Improvements in the Extraction of Chromium by Electrolysis, applicable also to the Production of Chromium Alloys.
Year: 1893

page_text: Date of Application, 30th Mar., 1893
Complete Specification Left, 12th Dec., 1893-Accepted, 30th Mar., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Extraction of Chromium by Electrolysis,
applicable also to the Production of Chromium Alloys.
We EMILE PLACET and JOSEPH BONNET, both of 95 Boulevard Beaumarchais,
Paris, in the Republic of France, Chemists, do hereby declare the nature of this
invention to be as follows:-
In a preceding Patent for the extraction of chromium by the aid of electrolytic
baths (No. 22855 of 1891), we have said that, in certain cases, we heat our baths
so far as to effect the watery reduction, and also the reduction by heat, of the salts
that we employ. The following is, in effect, how we operate in certain cases.
We take, for example, 10 to 15 grains of bi-sulphate of potash, 100 grains of chrome
alum, 100 grains of water. We heat until the salts are dissolved, and we cause an
electric current to pass through the same. The chromium deposits immediately at
the negative pole. We keep up the strength of the bath by means of chrome alum
alone, or by means of a concentrated solution of chrome alum and alkaline
bi-sulphate.
The addition of these new salts increasing the volume of the bath, an overflow
pipe is provided, to maintain, at a constant height, the level of the bath. The bath
is thus constantly renewed, and can consequently last a long time. The liquid
running away by the overflow pipe, crystallizes under the influence of the cold, and
serves again to feed the bath. When we maintain the bath with chrome alum
alone, there arrives a time when all the water that we have employed to form the
bath will have run away by the overflow pipe, with the salts in solution.
From this time, the bath is composed only of salts reduced either by water or by
heat. We can also dispense with the water in the formation of the bath, and
prepare the bath by heating directly the mixture of salts until they become melted.
We add sometimes to these baths a little chlorate of potash and boric acid, benzoic
acid, or other analogous salt, in order to assist the deposit of the metal. In place
of bi-sulphate of potash, we employ also, as a flux, the sulphate or the bi-sulphate
of soda or ammonia, the phosphates, borates, chlorates, silicates, chlorides, fluorides,
&c., alkalies or alkaline earths, or a mixture of the same. In place of chrome alum,
we employ, also, oxide of chromium, and all the other salts of chromium (nitrate,
borate, phosphate, fluoride, chloride, tartrate, &c., of chromium) which will easily
fuse on contact with alkaline earths. The fusion of chromium requiring a very
high temperature, we generally employ the electric current to effect the same.
Frequently, to obtain this fusion, in place of using positive and negative
electrodes of pure carbon, we employ electrodes composed of carbon, of oxide of
chromium, of salts or ores of chromium, the whole previously agglomerated with a
flux (borax, phosphate, lime, fluoride, &c.) and a reducer (zinc, magnesium,
aluminium &c.), so that we effect, at the same time, the reduction and the fusion of
the metal.
At other times, we make these electrodes of different metals, copper, aluminium,
zinc. nickel, silver, &c., or of oxides of these metals, in order to obtain immediately
alloys of chromium and the other metals. Lastly, we find it advantageous to
introduce into the crucible where we effect this fusion, inert gas, or reducing gas,
such as hydrogen, carburetted gases, gas containing dust of zinc, aluminium, &c.,
and we introduce these gases by the aid of a blast pipe, or simply through the
interior of the electrodes, which in this case are hollow.
Dated this 30th day of March 1893.
NEWTON & SON,
Agents for the Applicants.

page_text: Improvements in the Extraction of Chromium by Electrolysis,
applicable also to the Production of Chromium Alloys.
We EMILE PLACET and JOSEPH BONNET, both of 95 Boulevard Beaumarchais,
Paris, in the Republic of France, Chemists, 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 :-
In a preceding Patent for the extraction of chromium by the aid of electrolytic
baths (No. 22855 of 1891), we have said that in certain cases we heat our baths so
far as to effect the watery reduction, and also the reduction by heat, of the salts
that we employ. The following is, in effect, how we operate in certain cases.
We take, for example, 10 to 15 grammes of bi-sulphate of potash, 100 grammes
of chrome alum, 100 grammes of water. We heat until the salts are dissolved, and
we cause an electric current to pass through the same. The chromium deposits
immediately at the negative pole, to which may be attached an object of any kind
susceptible of receiving a coating of deposited metal, such as the carbon filaments and
rods used in electric lighting. We keep up the strength of the bath by means of
chrome alum alone, or by means of a concentrated solution of chrome alum and
alkaline bi-sulphate. The addition of these new salts increasing the volume of the
bath, an overflow pipe is provided to maintain at a constant height the level of the
bath. The bath is thus constantly renewed, and can consequently last a long time.
The liquid running away by the overflow pipe crystallizes under the influence of
the cold, and serves again to feed the bath. When we maintain the bath with
chrome alum alone, there arrives a time when all the water that we have employed
to form the bath, will have run away by the overflow pipe, with the salts in
solution. From this time the bath is composed only of salts reduced either by
water or by heat. We can also dispense with the water in the formation of the
bath, and prepare the bath by heating directly the mixture of salts, until they
become melted. We add sometimes to these baths, a little chlorate of potash and
boric acid, benzoic acid, or other analogous salt, in order to assist the deposit of the
metal. In place of bi-sulphate of potash, we employ also, as a flux, the sulphate or
the bi-sulphate of soda, or ammonia, the phosphates, borates, chlorates, silicates,
chlorides, Aluorides, &c., alkalies, or alkaline earths, or a mixture of the same. In
place of chrome alum, we employ also oxide of chromium, and all the other salts of
chromium (nitrate, borate, phosphate, fluoride, chloride, tartrate, &c., of chromium),
which can easily fuse on contact with alkaline or earthy alkaline salts. The fusion
of metallic chromium (previously obtained by electrolysis) requiring a very high
temperature, we generally employ the electric current to effect the same.
Sometimes, in order to obtain this fusion, in place of using positive and negative
electrodes of pure carbon, we employ electrodes composed of carbon, of oxide of
chromium, of salts, or ores of chromium, the whole previously agglomerated with
a flux (borax, phosphate, lime, fluoride, &c.), and a reducer (zinc, magnesium
aluminium &c.), and we thus effect at the same time the reduction and the fusion of
the metal.
On the other hand, we may include in the composition of these electrodes,
different metals, as copper, aluminium, zinc, nickel, silver, &c., or oxides of these
metals, in order to obtain, at one and the same operation, alloys of chromium and
the other metals. Lastly, we find it advantageous to introduce into the vessel
where we effect this fusion, inert gases, or reducing gases, such as hydrogen,
carburetted gases, gas containing dust of zinc, aluminium, &c., and we may
introduce these gases by the aid of a blast pipe, or simply through the interior of
the electrodes, which in this case are hollow.

page_text: Having now particularly described and ascertained the nature of the said inven--
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. The improvements above described for obtaining the electrolytic deposit of
chromium, of all thicknesses, and in large quantities, for the requirements of
manufactures.
2. The improvements above described for obtaining the chromatization of objects
of various kinds, amongst others the carbon filaments and rods used in electric
lighting.
3. The improvements above described for obtaining directly, by electrolysis,
alloys of chromium and other metals.
Dated this 19th dor of December 1802
NEWTON & SON,
Agents for the Applicants..