Decanter for purifying water contg. particulate materials - incorporates scraper which can be lifted clear of deposited mud, facilitating starting after prolonged stoppage

摘要

A decanter, consisting of a decantation tank and a scraper driven axially to circulate decanted mud from the periphery of the tank to the centre where it is discharged, incorporates means of raising or lowering the scraper, pref. independent of its means of rotation, and such that the rate of lifting is considerably greater than that of lowering. Used partic. for the purificn. of water which has been used to wash material extracted from quarries and sand-pits or coal or mineral mines. Process facilitates starting of the scraper after a prolonged stoppage resulting in a thick layer of mud. The scraper can be raised out of the layer, then started up and lowered so that it enters the mud in a very progressive manner until it comes back to its normal operating regime. Decanter may be used when decantation gives rise to the formation of dense muds, e.g. in sugar refining, in the cases when a flocculating agent is made heavy by a flocculant and in the case where a ppte. is formed by crystallisation in a liq. medium other than water.