Ore grinding method for improving proportion of particle fraction of-0.074 +0.037 mm

Abstract

The invention discloses an ore grinding method for improving the proportion of the particle fraction of-0.074 + 0.037 mm, and belongs to the technical field of ore grinding. The method solves the problems that in the prior art, energy-saving and consumption-reducing measures are not taken for ore grinding operation, and energy consumption in the ore grinding operation process cannot be effectively reduced, prepared raw ore with the-3mm fraction content larger than or equal to 85% is subjected to first-stage grading and ore grinding treatment, and first-stage grading overflow is obtained; the method comprises the steps that first-stage grading overflow is subjected to second-stage grading and ore grinding treatment, finally, qualified-fraction ore with the-0.074 + 0.037 mm fraction content larger than or equal to 60% can be obtained, prepared raw ore is subjected to two-stage grading-ore grinding closed cycle operation treatment, the target fraction proportion in an ore grinding product is increased, non-target-fraction ore grinding is reduced, ore grinding energy consumption is reduced, and ore grinding efficiency is improved. Various indexes of the mineral processing technology are stabilized, and the purposes of energy conservation and consumption reduction are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of ore grinding, and in particular to an ore grinding method for increasing the proportion of a -0.074+0.037 mm particle size. Background Art

[0002] In the field of mineral processing technology, grinding operation is a necessary process in the production process of mineral processing plants and is an extremely important operation. Grinding operation is responsible for providing qualified raw materials for subsequent separation operations. The quality of grinding products directly affects the separation indicators and determines the qualified rate of the final product.

[0003] With the continuous deepening of mining of mineral resources in my country, the phenomenon of resource depletion and ore poverty and fineness has become increasingly prominent. The current production process of mineral processing plants has put forward higher requirements on technical parameters such as grinding indicators, unit energy consumption and steel consumption, which are mainly concentrated in the particle size range of -0.074+0.037mm for grinding products. It can not only complete the full monomer dissociation of minerals, but also reduce the excessive grinding of ores (referred to as "over-grinding") as much as possible, and minimize unnecessary over-grinding. The phenomenon of maximizing the energy utilization rate of grinding operations can reduce the energy consumption of grinding as much as possible.

[0004] A Chinese patent with publication number CN115254275B discloses a method for reducing the energy consumption of a high-pressure roller mill-ball mill system. The patent divides narrow particle sizes based on the calculation of the Bond ball mill work index, obtains the relative yield of each level except the particle size below the target grinding fineness, determines the multi-graded non-ferrous grinding medium size corresponding to each narrow particle size mineral in the full feed of the mill according to the calculation formula and relative yield of the non-ferrous grinding medium size, uses the multi-graded non-ferrous grinding medium size as the non-ferrous medium assembly plan of the mill to load the non-ferrous grinding medium, and performs grinding; uses a high-pressure roller mill to crush the ore in advance before it enters the mill, reduces the particle size of the ore entering the mill, and reduces the energy consumption required for the grinding operation.

[0005] However, the above patent still has the following problems in actual use: this process does not take energy-saving and consumption-reducing measures for the grinding operation itself, and cannot effectively reduce the energy consumption of the grinding operation process. In addition, its process flow has been extended at the front end, and a high-pressure roller grinding operation has been added, which cannot achieve energy saving and consumption reduction within the scope of the grinding process; therefore, it does not meet the existing needs. In this regard, we have proposed a grinding method that increases the proportion of the -0.074+0.037mm particle size. Summary of the invention

[0006] The purpose of the present invention is to provide a grinding method for increasing the proportion of -0.074+0.037mm particle size. By accurately controlling the particle size of the original ore, effective utilization of energy is achieved, and the purity and output of the mineral particle size are improved. The original ore is subjected to a two-stage "classification-grinding" closed-loop cycle operation to obtain qualified particle size ore, which solves the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a grinding method for increasing the proportion of -0.074+0.037 mm particle size, comprising the following steps:

[0008] Step 1: Prepare the crushed ore, and the ore particle size range is controlled within -3mm particle content ≥85%;

[0009] Step 2: feeding the raw ore described in step 1 into a stage of classification performed by a hydrocyclone to obtain a stage of classification overflow and a stage of classification return sand;

