![\"Assembling](\"https:\/\/www.coralynne.co.za\/blog\/wp-content\/uploads\/2023\/08\/ORE-PASS-PIC-10-scaled.jpg\")
<\/a><\/a><\/a><\/a><\/a><\/a><\/a><\/a><\/a>\u201cThe tube is essentially a sacrificial shutter that can be lowered down the ore pass,\u201d he explains. \u201cThis can be done without anyone having to climb down the ore pass, so using this methodology has a significant safety advantage.\u201d<\/p>\n\n\n\n
This is an important advance on the traditional method which requires people and material to enter the system every day \u2013 leading to relatively high exposure to hazardous areas. In addition to being labour intensive, it also requires a rock engineer to inspect regularly and frequently \u2013 to give recommendations and approve the installed support.<\/p>\n\n\n\n
At the heart of the tube-and-fill method are reinforced rings of special fibreglass, with varying diameters up to a maximum of 3.5 m. The use of relatively light fibreglass \u2013 instead of much heavier material like steel \u2013 makes it possible to easily transport the tube segments and to assemble them underground. With a tube segment weighing just 80 kg, this means that a tube for a 60 m ore pass will weigh only around 5 t.<\/p>\n\n\n\n
At the same time, the reinforced design enables the fibreglass to withstand considerable hydrostatic pressure from the concrete being pumped on the outside. The concrete mix \u2013 designed in collaboration with concrete and admixture producers \u2013 is able to achieve final UCS strengths of up to 70 MPa.<\/p>\n\n\n\n
\u201cWhen replacing the original rock into which an ore pass has been created, we attempt to get our linings as close as possible to that rock strength,\u201d he says. \u201cThis specialised concrete mix design allows us to achieve close to 50% of the original rock strength.\u201d<\/p>\n\n\n\n
He notes that the mass fill product also creates a more abrasive lining when compared to the shotcrete sprayed lining.<\/p>\n\n\n\n
Fanie van Emmenes, Project Manager Mining Services at Murray & Roberts Cementation highlights that the early tube-and-fill installations are proving more durable than the traditional shotcreting approach. This, points out Van Emmenes, also demonstrates that it is more cost effective over the life of the mine.<\/p>\n\n\n\n
Murray & Roberts Cementation considers a range of options for customers when proposing solutions for underground rehabilitation. Another method that is used for ore pass rehabilitation is to lower a specialised robotic shotcrete unit into the ore pass, where it applies the concrete to the sidewall without the need for personnel to enter this hazardous zone. One of the limitations, however, is that the level of scaling cannot be too advanced, and this method is used for preconditioning of the ore passes immediately after being developed<\/p>\n\n\n\n
The mass fill and redrilling of the ore pass is yet another option. Here, the whole ore pass is filled with low-strength concrete, and a raisebore machine redrills through the mass fill to create a new ore pass system. Irrespective of the method, he says, safety remains the priority \u2013 with Murray & Roberts Cementation\u2019s comprehensive and proven protocols earning the company an enviable safety record.<\/p>\n\n\n\n
\u201cThis includes proper ventilation systems, monitoring for hazardous gases, personal protective equipment (PPE), and emergency response plans,\u201d he says. \u201cWe also ensure adequate training and supervision, which are essential to mitigate safety risks.\u201d Oosthuysen concludes that the success of the tube-and-fill method would make it the company\u2019s first choice for most applications. He argues that this approach is likely to see increased uptake as the durability of the initial installations become well known.<\/p>\n","protected":false},"excerpt":{"rendered":"
If the lifeblood of underground mines is the ore that must find its way to surface, then it is no exaggeration to describe the ore passes as the mines\u2019 arteries \u2013 and the innovative tube-and-fill method of rehabilitating ore passes from Murray & Roberts Cementation is proving itself safer and more durable. When the ground … Continue reading ORE PASS REHAB TECHNOLOGY ADVANCES TO KEEP MINES PRODUCING<\/span>