Coal Fines and Filter-Cake Utilization
Coal fines and filter-cakes are the side product of the most coal preparation plants which are using flotation for separating a regular coal from the rocks. Normally filter cake is a clay-liked substance with high moisture content and coal particles below of less than 1 mm. These fines are typically utilized as a waste. We convert them into a liquid fuel – Coal (Carbon) Water Slurry, CWS.
CWS can be pumped like liquid fuel and atomized into a boiler and/or drying kiln through the special nozzles.
CWS might be used as an additional fuel in boiler or drying kilns replacing a regular (expensive) coal: CWS is simply sprayed into the furnace above the grate though the air nozzle.
When there is an option to install ash removal systems CWS can replace oil, gas (LPG). In this case the project has very short period of returning investments (RoI).
According to achieved results it is determined that combustion of 1 ton CWS from filter cake saves aproximately 1 ton of salable coal.
Thus, combustion of coal-water slurry from cake allows for coal plant to solve two problems at once:
Reduce consumption of salable coal for technological needs, ie, reduce their own costs for the production of coal.
Dispose of unused coal filter cake having an ash content of about 30 … 40% and humidity up to 30%.
Proposed solution could be implemented with most of majority of coal factories.
In addition to filter cake other small coal fractions could be used as a raw material for CWS.
CWS from filter cake could be effectively made in by Hydroshock Wet Milling Machibe (WMM). WMM makes a uniform (homogeneous) suspension (sludge, slurry), which is atomized through a nozzle.
Example of burning of CWS from filter-cake in an drying kiln: