A fine classification and sorting method for fine-grained magnetite coarse concentrate

Abstract

The invention discloses a fine classification and sorting method for fine-grained magnetite coarse concentrate, wherein the fine-grained magnetite coarse concentrate is fed into a double overflow three-product hydrocyclone for classification, and an inner overflow product, an outer overflow product and an underflow product are obtained respectively; the underflow product is fed into a high-frequency fine screen for screening, and an over-screen product and an under-screen product are obtained; the under-screen product and the inner overflow product are combined and fed into a two-stage weak magnetic separation operation, and the outer overflow product is fed into a primary weak magnetic roughing selection I, a primary weak magnetic concentrating selection I, and a magnetic separation column selection to form a three-stage weak magnetic separation operation, and finally a total concentrate with an iron grade of ≥65.0% is obtained; the tailings obtained by the magnetic separation column selection are medium ore; the tailings obtained by the primary weak magnetic roughing selection I and the tailings obtained by the primary weak magnetic concentrating selection I are combined into the final tailings, and the over-screen product obtained and the medium ore obtained by the magnetic separation column selection are combined and fed into the subsequent grinding and selection operation. The method of the invention can achieve the advanced fineness before grinding, greatly reducing the subsequent grinding amount, and has the advantages of energy saving and good economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetite beneficiation, and in particular relates to a method for fine classification and efficient separation of fine-grained magnetite coarse concentrate, which can obtain iron concentrate in advance without grinding. Background Art

[0002] Fine-grained magnetite refers to an ore with a fine particle size of mineral embedding that requires fine grinding to separate into monomers. It usually refers to an ore that is ground to less than 43μm and the degree of separation of the target mineral monomer reaches more than 90%. At present, there are two main types of large-scale iron ore dressing plants in China. One is a dressing plant that mainly processes magnetite; the other is a dressing plant that mainly processes hematite (including a small amount of limonite, specularite, and siderite). Among them, the output of magnetite concentrate accounts for about 3 / 4 of my country's iron ore concentrate output, and most iron mines at home and abroad are mainly targeting these two types of ores in terms of mineral processing technology innovation. In addition, most of the overseas iron ore resources controlled by my country's mining enterprises have poor ore properties and poor ore selectivity, which are mainly manifested in the general fine particle size of the ore, high impurity content, and the ore type is mainly low-grade fine-grained magnetite ore, and the resource reserves with mining rights are more than 20 billion tons.

[0003] The main problems of fine-grained magnetite beneficiation are as follows: ① The useful minerals are embedded in fine particles, and generally two to three stages of grinding are required. It takes a lot of energy to crush them to monomer dissociation; and the accompanying over-crushing phenomenon not only wastes energy but also worsens the subsequent sorting indicators; therefore, the classification of grinding products is particularly important. ② For magnetite ores with fine embedded particles, stage grinding-weak magnetic roughing-reverse flotation selection is generally used for treatment, and the addition of various chemical agents during the flotation process causes certain pollution to the environment; therefore, it is necessary to find a process that can replace the reverse flotation operation and obtain qualified concentrate without further grinding treatment. ③ When processing materials with fine particle sizes, among the more commonly used classification equipment, the classification efficiency of gravity sedimentation classification equipment (spiral classifier, etc.) and fine screens is low, while the cyclone based on the principle of centrifugal sedimentation has certain advantages, but the traditional cyclone has the problems of wide classification product particle size, overflow coarseness, and underflow fineness. Therefore, it is still necessary to improve the classification efficiency and quality of the cyclone by improving its structure and classification parameters.

