Improvements in the Treatment of Slag Resulting from the Smelting of Tin Ore.
Year: 1897

page_text: Date of Application, 12th June, 1897
Complete Specification Left, 10th Aug., 1897-Accepted, 25th Sept., 1897
Date of Application, 12th June, 1897
Complete Specification Left, 10th Aug., 1897-Accepted, 25th Sept., 1897
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Slag Resulting from the Smelting
of Tin Ore.
-
I, CARL CHRISTIAN EDUARD BOHNE, of Tostedt, Kreis Harburg (Elbe) Metal-
lurgical Engineer, do hereby declare the nature of this invention to be as follows:-
The slag resulting from the smelting of tin ores in a hearth, flaming, or rever-
beratory furnace or in a shaft-furnace, contains about 20 per cent. of tin. For
the purpose of recovering the tin contained in this slag, it has hitherto been
necessary to subject the slag repeatedly to a smelting operation with the addition
of iron, and the slag has finally been thrown aside whilst containing about 4 per
cent. of tin. By my process, on the other hand, the whole of the contained tin can
be recovered in a practical manner from the ore-slags, and also from slag which
has already been treated one or more times in a hearth, flaming, or reverberatory
furnace or in a shaft-furnace.
According thereto the slags resulting from the smelting of pure tin-ores as
also the slags resulting from the treatment of low-grade tin-ores, are decomposed
in a granulated state, extremely easily and in a very short time, by means of hot
sulphuric acid of 36 to 46° Beaumé with stirring at intervals.
A residue is produced, consisting partly of gelatine-like silicic acid, and partly
of granular silicic acid, and containing from 0.5 to 0.8% of tin.
Now since the hearths of smelting hearth, flaming, or reverberatory furnaces for
tin-ores are built up with quartz sand, or are composed of quartz sand, I utilize
the aforesaid residue also for that purpose by mixing 1 part of the said residue in
the dry state with 2 to 3 parts of fresh quartz sand, and I use this mixture for
making the hearths of such furnaces.
The tin-viz., from 0.5 to 0.8 per cent.--remaining in the said residue, thus
passes afresh into the process of treatment.
The metals contained in the solution produced by treating the tin-slag with
dilute sulpruric acid, can be easily precipitated and recovered by crystallization
from the said solution. Thus, for instance, the tin is precipitated by electrolysis,
and the iron is recovered by crystallization from the lye in the form of iron-vitriol
My process.e., the treatment of the granulated tin-ore slag (and also of slag
which has already been worked one or more times) with dilute sulphuric acid, for
the purpose of recovering the contained tin from the same, and the utilization, of
the residue in forming the hearths of smelting hearth, flaming, or reverberatory
furnaces affords the advantage of effecting the recovery not only of almost all
the contained tin in a direct manner, but also, by gradually working it up, of
the tin (about 4 per cent.) contained in slag that has already been worked or
treated.

page_text: Improvements in the Treatment of Slag Resulting from the Smelting
of Tin Ore.
I, CARL CHRISTIAN EDUARD BOHNE, of Tostedt, Kreis Harburg (Elbe) Metal-
lurgical Engineer, 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 slag resulting from the smelting of tin ores in a hearth, flaming, or rever-
beratory furnace or in a shaft-furnace, contains about 20 per cent. of tin. For
the purpose of recovering the tin contained in this slag, it has hitherto been
necessary to subject the slag repeatedly to a smelting operation with the addition
of iron, and the slag has finally been thrown aside whilst still containing about
4 per cent. of tin.
By my process, on the other hand, the whole of the contained tin can be
recovered in a practical manner from ore-slags, and also from slag which has already
been treated one or more times in a hearth, flaming, or reverberatory furnace or
in a shaft-furnace.
According thereto the slags resulting from the smelting of pure tin-ores as
also the slags resulting from the treatment of low-grade tin-ores, are decomposed
sulphuric acid of 30 to 46° Beaumé with stirring at intervals.
in a granulated state, extremely easily and in a very short time, by means of hot
A residue is produced, consisting partly of gelatine-like silicic acid, and partly
of granular silicic acid, and containing from 0.5 to 0.8% of tin.
Now since the hearths of smelting hearth, flaming, or reverberatory furnaces for
tin-ores are built up with quartz sand, or are composed of quartz sand, I utilize
the aforesaid residue also for that purpose by mixing 1 part of the said residue in
the dry state with 2 to 3 parts of fresh quartz sand, and using this mixture for
making the hearths of such furnaces.
The tin viz. from 0.5 to 0.8 per cent.-remaining in the said residue, thus
passes afresh into the process of treatment.
The metals contained in the solution produced by treating the tin-slag with
dilute sulphuric acid, can be easily precipitated and recovered by crystallization
from the said solution. Thus, for instance, the tin is precipitated by electrolysis,
and the iron is recovered by crystallization from the lye in the form, of iron-vitriol.
My process i.e., the treatment of the granulated tin-ore slag (and also of slag
which has already been worked one or more times) with dilute sulphuric acid, for
the purpose of recovering the contained tin from the same, and the utilization of
the residue in forming the hearths of smelting hearth, flaming, or reverberatory
furnaces affords the advantage of effecting the recovery not only of almost all
the contained tin in a direct manner, but also, by gradually working it up, of
the tin (about 4 per cent.) contained in slag that has already been worked or
treated.
Having now rarticularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed I declare that what I
claim is:
The treatment of slag resulting from the smelting of tin-ore, consisting in
granulating it and fluxing the granulated slag by means of hot sulphuric acid so
.

page_text: whilst the residue, which contains the remainder of the tin, can be utilized to aid
in forming the hearths of hearth, flaming or reverberatory furnaces for smelting
tin.
Dated this 10th dess of August 1897
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.