Abstract

COETZER, G.. Compaction tests on coking coals. Part 1: Laboratory-scale compaction with a 4-ton hydraulic press. J. S. Afr. Inst. Min. Metall. [online]. 2019, vol.119, n.4, pp.403-411. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/17/070/2019.

Prior to operating a non-recovery coke pilot plant, it was critical to ascertain coal cake stability during the loading of a 1 m³ coal cake into the oven. Various compaction parameters were verified and established on a small laboratory-scale compaction machine to obtain a coal cake of acceptable stability. These parameters include cake density, cake surface moisture, transverse strength (force applied perpendicular to the original compacted coal cake layers), and applied force to the coal cake. This work determined the behavioural characteristics of the coal while being compacted either with a full-sized or a ¹/3-sized compaction plate in a 9 kg capacity mould. Two different coals were evaluated, namely Waterberg semi-soft coking coal (sscc) and Oaky North hard coking coal. The target wet cake density of 1 100 kg/m³ (79% of 1 400 kg/m³ relative density) was achieved for Waterberg sscc, with a particle size d₅₀varying between 0.6 mm and 1 mm, utilizing the ^1/3-sized compaction plate in the laboratory-scale set-up, with 11.6% surface moisture and 92.2 t/m² commercial equivalent applied force. For Oaky North hard coking coal, a wet cake density of 1 189 kg/m³ (85% of 1 400 kg/m³ relative density) was achieved at a surface moisture content of 12.3% and at a lower applied force than that for Waterberg sscc, i.e. 78.5 t/m². Coal cakes of acceptable strength, and therefore sufficient stability for further processing, were obtained for all materials evaluated during this study. Further studies should be conducted to determine the effect of zeta potential during the compaction of coals.

Keywords : coking coal; compaction test; coal coke stability; wet coke density; laboratory scale.

        · text in English     · English ( pdf )