PURPOSE: To economize considerably the labor and time required for detaching and attaching of a filter belt by subjecting the filter belt to primary cleaning with fresh water or filtrate kept under high pressure then to secondary cleaning with an aq. acidic or alkaline soln.
CONSTITUTION: An acidic cleaning soln. is used for removing the deposits consisting essentially of inorg. components such as lime and iron-content and hydrochloric acid is used for the acidic soln. An acid soln. of sulfuric acid, nitric acid, etc. is used according to the characteristic of the deposits. An aq. alkaline soln. is used for deposits consisting essentially of org. materials. An aq. alkali hydroxide or ammoniac water or the like is used as the alkali soln. Secondary cleaning may be accomplished continuously at all times in some case but usually the secondary cleaning is accomplished intermittently once a day to prevent clogging or when the filtering efficiency decreases on account of clogging. Tertiary cleaning by fresh water or filtrate is accomplished according to the characteristic of the material to be treated.
SATOU HAJIME
NAGASHI KENICHI
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