IMPROVEMENTS IN AND RELATING TO THE CONVERSION OF LIQUID HAZARDOUS WASTES TO SOLID FORM

摘要

1485625 Treating waste C L CHAPPELL 30 Aug 1974 [1 June 1973] 26201/73 Heading C1H A process for the conversion of a hazardous waste into a substantially impermeable solid comprises adding cement powder of substantial calcium content, and a powder consisting of aluminium silicate and/or an aluminosilicate, to the waste dissolved or dispersed in water, thereby forming a flowable slurry containing the waste, and allowing the slurry to set into a rigid rock-like mass. The calcium-containing cement may be Portland cement, while the aluminosilicate may be vermiculite or, preferably, fly ash from the combustion of pulverized coal. If desired, an oxide or hydroxide of aluminium or iron may also be present in the slurry. Where fly ash is employed, the presence of an alkali metal silicate ensures that the slurry sets more quickly. The hazardous waste may contain Al, B, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Sn, Zn, As, Sb, Ba, Co, Ga, Hf, Hg, Mo, Nb, Sr, Ta, Th, Ti, V, Zr, Se or Ag or a compound of any of these elements. It may contain anions such as fluoride, sulphate, phosphate, nitrate, nitrite, sulphite, cyanide, sulphide, thiocyanate, thiosulphate, ferricyanide or ferrocyanide and it may contain an acid, alkali, protein, carbohydrate, Prussian or Turnbulls blue, detergent, mineral oil, fat, tar or grease. Hazardous wastes mentioned include mining and metallurgy wastes (e.g. mine tailings and drosses), paint wastes, sulphide dye liquors, inorganic catalysts, electrical wastes (e.g. printed circuit wastes), printing and duplicating wastes, electroplating and metal finishing wastes, explosive industry wastes, latex wastes, battery production wastes, textile wastes, petrochemical industry wastes (including leaded petrol sludges and ash obtained by burning fuel oil), pulp and paper industry wastes, leather industry wastes, asbestos waste, scrubbing liquors from incinerators and gas cleaning equipment, silts and dredgings from waterways, spent oxides from gas purification, cement and lime industry wastes (including dust from electrostatic precipitators), sewage sludge, ash from burning domestic refuse and sewage sludge, and sulphide wastes (e.g. Ca or Na sulphide).