Efficient grinding process for tin ore

Abstract

The application discloses a high-efficiency grinding process for tin ore, which effectively separates coarse particles and makes them enter into sand by precisely controlling the pressure of a cyclone in a pressure range of 0.02-0.04 MPa, can effectively ensure that the content of +0.35 mm particles in overflow of the first-stage cyclone is strictly less than 5%, realizes the target of no coarse particles in the overflow, controls the ore concentration to be 30-40% at the same time, ensures the stable flow state of the ore slurry in the cyclone, makes the cyclone more accurately perform the grading operation, reduces the concentration of the sand in the first-stage cyclone, and ensures that the ore entering into the ball mill is basically +1 mm particle size ore through efficient screening, thereby reducing the over-grinding phenomenon of the ball mill, makes the material with a particle size of -0.074 mm particle grade stable between 50-55%, and the proportion of the material with a particle size of -0.01 mm particle grade is about 18%, thereby improving the tin recovery rate, and improving the economic benefit and resource utilization rate of the tin ore beneficiation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ore dressing, in particular to a high-efficiency grinding process for tin ore. BACKGROUND

[0002] Tin is an important non-ferrous metal, which has a wide range of applications in electronics, chemical industry, machinery and many other fields. The development and utilization of tin ore resources are of great significance to meet the industrial demand and promote economic development. As an important part of the tin ore dressing process, the grinding process is to further reduce the particle size of the mined tin ore by means of the impact of steel balls, steel rods or gravel media in mechanical equipment and the ore itself, until the ore is ground into powder. The purpose is to maximize the separation of useful minerals from other minerals, and to provide suitable particle size materials for subsequent beneficiation operations, so as to realize the efficient recovery and utilization of tin ore resources.

[0003] One of the most common grinding process combinations used in the existing 2500t / d concentrator is the SAB grinding process flow, that is, the combination of semi-autogenous grinding and ball grinding. Specifically, the raw ore is first coarsely ground by a semi-autogenous mill, and then the discharge of the semi-autogenous mill is treated by a cylindrical screen, and the under-screen product is sequentially treated by a first cyclone, a linear vibrating screen, a second cyclone, a high-frequency vibrating screen, and a ball mill for fine grinding. Finally, the overflow of the first cyclone, the overflow of the second cyclone, and the under-screen product of the high-frequency vibrating screen are used as the feed for the flotation operation. However, this process has many defects:

[0004] On the one hand, the material enters the first cyclone, and the feed pressure is controlled at more than 0.05MPa for a long time, which makes the first sand concentration as high as about 70%, resulting in low efficiency of the linear vibrating screen, with a-1mm screening efficiency of only 42.58% and a-0.5mm screening efficiency of only 48.14%. Moreover, the screen product is severely mixed with fine particles, and a part of the fine particles that should have fallen through the screen hole are left in the screen product. The-1mm content in the screen product is 79.87%, and the-0.5mm content is 53.76%. When these mixed fine particles enter the ball mill for regrinding, overgrinding is easily caused, which worsens the grinding effect.

[0005] On the other hand, the existing second cyclone also has a sand concentration as high as 70%, which not only leads to low efficiency of the high-frequency vibrating screen and severe mixing of fine particles in the screen product, with a-0.3mm content of 47.49%, but also easily causes the high-frequency vibrating screen to be blocked or to slide, which seriously interferes with the normal operation of the entire grinding process, reduces the production efficiency and the ore dressing quality.

[0006] The grinding fineness of the existing SAB grinding process is difficult to control, and when the actual final grinding product enters the flotation operation, the material with a particle size of-0.074 mm accounts for 63% of the total material, and the material with a particle size of-0.01 mm accounts for 30% of the total material, while the standard required by the flotation feed is that the material with a particle size of-0.074 mm accounts for 50-55%, and the content of the material with a particle size of-0.01 mm is as little as possible, that is, the actual over-grinding phenomenon is serious, which greatly affects the tin recovery index, and leads to a tin recovery rate of only about 40% with large fluctuations, and also damages the enterprise benefit. SUMMARY

[0007] The main purpose of the present application is to provide a high-efficiency grinding process for tin ore, aiming to solve the technical problem of the existing tin ore grinding process that the grinding fineness is difficult to control, resulting in a serious over-grinding phenomenon.