[0010] Step 3: feeding the first-stage graded return sand obtained in step 2 into the first-stage grinding operation to obtain a first-stage grinding product;

[0011] Step 4: returning the first-stage grinding product obtained in step 3 to the first-stage classification operation to form a first-stage grinding and classification closed-loop operation, and obtaining a first-stage classification overflow;

[0012] Step 5: feeding the first-stage classification overflow obtained in step 2 and step 4 into the second-stage classification operation to obtain the second-stage classification overflow and the second-stage classification return sand;

[0013] Step 6: Feed the second-stage classified return sand obtained in step 5 into the second-stage grinding operation to obtain the second-stage grinding product;

[0014] Step 7: Return the second-stage grinding product obtained in step 6 to the second-stage classification operation, forming a second-stage grinding and classification closed-loop operation, and obtain the second-stage classification overflow, and finally obtain qualified particle size ore.

[0015] Furthermore, the step 1 comprises the following steps:

[0016] Determine the crushing requirements of the raw ore, where the crushing requirement is that the particle size range of the raw ore is controlled within -3mm particle content ≥ 85%. At the same time, select appropriate crushing equipment and debug it. The crushing equipment uses a jaw crusher, impact crusher or cone crusher;

[0017] The raw ore is transported to the crushing equipment for crushing, and the working parameters of the crushing equipment are controlled during the crushing process, wherein the working parameters are the crushing time, speed and frequency;

[0018] After the initial crushing is completed, the obtained crushed product is subjected to particle size analysis and evaluation;

[0019] If the particle size distribution meets the pre-set crushing requirements, go directly to step 2;

[0020] If the particle size distribution does not meet the pre-set pulverization requirements, the pulverized product obtained by the primary pulverization needs to be pulverized for the second time;

[0021] The crushed products obtained from the secondary crushing are classified and screened to remove particles that do not meet the crushing requirements, and samples that meet the crushing requirements are collected and entered into step two.

[0022] Furthermore, after the initial crushing is completed, the obtained crushed product is subjected to particle size analysis and evaluation, which specifically includes the following process:

[0023] After the initial crushing, a portion of the crushed product is taken as a sample, and the number and location of the samples are randomly selected;

[0024] Using a particle size analyzer, the sampled particles are subjected to a particle size analysis to measure the particle size of the sample;

[0025] Analyze the measured particle size data and understand the particle size distribution of the original ore based on the analysis results;

[0026] The process and results of the above particle size analysis and evaluation shall be recorded and a report shall be generated.

[0027] Furthermore, in the step three, one stage of grinding is a permanent magnet driven mixed medium ball mill grinding, the permanent magnet driven mixed medium ball mill includes a permanent magnet motor 1 and a ball mill cylinder, the permanent magnet driven mixed medium ball mill uses a permanent magnet motor 1 to directly drive the ball mill cylinder, wherein the permanent magnet motor 1 is matched with a frequency converter and has a direct drive capability of 5Hz to 22Hz.

[0028] Furthermore, the permanent magnet driven mixed medium ball mill uses a mixed medium for grinding, and the mixed medium is a mixture of steel balls and ceramic balls in a certain ratio. Steel balls 15% to 22%, Steel balls 18% to 25%, Ceramic balls 15% to 20%, Ceramic balls 21% to 27% and Ceramic balls 15% ~ 20%.

[0029] Furthermore, the permanent magnet driven mixed medium ball mill adopts a high filling rate grinding method, the initial ball filling rate is 36% to 38%, the filling rate is 38% to 42% during stable production, and the permanent magnet driven mixed medium ball mill adopts a reverse spiral discharge middle section grate method to intercept the grinding medium.

[0030] Furthermore, in step six, the second-stage grinding is permanent magnet driven stratified medium vertical mill grinding, the permanent magnet driven stratified medium vertical mill includes permanent magnet motor 2 and a vertical mill spiral stirring shaft, the permanent magnet driven stratified medium vertical mill uses permanent magnet motor 2 to directly drive the vertical mill spiral stirring shaft, wherein permanent magnet motor 2 is matched with a frequency converter and has a direct drive capability of 5Hz to 50Hz.

