A process for precise pre-concentration of magnetite associated with sulphide ores by high pressure roller milling

Abstract

The present application belongs to the technical field of ore dressing, and relates to a kind of associated sulphide ore's magnetite high pressure roller mill accurate preselection process, adopts "12-2mm high pressure roller mill + wet magnetic separation + 2mm wet screening" full closed circuit high pressure roller mill process, realizes "more crushing less grinding, energy can throw early", reaches the purpose of energy saving and consumption reduction;High pressure roller mill products adopt wet magnetic separation of external drive magnetic separator, the process is simple, the tailing throwing effect is good, and the iron recovery rate is high. The product under the high pressure roller mill screen has been rolled by the high pressure roller mill, and the grindability has been improved, which is beneficial to the energy saving and consumption reduction of the grinding system.

Description

Technical Field

[0001] This invention belongs to the field of ore beneficiation technology, and more specifically, relates to a high-pressure roller mill precision pre-selection process for magnetite associated with sulfide minerals. Background Technology

[0002] The characteristics of Chinese iron ore are "low quality, fine texture, and complex composition," resulting in high iron concentrate production costs. Therefore, it is essential to adopt efficient, energy-saving, and low-cost beneficiation methods to comprehensively recover various elements and waste rock in order to improve market competitiveness. The basic principles of efficient beneficiation are "more crushing and less grinding," "early disposal where possible," "quality improvement and impurity reduction," and "comprehensive utilization." Based on these principles, it is necessary to adopt the latest high-efficiency equipment and supporting process technologies tailored to the characteristics of different ores to achieve the goals of energy saving, cost reduction, quality improvement, and efficiency enhancement. Relatively economical beneficiation methods for magnetite ore include weak magnetic dry separation of large lumps (large lump dry separator, magnetic pulley) and fine-grained weak magnetic wet separation.

[0003] High-pressure roller mills are a new type of crushing equipment developed in the 1980s based on the principle of hydrostatic crushing. They feature significant advantages such as small footprint, simple structure, large processing capacity, high grinding ratio, low unit energy consumption, and low wear. Currently, they are widely used in metallurgical mines in my country as ultrafine crushing equipment. Compared with conventional grinding processes, high-pressure roller mills offer strong process adaptability, ease of automatic control, improved ore grindability, wet coarse particle removal, energy saving, reduced consumption, and lower investment and operating costs. Currently, the high-pressure roller mill ultrafine crushing processes used in magnetite mines mainly include "high-pressure roller mill + wet screening closed-loop + under-screen wet magnetic separation for tailings removal + magnetic separation rough concentrate entering the grinding system" and "high-pressure roller mill + dry screening closed-loop + under-screen wet magnetic separation for tailings removal + magnetic separation rough concentrate entering the grinding system," etc. In magnetite mines, the conventional feed particle size for high-pressure roller mills is 20-60 mm, and the particle size range for closed-circuit screening is 3-5 mm. For example, the feed particle size of high-pressure roller mills at Maanshan Iron & Steel Nanshan Mining Company's Aoshan Beneficiation Plant, Fujian Makeng Iron Mine Beneficiation Plant, and Inner Mongolia Shibao Iron Mine Beneficiation Plant is 20 mm, and the particle size for wet closed-circuit screening is 3 mm. By controlling the roller mill particle size to -3 mm through wet screening in high-pressure roller mills and implementing wet magnetic separation to remove tailings, the feed rate to the mill is reduced, the grade of the raw ore is improved, and the goal of cost reduction and efficiency improvement is achieved. However, when this type of high-pressure roller mill process processes magnetite with associated sulfide minerals, the associated sulfide minerals (chalcopyrite, pyrite) in the raw ore are non-magnetic valuable minerals and enter the tailings, causing the loss of valuable minerals and adversely affecting economic benefits.

