Australia's junior explorers - The ASIA Miner

More documents

Recommendations

Info

Paste Thickening we have to take our licks on the first cut and really over-support that r ock. In some instances, we might even be shotcreting on the way in. Once we get that first cut done and backfilled with paste, however , we know what our back integrity is because we already know what that paste strength is.” At Stillwater, the distance to the stope being backfilled can be mor e than 7,000 ft (2.13 km). To move the paste that distance, in 1998 the company installed a KSP 80 pump from Schwing Bioset (Somerset, W isconsin, USA) powered by twin 150-hp (112-kW) electric motors. Marjerison said that, despite the relatively limited role underhand mining plays in Stillwater’s everyday operation—it is used for roughly 10% of the stope backfilling—the pump is the ideal tool for the job. “To move a material with a high solids content that distance would be a challenge for any piece of equipment,” he said. “Granted, in many of the deeper stopes, the material has gravity helping it out. However, that’s not always the case; we’ve pumped some really long distances without much of a vertical drop at all. But the combination of the stoutness of the pump and our efforts to produce a nice consistent product out of the mixer has really paid off. When needed, we’ve been getting steady pour rates in the 90 ton-anhour range and holding to that rate for sixhour, 12-hour, even 18-hour continuous pours. We’ve been very pleased with that level of performance.” 60 | ASIA Miner | July/August 2012 Stillwater’s paste plant operation is monitored at an operator station, and pump operation can be supervised from its own control panel. Designed for Strength The mix design at Stillwater to which Marjerison refers, includes 10% to 12% cement content and a Euco-Fill 31 water -reducing and plasticizing admixture that develops 85 psi (586 kPa) of unconfined compr essive strength (UCS) after seven days. Though lower in strength than paste used at other comparable mines also doing paste backfilling (a result of the large amount of –44 mi- Dewatered and treated mill tailings are processed in a pug mill and transferred through a hopper, visible in the background of the photo, to the Schwing Bioset KSP 80 pump, driven by dual 150-hp motors. cron [–325 mesh] particles in the mill tailings), the company benefits by being able to r educe velocity in the pipelines to about 2.1 ft/sec (0.64 m/sec), less than one-thir d that of the other mines. The mine’s pristine location also puts it literally at the end of the power grid, making outages a distinct possibility, particularly in the harsh Montana winters. T o deal with a service interruption to the Schwing Bioset pump—which could be catastrophic if it occurs in mid-pour—the company maintains a diesel-powered oil field mud pump. “That is our only backup for getting the pipes cleared if we have an outage,” said Fallis. “If the paste hardens in the pipe it is a real nightmare. More importantly, however, if the pour is interrupted for any length of time, because of the risk of cold joints we can’t simply resume pouring. W e’ve had instances where that’s been the case and we’ve had to drill and blast a partially filled stope to start over. It’s not what we like to do.” Prior to backfilling, Stillwater first lays down a bed of anywher e from 1–1.5 ft (30.5–46 cm) of broken rock or prep muck on the floor of the mined stope. Doing so not only of fers something of a buffer from subsequent blasting which will take place below the newlyfilled stope, but also acts as a base in which to drive DYWIDAG r einforcing bolts and plates for added str ength. The addition of wire mesh on the floor and construction of a 7-ft-high (2.1-m) wooden r etaining wall to hold the paste in place, complete the preparation, making the stope ready for backfilling. “There’s no denying that ther e is a lot more work and additional cost to doing underhand mining,” said Fallis. “It might take ten days or so just to get a stope ready for the pour, then the paste has to cure for another seven days after the pour itself. That’s two-plus weeks of lost pr oduction on that stope. However, we are now safely able to get to ore that we couldn’t before—and the key phrase there is ‘safely.’ Stillwater Mining places a tr emendous amount of emphasis on doing things the right way and has an enviable safety record within the industry to show for it. Underhand mining might only be used 10% of the time her e, but we’re happy to be able to make that 10% happen.” LARRY TROJAK is president of Trojak Communications, Ham Lake, Minnesota, USA; Email: trojakcom@gmail.com.