[0004] The traditional fine-grained and ultra-fine-grained magnetite beneficiation process requires fine grinding to obtain iron concentrate. Since it is impossible to obtain iron concentrate in the case of coarse particles, the energy consumption is extremely high. In order to solve the technical problems of long magnetite separation process and high energy consumption of fine-grained and micro-fine magnetite, Chinese patent application 201711107180.3 discloses an energy-saving beneficiation method for processing micro-fine magnetite. The beneficiation method sequentially performs the first-stage grinding and classification, the first-stage weak magnetic separation, the second-stage grinding and classification, the second-stage weak magnetic separation, the first-stage washing magnetic separation, the third-stage grinding and classification, the third-stage weak magnetic separation, and the second-stage washing magnetic separation on the iron ore, and the first-stage washing magnetic separation concentrate and the second-stage washing magnetic separation concentrate are combined into a total concentrate, and all the weak magnetic separation tailings are combined into a total tailings. The method adopts the washing magnetic separation technology to early harvest the magnetite minerals that have been basically monomerized under the condition of coarser grinding fineness, and the yield of the early-harvested iron concentrate reaches 15% to 45%, which greatly reduces the amount of ore that needs to be finely ground later and saves grinding energy consumption. However, this method still requires secondary grinding to obtain iron concentrate, and the energy consumption is still relatively high. In addition, this method uses washing magnetic separation, which has a small processing capacity and low sorting accuracy. It is already a backward and obsolete mineral processing technology and is basically not used in industrial production.

[0005] The research on fine classification technology is of great significance to reduce the over-crushing of fine-grained materials and reduce the energy consumption of grinding. Through the narrow-size selection, the dressing efficiency and sorting accuracy can be effectively improved, and qualified concentrates and tailings can be obtained in advance, which is in line with the concept of "early collection when possible and early disposal when possible". It is especially important to develop efficient, low-cost and environmentally friendly fine-grained magnetite classification and sorting technology based on the characteristics of my country's overseas iron ore resources, which is directly related to the speed of Chinese companies' overseas resource development process. Therefore, it is of great significance to develop a fine classification and efficient sorting process for fine-grained magnetite coarse concentrate. Summary of the invention

[0006] The purpose of the present invention is to solve the problems of high energy consumption and poor efficiency in the existing direct grinding process of fine-grained magnetite coarse concentrate, and to provide a fine-grained magnetite coarse concentrate fine grading and sorting method that can obtain high-yield, high-recovery and high-grade iron concentrate without grinding. The fine grading and sorting method obtains iron concentrate by pre-grinding grading and sorting, thereby greatly reducing the subsequent grinding amount and significantly reducing the grinding energy consumption.

[0007] To achieve the above-mentioned purpose of the present invention, a fine-grained magnetite coarse concentrate fine classification and sorting method is provided in the present invention, which adopts the following processes and steps for sorting:

[0008] (1) Fine-grained magnetite concentrate with an iron grade of 48.0% to 56.0% and a particle size of -0.076 mm accounting for 65.0% to 78.0% is fed into a double overflow three-product hydrocyclone for classification, and three products with significantly different particle size composition and dissociation characteristics are obtained, namely: inner overflow product, outer overflow product and underflow product.

[0009] The cylinder of the double overflow three-product hydrocyclone is cylindrical, with an inner diameter of 50mm-70mm and a cylinder height of 100mm-150mm. The overflow pipe is a double overflow pipe structure with different diameters. The diameters of the inner and outer overflow pipes are 12mm-15mm and 20mm-30mm respectively. The product discharged from the inner overflow pipe is the inner overflow, and the product discharged from the outer overflow pipe is the outer overflow.

[0010] The feed concentration of the double overflow three-product hydrocyclone is preferably between 20% and 40%, preferably between 25% and 30%; the feed pressure of the double overflow three-product hydrocyclone is generally between 0.08MPa and 0.15MPa, preferably between 0.11MPa and 0.13MPa.

[0011] The particle size of the double overflow three-product hydrocyclone in the method of the present invention is d 内溢流 <d 外溢流 <d 底流 .

[0012] (2) The underflow product obtained in step (1) is fed into a high-frequency fine screen for screening to obtain an oversize product and an undersize product.

[0013] The mesh size of the high-frequency fine screen is 0.07 mm to 0.1 mm.

[0014] (3) The undersize product obtained in step (2) and the internal overflow product obtained in step (1) are combined and fed into a two-stage weak magnetic separation operation. The process of the two-stage weak magnetic separation operation is a primary weak magnetic roughing selection II and a primary weak magnetic concentration II. The concentrate of the primary weak magnetic concentration II is an iron concentrate. The tailings of the primary weak magnetic roughing selection II and the tailings of the primary weak magnetic concentration II are combined into the final tailings.