[0031] Furthermore, the volume filling rate of the permanent magnet driven stratified medium vertical mill is 80±3%, the grinding concentration of the permanent magnet driven stratified medium vertical mill is 65±2%, the feeding method of the permanent magnet driven stratified medium vertical mill is self-flowing lower feeding with a height difference of more than 12 meters, and the discharge port of the permanent magnet driven stratified medium vertical mill is completely sealed with an arc-shaped vertical bar grate, and the curvature of the vertical bar grate is the same as the lining of the permanent magnet driven stratified medium vertical mill, and the inner side is flush with the cylinder of the permanent magnet driven stratified medium vertical mill, wherein the vertical bar hole width is 5mm~12mm, and the height is 100mm~160mm.

[0032] Furthermore, the permanent magnet driven layered medium vertical mill adopts a spatial natural layered structure of lower steel balls and upper ceramic balls for grinding, and the ceramic balls used have a diameter of 25 mm and a density of 3880 kg / m 3 The ceramic ball used has a diameter of 25 mm and a density of 3880 kg / m 3 The spatial natural layered structure is formed by 15% to 20% of steel balls as the lower layer and 80% to 85% of ceramic balls as the upper layer.

[0033] Furthermore, the permanent magnet driven mixed medium ball mill and the permanent magnet driven layered medium vertical mill are both equipped with a silencer and a shock absorbing device, wherein the shock absorbing device adopts a rubber shock isolator or a spring shock absorber.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention subjects the prepared raw ore with a -3mm particle size content ≥85% to a two-stage "classification-grinding" closed-loop cycle operation to increase the target particle size ratio in the grinding product, thereby obtaining a qualified particle size ore with a -0.074+0.037mm particle size content ≥60%, thereby reducing non-target particle size grinding, reducing grinding energy consumption, stabilizing various indicators of the mineral processing process, and achieving the purpose of energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The figure is a flow chart of the grinding method of the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In order to solve the technical problem that the existing process does not take energy-saving and consumption-reducing measures for the grinding operation itself, and cannot effectively reduce the energy consumption of the grinding operation process, and the existing process flow is extended to the front end, and the high-pressure roller grinding operation is added, and it is impossible to achieve energy saving and consumption reduction within the scope of the grinding process, please refer to Figure 1 , this embodiment provides the following technical solutions:

[0039] The grinding method for increasing the proportion of -0.074+0.037 mm particle size comprises the following steps:

[0040] Step 1: Prepare the crushed ore, and the ore particle size range is controlled within -3mm particle content ≥85%;

[0041] Step 2: feeding the raw ore described in step 1 into a stage of classification performed by a hydrocyclone to obtain a stage of classification overflow and a stage of classification return sand;

[0042] Step 3: feeding the first-stage graded return sand obtained in step 2 into a permanent magnet driven mixed medium ball mill with 65% ceramic balls and 35% steel balls as matching media for a first-stage grinding operation to obtain a first-stage grinding product;

[0043] Step 4: returning the first-stage grinding product obtained in step 3 to the first-stage classification operation to form a first-stage grinding and classification closed-loop operation, and obtaining a first-stage classification overflow;

[0044] Step 5: feeding the first-stage classification overflow obtained in step 2 and step 4 into the second-stage classification operation to obtain the second-stage classification overflow and the second-stage classification return sand;

[0045] Step 6: Feed the second-stage graded return sand obtained in step 5 into a permanent magnet driven layered medium vertical mill with 80% ceramic balls and 20% steel balls as matching media for second-stage grinding operation to obtain second-stage grinding products;

[0046] Step 7: Return the second-stage grinding product obtained in step 6 to the second-stage classification operation, forming a second-stage grinding and classification closed-loop operation, and obtain the second-stage classification overflow, and finally obtain qualified particle size ore.

