The flotation process of power plants’ ash-slag materials treatment is considered in the article. The original method related to preparing of ash-slag waste before their further bioleaching processing is proposed. The positive results of rare earth metals extraction efficiency increase by bioleaching are obtained. The essence of proposed approach is as follows. Coal combustion’s ash-slag waste is mixed with water to obtain a fine suspension, in which the carbonaceous reagent is injected. Flotation treatment of ash suspension is carried out in mechanical flotation machine with flotation time equal to 15-18 min and air flow rate equal to about 0.7-0.8 m3/(m2·min). The chamber product as treated ash suspension is going to the separation in open hydrocyclone. In such a case the concentration product in the form of ash product is derived to special site, and hydrocyclone overflow is directed to the clearing in pressure flotation machine for extraction of metal ions from the liquid. A positive effect of rare earth metals’ extraction rising related in particular to scandium about 26.6-30.3%, yttrium — 28-34.7%, lanthanum — 50.5-21.5%, as well as precious metals such as gold — 18.7-21.6%, silver — 11.4-21.4% is obtained.

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Problems related to rare earth metals leaching from coal ash and theirs ion-exchange concentration from sulfuric solutions, in particular the characteristics of scandium, yttrium and lanthanum sorption by different ion exchange resins have been considered in this work. It has been shown that the best way to leach rare earth metals from coal ash is a complex acid and biological treatment of ash waste. Kinetics related to the process of scandium, yttrium and lanthanum acid leaching from ash and slag waste of CHPP in Kumertau has been investigated. Subsequent metal solutions concentration was achieved using ion exchange resins. The results of experimental studies related to the processes of rare-earth metals (in particularly scandium) ion exchange concentration by cation exchange resin in the Naform PC-100 have been presented, as well as the results of experimental studies related to rare earth metals (scandium including) sedimentation process, using special sedimentators. Dependences of rare earth metals (in particular scandium) sedimentation efficiency against pH value have been constructed, and recommendations for pH values, that are optimal for rare earth metals sedimentation, have been given. Based on obtained experimental results it was created and tested an experimental laboratory prototype of plant for rare earth metals (scandium, yttrium and lanthanum including) extraction from located near Moscow brown coal basin’s slag heaps, and from ash dumps of Russian Federation’s energy enterprises. This plant’s process flow diagram as well as its operation description has been presented. The created plant was tested in modes previously fulfilled in laboratory conditions. At the same time, carried out integrated exploration have showed the prospects for implementation of developed technical solutions for processing of ash dumps of Russian Federation’s various energy enterprises.

The article covers theoretical basics of floatation process and main stages of flotators’ evolution. special attention is paid to flotation as multistage process as well as to definition of constants with theoretical and the experimental methods. Authors demonstrate that use of theoretical bases of multistage flotation model allows to significantly stimulating floatation process. Leading foreign and domestic innovations in floatation sewage treatment and active sludge thickening are presented. Promising research in constructing multi-tool floatation apparatus (flotation combine) is described. The article provides variants of multi-tool flotators’ design, examples of its integration into operation, and the test data confirming its high effectiveness for sewage treatment and active sludge thickening. Methods of stimulating thickening with carbon dioxide and chemical agents are used for wastewater sludge (including active sludge).