Ball mill installation is a must step before it is put into production, which will affect the subsequent use of the ball mill, and even affect the production volume, crushing rate, service life, etc., so the importance of ball mill installation is self-evident.
In addition, the choice of grinding medium is also crucial. In the grinding process, different grinding medium can be used for different materials, models and equipment, which can reduce production costs and improve production efficiency.
Steps to install the ball mill
1. The installation of chassis
There are four chassis should be installed: the front tile base, the rear tile base, the motor chassis and the reducer chassis. During the installation of the chassis, the horizontality and horizontal elevation of the chassis must be checked by a level or level gauge and a steel rule.
When an uneven phenomenon is found, a steel adjustment wedge is applied to the lower part of the chassis to ensure the horizontal.
At the same time, the width of these wedges should be between 50 and 60 mm; the length should be at least ensured to exceed the centerline of the anchor bolts inside the chassis, and the outside should be exposed to a length of 10 to 50 mm; the slope of the wedge should be between 1:10 and 1:20.
After that, the wedge iron should be welded together to avoid movement.
2. The installation of main bearing
The distance between the centerlines of the chassis of the two bearings shall be in accordance with the equipment technical documentation or the relevant design specifications.
If the actual combined size between the motor cylinder and the hollow shaft is inconsistent with the technical documents of the equipment or the relevant design, the construction may be carried out according to the actual size after obtaining the consent of the relevant unit personnel.
The transverse centerlines of the two main bearing chassis must coincide and allow for a combined error of no more than 0.5 mm. The non-horizontal degree of the main bearing chassis is allowed to differ by 0.1 mm/m, and the error of the non-parallelism is 0.5 mm/m, but the ball mill must be ensured to discharge materials.
Before the installation of the spherical surface of the main bearing, it is necessary to carefully check whether there are blisters, pores, cracks and other defects on the babbitt surface and the spherical surface, and there is no possibility of shrinking the shell in the interval between the hollow shaft and the contact surface of the bushing. phenomenon.
Outside the area where the hollow shaft is in contact with the bushing, the area of the shrinking on each side may not exceed 20% of the sum of the areas of the two sides.
3. The installation of cylinder and ring gear
Firstly, before assembling the cylinder and the end cap, check the cylinder to ensure that the ellipse of the cylinder is not larger than 4‰ of the diameter of the cylinder. And meanwhile, the ovality and surface smoothness of the hollow journal should also be checked.
After the end cap and the cylinder bolt hole are aligned with the positioning pin, put a 1/4 number of bolts and tighten by hand, one-third of which are half tightened, and the concentricity is adjusted within 0.25mm, and then tightened.
After the inspection, tighten all the bolts according to the required torque value. Finally, all the flanges should be inserted with a 0.03 mm feeler gauge to make sure there is no gap.
Next, the cylinder and end cap assembly are transferred into the main bearing, but the housing must be adjusted to meet the requirements before the cylinder and end cap assembly are installed in the main bearing.
After assembling, the assembled cylinder should be measured and the total length and the length of the center of the two journals are compared with the center distance of the bearing housing to make sure they match with each other, otherwise, the bearing housing or the position of the main base need to be adjusted.
Use the jack-up device to slowly lower the cylinder assembly into the bearing and avoid bumping the bearing pads.
Then, the large ring gear and the cylinder should be assembled. If the large ring gear is a unitary body, it must be installed on the cylinder and then be mounted on the bearing.
If the large ring gear is a combination of two halves, the usual method is to install the grinding machine revolving body on the main bearing and then install the large ring gear.
4. The installation of liner
The inner surface of the ball mill cylinder is generally equipped with liners of various shapes that are the main wearing parts of the ball mill, and whose cost is about 2%-3% of the price of the whole product.
Thus, the performance and service life of the lining plate are issues that users are very concerned about, for its performance will directly affect the performance of the ball mill.
10 requirements for the liner installation:
- A The gap between back lining of the liner and the end cover of the cylinder shall be filled with the compressive strength grade 43.5MPa cement mortar.
- B The bolts of the fixed end lining shall not be filled by the cement mortar, and it shall be able to rotate or enter.
- C linings are generally directional, must be careful when installing.
