Improvements in a Process and Apparatus for the Electrolytic Production of Metallic Zino and Metallic Copper from Zino Ores Containing Copper, and Oxygen Gas as a Bye-product.
Year: 1895

page_text: Date of Application, 23rd Oct., 1895
Complete Specification Left, 22nd Aug., 1896-Accepted, 26th Sept., 1996
PROVISIONAL SPECIFICATION.
Improvements in a Process and Apparatus for the Electrolytic
Production of Metallic Zino and Metallic Copper from Zino Ores
Containing Copper, and Oxygen Gas as a Bye-product.
Wo CHARLES ANTHONY BURGHARDT of 35 Fountain Street, in the City of
Manchester, in the County of Lancaster, Analytical Chemist, and GILBERT RIGG
of No. 1, Ellesmere Grove, Eccles, in the County of Lancaster, Analytical
Chemist do hereby declare the nature of this invention to be as follows :-
Our invention relates to the production of metallio zine and metallic copper
from ores of zino containing copper with simultaneous production of oxygen gas
by first caloining or roasting the ore of zinc in the usual manner to oxide taking
special caro at the end of the roasting to so raise the temperature that any
sulphate of zinc or sulphate of copper formed shall be decomposed and converted
into the oxide of those metals. The thoroughly roasted calciued ore is now
crushed into a powder and placed in a suitable tank fitted with a mechanical
stirrer and a concentrated solution of either normal carbonate of ammonium
(NH),CO, or the sesquicarbonate of ammonium {(NH),CO, + 2 NHHCO₂}
or the bicarbonate of ammouium (NHÂHCO,) poured upon the ore in the tank.
The liquid in the tank is kept covered with a layer of paraffin oil or other mineral
oil of high flashing point and low viscosity in order to prevent loss of ammonia by
volatilization, and the mechanical stirrer set in motion. The oxides of zinc and
copper are rapidly dissolved out of the ore by this treatment. The solution is
allowed to settle out all undissolved material and run out into another tank and
again covered with a layer of paraffin oil or other mineral oil where it is
subsequently treated to separate out of it any dissolved oxides of iron with the
recovery of the copper held in solution. In the course of our investigations and
experiments we have ascertained that sinall quantities of the oxides of iron are
dissolved by the above mentioned ammonium salts, and that this dissolved iron is
highly detrimental in the subsequent electric deposition of the zino causing it to
fall from the negative pole in a spongy condition and re-enter into solution whilst
the zino remaining on the negative pole always contains iron as an impurity. In
order to remove the iron in solution we add to the same kept at a temperature of
from 40°-50° Centigrade a certain quantity of hydrated oxide of tin obtained by
any convenient chemical method, by preference by oxydation of metallic tin with
nitric acid and subsequent washing and drying of the product. The hydrated
oxide of tin is kept well agitated in the solution and in a few hours the iron is
completely precipitated. After the hydrated oxide of tin has become saturated
with oxide of iron it is treated with dilute sulphuric acid which readers it again
fit for service. We now proceed to remove the copper from the above purifiod
solution by placing therein plates of metallic zinc or preferably plates of zinc and
of tin in contact acting as a couple. The copper deposits upon the zinc in hard
and bright metallic scales and strips owing to the exclusion of the air by the layer
of paraffin oil or mineral oil. The liquor now remaining consists of a pure
solution of zinc oxide in the above mentioned ammonium carbonates and is now
ready for electrolysis. It is run into depositing tanks made of wood or other
suitable material iron being excluded, the solution being covered with a layer of
paraffin oil or other mineral oil of high flashing point and low viscosity
and maintained at a temperature of about 50° Centigrade. The negative poles

page_text: are made of sheet zinc and the positive poles of tin, lead or other metal not
soluble in the liquid. Iron poles cannot be used for the reason given above.
Deposition of zinc at the negative pole and evolution of oxygen gas at the positive
pole commence as soon as the circuit is closed, the zinc being in the form of hard
coherent sheets of bright metallic lustre and easily separated from the negative
pole. We find that for every atom of zino deposited on the negative pole one
atom of oxygen is liberated at the positive pole. We may say here that no
hydrogen gas is liberated throughout the electrolysis. The oxygen gas is collected
as it is evolved by any convenient means and washed with water to remove any
traces of ammonia from it. The sheets of deposited zinc after removal from
tho negativo poles are easily melted and cast into ingots or otherwise dealt with.
A solution of ammonia gas in water may be used to dissolve the oxides of zinc
and copper in the above mentioned roasted ore but we find that no oxygen gas is
liberated in the electrolysis of the solution.
The material remaining undissolved by the carbonates of ammonium is thoroughly
washed with water under a layer of paraffin oil to recover the contained solution
of ammonium carbonates and zino and copper oxides.
After depositing the zine out of the above mentioned solution the exhausted
liquor is run back into the dissolving tank upon another charge of roasted ore and
resaturated with the oxides as abovo described and tho above described process
repeated.
Dated this Twant cocond day of October 180K
COMPLETE SPECIFICATION.
Improvements in a Process and Apparatus for the Electrolytic
Production of Metallic Zine and Metallic Copper from Zino Ores
Containing Copper, and Oxygen Gas as a Bye-product.
We Dr. CHARLES ANTHONY BURGHARDT, of 35 Fountain Street, Manchester,
in the County of Lancaster, Analytical Chemist, and Professor of Mineralogy in
the Victorin University, and GILBERT RIGG, of No. 1 Ellesmere Grove, Eccles,
in the County of Lancaster, Analytical 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 that is to say :-
Our invention relates to the recovery of metallic zinc and metallic copper from
zine ores containing copper with simultaneous production of oxygen gas in the
specified instances.
In carrying our invention into effect tho ore is first roasted to oxide in the usual
manner, care being taken at the end of the roasting to so raise the temperature that
any sulphate of zinc or sulphate of copper formed shall be decomposed and converted
into the oxides of these metals. The thoroughly roasted oru is now crushed into
powder and placed in a suitable tank fitted with a mechanical stirrer or agitator.
We then pour upon the crushed ore in the tank a concentrated solution of either
the normal carbonate of ammonium {(NH),CO,} or the sesquicarbonate of
'ammonium {(NH),CO, + 2 NH,HCO,} or the bicarbonate of ainmonium
{(NH,HCO₂)} or mixtures of these or a solution of aminouia gas in water.
We may here mention that where a solution of ammonia gas in water is used
there is no evolution of oxygen gas in the later stages of the process. Sufficient
solution having been poured upon the ore in the tank we next cover the surface of
the liquid with a layer of paraffin oil or other mineral oil of high flashing point
and low viscosity, in order to prevent loss of ammonia by volatilization.

