Safety of Workers Around Mobile Plant
IMC-TS, sponsored by HSE, completed work on a project to investigate the possible approaches and technologies to improve the safety of personnel around mobile plant. The study considered mobile plant across three industry sectors; underground mining, surface mineral extraction and warehousing and materials handling. The work programme investigated vehicle ergonomics and visual task analysis, aids to improve reversing and sight lines, direct body detection techniques, conventional transponder (Radio Frequency Identification Device) and Very Low Frequency magnetic dipole detection technologies. A proof-of-concept personnel detection scheme was developed, where workers would be equipped with a person-worn transmitter in high risk areas. The three axis transmitter unit employs microprocessor-based waveform synthesis with time-division transmission to generate mutually orthogonal fields.
Using a peak field detection algorithm, tests showed that detection performance was substantially insensitive to orientation of the transmitter. Field interrogation and mapping tests were undertaken to determine zonal coverage around typical mobile plant, including fork lift and free-steered articulated vehicles (FSVs). Moderate field distortion was observed, mainly due to the influence of the substantial mass of ferromagnetic material associated with large plant. However, even with the largest FSV type used underground, a predictable field and consistent detection thresholds can be obtained around the vehicle. The range of the prototype system, approximately 10 metres, could be extended to 15 metres by making improvements to the signal processing and transmitter diversity approach. A simple 'green', 'yellow', 'amber' and 'red' light driver's annunciator was constructed to give alerts corresponding to increasing proximity to the vehicle. The principle of the approach has been shown to be technically sound. The report has been published as Contract Research Report 358/2001 on HSE's website and in hard copy from HSE Books.
Non destructive Testing (NDT) of steel ropes.
A project, sponsored jointly by HSE, Bridon International, RJB Mining and Anglo American Corporation of South Africa, started this year at HSL. The aim is to assess the ability of a range of internationally available non-destructive testing instruments to find defects in wire ropes.
Six NDT companies were selected on the basis of an earlier investigation, sponsored by Anglo American in Germany. The participants were invited to bring their instruments (seven in total) to HSL, Sheffield, for evaluation. The evaluation of each instrument was conducted jointly by the company and HSL and was carried out using six ropes of varying construction some of which contained artificial defects; others were ex-service ropes containing real defects. In addition, the instruments were taken to a local colliery so that a winding rope, known to contain defects, could be examined. The instruments were also assessed by HSL for mechanical reliability and ease of use.
Each company is to produce a report on the condition of each rope and the findings will be evaluated by HSL. A number of the wire ropes will be tested destructively to confirm the location and severity of defects. Initial findings suggest that no one instrument is suitable for all types of rope.
Engineering Critical Assessment of Mining Cage Suspension Components
The aim of this HSL project is to provide information to enable engineering critical assessments to be made of mine cage suspension gear components. This involves the examination of the non-destructive test procedures and the application of fracture mechanics techniques to selected components.
Progress on the literature review and the production of NDT test blocks has been reported previously. The test blocks have now been issued to the four companies involved in the examination of cage suspension gear and they are being used to demonstrate the effectiveness of the NDT procedures.
Several cage suspension components have been assessed to establish the threshold defect size required to initiate fatigue cracking. Details of the design dimensions, maximum allowable stress, etc have now been received from the manufacturers and an engineering critical assessment of the most highly stressed components is to be undertaken. In addition, a set of life-expired cage suspension gear is to be supplied for examination by HSL.
The use of Virtual Reality for Mine Operations and Safety
The University of Nottingham leads this ECSC programme, also involving IMC and HSL in the UK and partners from Spain, France and Germany, to study the use of Virtual Reality (VR). The University has focused on developing underlying VR technology. IMC have concentrated on potential application areas.
HSL's contribution focuses on the reconstruction of mine incidents and on mine planning, as an aid to health and safety management. An incident at Stillingfleet has been modelled in VR and will be delivered to the mine for their appraisal shortly. They will evaluate the reconstruction in terms of its effectiveness at illustrating what happened and as a training tool.
