Drill & Blast Best Practices Part One: Bench Preparation

Written by Aron Muniz, Mining Engineer, Drill & Blast Specialist, Datamine

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Drill & Blast Best Practices Part One: Bench Preparation

In more than twelve years of working as a drill and blast engineer, I have learnt many great practices on site, and witnessed as many equally questionable ones that I believe should not be propagated into the wider open pit industry. With some mindful procedures, we can all do our best to keep safety a priority and efficiency an objective. This is a series of Drill and Bl­ast Best Practices that will break down parts of the operational process that many people tend to overlook these days.

Introduction

The operations of drilling and blasting are the beginning of mining operations. The safety of a blast, the quality of the material fragmentation, the roads’ conditions, and the resulting slope stability all strongly depend on the proper execution of these jobs. The drilling itself can be treated as an activity composed of several steps and begins long before the drill rig even reaches the workbench. The blasting plan must follow the drill, charge and timing projects. All these activities depend on one another and therefore must be planned and carried out as a single process.

Bench Preparation: Easily Avoid Hazards

One of the first steps in an optimized drill and blast workflow is the bench preparation. Apart from achieving optimal blast results, this also refers especially to safety, which should be an essential key practice in the forefront of every blasting engineers’ mind. Establishing a safe work environment is everyone’s responsibility.

Aerial View of Open Pit Benches

A good daily safety briefing between engineers, supervisors, surveyors, drill rig operators and auxiliaries in the field is fundamental to ensure general situational awareness is attained. Everyone should be actively encouraged identify hazards and discuss safety measures to successfully mitigate them.

The dangers associated with blasting does not only start when explosives are delivered to the bench; several hazards can be avoided with apparent, but simple steps:

  1. Although not affecting blast results, removing existing loose fragments at the crest or close to the hole collars, for example, can avoid flying rocks due to eventual gas ejections. These fragments can cause falls and injuries to employees, especially during a night drilling shift.
  2. The proper demarcation – with physical barriers – of bench limits, road accesses, parking spots, turn-around rooms, high-wall stand-off distances, and other potentially hazardous areas also help to minimize the risks associated with drilling and blasting processes.
  3. The topographical survey of the bench and scanning of irregular faces (when available) are activities often treated with less relevance, or even completely discarded. However, when it comes to blasting results, their credit for the process quality is greater than it may appear. These activities are directly responsible for the formation of a bench database; information that is used as a foundation on which the drilling and blasting project will be developed on.

The safety and quality of a drilling and blasting process is the result of a series of well-performed steps, which I would prefer calling ‘procedures’. A procedure is a set of mandatory activities to be executed every time, regardless of any variables such as blast size, bench position or rush required for the operation. I have heard people say similar things such as,

We don’t need to care about safety with this blast because it is just a small one.”

However, this very well could be the first link of the chain that unfortunately leads to an accident. Bench preparation is a commonly bypassed procedure… however, it is a pertinent issue to be seriously addressed, and an essential practice to be adopted. The results will come.

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