IMPROVEMENTS IN EXTRACTING SILVER FROM ALLOYS OF ZINC WITH LEAD
Year: 1867

page_text: PROVISIONAL SPECIFICATION left by William George Blagden at the
Office of the Commissioners of Patents, with his Petition, on the
14th March 1867.-A communication from abroad by Francisco Marquez-
Millan, of No. 7, Rue Liandier, Marseilles, in the Empire of France.
I, WILLIAM GEORGE BLAGDEN, of Hackney Wick, in the County of Middlesex,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
EXTRACTING SILVER FROM ALLOYS OF ZINC WITH LEAD," a communication, to be
as follows:-
The improvements in extracting silver from alloys of zinc with lead relate
to effecting the disintegration and granulation of the alloy by treatment thereof
in crucibles or vessels, and the separation of the granules by sifting, and when
the granules have been dissolved in diluted acid to acting upon the solution
obtained by means of carbonate of soda for the purpose of precipitating car-
bonate of zinc, and again upon a further solution to obtain carbonate of lead.
Means for effecting these improvements are as follows:-The alloy is placed
in a pot or pan, and in which it is heated to a temperature of, say, about 350°
Réaumur, in order to melt any lead that may be mixed with it mechanically.
The lead thus obtained contains a quantity of zine, and may afterwards be
refined or annealed in a reverberatory furnace in the ordinary way; or it may
be used in the place of metallic zinc for the purpose of desilverizing argenti-
ferous lead. The dross removed from the above-mentioned pot or pan is
pressed into moulds, and is then placed in a crucible or vessel where it is
heated to a temperature of, say, about 400° Réaumur. By this operation a
certain quantity, say, about of its bulk of lead, is sweated out, and the alloy

page_text: which remains unmelted loses its firm texture and crumbles like sand. The
alloy which is not melted may be removed by means of a perforated ladle, and
then thrown on a sieve and shaken for some time over a vessel containing
water; the alloy remaining in this sieve may be remelted in the crucible with
the next charge. The lead which is sweated out in the crucible contains a
considerable quantity of silver, which is separated from it, by preference, by
means described in the application by me for protection, dated January 14th
1867, No. 87. The granules that have passed through the sieve are then
treated with muriatic acid of commerce (diluted with water) in the proportion
of about 2 pints of acid to 1 lb. of zinc; this operation is continued until
zinc is dissolved, say, from about 30 minutes to about 2 hours, according as
the previous process of granulation has reduced the substance to a more or less
fine powder. At the end of this time the liquid is poured off diluted with
water, filtered, heated, and treated with carbonate of soda to precipitate the
carbonate of zinc ready for sale. The substance remaining undissolved by the
muriatic acid is then carefully washed, and from the water thus used carbonate
of lead is precipitated; the solid substance remaining after this washing will
be found to be silver mixed with a very small quantity of lead and a trace of
zine; it may be easily melted and refined in crucibles without being submitted
to the process of cupellation, and can then be sold.