A reconstruction of an incident at Milldam/Ladywash mine involving a free steered vehicle (FSV) has been started, with the help of the Mines Inspectorate. A model of the FSV has been constructed, with accurate dimensional detail. An analysis of the point-of-view (POV) of the driver will be carried out as part of the reconstruction. The POV from the FSV involved in the accident will be compared with the POV from a modified FSV to illustrate how VR can be used to assess safety issues with mining equipment in a simulated mine environment.
Investigations have been carried out into the use of photogrammetry (measurements derived from a series of photographs) to construct VR models of mine scenes and equipment. The suitability, speed and accuracy of using this method were investigated, taking into account the environmental restrictions which are often present in a mine (e.g.. space and lighting). Other methods for rapidly retrieving dimensional data from mine areas will be investigated.
The scope for using VR in mine planning operations has been investigated in preparation for discussions with mine personnel. The discussions will identify procedures which might benefit from the use of VR and promote safety management.
Material Transport Systems
The aim of this ECSC-sponsored research by IMC-TS is to enable mines to predict and evaluate the risk factors which affect both the economic and safety performance of their transport systems. Based on a combination of initial field research and data collection at the collaborating UK colliery and an extensive review of published research and technical papers, a document containing written guidance has now been drafted. The document covers locomotives for manriding and materials transport, free-steered vehicles for materials transport, and belt conveyors for manriding and the transportation of coal. A unique aspect of the work is that it includes a systematic consideration of the factors associated with individual performance and human reliability that are likely to impact on both economic and health and safety performance of transport systems. The document provides guidance on the measures that should be considered to reduce the potential for driver/operator errors. Case studies are provided to demonstrate the improvements that are possible through a systematic consideration of ergonomics and human factors.
Work has commenced on the second major phase of the project, which involves the development of a computer-based model. The model is being designed to be equally applicable to the planning of new transport systems and the improvement of existing operations. In order to promote widespread use throughout the industry, special emphasis is being placed on making the model user-friendly and, to this end, the computer software is being developed using C++ in a Microsoft Windows environment.
This ECSC study by IMC-TS was completed during 2000 and a Final Research Report is now is preparation. The research objective was to develop a mine-wide data/speech communications network philosophy exploiting the existing power distribution network infrastructure rather than using dedicated communication feeders or data and telephone cables. The developed scheme uses low-medium frequency inductive communication techniques in conjunction with short-range high frequency nodal communications. The conclusions from the work are:
Alarm and Evacuation Systems
IMC-TS and the University of Nottingham were also involved in an ECSC collaborative project, commenced in November 1999, investigating issues relating to emergency situations which may develop in underground coal mines. The focus is particularly on remote operation and long drivages where evacuation times can be extreme. The University is concentrating on novel refuge and escape technology together with environmental control technology and the use of virtual reality to model emergency scenarios and for training rescue teams.
The objectives of IMC-TS's work are:
During 2000, a literature study and review of international practice examined major international mining incidents, approaches to emergency planning and incident management, prevailing legislation and guidance documentation, together with related research on evacuation and early warning. It is acknowledged that the UK DMCIAC National Rescue Advisory Committee's Guidance and Information on Escape from Mines has made a major contribution to this field.
Technical development work concentrated on examining the problem of ensuring effective means of evacuation through smoke, accounting for the direct impacts on oxygen costs where SCSR technology may be used. A range of 'passive' and 'active' guidance technologies was investigated, summarised as follows:
A prototype wayfinding scheme has been devised which will offer guidance through smoke, and which has a distributed fire and temperature monitoring capability. The system will thus offer multifunctionality of emergency wayfinding together with pre- and post-incident environmental monitoring. Testing of the system will be conducted in 2001 in conjunction with the UK Mines Rescue Service.