Steel slag processing and purifying method and system

Abstract

The invention relates to the technical field of solid waste treatment in the metallurgical industry, in particular to a steel slag processing and purifying method and system. Removing non-magnetic materials through 30mm screening and pre-magnetic separation; grinding by a large rod mill, sieving by 10mm, and performing closed-loop processing on oversize products in a small rod mill; performing magnetic separation and purification on the screen underflow for collecting fine iron powder and tailings; the steel slag processing and purifying system comprises a primary crushing unit, a gridding device, a secondary crushing unit, a conveying belt system, a stock bin feeding unit, a primary screening unit, a pre-selection magnetic separation unit, a large rod mill, a secondary screening unit, a rod abrasive particle steel separation module, a magnetic separation unit and a closed-loop circulation system. The method has the advantages that the materials are divided into the materials smaller than or equal to 30 mm and the materials larger than 30 mm through the roller screen, the materials smaller than or equal to 30 mm are subjected to air separation and magnetic separation, non-magnetic materials are separated out in advance and discharged as tailings, the amount of the materials entering the follow-up rod milling procedure is reduced, the treatment efficiency is improved, and meanwhile energy consumption of the follow-up procedure is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste treatment in the metallurgical industry, and in particular to a steel slag processing and purification method and system. Background Art

[0002] With the booming steel industry, steel mills inevitably generate large quantities of slag during production. For example, one steel mill, for example, must handle as much as one million tons of slag annually. This phenomenon is not isolated; many steel mills face similar challenges with large quantities of slag to be handled. As an unavoidable byproduct of steel production, proper handling of this slag is crucial for achieving green and sustainable development in the steel industry.

[0003] Currently, many domestic steel mills generally use pool-type hot stuffing and permanent magnet drum magnetic separation processes to treat steel slag. The pool-type hot stuffing process primarily utilizes a hot stuffing pool to heat the steel slag, causing some substances in the steel slag to undergo physical and chemical changes at high temperatures, initially achieving treatment goals such as stabilization. The permanent magnet drum magnetic separation process, on the other hand, uses the magnetic field generated by the permanent magnet drum to adsorb and separate magnetic substances such as iron from the steel slag, resulting in magnetic separation powder and achieving initial purification of the steel slag.

[0004] Using the above process, many problems are exposed in the actual application process:

[0005] After secondary purification, the grade of magnetic separation powder can still only reach 35-40%, and the grade improvement is obviously limited;

[0006] At the same time, some low-grade materials in steel slag cannot be effectively recycled through existing processes due to their low iron content, resulting in a large backlog of these low-grade materials in the factory, which not only occupies land resources, but also may cause potential harm to the surrounding environment, increasing the operating burden of steel companies.

[0007] This situation is also common among other domestic steel companies. The grade of their magnetic separation fines also hovers around 40%. Furthermore, when lower-grade magnetic separation fines are recycled into blast furnaces, their insufficient iron content requires more fuel to maintain normal smelting reactions. This results in significant fuel waste and severely hinders steel companies' ability to reduce costs, improve economic efficiency, and achieve energy conservation and emission reduction goals. These issues highlight the urgent need for improvement and optimization of existing slag processing and purification processes. Summary of the Invention

[0008] The purpose of the present invention is to provide a steel slag processing and purification method and system, which aims to address the defects of the existing metallurgical solid waste (steel slag) processing and purification technology, provide a dust-free process magnetic separation production line, comprehensively improve the grade of magnetic separation powder, reduce the iron content of tailings, and realize the efficient recycling of steel slag resources.

[0009] To achieve the above object, the present invention is implemented through the following technical solutions:

[0010] A method for processing and purifying steel slag, comprising:

[0011] S1, two-stage mechanical crushing to make the raw material particle size ≤200mm;

[0012] S2, remove non-magnetic materials through 30mm screening and pre-magnetic separation;

[0013] S3, after grinding in the large rod mill, the material is screened with 10mm, and the material on the screen enters the small rod mill for closed-loop processing;

[0014] S4. Magnetic separation and purification of the material under the sieve is carried out to collect iron ore concentrate and tailings.

[0015] In S2, pre-magnetic separation uses gradient magnetic field separation.

[0016] The gradient magnetic field is 10,000 Gauss → 5,000 Gauss.

[0017] In S3, the rod mill output material is subjected to air separation to extract the rod abrasive steel, and the non-magnetic material is directly discarded.

