Improvements in the Extraction of Bismuth, especially applicable to the Treatment of the Flue Dust of Copper Works.
Year: 1892

page_text: Date of Application, 4th Oct., 1892
Complete Specification Left, 4th July, 1893-Accepted, 16th Sept., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Extraction of Bismuth, especially applicable to
the Treatment of the Flue Dust of Copper Works.
I, JOSIAH WYCKLIFFE KYNASTON of 3, Oak Terrace, Beech Street, Liverpool
in the County of Lancaster, Manufacturing Chemist, do hereby declare the nature
of this invention to be as follows:-
The sublimate which collects in the flues of copper furnaces contains considerable
quantities of bismuth and also copper, lead, arsenic, antimony and other matters.
Up to the present, it has been treated only for the extraction of the copper it
contains and the valuable bismuth has been lost.
To obtain the bismuth from this material, I digest it with hydrochloric acid of
from 10 to 15 Twaddell and preferably heated, and using only a proportion of the
acid sufficient to dissolve and retain in solution the whole of the bismuth and other
metals. The muddy mixture is then run on to. a filter bed and the liquor allowed
to drain through, assisted by suction if necessary, and a second portion of acid,
about one fourth more than the first, is then run upon the material to wash out
the bismuth more completely, and the second runnings are used for the initial
treatment of a fresh portion of material.
The liquor so obtained contains, besides the bismuth, the copper, antimony,
arsenic and other matter, soluble in the acid liquid. To this liquor I now add
about one fourth of its bulk of strong solution of chloride of calcium, the purpose
of which is two-fold; first, it ensures the removal, as sulphate of calcium, of some
sulphuric acid which is present in the liquid and which, if not removed, would lead
to an admixture of calcium sulphate with the bismuth compound subsequently
obtained; and, secondly, the chloride of calcium serves to retain in solution the
antimony and prevents its precipitation along with the bismuth.
After the removal of the calcium sulphate either by decantation or filtration or
both, I add to the solution powdered limestone, chalk or other calcium carbonate
in sufficient quantity to neutralise much of the free acid present. The bismuth
then separates as oxychloride in a state of high purity. The precipitated
oxychloride is collected, washed and dried, and, by fusion with a suitable flux, as is
well known, metallic bismuth is obtained.
in
After the removal of the bismuth, as above described, the antimony may be
extracted from the solution by treatment with precipitated metallic copper
quantity equivalent to the antimony contained in the solution, and, after the
removal of the antimony, the copper can be precipitated in the ordinary manner by
means of metallic iron.
1
TROD

page_text: COMPLETE SPECIFICATION.
Improvements in the Extraction of Bismuth, especially applicable to
the Treatment of the Flue Dust of Copper Works.
I, JOSIAH WYCKLIFFE KYNASTON of 3 Oak Terrace, Beech Street, Liverpool,
in the County of Lancaster, Manufacturing Chemist, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
The sublimate which collects in the flues of copper furnaces contains considerable
quantities of bismuth and also copper, lead, arsenic, antimony and other matters.
Up to the present, it has been treated only for the copper it contains, and the
valuable bismuth has been lost.
To obtain the bismuth from this material (in which I have found from 1 to 6 per
cent. of bismuth, varying according to the nature of the ores treated) I digest it in
a stoneware tank fitted with a wooden agitator with hydrochloric acid. The
quantity of hydrochloric acid required is about 16 cubic feet of from 10
to 15 degrees Twaddell per ton of flue dust to be treated. The acid having been
first charged into the tank and the agitator started, the flue dust is thrown in, and,
when the mixture is complete, steam is blown in until the boiling point is attained.
Water is then added to the extent of 16 to 20 cubic feet per ton of flue dust and
the agitation is continued until a perfect mixture is produced. The charge is now
run off on to a filter bed constructed of wood in the manner well known, the false
bottom of the vessel being conveniently covered with stout asbestos cloth. Suction
being now applied, the liquor drains through, and, when the surface of the material
on the filter bed is dry, water slightly acidified with hydrochloric acid is run upon
it and the washing continued until the soluble matters are completely extracted.
The solution thus obtained contains the whole of the bismuth originally present in
the flue-dust treated, and the whole of the copper, together with a small proportion
of the arsenic and antimony.. The lead remains in the residue as sulphate, and the
bulk of the arsenic and antimony also remains undissolved. To the solution of
bismuth aud copper, contained preferably in a wooden vessel fitted with an agitator,
I now add solution of chloride of calcium. If this solution of chloride of calcium
is of high density, the proportion required is about one-fourth of the bulk of the
liquor to be treated. If the ordinary residual chloride of calcium liquor of the
Weldon chlorine process be used, one-third of the bulk of the liquor to be treated
should be used. The mixed liquors are well agitated and then allowed to stand at
rest for a few hours. A large quantity of calcium sulphate now settles out and is
removed either by decantation or filtration or both, in the manner well known.
The liquors are now replaced in the same or a duplicate wooden vessel, fitted
with an agitator, and there is added gradually limestone, dust, chalk or other
carbonate of lime, just to the point when effervescence ceases to be produced. By
this treatment, the whole of the bismuth is rendered insoluble, whilst the whole of
the copper remains in solution. The muddy mass is then run upon a filter bed, and
the solution containing the copper drained off and the bismuth mud is well washed
with water until the last trace of copper is removed.
The bismuth mud so obtained contains, besides the bismuth compound, some
calcium sulphate, and sometimes a little arsenic and antimony, but, after having
been dried, it yields, by fusion with suitable fluxes, the character of which is well
known, metallic bismuth in a state of high purity.
A cheap and highly convenient flux for the purpose cousists of sodium sulphate
or ordinary salt cake mixed with one-third of its weight of powdered coal, and the
proportions required are about equal parts of the dry bismuth mud and of the fusion
mixture. The metallic bismuth obtained by the use of this flux contains only
traces of any impurity.
The liquor and the washings drained from the bismuth mud, when treated with

page_text: metallic iron in the usual well known manner, yield a copper precipitate of very
high quality.
If care be exercised in the proper dilution of the hydrochloric acid used for the
extraction of the bismuth from the flue-dust, nearly the whole of the antimony and
arsenic remain undissolved, and, if the dried residue be heated with hydrochloric
acid of 28 to 30 degrees Twaddell and the solution obtained be run into 8 or 10
times its bulk of water, the antimony is obtained as oxychloride almost free from
impurity.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
The extraction of bismuth from the flue-dust of copper works by treating the
said dust with moderately diluted hydrochloric acid, mixing the solution obtained
with chloride of calcium so as to eliminate much of the sulphuric acid present,
precipitating the solution, after the removal of the calcium sulphate, with carbonate
of lime or of other alkaline earth, and finally fusing the bismuth precipitate with a
suitable reducing flux so as to obtain metallic bismuth in the manner substantially
as described.
Dated this 23rd day of July 1893.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Patent Agents.