[0004] For example, the invention patent (application number: CN201810728974.X) "High-pressure roller mill wet pre-selection-stage grinding-fine screening tower magnetic separation process for magnetite" adopts a closed-loop process of high-pressure roller mill wet screening, with wet pre-selection implemented at -3mm to reduce the amount of raw ore entering the mill. This process is only suitable for single magnetite ore. If it contains associated sulfide minerals such as pyrite or chalcopyrite that need to be comprehensively recovered, these sulfide minerals will enter the tailings, resulting in the loss of associated sulfide minerals. Summary of the Invention

[0005] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a high-pressure roller mill precision pre-selection process for magnetic ore that can comprehensively recover associated sulfide ores. By performing wet pre-selection and tailings removal on the fine crushed product and high-pressure roller mill ultra-fine crushing and tailings removal processes, the particle size entering the mill is reduced, the amount of raw ore entering the ball mill is reduced, the grade entering the mill is improved, and associated sulfide ores and waste rock resources are comprehensively utilized. This process has the effects of energy saving, consumption reduction, and efficiency improvement, while comprehensively recovering associated sulfide ores and waste rock resources.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0007] A high-pressure roller mill precision pre-selection process for magnetite associated with sulfide minerals includes the following steps:

[0008] a) The raw ore is crushed to -12mm and subjected to wet medium-intensity magnetic separation to obtain magnetic concentrate and magnetic tailings;

[0009] b) The magnetic concentrate obtained in step a) is screened by a vibrating screen to obtain the oversize product and the undersize product. The undersize product enters the grinding and beneficiation system of the concentrator.

[0010] c) The product on the vibrating screen obtained in step b) is subjected to high-pressure roller mill for ultrafine crushing to obtain the discharge product of the high-pressure roller mill;

[0011] d) Perform magnetic separation on the high-pressure roller mill discharge product obtained in step c) to obtain magnetic concentrate and magnetic tailings;

[0012] e) The magnetic separation tailings obtained in steps a) and d) are screened by a vibrating screen to obtain the oversize and undersize products of the vibrating screen.

[0013] f) The magnetic concentrate obtained in step d) is returned to the linear vibrating screen in step b) and mixed with the magnetic concentrate in step a) as feed for the linear vibrating screen.

[0014] Preferably, in step a), the TFe grade of the raw ore is 30-40%, the mFe grade is 25.8-35.0%, the Cu grade is 0.02-0.09%, and the S grade is 1.5-3.2%.

[0015] Preferably, in step a), the magnetic separator is an external magnetic separator with a drum rotation speed of 8-16 rpm, a slope of 9-12 degrees, a feed solid mass concentration of 30-50%, and a magnetic field strength of 350-450 mT.

[0016] Preferably, in step b), the vibrating screen should be a linear vibrating screen with a screen aperture size of 2mm.

[0017] Preferably, in step c), the high-pressure roller mill has a pinned roller surface, requiring full ore filling, and the roller surface pressure is 4.5-5.5 N / mm. 2 .

[0018] Preferably, in step d), the magnetic separator is an external magnetic separator or a wet magnetic separator, with a drum rotation speed of 8-16 rpm, a slope of 9-12 degrees, a feed solid mass concentration of 30-50%, and a magnetic field strength of 350-450 mT.

[0019] Preferably, in step e), the vibrating screen is a linear vibrating screen with a screen aperture size of 1 mm.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] (1) Wet magnetic separation is implemented for fine crushed products of -12mm. This reduces the output of subsequent operations to the greatest extent by discarding tailings, and reduces the equipment model and specifications, which is conducive to reducing investment and costs. Because the magnetic separation concentrate product smaller than 12mm has low concentration and high moisture content, it cannot be directly fed into the high-pressure roller mill. It is screened by a linear vibrating screen of 2mm. The moisture content of the 12-2mm product on the screen is controlled below 6%, which meets the requirements for entering the high-pressure roller mill. The particle size under the screen is controlled below 2mm, which can be directly fed into the subsequent grinding system, which also reduces the load on the high-pressure roller mill.

[0022] (2) This application adopts a fully closed-circuit high-pressure roller mill process of "12-2mm high-pressure roller mill + wet magnetic separation + 2mm wet screening", which realizes "more crushing and less grinding, and early discarding when possible", achieving the purpose of energy saving and consumption reduction. The high-pressure roller mill product adopts wet magnetic separation with external drive magnetic separator, which is simple in process, has a good tailing effect, and high iron recovery rate. The undersize product of high-pressure roller mill has been roller milled by high-pressure roller mill, which improves grindability and is conducive to energy saving and consumption reduction of grinding system.

