Accelerated moisture reduction
About 10 years ago during a groundwater-lowering exercise at a sand-processing quarry, it became apparent that a beneficial side-effect was taking place on the periphery of the pumping project. Sand stockpiles located adjacent to the area being dewatered were generally very wet at their bases, with gravity drainage being used to reduce the moisture content from around 25% to approximately 6–8% over a period of two to three weeks, weather permitting.
As the dewatering project progressed it was observed that ‘flow paths’ began to develop from beneath the sand stockpiles towards the operational vertical well-point installation, resulting in very rapid drying of the stockpiles. Moisture readings taken at the time showed that after just 2h of pumping a final moisture-retained value of 3% had been achieved within the stockpiles.
These findings led to subsequent research and development work on vacuum-assisted moisture reduction, which has culminated in the production of a cost-effective advanced horizontal accelerated moisture-reduction pumping system, designed specifically for use in sand and other material-processing industries.
The system, which is expected to transform stockpile drying times and significantly reduce the costs associated with force drying materials in kilns or oil-fired furnaces, has been patented by Len McGarry, geotechnical consultant and managing director of newly formed Moisture Reduction Systems Company Ltd.
A complete accelerated moisture-reduction system has recently been installed at Tarmac Northern’s Loudounhill Quarry, in East Ayrshire, to help speed up the drying of the site’s concrete sand and fine washed-sand stockpiles.
Commenting on the new installation, quarry manager Charlie Lamb said: ‘Since last September when we changed over from gravity drying to an accelerated moisture-reduction system, we have noticed a big improvement in our drying times.’
Moisture Reduction Systems say that prior to quoting for a new installation, they will be happy to conduct a simulated ‘drawdown’ pumping test, free of charge, on a sample of their customer’s sand material. According to Mr McGarry, in one recent test a fully saturated concrete sand achieved a 1.8% final moisture retained value after just 2.5h of pumping.
Accelerated moisture-reduction systems can be individually designed to suit most material producers’ requirements and a fully skilled installation service, together with full technical back-up, is available to ensure that users achieve the most cost-effective end results.