[0008] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a high-efficiency grinding process for tin ore, comprising the following steps:

[0009] (1) Pre-screening: the raw ore is subjected to a multi-layer vibrating screen, and the screened product with a particle size greater than 0.074 mm is the raw ore;

[0010] (2) Semi-autogenous grinding: the screened product after the pre-screening is sent to a semi-autogenous grinding mill for first-stage grinding, the operating parameters of the semi-autogenous grinding mill are dynamically adjusted by monitoring the particle size composition of the semi-autogenous grinding discharge, and the semi-autogenous grinding discharge is subjected to a cylindrical screen, and the screened product is returned to the feed end of the semi-autogenous grinding mill;

[0011] (3) One-stage cyclone treatment: the undersize product of the semi-autogenous grinding discharge is subjected to a one-stage cyclone for classification, the pressure of the cyclone is controlled to be 0.02-0.04 MPa, and the feed concentration is controlled to be 30-40%, so as to obtain one-stage cyclone sand and one-stage cyclone overflow;

[0012] (4) Screening: the one-stage cyclone sand is subjected to a linear vibrating screen, and the undersize product of the linear vibrating screen is subjected to a high-frequency screen;

[0013] (5) Ball grinding: the oversize product of the linear vibrating screen and the oversize product of the high-frequency screen are subjected to a ball mill for second-stage grinding;

[0014] (6) Subsequent treatment: the ball mill discharge is subjected to a one-stage cyclone for re-classification, and the re-classified cyclone overflow is obtained, wherein the undersize product of the multi-layer vibrating screen, the one-stage cyclone overflow, the re-classified cyclone overflow and the undersize product of the high-frequency screen are used as the feed of the flotation operation.

[0015] Further, the multi-layer vibrating screen comprises a plurality of screen surfaces, and the screen hole diameters of each layer of screen surfaces gradually decrease from top to bottom.

[0016] Further, the multi-layer vibrating screen comprises a first layer screen surface, a second layer screen surface and a third layer screen surface, the screen hole diameter of the first layer screen surface is 80mm, the screen hole diameter of the second layer screen surface is 20mm, and the screen hole diameter of the third layer screen surface is 0.074mm.

[0017] Further, the vibration frequency range of the multi-layer vibrating screen is 800-1200 times per minute, and the amplitude range is 3-6mm.

[0018] Further, the operating parameters in the semi-autogenous grinding step comprise a rotating speed and a filling rate, the rotating speed range is 15-20r / min, and the filling rate range is 25%-35%.

[0019] Further, the rotating speed of the two-stage grinding is 15-20r / min, and the filling rate range of the two-stage grinding is 25%-35%.

[0020] Further, the screen hole diameter of the cylindrical screen is 12mm.

[0021] Further, the screen hole diameter of the linear vibrating screen is 1mm, and the screen hole diameter of the high-frequency screen is 0.35mm.

[0022] Further, the screen surface of the linear vibrating screen adopts a polyurethane material.

[0023] Further, in the ball mill, the proportion of steel balls with a diameter of 60-80mm is 30%-40%, the proportion of steel balls with a diameter of 40-60mm is 40%-50%, and the proportion of steel balls with a diameter of 20-40mm is 10%-30%.

[0024] Beneficial effects:

[0025] The tin ore high-efficiency grinding process provided by the application cancels the two-stage cyclone, optimizes the parameters of the one-stage cyclone, controls the pressure of the cyclone in the range of 0.02-0.04MPa, effectively separates the coarse particles and makes them enter the sand, avoids the coarse particles from entering the overflow too early and affecting the subsequent flotation operation, effectively ensures that the content of +0.35mm particles in the overflow of the one-stage cyclone is strictly less than 5%, realizes the goal of no coarse particles in the overflow, controls the ore concentration to be 30-40%, ensures the stability of the ore slurry flow in the cyclone, makes the cyclone more accurately perform the classification operation under the given pressure, further guarantees the stability of the overflow of the cyclone, and significantly reduces the sand concentration of the one-stage cyclone, thereby creating favorable conditions for the subsequent linear vibrating screen screening.

