Method for reducing grade of tailings in magnetic separation process

Abstract

The invention belongs to the technical field of metallurgical magnetite beneficiation, and particularly relates to a method for reducing the grade of tailings in a magnetic separation process, which comprises the following steps: (1) determining the working clearance of a magnetic separator according to the formula H (working clearance) = h1 + 0.3 T * (100-0.615 W-0. 00265 Walpha) / LW, and adjusting the matching of the feeding concentration, the feeding quantity and the working clearance of the magnetic separator; (2) adjusting the gap of the ore discharge port of the magnetic separator according to a formula H (gap of the ore discharge port) = h < 2 > + 0.872 t * (0.6-0.00172 beta) / L; and (3) optimizing the roller structure of the magnetic separator, and adjusting the mounting position and the shape of an ore discharge water nozzle: additionally arranging a pre-ore discharge scraper, mounting the pre-ore discharge scraper at a position 150 + / -20mm above an ore discharge port of a bottom box of the magnetic separator, and mounting the ore discharge water nozzle at a position 100-120mm above the ore discharge scraper. According to the method, the optimal working clearance and the ore discharge opening clearance of the magnetic separators of different models are determined according to the length, the ore feeding amount, the ore feeding concentration, the ore feeding grade and the concentrate grade of the magnetic separators, and the tailing grade is reduced by combining an optimized ore unloading device.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical magnetite beneficiation, and in particular relates to a method for reducing the grade of tailings in a magnetic separation process. Background Art

[0002] my country is rich in iron ore resources, with proven reserves reaching 50 billion tons, ranking among the highest in the world. However, poor ore accounts for about 90%, rich ore accounts for only about 10%, and about 5% of the rich ore cannot be directly smelted due to harmful impurities. Therefore, more than 90% of the iron ore requires mineral processing.

[0003] Magnetic separation is the most common method for separating magnetite, and a semi-countercurrent magnetic separator (hereinafter referred to as a magnetic separator) is the primary equipment for magnetite separation. The slurry flow direction of the magnetic separator is consistent with that of the magnetic product and opposite to that of the non-magnetic product, resulting in high-quality iron ore concentrate and a high metal recovery rate. It is widely used to process highly magnetic ore particles smaller than 0.2 mm in size, either for roughing or concentrating. However, in mineral processing, there are the following drawbacks:

[0004] (1) The unreasonable combination of feed concentration, feed volume and working interval of magnetic separator results in high grade of magnetic separation tailings;

[0005] (2) The gap at the discharge port of the magnetic separator is large, the concentrate cannot be discharged in time, the bottom box will be blocked by siltation, and the gap at the discharge port becomes smaller, causing the magnetic separator to run black. The magnetic ore particles cannot be effectively separated, but are mixed with non-magnetic minerals, which increases the grade of the tailings.

[0006] (3) The drum belt of the magnetic separator is frequently conveyed during operation. When the amount of ore is large, the concentrate after separation directly enters the tailings mouth. The separation of magnetic minerals and non-magnetic minerals is not complete, the tailings grade increases, and the recovery rate decreases. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for reducing the grade of tailings in a magnetic separation process, so as to solve the problem that the tailings grade is high due to the unreasonable combination of magnetic separator feed concentration, feed amount and working gap, large unloading port gap and large drum belt ore volume in mineral processing production.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for reducing the grade of tailings in a magnetic separation process, comprising the following steps:

[0010] (1) According to formula H (工作间隙)=h1+0.3T*(100-0.615W-0.00265Wα) / LW Determine the working gap of the magnetic separator, adjust the feed concentration, feed amount and working gap of the magnetic separator. In the formula, h1 is the minimum working gap of the magnetic separator, unit: mm, T is the feed amount of the magnetic separator (dry ore), unit: t / h, W is the feed concentration of the magnetic separator, unit: %, L is the length of the magnetic separator drum, unit: m, α is the feed grade of the magnetic separator, unit: %:

[0011] ① When the feed concentration of the magnetic separator is ≥40%, W in the formula is calculated as 40%;

[0012] ② The feed rate of the magnetic separator must be lower than the maximum amount provided by the manufacturer;

[0013] ③ When the magnetic field strength of the magnetic separator is ≥200mT, the minimum working gap of the magnetic separator h1=40mm;

[0014] ④ When the diameter of the magnetic separator drum is ≥1200mm, the minimum working gap of the magnetic separator h1=40mm;

[0015] ⑤ When the diameter of the magnetic separator drum is ≤1000mm, the minimum working gap of the magnetic separator h1=35mm.

[0016] (2) According to formula H (卸矿口间隙) =h2+0.872t*(0.6-0.00172β) / L to adjust the magnetic separator discharge port gap. In the formula, h2 is the minimum discharge port gap of the magnetic separator, unit: mm, t is the concentrate volume (dry ore) of the magnetic separator, unit: t / h, L is the length of the magnetic separator drum, unit: m, β is the concentrate grade of the magnetic separator, unit: %:

[0017] ① When the diameter of the magnetic separator drum is ≥1200mm, h2=30mm;

[0018] ② When the diameter of the magnetic separator drum is between 900 and 1200 mm, h2 = 25 mm;

[0019] ③ When the diameter of the magnetic separator drum is ≤900mm, h2=20mm.

