Q. What is Nxburst™ ? A. The Technology is based on a non-detonating propellant compound enclosed in a cartridge, which reacts very quickly when ignited to produce high volumes of harmless gas, mainly consisting of nitrogen, carbon dioxide and steam. When the cartridge is sealed in a drill hole, the high pressure gas generated by the ignition of the propellant enters into the micro-fractures created from the percussive drilling process and in to the natural fractures and planes of weakness of the rock, expanding the fractures and propagating cracks towards the nearest free face of the rock. The number of cracks propagated is related to the maximum pressure and peak pressure rate achieved by the expanding gasses within the drill hole. The gas pressure, within the drill hole and propagated cracks, then causes the fractured rocks to heave a part, producing a shearing of the rock often called splitting. Q. What is Nxburst™ used for ? A. The Nxburst™ rock breaking technology was developed to solve problems associated with specialist excavations and rock breaking insensitive conditions. The collateral damage associated with excavations using explosives in poor rock conditions or in blast sensitive areas often creates a larger problem than the original explosive solution set out to address. Problems of blast damage in highly jointed rock and collateral damage to sensitive installations and infrastructure have persisted in the industry for many years due mainly to the absence of credible alternative methods to address such situations. Nonex™ offers the industry a solution, which allows a controlled approach to excavation in these difficult situations without the vestiges of damage associated with traditional methods of rock breaking using explosives. The Nxburst™ rock breaking method, developed by NXCO Mining Technologies, has recently been applied to several applications in a wide variety of rock conditions. The Nxburst™ technology allows a tailored rock breaking (“TRB”) approach where by energy can be applied more efficiently to break and dislodge the rock in a controlled fashion, which can be optimally adapted to suit the rock breaking requirements of any particular situation in all types of rock conditions. Q. What are the advantages of using Nxburst™? A. Nxburst™ is environmentally sensitive Minimal fly rock (< 10m) Minimal vibration Lower noise and overpressure levels than conventional explosives Negligible noxious gasses Similar yields to small-diameter conventional blasting can be achieved with Nxburst™ using smaller charge weights. Primary rock breaking yields typically around 1m3, in hard in-situ rock pavements, can be achieved using a 100g Nxburst™ cartridge. Significantly greater secondary-breaking yields are produced when breaking boulders rather than in- situ rock Only localised clearance of personnel is required with Nxburst™. Production is optimised as no downtime to loading and hauling equipment is experienced due to site evacuation during initiation. Nxburst™ is safer to transport, store and use than conventional explosives. Nxburst™ can be used with low capital, lightweight equipment – One small hand-held drill rig is all that is needed to drill the hole. Q. What are the Nxburst™ cartridge sizes? A. Nxburst™ cartridges come in a range of diameters and charge weights: 13mm Nxburst Cartridge RockPoppersareusedforbreakingsmallbouldersupto2cubicm etersinsize.Applicationsincludecrusher blockages, oversize boulders, scale removal in tanks and small demolition jobs. Available in 5 and 10 gram charge weights Electric Initiation Only 28mm Nxburst Cartridge 28mm cartridges are used for boulder breaking, armoured stone splitting, medium size concrete demolition, dimension stone quarrying, swimming pool excavations and other in situ rock-breaking. 28mm cartridge requires a 32-34mm diameter hole which can be drilled with a hand held pneumatic drill using a185 cubic feet per minute (cfm) compressor. Available in 20, 40, 60, 80, 100 and 120 gram charge weights Electric Initiation Only 34mm Nxburst Cartridge 34mm cartridges are used for deep level underground mining operations, concrete demolition, tunnel and shaft enlargement, trenching and other in situ rock excavations. 34mm cartridge requires a 38-42mm diameter hole which can be drilled with a hand held pneumatic drill using a 185+ cfm compressor or by a small hydraulic rig. Available in 20, 40, 60, 80, 100, 120, 140, 180 and 250 gram charge weights Electric and Non-Electric Initiation 42mm Nxburst Cartridge Used for concrete demolition, tunnel and shaft enlargement, trenching and other large in situ rock excavations. 42mm cartridge requires a 45-51mm diameter hole which can be drilled with a hand held pneumatic drill using a 185+ cfm compressor or by a small hydraulic rig. Available in 60,80,120,180 and 240 gram charge weights Electric and Non-Electric Initiation 60mm Nxburst Cartridge 60mm cartridges can be used for large scale rock excavations, hard rock trenching, foundation excavation and other sensitive civil rock & concrete breaking applications. It is used for concrete demolition, tunnel and shaft enlargement, trenching and other in situ excavations. 