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

Abstract

Prior to operating a non-recovery coke pilot plant, it was critical to ascertain coal cake stability during the loading of a 1 m 3 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/m 3 (79% of 1 400 kg/m 3 relative density) was achieved for Waterberg sscc, with a particle size d 50 varying between 0.6 mm and 1 mm, utilizing the 1 /3-sized compaction plate in the laboratory-scale setup , with 11.6% surface moisture and 92.2 t/m 2 commercial equivalent applied force. For Oaky North hard coking coal, a wet cake density of 1 189 kg/m 3 (85% of 1 400 kg/m 3 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/m 2. 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.

Compaction tests on coking coals. Part 2: Pilot-plant-scale compaction with a 60-ton hydraulic press

“…The preparation of Waterberg sscc and Oaky North hard coking coal samples is described by Coetzer (2019). The material properties of these coals utilized during the 1 m 3 coal stability tests are summarized in Table I.…”

“…This was addressed, and higher cake densities were obtained. During laboratory tests on Waterberg sscc (Coetzer, 2019), the maximum obtainable wet cake density was 1.10 t/m 3 at a commercially equivalent 92 t/m 2 applied force, at 12.6% surface moisture. A maximum wet density of 1.13 t/m 3 was obtained at a significantly lower applied force (14% lower), i.e.…”

“…This was followed by the compaction of the coal layers with a 1 / 3 -sized plate (see Figure 5), instead of a full-sized plate, according to a preselected compaction philosophy. Laboratory tests have shown that higher compaction wet cake bulk densities and transverse strengths are obtainable with a 1 / 3 -sized compaction plate than with a full-sized plate (Coetzer, 2019). Various layers of compaction (six in total) were utilized to ensure uniform compaction density and mechanical stability of the compacted coal cake to obtain a final coal cake height of 1 m. Each layer was compacted in an overlaying manner of 5× in sections of 5, i.e.…”

“…In order to obtain a coal cake of acceptable stability for the 1 t coke oven, various compaction parameters need to be verified and established. Coetzer (2019) reported on the parameter settings required during laboratory-scale investigations of different coking coals. These findings are preconditions for obtaining high-stability coal cakes for loading into the 1 t pilot plant coke oven to ensure successful cokemaking.…”

Design of Hydraulic Control System for Press Machine and Analysis on Its Fluid Transmission Features

“…Currently, there are few studies on the operating mechanism of modern hydraulic systems under extremely high or low temperatures [5][6][7][8][9]. From the perspective of fluid mechanics, Coetzer [10] simulated the fluid flow in the orifices and gaps of the hydraulic system, and constructed the corresponding experimental device; then, Coetzer conducted structural design of the mechanical platform and drive equipment for the system, and designed the electrical, measurement and control systems in terms of component selection, circuit design, and drive control; finally, Coetzer completed test bench construction, process integration, system debugging and sensor calibration.…”