer is used to adjust the crystal stability region of dicalcium silicate in the non-magnetic silicate matrix, thereby controlling the waste residue to... The cooling rate decreased to ℃ per minute. Below ℃, dicalcium silicate is triggered to... Orientation Crystal transformation of type and production The volume expansion caused by this crystal transformation induces annular microcracks at the interface between the metallic iron core and the non-magnetic silicate matrix, leading to spontaneous pulverization of the non-magnetic silicate matrix. Finally, a two-stage weak magnetic separation process is applied to the pulverized material at a separation field strength of [insert value here]. to Under the action of extraction, the total iron grade obtained is The process for producing iron-rich magnetic concentrate utilizes the residual heat from waste residue to break chemical bonds, while simultaneously addressing the conflict between grinding energy consumption and concentrate grade through directional control of physical properties.

[0025] Example 2: In processing a substance containing a total iron mass fraction of And the mass fraction of silicon dioxide is In a verification test scenario involving industrial molten copper slag, to quantify the correlation between the sodium fluoride-induced interfacial self-cleaning mechanism and the phosphorus-containing component-driven crystal transformation stress in improving ferrite recovery and reducing grinding energy consumption, the experimental data were collected by a simulation platform equipped with online monitoring of high-temperature rotational viscosity and cooling stress analysis capabilities. This platform features temperature control accuracy superior to [previous standard]. A high-temperature tubular resistance furnace at ℃ was used, and a signal-to-noise ratio of ℃ was superimposed during the test signal acquisition stage. Background thermal noise is used to characterize the signal features under actual smelting conditions; the amount of sodium fluoride added is set based on the interfacial liquid phase diffusion rate and the melt surface tension gradient, forming a technical trade-off in performance. When the initial kinetic viscosity of the iron-containing silicate-based smelting waste slag is at... to In the specified range, to ensure that the primary silicate formed by the reaction of sodium fluoride with particulate calcium carbide exhibits superfluid characteristics, the value of sodium fluoride is determined according to a logic that is negatively correlated with the acidity coefficient of the slag. In this experiment... Under a constant temperature environment of ℃, the baseline addition amount of sodium fluoride was set as [amount] of the iron-containing silicate-based smelting waste slag. The experiment confirmed the performance inflection point by setting different group ratio gradients and a control group exceeding the specified range. The control group was operating under normal reduction conditions without the addition of conditioning agents. Compared with the control group The control group represents out-of-range operating conditions where the sodium fluoride addition is below the lower limit and above the upper limit, respectively. The control group was missing phosphorus-containing components. The experimental group was the control group. To the experimental group Within the required protection range, parameter gradient settings are performed. Table 1 shows the comparison of key intermediate data and final performance indicators for each group under the same reduction time and heat preservation regime.

[0026] Table 1: Comparison of Phase Behavior and Magnetic Separation Effect under Different Tempering and Conditioning Composition Ratios

[0027] Analysis table The data shows that when the amount of sodium fluoride added is from Increase to At that time, the interfacial viscosity changed from Sharply down to The effective percentage of the restored interface subsequently decreased. Upgraded to This study confirmed that sodium fluoride removes the solid coating layer by reducing the viscosity of the primary silicate on the particle surface, thereby improving the contact conditions of the reduction reaction and driving the transformation of the metallic iron nuclei from a dispersed state to coarser grains with physical magnetic separation conditions; the control group was observed. It can be seen that when the amount of sodium fluoride added exceeds Subsequently, the optimization range of interfacial viscosity and recovery rate tended to plateau, indicating that the system's interfacial self-cleaning efficiency had entered the saturation region, and further increasing the component dosage would not produce commensurate engineering benefits; in the self-pulverization performance verification, the control group In the absence of phosphorus-containing components, the self-pulverization rate is only [missing information]. The overall iron content is limited by the adhesion to the matrix and is difficult to achieve. The above, and the experimental group The formation of dicalcium silicate induced by phosphorus-containing components is achieved by... Orientation The crystal form transformation generates shear stress sufficient to overcome the fracture toughness of the matrix, enabling the self-pulverization rate to reach [a certain level]. This reduces the damping of subsequent physical grinding; grain growth experiments during the heat preservation stage further confirm that, The observed grain radius change trend after prolonged holding time at ℃ conforms to the following Ostwald ripening model: ,in, For heat preservation treatment Average grain radius after time, in units of ; The initial average grain radius, in units of ; The interfacial tension between the magnetic phase and the non-magnetic silicate matrix, in units of... ; This is the iron atom diffusion coefficient, in units of... ; This is the molar volume of iron, in units of... ; The equilibrium solubility of the magnetic phase in a nonmagnetic silicate matrix, in units of ; Let be the gas constant, and take the value of . ; Thermodynamic temperature, unit: Experimental data show that its final average particle size crosses the effective capture threshold of physical magnetic separation.

