Process for improving machine-hour quantity of ball mill in iron separation plant

Abstract

The invention discloses a process for improving the machine-hour quantity of a ball mill of an iron separation plant, and belongs to the technical field of mine production. A plurality of technologies are integrated, including accurate ore grinding, so that the final ball load characteristic is always in a proper proportion, and the processing capacity of the mill is improved. The ore pulp viscosity is low, the ore pulp viscosity and the yield stress are reduced when the ore grinding ore pulp concentration is reduced, the contact time of media and particles is shortened, the acting force at the collision moment is enhanced, and effective crushing and grinding are improved. Low centrifugal force: the cyclone is produced under the low centrifugal force, so that settled sand is fine, the regeneration of the ball mill is improved, and the processing capacity of the ball mill is improved. The three technologies are combined and complement each other, the iron ore treatment capacity of the overflow type ball mill is remarkably improved, and the machine hour of the mill is increased by about 13.6%.

Description

Technical Field

[0001] The invention belongs to the technical field of mine production, and more specifically, relates to a process for improving the machine time of a ball mill in an iron concentrator. Background Art

[0002] As the most common raw material, steel is widely used in many fields of modern industry. Iron ore is the most basic and most in-demand raw material for the steel industry. Ball mill is the grinding equipment after the iron ore is crushed. The processing capacity of the first-stage grinding ball mill affects the machine time of the entire process. Most iron ore concentrators use stage grinding and stage separation, and flotation and magnetic separation operations are connected after the first-stage grinding, so overflow ball mills are used. Compared with the grid ball mill, the overflow ball mill has good particle size characteristics, but its processing capacity is not as good as the grid ball mill. The constraint for iron ore concentrators to increase the machine time is how to improve the processing capacity of the first-stage overflow ball mill.

[0003] In the prior art, the invention patent with patent application number: CN202111494815.6 discloses a method for improving the utilization coefficient of a primary ball mill in a grinding process, comprising the following steps: coarsening the first-stage grinding classification particle size, and increasing the processing capacity of the first-stage mill according to the grinding work index; then increasing the magnetic field strength of the first-stage magnetic separator to 120-200 kA / m to reduce the magnetic iron grade of the magnetic separation tailings; by adding 50% to 60% of the original number of second-stage mills, increasing the grinding capacity of the second-stage grinding process, and increasing the volume by 50% to 60%, to digest the increased processing capacity of the first-stage mill and the increased ore volume after the first-stage magnetic separation improves the recovery rate.

[0004] The invention patent with patent application number: CN201310363842.9 discloses a method for improving the grinding efficiency of a ball mill, comprising the following steps: (1) improving the structure of the ball mill by replacing the cylinder lining with a corrugated lining; (2) adjusting the grinding medium of the ball mill to increase the grinding filling rate by 40-48%; (3) improving the conditions for entering the mill and reducing the feed particle size of the ball mill; (4) improving the grinding parameters: increasing the grinding time, increasing the mill speed, and increasing the grinding concentration to improve the grinding fineness.

[0005] The above invention improves the grinding efficiency and utilization coefficient, reduces the grinding cycle load, increases the processing capacity of the ball mill, increases the qualified output of iron ore powder, and improves the economic benefits; however, the patent does not take into account the need to increase the number of mills and modify the grinding equipment, and the operation is difficult. Some of the features have limited operation on other ball mill parameters. The speed of most ball mills cannot be adjusted, the grinding time is fixed, and high-concentration grinding reduces the collision force between the medium and the material, and the impact of high concentration on subsequent sorting operations is not considered. And when the slurry level of the overflow ball mill is too high, the slurry is easy to gush out from the discharge port of the mill, and the discharge is not smooth, causing blockage at the discharge end. Therefore, the key to improving the milling machine time is how to increase the ball milling newborn and reduce the grinding return sand ratio. The machine time can only be increased when the mill has surplus grinding capacity, otherwise it will cause the return sand ratio to become larger and larger, affecting the stability of the process. Summary of the invention

[0006] 1. Problems to be solved

[0007] In view of the deficiencies of the prior art mentioned in the background technology, the present invention provides a process for improving the running time of the ball mill in an iron ore dressing plant. Through precise steel ball ratios for different particle sizes, low grinding concentration and low centrifugal force, the grinding effect is improved while the processing capacity of the ball mill is improved.

[0008] 2. Technical solution

[0009] To solve the above problems, the present invention adopts the following technical solutions.