[0026] Due to the optimization of the cyclone parameters, the linear vibrating screen screening efficiency (-1mm) reaches more than 91% after the first-stage cyclone sand enters the linear vibrating screen, the linear vibrating screen screening efficiency (-0.5mm) reaches more than 69%, through efficient screening, it is ensured that the ore entering the ball mill is basically +1mm particle size, thereby reducing the over-grinding phenomenon of the ball mill, improving the working efficiency and grinding effect of the ball mill, making the material with a particle size of-0.074mm particle size in the flotation feed stable at 50-55%, the material with a particle size of-0.01mm particle size accounts for about 18%, thereby improving the tin recovery rate by about 13%, and significantly improving the economic benefit and resource utilization rate of tin ore beneficiation. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The process flow chart of the embodiment of the present application is shown in the figure.

[0028] Figure 2 The process flow chart of the comparative example 1 is shown in the figure.

[0029] The implementation, functional features and advantages of the present application will be further described with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] The experimental methods not specified in the following embodiments of the present application are generally carried out under conventional conditions or under the conditions recommended by the manufacturers. The various common chemical reagents used in the embodiments are all commercially available products.

[0031] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0032] The terms "comprising" and "having" and any variations thereof used in the present application are intended to cover non-exclusive inclusion. For example, a process, method, device, product or equipment including a series of steps is not limited to the listed steps or modules, but optionally also includes steps not listed, or optionally also includes other steps inherent to these processes, methods, products or equipment.

[0033] In order to make the purpose, technical solutions and advantages of the present application more clear and obvious, the present application will be further described in detail below with reference to specific embodiments. It should be understood that these descriptions are only exemplary and do not limit the scope of the present application. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0034] The following embodiments further describe the present application, but the embodiments are not used to limit the protection scope of the present application.

[0035] One embodiment of the present application provides a method comprising the following steps:

[0036] (1) Pre-screening: the raw ore is passed through a multi-layer vibrating screen, and the oversize product is the raw ore with a particle size greater than 0.074 mm;

[0037] (2) Semi-autogenous grinding: the oversize product after the pre-screening is sent to a semi-autogenous mill for first-stage grinding, the operating parameters of the semi-autogenous mill are dynamically adjusted by monitoring the particle size composition of the semi-autogenous mill discharge, and the semi-autogenous mill discharge is passed through a cylindrical screen, and the oversize product is returned to the feed end of the semi-autogenous mill;

[0038] (3) One-stage cyclone treatment: the undersize product of the semi-autogenous mill discharge is passed into a one-stage cyclone for classification, the cyclone pressure is controlled to be 0.02-0.04 MPa, and the feed concentration is controlled to be 30-40%, to obtain one-stage cyclone sand and one-stage cyclone overflow;

[0039] (4) Screening: the one-stage cyclone sand is passed into a linear vibrating screen, and the undersize product of the linear vibrating screen is passed into a high-frequency screen;

[0040] (5) Ball milling: the oversize product of the linear vibrating screen and the oversize product of the high-frequency screen are passed into a ball mill for second-stage grinding;

[0041] (6) Subsequent treatment: the ball mill discharge is passed into a one-stage cyclone for re-classification, to obtain re-classified cyclone overflow, wherein the multi-layer vibrating screen undersize product, the one-stage cyclone overflow, the re-classified cyclone overflow and the high-frequency screen undersize product are used as the feed of the flotation operation.

[0042] In the above embodiment, by accurately controlling the cyclone pressure in the range of 0.02-0.04 MPa, the cyclone can effectively separate the coarse particles and make them enter the sand, avoiding the coarse particles from entering the overflow too early and affecting the subsequent flotation operation, which can effectively ensure that the content of +0.35 mm particles in the one-stage cyclone overflow is strictly less than 5%, achieving the goal of no coarse particles in the overflow; at the same time, the feed concentration is controlled to be 30-40%, ensuring the stability of the slurry flow in the cyclone, so that the cyclone can more accurately perform classification operation under the given pressure, further ensuring the stability of the cyclone overflow, significantly reducing the concentration of the one-stage cyclone sand, thereby creating favorable conditions for subsequent linear vibrating screen screening.

[0043] Due to the optimization of the cyclone parameters, the linear vibrating screen screening efficiency (-1mm) reaches more than 91.10%, and the linear vibrating screen screening efficiency (-0.5mm) reaches more than 69.56% after the first-stage cyclone sand enters the linear vibrating screen. Through efficient screening, it is ensured that the ball mill is basically +1mm particle size ore, thereby reducing the over-grinding phenomenon of the ball mill, improving the working efficiency and grinding effect of the ball mill, and making the flotation feed grinding particle size of -0.074 particle size material stable at 50-55%, and the -0.01mm particle size accounts for about 18%, thereby improving the tin recovery rate by about 13%, and significantly improving the economic benefit and resource utilization rate of tin ore beneficiation.

