Improvements in the Manufacture of Copper.
Year: 1889

page_text: Date of Application, 20th Mar., 1889
Complete Specification Left, 20th Dec., 1889-Accepted, 1st Feb., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Copper.
I, PEROY CARLYLE GILCHRIST of 101 Palace Chambers, Bridge Street in the
City of Westminster, Metallurgist, do hereby declare the nature of this invention to
be as follows:
This invention relates to the manufacture of copper and to the purifying thereof
from certain substances or impurities associated with it in certain stages of the
manufacture of pure or refined copper, more especially from arsenic antimony
and tin.
By my invention I carry out certain of the operations in connection with the
production of refined copper in furnaces which are furnished with linings made
of shrunk dolomite, magnesia, or other basic or neutral material, by which means it
is possible to maintain during the operation of refining, a basic slag instead of the
acid slag as hitherto. Instead of employing a lining composed of shrunk dolomite
or magnesia a lining of chrome iron ore may be employed.
I do not employ such linings in all the stages of copper refining but I find
that such linings can be advantageously employed in the following operations,
in the fusion of calcined coarse metal, in the roasting of the white or fine metal
for the production of blister copper, and in the refining of copper from blister or bar
copper.
By my invention I am able to purify the blister or black copper or other form of
impure copper, and to obtain a product more free from injurious foreign elements
such as arsenic, antimony, tin &c., than can be ordinarily produced under the
conditions now practised."
I perform the operation of refining the coarse, white, blistor, or other form of
impure copper either in a reverberatory furnace as at present used, or preferably in an
open hearth regenerative gas furnace or other convenient form of apparatus, in
either case furnished with a basic or chrome lining. The charge of coarse, white
metal, blister or other impure copper is placed in the basic furnace and melted down
in an oxidizing atmosphere as at present, I charge with or among the copper some
lime or limestone and with or without copper slags rich in oxide. When the bath is
thoroughly molten I charge carefully successive additions of lime or fine limestone,
and when necessary some copper slags rich in oxide, the object being to obtain
the oxidation of the arsenic, antimony, and tin present, either by means of the
atmospheric air or by means of the small amount of cuprous oxide which forms, and
to combine and fix the impurities in the slag. The amount of lime or limestone
to be used varies with the composition of the charge.
The slag should not be very silicious, it is preferable always to keep the silica
under 20 per cent., the best results being obtainable when silica is under
10 per cent.
Samples are taken from the bath from time to time in the usual manner until the
purification is considered complete.
Do this 20th day of March 1889

