The next long distance of 1,804 ft in a taconite mine in the USA was constructed with low maintenance plastic e-chain systems® from igus®.
Taconite is a ferrous, flint-like stone, named after the Taconic Mountains in the United States of America. It is a Precambrian sediment stone that belongs to the banded ore due to its typical change between ferrous layers and layers of clay slate or chert. The very finely distributed iron content in the form of magnetite lies between 25 and 30%. The biggest deposit in the world is in the Mesabi Range in Minnesota. At the end of the 19th and beginning of the 20th centuries, the available iron ore was of such high quality that taconite was viewed as an unprofitable waste product. After the Second World War, however, a major part of the high-quality iron ore in the United States was already depleted, so that taconite became economical as a new source for iron. For the processing of taconite, the ore is ground to a fine powder and the iron is subsequently separated with the aid of strong magnets from the remaining stone.
The powdery iron concentrate is then rolled together with bentonite and lime as fluxing agent into pellets of about one centimeter diameter, which contains approximately 65% of iron. The pellets are then heated at high temperatures for further processing, in order to oxidize magnetite (Fe3O4) to hematite (Fe2O3). The concentrated taconite is transported from the production plants by railroad to Silver Bay, Two Harbors and to the twin harbors of Duluth and Superior on Lake Superior and then shipped in bulk carriers to other locations along the Great Lakes. Many steel-producing undertakings are located close to Lake Erie.
The e-chain® cable carrier system is installed on a conveyor system, which transports the mined taconite. With a travel of 1,804 feet, it is the second largest distance in the world supplied with plastic e-chains® beside the 1,441 ft travel in a harbor crane in Singapore - all of them implemented with igus® plastic e-chains®.
Since the igus® e-chain systems® were installed at the North Shore Mine in October 2008, over 3 feet of snow had fallen and temperatures dropped to -31°F. Below temperatures still reign at the start of 2009, yet the igus® system (chain + cables) runs without any problems at all - Plastics for longer life®
In the igus® lab in Cologne, e-chains® and chainflex® cables are regularly subjected to extreme temperature tests in the in-house climatic chamber and thus temperatures up to -40°F can be extensively tested and a functional safety guaranteed.
The operator of the North Shore Mine had already had excellent experiences in the past with igus® e-chains® in this plant. The advantages of the e-chains® are, compared to the previously used festooning systems, in addition to the price factor, the absolute corrosion-resistance, durability, safety and low space requirement. Additional decisive factors are the excellent technical support and the cost-free project planning from igus®.