Improvements in the Production of Aluminium
Year: 1887

page_text: Date of Application, 2nd July, 1887
Complete Left, 29th Mar., 1888
Complete Accepted, 4th May, 1888
Improvements in the Production of Aluminium,
WO CHARLES ANTHONY BURGHARDT, of King Street in the City of Manchester
County of Lancaster, Analytical Chemist and WILLIAM JAMES TWINING of St. Bees
Street, in the same City Electro Plater do hereby declare the nature of this Invention
to be as follows:-
Our said Invention relates to improvements in the manufacture of aluminium, and
has for its object to cheapen the cost of production. A solution from which aluminium
can be economically extracted is prepared in the following manner. We take a
quantity of aluminium sulphate or other suitable salt of aluminium and dissolve it
in water the contained aluminium being precipitated as hydrated aluminium oxide
(Al, O 3 H, 0) by the addition of an excess of ammonia solution (ammonical liquor)
or otherwise caustic soda, caustic potash or the carbonates of these fixed alkalies is
added to the solution of the aluminium salt in such proportion as will precipitate out
all the aluminium as hydrated oxide of aluminium. The aluminium thus obtained is
washed to free it from saline impurities and is afterwards dissolved in an excess of
caustic soda or caustic potash solution, thus forming so called aluminates of these
metals or we purchase the so called aluminate of sodium or aluminate of potassium of
commerce and dissolve the same in water. To the solution of aluminate thus obtained,
we add a proportion of potassium cyanide and boil the solution for some time.
then add potassium bicarbonate or sodium bicarbonate to the solution and boil the
whole for 12 or 16 hours or longer if requisite until the solution becomes sufficiently
clear, and finally to make the solution deposit the metal in a bright condition we add
a small quantity of a solution of hydrocyanic acid gas or we prepare the hydrocyanic
acid gas by any suitable means and pass it through and into the above solution until
the desired effect is obtained.
We
The aluminium metal is obtained from the hereinbefore described solution according
to one method by electro deposition. In this instance we heat the solution to about
160° Fahrenheit or to a higher or lower temperature. If it be desired to deposit the
metal upon another metal or object as in the process of electro-plating we suspend
the object to be plated in the usual manner in a bath of the solution and use either an

page_text: aluminium or platinum anode. The requisite electric current is derived from a
dynamo-electric machine or from a galvanic battery of sufficient power. When it is
desired to precipitate the metal aluminium out of the solution a carbon pole is
substituted for the object in conjunction with an anode of platinum or aluminium.
Another mode of obtaining the aluminium metal from the solution is as follows
The solution is evaporated leaving the dry compound of aluminium. We place this
dry compound of aluminium in a suitable clay or other vessel or crucible and heat it
to an intense heat in a furnace until the metal is reduced out of the mass in the
crucible and most of the saline matter volatilized away. The aluminium metal is then
poured out of the crucible.

