【文章內(nèi)容簡(jiǎn)介】 ith the sand to from a sort of paste in the hole. The paste expands to fill up the section area of the hole and dries quickly into a plug that seals tightly the hole. The propellant charge is initiated by an AEL made electrical/bustion igniter named ―sure start‖. It is basically an electrical fusehead that is made to set off normal igniter cord for bustion initiation. Safex field trials conducted at a chrome mine as well as at 第 6 頁(yè) a platinum mine respectively in the Eastern and Western Bushveld did not yield conclusive evidence to warrant remendation of the system for routine mining. As in any Ramp。D, the product is being improved (back to the drawing board) for further attempts. Salient features of nonexplosive rock breaking The learning curve of nonexplosive rock breaking technologies has been steep since they are meant to pete with settled high explosives that have built the mining industry wealth and reputation over many is against this background and the general conservatism that riddles the industry that the new ers have to battle .Whatever the standoff will be, it is worth highlighting the following salient features of these new technologies. Motivational edge Full day work in stops with shift relief underground can be continuous mining and its several advantages discussed below ceases to be a dream of the industry but a reality applicable for both primary and secondary, surface and underground mining. Legal advantage Nonexplosive mining offers tremendous advantages in that countless legal implications would fall through and would no longer haunt the industry. By virtue of using safetohandle energetic materials, . propellant instead of explosives, the perception of mining being the peacetimes most killing industry would fade away. Technical argument Nonexplosive rock breaking technologies are being introduced at the time when the mining industry is very environmental conscientious. Energetic products are designed with health and safety concerns in mind. Components are userfriendly and life entertaining therefore no special dispositions should be required in their handling and transported as preassembled units ready for charging in the hole or can be assembled on site shortly before use. The system guarantees costeffective mining, which may e in as an 第 7 頁(yè) oxygen line to deep and marginal mines threatened with closure. This would boost the industry and contribute to ensuring its global petitiveness. The technology is set to revolutionise rock breaking in mining. Short of replacing high explosives this technology would pete favourably and capture a sensible portion of the mercial explosives market. Its edge over explosives mining is embedded in the gentleness of the propellant bustion reaction. The slow release of equally huge energy like that from explosives enable more useful work to be done in the rock, . the longer the gas containment in drilled holes the better the breaking and the lesser the fine generation (crushing). Economic benefits Nonexplosive rock breaking is expected to offer the following advantage: ★ Safety aspects: ○ Little or no harmful nitrous fumes are created, ○ Little or no dust created when the blast takes place, ○ Little or no fatal injury from accidental detonation, ○ Due to lower concussion, fewer fractures in the solid rock surrounding the blasted area, which implies less rockfalls. (Great reduction in hanging wall fracturing). ○ Temporary supports are not blasted out leading to lower support costs. ○ Number constraints and current regulations applicable to dangerous mercial explosives areavoided. ○ Working time restraints in stopes are greatly reduced. ○ Few misfires. Ever if they occur one can safely drill through them as the propellant would be rendered harmless on contact with the water. ★ Productivity aspects: ○ Production process to be continuous, . no need for lengthy reentry periods that underpins current inefficient work schedule of one blast per day. ○ High monthly calls. A double advance per day in a panel is achievable. A 第 8 頁(yè) slight increase in overheads (labor force and drilled meters ) that would be pensated by the extra advance production. ○ Possibility of multiple breakings(3 to 4 times in 24 hours, provided that cleaning technology follows suite). ○ Optimum utilization of the labor force. Crews relieve one another on the face. ○ Concentration of mining (reduced ore traming distances to impact on transport cost) ○ In the mining industry, the strongest production criteria is to get as many effective blasts per face per month as possible – This system offers a potential for 200％ more blasts per month. Operational benefis → The product lends itself to increased panel length, in excess of 40 metres, subject to adapting the rock cleaning and disposal methods. It is noted that the current conventional operations (explosives) are limited to ＋ /－ 20m. → Vastly improved mining cycles. → Stoping width control improved thus less contamination of ore, optimisation of transported material underground, cost saving at milling. → Flexibility as mining cycles, shift cycles and stope layout can be varied on site to the discretion of the miner. → Reduction in waste devel