I think your question is to stop the mitigation of spontaneous combustion.

There is a little you can do when it starts and you are not ready for it.

To avoid the spontaneous combustion the coal must be stored in packs separated from each other by either wall or hydraulic fences.

you have to have a lots of water stored for any short of unusual accident and avoid fresh supply of air if you can.

Dear Dr. Ravi,

The following articles are useful to understand the topic.

1) Prevention and control of spontaneous combustion

https://miningandblasting.files.wordpress.com/2009/09/spontaneous_combustion_guidelines.pdf

2) Assessing and managing spontaneous combustion of coal

https://www.usea.org/sites/default/files/media/Assessing%20and%20managing%20spontaneous%20combustion%20of%20coal%20-%20ccc259_new.pdf

3) Coal stock pile spontaneous combustion early detection

http://www.imcontrol.com.au/white-papers/test-white-paper/

Regards

In generally, spontaneous combustion fires begin as hot spots deep within the reserve of coal. Each coal stockpile temperature should be measured. If temperature probes installed in the coal bunker resulted in an excessive period of time before the fire was detected.

New coal added on top of old coal created segregation of particle sizes, which is a major cause of heating. The hot spots appear when coal absorbs oxygen from the air. Heat generated by the oxidation then initiated the fire.

Air circulating within a coal pile should be restricted as it contributes to heating; compacting helps seal air out.

Regarding the control of coal fires or coal refuse pile fires (both caused by the spontaneous combustion of coal), you can refer to the following two articles.

1. Controlling coal fires using the three-phase foam and water mist techniques in the Anjialing Open Pit Mine, China

https://www.researchgate.net/publication/269637532_Controlling_coal_fires_using_the_three-phase_foam_and_water_mist_techniques_in_the_Anjialing_Open_Pit_Mine_China?_sg=ZY93uTMuQz9ob8y8GzI6rKSv7Em4K-pWCWoT75dVfKTrZxqXvxzl9ugWGDiCbyp15s_O1Fzq6qgjwL8KbM_kiNtD8ACsusd9lpjZ3thb.Jk0wV49zV0Co7Obj61V4y8048cjP68_4fCFrJIwhrQQcQgo9JewXlVK1czAQhfKIEJSoJT84jNFiIGQdEVe5rA

2. Treatment of smoldering coal refuse piles: An application in China

Article Treatment of smoldering coal refuse piles: An application in China

1use a dozer or other earth mover to move the hot materials into fresh air so that the heat from the oxidation is liberated away from the rest of the coal.

2use water or mosture or foam to disrupt the thermal gain - the propellant of sponcom is dry air - substitute moist air or wet the coal.

3use an inert gas like N2 or CO2 to distrupt the oxidation

4 use cements or limes fly ash wash or slurry to permeate the coal

5 use fire fighting foams - they will be drawn into the coals -

Gypsum found to be an economically viable option...Have a look at the article below:

Article Influence of antioxidants on spontaneous combustion and coal...

1. Stockpile Temperature Monitoring

1.1 Temperature measurement frequency

a) In general, each Coal stockpile temperature should be measured 1 (one) time /day

b) However, in case of increasing temperature or suspected combustion in the stockpile, measuring frequency should be increased to 3 (three) times per day (1 (one) time per every shift)

1.2 Temperature monitoring locations

a) 12 points: incline of stockpile and edge, where it is easier to gain access to inside of stockpile (standards for 50,000 ~ 100,000 tons)

b) 3 points: at the center of the compacted strategic (long-term) stockpile, per pile with regular interval (standards for 50,000 ~ 100,000 tons)

c) The measuring locations and frequency should be increased if there are suspected points of temperature increase, because internal temperature can rapidly increase due to long-term stocking.

2. Pre-caution to take for prevention of Spontaneous combustion and effect

a) External precautions

(i) Condition of Stock

 Factors affecting spontaneous combustion: storage method, storage quantity, storage period, stockpile structure, occurrence of free water (ponding), etc.

 Initial occurrence: Approximately 1.0 ~ 1.5 m from the surface of the land

(ii) Circumstantial pre-cautions

 Ambient temperature, moisture, wind direction, wind velocity, etc

 Continuous evaluation of the exact impact of each factor is difficult, but should be applied

b) Internal precautions

(i) Volatile component and oxygen component

Maximum absorption of oxygen points: over 36% volatile component and over 90% oxygen component.

(ii) Moistures especially more prone to absorb oxygen at total moisture of 10 ~ 15%

(iii) Particle size of coal: the larger surface area which has small particle size of coal will speeds up the oxidation rate

(iv) Foreign materials: spontaneous combustion occurs more readily by the oxidation of Iron Sulfide (FeS2) and Phosphorus (P)

2FeS2 + 7O2 + 2H2O  2H2SO4 + 2FeSO4 + heat

2.1 Measures to prevent spontaneous combustion

a) Prevention of combustion by air isolation

 Making low incline plane, compaction of stock by bulldozer and vibrating roller

 Stock altitude of below 12m

 Don’t blend of lump coal and fine coal

b) Cooling by water injection

 Around 60ºC water injection by fire fighting hose after digging up with bulldozers and compaction of stock by bulldozers

c) Don’t stock long-term of high volatile coals

 Elevated temperature of coal received, or receiving coal in season prone to easy temperature rises (dry season) should be given priority reclaiming over other coals

 Coal identified to have elevated temperature should be used earliest or moved to another stocking area and apply compaction of the stock by bulldozer and vibrating roller

2.2 Applicable actions per measure temperatures

a) The first (1st) boundary temperature (40 ~ 50ºC)

 Increase of patrol times and monitoring the status of temperature conditions

 Compaction of stock at surface by bulldozer or vibrating roller

b) The second (2nd) boundary temperature (50 ~ 60ºC)

 Increase of patrol times and monitoring the status of temperature conditions

 Water injection and priority loading over the coals

 After digging up with bulldozers, compaction of stock at surface by bulldozer in case of temperature spread

c) The first (1st) dangerous temperature (60 ~ 80ºC)

 Greater increase of patrol times and monitoring the status of temperature conditions

 Highest priority of loading of coal and compaction of stock at surface by bulldozer

 Continuous water injection to the spot of temperature increase

 Compaction of stock at surface by bulldozer and vibrating roller and continuous water injection until reclaiming completion of the combustion coal. If the water injection stopped, temperature can rise very sharply by increased air flow through the internal voids within coal piles

d) The second (2nd) dangerous temperature (>80ºC)

 Bulldozer should dig the spot of temperature increasing and moving to other stock locations as well as applying water injection action should be continuously carried out until enough cooling is experienced

 Thereafter dig up with bulldozers the compacted stock at surface and remove by bulldozer in case of increased temperatures have spread

 The increased temperature of coals should be perfectly separated and moved to other stock areas, and monitored that it does not flare up again.