http://hdl.handle.net/10204/938 2013-05-18T17:09:53Z 2013-05-18T17:09:53Z Pretorius, CJ Chesalokile, T http://hdl.handle.net/10204/6730 2013-05-07T11:59:09Z 2013-03-01T00:00:00Z

Title: What role can ISO 17025 play in the South African mining industry? ; Article Authors: Pretorius, CJ; Chesalokile, T Abstract: The ISO/IEC 17025 Standard was developed by the International Standards Organisation (ISO) to provide a mechanism to enable laboratories to manage the quality of their analytical results and to produce internationally comparable results. The Standards Division of the South African Bureau of Standards has adopted the ISO/IEC 17025:2005 as South African National Standard 17025:2005. There are, however, many misconceptions about what the ISO 17025 standard involves and the importance of such a standard in analytical measurements within the mining industry. This paper gives an overview of the standard, and explains what the standard requires and how it is applied in analytical measurements of respirable, silica-containing dust. The recent Mankayi case shows there is a need for the improvement and standardisation of analytical measurements within the mining industry. The ISO 17025 provides the framework in which these can take place. Description: Copyright: 2013 Mine Ventilation Society of South Africa. This is an ABSTRACT ONLY. The definitive version is published in Journal of the Mine Ventilation Society of South Africa, vol. 66(1), pp 15-17

2013-03-01T00:00:00Z Yenwong Fai, AS Durrheim, RJ Hildyard, MW http://hdl.handle.net/10204/6724 2013-05-03T21:55:15Z 2012-09-01T00:00:00Z

Title: Guided elastic waves produced by a periodically joined interface in a rock mass Authors: Yenwong Fai, AS; Durrheim, RJ; Hildyard, MW Abstract: Mining-induced seismic events pose a serious risk to workers in deep mines. Accurate numerical simulations are useful in analyzing the problem and developing mitigation strategies. Here we tackle the problem of guided interfacial elastic wave propagation in a periodically joined interface of two half spaces. The problem is viewed as a mixed boundary-condition plane strain problem and a displacement discontinuity model is used to model the boundary condition. The coupled set of first order linear differential equations for stress and velocity for an elastic continuum are replaced by an explicit finite difference scheme that is implemented on a regular rectangular staggered grid. Phase velocity dispersion curves for the guided interfacial wave modes are obtained via a phase spectra analysis method. The analysis reveals that longer wavelengths travel faster than shorter ones and that the phase velocity dispersion curve is a function of many model parameters including: source type (shear or dilatation), source time function, inherent periodicity at the model interface and size of periodic strips joining the interface. Lastly, we observe that the medium acts like some sort of “soft” frequency filter. Description: 8th South African Conference on Computational and Applied Mechanics (SACAM 2012), Johannesburg, South Africa, 3-5 September 2012. Not part of the 8th SACAM Conference Proceedings.

2012-09-01T00:00:00Z Pretorius, CJ http://hdl.handle.net/10204/6722 2013-05-03T21:55:09Z 2013-06-01T00:00:00Z

Title: The Status of silicosis in the world: Feedback on the ASTM Silica Symposium Authors: Pretorius, CJ Abstract: The second ASTM Silica Symposium was held in Oct 2012 where speakers reported on the status of silicosis in their respective countries. Speakers reported on findings of research that they carried out on sampling equipment and analytical techniques that are used in the monitoring of respirable dust that contains crystalline silica. This paper summarises some of the work presented. Description: The Mine Ventilation Society of South Africa 2013 Conference, Emperors Palace, Johannesburg, 27 February - 1 March 2013

2013-06-01T00:00:00Z Green, JJ http://hdl.handle.net/10204/6685 2013-04-18T21:55:16Z 2012-11-01T00:00:00Z

Title: CSIR Centre for Mining Innovation and the mine safety platform robot Authors: Green, JJ Abstract: The Council for Scientific and Industrial Research (CSIR) in South Africa is currently developing a robot for the inspection of the ceiling (hanging wall) in an underground gold mine. The robot autonomously navigates the 30 meter long by 3 meter wide, by 1 meter high stope area, while scanning the hanging wall to generate a thermally textured 3-D map. This 3-D model is then analyzed to identify cooler regions that are not consistent with the hanging wall topography. Cool ventilation air cools the hot rock deep below surface. If a crack exists in the rock, then the heat flow is interrupted and the 'unstable' cracked area is preferentially cooled by a fraction of a degree. This area is identified as potentially unsafe and flagged for attention by the miners upon their re-entry to the mine. The project is a collaborative effort between three units within the CSIR. The Centre for Mining Innovation (CMI) is the project lead unit and is developing the sensors needed for underground data acquisition for the safety application. A 3-D structured light scanner is rigidly mounted with a FLIR long wave infra-red camera and rotated through 360 degrees, creating a model of the stope. The CMI is also developing a telescopic arm with a 'tapper' to mimic the current inspection process and verify the algorithmically determined unstable region. The body of the robot is being developed by the Mechatronics and Micro-Manufacturing (MMM) group. The tracked main body is assisted by tracked flippers. Sensors for navigation are mounted in the front section while the safety data sensors are mounted atop the robot. A telescopic robot arm completes the package. The software component is being developed by the Mobile Intelligent Autonomous Systems (MIAS) Group. It includes the scanning of the environment with a laser scanner to determine a drive-ability region which is used in constraining the path planning and exploration algorithms. Combined these systems form the Underground Autonomous Mine Safety Platform for the autonomous inspection of a stope hanging wall. Description: 10th IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR 2012), College Station, Texas, USA, 5-8 November 2012

2012-11-01T00:00:00Z