[0018] A steel slag processing and purification system, comprising: a primary crushing unit, a grizzly screen device, a secondary crushing unit, a conveyor belt system, a silo loading unit, a primary screening unit, a pre-selection magnetic separation unit, a large rod mill, a secondary screening unit, a rod mill steel separation module, a magnetic separator unit, and a closed-loop circulation system;

[0019] The primary crushing unit is used to crush the raw materials to a size less than 500mm;

[0020] The grid screen device is used to screen the materials after primary crushing;

[0021] The secondary crushing unit is used to crush the material on the grid screen to less than 200mm;

[0022] The conveyor belt system is used to mix the undersize material from the grid screen device with the secondary crushed material and transport it to the material pool;

[0023] The silo loading unit is used to store mixed materials;

[0024] The first-level screening unit is connected to the silo through conveyor belt 1, and the screened material is sent to the large rod mill silo through conveyor belt 2;

[0025] Pre-selection magnetic separation unit, air separation and magnetic separation heads are sequentially arranged above the large rod grinding bin to separate tailings;

[0026] Large rod mill, processing 30mm screen oversize and pre-selected magnetic materials;

[0027] The secondary screening unit is used to sort the material discharged from the large rod mill, and the material on the screen enters the small rod mill;

[0028] Rod abrasive steel separation module (with air separation and magnetic separation heads above the small rod grinding discharge belt) is used to separate non-magnetic waste materials;

[0029] The magnetic separator is used to process the 10mm undersize from the large / small rod mill and output fine powder and tailings;

[0030] The closed-loop circulation system returns the discharge from the small rod mill to the secondary screening unit.

[0031] The primary crushing unit is completed by two or more excavators working together to complete the crushing; the secondary crushing unit uses a secondary jaw crusher to crush the material on the grid screen, with the target particle size being ≤200mm, and there are at least two secondary jaw crushers.

[0032] The sieve hole size of the grizzly screen device is (160-180) mm × (240-260) mm. The undersize of the grizzly screen device directly enters the conveyor belt and is mixed with the jaw crusher discharge.

[0033] The first-stage screening unit adopts 30mm roller screen, and the second-stage screening unit adopts 10mm roller screen.

[0034] The discharge from the small rod mill is returned to the 10mm roller screen through a belt closed loop for cyclic crushing.

[0035] The magnetic separator unit includes at least two stages of high-intensity magnetic separators, and the magnetic field strength is not less than 12,000 Gauss.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. Use the excavator to initially crush large pieces of material to less than 500mm, and then use the grid screen and jaw crusher to further process them into small pieces less than 200mm. This multi-stage crushing and screening method can effectively reduce the material particle size, provide a suitable particle size range for subsequent processing steps, and improve the overall processing efficiency;

[0038] 2. The coordinated use of the grizzly screen and jaw crusher ensures uniform particle size of the material entering the next process, which is conducive to the stable operation of subsequent equipment and reduces equipment failure and wear caused by excessive or uneven material particle size;

[0039] 3. The roller screen is used to separate the material into two parts: ≤30mm and >30mm. The material ≤30mm is subjected to air separation and magnetic separation. The non-magnetic material can be separated in advance and discharged as tailings, which reduces the amount of material entering the subsequent rod mill process, improves the processing efficiency, and reduces the energy consumption of the subsequent process.

[0040] 4. The large rod mill and small rod mill grind materials of different particle size ranges respectively, and then screen them through roller screens to further refine the material particle size, so that the material reaches a more suitable particle size range, which is conducive to the subsequent concentrate extraction and purification;

[0041] 5. Air separation and magnetic separation devices are installed above and at the end of the belt to monitor and screen out non-magnetic materials in real time and discharge them, avoiding repeated processing of useless materials, reducing system energy consumption and equipment wear, and improving overall production efficiency;

[0042] 6. By gradually reducing the amount of materials, the processing volume of subsequent processes is reduced, the operating load and energy consumption of the equipment are reduced, and the purpose of energy saving and consumption reduction is achieved, which is conducive to reducing production costs and improving economic benefits;

[0043] 7. The various processes are closely connected, and materials are continuously transported through conveyor belts, which ensures the continuity and stability of production, improves production efficiency, and reduces production delays and equipment downtime caused by material interruptions;

[0044] 8. Through multi-stage crushing, screening, air separation and magnetic separation of materials, useless materials and impurities are gradually removed, which improves the quality and purity of the final product and meets the market demand for high-quality steel slag processing products. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a process flow chart for steel slag processing and purification. DETAILED DESCRIPTION

[0046] The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0047] The following examples are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the scope of protection of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0048] Example 1

[0049] See Figure 1A steel slag processing and purification system includes: a primary crushing unit, a grizzly screen device, a secondary crushing unit, a conveyor belt system, a silo loading unit, a primary screening unit, a pre-selection magnetic separation unit, a large rod mill, a secondary screening unit, a rod mill steel separation module, a magnetic separator unit, and a closed-loop circulation system;

[0050] The primary crushing unit is used to crush the raw materials to a size less than 500mm. The primary crushing unit is completed by two excavators in collaboration.

