International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

A sulphide flotation concentrate containing 15.2 g/t gold and 893 g/t silver finely disseminated in pyrite (4.1 % sulphidic sulphur in the concentrate) was treated by a two-stage process to recover these precious metals. Initially the concentrate was subjected to microbial oxidation by means of different acidophilic chemolithotrophic microorganisms (bacteria at 37 ^oC and archaea at 59 and 86 ^oC) to expose the precious metals encapsulated in the pyrite. The precious metals liberated in this way were then subjected to leaching by means of solutions containing different reagents (protein hydrolysate, thiosulphate, cyanide and some chemical oxidizers). The leaching was carried out in agitated reactors and up to 93.6 % of the gold and 80.8 % of the silver were solubilised in this way for 48 hours from a pulp density of 20 % at 57 ^oC.

Nowadays are very actual problems of working out waste of non-ferrous metallurgy such as converter slags of the copper enterprise. One of the new direction of additional extraction of copper from slags of converter section is combine method including mechanochemical activation and concentration by flotation of nanostructured initial material. The first stage – is receiving thin crumbled material with high degree of dispersion. This permit furnish an explanation of noticeable changing of properties of high dispersion materials: appearance of activity centers on the surface of minerals because there are alterations and become activity of electronics structures of surfaces layers as consequence of modification of surface. Moreover, take places processes of opening of capsules, including captured particles of some components (metals, minerals from slag, such as copper sulphides etc.). As far as, converting is going with high speeds it’s possible mechanical capturing of initial particles which didn’t participate in interaction during of process converting, minerals may be screened by slag melt. Under the condition of the slowly cooling predominated kinetic mechanism of geterogenic interaction in the silicacontainig system. On the basis of investigations was worked out the technological regulations and fulfilled the industrial probation.

Depleted U₃O₈ was mechanically activated in suspension with tributyl phosphate (TBP), trioctylamine (TOA) and ethylenglycolmonomethylether (EGME) in planetary ball mill with stainless steel vessels and balls. X-ray diffractograms and IR spectra of the activated solid samples were taken. The radioactivities of ²³⁸U and ²³⁴Th in the leaching solutions were determined by α/β liquid scintillation spectrometry. The reduction degree of the oxide, the mean crystallite size of U₃O₈ and U₃O₇ and the leaching of ²³⁸U and ²³⁴Th as a result of the mechanoactivation were determined. Higher degree of ²³⁸U and ²³⁴Th leaching was achieved when mechanoactivation with TBP was performed. No leaching of ²³⁸U daughter product (²³⁴Th) proceeded at mechanoactivation with TOA and EGME. The role of the solvents complexation ability, milling induced increase of crystal defect concentration and UO₂ – ThO₂ solid solution formation is discussed. Further studies have to be made to elucidate the potential of the applied approach as a step in spent nuclear fuel processing.