[0044] The tin ore high-efficiency grinding process of the application breaks through the concept limitation of simply pursuing "improving the classification efficiency of the cyclone" in the traditional process, and innovatively clearly defines the dual working purposes of the first-stage cyclone "overflowing without coarse particles and reducing the sand concentration".

[0045] In an embodiment, the multi-layer vibrating screen includes multiple layers of screen surfaces, and the screen hole diameter of each layer of screen surfaces gradually decreases from top to bottom. The multi-layer vibrating screen includes two or more layers of screen surfaces, and the screen hole diameter of the bottom layer is 0.074mm. Fine particle size ore smaller than 0.074mm is screened out in advance, which can avoid excessive grinding in the subsequent semi-autogenous grinding and ball grinding processes. The screen hole size of the remaining layers of screen surfaces increases from bottom to top, and the raw ore is pre-divided into different particle sizes for subsequent processing, thereby significantly improving the efficiency of semi-autogenous grinding and laying a good foundation for subsequent beneficiation operations, and effectively reducing the risk of over-grinding.

[0046] In the above embodiment, the multi-layer vibrating screen includes a first layer of screen surfaces, a second layer of screen surfaces, and a third layer of screen surfaces. The screen hole diameter of the first layer of screen surfaces is 80mm, the screen hole diameter of the second layer of screen surfaces is 20mm, and the screen hole diameter of the third layer of screen surfaces is 0.074mm. The first layer of screen surfaces screens out large-sized particulate matter in the raw ore, which may contain a large amount of gangue minerals or tin ores that have reached the degree of monomer dissociation and do not need to be further ground. The second layer of screen surfaces separates the ore with a particle size of 20mm to 80mm, so as to differentially process different particle size ores and optimize the material distribution of the entire grinding process. The third layer of screen surfaces can separate fine particle size ores in the raw ore, and fine particle size ores smaller than 0.074mm are screened out in advance, which can avoid excessive grinding in the subsequent semi-autogenous grinding and ball grinding processes, reduce over-grinding, and thereby improve the overall recovery efficiency of tin ores.

[0047] In an embodiment, the multi-layer vibrating screen has a vibration frequency ranging from 800 to 1200 times per minute and an amplitude ranging from 3 to 6 mm. Too low vibration frequency or too small amplitude can result in insufficient movement of the ore on the screen surface, affecting the screening efficiency; while too high vibration frequency or too large amplitude can make the ore jump on the screen surface too violently, causing some ore to pass through the screen hole, also reducing the screening accuracy. By setting the vibration frequency ranging from 800 to 1200 times per minute and the amplitude ranging from 3 to 6 mm, the efficiency and accuracy of pre-screening are ensured.

[0048] In an embodiment, the operating parameters in the semi-autogenous grinding step include the rotational speed and the filling rate, the rotational speed ranging from 15 to 20 r / min, and the filling rate ranging from 25% to 35%. By monitoring the particle size composition of the semi-autogenous grinding discharge during the semi-autogenous grinding process, the operating parameters of the semi-autogenous mill are dynamically adjusted, so that the rotational speed ranges from 15 to 20 r / min, the larger particle ore has enough time and space to grind in the semi-autogenous mill, and the filling rate ranges from 25% to 35%, so that there is a certain collision probability between the steel balls and the ore and the material has moderate fluidity, ensuring the grinding effect.

[0049] In an embodiment, the rotational speed of the secondary grinding ranges from 15 to 20 r / min, and the filling rate of the secondary grinding ranges from 25% to 35%. Similarly, the rotational speed and the filling rate of the ball mill used in the secondary grinding are set to ensure the grinding effect.

[0050] In an embodiment, the diameter of the screen hole of the cylindrical screen is 12 mm.

[0051] In an embodiment, the diameter of the screen hole of the linear vibrating screen is 1 mm, and the diameter of the screen hole of the high-frequency screen is 0.35 mm. This can avoid the problems such as blockage and sliding of the 0.2 mm high-frequency screen in the prior art.