[0047] The technical effect of the above content is: by crushing, an ore with a -3mm particle size content ≥85% can be obtained, and then the prepared ore is subjected to a two-stage "classification-grinding" closed-loop cycle operation, which can increase the proportion of target particle size in the grinding product, and finally obtain a qualified particle size ore. Moreover, the qualified particle size ore obtained by the grinding operation has a -0.074+0.037 particle size content that is more than 12 percentage points higher than that of the traditional ball mill, and the separation index is not lower than that of other types of grinding operations. A closed-loop cycle can be formed through two-stage "classification-grinding" operations, which can reduce non-target particle size grinding, reduce grinding energy consumption, stabilize various indicators of the mineral processing process, and achieve the purpose of energy saving and consumption reduction.

[0048] Step 1 includes the following steps:

[0049] Determine the crushing requirements of the raw ore, where the crushing requirement is that the particle size range of the raw ore is controlled within -3mm particle content ≥ 85%. At the same time, select appropriate crushing equipment and debug it. The crushing equipment uses a jaw crusher, impact crusher or cone crusher;

[0050] The raw ore is transported to the crushing equipment for crushing, and the working parameters of the crushing equipment are controlled during the crushing process, wherein the working parameters are the crushing time, speed and frequency;

[0051] After the initial crushing is completed, the obtained crushed product is subjected to particle size analysis and evaluation;

[0052] If the particle size distribution meets the pre-set crushing requirements, go directly to step 2;

[0053] If the particle size distribution does not meet the pre-set pulverization requirements, the pulverized product obtained by the primary pulverization needs to be pulverized for the second time;

[0054] The crushed products obtained from the secondary crushing are classified and screened to remove particles that do not meet the crushing requirements, and samples that meet the crushing requirements are collected and entered into step two.

[0055] The technical effect of the above content is: when determining the crushing requirements of the original ore, it is necessary to consider the range of mineral particle size and target content. These factors will affect the selection of crushing equipment and the setting of working parameters. After determining the crushing requirements, the crushing requirements are selected according to the characteristics of the original ore and the crushing requirements, and the working parameters of the crushing equipment are set, so that the original ore can be crushed more efficiently. By performing particle size analysis and evaluation on the crushed products, possible problems can be discovered in time to determine whether the crushed products have met the expected crushing requirements, so as to take corresponding measures, such as secondary crushing and readjusting the working parameters. Finally, the crushed products obtained from the secondary crushing are classified and screened to remove particles that do not meet the requirements, and then samples that meet the requirements are collected to proceed to the next step. By crushing, analyzing and secondary crushing the original ore, an ore with a -3mm particle size content ≥85% can be obtained, so that the subsequent two-stage "classification-grinding" closed-loop cycle operations can be carried out smoothly.

[0056] After the initial crushing, the obtained crushed product is subjected to particle size analysis and evaluation, which specifically includes the following processes:

[0057] After the initial crushing, a portion of the crushed product is taken as a sample, and the number and location of the samples are randomly selected;

[0058] Using a particle size analyzer, the sampled particles are subjected to a particle size analysis to measure the particle size of the sample;

[0059] Analyze the measured particle size data and understand the particle size distribution of the original ore based on the analysis results;

[0060] The process and results of the above particle size analysis and evaluation shall be recorded and a report shall be generated.

[0061] The technical effect of the above content is: by randomly selecting a part of the crushed product as a sample, it can not only ensure that the obtained sample is representative, but also effectively avoid the situation where the particle size in some areas is abnormal due to some special reasons. Then, the sample is analyzed by a particle size analyzer. Through precise data measurement, the particle size distribution of the original ore can be accurately reflected, which has a very important guiding role in the subsequent crushing operation. Next, the measured particle size data is analyzed (such as MATLAB data analysis software), and the crushing process is further optimized or the working parameters of the crushing equipment are adjusted according to the results of the analysis to make it better adapt to the particle size characteristics and crushing requirements of the original ore. Finally, the entire process and results of the particle size analysis and evaluation are recorded in detail, and a corresponding report is generated to facilitate the traceability and improvement of the entire process in the later stage.

[0062] In step three, one stage of grinding is a permanent magnet driven mixed medium ball mill grinding. The permanent magnet driven mixed medium ball mill includes a permanent magnet motor 1 and a ball mill cylinder. The permanent magnet driven mixed medium ball mill uses a permanent magnet motor 1 to directly drive the ball mill cylinder. Among them, the permanent magnet motor 1 is matched with a frequency converter and has a direct drive capability of 5Hz to 22Hz. When the permanent magnet motor 1 directly drives the mill at a frequency of 5Hz to 17Hz, it reaches 2.5 times the torque.

