Environmental Benefits of Surface Mining By Peter n. Grimshaw

Most forms of economic activity affect the environment in ways which can be claimed to be detrimental. Some of the worst results were produced in the pasty by mining. However, handled correctly, surface mining can have beneficial effects and the author discusses this, talking examples from coal mining activities in Great Britain.

SURFACE mining by its very nature causes severe disturbance to the surface of earth and, with associated activities , is undoubtedly detrimental to human, animal and plant life in the short-term. Any long-term permanent effects, albeit often conjectural, are rightly the subject of much critical attention and debate.

If, however, after taking into account a wide range of economic, social and environmental factors, surface mining is deemed a necessity, then not only can the inevitable and traumatic losses to the quality of both the natural and manmade environments during extraction operations be minimized, but actual long-term gains can result. The planning for, and creation of, such environmental benefits rarely receives the attention it deserves; but recognition of these benefits is necessary if a board and balanced perspective on this emotive form of economic activity is to be achieved.

Environmental benefits from opencast mining can range from something as small-scale as the planting of wild roses on a former site which were then harvested as the basis of a health preparation, to the possible rehabilitation of Cutacre colliery tip, claimed to be the largest of its type in Europe. This is on the proposed 600 ha Lomax site between Little Hulton, Atherton and Tyldesley in Lancashire.

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Kiruna Iron Ore Mine, Sweden

With an ore body 4km long, 80m thick reaching a depth of 2km, LKAB’s Kiruna is the world’s largest, most modern underground iron ore mine. Since mining began here over 100 years ago, LKAB has produced over 950Mt of ore, yet only one-third of the original ore body has been extracted. Since mid-1999, Kiruna’s haulage level at a depth of 775m has been replaced by the next level down at 1,045m, which will support production until 2018. The operation employs 1,800 people, of whom 400 work in the mine.

In 2004, Kurina produced 14.5Mt of iron ore products out of LKAB’s total of 22.3Mt, maintaining the general relationship that it produces around two-thirds of the company’s total Swedish production. 11.5Mt of Kiruna’s output was sold as pellets. In 2004, LKAB achieved sales of iron ore products totaling 22.8Mt, of which 17/2 Mt were exported and 5.6Mt were delivered to customers in Sweden.

Geology and reserves

The Kiruna ore body was formed at around 1,600Ma following intense volcanic activity with the precipitation of iron-rich solutions on to a syenite porphyry footwall. The ore bed was then covered by further volcanic deposits (quartz porphyry) and sedimentary rocks before being tilted its current dip of 50 to 60. The ore contains a very pure magnetite-apatite mix, containing more than 60% iron and an average of 0.9% phosphorus. Black ore contains less apatite than grey ore.

The original reserve at Kiruna was some 1,800Mt. As of the end of 2004, LKAB estimated that the current proven reserve at the mine is 657Mt grading 48.3% iron, with probable reserves of 140Mt at 46.5% iron. Measured, indicated and inferred resources add a further 500Mt-plus to the inventory, with exploration continuing to identify further resources at depth.

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