IMPROVEMENTS IN THE TREATMENT OF THE ORES OF ZINC AND IN SPELTER MAKING
Year: 1858

page_text: PROVISIONAL SPECIFICATION left by Charles Crockford at the Office of
the Commissioners of Patents, with his Petition, on the 17th June
1858.
I, CHARLES CROCKFORD, of Holywell; Flintshire, Smelter, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN THE TREATMENT OF
THE ORES OF ZINC AND IN SPELTER MAKING," to be as follows:-
My Invention relates to the treatment of the ores of zinc and to the making
of spelter, and consists, 1st, in utilizing the sulphur contained in the sulphuret
of zinc.
2nd, in the mode of treating the carbonate of zinc for the purpose of
obtaining carbonic acid and other products therefrom.
3rd, in the mode of obtaining products from the zinc vapours passing
through the flues of retort furnaces used in spelter-making.
And, 4th, in treating the residue left in the retorts after the process of
reduction is completed...,
In carrying out the 1st part of my Invention, I so construct a furnace for
calcining the sulphuret of zinc, that the sulphuret of zinc is introduced
continually in small quantities at one end of a chamber, the floor of which is
heated by a fire and flues underneath, and exposed in its passage from one
end to the other end of the said chamber to the action of a current of heated
air, by which the sulphur is converted into sulphurous acid, which is carried
off in a nearly continuous stream, and may be applied to the manufacture of
sulphuric acid, or to any other purpose for which sulphurous acid may be
required. By the construction of such a furnace, from which a practically
continuous stream of sulphurous acid is obtained, and also by the application
of the surplus heat from such furnace to the heating of air intended to be

page_text: passed in a current over the sulphuret of zinc, I effect a considerable
improvement in this part of the manufacture.
In carrying out the 2nd part of my Invention, the carbonate of zinc is
placed in a suitable vessel, and treated with sulphuric or muriatic acid, by
which the carbonic acid is given off, and may be collected and applied to any
purpose for which carbonic acid may be required. The sulphate or muriate
of zinc formed by this process may also be collected and applied to any
purpose for which those salts may be required. This part of my Invention
relates to the mode of treating the carbonate of zinc for the purpose of
generating carbonic acid, and forming the sulphate or muriate of zinc.
In carrying out the 3rd part of my Invention I proceed as follows:- Into
the flues of the retort furnace used in spelter-making, a stream of muriatic acid
gas and a jet of steam are injected, by which means the oxide of zinc, or zinc
fumes passing through the said flues become converted into muriate of zinc,
which may be condensed and collected at a point in the said flues wherethe tem-
perature becomes sufficiently low for such condensation; or the vapours passing
through the said flues are exposed in their passage to a shower of muriatic or
any other acid, capable of dissolving the oxide of zinc, and the muriate or
other zinc salt thus formed may be collected in a suitable reservoir. I do
not claim any particular form of apparatus for effecting this, but what I do
claim as novel is the application of acids either in vapour or liquid to the
fumes passing through the flues of the retort furnaces used in spelter-
making.
In carrying out the 4th part of my Invention I proceed as follows:-The
residue from the retorts, after the process of reduction has been practically
completed, consists of about equal proportions of oxide of iron and oxide of
zinc, and this being mixed up with a small quantity of clay or lime, or both, is
submitted to the action of a blast in a small cupola or blast furnace, the vent
of which is conducted into a cistern of water; by this means the iron will be
reduced, and may be drawn off at the tap hole of the furnace, and the oxide of
zine will be carried forward into the cistern of water, where it will be de-
posited and may be collected for use. What is novel in this part of my Inven-
tion is the treatment of the residue from the retorts used in spelter-making
by means of a blast furnace in manner described.