Method for adding grinding medium of ball mill

Abstract

The invention belongs to the technical field of mineral processing in the metallurgical industry, and provides a method for adding an ore grinding medium of a ball mill, which adopts natural consumption of steel forgings in the original ball mill in the operation process of the ball mill, realizes replacement of a mixed ore grinding medium of porcelain balls and steel balls in continuous operation of the ball mill, and does not need to stop the ball mill. The problems that in the replacement process, mixed ore grinding media are not suitable for production fluctuation of on-site ore grinding indexes and balls are discharged from the ore discharging end of the ball mill are solved, the optimal proportion of the ball adding size and the ball adding amount of porcelain balls and steel balls in different ball mills is rapidly found out, meanwhile, the workload for completely removing the steel balls and the cost for adding a large number of porcelain balls for the first time are reduced, and the production efficiency is improved. And finally, the novel wear-resistant ore grinding medium replacement period is shortened, production is stabilized, and the comprehensive cost in the ceramic ball replacement process is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing in the metallurgical industry, and relates to the addition of grinding media for a ball mill, in particular to a method for adding grinding media for a ball mill. Background Art

[0002] In the process of mineral processing, grinding is used to make the useful minerals in the original ore reach a monomer dissociation state, creating good conditions for the separation process.

[0003] Steel forging is a common grinding medium for ball mills. In recent years, nano-ceramic composite balls (hereinafter referred to as ceramic balls) as new materials for grinding media have the characteristics of high wear resistance, high hardness, high pressure resistance, uniform particle size of grinding products, low grinding power consumption, and low ball consumption. Compared with traditional steel balls / steel forgings, they have significant advantages in energy saving and consumption reduction, and have been gradually promoted and applied in the fine grinding section of iron ore ball mills. However, during the replacement process, the existing technology has the following disadvantages: 1. It takes at least one week of shutdown to remove all the steel forgings in the original ball mill and add porcelain balls and steel balls according to the initial ball ratio. This will inevitably affect the production progress. In addition, the manpower, material and financial resources required for cleaning the site are large. The original steel forgings of each ball mill are treated as waste and wasted seriously.

[0004] 2. First, add porcelain balls and steel balls according to the initial charging ratio. During the gradual addition process, due to the incompatibility with the production site, the production fluctuation of grinding indicators increased. For example, the fine screen circulation volume of the third mill discharge particle size -200 mesh with a content of less than 70% increased and the classification efficiency decreased. When the grinding concentration was higher than 65%, there was ball spitting phenomenon. The vicious cycle of circulation volume higher than 350% directly caused production impacts such as system production reduction.

[0005] 3. The exploration period for the optimal ratio of ball size and amount of "ceramic balls + steel balls" in different ball mills is long, and an adjustment period of at least three months is required.

[0006] 4. If the original ore is difficult to grind and select, the large circulation volume of the ball mill will cause the grinding concentration to increase, the specific gravity of the porcelain balls will be close to the specific gravity of the ore pulp, and the ball spitting phenomenon will occur at the discharge end of the ball mill. Summary of the invention

[0007] The purpose of the present invention is to provide a method for adding grinding media to a ball mill, so as to solve the problem that production needs to be stopped before the replacement of "porcelain balls and steel balls", reduce the waste of manpower, material resources and materials, and achieve the goal of stabilizing grinding efficiency, eliminating waste, shortening cycle and reducing cost.

[0008] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: A method for adding grinding media to a ball mill comprises the following steps: S1. Preparation: Add a discharge grid at the discharge end of the ball mill; S2. Set the addition standard of grinding media: 1. Steel ball addition specifications: Steel ball diameter D 钢 =24.5*d 1 / 2 mm; where d is the maximum particle size of the ball mill feed; 2. The size of the ceramic ball is divided into three specifications: D 瓷1 =D 瓷 , D 瓷2 =D 瓷 -5mm, D 瓷3 =D 瓷 -10mm 3. The weight percentage of three different specifications of ceramic balls is G 瓷1 :G 瓷2 :G 瓷3 =45%:35%:20%; 4. Standard proportion of porcelain balls and steel balls: The three-stage sand return ratio is ≥250%, and the ratio of porcelain balls to steel balls is less than 4:6; The sand return ratio of the third stage is 180~250%, and the ratio of porcelain ball to steel ball is 5:5; The three-stage sand return ratio is ≤180%, and the ratio of porcelain balls to steel balls is above 6:4; S3, Replace and add porcelain balls and steel balls: S31, first stage, adding ceramic ball D 瓷2 and porcelain ball D 瓷3 , so that the filling rate of the ball mill is increased by 4-6%; S32, second stage, adding ceramic ball D 瓷1 and D 瓷2 , stabilize the grinding efficiency of the three-stage ball mill; S33, the third stage, adding ceramic ball D 瓷1 and steel ball D 钢 In the third stage, it is expected that all the steel forgings in the original belly of the ball mill will be consumed: S34, the fourth stage, determine D 瓷1 With D 钢 The best ratio.

