Abstract: This invention is concerned with production and use of high surface area particulate matter by calcining a charge of clay mineral, feldspar, zeolite, coal ash, fly ash, pozzolan or volcanic ash for a time to develop fractures which increase the surface area of the particles. Vacuum calcining decreases the calcining time. The calcined matter desirably has an analysis including: calcium oxide, about 20-40 weight %; aluminum oxide, about 15-35 weight %; and silicon oxide, about 20-40 weight %.The calcined particulate matter can be used in the treatment of impure aqueous materials; the matter is denser than water and sludge settles rapidly and completely. The calcined matter interacts with heavy metal ions to form tightly bound sludge that is nonhazardous for landfill disposal. The calcined matter can be combined with conventual coagulants, flocculants, filter aids, or activated carbon to obtain a multipurpose treating agent.

Abstract: This invention is concerned with production and use of high surface area particulate matter by calcining a charge of clay mineral, feldspar, zeolite, coal ash, fly ash, pozzolan or volcanic ash for a time to develop fractures which increase the surface area of the particles. Vacuum calcining decreases the calcining time. The calcined matter desirably has an analysis including: calcium oxide, about 20-40 weight %; aluminum oxide, about 15-35 weight %; and silicon oxide, about 20-40 weight %.The calcined particulate matter can be used in the treatment of impure aqueous materials; the matter is denser than water and sludge settles rapidly and completely. The calcined matter interacts with heavy metal ions to form tightly bound sludge that is nonhazardous for landfill disposal. The calcined matter can be combined with conventual coagulants, flocculants, filter aids, or activated carbon to obtain a multipurpose treating agent.

Abstract: This invention is directed to the oxidation of ferrous chloride in liquid aqueous solution, such as, waste HCl pickle liquor, to a solution containing ferric chloride, by intimately intermingling said ferrous chloride solution with free oxgyen in the presence of a dissolved promoter cation selected from the class consisting of ammonium, chromium, cobalt, copper, manganese, nickel, zinc and mixtures thereof at an elevated temperature between about 120.degree.-500.degree. F. for a time sufficient to obtain a ferric chloride containing solution.The invention is also directed to producing hydrochloric acid from ferric chloride solution in water by heating the liquid solution at a temperature of about 250.degree. -400.degree. F. at subatmospheric pressure, preferably, by means of hot submerged combustion gases, to obtain a hydrogen chloride gas-water vapor mixture and a bottoms aqueous slurry of iron oxide.