Mining support systems manufacturer Mine Support Products (MSP) is working on an improved version of its Rocnet modular safety net that will offer better corrosion resistance for longer-term installations that could evolve into a new product, says MSP technical manager Christiaan Nissen.
Constructed from galvanised steel cable with an added secondary protection layer, the 1.5 m x 1.5 m Rocnet, with 150 mm apertures, is installed between permanent or temporary support as aerial coverage to protect miners from fall of ground.
The Rocnet can be suspended from permanent support elongates, roof bolts or temporary mechanical or hydraulic jacks and has been in use across gold mining company Harmony Gold’s local operations since its launched in 2020.
“Orders from Harmony are ongoing as the product is used in the mine stope area. Therefore, as mining progresses, Rocnets are permanently installed,” states Nissen.
The product won the innovation for safer, healthier mining category in April at this year’s Mining Equipment Manufacturers of South Africa’s Innovation Awards.
MSP generates its innovative support solutions, including a range of underground roof supports and accessories, through its research and development programme, Nissen highlights.
“This involves regularly engaging our customers. Before developing the Rocnet, we identified some areas where we could improve on similar products in the market.”
For example, the patented zero overlap modular construction of the Rocnet system results in a 20% reduction in cost, as it eliminates the 300 mm overlap of standard netting.
The Rocnet is also easy to transport as it is supplied in separate bags that are effortless to handle, with logistics further simplified as there is only one stock item. Uncomplicated to install and tension, as there are no issues associated with the handling of big nets, the Rocnet can also be extended in any direction using Rocnet connectors. Its modular design further allows for the replacement of damaged sections rather than the whole net.
During the development of the Rocnet, MSP constructed a test frame worth about R500 000, equipped with instrumentation to measure forces on and displacement of the net.
“This was necessary to ensure that the net complies with the mining standard, which requires the net to withstand the force of 450 kg falling from a height of 100 mm. The test frame can test nets of up to 3 m x 3 m. The frame is also designed so that we could install support units, such as temporary support, permanent elongate support or rocbolts, and suspend the net from the support to do a full system test as would be used underground.”
However, designing the product is only half the effort, the other half is finding the most effective production methods to ensure consistent quality at an economical cost to supply a quality product at an affordable price, explains Nissen.
Manufactured at MSP’s factory in Duncanville, Vereeniging, Gauteng, the Rocnet comprises 60% local content, with only the cable used in its construction sourced internationally, owing to a lack of thin-gauge cable manufacturers in South Africa.
“The net is produced by weaving the cable manually on purpose-built frames, whereafter the cable intersections are crimped together and the perimeter cable and Rocnet connectors are added,” states Nissen.
MSP can produce about 200 nets a day or 10 000 m2 of netting a month and carries stock for its existing customers, producing special net sizes on request.
“If demand increases, we will increase our production capacity accordingly,” Nissen confirms, stating that while MSP is not exporting the Rocnet, the company is engaging customers in the US and Australia.