Method and system for recovering ferrochrome alloy in ferrochrome slag based on particle size separation

Abstract

The invention provides a method and a system for recovering ferrochrome in ferrochrome slag based on particle size separation, and relates to the technical field of metal mineral treatment. The method comprises the following steps: crushing the ferrochrome slag until the particle size is less than or equal to 15mm; the crushed ferrochrome slag is screened into materials with three particle sizes of-15 + 6 mm,-6 + 1 mm and-1 mm; respectively carrying out magnetic separation on the materials of the first particle size fraction and the second particle size fraction to obtain a first magnetic product, a second magnetic product and a non-magnetic product; the materials of the third particle size fraction are ground to the preset fineness, and ground materials are obtained; the ore grinding materials are subjected to gravity separation, and gravity separation products and tailings are obtained; the first magnetic product, the second magnetic product and the reselection product are recycled ferrochrome. Through the combination of crushing, screening, magnetic separation, grinding and reselection processes, high-efficiency recovery of ferrochrome alloy with different particle sizes in ferrochrome slag is realized, the recovery rate of ferrochrome alloy is improved, and good economic benefits and environmental benefits are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal ore treatment, and particularly to a method and system for recovering ferrochrome alloy from ferrochrome slag based on particle size separation. Background Art

[0002] Ferrochrome slag is an industrial solid waste residue generated during the pyrometallurgical smelting process of high-carbon ferrochrome alloy. The main chemical components of ferrochrome slag are complex and usually include: Cr2O3 (3% - 8%), SiO2 (28% - 34%), Al2O3 (15% - 30%), MgO (20% - 35%), Fe2O3 (1% - 5%) and CaO (1% - 5%). Among them, chromium (Cr) and iron (Fe) elements have high recovery value. If they can be effectively recovered, it can not only realize the recycling of resources but also reduce environmental risks.

[0003] However, the current treatment and utilization methods of ferrochrome slag are relatively extensive, mainly based on stacking and building materials utilization. Stacking treatment is the simplest and most direct method, but long-term stacking not only occupies a large amount of land resources, but also the heavy metal elements (such as Cr) in ferrochrome slag will gradually be released under natural actions such as rain leaching and migrate into the surrounding soil and water bodies, causing serious environmental pollution and constituting long-term environmental risks. Although building materials utilization realizes the resource utilization of ferrochrome slag to a certain extent, for example, using it as an auxiliary material for cement or concrete, this method has two limitations: one is that the application proportion of ferrochrome slag in the building materials field is still limited and it is difficult to effectively dispose of the huge amount of ferrochrome slag generated; the other is that this method only realizes the low-value utilization of ferrochrome slag, and the valuable components such as chromium and iron in it are not effectively recovered, resulting in a waste of precious resources.

[0004] Chinese Patent Document (CN114164346A) proposes a method for co-recovering valuable metals from chromium-containing waste slag and carbon-containing waste materials. The core of this method lies in high-temperature reduction roasting, with a relatively complex process flow, high energy consumption, and high requirements for equipment, and its economy needs to be improved.

[0005] Chinese Patent Document (CN116273436A) discloses a beneficiation process for chromite ore. This process mainly targets chromite ore raw materials rather than ferrochrome slag. The technical processes such as high-pressure roll grinding and reverse flotation used in it are complex and require the use of flotation reagents. For ferrochrome slag with complex composition and low grade, its economy and applicability are poor.

[0006] Therefore, it is necessary to improve the existing ferrochrome slag treatment technology to overcome the defects of the existing technology. Summary of the Invention

[0007] To overcome the problems existing in the related technologies, one of the objectives of the present invention is to provide a method for recovering ferrochrome alloy from ferrochrome slag based on particle size separation. By crushing and screening the ferrochrome slag and then performing magnetic separation and gravity separation on the products of different particle size grades respectively, the efficient recovery of ferrochrome alloy is achieved, overcoming the problems such as high environmental pollution risk, low resource utilization rate, complex process, high energy consumption, and lack of pertinence existing in the prior art.

