A big affection of the rock environment and groundwaters occured during the chemical mining of uranium in the years 1966 to 1996 in the neighbourhood of the town Straz pod Ralskem in the Czech Republic. It is necessary to clean the residual technological solutions (RTS) from the underground. The pH of the solutions in some places is still less than 2 and the concentration of sulphates reachs up to 65 g/l.

The remedial activities consist of pumping of the RTS from the ground and reprocessing of the RTS in the surface technologies. The implementation of the new neutralization technologies NDS ML and NDS 10 help us with increasing of the efficiency of the remedial process.

The NDS ML technology (“Mother liquor reprocessing station”) started its operation in 2009 and it processes the concentrated technological solution from the evaporation station after the alum crystalization (mother liquor) with the concentration of total dissolved solids up to 250 g/l. The principle is the neutralization of the acid solutions with the aid of the lime milk. The suspension is then filtrated in the filter press, the filter cake is deposited in the tailings pond and the filtrate is injected back into the underground rock environment.

The NDS 10 technology (“Neutralization and Decontamination Station NDS 10”) started its operation in 2012 and it works on the same technological principle as the NDS ML station. The difference is that the NDS 10 station can process higher volume (4.4 m3/min) of the RTS with lower concentration of total dissolved solids 20–25 g/l.

This poster describes the experiences of the state enterprise DIAMO with putting of these two neutralization technologies into operation and with using of the lime milk neutralization in such a large scale.

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