[0052] In an embodiment, the screen surface of the linear vibrating screen is made of polyurethane material. The screen surface made of polyurethane material has good wear resistance and elasticity, can adapt to long-time high-load screening environment, reduces the wear and deformation of the screen mesh, and prolongs the service life of the screen mesh.

[0053] In an embodiment, the steel balls with a diameter of 60-80 mm account for 30-40% in the ball mill, the steel balls with a diameter of 40-60 mm account for 40-50%, and the steel balls with a diameter of 20-40 mm account for 10-30%. The steel ball ratio adjustment based on the tin ore particle size can maximize the grinding capacity of the ball mill. During the rotation of the ball mill, the large steel balls first impact and crush the large particle ores, and then the medium steel balls and the small steel balls play a role in turn to further grind and refine the ores, so that the product particle size uniformity after ball milling is significantly improved, the over-grinding and under-grinding phenomena are reduced, and the material with suitable particle size and good uniformity is provided for subsequent flotation operation, which is beneficial to improve the flotation recovery rate and concentrate grade of the tin ore.

[0054] The application will be further described in detail below with reference to specific embodiments, but the protection scope of the application is not limited to the content.

[0055] Embodiment 1

[0056] Taking a certain silver-tin polymetallic ore in Yunnan as the research object, a kind of efficient grinding process for tin ore, the process flow refers to Figure 1 , and the specific steps are as follows:

[0057] (1) Pre-screening: a certain amount of tin ore is selected and conveyed to a multi-layer vibrating screen, the vibration frequency of the multi-layer vibrating screen is set to 800 times / min, and the amplitude is 3 mm. The raw ore is first screened through the first layer of screen surface (screen hole 80 mm), and about 20% of large particle impurities and already dissociated large particle ores are screened out and collected; then, about 30% of medium particle size ores are separated through the second layer of screen surface (screen hole 20 mm); finally, about 15% of fine particle grade ores are screened out through the third layer of screen surface (screen hole 0.074 mm);

[0058] (2) Semi-autogenous grinding: the pre-screened raw ore is sent to a semi-autogenous mill, the mill rotation speed of the semi-autogenous mill is set to 15 r / min, and the filling rate is 25%. During the semi-autogenous grinding process, the particle size composition of the discharged ore is monitored every 30 minutes. It is found through laser particle size analysis that the-0.074 mm particles in the semi-autogenous grinding discharge account for about 25% of the total material, and the-0.025 mm particles account for about 20% of the total material. According to the monitoring result, the mill rotation speed is appropriately increased to 16 r / min to further optimize the particle size of the discharge. After adjustment, the-0.074 mm particles in the semi-autogenous grinding discharge account for about 28%, which meets the preliminary requirements of the subsequent process on the material particle size;

[0059] (3) One-stage cyclone treatment: The semi-autogenous discharge is passed through a 12 mm cylindrical screen, the oversize product is returned to the feed end of the semi-autogenous mill for regrinding, and the undersize product is fed into a one-stage cyclone for classification. The cyclone feed concentration is monitored and controlled at 30% by an online concentration meter, and the cyclone pressure is set at 0.02 MPa. At this time, the +0.35 mm particle content in the one-stage overflow is 3%, and the one-stage underflow concentration is 50%. Particle size analysis of the one-stage underflow shows that the particle size distribution is relatively uniform, which is suitable for screening treatment in a linear vibrating screen;

[0060] (4) Screening: The one-stage cyclone underflow is fed into a 1 mm linear vibrating screen. The linear vibrating screen uses a polyurethane screen mesh with a mesh size error of ±0.03 mm. After screening, the linear vibrating screen screening efficiency (-1 mm) reaches 92%, and the screening efficiency (-0.5 mm) reaches 70%. Particle size detection of the linear vibrating screen oversize product shows that the +1 mm particle level ore accounts for about 95%, and the undersize product is fed into a 0.35 mm high-frequency screen. The high-frequency screen screening efficiency (-0.35 mm) reaches 84%. Particle size detection of the high-frequency vibrating screen oversize product shows that the +0.35 mm particle level ore accounts for about 87%,