[0008] A method for recovering ferrochrome alloy from ferrochrome slag based on particle size separation, comprising the following steps:

[0009] Step S1: Crush the ferrochrome slag to a particle size less than or equal to 15 mm;

[0010] Step S2: Screen the crushed ferrochrome slag into materials of a first particle size grade, a second particle size grade, and a third particle size grade, wherein the first particle size grade is -15 + 6 mm, the second particle size grade is -6 + 1 mm, and the third particle size grade is -1 mm;

[0011] Step S3: Perform magnetic separation on the materials of the first particle size grade and the second particle size grade respectively to obtain a first magnetic product, a second magnetic product, and a non-magnetic product;

[0012] Step S4: Grind the materials of the third particle size grade to a predetermined fineness to obtain ground ore materials;

[0013] Step S5: Perform gravity separation on the ground ore materials to obtain a gravity separation product and tailings;

[0014] The first magnetic product, the second magnetic product, and the gravity separation product are the recovered ferrochrome alloy.

[0015] Through the physical property differences of different particle size grades of ferrochrome slag and by adopting different separation processes, the efficient recovery of ferrochrome alloy is realized. By crushing and screening, the ferrochrome slag is divided into different particle size grades, making the subsequent separation more targeted; magnetic separation is used for the larger particle size grades and gravity separation is used for the smaller particle size grades, making full use of the magnetic and density differences between ferrochrome alloy and gangue minerals and improving the recovery rate.

[0016] Further, in the step S4, the predetermined fineness is -100 mesh to -300 mesh.

[0017] Furthermore, the predetermined fineness is -200 mesh.

[0018] Further, in the step S3, the magnetic separation specifically includes:

[0019] Perform high-intensity magnetic separation and low-intensity magnetic separation on the materials of the first particle size grade successively to obtain a first magnetic product, a second magnetic product, and a non-magnetic product;

[0020] The materials at the second particle size level are subjected to high-intensity magnetic separation and low-intensity magnetic separation successively to obtain a first magnetic product, a second magnetic product and a non-magnetic product.

[0021] The combination of high- and low-intensity magnetic separation areas can specifically recover ferrochrome alloy components with different magnetic intensities, improving the magnetic separation efficiency and the overall recovery rate of ferrochrome alloy.

[0022] Furthermore, the magnetic field intensity of the high-intensity magnetic separation is 1800 Gs to 5000 Gs, and the magnetic field intensity of the low-intensity magnetic separation is 500 Gs to 1500 Gs.

[0023] The design of this magnetic field intensity range and magnetic field gradient difference makes the magnetic separation process more controllable, can efficiently classify and recover magnetic substances, obtain magnetic products with higher purity, and maximize the recovery rate of ferrochrome alloy.

[0024] Furthermore, the step S5 includes:

[0025] According to the density differences of different components in the ground ore materials, a shaking table is used to layer and separate the ground ore materials with different densities to obtain a gravity separation product and tailings.

[0026] The gravity separation step is carried out by a shaking table, which can effectively layer and separate according to the density differences of different components in the materials, improving the accuracy and efficiency of gravity separation.

[0027] Furthermore, the ferrochrome slag is the waste slag produced by the smelting of high-carbon ferrochrome alloy.

[0028] The second object of the present invention is to provide a ferrochrome alloy recovery system based on particle size separation for implementing the method for recovering ferrochrome alloy from ferrochrome slag based on particle size separation as described above, including:

[0029] A crushing device for crushing the ferrochrome slag to a particle size less than or equal to 15 mm;

[0030] A screening device for screening the crushed ferrochrome slag into materials at a first particle size level, a second particle size level and a third particle size level;

[0031] A magnetic separation device for magnetically separating the materials at the first particle size level and the second particle size level to obtain a first magnetic product, a second magnetic product and a non-magnetic product;

[0032] A grinding device for grinding the materials at the third particle size level to obtain ground ore materials;

[0033] A gravity separation device for carrying out gravity separation on the ground materials to obtain a gravity separation product and tailings.