[0010] A process for improving the time of a ball mill comprises the following steps:

[0011] (1) Feeding the product crushed by the high-pressure roller into a ball mill;

[0012] (2) Accurately proportion the grinding media in a first-stage ball mill;

[0013] (3) Reduce the grinding concentration of the ball mill;

[0014] (4) The ball mill discharge product enters the cyclone for classification, and the cyclone sand settling product and overflow product are classified and processed;

[0015] (5) The fineness of the sand settling product in the cyclone is returned to the first-stage ball mill;

[0016] (6) The overflow product of the cyclone enters the linear vibrating screen, and the products above the screen and below the screen are classified and processed;

[0017] (7) The product on the linear vibrating screen is discarded as waste rock, and the product under the screen enters the flotation operation.

[0018] As a further improvement of the technical solution, in step (1), the particle size of the product crushed by the high-pressure roller is -3 mm, accounting for 70%.

[0019] As a further improvement of the technical solution, the model of the first stage ball mill in step (1) is MQY4.0m×6.0m.

[0020] As a further improvement of the technical solution, in step (4), the ball mill discharge material is lifted and transported to the cyclone for classification by a slurry pump. The cyclone specification is FX500-PU*6. Under low centrifugal force of the cyclone, the classification pressure is reduced to 70 kPa.

[0021] As a further improvement of the technical solution, the mesh size of the linear vibrating screen in step (6) is 0.3 mm.

[0022] As a further improvement of the technical solution, the magnetic iron grade of the material on the screen in step (7) is 9.52%, and the total iron grade is 18.48%.

[0023] As a further improvement of the technical solution, the optimal grinding concentration of the ball mill in step (2) is 70%-75%.

[0024] As a further improvement of the technical solution, in step (3), the frequency of reducing the water volume is reduced to reduce the centrifugal force of the cyclone.

[0025] As a further improvement of the technical solution, in step (3), a group of cyclones is added to reduce the frequency so as to reduce the centrifugal force of the cyclones.

[0026] 3. Beneficial effects

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The process of improving the time of a ball mill in the present invention integrates multiple technologies, including precise grinding of ball mills, low slurry viscosity and low centrifugal force. The three technologies complement each other. Compared with the prior art, there is no need to add equipment or significantly modify the grinding equipment. The time of an overflow ball mill can be improved by adjusting various parameter values;

[0029] (2) The present invention provides a process for improving the time of ball milling. By using precise grinding, the final ball load characteristics are always in an appropriate ratio, and the grinding effect is not reduced due to roundness loss, resulting in a very good grinding effect. The particle size distribution characteristics of the grinding product are also optimal, thereby improving the processing capacity of the mill and reducing the energy consumption of the product.

[0030] (3) The present invention provides a process for improving the time of a ball mill, which changes the ball diameter ratio of the grinding medium in the ball mill according to the precise ball loading system, reduces the average ball diameter of the medium, and combines it with the result of reducing the particle size of the product after high-pressure roller crushing, so that the grinding conditions are more suitable for the sample to be milled;

[0031] (4) The present invention provides a process for improving the time of a ball mill, which uses low slurry viscosity to increase the fluidity of the slurry, shorten the collision time between the medium and the material, increase the instantaneous collision force between the medium and the material, and increase the first crushing rate of the material;

[0032] (5) The present invention provides a process for improving the time of a ball mill, using low classification centrifugal force. Under low classification pressure, the classification efficiency is reduced, the fineness of the sand settling is increased, the sand settling material is returned to the mill to adapt to the precise grinding medium, the ball milling is increased, the return sand ratio is reduced, and the working efficiency of the mill is improved;

[0033] (6) The present invention provides a process for improving the time of a ball mill, which combines reducing the particle size of the material entering the mill with the precision of the ball diameter. The precision ball diameter is smaller than the original ball diameter of the grinding medium, and the particle size of the returned sand material is reduced to just match it, which is beneficial to improving the regeneration of the ball mill and reducing the return sand ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a process flow chart of the present invention;

[0035] Figure 2 It is to adjust the particle size characteristics of the grinding and classification products of the first 230t / h grinding and classification process;

[0036] Figure 3 It is the particle size characteristics of the grinding and classification products in the 250t / h first-stage grinding and classification process after adjustment. DETAILED DESCRIPTION

[0037] Exemplary embodiments of the present invention are described in detail below. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention, it should be understood that other embodiments may be implemented and various changes may be made to the present invention without departing from the spirit and scope of the present invention. The more detailed description of the embodiments of the present invention below is not intended to limit the scope of the claimed invention, but is merely for illustration and does not limit the description of the features and characteristics of the present invention, in order to propose the best mode for performing the present invention, and is sufficient to enable those skilled in the art to implement the present invention. Therefore, the scope of the present invention is limited only by the appended claims.

