Grinding of minerals are carried out in the mills. There are different types of the grinding media used in grinding.
According to the geometric shape of grinding media there are:
- The balls of different diameters;
- Short cylinders — steel circle cut into the size;
- Steel bars (round billet);
- Truncated cones (cylpebs, ellipsoids).
The material used for the production of the grinding media can be divided into three main groups:
- Steel grinding media — used carbon steel as a raw material for the production, which doped with various chemical elements to impart grinding medias properties as hardness and strength.
- Cast iron grinding media — for the production this type of the grinding media used cast iron as «gray» and «white.»
- The ceramic grinding media — this type of the grinding media, as the name suggests, is made of ceramic and used mainly in small-sized mills (about 50 liters) in the chemical and food industries.
According to the production method, grinding media (except for the rods of short cylinders) are divided into:
Today, in industry for crushing the material mainly used the grinding media, which have a geometrical shape of a ball or a truncated cone (hereinafter — cylpebs). Consider in more detail each of them.
Grinding balls. This type of the grinding media made of steel and cast iron. Manufacturing methods — helical rolling of round billet, molding, stamping. Recently, manufacturers of stamped balls losing their relevance in the market, because this method is quite energy intensive, which leads to higher costs of the finished products. The molding is a second method by the cost of production the finished products. Basically, a ball poured of cast iron. This type of production of grinding balls is expensive also. In addition to energy consumption, a large percentage of «waste» in production affect to the cost of the finished product. Today, the most competitive technology of production the steel grinding balls is a helical rolling of round billet. For sufficiently small energy consumption at the production, the quantity of «waste» less than 1-1.5% by the total volume of the raw material.
Cylpebs. This type of grinding media are manufactured by casting and rolling method. Rolled cylpebs is not common in the market of grinding media. This is caused by high production costs and low milling quality, which gives this type of grinding media. In most cases, cylpebs produced from «gray» and «white» iron by casting method. It should be noted that this type of grinding media has a number of disadvantages, depending of the cast iron type used in production of cylpebs. For example cylpebs of «gray» cast iron is soft enough and as result an increase in specific consumption of grinding media in the grinding process. Cylpebs production of «white» cast iron is very expensive and this caused by the high cost of the chemical elements that are part of the «white» cast iron.
So what is better, a ball or a cylpebs? As shown recent researches, the ball charged to the ball mill has a large contact area, providing better quality of grinding in comparison with the grinding cylpebs. In confirmation of this, currently, almost all the companies partially or completely refused of using cylpebs during grinding.
In our next articles, specialists of Energosteel company will hold for you a more detailed comparative analysis of the most common grinding media, marking the advantages and disadvantages of each.