Preliminary analysis on roles of metal–organic compounds in the formation of invisible gold

The paper comprises new analytical data on the nature and occurrence of gold in solid pyrobitumen,closely associated with the main gold-bearing sulfide arsenic ores of the Bakyrchik gold deposit(Kazakhstan),related to post-collisional magmatic-hydrothermal origin.Gold mineralization of the deposit occurs mainly in the form of an“invisible”type of gold in the structures of arsenian pyrite and arsenopyrite,and the form of gold-organic compounds of pyrobitumen in carbonaceous-terrigenous sequences of Carboniferous formation.Microscopic and electron microscopic analysis,Raman and FT-Infrared analysis,mineralogical and three-step sequential extraction analysis(NH2OHHCl,H2O2,HNO3?HCl)has been carried out using 9 ore samples(from 3 different types of ores)for a comprehensive study of pyrobitumen and sulfide arsenic ores focusing mainly on organic matter.The sequentially extracted precious metal content of pyrobitumen reaches up to 7 ppm gold and other metals like Ag 4 ppm,Pt 31 ppb,and Pd 26 ppb,forming metal–organic compounds,while arsenic sulfide minerals incorporate 11 ppm gold,39 ppm Ag,0.49 ppm Pt.The enrichment of gold associating with organic matter and sulfide ore minerals was confirmed in this study.Organic matter was active in the migration of gold and the capture of gold by pyrobitumen.Moreover,the reductive organic matter agent released gold,most likely for the sulfide arsenic ore minerals.Pyrobitumen was a decisive factor in the concentration,transportation,and preservation of gold in the deposit.

A Two-step Sequential Extraction for Analyzing Hardly Accessible Precious Metals in Sulfide Ore-bearing Sedimentary Rocks

The work concentrates on extraction of precious metals (Au, Ag, Pd, Pt) and As, Sb, Cu, Pb, Zn, and Fe which are bound to sulfide-ore minerals in sedimentary rocks, using a two-step sequential extraction experiment with two chemical reagents (hydrogen peroxide and aqua regia) on three rock specimens from the black shale formation in Bakyrchik gold-sulfide deposit in North-East Kazakhstan. The experiment allows to determine the speciation of hardly accessible precious metals and to identify the most productive ore-forming stage from the three identified ones. Analytical methods are used for determining polysulfide mineral textures (optical microscopy), mineralogical (XRPD) and chemical compositions (XRF), and for measuring extracted metals concentrations (ICP-OES) in experimental procedures. The analytical results show that the first stage is more productive in gold (total extraction 2.8 ppm) than others and the second stage is more productive in Ag (total 1.6 ppm) and Pd (total 0.01 ppm), while the last stage is more productive in Pt (0.019 ppm) in the deposit.

Multi-exponential model to describe pressure-dependent P-and S-wave velocities and its use to estimate the crack aspect ratio

We present new quantitative model describing the pressure dependence of acoustic P-and S-wave velocities.Assuming that a variety of individual mechanisms or defects(such as cracks,pore collapse and grain crushing)can contribute to the pressure-dependent change of the wave velocity,we order a characteristic pressure to all of them and allow a series of exponential terms in the description of the(Pand S-waves)velocity-pressure function.We estimate the parameters of the multi-exponential rock physical model in inversion procedures using laboratory measured P-and S-wave velocity data.As is known,the conventional damped least squares method gives acceptable results only when one or two individual mechanisms are assumed.Increasing the number of exponential terms leads to highly nonlinear ill-posed inverse problem.Due to this reason,we develop the spectral inversion method(SIM)in which the velocity amplitudes(the spectral lines in the characteristic pressure spectrum)are only considered as unknowns.The characteristic pressures(belonging to the velocity amplitudes)are excluded from the set of inversion unknowns,instead,they are defined in a set of fixed positions equidistantly distributed in the actual interval of the independent variable(pressure).Through this novel linear inversion method,we estimate the parameters of the multi-exponential rock physical model using laboratory measured P-and S-wave velocity data.The characteristic pressures are related to the closing pressures of cracks which are described by well-known rock mechanical relationships depending on the aspect ratio of elliptical cracks.This gives the possibility to estimate the aspect ratios in terms of the characteristic pressures.

Vanishing torsion of parametric curves

We consider the class of parametric curves that can be represented by combination of control points and basis func- tions. A control point is let vary while the rest is held fixed. It’s shown that the locus of the moving control point that yields points of zero torsion is the osculating plane of the corresponding discriminant curve at its point of the same parameter value. The special case is studied when the basis functions sum to one.

Prediction of Dynamic and Aerodynamic Characteristics of the Centrifugal Fan with Forward Curved Blades

The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteristics based on numerical modeling. Three variants of geometry were investigated. The first, basic "A" variant contains 12 blades. The geometry of second "B" variant contains 12 blades and 12 semi-blades with optimal length[1]. The third, control variant "C" contains 24 blades without semi-blades. Numerical calculations were performed by CFD Ansys. Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated to determine characteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also partially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calculation stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using frequency analysis for each variant and working condition.