[0061] (5) Ball milling: The linear vibrating screen oversize product and the high-frequency screen oversize product are fed into a ball mill for secondary grinding. The steel balls in the ball mill are loaded according to the following proportions: 30% of steel balls with a diameter of 60-80 mm, 40% of steel balls with a diameter of 40-60 mm, and 30% of steel balls with a diameter of 20-40 mm. During ball milling, the filling rate of the ball mill is controlled at 30%, and the rotation speed is 18 r / min;

[0062] (6) Subsequent treatment: The ball mill discharge is fed into a one-stage cyclone for reclassification. The multi-layer vibrating screen undersize product, the one-stage cyclone overflow, the reclassified cyclone overflow, and the high-frequency screen undersize product are used as the feed for the flotation operation. After detection, the flotation feed grinding fineness is 50%, the -0.01 mm particle level accounts for 17%, and the tin recovery rate is increased by 12%.

[0063] Example 2:

[0064] A certain tin stone polymetallic sulfide ore in Guangxi was taken as the research object, and a high-efficiency grinding process for tin ore was used, with the following specific steps:

[0065] (1) Pre-screening: A certain amount of tin ore is selected and sent to a multi-layer vibrating screen. The vibration frequency of the multi-layer vibrating screen is set to 1000 times per minute, and the amplitude is 4 mm. The raw ore is first screened through the first layer of screen surface (screen hole 80 mm), and about 22% of large particle impurities and already dissociated large particle ores are screened out and collected; then, about 28% of medium particle size ores are separated through the second layer of screen surface (screen hole 20 mm); finally, about 13% of fine particle grade ores are screened out through the third layer of screen surface (screen hole 0.074 mm);

[0066] (2) Semi-autogenous grinding: The pre-screened raw ore is sent to a semi-autogenous mill. The initial mill speed of the semi-autogenous mill is set to 18 r / min, and the filling rate is 30%. During the semi-autogenous grinding process, the particle size composition of the discharge ore is monitored every 25 minutes. Through laser particle size analysis, it is found that the-0.074 mm particles in the semi-autogenous discharge account for about 26% of the total material, and the-0.025 mm particles account for about 22% of the total material. According to the particle size in the monitoring results, the filling rate is adjusted to 28%. After adjustment, the-0.074 mm particle ratio stabilizes at about 30%, ensuring that the semi-autogenous discharge particle size meets the subsequent process requirements;

[0067] (3) One-stage cyclone treatment: The semi-autogenous discharge is passed through a 12 mm cylindrical screen. The screen product is returned to the feed end of the semi-autogenous mill for regrinding by a belt conveyor. The screen underproduct enters a one-stage cyclone for classification. The cyclone feed concentration is monitored and controlled at 35% by an online concentration meter. The cyclone pressure is set to 0.03 MPa. At this time, the +0.35 mm particle content in the one-stage overflow is 2%, and the one-stage sand concentration is 45%. The one-stage sand is analyzed for particle size, and the results show that the particle size distribution is relatively uniform, suitable for entering a linear vibrating screen for screening treatment;

[0068] (4) Screening: The one-stage cyclone sand enters a 1 mm linear vibrating screen. The linear vibrating screen uses a polyurethane screen mesh with a mesh size error of ±0.04 mm. After screening, the linear vibrating screen screening efficiency (-1 mm) reaches 93%, and the screening efficiency (-0.5 mm) reaches 72%. The particle size of the screen product is detected, and it is found that the +1 mm particle grade ore accounts for about 96%. The screen underproduct enters a 0.35 mm high-frequency screen. The high-frequency screen screening efficiency (-0.35 mm) reaches 85%. The particle size of the screen product is detected, and it is found that the +0.35 mm particle grade ore accounts for about 88%,

[0069] (5) Ball milling: the products on the linear vibrating screen and the products on the high-frequency screen enter the ball mill for secondary grinding. The steel balls in the ball mill are filled according to the proportion of 35% of steel balls with a diameter of 60-80 mm, 45% of steel balls with a diameter of 40-60 mm, and 20% of steel balls with a diameter of 20-40 mm. During the ball milling process, the filling rate of the ball mill is controlled to be 32%, and the rotating speed is 19 r / min;

[0070] (6) Subsequent treatment: the ball mill discharge enters a first cyclone for reclassification. The underflow of the multi-layer vibrating screen, the overflow of the first cyclone, the overflow of the reclassified cyclone, and the underflow of the high-frequency screen are used as the feed of the flotation operation. After detection, the grinding-0.074 mm particle size of the flotation feed accounts for 53%, and the-0.01 mm particle size accounts for 19%. The tin recovery rate is increased by 14% compared with the comparative example 1.

