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Safety and health in mines research advisory board
Annual review 2006

Contents


Mine operations

Control room ergonomics

Welbeck Mine are currently transferring the function of some of their older control room equipment into a computer-based SCADA (Supervisory Control & Data Acquisition) system.  As part of this change process, the opportunity is being taken to ensure that the new control room is ergonomically designed.  This is being achieved by the HSL Ergonomics section facilitating the design process in close cooperation with the SCADA system developers, the control room operators and the mine management.  Interviews with and video analysis of the operators at work have been used to find the ergonomic requirements of the proposed new control room, and are being fed back into the design process.  Ergonomics/Human Factors advice is being provided to enable the new control room design (and also the design method) to meet relevant BS/ISO standards as far as is reasonably practicable given that there are existing design and operational constraints.  Recommendations and some solutions for the workstation and environment design are being provided on an on-going basis as the project develops, and will also be delivered in a final report to the mine and HSE’s Mines Inspectorate.

Optimisation of minewater discharge by monitoring and modelling

MRSL has contributed to this RFCS project, RFC  03006, which is nearing completion.  The overall objectives were to offer solutions for effective mine closure, improved knowledge of ground water movement for working mines and effective surface environmental control of factors resulting from mining activities, both past and present. To achieve this, the study was designed to:

An analysis of the data related to surface hazards allowed the identification and selection of a sample of sites where mine water was most likely to have been a significant contributory factor. For each of the surface hazards within this sample, more detailed studies and follow-up investigations were undertaken. The data obtained provided information concerning:

The issue of acidic mine water having a corrosive effect on shaft linings, and therefore a major contributory effect on shaft collapse, was further studied.  Immersion tests on concrete cores were undertaken, to identify and quantify the physical and chemical effects. Concrete samples were immersed in tap water, de-ionised water, dilute sulphuric acid pH 5, actual acid mine water pH 4 and compared with un-soaked samples. Similar tests on gritstone and typical coal measure fill material were also conducted.

The tests on concrete showed that there was a reactive process from acidic conditions through to the alkaline phase.  Indications are that any water, flowing or in stagnant conditions, will attack lime based materials such as concrete or mortar in brick lined shafts. Weathering will also have major detrimental effects on such shaft materials. Methods of examining shaft lining competency, especially in submerged/filled conditions, are required. More work is also required to investigate the relationship of the initial findings and the numbers of abandoned mine shaft collapses and crown holes at the surface in the UK.

Tests on granular gritstone showed 3% loss of competency by weight. In a 1000 metre shaft, this may result in a considerable void space forming below the shaft cap. It is essential that careful choice of fill material is made to ensure void reduction and prevent potential lining and / or ground failure.

It is concluded that further studies are required to determine competent fill materials and in-situ treatments to prevent corrosion of shaft linings, support, fill material and cappings.

Failed rubbing rope

A sample of the failed rope from Hatfield No. 2 upcast shaft was examined metallurgically by HSL to determine the failure mechanism.  This shaft had been used infrequently in the period before the failure.  The tests carried out indicated that the rope was degraded significantly and ultimately failed due to loss of strength from severe localised corrosion.  The corrosion was caused by contact between the rope and aggressive strata water.  Rubbing ropes are normally protected by rope grease when a shaft is in regular use and the lack of rope grease was probably a consequence of the infrequent use.  The investigation has not revealed any evidence of material or manufacturing deficiencies in the rope.

Increasing the Efficiency of Roadway Drivages through the Application of Advanced Information, Automation and Maintenance Technologies

MRSL is contributing to this RFCS project, RFC-CR-04001, which is due to run until June 2007.  The aim of the research is to improve the efficiency of roadway drivages, through the use of the latest advances in information and automation technologies, applied to:

Satisfying the programme goals will involve applying advanced Information, Automation and Maintenance Technologies, including:

Varying techniques for the detection of the interface between coal measures and the encasing or surrounding stratum were reviewed, as part of the study into 3D profiling. The research considered the practicalities of the techniques, not specifically their suitability for use in coal mines. Detection techniques examined were Nucleonic Sensing, Natural Gamma Radiation (NGR), Vibration based coal interface detection, Infrared, Optical Reflectance, Radio Imaging, Electrical Resistivity, Radar, Longhole Drilling (Coring) and Magnetic spin resonance.

It has also been possible to take advantage of fundamental (continuous wave microwave frequency) signal measurements undertaken within other RFCS projects. This has offered a further theoretical insight into the capacity of WiFi (IEEE 802.11) technology to provide competent, predictable high data bandwidth network connections in the application areas in this project. The science of subterranean microwave propagation has been significantly advanced by the collective contribution of partners. These studies on the selection and evaluation of wireless technologies and investigation of underground propagation are now complete.

