Arbiter Process

[jimjim]

I saw the obituary to Nat Arbiter on MEI Online. Is this the person who invented the Arbiter Process? Although I have heard of this, and I believe it is a hydromet process, can anyone give more details on the process?

[fathihabashi1928]

Yes, at that time Arbiter was working at the Extractive Metallurgical Research Division of the Anaconda Company at South Kolb Road in Tucson, Arizona. The process was developed in 1970 in a pilot plant in Tucson under the direction of Arbiter, a former professor of mineral processing at Columbia School of Mines in New York City. A commercial 91 tonnes /day copper plant went in operation at Anaconda, Montana few months later. The leaching plant was composed of 10 intensely agitated vessels 14 cubic meters each and 5 counter-current decantation thickeners, with the first overflow filtered to form the pregnant solution. The process is based on leaching chalcopyrite concentrates with ammonia at 75-80oC in presence of oxygen to form copper ammine sulfate and iron hydroxide:

2CuFeS2 + 12NH3 + 8½O2 + 2H2O → 2[Cu(NH3)4]2+ + 4NH4+ + 4 SO4 + Fe2O3

After filtering the solids, copper was extracted by LIX-65N, stripped by sulfuric acid, and electrolyzed to give metallic copper. Lime is then added to the raffinate, and the slurry boiled to distil ammonia for recovery and precipitate gypsum for disposal:

(NH4)2SO4 + Ca(OH)2 → 2NH3 + CaSO4.2H2O

This ammonia recovery step as well as that from the residue washings proved to be technically difficult and economically unsound and was the main reason for the shut down. More details of the process with a flowsheet, a photograph of Arbiter, and the circumstances under which the process was deveolped is to be found in:
1) F. Habashi, Readings in Historical Metallurgy, Volume 1. Changing Technology in Extractive Metallurgy, Métallurgie Extractive Québec, Québec City 2006, 800 pages. Published by Métallurgie Extractive Québec and distributed by Laval Univeristy Bookstore in Quebec City,Canada
2) F. Habashi, “Abandoned But Not Forgotten. The Recent History of Copper Hydrometallurgy,” Metall 60 (7–8), 459–465 (2006), reprinted in Symposium on Copper Hydrometallurgy pp. 3–19, edited by P. A. Riveras et al., CIM, Montreal 2007.
Fathi Habashi, Professor Emeritus, Laval University, Quebec City, Canada. E-mail: [e-mail]

[jimjim]

Thanks for your prompt response