OH&S News

Achieving energy efficiency in the drill and blast process

The cost of energy is definitely headed north. Ever increasing fuel prices, looming carbon taxes, legislation and community demands for the operation are a dark cloud on many operations? horizons. So what can be done? There is not much to do about the quarry process as such, it stays the same. To some extent you can always ask for energy awareness from your staff, and try to be as lean as possible. But this will only take you so far. There is a saying: ?What gets measured gets done?. What is focused or rewarded from management gets people?s attention and focus.

Technology offers some chance of relief. Atlas Copco?s modern range of SmartROC drill rigs are all about documentation and precision. SmartROCs are all able to run high precision navigation so it is easy to get your staff into a documented trial and error process that will lead to more optimised drill and blast results. And being early in the chain of drill and blast means they will affect the rest of the quarrying process.
The northbound energy cost can be battled at its roots. It is no secret that the cost of loading, for example, is affected by the quality of the blasted material. Is it a tight dig or is it a good open well fragmented blast?
The next step of crushing is also very dependent on the fragmentation. Big boulders will lower the throughput or even damage the equipment. Too many fines will waste material. So there is a delicate balance to strike and there is money to be made.
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With the ability to document and repeat the operations in a precise way we have begun improvements. Before planning any major changes to your position, you need to know where you are. In other words, you need to create a baseline. By challenging this baseline you can then start the process of improvement.
Precision in itself is a major improvement factor for the bench blast result. The ability to create a high precision floor of the blast with all holes ending in the right place greatly improves the energy distribution in the rock, creating good breaking and in the end fragmentation into correct size rocks. By moving the holes, ie changing the drill patterns, you can then, of course, also change the fragmentation. This is not new but to get good tools for the staff at the quarry that will help them in their daily work is the hardest part. It needs to be simple to use and close to the actual operation at hand.
Figure 4 shows principally a bench drill pattern precisely laid out. By changing the pattern and trialling different charges, the resulting fragmentation can be affected and finetuned. There are different technologies, like electronic detonators with simulation software that will show astonishing results, but they all need a bench drilled to deliver what they promise.

To reference a key user of Smart products, Norwegian limestone quarry Br?nn?y Kalk is a good case story. This is a highly efficient quarry, running two navigated Atlas Copco SmartRig F9Cs and one SmartRig D9C. Br?nn?y Kalk?s operation is lean and operates on a roster of two shifts. One of their bottlenecks is the loader capacity (a Caterpillar 990). In 2010,  Br?nn?y Kalk decided to improve the productivity in its existing fleet. By reducing the pattern of the bench from 2.8m by 3.6 metres to 2.6m by 3.3m, Br?nn?y Kalk improved the loader productivity from an average of 5500 tonnes per shift to 7000 tonnes per shift. Of course, this came at a slightly higher expense but this is what was needed at the time.

To summarise, there are improvements to be made, there are energy costs to be saved and there is a community image to be gained. Many quarries are finding it harder and harder to hire young people into our industry and the retention of experienced operators is equally challenging with the thrust of the two-speed economy. How about starting to offer modern tools, with measurable results and rewarded improvements? Would the modern quarry owner wish to go back to pen and paper for the budget work? Or is the laptop with a spreadsheet software a step towards the future? Isn?t it about time that we start thinking the same of our drill and blast crew and their tools?

What gets measured gets done!

Olav Kvist is the product line manager of Atlas Copco Rock Drills AB in ?rebro, Sweden.

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