Spontaneous Combustion Testing for Hazard Management Planning Dr B Basil Beamish MAusIMM CP (Min) RPEQ Technical Director CB3 Mine Services Pty Ltd 3/20 Archerfield Road, Darra Qld 4076 T: +61 7 33754100 M: +61 488 708 949 b.beamish@cb3mineservices.com International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014

Assessment of self-heating propensity in Australia Presentation outline The Sponcom process and requirements for a Principal Hazard Management Plan Assessment of self-heating propensity in Australia Examples of spontaneous combustion testing results and interpretation for mine planning Conclusions International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014

Sponcom process (Moreby and Chalmers, 2006) Coal + O2 CO, CO2, and H2O + HEAT  Intrinsic and extrinsic factors determine reaction rate INCREASES REACTION RATE INCREASES COAL TEMPERATURE RETAINED LOST CONVECTION CONDUCTION EVAPORATION Balance determines development of event Incubation period is the time taken for coal to reach thermal runaway with given intrinsic and extrinsic factors. Oxidation rate doubles for each 10⁰C rise in temperature, once the coal temperature exceeds 70⁰C Coal is a good insulator and can retain heat for years Coal can retain elevated activity for years Incubation periods can range from weeks to years Never use incubation period to avoid controls International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014

MDG1006 Spontaneous Combustion Management Guideline Updated by the NSW Mine Safety Operations Branch in February, 2011 released in May 2011 www.resourcesandenergy.nsw.gov.au/__data/assets/pdf_file/0007/419515/MDG-1006.pdf The intent of this guideline is to provide assistance to mines in the development and implementation of a Principal Hazard Management Plan (PHMP) for Spontaneous Combustion. Spontaneous combustion testing information is required to assess propensity to self-heat and to obtain data on gas evolution associated with coal temperature increase. International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014

Common Sponcom tests used by the Australian Coal Mining Industry Common tests measure the intrinsic spontaneous combustion propensity under set conditions with no indication of time to thermal runaway. Assessment is based on a rating scheme compared against previous coal histories. Crossing Point Temperature (CPT) and Relative Ignition Temperature (RIT) are high temperature index tests and do not provide any measure of the coal self-heating at low ambient temperature. They are also measured by force heating the coal in an oven. Minimum Self-heating Temperature (SHT) and R70 self-heating rate are low temperature index tests and provide a measure of the coal self-heating at low ambient temperature. They are measured in an adiabatic oven that allows the coal to heat itself, although SHT is now calculated from the oxygen content of the coal. New SponComSIM™ testing provides additional data on the time taken to reach thermal runaway using site boundary conditions and is benchmarked against coals with known self-heating performance. International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014

Sampling strategies for Sponcom assessment of a longwall mine Site specific and tailored to suit project objectives Top, middle and bottom of seam, plus any rider seams likely to fall into the goaf or floor coal left behind Minimum 800g required per sample (25cm of HQ core) Longwall operations tested every longwall panel Fresh face lumps just as good as core R70 testing of all samples for assessing intrinsic spontaneous combustion propensity SponComSIM™ testing of specific samples for benchmarking thermal runaway timeframe SponComGAS™ testing for evaluating gas evolution trends in support of TARPs International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014

Example of repeat R70 testing for a Newcastle high volatile bituminous coal International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 7

Example of repeat R70 testing for an Australian sub-bituminous coal International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 8

Intrinsic Spontaneous Combustion Propensity classification (ISCP) based on Qld and NSW coal conditions (Beamish and Beamish, 2012) Queensland New South Wales ISCP Class Propensity rating R70 value (°C/h) I low (L) R70 < 0.5 R70 < 1 II low-medium (LM) 0.5  R70 < 1 1  R70 < 2 III medium (M) 2  R70 < 4 IV high (H) 4  R70 < 8 V very high (VH) 8  R70 < 16 VI ultra high (UH) 16  R70 < 32 VII extremely high (EH) R70  16 R70  32 International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 9

New South Wales intrinsic spontaneous combustion propensity plot International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 10

Examples of SponComSIM™ testing to establish time to thermal runaway International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 11

Example of recent Queensland case study International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 12

Quantification of reactive pyrite effect International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 13

Effect of increasing amounts of reactive pyrite (Beamish, Lin and Beamish, 2012) International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 14

Trigger Action Response Plan (TARP) setting for underground mines Identification of most appropriate indicator gases and ratios Initially based on gas evolution testing of the coal TARP trigger levels set at logically determined values that are site specific (internal standard) Refined as part of the review process with mine site experience Possibility of differing geological domains influencing TARP trigger levels International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014

Small-scale gas evolution testing Characterises the gas evolution trend that occurs in response to coal self-heating as the temperature of the coal increases Results are evaluated for the specific trends of individual gases and gas ratios The information can be used to identify key indicator gases and ratios for use in TARPs and to support the alarm limits set in the TARP Coal is step heated up to approximately 180°C and gases analysed by GC include: O2, N2, CH4, CO2, CO, H2, C2H6, C2H4 International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014

Individual gas evolution results for Area A of a New South Wales mine International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 17

Individual gas evolution results for Area B of a New South Wales mine International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 18

Graham’s ratio trend with increasing coal temperature for Area A International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014 19

Conclusions Reliable and accurate results with appropriate interpretation are required by industry for Spontaneous Combustion Principal Hazard Management Planning. Relevant laboratory spontaneous combustion testing is required to evaluate the risk of developing an event under the site specific conditions of each mine and within different areas of the mine. Gas evolution testing provides support for the selection of appropriate indicator gases and ratios used in TARPs. International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014

References Beamish, B and Beamish, R, 2012. Testing and sampling requirements for input to spontaneous combustion risk assessment, in Proceedings of the Australian Mine Ventilation Conference, B Beamish and D Chalmers (eds), pp 15-21 (The Australasian Institute of Mining and Metallurgy: Melbourne). Beamish, B, Lin, Z and Beamish, R, 2012. Investigating the influence of reactive pyrite on coal self-heating, in Proceedings 12th Coal Operators’ Conference, N Aziz (ed), pp 295-300 (University of Wollongong and The Australasian Institute of Mining and Metallurgy). Moreby, R and Chalmers, D, 2006. Mine ventilation course notes, Mining Education Australia. International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014

Questions? International Conference and Exhibition on Occupational Health and Safety in Mines - Istanbul December 2014