What Is a Ball Mill?
Ball mill is the key equipment for crushing materials. This type of grinder is filled with a certain number of steel balls as grinding media in its barrel.
The ball mill is made of horizontal
Ball mill
The ball mill is composed of the feeding part, the discharging part, the turning part, and the transmission part (reducer, small transmission gear, motor, electronic control) and other main parts. The hollow shaft is made of cast steel, and the inner lining can be replaced. The rotary gear is processed by casting hobbing. The cylinder is equipped with a wear-resistant liner, which has good wear resistance. The machine runs smoothly and works reliably.
The main body of the ball mill includes a cylinder body, which is lined with a lining made of abrasion-resistant materials, a bearing that carries the cylinder body and maintains its rotation, and a driving part, such as a motor, and transmission gears, pulleys, V-belts, etc.
As for the parts called blades, they are generally not the main components. The internal spiral at the feed end of the component can be called its internal spiral blade, and the internal spiral at the outlet of the component can also be called its internal spiral blade.
In addition, if the screw conveyor is used in the auxiliary equipment at the discharge end, there will be parts called spiral blades in the equipment, but strictly speaking, it is no longer a part of the ball mill.
Depending on the material and the way of ore discharge, dry ball mills and wet lattice ball mills can be selected. Energy-saving ball mill adopts self-aligning double-row radial spherical roller bearings, which has small running resistance and significant energy saving effect. In the cylinder part, a section of conical cylinder is added at the discharge end of the original cylinder, which not only increases the effective volume of the mill, but also makes the medium distribution in the cylinder more reasonable. This product is widely used in non-ferrous metal, ferrous metal, non-metal beneficiation sites and chemical and building materials industries for material grinding.
(1) Increase effective volume
Increasing the effective volume of the mill can increase the productivity of the mill year on year. The thickness of the lining plate and the weight are large, which increases the power consumption, reduces the effective volume of the cylinder, and reduces the production efficiency of the ball mill. If the magnetic liner is selected, the effective volume of the cylinder can be increased, while the weight is relatively reduced, and the power consumption is reduced. However, the use of thinner magnetic liners has certain disadvantages. Due to the small thickness, the impact resistance is not as good as the existing Cr-Mn-Mo alloy cast steel liners, which are prone to cracking problems. For example, for the problem of lining boards, some manufacturers use grooved ring-shaped lining boards, which increase the contact surface of ball ore, strengthen the grinding effect, and have the ability to enhance the ore, reduce energy consumption, and are widely used.
(2) Increase filling rate and speed
The processing capacity of the ball mill increases with the increase of the filling rate of the steel ball. Increasing the filling rate increases the probability that the steel ball crushes the ore and the self-grinding effect of the ore. When the steel ball filling rate is 45%, the load of the ball mill is the largest, and when it exceeds 45%, the load decreases significantly with the increase of the filling rate. This is mainly because with the increase of the filling rate, the lifting point of the steel ball is raised, and the impact force of the falling steel ball accelerates towards and over the center of rotation, and the resultant torque is greatly shortened and becomes O to negative. The load required by the impact torque of the steel ball (containing ore) dropped from large to zero until it becomes the driving force to rotate the cylinder (that is, the resultant force exceeds the center, and the resultant torque is negative).
(3) Change the shape of the grinding medium
Ellipsoidal medium can be used instead of the current spherical medium. Compared with the spherical ball, the advantages of the oval ball are as follows:
Compared with a ball of the same diameter, the oval ball has a weight increase of 62%, a strong impact force, and an improved crushing capacity;
Elliptical spheres are replaced by line contacts instead of point contacts between spheres.The contact area is 4 times larger than that of spheres. It has selective crushing and good sieving effect on materials, and the product size is uniform, reducing over crushing.
Compared with oval balls of the same diameter, the surface area of the ball increases by 8%, which increases the contact surface between the steel ball medium and the material, and improves the grinding capacity;
The elliptical ball and the mill liner use line contact instead of the point contact of the round ball, which reduces the wear of the steel ball medium on the liner, reduces the impact of the steel ball medium and the mill liner, thereby reducing the steel ball medium and grinding. The wear of the machine lining board prolongs the service life;
The oval ball also has antistatic and anti-humidity effects, which can reduce the adsorption of fine powder and reduce the phenomenon of fullness.
