HIGH PROFILE
First line of defence
Q With a lot of brownfield mine development during the downturn, mines have been steepening walls and doing more pushbacks to get more out of existing sites. Have you seen a corresponding increase in interest in your technology?
A Steepening of the walls has nothing to do with more nets, the design of the wall angle of the open pit mine can only be adapted to a point where the mine is still stable. Our solutions are implemented at specific spots, for example to protect infrastructure, ramps or equipment, mainly against rockfall caused by external causes like weather or similar. There are one or two mines we are aware of that are using our systems in a proactive way and steepening the walls, but we could not say at all that this is a trend
Q Is a lot of demand for your technology still reactive ie once a rockfall has happened and to safeguard against future falls?
A Since a rockfall is by definition not a problem of the geomechanics in the sense that the design of the mine in the first place, has to be done in a
Geobrugg drapes are one option for securing pits no longer in operation
Protecting miners and mining assets against rockfall and failures is crucial and physical barriers in the form of fencing and mesh represents the last line of defence. Paul Moore spoke to several global managers at Geobrugg about its surface and underground solutions
way that rockfalls do not occur, additional measures to protect the installations, workers and equipment are in general as much as 99 % reactive. And often the mines are asked to do something to protect against rockfalls by centralised mining engineering departments or even external insurance companies
Q Are you also seeing more demand for your solutions to safeguard against failures not on walls but on the slopes of large waste stockpiles? Does this require a different approach?
A It would be a great idea but to take Chile as an example, in the whole history of its mining industry, only once has a waste rock stockpile failed, and in remote areas where mines are located often it is relatively easy to find the space to place waste material. On the other hand in the most mountainous as well as in urban areas our solutions are considered from time to time as space is limited. Anchoring in loose material such as waste stockpiles requires very large anchors hence the drilling cost can be the killer criteria. But we are increasingly seeing interest for our erosion control mat with the internal wire mesh GREENAX ®, to help to establish vegetation on tailings piles
Q With a lot of development of laser and radar in-pit scanning from companies like Groundprobe, Reutech, IDS and others, pit walls are monitored more closely than ever before, but solutions from companies like Geobrugg still represent the first line of defence. Is there any direct coordination, ie mines will use the radar to pinpoint areas of small movement, then concentrate Geobrugg technology there?
Increasingly, barriers are used to protect physical fixed assets such as processing plants that are adjacent to old pit areas
A Absolutely! This is the goal … to pinpoint areas where rockfalls or slope failures are likely, and then provide cost-effective and quickly deployable mitigation measures. We are seeing this become much more common, and this is an important trend for the future. However, we think this only works for large scale failures, and not for smaller to mid-size rockfalls. It seems the mines and the suppliers of radars have learned and understood that one method is to monitor with radars and lasers, and the other is to mitigate with drape mesh and rockfall barriers
Q Can you explain how SPIDER ® and MINAX ® technology is specifically used in different open pit mine situations / applications and when drapes are used versus barriers?
A There are no general specifications as every minesite and mining situation is different. The design depends mainly on the ambient conditions such as the expected rock sizes, and the available space to build a barrier allowing its nets to flex out or deflect. The question is also asked whether it is acceptable that the rocks move freely downslope under the mesh. We then advise the client, whether that be a mine or consultant, on what type of mesh / drape system or barrier system we would suggest, but the decision in the end is with the client
Q How mobile are these technologies ie how easy is it to move barriers to different parts of a pit without the mine incurring a lot of extra cost?
A We have deployed multiple versions of mobile barriers. As long as it is known from the outset that a barrier will need to be relocated, then we can present a number of options ranging from a requirement for partial disassembly to versions with virtually no disassembly. But each particular case, site conditions, frequency of relocation, equipment availability, etc will dictate which version is most appropriate. The drilling work, dismantling and making the new installation is actually very simple if the current system( height, energy, length of barrier) will also address the problem at the new location. However if the onsite conditions are difficult even the“ mobile” barriers can be hard to move around and might not represent the ideal solution
Q Are you also finding that mines are applying this sort of protection more to key buildings such as equipment workshops, crushing stations, main conveyors etc that are in the pit?
A We 100 % agree, and this is one of our niches in
14 International Mining | NOVEMBER 2017