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Industrial Processes Title

Remote sensing makes sense for mining

   
 

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Four organisations with experience in mining, geodata processing and remote sensing have collaborated in using various spatial analysis methods, including a Geographical Information System (GIS), to correlate a wide variety of geographical, geological, geophysical, meteorological and industrial data of interest to the mining industry. Much of the information was gathered by remote sensing from aircraft and satellites. By focusing on three sites in Spain and Germany, the partners have demonstrated the potential of dedicated digital analysis procedures for mineral prospecting and for environmental monitoring of activities of the mining industry.

As known deposits of valuable minerals are consumed, the mining industry needs to employ increasingly sophisticated techniques in its search for new reserves. At the same time, mining companies are becoming more sensitive to environmental issues and are looking for new tools to help them monitor and reduce the damaging effects of their operations.
This project arose out of discussions between mining companies and consultants who recognised the potential for combining prospecting and monitoring techniques. The project had two main objectives. First, the partners wanted to find ways to use existing data and new remote sensing data in the search for hidden mineral deposits. Second, they wanted to extend the use of remote sensing for the assessment, surveillance and monitoring of the environmental impact of mining operations. The main technical challenge was to make the system sufficiently flexible to accommodate the requirements of all the potential users.
Until now there has been no systematic use of data for both exploration and monitoring. Remote sensing, from aircraft and satellites, is a powerful technique in mineral prospecting which can be adapted for environmental monitoring. The partners in this project brought data from remote sensing together with ground measurements in a GIS, a computer database used to correlate spatial data with an underlying map of the area.

Three test sites

The project started in November 1992, with research focusing on three sites: one in central Spain, one in southern Spain and one in the Erzgebirge of eastern Germany.
• The Pyrite Belt covers more than 8,000 km2 and stretches from south-western Spain into Portugal. The deposits include copper, zinc, lead, tin and manganese. It has been mined for more than 4,000 years and several companies are still extracting there. This long history of exploitation has left a legacy of spoil heaps which cause serious environmental problems. The Mediterranean climate is ideal for evaluating the ability of remote sensing and GIS techniques to detect and monitor contamination from mining activities. The project concentrated on the central part of the belt in the Huelva province of Spain, one of the few places of active mining in Europe.
• The Alcudia Anticline is located to the east of the Pyrite Belt, south of Almadén. It has been intensively mined for lead, zinc and silver since Roman times. There is no mining there now, but more than 500 small mines were extracting only a century ago. It is not a promising area for exploration, but is ideal for using remote sensing to investigate contamination from old mines in numerous small places. Roman contamination is especially interesting since it is already covered by soil and difficult to map.
• The Eastern Erzgebirge, on the border between Germany and the Czech Republic, is one of the most extensively mined areas in Europe. Deposits of tin, tungsten, uranium, gold, silver and zinc have been exploited for more than 1,000 years. The region is characterised by a high population density and large forests. Environmental damage caused by mining and related heavy industry is widespread and can be severe.
The first step was to collect available information for each of the three areas and integrate it in the GIS database. For the Erzgebirge, for example, there were 85 'layers' of information, including 30 sets of remote sensing data. Information included such things as satellite images and radar maps, aerial photographs, soil geochemistry, gravity surveys, aeromagnetic data, geological maps, topographical maps, sources of pollution, meteorological records, and so on. Similar databases were compiled for the two Spanish areas. New surveys were undertaken in some areas where the need arose.
Once all these data had been converted into GIS format, researchers could relate numerous different measurements to each other at each point on the ground. Complex statistical methods were devised to restore gaps in irregular and incomplete data sets and to explore the relationships between different types of data and how they relate to geological and environmental features of interest. In this very productive collaboration, the partners used the databases to pursue 15 different lines of inquiry.

Remarkable results

The group attempted to identify hidden mineral reserves by using modelling of geophysical data, extrapolating from surface data and by simulating the local geology. Possible new target areas have been identified in the Erzgebirge. Further detailed research along these lines promises to be fruitful.
The most remarkable results were achieved in environmental monitoring. By sophisticated analysis of data in the Erzgebirge, the researchers showed that the loss of forest by acid rain which has taken place in the last few decades is not directly linked to the presence of ore mining activities. Damage to the forests, and associated poor air quality, is rather governed by topographical and climatological factors and the presence of lignite-fired power stations and associated heavy industry.
Work on a site in the Alcudia Anticline demonstrated the potential of remote sensing to detect 2,000-year-old mining contamination through its effect on vegetation, even where the contamination is now covered by half a metre of new soil. The method, however, needs to be modified for other sites where soil and vegetation are different. Another important finding was that ancient lead and silver extraction does not appear to have had a harmful effect on recent vegetation now covering the site. The partners believe that using GIS and remote sensing techniques to identify ancient contamination sites saves about a third of the time and manpower required by traditional survey methods.
One advantage of the GIS approach is that smaller countries and companies can have access to data that has historically been the preserve of large multinational companies with well-resourced exploration divisions. Small mining companies should now be in a better position to compete.
Although this project was designed for the mining industry, especially for the exploitation of resources and resulting environmental impact, it is hoped that the principle of correlating many different sets of information will in future be applied to a wide range of industries who need to handle specialised data. The mathematical tools developed in the project should have a wide market, not only in the mining field.

 

Project Title:  
New technologies for mineral exploration and surveillance of environmental impacts of mining operations based on remote sensing and multidata set analysis

Programmes:
Industrial and Materials Technologies (BRITE-EURAM/CRAFT/SMT)

Contract Reference: BE-5361

Cordis DatabaseFor more information on this project,
go to the CORDIS Database Record

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