General guidelines of Charging and Blasting in Hot Strata condition:
Select the number of holes properly so that the total blasting operation should not exceed 2 hour from charging of first hole.
Measure the temperature of the holes almost constantly till the commencement of blasting operation.
Use water at least 12 hour before blasting to flush hot holes till the temperature comes down below 80oC.
Record the temperature of holes at a regular interval of time.
Use a mixture of Bentonite, Sodium Silicate and Water in holes which do not retain water to seal micro-fractures and cracks. Guar gum upto 5 percent may also be used for the purpose.
Only slurry or emulsion explosives, preferably bulk explosives to be used for hot-hole blasting purpose.
It is preferred that explosives charging may be started near the initiation point first, (i.e., load explosives in the sequence in which the blast will be fired first). This allows the pattern to be quickly charged, tied up and fired in the event of a change in conditions.
Where possible hottest holes to be loaded last.
Detonating fuse as initiation system only should be used. Shock tube and detonators should not be used down-the-hole.
Adequate non-combustible stemming material should be available near the collar of each hole prior to commencing of charging operation, for fast accomplishing charging operation.
Punctured holes are to be plugged at bottom before charging. Air-bags may be used for the purpose.
Combination of Bulk-Loading Emulsion explosives, Detonating Fuse with ‘Top-Priming’ of Booster is preferred. These primers are applied shortly before blasting time, at the top of the explosives charge, where the emulsion is relatively cooler.
After primers are put, stemming and firing are done as quickly as possible, without wasting any time.