Efficiency of air classifiers in dry separation of nometallic mineral fines

Abstract

The article analyzes dry separation of nometallic mineral fines with a view to enhance the process efficiency owing to optimized choice of equipment design variables and operating conditions. The earlier studies neglected the separation process capacity and energy intake, which weakened representativity of the research findings. It is possible to improve the quality and quantity characteristics of air separation using the specific effect criteria which define the perfection rate of the test machines and determine their optimal design variables. The main specific effect criterion is assumed to be a criterion which provides such choice of design variables that the operational factors with respect to the other criteria are the best. In the air classifier efficiency evaluation, the main criterion is a criterion which takes into account both the mechanical energy intake and the processing time. The analysis of the criteria used to assess the classification machines finds out that the main optimization criterion for air classifiers is a criterion that takes into account the quantity of pollutants in separation products, while the main optimization criterion for vibratory air classifiers is a criterion that takes into account the mechanical energy intake of separation. This study also adjusts parameters of air classification machines using their earlier recommended ranges: the grid incline angle αgrid = 8–9 deg, the vibration amplitude Ас = 2.5 mm and the vibration frequency ωc = 100 s–1 of the vibratory air classifier body. The obtained results enable recommending choosing design variables and operating conditions in air classification and vibratory air classification in dry separation of granite by the size of 10 mm and in dry separation of carbonate minerals by the size of 1 mm.