Tantalum and Niobium Experience

Tantalum and Niobium
Since 1982, the dramatic increase in demand for tantalum has been fueled at a rate of 10% per year by the electronics industry (Roskill Information Services). Characterized by a low natural abundance, few known deposits, sporadic supply and difficult metallurgy, Ta is a high tech metal of the future. SGS Minerals Services has contributed to many tantalum projects over the years and can bring an integrated suite of services to either the exploration or developmental stages of Ta and Nb projects.

MINERALOGICAL INVESTIGATIONS
Early identification of the Ta or Nb minerals in an ore as well as their deportment, textural associations and micro-chemical composition plays a critical role in determining a deposit’s amenability to metallurgical processing.

Mineral Identification
Owing to the extensive solid solution between Ta, Nb and Fe, identification of Ta and Nb minerals is critical to the evaluation of mineral recovery and deposit economics. For example, the sample to the right contains intergrown plumbopyrochlore (ppc) (Pb,U,Ca) Nb O (OH), pyrochlore (pc) (Ca,Na) (Nb,Ta) O  (OH,F) (red arrow), ilmenorutile (Ti,Nb,Fe) O (ilmr) and quartz (qtz) gangue.

Deportment and Texture
Deportment and textural associations define liberation and locking characteristics that are crucial for metallurgical processing. For instance, the back-scattered electron image at right shows pyrochlore (white) locked with gangue minerals, implying poor liberation and recovery, and suggesting the need for regrinding.

Chemical Composition
Quantification of the chemical composition assists in the elemental allocation among Ta and Nb species. It also assists in the metallurgical mass balance calculations used to optimize recovery. Deleterious elements can create environmental concerns or result in smelter penalties.

In the case to the left, ferrotapiolite (bright white) (Fe,Mn)(Ta,Nb) O  has a different trace element composition (SEM spectrum) from pyrochlore and columbite, and may contain Sn, U, Th and Pb.

METALLURGICAL PROCESSING
Mineralogical data provides the grain size and textural parameters needed to establish and optimize a metallurgical flowsheet. Depending on the grain size, textural associations and accessory minerals present, a variety of different separation strategies can be used to concentrate Ta and Nb minerals, including grinding, conventional and centrifugal gravity separation, regular or high intensity magnetic separation and advanced flotation techniques.

Grinding
Proper grinding parameters ensure effective liberation. For Ta or Nb processing, it is particularly important to minimize the production of fines.

Conventional and Centrifugal Gravity Separation
Ta and Nb minerals are easily separated from gangue due to their high specific gravity. SGS Minerals Services has a wide variety of bench and pilot scale gravity separation equipment available for testing.

Magnetic Separation
Low and high intensity magnetic separation can separate Ta and Nb minerals of varying from quartz-calcite gangue using bench-scale magnetic susceptibility during final up¬grading. Here tantalite is being separated high intensity magnetic separation.

Flotation
SGS Minerals Services has developed new flotation reagents that yield excellent primary separations between Ta and Nb minerals and gangue. The sample below right is a highly liberated Ta-Nb ore (pyrochlore, columbite) (bright white) with a calcite-quartz gangue (dull grey), which responded well to these reagents.

Traditional flotation technology is also used to remove or concentrate associated sulphide minerals. Reverse flotation procedures and regrinding circuits then are used to prepare final Ta or Nb concentrates.

Make the right choices for the right reasons. Mineralogical scoping studies early in a project result in efficient metallurgical bench-scale and piloting later. Maximize the return on your investment.

Innovative solutions for practical problems
Experience Record 1990-Present

TANTALUM AND NIOBIUM
Ta-Nb minerals are brittle, heavy and typically highly intergrown with sulphide and other oxide minerals. To achieve cost effective operation, it is critical to evaluate size and texture, to define the grinding parameters that ensure proper liberation. A variety of different separation strategies are used to separate these minerals, including conventional and centrifugal gravity separation, regular or high intensity magnetic separation and flotation. New flotation reagents are available to allow an excellent primary separation. As well, flotation is used to remove associated sulphide minerals. Reverse flotation-regrinding circuits are used to prepare final concentrates.

Code:
lab = Laboratory test work, GRA = Gravity, MAG = Magnetic separation,
FLT = Flotation, MIN = Mineralogy, ROAST = Roasting, LCH = Leaching,
PPT = Precipitation, SX = Solvent extraction.