ACARP ACARP ACARP ACARP
Underground

Investigation of Heatings and Related CO and H2 Gas Flow Patterns in Longwall Goafs

Underground » Detection and Prevention of Fires and Explosions

Published: April 09Project Number: C15022

Get ReportAuthor: Ting Ren, Rao Balusu | CSIRO Exploration and Mining

This report presents a summary of the research work carried out under the Australian Coal Association Research Program (ACARP) project C15022, entitled "Investigation of heatings and related CO and H2 gas flow patterns in longwall goafs". The main objective of the project was to develop advanced CFD models and conduct detailed investigations of the heatings and associated carbon monoxide (CO) and hydrogen (H2) gas flow patterns in longwall goafs under various heating/oxidation scenarios. This work has provided a greater insight into heating gas flow patterns in longwall goafs and improved mine operator's capability to evaluate heating conditions at an early stage and develop appropriate control measures.

Review of laboratory tests and field observations indicated that CO make and absolute CO and H2 concentrations are closely associated with the development of spontaneous heating in longwall goafs. Three heating incidents in Australia longwalls were reviewed in this study, and in all cases, the development of goaf heating was closely linked with the rise of spontaneous heating indicator gases such as CO and H2 gas at different locations of the goaf. CO and H2 gas levels up to 2000ppm and 1000ppm respectively had been recorded during the heating incidents. These heatings were eventually brought under control by goaf inertisation and face ventilation management. It was also noted that the trends of heating gas were heavily influenced by a number of factors and a good understanding of goaf gas flow dynamics was critical for accurately locating the heating and its control.

Three dimensional CFD models were developed to investigate heatings and related CO and H2 gas flow patterns in longwall goafs. Based upon previous studies of goaf gas flow and oxygen ingress patterns in the goaf, the CFD model incorporates a number of 'heating blocks' representing heatings in the most likely locations in the goaf. Rather than modelling the complexity of the oxidation process of coal, the evolution rate of CO and H2 gas was assumed to follow a defined value at different stages of the heating. Base CFD models were developed to model heatings on both sides of the longwall goaf, imitating the heating experiences at an Australian underground coal mine. Results from the base CFD models were calibrated and validated against field data.

The validated CFD models were used for extensive parametric studies to investigate the impact of a number of inherent and operational parameters on the distribution pattern of CO and H2, including goaf gas emission rate, goaf leakage, face ventilation and the impact of goaf inertisation strategies. Field data from three heating incidents was then analysed in detail to link the real heating scenarios with the outcomes of CFD modelling results.

CFD modelling results demonstrate that the behaviour of gaseous products from goaf heatings is influenced by a number of factors and the understanding of goaf gas flow patterns is an important prerequisite for the correct interpretation of CO and H2 monitoring data. The project studies indicate that the location of gas monitoring sensors or tubes is critical for the early detection of a goaf heating, and where possible additional gas monitoring points should be placed at strategic locations on both sides of the goaf to ensure that increasing CO and H2 gas levels can be detected before the heating escalates into an advanced stage. Modelling results also indicated that more effective goaf inertisation for heating suppression and gaseous products (such as CO and H2 gas) dilution can be achieved by in-bye injection of inert gas at a distance from the face, either via a cut-through or surface borehole(s), in combination with a foam 'Air Plug' to reduce air ingress.

Underground

Health and safety, productivity and environment initiatives.

Recently Completed Projects

C29010In-Situ Stress Measurement Using Non-Destructive Techniques (Ndts)

Rock in depth is subjected to stresses due to overlaying burden and ...

C33029Review Longwall Face Ventilation To Mitigate Goaf Gas Emissions Onto Walkways And Tailgate End

As longwall mining increasingly targets deeper coal seams, managing ...

C29009Control Of Transient Touch Voltages During Switching

There have been an increasing number of electric shock incidents rep...

Underground

Open Cut

Safety, productivity and the right to operate are priorities for open cut mine research.

Recently Completed Projects

C35029Renewable Energy As Post-Mining Land Use

In 2020, the Queensland Resources Council (QRC), in partnership with...

C33036Radar Tyre Monitor System

This project focussed on trialling a radar sensing technology design...

C26020Preventing Fatigue Cracking Via Proactive Surface Dressing

Fatigue cracking of plant and equipment presents a significant chall...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C28061Quantitative Based Structural Integrity Evaluations Using Modal Parameters Estimation

This project focused on the development and implementation of a quan...

C34039Development Of A Soft Sensor For Predicting Dense Medium Cyclones Performance

This project details the development of a DMC soft sensor for modell...

C34041A Coal Spiral For The 2020S

The objective of this project is to develop an enhanced coal process...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Recently Completed Projects

C35039Impact Of Coal Grain Composition And Macerals Association On Fluidity Development In Australian Coals

The coke quality prediction models use thermoplastic terms as key ex...

C36004Physical And Chemical Structure Characterisation Of Biomass For Biocoke Production

Partial substitution of coking coal with renewable biomass is identi...

C35037Examination Of Contraction Pre And Post Resolidification Using A High Temperature Dilatation Rig

This project examined the contraction of coking coal samples, both p...

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C34066Safe Operation Of Catalytic Reactors For The Oxidation Of VAM Operating Under Abnormal Reaction Conditions

The catalyst Pd/TS-1 has shown excellent activity in oxidising venti...

C28076Selective Absorption Of Methane By Ionic Liquids (SAMIL)

This third and final stage of this project was the culmination of a ...

C29069Low-Cost Catalyst Materials For Effective VAM Catalytic Oxidation

Application of ventilation air methane (VAM) thermal oxidiser requir...

Mine Site Greenhouse Gas Mitigation

Low Emission Coal Use

Step-change technologies aimed at reducing greenhouse gas emissions.

Recently Completed Projects

C17060BGasification Of Australian Coals

Four Australian coals were trialled in the Siemens 5 MWth pilot scale ga...

C17060AOxyfuel Technology For Carbon Capture And Storage Critical Clean Coal Technology - Interim Support

The status of oxy-fuel technology for first-generation plant is indicate...

C18007Review Of Underground Coal Gasification

This report consists of a broad review of underground coal gasification,...

Low Emission Coal Use

Mining And The Community

The relationship between mines and the local community.

Recently Completed Projects

C16027Assessing Housing And Labour Market Impacts Of Mining Developments In Bowen Basin Communities

The focus of this ACARP-funded project has been to identify a number...

C22029Understanding And Managing Cumulative Impacts Of Coal Mining And Other Land Uses In Regions With Diversified Economies

The coal industry operates in the context of competing land-uses that sh...

C23016Approval And Planning Assessment Of Black Coal Mines In NSW And Qld: A Review Of Economic Assessment Techniques

This reports on issues surrounding economic assessment and analysis ...

Mining And The Community

NERDDC

National Energy Research,Development & Demonstration Council (NERDDC) reports - pre 1992.

Recently Completed Projects

1609-C1609Self Heating of Spoil Piles from Open Cut Coal Mines

Self Heating of Spoil Piles from Open Cut Coal Mines

1301-C1301Stress Control Methods for Optimised Development...

Stress Control Methods for Optimised Development and Extraction Operations

0033-C1356Commissioned Report: Australian Thermal Coals...

Commissioned Report: Australian Thermal Coals - An Industry Handbook

NERDDC