page_text: The mechanical stirrer is now set in motion so as to mix the powdered ore
thoroughly with the solution.
The oxides of zinc and copper are rapidly dissolved out of the ore powdor by this
treatment. The stirrer is then stopped and the solution allowed to settle, all'.
undissolved mechanically suspended matter falling to the bottom of the tank or
otherwise the undissolved mattor may be separated by filtration. The solution is
then run into another tank and again covered with a layer of oil as in the first
instance. We now treat the solution to remove from it any dissolved oxides of
iron. In the course of our investigations we have ascertained that small quantities
of the oxides of iron are dissolved by the aforesaid carbonate of ammonium and
solution of ammonia gas in water and this dissolved iron is highly detrimental in
the subsequent electrolytio deposition of the ziuc, causing it to fall from the
negative pole in a spongy condition and re-enter into solution, while any zino
which does remain on the negative pole always contains iron as an impurity. It
is therefore essential to remove the oxides of iron from the solution and to do this
we add to the same, proferably at a temperature of about 40 degrees Contigrade,
a proportion of hydrated oxide of tin obtained by any convenient and well known
chemical method, but by preference by oxidation of metallic tin with nitric acid
and subsequent washing and drying of the product. After adding the hydrated
oxide of tin to the solution, it is kept well agitated by any suitable mechanical
means, and in a few hours the iron in the solution is completely precipitated as
oxide. The oxide of tin is then allowed to subsido to the bottom of the tank and
the clear solution is run into a fresh tank. To render the hydrated tin oxide
again fit for service after it has become saturated with oxide of iron, it is placed in
a suitablo vessel and treated with sulphuric acid and washed with water, the iron
passing into solution as sulphate. The iron might however be extracted from the
solution by other meaus although we at present consider the said hydrated oxide
of tin to be the best agent for the purpose. To recover the copper from the
solution we place in the tank, plates of metallic zinc or platos of metallic zinc and
metallic tin in contact and acting as a couple. After immersion the copper begins
to deposit upon the zinc in hard, bright metallic scales and strips entirely free from
oxide, owing to the exclusion of air by the layer of mineral oil. The solution is
thus freed from its contained copper and is then run into tanks.
In the zinc depositing tanks the solution is subjected to electrolysis and is
covered as before with a layer of oil and maintained at a temperature of about
40 to 50 degrees Centigrade. We may here mention that the tanks used in our
improved process after the solution has been freed from iron should be made of
wood or of other suitable material, iron being excluded because of its hurtful effect
upon the deposition of the zinc. In the electro-depositing tanks, the negative
poles are made of sheet zino and the positive poles of tin, lead or other metal not
soluble in the liquor. Iron poles cannot be used for the reasons already given.
Deposition of zinc at the negative pole and evolution of oxygen gas at the positive
polo commence as soon as the circuit is closed, in solutions prepared from the
carbonates of aminonium, the zinc being deposited in the form of hard coherent
sheets of bright metallic lustre and easily separated from the negative pole. We
have found that for every atom of zinc deposited on the negative pule one atom of
oxygen gas is liberated at the positive pole. No hydrogen gas is liberated during
electrolysis. The oxygen gas is collected as it is evolved by the meaus usually
employed to trap such gas in the manufacture of oxygen or by any other
convenient means, the gas being washed with water to remove any traces of
ammonia from it.
It may be here repeated that no oxygen gas is evolved in a solution of ammonia
gas in water. The sheets of deposited zinc after removal from the negative poles
are easily melted and cast into inguts or otherwise dealt with. The material
remaining undissolved by the carbonate of ammonium solution or the solution of
ammonia gas in water is thoroughly washed with water under a layer of paraffin
or other mineral oil, to recover the contained solution of ammonium carbonates or

page_text: ammonia and zinc oxides or zinc and copper oxides. After depositing the zino out
of the aforesaid solutions, the exhausted liquor is run back into the first dissolving
tank upon another supply of roasted and ground ore, whereupon it becomes
recharged with oxide of zinc or oxides of zino and copper as hereinbefore described,
the processes set forth being then repeated.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is.
1. The improved process for recovering metallic zinc and metallic copper from
zine ores containing copper, by treating the roasted and ground ores with one of
the described solutions, freeing the resultant liquor from iron by means of hydrated
oxide of tin or other suitable agent, recovering the copper from the solution by
means of immersed zinc or zinc and tin plates and thereafter obtaining the metallío
zine by electrolytic deposition substantially as described.
2. The manufacture of oxygen gas effected during the electro-deposition of zinc
in the course of carrying our improved process into effect, substantially as
hereinbefore described.
3. In carrying out the indicated process, preventing the loss of ammonia from
the solution by covering it with a layer of paraffin or other mineral oil as set forth.
Dated the 21st day of August 1896.