Лако-красочные материалы — производство

All undissolved solid material must be removed as completely as possible from the solution. The most economical method is to employ preliminary settling in a thick­ener (g), followed by filtration of the sediment with a rotary vacuum drum filter (h) or a filter press. The filtrate and the supernatant from the thickener are passed through filter presses (i) to remove fines. Owing to the poor filtering properties of the solution, the rotary filter must be operated as a precoat filter. Preliminary separation in the thickener must be assisted by adding chemicals to promote sedimentation. Attempts to carry out the entire clarification process in a single stage using automated filter presses have been reported [2.31].