Compared with round spheres, the ellipsoidal sphere can greatly improve the crushing and grinding capabilities of the ball mill, and at the same time reduce the equipment loss. [5]
Ball mill installation:
a) The installation plan is designed according to the user's basic engineering, and it should be installed according to the direction, location and space shown in the figure;
b) The lower plane of the fuselage should be grounded, and the level of the bottom surface of the cylinder after level adjustment is not greater than 1.5 / 1000;
Installation
a) Remove foreign objects in the reserved holes of the installation equipment foundation, especially the inner wall of the holes must be free of dust, oil, water and other liquids;
b) After unpacking the box, use a suitable lifting facility (crane / forklift) to move the main unit to the installation position;
c) Place the equipment in the installation holes of the anchor bolts, put the live feet of the random belt on the anchors of the anchors, and weld them to the chassis of the rack before performing the second grouting;
d) After installing the cement for 24 hours, tighten the nut to load the test machine;
e) Connect power;
f) Installation inspection and correction of inappropriate places;
g) The electrical cabinet is placed in the auxiliary machine room without installing feet.
2. Test run:
The installation of the ball mill is completed. After passing the inspection, an empty car trial operation can be carried out. The test operation of the ball mill should be performed by a skilled ball mill operator, and the ball mill safety operation regulations must be strictly observed.
(1) The continuous running time of dry running is not less than 12-24 hours, and problems found during running should be solved in time.
(2) The load test operation can be carried out when the dry running test machine is normal. The load test operation should be carried out in stages. During the load operation, feeding should be performed according to the discharge conditions to avoid unnecessary wear and damage of the steel balls and the cylinder liner. .
a) Add appropriate materials and 1/3 quantity of steel balls (refer to the general diagram of the ball mill for the maximum ball loading capacity) for a trial run of 12-24 hours.
b) Add 2/3 of the steel balls and run for 24-48 hours.
c) According to the discharge condition of the ball mill and the output of qualified products, refer to the actual ball loading capacity of the ball mill of the same type of concentrator to determine the reasonable ball loading capacity of this ball mill, and perform a test run of not less than 72 hours.
(3) The increase of the above load and the length of test run time are determined based on the running-in conditions (temperature rise, noise, tooth surface contact, etc.) of the large and small gears and reducer gears. Do not run at full load until the tooth surface contact accuracy does not meet the design requirements.
(4) The cooling and lubrication system should work normally during the trial operation, and the temperature of the main bearing, transmission bearing and reducer should be normal.
(5) After putting in 2/3 quantity of steel balls for trial operation for 24-48 hours, check and tighten all bolts again.
(6) The commissioning work should be carefully recorded.
The ball mill is mainly used for the mixing and grinding of ceramic raw materials. It is an indispensable device for the production of various ceramic products. The machine uses auto-coupling and decompression to reduce the starting current. Its structure is divided into integral and independent. It adopts V-belt transmission, single-stage or double-stage deceleration, and is equipped with independent low-power motor for loading and unloading. [5]
The ball mill should be installed on a solid concrete foundation. For the basic design and construction of the ball mill, please refer to the ball mill general assembly drawing and basic drawing. In order to ensure that the position accuracy of each part of the ball mill does not change greatly during use, the foundation of the ball mill should adopt a monolithic structure.
After the compressive strength of the concrete foundation reaches more than 75%, a ball mill can be installed on it. Before the installation, the quality of the foundation should be inspected. It is required that the concrete has no defects that affect the strength. The number and location of the reserved holes meet the requirements. There are no debris, water, and oil in the reserved holes. When using the "ground wire method" for installation operations, a "central target plate" should be embedded on the surface of the foundation. Before installation, draw all the centerlines and make a striking punch mark on the "center standard plate" as the centerline reference during installation.
Before hoisting, the ball mill should be inspected and accepted in full, and any problems should be solved in time.
