User's Manual

RIOTRONIC X+

User Manual

This over confinement of gases causes:

 excessive backbreak

 ground vibration

 reduced fragmentation

 reduced muck pile looseness & diggability

Special attention should be paid to the positions of front row blast-holes. If the burden on

front row charges is excessive, the rock will not move sufficiently to allow rock in

subsequent rows to blast optimally and the blast will be a disaster.

If the burden is too small, energetic explosive gases burst rapidly through the face causing

noise, air blast and, in some cases, fly rock. If air blast is to be controlled, the burden distance

should be at least 20 blast-hole diameters.

Changes in burden tend to affect fragmentation, muck pile looseness and the presence of toe

much more rapidly than any changes in spacing. If blasting results are good and it is decided

to try a larger pattern, it is preferable to increase spacing rather than burden. If the current

pattern is already quite elongated, however, it may be necessary to keep spacing constant

and increase burden by a sensible amount (10% maximum). With any trial blast, it is

important that the muck pile is completely removed and the cost efficiency of digging

assessed before the next blast is drilled out.

It is most important that once burden and spacing have been selected, every blast-hole is

collared in the correct place and drilled at the correct angle and direction of dip and to the

correct depth. There is a very good argument for every blast-hole being pegged out by a

surveyor. Optimum blasting results cannot be achieved by stepping out of a blast-hole

pattern.

Main Points - burden

 General rule of thumb for burden is 24-36 blast-hole diameters.

 Burden and Spacing are controlled by blast-hole diameter, rock properties, required

fragmentation, muck pile looseness and layout of the block to be blasted.

 Excessive burden causes poor fragmentation, poor movement, toe and excessive

ground vibration.

 Insufficient burden causes air blast, fly rock, and poor fragmentation between blast-

holes and it wastes the explosive´s energy.

 Burdens can be changed in a blast to provide better relief in deep blasts (reduce

burdens as you move to the back of the blast with more than 15 rows from front to