The solution to slurry contaminants and maximising water reuse

When it comes to underground hard rock mining, the produced slurry often presents significant concern in terms of contaminants and logistics.

In the first instance it is common for potable water to be carted in for excavation as it needs to be of a grade suitable to aerosol and not be an occupational hazard. On top of that is the physical footprint and complexity of surface treatment plants where slurry from the underground site is transported topside for processing into dry cake and treated water.

In the current environment most mine sites have a slurry plant on the surface with multiple silo’s, a number of clarifiers, high maintenance belt presses, conveyor systems and the list goes on.

Through significant technical experience, the Hydroflux Group have switched those concerns to an adaptive transportable solution for a tenth of the price.

Looking at the solution rather than the problem, Hydroflux developed the containerised TunnelMax screw press as a means of placing the process where it can best be implemented, at the rock face, underground, with the shortest point of travel for the slurry and the greatest potential for water reuse back into the excavating machinery itself.

Take as an example the recent tunnelling project as pictured. In contrast to a static surface based plant, the Hydroflux TunnelMax sat behind the tunnel boring machine, underground.

The advantage of close proximity meant the client was able to capture the slurry into adjacent containerised tanks feeding the Tunnel Max directly for processing of the discharge streams into dry cake and produced water.  In this instance, the client chose to process the produced water above ground to ANZECC standards for environmental discharge while the dry cake was mixed with excavation spoil, in the tunnel, for transporting to the surface.

The example above is the TunnelMax at it’s most basic processing stage of primary solids removal. At this stage, the slow speed screw press captures contaminants including excavation spoil and heavy metals while removing liquid and as a result producing the dry cake in a far safer manner using less infrastructure than a typical belt press-clarifier combination.

In addition to the primary stage, many clients choose to integrate a polishing stage to reuse their water and capitalise on the benefits that come with processing at the source. In some instances, reuse might be dust suppression, while in others it may be for boring or excavation but in all cases the important consideration is that it is safe for reuse in the confined environment.

One of the features of the TunnelMax polishing stage is the potential to tailor the process to client mining practices by customising the Hydroflux HyPure membrane solution to match the produced water make up with the reuse intent. Not only is the solution tailored to the individual client, but it is also adaptable to cater for variations in Hydrogeology from point to point within the one location.

Compared to more traditional static treatment processes, the Hydroflux TunnelMax reduces operational complexity, improves reuse potential and captures contaminated spoil in one portable solution. Add to these benefits the considerations of reduced CAPEX and OPEX and the choice becomes as clear as the water we produce.

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