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The research data on the technology of manufacturing adjoining parts of valves meant to create required sealing of high-pressure drilling unit cylinders are reported in the article. The serviceability of the new design tools made of superhard composite 10 in cutting out adjoining parts from steel and plastic and in efficient shock absorption of vibrations during cutting-out has been proved. The achieved process result ensures enhanced quality of manufacturing and running efficiency of pneumatic drilling machines.

The discussed basic features of geology at gold placers in Transbaikalia include: long extent, occurrence of a gold pay bed nearby gutter, small thickness of a gold pay bed and deep occurrence sometimes, majority of fine flattened gold particles. It is suggested to enhance development of such placers using new engineering solutions. It is recommended to carry out flushing by means of technologies based on the combination of flotation and gravity concentration followed by activation leaching of gold from concentrates and bullion minerals-gold concentrators. A new leaching technology offered for deep-seated placers involves pre-drainage of a pay bed, saturation of the pay bed with photoelectron-activated concentrated solutions and, finally, electrodiffusion leaching of gold.

Under discussion are the direct dumping flowsheets applied to remove lower overburden layers at coal series deposits in Kuzbass. The authors present the calculation procedure for the parameters of overburden excavation and re-excavation flowsheets using draglines. It is found how the re-excavation coefficient depends on the place and level of the dragline site. The recommendations on selecting the dragline route in case of internal dumping are made. The main trends toward expanding the area of application of the direct dumping technology are identified.

One of the approaches to reducing aftereffects of rock bursts is the dynamic support capable to stand strong dynamic rock pressure events in the form of seismic vibration and failure of adjacent rock mass. The article describes the support design procedure in use in hard mineral mines exposed to rockburst hazard. Different types of rock bolting and surface support are discussed from the viewpoint of energy absorption and yielding.

The article describes designs of injection rock bolts that combine the functions of bolts and injectors in reinforcement of jointed rocks during mining. The data of search for low-toxic compositions are presented. The injection rock bolting installation technology is developed.

In focus is waste management-utilization of screenings after volcanic rock crushing at broken stone production plants. The authors formulate causes of increased production of screenings and their poor utilization. The composition and properties of screenings of granite, gabbro and hornblendite are determined. High content of dust particles limits the use of screenings in production of concrete and mortar. It is proposed to remove dust from screenings by pneumatic treatment. The test data on air separation of screenings by cross-flow classifier are reported. The efficiency of dry processing of screenings is checked in tests of treated sand behavior in composition of heavy concrete. It is shown that treated sand enhances strength of concrete.

Based on the developed parametric model of mined-out area in Artemievsk Mine, parameters and anticipated size of accumulated voids and exposures within the limits of Phase I mining are determined. Stability of underground excavations is estimated by the data of 3D modeling of rock mass stress state. Implementation of recommendations will allow safe completion of Phase I and transition to Phase II mining.

The authors discuss the mechanism of interaction between dust coal and gas flow. The characteristics of two-phase flow are studied with regard to energy of expanding gas at the stage of outburst propagation using the developed method of numerical modeling. The mechano-mathematical method is verified in the wind tunnel tests of dust coal and gas flow. The comparison of the experimental and modeling data show satisfactory agreement in description of two-phase coal dust and gas flow under outburst with formation of shock waves attenuating in the line of the flow. The volume concentration of dust coal in two-phase flow essentially influences the process of the outburst shock wave attenuation.

The article reports test data on adsorption and flotation characteristics of thermomorphic polymer joined with diphenylphosphine-TMPD. The tested materials are natural pyrite and arsenopyrite, and models of gold-bearing sulfide minerals. Electron microscopy and X-ray structure analysis prove that reductive adsorption of gold at the surface of sulfide minerals from HAuCl4 solution allows modeling natural aggregates of sulfides and finely dispersed gold. UV spectrophotometry proves selective adsorption of TMPD at gold. Laser scanning microscopy shows connection of TMPD with micro- and nano-size gold on polished sections of pyrite and arsenopyrite. During monomineral flotation, joint use of TMPD and butyl xanthate at a ratio of 1:1 doubles the yield of gold-bearing sulfides and enables maximum recovery of gold minerals at the total consumption of reagents reduced by 30-50%. It is found that TMPD is selective relative to gold-bearing minerals and its combination with xanthate ensures considerable increment in gold-bearing mineral recovery by flotation.

The authors analyze geochemical data on residual soils of Svetloborsk and Nizhny Tagil massifs of the Ural Platinum Belt after tests aimed to determine content of platinum group elements, gold and silver in different zones of geological cross section. The scope of the analysis embraces theory of gravity concentration in the flows of suspended matter. The criterion of efficient dressability in gravity concentrators (hydraulic separation coefficient) is adapted as an alternative to the equal-settling factor inclusive of the influence of a particle shape. The presented calculated coefficients of hydraulic separation for different shape particles of olivine and platinum prove that flattened particles are separated more efficiently with centrifugal gravity concentrators. The theory is backed with the experimental data, and the conclusion on applicability of the proposed hydraulic separation coefficient is drawn.