Metallgesellschaft Aktiengesellschaft

Walter Koch

Martin Hirsch

Hans-Werner Schmidt

Yilmaz Yetmen

Karlheinz Rosenthal

Rudolf Heng

Hans Beisswenger

Fred Erich Cappel

Hartmut Pietsch

Dirk Hankel

Ali-Naghi Beyzavi

Bodo Peinemann

Refractory gold ores are roasted at temperatures from 500.degree. to 650.degree. C. in an oxidizing atmosphere in a fluidized bed, which is supplied with a carbonaceous additional fuel. To effect a substantially complete combustion of the additional fuel to form CO.sub.2 and H.sub.2 O, methanol is added as a carbonaceous fuel.

Process for roasting refractory gold ores

The iron content of the TiO.sub.2 -containing precursor is subjected to a direct reduction to effect a metallization of at least 90%. The reduced product is separated into magnetic and nonmagnetic fractions by magnetic separation. To oxidize the metallic iron, the magnetic fraction is subjected to an oxidation in an acid medium with agitation at a pH value below 2, under a pressure of 12 to 24 bars, and at a temperature from 150.degree. to 210.degree. C. with a supply of an oxygen-containing gas that contains at least 90% oxygen. When the suspension has been pressure-relieved, the hematite which has been formed is separated from the TiO.sub.2 concentrate.

Recovering TiO.sub.2 concentrates from TiO.sub.2 -containing substances

A mechanical disintegration is effected in which substantially only the metal sheath of the small batteries is torn apart. The crushed material is roasted at 500.degree. to 1000.degree. C. in a state of motion in an oxidizing atmosphere and the volatilized mercury is recovered from the exhaust gas. The roasted material is separated by sieving and magnetic separation into an iron-containing scrap fraction, a brass-containing scrap fraction and a collectable fraction, which contains manganese, zinc and silver.

Method of processing small batteries

Disclosed is a process for burning cattle dung at a temperature of from 500.degree. to 780.degree. C., preferably from 650.degree. to 780.degree. C., in the presence of one or more aluminum-containing substances selected from the class consisting of bauxite, kaolin and aluminum compound-containing ash from furnaces for firing solid fuels. A major part of the alkalies contained in the cattle dung and a substantial part of the chlorine are retained in combined form in the resulting furnace ash.

Process of burning cattle dung

In a method of processing contaminated sodium oxalate which becomes available in a separating stage succeeding the digestion of bauxite in accordance with the Bayer process, chemicals used in the digesting process are recovered in that moist sodium oxalate which has been separated is dried with the hot exhaust gases from a rotary kiln jointly with aluminum hydroxide or aluminum oxide hydrate and/or reactive alumina at a mole ratio of aluminum to sodium of at least 0.8 and the dried product is decomposed in said rotary kiln at a temperature of 780.degree. to 1000.degree. C. to form sodium aluminate. Suitably drying is effected by spray drying in direct contact with the exhaust gases of the rotary kiln and decomposition is effected at a temperature in the range from 850.degree. to 950.degree. C. and with an Al:Na ratio not in excess of 1.2.

Method of processing sodium oxalate formed during the digestion of

In a method for processing contaminated sodium oxalate which becomes available in a separating stage succeeding the digestion of bauxite in accordance with the Bayer process, chemicals used in the digesting process are recovered in that the moist sodium oxalate which has been separated is dried with the hot exhaust gases from a fluidized bed, particularly a circulating fluidized bed, jointly with aluminum hydroxide or aluminum oxide hydrate and/or reactive alumina at a mole ratio of aluminum to sodium of at least 0.8 and the dried product is decomposed in said fluidized bed at a temperature of 780.degree. to 1000.degree. C. to form sodium aluminate. Suitably drying is effected by spray drying in direct contact with the exhaust gases of the fluidized bed and decomposition is effected at a temperature in the range from 850.degree. to 950.degree. C. and with an Al:Na mole ratio not in excess of 1.2.

Growing community of inventors

Muhlheim, Germany

Walter Koch