Ball mill

Cone crusher
  • 【Feed size】: ≤ 25mm
  • 【Production capacity】: 0.65-615t / h
  • 【Application】: for silver, cement, building materials, refractories, glass and ceramics, all kinds of metal and non-metallic materials such as grinding operations.
  • 【Products】: Silver ore ball mill is silver ore processing process must be used in the equipment, which is mainly used for silver grinding processing, the device is the SBM machine for the nature of silver and domestic and foreign ball mill developed from the advantages of , With significant performance and quality advantages.
Introduction of ball mill

The ball mill is composed of horizontal cylinder, inlet and outlet hollow shaft and grinding head, the cylinder is long cylinder, the cylinder is equipped with grinding body, the cylinder is made of steel plate, the liner and the cylinder are fixed, the grinding body is generally steel Made of balls, and according to different diameter and a certain proportion into the tube, grinding body can also be used steel section. Ball mill is widely used in industrial sectors such as mining, cement, chemical industry and electric power. The main working mechanism is the cylinder with grinding medium, which crushes the material by the impact of the medium during the rotation of the cylinder.

Use and scope of use

This series of ball mill wet plaid ball mill for mineral processing, chemical, cement, construction and other industrial sectors wet grinding at all levels of hardness of the ore and materials used.

The working principle of ball mill

Ball mill is mainly composed of cylindrical cylinder, end cap, bearing and transmission large ring gear and other components, the cylinder into the diameter of 25-150mm steel ball or steel bar, known as the grinding medium, the loading capacity for the entire cylinder There is a relatively large volume of 25% -50%. The ends of the cylinder are end caps, and the end caps are connected with the end flanges of the cylinder by means of screws. The middle part of the end caps has holes, which are called hollow journals and hollow journals are supported on the bearings. A large gear 4 is also fixed on the cylinder. In the drive system, the motor through the coupling, reducer and pinion drive large gear wheels and cylinder, slowly turn. When the cylinder rotation, grinding with the cylinder rose to a certain height, and then was a parabola falling or diarrhea down. As the end cap has a hollow journal, the material from the left side of the hollow journal into the cylinder, and gradually spread to the right to move, when the material from left to right during the move, the rotating cylinder to the ball to a certain Height and fall will be crushed material, and part of the ball in the cylinder into the diarrhea state of the material grinding effect, the entire process is the process of grinding the material.

The working principle of the ball mill, due to the rotation of the cylinder and the grinding of the movement, the material gradually spread to the right, and finally from the right hollow journal overflow discharge, the type of ball mill known as overflow ball mill.

Another kind of ball mill in the right end (discharge end) with a grid plate, the grid board consists of a number of fan-shaped perforated plate composition, fan-shaped plate on the hole width of 7-20mm, generally 7-8mm is appropriate, the material can Through the grate hole into the space between the grid plate and the end cap, and then by the board, the material up to lift, the material stretched through the cone slide through the cone-shaped block to the right to the hollow journal, and then by the hollow journal discharge machine outside.

The third way is to use the wind nesting, wind discharge ball mill. Material from the feed port into the ball mill, with the mill rotation, grinding mill grinding (steel) on the material impact and grinding, the material from the left side of the mill (import) ashamed to move to the right, in the process of moving Material broken, grinding process. In the ball mill outlet end connected with the duct, in the pipeline system in series with the separator, cyclone, dust and fan imports. When the wind power system to drive, the ball mill body is also in low negative pressure operation. When the grinding of the material with the mill into a loose rotation, and with the wind from the outlet into the pipeline system, the coarse particles separated by the separator and then into the ball mill imports, fine powder separated by the separation of gas, gas By the fan into the atmosphere.

When the ball filling rate (the total volume of the ball in the cylinder volume of the volume of the percentage) accounted for 40% -50%, the ball mill at different speeds of rotation, the cylinder of the grinding medium may occur three basic state of motion. In the first case, the speed is too high, the centrifugal force causes the ball to rotate together with the cylinder. The whole ball forms a ring which is in close contact with the inner wall of the cylinder. It is called "working state", which can not reach the impact of the material Grinding effect. In the second case, the speed is too slow and the material and the mill are rotated up to 40 ° -50 ° along the mill (there is also a relative slippage between the layers during the rise), when the grinding and material Body friction is equal to the dynamic friction angle, the friction and material on the decline, known as the "diarrhea state." The material has a grinding effect, but no impact on the material, so that the grinding efficiency is poor. The third case, the mill speed is relatively moderate. Grinding along with the cylinder to a certain height, leaving the circular orbit along the parabolic trajectory is free falling, called "throwing state", along the parabolic trajectory of the ball, the lower part of the cylinder ball or tube Body liner produces impact and grinding, so that the material crushed.

The main parameters of the ball mill
  •  1. ball mill productivity. There are many factors that affect the productivity of the mill, such as the type, specification and speed of the mill, the nature of the material being ground, the nature, size, shape and filling rate of the grinding medium, the grading efficiency of the closed- Discharge fineness, and operating conditions. Therefore, it is difficult to determine the productivity of the millile in theory. Half of the time is determined by specific experiments and simulation methods. The results are similar and the actual data are checked. Therefore, there are no examples of productivity measures in the textbooks and design manuals that list the range of productivity in the mill technical performance tables in the various mill selection examples.
  •  2. mill speed. Mill of the simplified working speed is generally 30-14r / min, simplified diameter of the main high speed, and vice versa is high. The ratio of the working speed of the mill to its critical speed is called the rate of change, which is generally 76% -88%.
  • 3. The filling rate and loading of medium in the mill. When the mill is running, the percentage of the area occupied by the medium in the simplified section and the cross-sectional area is called the filling rate of the mill. Through the calculation, we can get different types of mill at different speeds when the filling rate. In actual work, the filling rate of wet-type lattice ball mill is generally 40% -50%, overflow ball mill or rod mill filling rate is generally 35% -40%, dry-type lattice mill and tube mill Filling efficiency is generally 25% -35%.After the filling rate of the mill is known, the amount of media loading can be calculated from the effective volume of the mill and the loose density of the medium. In the mill selection example in the mill technical performance table has been listed in different mill media loading. In the self-grinding machine, generally do not install any medium, but in order to improve the grinding efficiency, often add a small amount of steel ball, the ball is about 80% of the effective volume of self-grinding machine.
  • 4. Mill power. Types and specifications of the mill are actually equipped by the factory equipped with the appropriate power of the motor. The power consumption of the motor itself is about 10%, the mechanical friction loss power consumption is about 10% -15%, and the swimming power used to make the grinding medium and material movement to produce crushing and grinding is about 75%.
Installation and adjustment of ball mill

1, the installation of the basic requirements

  • (1) the ball mill should be installed on a solid reinforced concrete foundation;
  • (2) Ball mill cylinder should be installed with the ground after a sufficient height to facilitate the replacement of the cylinder liner and grinding body, and the strong lining of the bolt.
  • (3) The factory for the basis of the map, only the center of the machine components and the centerline of the center line bolts center line, anchor bolts with the machine supply, the basis of the user only for the basis of the design reference, can not be used for construction plans.

2, the general requirements of the installation

  • (1) All parts should be removed before the installation of rust, dust and dirt, and check the machine surface is damaged in the transport process, if damaged should be trimmed.
  • (2) on the fixed connection should be smear thick grease, non-fixed connection smear thin oil, friction surface plus lubricating oil.
  • (3) the assembly should be to protect the friction surface, not with a clean cotton yarn and dirty grease friction surface.