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Safety and health in mines research advisory board

Annual Review 2003


CONTENTS

Mine Environment

The Development of Improved Climatic Mapping Procedures to assist the Environmental Planning of Hot Mine Workings

For ECSC project PR 116, joint University of Nottingham (UoN) and UK Coal Ltd (UKCL) research teams have been evaluating the use of thermal data loggers to collect continuous climatic data from a number of underground workings. Continuous climatic logging data have been obtained and collected from the H308's Longwall face, Stillingfleet Colliery, 312's Longwall face, Welbeck Colliery, and H272's drivage, Stillingfleet Colliery. The continuously recording data loggers record simultaneous dry bulb and relative humidity measurements. In addition to the collection of the continuous climatic record, the UKCL researchers have undertaken a number of consecutive manual climatic surveys within these underground workings.

UKCL researchers have conducted a geothermal survey to obtain the virgin rock temperature in the vicinity of 30's Longwall district, Harworth Colliery using a geothermal probe. A psychrometric computer model has been developed and successfully used to calculate the related wet bulb temperatures based upon the logged dry bulb temperature and relative humidity data, and the in situ underground barometric pressure calculated for the logging sites.

A study has been performed to identify the trends observed in the temperature variation across the longwall district over an operational week and that observed over the weekend. The objectives of this study were to attempt to identify the temperature trends across the underground working at Stillingfleet Colliery where the virgin rock temperature (VRT) is 30.4oC.

The thermal contributions to the ventilation air along the main gate of the H308's Longwall face, Stillingfleet Colliery have been examined. The intake main gate airflow is heated up by the sensible and latent heat generated by the conveyed minerals, water sprays and the machinery.

An analysis of the continuously recorded wet and dry bulb temperatures concluded that when the longwall face resumes production on Monday, the heat generated by the production activities is initially consumed to heat up the intake air. However, as the rock temperature is below that of the air a portion of the available heat energy is transferred from the ventilation air to the rock mass surrounding the main gate. To obtain a measure of the changes observed over a weekly shift period a linear least squares fit line was constructed for both the measured dry and wet bulb temperature profiles. An analysis of the data collected determined that there was a gradual increase in the dry and wet bulb temperatures over the first three days of the week (Monday to Wednesday).

However, it was observed that the temperature of the surrounding wall rock also gradually increases during this period (Monday to Wednesday) until the differences between the temperature of the surrounding rock and the ventilating air becomes insignificant. At this point little heat energy is transferred from the ventilation air goes to the surrounding rock. This results in the a levelling off of the gradient of the regression line for the dry and the wet bulb temperature as the ventilation air solely consumes the heat energy produced during production.

Use of Self-Rescuers in Hot and Humid Mines

MRSL completed this project with funding support from HSE. The concept of self-rescue is premised on the assumption that underground mine workers will have the physical and mental capacities required for self-rescue and in-seam rescue. There is a recognised research 'gap' concerning the practical limitations, and ultimately personal endurance limits, associated with the extended wearing of mining industry respiratory protective devices under high physiological stress conditions. This has important implications for emergency response strategies predicated on seeking to directly evacuate hot and humid mines. In response to these issues, a programme of research was defined, consisting of literature review, audit of climatic conditions, laboratory investigations and a programme of climatic chamber wearing trials. The wearing trial component of the programme, which involved volunteers being subject to controlled physiological stress, was reviewed by and received the approval of HSE's Research Ethics Committee. The research has provided a wide base of fundamental knowledge on physiological response to the wearing of escape respiratory protective devices under hot and humid conditions, and contributes to guidance on the selection and use of self-rescuers appropriate to prevailing deep mine environments in the UK. The work has been published as a HSE Research Report

Improved gas capture and climate control within high performance workings

This new MRSL three-year Project, 03010, has funding support from the EC Research Fund for Coal and Steel (RFCS) set up following the expiry of the ECSC treaty. It will examine how arduous climatic and environmental conditions impact on workers, together with investigating how climate issues affect the successful outcome of emergency activities. A number of analytical methods and tools, instruments and practical improvements will be investigated:

  1. Problem scoping and industry review phase. Specific consideration will be given to the challenges posed in respect of the development of longer headings in deeper mines. Consideration of how perturbations in the mining process and design changes to mine environment control measures affect local mine climate and introduce short-term, excessive temperatures will be examined. Alternative methodologies to introducing ventilation and cooling system changes will be reviewed.
  2. Development of improved visualisation and monitoring techniques. Various dynamic computational modelling simulations will be investigated to provide simpler, faster visualisation of mine conditions, and to ensure that modifications made to ventilation arrangements are effective. One area of modelling focus will be local microclimate and the value of applying finite difference iterative processes. To improve real-time environmental monitoring, the feasibility to provide an intrinsically safe instrument to measure basic effective temperature (BET) directly will be examined.
  3. Development of an integrated thermal risk assessment methodology. At the present time, there is an incomplete understanding of how arduous working conditions and high heat and humidity affect the probability of successful outcome of self-escape or assisted escape. This phase of the work will examine the development of a combined risk assessment and modelling methodology, with an objective of providing a more systematic and comprehensive approach, with a better understanding of the complex interaction of the various site, physical, environmental and physiological parameters.
  4. Practical measures to improve emergency intervention in high heat stress conditions. This component of the work is concerned with identifying practical measures to improve emergency intervention capability in arduous climatic conditions. This work will cut across strategic consideration of the respective emergency response models, through to examine specific improvements in transport, establishment of personal and microclimate cooling facilities, improvements to protective equipment and apparatus.
Updated 2012-01-20