[0015] The magnetic induction intensity of the primary weak magnetic roughing II is 0.2T to 0.3T, and the magnetic induction intensity of the primary weak magnetic concentrating II is 0.1T to 0.2T.

[0016] (4) the overflow product obtained in step (1) is fed into three-stage weak magnetic separation operations, wherein the three-stage weak magnetic separation operations are primary weak magnetic roughing I, primary weak magnetic concentration I, and magnetic column concentration; the concentrate obtained by magnetic column concentration is an iron concentrate, and the iron concentrate and the iron concentrate obtained in step (3) are combined into a total concentrate with an iron grade of ≥65.0%; the tailings obtained by magnetic column concentration are middlings; the tailings obtained by primary weak magnetic roughing I and the tailings obtained by primary weak magnetic concentration I are combined into final tailings;

[0017] (5) The oversize product obtained in step (2) and the middling ore obtained in step (4) are combined and fed into subsequent grinding and selection operations.

[0018] Furthermore, in step (4), the magnetic induction intensity of the primary weak magnetic roughing selection I is 0.2T to 0.3T, and the magnetic induction intensity of the primary weak magnetic fine selection I is 0.1T to 0.2T; the magnetic induction intensity of the magnetic column selection is 0.02T to 0.03T, the separation magnetic field period of the magnetic column selection is 2s to 3s, and the rising water volume is 200ml / s to 300ml / s.

[0019] The results of research and testing show that the dissociation degree of the five products obtained by steps (1) and (2) is dd 底流筛下 ≈dd 内溢流 >dd 外溢流 >dd 底流 >dd 底流筛上。

[0020] Compared with the prior art, the fine-grained magnetite coarse concentrate fine classification and separation method of the present invention has the following innovative and beneficial effects:

[0021] (1) The method of the present invention adopts a double overflow three-product hydrocyclone and a high-frequency fine screen combined classification process to obtain five classified products with different particle sizes and different dissociation degrees, thus creating conditions for fine sorting.

[0022] (2) The method of the present invention can obtain iron concentrate with a yield of more than 60% and an iron grade of more than 65.0% in advance through fine sorting without grinding. On the one hand, it can achieve early fineness before grinding, and on the other hand, it greatly reduces the amount of subsequent grinding, which has significant advantages such as energy saving and consumption reduction and good economic benefits.

[0023] (3) The method of the present invention achieves refined classification by precisely controlling the feed pressure, feed concentration and cyclone structural parameters of the double overflow three-product hydrocyclone, thereby obtaining three products with significantly different selectivities.

[0024] (4) Narrow particle size separation is one of the main means to improve the efficiency and accuracy of mineral processing. The present invention fully achieves the purpose of narrow particle size separation through a multi-product hydrocyclone and fine screen combined classification process.

[0025] (5) The method of the present invention, according to the particle size and dissociation degree of different graded screening products, respectively combines the under-screen product and the internal overflow product into a two-stage weak magnetic separation operation consisting of "first weak magnetic roughing II, first weak magnetic fine selection II", and feeds the external overflow product into a three-stage weak magnetic separation operation of "first weak magnetic roughing I, first weak magnetic fine selection I, magnetic separation column fine selection", thereby achieving narrow particle size fine separation, and finally obtaining the mineral processing technical indicators of iron recovery rate greater than 75.0% and iron concentrate grade greater than 65.0 before grinding. The research and calculation results show that compared with the mineral processing process of all fine grinding and then selection, the grinding and selection energy consumption of the method of the present invention is reduced by more than 45.0%, and the total iron recovery rate is increased by more than 5%. Taking the annual processing of 3 million tons of fine-grained magnetite rough concentrate as an example, more than 100,000 tons of iron concentrate with TFe greater than 65.0% can be recovered each year, and the annual sales volume can be increased by more than 90 million yuan, achieving unexpected technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a principle flow chart of a method for fine-grained magnetite coarse concentrate fine classification and sorting of the present invention;