[0071] Example 3:

[0072] Taking a certain silver-tin polymetallic ore in Hunan as the research object, a high-efficiency grinding process for tin ore is as follows:

[0073] (1) Pre-screening: a certain amount of tin ore is selected and conveyed to a multi-layer vibrating screen. The vibration frequency of the multi-layer vibrating screen is set to 1200 times / min, and the amplitude is 6 mm. The raw ore is first screened through the first layer of screen surface (screen hole 80 mm) to remove and collect about 25% of large particle impurities and already dissociated large particle ores. Then, about 32% of medium particle size ores are separated through the second layer of screen surface (screen hole 20 mm). Finally, about 18% of fine particle size ores are screened out through the third layer of screen surface (screen hole 0.074 mm);

[0074] (2) Semi-milling: the pre-screened raw ore is sent to a semi-mill. The initial mill rotating speed of the semi-mill is set to 20 r / min, and the filling rate is 35%. During the semi-milling process, the particle size composition of the discharge is monitored every 20 minutes. Through laser particle size analyzer detection, it is found that the-0.074 mm particles in the semi-milling discharge account for about 28% of the total material, and the-0.025 mm particles account for about 25% of the total material. According to the particle size in the monitoring results, the rotating speed is appropriately reduced to 19 r / min. After adjustment, the-0.074 mm particle proportion is stabilized at about 32%, ensuring that the semi-milling discharge particle size meets the requirements of the subsequent process;

[0075] (3) One-stage cyclone treatment: The semi-autogenous discharge is screened through a 12 mm cylindrical screen, and the oversize product is returned to the feed end of the semi-autogenous mill for regrinding; the undersize product enters the one-stage cyclone for classification, the cyclone feed concentration is monitored and controlled at 40% by an online concentration meter, and the cyclone pressure is set at 0.04 MPa, at which time the +0.35 mm particle content in the one-stage overflow is 4%, and the one-stage underflow concentration is 40%; particle size analysis of the one-stage underflow shows that the particle size distribution is relatively uniform, and it is suitable for screening treatment by a linear vibrating screen;

[0076] (4) Screening: The one-stage cyclone underflow enters a 1 mm linear vibrating screen, which uses a polyurethane screen mesh with a mesh size error of ±0.05 mm. After screening, the linear vibrating screen screening efficiency (-1 mm) reaches 91%, and the screening efficiency (-0.5 mm) reaches 69%. Particle size detection of the linear vibrating screen oversize product shows that the +1 mm particle size ore accounts for about 94%, and the undersize product enters a 0.35 mm high-frequency screen; the high-frequency screen screening efficiency (-0.35 mm) reaches 82%. Particle size detection of the high-frequency vibrating screen oversize product shows that the +0.35 mm particle size ore accounts for about 84%,

[0077] (5) Ball milling: The linear vibrating screen oversize product and the high-frequency screen oversize product enter the ball mill for secondary grinding, and the steel balls in the ball mill are loaded according to a ratio of 40% of steel balls with a diameter of 60-80 mm, 50% of steel balls with a diameter of 40-60 mm, and 10% of steel balls with a diameter of 20-40 mm. During ball milling, the filling rate of the ball mill is controlled at 35%, and the rotation speed is 20 r / min;

[0078] (6) Subsequent treatment: The ball mill discharge enters the one-stage cyclone for reclassification, and the multi-layer vibrating screen undersize product, the one-stage cyclone overflow, the reclassification cyclone overflow, and the high-frequency screen undersize product are used as the feed for the flotation operation. Detection shows that the -0.074 mm material accounts for 55% of the total material, and the -0.01 mm particle size accounts for 18%, and the tin recovery rate is increased by 13% compared to Comparative Example 1.

[0079] Comparative Example 1

[0080] The difference from Example 1 is that the existing SAB grinding process is used, and the process flow chart is as follows Figure 2 .

[0081] When the ground product enters the flotation operation, the -0.074 mm material accounts for 63% of the total material, the -0.01 mm particle size accounts for 30.27%, and the tin recovery rate is 40.51%.

