Ferro alloy metals

Figure 4.12. The position in the Periodic Table of a few classes of commercially important metals. L Light metals, R Refractory metals, F Ferro alloy metals, P Precious metals, C Coinage metals and S Soft solder metals.

On a fresh surface the metal has a steely lustre but rapidly tarnishes in air as a result of surface formation of oxide and carbonate species. For protection against oxidation the metal is usually stored in a light mineral oil. When made finely divided, eg, on being cut, it can be strongly pyrophoric, and, for this reason is used, as the ferro-alloy mischmetal, in lighter flints and ordnance. Cerium reacts steadily with water, readily dissolves in mineral acids, and is also attacked by alkafl it reacts with most nonmetals on heating. 

An alternative commercial form of a metallic mixed lanthanide-containing material is rare-earth siUcide [68476-89-1/, produced in a submerged electric-arc furnace by the direct reduction of ore concentrate, bastnasite, iron ore, and quart2. The resulting alloy is approximately 1/3 mischmetal, 1/3 sihcon, and 1/3 iron. In addition there are some ferro-alloys, such as magnesium—ferrosilicons, derived from cerium concentrate, that contain a few percent of cerium. The consumption of metallic cerium is overwhelmingly in the mixed lanthanide form in ferrous metallurgy. 

Ammoniacal leaching is typically applied to oxidic nickel-bearing materials that have been subjected to a reductive roast, which converts the cobalt and nickel present to their metallic form (or as ferro-alloys) and most of the iron to Fe11.106,107... 

Stable oxides, such as those of chromium, vanadium and titanium cannot be reduced to the metal by carbon and the production of these metals, which have melting points above 2000 K, would lead to a refractory solid containing carbon. The co-reduction of the oxides with iron oxide leads to the formation of lower melting products, the ferro-alloys, and this process is successfully used in industrial production. Since these metals form such stable oxides and carbides, the process based on carbon reduction in a blast furnace would appear to be unsatisfactory, unless a product saturated with carbon is acceptable. This could not be decarburized by oxygen blowing without significant re-oxidation of the refractory metal. 

Other metals having very stable oxides can be reduced by the aluminothermic reaction to produce useful ferro-alloys. Niobium oxide, NbO, can be reduced to form a ferro-alloy by the inclusion of iron in the reacting mixture as haematite or magnetite, depending on the niobium content which is required in the product. 

Bohonovsky, 0. Proceedings of Metal Bulletin s First International Ferro-alloys Conference, Oct. 9-11, 1977, Zurich Metal Bulletin Ltd, London, 1978, p. 86-89. 

Today Valdi recycle various metal or mineral containing by-products into ferro-alloys within a dedicated 10,000 tonne per year facility in the Feurs foundry. Primary batteries have been included as one of the recycleables within the facility since 1994. 

In the ferro-alloy industry the PAH emission is due to contact between hot metal and tarry products in electrodes and shutters. Only data for PAH emissions to water has been found for this source (29). However, assuming equal emission to water and air (50% efficiency in the wet scrubbers), this source has an emission factor of 10 g PAH per ton alloy. In a study in a Norwegian iron work, emissions to water were determined (29). PAH emission is due to the use of Soderberg electrodes. Making the same assumptions as above with the scrubber efficiency, the iron works emit 60 g PAH per ton produced iron. 

Additional alloying elements can be added to the charge as ferro-alloys such as FeSi, FeMn, FeCr, or pure such as Cu, C, Ni. However most alloys are added to the molten metal to prevent metallic losses due to oxidation. Alloying elements are usually present in the foundry in small quantities and are always stored inside the building, preferably close to the melting installation. [32, CAEF, 1997]. 

Table 10.4 summarises the costs of cast iron calculated for the 3 main cupola types compared with coreless induction furnace. Some items greatly depend on the melting device and the grade energies and fluids, metallic charge and ferro alloys. They are detailed in Table 10.5 and Table 10.6. 

The route shown in Fig. 9.12 is one which has been operated commercially in the U.K. on a fairly small scale, quite successfully. As in the case of niobium, it is convenient to use the crude ferro alloy as feed to the chlorination stage. The chloride purification stages lead to pure vanadium trichloride, which is reduced with magnesium in a manner similar to that employed for titanium, zirconium or hafnium. Some of the complexities, applicable in the latter processes owing to the volatile nature of the chlorides, are absent with vanadium. The vanadium metal sponge has some properties in common with the other metal sponges. 

According to Analyse der Metalle (44) the procedure used for ferro-alloys and for refractory metals is also valid for nickel. Samples of up to 1 g can be analyzed in the form of chips. As fluxing agents 0.5 to 1 g low carbon iron are used as basis in the combustion boat, and 0.5 g tin chips -respectively 0.25 g tin chips and 0.25 g granulated bismuth - as cover for the sample. Combustion is carried out in a tube furnace at 1350 to 1400°C. Carbon dioxide is determined by coulometry or by conductometry. 

A kind of summary of the similarities which, albeit with some uncertainties, may be evidenced between the single lanthanide and actinide metals is reported, according to Ferro et al. (2001a) in Fig. 5.13. According to this scheme the alloying behaviour of plutonium could be simulated by cerium whereas a set of similarities may especially be considered between the block of elements from praseodymium to samarium with those from americium to californium. 

Massalski, T.B., editor. Binary Alloy Phase Diagrams. Metals Park, OH Amer. Soc. Metals 1986. Mazzone, D., Rossi, D., Marazza, R., Ferro, R. J. Less-Common Met. 1982, 84,301. 

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