[0027] Figure 2 The present invention is a quality flow chart of a fine-grained magnetite coarse concentrate fine classification and sorting method. DETAILED DESCRIPTION

[0028] To further describe the present invention, a method for fine classification and separation of fine-grained magnetite coarse concentrate of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0029] Depend on Figure 1 The invention shown is a flow chart of the principle of a fine-grained magnet coarse concentrate fine classification and separation method of the present invention and combined with Figure 2 It can be seen that the fine-grained magnetite coarse concentrate fine classification and separation method of the present invention is implemented by the following steps:

[0030] The fine-grained magnetite coarse concentrate sample used in the embodiment of the fine-grained magnetite coarse concentrate fine classification and sorting method of the present invention is taken from the weak magnetic separation coarse concentrate of Shandong Hualian Mining Co., Ltd. The iron grade of the sample is 52.96%, and the content of -0.076mm particle size in the sample accounts for 74.78%. The particle size composition and metal content distribution of the sample are shown in Table 1.

[0031] Table 1 Sample particle size composition and metal content distribution

[0032]

[0033] (1) The fine-grained magnetite concentrate is subjected to double overflow three-product hydrocyclone classification to obtain three products with significantly different particle size composition and dissociation characteristics, namely, inner overflow product, outer overflow product and underflow product; the particle size composition and metal content distribution of the three products are shown in Table 2, Table 3 and Table 4;

[0034] Table 2 Internal overflow particle size composition and metal content distribution

[0035]

[0036]

[0037] Table 3 Overflow particle size composition and metal content distribution

[0038]

[0039] Table 4 Underflow particle size composition and metal content distribution

[0040]

[0041] The cylinder of the three-product hydrocyclone with double overflow is cylindrical, with a diameter of 50mm, a cylinder height of 110mm, and a bottom flow port diameter of 8mmmm. The overflow pipe has a double overflow pipe structure with different diameters. The diameters of the inner and outer overflow pipes are 12mm and 20mm respectively. The product discharged from the inner overflow pipe is the inner overflow, and the product discharged from the outer overflow pipe is the outer overflow.

[0042] The feed concentration of the double overflow three-product hydrocyclone is 30% and the feed pressure is 0.12MPa;

[0043] (2) The underflow product obtained in step (1) is screened by a high-frequency fine screen to obtain an oversize product and an undersize product; the mineral dissociation degrees of the internal overflow, external overflow and undersize products are shown in Table 5;

[0044] Table 5 Analysis of mineral dissociation degree of internal overflow, external overflow and underflow screen products

[0045]

[0046] The mesh size of the high-frequency fine sieve is 0.076 mm;

[0047] (3) combining the undersize product obtained in step (2) and the internal overflow product obtained in step (1) to feed into a second-stage weak magnetic separation operation, wherein the process of the second-stage weak magnetic separation operation is a primary weak magnetic roughing selection II and a primary weak magnetic concentrating selection II, wherein the concentrate of the primary weak magnetic concentrating selection II is an iron concentrate, and the tailings of the primary weak magnetic roughing selection II and the tailings of the primary weak magnetic concentrating selection II are combined into the final tailings;

[0048] The magnetic induction intensity of the primary weak magnetic roughing II is 0.2T, and the magnetic induction intensity of the primary weak magnetic concentrating II is 0.12T;

[0049] (4) the overflow product obtained in step (1) is fed into three-stage weak magnetic separation operations, wherein the three-stage weak magnetic separation operations are primary weak magnetic roughing I, primary weak magnetic concentration I, and magnetic column concentration; the concentrate obtained by magnetic column concentration is an iron concentrate, and the iron concentrate and the iron concentrate obtained in step (3) are combined into a total concentrate with an iron grade of ≥65.0%; the tailings obtained by magnetic column concentration are middlings; the tailings obtained by primary weak magnetic roughing I and the tailings obtained by primary weak magnetic concentration I are combined into final tailings;

[0050] The magnetic induction intensity of the weak magnetic roughing I is 0.2T, and the magnetic induction intensity of the weak magnetic concentrating I is 0.12T; the separation magnetic field cycle of the magnetic column concentrating is 2 seconds, the magnetic induction intensity is 0.02T, and the rising water volume is 220ml / s;

[0051] (5) combining the oversize product obtained in step (2) and the middling ore obtained in step (4) and feeding them into subsequent grinding and selection operations;

[0052] Through the above process, iron concentrate with a yield of 61.20%, an iron grade of 65.83% and an iron recovery rate of 76.42% can be obtained in advance.