[0063] The permanent magnet driven mixed medium ball mill uses mixed medium for grinding. The mixed medium is a mixture of steel balls and ceramic balls in a certain proportion. Steel balls 15% to 22%, Steel balls 18% to 25%, Ceramic balls 15% to 20%, Ceramic balls 21% to 27% and Ceramic balls account for 15% to 20%, and five specifications of balls account for 100% in total.

[0064] The permanent magnet driven mixed medium ball mill adopts a high filling rate grinding method. The initial ball filling rate is 36% to 38%, and the filling rate is 38% to 42% during stable production. The permanent magnet driven mixed medium ball mill adopts a reverse spiral discharge middle section grate method to intercept the grinding medium.

[0065] In this embodiment, the permanent magnet driven mixed medium ball mill used in step three is composed of a permanent magnet motor 1 directly meshing with a large gear of the ball mill, and the system transmission efficiency is increased by 12.75 percentage points to 92.10%, and the power factor is increased by 0.11 to 0.96; the mixed medium composed of 65% ceramic balls and 35% steel balls has a weight reduction of 39.13% under the same volume, and the medium filling rate of the permanent magnet driven mixed medium ball mill is increased by 7 percentage points to 40%, so as to achieve the saving of the permanent magnet driven mixed medium ball mill. Under the premise of reducing the medium energy consumption by more than 30%, the grinding process parameters can still be improved, and the particle size composition of the permanent magnet driven mixed medium ball mill can be improved. The permanent magnet driven mixed medium ball mill used in the present invention saves more than 25% energy than the traditional ball mill of the same specification.

[0066] In step six, the second stage grinding is permanent magnet driven stratified medium vertical mill grinding. The permanent magnet driven stratified medium vertical mill includes permanent magnet motor 2 and vertical mill spiral stirring shaft. The permanent magnet driven stratified medium vertical mill adopts permanent magnet motor 2 to directly drive the vertical mill spiral stirring shaft. Among them, permanent magnet motor 2 is matched with a frequency converter and has a direct drive capability of 5Hz to 50Hz. When permanent magnet motor 2 directly drives the mill at a frequency of 5Hz to 10Hz, it reaches 3.5 times the torque.

[0067] The volume filling rate of the permanent magnet driven stratified medium vertical mill is 80±3%, the grinding concentration of the permanent magnet driven stratified medium vertical mill is 65±2%, the feeding method of the permanent magnet driven stratified medium vertical mill is self-flowing lower feeding with a height difference of more than 12 meters, and the discharge port of the permanent magnet driven stratified medium vertical mill is completely sealed with arc-shaped vertical bar grate, and the arc of the vertical bar grate is the same as the lining of the permanent magnet driven stratified medium vertical mill, and the inner side is flush with the cylinder of the permanent magnet driven stratified medium vertical mill, wherein the vertical bar hole width is 5mm~12mm, and the height is 100mm~160mm.

[0068] The permanent magnet driven layered medium vertical mill uses a natural layered structure of lower steel balls and upper ceramic balls for grinding. The ceramic balls used have a diameter of 25mm and a density of 3880kg / m 3 The ceramic ball used has a diameter of 25 mm and a density of 3880 kg / m 3 The spatial natural layered structure is formed by 15% to 20% of steel balls as the lower layer and 80% to 85% of ceramic balls as the upper layer.

[0069] In this embodiment, the permanent magnet driven layered medium vertical mill used in step 6 uses a steel ball with a diameter of 30 mm and a density of 7815 kg / m 3 The ceramic ball used has a diameter of 25 mm and a density of 3880 kg / m 3 The volume filling rate is 80%, the grinding concentration is 65%, and the suspended fluid composed of slurry, steel balls and ceramic balls in the spiral stirring space of the vertical mill forms a spatial natural stratified structure of lower steel balls and upper ceramic balls according to the difference in true density for grinding. The density of the suspended fluid decreases by 47.59%, and the theoretical energy consumption is therefore reduced by more than 45%. Among them, the density of the ceramic balls is 49.65% of that of the steel balls. During the grinding process, the energy consumption required for the ball mill to lift the grinding medium is reduced by more than 50%. The lightweight grinding medium saves a lot of energy other than the dissociation of the ore. At the same time, the impact between the ceramic balls and the ore is weakened after they fall, which greatly reduces the production of ore below 5μm, thereby increasing the proportion of the target -0.074+0.037mm particle size. The permanent magnet driven stratified medium vertical mill grinding adopted in the present invention saves more than 32% energy than the fine grinding operation of the traditional ball mill with the same processing capacity.

