Floating material sepn. from grinding waste waters - by adding inorganic acid soln. contg. polyvalent cation and or polyelectrolyte, adjusting pH and flocculating

摘要

Grinding-, esp. frictional grinding waste waters are worked up (a) mixing with 0.01-10 (0.1-1)% inorganic acid soln. contg. 5 g/l to saturation, esp. 10.-15 g/l, di- or polyvalent cations and/or 0.1-5 g/l cation-active polyelectrolytes. (b) A neutralising agent is added to set pH 6-9 (6.5-8.5). (c) A flocculant is charged until flocculant concn. in waste water reaches 0.5-20 (1-5)mg/l. While adding the chemicals, the mixt. is stirred. After flocculant addn., stirring velocity is reduced for 10 secs. to 5 min., so that the sludge can be sepd. from water by settling. Floating materials are flocculated, to form a clear run and a sludge which settles and can be separated by filtration. The acid in (a) is esp. HC1. The cations can be Fe, Mg and esp. Al and Ca. In (b) pH canbe set with milk of lime. While adding the chemicals, the waste water is stirred esp. at 200 r.p.m. stirring is then continued at 60 r.p.m. for 1-2 min.