Evaluation of the Performance of Tri-Flo Separators in Tabas (Parvadeh) Coal Washing Plant

Abstract

Parvadeh Coal Preparation Plant (CPP) was installed in 2008 for the production of the 750000 TPY of clean coal containing 10.5% ash from the raw feed having 44% ash and mainly coming from the long-wall mine. Three units of high capacity centrifugal separators (Tri-Flo) are used for the preparation of the coal in the size ranges of -50+6 mm and -6+0.5 mm. Tri-Flo separators are operating in double stages, so they can produce three products. The nominal feed capacities of the 700 mm Tri-Flo and each unit of 500 mm Tri-Floes are 120 and 70 TPH respectively. However, due to some of the operating difficulties in the coal mine, the current feed capacities to the separators are changed to 160 and 30 TPH accordingly. In this research, sink-float experiments on the representative samples of the Tri-Flo separators were used for the evaluation and optimization of their performance. The experiments were performed in six different densities. On the basis of the experimental results, the operating Ep (Ecart Probable) value of the 700 mm Tri-Flowas 0.075 which was more than the design figure (0.035). Such a difference was mainly attributed to the changes in the feed characteristics. In the small Tri-Flo separator, Ep values were measured as 0.062 and 0.087 for the size ranges of (-1+0.5 mm) and (-6+1 mm) respectively and were in good agreement with the design criteria. The optimization of the heavy media separation circuit of the plant is underway using the results presented here.