Geologiczno-inżynierskie własności utworów z osadników kopalń węgla kamiennego

Krystyna Kolasa

Abstract


ENGINEERING-GEOLOGICAL PROPERTIES OF FORMATIONS FROM SETTLING TANKS IN HARD COAL MINES

Summary

The formations laid down in the settling tanks of hard coal mines are deposits from washing waters supplied periodically. These waters contain up to 200 g/l of solid particles in the form of suspension, where, from mineralogical point of view, the highest percentage (70% on an average) falls to coals. In addition to this there appear also: quartz, clay minerals, muscovite, pyrite, and in the case of magnetite

washing fluids - also magnetite. The settling tanks are characterized mainly by current sedimentation, as proved by predominating diagonal bedding. The process of gravitative sedimentation takes place chiefly after the settling tank is filled in, that is after stopping the supply of washing waters, and it results in a differentiation in vertical profile, giving four types of deposits: coal gravels, quartz sands, coal silt sands and silt clays.
The deposits rarely demonstrate any well-developed sedimentary cycle there. Irregular supply of material, and oscillations in density and granulometrical composition of the suspension are responsible for a considerable changing and diversity in the development of the deposits. Facial differentiation of deposits may distinctly be observed in the settling tanks. In the proximity of inlet pipes coarse-grained deposits predominate, the percentage of fine grains increasing with the distance from these pipes.
Heterogeneity in the development of the deposits and ranging natural humidity considerably affect the physic-mechanical parameters of these formations. The value of the parameters obtained during laboratory examinations are presented in Tables 1-4, Figs. 1-4, and in Table II.
When projecting slopes of materials from settling tanks we have to take into account a fact that these formations are highly susceptible to humidity, and tends to keep high water contents in the heaps. Moreover, they are also susceptible to shocks, and at higher humidity may easily flux.

 


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