[0009] Furthermore, the opening rate of the discharge grid is ≥32%, and the aperture width is 0.65~0.75*D 瓷 , where D 瓷 It is the minimum diameter of the initial ceramic ball.

[0010] Furthermore, in the first stage, ceramic ball D is added 瓷2 and porcelain ball D 瓷3 The standards are: 1. Add ceramic balls D during the ball mill filling rate improvement stage 瓷2 and porcelain ball D 瓷3 The weight of each accounts for 20% of the budget; 2. Adding cycle 6-8 days, small size ceramic ball D 瓷3 After all the additions are completed in the first stage, D 瓷2 Add 45% of the budgeted weight.

[0011] Furthermore, in the second stage, ceramic ball D is added 瓷1 and porcelain ball D 瓷2 , the standard is: 1. Add 45% by weight of ceramic ball D 瓷1 and porcelain ball D 瓷2 , where the ceramic ball D 瓷2 All are added at this stage; 2. The total amount of addition is completed in 7-9 days, and the daily addition amount is calculated based on 60-70% of the original steel forging consumption; 3. Observe the decrease in the operating current of the ball mill and analyze the grinding efficiency. If there is ore leakage in the subsequent process, add 1~2t of steel balls if necessary to improve the grinding efficiency.

[0012] Furthermore, in the third stage, ceramic ball D is added 瓷1 and steel ball D 钢 The standards are: 1. The amount of steel ball added = (0.5~0.7) * the daily consumption of original steel forging / day; 2. Porcelain ball D 瓷1 Addition amount = (0.2~0.3) * original steel forging daily consumption / day; 3. The adding cycle is controlled within 25 to 30 days.

[0013] Furthermore, the fourth stage determines the ceramic ball D 瓷1 With steel ball D 钢 The best ratio of standards: 1. The on-site process must meet the grinding and classification efficiency. When the grinding efficiency is low, increase the proportion of steel balls; when the on-site three-stage circulation volume is small, increase the proportion of porcelain balls; 2. With the goal of reducing the power consumption of the three-stage ball mill, adjust the proportion of porcelain balls, with the addition amount of porcelain balls fluctuating within ±1kg and the addition amount of steel balls fluctuating within ±2kg; 3. Control the consumption cost of grinding media, that is: the cost of porcelain balls and steel balls ≤ the cost of steel forging.

[0014] The beneficial effects of the present invention are: The method of the present invention realizes the natural consumption of the original steel forging in the belly of the ball mill, and eliminates the waste of discarding the steel forging when replacing porcelain balls; the design of the discharge grid at the discharge end of the ball mill solves the problem of reduced specific gravity after replacing porcelain balls and increased ball running during the operation of the on-site ball mill; through the design of the mixed addition ratio of "porcelain balls + steel balls" in four stages, stable and reliable on-site grinding indicators are achieved, and production fluctuations during the replacement of porcelain balls are eliminated. By analyzing the on-site operation indicators, the best ratio of "porcelain balls and steel balls" is found in the shortest time, and the replacement stabilization period is shortened by more than 20 days, thereby minimizing the series grinding costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the structure of the discharge grid of the ball mill in the embodiment; Figure 2 yes Figure 1 Middle AA section view; Figure 3 This is the grinding media filling and replacement flow chart; Figure 4 This is the index data table 1 at different stages in the embodiment; Figure 5 This is a comparison table 2 of indicators before and after the method of the present invention is used; In the figure, 1, round steel; 2, outer reinforcement ring; 3, reinforcement plate. DETAILED DESCRIPTION