A comprehensive review of the health and safety implications of electromagnetic energy in mines was initiated to reconcile the literature, standards, regulations and guidance pertaining to these issues. Further work is ongoing to assess within-system and inter-system interference. Traditionally, a wide-ranging risk assessment must be undertaken, both above and below ground, to qualify the hazards and residual risks that can arise from the use of radio-frequency transmitting devices at or near mine sites. The possible wide-scale deployment of wireless network components, both for data transmission and monitoring and control purposes, raises issues of how safety assessments and controls can be managed. The studies did not consider the procedural controls that will emerge at mine level, but rather, examined the nature of the hazards, focussing on electromagnetic exposure and safety of electro-explosive devices.

Advances in Exploration Methods and Applications

UK partners involved in this RFCS project, RFCR- CT- 2005- 00001, are MRSL, UK Coal, Heriot Watt University and Seismic Image Processing.  The project consists of a package of integrated research which seeks to enhance mining exploration and planning capability, both at a strategic and tactical level.  The main topics for development are seismic surveys, radio imaging through coal panels, drilling parameter analysis, micro seismic activity and predictive analysis. 

Tomographic radio imaging is widely used in the United States and Australia, but for various reasons, has not been deployed in the UK and European coal industries. Here there has been greater reliance on seismic-based geophysical methods. The premise of MRSL’s research is to determine what factors practically impact on the scope of deployment of radio imaging methods, and whether significant enhancements are possible, leading to wider deployment potential and the reduction in coal face geological uncertainty.

An analysis of radio imaging methods has been undertaken, whereby the geological structure of the ground is deduced by measuring the attenuation of medium frequency electromagnetic waves over a number of intersecting paths. So far, this has involved an extensive appraisal of the complex electromagnetic propagation seen within coal seams, the construction of prototype transmitting equipment and the measurement of the parameters of the medium using several different types of equipment.

UK Coal are contributing with a programme of cored underground boreholes and geological observations at Daw Mill mine.  This is being undertaken in order to validate the sedimentary model generated from the re-processed seismic volume. The 3D seismic volume over the Daw Mill take was provided for reprocessing using novel inversion techniques by Seismic Image Processing, potentially to provide increased stratigraphic detail.  Re-allocation of resources to remedial repairs of gate roads means that just 13 underground cored boreholes have been drilled in 2006.

Coal samples were sent to partners for testing, and the details concerning 42 surface boreholes were provided to RFCS project partners, for modelling purposes.

New mechanisation and automation of longwall and drivage equipment

This RFCS Project, RFC-PR-05012, started in mid-2006. It focuses on the development of fully automatic shearer face equipment. This will take into account development of software for the design of cutting tools with a minimum of pick wear and machine down time due to excessive vibrations. Innovative methods of maintenance and planned repair of the machines are also features of the project.

RMT’s contribution is focussed on developing improved techniques and tools for designing mechanical cutting drums used in coal mining machinery. This will cover roadheaders, with axial and transverse heads, shearers and continuous miners.  RMT’s principal objectives are:

The main health and safety issue associated with this work is the reduction of dust from cutting and loading processes. Noise and exposure to risk during pick changing are related issues. Whilst addressing these is not the primary objective of the work, which is economic (faster cutting, less pick wear, lower maintenance costs), the health and safety aspects will be taken into account at every stage and reduced dust and noise should be a consequence of more efficient cutting equipment.

At the year end, RMT were in the first iteration of developing the new software and are compiling the databases on current equipment. They have also commenced the modelling work and have determined that the best package to use is FLAC3D.

MRSL has also contributed a technical appraisal of candidate methods of oil contaminant monitoring, with particular attention given to the measurement of water in oil.  An ‘internal’ report entitled ‘Investigation and recommendations on candidate methods of oil contamination monitoring’, highlights suitable technologies for further investigation.

The appraisal was wide-ranging, including techniques which may not be obvious contenders. In addition to those methods normally used for measuring the water content in lubricating and hydraulic oils, consideration was given to those products employed in the oil production industry (water cut meters). In addition to techniques for real-time, on-line monitoring of oil (both in the main line and in a bypass), attention was given to methods generally used for off-line measurements. This will allow consideration of possible means of adapting these techniques to provide an on-line measurement capability. An understanding of highly accurate yet off-line methods will also be necessary during the development phase in view of their use in validating the results achieved by prototype units.

A broad sample of existing maintenance operations on coal face equipment was also studied, to identify the operational task requirements and maintenance limitations likely to arise as a result of the equipment design or the working environment in which the maintenance is undertaken.

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Updated 2009-05-22