Technology of coke coal transmission by main hydraulic transport

Abstract

This article presents the results of comprehensive field and pilot plant testing of a technological process chain involving “coal preparation via oil agglomeration, pressurised mainline hydraulic pipeline transport, and subsequent coking of the coal”. The study found that for non-agglomerated coal, the overall degree of coal size reduction during hydraulic pipeline transport is directly proportional to the transport distance. Over a 0–1700 km stretch, this index reached 1. 1.9 for the coal charge, with values for individual particle size classes ranging from 1.5 to 2.5. Notably, there is a significant accumulation of fine classes within the 0.074-0 mm size range. Conversely, agglomerated coal displayed the opposite behaviour: rather than breaking down, coal agglomerates tend to increase in size during hydraulic transport. Over a distance of 1000 km, the overall agglomerate enlargement coefficient was 1.21, with a 22% decrease in the proportion of fine class 0.074-0 mm compared to the feed coal. However, any further transport beyond 1000 km and up to 1650 km begins to abrade the larger coal classes, resulting in an increased content of the 0.0.074-0 mm class from 17. 8% to 31%.The study established that the moisture content of the centrifuge cake (sediment) for nonagglomerated coal is directly proportional to the distance of hydraulic transportation and is strongly correlated with the degree of coal ragmentation. In the case of agglomerated coal, this proportional dependence of the centrifuge cake (sediment) moisture on transport distance appears only beyond 1000 km and is considerably less pronounced compared to non-agglomerated coal. Within the initial 0–1000 km transport range, this dependency is effectively non-existent. Pilot plant (box-type) coking trials revealed a significant decline in coke quality following hydraulic transport of a non-agglomerated coal charge over 450 km. Conversely, the oil agglomeration of the charge had a positive impact on coke quality. Specifically, based on the M25 and M10 indices, coke produced from agglomerated coal transported over 450 km outperformed coke made from the non-agglomerated feed coal in terms of mechanical strength. Furthermore, a reduction in coke fines generation was observed due to the increased mechanical strength of the coke. Overall, the testing supports the viability of the technology of “oil agglomeration, mainline hydraulic transport, and subsequent coal coking”.