| 摘要 |
PURPOSE:To prepare a quick-acting soil conditioner economically, by curing a mixt. of dried slaked lime and gypsum-contg. sludge obtained by adding a specified amt. of quick lime to a gypsum-contg. sludge prepd. by neutralizing waste sulfuric acid with lime, etc., followed by dehydration. CONSTITUTION:Waste sulfuric acid generated in a pickling process of metallic material and containing hydrochloric acid, nitric acid, etc. is neutralized with milk of lime or by-product lime to cause precipitation of gypsum, etc. The precipitate is subjected to primary dehydration to produce hydrous gypsum-contg. sludge and the sludge is made to undergo dehydration reaction. The quick lime is mixed into it in such am amt. that lime, may be totally hydrated and final dried mixt. may have a gypsum content of 5-40%, for drying by heat of hydration and dehydration reaction of lime to obtain dried mixt. or slaked lime and gypsum-contg. sludge. The mixt. is crushed into powder or quick lime is mixed into it in an amt. to make a quick lime content of 80% or lower, followed by crushing, to obtain the titled soil conditioner. |