[0028] Example 3: This example combines Figures 1 to 3 This paper describes an efficient ironmaking method for copper slag based on magnetic separation pretreatment, as follows: Figure 1 As shown, a multi-component conditioning agent consisting of granular calcium carbide, sodium fluoride, and phosphorus-containing components was added to molten iron-containing silicate-based smelting slag at a temperature of 1250℃ to 1350℃. This process initiated a reduction interface construction stage, where sodium fluoride was used to construct a liquid-phase diffusion field and reduce viscosity to expose the reduction interface, thereby triggering an in-situ reduction reaction to generate metallic iron nuclei and transform them into a non-magnetic silicate matrix. Following the reaction, a heat-holding polymerization treatment at 1100℃ to 1250℃ for 20 to 60 minutes was performed to promote the polymerization and growth of the metallic iron nuclei. Gradient cooling and phase transformation steps were then carried out, where phosphorus-containing components induced a crystal transformation and generated expansion stress to break the matrix. Physical grinding was performed on the broken material to control the particle size between 150 μm and 250 μm and to assist in phase dissociation. Finally, a weak magnetic separation process with a magnetic field strength of 0.15T to 0.3T was used to extract and enrich the product, ultimately obtaining a magnetically enriched product in the form of high-grade iron concentrate.

[0029] like Figure 2 As shown, the horizontal axis represents multiple experimental groups, including control group 1, control group 2, experimental group 1, experimental group 2, experimental group 3, control group 3, and control group 4. The vertical axis represents percentage values. The legend distinguishes between two data dimensions: total iron content of concentrate (%) and concentrate recovery rate (%). The bar heights of experimental groups 1 to 3 are higher than those of control groups 1 and 4 in both indicators. Figure 3 As shown, the system centers on the phase reconstruction and decoupling of copper slag to achieve the transformation of bound iron to metallic state. It receives high-temperature molten copper slag with an initial temperature of 1250℃ to 1350℃ as input. The interface activity induction module, connected by the slag turbulence mixing effect, is responsible for the dynamic batching of sodium fluoride and calcium carbide and the construction of a liquid phase diffusion field to peel off the solid layer. At the same time, it is connected to the ripening growth monitoring module through thermodynamic temperature control feedback, which controls the iron core polymerization rate and grain size based on the Ostwald model. Below, there is an endogenous stress induction module connected by the cooling phase transformation driving effect, which is used to adjust the phosphorus-containing components to achieve crystal transformation and generate volume expansion shear stress self-pulverization. There is also a multi-stage magnetic separation module connected by the magnetic phase extraction effect, which performs two-stage weak magnetic gradient separation to extract fine powder with a total iron content of not less than 90%, and finally outputs high-grade iron concentrate with a total iron content of ≥90%.

[0030] Example 4: In the treatment of binary alkalinity Below And the mass fraction of silicon dioxide is higher than In the calibration scenario of high-silica molten copper slag, since the lattice energy of fir olivine in the slag system increases with decreasing basicity, a single dose of conditioning agent is insufficient to induce sufficient crystal transformation stress in the non-magnetic silicate matrix. Therefore, before adding the conditioning agent, the composition of the iron silicate-based smelting waste slag is monitored online, and the dynamic compensation amount of phosphorus-containing components is determined based on the mass ratio of calcium oxide to silicon dioxide in the slag. Dynamic compensation amount The calculation follows these rules: ,in, This represents the mass fraction of the phosphorus-containing component, in units of... ; This is the alkalinity compensation coefficient, with a value of [value missing]. ; To measure the binary basicity, i.e., the mass ratio of calcium oxide to silicon dioxide; this method increases the solid solution concentration of phosphorus in the non-magnetic silicate matrix, allowing dicalcium silicate to react upon cooling to... The phase transition expansion force generated at ℃ reaches the matrix dissociation threshold; the measured binary alkalinity is based on feedback from the online X-ray fluorescence analyzer. Automatically corrects the feeding screw speed and adjusts the phosphorus ore powder content. Solid solution concentration anchors the chemical driving force of crystal transformation. exist to During automatic correction, the control system will calculate the resulting dynamic compensation amount within the specified range. The target setpoint is input to the programmable logic controller (PLC). Based on the calibration characteristic curve of the screw feeder configured with the conditioning agent spray gun, i.e., the feed mass flow rate per unit speed, the output frequency of the inverter is adjusted in real time. If the actual measured binary alkalinity is... Reduced to the required If the flow rate increases, the controller linearly increases the motor speed to ensure that the phosphorus-containing component flow rate per unit mass of waste residue in the turbulent mixing zone is consistent with the flow rate of the waste residue. The command values ​​are absolutely matched to maintain a stable instantaneous phosphorus concentration in the melt; the slag cooling curve is acquired in real time and the fan opening is linearly adjusted. Anchoring to The cooling rate in the phase change temperature region is To ensure the interfacial normal tensile stress generated by the phase transformation volume expansion Constantly greater than the fracture toughness criterion To achieve self-powdering and separation, a network-like brittle fracture was forced into the slag. To confirm the kinetic efficiency of sodium fluoride in stripping the solid product coating, the flow rate of the liquid-phase diffusion field on the surface of granular calcium carbide was calibrated, and the circumferential migration rate of primary silicates driven by the surface tension gradient of the melt was monitored using a high-temperature visual sensor. When the circumferential migration rate is detected Below At that time, the slag mass is compensated by injecting conditioning agent into the turbulent slag flow zone through a conditioning agent spray gun. Sodium fluoride particles are used to increase the shear rate of the superfluid film, thereby maintaining the proportion of active contact area at the atomic scale at the reduction reaction interface. above.