[0038] Example 1

[0039] A process for improving the time of a ball mill comprises the following steps:

[0040] (1) Feeding the product crushed by the high-pressure roller into a ball mill;

[0041] (2) Accurately proportion the grinding media in a first-stage ball mill;

[0042] (3) Reduce the grinding concentration of the ball mill;

[0043] (4) The ball mill discharge product enters the cyclone for classification, and the cyclone sand settling product and overflow product are classified and processed;

[0044] (5) The fineness of the sand settling product in the cyclone is returned to the first-stage ball mill;

[0045] (6) The overflow product of the cyclone enters the linear vibrating screen, and the products above the screen and below the screen are classified and processed;

[0046] (7) The product on the linear vibrating screen is discarded as waste rock, and the product under the screen enters the flotation operation.

[0047] Among them, in step (1), the particle size of the product crushed by the high-pressure roller is -3mm, accounting for 70%, and the model of the first-stage ball mill is MQY4.0m×6.0m.

[0048] Step (4) The discharged material from the ball mill is lifted and transported by a slurry pump to a cyclone for classification. The specification of the cyclone is FX500-PU*6. Under low centrifugal force of the cyclone, the classification pressure is reduced to 70 kPa.

[0049] The mesh size of the linear vibrating screen in step (6) is 0.3 mm

[0050] The magnetic iron grade of the material on the sieve in step (7) is 9.52%, and the total iron grade is 18.48%.

[0051] The optimum grinding concentration of the ball mill in step (2) is 70%-75%.

[0052] In step (3), the frequency of reducing the water volume is reduced to reduce the centrifugal force of the cyclone.

[0053] In step (3), the centrifugal force of the cyclone classification is reduced by increasing a group of cyclones and reducing the frequency.

[0054] The characteristics of the present invention are analyzed from the ball mill utilization coefficient, taking the MQY4060 overflow ball mill as an example:

[0055]

[0056] In the formula

[0057] q -200 —Ball mill utilization factor, t / h·m 3 ;

[0058] Q—current mill production capacity, t / h;

[0059] β 1 —Content of ore in the feed to the mill currently produced by the factory that is less than the calculated grade, %;

[0060] β 2 —The content of ore grinding products produced by the current mill that is less than the calculated level, %;

[0061] V—effective volume of the mill currently produced, m 3 .

[0062] The effective volume of MQY4060 overflow ball mill is 70.2m 3 Taking an iron ore mine as an example, the current mill production capacity is 230t / h, the current mill feed ore content less than the calculated level is 9%, the current mill product content less than the calculated level is 14%, the calculated ball mill utilization coefficient is 16.38t / h·m 3 .

[0063] When the MQY4060 overflow ball mill is used for iron ore, the ball milling regeneration increases from 5% to 7% after the invention is applied, and the milling time increases from 230h / t to 250t / h. The characteristic is that the milling processing capacity can be increased without changing the equipment while increasing the ball milling regeneration. The calculated ball mill utilization coefficient is 24.93t / h·m 3 .

[0064] The first-stage ball mills of A iron ore and B iron ore are both MQY4060 overflow ball mills. The sample of A iron ore after crushing is discarded and enters the first-stage ball mill with a maximum hourly rate of 230t / h. Figure 1 As shown, taking the first stage mill of B iron ore as an example, a process method for improving the time of the ball mill in an iron concentrator includes the following steps:

[0065] (1) Feeding the product crushed by the high-pressure roller into a first-stage ball mill, and accurately proportioning the grinding media in the first-stage ball mill;

[0066] Specifically, the B iron ore is crushed in three stages, i.e., one open circuit coarse crushing, one open circuit medium crushing, and one closed circuit fine crushing, the ore is crushed to -10mm≥90%, and then dry waste operation is carried out. The waste ore enters the high-pressure roller operation, which is a semi-closed circuit crushing. After crushing, the material enters a ball mill;

[0067] The grinding media of the first-stage ball mill (MQY4060 overflow ball mill) is loaded with balls according to the optimal filling rate and precise proportion of steel balls obtained from the laboratory precision grinding test. The proportion of steel balls is: Φ40mm:Φ30mm:Φ25mm=40%:50%:10%, the mixed ball diameter is 33mm, and the steel ball filling rate is 35%. At this time, the yield of new -0.075mm is 28.18%, and the yield of -0.075mm reaches 43.01%. The results of mechanical tests and semi-theoretical ball diameter formula calculation show that when the feed particle size of the first-stage ball mill is 15mm, its calculated ball diameter is 80mm. Therefore, according to the feed particle size characteristics of B iron ore, the maximum steel ball diameter is designed to be 80mm. Considering the gradation of steel balls, 65mm, 50mm neutral balls and small balls below 40mm are selected. According to the particle size distribution obtained from the process investigation and the particle size distribution of the first-stage mill feed provided by the concentrator, the initial steel ball ratio of the concentrator mill is designed to be: Φ80mm: Φ65mm: Φ50mm: ≤Φ40mm=30%: 25%: 25%: 20%.

