Rozan process

The pig lead contains about 2 per cent, of silver, and there are three processes for its desilverization, the final stage of each being cupellation. In the almost obsolete PaUinson process the lead is melted and then allowed to crystallize. The first fractions consist of almost pure lead, and the crystals are removed by means of perforated ladles. The crystallization is continued until the residual lead contains about 1 per cent, of silver. In the Rozan process the molten metal is agitated by revolving paddles or jets of steam, and the concentration continued up to 2 per cent. In the Parke process the silver is extracted from the... 

Luce-Rozan A variation of the Pattinson process, in which steam is blown through the molten metal as cold water is sprayed on the surface. 

Pattinson (1) A process for extracting silver from lead by selective crystallization. When molten lead is cooled, the first crystals of lead contain less silver than the residual melt. Repetition of this process a number of times yields a silver concentrate which is further purified by cupellation. Invented in 1833 by H. L. Pattinson. Largely superseded by the Parkes process, except for metals containing bismuth for which the Pattinson is the preferred process. See also Luce-Rozan. 

Theberge SM, Luther GW, Rozan TF, Rickard DT (2000) Evidence for aqueous clusters as intermediates during copper sulfide formation. Abstr Am Chem Soc 220 353 Thompson DN, Sayer RL, Noah KS (2000) Sawdust-supported passive bioremediation of western United States acid rock drainage in engineered wetland systems. Minerals Metall Process 17 96-104 Tolman RC (1966) Consideration of Gibbs theory of surface tension. J Chem Phys 16 758-774 Tolman RC (1949) The effect of droplet size on surface tension. J Chem Phys 17 333-337 Tomino H, Kusaka I, Nishioka K, Takai T (1991) Interfacial tension for small nuclei in binary nucleatioa J Crystal Growth 113 633-636... 

An improvement to this approach was developed by Luce-Rozan in Marseilles in which dry steam was injected into the molten lead while cold water was sprayed onto the surface. The steam blast kept the temperature much more uniform and the enriched alloy approached closer to the eutectic composition of two per cent silver. Generally only two pans were required for this variant of the process. 

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