[0016] The method of the present invention is further described below in conjunction with embodiments: A method for adding grinding media to a ball mill comprises the following steps: S1. Preparation: Add a discharging grid at the discharging end of the ball mill, with an opening rate of ≥32% and an aperture width of 0.65~0.75*D 瓷 , where D 瓷 The minimum diameter of the porcelain ball for initial loading; S2. Set the addition standard of grinding media: 1. Steel ball addition specifications: Steel ball diameter D 钢 =24.5*d 1 / 2 mm; where d is the maximum particle size of the ball mill feed; 2. The size of the ceramic ball is divided into three specifications: D 瓷1 =D 瓷 , D 瓷2 =D 瓷 -5mm, D 瓷3 =D 瓷 -10mm 3. The weight percentage of three different specifications of ceramic balls is G 瓷1 :G 瓷2 :G 瓷3=45%:35%:20%; 4. Standard proportion of porcelain balls and steel balls: The three-stage sand return ratio is ≥250%, and the ratio of porcelain balls to steel balls is less than 4:6; The sand return ratio of the third stage is 180~250%, and the ratio of porcelain ball to steel ball is 5:5; The three-stage sand return ratio is ≤180%, and the ratio of porcelain balls to steel balls is above 6:4.

[0017] S3, Replace and add porcelain balls and steel balls: S31, first stage, adding ceramic ball D 瓷2 and porcelain ball D 瓷3 , so that the ball mill filling rate increased by 4-6%: 1. Add D during the ball mill filling rate improvement stage 瓷2 , D 瓷3 Porcelain ball; D 瓷2 , D 瓷3 The weight of each accounts for about 20% of the budget; 2. Adding cycle 6-8 days, small size ceramic ball D 瓷3 At this stage, all the additions are completed, D 瓷2 Add 45% of the budgeted weight.

[0018] S32, second stage, adding ceramic ball D 瓷1 and D 瓷2 ,Stable three-stage ball mill grinding efficiency: 1. Add 45% by weight of ceramic ball D 瓷1 and porcelain ball D 瓷2 , where the ceramic ball D 瓷2 All are added at this stage; 2. The total amount of addition is completed in 7-9 days, and the daily addition amount is calculated based on 60-70% of the original steel forging consumption; 3. Observe the decrease in the operating current of the ball mill and analyze the grinding efficiency. If there is ore leakage in the subsequent process, add 1~2t of steel balls if necessary to improve the grinding efficiency.

[0019] S33, the third stage, adding ceramic ball D 瓷1 and steel ball D 钢， At this stage, it is estimated that all the steel forgings in the original belly of the ball mill will be consumed: 1. The amount of steel ball added = (0.5~0.7) * the daily consumption of original steel forging / day; 2. Porcelain ball D 瓷1 Addition amount = (0.2~0.3) * original steel forging daily consumption / day; 3. The adding cycle is controlled within 25 to 30 days.

[0020] S34, the fourth stage, determine D瓷1 With D 钢 The best ratio: 1. The on-site process must meet the grinding and classification efficiency. When the grinding efficiency is low, increase the proportion of steel balls; when the on-site three-stage circulation volume is small, increase the proportion of porcelain balls; 2. With the goal of reducing the power consumption of the three-stage ball mill, adjust the proportion of porcelain balls, with the addition amount of porcelain balls fluctuating between ±1kg and the addition amount of steel balls between ±2kg; 3. Control the consumption cost of grinding media, that is: porcelain ball + steel ball cost ≤ steel forging cost. Example

[0021] Take the replacement of "porcelain ball + steel ball" mixed medium by three-stage grinding Ø3200*4500 overflow ball mill as an example: Jianshan three-stage grinding mill adopts Ø3200*4500 overflow ball mill with a mill volume of 31.5m 3 , filling rate 32%, maximum feed particle size 1.5mm, total weight of steel forging in the ball mill 46870kg, steel forging size Ø25*30mm, three-stage sand return ratio 217%, steel forging unit consumption 0.28kg / (t original ore).

