Fines circuit performance evaluation

¹ Metallurgy Professional, Khwezela Colliery, Tweefontein Road, eMalahleni, South Africa
² Plant Superintendent, Mafube Coal Mining (Pty) Ltd, Farm Springboklagte, Middelburg, South Africa
³ Plant Manager, Mafube Coal Mining (Pty) Ltd., Farm Springboklagte, Middelburg, South Africa
⁴ Metallurgy Manager, Mafube Coal Mining (Pty) Ltd., Farm Springboklagte, Middelburg, South Africa
⁵ Head of Coal Processing & BI, Thungela Operation (Pty) Ltd., 25 Bath Avenue, Rosebank, South Africa

Abstract

The Mafube processing plant encountered significant discrepancies between the actual yield of middling product compared to the yield predicted by the geological model. This triggered a review of the performance of the coarse-fines circuit given its significant contribution to the middlings product. This paper presents the results of performance measurements conducted on the coarse-fines circuit performance to understand existing performance and improvements required. The Mafube coarse-fines circuit beneficiates coarse-fines within the particle size range from -0.50mm to 0.150mm and consist of the low-cut density three product (LC3) spirals and the teetered bed separator (TBS). The LC3 spirals operate as the primary beneficiation circuit of the coarse-fines whereas the TBS serves as a secondary upgrade stage, to achieve a target overall coarse-fines calorific value (CV) upgrade of 5 MJ/kg. The LC3 spirals results indicated an efficient performance in the primary beneficiation circuit with a CV upgrade of 3.2 MJ/kg with an ash yield of 51%. The secondary beneficiation stage in TBS indicated a further coarse-fines upgrade CV of 1.55 MJ/kg, thus yielding an overall coarse-fines CV upgrade of 4.82 MJ/kg from the Mafube coarse-fines circuit. Notably, the TBS discard stream showed a CV quality of 21.90 MJ/kg which still meets the Mafube middlings product specifications, thus indicating additional potential to capture the Mafube coarse-fines circuit's discard stream as middlings product. A further feasibility study must be conducted to evaluate the potential gains of capturing the Mafube coarse-fines product for the RB2 export stream and the coarse-fines discard for the RB4 middlings stream.