While trucks are designed to carry weight, they are used to move a volume of dirt. This difference in function is natural.
Trucks are machines designed to withstand mechanical load, thus maintenance engineers need to know how much weight the vehicle will carry.
The utilisation of each truck can be improved by maximising the volume of dirt that the tray can carry without overloading the truck.
In the past, the volume carried by the truck has been inferred from a volumetric survey of the mine (divided by the number of loads) or a weight survey of each truck (bulk density of the material divided by weight).
Neither technique actually measures the load in the tray and does not take into account changes in packing, or swelling, that the load undergoes in the tray.
With the development of laser scanning technology it is now possible to measure the in-situ volume of each load directly, according to research scientist Chad Hargrave of CSIRO Exploration and Mining based at the Queensland Centre for Advanced Technologies (QCAT).
“The laser scanning technology is a fairly straightforward kind of idea. It’s using a laser, much like a laser pointer, to give you the distance to a wall or a series of objects in a room so that you can build up an image of that room or area by scanning it,” Hargrave told Australian Mining.
“This sort of information when combined with an automation system allows us to do things like navigate a robot, or scan an area like a truck to determine the size of the load within that truck.”
Queensland company Transcale recognised the importance of volume optimisation and released the highly successful “Trayscan” a volumetric and density weighing system developed in with CSIRO. This system is being utilised by mine specific truck body companies and mine operations to improve design and operational efficiencies.
The Trayscan system consists of two laser measurement units that scan the truck’s trays as they pass beneath. Used in conjunction with Transcale Scale Systems, both volume and weight information is available, giving accurate and real time bulk material density, a first for mine operators and truck body designers.
The Trayscan system is available for both rental or outright purchase and Transcale provides full training or can conduct the weight & density studies where required.
Current product development rollouts will include the ability to conduct volumetric scanning studies on equipment such as coal haulers, side tippers, belly dumpers, rail rolling stock, loader and shovel buckets, the list goes on and the possibilities are endless.
“Trayscan is probably the most mature product that we’ve developed in the laser scanning area,” Hargrave said.
Carry back project
A sponsored project at the CSIRO’s QCAT and employing laser technology to identify coal left in rail wagons “sticky coal” can not only reduce contamination of coal types it can also result in big savings, according to Hargrave.
The application was developed from previous experiences the CSIRO had in using laser scanners.
“The basic idea is to identify the coal that gets left in coal wagons as they leave the port after dumping their load,” Hargrave said.
“This phenomenon known as sticky coal is a real problem because the coal stays in the wagons, gets carried back to the mine and you can get situations of cross-contamination of different coal types of wagons that aren’t completely loaded – and if there’s sufficient carry back in a wagon then the load is rejected.
Losses from carry back certainly add up. Estimates vary in terms of accurate figures, but about 10,000 tonnes a year per mine is a fairly conservative figure of the sort of losses. “If we can identify where the coal is in the wagon, clean it automatically using the information from a scanner and then send the wagons back to the mines clean we’ll save everybody a lot of money and heartache,” Hargrave said.