The 33 San Jose coppergold miners could see daylight very soon

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first_imgEvents, thankfully, have overtaken the Leader in International Mining October that is currently mailing to readers. We hope to be able to report tomorrow that the men are being pulled from underground – considerably sooner than anyone expected, until very recently. Casing of the top 96 m of the Plan B hole is being completed and it is hoped that hoisting of the men up this rescue shaft will start tomorrow. News footage yesterday showed the Plan B Schramm T-130 XD drill, equipped with a Low Profile DTH drill, being driven away from the shaft, job done. It is always a risk writing about a relatively fast moving news situation in a monthly publication. In this case, I am very happy to point out the errors in the Leader. However, the main point about that Leader was to explain that three different holes using three different technologies were being drill to save these men – Plans A, B and C – a fact that was not clear from much of the general media reporting. The technology used to drill the rescue shafts is truly worldclass. The Schramm drill put its hole into the underground workshop on Level 135, a 630 m long hole. A 130 mm diameter pilot was opened out to 660 mm in diameter.Plan A’s Strata 950 raise drilling machine, built in Western Australia, is owned by Murray & Roberts of South Africa. This was developed for downhole pilot drilling at sizes up to 400 mm in diameter either byconventional means or using Mincon’s Rotary Vertical Drilling System (RVDS) tool that continuously self surveys and corrects itself to the vertical. It drilled an initial pilot hole to a diameter of 0.375 m which is being reamed out to excavate a 0.72 m diameter access hole from surface to the location of the trapped miners. This diameter was chosen because a larger diameter would take commensurately longer to drill.Precision Drilling is executing Plan C using an oil industry drill, which only started drilling in late September. The plan for this was to drill a 600 mm hole (no pilot hole required) directly into the rampat level 150 – this will be a hole length of 700 m at 85°, slightly off vertical.In late September, a Chilean Navy technical team delivered the first of three 540 mm diameter, 2.5 m tall cylindrical pods with a reinforced roof to pull the miners up the completed rescue shaft. It is equippedwith a video link to surface, an oxygen supply, lighting system and an escape hatch and safety device so the passenger can lower himself back should such an escape be necessary. It will be hoisted using guide wheels. We look forward to seeing those rescue cages do their job successfully tomorrow.last_img

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