A South African safety product has saved a Canadian mining company tens of thousands of dollars in potential downtime and damaged equipment. When a conveyor belt failed at a large potash mine in the last week of April 2014, it was a Technogrid system developed and manufactured in South Africa by Horne that immediately caught the multi-ton counterweight and prevented its fall.
Counterweights are needed to maintain belt tension in conveyors. Attached to the belt and suspended below it, the counterweight has the potential to damage equipment and structures should the belt fail. The Technogrid is designed to prevent such a fall, and the mine concerned has 40 of them fitted beneath belt counterweights throughout the facility.
Technogrids are also fitted to conveyor belt systems throughout the mining company’s other potash mines in Canada. They are suspended vertically next to each counterweight and connected by a catch frame positioned just below the lowest point of normal vertical movement. The tops of the Technogrids are anchored to the conveyor structure. Upon impact, the Technogrids stop the fall of the counterweight, absorbing all the impact energy and retaining the counterweight on the catch frame until it can be reinstalled on the repaired conveyor belt. The Technogrids are then replaced.
Horne developed the Technogrid several decades ago to absorb the kinetic energy of a moving object by deforming a metal grid of known design and characteristics through a stroke deformation of predicted value. The device comprises a series of multi-bar units connected in a staggered grid shape which, upon impact, yield and deform under double-curvature bending. It is the yielding of the bars that allows the unit to open up and stroke, and it is the strain hardening of the material that absorbs the impact energy.
Technogrids can be designed for specific energy absorption requirements, allowing safe deceleration and the control of very high end-forces. Optimum unit configuration can be achieved by combining grids in series or parallel.