[0031] When determining the cooling rate of gradient cooling, the real-time cooling curve of the iron-containing silicate-based smelting waste slag is obtained by a thermal conductivity balance sensor embedded in the lining of the slag discharge bag. The opening degree of the insulation cover is used to... ℃ to The cooling rate in the ℃ range is anchored at The phase transition volume expansion stress generated under this cooling regime is ℃ per minute. The following criteria must be met: ,in, The tensile stress is the normal stress at the interface, and the unit is 1000 ppm. ; The fracture toughness of the nonmagnetic silicate matrix is ​​taken as a value of ; The characteristic length of the pre-existing crack in the matrix, in units of When the phase transformation stress exceeds the strength limit of the matrix, the waste residue undergoes spontaneous network-like brittle fracture, resulting in a particle size distribution of the produced powder. micrometers to Between micrometers; the magnetic field strength of the pulverized powder is calibrated by measuring the mass ratio and magnetization coefficient curve of the magnetic phase to obtain magnetic characteristic parameters. Based on the average particle size distribution of the metallic iron core after growth in a quasi-equilibrium state, the magnetic field strength of the first-stage magnetic separation is set to... This value corresponds to the point where the probability of recovering magnetic particles in the sorting space is maximized. The magnetic field strength of the second-stage magnetic separation is set to... This value corresponds to the characteristic field strength of gangue particle desorption, ensuring that the total iron content of the obtained magnetic concentrate is high while removing calcium sulfoaluminate impurities from the slag. And the total sulfur mass fraction is lower than .

[0032] Example 5: Applied to an annual production In the on-site deployment scenario of a 10,000-ton copper smelting slag treatment line, to ensure that the phosphorus substitution solid solution system formed between the phosphorus-containing component and the non-magnetic silicate matrix has a phase transition induced energy level, a standardized screening procedure based on the phosphorus pentoxide content is performed on the selected phosphorus-containing ore powder. This requires that the selected phosphorus-containing ore powder contain... Quality score at to Between, and through the execution of materials X-ray diffraction analysis was used to confirm that the main crystalline phase was fluorapatite, and the degree of matching between this phase and the lattice parameters of dicalcium silicate was used to assess its effect on... Orientation Chemical driving force of crystal form transformation When the calculated chemical driving force In to When the range is defined, it is determined that the phosphorus-containing component has the property of reacting when cooled to... Produced below ℃ The physical state of volume expansion: This screening procedure controls the interference deviation of different batches of mineral powder on the self-pulverization effect of slag within a preset threshold by quantitatively limiting the physical properties of raw materials.

[0033] When the system faces a situation where the heat dissipation rate of the slag body varies due to different degrees of erosion of the slag lining, the opening degree of the cooling fan of the slag discharge system should be adjusted before adding the conditioning agent. With the cooling rate of the slag The response function is calibrated offline. The offline calibration process involves measuring the temperature drop curves under different slag loads to correct the control parameters of the insulation cover. The response function follows the following linear adjustment rule: ,in, The target opening percentage for the cooling fan; The air volume adjustment coefficient is calculated by the ratio of heat dissipation power to specific heat capacity. To achieve the target cooling rate, under this operating condition, the anchor value is... ℃ per minute; The natural cooling rate of the slag at the current ambient temperature; As a reference opening degree; by compensating for fluctuations in the heat dissipation environment in this feedback loop, the iron-containing silicate-based smelting waste slag is kept within a certain range. ℃ to The cooling rate deviation in the phase transition temperature region of ℃ is within Within the range of ℃ per minute, the normal component of the crystal transformation stress at the metal-iron core interface exceeds the matrix dissociation strength.