[0034] Through devices such as crushing, screening, magnetic separation, grinding, and gravity separation, the automated and continuous production of ferrochrome slag recovery can be achieved, improving production efficiency. Each device works in coordination to efficiently recover ferrochrome alloy from ferrochrome slag.

[0035] Furthermore, it also includes a belt conveyor for connecting the crushing device, screening device, magnetic separation device, grinding device, and gravity separation device and transporting materials.

[0036] The addition of the belt conveyor enables the automatic transportation of materials between devices, reduces manual operation, and improves the degree of automation and production efficiency.

[0037] Furthermore, the magnetic separation device includes two magnetic drums, and a strong magnet is installed inside the magnetic drum to form a magnetic field;

[0038] The magnetic drum is arranged at the head of the belt conveyor for receiving the materials transported by the belt conveyor;

[0039] The two magnetic drums respectively perform magnetic separation on materials of the first particle size grade and the second particle size grade. Each magnetic drum is provided with a high-field-strength magnetic separation area and a low-field-strength magnetic separation area. The magnetic field strength in the high-field-strength magnetic separation area is between 1800 GS and 5000 GS, and the magnetic field strength in the low-field-strength magnetic separation area is between 500 GS and 1500 GS.

[0040] Two magnetic drums are used to separately process materials of -15 + 6 mm and -6 + 1 mm particle size grades, and each magnetic drum is provided with a high-field-strength magnetic separation area of 1800 Gs to 5000 Gs and a low-field-strength magnetic separation area of 500 Gs to 1500 Gs. This setting avoids interference between materials of different particle size grades, realizes the classified recovery of magnetic substances, and defines the magnetic field strength range to ensure the magnetic separation effect. The arrangement of the magnetic drum at the head of the belt conveyor realizes the continuous automated operation of material transportation and magnetic separation, improving production efficiency.

[0041] Furthermore, the grinding device includes a cylinder body, a driving device, and spherical grinding media;

[0042] The spherical grinding media are contained in the cylinder body, and the driving device is used to drive the cylinder body to rotate, causing the grinding media to collide and rub against the materials;

[0043] The gravity separation device is a dressing table.

[0044] The grinding device is a grinding device containing spherical grinding media. The spherical grinding media can fully grind fine-grained materials, dissociate the ferrochrome alloy monomers, and is beneficial for subsequent gravity separation. The gravity separation device is a dressing table, and the dressing table has good separation effect on fine-grained minerals and can effectively recover the ferrochrome alloy after grinding.

[0045] Further, the crushing device includes a crushing chamber and a crushing component;

[0046] The crushing component is disposed in the crushing chamber and is used for crushing the ferrochrome slag entering the crushing chamber.

[0047] The screening device includes a screen mesh, a vibrator, and a screen frame;

[0048] The screen mesh is disposed on the screen frame and is used for screening materials;

[0049] The vibrator is used to generate vibrations to vibrate the screen mesh and promote the screening of materials;

[0050] The screening device has at least three layers of screen meshes, and the at least three layers of screen meshes correspond to the first particle size grade, the second particle size grade, and the third particle size grade.

[0051] The crushing device can crush the ferrochrome slag to a suitable particle size. The screening device uses at least three layers of screen meshes and can screen the crushed ferrochrome slag into three particle size grades, ensuring the coordination and high efficiency of the entire system. The vibrating screen uses a vibrator to generate vibrations, which can effectively prevent the screen holes from being blocked and improve the screening efficiency.

[0052] The beneficial effects of the present invention are as follows:

[0053] A method for recovering ferrochrome alloy from ferrochrome slag based on particle size separation provided by the present invention adopts a pretreatment method of first crushing and then screening according to the characteristics of ferrochrome slag. As a metallurgical waste residue, ferrochrome slag has a complex composition, and the ferrochrome alloy and gangue minerals are unevenly disseminated in particle size. Through crushing, the ferrochrome alloy and gangue minerals in large pieces of ferrochrome slag can be preliminarily dissociated, and at the same time, the particle size of the material can be reduced, which is beneficial to subsequent separation operations; while screening divides the crushed material into different particle size grades, facilitating subsequent targeted separation, and realizes the pretreatment and classification of the material through crushing and screening.