A significant amount of the consulting work performed by Metso’s Process Technology and Innovation group involves Process Integration and Optimization (PIO) studies, which includes investigating the effects of drill and blast design and implementation on downstream processing. Critical to these studies is the ability to track specific or e into and through the plant. To increase the accuracy of this ore tracking, Metso Process Technology and Innovation (PTI) developed a system to track or e using RFID transponders called SmartT ag. Since its commercialization in 2007 SmartTag has been used in the majority of PTI’ s consulting projects and several permanent systems have been installed worldwide. According to PTI, the benefits of using SmartTag include: linking spatial mine data to time-based processing data; increased confidence in ore blending; proactive process changes for known ore types; and accurate measurement of r esidence times in stock piles and bins. Since 2007, there have been significant advancements with RFID technology that have allowed PTI to extend the r each of SmartTag beyond secondary crushing to tertiary crushing and even further downstr eam. This has been achieved by drastically reducing the size of the SmartTags from a diameter of 60 mm to 20 mm. The new smaller RFID tags have been successfully used in several studies. The SmartTag System A SmartTag RFID tag travels thr ough a mine and mineral processing plant in a series of simple steps. Initially, the tag and insertion location is logged using a handheld computer or PDA, then it is inserted into the ore (e.g., into a blasthole). The tag travels with the ore through digging, transport and pr ocessing before being detected at specific locations on conveyor belts, when the time and specific tag is recorded. The RFID tag data is then loaded into a database and analyzed as required. To achieve this, the SmartTag system requires five main components: The first is a PDA, which allows the initial RFID tag insertion process to become more efficient and accurate. Each RFID tag is added to the database using one of thr ee options—it is associated with a GPS coor dinate; it is associated with a predefined point (such as a blasthole); or it is associated with a new point, which can be accurately located later. Grinding Mills SmartTag Looking at the Next Generation, and Beyond Metso reports current developments and the future direction of its RFID-based ore tracking system The SmartTag system utilizes radio frequency identification (RFID) tags and detectors to track ores as they flow from the blast to the downstream processes and beyond. The insertion point of each SmartTag is registered using a PDA. Currently, the system does not allow for high-precision GPS but it can locate the nearest point in a series of predefined points, such as blastholes, and allow the user to associate RFID tags with these points. The next component in the system, the antenna, is located at the conveyor belts. The antenna both induces a charge on the tag and also receives a transmitted signal back from the tag. The design of the antenna is decided by two parameters, which are its size and its r obustness. The size of the antenna dictates the size and the July/August 2012 | ASIA Miner | 61
Page 1:
July/August 2012 | Volume 9 | Issue
Page 4:
From The Editor Philippines mining
Page 7 and 8:
AN interesting recent development f
Page 9 and 10:
Intex is involved in the provision
Page 12 and 13: Philippines 10 | ASIA Miner |July/A
Page 14 and 15: Philippines Policy review provides
Page 16 and 17: Philippines Taysan PFS delivers pos
Page 18: China Drilling extends main zone at
Page 22: China Drilling at Linc Energy’s C
Page 26: China Improved zinc outlook for Chi
Page 29 and 30: THE completion of data logging from
Page 31 and 32: TWO Chinese companies have signed c
Page 34 and 35: Australia Spotted Quoll exceeds pro
Page 36 and 37: Australia Tasman secures Rio Tinto
Page 38 and 39: Papau New Guinea Maiden Mambare res
Page 40 and 41: Central Asia Premier Gold starts Ch
Page 42 and 43: Malaysia Sokor gold resources incre
Page 45 and 46: First sales into domestic market NS
Page 47 and 48: LIFE OF MINE 10-12 July, Brisbane,
Page 49 and 50: provide reasonably continuous news
Page 51 and 52: MAIDEN RESOURCE FOR MOOLYELLA PROJE
Page 53 and 54: KAOLIN EXPLORATION TARGET SET AT PO
Page 56 and 57: Australian Junior Explorers PRINCES
Page 58 and 59: Australian Junior Explorers CORE EX
Page 61: Prior to the early 1980s, if poor s
Page 65 and 66: Secondary Crushing Circuit As part
Page 68 and 69: Supplier News Aggreko powers up Mar
Page 70 and 71: Supplier News Camp management compa
Page 72 and 73: Subscribe now to the ASIA Miner mag
Page 74: Exploration Spotlight Survey identi
show all

Australia's junior explorers - The ASIA Miner

Create successful ePaper yourself

Delete template?

Save as template?