CES CES Blasting Operations & Techniques

Question 1

What is the primary purpose of a pre-blast inspection in surface blasting operations?

Accepted Answer

To identify nearby structures, utilities, and conditions that could be affected by the blast

Answer

A pre-blast inspection identifies structures, utilities, and environmental conditions that may be affected by ground vibration, airblast, or flyrock.

Question 2

In bench blasting, what does the term 'burden' refer to?

Accepted Answer

The perpendicular distance from the free face to the front row of blast holes

Answer

Burden is the perpendicular distance from the front row of blast holes to the nearest free face, and it directly influences fragmentation and ground movement.

Question 3

Which delay timing system minimizes flyrock and overbreak by allowing sequential detonation of blast holes?

Accepted Answer

Electric millisecond delay detonators or electronic detonators with programmed delays

Answer

Millisecond delay or electronic detonators allow sequential detonation that controls rock movement, reduces overbreak, and minimizes flyrock.

Question 4

What is the recommended minimum stemming length above explosive column in a blast hole?

Accepted Answer

Equal to or greater than the burden distance

Answer

Industry practice and many regulations require stemming length to be at least equal to the burden to contain gases, reduce airblast, and improve fragmentation.

Question 5

What does the term 'specific charge' (or powder factor) mean in blasting operations?

Accepted Answer

The weight of explosive used per unit volume or ton of rock broken

Answer

Powder factor (specific charge) is expressed as pounds of explosive per ton or cubic yard of rock and is used to design and evaluate blast efficiency.

(CES) Certified Explosives Specialist Practice Test

(CES) Certified Explosives Specialist Practice Test

CES CES Blasting Operations & Techniques