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Copper.
I, PERCY CARLYLE GILCHRIST of 101 Palace Chambers, Bridge Street in the City
of Wastminster, Metallurgist, 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 the manufacture of copper and to the purifying thereof
from certain substances or impurities associated with it in certain stages in the
manufacture of pure or refined copper, and more especially to its purification from
arsenic antimony and tin.
By my invention I carry out certain of the operations in connection with the
production of metallic copper in furnaces which are furnished with linings composed
of shrunk dolomite, magnesia, chrome iron ore, or other basic or neutral material by
which menus it is possible to maintain during the operation of refining a basic slag
instead of the acid slag as hitherto. I do not employ such linings in all the stages of
copper refining but I find that such linings can be advantageously employed in the
following operations :-
In the roasting of white or pimple metal for the production of blister copper,
in the treatment of metallic bottoms for the removal of arsenic and conversion
into blister or into refined copper, and also in the toughening and refining of
blister copper.
By my invention I am able whilst removing the arsenic etc. from metallic bottoms
or when treating white metal or blister copper, to obtain in each case a purer product
than is at present obtained, together with a larger yield and increased output. For
roasting the white metal and for refining and toughening the blister or other form
of impure copper, I make use of either a reverberatory furnace as at present employed,
or an open hearth regenerative gas furnace or other convenient form of apparatus,
in either case furnished with a basic or chrome lining.
For roasting white metal 1 prefer to employ a reverberatory furnace as at present
employed, lined however with a basic or chrome iron ore lining and preferably
furnished with an air blast or tuyere, the melt is melted down as at prosent in a
strongly oxidizing atmosphere.
I have found that a suitable amount of lime to add when charging white metal
containing 75 per cent. of copper, is from two to three cwts. por seven tons of white
metal charged. The metal should be melted down slowly under air. The slag is
skimmed off from time to time as is usual when working on a sand bottom, much
less slag however will be formed than is usual in sand lined furnaces. A good
heat should be kept on the furnace throughout the charge. It is often advan-
tageous to add a few shovels full of lime to the slag shortly before tapping the
charge.
When treating blister metal, metallic bottoms, or other form of impure copper,
the charge is placed in the basic furnace and melted down in an oxidizing
atmosphere as at present. I charge on the furnace bottom some lime or limestone
with or without copper slags rich in oxide. When the bath is thoroughly molten
more lime may be carefully added as it is seen that the bath will take it up. Care
must be taken however not to form too thick a slag or the operation will be
retarded. It is often convenient to charge in also some copper oxides or slags,
and to subject the surface of the bath to the action of an air blast, the oxidizing action
of which materially helps the elimination of the arsenic. The object of the smelter
should be to obtain as little slag as possible and with a low percentage of copper
in it.
1 find, for example, that when treating a charge consisting of 7 tons of metallic
bottonis containing from 4 to 6 per cent. of arsenic that 5 to 7 cwts. of lime or its
equivalent in limestone may be conveniently added with the charge. The charge
should be melted down under air for five or six hours as usual. When it is

page_text: found that the whole charge is clear off the bottom the first skimming of slag
may be made, this will usually be a larger skimming than any subsequent one.
When a blast tuyere is attached to the furnace the blast may be blown on the
surface of the metal to hasten the elimination of the impurities.
Skimmings of slag should be made three or four times as desirable. When the
sample begins to show a blister fracture a few shovels of lime are to be added once or
twice until the bath is ready for tapping. The slags obtained when working as
described will not average more than 80% of copper, whereas when working with
the ordinary sand bottoms the slag usually averages 55 % of copper, besides weighing
considerably more per ton of blister produced. I have found when treating 400 tons
of metallic bottoms in a basic lined furnace that there was obtained 323 tons of
blister and 102 tons of slag, averaging 25% of copper, and that when treating an
equal weight of metallic bottoms in a sand lined furnace there was obtained 191 tons
of blister only, and 221 tons of slag averaging 55% of copper.
In working according to my invention the silica in the slag should always be kept
as low as possible, say under 10%. I prefer to work with a slag in which the
silica is not over 20%, as I find that with more silicious slags the elimination of
the impurities takes place more slowly.
For this cause it is advantageous to cast the cupriferous material destined for
treatment in basic lined furnaces either in iron moulds or in coke dust. The
amount of lime or limestone it is most advantageons to add to the charge will vary
according to the composition of the material it is desired to treat.
I find that when removing arsenic from metallic bottoms containing 6% of arsenic
or thereabouts, that a large part of the arsenic is volatilized and is not to be found in
the slag. The smelter should ain at volatilizing as large an amount of arsenic and
sulphur as he possibly can, so that there may be as little slag as possible to go hack
to be resmelted.
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 :-
1st. The purification and treatment of cupriferous reguluses and mattes and copper
in basic or neutrally lined vessels in the presence of a basic slag whereby a slag lower
in copper oxide than has heretofore been usual is obtained with a correspondingly
larger yield of metallic copper substantially as set forth.
2nd. The treatment of cupriferous reguluses or mattes and copper in basic lined
furnaces for the removal of arsenic partly by combining it with lime in the slag in
place of copper oxide as at present, and partly by volatilization, substantially in the
manner herein described.
Dated this 20th day of December 1889.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Applicant's Agent.