Fine-fraction steel slag resource recovery process

Abstract

The invention relates to the field of ferrous metallurgical industry, in particular to a fine-fraction steel slag resource recovery process. For fine-fraction steel slag with the particle size smaller than 10 mm, the beneficiation engineering of first-stage ore grinding and screening, first-stage magnetic separation and dewatering, second-stage ore grinding and grading, second-stage magnetic separation, concentrate filtering and tailing concentration filtering is adopted. According to the method, through stage grinding and stage magnetic separation, ultrahigh-grade particle steel with the grade not smaller than 75% and medium-grade fine iron powder with the grade larger than 45% are produced, and efficient recovery of the iron element in the steel slag is achieved.

Description

Technical Field

[0001] The invention relates to the field of iron and steel metallurgy industry, and in particular to a fine-grained slag resource recovery process. Background Art

[0002] Steel slag is a solid waste generated in the steel production process. Its composition is complex, mainly including minerals such as iron oxides, silicates and aluminates. The traditional way to deal with steel slag is mainly storage and landfill, which not only occupies a large amount of land resources, but also pollutes the environment in the long run. Although some steel slag is used as building materials, the resource utilization rate is limited because the iron element in it is not effectively recovered. Although there are some technologies trying to recover iron from steel slag, such as screening and dry separation, these technologies face the problem of low iron recovery rate during application.

[0003] On November 27, 2023, GB175-2023 "General Portland Cement" was officially released, which will replace the 2007 version and will be implemented on June 1, 2024. Since the mandatory provisions have been changed to mandatory in full, and steel slag is not included in the raw materials of cement, steel slag will be prohibited from being used as a mixed material in the production of Portland cement. my country produces about 100 million tons of steel slag each year. The implementation of the provisions will add 100 million tons of solid waste to the metallurgical industry. Therefore, it has become a top priority to develop a new process that can efficiently recover iron elements in steel slag and reduce solid waste emissions.

[0004] The existing slag treatment process is: two-stage one closed circuit crushing to 10mm, and one-stage magnetic pulley dry separation. See the attached process Figure 1 . Summary of the invention

[0005] The purpose of the present invention is to provide a new process for recovering fine-grained iron from steel slag resources below 10 mm. Through stage grinding and stage magnetic separation, ultra-high-grade particle steel with a grade of not less than 75% and medium-grade iron concentrate with a grade of more than 45% are produced, thereby realizing efficient recovery of iron elements in steel slag.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A fine-grained steel slag resource recovery process, for fine-grained steel slag below 10 mm, adopts a mineral processing project of one-stage grinding and screening - one-stage magnetic separation and dehydration - two-stage grinding and classification - two-stage magnetic separation - concentrate filtration - tailings concentration and filtration.

[0008] The specific process steps include:

[0009] 1) The steel slag enters a ball mill for open circuit grinding;

[0010] 2) The first-stage grinding products are screened to 1-5 mm, the screened materials are used as particle steel, the screened materials are subjected to first-stage weak magnetic separation, and the first-stage weak magnetic separation tailings are used as qualified tailings;

[0011] 3) The concentrate of the first stage weak magnetic separation is graded and dehydrated, and the particles on the graded dehydration screen are used as steel. The second stage grinding and classification is carried out under the graded dehydration screen, and the product is subjected to the second stage weak magnetic separation;

[0012] 4) The granular steel obtained by combining the coarse particle screening screen and the graded dewatering screen is directly stored, the second stage weak magnetic separation concentrate is disc filtered, the filter cake is stored as the iron concentrate, and the filtrate is returned to the second stage weak magnetic separation;

[0013] 5) The first stage weak magnetic separation tailings, the second stage weak magnetic separation tailings and the tailings filter press filtrate are combined and fed into the tailings thickening equipment. The tailings thickening overflow is used as circulating water, the tailings thickening underflow is subjected to tailings filter press, and the tailings filter press filter cake is discharged dry.

[0014] The classification overflow fineness of the second-stage grinding and classification operation is more than 60% of -200 mesh.

[0015] The grade of the particle steel is not less than 75%.

[0016] The grade of the iron ore concentrate is greater than 45%.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1) The ball mill performs open circuit grinding to fully realize the monomer dissociation of steel slag, providing favorable conditions for the subsequent magnetic separation process. The ball mill has the advantages of large processing capacity and good wear resistance, which overcomes the problems of small processing capacity and easy breakage of steel bars in traditional rod mills.

[0019] 2) The present invention creatively adopts 2mm coarse particle screening process for ore dressing, and recycles the medium-sized particles in the grinding products as high-grade particle steel, reducing the amount of ore entering the second-stage grinding. The use of coarse particle screening for ore dressing overcomes the problems of fast equipment wear, small processing capacity, and easy blockage in the traditional magnetic separation process.

[0020] 3) The present invention performs a weak magnetic separation on the coarse-grained undersize material, and performs graded dehydration on the magnetically separated concentrate, thereby further recovering fine-grained high-grade particle steel in the material. Graded dehydration has the advantages of simple equipment structure and low processing cost.

[0021] 4) The present invention adopts a process flow of stage grinding and stage magnetic separation, performs open circuit first-stage grinding and second-stage grinding classification by a ball mill, and then screens and magnetically separates the grinding products. This process flow can fully realize the monomer dissociation of iron elements and improve the recovery rate of iron elements.

