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 i-kon™ saves "two weeks” per blast

i-kon™ saves "two weeks” per blast  

Zinkgruvan, established in 1857, was taken over by Lundin Mining in 2004. At this mine they extract mainly zinc, as well as by products lead and silver. In 2008, 900 000 tonnes of ore was extracted and this year that amount is estimated to increase by 90 000 tonnes. At the moment the focus is on the ore bodies at Burkland and Nygruvan. In Burkland there are problems with bad quality rock which is why a comprehensive test using i-kon™ was initiated.

Clever logistical solution
When Sprängnytt (Orica’s Swedish Customer Magazine) visited the mine, Andreas Werme and Catarina Ask were in the process of loading an 18 tonne blast which is expected to break loose about 35 000 tonnes of rock.  They had drilled 180 blast holes and were filling them with emulsion from a loader which is custom-built in the Orica style. This truck can load from all directions, states Thomas Geidby, blasting technician at Orica Mining Services, who is in charge of detonating the i-kon™ blasts.

Employees at Zinkgruvan and Orica Mining Services have worked together to develop their own emulsion tanks with an approx five tonnes capacity.

There are eleven tanks like these, and they are all equipped with BM-brackets so that they can be easily hoisted and transported to the mine elevator by a forklift so that again it can be hoisted by another forklift for another journey to the loading truck. 

Fig 1: Catarina Ask connecting hose to the emulsion tank.

This system, which has made continuous loading possible, has been in successful use since 2005 and has proved very efficient. It should be possible to apply it in other Swedish mines, Thomas Geidby suggests. Bench Blasting all the way Bench Blasting has been the predominant method of excavation in Zinkgruvan since the end of the 1980s, a method which is continuously improving. It’s been especially aimed to find an excavation method for ore from bad quality rock wall whilst keeping the advantages of bench blasting.

It was apparent that Panel Stoping, during both first and second excavation attempt, was the best way. Zinkgruvan was the first mining company in Sweden who opted for this method.

Using electroninc detonators is a good choice when facing problems with rock movement, Thomas Geidby reports.

Karin Fogelqvist, planning engineer at Zinkgruvan, states that by using i-kon™ it is possible to fire bigger blasts than previously possible. These blasts are smoother, which means that the damage to the surronding rock is diminished, she says.



Fig 2:  Thomas Geidy, Blasting Technician - Orica Mining Services with the blaster that controls up to 400 detonators.

Reduced vibrations
Thomas Geidby has fired all four i-kon™ blasts at Zinkgruvan. He is also training the blasting team in using this new blasting techique. Of course we should manage to do this by ourselves in the long run, and I am very happy with the results so far. It is now possible to fire bigger blasts in one go, Lars Ljungqvist says. Lars Ljungqvist is also elated by the fact that the amount of vibration has been reduced by using electronic detonators.

This is an important factor as Zinkgruvan, in the next few months, will start blasting in areas near the factory buildings further down.

Fig 3:  Lars Ljunqvist, supervisor at Zinkgruvan and Lars Geidby, Blasting Technician, Orica Mining Services. "We are able to do the biggest blasts in one round now", says Lars Ljungqvist.