[0070] The permanent magnet driven mixed medium ball mill and the permanent magnet driven layered medium vertical mill are both equipped with a silencer and a shock absorbing device, wherein the shock absorbing device adopts a rubber shock isolator or a spring shock absorber.

[0071] The technical effect of the above content is: the silencer can reduce the noise of the permanent magnet driven mixed medium ball mill and the permanent magnet driven layered medium vertical mill; the rubber isolator is made of porous rubber material and has good absorption performance, which can effectively isolate and attenuate mechanical vibrations; the spring shock absorber uses the high elasticity of the spring to reduce the amplitude and play a shockproof role; the silencer and shock absorbing device can reduce the noise in the grinding operation area, thereby solving the noise problem of the ore dressing plant.

[0072] Working principle: The prepared raw ore with a -3mm particle size content ≥85% is processed in a two-stage "classification-grinding" closed-loop cycle operation to increase the target particle size ratio in the grinding product, thereby obtaining a qualified particle size ore with a -0.074+0.037mm particle size content ≥60%, thereby reducing non-target particle size grinding, reducing grinding energy consumption, stabilizing various indicators of the mineral processing process, and achieving the purpose of energy saving and consumption reduction.

[0073] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0074] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A grinding method for increasing the proportion of -0.074+0.037 mm particle size, characterized in that: The following steps are involved: Step 1: Prepare the crushed ore, and the ore particle size range is controlled within -3mm particle content ≥85%; Step 2: feeding the raw ore described in step 1 into a stage of classification performed by a hydrocyclone to obtain a stage of classification overflow and a stage of classification return sand; Step 3: feeding the first-stage graded return sand obtained in step 2 into the first-stage grinding operation to obtain a first-stage grinding product; Step 4: returning the first-stage grinding product obtained in step 3 to the first-stage classification operation to form a first-stage grinding and classification closed-loop operation, and obtaining a first-stage classification overflow; Step 5: feeding the first-stage classification overflow obtained in step 2 and step 4 into the second-stage classification operation to obtain the second-stage classification overflow and the second-stage classification return sand; Step 6: Feed the second-stage classified return sand obtained in step 5 into the second-stage grinding operation to obtain the second-stage grinding product; Step 7: Return the second-stage grinding product obtained in step 6 to the second-stage classification operation, forming a second-stage grinding and classification closed-loop operation, and obtain the second-stage classification overflow, and finally obtain qualified particle size ore.

2. The grinding method for increasing the proportion of -0.074+0.037 mm particle size according to claim 1, characterized in that: The step 1 comprises the following steps: Determine the crushing requirements of the raw ore, where the crushing requirement is that the particle size range of the raw ore is controlled within -3mm particle content ≥ 85%. At the same time, select appropriate crushing equipment and debug it. The crushing equipment uses a jaw crusher, impact crusher or cone crusher; The raw ore is transported to the crushing equipment for crushing, and the working parameters of the crushing equipment are controlled during the crushing process, wherein the working parameters are the crushing time, speed and frequency; After the initial crushing is completed, the obtained crushed product is subjected to particle size analysis and evaluation; If the particle size distribution meets the pre-set crushing requirements, go directly to step 2; If the particle size distribution does not meet the pre-set pulverization requirements, the pulverized product obtained by the primary pulverization needs to be pulverized for the second time; The crushed products obtained from the secondary crushing are classified and screened to remove particles that do not meet the crushing requirements, and samples that meet the crushing requirements are collected and entered into step two.

