This safety focus is very pertinent when we look at the design and construction of one of the largest and most integral parts of mining infrastructure, the Tailings Dams. Generally, these earth and fill embankment dams are designed to be the physical compound for by products of mining operations aka Tailings. Owing to the sheer volume of tailings contained in these dams, these structures are placed under extraordinary loads.
However regardless of historical events, Tailings dam failures are yet to have been eliminated worldwide. It is estimated that in excess of 300 tailings dams still collapse per year, of which a small percentage suffer major failures resulting in the catastrophic loss of human life, environmental damage and huge economic costs. Such was the concern prompted by recent tailings dam disasters, the UN recently published a report into the safe storage of mine waste, the fundamentals finding of which was that ‘safety is no accident’ http://www.grida.no/events/9
This report, like many others invariably points to the integrity of the earth and rockfill embankment as being critical in the design and construction of tailings dams. Within this, construction materials testing plays an upmost important part, tests that at minimum can determine material dispersion, compactive effort and density as well as determining minimum plasticity and particle size requirements.
Without these set perimeters and designs being achieved, embankments can be easily corroded. One such example can be the formation of small tunnels which are as a result of soil particles forming into a state of suspension and being washed away. These tunnels unavoidably grow as further amounts of soil are dispersed on the down-stream of the dam. Eventually, these tunnels will reach the tailings pool resulting in the increased flow of water through the tunnels and the ensuing formation of enlarged holes. Unfortunately, this will likely result in the imminent collapse of the embankment, the result of which could have been unavoidable.
Ultimately, dams that have been constructed with materials of a dispersive nature would be at risk of failing due to this tunnelling process. As a result, tests such as the ‘Determination of Emerson Class Number’, ‘Pin Hole Dispersion’ and ‘Permeability’ are of paramount importance to our clients when determining the dispersive properties of a soil. As too do tests that measure the way in which soil, sand and clay particles are sized and distributed determine soil structures and strength.
Given the huge implications, having upmost confidence in the results that have been produced by your chosen testing supplier is imperative to dam design and construction. Therefore you can be rest assured that the Coffey Testing team will approach your testing requirements with diligence, care and industry leading expertise.
If you would like further information about Tailings Dams, please contact us.