The disadvantage of these mills is the low service life of the grinding elements (rolls and table armor) due to their uneven wear: maximum wear of the bandage occurs at about 1/3 of its forming from a larger diameter, the edges practically do not wear out, the armor has a similar wear character, that is, the armor section opposite to the maximum bandage wear has the maximal wear, and opposite to the bandage edges the armor wear is slight. Since the slightly worn edges of the roll bandage do not allow lowering it as it is worn, the gap between the roll and the table increases and the pressing of fuel by the rolls worsens, which leads to a decrease in the grinding performance of the mill. When performance decreases below the permissible value, the grinding elements have to be replaced.
The established overhaul resource of a roller mill is 23-25 thousand hours. "Tekhnoinkom" has increased interest in the work terms of table armor and grinding rolls.
The approximate service life of St15GL bandages is 12 thousand hours. The wear of bandages is allowed for a value of not more than 40%. The approximate service life of the table armor is 16-20 thousand hours. Material - St.300Х13Г3С2М
Planned repairs include:
Welding bandages. If it is impossible to weld the bandage ¬- when the worn out is heated by more than 40% of the bandage, there is a high probability that the bandage will fail (may burst), the bandage is replaced with a new one. The wear surfaces of the grinding table and the roll consist of segments that are easy to replace when worn. Replaceable roll segments can also be rotated to use both their sides (the outer part of the rolls is subject to the greatest wear), which ensures a high use factor. For mills that grind highly abrasive materials, such as slag, it is advisable hard-facing welding to ensure high availability of the grinding unit, optimize the grinding process and reduce the cost of replacing worn parts. Hard-facing is an economical alternative to replacing wearing parts and is excellent for high-chrome cast iron or high-strength steel used in the mill. The segmental design of wear surfaces allows multiple hard-facing over the entire life cycle.
Wear-resistant coating allows to increase the life of the separator by at least 2 times.