[0082] Comparative Example 2

[0083] Different from example 1, the feed pressure of a cyclone is set to 0.05 MPa, and the control feed concentration is 50%.

[0084] When the ground product enters the flotation operation, the material with particle size of-0.074 mm accounts for 64.84% of the total material, the-0.01 mm size fraction accounts for 28.67%, and the tin recovery rate is 41.38%.

[0085] Comparative example 3

[0086] Different from example 1, there is no pre-screening step, and the tin ore raw ore is directly sent into the semi-mill. When the ground product enters the flotation operation, the material with particle size of-0.074 mm accounts for 62.12% of the total material, the-0.01 mm size fraction accounts for 32.51%, and the tin recovery rate is 38.92%.

[0087] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A process for high efficiency grinding of tin ores, characterized in that, The process comprises the following steps: (1) Pre-screening: the raw ore is passed through a multi-layer vibrating screen, and the product with a particle size greater than 0.074 mm is screened out; (2) Semi-autogenous grinding: the screened product is fed into a semi-autogenous mill for first-stage grinding, the operating parameters of the semi-autogenous mill are dynamically adjusted by monitoring the particle size composition of the semi-autogenous mill discharge, and the semi-autogenous mill discharge is screened through a cylindrical screen, and the screened product is returned to the feed end of the semi-autogenous mill; (3) One-stage cyclone treatment: the undersize product of the semi-autogenous mill is fed into a one-stage cyclone for classification, the cyclone pressure is controlled at 0.02-0.04 MPa, and the feed concentration is controlled at 30-40%, thereby obtaining one-stage cyclone underflow and one-stage cyclone overflow; (4) Screening: the one-stage cyclone underflow is fed into a linear vibrating screen, and the undersize product of the linear vibrating screen is fed into a high-frequency screen; (5) Ball milling: the oversize product of the linear vibrating screen and the oversize product of the high-frequency screen are fed into a ball mill for second-stage grinding; (6) Subsequent treatment: the ball mill discharge is fed into a one-stage cyclone for re-classification, thereby obtaining re-classified cyclone overflow, wherein the multi-layer vibrating screen undersize product, the one-stage cyclone overflow, the re-classified cyclone overflow, and the high-frequency screen undersize product are used as the feed for the flotation operation.

2. The tin ore high-efficiency grinding process according to claim 1, characterized in that, The multi-layer vibrating screen comprises multiple layers of screen surfaces, and the screen hole diameters of the screen surfaces gradually decrease from top to bottom.

3. The tin ore high-efficiency grinding process according to claim 2, characterized in that, The multi-layer vibrating screen comprises a first layer of screen surface, a second layer of screen surface, and a third layer of screen surface, the screen hole diameter of the first layer of screen surface is 80 mm, the screen hole diameter of the second layer of screen surface is 20 mm, and the screen hole diameter of the third layer of screen surface is 0.074 mm.

4. The tin ore high-efficiency grinding process according to any one of claims 1-3, wherein the vibration frequency of the multi-layer vibrating screen ranges from 800 to 1200 times per minute, and the amplitude ranges from 3 to 6 mm.

5. The tin ore high-efficiency grinding process according to claim 1, characterized in that, The operating parameters in the semi-autogenous grinding step include the rotational speed and the filling rate, the rotational speed ranges from 15 to 20 r / min, and the filling rate ranges from 25% to 35%.

6. The tin ore high-efficiency grinding process according to claim 1, characterized in that, The rotational speed of the second-stage grinding ranges from 15 to 20 r / min, and the filling rate ranges from 25% to 35%.

7. The tin ore high-efficiency grinding process according to claim 1, characterized in that, The screen hole diameter of the cylindrical screen is 12 mm.

8. The tin ore high-efficiency grinding process according to claim 1, characterized in that, The screen hole diameter of the linear vibrating screen is 1 mm, and the screen hole diameter of the high-frequency screen is 0.35 mm.

9. The tin ore high-efficiency grinding process according to claim 1 or 8, characterized in that, The screen surface of the linear vibrating screen is made of polyurethane material.

10. The tin ore high-efficiency grinding process according to claim 1, characterized in that, In the ball mill, the proportion of steel balls with a diameter of 60-80 mm is 30%-40%, the proportion of steel balls with a diameter of 40-60 mm is 40%-50%, and the proportion of steel balls with a diameter of 20-40 mm is 10%-30%.

Images