Produced in hard coal-fired power plants, the brand products of BauMineral are a direct result of state-of-the-art power plant technology geared towards minimizing environmental impact. Hard coal is ground to fine dust and, together with preheated air, injected into the combustion chamber of the boiler via blowpipes. Most of the mineral components of the coal which are not combustible at more than 1200°C melt during this process.
They are then transported in the flow of flue gas and solidify as ash particles on cooling, generally into a spherical particle shape. Prior to entering the flue they are filtered out of the flue gases as hard coal fly ash via electrostatic precipitators. Their chemical-mineralogical properties are consistent with those of natural pozzolans which were used as binding agents in ancient times.
In the case of boilers heated by dry firing, the coarser ash particles fall to the bottom of the combustion chamber and are collected as bottom ash in a water-filled hopper at the boiler end. In the case of slag-tap boilers, the liquefied, incombustible components at temperatures of 1500°C are extracted and shock-cooled in the water quench. The material then crystallizes into glassy pellets thus becoming boiler slag.
All products of BauMineral are subject to continuous internal production checks. Chemical tests are mostly conducted in the power plant laboratories, and the physical tests are conducted in the building material laboratory of BauMineral. In addition, most products are subjected to external monitoring by recognized material test centres, institutes and engineering companies.