Treating Ores and Residues containing Zinc by means of Bi-sulphate of Soda for the Production of Commercial Products.
Year: 1891

page_text: Date of Application, 24th Jan., 1891
Complete Specification Left, 22nd Oct., 1891-Accepted, 23rd Jan., 1892
PROVISIONAL SPECIFICATION.
Treating Ores and Residues containing Zinc by means of Bi-sulphate
of Soda for the Production of Commercial Products.
I, ALEXANDER MELVILLE CLARK of the firm of A. M. and Wm. Clark, of
53 Chancery Lane, in the County of Middlesex, Fellow of the Institute of Patents,
do hereby declare the nature of this invention, (a communication to me from
abroad by La Société Anonyme de Produits Chimiques Etablissements Malétra
of 140 Rue de Rivoli, Paris, France, represented by François Etienne Costes,
Administrateur-Délégué et President du Conseil) to be as follows:-
This invention relates to the metallurgical treatment of ores and residues con-
taining zine, by means of bisulphate of soda and thereby to utilize two kinds of
industrial residues for the production of commercial products. The one residue
comprises zinc turnings, filings, scraps, clippings, scum and dross from molten zinc,
galvanization residues, slimes from the washing of calamines and blendes, calamines
and blendes too poor in zine for distillation in the furnace, and other waste
products containing zinc; whilst the other is the valueless residue of chemical
works known in commerce as bisulphate of soda.
The treatment of the zinc residues with bisulphate of soda is effected in a closed
boiler or preferably in an ordinary reverberatory furnace heated with coal upon a
hearth lined with refractory material, in quantities of from 300 to 350 kilogrammes
at a time mixed with a suitable proportion of bisulphate of soda varying according
to the richness in metallic zinc of the residues under treatment.
The bisulphates
After
are the acid sodium sulphates forming the residues of the manufacture of nitric acid,
by means of sulphuric acid and nitrates of soda, these residues being practically
useless and forming a positive encumbrance in many chemical works. The zincic
frit obtained is thrown in water which dissolves the zinc and soda in the form of
sulphates charged with sulphate of iron, the earthy and other impurities being
precipitated. After decantation, the dissolved iron is separated from the liquor
by known means. From the filtered clear neutral liquors, sulphate of soda is
crystallized out, collected, dried, and put into sacks or barrels for sale.
decanting the mother waters lime water or sulphide of sodium is added, and the
precipitate, which is white or yellowish as the case may be, is calcined at a dull
red heat in a crucible or preferably in a continuous furnace resembling a tile kiln,
the resulting product being zinc white of good color, unctuous, and which covers
well, if the preceding operations have been properly conducted. If the first
washing waters are rich enough in sulphate of soda to be worth treatment, they
are concentrated and run into the first crystallizing vats or pans of the sulphate of
soda works.
When ammonia can be cheaply obtained, it may be substituted for the two
re-agents above mentioned. The resulting sulphate of animonia being crystallised
out from the residual solution for use as a fertilizer. The waters from which the
zinc has been precipitated by means of sulphide of sodium or lime water may be
utilised for the manufacture of barium sulphate or blanc fixe by the addition of a
weak solution of barium hydrate of low quality, filtering washing and drying the
precipitate.
The muddy residues of the reaction often contain lead in the form of sulphate
of but little value as such, but which may readily in presence of pyroligneous acid

