Ammonium Nitrate-Fuel Oil (ANFO) is the explosive generally used in the mining industry to blast ore from the rock face. The use and detonation of ANFO explosives in an underground mine is an intrinsically hazardous process. The by-products formed during blasting have been well studied over the years and modern mining techniques and methods have evolved to mitigate the inherent blasting and gas emission risks. However, there is insufficient research and quantitative data on mine workers’ respiratory exposure to blasting gasses under realistic underground conditions. Aim: The objective of this study was to determine whether blasting gasses such as nitric oxide (NO), nitrogen dioxide (NO2) and ammonia (NH3) pose an inhalation health risk to underground mine workers cleaning at the blasting panels approximately three hours after the detonation of ANFO explosives. Scraper Winch Operators’ (SWOs) respiratory exposure to selected blasting gasses was simultaneously sampled by means of active and passive sampling methodologies. Method: Personal exposures to NO, NO2 and NH3 were measured and analysed in accordance with NIOSH methods 6014 and 6015. Along with the active air samplers, respiratory exposure to NO2 and NH3 were measured by means of radial symmetry diffusive samplers (Aquaria® RING). Measurements were taken over an 8-hour period, where this was not applicable; results were time weighed to an average 8-hour exposure concentration in order to compare the Scraper Winch Operators’ (SWOs) respiratory exposure to the Occupational Exposure Limits (OELs) contained in the Regulations of the Mine Health and Safety Act (No. 29 of 1996). Results: The active air sampling results indicated that the SWOs’ respiratory exposure to NO, NO2 and NH3 complied with their respective OELs contained in the Regulations of the Mine Health and Safety Act (No. 29 of 1996). However, one of the SWOs had an exposure which exceeded the action level (50% of OEL) at which level the implementation of control measures are recommended to reduce the SWO’s exposure. Based on the results of the Wilcoxon matched pairs test, statistical significant differences were observed between the exposure results of the two sampling methodologies for NO2 (p = 0.00078) and NH3 (p = 0.044), with the passive diffusive sampling technique under sampling when compared to the active sampling method. This was also confirmed by a Spearman rank order correlation which indicated a poor relationship between the two sampling methods for NO2 (r = -0.323) and NH3 (r = 0.090). Environmental conditions (i.e. temperature and humidity), as presented in an underground mine, may have been a major factor for the variation between the two sampling methods, mostly affecting the passive samplers. Conclusion: It was established that engineering and administrative control measures implemented at the underground mine were effective to control SWOs’ respiratory exposure to NO, NO2 and NH3 below their respective OELs. An acute health risk pertaining the inhalation of blasting gasses was, therefore, not presented to mine workers cleaning at the blasting panels approximately three hours after the detonation of ANFO explosives. However, long-term exposure to blasting gasses at low concentrations may present SWOs with a health risk if such exposures are not adequately controlled or mitigated. The dilution and production of blasting gasses also varied from one blasting level to another. Geological formation, explosive charge-up and loading practices, the amount of water vapour inside the stopes and ventilation parameters are among the factors that may have affected the amount of blasting gasses produced underground. In addition, a drop in the carbon monoxide levels as indicated by the mine’s central gas monitoring system would not necessarily mean a lowering in other blasting gas concentrations (i.e. elevated ammonia gas concentrations as identified in the present study). The personal exposure levels between the active and passive sampling measurements also differed considerably. This may be ascribed to the impact underground mining conditions and processes had on the sampling media as well the complexities involved when sampling blasting gasses in general. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

Ammonium Nitrate-Fuel Oil (ANFO) is the explosive generally used in the mining industry to blast ore from the rock face. The use and detonation of ANFO explosives in an underground mine is an intrinsically hazardous process. The by-products formed during blasting have been well studied over the years and modern mining techniques and methods have evolved to mitigate the inherent blasting and gas emission risks. However, there is insufficient research and quantitative data on mine workers’ respiratory exposure to blasting gasses under realistic underground conditions. Aim: The objective of this study was to determine whether blasting gasses such as nitric oxide (NO), nitrogen dioxide (NO2) and ammonia (NH3) pose an inhalation health risk to underground mine workers cleaning at the blasting panels approximately three hours after the detonation of ANFO explosives. Scraper Winch Operators’ (SWOs) respiratory exposure to selected blasting gasses was simultaneously sampled by means of active and passive sampling methodologies. Method: Personal exposures to NO, NO2 and NH3 were measured and analysed in