Calculation of a closed grinding cycle in a jet mill with two classifiers

Abstract

The matrix calculation method is successfully used for calculating the closed cycle in a jet mill. In the traditional closed-cycle scheme of a jet mill, a dynamic centrifugal classifier is used for fine separation of the grinding product. The circulation load can be up to 5 or more. This involves using a high-performance classifier the cost of which will be a significant share of the total installation cost. In addition, the dynamic classifier rotor wear is proportional to the quantity of material, i.e. performance. To eliminate these shortcomings a closed loop scheme with two consecutive classifiers is proposed within the framework of the matrix model. Moreover, the first classifier must be of the pass-through type and the second is of the dynamic one. The use of this scheme in mica production allowed reducing the circulation load on the second centrifugal dynamic classifier for fine separation of the material by two times. Equations that allow determining the granulometric composition and mass yield of separation products, the multiplicity of circulation, the load on the mill and classifiers are obtained. The mathematical model proposed permits to calculate the optimal separation limits of each classifier. © Published under licence by IOP Publishing Ltd.