Abstract: 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.

Abstract: 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.