Abstract: In a process for the recovery of silver by flotation from the residue from the wet extraction of zinc, the residue from the neutral wet extraction of zinc, the residue from the neutral wet extraction of zinc is recovered and is subsequently ground in an attritor and the residue which has been ground in an attritor is subjected to a flotation.

Abstract: In a process for a selective flotation of a copper-lead-zinc sulfide ore the raw ore is ground and slurried with water and the resulting suspension is aerated with air to adjust a certain oxidation-reduction potential and is subsequently successively conditioned with SO.sub.2, Ca(OH).sub.2, and collecting and frothing agents, whereafter a flotation of Cu is effected. An oxidation-reduction potential which is 70 to 90% of the oxidation-reduction potential desired for the flotation of Cu is adjusted by the aeration of the suspension with air before the flotation of Cu, the desired oxidation-reduction potential of 60 to 340 mV is adjusted during the flotation of Cu by the aeration with air, the flotation of Cu is effected at a pH of 8.5 to 10.5 and Cu is removed from the flotation process with the froth.

Abstract: Contaminated soils are treated in that an aqueous slurry of the soil is separated into a coarse fraction and a fine fraction, the fine fraction is subjected to flotation, the resulting froth is dewatered and then carried away as a pollutant concentrate, and the underflow from the flotation is dewatered and is then carried away as purified soil. An emulsified oily vegetable oil is used as a collector agent for the selective flotation or an emulsified light mineral oil is used as a collector agent for the selective flotation and a light mineral oil is stirred as a conditioning agent into the fine fraction before it is subjected to the selective flotation.