Determination of open pit diamond mine limits with regard to stripping time difference

The analysis of methods to account for stripping time difference at the stage of determination of limits in deep open pit mining reveals advantages and shortcomings of the methods and provides a principled approach to determination of a discount ultimate strip ratio for the most representative geological and geotechnical conditions of diamond-bearing ore bodies in the form of single pipes. Discounting of marginal strip ratios is based on adding the common formula with an average mean discount coefficient represented by a correlation of mining rate decrease, stripping zone height and highwall slope angle. It is shown that target variation of the factors included in the discount marginal strip ratio allows considerable influence on depth and efficiency of open pit mining.     

Molecular beam epitaxy of thermodynamically metastable GaInAsSb alloys for medium IR-range photodetectors

Semiconductors - The features of growth of GaInAsSb alloy with In content as high as 25 mol % lattice-matched to GaSb by molecular beam epitaxy are studied. These alloys are promising for use as...     

Fast magnetosonic and fast Alfvén waves in an elliptic plasma cylinder

The propagation of ion-cyclotron waves in an extended cylindrical plasma is analyzed analytically. The results obtained show progress in constructing a two-dimensionally-nonuniform analytical theory. Pis’ma Zh. Tekh. Fiz. 25, 33–38 (September 26, 1999)     

Noble gases as indicators of molecular-selective gas transport in polymeric membranes

Methods of estimation of molecular-selective gas transport parameters in polymeric membranes and explanation of separation selectivity evolution for ‘small’ and ‘large’ molecules up to inversed selectivity are proposed based on comparative analysis of diffusion and solubility of noble gases as isotropic diffusion probes in different classes of polymers and block copolymers on their basis. Two approaches are considered in this work: (1) analysis of diffusional migration of permanent gases, lower hydrocarbons, and alcohols (vapor) in glassy polymers and rubbers relative to the diffusion of noble gases including radon; (2) adaptation of the ‘hard sphere’ theory developed for gas solubility in liquids to the calculation of the solubility of gases in the polymer matrix. In the latter case, noble gases as isotropic probes are used for calculating the required fitting parameters of the polymer medium.     

Image-processing procedures for quality estimation in production of elastic foamy materials

We present a system for estimating the quality of polyurethane foam, which is able to measure the apparent density and mean size of the cell. The system consists of a flatbed scanner of high resolution, an electronic balance, and a personal computer. We present the new way for measuring the sample volume using six nonorthogonal projections and adapt the marker dividing line algorithm for cell segmentation in the scanned image. We examine an approach for determining the efficiency of the image-processing system operating as a measuring system on the basis of the Six Sigma method.     

Computer diagnostics of the mesoscopic structure of nanoporous aluminas

A method based on the computer analysis of electron microscopic images of the surface of porous anodic aluminas is described for deriving quantitative information about the mutual arrangement of cells and pores (mesoscopic structure). The developed package of programs is used to calculate dimensional parameters of a cellular-porous structure, the size distribution of the image objects, and the morphological functions of the radial distribution of cells/pores, which are analogs of the function of the radial distribution of atoms characterizing the short- and medium-range orders of atoms in amorphous materials. A quantitative analysis is performed for the first time using the method of pair functions, which was used earlier for identification of the atomic structure in amorphous films. The developed package of Spot Calculator and MFRD programs for processing electron microscopic images of the surface can be used to study the mesoscopic structure of not only porous aluminas but also any materials if characteristic features can be distinguished on their surface.     

Effect of longwall face advance rate on spontaneous heating process in the gob area - CFD modelling

A commercial CFD software programme, FLUENT, was used to study the oxidation process of coal in the mined-out longwall (gob) area. A three-dimensional, single-phase model with a continuously advancing longwall face has been developed. For the model, the gob longwall area was designed on the basis of the actual longwall panel operating in the Ostrava-Karviná Coal Mines (OKD, Czech Republic). The behaviour of the coal to oxygen was modelled using the results arising mainly from the former laboratory-scale experiments with Czech bituminous coals. Basically, the technique of pulse flow calorimetry and measurements at a continuous airflow reactor were applied during the laboratory investigations. In the contribution, the main focus was to understand the effect of the longwall face advancing speed on the oxidation heat production as well as evolution of the gases in the gob area. Simultaneously, the effect of coal crushing in the mined-out area on the spontaneous heating process was examined.Numerical simulations confirmed the existence of a “favourable” zone for the onset and development of the spontaneous heating process in the gob area. The location and the maximal temperature reached in the “favourable” zone were found to be significantly affected by the advancing rate of the coalface. The slower the advancing rate is, the higher the maximal temperature and smaller the depth of the “favourable” zone in the gob area are. When the rate drops to a certain “critical” value, spontaneous heating turns to flammable combustion of the coal. The value of the “critical” advancing rate was confirmed to increase if the grain size of the coal left in the gob decreases. Numerical examinations of carbon monoxide concentrations then proved that small incidents of spontaneous heating could occur in the gob area that need not be detected in the airflow of the longwall tail gate.     

Catalytic heat-generating units for industrial heating

The design and operation of catalytic solid fuel-flamed heat-generating units intended for local heating of industrial and municipal facilities are discussed. An advantage of these units is that their thermal power can be regulated between 0.5 and 10 Gcal/h and that they are capable of burning various types of solid fuels, including low-grade ones and waste, in an environmentally friendly way. Data characterizing the operation of an industrial-scale boiler plant with a thermal power of 3 Gcal/h are presented.     

New Filtering Equipment for Dewaxing and Deoiling Processes

The results of the first stage of renewed research on the development and introduction of a dynamic pulsation filter for dewaxing and deoiling processes using selective solvents are presented. __________ Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 6, pp. 17 – 21, November – December, 2005.