Method of adding grinding media to a ball mill

Abstract

The application belongs to the technical field of mineral processing in the metallurgical industry, and provides an adding method of grinding medium of a ball mill. The method replaces the original steel forging natural consumption in the ball mill by using the ball mill in the operation process, realizes the replacement of mixed grinding medium of porcelain balls and steel balls in the continuous operation of the ball mill, does not need to stop, solves the production fluctuation of the mixed grinding medium not adapting to the on-site grinding index in the replacement process, the ball discharge end spits ball problem of the ball mill, quickly finds out the best matching ratio of the size and quantity of the added porcelain balls and steel balls in different ball mills, reduces the workload of removing all the steel balls and the cost of adding a large number of porcelain balls for the first time, and finally shortens the replacement period of the new type of wear-resistant grinding medium, stabilizes the production, and reduces the comprehensive cost in the replacement process of the porcelain balls.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology in the metallurgical industry, and relates to the addition of grinding media in a ball mill, specifically a method for adding grinding media in a ball mill. Background Technology

[0002] In the mineral processing process, grinding enables the useful minerals in the raw ore to reach a state of individual liberation, creating favorable conditions for the beneficiation process.

[0003] Forged steel is a commonly used grinding media in ball mills. In recent years, nano-ceramic composite balls (hereinafter referred to as ceramic balls) have emerged as a new material for grinding media, possessing characteristics such as high wear resistance, high hardness, high compressive strength, uniform particle size of the ground products, low grinding power consumption, and low ball consumption. Compared with traditional steel balls / forged steel, 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 drawbacks:

[0004] 1. It will take at least a week of production stoppage to completely remove all the steel forgings from the original ball mill and add them back according to the initial ball loading ratio of ceramic balls and steel balls. This will inevitably affect the production schedule. Moreover, the manpower, material resources and financial resources required for cleaning the site are relatively large. The original steel forgings of each ball mill will be seriously wasted as scrap.

[0005] 2. Initially, the ceramic balls and steel balls were added according to the initial ball loading ratio. During the gradual addition process, due to the incompatibility with the production site, the production fluctuations of the grinding indicators were amplified. For example, the fine screen circulation volume increased and the classification efficiency decreased when the content of the -200 mesh discharge particle size of the third mill was less than 70%. When the grinding concentration was higher than 65%, ball spitting occurred. The vicious cycle of circulation volume exceeding 350% directly caused the system to reduce production and other production impacts.

[0006] 3. The optimal ratio of ceramic balls and steel balls in different ball mills requires a long period of exploration, with an adjustment period of at least three months.

[0007] 4. If the raw ore is difficult to grind and beneficiate, the large circulation volume of the ball mill will cause the grinding concentration to increase. The specific gravity of the ceramic balls will be close to that of the slurry, and the ball mill will discharge balls at the discharge end. Summary of the Invention

[0008] The purpose of this invention is to provide a method for adding grinding media in a ball mill, which solves the problem that production needs to be stopped during the replacement process of "ceramic balls and steel balls", reduces the waste of manpower, material resources and materials, and achieves the goals of stabilizing grinding efficiency, eliminating waste, shortening cycle and reducing costs.

[0009] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0010] A method for adding grinding media to a ball mill includes the following steps:

[0011] S1. Preparation: Install a discharge grid at the discharge end of the ball mill;

[0012] S2. Set the addition standard for grinding media:

[0013] 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 ore feed to the ball mill;

[0014] 2. Ceramic balls are available in three sizes: D 瓷1 =D 瓷 D 瓷2 =D 瓷 -5mm, D 瓷3 =D 瓷 -10mm

[0015] 3. The weight percentage of the three different sizes of ceramic balls added is G. 瓷1 :G 瓷2 :G 瓷3 =45%:35%:20%;

[0016] 4. Standard ratio for adding ceramic balls and steel balls:

[0017] The three-stage sand return ratio should be ≥250%, and the ratio of ceramic balls to steel balls should be 4:6 or less;

[0018] The three-stage return sand ratio is 180-250%, and the ratio of ceramic balls to steel balls is 5:5;

[0019] The three-stage sand return ratio should be ≤180%, and the ratio of ceramic balls to steel balls should be 6:4 or higher.

