Influence of binder composition on briquetting of coal slacks

Abstract

Coke is the most important raw material been fed into blast furnace influencing the efficiency and quality of the molten iron produced. Coal processing industry generates (20-25% of each tonne mined) large amount of coal slacks which are often considered as wastes. Due to its high moisture content and smaller in particle size (<3mm) it is very difficult to transport, handle and utilise; therefore these coal slacks are generally discarded. Coal slacks are potential energy resources, which can be treated and used for various applications. One avenue for it use is to pelletize or briquette it. Various briquetting techniques have been adopted in past few decades; however, the main issues upfront in commercializing this technique are significant binder cost, low strength and effluent being released. This study majorly concentrates on utilising commonly available organic and inorganic binders by varying their percentage compositions along with biomass. Henceforth, optimisation of process parameters for this process is to be economically feasible. Briquettes were being made by mechanical pressing of homogeneously mixed coal slacks, biomass, binder and moisture. Briquettes were then pyrolysed in an inert environment to remove/reduce the volatile content in coal slacks and biomass, improve binding properties, eventually increase the strength and fixed carbon content in it. Characterization of the pyrolysed briquettes were benched against conventional coke. Mechanical properties such as compressive strength, drop strength, shatter index and tumbling index were carried out to realise the suitability of the briquettes. Proximate, ultimate analysis and gross calorific value of the briquettes were carried out. Efficient and economically feasible briquetting process of coal slacks with biomass for industrial purposes would be obtained thus, providing an avenue for the utilization of these waste materials.