[0023] (3) Based on the high particle size distribution of sulfide ore in tailings, the -2mm magnetic separation tailings are screened and graded by 1mm. The sulfide ore content of the oversize product is low, and it is sold as building material, which not only reduces the amount of ore in subsequent operations, but also achieves the purpose of cost reduction and efficiency improvement. The sulfide ore content of the undersize product is high, and it enters the sulfide ore grinding and beneficiation system to comprehensively recover chalcopyrite and pyrite, thus comprehensively recovering sulfide ore.

[0024] (4) This invention reduces the particle size of the fine crushed product by wet pre-selection and tailings removal and high-pressure roller mill ultra-fine crushing and tailings removal process, reduces the amount of raw ore entering the ball mill, improves the grade of the fine crushed product, and makes comprehensive use of associated sulfide minerals and waste rock resources. It has the effects of energy saving, consumption reduction and efficiency improvement, while comprehensively recovering associated sulfide minerals and waste rock resources. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of a precise pre-selection process for magnetite associated with sulfide minerals according to the present invention. Detailed Implementation

[0026] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0027] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0028] Definitions:

[0029] "12-2mm high-pressure roller mill" refers to a high-pressure roller mill with a feed size of 12-2mm. Currently, the feed for high-pressure roller mills in China is for fine or medium crushed products, with a maximum feed size of 60-12mm and a minimum feed size of 0mm.

[0030] "12-2mm on the sieve" means that the feed size is 12mm and the sieve opening size is 2mm, so the product on the sieve is 12-2mm.

[0031] This application employs a fully closed-circuit high-pressure roller mill process consisting of a 12-2mm high-pressure roller mill, wet magnetic separation, and 2mm wet screening. This achieves the goals of "more crushing, less grinding, and early discarding," resulting in energy conservation and reduced consumption. The high-pressure roller mill product utilizes an externally driven wet magnetic separator, which simplifies the process, improves tailings removal, and increases iron recovery. The undersize product from the high-pressure roller mill has already undergone grinding, enhancing its grindability and contributing to energy conservation and reduced consumption in the grinding system. Compared to existing technologies, this application improves the feed particle size and closed-circuit screening particle size of the high-pressure roller mill, as well as the structure of the wet weak magnetic separator, offering advantages for the directional and precise roller milling of magnetite containing sulfide ores.

[0032] Specifically: such as Figure 1 As shown, a high-pressure roller mill precision pre-selection process for magnetite associated with sulfide minerals includes the following steps:

[0033] a) The raw ore is crushed to -12mm and subjected to wet medium-intensity magnetic separation to obtain magnetic concentrate as magnetic tailings. For example, the raw ore has a TFe grade of 30-40%, mFe grade of 25.8-35.0%, Cu grade of 0.02-0.09%, and S grade of 1.5-3.2%. An external magnetic separator (model: ZCLA5814, manufacturer: Hunan Keyuan Magnetic Equipment Co., Ltd.) is recommended, with a drum speed of 8-16 rpm, a slope of 9-12 degrees, a feed solids concentration of 30-50%, and a magnetic field strength of 350-450 mT.

[0034] b) The magnetic concentrate obtained in step a) is screened using a vibrating screen to obtain oversize and undersize products. The undersize product enters the grinding system of the concentrator. The purpose of this step is to pre-screen out some suitable fine particles directly into the ball mill system and provide suitable feed with low moisture content for the high-pressure roller mill operation. A linear vibrating screen with a screen aperture size of 2mm is recommended to effectively reduce the particle size of the high-pressure roller mill product to 2mm. The impact on subsequent processes is that the yield of magnetic separation tailings is higher, the amount of ore entering the ball mill system is less, and the energy saving and consumption reduction effect is better.