[0020] (3) Optimize the drum structure of the magnetic separator and adjust the installation position and shape of the unloading water nozzle: add a pre-unloading scraper, which must be made of non-magnetic material. The pre-unloading scraper is installed 150±20mm above the unloading port of the magnetic separator bottom box, and the unloading water nozzle is installed 100~120mm above the unloading scraper.

[0021] Preferably, the nozzle for unloading the mineral water in (3) is of duckbill type to reduce water consumption.

[0022] Preferably, the pre-unloading scraper in (3) is a rubber scraper or a brush scraper.

[0023] Preferably, the magnetic separator in (3) with a feed particle size of -200 mesh content ≤55% or a feed concentration ≥50% adopts a combination of a rubber scraper and a duckbill type unloading water nozzle.

[0024] Preferably, the magnetic separator in (3) with a feed particle size of -200 mesh and a content of ≥65% adopts a combination of a brush scraper and a duckbill type ore unloading nozzle.

[0025] Preferably, the magnetic separator in (3) is a concentration magnetic separator, which adopts a double-layer pre-unloading scraper, a lower rubber scraper and an upper brush scraper combination.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) According to the magnetic separator drum length, feed rate, feed concentration, feed grade and working gap formula, the optimal working space of different types of magnetic separators is obtained, so that the feed concentration, feed rate and working gap are reasonably matched to fully recover metals and reduce the tailings grade;

[0028] (2) According to the magnetic separator drum length, minimum discharge port gap, magnetic separator concentrate volume, concentrate grade and discharge port gap formula, the optimal discharge port gap of different types of magnetic separators is determined to achieve uniform ore distribution inside the magnetic separator, effectively separate the magnetic ore particles and reduce the tailings grade;

[0029] (3) Add a pre-unloading scraper and adjust the position and shape of the unloading water nozzle to prevent the concentrate from entering the tailings outlet directly when the magnetic separator drum carries a large amount of ore. The magnetic minerals and non-magnetic minerals are separated thoroughly, and the tailings grade is reduced. It is ensured that the magnetic separation process can reduce the grade of the magnetic separation tailings while ensuring the quality of the concentrate, so as to achieve the purpose of improving the recovery rate of magnetite. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is described in detail below with reference to the embodiments.

[0031] A method for reducing the grade of tailings in a magnetic separation process, comprising the following steps:

[0032] (1) According to formula H (工作间隙)=h1+0.3T*(100-0.615W-0.00265Wα) / LW to determine the working gap of the magnetic separator, adjust the feed concentration, feed amount and working gap of the magnetic separator. In the formula, h1 is the minimum working gap of the magnetic separator, unit: mm, T is the feed amount of the magnetic separator (dry ore), unit: t / h, W is the feed concentration of the magnetic separator, unit: %, L is the length of the magnetic separator drum, unit: m, α is the feed grade of the magnetic separator, unit: %: The old series of first-stage magnetic separation is equipped with 3 CTB1024 magnetic separators, with a flow rate of 188t / h, a single magnetic separator feed amount T=61.67t / h, a feed concentration W=45%, a feed grade α=31.5%, a minimum working gap h1=35mm, and a CTB1024 magnetic separator drum length of 2.4m. By the formula H (工作间隙) =h1+0.3T*(100-0.615W-0.00265Wα) / LW, the working clearance is 52mm.

[0033] (2) According to formula H (卸矿口间隙) =h2+0.872t*(0.6-0.00172β) / L Adjust the magnetic separator discharge port gap, where h2 is the minimum discharge port gap of the magnetic separator, unit: mm, t is the concentrate volume (dry ore) of the magnetic separator, unit: t / h, L is the length of the magnetic separator drum, unit: m, β is the concentrate grade of the magnetic separator, unit: %: The new series of first-stage magnetic separation is equipped with 3 CTB1230 magnetic separators, with a flow rate of 223t / h, a single magnetic separator feed rate T of 74.33t / h, a feed concentration W of 28.3%, a magnetic separator drum length L of 3.0m, a concentrate grade β of 46.5%, and a minimum discharge port gap h2 of 25mm. By the formula H (卸矿口间隙) =h2+0.872t*(0.6-0.00172β) / L, the unloading gap is 36mm.

[0034] (3) Optimize the drum structure of the magnetic separator and adjust the installation position and shape of the unloading water nozzle: add a pre-unloading scraper, which is installed 150±20mm above the unloading port of the magnetic separator bottom box, and install the unloading water nozzle 100~120mm above the unloading scraper.