accordance with NIOSH methods 6014 and 6015. Along with the active air samplers, respiratory exposure to NO2 and NH3 were measured by means of radial symmetry diffusive samplers (Aquaria® RING). Measurements were taken over an 8-hour period, where this was not applicable; results were time weighed to an average 8-hour exposure concentration in order to compare the Scraper Winch Operators’ (SWOs) respiratory exposure to the Occupational Exposure Limits (OELs) contained in the Regulations of the Mine Health and Safety Act (No. 29 of 1996). Results: The active air sampling results indicated that the SWOs’ respiratory exposure to NO, NO2 and NH3 complied with their respective OELs contained in the Regulations of the Mine Health and Safety Act (No. 29 of 1996). However, one of the SWOs had an exposure which exceeded the action level (50% of OEL) at which level the implementation of control measures are recommended to reduce the SWO’s exposure. Based on the results of the Wilcoxon matched pairs test, statistical significant differences were observed between the exposure results of the two sampling methodologies for NO2 (p = 0.00078) and NH3 (p = 0.044), with the passive diffusive sampling technique under sampling when compared to the active sampling method. This was also confirmed by a Spearman rank order correlation which indicated a poor relationship between the two sampling methods for NO2 (r = -0.323) and NH3 (r = 0.090). Environmental conditions (i.e. temperature and humidity), as presented in an underground mine, may have been a major factor for the variation between the two sampling methods, mostly affecting the passive samplers. Conclusion: It was established that engineering and administrative control measures implemented at the underground mine were effective to control SWOs’ respiratory exposure to NO, NO2 and NH3 below their respective OELs. An acute health risk pertaining the inhalation of blasting gasses was, therefore, not presented to mine workers cleaning at the blasting panels approximately three hours after the detonation of ANFO explosives. However, long-term exposure to blasting gasses at low concentrations may present SWOs with a health risk if such exposures are not adequately controlled or mitigated. The dilution and production of blasting gasses also varied from one blasting level to another. Geological formation, explosive charge-up and loading practices, the amount of water vapour inside the stopes and ventilation parameters are among the factors that may have affected the amount of blasting gasses produced underground. In addition, a drop in the carbon monoxide levels as indicated by the mine’s central gas monitoring system would not necessarily mean a lowering in other blasting gas concentrations (i.e. elevated ammonia gas concentrations as identified in the present study). The personal exposure levels between the active and passive sampling measurements also differed considerably. This may be ascribed to the impact underground mining conditions and processes had on the sampling media as well the complexities involved when sampling blasting gasses in general. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

Student Number : 9104308Y - Msc Eng research report - School of Mining Engineering - Faculty of Engineering and the Built Environment / African Explosives Limited (AEL) is involved with the Hybrid Stress Blast Model (HSBM) project in the characterisation of its bulk explosives and part of this involves the collection of unconfined detonation velocities (VoD). Historical methods of unconfined VoD measurements and earlier measurements taken for the HSBM project did not attribute significance to the strength of the light containment media used, which was either cardboard or PVC, in various wall thicknesses. The main focus of this exercise was to investigate this significance and to make recomendations to the HSBM on the choice of pipes for future tests. ANFO was used in order to avoid complexities of manufacturing and density variation, which arise with emulsion explosives. Plastic sleeves were used as a control in defining a medium of negligible confinement in order to compare the results in PVC and cardboard pipes. The cardboard pipes selected had wall thicknesses of 2mm and 4mm, while the PVC pipes had pressure ratings of 4 Bar and 9 Bar with wall thicknesses from 1.5mm to 8.5mm. The inner diameters ranged between 45mm and 253mm. The following findings have been made in this report. - Plastic sleeves were not effective in comparing the effects of confinement, but the results suggests that thin walled carboard pipes are probably very close to unconfined, even near the critical diameter. - PVC pipes affect VoD more than cardboard pipes and the confinement provided by both types of pipes increases with their wall thickness. - Critical diameter increases with weaker confinement and vice versa. - VoDs in the different types of confinement converge as diameter increases. - Future unconfined VoD tests should take cognisance of the findings of this project. A similar confinement investigation would be benificial to determine whether similar trends prevail with Emulsion and Emulsion-ANFO blend explosives. However if such an evaluation is not conducted, the minimum requirements for further tests should be to apply the confinement and diameter relationships as determined for ANFO during this investigation.