60mm cartridge requires a 64-76mm diameter hole which can be drilled with a small hydraulic or pneumatic drilling rig. Available in 300 and 500 gram charge weights Electric and Non-Electric Initiation Q. Does Nxburst™ detonate? A. One of the most salient features distinguishing Nxburst™ from high explosives is that explosives detonate whilst the propellant used in a Nxburst™ cartridge deflagrates. Deflagrations are thermally initiated reactions propagating at subsonic speeds that proceed radially outwards in all directions through the energetic material, away from the ignition source. The maximum pressure developed by deflagration is dependent on the energetic materials involved; their geometry; and the strength (failurepressure) of the vessel or structure confining the materials. Deflagration speeds of propellants are in the order of 200 to1000 metres per second producing pressures reaching 1000 Mpa, which are developed in thousandths of a second. High explosives are defined as materials intended to function by detonation (2). The reaction speeds of detonation are higher than the speed of sound in the explosive material. The speed of sound through a material is dependent on the density of the material; the higher the density, the higher the speed of sound will be through it. A reaction speed of 1000 metres per second is set as the minimum speed that distinguishes detonations from deflagrations (2). Detonation speeds are in the order of 1000 to10000 metres per second producing pressures from 1500 to 15000 Mpa which are developed in millionths of a second. Q. What are the transport and storage requirements for Nxburst™ A. The Nxburst™ cartridge is classified according to the United Nations Classification of Hazardous Substances as a Division 1.4S hazardous substance. The UN classification system is used by most countries of the world to classify hazardous products according to the danger that each of the products poses whilst in storage and transport. The1.4S classification that applies to Nxburst™ cartridges is the same classification as that applied to small arms ammunition. The Nxburst™ cartridge was tested by a UN accredited testing agency and subsequently classified under UN1.4S as a “Cartridge Power Device”. The UN 1.4S classification is defined as follows: “Articles and substances that present no significant hazard ”This division comprises articles and substances, which present only a small hazard in the event of ignition or initiation during transport. The effects are largely confined to the package and no projection of fragments of appreciable size or range is to be expected. Articles and substances in this Division are placed in Compatibility Group S when they are so packaged or designed that any hazardous effects arising from accidental ignition are confined within the package unless the package has been degraded by fire, in which case all blast or projection effects are limited to the extent that they do not significantly hinder fire-fighting or other emergency response efforts in the immediate vicinity of the package”. The 1.4S classification described above is awarded to only those products that attain the classification by undergoing a series of strenuous testing under the supervision of the SABS. The successful outcome of the testing requires that the product is incapable of an explosion whilst in its packaged state even if it is accidentally ignited or otherwise initiated by external means. Q. What are the environmental benefits of Nxburst™? A. Environmental Benefits of Nxburst™ rock splitting produces low vibration resulting in significantly reduced damage to surrounding rock and infrastructure; minimal fly rock resulting in minimal scatter of blasted rock; low over pressures resulting in minimal concussion effects; and minimal fumes and dust allowing operations to be carried out continuously without the need to evacuate the mine as is the case with conventional explosives blasting. These benefits are explained below. Q. What vibration levels are produced by Nxburst™ rockbreaking? A. When an in situ rock splits / breaks up on tensile, the movement of rock causes minimal vibrations to its environment. Should the rock which breaks be attached to a wall (without a foundation for example,) the movements created by breaking are likely to impact upon the wall, which will probably crack. However these are mechanically induced vibrations, not vibrations induced by a shock wave initiated by detonation. The physics has not been studied, however, the application of vibration monitors close to the Nxburst initiation proves that these minimal to low vibrations are a fact. Q. Do the same low vibrations impact underwater? A. Yes, divers only need to withdraw about 20 metres, because no shock wave is produced; as a result there is minimal damage done under the water, fish are safe and the environment protected Q. Is Nxburst™ an explosive? A. The Nxburst™ cartridge is classified as a 1.4S product under the United Nations hazardous substances classification, in the same category as small arms ammunition. This classification is given to products that do not explode when ignited in their original packaged state and as such the classification defines Nxburst™ as a non- explosive product for transport and storage purposes. An explosion is basically any rapid expansion of matter into a volume much larger than the original. The rapid expansion of a gas from the bursting of a latex balloon can be classed, according to some definitions, as an explosion. Equally, the bursting of a pneumatic tyre or the rupturing of a pressurised gastank can be termed as explosive events. As mining engineers we are more attuned to the term explosion being applied to the exothermic chemical reaction caused by the initiation of an explosive. In general, the term explosive is used to describe a material that can undergo an exothermic chemical reaction resulting in a rapid expansion of the reaction products into a volume larger than the original. The reason why a Nxburst™ cartridge does not explode, and is therefore not an explosive in its packaged state, is that the velocity of deflagration or burning of the propellant is almost directly proportional to the degree of confinement of the chemical reaction. Thus, in an unconfined environment such as the product’s original packaging, the propellant if ignited will only burn at a very low velocity, which is incapable of causing an explosion. In contrast, an explosive if detonated or initiated in its original packaging, will produce a major explosion the result of which historically has had fatal consequences. The end result is that propellant-based cartridges are much safer to transport, store and use than explosives and for that reason the regulations relating to the transport and storage of Nxburs™ are considerably less stringent than for explosives such as Ammonium Nitrate/ Fuel Oil (ANFO).