OPEN PIT MINING AT THE ERZBERG



The Erzberg is the biggest and most modern mining area in Central Europe, the most important ore deposit in the Alps, symbol of Austrian industrialization, and the center of the famous “Eisenstraße” (= iron road). For more than 1.300 years people have been mining the precious mineral on this mountain called “Erzberg” (= ore mountain). In 1890 open-pit mining changed and mining was done in benches. This is the reason why the mountain looks like a pyramid these days. More than 12 million tons of stone are mined per year. Not by using tools, of course, but by daily blasts.

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3 MILLIONEN TONS OF ORE PRODUCTION PER YEAR 

More than 230 people are currently working for the mining company VA Erzberg. 12 million tons of stone are processed and, thus, 3 million tons of grain-sized iron ore can be produced in one year. Since the Erzberg provides ore of different qualities, short to long-term mining plans have to be made by using computer generated deposit models.

Before the blasts, two huge surface crawlers of the Atlas Copco company (ROC L8) and one Sandvik Pantera DI6400 drill boreholes, which are 27 meters long, into the benches. These impressive machines are able to produce 30 meter-long holes in one hour. After drilling, the boreholes are filled with a viscous emulsion explosive and ANFO (ammonium nitrate/fuel oil), a widely used bulk industrial explosive, which are provided by the company Maxam Austria.

 

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THE BIGGEST INDUSTRIAL MACHINES IN CENTRAL EUROPE

On average, about 80,000 tons of material is won per blast. A part of this amount is waste and, thus, of no economic value. It is taken to our waste dumps. The rest is material containing the precious mineral, which is sent to the main customers “voestalpine Stahl Donawitz GmbH & Co KG” and “voestalpine AG Linz”. But first it has to be processed: big dumpers with a loading capacity of 120 tons take it to the crushing plant. Wheel loaders with a bucket capacity of 11-13m3 fill the blasted material onto the dumps. Three to four buckets are enough to fill a dumper. At the moment, 13 dumpers (Komatsu HD 985-5 qnd Komatsu HD 785-7) and 5 wheel loaders (Komatsu WA-800-3) are used for haulage. On several occasions, the company also uses a crawler excavator for loading (Komatsu PC 1250: operating weight = 125 tons; bucket capacity = 7m3)

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ORE PROCESSING

The first step of ore production is crushing. In our crushing plant, a big crusher breaks the big chunks (up to 1 meter in diameter) to smaller pieces (smaller than 15 centimeters in diameter) in only 6 minutes. Amazing fact: this gyratory crusher can crush 1200 tons per hour. After crushing, the material is processed in two ways. The high quality ore (more than 30% iron content) is screened, washed and undergoes a sensor based sorting. The lower quality ore is processed by using a dense media separation. Thereby, a high dense liquid is used for separating the ore (high density) from waste (low density). After separation, the ore is crushed again until it has the final grain size of about 10 millimeters in diameter. 4 crushers and 7 sieves take care of that. This fine ore is now ready for shipment.

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OUR PRODUCT: FINE ORE

At our mechanized blending bed, the fine ore is stored and homogenized. It is transported to the station, where the trains are filled, by a conveyor belt. Thus, 3 million tons of fine ore can be processed to high quality steel in Linz and Donawitz.

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