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UV LASER PROSPECTING : FIELD TEST OF PREUSSAG'S CLOSE RANGE SYSTEM.

Objective

THE CONTRACT IS FINISHED AND THE FINAL REPORT IS WELL DOCUMENTED AND ANSWERS TO ALL OBJECTIVE SET IN THE CONTRACT: THE TEST IN SEVERAL AREAS OF TURKEY HAS BEEN PERFORMED IN DIFFICULT TERRAIN CONDITIONS. DESPITE SEVERAL TRUCK FAILURES AND SYSTEM DIFFICULTIES THE EXPERIMENT WAS SUCCESSFUL FOR THE DETECTION OF SCHEELITE, HYDROZINCITE AND FLUORITE. IN THE NEAR ULTRAVIOLET, REE TEST FAILED DUE TO A WEAK OPTIC SIGNAL AND ALSO TO THE EXTREMELY FINE GRAINED BASTNAESITE (50 MICRONS) DURING THE TEST ON THE KIZILCAOREN RARE EARTH DEPOSIT.
THE SURVEY HAS COVERED 1750 KM AT A COST OF 222 DM KM AND HAS IDENTIFIED 68 TARGETS OF WHICH 50% MAY BE OF INTEREST. COST MAY BE FURTHER REDUCED.
IT MAY BE CONCLUDED THAT THE SYSTEM IS OPERATIONAL FOR THE MINERALS MENTIONED ABOVE WITH THE PRESENT MOUNTED SYSTEM WHICH IS ABLE TO OPERATE IN DAYLIGHT CONTRARILY TO OTHER METHODS. ITS MAJOR DRAWBACK IS THAT THE SURVEY IS LIMITED TO A DRIVEABLE PATH.
A mobile fluorosensor system has been developed for the prospecting of fluorescent minerals and related deposits. The system comprises a truck mounted container hosted laser system in close range application with the ability to perform a continuous survey over the driven path for the detection of fluorescent minerals (ie scheelite, hydrozincite, fluorite and bastnaesite).
The system surveys a 10 metre wide strip in front of the moving 4 wheel drive truck with overlapping pixels providing total coverage up to a vehicle speed of 45 kilometre per hour.
The system has been field tested to obtain data on the system's reliability under field conditions and to establish a firm cost and logistic structure. The method was found to be very selective with a low number of samples needed mainly for a mineral check and grade. Performance and costs depend on favourable field conditions.

The evaluation of the photoluminescence parameters of 500 mineral samples representing 70 different minerals shows that ore minerals such as scheelite, powellite, fluorite, barite and uranium minerals, as well as secondary minerals related to ores (eg hydrozincite), can be determined or determination can be supported based on specific peak wavelengths of emission and lifetimes. The occurence of these minerals in outcrops, scree or as coatings facilitate the use of a photoluminescence sensor in prospecting.
Detection limits for such a sensor were calculated and established in laboratory and field tests. The sensor is based on an ultraviolet (UV) excimer laser as the light source and photomultipliers for signal detection. The maximum size of an area observed under bright sunlight from a distance of 10 metre is approximately 0.1 square millimetre. In this area a scheelite sample of only 1 square millimetre should theoretically be detectable whereas in practice the minimum size was 6 square millimetre.

A mobile fluorosensor system was developed for the prospecting of fluorescent minerals and related deposits, which was tested in 1987 in Turkey.
The tested fluorosensor system is a truck mounted (Mercedes Unimog 1300 L) container hosted laser system in close range application, with the ability to continuously survey in the driven path, for the detection of fluorescent minerals (ie, scheelite, hydrozincite, fluorite and bastnaesite).
The objective of the test was to obtain data on the systems reliability under field conditions and to establish a firm cost and logistic structure.

The mobile fluorosensor is a fully operable system for the prospecting of fluorescent minerals with a priority on scheelite.
The system is very selective with a low number of samples needed, most of them only for checking mineralogy and grade.
The fluorosensor system had shortcomings against other reconnaissance methods due to:
a random survey (driveable path);
preconditions of mineral occurrences (as minerals have to be on surface, should be fresh and have to show a minimum fluorescent plane with respect to the detection limit);
random conditions of activated fluorescent minerals which are influenced by ions acting as killers and quenches of fluorescence and a saturation phenomenon.
Performance and costs are related to the driven km per day (ie, depend on favourable field conditions). The fluorosensor method is open for further development and applications in a broader wavelength range.
DURING THE PAST FOUR YEARS PREUSSAG AG METALL UNDER CONTRACT NO MSM-003-D (B) HAS DEVELOPED A VEHICLE-MOUNTED FLUOROSENSOR FOR PROSPECTING FOR FLUORESCENT MINERALS ON THE EARTH'S SURFACE.
THE OBJECTIVE OF THE FIELD TEST OF THIS "CLOSE RANGE SYSTEM" IS TO PROVE OR ENHANCE ITS FIELDWORTHINESS AND TO ESTABLISH PERFORMANCE AND COST DATA FOR ITS APPLICATION IN GEOGRAPHIC AND CLIMATIC ZONES TYPICAL OF EUROPE. IN A EUROPEAN ENVIRONMENT THE SYSTEM HAS TO COMPETE WITH THE CLASSICAL PROSPECTING METHOD OF GEOCHEMICAL SAMPLING.
BECAUSE OF PREUSSAG'S EXISTING INFRASTRUCTURE IN TURKEY THE FIELD TESTS SHALL BE CARRIED OUT IN THAT COUNTRY ON SEVERAL TEST SITES.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Preussag AG
Address
Karl-wiechert-allee 4
30625 Hannover
Germany

Participants (2)

TECHNICAL UNIVERSITY OF MUNICH
Germany
Address
21,Alte Akademie 16
85350 Freising
UNIVERSITA' DEGLI STUDI DI TRENTO
Italy
Address

Trento