Neutralising waste acids from glass polishing - by setting to alkaline pH with lime, separating solids and neutralising liquids with carbon dioxide

摘要

Waste acids from acid polishing of glassworks are rendered harmless by bringing the aq or pre-treated waste acids to pH >9 with excess CaO quicklime, or lime milk; separating reaction mixt. into solids and liquids and neutralising liquids having pH >9 by introducing CO2 or CO2-contg. gases, sepg. solids obtd. and discharging liquids to a river. Setting to pH >9 is pref. effected by using just sufficient or slight excess of CaO. Whole of reaction mixt. can then be neutralized with CO2 and sepd. to neutral solids and liquid. CO2 may be replaced by acids forming water-soluble, non-toxic Ca salts, e.g. HCl.