SUM next WA1, page-1127

Let’s not compare with WA1, SUM is at a much earlier stage and higher risk. WA1 have a carbonatite deposit enriched in Nb and REEs. SUM have a granitic pegmatite deposit enriched in Li, Rb, Cs, Be, Sn, Ta, Nb, B, P, F and Fe. WA1 have grades from drilling, SUM have only rock chip samples from the mineralised veins and nodules.

CBMM and WA1 have niobium deposits dominated by pyrochlore, this lends itself to much simpler extraction and refining processes. This is the main reason why tantalum is more expensive than niobium.

Two separate processing schemes are utilized for niobium production. Those companies that mine pyrochlore convert the niobium oxide units into HSLA ferroniobium through the aluminothermic reduction process or by reduction in an electric arc furnace. CBMM has installed capacity for the production of a high purity oxide that can be used to produce vacuum grade ferro- and nickel-niobium as well as niobium metal ingots via electron beam refining.

The use of columbite and tantalum-bearing ores, such as tantalite, as feedstocks results in the necessity to process these materials chemically.

The extraction and refining of tantalum, including the separation from niobium in these various tantalum-containing mineral concentrates, is generally accomplished by treating the ores with a mixture of hydrofluoric and sulfuric acids at elevated temperatures. This causes the tantalum and niobium values to dissolve as complex fluorides, and numerous impurities that were present also dissolve.

Other elements such as silicon, iron, manganese, titanium, zirconium, uranium, thorium, rare earths, et c. are generally present. The filtration of the digestion slurry, and further processing via solvent extraction using methyl isobutyl ketone (MIBK) or liquid ion exchange using an amine extractant in kerosene, produces highly purified solutions of tantalum and niobium. Generally, the tantalum values in solution are converted into potassium tantalum fluoride (K2TaF7) or tantalum oxide (Ta2O5). The niobium is recovered as niobium oxide (Nb2O5) via neutralization of the niobium fluoride complex with ammonia to form the hydroxide, followed by calcination to the oxide.

There exist alternative methods which are used when they are better suited to particular local conditions. One used for a titanium-niobium-tantalum-rare earth mineral concentrate involves blending the crushed concentrate with coke and passing this through a chlorination stage which separates out the rare earths and other elements including most of the thorium. The resulting titanium-niobium-tantalum oxichloride gas is dropped in temperature which causes the iron, thorium and alkali metals to precipitate out. The cleaned titanium-niobium-tantalum oxichloride gas is then cooled to a liquid and distilled to separate out low-boiling titanium chloride gas, whereafter the niobium-tantalum oxichloride gas is further chlorinated to produce NbCl5 and TaCl5. These chlorides are fractionally distilled and the niobium chloride subsequently reacted with steam to produce the hydroxide which is calcined to oxide. The tantalum chloride is reacted with ammonium hydroxide to produce the oxide.

The primary tantalum chemicals of industrial significance, in addition to K2TaF7 and Ta2O5, are tantalum chloride (TaCl5), lithium tantalate (LiTaO3) and tantalum carbide (TaC).

Tantalum metal powder, including the precursor to capacitor grade powder, is generally produced by the sodium reduction of the potassium tantalum fluoride in a molten salt system at high temperature. The metal can also be produced by the carbon or aluminium reduction of the oxide or the hydrogen or alkaline earth reduction of tantalum chloride.