[0020] S3, Replacement with ceramic and steel balls:

[0021] S31, First stage: Add ceramic balls D 瓷2 And porcelain ball D 瓷3 This increases the ball mill filling rate by 4-6%.

[0022] S32, Second stage: Add ceramic balls D 瓷1 and D 瓷2 Stabilize the grinding efficiency of the three-stage ball mill;

[0023] S33, Third Stage: Add ceramic balls D 瓷1 And steel ball D 钢 The third phase is expected to consume all the original steel forgings inside the ball mill:

[0024] S34, Fourth Stage, Determine D 瓷1 With D 钢 The optimal ratio.

[0025] Furthermore, the discharge grid has an opening ratio of ≥32% and an aperture width of 0.65~0.75*D. 瓷 D 瓷 The initial diameter of the ceramic ball is the smallest.

[0026] Furthermore, in the first stage, ceramic balls D are added. 瓷2 And porcelain ball D 瓷3 The standard is:

[0027] 1. Adding ceramic balls D during the ball mill filling rate improvement stage 瓷2 And porcelain ball D 瓷3 Each of these amounts accounts for 20% of the budget.

[0028] 2. Adding cycle is 6-8 days, small-sized ceramic balls D 瓷3 All additions were completed in the first phase, D 瓷2 Add 45% of the budgeted weight.

[0029] Furthermore, in the second stage, ceramic balls D are added. 瓷1 And porcelain ball D 瓷2 The standard is:

[0030] 1. Add 45% by weight of ceramic balls D 瓷1 And porcelain ball D 瓷2 Among them, ceramic ball D 瓷2 Complete all additions at this stage;

[0031] 2. The total amount to be added will be completed in 7-9 days, with the daily addition calculated based on 60-70% of the original steel forging consumption;

[0032] 3. Observe the decrease in the operating current of the ball mill and analyze the grinding efficiency. If there is ore runoff in the subsequent process, add 1-2 tons of steel balls if necessary to improve the grinding efficiency.

[0033] Furthermore, the third stage involves adding ceramic balls D. 瓷1 And steel ball D 钢 The standard is:

[0034] 1. Steel ball addition amount = (0.5~0.7) * original steel forging daily consumption / day;

[0035] 2. Porcelain ball D 瓷1 Addition amount = (0.2~0.3) * daily consumption of original steel forging / day;

[0036] 3. The addition cycle should be controlled within 25 to 30 days.

[0037] Furthermore, the fourth stage determines the ceramic ball D. 瓷1 With steel ball D 钢 The standard for the optimal ratio:

[0038] 1. On-site process must meet the standards, including grinding and classification efficiency. If the grinding efficiency is too low, increase the proportion of steel balls; if the on-site three-stage circulation volume is too low, increase the proportion of ceramic balls.

[0039] 2. To reduce the power consumption of the three-stage ball mill, the proportion of ceramic balls was adjusted, with the amount of ceramic balls fluctuating between ±1kg and the amount of steel balls between ±2kg.

[0040] 3. Control the cost of grinding media consumption, i.e.: the cost of ceramic balls and steel balls ≤ the cost of steel forging.

[0041] The beneficial effects of this invention are:

[0042] This invention enables the natural consumption of the original steel forging within the ball mill, eliminating the waste of discarded steel forging when replacing ceramic balls. The design of the discharge grid at the ball mill's discharge end solves the problem of reduced specific gravity after ceramic ball replacement and increased ball loss during on-site ball mill operation. Through the design of a four-stage mixing ratio of "ceramic balls + steel balls," stable and reliable on-site grinding indicators are achieved, eliminating production fluctuations during ceramic ball replacement. By analyzing on-site operating indicators, the optimal ratio of "ceramic balls and steel balls" can be found in the shortest possible time, shortening the replacement stabilization cycle by more than 20 days and minimizing the series grinding costs. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the discharge grid of the ball mill in the embodiment;

[0044] Figure 2 yes Figure 1 Sectional view of AA;

[0045] Figure 3 This is a flow chart of grinding media addition and replacement.

