Abstract: A substance in a particulate form, e.g. a polyacrylamide flocculant powder, is rapidly dissolved in a liquid, e.g. water by feeding the powder down a circular bore in a casing while the water is fed tangentially and swirled in two chambers in the casing and around the circular bore to emerge in the bore, as oppositely swirling, inwardly converging streams in the path of the powder. The diverging portion of the first stream intersects the converging portion of the second stream, which goes out of the bore with the powder dissolved therein.

Abstract: A method and apparatus for beneficiating crushed raw coal comprising: cleaning the crushed coal in bulk in cyclone separators using only water as a cleaning medium and obtaining a product of wet clean coal and wet reject material and also a stream of effluent; drying said wet clean coal and wet reject material by agglomerating after the addition of a small amount of oil and then centrifuging to obtain a product of clean dry coal and solid reject material and also a stream of effluent; treating the effluent stream from the cleaning step and the effluent stream from the drying step by means of flocculation to recover a product of coal and reject sludge which is returned to pass through the drying step again; and thus obtain clean water which is recycled and applied to the input of the cyclones in the cleaning step.