1. For the specific requirements of the main bearing part, refer to the main bearing component assembly drawing.
2. Refer to the assembly drawing of the rotary part for the cylinder part.
3. Refer to the assembly drawing of the transmission part for the transmission part.
4. Refer to the assembly drawing for the overall relative position. [5]
Mine ball mill model | Barrel speed (Per minute) | Ball load (Ton) | Feed size (mm) | Discharge size (Mm) | Yield (t / h) | Motor power (kw) | Weight (t) |
MQ750 × 1060 | 1.6 | 4 | 20 | 1.075-0.89 | 1.14 ~ 0.34 | 1.5 | 1.6 |
900 × 3000 | 36 | 1.7 | 20 | 1.075-0.89 | 1.1-3.5 | twenty two | 1.6 |
The main technical parameters of the cone ball mill:
Specifications | Feeding size (mm) | Output granularity (mm) | Yield (t / h) | Motor Power (kw) | weight (kg) |
GZM900 × 2100 | 15 | 1.075-0.83 | 1.7-3.5 | 15 | 3900 |
GZM1200 × 2800 | 25 | 1.075-0.6 | 2-6 | 37 | 13000 |
GZM1500 × 3500 | 25 | 1.075-0.4 | 1.5-12 | 75 | 17500 |
GZM1830 × 3600 | 25 | 1.075-0.4 | 5-22 | 130 | 33500 |
GZM2100 × 3600 | 25 | 1.075-0.4 | 15-36 | 210 | 46800 |
GZM2400 × 3000 | 25 | 1.075-0.4 | 22-44 | 245 | 59000 |
Main technical parameters of cement mill:
Specifications (m) | Production capacity (t / h) | Mill form | transmission form | power (kw) | Reducer | weight (t) | Remark |
model | Speed ratio |
2.2 × 7m | 8-9 | Open stream | edge | 380 | ZD70 | 5 | 54 | |
2.2 × 7.5m | 10-11 | Open stream | edge | 380 | ZD70 | 5 | 63 | |
2.2 × 8m | 10-12 | Open stream | edge | 380 | ZD70 | 5 | 65 | |
2.2 × 9.5m | 14-16 | Open stream | edge | 475 | ZD70 | 5 | 70 | |
2.4 × 10m | 19-19 | Open stream | edge | 630 | JR75 | 1.64 | 1.5 | Without motor |
2.4 × 11m | 19-21 | Open stream | edge | 630 | RZD80 | 1.3 | 1.2 | Without motor |
2.4 × 13m | 21-23 | Open stream | edge | 800 | MBY710 | 1.1 | 1.2 | Without motor |
2.6 × 13m | 28-32 | Open stream | edge | 1000 | MBY800 | 1.1 | 148 | |
2.6 × 13m | 28-32 | Open stream | center | 1000 | MFY100 | 1.5 | 1.73 | |
3 × 12m | 32-35 | Open stream | edge | 1250 | MBY900 | 1.1 | 1.6 | |
3 × 13m | 34-37 | Open stream | edge | 1400 | MBY900 | 1.1 | 1.26 | |
3.2 × 13m | 45-50 | Open stream | edge | 1600 | MBY1000 | 1.1 | 1.26 | |
3.8 × 13m | 60-62 | Open stream | center | 2500 | MFY250 | 1.5 | 204 | |
4.2 × 13m | 85-87 | Open stream | center | 3530 | JQS3550 | 1.6 | 254 | |
Ceramic ball mill technical parameters:
model | Loading (Tons / time) | Cylinder speed (r / min) | Power (kw) |
600 × 700 | 1.05 | 50 | 1.02 |
800 × 600 | 1.075 | 42 | 3 |
900 × 1200 | 1.2 | 1.5 | 1.5 |
1300 × 1500 | 1.5 | 33 | 1.5 |
1500 × 1800 | 1.2 | 1.5 | 11 |
1800 × 2000 | 1.5 | twenty four | 15 |
2600 × 2800 | 5 | 1.5 | 37 |
3000 × 3800 | 10 | 1.5 | 1.2 |
3200 × 4600 | 15 | 1.5 | 75 |
3400 × 6600 | 18 | 13 | 135 |
The maintenance and repair of the ball mill is a regular work. The quality of the repair work directly affects the operation rate and service life of the ball mill. Then how to properly maintain and repair the ball mill during use will be introduced below:
1. All lubricating oil should be discharged when the mill is put into continuous operation for one month, thoroughly cleaned and replaced with new oil. In the future, the oil will be changed every 6 months in combination with the intermediate repair.
2. Check the lubrication condition and oil level of each lubrication point at least every 4 hours.
3. When the mill is running, the temperature rise of the main bearing lubricant does not exceed 55 ° C.
4. During normal operation of the mill, the temperature rise of the transmission bearing and reducer does not exceed 55 ° C, and the maximum does not exceed 60 ° C.
5. The large and small gears are driven smoothly without abnormal noise. If necessary, the gap should be adjusted in time.
6. The ball mill runs smoothly without strong vibration.
7. The motor current should be free from abnormal fluctuations.
8. There is no loosening of each connecting fastener, no oil leakage, five leakage of water, and no leakage of minerals on the joint surface.
9. Steel balls are added in time according to the wear condition.
10. If abnormal conditions are found, the grinding and maintenance shall be stopped immediately.
11. The mill liner should be replaced when it is worn by 70% or has a crack of 70mm length.
12. Liner bolts should be replaced when damaged.
13. The main bearing should be replaced when it is severely worn.
14. The ladle plate of the lattice ball mill is worn so that it can no longer be repaired.
15. The gear face of the large gear can be turned over and continued to be used after being worn to a certain extent.
16. The pinion should be replaced if it is severely worn.
17. Welding should be done in time when the inlet and outlet spirals are worn, and they should be replaced when they are worn out.
18. Loose or damaged anchor bolts should be repaired in time.
A regular work during the maintenance of the ball mill, the quality of the maintenance work directly affects the operation rate and service life of the ball mill. In order to find defects in time and eliminate hidden dangers to ensure the normal operation of the mill, in addition to routine maintenance, grinding needs to be stopped regularly (once a month is recommended). Important components such as hollow shafts, main bearings, cylinders, reducers, The small and large gears are carefully checked and detailed records are made. According to the deficiencies, make appropriate treatments and arrange intermediate and overhaul plans. [5]
The bearing position and bearing chamber of the ball mill reducer, under high-load low-speed, heavy-load high-speed high-torque startup, and under the action of equipment vibration and radial impact, metal fatigue occurs in the bearing chamber or bearing position, resulting in permanent deformation; inside the bearing There is a clearance fit between the ring and the shaft or the outer ring of the bearing and the bearing chamber, resulting in wear on the relative movement. Once this problem occurs, it will seriously affect the normal production of the equipment. If the bearing room of the reducer of the ball mill is worn, this kind of problem is difficult to be repaired on-site by traditional methods, and the external repair is difficult to repair due to the limitations of the material and wear size of the parts. Usually, new parts are used to solve it. Quickly, spare parts take up huge funds. Adopted by developed countries in the 21st century
1. When the ball mill is running, there are regular knocking sounds, and the sound is loud. It is because some of the liner bolts are not tightened. When the ball mill rotates, the liner hits the ball mill barrel. Judge by sound
The configuration of the ball mill is quite expensive: due to the low rotation speed of the barrel of the ball mill (15 to 25 revolutions per minute), if it is driven by a common motor, it needs to be equipped with an expensive reduction gear.
High production cost: while the grinding body impacts and grinds the material, it also needs to be abraded and stripped, and the liner and other parts in the cylinder are also abraded and stripped. Therefore, during the entire cement production process, the grinding operation (raw material preparation, grinding The amount of iron plates consumed is very large. According to analysis, about 1 kg of steel is consumed for each ton of cement produced.
Low working efficiency: For example: in the process of producing cement, the electricity used for crushing operations accounts for about two-thirds of the entire plant. According to statistics, the power consumption per ton of cement produced is not less than 70 kWh, but this part The effective utilization rate of electric energy is very low. According to analysis, the power input by the cement ball mill for pulverizing materials (doing useful work) accounts for only a small part of the power consumption, about 5% to 7%, and most of the power is consumed by other On the one hand, it is mainly converted into thermal and acoustic energy and disappears, which is a great waste.
Bulky: The total weight of a large ball mill can be hundreds of tons or more, so the one-time investment is bound to be large.
