Effective utilization of mine overburden soil in producing aggregates by pelletization and sintering

Abstract

The mine overburden generated during mining operations remains largely unused. Though existing studies aimed at using mining waste in coarse aggregate manufacture, limited studies have emphasized the parametric investigation of the manufacturing process. This study focuses on the total volume utilization of the mine overburden soil into a value-added product for use in construction. The study used three types of mine overburden soil samples from a nearby lignite mine: red clay, ball clay and alluvial clay. The study included determining physical, chemical, mineralogical and geotechnical properties. The mine overburden was free of toxic minerals and suited to manufacture coarse aggregate using pelletization and sinter hardening. The parameters influencing aggregate manufacturing, viz., pelletization angle, speed, and moisture content were studied for each soil type to identify the optimal combination of these factors. As a next step, the sintering temperature was varied between 900 °C and 1300 °C to manufacture aggregate with a bulk density and strength range. The water absorption was about 10% for a strength of 4.8 MPa and a density range between 877 to 1195 kg/m3. SiO2, Al2O3, and other flux-forming compounds highly influenced aggregate properties.