After almost a decade cooperation with veteran experts on vertical mill manufacturing and scientific research institutes both in home and abroad, the GRM series vertical mills dedicated to be developed and produced by Xinxiang Great Wall Machinery Co., Ltd, have the characteristics of reliable performance, compact structure, convenient maintenance and outstanding energy saving etc. Here are two more important advantages of Great Wall vertical mill.

Wear protection

The grinding plant, which is carefully maintained by the owner, provided high availability and trouble-free operation. None of the wear protection plates in the mill housing and in the grit cone of the separator have yet needed replacing. Only the ceramic castable in the upper housing section of the separator was replaced by wear-resistant steel plates soon after the commissioning. Once a year, after approx. 3500 operating hours and production of 300,000t of ground blast furnace slag, the surfaces of the grinding elements are refurbished by build-up welding during a planned maintenance stoppage. The specific wear of grinding track and roller tyres, taken together, is 7.3g/t.

For long service life of the grinding tools not only the appropriate wear lining is important. The iron extraction system in the external material circuit is an extremely important feature of the Great Wall vertical roller mill for slag grinding.

Iron extraction system

It is a well-known fact that iron particles in the granulated blast furnace slag are the main cause of wear in the mill. Therefore it is extremely important to remove the maximum possible amount of this iron. The external material circuit is very well suited for this purpose, because it handles a large quantity of material, some of which is already partly ground.

The material passing through the nozzle ring falls onto a discharge ring rotating with the grinding table. This material then passes via a discharge chute into the bucket elevator.

The material discharged by the bucket elevator is fed to a vibrating trough, to ensure a uniform feed rate to a magnetic drum separator. The aeration of this magnetic drum separator is so designed that practically pure iron with no granulated slag is removed from the stream of material. After the magnetic drum, the recirculated material finally returns to the grinding table. The incoming granulated blast furnace slag has an iron content of 0.28%, corresponding to an iron quantity of 210kg/h.

The recirculating material in the bucket elevator has an iron content of 0.7%. The magnetic drum separator removes around 170kg of iron per hour in permanent operation. The iron contents found in the roller mill and in the finish product impressively illustrate the efficiency of the external material circuit for concentrating the iron and facilitating its removal. Such efficient extraction of iron in the grinding process has a very positive effect on wear in the mill.

In the world, many granulated blast furnace slag grinding plants are already in operation, but the number of granulated blast furnace slag grinding plants is still low. Customers from all over the world who are now interested in slag grinding are invited to send their inquiries to the Great Wall Machinery. Any of your inquiries will get prompt attention.