[0035] c) The product obtained from the vibrating screen in step b) is subjected to high-pressure roller milling for ultrafine crushing to obtain the discharge product of the high-pressure roller mill. The purpose of this step is to reduce the particle size of the crushed ore product and increase the grindability of the iron ore through the high-pressure roller mill. The high-pressure roller mill has a pinned roller surface and requires full feed. The roller speed of the high-pressure roller mill is 0.335 m / s, and the roller surface pressure is 4.5-5.5 N / mm. 2 The aim is to ensure that the roller surface of the high-pressure roller mill has a long service life and that the unit power consumption and product particle size are reasonable.

[0036] d) The high-pressure roller mill discharge product obtained in step c) is subjected to magnetic separation to obtain magnetic concentrate and magnetic tailings. The purpose of this step is to perform wet magnetic separation on the high-pressure roller mill discharge product to separate the liberated non-magnetic minerals into the tailings. The magnetic separator is an external magnetic drum separator with a drum speed of 8-16 rpm, a slope of 9-12 degrees, a feed solids concentration of 35%, and a magnetic field strength of 400 mT. The magnetic system of the external magnetic drum separator is located outside the separation drum, which can separate large particle sizes and can adapt to wet separation of ores with a maximum particle size of 12 mm, resulting in good separation effect.

[0037] e) The magnetic separation tailings obtained in steps a) and d) are screened using a vibrating screen to obtain the oversize and undersize products. The purpose of this step is to collect the coarse tailings for sale as building materials. The vibrating screen is a linear vibrating screen with a screen aperture size of 1 mm. This is because, based on the tailings particle size characteristics, ores larger than 1 mm have a low sulfide content and can be sold as building materials, generating better economic benefits; ores smaller than 1 mm have a high sulfide content and can enter the subsequent grinding and flotation system to recover the sulfide, thus improving the sulfide recovery rate.

[0038] f) The magnetic concentrate obtained in step d) is returned to the linear vibrating screen in step b) and mixed with the concentrate from the external magnetic separator in step a) as feed for the linear vibrating screen. The purpose of this step is to reduce the number of screening operations, facilitate production management, and improve the stability of the high-pressure roller mill products.

[0039] Example 1

[0040] This invention discloses a high-pressure roller mill precision pre-selection process for magnetite ore with associated sulfide minerals (in this embodiment, the main industrial metallic mineral in the iron ore is magnetite, containing small amounts of hematite and specular hematite. The main recoverable associated minerals are pyrite and chalcopyrite; the main gangue minerals are quartz, feldspar, chlorite, diopside, tremolite, actinolite, etc.). Figure 1 As shown, it includes the following steps:

[0041] a) The raw ore (TFe grade 35.14%, mFe grade 30.05%, Cu grade 0.046%, S grade 1.9%) was crushed to -12mm and subjected to wet magnetic separation using an external magnetic separator. The equipment model was Φ630 ZCLA, the drum speed was 14 rpm, the slope was 11 degrees, the slurry mass concentration was 35%, and the magnetic field strength was 400mT to obtain magnetic concentrate and magnetic tailings.

[0042] b) The magnetic concentrate obtained in step a) is screened by a linear vibrating screen. The equipment used is XSZ-600X300 with a screen aperture size of 2mm to obtain the oversize product and the undersize product. The undersize product enters the grinding and beneficiation system of the concentrator.

[0043] c) The product on the vibrating screen obtained in step b) is subjected to ultrafine crushing by high-pressure roller milling. The high-pressure roller mill model is GLGY0825 (roller diameter 800mm, width 250mm), the roller speed is 0.335m / s, and the roller surface pressure is 5.0N / mm. 2 , to obtain the discharge products of the high-pressure roller mill;

[0044] d) The high-pressure roller mill discharge product obtained in step c) is subjected to magnetic separation. The magnetic separation equipment is a Φ630 ZCLA with a magnetic field strength of 400mT on the cylinder surface to obtain magnetic concentrate and magnetic tailings.

[0045] e) The magnetic separation tailings obtained in steps a) and d) are screened using a vibrating screen. The equipment used is XSZ-600X300 with a screen aperture of 1mm. The vibrating screen produces oversize and undersize products. The oversize products are sold as building materials, while the undersize products are further recovered by entering the copper and sulfur flotation system of the concentrator.