page_text: and zinc be converted into spongy lead smitable for the manufacture of secondary
batteries, or into litharge and merchant lead.
Deted this 24th day of Januar£1001
A. MELVILLE CLARK.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
Treating Ores and Residues containing Zinc by means of Bi-sulphate
of Soda for the Production of Commercial Products.
I, ALEXANDER MELVILLE CLARK, of the firm of A. M. and Wm. Clark, of
53, Chancery Lane, in the County of Middlesex, Fellow of the Institute of Patent
Agents, do hereby declare the nature of this invention (a communication to me by
La Société Anonyme de Produits Chimiques, Etablissements Malétra, of 140, Rue
de Rivoli, Paris, France, represented by François Etienne Costes, Administrateur-
Delégué et Président du Conseil) and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement :-
This invention relates to the metallurgical treatment of ores and residues con-
taining zinc, by means of bi-sulphate of soda and thereby to utilize two kinds of
industrial residues for the production of commercial products. The one residue
comprises zinc turnings, filings, scraps, clippings, scuni, and dross from molten zinc,
galvanization residues, slimes from the washing of calamines and blendes, calamines
and blendes too poor in zinc for distillation in the furnace, and other waste
products containing zinc, whilst the other is the valueless residue of chemical
works, known in commerce as bi-sulphate of soda.
The treatment of the zinc residues with bi-sulphate of soda is effected in a
closed boiler or preferably in an ordinary reverberatory furnace heated with coal
upon a hearth lined with refractory material, the residues being mixed in regulated
quantities with a suitable proportion of bi-sulphate of soda, varying according to
the richness in metallic zinc of the residues under treatment. Thus in treating
charges of 300 to 350 kilogrammes of zinc ashes obtained from skimmings in the
remelting of old or scrap zinc, the said ashes, if containing 70 per cent. of metallic
zinc, will require from two and a half to three times their weight (viz. from 750
to 1000 kilogrammes) of bi-sulphate of soda. The ashes and salt after being
intimately mixed are introduced into the furnace in successive charges as the fusion
proceeds. The charge is drawn from the furnace immediately the mass becomes
pasty and homogeneous and after nearly all the vapours have ceased to disengage.
The bi-sulphates employed are the acid sodium sulphates forming the residues of
the manufacture of nitric acid by means of sulphuric acid and nitrates of soda,
these residues being practically useless and forming a positive encumbrance in
many chemical works. The zincic frit obtained is thrown in water, which dissolves
the zine and soda in the form of sulphates charged with sulphate of iron, the
earthy and other impurities being precipitated. After decantation, the dissolved
iron is separated from the liquor by known means.
From the filtered clear neutral liquors, sulphate of soda is crystallized out,
collected, and after being desiccated to render it anhydrous, put into sacks or
barrels for sale.
After decanting the mother waters, lime water or sulphide of sodium is added
and the precipitate which is white or yellowish as the case may be, is. calcined at
a dull red heat in a crucible, or preferably in a continuous furnace, the resulting
product being zinc white, of good color, unctuous, and which covers well, if the
preceding operations have been properly conducted.
If the first washing waters are rich enough in sulphate of soda to be worth

page_text: treatment, they are concentrated and run into the first crystallizing vats or pans.
of the sulphate of soda works.
The precipitation by means of lime water of the zinc in the form of sulphate in
the liquors, produces white oxide of zine. The precipitation by means of sulphide
of sodium produces sulphide of zinc. The one or other of these precipitates is
calcined in a reverberatory furnace, but beneath an arch with return flame, so as
to prevent contact of the matters with the flame and furnace gases, in other words
in a muffle furnace. The sulphur in the second case is partly burnt and it is
necessary that the temperature should not exceed 400° to 500° C.
The charge for an ordinary muffle furnace would be from 200 to 300 kilo-
grammes.
When it is desired on the other hand to utilise the oxide of zinc for obtaining
the metal, the sulphate of zinc may be precipitated by milk of lime or sulphide of
sodium, but in these latter cases the matters should be highly calcined, after being
well washed and moulded into bricks, the residue of the calcination being oxide of
zine containing 70 per cent. of zinc, which is capable of being distilled in retort
furnaces of the Liège, Silesian, English, or other kind, like any other calcined zinc
ores, in one half less time than that required for ordinary calcined blendes or
calamines.
When ammonia can be cheaply obtained it may be substituted for the two-
reagents above mentioned, the resulting sulphate of ammonia being crystallized out
from the residual solution, for use as a fertilizer.
The waters from which the zinc has been precipitated by means of sulphide of
sodium or lime water, may be utilized for the manufacture of barium sulphate or
"blanc fixe" by the addition of a weak solution of barium hydrate of low quality,
filtering, washing, and drying the precipitate.
The muddy residues of the reaction often contain lead in the form of sulphate
of but little value as such, but which may readily, in presence of pyroligneous
acid and zinc, be converted into spongy lead suitable for the manufacture of
secondary batteries or into litharge and merchant lead.
The whole of the metallurgical treatment herein described can be performed
with the aid of the ordinary plant of chemical works, except the calcination of the
zinc white which is effected in a furnace of the kind before referred to.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is-
1st. The herein described metallurgical treatment of ores and residues containing
zinc, by the employment in the manner specified, of bi-sulphates of soda or acid
sodium sulphates forming the residues of the iñanufacture of nitric acid.
2nd. The conversion, by means of the soluble re-agent hereinbefore specified, of
all kinds of zinc residues, hitherto comparatively useless into zinc white (60%
to 80%) capable of being sublimated, to obtain metallic zinc, in the ordinary
retort furnaces of the Liège, Silesian, English, or other kind in one-half less time
than that required for ordinary calcined blendes or calamines.
3rd. Obtaining white crystallized sulphate of soda or anhydrous sulphate of
soda.
4th. Obtaining from the residual liquor of the precipitation of oxide of zinc,
ammonium sulphate, or barium sulphate ("blanc fixe") according as ammonia or
baryta are employed, as specified.
Dated this 22nd day of Outabes 1001
A. MELVILLE CLARK.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.