[0034] Example 6: In the treatment of total iron mass fraction of to In the deployment scenario of molten copper slag, the average particle size of granular calcium carbide is determined by performing [the following steps]. The calibration procedure eliminates the mismatch between particle size and melt mass transfer depth. It determines the reaction driving force based on the chemical potential of the ferrite component in iron-containing silicate-based smelting waste slag, and calculates the average particle size using the following kinetic equation. : ,in, The average particle size of granular calcium carbide is given in units of 1000 mm. ; The reaction depth adjustment coefficient is set to a value under this operating condition. ; The diffusion coefficient of iron atoms at the current temperature is given by . ; The duration of the insulation treatment is expressed in units of... This calibration procedure limits the physical size of granular calcium carbide to the mass transfer limit of the melt, matches the migration rate of iron atoms and the growth rate of crystal nuclei at the interface between granular calcium carbide and iron-containing silicate-based smelting waste, and the average particle size of the produced metallic iron nuclei is within the effective capture range of physical magnetic separation.

[0035] In addition, to address the response deviations of slag systems with different mineral compositions to self-pulverizing stress, a calibration procedure was performed on the phosphorus replacement rate in the non-magnetic silicate matrix before gradient cooling was initiated. This was achieved by measuring the dicalcium silicate main crystalline phase in... Lattice distortion energy at ℃ To adjust the feeding rate of phosphorus-containing components and control the phosphorus content in the non-magnetic silicate matrix to reach the barrier level for induced crystal transformation, this calibration procedure establishes a phosphorus equivalent database using gradient phosphorus content slag samples prepared under controlled conditions. By controlling the addition amount of phosphorus-containing components within a preset proportion of the mass of iron-containing silicate-based smelting waste slag, the non-magnetic silicate matrix is ​​driven to cool to... The shear stress generated below ℃ reaches the fracture toughness of a non-magnetic silicate matrix. The iron-containing silicate-based smelting waste slag is in a self-dissociation state induced by crystal transformation stress before the grinding process.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for efficient ironmaking from copper slag based on magnetic separation pretreatment, characterized in that, Includes the following steps: Step 101: Obtain molten iron-containing silicate-based smelting waste slag at a temperature of 1250℃ to 1350℃; Step 102: A conditioning agent consisting of granular calcium carbide, sodium fluoride as an interfacial activity inducer, and a phosphorus-containing component as a phase change inducer is added to the iron-containing silicate-based smelting waste slag, and turbulent mixing is carried out using slag falling; wherein, sodium fluoride reduces the local viscosity of the primary silicate formed on the surface of the granular calcium carbide and constructs a dynamic liquid phase diffusion field migrating to the outside of the particles based on the surface tension gradient of the iron-containing silicate-based smelting waste slag melt, so as to expose the reduction reaction interface between the granular calcium carbide and the iron-containing silicate-based smelting waste slag melt; Step 103: The reduction reaction interface is used to induce an in-situ reduction reaction between granular calcium carbide and the iron silicate phase in the iron silicate-based smelting waste slag, so as to generate a metallic iron core and transform the iron silicate phase into a non-magnetic silicate matrix. Step 104: The iron-containing silicate-based smelting waste slag after the reaction is subjected to a heat treatment at 1100℃ to 1250℃ for 20 minutes to 60 minutes to construct a magnetic phase by polymer growth of metallic iron cores. Step 105 involves performing gradient cooling on the iron-containing silicate-based smelting waste slag after heat preservation, and using phosphorus-containing components to induce dicalcium silicate in the non-magnetic silicate matrix to undergo oxidation. Orientation The crystal form transformation of the type generates volume expansion shear stress to break the nonmagnetic silicate matrix; Step 106: Physically grind the crushed iron-containing silicate-based smelting waste slag to control the average particle size of the selected powder to be 150 micrometers to 250 micrometers. Step 107: Use a weak magnetic separation process with a magnetic field strength of 0.15T to 0.3T to perform magnetic separation on the powder to be selected and extract the magnetic enriched product.

