A Process for the Manufacture of Double Compounds of Sulphuret of Aluminium with other Metallic Sulphides.
Year: 1896

page_text: Date of Application, 4th Apr., 1896-Accepted, 25th July, 1896
COMPLETE SPECIFICATION.
A Process for the Manufacture of Double Compounds of Sulphuret
of Aluminium with other Metallic Sulphides.
I, DMITRY ALEXANDROWITCH PENIAKOFF, of Rue Bauduin Pièrre, Huy, in
the Kingdom of Belgium, 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:-
This invention relates to a process for the manufacture of double compounds of
sulphuret of aluminium with other metallic sulphides by the treatment of dehydrated
alumina with sulphuret of carbon vapours or sulphoxy-carbon in the presence of
salts rich in oxygen (such, for example, as sulphates, phosphates, chromates and
the like) of corresponding metals.
In carrying out this process, there is first prepared a thorough mixture of
alumina with the metallic salt which it is proposed to use for the purpose of
obtaining the desired double compound, it being necessary that both the alumina
and the salt should be well dried.
A very thorough mixture of the substances in question may be obtained by a
chemical process, by the use of sulphate of alumina, still containing moisture, with
the chloride of an alkali. The following reaction will then, in the usual course,
take place
Al, (S.O)Aq. + 6 NaCl = Al2O3 + 3 Na2SO4 + 6 HCI.
Instead of haloid salts, other salts also, with volatile acids (nitrates, acetates,
and the like,) may be employed in this operation.
This reaction is a quantitative one and yields a compact mass, which however is
still sufficiently porous to be readily permeated by gases. It is an extremely
economical operation, as it enables a quantity of chemically pure hydrochloric acid
(nitric acid, acetic acid and the like) equivalent to the amount of sulphuric acid
consumed, to be obtained.
The remaining residue, or the artificial mixture of alumina with the oxy-salt is,
either directly, or after having been formed into blocks or cakes, with or without
the employment of any suitable adhesive substance or cement introduced into
retorts and heated to a higher or lower temperature according to the nature of the
salt that is used in the mixture.
The retorts should be tightly closed and provided with tubing for the intro-
duction of vapours or mixtures of vapours exercising a sulphurizing action; and
further, with a second set of tubes for the vapours and gases (carbonic acid,
sulphur, sulphuretted phosphorus) evolved in the course of the reaction.
The reactions which take place during the operation may be expressed as
follows:-
Al2O3 + 3 RxSO4 + 7.5 CS, = Al,S, 3 RxS + 7.5 CO, + 12 S
==

page_text: chromates and the like) is advisable on the ground that these salts yield a
considerable amount of combustible oxygen which when it combines with the
carbon sets free a very large amount of heat whereby the formation of sulphide
(or sulphuret) takes place far more easily than if alumina were alone employed.
From the foregoing it will readily be seen that this action, calculated to promote
the main reaction, cannot be brought about by the employment of carbonates
since the oxygen of the same is already bound up with or absorbed by carbon.
The object of this process as well as of that described in the Specification of
Letters Patent No. 20604 of 1893 (for "Obtaining sulphide of aluminium from
alumina salts rich in oxygen ") is to render the reaction as favourable, or satisfactory,
as possible from a thermo-chemical point of view. In both these processes devised
by me that result is obtained by the employment of an alumina salt as the initial
material to be operated upon, the difference being that, in one case, the operation
is conducted in the presence of an alkaline salt, while in the other, the alumina
salt is dehydrated by itself and subsequently submitted to the action of vapours
producing a sulphurising effect.
Thus the process herein described enables a thorough mixture of the initial
substances to be obtained; such process combining the advantages of convenience
since it is performed simply by vapours and of economy, admitting, as it does, of
the chemically pure acid of the alkaline salt employed being recovered again.
These substances, moreover, are selected with a view to obtaining a more satis-
factory main reaction, from the thermo-chemical point of view; or in other words,
materially facilitating the reaction upon the whole, by the introduction of secondary
reactions i.e. the combustion of carbon in the oxygen.
By such means the requisite temperature for the reaction may be considerably
lowered while the cost of the plant and keeping it in repair and heating it is
materially reduced.
The double sulphides obtained in this manner may be, by well known methods
(chemical reduction or electrolysis) converted into aluminium in the condition of
metal, or into alloys thereof.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is :-
A process for obtaining double compounds of sulphuret of aluminium with other
metallic sulphides mainly consisting in the treatment of a mixture of alumina free
from moisture with salts rich in oxygen (such for instance as sulphates, phosphates-
chromates and manganates) by means of sulph-oxy-carbon or sulphuretted carbon
vapours, the mixture for the reaction being conveniently obtainable by a chemical
process.
Dated this 2nd day of April 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.