Effects of power coal preparation in two parallel jigs

W artykule przedstawiono wyniki analizy wzbogacania grawitacyjnego węgla we fragmencie układu technologicznego przeróbki węgla - wzbogacania w dwóch osadzarkach. Uzyskane wyniki dotyczą szczegółowej analizy jednego z układów rozpatrywanych w opracowaniu [11]. Założone zostały zmiany gęstości rozdziału w jednej z osadzarek, a wyznaczone zostały optymalne gęstości rozdziału w drugiej osadzarce przy różnej zadanej jakości koncentratu końcowego. Podane zostały względne wartości produkcji dla rozpatrywanych przypadków wzbogacania.Stabilization of coal quality parameters is an important technological problem especially in the presence of variable raw coal characteristics such as coal size distribution and its washability. Local control systems for gravitational preparation processes have been introduced (the control of the density of separation in heavy media vessels and the refuse discharge in jigs) to compensate the influence of various disturbances on the performance of technology. The main task of these local control systems is to stabilize technological chosen parameters on the desired level, which makes it easier to keep the quality of coal within the limits of declared price and allows to control final products parameters according to the terms of the contract. Concentrates of steam or coking coal are often produced in a system of parallel processes of coal separation in heavy media vessels, jigs and flotation. In such a system there usually exists an optimal point of work (global extremum) for which the maximum amount of the final concentrate with desired ash content can be obtained. The final product of desired quality (ash content) can be produced for various set values of the densities of separation in both processes so that the blending of two components would give product of desired quality. Further analysis will show that the considered system has the characteristic of the extreme object i.e. that for the desired ash content in the product it is possible to choose optimal separation densities for which the system produces the maximum amount of the blend or the maximum value of the product [1]. In the paper an application of computer simulation program for coal preparation processes analysis and their control has been presented. The integral part of this software is an algorithm of searching the function algorithm of control target, i.e. the maximum production function of preset quality. In the paper is presented results of analysis part of coal preparation system, that is two jigs. These results relate detailed analyses one of certain of plant reviewed in the study [11]. Value of separation density was desired in one jigs, but in second jigs the value of separation density was calculated as optimum value. The density of separation in jigs can be changed indirectly, for instance by the adjustment of the float position linked with refuse removal gate. Relative values were given to the production for examined cases of enriching