[0051] The grizzly screen device is used to screen the material after primary crushing. The sieve size of the grizzly screen device is 170mm×250mm. The undersize of the grizzly screen device directly enters the conveyor belt and mixes with the jaw crusher discharge.

[0052] The secondary crushing unit uses a secondary jaw crusher to crush the material on the grid screen, with the target particle size being ≤200mm. There are two secondary jaw crushers.

[0053] The conveyor belt system is used to mix the undersize material from the grid screen device with the secondary crushed material and transport it to the material pool;

[0054] The silo loading unit includes a forklift + silo. The silo loading unit is used to store mixed materials in the silo via a forklift.

[0055] The first-stage screening unit uses a 30mm roller screen, which is connected to the silo via conveyor belt 1. The screened material is sent to the rod mill silo via conveyor belt 2.

[0056] Pre-selection magnetic separation unit, air separation and magnetic separation heads are sequentially arranged above the large rod grinding bin to separate tailings;

[0057] Large rod mill, processing 30mm screen oversize and pre-selected magnetic materials;

[0058] The secondary screening unit adopts 10mm roller screen, which is used to sort the material discharged from the large rod mill, and the material on the screen enters the small rod mill;

[0059] The rod abrasive steel separation module uses a small rod mill. The discharge from the small rod mill is returned to a 10mm roller screen via a closed-loop belt for cyclic crushing. Above the small rod mill discharge belt are an air separator (using an electromagnetic iron remover) and a magnetic separator (using a permanent magnetic drum) to separate non-magnetic waste. The peak value of the air separator is above 10,000 gauss, while the peak value of the magnetic separator is above 5,000 gauss.

[0060] The magnetic separator unit includes a two-stage high-intensity magnetic separator with a magnetic field strength of not less than 12,000 Gauss. The magnetic separator unit is used to process the 10mm undersize of the large / small rod mill and output fine powder and tailings.

[0061] The closed-loop circulation system returns the discharge from the small rod mill to the secondary screening unit.

[0062] A method for processing and purifying steel slag, comprising:

[0063] S1, two-stage mechanical crushing to make the raw material particle size ≤200mm;

[0064] S2. Non-magnetic materials are removed through 30mm screening and pre-magnetic separation; pre-magnetic separation uses a gradient magnetic field with a gradient magnetic field of 10,000 Gauss to 5,000 Gauss;

[0065] S3, after grinding in the large rod mill, the material on the screen is screened with 10mm, and the material on the screen enters the small rod mill for closed-loop processing. The material discharged from the small rod mill is subjected to air separation to extract the rod abrasive steel, and the non-magnetic material is directly discarded;

[0066] S4. Magnetic separation and purification of the material under the sieve is carried out to collect iron ore concentrate and tailings.

[0067] Example 2

[0068] In this embodiment, a steel slag processing and purification method and system are the same as those in Example 1, with the addition of a process flow as follows:

[0069] First, two excavators are used to crush the large pieces to less than 500mm and then they are put into the sieve. The size of the sieve is 170mm*250mm. The material on the sieve is fed into two jaw crushers and crushed into small pieces below 200mm. The undersize material and the small pieces crushed by the jaw crusher are conveyed together on the conveyor belt and enter the material pool. Then, the forklift is used to load the material into the silo.

[0070] The silo material is transported by conveyor belt No. 1 to the 30mm mesh roller screen. The No. 2 under-screen conveyor conveys materials ≤30mm to the large rod mill silo. Above the silo, there is an air filter + magnetic head (air filter is 10,000 gauss, magnetic head is 5,000 gauss). Non-magnetic materials enter the tailings belt. All materials above the 30mm screen enter the large rod mill.

[0071] The material from the large rod mill enters the 10mm hole roller screen, and then enters the small rod mill. There is a space above the belt to select the rod mill grain steel;

[0072] There is a magnetic head at the end of the belt on the screen, and non-magnetic materials are no longer processed. This design allows the material to be gradually reduced, effectively reducing the processing volume of the next process. Since there is no need to process non-magnetic materials again, the purpose of high production and reduced power consumption is achieved.

