Selection of grinding equipment

Grinding equipment is mainly selected according to the production capacity of the grinding workshop, the nature of the ore, the size of the ore and product, the conditions and performance of the grinding equipment. At present, the grinding equipment commonly used in the factory is selected, which is a conventional rod mill, a lattice ball mill and an overflow ball mill; the self-grinding wet and dry self-grinding machine . The gravel mill belongs to the self-grinding category.

The main advantage of the rod mill is that it has a certain selective grinding effect, the product has a uniform particle size and less pulverized particles. Compared with the ball mill, it can accept a larger ore size (the upper limit of the ore size is generally 15~25mm); For rough grinding, the upper limit of product size is generally 1~3mm; under rough grinding conditions, the production capacity is higher. Its main disadvantages are: the need to stop and add rods, the operating rate is lower than the ball mill; the output is lower during fine grinding. Rod mills are generally used for the first stage of grinding in two-stage (or three-stage) grinding, and can also be used for grinding operations of brittle ores such as tungsten and tin .

The main advantage of the lattice ball mill is that there is a grid plate at the discharge end, the discharge liquid surface is low, the product can be discharged in time, the pulverization phenomenon is lighter; the treatment capacity is higher, which is 10% higher than the overflow ball mill of the same specification~ 15%. The main disadvantages are: large ball loading, large shaft power, complicated equipment construction, large maintenance and heavy equipment. The upper limit of the particle size of the lattice ball mill is generally 0.2~0.3mm, which is often used in the first stage of grinding.

The main advantage of the overflow ball mill is that the structure is simple, the maintenance amount is small, the product size is fine (generally less than 0.2mm); the main disadvantage is that the processing capacity is smaller than that of the grid ball mill of the same specification, and it is easy to produce excessive pulverization. The overflow ball mill is generally used for the second and third sections (or medium mine regrind) grinding operations, and can also be used for the first stage of grinding operations. When the mill diameter is greater than 3.6m, the first section of the mine mostly uses an overflow ball mill. Because such a large-size mill is generally closed with a hydrocyclone (with no corresponding standard spiral classifier), the overflow ball mill can reduce the coarse grain content in the mill discharge, thereby reducing the pulp and The wear of the cyclone.

The main advantage of the self-grinding machine is that the ore size is large (the maximum feeding size is generally 200~350mm), so it can replace the medium and fine crushing and coarse grinding operations, reduce the production link and dust pollution (referring to wet self-grinding), simplifying Drag composition, accounting for reducing hair dressing plant area; has a certain effect selective comminution, crushing too little; does not consume less consumption of grinding media; mud containing ore more viscous aqueous wet grinding process can be avoided from conventional Broken, sifted and other work blockage problems. The main disadvantages are: in general, the power consumption is higher than that of conventional grinding; the equipment operation rate is slightly lower than that of the ball mill; it is sensitive to the ore size and grindability, the production is easy to fluctuate, and the operation is complicated. Dry self-grinding is generally limited to dry and water-deficient areas or must be used under dry conditions due to dust pollution and wind system wear.

In order to use self-grinding, sufficient experimental research work must be carried out. Includes medium capacity tests and semi-industrial tests (or industrial tests) of ore. Based on the semi-industrial test (or industrial test), the technical and economic comparison with the conventional grinding program is carried out to determine whether the self-grinding and self-grinding process structure is adopted.

The gravel surface is often used for the second stage of grinding in two-stage grinding. The gravel mill can use the block ore sieved from the crushing system as the grinding medium, or the gravel (pebble) naturally formed from the gravel or gravel field discharged from the first section of the grinder gravel as the grinding medium. . The main advantage of pebble mill: no metal media grinding to reduce the consumption of steel; rare metals and non-metallic mineral ore concentrator may reduce the iron contamination of the beneficiation process, improving the sorting effect. The main disadvantage is that the processing capacity is low. Therefore, when the scale of the concentrator is the same, the mill has a larger specification (or a larger number of mills) than the steel medium mill, and the capital investment is also high.