[0035] ① The first stage magnetic separation particle size is -200 mesh and the content is 50±2%. It adopts pre-unloading rubber scraper and duckbill type unloading water nozzle;

[0036] ② The second to fourth stage magnetic separation particle size is -200 mesh content 75±2%, using pre-unloading brush scraper and duckbill type unloading water nozzle;

[0037] ③ Second stage concentrated magnetic separation, the concentrate concentration is required to reach more than 60%, using a double layer of pre-unloading scrapers, a lower layer of rubber scrapers and an upper layer of brush scrapers;

[0038] ④ Three-stage concentrated magnetic separation, the concentrate concentration is required to be 50-55%, and pre-unloading rubber scrapers and duckbill type unloading water nozzles are used.

[0039] The data before and after using this method are shown in the following table:

[0040]

[0041] After the implementation of this method, the TFe content of the comprehensive tailings grade of Taigang Jianshan Iron Mine decreased from 11.43% to 11.09%, and the concentrate grade increased by 0.28 percentage points, achieving a reduction in tailings grade and an increase in concentrate yield. In the second half of 2024, compared with the same period in the first half of the year, the concentrate output increased by 1.7129-1.7031=0.98 million tons after the tailings grade was reduced. The same period comparison refers to the comparison of the tailings and concentrate grades completed in the first half of the year and the tailings grades completed in the second half of the year, with the original ore volume and mill grade remaining unchanged, and the comparison of the converted concentrate yield with the corresponding concentrate volume. By determining the optimal working gap and discharge port gap of the magnetic separator and optimizing the drum unloading structure, the slurry flow rate in the bottom box of the magnetic separator is achieved to be lower than the drum speed of the magnetic separator. The separation concentration of the magnetic separator is controlled below 45%, solving the problems of bottom box blockage and uneven unloading of the magnetic separator, which has a significant effect on improving the recovery rate of magnetic concentrate and has significant economic benefits.

Claims

1. A method for reducing the grade of tailings in a magnetic separation process, characterized in that: Includes the following: (1) According to formula H (工作间隙) =h1+0.3T*(100-0.615W-0.00265Wα) / LW Determine the working gap of the magnetic separator, adjust the feed concentration, feed amount and working gap of the magnetic separator. In the formula, h1 is the minimum working gap of the magnetic separator, unit: mm, T is the feed amount of the magnetic separator (dry ore), unit: t / h, W is the feed concentration of the magnetic separator, unit: %, L is the length of the magnetic separator drum, unit: m, α is the feed grade of the magnetic separator, unit: %: ① When the feed concentration of the magnetic separator is ≥40%, W in the formula is calculated as 40%; ② The feed rate of the magnetic separator must be lower than the maximum amount provided by the manufacturer; ③ When the magnetic field strength of the magnetic separator is ≥200mT, the minimum working gap of the magnetic separator h1=40mm; ④ When the diameter of the magnetic separator drum is ≥1200mm, the minimum working gap of the magnetic separator h1=40mm; ⑤ When the diameter of the magnetic separator drum is ≤1000mm, the minimum working gap of the magnetic separator h1=35mm; (2) According to formula H (卸矿口间隙) =h2+0.872t*(0.6-0.00172β) / L Adjust the magnetic separator discharge port gap, where h2 is the minimum discharge port gap of the magnetic separator, unit: mm, t is the dry ore concentrate volume of the magnetic separator, unit: t / h, L is the magnetic separator drum length, unit: m, β is the magnetic separator concentrate grade, unit: %: ① When the diameter of the magnetic separator drum is ≥1200mm, h2=30mm; ② When the diameter of the magnetic separator drum is between 900 and 1200 mm, h2 = 25 mm; ③ When the diameter of the magnetic separator drum is ≤900mm, h2=20mm; (3) Optimize the drum structure of the magnetic separator and adjust the installation position and shape of the unloading water nozzle: add a pre-unloading scraper, which must be made of non-magnetic material. The pre-unloading scraper is installed 150±20mm above the unloading port of the magnetic separator bottom box, and the unloading water nozzle is installed 100~120mm above the unloading scraper.

2. The method for reducing the grade of tailings in a magnetic separation process according to claim 1, wherein: The (3) middle unloading nozzle for the mineral water adopts a duckbill type to reduce water consumption.

3. The method for reducing the grade of tailings in a magnetic separation process according to claim 1, wherein: The pre-unloading scraper in (3) is a rubber scraper or a brush scraper.

4. The method for reducing the grade of tailings in a magnetic separation process according to claim 1, wherein: The magnetic separator in (3) with feed particle size of -200 mesh and content ≤55% or feed concentration ≥50% adopts a combination of a rubber scraper and a duckbill type ore unloading water nozzle.

5. The method for reducing the grade of tailings in a magnetic separation process according to claim 1, wherein: The magnetic separator with feed particle size of -200 mesh and content ≥65% in (3) adopts a combination of a brush scraper and a duckbill type ore unloading nozzle.

6. The method for reducing the grade of tailings in a magnetic separation process according to claim 1, characterized in that: The magnetic separator in (3) is a concentration magnetic separator, which adopts a double-layer pre-unloading scraper, a lower rubber scraper and an upper brush scraper.

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