3. The grinding method for increasing the proportion of -0.074+0.037 mm particle size according to claim 2, characterized in that: After the initial crushing, the obtained crushed product is subjected to particle size analysis and evaluation, which specifically includes the following processes: After the initial crushing, a portion of the crushed product is taken as a sample, and the number and location of the samples are randomly selected; Using a particle size analyzer, the sampled particles are subjected to a particle size analysis to measure the particle size of the sample; Analyze the measured particle size data and understand the particle size distribution of the original ore based on the analysis results; The process and results of the above particle size analysis and evaluation shall be recorded and a report shall be generated.

4. The grinding method for increasing the proportion of -0.074+0.037 mm particle size according to claim 1, characterized in that: In the step three, the first stage of grinding is a permanent magnet driven mixed medium ball mill grinding, the permanent magnet driven mixed medium ball mill includes a permanent magnet motor 1 and a ball mill cylinder, the permanent magnet driven mixed medium ball mill uses a permanent magnet motor 1 to directly drive the ball mill cylinder, wherein the permanent magnet motor 1 is matched with a frequency converter and has a direct drive capability of 5Hz to 22Hz.

5. The grinding method for increasing the proportion of -0.074+0.037 mm particle size according to claim 4, characterized in that: The permanent magnet driven mixed medium ball mill adopts the form of mixed medium for grinding, and the mixed medium is steel balls and ceramic balls mixed in a certain proportion, which is 15% to 22% of φ50 steel balls, 18% to 25% of φ30 steel balls, 15% to 20% of φ30 ceramic balls, 21% to 27% of φ25 ceramic balls and 15% to 20% of φ20 ceramic balls.

6. The grinding method for increasing the proportion of -0.074+0.037 mm particle size according to claim 4, characterized in that: The permanent magnet driven mixed medium ball mill adopts a high filling rate grinding method, the initial ball filling rate is 36% to 38%, the filling rate is 38% to 42% during stable production, and the permanent magnet driven mixed medium ball mill adopts a reverse spiral discharge middle section grate method to intercept the grinding medium.

7. The grinding method for increasing the proportion of -0.074+0.037 mm particle size according to claim 1, characterized in that: In the step six, the second stage grinding is permanent magnet driven stratified medium vertical mill grinding, the permanent magnet driven stratified medium vertical mill includes permanent magnet motor 2 and vertical mill spiral stirring shaft, the permanent magnet driven stratified medium vertical mill uses permanent magnet motor 2 to directly drive the vertical mill spiral stirring shaft, wherein the permanent magnet motor 2 is matched with a frequency converter and has a direct drive capability of 5Hz to 50Hz.

8. The grinding method for increasing the proportion of -0.074+0.037 mm particle size according to claim 7, characterized in that: The volume filling rate of the permanent magnet driven stratified medium vertical mill is 80±3%, the grinding concentration of the permanent magnet driven stratified medium vertical mill is 65±2%, the feeding method of the permanent magnet driven stratified medium vertical mill is self-flowing lower feeding with a height difference of more than 12 meters, and the discharge port of the permanent magnet driven stratified medium vertical mill is completely sealed with an arc-shaped vertical bar grate, and the arc of the vertical bar grate is the same as the lining of the permanent magnet driven stratified medium vertical mill, and the inner side surface is flush with the cylinder of the permanent magnet driven stratified medium vertical mill, wherein the vertical bar hole width is 5mm~12mm, and the height is 100mm~160mm.

9. The grinding method for increasing the proportion of -0.074+0.037 mm particle size according to claim 7, characterized in that: The permanent magnet driven layered medium vertical mill adopts a natural layered structure of lower steel balls and upper ceramic balls for grinding. The ceramic balls used have a diameter of 25 mm and a density of 3880 kg / m 3 The ceramic ball used has a diameter of 25 mm and a density of 3880 kg / m 3 The spatial natural layered structure is formed by 15% to 20% of steel balls as the lower layer and 80% to 85% of ceramic balls as the upper layer.

10. The grinding method for increasing the proportion of -0.074+0.037 mm particle size according to any one of claims 4 and 7, characterized in that: The permanent magnet driven mixed medium ball mill and the permanent magnet driven layered medium vertical mill are both equipped with a silencer and a shock absorbing device, wherein the shock absorbing device adopts a rubber shock isolator or a spring shock absorber.

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