AEL Pioneers Early Warning Device for Hot Holes

Johannesburg - South Africa - AEL Mining Services, an international leader and innovator in commercial explosives and blasting solutions, has developed and launched hot hole temperature monitoring device which will assist in detecting and reducing the safety risks posed by hot holes in coal surface mining.

Developed and researched in conjunction with electronics expert, Designs Unique, the patented hot hole device provides a cost-effective early warning device to the coal mining sector.

According to Dr Andre Pienaar, AEL's Chief Technologist, burning coal exists at coal surface mining sites often associated with abandoned underground operations. "When oxygen enters these old workings through openings such as the blast holes and mixes with the coal, it may cause the coal to spontaneously combust before the hole is loaded with explosives.

A hot hole loading procedure has been developed in partnership with the industry, which is to be used to safely load explosives in any holes with a temperature above 40 degrees Celcius. Holes above 60 degrees are considered hot and attempts are made to cool these holes down with either water or other chemicals such as pyrocool. The temperatures of these holes are monitored after cooling and loaded only if the temperature is cooled down below 60 degrees Celsius.

Pienaar adds, "Holes that are hotter than 80 degrees are abandoned and not loaded. Due to the uncontrolled nature of these underground fires, holes previously cool or those cooled below 60 degrees and loaded with explosives can suddenly be subjected to heat again, exposing the on bench loading crew to danger. It is AEL’s belief that it is a challenge to formulate an explosive product capable of working effectively above 100 degrees Celsius providing a greater safety margin."

AEL's Research and Development (R&D) team conducted field trials on the bench probing temperatures and pressures in blast holes as deep as 30 metres. The original testing equipment cost R100 000, which was funded by Coaltech Research Association of South Africa. Informative data regarding the nature of hot holes was captured during these experiments and the need for an early warning device became apparent.

AEL's newly developed hot hole detector ensures continuous monitoring of loaded blast holes and provides early warning for changes in the blasting conditions, which assists the blaster before and during operations.

Larry Wilson, AEL's Technical Manager, adds, "AEL has patented the product and is bringing it into the market at an affordable price. AEL has modified the design of the product extensively to make it disposable and highly affordable. It comes with a protective rip tag, which is connected to the battery, and is guaranteed for approximately 8 hours of safe usage. The hot hole detector doesn't guarantee safer blasting, but provides a cost effective tool that is an early warning device for these unpredictable blasting operations.”

Using the hot hole detector, an intermittent alarm goes off once the hole temperature reaches 60 degrees and a second, continuous alarm sounds at 80 degrees, indicating that the hole is no longer safe and the operator should evacuate the bench. The hand-held device has a 30 m temperature probe wire, which is dropped down the hole.

Johan Beukes of Coaltech Research Association of South Africa, comments on the launch of the hot hole detector, “This product certainly addresses the safety threat posed by hot holes in coal mining and will go a long way to reduce the risk to the blasting team. We commend AEL's innovation and drive to improve methods and safety of operating in the coal mining industry.”

More about Designs Unique

Since 1993, Johannesburg-based company Designs Unique cc. has specialised in Data Acquisition and innovative custom electronic instrumentation solutions. The company was a pioneer of PC-based Data Acquisition in South Africa, and has several ‘world’s-first’ electronic designs to its name. Designs Unique has been involved in mining for many years in projects ranging from the Lesotho Highlands Water Project, to the CSIR’s research into methane explosions. They have also been closely involved with AEL for the past 10 years with its product testing, and R&D.

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