[0054] According to the characteristics of materials with different particle size grades, two separation processes of magnetic separation and gravity separation are respectively adopted. For the two larger particle size grades of -15 + 6 mm and -6 + 1 mm, since the iron-containing minerals in the ferrochrome alloy have strong magnetism, while the gangue minerals usually have no magnetism or weak magnetism, magnetic separation process can effectively enrich and recover the ferrochrome alloy in these two particle size grades, that is, magnetic separation is adopted for the larger particle size grades to achieve separation by using magnetic differences.

[0055] For fine-grained materials with a particle size of -1 mm, due to their fine particle size, the magnetic separation effect is not good. Therefore, this method first grinds them to a predetermined fineness to further monomerize the ferrochrome alloy. After grinding, the density difference between the ferrochrome alloy and gangue minerals becomes more significant. Therefore, the gravity separation process can effectively separate the ferrochrome alloy from the fine-grained materials, that is, for fine-grained materials, grinding and gravity separation are used to achieve separation by means of monomer dissociation and density difference.

[0056] This method realizes the efficient recovery of ferrochrome alloy from chromite slag, improves the recovery rate of ferrochrome alloy, and reduces the waste of valuable resources. At the same time, this method has a simple process flow, is easy to implement, and has relatively low equipment investment and operating costs, with good economy and applicability. Brief Description of the Drawings

[0057] Figure 1 is a flowchart of the method for recovering ferrochrome alloy from chromite slag based on particle size separation provided in this application;

[0058] Figure 2 is a schematic diagram of the system for recovering ferrochrome alloy from chromite slag based on particle size separation provided in this application.

[0059] Reference Signs:

[0060] 100, crushing device; 200, screening device; 300, magnetic separation device; 400, grinding device; 500, gravity separation device. Detailed Embodiments

[0061] The preferred embodiments of the present invention will be described in more detail below with reference to the drawings. Although the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0062] Embodiment

[0063] As Figure 1 , Figure 2 shown, this embodiment provides a method and system for recovering ferrochrome alloy from chromite slag based on particle size separation. The system for recovering ferrochrome alloy from chromite slag based on particle size separation is used to implement the method for recovering ferrochrome alloy from chromite slag based on particle size separation. The system for recovering ferrochrome alloy from chromite slag based on particle size separation mainly includes a crushing device 100, a screening device 200, a magnetic separation device 300, a grinding device 400, a gravity separation device 500, and a belt conveyor connecting each device.

[0064] The crushing device 100 is used to crush large pieces of ferrochrome slag into smaller particle sizes, enabling the preliminary dissociation of ferrochrome alloy and gangue minerals. Usually, equipment such as jaw crushers or impact crushers is adopted. The crushing device 100 preferably uses a jaw crusher, and other types of crushing equipment such as impact crushers can also be used. The jaw crusher has the advantages of a large crushing ratio, uniform product particle size, simple structure, reliable operation, and convenient maintenance. The main function of the crushing device 100 is to crush large pieces of ferrochrome slag into smaller particle sizes (less than or equal to 15 mm), enabling the preliminary dissociation of ferrochrome alloy and gangue minerals and meeting the requirements of subsequent screening and sorting operations.

[0065] The jaw crusher mainly consists of a frame, eccentric shaft, pulley, flywheel, moving jaw, fixed jaw, toggle plate, toggle plate rear seat, gap adjustment screw, return spring, fixed jaw plate, and movable jaw plate, etc. Among them, the moving jaw and the fixed jaw form a crushing chamber, and the material is crushed under the action of extrusion, splitting, and bending in the crushing chamber.

