Hunter 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. 

Main uses ofNa alloys. Hypoeutectic Al-Si alloys (from 5 mass% Si to the eutectic) through the so-called modification (structural modification of the normally occurring eutectic) achieve somewhat higher tensile properties and improved ductility. Modification is obtained by the addition of elements such as Na (or Sr, Ca, Sb) and results in a finer lamellar or fibrous eutectic. Phosphorus, which reacts with sodium, interferes with the modification mechanism. Sodium can be used as the reductant of several chlorides in the preparation of metals such as Ti (Hunter process), Zr, Hf, Nb, Ta. 

Hunter process. Production of titanium by reduction with sodium in an atmosphere of argon or helium. 

Derivation (1) Reduction of titanium tetrachloride with magnesium (Kroll process) or sodium (Hunter process) in an inert atmosphere of helium or argon. The titanium sponge is consolidated by melting. (2) Electrolysis of titanium tetrachloride in a bath of fused salts (alkali or alkaline-earth chlorides). 

Titanium is generally produced by the Kroll or Hunter process and recently also by energy saving deposition from high-temperature salt baths as known for coating . Many attempts have been made to replace the high-tempeiatuie process with a low-temperature electroplating process. Brenner et al. listed more... 

Hunter process. As initiaUy practiced at General Electric (GE) in 1910 by Mathew A. Hunter, the Hunter process reacted titanium tetrachloride with elemental sodium in an inert-gas atmosphere in a sealed steel retort at a temperature of about 900 C. Titanium sponge and molten sodium chloride are formed upon completion of the reaction ... 

Advantages and drawbacks of the two processes. By contrast with the Kroll process, the Hunter process offers the following main advantages ... 

Hunter process TiCl,(g) + 4Na(l) —> Ti(s)+ 4NaCI(l) Fines produced during metallothermic reduction of titanium tetrachloride with sodium metal at 1000°C Alta Group (Utah), Chinese producers (Zunyi, Fushun, Bongen) 22 Spongelike Chloride (Cl) 120-150... 

Titanium is produced by chlorination of rutile (Ti02, 95%), synthetic rutile prepared from ilmenite or titanium slug of a high content with cokes at 1000 C to give crude TiCU, which is then purified by distillation and by reduction of the purified TiCU with Mg at about 900 °C under argon atmosphere (Kroll process), or by two step reduction with sodium metal (Hunter process) [2-5]. 

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... 

Titanium was first produced by the Hunter process [6] but this has been superseded, except for special applications, by the Kroll process [4, 6] which entails the carbochlorination of rutile and ilmenite to obtain titanium tetrachloride, followed by metallothermic reduction with magnesium. 

These and other standard commercial methods of titanium production, such as the sodium-reduction (or Hunter) process, the direct-oxide-reduction process, and the electrolytic process, have been described in detail by MCQUILLAN [Mcq56, Chap. 2], Hoch [Hoc73 ], and ZwiCKER [Zwi74, pp. 21-27], while some new approaches developed in the Soviet Union have been outlined by Reznichenko and coworkers [Rez82, Rez82 J. 

Armstrong A process for making titanium metal powder, developed by Don Armstrong at International Titanium Powder (ITP) in Woodbridge, IL. Acquired by Cristal USA in 2008 and commercialized in Ottawa, IL, since 2011. Essentially a continuous version of the Hunter process, in which titanium tetrachloride is reacted with metallic sodium. 

Hunter process A process used for the production of titanium metal by the reduction of titanium tetrachloride with sodium metal. 

Kroll process A process used in the production of certain metals such as titanium by reduction of its chloride with magnesium metal. It was named after William J. Kroll, who invented the process in 1937, replacing the earlier Hunter process. The process involves reducing refined rutile from its ore at 1,000°C within a fluidized bed with chlorine gas to... 

Miller RJ, Smith CR, DeMaster DJ, Pomes WL (2000) Feeding selectivity and rapid particle processing by deep-sea megafaunal deposit feeders A " Th tracer approach. J Mar Res 58 653-573 Moore RM, Hunter KA (1985) Thorium adsorption in the ocean - reversibility and distribution amongst particle sizes. Geochim Cosmochim Acta 49 2253-2257 Moore RM, Millward GE (1988) The kinetics of reversible Th reactions with marine particles. Geochim Cosmochim Acta 52 113-118... 