[0022] The method of adding grinding media to the replacement ball mill is as follows: Figure 3 As shown, the following steps are included: S1. Ball mill discharge end anti-spitting ball modification: add a grate plate (grid) at the discharge end of the ball mill, with an opening rate of 35.6%, a hole width of 10mm, and stainless steel. Figure 1 and Figure 2 As shown, the round steel 1 and the outer rib ring 2 are fixed by the rib plate 3, and the fixing points are not less than 8. The outer rib ring 1 is installed in the direction of the discharge port. The grid is symmetrically divided and made for easy installation. Each node should be welded firmly. The out-of-roundness error of Ø1060 is controlled within ±2mm. The size of the round steel 1 and the outer rib ring 2 can be confirmed on site. The round steel 1 in the embodiment is made of stainless steel, Ø6-8mm, the round steel spacing is 10~15mm, the size of the outer rib ring 2 is 10mm thick * 30mm wide; the rib plate is 10mm*30mm.

[0023] S2. Grinding media addition standards: 1. Steel ball diameter 30mm; 2. Ceramic ball addition specifications: 15mm, 25mm, 20mm 3. The weight ratio of porcelain ball to steel ball is: 5:5 4. Use "ceramic balls and steel balls" to add grinding media. The initial filling rate of ceramic balls is 25%, the filling rate of steel balls is 12%, and the filling rate of grinding media is controlled below 40%; 1) The specific gravity of the ceramic ball pile is 2.2g / cm 3, the filling rate is calculated as 25%, then the total weight of the initial porcelain balls is 17.5t, of which 25mm: 20mm: 15mm = 8t: 6t: 3.5t; 2) The specific gravity of the steel ball pile is 4.85g / cm 3 According to calculation, if the filling rate is designed to be 12%, there should be 17.6t of steel balls in the ball mill.

[0024] S3, the steps of replacing and adding porcelain balls and steel balls include: 1. In the first stage, 15mm and 20mm ceramic balls were added, and the filling rate of the ball mill increased by 4.2%; Add 600kg of 20mm ceramic balls and 600kg of 15mm ceramic balls every day for 6 consecutive days until the budgeted 15mm ceramic balls are fully added; 2. In the second stage, 20mm and 25mm ceramic balls are added. Starting from the 7th day, add 400kg of 25mm ceramic balls and 400kg of 20mm ceramic balls every day for 10 consecutive days until the budgeted 20mm ceramic balls are fully added; 3. In the third stage, steel balls are added to improve grinding efficiency; Starting from the 17th day, add 300 kg of 25 mm ceramic balls and 800 kg of steel balls for 30 consecutive days until the initial addition of ceramic balls is completed; 4. The fourth stage is to determine the best ratio of porcelain balls to steel balls; Starting from the 47th day, 280 kg of porcelain balls and 600 kg of steel balls are added daily; Starting from about 55 days later, the porcelain balls were optimized to 260kg per day and the steel balls to 550kg per day. The porcelain ball weight: steel ball weight = 1:2.1 was found on site, and the comprehensive unit consumption was stabilized at 0.167kg / t. 原矿 Indicators at different stages such as Figure 4 As shown in Table 1.

[0025] Also note that: 1) Control the grinding concentration range to 60-65%; the total filling rate to below 39%; 2) During the process of adding ceramic balls, if the grinding is too fine, stop adding ceramic balls for 1-2 days, depending on the actual fineness of the sample; 3) If you find that there is still a lot of steel forging in the mill after adding porcelain balls, you can temporarily stop adding steel balls and start adding steel balls when the fineness changes (becomes coarser).

[0026] After applying the method of the present invention, under the premise that the process indicators "discharging particle size - 200 mesh content (%)" and "classification circulation volume (%)" meet the standards, Figure 5As shown in Table 2, the unit consumption of grinding media is reduced from the original 0.28kg / t (steel forging) to 0.167kg / t (ceramic ball + steel ball), and the unit power consumption of the three-stage ball mill is reduced from the original 3.184kwh / t to 2.288kwh / t. The comprehensive cost is reduced by 0.501 yuan / t of raw ore. Calculated based on the annual processing capacity of 9 million tons of raw ore, the annual benefit is about 4.5 million yuan, and the adjustment period is shortened by 24 days.