[0046] f) The magnetic concentrate obtained in step d) is returned to the linear vibrating screen in step b) and mixed with the concentrate from the external magnetic separator in step a) as feed for the linear vibrating screen.

[0047] After the above processes, and following testing, the yield of the iron grinding and beneficiation system was 66.45%, with an iron grade of 47.75%, an increase of 12.61 percentage points. This tailings removal and quality improvement achieved energy saving and cost reduction. The particle size of the raw ore entering the ball mill was reduced from -12mm to -2mm, achieving energy saving in grinding costs and reducing power consumption and ball mill liner and steel ball consumption by 19.80%. The tailings yield for sale as building materials was 18.45%, with low sulfur and copper content. The sales revenue from building materials far exceeded the benefits of recovering copper and sulfur in the beneficiation plant. The magnetic separation tailings yield of -1mm was 15.10%, with higher copper and sulfur content, and was recovered in the copper and sulfur grinding and beneficiation system.

[0048] This invention reduces the particle size entering the mill, decreases the amount of raw ore entering the mill, and improves the grade entering the mill by wet pre-selection and tailings removal of fine crushed products and high-pressure roller mill ultra-fine crushing and tailings removal process. It also makes comprehensive use of associated sulfide minerals and waste rock resources, achieving the effects of energy saving, consumption reduction and efficiency improvement. At the same time, it comprehensively recovers associated sulfide minerals and waste rock resources, achieving the effect of efficient and accurate pre-selection.

Claims

1. A high-pressure roller mill precision pre-selection process for magnetite associated with sulfide minerals, characterized in that, Includes the following steps: a) The raw ore is crushed to -12mm and subjected to wet medium-intensity magnetic separation to obtain magnetic concentrate and magnetic tailings; b) The magnetic concentrate obtained in step a) is screened by a vibrating screen to obtain the oversize product and the undersize product. The undersize product enters the grinding and beneficiation system of the concentrator. c) The product on the vibrating screen obtained in step b) is subjected to high-pressure roller mill for ultrafine crushing to obtain the discharge product of the high-pressure roller mill; d) Perform magnetic separation on the high-pressure roller mill discharge product obtained in step c) to obtain magnetic concentrate and magnetic tailings; e) The magnetic separation tailings obtained in steps a) and d) are screened by a linear vibrating screen to obtain the oversize and undersize products of the vibrating screen. f) The magnetic concentrate obtained in step d) is returned to the linear vibrating screen in step b) and mixed with the magnetic concentrate in step a) as feed for the linear vibrating screen. In step c), the high-pressure roller mill has a pinned roller surface, requiring full ore feeding, and the roller surface pressure is 4.5-5.5 N / mm. 2 ; In step e), the screen aperture size of the linear vibrating screen is 1 mm.

2. The high-pressure roller mill precision pre-selection process for magnetite associated with sulfide ores according to claim 1, characterized in that, In step a), the TFe grade of the raw ore is 30-40%, the Fe grade is 25.8-35.0%, the Cu grade is 0.02-0.09%, and the S grade is 1.5-3.2%.

3. The high-pressure roller mill precision pre-selection process for magnetite associated with sulfide minerals according to claim 1, characterized in that, In step a), the magnetic separator is selected as an external magnetic separator, with a drum rotation speed of 8-16 rpm, a slope of 9-12 degrees, a feed solid mass concentration of 30-50%, and a magnetic field strength of 350-450 mT.

4. The high-pressure roller mill precision pre-selection process for magnetite associated with sulfide minerals according to claim 1, characterized in that, In step b), a linear vibrating screen with a screen aperture size of 2mm is selected.

5. The high-pressure roller mill precision pre-selection process for magnetite associated with sulfide ores according to claim 1, characterized in that, In step d), the magnetic separator is an external magnetic separator with a drum speed of 8-16 rpm, a slope of 9-12 degrees, a feed solid mass concentration of 30-50%, and a magnetic field strength of 350-450 mT.

Images