[0066] The screening device 200 is used to divide the crushed ferrochrome slag into multiple levels according to particle size. Usually, a vibrating screen is adopted, and classification is achieved through sieve meshes with different apertures. In this system, the screening device 200 divides the ferrochrome slag into three particle size levels: -15 + 6 mm, -6 + 1 mm, and -1 mm. In this embodiment, the screening device 200 preferably uses a three-layer vibrating screen, and vibrating screens with different numbers of layers can also be selected according to actual needs. The vibrating screen makes the material layer on the screen surface loose and jump through the vibration generated by the vibrator. The small-particle material passes through the sieve holes, while the large-particle material remains on the screen surface, thereby achieving classification according to particle size. The main function of the screening device 200 is to divide the crushed ferrochrome slag into multiple levels according to particle size, so as to adopt different sorting processes for different particle sizes subsequently. The vibrating screen mainly consists of a screen box, sieve mesh, vibrator, damping spring device, support, etc. In this embodiment, the apertures of the three-layer sieve mesh are 15 mm, 6 mm, and 1 mm respectively, dividing the ferrochrome slag into three particle size levels: -15 + 6 mm, -6 + 1 mm, and -1 mm.

[0067] The magnetic separation device 300 is used to separate magnetic substances (ferrochrome alloy containing iron) and non-magnetic substances (gangue) in materials of larger particle size levels (-15 + 6 mm and -6 + 1 mm). Usually, a magnetic roller is adopted, with a strong magnet installed inside, and separation is carried out using magnetic force. In this system, two magnetic rollers are set up to process materials of two particle size levels: -15 + 6 mm and -6 + 1 mm respectively.

[0068] In this embodiment, the magnetic separation device 300 includes two magnetic drums, which are respectively used to process materials of two particle size grades, -15 + 6 mm and -6 + 1 mm. A permanent magnet (such as a neodymium iron boron strong magnet) is installed inside the magnetic drum, which can generate a strong magnetic field. A high magnetic field intensity magnetic separation area is arranged near the material inlet of each magnetic drum, and a low magnetic field intensity magnetic separation area is arranged away from the material inlet. Among them, the magnetic field intensity of the high magnetic field intensity magnetic separation area is between 2500 Gs and 3500 Gs, and the magnetic field intensity of the low magnetic field intensity magnetic separation area is between 800 Gs and 1200 Gs. The magnetic drum is usually installed at the head of the belt conveyor. When the material is conveyed to the upper part of the magnetic drum by the belt conveyor, the magnetic substances (ferrochrome alloy containing iron) therein are attracted by the magnetic force, adsorbed on the surface of the magnetic drum, and are carried to the area with a weaker magnetic field as the magnetic drum rotates, and then fall off into the magnetic product collection tank; the non-magnetic substances (gangue) continue to move forward along the direction of the belt conveyor under the action of gravity and enter the non-magnetic product collection tank.

[0069] The diameter of the magnetic drum is usually 400 - 800 mm, the length is determined according to the processing capacity, and the magnetic field intensity is usually between 1000 - 4000 gauss. In this embodiment, the magnetic field intensities of the two magnetic drums are not less than 2500 gauss to ensure the effective adsorption of magnetic substances.

[0070] The grinding device 400 is used to further grind the fine-grained (-1 mm) materials to dissociate the ferrochrome alloy monomers. Usually, a ball mill is used, and the grinding is realized by the impact and abrasion of grinding media (such as steel balls). In this embodiment, the grinding device 400 preferably uses a ball mill, and other types of grinding equipment such as a rod mill can also be used. The ball mill is driven by a motor to rotate the cylinder body, and a certain proportion of grinding media (such as steel balls) is installed inside the cylinder body. When the cylinder body rotates, the grinding media are lifted to a certain height under the action of centrifugal force and friction force, and then fall or flow down, generating impact and abrasion on the materials, so as to grind the materials finely. The main function of the grinding device 400 is to further grind the -1 mm fine-grained materials to -200 mesh (less than 0.074 mm) to dissociate the ferrochrome alloy therein and create conditions for subsequent gravity separation operations.

