Ultrafine Tantalum Recovery Strategies

Pergamon 0892-6875(95)00048-8

Minerdr Engineerin& Vol. 8, No. 8, pp. 859-870, 1995 Cotwtiebt Q 1995 Elsevier Science Ltd Printed’ &at Britain. All rights reserved i 0892-6875/95 $9.50-@.00

ULTRAFINE TANTALUM RECOVERY STRATEGIES

P -_--___-iJ. .__I R.O.BUKTS,G.BORi~~Kt,S.K. YOUNG 1 and C. DEVFAUT
0 Tantalum Mining Corporation of Canada Limited, Box 2000, Lac du Bonnet, Manitoba, CanadaROE 1AO t Tantalum Niobium International Study Centre, Rue Washington 40, 1050 Brussels, Belgium
(Received I August 1994; accepted 4 April 1995)

ABSTRACT The Bernie Lake mine of the Tantalum Mining Corporation of Canada is the largest producer of tantalum concentrate, high purity spodumene, as well as cesium and rubidium ores, in North America. Tantalum is one of the “high-tech” materials, andsome of its applications are briefiy discussed. Tantalum recoveries have consistently been in excess of 70%, from ores grading less than 0. IT0 Tazi2> The prnnary target for increased recovery ts tn the ubra J#ne size ranges. This paper discusses ultrafine recovery strategies which have been attempted, including flotation and “slime” gravity concentration devices such as Battles-Mozley Separatorsand Crossbelt Concentrators. Testwork has now been carried out on the new generation of fine gravity devices; centrifugal separators. Data from four such devices - Mozley Multigravity Separator, Kelsey Jig, Falcon concentrator and Knelson Concentrator have been compared with the existing technology, which has resulted in modifications to the ftne tantalum recovery circuit. Keywords,

Gravityco~ncentration, tantalum, Tanco, centrifugal concentrators, Mozley MGS, Falcon Concentrator, Crossbeit Concentrator.
INTRODUCTION

Exploring for gold around the north shore of Bernie Lake in 1929, Jack Nutt found tin instead. In the resulting diamond drilling programme the blind Bernie Lake pegmatite was discovered. Its tin content was too low to be of interest, and its lithium content being of novalue, the deposit lay dormant until the 1950’ s, when the requirement for lithium brought renewed interest. At that time, not only the lithium, but also the cesium, rubidium, beryl and tantalum potential was discovered; however it was not until the tantalum capacitor had been developed that mining commenced. Tantalum, a member of the refractory metals group, has a very high melting point(2,996OC) and density (16,600 kg/m3). In an oxidizing environment it forms a tough, adhesive, impermeable film which, when applied anodically has outstanding dielectric properties. Tantalum is very ductile, and it can be worked hot or cold; by reaction with carbon it forms a very stable carbide. These properties are the basis of all major applications of tantalum.

Presented at Minerals

Engineering‘ 94, Lake Tahoe, USA, September 1994

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R. 0. BURT et (11.

Electronics. The electronics industry accounts for about 60% of annual tantalum production of about 3 million pounds, in the form of powder, wire, or furnace hardware for the production of tantalum capacitors. The first applications of tantalum capacitors were for the military and aerospace fields, but today allrr\mnlltPr ‘ “._......, electronic devices in telecormnunications, VCRs, radar and other commnrt l=ll=rtrnnir ‘“..Li.,-‘ cvctemc V’ , rl-- _.VV...,..._ devices use tantalum capacitors. The automotive industry has become an important consumer of tantalum capacitors: their unique ability to withstand the substantial temperature fluctuations that occur under the hood of a car (from -5OOC to +8OOC) withoutdeterioration make them the capacitor of choice. The ability to sinter tantalum to predetermined sized anodes, the high purity of the powder and its unique porous structure allow very high values of capacitance, not only by weight, but also by volume. This is of critical importance in the ever increasing trend of miniaturisation, and has resulted in close to a threefold increase in tantalum...