A New or Improved Process for the Treatment of Aluminous Ores and Silicious Matters.
Year: 1896

page_text: Date of Application, 16th Apr., 1896-Accepted, 23rd May, 1896
COMP
IFIC TION.
[Communicated from abroad by THE COMPAGNIE GENERALE L'ALUMINE
EXPLOITATION DES BREVETS F. RAYNAUD (SOCIÉTÉ ANONYME), of
No. 76 Rue de Venise, Brussels, in the Kingdom of Belgium.]
A New or Improved Process for the Treatment of Aluminous Ores
and Silicious Matters.
I WILLIAM THOMAS WHITEMAN of No. 7 Staple Inn in the County of
Middlesex Patent Agent 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:-
This invention consists in a new or improved process for the treatment of
aluminous ores and silicious matters with the object of obtaining alumina metallic
aluminium, sulphur, alkaline silicates and aluminates and sundry other accessory
chemical products hereinafter mentioned.
The said invention is based on the reaction which takes place at a comparatively
low temperature when steam is caused to act on an aluminous ore, or a silicious
substance, in the presence of a sulphide (or a sulphate mixed with carbon) capable
of combining with alumina or silica. Thus
I. When a mixture of bauxite and sulphide of sodium is brought to a dull red
beat in presence of steam aluminate of soda is formed without difficulty and
sulphuretted hydrogen is liberated.

page_text: the said mixture should contain about 900 kilos. of sulphate of soda, 207 kilos. of
carbon, and 640 kilos. of alumina; and where aluminate of potash is to be obtained
the sulphate of soda is replaced by sulphate of potash due regard being had to the
difference of the equivalents.
The briquettes are next rapidly dried upon cast iron frames or plates heated to
a bright red heat or any other means may be used whereby the drying may be
effected with sufficient rapidity to produce a high degree of porosity. The
briquettes are then charged into cylinders or retorts, wherein they are heated to,
and maintained at, a bright red heat, by external firing. These cylinders com-
municate with each other, and through each of them in succession a current of
steam passes the said steam travelling from one to another of the said cylinders in
regular order and passing through the briquettes the passage of the steam through
the briquettes being permitted by their porosity.
The gases which escape through the outlet of the last cylinder consist of
sulphuretted hydrogen (HS) and carbonic oxide (CO).
As the carbonic oxide cannot in any way interfere with re-use of the sulphur
contained in the sulphuretted hydrogen it is available for re-use in known ways.
The blocks thus treated yield, on being subsequently lixiviated, a very clear
solution of alkaline aluminate.
The economical production of the aluminates being effected by the means
hereinbefore indicated (Reactions I II and IV) to obtain pure alumina and alkaline
carbonate, the clarified lixivium of aluminate is subjected to the action of a current
of carbonic acid according to the known process.
The alumina precipitated from the carbonated lixivium may, after having been
dried, be at once put in the market or it may serve for the manufacture of metallic
aluminium.
V. In the latter case briquettes are made of alumina (Al2O3) and crushed coke,
which are heated to a bright red heat within a retort or cylinder into which is
passed a current of sulphuretted hydrogen (HS) produced by the Reaction I or by
any other means.
The sulphuretted hydrogen would produce no action on the alumina without the
presence of the carbon. In this operation the sulphurizing action is considerably
augmented if to the mixture of carbon and alumina a small quantity of alkaline
or alkaline-earthy metallic oxides he added. This addition should not exceed
from three to four per cent. in order that the sulphuration may take place
actively.
It may here be observed, that the production of sulphide of aluminium may
also be effected by reducing the sulphate of alumina by action of a current of
sulphuretted hydrogen in presence of carbon, oxides, sulphates or sulphides.
The sulphide of aluminium being obtained there is added to it a small portion
(about five per cent.) of sulphide of lead, and then a quantity of sulphate of lead
equivalent to the sulphur of the aluminium.
The mixture thus obtained being heated to a bright red heat the sulphide of lead
reacts on the sulphate of lead and immediately forms sulphurous acid, which is set
free in a pure state, and metallic lead which instantaneously acting on the sulphide
of aluminium seizes upon its sulphur and oxidizes it by means of the sulphate of
lead, thus re-forming a fresh quantity of sulphurous acid and metallic lead, which
continues to absorb the sulphur of the aluminium while the latter is not in the
metallic state.
A small amount of sulphide of lead is, therefore, sufficient to reduce large
quantities of sulphide of aluminium; and thus the use of metallic lead is avoided
and production of sulphurous acid of great purity is insured.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to
me by my foreign correspondents I declare that I claim :-
First. The process for the production of alkaline and other aluminates and the

page_text: simultaneous production of sulphur or sulphuretted hydrogen consisting in heating
in the presence of a current of steam a mixture of aluminous ore and of any
sulphide capable of combining with alumina or of carbon mixed with any sulphate
capable of combining with alumina substantially as herein before described.
Secondly. The application of the process characterized in the first claim.
to the production of silicates by the substitution of silicious matter for the
aluminous ore.
Thirdly. The preparation of porous briquettes of the mixture of sulphide and
aluminous or silicious ore or of the mixture of sulphate, carbon and aluminous or
silicious ores with a view to methodical treatment of such mixtures by means of a
current of steam as herein before described.
Fourthly. The obtainment of sulphide of aluminium by the sulphuration of
alumina or of sulphate of alumina by means of sulphuretted hydrogen in presence
of carbon or of carbon and metallic oxides substantially as herein before
described.
Fifthly. The simultaneous production of metallic aluminium and sulphurous.
acid by the desulphuration of sulphide of aluminium by means of sulphide and.
sulphate of lead substantially as herein before described.
בד
W. T. WHITEMAN.