[0071] The gravity separation device 500 is used to separate the heavy minerals (chromium-containing ferrochrome alloy) and light minerals (gangue) in the ground fine-grained materials. Usually, a shaking table is used to perform separation by using the density difference of minerals.

[0072] In this embodiment, the re-selection device 500 is preferably a shaking table, and other types of re-selection equipment such as a spiral chute can also be used. The shaking table is a commonly used re-selection equipment mainly used for processing fine-grained minerals. The surface of the shaking table is engraved with riffles. The table surface makes a longitudinal reciprocating motion driven by a transmission mechanism and is inclined laterally at the same time. After the pulp is fed onto the table surface, under the action of water flow and table vibration, mineral particles of different densities are stratified and separated. The mineral particles with a large density (ferrochrome alloy) move along the table surface to the concentrate end and are discharged, while the mineral particles with a small density (gangue) are discharged from the tailings end along the lateral slope.

[0073] The belt conveyor is used to connect the above-mentioned devices to realize the continuous transportation of materials between the devices. Multiple belt conveyors are used to connect the above-mentioned devices to realize the continuous and automatic transportation of materials between the devices. The belt conveyor has the advantages of large conveying capacity, long conveying distance, stable operation, and low energy consumption.

[0074] The process for recovering ferrochrome alloy from ferrochrome slag based on particle size separation is as follows:

[0075] Step S1, crushing: Feed the ferrochrome slag into the crushing device 100 for crushing so that its particle size is less than or equal to 15 mm. During the crushing process, it is necessary to control the feeding speed to avoid overloading the crusher. At the same time, it is necessary to regularly check the wear condition of the crusher and replace the vulnerable parts in time.

[0076] Step S2, screening: Feed the crushed ferrochrome slag into the screening device 200 and screen it into three particle size grades: -15 + 6 mm, -6 + 1 mm, and -1 mm. During the screening process, it is necessary to regularly check the wear and blockage conditions of the screen mesh and clean and replace the screen mesh in time.

[0077] Step S3, magnetic separation: Convey the materials of the -15 + 6 mm particle size grade to the upper part of the first magnetic drum through a belt conveyor. The materials first pass through the high-intensity magnetic separation area and then through the low-intensity magnetic separation area; use the magnetic field attraction of the high-intensity magnetic separation area and the low-intensity magnetic separation area to adsorb the magnetic substances in the materials on the surface of the magnetic drum, and as the magnetic drum rotates, the magnetic substances are taken away from the discharge port to obtain the first magnetic product; the non-magnetic substances continue to move forward along the belt conveyor to obtain the first non-magnetic product.

[0078] Convey the materials of the -6 + 1 mm particle size grade to the upper part of the second magnetic drum through a belt conveyor. The materials first pass through the high-intensity magnetic separation area and then through the low-intensity magnetic separation area; use the magnetic field attraction of the high-intensity magnetic separation area and the low-intensity magnetic separation area to adsorb the magnetic substances in the materials on the surface of the magnetic drum, and as the magnetic drum rotates, the magnetic substances are taken away from the discharge port to obtain the second magnetic product; the non-magnetic substances continue to move forward along the belt conveyor to obtain the second non-magnetic product.

[0079] Step S4, Grinding: Feed the materials of -1 mm particle size into the grinding device 400 and grind them to -200 mesh. During the grinding process, it is necessary to control the ore feeding concentration, the rotation speed of the ball mill, and the ratio of the grinding medium to ensure the grinding fineness and efficiency.

[0080] Step S5, Gravity Separation: Feed the ground materials into the gravity separation device 500 and separate the gravity separation products (fine-grained ferrochrome alloy) and tailings using the density difference. During the gravity separation process, it is necessary to adjust the stroke, impulse, transverse slope, and flushing water volume of the shaking table according to the properties of the materials to achieve the best separation effect.

