IMPROVEMENTS IN THE MODE OF TREATING THE ORES OF LEAD OR PRODUCTS CONTAINING LEAD, EITHER ISOLATED OR IN COMBINATION WITH OTHER METALS OR MINERALS, FOR THE PURPOSE OF PRODUCING METALLIC LEAD AND OTHER METALS AND THEIR COMPOUNDS, AND ALSO IN FURNACES POR CARRYING OUT THE SAID OPERATIONS
Year: 1869

page_text: PROVISIONAL SPECIFICATION left by Charles Crockford at the Office
of the Commissioners of Patents, with his Petition, on the 6th July
1869.
I, CHARLES CROCKFORD, lately of Holywell, Flintshire, but now of
Amluch, in the Island of Anglesey, Gentleman, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE MODE OF TREATING
THE ORES OF LEAD OR PRODUCTS CONTAINING LEAD, EITHER ISOLATED OR IN
COMBINATION WITH OTHER METALS OR MINERALS, FOR THE PURPOSE OF PRODUCING
METALLIC LEAD AND OTHER METALS AND THEIR COMPOUNDS, AND ALSO IN FURNACES
POR CARRYING OUT THE SAID OPERATIONS," to be as follows:-
I take galena and convert as large a portion of it as practicable into
sulphate of lead by calcination; I then treat it with chloride of sodium
to form sulphate of soda and chloride of lead, and after washing out the
sulphate of soda I dissolve out the chloride of lead with a strong solution
of chloride of calcium; I then precipitate the lead with zinc, iron, sul-
phide of sodium, carbonate of soda, or other reagent, according to the
nature of the product required. Sometimes I calcine the galena with
chloride of sodium, or I treat it with hydrochloric acid, for the purpose
of obtaining the chloride of lead. The sulphate of lead may be treated

page_text: direct with the chloride of calcium, and the lead, &c. obtained in solution.
Instead of the chloride of calcium for dissolving the chloride of lead
I may use the chloride of magnesium, barium, strontium, potassium,
ammonium, or manganese, and any of these salts may be used for
converting the lead into chloride as well as for dissolving it.
In working the mineral known as bluestone, from the island of
Anglesey (or similar material or materials), being a combination of the
sulphides of zinc, iron, lead, copper, and silver, I proceed as follows:-
Having ground the ore I desulphurize it by heating it in a furnace, over
the inclined bed of which it is caused to travel by a succession of per-
cussive blows, which may be so regulated as to admit of a continuous
feeding of the raw ore at one end and a continuous delivery of the
desulphurized ore at the other end of the said bed; or I place several
inclined beds one over the other, and by percussive blows I cause the
mineral to descend from one to the other; or I feed the ore continuously
into the upper end of a long fire-clay cylinder which is heated externally,
and which cylinder is placed on an incline, and upon being caused to
revolve the ore is caused to travel continuously or intermittently towards
the lower end, where it is delivered in a desulphurized state. By ceither
of these constructions of furnaces I am enabled to desulphurize ores and
to collect the sulphurous acid gas for the purpose of manufacturing
sulphuric acid. After having desulphurized the ore I heat it with a
small quantity of chloride of sodium, and thus convert the lead, silver,
and copper into chlorides; the chloride of copper is washed out with
water and the copper precipitated, after which the chlorides of lead and
silver are dissolved out with chloride of calcium or other chlorides, and
the silver is first precipitated with copper, and afterwards the lead is
precipitated, as before described. I then treat the residue, consisting of
silica and the oxides of zinc and iron, with weak sulphuric acid, by
which I dissolve out the zinc, which I precipitate with sulphate of
sodium; or instead thereof I calcine the ground bluestone with chloride
of sodium, and after washing out the sulphate of soda and the chlorides
of zinc and copper I first precipitate the copper and then "salt out" the
sulphate of soda; after which I precipitate the zinc (as oxide) with lime,
and I then dissolve out the lead and silver with chloride of calcium, as
before described.
I now proceed to describe another modification of the treatment or
process for working the bluestone or other similar material. After

page_text: having desulphurized it, as beforé described, I mix it with sufficient
carbon to reduce the metals, and smelt it in retorts (placed perpen-
dicularly in a furnace) having a condensing apparatus attached to the
top of them for collecting the volatile metal, and also having a receiving
cup attached to the bottom of them, into which the non-volatile metals
are caused to descend by means of the vibratory motion given to the
retort by a succession of percussive blows. Sometimes I add litharge or
other flux for the purpose of facilitating the descent of the metals.
Instead of giving motion to the retort in the manner described I prefer
in some cases to bring up a heated receiver, into which I empty the
contents of several retorts, and then by applying motion to it, as before
described, I am enabled to collect the metallic products at the bottom
of it, and instead of condensing the zinc in a fluid metallic state I may
conduct the fumes into a chamber, and by the admission of air thero
collect it as white oxide of zinc.
The novel construction and arrangement of vertical or inclined and
revolving furnaces herein described having several inclined beds therein,
and having a series of percussive blows given thereto for passing the
materials through, as herein described, may be used or employed for
treating other materials.