The issue of the influence of the concentration of the solid phase on the reduction of energy costs and specific energy consumption during pulp transportation is considered. The procedure for preparing slurry from the current enrichment tailings is shown. A scheme is given and the operation of a hydroficated unit for thickening and hydraulic transport of backfill mixtures is described. A diagram of the movement of solid particles in one of the units of the complex – a lamellar thickener is shown. The summary table shows the main design parameters and characteristics of the lamellar thickener. A general view of the laboratory setup used for experimental studies with slurry at various concentrations is given. An example of calculating productivity, density and specific load is presented. The dependence of the shear stress on the velocity gradient was determined for various pulp concentrations. Experimental studies of the process of thickening the production of slurry from the current enrichment tailings have been carried out. It was found that the geometric dimensions of the thickener depend on the concentration of the solid phase in the transported mixture. It is concluded that the flow rate of the slurry and the head loss are functions of the rheological characteristics of the viscoplastic slurry and can be calculated from the derived calculated dependencies.
Existing methods for determining the effective power, based on the calculation of the average indicator operation of the engine during the piston stroke, do not take into account the change in thermodynamic parameters and the polytropic operation of the engine, the value of which depends on the polytropic efficiency of the duty cycle. This is the reason that the calculation of the effective power leads to some error – the margin of the engine features. The identification of this stock allows us to review the entire line of dump trucks in the direction of increasing their pass- port effective capacity, which will lead to a reduction in capital purchase costs due to the choice of a previously un- derestimated and cheaper option, as well as a reduction in current operating costs due to a decrease in the specific fuel consumption rate. Taking into account the stochastic nature of the transport process and assessing the influence of all external and internal factors when calculating the rational mode of operation of a mining truck can further reduce specific fuel consumption by choosing the rational speed of its movement in loaded and empty directions.
The object of study is the system of hydrotransport of iron ore processing tailings at JSC «EVRAZ Kachkanarsky GOK». The aim of the work was to determine the parameters of the hydraulic transport of tailings of the iron ore enrichment at weight concentrations of the solid phase from 30 to 70 % and to develop recommendations for the industrial operation of hydraulic transport systems of highly concentrated slurries of the Tailing Facilities of the Kachkanarsky GOK. Laboratory studies of the parameters of hydrotransport of thickened tail pulps were carried out with the development of a calculation method; pilot tests of the hydrotransport system under the conditions of the Tailing Facilities of the Kachkanarsky GOK. It has been established that using polyurethane coatings on the inner surface of the slurry lines significantly (1.75 times) decrease the specific pressure loss on the hydrotransport of thickened fluids. This allows to significantly increase the range of transportation for placing tailings in the distant parts of the storage zone. The introduction of research results is in the project of reconstruction and development of the tailing facility of the TF of the Kachkanarsky GOK for the period 2018-2020. It is proposed to use the results of work in the project of reconstruction of the hydraulic transport system at the TF of the Kachkanarsky GOK by switching to the hydraulic transport of slurries thickened to weight concentrations of 35-40 % in the slurry pipes with an internal polyurethane coating, which will ensure energy saving in the hydraulic transport process.
The article presents analytical calculations of specific pressure losses during hydraulic transportation of slurry tailings from iron ore beneficiation processes at the Kachkanarsky MPP during the storage of processing tailings in the tailings pond. The calculations were performed based on the results of experimental studies of dependence of specific pressure losses on roughness of inner surface of pipelines lined with polyurethane coating. In the process of experimental determination of pipeline polyurethane coatings roughness, it was established that the physical roughness of the coatings is more than four times less than the roughness of steel pipelines, which leads to a decrease in the coefficients of hydraulic resistances included in the design formula for the specific pressure losses - the Darcy-Weisbach formula. The coefficients of relative and equivalent roughnesses for pipelines with and without coating have been calculated. Comparative calculations have shown that the use of polyurethane coatings of hydrotransport pipelines contributes to a decrease in the specific energy during hydraulic transportation of processing tailings of iron ore from Kachkanarsky MPP in 1.5 times. To assess the nature and intensity of changes in the physical roughness of test pipes with polyurethane coating, experiments were performed on the roughness on a laboratory hydraulic bench. The prepared slurry of the iron ore tailings of Kachkanarsky MPP was pumped through a looped pipeline, in the linear part of which three test coated pipes were sequentially installed. Experiments showed that the roughness after running 484 hours on all the samples of the pipelines varies insignificantly. Roughness values are in the range from 0.814 to 0.862 μm. As a result of the processing of experimental data by mathematical statistics, an empirical formula is obtained for calculating the surface roughness of the polyurethane coating surface, depending on the time of operation of pipeline transporting the slurry of the iron ore processing tailings.
Analysis of the work hydrotransport systems in processing plants shows that the efficiency of this type transport does not match its technical capabilities: the high laboriousness involved in the operation of the equipment, high hydroabrasive wear of slurry pumps and pipelines, low working life pumps, high metal consumption and energy. The main reason for the lack of effectiveness of hydraulic transport is hydroabrasive wear impellers of slurry pumps, causing rising levels of vibra-tion pumps, reducing the pressure characteristics, general technical state of hydrotransport system and as a result - low pumps life, not exceeding 500 hours of continuous operation. In paper, it is shown that as a criterion of period normal operation slurry pump can be used coefficient of techni-cal state, the value of which is proportional to the relative head, degree of hydroabrasive wear of the impeller and time of continuous operating. The coefficient technical state of slurry pump can be represented as a function of current flow rate and the RMS value of vibration velocity. The re-sults of theoretical and experimental studies used to develop algorithms and techniques express-diagnosis and monitoring of slurry pumps in hydrotransport system, data which indicate the need for routine maintenance of pumping equipment.