[0073] The present invention uses an excavator to initially crush large pieces of material to less than 500mm, and then further processes them into small pieces below 200mm through a grid screen and a jaw crusher. This multi-stage crushing and screening method can effectively reduce the material particle size, provide a suitable particle size range for subsequent processing steps, and improve overall processing efficiency; the coordinated use of the grid screen and the jaw crusher ensures that the material entering the next step has a uniform particle size, which is beneficial to the stable operation of subsequent equipment and reduces equipment failure and wear caused by excessive or uneven material particle size; the roller screen is used to divide the material into two parts of ≤30mm and >30mm, and the material ≤30mm is subjected to air separation and magnetic separation, and the non-magnetic material can be separated in advance as tailings for discharge, reducing the amount of material entering the subsequent rod mill process, improving processing efficiency, and reducing the energy consumption of the subsequent process; the large rod mill and the small rod mill grind the materials in different particle size ranges respectively, and then screen them through the roller screen to further refine the material particle size. The material reaches a more suitable particle size range, which is beneficial to the subsequent concentrate extraction and purification; air separation and magnetic separation devices are set above and at the end of the belt to monitor and screen out non-magnetic materials in real time and discharge them, avoiding repeated processing of useless materials, reducing the system's energy consumption and equipment wear, and improving overall production efficiency; by gradually reducing the amount of material, the processing volume of subsequent processes is reduced, the operating load and energy consumption of the equipment are reduced, and the purpose of energy saving and consumption reduction is achieved, which is conducive to reducing production costs and improving economic benefits; the connection between each process is close, and the material is continuously transmitted through the conveyor belt, which ensures the continuity and stability of production, improves production efficiency, and reduces production delays and equipment downtime caused by material interruptions; through multi-stage crushing, screening, air separation and magnetic separation of the material, useless materials and impurities are gradually removed, the quality and purity of the final product are improved, and the market demand for high-quality steel slag processed products is met.

Claims

1. A method for processing and purifying steel slag, characterized in that: include: S1, two-stage mechanical crushing to make the raw material particle size ≤200mm; S2, remove non-magnetic materials through 30mm screening and pre-magnetic separation; S3, after grinding in the large rod mill, the material is screened with 10mm, and the material on the screen enters the small rod mill for closed-loop processing; S4. Magnetic separation and purification of the material under the sieve is carried out to collect iron ore concentrate and tailings.

2. The steel slag processing and purification method according to claim 1, characterized in that: In S2, the pre-magnetic separation adopts gradient magnetic field separation.

3. The steel slag processing and purification method according to claim 2, characterized in that: The gradient magnetic field is 10,000 Gauss→5,000 Gauss.

4. The method for processing and purifying steel slag according to claim 1, wherein: In S3, the rod mill output material is subjected to air separation to extract the rod abrasive steel, and the non-magnetic material is directly discarded.

5. A steel slag processing and purification system for implementing the method according to claims 1-4, characterized in that: include: Primary crushing unit, grizzly screen device, secondary crushing unit, conveyor belt system, silo loading unit, primary screening unit, pre-selection magnetic separation unit, large rod mill, secondary screening unit, rod abrasive steel separation module, magnetic separator unit, closed-loop circulation system; The primary crushing unit is used to crush the raw materials to a size less than 500mm; The grid screen device is used to screen the materials after primary crushing; The secondary crushing unit is used to crush the material on the grid screen to less than 200mm; The conveyor belt system is used to mix the undersize material from the grid screen device with the secondary crushed material and transport it to the material pool; The silo loading unit is used to store mixed materials; The first-level screening unit is connected to the silo through conveyor belt 1, and the screened material is sent to the large rod mill silo through conveyor belt 2; Pre-selection magnetic separation unit, air separation and magnetic separation heads are sequentially arranged above the large rod grinding bin to separate tailings; Large rod mill, processing 30mm screen oversize and pre-selected magnetic materials; The secondary screening unit is used to sort the material discharged from the large rod mill, and the material on the screen enters the small rod mill; Rod abrasive steel separation module (with air separation and magnetic separation heads above the small rod grinding discharge belt) is used to separate non-magnetic waste materials; The magnetic separator is used to process the 10mm undersize from the large / small rod mill and output fine powder and tailings; The closed-loop circulation system returns the discharge from the small rod mill to the secondary screening unit.

6. A steel slag processing and purification system according to claim 5, characterized in that: The primary crushing unit is completed by two or more excavators working together to complete the crushing; the secondary crushing unit uses a secondary jaw crusher to crush the material on the grid screen, with the target particle size being ≤200mm, and the number of secondary jaw crushers is at least two.

7. The steel slag processing and purification system according to claim 5, characterized in that: The sieve hole size of the sieve used in the grizzly screen device is (160-180) mm×(240-260) mm. The undersize of the grizzly screen device directly enters the conveyor belt and is mixed with the jaw crusher discharge.

8. The steel slag processing and purification system according to claim 5, characterized in that: The first-stage screening unit adopts a 30mm roller screen, and the second-stage screening unit adopts a 10mm roller screen.

9. The steel slag processing and purification system according to claim 5, characterized in that: The discharge of the small rod mill is returned to the 10mm roller screen through a belt closed loop for cyclic crushing.

10. The steel slag processing and purification system according to claim 5, characterized in that: The magnetic separator unit includes at least two stages of high-intensity magnetic separators, and the magnetic field strength is not less than 12,000 Gauss.

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