【正文】 detonations and management of misfires. Indeed, the SA industry has managed to scale down and manage these hazards relatively well, given the risks involved and the statistics of accidents recorded to date. However since human life should be rightly valued, the national expectance is zero accidents at any cost. Thus the reason for this quest by all concerned parties is to work towards a safer mining system that ensures sustainable mining to well take the industry into the future. Cunningham (2020) highlights the major shorting of conventional high explosive mining. He observes that underground ore production is limited by disruption of operations imposed by mining legislation associated with blasting. Full shift continuous operations are impossible owing to the withdrawal time required. Workers vacate the workings shortly before and during blasting. There is a working prescribed reentry period that ought to be observed while blast fumes, noxious gas and dust settle. Nonexplosive rock breaking systems claim the advantage of no concern with such huge loss of working time. Several systems have been developed and put forward to the industry. Despite their subtle differences warranting their individual patents, they all have in mon the following claimed features: 第 3 頁 Low toxic fumes, enabling immediate reentry and continuous mining. 2 NONEXPLOSIVE ROCK BREAKING SA mining industry has one of the highest rate of mining casualties in the world mainly due to the great depth of mining (2 to 3 kilometres under the ground, ever more ). The unique geotechnical rock conditions are generally characterized by heavily fractured rock in stops and haulages as well as a highly sesmic active ground explosive mining does add to the ground conditions described above another safety concern that is born out of the enormous energy generated by blasting,which is often poorly accounted portion of blast energy remains locked up in hanging walls of mining prior warning such energy es down often triggering bloody falls of ground that frenquently result in accidents varying in intensity from small cuts to multiple fatalities .Tabulated below are statistics of accidents recorded in SA mines for a period of nine years from 1990 to 1999. Table 1. Statisics of high explosive related accidents in SA mines. SA mines accident statistics from 9099 Total injured Total disabled Total killed Total accidents Fall of ground Misfires Exposure to blasting fumes Other explosive related accidents 17286 124 — — 99 3 0 — 1547 29 0 — 18229 97 417 180 Table 1(above)depicts the horrendous reality of SA mining industry that may be summed up in the following:Every single year high explosives in the industry cause death to over one hundred and fifty people,injure over one thousand eight hundred people and inflic permanent disability to some ten is the 第 4 頁 scenario that nonexplosive rock breaking technologies intend redressing beside the added advantage of increased production rates. Path and underlying principles of nonexplosive rock breaking systems Impact mining In the early niies, the mining industry witnessed an eagered search for paradigm shift in mining underpinning intensive reaserch for safer and more productive rock breaking technology for narrow reef mining. The trend was fuelled by the need for substituting the inherent disadvantages of conventional labour intensive method of drilling holes and detonating violently chemicals into the rock to extract portions of orebodies. In already difficult ergonomical conditions, . deep mine heat load, highly stressed rock and confined spaces, explosions are always perceived to sensibly obscure the positive contribution of the industry. Financial Mail, September 1993 reports that impact mining considered revolutionizing mining since the eighties. Intitial exploratory trials were carried out at Doornfontein mine. Number of mines which followed suite to pioneer the process, . Kloof Mine, claimed an upper hand for the technology as it yielded lower working costs and high production rations. However the technology was not further developed owing to its lack of flexibility associated with high level of mechanisation. So despite being nonexplosive impact mining was seen as part of drive towards mechanizedmining in deep mines, which falls outside the scope of this paper. NXCO’s Nonex technology Nonex technology is also based on the use of a propellant cartridged in a drilled hole and stemmed by aggregates (stemming column) to fill the blasthole. This system claims to have substantially improved the geometry and nature of the stemming material used to confine the propellant in the hole therefore resulting in a much better inhole confinement of gas energies. In addition Nonex cartridges are 100％ nonexplosive and totally inert. Ignition is obtained by low voltage electric power a part from which any other means would pletely fail to set off the cartridge, hence its extreme safety in handling and transportation. The Nonex cartridge system works on the principle of a balloon to seal off the hole and avoid premature gas escape during the pressure buildup. This is a 第 5 頁 considerable advantage as escaping