Waste from the coal extraction process as raw material for the construction industry

Abstract

During mineral mining, huge quantities of waste are produced. This waste is usually placed in the open air, near the deposits, with the environmental consequences this situation implies. The construction industry and its auxiliaries can receive waste and by-products. As these industries handle materials on a large scale they can include an important percentage of waste in their compositions. In the present work the feasibility of utilization by the construction industry of waste originating during the coal extraction process as a raw material was studied. The materials, as received from the mine, were characterized as usual. From analysis of the results it is concluded that the waste can be used without any additives, but subject to a previous milling process in order to reduce the bigger pieces so as to prepare adequate mixtures for the compacting process. In a previous work some waste from the process was analyzed: ashes, mud and sterile material. As the stored quantity of the sterile material is noticeably higher and its characterization shows the possibility of using it to produce dense bodies, only this residue is studied in this work. The “steriles” were ground and mixtures with different particle size distribution were prepared. These powders, with 12% H2O and without other additives, were uniaxially pressed in order to obtain samples that were heat treated at 850°C. The samples obtained had good properties related to color, edges and surface finish. They were characterized by several techniques.