The extraction and refining of tantalum, including the separation of niobium in various concentrates of minerals containing tantalum, is generally carried out by a mixture of hydrofluoric and sulfuric acids at elevated temperatures. (> 3,000 degrees).
This process makes the values of tantalum and niobium in high percentage to dissolve complex fluorides that will make disappear numerous impurities present. Other elements such as silicon, iron, manganese, titanium, zirconium, uranium, thorium, rare earths, etc. ... that are generally present.
The filtration of the suspension in the decantation, and its subsequent processing by a solvent extraction using metal isobutyl ketone (MIBK) or a liquid ion exchange using an amine extractor in kerosene, produces highly purified solutions of tantalum and niobium. Generally, tantalum values in solution are converted to potassium tantalum fluoride (K2 TaF7) or tantalum oxide (Ta2O5).
Niobium is recovered in form of niobium oxide (Nb2O5) by a neutralization of the niobium fluoride complex with ammonia to form the hydroxide, followed by a calcination to the oxide.
There are some other alternative methods that are used when they adapt better local conditions. One of them is used for a mineral concentrate with titanium, niobium, tantalum, rare earth, involves mixing the crushed concentrate with coke and going through a chlorination step that separates the rare earths and other elements, including most of the thorium.
The result of niobium tantalum titanium oxychloride gas is dropped at the temperature that causes the iron, thorium and alkali metals to precipitate. The cleaned titanium niobium tantalum oxychloride gas is then cooled to a liquid state and distilled to remove gas under the boiling point of titanium chloride, after which the niobium tantalum oxychloride gas is more chlorinated to produce NbCl 5 and TACL 5.
These chlorides are fractionally distilled and the niobium chloride is subsequently reacted with steam to produce the hydroxide that calcines the oxide. The tantalum chloride is reacted with ammonium hydroxide to produce the oxide.
The primary tantalum chemicals of industrial importance, in addition to K2 TaF7 and Ta2O5, are tantalum chloride (TACL5), lithium tantalum (Lita O3) and tantalum carbide (TaC).
Tantalum metal in powder, including the precursor to the powder condenser, is generally produced by the reduction of the sodium of potassium tantalum fluoride in a system of molten salt at high temperature. The metal can also be produced by reducing carbon or aluminum oxide or hydrogen or alkaline earth-reducing tantalum chloride.
The process choice is based on specific application and whether the resulting tantalum will be further consolidated by the transformation into ingot, sheet, bar, tube, wire or other articles of manufacture.
The consolidation of metallic powder for ingot and the processing into various metallurgical products starts with either arc melting vacuum or electrons melting beam of metal raw materials, composed from powder or high purity debris where the elements with points of boiling greater than tantalum are not present.
Double and triple ingots of fusion in achieving of a very high level of purification with respect to the metallic and interstitial ones. The ingots are used to produce the different metallurgical products named above. Ingot values are also used for the production of such alloys such as tantalum 10% tungsten. Ingot and pure tantalum waste are used in the production of alloys for earth and air-based turbines.
Primary or secondary Processor?
In the tantalum industry, a distinction is often made between "primary processors" and "secondary processors", which indicates the difference in which a company fits into the supply chain.
The distinction is relevant if a company is considered a "smelter" for mineral in the distribution of the mineral appears in a conflict: the primary processors are the equivalent of foundries, while the secondary processors are the water industry down".
Primary processors are those that have the ability to process primary raw materials, whether they are tantalum mineral concentrates or slag. A main processor is generally also capable of processing secondary concentrates (Columbite or Struverite), synthetic concentrates and / or scrap. The products of a primary processor can be anything from the tantalum most common an intermediate 'K-salt' (K2 TaF7), through high purity oxides or condensing degree of tantalum metal powder.
Secondary processors are those that cannot handle minerals or slags, but can use tantalum intermediate states and in the end product processes. For example, a secondary processor may purchase K-salt, tantalum metal powder or tantalum ingot, and then, additionally, apply chemistry and / or metallurgical processing (e.g., reduction, or arc melt vacuum, or injection molding). Molding powder and produce final products such as oxides, grade condenser powder, or metal products, such as tubes or wire.
The tantalum powder condenser provides about 25% of the market demand for all tantalum shipments. Additional quantities related to capacitors are consumers for tantalum wire at the lead anode, as well as for tuning of tray assemblies, molds and shields as components for the anode tuning furnaces.
Other plaintiffs are castings for tantalum cast steel, for the use in chemical products with tantalum and in the electronics of audio and video components.