Claims

1. A fine classification and sorting method for fine-grained magnetite concentrate, characterized in that Use the following steps: (1) A fine-grained magnetite concentrate with an iron grade of 48.0% to 56.0% and a particle size of -0.076 mm accounting for 65.0% to 78.0% is fed into a double overflow three-product hydrocyclone for classification to obtain an inner overflow product, an outer overflow product and an underflow product respectively; the cylinder of the double overflow three-product hydrocyclone is cylindrical, with an inner diameter of 50 mm to 70 mm and a cylinder height of 100 mm to 150 mm, and the overflow pipe is a double overflow pipe structure with different diameters, the diameters of the inner overflow pipe and the outer overflow pipe are 12 mm to 15 mm and 20 mm to 30 mm respectively, the product discharged from the inner overflow pipe is the inner overflow, and the product discharged from the outer overflow pipe is the outer overflow; (2) feeding the underflow product obtained in step (1) into a high-frequency fine screen for screening to obtain an oversize product and an undersize product; (3) combining the undersize product obtained in step (2) and the internal overflow product obtained in step (1) and feeding them into a second-stage weak magnetic separation operation, wherein the process of the second-stage weak magnetic separation operation is a primary weak magnetic roughing selection II and a primary weak magnetic concentrating selection II, wherein the concentrate of the primary weak magnetic concentrating selection II is an iron concentrate, and the tailings of the primary weak magnetic roughing selection II and the tailings of the primary weak magnetic concentrating selection II are combined into the final tailings; (4) The overflow product obtained in step (1) is fed into a three-stage weak magnetic separation operation, wherein the three-stage weak magnetic separation operation comprises a primary weak magnetic roughing I, a primary weak magnetic concentrating I, and a magnetic column concentrating operation. The concentrate obtained by the magnetic column concentrating operation is an iron concentrate, and the iron concentrate is combined with the iron concentrate obtained in step (3) to form a total concentrate with an iron grade of ≥65.0%; the tailings obtained by the magnetic column concentrating operation are middlings; the tailings obtained by the primary weak magnetic roughing I and the tailings obtained by the primary weak magnetic concentrating I are combined to form a final tailings; (5) The oversize product obtained in step (2) and the middlings obtained in step (4) are combined and fed into subsequent grinding and selection operations.

2. A fine-grained magnetite rough concentrate fine classification and sorting method as claimed in claim 1, characterized in that: The feed concentration of the double overflow three-product hydrocyclone is 20%~40%, and the feed pressure is 0.08MPa~0.15MPa.

3. A fine-grained magnetite coarse concentrate fine classification and separation method as claimed in claim 1 or 2, characterized in that: In step (2), the mesh size of the high-frequency fine screen is 0.07 mm to 0.1 mm.

4. A fine-grained magnetite coarse concentrate fine classification and separation method as claimed in claim 3, characterized in that: In step (3), the magnetic induction intensity of the primary weak magnetic roughing II is 0.2T~0.3T, and the magnetic induction intensity of the primary weak magnetic concentrating II is 0.1T~0.2T.

5. A fine-grained magnetite coarse concentrate fine classification and separation method as claimed in claim 4, characterized in that: In step (4), the magnetic induction intensity of the primary weak magnetic roughing selection I is 0.2T~0.3T, and the magnetic induction intensity of the primary weak magnetic concentrating selection I is 0.1T~0.2T; the magnetic induction intensity of the magnetic column concentrating is 0.02T~0.03T, the separation magnetic field period of the magnetic column concentrating is 2s~3s, and the rising water volume is 200ml / s~300ml / s.

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