IMPROVED SCREEN-BOWL CENTRIFUGE RECOVERY USING POLYMER INJECTION TECHNOLOGY

摘要

Screen-bowl centrifuges are currently the most popular process for dewatering fine particles in the U.S. coal industry. Although these units typically provide acceptable product moistures, they often suffer from low recoveries of fine solids. Past attempts to improve solids recovery by adding conventional flocculants directly to the feed stream have been shown to have little, if any, positive benefit. However, recent field studies indicate that solids recovery can be significantly improved using a modified feed tube to inject custom designed polymer directly into the low-solids clarified pool within the rotating bowl section. The solid-solid separation processes employed by modern coal preparation plants require large amounts of process water. After cleaning, the unwanted water must be removed from the surfaces of the particles using mechanical dewatering equipment. Coarse particles can be readily dewatered using simple screening systems, while finer particles require centrifugal dryers, screen-bowl centrifuges or disc filters for effective moisture removal. The most popular unit for dewatering fine coal in the U.S. is the screen-bowl centrifuge.