In the paper it is shown that application of standard design methods for hydrotransport used for slurry with small concentration of a solid phase and for hydrotransport of high concentration slurry leads to considerable divergences between practical values of pressure losses which are received as a result of calculation. A major factor, which defines errors of calculation of hydrotransport of slurry with high concentration of a solid phase by means of standard techniques, is that these techniques do not consider rheological characteristics and parameters substantially influencing the amount of spe-cific pressure losses. The offered model of a pulp movement and technique developed on the basis of this model allow to define hydrotransport parameters with a margin error no more than 0,1.
The problem of decreasing power consumption by hydraulic transport systems remains to be the most important among other problems in the mining industry. The increase of solid material concentration in the volume of transported pulp leads to reduction of general pulp flow rate on the one hand and to increase of pressure losses and, accordingly, of a necessary head for over-coming hydraulic resistance on the other hand. The problem of minimizing power consumption in slurry transport is of particular relevance now when there is a tendency for hydraulic transport of highly-concentrated pulps and pastes to be widely used in the mining industry. The article shows that the energy intensity to a certain extent depends on the performance of hydraulic transport of solid materials, and this dependence is of extreme nature. At low concentra-tions of solid particles large volumes of recycled water have to be pumped to provide the neces-sary performance, which leads to consumption of large amounts of electricity. The increase оf concentration results in the decrease in the volumetric flow rate of the pulp and, accordingly, spe-cific power consumption of the process. The process of reducing energy consumption takes place up to a certain critical value of the concentration above which a further increase in the concentra-tion raises power consumption.
The article deals with the physical model of high viscosity oil-in-water emulsion flow, which concern both structural and plastic properties of viscoplastic liquids. On the basis of theoretical study, which was proved with experimental data, computation algorithm of high viscosity oil in emulsion state pipeline transportation was developed.
Предпринята попытка на теоретическом уровне оценить величину начального напряжения сдвига при гидравлическом транспортировании высококонцентрированных гидросмесей хвостов обогащения руды. Используются отдельные положения теории подобия при сочетании чисел Рейнольдса, Фруда и Эйлера, совокупность которых привели к новому безразмерному критерию, характеризующему начальное напряжение сдвига.
One of complicated aspects in designing and developing of deep-water complexes is estabfishing economical and safe systems of elevating carrying out transportation of valuable fossil from underwater face up to aqueous surface to transport vessel. Very perspective for elevating of rock mass are submarine modules with submersible camera, connected with transport piping, along which the transportation of mineral raw in the form of mixtures is carried out. To practically unknown questions, directly associated with the possibility of designing and building up of submersible cameras, the calculation of the parameters of the vertical elevating of rock mass with higher depths can be applied.
Coal-water slurry (CWS), which is a hydro mixture of ground coal and water, can be regarded as a technological type of power-plant fuels. Provided that necessary requirements are met during CWS preparation, CWS can make a valuable alternative to traditional types of liquid and gaseous power-plant fuels, such as natural gas, mineral and boiler oil, for burning in boiler furnaces and combustion chambers of gas-turbine units. To secure power plant conversion using CWS, it is necessary to consider a number of tasks related to the development of requirements for the preparation of CWS from coals of different categories, hydraulic long-distance transportation of CWS and design of CWS injection devices to ensure combustion of suspension jet in a short flame. The general problem of using CWS as a fuel for power plants is considered and general research trends in this area are shown.
Течение вязкопластичных гидросмесей по трубопроводам сопровождается перераспределением концентрации твердой фазы по сечению потока. При структурном режиме течения и линейном характере распределения твердой фазы концентрация в ядре потока и в кольцевом пространстве составляет соответственно 1,6 и 0,8 от исходного содержания твердого.
В процессе проектирования систем гидротранспорта приходится выполнять большой объем расчетов, обусловленных необходимостью анализа различных вариантов компоновки схемы, определения параметров потока смеси, экономических показателей и др. Этот объем работы может быть достаточно быстро выполнен с помощью ЗВМ. Однако это требует разработки ряда программ, из которых должен быть сформирован пакет программ, позволяющий решать различные задачи при проектировании, эксплуатации и реконструкции гндротранспортных комплексов ...
Существующие запасы окисленных никелевых руд Республики Куба состоят из лимонитовой (железистой) и серпентинитовой (магнезиальной) фракций, при этом серпентиниты составляет примерно одну треть запасов. Технологический процесс переработки серпентинитовых руд на предприятии имени Педро Сото Альба и разница геодезических высот между заводом и месторождением делают более выгодным применение самотечного гидротранспорта обогащенного минерала до металлургического завода как наиболее экологически чистого вида транспорта продуктов обогащения и к тому же не требующего снабжения энергией. Однако состав твердой фазы пульпы создает определенные трудности для ее движения ...
В технологических процессах гидравлического транспортирования насыпных материалов применяются различные типы сгустителей исходной двухфазной смеси. В последние года получили распространение, особенно за рубежом, сгустители пластинчатого типа, так называемые "Lamell". Принципиальным отличием этих сгустителей от традиционных, например типа " Dora", является деление исходного потока сгущаемой гидросмеси на ряд ламинарных течений при помощи тонких пластин, устанавливаемых наклонно в корпусе сгустителя, на некотором малом, обычно 30-50 мм, расстоянии одна от другой.
Перистальтический насос по принципу действия относится к насосам вытеснения (объемным). Основным элементом, определяющим в конечном итоге надежность насоса, является рабочий шланг, воспринимающий в процессе работы нагрузки, определяемые деформацией стенок шланга и внутренним давлением ...