[0081] Step S6, Product Collection: Combine the first magnetic product, the second magnetic product, and the gravity separation product, which is the recovered ferrochrome alloy product.

[0082] The system and method of this embodiment are used to conduct a treatment test on the ferrochrome slag generated by a high-carbon ferrochrome plant. During the test, the total weight of the ferrochrome slag before treatment is 33850.00 g, in which the Cr element content accounts for 3.58%, and the Cr metal amount is 1210.56 g.

[0083] The ferrochrome slag is processed according to the method of this embodiment for the test, and the results are shown in the following table:

[0084]

[0085] Among them, magnetic concentrate corresponds to the first magnetic product, magnetic tail corresponds to the second magnetic product, and gravity separation ore corresponds to the gravity separation product.

[0086] Recovery situation of each particle size:

[0087] +6 mm particle size: The yield of magnetic separation concentrate is 2.23%, the yield to the original ore is 0.63%, the Cr recovery rate is 25.24%, and the recovery rate to the original ore is 7.66%. This part is mainly the larger particle size ferrochrome alloy.

[0088] -6 + 1 mm particle size: The yield of magnetic separation concentrate is 1.06%, the yield to the original ore is 0.61%, the Cr recovery rate is 10.62%, and the recovery rate to the original ore is 5.75%. This part is mainly the medium particle size ferrochrome alloy.

[0089] -1 mm particle size: The yield of the gravity separation product is 100% (relative to the weight of the -1 mm particle size), the yield to the original ore is 14.77%, the Cr recovery rate is 100% (relative to the Cr metal amount in the -1 mm particle size), and the recovery rate to the original ore is 15.49%. This part is mainly the fine particle size ferrochrome alloy that is monomer-dissociated after grinding.

[0090] Overall recovery situation: The yield of total chromium ferro magnetic concentrate (including +6mm, -6+1mm magnetic separation products, and -1mm gravity separation products) is 1.24% (based on the original ore), and the chromium recovery rate is 13.41% (based on the original ore).

[0091] The amount of chromium metal in the total weight of the original ore is 1210.56g. Among them, the proportions of the three particle sizes of -15+6mm, -6+1mm, and -1mm are 30.33%, 54.18%, and 15.49% in sequence.

[0092] The chromium recovery rate of the -1mm particle size is high, but the small proportion of -1mm results in a low recovery rate for the original ore.

[0093] The method of this embodiment can effectively recover chromium ferroalloy from chromium iron slag. Especially after crushing and screening, better results are achieved for the larger particle sizes (+6mm and -6+1mm) through the magnetic separation process combining high magnetic field strength and low magnetic field strength, and the recovery rates for the original ore reach 7.66% and 5.75% respectively. For the fine particle size material of -1mm, a relatively high recovery rate of 15.49% is also obtained through grinding and gravity separation.

[0094] The chromium ferroalloy recovery system and method for chromium iron slag based on particle size sorting provided in this embodiment realize the efficient recovery of chromium ferroalloy with different particle sizes in chromium iron slag through the organic combination of processes such as crushing, screening, magnetic separation, grinding, and gravity separation. This method has a simple process flow, reasonable equipment configuration, stable and reliable operation, can significantly improve the recovery rate of chromium ferroalloy, reduce resource waste and environmental pollution, and has good economic and social benefits.

[0095] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps described in these embodiments do not limit the scope of this application. In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that: Similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0096] In addition, it should be noted that the use of terms such as "first" and "second" is only for the convenience of distinction. Without additional declaration, the above terms have no special meaning, and thus cannot be construed as limiting the protection scope of this application.

[0097] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting, characterized in that: include: S1. Crushing the ferrochrome slag to a particle size of less than or equal to 15 mm; S2, screening the crushed ferrochrome slag into materials of a first particle size grade, a second particle size grade and a third particle size grade, wherein the first particle size grade is -15+6mm, the second particle size grade is -6+1mm, and the third particle size grade is -1mm; S3, performing magnetic separation on the materials of the first particle size grade and the second particle size grade respectively to obtain a first magnetic product, a second magnetic product and a non-magnetic product; S4, grinding the material of the third particle size level to a predetermined fineness to obtain a ground material; S5, performing gravity separation on the ground material to obtain gravity separation products and tailings; The first magnetic product, the second magnetic product and the gravity separation product are recovered ferrochrome.

