Optimization of complex coal preparation flowsheets

Abstract

A simulation package was developed to model the size reduction and separation process commonly used in Chinese coal preparation plants. the data for the simulation package was collected in coal preparation plants in China, and supplemented by data collected at the Julius Kruttschnitt Mineral Research Centre, during studies of dense medium separators. The new or improved models developed are: (1) a roll crusher model; (2) a rotary breaker model; (3) an empirical model to predict the ash content of coal fractions after breakage; and (4) partition curve models for jigs and dense medium separators. These models were used in conjunction with existing process models to develop a simulation package for five size reduction and fourteen gravity separation flowsheets. These flowsheets can be combined to simulate the commonly used Chinese coal preparation circuits. The simulation program includes an optimization package to optimize: (1) screen apertures; (2) the separation densities for gravity separation devices; and (3) flotation time, so as to maximize the plant clean coal yield at a specified ash content. The Rosenbrock search technique was found to be the most suitable optimization method.