At present, most ball mills in China are still in the state of manual control, which causes large changes in the material in the mill, low grinding efficiency, large unit power consumption, and large losses of steel balls and liners. In addition, due to the large change in the grinding state, it is difficult to ensure the uniformity of the fineness of the material. The planetary ball mill is designed for crushing, grinding, and dispersing powders, and is widely used in laboratory research. Its working principle is to use the high-speed running force in the grinding tank of the mill to grind the material. During the turning process, the material is finally subjected to a series of shearing, impact, rolling, and dispersion to complete the grinding operation. The planetary ball mill has four grinding ball tanks on one turntable, and they work with the grinding shaft to perform rotation motion, that is, planetary motion. During the movement, the four tanks grind the material through friction and collision. The mill can select the corresponding friction method according to the size of the abrasive grains of the material, and the final abrasive grain diameter can reach 0.1 micron. It can well meet the requirements of various process parameters, and is the first choice of equipment for pulverization process, new materials and coatings research. [5]
To increase the output of the ball mill, we must not only start with process factors and mechanical factors, but also ensure that the ball mill is effectively managed and controlled! The main purpose of management is to prevent the occurrence and elimination of diseased operating conditions, to achieve fine operation of equipment, and to achieve high-quality, high-stage production with low power and ball consumption.
Steps to achieve fine operation: A reasonable production index refers to the operation target, and the index must determine the upper and lower limits; the correct operating parameters are the process paths that must be controlled; and the troubleshooting measures refer to the failure to be timely and fast when the operation method is executed exclude. So today I will elaborate these steps of fine operation:
Reasonable index
Reasonable production indicators can not only increase the enthusiasm of employees, but also a measure of cost control for the enterprise. The indicators with upper and lower limits can be determined through the internal performance of the equipment and various factors.
2. Correct operating parameters
The operation and control of the ball mill are mainly based on the two parameters of circulating load and powder selection efficiency, and the three parameters of wind, material and fineness are reasonably matched to control the grinding condition and fineness of the finished product.
3. Troubleshooting
For troubleshooting, how to find the cause in a timely manner, and troubleshoot safely and reliably is a necessary content for detailed operations.
1. Before turning on the equipment, we first need to check the lubrication between various mechanical parts. After confirming that all preparations have been completed, first start the ball mill discharge device, the ball mill general power supply, and finally start the feeding device.
2. Before the material enters the box, you need to check whether the steel spheres installed in the box are set and the quantity is appropriate. 3. After turning on the ball mill, it is necessary to first test the empty box. After ensuring that the contact surface between the box and the mechanical parts is sealed and well lubricated, the operation is started. 4. Moreover, the start-up of the ball mill is carried out in cooperation with the personnel of other work positions. The staff who operate the machine can only carry out after seeing the corresponding command signal. 5. Be sure to close the discharge port only after confirming that both the material and the feed port have stopped running. 6, usually to the equipment maintenance work to be timely, reasonable and comprehensive. After the ball mill is completely stopped, it is necessary to carefully clean the grinding medium in the box to prolong the service life of the mechanical equipment and reduce the industrial cost.
1.Ensure the production capacity of the mill
The selected grinding equipment can complete the required output under the condition that the required grinding fineness is achieved.
2.The production capacity should be higher than the design time
The design should take into account changes in the hardness and fineness of the ore. Generally, the ore in the deep part of the ore is hardened or thinned. The selected pulverizer should also be able to adapt, and at the same time ensure that the initial smooth production.
3. Must do grinding test
When there is no actual data in the design as a basis, a grinding test must be required. Especially for large-scale beneficiation plants, the grinding machine selection calculation and scale-up should be performed from the basic data obtained.
4. Give due consideration to large equipment
Large-scale equipment is a design trend since the 21st century. Due to the large-scale equipment, the total equipment is light in weight, occupies less land, has fewer production systems, fewer operators and auxiliary systems, and the corresponding investment and production costs are low. However, large-scale equipment requires high levels of operation and management. If the operating rate is slightly reduced, the output of the ore dressing plant will be greatly reduced.
5.Select equipment with high operating rate
There are good and bad in the same type of equipment. Rod mills and self-mills sometimes have lower operating rates, but they are still applicable under certain conditions. In principle, equipment with a high operating rate should be selected to reduce maintenance and downtime.
6, understand the hardness, grade and other properties of minerals, try to choose energy-saving ball mills;
7, know the fineness required for mineral grinding, according to the fineness required by your own minerals, choose the aperture and the position of the bin;
8. According to the output requirements, the diameter and length of the ball mill should be selected appropriately.
9. Select a new generation of modified ball mill, it is best to buy it from a professional ball mill manufacturer corresponding to your mineral type.
10. Select the manufacturers of the large and small teeth of the ball mill, as well as the manufacturers of motors and subtractors. According to the price of the ball mill, the material of the lining plate and the thickness of the body steel plate are required. [5]
