Basic raw materials for cement production in Cemmac a.s. are limestone and marls. In addition, gypsum, silica sand and an iron additive (e.g. demetallized steel slag) are used as corrective additives. Limestone and marls are extracted in a local quarry, from where they are transported by trucks to the primary crushing plant. Corrective additives are delivered by external suppliers.
Raw material storage
The crushed raw material is stored in a circular pre-blending store using continuous Chevron stacking, with a capacity of 22,000 tonnes. From there, the raw material is transported to the raw mill.
Raw material grinding
A mixture of pre-blended material from the circular pre-blending store, corrective limestone and corrective additives is ground in two ball mills with a capacity of 50 t/h each, which are part of a pneumatic grinding system. The finished product, raw meal, is stored in an IBAU interim blending silo with a capacity of 6,000 t. Raw meal is dried in the grinding circuit by means of waste heat from the rotary kiln.
Burning and storage of clinker
Clinker burning takes place in a rotary kiln equipped with a 5-stage cyclone heat exchanger and precalcination. The kiln’s design output is 1,200 tonnes of clinker per day. The main stages of the clinker burning process are the calcination of calcium carbonate and formation of clinker minerals. Basic fuel used in the burning process is finely ground coal. Since 2006, a part of the heat needed for clinker burning has been replaced by alternative fuels. Burnt clinker is cooled down in a state-of-the-art grate cooler and subsequently stored in two concrete silos with a total capacity of 14,000 t.
A mixture of clinker, gypsum and possibly additives (depending on the type of cement) is ground in a two-compartment ball mill, which is part of a grinding system with a closed circuit and a third generation sorter. The resulting product is finely ground cement, which is subsequently stored in cement silos.
Dispatch of cement
Cemmac a.s. delivers the cement to customers in form of a packed or bulk product. Packed cement is dispatched in 25 kg bags stacked on euro-pallets and covered by plastic foil. Bulk cement is dispatched by bulk trucks.
Technological processes are controlled from a central control room using modern computer technology to the highest degree possible. An automatic emission monitoring system is also installed at Cemmac a.s.
The quality parameters of all technological inputs and outputs are monitored by a laboratory equipped to the highest modern standards, using an X-ray fluorescence analyzer and diffractometer.