3 functions, 8 categories and 10 installation requirements of ball mill linerDate: 2019-07-08 Views:
The inner surface of the ball mill cylinder is generally equipped with various shapes of liner. Liner is the main vulnerable part of ball mill, and its use cost is about 2% ≤ 3% of the product price. The performance and service life of liner are of great concern to users. The performance of the liner will directly affect the performance of the ball mill. This paper introduces 3 functions, 8 categories and 10 installation requirements of the liner of the ball mill.
Function of liner
The materials for making liner are metal materials (manganese steel, chromium steel, etc.) and rubber. At present, there are many metal material liners in China, and the application of rubber liner in mines is also very many. The main functions of the liner are as follows:
1. Protect the stiffness of the cylinder and the stiffness of the reinforced cylinder
The cylinder body is an important part of a ball mill, and the price is relatively high; after the lining plate is arranged in the cylinder body, the cylinder body is not directly subjected to the impact and the grinding of the grinding medium and the ground material, so that the cylinder body is protected, and the service life of the cylinder body and the whole device is prolonged. The lining plate and the cylinder body are closely combined together, and also play the role of enhancing the rigidity of the cylinder body.
2. Energy transfer
During the rotation of the cylinder, the ball is lifted to a certain height by means of the special shape and the friction force of the surface of the lining plate, so that a certain position energy and a throwing kinetic energy are given, so that they can generate the "arc-parabola" movement track, the impact and the grinding material in accordance with the requirements of the grinding process.
3. Automatic grading sphere
The automatic grading lining plate, such as angular helical lining plate and conical grading lining plate, can make the grinding bodies of different gradation in the cylinder, along the axial direction of the mill, reasonably classify according to the change of the grinding particle size, so that the grinding bodies of different diameters play a maximum function in the process of crushing the corresponding particle size material. In other words, the automatic grading lining plate can collect the larger steel balls in the same grinding bin at the feeding end of the bin, so as to crush the larger material block, and at the same time, the smaller steel balls can be gathered at the discharging end of the bin to crush the smaller material block.
Classification of the lining plate
The shape of the lining plate of the ball mill is divided into nine shapes according to different requirements, which are wedge-shaped, wave-shaped, flat-convex, flat, stepped, long-strip, rudder-shaped, K-shaped rubber lining plate and B-shaped rubber lining plate (as shown in the figure below).
The rising height of the grinding body depends on the static friction coefficient between the grinding body and the tree board.
The application of strip liner in the first silo can make the grinding body rise higher and has greater impact energy.
The corrugated rib liner is similar to the bead liner.
Waveform liner is suitable for baseball mill.
Ladder liner is suitable for crushing silo and is widely used. It has the following three advantages:
a)The lifting height of the same spherical layer shall be uniform.
B) The surface of the plate is evenly worn.
c) the holding capacity of the lining plate acts on the grinding body of the other layers, the sliding abrasion between the lining plate and the outermost grinding body is reduced, and the sliding and the abrasion between the grinding bodies at different levels are also prevented.
The semi-spherical lining plate is suitable for crushing the cabin.
Waveform liner, suitable for fine grinding silo laying of bolted liner, its wave peak and constraints are very small.
8 grading liner, can make steel ball automatic classification.
The shape of cylinder liner has a great influence on the work of ball mill. When dealing with coarse material, fluctuating liner (such as waveform, convex shape, lap shape and stage shape, etc.) should be used on the cylinder of ball mill. This kind of shape liner has the ability to raise the grinding medium to a higher height, so as to enhance the impact ability of the medium and improve the production capacity of the ball mill. It is commonly used in the first stage of grinding.
Fine grinding (often refers to the second stage of grinding) is mainly based on grinding and peeling. The smooth liner is easy to roll the steel ball, and the grinding and peeling effect is strong, so the smooth liner is often used in the cylinder of the fine grinding ball mill
Liner installation requirements
The back end liner and the end cover of the cylinder should be filled with 43.5MPa cement mortar of compressive strength grade.
The bolt of the fixed end lining plate shall not cause the cement mortar to be filled and allowed to rotate or enter and exit.
The lining board is generally directional, and must be paid attention during installation. Do not put it back.
The arc length of all circular crevice should not exceed 310 mm, and the arc length should be wedged with steel plate to separate it.
The clearance of adjacent liner is not more than 3 ≤ 9 mm.
The spacer should be laid between the liner and the inner surface of the cylinder according to the design requirements. If there is no requirement, the compressive strength grade 42.5MPa cement mortar can be filled between the two, and the excess part should be extruded through the solid liner bolt, and the liner bolt can be fastened again after the cement mortar is solidified.
When the liner with rubber gasket is installed, the rolled rubber plate will be opened 3 weeks before installation so that it can stretch freely; when the rubber board is used, the long side of the rubber plate follows the axial direction of the cylinder and the short side follows the circumferential direction of the cylinder.
The geometric shape of the lining plate bolt hole and the lining plate bolt shall be carefully checked, and the flying edge, burrs and protrusion on the liner bolt hole and the liner plate bolt shall be carefully cleaned to make the bolt freely penetrate into the required position.
The complete set of lining plate bolts shall be composed of a mesh bolt, a dust-proof washer, a flat washer, a spring washer and a nut; in order to prevent the ash from leaking, it is not forgotten to use the dust-proof pad when in use.
Torque wrenches should be used to fasten liner bolts, and different specifications of liner bolts should be tightened according to the corresponding tightening torque requirements.