Challenges facing occupational environment professionals and their future

No abstract available.http://www.mvssa.co.zaam2017Mining Engineerin

Active explosion barrier performance against methane and coal dust explosions

Preventing the propagation of methane or coal dust explosions through the use of active explosion-suppression systems remains one of the most underutilised explosion controls in underground coal mines. As part of the effort to develop better technologies to safeguard mines, the use of active barrier systems was investigated at Kloppersbos in South Africa. The system is designed to meet the requirements of the European Standard (EN 14591-4 2007) as well as the Mine Safety Standardisation in the Ministry of Coal Industry, Coal Industrial l Standard of the Peoples Republic of China (MT 694-1997). From the tests conducted, it can be concluded that the ExploSpot System was successful in stopping flame propagation for both methane and methane and coal dust hybrid explosions when ammonium phosphate powder was used as the suppression material. The use of this barrier will provide coal mine management with an additional explosion control close to the point of ignition and may find application within longwall faces further protecting mines against the risk of an explosion propagating throughout a mine.http://www.saimm.co.za/journal-papersam2017Mining Engineerin

Methods to suppress dust on open pit drill rigs

Spotters and samplers working around surface drill rigs can be exposed to high dust concentrations. In this study it was found that individuals were exposed to as much as 14.2 mg/m3, which exceeds the Occupational Exposure Level of 10 mg/m3. The work on which this paper is based included an extensive literature study, as well as field investigations on a surface mine in Namibia. A number of additional dust suppression interventions were identified. These improvements, listed below, will assist in reducing dust concentrations around the drill rigs: • Increase maintenance frequency on the shroud, sealing ring, suction pipes and filters of the drill rigs, • Design and install new overlapping rubber belts on the shroud of the DM45, • Install an air-blocking shelf on the inside perimeter of the shroud of the DM45, • Install an airflow meter to ensure that the QC: QB ratio never drops below 3:1, • Only allow wet drilling, • Flush the dust collector system more regularly with compressed air to ensure that it does not become blocked, • Introduce stricter supervision to ensure that the suction pipes are always connected to the shroud, • Give drill rig operators more advanced training to ensure more effective drilling in order to reduce dust levels. It can be concluded that the implementation of the recommended improvements in engineering controls, better maintenance practices and better operating practices will assist in preventing any potential respiratory diseases and the degradation of the surrounding environment.http://www.mvssa.co.zaam2017Mining Engineerin

Sub-standard practices : effects on safety performance in South African gold mines

Sub-standard practices and their adverse impact on safety performance remain a challenge in the South African gold mining industry. The purpose of this study was to investigate the root causes of sub-standard practices and the effect on safety performance in South African gold mines. The focus of the study was on the underground production operations at a gold mine in the Free State. The study consisted of three parts: a personal investigation into the causes of sub-standard practices at the mine, a comparison with the results of a cultural study performed at the West Wits mines, and a behavioural survey. The studies described in this article yielded similar results in terms of the key drivers behind sub-standard practices. It was found that substandard practices had a number of causes, and the origin lies within the habits, attitude, and behaviour of employees. Current methods of addressing sub-standard practices and improving safety performance were found to discourage employees from performing work safely and according to procedure. It was concluded that the lack of critical behavioural habits for the given work environment and job title could possibly be the primary reason for the occurrence of sub-standard practices.Paper written on project work carried out in partial fulfilment of B. Eng. (Mining Engineering).http://www.saimm.co.za/journal-papersam2016Mining Engineerin

Control strategies for coal dust and methane explosions in underground coal mines : current South African research and development initiatives

Please read abstract in article.http://www.saimm.co.za/journal-papersam2017Mining Engineerin

Surface fan operational cost saving using purposely designed fans

The use of high powered catalogued auxiliary fans to meet the ventilation requirements of fairly shallow mines is common practice and often is not an energy efficient ventilation solution. This paper describes the process followed to investigate the potential of using alternative and more energy efficient axial flow fans to meet the ventilation requirements when used as main surface fans for shallow platinum mine shafts. The benefit of replacing catalogued auxiliary fans used as main fans with purposefully engineered fans was considered. From the investigation it can be concluded that the operational cost saving associated with the saving in power due to the improvement in the operational efficiency proved that the replacement of the older generation installations is viable. When comparing a single original fan installation to a purposefully engineered fan it will have a payback period of approximately 7 months per complete new installation and will continue to save electrical operational cost as a result of the improved energy efficiency.Original paper presented at the 2017 MVSSA Conference.http://www.mvssa.co.zahj2021Mining Engineerin

Evaluation of a continuous miner half-curtain dust control system in a South African underground coal mine

