Coal Recovery from Processing Waste and Coal Combustion Products

Waste from the extractive industry, which includes processing waste, constitutes a vast majority of the industrial waste streams generated in economies where the energy mix is based on coal. Although the efficiency of coal processing is increasing the amount of coal deposited in abandoned slurry ponds is significant. Coal waste storage negatively impacts the environment and due to the high carbon content, this waste cannot be used directly for construction purposes. This also refers to the high carbon content of bottom slags from brown coal boilers. In this chapter, a modern mobile technology of coal recovery from hard coal slurry ponds and an idea of carbon recovery from lignite bottom slag is described. For the first case, the basic idea is to recover combustible matter from the waste coal slurry deposits and create solid fuel and mineral fraction (waste) that can be used for construction purposes. This allows reclaiming post-industrial areas to fit for other purposes, for instance, forestation, commercial or others. The coal recovery process in the COBANT mobile installation is carried out using gravity separation methods classifying and concentrating hydrocyclones. Before the slurry is introduced into the process the slurry is homogenized in a mixing tank to achieve desirable solid concentration and pumped into the circuit of the installation. Dewatering is carried out in dewatering screens and two products are obtained: coal concentrate and mineral fraction. The process is monitored at every stage and is fully automated. In the second approach where brown coal bottom slags are processed, the resulting product from the process will be either a solid fuel or a semi-product for the production of sorbent (activated carbon). In this chapter initial results of the processing technology and results of semi-product carbonation and activation are presented. The aforementioned methods allow to creation of two streams of products that can be used in the energy and construction industry under the circular economy approach.