Improvement of radiometric separators using a microcomputer

Abstract

Radiometric methods for separating mineral resources are currently being extended in the mining branches of industry [I].Studies carried out in DonUGI have confirmed the potential and promising nature of applying these methods for separation in the coal industry.Use of a microcomputer in order to monitor radiometric separators makes it possible to simplify coal and ore recognition schemes, and also to increase the efficiency of separation as a result of increasing the accuracy of coal and rock recognition, to improve compensation for lump geometric dimensions as a result of improved treatment of the information signals, to increase the operating reliability of separators as a result of introducing technical diagnostics for individual blocks of separators, and to increase sharply the functional feasibility of the monitoring scheme as a result of introducing service programs. In the current work consideration is given to the possibility of organizing a service program for determining coal processing and enrichment efficiency.The service program is organized in different ways depending upon the separation method used.Consideration is given to a y-absorption method of separation which is used most extensively [2] and is based on the varying level of weakening of a collimated flow of y-radiation by coal and rock grains.The structural layout of monitoring for the y-absorption separator using a microcomputer is presented in Fig. i. On arrival of lumps of coal or rock in the monitoring line (radiation source RS, detector D) an entry relay ER is activated, a code counter CON is activated through a coincidence circuit c:, and a time counter (lump length) COt is activated through coincidence circuit e2. The code counter is charged by pulses from the radiation detector, and the time counter from the standard frequency generator G. On departure of a lump from the monitoring line the coincidence circuits e, and e2 are closed by the end of the entry relay pulse, and the microcomputer carries out sampling of the CON and COt counters, and resets them. Then the microcomputer calculates the counting rate of the radiation detector and compares this counting rate with the threshold value T.The counting rate for the radiation detector n = N/t, where N is code of counter CON; t is code of counter COt. The counting rate for the radiation detector is compared with the threshold value no established in threshold controller T. If n > no (coal), then the output of the microcomputer, controlling the actuating mechanism AM, specifies O, and the lump passes into the concentrate bunker; with n < no (rock) the output controller specifies i, the actuating mechanism operates and the lump is discarded into the rock bunker.With a transporter movement rate of V = 0.5 m/sec and a frequency for the standard generator of 1 kHz, the code of counter COt represents the time for passage of a lump t, m/sec. Lump length l I = Vt.Thus, information enters the microcomputer about the length of each lump, the detector counting rate for lumps of coal and rock, and...