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A review is presented of mine ventilation systems currently employed in coal longwall extraction mines, based on data obtained from a survey of 13 generally larger operations in Queensland. There is a strong move towards longer panels, wider faces, greater extraction heights, increased production rates, more efficient ventilation and reduced numbers of personnel, motivated by improved productivity and cost reduction. Mine workings are also moving deeper, resulting in increased ventilation control issues such as higher total and respirable dust levels, greater seam gas contents along with lower in situ permeabilities, spontaneous combustion and heat management. Longwall panel ventilation circuits vary with a combination of factors including seam characteristics, gas emission rates, spontaneous combustion, geological features and surface constraints. The main circuit design and planning parameters are airway velocity, longwall cutting methods, ventilation of control devices, pressure differentials and leakage paths, and gas concentrations across the length and width of the goaf. Provided that the ventilation circuit can manage the applied contaminant load of gases, heat and dust at an acceptable cost and circuit duty, supplementary controls such as gas drainage, refrigeration and dust sprays and scrubbers may not be required., A review is presented of mine ventilation systems currently employed in coal longwall extraction mines, based on data obtained from a survey of 13 generally larger operations in Queensland. There is a strong move towards longer panels, wider faces, greater extraction heights, increased production rates, more efficient ventilation and reduced numbers of personnel, motivated by improved productivity and cost reduction. Mine workings are also moving deeper, resulting in increased ventilation control issues such as higher total and respirable dust levels, greater seam gas contents along with lower in situ permeabilities, spontaneous combustion and heat management. Longwall panel ventilation circuits vary with a combination of factors including seam characteristics, gas emission rates, spontaneous combustion, geological features and surface constraints. The main circuit design and planning parameters are airway velocity, longwall cutting methods, ventilation of control devices, pressure differentials and leakage paths, and gas concentrations across the length and width of the goaf. Provided that the ventilation circuit can manage the applied contaminant load of gases, heat and dust at an acceptable cost and circuit duty, supplementary controls such as gas drainage, refrigeration and dust sprays and scrubbers may not be required.

Field studies were conducted at two locations in southern Queensland, Australia during the 2003-2004 and 2004-2005 growing seasons to determine the differential competitiveness of sorghum (Sorghum bicolor L. Moench) cultivars and crop densities against weeds and the sorghum yield loss due to weeds. Weed competition was investigated by growing sorghum in the presence or absence of a model grass weed, Japanese millet (Echinochloa esculenta). The correlation analyses showed that the early growth traits (height, shoot biomass, and daily growth rate of the shoot biomass) of sorghum adversely affected the height, biomass, and seed production of millet, as measured at maturity. "MR Goldrush" and "Bonus MR" were the most competitive cultivars, resulting in reduced weed biomass, weed density, and weed seed production. The density of sorghum also had a significant effect on the crop's ability to compete with millet. When compared to the density of 4.5 plants per m2, sorghum that was planted at 7.5 plants per m2 suppressed the density, biomass, and seed production of millet by 22%, 27% and 38%, respectively. Millet caused a significant yield loss in comparison with the weed-free plots. The combined weed-suppressive effects of the competitive cultivars, such as MR Goldrush, and high crop densities minimized the yield losses from the weeds. These results indicate that sorghum competition against grass weeds can be improved by choosing competitive cultivars and by using a high crop density of > 7.5 plants per m2. These non-chemical options should be included in an integrated weed management program for better weed management, particularly where the control options are limited by the evolution of herbicide resistance.

A personal dust monitor is described which provides real-time respirable dust readings, based on a tapered element oscillating microbalance system which is able to collect suspended particles on a filter while simultaneously determining the accumulated mass. The unit is mounted within the miner’s cap lamp battery and internally measures the true particle mass of dust collected on the filter. Samples are available for later mineralogical analysis and results do not exhibit the same sensitivity to water spray as optically based measurement approaches. The technique achieves microgram-level mass resolution and reports dust loading data on a continuous basis. The system can also be used for real- time atmospheric diesel particulate matter monitoring to pinpoint high- exposure zones where a number of trucks and other vehicles work in areas of poor ventilation. The results can be used for efficient modification of work practices to reduce underground exposure., A personal dust monitor is described which provides real-time respirable dust readings, based on a tapered element oscillating microbalance system which is able to collect suspended particles on a filter while simultaneously determining the accumulated mass. The unit is mounted within the miner’s cap lamp battery and internally measures the true particle mass of dust collected on the filter. Samples are available for later mineralogical analysis and results do not exhibit the same sensitivity to water spray as optically based measurement approaches. The technique achieves microgram-level mass resolution and reports dust loading data on a continuous basis. The system can also be used for real- time atmospheric diesel particulate matter monitoring to pinpoint high- exposure zones where a number of trucks and other vehicles work in areas of poor ventilation. The results can be used for efficient modification of work practices to reduce underground exposure.