[0046] Figure 4 Table 1 shows the indicator data for different stages in the embodiment;

[0047] Figure 5 Table 2 shows a comparison of indicators before and after using the method of this invention;

[0048] In the diagram: 1. Round steel bar; 2. Outer reinforcing ring; 3. Rib plate. Detailed Implementation

[0049] The method of the present invention will be further described below with reference to embodiments:

[0050] A method for adding grinding media to a ball mill includes the following steps:

[0051] S1. Preparations:

[0052] A discharge grid with an opening ratio of ≥32% and a pore width of 0.65~0.75*D is added to the discharge end of the ball mill.瓷 D 瓷 The minimum diameter of the initial ceramic ball being loaded;

[0053] S2. Set the addition standard for grinding media:

[0054] 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 ore feed to the ball mill;

[0055] 2. Ceramic balls are available in three sizes: D 瓷1 =D 瓷 D 瓷2 =D 瓷 -5mm, D 瓷3 =D 瓷 -10mm

[0056] 3. The weight percentage of the three different sizes of ceramic balls added is G. 瓷1 :G 瓷2 :G 瓷3 =45%:35%:20%;

[0057] 4. Standard ratio for adding ceramic balls and steel balls:

[0058] The three-stage sand return ratio should be ≥250%, and the ratio of ceramic balls to steel balls should be 4:6 or less;

[0059] The three-stage return sand ratio is 180-250%, and the ratio of ceramic balls to steel balls is 5:5;

[0060] The three-stage return sand ratio should be ≤180%, and the ratio of ceramic balls to steel balls should be 6:4 or higher.

[0061] S3, Replacement with ceramic and steel balls:

[0062] S31, First stage: Add ceramic balls D 瓷2 And porcelain ball D 瓷3 This increases the ball mill filling rate by 4-6%.

[0063] 1. Add D during the ball mill filling rate improvement stage 瓷2 D 瓷3 porcelain balls; D 瓷2 D 瓷3 Each of these amounts accounts for approximately 20% of the budget.

[0064] 2. Adding cycle is 6-8 days, small-sized ceramic balls D 瓷3 All additions were completed in this stage, D 瓷2 Add 45% of the budgeted weight.

[0065] S32, Second stage: Add ceramic balls D 瓷1 and D瓷2 Stabilize the grinding efficiency of the three-stage ball mill:

[0066] 1. Add 45% by weight of ceramic balls D 瓷1 And porcelain ball D 瓷2 Among them, ceramic ball D 瓷2 Complete all additions at this stage;

[0067] 2. The total amount to be added will be completed in 7-9 days, with the daily addition calculated based on 60-70% of the original steel forging consumption;

[0068] 3. Observe the decrease in the operating current of the ball mill and analyze the grinding efficiency. If there is ore runoff in the subsequent process, add 1-2 tons of steel balls if necessary to improve the grinding efficiency.

[0069] S33, Third stage: Add ceramic balls D 瓷1 And steel ball D 钢， It is expected that all the original steel forgings inside the ball mill will be consumed during this stage.

[0070] 1. Steel ball addition amount = (0.5~0.7) * original steel forging daily consumption / day;

[0071] 2. Porcelain ball D 瓷1 Addition amount = (0.2~0.3) * daily consumption of original steel forging / day;

[0072] 3. The addition cycle should be controlled within 25 to 30 days.

[0073] S34, Fourth Stage, Determine D 瓷1 With D 钢 Optimal ratio:

[0074] 1. On-site process must meet the standards, including grinding and classification efficiency. If the grinding efficiency is too low, increase the proportion of steel balls; if the on-site three-stage circulation volume is too low, increase the proportion of ceramic balls.

[0075] 2. To reduce the power consumption of the three-stage ball mill, the proportion of ceramic balls was adjusted, with the amount of ceramic balls fluctuating between ±1kg and the amount of steel balls between ±2kg.

