IMPROVE- MENTS IN THE MANUFACTURE OF SULPHURIC ACID, AND ALSO IN SEPARATING COPPER AND SILVER FROM THEIR ORES
Year: 1861

page_text: PROVISIONAL SPECIFICATION left by George Dryden Mease at the Office
of the Commissioners of Patents, with his Petition, on the 7th January
1861.
I, GEORGE DRYDEN MEASE, of the Lake Chemical Works, East Jarrow,
South Shields, do hereby declare the nature of the Invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF SULPHURIC ACID, AND ALSO IN SEPARATING
COPPER AND SILVER FROM THEIR ORES," to be as follows:-
This Invention has for its object improvements in the manufacture of
In
sulphuric acid, and also in separating copper and silver from their ores.
the manufacture of sulphuric acid in place of employing pyrites as is com-
monly done, I employ poor sulphuret ores of copper, such as contain a large
percentage of sulphur are suitable. These ores also contain iron, and in
burning them to produce sulphurous acid I so conduct the process as (as far
as possible) to bring the copper and the iron into forms in which they are
readily separated the one from the other, that is to say, I endeavour to convert
the copper into sulphate, and the iron into peroxide. The copper then will be
soluble in water, and the iron insoluble. For this purpose I burn the copper
ore in a kiln, such as is commonly used for burning iron pyrites; but I modify
the process by causing steam to pass through or come in contact with the
ore whilst it is burning; this favours the formation both of sulphate of

page_text: copper and peroxide of iron. The sulphurous acid gas is mixed with nitrous
gases and passed into the leaden chamber as is usual in the manufacture of
sulphuric acid.
In burning copper ore, as above described, it is not possible to convert the
whole of the copper into sulphate, and the whole of the iron into peroxide.
I therefore, when the burning is complete, proceed to grind the ore to powder,
and as after the burning the ore will not contain sufficient sulphur to insure
conversion of the remaining copper into sulphate, I mix with the burnt ore
protosulpliate of iron (which, as will be hereafter seen, is a product of the
process I pursue) or in place of protosulphate of iron, a portion of crude ore
or sulphur may be employed. I then expose the mixture to the combined
action of heat and moisture. I prefer to mix a solution of sulphate of iron
with the powdered ore, so as thoroughly to moisten it, and then to put the
mixture into a stove or furnace and heat it to a low red heat; then again
to apply water to moisten the mass in the furnace, continuing the heat of the
furnace as before, and so on for several successive times. Or, in place of this
arrangement, I put the burnt and powdered orc into the stove or furnace and
heat it to a low red heat, and then let down upon it or apply in small streams,
first, the solution of sulphate of iron, and then the water, the quantity poured
on being so regulated that the ore may be maintained at a uniform heat
throughout the process. After some time it will be found that the conversion of
the coppor into sulphate, and the iron into peroxide, is complete. I then draw
the charge, and dissolve out the copper with water, the clear solution I run off
on to metallic iron, which precipitates the copper and produces protosulphate
of iron. The copper is separated and freed from iron, which otherwise it
would contain in small quantity, by hydrochloric aold or otherwise, as herein-
after described; and the solution of protosulphate of iron is evaporated, and a
portion of the salt crystallized out. The mother liquor is the solution of proto-
sulphate of iron, which I employ for mixing with the burnt are, as before
mentioned.
In some cases before or after exposing the burnt ore to the combined action
of heat and moisture in the furnace, as before explained, I place it (when
powdered) in trays, over which the vapours from burning ore are caused to
pass after they have been combined with the nitrous vapours, and before they
enter the leaden chamber.
An important feature of the process is the submitting the burnt ore to the
combined influence of heat and moisture as described, and this is also applicable
to the treatment of ores containing copper and iron which have not been burnt

page_text: for the manufacture of sulphuric acid. When sulphuret ores are employed, in
some cases it is necessary only to powder the ore and to raise it to a suitable
heat, watering it from time to time, or continuously, whilst in the furnace, in
the manner already set forth.
In some cases it is desirable to. roast off, in the first place, a portion of the
sulphur, or the sulphuret ore may be mixed with oxide or carbonate ore to
reduce to the required extent the per-centage of sulphur. When oxide or
carbonate ores are treated alone, then, together with water in the stove or
furnace, sulphate of iron is employed as when treating burnt ore, and the
process proceeds as before; or, chloride of iron may be employed, which will
leave the copper in the form of chloride and the iron as peroxide, which allows
of their being separated as before. Hydrochloric acid, sulphuric acid, and
sulphur may also be similarly employed in conjunction with heat and
moisture.
The waste material known as manganese liquor, and which is produced in
the manufacture of chlorine, is very suitable for use for this purpose, as it
contains both ebloride of iron and hydrochloric acid, together with which there
is some chlorine. I use this waste liquor also to separate from the pre-
cipitated copper the small quantity of iron it will contain, having firshow-
ever, neutralized the chlorine with sulphate iron or otherwise.
If the copper ores treated contain silver, the same will, if a sulphur process
is employed, become converted into sulphate, which is soluble in water, and
may be precipitated by metallic coppor before the copper is thrown down
by iron.
If a chlorine process is employed, the silver is converted into chloride, which
is insoluble in water, and it will therefore remain in the ore when the copper
is dissolved out from it by water; but, if preferred, salt water may be used to
dissolve both simultaneously. The ore must, in case of water being used,
be subsequently treated to separate the silver by one or other of the usual
processes.
In the sulphur process the silver will also become converted into chloride,
if the water employed to moisten it and otherwise in its treatment contains
chlorine.
The process now sometimes employed of roasting copper ore with common
salt to convert the copper into chloride and the iron into peroxide, is rendered
much more rapid and complete by the application of moisture during the
roasting process. The moisture may be applied either at intervals or con-
tinuously, as before.

page_text: Silver ores either not containing copper, or from which it is not desired to
separate copper, may be treated as copper ores by heat and moisture com-
bined, to convert the silver into sulphate or chloride, suitable salts being added
to the ore when required. Besides the salts already named as suitable for use
for this purpose when treating copper ore, chloride of copper or of zinc may
be employed when a silver ore is under treatment.