Re-use of colliery spoils in construction materials using Fluidized Bed Combustion

Abstract This article describes a plan to upgrade colliery spoils to construction materials. The plan is based on the idea that the mineral composition of which colliery spoils are made of are similar to the composition of construction materials. However, colliery spoils also contain carbon and sulfides whilst construction materials mostly do not. By thermal treatment, i.e. burning out the carbon and oxidation of sulfides, the mineral part can be upgraded into a form, suitable for production of construction materials. An optimized Fluidized Bed Combustion (FBC) technology in combination with treatment of coarser particles in a shaft-furnace, is regarded the most suitable method for this purpose. An integrated processing facility based on proven technologies will be able to upgrade colliery spoils into (1) basic minerals to be used for the production of construction materials (a high valued re-use), simultaneously recovering the remaining energy-content, i. e. (2) electricity and (3) heat. The facility itself can very likely be a basis or crystallization point for innovative building material industry, thus causing an economic stimulus for the region. Furthermore, the removal of colliery spoil deposits will prevent groundwater contamination caused by percolate which may contain sulphuric acid resulting from the oxidation of sulfides. A feasibility check for this project has been carried out for FBC capacities up to 200 MW-fuel, aimed at the removal of an uncovered colliery spoil deposit of about 30 million tonnes in Limburg, the southernmost province of The Netherlands. Production of ceramic limestone as an end-product was found to be a very interesting option.