[0076] 3. Control the cost of grinding media consumption, i.e.: the cost of ceramic balls + steel balls ≤ the cost of steel forging. Example

[0077] Taking the replacement of the "ceramic ball + steel ball" mixed media in a three-stage grinding mill with an overflow ball mill of Ø3200*4500 as an example: Jianshan three-stage grinding mill adopts an overflow ball mill of Ø3200*4500 with a mill volume of 31.5m³. 3The filling rate is 32%, the maximum feed particle size is 1.5mm, the total weight of steel forgings inside the ball mill is 46870kg, the steel forging size is Ø25*30mm, the three-stage return sand ratio is 217%, and the steel forging unit consumption is 0.28kg / (t raw ore).

[0078] The method and process for adding grinding media in a displacement ball mill are as follows: Figure 3 As shown, it includes the following steps:

[0079] S1. Ball mill discharge end anti-ball ejection modification: A grate (grid) is added to the discharge end of the ball mill, with an opening ratio of 35.6% and a hole diameter width of 10mm, made of stainless steel. Figure 1 and Figure 2 As shown, the round steel 1 and the outer reinforcing ring 2 are fixed by the reinforcing plate 3, with no less than 8 fixing points. The outer reinforcing ring 1 is installed in the direction of the ore discharge outlet. The grid is symmetrically and evenly made for easy installation. All nodes should be firmly welded. The out-of-roundness error of Ø1060 is controlled within ±2mm. The dimensions of the round steel 1 and the outer reinforcing ring 2 can be confirmed according to the site. In this embodiment, the round steel 1 is made of stainless steel with a diameter of Ø6-8mm and a spacing of 10~15mm between round steels. The dimensions of the outer reinforcing ring 2 are 10mm thick and 30mm wide. The reinforcing plate is 10mm*30mm.

[0080] S2. Grinding media addition standard:

[0081] 1. The steel ball has a diameter of 30mm;

[0082] 2. Ceramic balls with sizes of 15mm, 25mm, and 20mm are added.

[0083] 3. The weight ratio of the ceramic ball to the steel ball is 5:5.

[0084] 4. The grinding media are added using ceramic balls and steel balls. 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%.

[0085] 1) The specific gravity of the ceramic balls is 2.2 g / cm³. 3 Assuming a filling rate of 25%, the total weight of the initial ceramic balls is 17.5t, of which 25mm:20mm:15mm = 8t:6t:3.5t.

[0086] 2) The specific gravity of the steel balls is 4.85 g / cm³. 3 Calculations show that, with a filling rate of 12% as the design, the ball mill should contain 17.6 tons of steel balls.

[0087] S3, the steps for replacing and adding ceramic balls and steel balls include:

[0088] 1. In the first stage, adding 15mm and 20mm ceramic balls increased the ball mill filling rate by 4.2%.

[0089] Add 600kg of 20mm ceramic balls and 600kg of 15mm ceramic balls daily for 6 consecutive days until all 15mm ceramic balls are replenished.

[0090] 2. In the second stage, 20mm and 25mm ceramic balls are added.

[0091] Starting from day 7, add 400 kg of 25 mm ceramic balls and 400 kg of 20 mm ceramic balls every day for 10 consecutive days until all 20 mm ceramic balls are added.

[0092] 3. In the third stage, steel balls are added to improve grinding efficiency;

[0093] Starting from day 17, add 300 kg of 25 mm ceramic balls and 800 kg of steel balls, and continue adding for 30 days until the initial ceramic ball replenishment is completed.

[0094] 4. The fourth stage involves determining the optimal ratio of ceramic balls to steel balls;

[0095] Starting from the 47th day, ceramic balls are replenished daily at a rate of approximately 280 kg and steel balls at a rate of approximately 600 kg.

[0096] Starting around day 55, the ceramic balls were optimized at a rate of 260 kg and the steel balls at approximately 550 kg per day. Through on-site testing, a ceramic ball to steel ball weight ratio of 1:2.1 was found, resulting in a stable overall unit consumption of 0.167 kg / t. 原矿 Indicators at different stages, such as Figure 4 As shown in Table 1.

[0097] Another point to note is:

[0098] 1) Control the grinding concentration range to 60-65%; the total filling rate to below 39%;

[0099] 2) If the ceramic balls are ground too finely during the process of adding them, the addition of ceramic balls should be stopped immediately for 1-2 days, depending on the actual fineness of the sample.

