Description of the technology

SMZ, a.s. Jelšava exploits one of the largest magnesite deposits in Europe. The basic mineral form of the mined raw material is magnesium carbonate – magnesite. In the deposit of Dúbravský masív it is found in an isomorphic mixture with dolomite and siderite.

Over approximately the last 20 years, the vast majority of raw material has been mined from underneath the earth by means of the overhead stoping method with inter-block pillars with backfilling of the mined areas. This method of mining, due to the elimination of large scale free spaces, increases the safety of the mining procedure; it enables selective separation of mined raw material and, based on defined quality criteria, it also prevents generation of dolomite waste rock piles. On the contrary, 50 % of the back-filling material comes from former waste rock piles originating from the excavation processes performed in the past.

Sketch of the block developed by the overhead stoping method with inter-block pillars:

As for hauling equipment, we use electro-hydraulic drills, bucket haulers, and front scoop loaders. Backfilling is mainly provided by means of wheeled haulers complemented with rail transport.

As for hauling equipment, we use electro-hydraulic drills, bucket haulers, and front scoop loaders. Backfilling is mainly provided by means of wheeled haulers complemented with rail transport.

For the purpose of magnesite concentrates heat treatment, there are 3 rotary kilns available in the company.

5 shaft furnaces plus using the processing line at the Bočiar site (near Košice) including calcinator and shaft furnace producing clinker made of pressed flyash

Clinkers produced in ovens are subsequently processed by crushing, classification based on grain size and magnetic separation. Clinkers obtained in this way are either processed into special purpose basic refractory materials or used for the production of magnesite bricks with a wide range of applications.