Jennmar sent 2.4-metre, high-tensile, steel roof bolts, made from OneSteel HSAC840 grade high-tensile steel rebar, to the 2.5 million tonne per annum mine.

Jennmar Australia managing director Peter Roberts said the bolts, manufactured at the company’s Smeaton Grange plant in New South Wales, were selected by the Chinese mine for their quality and the inherent safety benefits.

“Ground support products manufactured from steel require specific physical characteristics and chemical compositions to perform the task they were designed to do, which is to bear loads in underground mines,” Roberts said.

“The relationship between steel quality and safety lies in the reduction of roof falls.”

He said prematurely failed bolts from stress corrosion cracking decreased the effective support in the mine roof by reducing the working support pattern, while broken bolts could lead to the ground stresses overcoming the strength of the reinforced roof, leading to a roof fall.

“Roof falls have been known to cause injuries and fatalities along with blocking emergency exits within a mine. Major roof falls cost a lot of money for rectification but the lost production when falls stop mining can lead to far greater losses.

“The essential criteria in selecting the steel for use as ground support is to know that the steel’s physical characteristics and chemical composition have been properly tested under the conditions in which it will be used and that these characteristics and chemistry are consistent from one batch of steel to the next.”

Roberts said Jennmar Australia would continue to seek out opportunities in China.