Stamped coal cakes in cokemaking technology: Part 1 – A parameter study on stampability

Abstract

Coking of coal blends using high volatile coals with poor caking properties to produce a high quality coke for blast furnace application can be achieved by compacting the whole coal blend before pyrolysis in the so called stamp charge operation. Using stamp charging not only improves the flexibility of the coke making plant using cost efficient raw materials, but oven throughput is also increased. Therefore, in recent years, densification of coals has been introduced even to coals with good carbonisation properties when heat recovery ovens are used. At the Department for Mechanical Process Engineering and Solids Processing of the Technical University Berlin, the two subprocesses, densification and strengthening during stamping, were theoretically and experimentally investigated. The research work aims on the development of an integrated mathematical model, allowing the calculation of cake density and strength of the coal cake for a given coal blend depending on the stamping energy. The first part of this paper defines the overall process objectives and presents results from systematic investigations of the effects of several coal properties on the so called stampability as the integral model parameter for compacting. Surface moisture, coal granulometry and mechanical properties have significant influence on the densification. The incorporation of these parameters into the model allows the differentiated calculation of the cake density.

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

“…Various coal cake parameters need to be optimized during the compaction process. The parameters of importance, according to Abel, Rosenkranz, and Kuyumcu, (2009), Kuyumcu and Sander (2014), Burat, Kuyumcu, and Sander, (2015), and Rejdak and Wasielewski (2015) Granulometric properties of coal particles (particle size distribution (PSD), particle shape, particle density, and grindability).…”

“…Industrial stamp charge technology encompasses the use of a combined stamping-charging-pushing machine. Various authors in this field (Abel, Rosenkranz, and Kuyumcu, 2009;Kuyumcu, Rosenkranz, and Abel, 2010;Kuyumcu and Sander, 2014) have indicated that during this process the bulk density of the feed coal is increased to a compact density of 80% of the true coal density, i.e. a compact density of about 1 100 kg/m 3 , depending on the true density of the coal, before charging to the oven.…”

“…Most commonly, portions in the range of 12% to 16% break from the cake when the mechanical strength is exceeded locally. Coetzer (2019) summarized the causes for this phenomenon identified by various authors (Abel, Rosenkranz, and Kuyumcu, 2009;Madias and de Córdova, 2013;Kuyumcu and Sander, 2014) when dynamic forces act on the cake: Cake weight (i.e. critical cake height) A local reduction of shear strength along a plane that is sloped according to a decreased angle of internal friction (cake failure by shear fracture with the fracture along a sliding plane)…”

“…Poor water distribution or wetting. Abel, Rosenkranz, and Kuyumcu (2009) indicated that a criterion for the sufficient mechanical strength of the coal cake relates that strength to the loading conditions, considering the weakening of the cake and the dynamic stress, through the introduction of appropriate safety margins.…”

Testing of Ore Comminution Behavior in the Geometallurgical Context—A Review

“…Based on the principle design of the simple drop weight test, another instrumented drop weight tester has been designed [27] and has initially been used for the investigation of particle compaction processes. Here, the drop weight itself is instrumented by a load cell and an inductive displacement transducer that yields time-dependent measurement profiles for the entire sequence of primary impact and subsequent rebounds (Figure 7).…”