[0022] 5) The present invention recovers steel particles and iron ore concentrate, and the tailings can be concentrated and filtered to produce building materials, thereby reducing the amount of tailings entering the tailings pond, achieving comprehensive recycling of resources, and reducing the occupation of land resources, with significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of steel slag treatment in the prior art.

[0024] Figure 2 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only for illustration and are not intended to limit the present invention.

[0026] like Figure 2 As shown, a fine-grained steel slag resource recovery process, for fine-grained steel slag below 10mm, adopts a beneficiation project of one-stage grinding and screening - one-stage magnetic separation and dehydration - two-stage grinding and classification - two-stage magnetic separation - concentrate filtration - tailings concentration filtration. The specific process steps include the following:

[0027] 1) The steel slag enters a ball mill for open circuit grinding;

[0028] 2) The first-stage grinding products are screened to 1-5 mm, the screened materials are used as particle steel, the screened materials are subjected to first-stage weak magnetic separation, and the first-stage weak magnetic separation tailings are used as qualified tailings;

[0029] 3) The concentrate of the first stage weak magnetic separation is graded and dehydrated, and the particles on the graded dehydration screen are used as steel. The second stage grinding and classification is carried out under the graded dehydration screen, and the product is subjected to the second stage weak magnetic separation;

[0030] 4) The granular steel obtained by combining the coarse particle screening screen and the graded dewatering screen is directly stored, the second stage weak magnetic separation concentrate is disc filtered, the filter cake is stored as the iron concentrate, and the filtrate is returned to the second stage weak magnetic separation;

[0031] 5) The first stage weak magnetic separation tailings, the second stage weak magnetic separation tailings and the tailings filter press filtrate are combined and fed into the tailings thickening equipment. The tailings thickening overflow is used as circulating water, the tailings thickening underflow is subjected to tailings filter press, and the tailings filter press filter cake is discharged dry.

[0032] Embodiment 1: The raw materials of the embodiment of the present invention are steel slag from Handan Taihang Iron and Steel, the ore grade of which is 32.75%, and the main components of the steel slag are magnetic iron, hematite, metallic iron, etc.

[0033] First, steel slag with a particle size of less than 10mm is put into the ball mill for coarse grinding, using wet grinding and open-circuit grinding. The grinding products are screened on a 2mm linear screen. The products on the screen are used as particle steel and stored in the particle steel warehouse. The products under the screen enter the first weak magnetic separation operation. The tailings of the first weak magnetic separation enter the tailings concentration operation. The first weak magnetic separation concentrate is dehydrated and screened. The product is used as particle steel and stored in the particle steel warehouse. The dehydrated and screened under the screen enters the second grinding and classification operation. The overflow fineness of the classification is -200 mesh 90%. The classified products enter the second weak magnetic separation, and the tailings of the second weak magnetic separation enter the tailings concentration. The concentrate is used as iron concentrate. After concentrate filtration, the filter cake enters the iron concentrate warehouse. The concentrate filtrate returns to the second weak magnetic separation. The tailings of the second weak magnetic separation are tailings concentrated and filtered, and the filter cake enters the tailings warehouse. The tailings from the first and second stage weak magnetic separation and the tailings filtration filtrate enter the tailings concentration, the tailings concentration overflow is used as circulating water, the tailings concentration underflow enters the tailings filtration operation, the tailings filtration cake is sent to the tailings pile for storage, and the tailings filtration filtrate returns to the tailings concentration. The grade of the particle steel in the embodiment is 90%. The grade of the iron ore concentrate is 60%.

Claims

1. A fine-grained slag resource recovery process, characterized in that: For fine-grained steel slag below 10mm, the beneficiation project adopts one-stage grinding and screening - one-stage magnetic separation and dehydration - two-stage grinding and classification - two-stage magnetic separation - concentrate filtration - tailings concentration and filtration.

2. The new process for recycling fine-grained steel slag resources according to claim 1 is characterized in that: The specific process steps include: 1) The steel slag enters a ball mill for open circuit grinding; 2) The first-stage grinding products are screened to 1-5 mm, the screened materials are used as particle steel, the screened materials are subjected to first-stage weak magnetic separation, and the first-stage weak magnetic separation tailings are used as qualified tailings; 3) The concentrate of the first stage weak magnetic separation is graded and dehydrated, and the particles on the graded dehydration screen are used as steel. The second stage grinding and classification is carried out under the graded dehydration screen, and the product is subjected to the second stage weak magnetic separation; 4) The granular steel obtained by combining the coarse particle screening screen and the graded dewatering screen is directly stored, the second stage weak magnetic separation concentrate is disc filtered, the filter cake is stored as the iron concentrate, and the filtrate is returned to the second stage weak magnetic separation; 5) The first stage weak magnetic separation tailings, the second stage weak magnetic separation tailings and the tailings filter press filtrate are combined and fed into the tailings thickening equipment. The tailings thickening overflow is used as circulating water, the tailings thickening underflow is subjected to tailings filter press, and the tailings filter press filter cake is discharged dry.

3. A new process for recycling fine-grained steel slag resources according to claim 1 or 2, characterized in that: The classification overflow fineness of the second-stage grinding and classification operation is more than 60% of -200 mesh.

4. A new process for recycling fine-grained steel slag resources according to claim 1 or 2, characterized in that: The grade of the particle steel is not less than 75%.

5. A new process for recycling fine-grained steel slag resources according to claim 1 or 2, characterized in that: The grade of the iron ore concentrate is greater than 45%.

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