page_text: COMPLETE SPECIFICATION.
Improvements in the Production of Aluminium.
We CHARLES ANTHONY BURGHARDT of King Street, in the City of Manchester,
County of Lancaster, Analytical Chemist and WILLIAM JAMES TWINING of St. Bees
Street, in the same City, Electro Plater, 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, that is to say :--
Our said Invention relates to improvements in the manufacture of aluminium and
has for its object to cheapen the cost of production. A solution from which aluminium
can be economically extracted is prepared in the following manner. Wo tako a
quantity of aluminium sulphate or other suitable salt of aluminium and dissolve it in
water the contained aluminium being precipitated as hydrated aluminium oxido
(Al, O, 3 H, 0) by the addition of an excess of ammonia solution (ammonical liquor)
or otherwise caustic soda, caustic potash or the carbonate of one of these fixed alkalies
is added to the solution of the aluminium salt in such proportion as will precipitate out
all the aluminium as hydrated oxide of aluminium. The aluminia thus obtained is
washed to free it from saline impurities and is afterwards dissolved in an excess of
caustic soda or caustic potash solution, thus forming so called aluminates of these
metals. To the solution of aluminate thus obtained we add a proportion of potassium
cyanide and boil the solution for some time. We then add potassium bicarbonate or
sodium bicarbonate to the solution and boil the whole for 12 hours or longer if
requisite until the solution becomes sufficiently clear, and finally to make the solution
deposit the metal in a bright condition we add a small quantity of a solution of
hydrocyanic acid gas or we prepare the hydrocyanic acid gas by any suitable means
and pass it through and into the above solution until the desired effect is obtained.
In order that the method whereby we carry our invention into practical effect may
be well understood we will furnish instructions for the production of a plating bath
containing say 7.20 ounces avoirdupois of the metal aluminium to one gallon of water.
Take 5 lbs. 9 oz. avoirdupois of aluminium sulphate containing 9.2 per cent. of
metallic aluminium dissolve in water and precipitate out the hydrated oxide of
aluminium by adding an excess of liquor ammonia or ammonia solution. Allow the
precipitate to subside pour off the supernatant water and repeat this washing several
times or until all or most of the ammonia sulphate produced by the adding of the
aluminium sulphate to the ammonia solution is removed. Then dissolve 24 lbs. of
good caustic soda containing about 70 per cent. of soda in about one quart of water or
if preferred caustic potash may be used. The equivalent amount required can be
calculated by a practical chemist after making an analysis of the caustic potash and
comparing it with the 70 per cent. caustic soda. We find that 31 of soda (Na O) are
equal to 471 of potash (KO) but we prefer to use the caustic soda as being the most
economical.
Having prepared the caustic soda solution we place the washed hydrated oxide of
aluminium in a pan or suitable vessel add about one quart of water and gradually add

page_text: the cold caustic soda solution stirring the whole constantly until nearly all the alumina
is dissolved. We prefer to leave a small proportion of the alumina undissolved in
order to avoid having an excess of caustic soda which is objectionable. To the
contents of the vessel add a solution of 4 lbs. of potassium cyanide of 95 per cent.
strength in one quart of water and also add gradually 2 lbs. of potassium Bicarbonate
and then boil the whole for about 12 hours or more until the solution becomes
sufficiently clear adding water to make one gallon of solution. To obtain the
deposition of the metal in a bright condition add a small quantity of a solution of
hydrocyanic acid gas or pass such gas through and into the solution for a suitable period
of time. We may shorten the process by obtaining the ready prepared aluminate of
sodium or aluminate of potassium and after determining the percentage of contained
aluminium dissolve the selected aluminate in water and then proceed with the process
as already described by adding the potassium cyanide and potassium Bicarbonate.
The aluminium metal is obtained from the solution so prepared by electro deposition.
We heat the solution to about 175° Fahrenheit or to a suitable temperature. If it
be desired to deposit the metal upon another metal or object as in the process of
electro-plating we suspend the object to be plated in the usual manner in a bath
of the solution and use either an aluminium or platinum anode. The requisite electric
current, is derived from a dynamo-electric machine or from a galvanic battery of
sufficient power: When it is desired to precipitato the metal aluminium cut of the
solution a cathode of copper or of carbon or other suitable substance is substituted
for the object in conjunction with an anode of platinum or aluminium. We do not
confine ourselves to the precise proportionate quantities of the materials used in the
preparation of the bath as herein given the quantities stated herein having been
furnished by way of example.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed wo declare that what we
claim is:-
(1) The process for the preparation of a bath for use in the electro deposition of
aluminium substantially as herein set forth.
(2) In the preparation of a bath for the indicated uses the addition to a solution of
aluminate of sodium or of aluminate of potassium; of potassium cyanide and of
sodium Bicarbonate or Potassium Bicarbonate and the boiling of the solution substantially
as set forth.
(3) In the production of aluminium as a bright electro deposited coating the use of
a bath prepared by adding potassium cyanide and sodium bicarbonate or potassium
bicarbonate to a solution of aluminate of sodium or aluminate of potassium and by
boiling the solution and by the further treatment with hydrocyanic acid gas or with a
solution of such gas substantially as set forth.
Dated this 28th day of March 1888.