A rainfall simulation system is designed and used in centrifuge modelling of rainfall-induced landslides. The configuration of this system is described in terms of techniques special for centrifuge tests. These techniques allow the system to distribute raindrops uniformly and minimize the size effect of raindrops and the inclination of raindrops due to Coriolis effects. Hence this system is able to simulate rainfall with different intensities and durations. The function of the simulation system is verified during an infiltration process in a sand slope test in the centrifuge.

The use of computers for real-time monitoring and control of mine ventilation systems could be integrated into mine information systems, providing automatic control on a cost-effective basis. The background to the development of real time monitoring systems is reviewed and results of a field trial given. This monitored ventilation flows in an Australian metalliferous mine, and the trials showed that the system could detect and predict changes., The use of computers for real-time monitoring and control of mine ventilation systems could be integrated into mine information systems, providing automatic control on a cost-effective basis. The background to the development of real time monitoring systems is reviewed and results of a field trial given. This monitored ventilation flows in an Australian metalliferous mine, and the trials showed that the system could detect and predict changes.

One method of fire fighting underground is the injection of inert gases into the mine, for example using the GAC jet engine unit. The effect of the injection on the ventilation system can be modelled with the aid of the Polish mine fire simulation software Ventgraph. Case studies using the software to simulate the effects in Australian longwall coal mines are discussed. The first looks at the most efficient location of the GAC unit at a surface portal. The second examines the case when there are significant gas emissions at the face. This showed that under certain conditions there is an increased chance of an explosion if the surface fan is stopped. The third investigated the control of inert gases in the complex ventilation pathways in main headings. The work will lead to better fire-fighting methods and emergency plans., One method of fire fighting underground is the injection of inert gases into the mine, for example using the GAC jet engine unit. The effect of the injection on the ventilation system can be modelled with the aid of the Polish mine fire simulation software Ventgraph. Case studies using the software to simulate the effects in Australian longwall coal mines are discussed. The first looks at the most efficient location of the GAC unit at a surface portal. The second examines the case when there are significant gas emissions at the face. This showed that under certain conditions there is an increased chance of an explosion if the surface fan is stopped. The third investigated the control of inert gases in the complex ventilation pathways in main headings. The work will lead to better fire-fighting methods and emergency plans.

48 Australian mining operations (15 fly-in/fly-out (FIFO) and 33 traditional) completed a survey on the impact of FIFO methods. Employees, state government Departments of Mines and Energy and AusIMM branches also responded to questions. Tables are presented of data on mine type, annual production, expected mine life, probability of mine life extension, number of employees and workforce distribution. The majority of FIFO operations were found to be successful although there was evidence that labour turn-over rates at some FIFO operations were higher than those at town-based operations. FIFO operations which were successful in retaining their workforce generally operated on a symmetrical shift roster and spent high capital sums on developing a high quality mine camp/hostel at the mine site. The successful use of FIFO operations at the North Goonyella and North Moranbah coal mines in Queensland is discussed., 48 Australian mining operations (15 fly-in/fly-out (FIFO) and 33 traditional) completed a survey on the impact of FIFO methods. Employees, state government Departments of Mines and Energy and AusIMM branches also responded to questions. Tables are presented of data on mine type, annual production, expected mine life, probability of mine life extension, number of employees and workforce distribution. The majority of FIFO operations were found to be successful although there was evidence that labour turn-over rates at some FIFO operations were higher than those at town-based operations. FIFO operations which were successful in retaining their workforce generally operated on a symmetrical shift roster and spent high capital sums on developing a high quality mine camp/hostel at the mine site. The successful use of FIFO operations at the North Goonyella and North Moranbah coal mines in Queensland is discussed.

A large-scale field trial at Mount Isa showed that controlled partial recirculation is practical and reliable, giving considerable benefits in terms of improved air quality and reduced costs. The recirculation does not cause an increase in the concentration of contaminants in the return air or a gradual build-up of any contaminant. The only significant change in any contaminant was observed in the period following large-scale blasting in the 3000 orebody, but potential problems of this kind can easily be eliminated by shutting off the recirculation system during blasting to prevent highly contaminated air being recirculated into working areas., A large-scale field trial at Mount Isa showed that controlled partial recirculation is practical and reliable, giving considerable benefits in terms of improved air quality and reduced costs. The recirculation does not cause an increase in the concentration of contaminants in the return air or a gradual build-up of any contaminant. The only significant change in any contaminant was observed in the period following large-scale blasting in the 3000 orebody, but potential problems of this kind can easily be eliminated by shutting off the recirculation system during blasting to prevent highly contaminated air being recirculated into working areas.

Data was collected from various published financial reports of gold mining companies and a questionnaire was also sent out. It was found that a significant number of gold mines are variously using gold loans, forward sales, contractor mining and fly-in fly-out arrangements to finance their projects, though only four operations have vendor suppliers investing capital funds. It is concluded that such approaches are likely to be with the Australian industry for some time in the future., Data was collected from various published financial reports of gold mining companies and a questionnaire was also sent out. It was found that a significant number of gold mines are variously using gold loans, forward sales, contractor mining and fly-in fly-out arrangements to finance their projects, though only four operations have vendor suppliers investing capital funds. It is concluded that such approaches are likely to be with the Australian industry for some time in the future.