[0068] (2) Reduce the grinding concentration of the ball mill;

[0069] Specifically, the original grinding concentration of the first-stage mill is between 80% and 85%, and the mill feed water is 90m 3 / h, mill discharge water is 210m 3 / h, total water volume is 300m 3 / h, because the first stage of grinding is followed by flotation process, a large increase in the total water volume will cause the subsequent flotation tank to overflow. The present invention raises the discharge water to the feed water, thereby reducing the grinding concentration without increasing the total water volume of the process, and maintaining the stability of the subsequent flotation process. After adjustment, the mill feed water is 230m 3 / h, the discharge water is 0m 3 / h, the grinding concentration of the mill is 70%-75%.

[0070] (3) The ore products discharged from the ball mill enter the cyclone for classification, which reduces the classification pressure of the cyclone, and the cyclone sand settling products and overflow products are classified and processed;

[0071] Specifically, the first stage of discharge material is fed into the cyclone by a slurry pump. The specification of the cyclone is FX500-PU*6. The discharge water volume is adjusted, and the frequency of the cyclone feeding pump pool is reduced. The classification pressure of the cyclone is reduced from about 90kPa to about 70kPa, which reduces the classification efficiency of the cyclone, increases the fineness of sand settling, and reduces the overflow fineness. At the same time, the overflow fineness index is maintained above 50%, which does not affect the subsequent flotation process.

[0072] (4) Increase the fineness of the cyclone sand settling product, and return the sand settling material to the first stage ball mill;

[0073] Specifically, the fineness of the sedimentation sand increased from about 9% to about 11%, the overall particle size decreased, and after the sedimentation sand returned to the mill, it was more suitable for the precise ball diameter system. The fineness of the discharged mineral material increased from about 14% to about 20%, and the ball milling regeneration increased from about 5% to about 9%, which greatly increased the ball milling regeneration and significantly reduced the return sand ratio, making the process more stable.

[0074] (5) The overflow product of the cyclone enters the linear vibrating screen, and the products above the screen and below the screen are classified and processed.

[0075] Specifically, after the cyclone classification pressure is reduced, the overflow material is slightly "coarse", but the overflow is fed into the linear vibrating screen (slag removal screen). The screen hole size of the linear vibrating screen is 0.3mm. The magnetic iron grade of the material on the screen is about 9.52%, and the total iron grade is 18.48%. The magnetic iron and total iron grades are relatively low and can be discarded as waste rock. The fineness of the material under the screen is -0.075mm, accounting for more than 50%, and -0.3mm, accounting for 80%, and will not affect the subsequent flotation operation.

[0076] The process method for increasing the time of ball mill in this application:

[0077] (1) Precise filling and supplementing ball system: Step (1) accurately fills the balls with the ball diameter ratio (Φ80mm:Φ65mm:Φ50mm:≤Φ40mm=30%:25%:25%:20%), and according to the principle of large grinding for large and small grinding for small, it is beneficial to crush and grind materials of different particle sizes and better improve the grinding capacity of the mill. The filling ball system is Φ80mm:Φ65mm=50%:50%, which can better grind the intermediate particle size compared with adding a single ball diameter. The original yield of -0.5mm+0.075mm at 230t / h is 60%, and after adjustment by the present invention, the yield of -0.5mm+0.075mm is 55%, and when the subsequent unit time is increased to 250t / h, the yield of -0.5mm+0.075mm is still 55%, which shows the advantages of the precise filling and supplementing ball system.

[0078] (2) Low-concentration grinding: The grinding concentration in step (2) is controlled at 70%-75%. The present invention significantly reduces the grinding concentration and controls it within the optimal concentration range, significantly improving the grinding effect of the mill. Because the mill specification is an MQY4060 overflow ball mill with a large internal volume, a small increase in the feed water cannot effectively reduce the grinding concentration. On the contrary, it will cause the flow rate to increase and the discharge end to spray ore, blocking the discharge end. The present invention first reduces the mill time to reduce the slurry flow rate, and then increases the feed water from 90t / h to 200t / h. When the process is relatively stable, the time is then increased back to 230t / h to reduce the grinding concentration without causing the discharge end to spit out ore. At this time, the return sand is relatively low.