[0100] 3) If after adding ceramic balls, it is observed that there are still a lot of steel forgings in the mill, you can temporarily stop adding steel balls and start adding steel balls again when the fineness changes (becomes coarser).

[0101] After applying the method of this invention, provided that the process indicators "discharge particle size - 200 mesh content (%)" and "grading circulation volume (%)" meet the standards, such as Figure 5As shown in Table 2, the grinding media consumption per unit decreased from 0.28 kg / t (forged steel) to 0.167 kg / t (ceramic balls + steel balls), and the power consumption per unit of the three-stage ball mill decreased from 3.184 kWh / t to 2.288 kWh / t. The overall cost was reduced by 0.501 yuan / t of raw ore. Based on an annual processing capacity of 9 million tons of raw ore, the annual benefit is approximately 4.5 million yuan, and the adjustment cycle is shortened by 24 days.

Claims

1. A method for adding grinding media to a ball mill, characterized by comprising the following steps: S1. Preparation: Install a discharge grid at the discharge end of the ball mill; S2. Set the addition standard for 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 ore feed to the ball mill; 2. Ceramic balls are available in three sizes: D 瓷1 =D 瓷 D 瓷2 =D 瓷 -5mm, D 瓷3 =D 瓷 -10mm; 3. The weight percentage of the three different sizes of ceramic balls added is G. 瓷1 :G 瓷2 :G 瓷3 =45%:35%:20%; 4. Standard ratio for adding ceramic balls and steel balls: The three-stage sand return ratio should be ≥250%, and the ratio of ceramic balls to steel balls should be 4:6 or less; The three-stage return sand ratio is 180-250%, and the ratio of ceramic balls to steel balls is 5:5; The three-stage sand return ratio should be ≤180%, and the ratio of ceramic balls to steel balls should be 6:4 or higher. S3. Add ceramic balls and steel balls: S31, First stage: Add ceramic balls D 瓷2 And porcelain ball D 瓷3 This increases the ball mill filling rate by 4-6%. S32, Second stage: Add ceramic balls D 瓷1 and D 瓷2 Stabilize the grinding efficiency of the three-stage ball mill; S33, Third Stage: Add ceramic balls D 瓷1 And steel ball D 钢， It is expected that all the original steel forgings inside the ball mill will be consumed during this stage. S34, Fourth Stage: Determine the ceramic ball D 瓷1 With steel ball D 钢 The optimal ratio.

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

3. The method for adding grinding media in a ball mill according to claim 1, characterized in that: The first stage involves adding ceramic balls D. 瓷2 And porcelain ball D 瓷3 The standard is:

1. Adding ceramic balls D during the ball mill filling rate improvement stage 瓷2 And porcelain ball D 瓷3 Each accounts for 20% of the weight; 2. Adding cycle is 6-8 days, small-sized ceramic balls D 瓷3 All additions were completed in the first phase, D 瓷2 Add 45% of the budgeted weight.

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

1. Add 45% by weight of ceramic balls D 瓷1 And porcelain ball D 瓷2 Among them, ceramic ball D 瓷2 Complete all additions at this stage; 2. The total amount to be added will be completed in 7-9 days, with the daily addition 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 runoff in the subsequent process, add 1-2 tons of steel balls if necessary to improve the grinding efficiency.

5. The method for adding grinding media in a ball mill according to claim 1, characterized in that: The third stage involves adding ceramic balls D. 瓷1 And steel ball D 钢 The standard is:

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

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

1. On-site process must meet the standards, including grinding and classification efficiency. If the grinding efficiency is too low, increase the proportion of steel balls; if the on-site three-stage circulation volume is too low, increase the proportion of ceramic balls.

2. To reduce the power consumption of the three-stage ball mill, the proportion of ceramic balls was adjusted, with the amount of ceramic balls fluctuating between ±1kg and the amount of steel balls between ±2kg.

3. Control the cost of grinding media consumption, i.e.: the cost of ceramic balls and steel balls ≤ the cost of steel forging.

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