2. The method for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting according to claim 1, characterized in that: In the step S4, the predetermined fineness is -100 mesh to -300 mesh.

3. The method for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting according to claim 1, characterized in that: In step S3, magnetic separation specifically includes: The materials of the first particle size grade are subjected to high-field strength magnetic separation and low-field strength magnetic separation successively to obtain a first magnetic product, a second magnetic product and a non-magnetic product; The material of the second particle size grade is subjected to high field strength magnetic separation and low field strength magnetic separation in sequence to obtain a first magnetic product, a second magnetic product and a non-magnetic product.

4. The method for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting according to claim 3, characterized in that: The magnetic field strength of the high-field strength magnetic separation is 1800Gs to 5000Gs, and the magnetic field strength of the low-field strength magnetic separation is 500Gs to 1500Gs.

5. The method for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting according to any one of claims 1 to 4, characterized in that: The step S5 comprises: According to the density difference of different components in the ground material, the ground materials with different densities are layered and separated using a shaking table to obtain gravity separation products and tailings.

6. A system for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting, used for implementing the method for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting as claimed in any one of claims 1 to 5, characterized in that: include: A crushing device (100) is used to crush the ferrochrome slag to a particle size of less than or equal to 15 mm; A screening device (200) is used to screen the crushed ferrochrome slag into materials of a first particle size grade, a second particle size grade and a third particle size grade; A magnetic separation device (300) is used to perform magnetic separation on the materials of the first particle size grade and the second particle size grade to obtain a first magnetic product, a second magnetic product and a non-magnetic product; A grinding device (400) is used to grind the third particle size grade to obtain a ground material; The gravity separation device (500) is used to perform gravity separation on the ground material to obtain gravity separation products and tailings.

7. The system for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting according to claim 6, characterized in that: It also includes a belt conveyor, which is used to connect the crushing device (100), the screening device (200), the magnetic separation device (300), the grinding device (400) and the gravity separation device (500) and to transport materials.

8. The system for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting according to claim 7, characterized in that: The magnetic separation device (300) comprises two magnetic rollers, and strong magnets are installed inside the magnetic rollers to form a magnetic field; The magnetic roller is arranged at the head of the belt conveyor and is used to receive the material conveyed by the belt conveyor; The two magnetic rollers respectively perform magnetic separation on the materials of the first particle size grade and the second particle size grade, and each magnetic roller is provided with a high field strength magnetic separation area and a low field strength magnetic separation area. The magnetic field strength of the high field strength magnetic separation area is between 1800GS and 5000GS, and the magnetic field strength of the low field strength magnetic separation area is between 500GS and 1500GS.

9. The system for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting according to claim 6 or 7, characterized in that: The grinding device (400) comprises a cylinder, a driving device and spherical grinding media; The spherical grinding medium is contained in the cylinder, and the driving device is used to drive the cylinder to rotate so that the grinding medium and the material collide and rub against each other; The gravity separation device (500) is a mineral separation shaking table.

10. The system for recovering ferrochrome alloy from ferrochrome slag based on particle size sorting according to claim 6, characterized in that: The crushing device (100) comprises a crushing chamber and a crushing component; The crushing component is arranged in the crushing chamber and is used to crush the ferrochrome slag entering the crushing chamber; The screening device (200) comprises a screen, a vibrator and a screen frame; The screen is arranged on the screen frame and is used for screening materials; The vibrator is used to generate vibration to make the screen vibrate; The screening device (200) has at least three layers of screens, and the at least three layers of screens correspond to the first particle size grade, the second particle size grade and the third particle size grade.

Images