- D All circumferential gap arc length can not exceed 310 mm, and the excess area is wedged with steel plate to cut it off.
- E The gap between adjacent liners is not more than 3~9mm.
- F Between the lining plate and the inner surface of the cylinder, the partition should be laid according to the design requirements. If there is no requirement, the compressive strength grade 42.5MPa cement mortar can be filled between the two as full as possible, and the excess part is extruded through the strong lining bolt.
- G When the rubber lining plate is installed, the rolled rubber sheet is opened for 3 to 4 weeks before installation to make it free to stretch; when using the rubber sheet, the long side of the rubber sheet follows the cylinder axis and the short side follows the circumferential direction of the cylinder.
- H Carefully check the geometry of the lining bolt holes and lining bolts, carefully clean the lining bolt holes and the burrs and protrusions on the lining bolts so that the bolts can freely penetrate into the required position.
- I Sets of lining bolts shall be composed of glaring bolts, dustproof washers, flat washers, spring washers and nuts; in order to prevent ash leakage, and do not forget to use the dustproof mat when using.
- J When tightening the lining bolts, use a torque wrench to work. The bolts of different specifications should be tightened according to the corresponding tightening torque requirements.
How to choose grinding medium?
Medium density, hardness, size
The greater the density of the grinding medium is, the shorter the grinding time is. In order to increase the grinding effect, the hardness of the grinding medium must be greater than the hardness of the material to be ground.
According to long-term experience, the Mohs hardness of the medium is preferably greater than the hardness of the material to be ground by more than three grades. In addition, the smaller the size of the grinding medium is, the more the contact points it will be.
The loading amount has a direct influence on the grinding efficiency, and the particle size of the grinding medium determines the loading amount of the grinding medium. It must be ensured that when the grinding medium moves in the disperser, the porosity of the medium is not less than 40%.
For different fineness requirements, it is necessary to adjust the ability of the grinding medium to break and grind. The filling rate is high and the grinding ability is strong. On the contrary, the crushing ability is weak. When super fine grinding, the high filling rate is generally adopted.
The grinding material determines the cost and efficiency of pulverization. Grinding materials can be mainly divided into metal media, rock mineral materials and non-metal materials.
In addition to considering the production cost, it is also necessary to consider whether the materials and medium will cause pollution issues.
Common grinding medium includes steel balls, alumina balls, zirconia balls, and so on.
Shape and size
Grinding medium generally is spherical because other irregularly shaped medium can wear themselves and cause unnecessary contamination. The size of the medium directly affects the grinding efficiency and product fineness.
The larger the diameter is, the larger the product size and the yield are. Conversely, the smaller the particle size is, the smaller the particle size and the the yield are. In actual production, it is generally determined by the feed size and the required product fineness.
Generally speaking, in the continuous grinding process, the size of the grinding medium is distributed regularly. The medium size ratio is directly related to whether the grinding ability can be exerted and how to reduce the wear of the medium.
In the process, it will not always maintain at a fixed medium ratio. So, the method of replenishing large balls is used to restore the grinding of the system. It is difficult for the mill to maintain at a fixed medium ratio for a long time.
In the production process, it is necessary to explore the appropriate ratio according to the type of material and the characteristics of the process, and remove the too small medium in time to reduce the cost.
Abrasion resistance and chemical stability
The wear resistance and chemical stability of the grinding medium are important conditions for measuring the quality of the grinding medium. The non-wearing media needs to be supplemented by the need of abrasion, which not only increases the cost, but more importantly affects the production.
The grinding medium needs to have certain chemical stability in the specific grinding process, and cannot chemically react with the material during grinding, causing pollution to the material.
As common grinding equipment, ball mills are widely used in power, chemical, mining, cement and other processing sectors. At present, there are many kinds of ball mills popular in the market, with various functions and different prices.
Therefore, enterprises often face a dazzling situation when purchasing. Generally, when selecting a ball mill, the company must combine the material properties, abrasive requirements, production environment, energy consumption and other factors through scientifically comparing to select the ball mill that is most suitable for its use requirements.
As a professional manufacturer of ball mill equipment, Fote Heavy Machinery has continuously improved its research and development of ball mills with 40 years of experience.
Its superior performance and efficient production capacity make it the best choice for domestic and foreign users.