Laboratory Scale Investigation to Improve the Productivity of Stamp Charge Coke Oven through Optimisation of Bulk Density of Coal Cake

Abstract

In the recent past, it was realised that the gross coke yield was going down as a result of lower oven throughput in the stamp charged batteries of Tata Steel. The basic reason for this being the net reduction in the ash content of the coal blend used due to the incorporation of higher percentage of low ash imported coals and reduction in the ash content of captive coals through washing. The coals having higher ash content improves the bulk density, as the specific gravity of ash is higher than that of pure coal. Moreover, the ash components have affinity for water and pure coal repels water, which in case of pure coal, works against the holding together of the blend. Hence, lower the ash content, less is the bulk density of cake under identical stamping energy and lower the bulk density, less is the oven throughput. In order to maximise the oven throughput and productivity, a study was conducted in the laboratory mainly to assess the effect of various blend constituents and their ash content on the bulk density of coal charge. The effect of ash content on the coal cake stability has also been dealt with. This study, in short, is a useful tool for selecting the right type of coals and designing the optimum blend for stamp charging to achieve maximum throughput and productivity.In addition, studies were also carried out to assess the effect of addition of various binders on coal cake stability at lower moisture level which would also help in achieving higher throughput and productivity.

Compaction tests on coking coals. Part 1: Laboratory-scale compaction with a 4-ton hydraulic press

“…The d 50 of the Waterberg sscc materials varied between 0.6 mm and 1 mm, whereas the crushing fineness was more than 99% < 3.25 mm. The particle sizes of the coals utilized in this study were similar to those suggested for compaction or stamping by various workers in the field, namely 85% to 99% < 3.25 mm (Dash et al, 2005;Kumar et al, 2008, Tiwari et al, 2012Madias and de Córdova, 2013;Rejdak and Wasielewski, 2015). In the case of the Oaky North sample, the d 50 was 0.7 mm with a crushing fineness of 95% < 3.25 mm.…”

“…The mineral components in coals are hydrophilic, and pure coal repels water, which in this case works against the cohesion of the blend. Hence, the lower the mineral content, the lower the bulk density of the coal cake, and this decreases the oven throughput (Dash et al, 2005). Less coalified coals contain more oxygen and hydrophilic functional groups than more coalified coals do.…”

Effect of Grinding Behavior on Liberation of Coal Macerals

“…The minimum shear and compressive strength require for stable coal cake are around 14 709 N/m 2 and 156 906 N/ m 2 respectively. 19)…”

Stamping coal cake simulation with Duncan–Kelvin–Maxwell constitutive relations

“…Similarly, in the E-v model, 16 assuming the relation between axial and lateral strains is hyperbolic, the tangential Poisson's ratio v t can be expressed as (2) where G, F and D are material constants given from the hyperbola through triaxial tests. Note that the sign of tensors in soil mechanics is contrary.…”

“…Recently, research has focused mainly on the blending optimisation 1,[2][3][4] of raw material (coal powder) and on the factors affecting the density and strength of coal cake. [5][6][7] The stamping process itself is rarely studied so the lack of information on the stamping operation makes it difficult to analyse and optimise the design of the charging car and operational factors such as coal box pressure.…”