Coal waste handling, pollution impacts and utilization Dr. Tanveer Iqbal Associate Professor, Chemical, Polymer & Composite Materials Engineering Department, University of Engineering & Technology, KSK Campus, Lahore

Introduction In the extraction of the valuable coal products, typically the production of 1 tonne of hard coal generates 0.4 tonne of extractive ‘waste material’, comprising waste rock including lost coal, and washery rejects and tailings, both containing economically recoverable coal In coal mining and utilization operations, the amount of fine-grained waste containing potentially recoverable coal, coke, coke breeze, etc., despite being significant in quantity, is currently not being visibly reduced.

Fine-grain fuel sources coal slurries (i.e. suspensions of coal flotation tailings or other types of coal fines in water), including sediments; dust arising from brown coal waste; petroleum coke breeze from gasification processes of residues from crude oil processing; fine coal residue from fluidized bed gasification of solid fuels; coke breeze from decarburization of fly ash; coke dust waste from production and processing of carbon and graphite products.

Classification of Mining Wastes Extraction wastes Overburden or coal spoil (CS) Rocks and minerals generated from the mining and preparation plants resulting from opening up the main mineral deposit Composed mainly of cap and interlayer rocks. Represent an average of about 20% of the total mass of waste Tailings finely sized rock and mineral material extracted along with the coal and separated in the beneficiation processes (e.g. sorting, crushing, washing, flotation) their share in the total mass of waste is on an average ~80% Secondary processing wastes the remnants of the main processing treatment, generated in the production processes of commercial products

Potential uses of recoverable materials For recovery of coal, as low-energy material (possibly in slurry form) for combustion in power plants; Manufacture of construction products and refractories; As a filling and sealing material in various types of engineering works; In agricultural applications as fertilizer or substrate; Hydro construction and engineering (e.g. building river dams and embankments of settlers and to strengthen the shipping channels); Marine engineering (e.g. the construction of embankments, coastal protection and of wharves); Road engineering (e.g for building road and railway embankments).

Coal spoil

Coal tailings The hard coal beneficiation process in mechanical preparation plants generates coarse, small or fines rejects and coal tailings slurries. The tailings are the finest grain size, with the majority below ~0.25 mm, whereby material sized below 0.035 mm makes up to 60% share in the slurry composition. Depending on the quality parameters (ash and sulphur content, calorific value, etc.), such slurries can be transferred as an ingredient to energy mixtures, or are dumped in earth settlers of individual mines Commonly used in the manufacture of construction products for the building industry

Energy generation from coal slurries Qualitative assessment of fine-grain materials as a source of heat energy. Technologies for beneficiation of fine-grain materials as a fuel source for energy processes.

Coal Recovery: Natural medium dual density process