Claims

1. A method for adding grinding media to a ball mill, characterized in that it comprises the following steps: S1. Preparation: Add a discharge grid at the discharge end of the ball mill; S2. Set the addition standard of grinding media:

1. Steel ball addition specifications: Steel ball diameter D 钢 =24.5*d 1 / 2 mm; where d is the maximum particle size of the ball mill feed; 2. The size of the ceramic ball is divided into three specifications: D 瓷1 =D 瓷 , D 瓷2 =D 瓷 -5mm, D 瓷3 =D 瓷 -10mm; 3. The weight percentage of three different specifications of ceramic balls is G 瓷1 :G 瓷2 :G 瓷3 =45%:35%:20%; 4. Standard proportion of porcelain balls and steel balls: The three-stage sand return ratio is ≥250%, and the ratio of porcelain balls to steel balls is less than 4:6; The sand return ratio of the third stage is 180~250%, and the ratio of porcelain ball to steel ball is 5:5; The three-stage sand return ratio is ≤180%, and the ratio of porcelain balls to steel balls is above 6:4; S3. Add porcelain balls and steel balls: S31, first stage, adding ceramic ball D 瓷2 and porcelain ball D 瓷3 , so that the filling rate of the ball mill is increased by 4-6%; S32, second stage, adding ceramic ball D 瓷1 and D 瓷2 , stabilize the grinding efficiency of the three-stage ball mill; S33, the third stage, adding ceramic ball D 瓷1 and steel ball D 钢， At this stage, it is estimated that all the steel forgings in the original belly of the ball mill will be consumed: S34, the fourth stage, determine the porcelain ball D 瓷1 With steel ball D 钢 The best ratio.

2. The method for adding grinding media to a ball mill according to claim 1, characterized in that: The opening rate of the discharge grid is ≥32%, and the aperture width is 0.65~0.75*D 瓷 , where D 瓷 It is the minimum diameter of the initial ceramic ball.

3. The method for adding grinding media to a ball mill according to claim 1, characterized in that: The first stage adds ceramic ball D 瓷2 and porcelain ball D 瓷3 The standards are:

1. Add ceramic balls D during the ball mill filling rate improvement stage 瓷2 and porcelain ball D 瓷3 The weight of each accounts for 20%; 2. Adding cycle 6-8 days, small size ceramic ball D 瓷3 After all the additions are completed in the first stage, D 瓷2 Add 45% of the budgeted weight.

4. The method for adding grinding media to a ball mill according to claim 1, characterized in that: The second stage adds ceramic ball D 瓷1 and porcelain ball D 瓷2 , the standard is:

1. Add 45% by weight of ceramic ball D 瓷1 and porcelain ball D 瓷2 , where the ceramic ball D 瓷2 All are added at this stage; 2. The total amount of addition is completed in 7-9 days, and the daily addition amount is calculated based on 60-70% of the original steel forging consumption; 3. Observe the decrease in the operating current of the ball mill and analyze the grinding efficiency. If there is ore leakage in the subsequent process, add 1~2t of steel balls if necessary to improve the grinding efficiency.

5. The method for adding grinding media to a ball mill according to claim 1, characterized in that: The third stage adds porcelain ball D 瓷1 and steel ball D 钢 The standards are:

1. The amount of steel ball added = (0.5~0.7) * the daily consumption of original steel forging / day; 2. Porcelain ball D 瓷1 Addition amount = (0.2~0.3) * original steel forging daily consumption / day; 3. The adding cycle is controlled within 25 to 30 days.

6. The method for adding grinding media to a ball mill according to claim 1, characterized in that: The fourth stage determines the ball D 瓷1 With steel ball D 钢 The best ratio of standards:

1. The on-site process must meet the grinding and classification efficiency. When the grinding efficiency is low, increase the proportion of steel balls; when the on-site three-stage circulation volume is small, increase the proportion of porcelain balls; 2. With the goal of reducing the power consumption of the three-stage ball mill, adjust the proportion of porcelain balls, with the addition amount of porcelain balls fluctuating within ±1kg and the addition amount of steel balls fluctuating within ±2kg; 3. Control the consumption cost of grinding media, that is: the cost of porcelain balls and steel balls ≤ the cost of steel forging.

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