Metallothermic Process

Ferro-alloys Master alloys containing a significant amount of bon and a few elements more or less soluble in molten bon which improve properties of bon and steels. As additives they give bon and steel better characteristics (increased tensile sbength, wear resistance, corrosion resistance, etc.). For master alloy production carbothermic processes are used for large-scale ferro-sihcon, ferro-chromium, ferro-tungsten, ferro-manganese, ferro-nickel and metallothermic processes (mainly alumino and sihco-thermic) for ferro-titanium, ferro-vanadium, ferro-molybdenum, ferro-boron. 

Today electrolytic methods account by far for the largest amounts of rare earth metal produced throughout the world - thousands of tons per year. The main reason for this is that the electrolytic method is cheaper than any metallothermic process one can devise, either practically or theoretically. However, because of the reactivity of the materials the electrolytic method is usually limited to operating temperatures of 1100°C or lower. Because of this limitation generally only the first four lanthanide metals. La, Ce, Pr and Nd (and their mixture-mischmetal), are prepared by electrowinning. Limited quantities of... 

Keywords Intermetallics, Ni-based alloys, Cr-based alloys, Metallothermic process... 

Metallothermic process Electrowinning of Na and Clj Metal reductant makeup Chlorine makeup Heat and energy losses Total... 

FFC process exhibits advantages compared to the other metallothermic processes such as Kroll process, in particular a lower cost and far less polluting, but it has major drawbacks ... 

Pure titanium metal is produced from TiC by metallothermic processes using sodium metal (Hunter process) or magnesium metal (Kroll process) as reductive agents at temperatures of 800-850 °C... 

PRODUCTION OF MOLYBDENUM CONTAINING IRON BASED ALLOYS VIA METALLOTHERMIC PROCESSES... 

Keywords Metallothermic process. Mill-scale, Fe-based alloys Abstract... 

Mironov, K.E., G.P Brygalina, l.G. Vasil eva and E.D. Popova, 1971, Process of phosphidization of europium sesquialteral oxide, in Metallothermic Processes in Chemistry and Metallurgy (Nauka, Novosibirsk) pp. 116-120. In Russian. 

Very reactive metals, eg, titanium or 2irconium, which in the Hquid state react with all the refractory materials available to contain them, also require reduction to soHd metal. Titanium is produced by metallothermic reduction of its chloride using Hquid magnesium at 750°C (KroU process). 

The spent salt from MSE is currently sent to an aqueous dissolution/carbonate precipitation process to recover plutonium and americium. Efforts to recover plutonium and americium from spent NaCl-KCl-MgCl2 MSE salts using pyrochemistry have been partially successful (3). Metallothermic reductions using Al-Mg and Zn-Mg alloys have been used in the past to recover plutonium and americium, and produce salts which meet plant discard limits. Attempts at direct reductions of MSE salts using... 

Examples of metals which are prepared by the metallothermic reduction of oxides include manganese, chromium, vanadium, zirconium, and niobium. In a manner similar to the production of magnesium by the Pidgeon process, some of the rare earth metals have been produced by the metallothermic reduction-distillation process. 

Metallothermic reduction of chlorides has been the basis of some very important processes for reactive metals production. Examples include the Kroll and Hunter processes for the preparation of zirconium and titanium, and calcium or lithium reduction processes for the rare earths. 

Due to the great similarity of the chemical properties of the rare earth elements, their separation represented, especially in the past, one of the most difficult problems in metallic chemistry. Two principal types of process are available for the extraction of rare earth elements (i) solid-liquid systems using fractional precipitation, crystallization or ion exchange (ii) liquid-liquid systems using solvent extraction. The rare earth metals are produced by metallothermic reduction (high purity metals are obtained) and by molten electrolysis. 

SmCl3 resulted in the reduction only to SmC. From NdCl3 + Ca with the addition of Fe powder, the alloy Nd2Fei7 was obtained. In a discussion of the results it was observed that the products obtained at ambient temperature by mechanical alloying are the same which result from the conventional metallothermic reduction of the rare earth halides. However, the metallothermic reduction requires a temperature of 800-1000°C for the reduction of the chlorides and 1400-1600°C for the fluorides. The products of the mechanical process, on the other hand, are fine, amorphous or microcrystalline, highly reactive metal powders mixed with CaCl2. 

The yield and rate of the tantalothermic reduction of plutonium carbide at 1975 K are given in Fig. 3. Producing actinide metals by metallothermic reduction of their carbides has some interesting advantages. The process is applicable in principle to all of the actinide metals, without exception, and at an acceptable purity level, even if quite impure starting material (waste) is used. High decontamination factors result from the selectivities achieved at the different steps of the process. Volatile oxides and metals are eliminated hy vaporization during the carboreduction. Lanthanides, Y, Ti, Zr, Hf, V, Nb, Ta, Mo, and W form stable carbides, whereas Rh, Os, Ir, Pt, and Pd remain as nonvolatile metals in the actinide carbides. Thus, these latter elements... 

This process is particularly useful for the preparation of pure plutonium metal from impure oxide starting material (111). It should also be applicable to the preparation of Cm metal. Common impurities such as Fe, Ni, Co, and Si have vapor pressures similar to those of Pu and Cm metals and are difficult to eliminate during the metallothermic reduction of the oxides and vaporization of the metals. They are eliminated, however, as volatile metals during preparation of the actinide carbides. 

Protactinium metal was first prepared in 1934 by thermal decomposition of a pentahalide on a hot filament 50). It has since been prepared from PaF4 by metallothermic reduction (Section II,A) with barium 26, 27, 34,102), lithium 40), and calcium 73, 74). However, the highest purity metal is achieved using the iodide transport (van Arkel-De Boer) process (Section II,D). 

Of those factors that have proved a disincentive to the wider application of the metals perhaps none has proved more formidable than cost. Unquestionably some rare earth metals are expensive when compared with many of the more common metals but then others, such as the commercial grades of lanthanum and cerium produced by electrolytic methods, are relatively inexpensive. Unfortunately, for most rare earth metals one must use a metallothermic reduction process that is inherently costly to operate. However, while there is a wide variation in the price of the various metals, from 50 - 7,000 per lb., the overall picture is one of relative price stability when judged against the movements of many other metals. To some extent this stability has been born out of the need to encourage potential users to adopt a particular metal in the face of a competitive product while in other cases it reflects more the economy of scale that has been possible once production has passed a given level. 

Recovey. The final step in the chemical processing of rare earths depends on the intended use of the product. Rare-earth chlorides, usually electrolytically reduced to the metallic form for use in metallurgy, are obtained by crystallization of aqueous chloride solutions. Rare-earth fluorides, used for electrolytic or metallothermic reduction, are obtained by precipitation with hydrofluoric acid. Rare-earth oxides are obtained by firing hydroxides, carbonates or oxalates, first precipitated from the aqueous solution, at 900°C. 

Two principal methods of producing magnesium metal [264] are being used metallothermic reaction and electrolysis of molten salts. Two-thirds of the magnesium production is obtained by the electrolytic process. On the market there are few producers of magnesium. Therefore, process research and development work have been conducted by these producers, and the results have often been kept secret. Hence, there are few publications in this field, except for patents. 

The metallothermic reduction process has lost much of its importance in recent years owing to the increased costs of Al and Si powders and the necessity for using pure and expensive raw materials. 

Magnesium metal is produced primarily by either thermal or electrochemical processes. The thermal process operates at temperatures over 1200°C and utilizes a metallothermic reduction in which magnesium metal volatilizes from MgO and is condensed to recover the metal. The electrochemical process is based on the electrolysis of fused anhydrous magnesium chloride. 

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