[0079] (3) Reduce the cyclone classification pressure: (Step 3) The cyclone classification pressure is controlled at about 70 kPa. There are two ways to reduce the cyclone classification pressure: one is to reduce the discharge water: the mill discharge material is in the cyclone pump pool, and is fed into the cyclone through the slurry pump to reduce the discharge water. To prevent the pump pool from drying up, the pump pool feeding frequency is reduced accordingly, thereby reducing the cyclone classification pressure; the second is to increase the number of cyclone groups. The number of cyclone working groups will evenly distribute the input materials. Adding a group of cyclones will reduce the working pressure of each group of cyclones. The reduction of cyclone classification pressure also reduces the classification efficiency, increases the sand settling fineness, and reduces the overflow fineness (maintaining the overflow fineness index above 50%). As shown in Table 1.

[0080] Table 1 Particle size distribution of 230t / h grinding and classification products before and after adjustment

[0081]

[0082] As can be seen from Table 1, after precise steel ball ratio and adjustment of various parameters, including reducing grinding concentration and cyclone pressure, the fineness of sand settling increased and the average particle size decreased, the precise steel ball diameter ratio has advantages. The ball milling rate increased from the original 5.2% to 8.9%, and the return sand ratio decreased from the original 696% to 353%, and the grinding effect was significantly improved.

[0083] The MQY4660 overflow ball mill has a capacity of 230t / h, which is the highest capacity in the current ore dressing plant. It is difficult to increase the capacity again. After the adjustment of the present invention, the ball milling rate increases, the return sand ratio decreases, the grinding and classification process becomes smoother, and the grinding capacity of the mill is surplus. On this basis, the input abrasive of a first-stage mill is increased, and the capacity of the mill is increased from 230t / h to 250t / h. The particle size distribution of the grinding and classification products is shown in Table 2.

[0084] Table 2 Particle size distribution of grinding and classification products at 250t / h unit hour

[0085]

[0086] As can be seen from Table 2, when the grinding concentration is 75%, the overflow fineness index reaches more than 50%, and the ball mill regeneration ratio is 7.5% higher than the original parameters of 230t / h. Although the return sand ratio has increased to 424%, this value is within an acceptable range at 250t / h, and the process is smooth and stable.

[0087] The examples described in the present invention are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should all fall within the protection scope of the present invention.

Claims

1. A process for improving the time of a ball mill, characterized in that: The following steps are involved: (1) Feeding the product crushed by the high-pressure roller into a ball mill; (2) Accurately proportion the grinding media in a first-stage ball mill; (3) Reduce the grinding concentration of the ball mill; (4) The ball mill discharge product enters the cyclone for classification, and the cyclone sand settling product and overflow product are classified and processed; (5) The fineness of the sand settling product in the cyclone is returned to the first-stage ball mill; (6) The overflow product of the cyclone enters the linear vibrating screen, and the products above the screen and below the screen are classified and processed; (7) The product on the linear vibrating screen is discarded as waste rock, and the product under the screen enters the flotation operation.

2. A process for improving the time of a ball mill according to claim 1, characterized in that: In the step (1), the particle size of the product crushed by the high-pressure roller is -3 mm, accounting for 70%.

3. A process for improving the time of a ball mill according to claim 2, characterized in that: The model of the first stage ball mill in the step (1) is MQY4.0m×6.0m.

4. A process for improving the time of a ball mill according to claim 1, characterized in that: In the step (4), the ball mill discharge material is lifted and transported by a slurry pump to a cyclone for classification. The cyclone specification is FX500-PU*6. Under low centrifugal force of the cyclone, the classification pressure is reduced to 70 kPa.

5. A process for improving the time of a ball mill according to claim 1, characterized in that: The mesh size of the linear vibrating screen in step (6) is 0.3 mm.

6. A process for improving the time of a ball mill according to claim 1, characterized in that: The magnetic iron grade of the material on the screen in step (7) is 9.52%, and the total iron grade is 18.48%.

7. A process for improving the time of a ball mill according to claim 1, characterized in that: The optimum grinding concentration of the ball mill in step (2) is 70%-75%.

8. The process for improving the time of a ball mill according to claim 1, characterized in that: In the step (3), the classification centrifugal force of the cyclone is reduced by reducing the frequency of water reduction.

9. A process for improving the time of a ball mill according to claim 1, characterized in that: In the step (3), the classification centrifugal force of the cyclone is reduced by adding a group of cyclones to reduce the frequency.

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