Another chloride reduction process, originally developed by Hunter for titanium tetrachloride and known by his name, uses sodium as the reductant. In this process liquid sodium and titanium tetrachloride are simultaneously metered into a steel retort under an argon atmosphere. The highly exothermic reduction reaction... 

The value of EM for a cooperative self-assembled structure provides a measure of the monomer concentration at which trivial polymeric structures start to compete, and therefore EM represents the upper limit of the concentration range within which the cooperative structure is stable (Scheme 2). The lower limit of this range is called the critical self-assembly concentration (csac) and is determined by the stoichiometry of the assembly and the strength of the non-covalent binding interactions weaker interactions and larger numbers of components raise the csac and narrow the stability window of the assembly (8). Theoretical treatments of the thermodynamics of the self-assembly process have been reported by Hunter (8), Sanders (9), and Mandolini (10). The value of EM is lowered by enthalpic contributions associated with... 

The following procedure describes the iodination process for the Bolton-Hunter reagent and its subsequent use for the radiolabeling of protein molecules. Modification of other macromolecules can be done using the same general method. For particular labeling applications, optimization of the level of iodine incorporation may have to be done to obtain the best specific radioactivity with retention of biological activity. 

On request, Mr. Hunter promptly forwarded me samples of silver in which the gold is growing and some grown-up gold, said to have been produced by his secret process. I have not made analyses of the samples, which are here exhibited. (Baskerville 1908, 48)... 

By sending legitimate chemists such as Ramsay and Baskerville samples to test, Hunter was following in the footsteps of Emmens, who in 1897 had sent samples and instructions for repeating his process to Sir William Crookes, who was unable to reproduce Emmens s results. In 1898, Emmens launched his Argentaurum Company, which advertised that for each ounce of silver submitted by investors it would return 3/5 of an ounce of gold. Emmens s efforts to start the company failed, though, when his patent application for the process was turned down (Nelson 2000, 58). 

Hunter A process for making titanium metal by reducing titanium tetrachloride with sodium ... 

The process is operated in heated, batch reactors under an inert atmosphere. Two companies (Deeside Titanium, North Wales, and New Metals Industries, Nihongi, Japan) operate a one-stage process. Reactive Metals Industries Company, Ashtabula, OH, operates a two-stage process in the first stage, at 230°C, the trichloride and dichloride are formed. In the second, more sodium is added and the temperature is raised to 1,000°C. The sponge product is mixed with sodium chloride, which is leached out with dilute hydrochloric acid. Based on the work by M. A. Hunter at Rensselaer Polytechnic, New York in 1910. See also Kroll. 

Bollworm/budworm complex, 5 9 Bolometers, 19 143-144 Bolton-Hunter reagent, 21 274 Boltzmann distribution, 14 657 26 1035 Boltzmann s constant, 26 1035 numerical value of, 24 434 Boltzmann s law, 14 662 Bolzano magnesium manufacturing process, 15 342... 

Hunig s Base, 2 549t Hunter Color Spaces, 7 321 Hunter-Nash procedure, 10 757 Huntsman fixed-bed maleic anhydride process, 15 501... 

Dr. Beverly Lenny, a college counselor at Hunter College High School in New York, says she steers her students toward the paper application. Her main objection to the online version is her students tendency to treat it casually. "The application process is about learning how to present yourself well. You must carefully show your readers your very best. The casualness with which some students approach online applications interferes with this sense of purpose."... 

The beginning of modeling of polymer-electrolyte fuel cells can actually be traced back to phosphoric-acid fuel cells. These systems are very similar in terms of their porous-electrode nature, with only the electrolyte being different, namely, a liquid. Giner and Hunter and Cutlip and co-workers proposed the first such models. These models account for diffusion and reaction in the gas-diffusion electrodes. These processes were also examined later with porous-electrode theory. While the phosphoric-acid fuel-cell models became more refined, polymer-electrolyte-membrane fuel cells began getting much more attention, especially experimentally. 

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