The objective of this work is to substantiate the hereditary character of the stresses and deformations accumulation in loose mined rock during the disintegrators working surfaces convergence. It is shown, in particular, that the layer porosity after compression and the side thrust coefficient depend not only on the applied pressure, but also on the initial porosity. It is substantiated the mechanism of interrelation between the stresses and deformations of a layer. The experimental researches on fine– grained granite compression in a rigid matrix have been fulfilled. The approximation of obtained results by polynomial functions has been carried out. The coefficients have been determined by the least-square method. The close agreement of the analytical and the experimental values has been recorded. The initial porosity parameter was put into the equation of dependences of the current porosity and the side thrust coefficient on pressure. The mechanism of the forces distribution on separate particles contacts has been explained in terms of the material compacting hystory. The practical value of the research is in calculating the disintegrators operating parts parameters with account of the mined rock layer condition prior to the act of crushing.
The purpose of paper is to develop an algorithm for designing the half-masks of air-purifying respirators and assessment of their safety factor of insulation. To create a 3D model of a head, two-parameter NIOSH tables (National Institute for Occupational Safety and Health) were used. The model drawings were made with the use of Solid works software package. Differential geometrical method based on applying the moving Frénet trihedral was used to design half-masks. Two designs of the respirator half-mask were developed based on the averaged length and width of face (Modification 1), and length of face and lips (Modification 2). As a result of modeling test, the area and perimeter of the mask contact line have been defined. The safety factor of half-mask insulation was calculated theoretically. It has been established that the safety factor of Modification 1 half-mask is 2.5 times higher.
Purpose. To determine maximum dust holding capacity with the set dust-catching efficiency of two successively adjusted filtering elements made of polypropylene material when being dusted with coal dust. methodology. To define resistance of filters and their dust holding capacity, a gravimetric method was used according to DSTU EN 143-2002 requirements. The calculation methods consist of two stages. At the first stage the diameter of pre-filter fibres is calculated on the basis of maximum dust holding capacity for the set ultimate pressure and dust particle target size. At the same time, thickness and density of fibre packing of a filtering layer are selected by reference to conditions of the technological process of its formation while producing filtration fabric. At the second stage the radius of the main filter based on the set dust-catching efficiency is calculated. findings. It has been established that dust deposit on polypropylene filtering elements of respirators occurs in the front layer. It has been defined that dust holding capacity and protective power time of respirators can be increased while filtering coal dust with a system of two successively adjusted filtering elements with the following parameters: packing density of 55 and 27 g/cm 2 ; a fibre radius of 2-4 and 6-10 microns and a thickness of a filtering layer of 4 and 3 mm, respectively. This allowed creating an anti-aerosol two-layer polypropylene filter RPA-TD 1.2 which meets the DSTU EN 143-2002 requirements and can be used for protecting people's respiratory organs at the site of intensive coal dusting including stoping face, coal transloading, dressing plants and others. originality. Dust holding capacity of filters depends on generation of self-filtering dust layer, which can develop on the work surface at speeds below 0.04 m/s. Practical value. Rational parameters of the two successively adjusted filtering elements of polypropylene fabrics were defined with the protective power time of the proposed system increased by 25 % compared to the used filtering elements for RPA respirators.
Проанализированы вопросы процессов электроионизации при использовании импульсного коронного разряда, а также предложена система коронирующих электродов типа «острие-сетка». Установлена зависимость концентрации аэроионов от расстояния до ионизатора, позволяющая устанавливать заданный ионный состав для накопления максимально возможной величины заряда на мелкодисперсных частицах, однако скорость воздушного потока ограничивается технологическими параметрами и ее значения определяются в зависимости от условий (конструкции технологического оборудования, типа аспирационной системы и др.), а величина напряжения импульса ограничивается параметрами зарядного устройства при которых исключается «пробой». Ключевые слова: электроионизация; импульсный коронный разряд; импульсное напряжение; аэрозоль; зарядная камера; коагуляция.
Requirements concerning the selection of filtering respirators according to ЕN 529:2006 European standard have been analyzed; the requirements have been compared with the national recommendations given in the corresponding ДНАОП 0.00-1.04-07 normative act on labour protection. It has been determined that the protective efficiency of the respiratory protective devices is characterized by three various parameters characterizing the coefficient of protection – two of them are determined at the working place. However, adequate selection of a filtering respirator is tested in terms of nominal coefficient of protection being determined in a laboratory. Such an approach may result in certain errors due to the set of various factors being available under working conditions. It is proposed to use the value of the expected coefficient of protection determined in the USA being equal to 10 MAC while selecting a filtering respirator. Recommendations are given as for the improvement of respiratory protection of a worker under operational conditions.
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