One of the most important properties of an explosive is its velocity of detonation (VOD). It is essential that the explosive should detonate at its optimum rate and release sufficient detonation pressure to get good fragmentation under the existing field conditions. The main objectives of this research study are to investigate the effects of explosive type, blast hole diameter, and degree of confinement on the VOD of bulk ANFO and bulk emulsion in Kumtor Open Pit Gold Mine. In this study, the continuous resistance wire method is employed to measure in-situ VOD of both bulk ANFO and bulk emulsion. The VOD values are measured for different hole diameters and under different confinements for both explosives. The ideality of bulk ANFO and bulk emulsion is calculated by comparing the in-situ measured VOD&rsquo / s and their ideal detonation values. It is found that the VOD of both explosives increases as the blast hole diameter and the degree of confinement increases. In addition to this, VOD of bulk ANFO decreases when it gets wet in the blast hole. Another finding is that, proportion of bulk emulsion ingredients has influence on its VOD. This research study provides a good understanding to use suitable explosive in existing rock conditions in Kumtor Open Pit Gold Mine.

La presente investigación se desarrolló en Compañía Minera Cerro de Pasco (CMCP) donde se busca aplicar el uso del Plasma como agente de fragmentación de macizo rocoso en sectores productivos de la mina cercanas a zonas de expansión urbanas. La finalidad del estudio consiste en comparar los valores de Velocidad Pico Partícula (VPP) entre el uso de Plasma Frag Be vs el ANFO a una distancia promedio igual en ambos casos. En tal sentido, se construye el modelo matemático Imperialist Competitive Algorithm (ICA) – linear, el cual permite estimar valores de VPP y a su vez modificar las variables de entrada como el burden, el espaciamiento, la longitud de taco, el factor de carga, la cantidad máxima de Plasma por disparo y la distancia entre el punto de fragmentación y la ubicación del sismógrafo. El modelo ICA-linear queda validado mediante la aplicación de 4 indicadores de rendimiento estadísticos los cuales son: el coeficiente de determinación, el error cuadrático medio, el error absoluto medio y el error porcentual absoluto medio cuyos resultados son 0.817, 5.001, 1.979 y 14% respectivamente. Los resultados de comparar los valores de VPP a una distancia promedio de 172 metros como se determinó según el estudio, en el caso del Plasma Frag Be los valores estimados son nulos, es decir no se registrarán valores a dicha distancia, mientras que en el caso del ANFO los registros muestran un valor promedio de 8.802 mm/s para la misma distancia mencionada, lo cual demuestra que los valores de VPP en el caso del uso del Plasma como fragmentador de macizo rocoso son considerablemente menores que cuando se utiliza ANFO. / The present research was developed at Compañía Minera Cerro de Pasco (CMCP) where the aim is to apply the use of Plasma as a rock fragmentation agent in productive sectors of the mine close to urban expansion areas. The purpose of the study is to compare the values of Peak Particle Velocity (PPV) between the use of Plasma Frag Be vs ANFO at an equal average distance in both cases. In this sense, the Imperialist Competitive Algorithm (ICA) - linear mathematical model is built, which allows estimating PPV values and in turn modifying the input variables such as the burden, spacing, stemming, power factor, maximum charge of Plasma per delay and the distance from the blast-point to the seismograph. The ICA-linear model is validated by applying 4 statistical performance indicators which are: the determination coefficient, the mean square error, the mean absolute error and the mean absolute percentage error whose results are 0.817, 5.001, 1.979 and 14% respectively. The results of comparing the PPV values at an average distance of 172 meters as determined by the study, in the case of Frag Be Plasma the estimated values are zero, that is, no values will be recorded at that distance, while in the case of ANFO the records show an average value of 8,802 mm/s for the same distance mentioned, which shows that the PPV values in the case of the use of Plasma as a rock mass fragmentation device are considerably lower than when ANFO is used. / Tesis