The project was planned in two phases. The first phase involved laboratory tests on a continuous miner model for different ventilation and spray systems at the newly built ventilation simulation tunnel at the Klopperbos research centre. In the second phase of the project, tests were carried out underground based on the findings and recommendations from the simulated tests. This paper focuses on the results and findings for the half-curtain system which have been encouraging. The average dust concentration for the sampling period at the operator’s position for the half-curtain system was 3.20 mg/m3. On the other hand, the equivalent average dust concentration (TWA-CONC) for the half-curtain system for a 8-h period was 2.04 mg/m3. The outcome of this project has shown that the regulatory dust level of <5 mg/m3 can be achieved through close collaboration with all the interested parties.http://www.mvssa.co.zaam2017Mining Engineerin

Recent advances in dust control technology on South African underground coal mines

Despite the much-heralded arrival of the new millennium, improving mine health and safety remains an enormous challenge. Considerable progress with environmental (dust and methane) control in South African mines has indeed been made but it remains a matter of great concern to all parties, i.e. mine management, labor and the government. The introduction of the 1997 Directive on dust exposure and mine ventilation was a milestone for the South African coal mining industry in improving health and safety standards. These stricter guidelines and the latest dust control technologies are beneficial not only in the longterm health perspective, but also to in terms of controlling methane and coal dust explosions (high-risk) in the short term. Over the past two years, CSIR: Miningtek personnel developed new dust control systems through various Safety In Mines Research Advisory Committee (SIMRAC) funded projects and successfully implemented them in underground coal mines. Currently, it can be confidently claimed that the new and proven dust control systems are being effectively operated in more than 80% of the bord and pillar sections in South Africa. This paper highlights the critical components of the new dust control systems evaluated underground, viz., the half-curtain system, the retrofitted hood system, the double scrubber system and the integrated hood system for continuous miners, and the road header dust control system. The status of wet head dust control systems and the challenges facing high seam longwall mines are also presented in the paper. The relative effectiveness of various dust control systems are discussed and the relevant test results are given in the paper. It concludes with a discussion of the progress made and challenges facing the coal mining industry in reducing workers’ exposure to respirable dust.SIMRAChttp://www.mvssa.co.zaam2017Mining Engineerin

Testing of an on-board active suppression system for French mining conditions

The French research institute, INERIS, requested the assistance of the CSIR’s Division of Mining Technology in developing further precautionary measures against explosions in their collieries. In response to this approach, an on-board active suppression system was adapted to meet their mining requirements. This system is used on tunnelling machines in Germany where the machine is positioned in the middle of the tunnel, which is therefore not much wider than the machine itself. With this configuration, the machine is never away from the tunnel face during the cutting cycle. As a result, the possible volume in front of the machine of combustible gas requiring suppression is less than 50 m3. In South Africa this technology has been adapted to suit a twocut mining method which entails greater distances from the face and thus much larger volumes of methane mixtures requiring suppression. The particular configuration of the Explo-Stop® system being investigated required the suppression of possible methane ignition volumes of up to 180 m3 of a 9% per volume methane/air mixture. The volume is a consequence of the large cross-sectional area of French underground workings and of the two-cut mining method used in France. In order to take the second cut in the coal seam, the machine is pulled back a maximum distance of 4 m, leaving an air pocket in which gas can accumulate. The machine-mounted system is required to effectively suppress any flame ignited by such a large accumulated volume of methane. The results of the protocol tests done at Kloppersbos showed that the system was capable of suppressing all simulated methane ignitions for the prescribed conditions. This was achieved with a temperature increase of less than a 100°C at the operator’s position and without any flame being detected at this position.http://www.saimm.co.za/journal-papersam2017Mining Engineerin

The FutureMine collaborative research initiative : making research work

The FutureMine Collaborative Research Initiative has been successfully completed after three years of activity. The main objective of this initiative was to provide applications of research previously undertaken in the DeepMine initiative in terms of realistic solutions to problems facing gold mining operations as they reach for depths beyond 3500m below surface. The FutureMine initiative was sub-divided into four broad streams of technological expertise: rock engineering and seismicity; mining engineering and orebody management; software and communications and ventilation, cooling and refrigeration. This paper presents a summary of research output in this last area of expertise. Broadly, research in mine ventilation, cooling and refrigeration was directed in areas related to the re-circulation of air, cyclical use of ventilation and cooling systems, air scrubbing technology, optimization of chilled water reticulation, obtaining direct cooling at the work-face, improving underground refrigeration system through dry air-cooling and water heat rejection systems and a number of software simulation programs to be used in specific applications and as a tool assisting real-time monitoring of underground environmental conditions. This paper describes in broad terms the outcomes from this section of the research programme and proposes ways in which some of these technologies may be combined synergistically in novel systems aimed at maintaining acceptable environmental conditions while reducing the impact on the profitability of operations.http://www.mvssa.co.zaam2017Mining Engineerin