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Control of Spontaneous Combustion in a Pillar Using a ... - SME

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D. Chalmers<br />

A. Lim, E. Baume & P. Holt


• Self heat<strong>in</strong>g <strong>of</strong> coal<br />

• Develops as a result <strong>of</strong> oxidation on exposure<br />

to air.<br />

• Ideal conditions<br />

• Sufficient supply <strong>of</strong> air<br />

• Insufficient airflow to remove heat<br />

• Some coals are more prone than others.


INHERENT<br />

• Rank<br />

• Porosity<br />

• Pyrites<br />

• Moisture<br />

• Petrology<br />

MINING RELATED<br />

• Low air velocity<br />

• Moderate differential<br />

pressures<br />

• Broken coal<br />

• M<strong>in</strong><strong>in</strong>g method


• Rout<strong>in</strong>e shutdown <strong>of</strong> the m<strong>in</strong>e<br />

• M<strong>in</strong>e deputy patroll<strong>in</strong>g the conveyor belt <strong>in</strong> C<br />

head<strong>in</strong>g<br />

• noticed that the rib just <strong>in</strong>bye n<strong>in</strong>e cut through<br />

was glow<strong>in</strong>g orange.<br />

• Senior management was alerted<br />

• procedures were implemented to br<strong>in</strong>g this<br />

under control


MEASURES TAKEN<br />

• Bore holes and <strong>in</strong>ject<br />

water to cool it<br />

• Spray it with shotcrete<br />

• Lower Fan pressure by<br />

shutt<strong>in</strong>g down one unit.<br />

EFFECTIVENESS<br />

• Good, but messy<br />

• Worked for a while then<br />

failed<br />

• Good but damag<strong>in</strong>g<br />

bottom l<strong>in</strong>e


• How much grout would be needed to <strong>in</strong>ject<br />

<strong>in</strong>to pillar to prevent Spon Comb reoccurr<strong>in</strong>g?<br />

• Sought help from consultants<br />

• Attended Australian M<strong>in</strong>e Ventilation Conference,<br />

UNSW<br />

• Discussed solution with several presenters<br />

• Lateral Th<strong>in</strong>k<strong>in</strong>g was required


• Problem<br />

• Only one return<br />

• Belt road has drive head –INTAKE AIR


SMH.com.au<br />

Annie Leibovitz<br />

Maggie Mastricola


• A. wrapp<strong>in</strong>g pillar <strong>in</strong> Plastic<br />

• B. Form a balance chamber by runn<strong>in</strong>g a<br />

membrane along return side <strong>of</strong> pillar<br />

• This drops the Pressure across the pillar<br />

• Keeps return open for ventilation<br />

• Reduces leakage through pillar<br />

• Spon comb under control


900Pa<br />

25Pa<br />

Door<br />

Stopp<strong>in</strong>g<br />

Membrane stopp<strong>in</strong>g


• Leakage through the door provides <strong>in</strong>take<br />

pressure to both sides <strong>of</strong> pillar<br />

• Pressure dropped from 900 Pa to 25 Pa


• flexible membrane as a means to provide a<br />

balance chamber -successful.<br />

• The spontaneous combustion event under<br />

control<br />

• Chamber has provided long-term solution


• clean up floor before <strong>in</strong>stallation<br />

• brief<strong>in</strong>g <strong>of</strong> m<strong>in</strong>e personnel how membranes<br />

work<br />

• modification <strong>of</strong> reta<strong>in</strong><strong>in</strong>g washers<br />

• <strong>in</strong>jection <strong>of</strong> grout <strong>in</strong> floor and ro<strong>of</strong> where<br />

applicable

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