2. The method for efficient ironmaking of copper slag based on magnetic separation pretreatment according to claim 1, characterized in that, In step 102, the amount of sodium fluoride added is 0.3% to 0.8% of the mass of iron silicate-based smelting waste slag. Sodium fluoride is used to construct a superfluid film composed of low-melting-point primary silicates on the surface of granular calcium carbide. The primary silicates are driven to diffuse into the melt body of iron silicate-based smelting waste slag through the surface tension gradient, so as to peel off the solid product coating layer on the surface of granular calcium carbide, thereby maintaining the active reaction area of ​​the reduction reaction interface.

3. The efficient ironmaking method for copper slag based on magnetic separation pretreatment according to claim 1, characterized in that, The phosphorus-containing component is phosphate rock powder or phosphate slag; in step 105, the phosphorus-containing component is used to adjust the crystal stability region of dicalcium silicate, so that the non-magnetic silicate matrix undergoes endogenous stress cracking caused by volume expansion shear stress when cooled to below 500°C, so as to generate annular microcracks at the interface between the metallic iron core and the non-magnetic silicate matrix.

4. The method for efficient ironmaking of copper slag based on magnetic separation pretreatment according to claim 1, characterized in that, The conditioning agent also includes anhydrous calcium sulfate as an embrittlement inducer, and the amount of anhydrous calcium sulfate added is 0.5% to 1.2% of the mass of the iron silicate-based smelting waste slag. At the end of the reduction reaction in step 103, the anhydrous calcium sulfate reacts with the residual carbon of the granular calcium carbide to carry out a redox reaction, so as to release sulfur dioxide and carbon dioxide microbubbles in situ before the iron silicate-based smelting waste slag melt solidifies.

5. The method for efficient ironmaking of copper slag based on magnetic separation pretreatment according to claim 1, characterized in that, The conditioning agent also includes a sulfur-fixing agent, which is alumina or aluminum-containing aluminum ash. The sulfur-fixing agent reacts with the alkaline components in the iron-containing silicate-based smelting waste to generate calcium aluminate microcrystals with sulfur capacity, so as to capture sulfur elements in situ and solidify them into calcium sulfoaluminate phase during the precipitation stage of metallic iron nuclei.

6. The efficient ironmaking method for copper slag based on magnetic separation pretreatment according to claim 1, characterized in that, The average particle size of the granular calcium carbide is 2 mm to 5 mm. In step 102, the heat of chemical reaction released by the strong exothermic reaction of the granular calcium carbide in the molten iron silicate-based smelting waste slag is used to construct a local high-temperature reduction micro-zone to reduce the zinc oxide in the iron silicate-based smelting waste slag and convert it into zinc vapor.

7. The efficient ironmaking method for copper slag based on magnetic separation pretreatment according to claim 1, characterized in that, The amount of conditioning agent added is 1.5% to 4.0% of the mass of iron-containing silicate-based smelting waste slag; in step 104, the polymerization rate of the magnetic phase is adjusted according to the Ostwald ripening model, which follows the following rules: ,in, For heat preservation treatment Average grain radius after time, The initial average grain radius, This refers to the interfacial tension between the magnetic phase and the non-magnetic silicate matrix. The diffusion coefficient of iron atoms in iron-containing silicate-based smelting waste slag. Let be the molar volume of iron. This represents the equilibrium solubility of the magnetic phase in a non-magnetic silicate matrix. The gas constant is The temperature is the thermodynamic temperature for heat preservation treatment.

8. The efficient ironmaking method for copper slag based on magnetic separation pretreatment according to claim 1, characterized in that, In step 106, the iron-containing silicate-based smelting waste slag, after being crushed by shear stress, is fed into a ball mill and subjected to coarse grinding for 10 to 20 minutes without the addition of grinding aids. The interfacial cracks generated by the volume expansion shear stress are used to separate the metallic iron core from the non-magnetic silicate matrix.

9. A method for efficient ironmaking from copper slag based on magnetic separation pretreatment according to claim 1, characterized in that, Step 107 employs a two-stage weak magnetic separation process. The magnetic field strength of the first stage is 0.3T, used to extract coarse and fine powder containing gangue. The magnetic field strength of the second stage is 0.15T, used to refine the coarse and fine powder to obtain iron-rich magnetic fine powder with a total iron content of not less than 90%.

10. A method for efficient ironmaking from copper slag based on magnetic separation pretreatment according to claim 1, characterized in that, In step 105, the cooling rate of the gradient cooling is controlled between 10°C per minute and 30°C per minute, so that the non-magnetic silicate matrix generates shear stress sufficient to overcome the fracture toughness of the non-magnetic silicate matrix when passing through the crystal transformation temperature range, thereby achieving the self-pulverization state of the iron-containing silicate-based smelting waste slag.

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