Improvements in Calcining and Refining Copper Ore, Copper Regulus, and Copper Precipitate, and in the Construction of Furnaces therefor.
Year: 1890

page_text: Date of Application, 30th Jan., 1890-Accepted, 1st Mar., 1890
COMPLETE SPECIFICATION.
Improvements in Calcining and Refining Copper Ore, Copper
Regulus, and Copper Precipitate, and in the Construction of
Furnaces therefor.
I, FREDERICK WILLIAM DÄHNE, of 18 Somerset Place, Swansea, in the County of
Glamorgan, Metallurgical Engineer, 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 :-
The main objects of my invention are the construction of an improved form of
furnace for calcining copper ore, and copper regulus; and the improved treatment
of the said ore, regulus, or precipitate, in such manner that the heat required for
calcination in the furnace is obtained by the decomposition of the material itself,
arsenic and other volatile impurities are completely expelled a larger percentage of
copper is obtained, and the total cost of extraction is only about one half that of the
ordinary process.
In carrying my invention into effect, I first convert all the copper products such
as metallic copper, copper precipitate, poor copper regulus, or copper ores, into a regulus
containing from 70 to 75 per cent. of copper, more or less, preferably 75 per cent.,
"white
this being found the best in practice. Such regulus is commonly known as
metal."
I then crush the said "white metal," and calcine it in the specially constructed
furnace which forms part of my invention. I may however employ any ordinary
form of calcining furnace for this purpose, although by preference, I employ my said
improved furnace.
In the accompanying two sheets of drawings, Fig. 1 is a vertical section, and
Fig. 2 is a sectional plan of a calcining furnace constructed according to my invention.
Similar letters of reference denote similar parts throughout the drawings.
The furnace consists of a series of circular floors, or hearths, supported one above
another in a square brickwork casing E. In the drawings four hearths F. G. H. J.
are shown, but a greater or less number can be employed, if desired. Each floor is
of sufficient size to hold about one ton of material at a time. A mechanical
arrangement is provided for stirring the material on the floors, and consists of a
central vertical shaft K, carrying arms L, provided with teeth M. forming rakes.
This shaft is suspended in a bearing N, and rotated through the medium of the spur
wheel P from any suitable source of power. The shait K and the arms of the
ales Lare hollow, and the necessary air for decomposition enters through the said
saft and escapes into the chambers of the furnace through the ends of the arms L
and through openings in their sides. By this means the air is highly heated before
entering the chambers.
I do not however confine myself to this method of introducing and heating the
air, as it may enter through suitable passages formed in the brickwork E.
Each hearth is provided with a separate exit for the fumes, communicating down-
wardly by separate passages Q. Q1 Q2 Q3 with the main flue R, leading to the chimney.
S is the exit for the hearth G, and S' for the hearth J.
The furnace is started, in the first instance, by making a coke fire in the lower, or
two lower hearths. When by this means the furnace is sufficiently heated, the fire
is drawn and a charge of a ton or thereabouts of "white metal " is introduced on
the top hearth F. through the door T, spread out; and the shaft K and rakes L, set
in motion.
Within 15 minutes the charge will become red hot and calcining will commence,
and the temperature will be effectively maintained by the combustion of the sulphur
contained in the charge. After the expiration of two hours the charge is allowed to

page_text: fall on to the second hearth G, through suitable openings in the hearth F, which are
provided with doors for closing, and a new charge is immediately introduced on to the
upper hearth F. The same operation is simultaneously carried on in the two lower
hearths H and J.
Before the second charges are allowed to descend to the hearths G and J, the first
charges are removed from these hearths, and fall into trucks and are conveyed to the
usual refining furnaces. The total quantity of "white metal," which can be treated
in a furnace of the size illustrated, is 12 tons in 24 hours, and this, as above explained,
is done entirely without any fuel other than that contained in the "white metal
itself, while at the same time obtaining complete decomposition, at a cost not exceeding
one quarter of the cost of caleining in the furnaces now ordinarily used for that
purpose.
I construct the refining furnace in such manner that it will take a 12 ton charge
at a time, and I provide mechanical appliances for charging in 15 minutes, so that
two charges of 12 tons each can be refined in 24 hours in one furnace, yielding
about 18 tons of fine copper.
After treatment in the calcining furnace, and before entering the refining furnace,
I mix the calcined "white metal" with from about 6 to 8 per cent. of carbon, by
preference crushed, or small anthracite coal, as well as with from about 2 to 3 per cent.
of sand, or other suitable silicious matter, 1 to 2 per cent. of lime, and 1 to 2 per cent.
of alumina, to form a flux, and smelt the whole mixture down into metallic copper
and refine the same at once, and in the same smelting or refining furnace. In cases
where the said copper products contain much or any arsenic, or other noxious volatile
impurities, which is generally the case with Spanish copper ores and copper
precipitates, then I add from 3 to 4 per cent. of carbon, by preference crushed, or
small anthracite coal, to the crushed "white metal" in the calcining process, by
which means I expel nearly all the arsenic and other volatile noxious matters during
the said caleining process, and the last traces of such noxious matters will be expelled
during smelting and refining by adding again, as described before, a certain percen-
tage of carbon, lime, silicate, and alumina.
My improvements possess considerable advantages over the refining process hitherto
used, in which all the copper products are first concentrated into "white metal,"
which is then roasted into black or blister copper. This roasting process is :-first,
very wasteful and expensive, and secondly, all the impurities as stated above are
retained in such black or blister copper and by smelting such black or blister copper
down again in the refining furnace for refining purposes, another large waste of
copper is incurred and almost insurmountable difficulties are experienced in expelling
arsenic etc.. from the copper, which in my improved process, as described, is easily
effected and without any loss of copper and at about half the present expense.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
--
1. The improved process for calcining and refining copper ore, copper regulus, and
copper precipitate, substantially as herein set forth.
2. The improved calcining furnace, constructed substantially as herein described and
shewn with reference to the accompanying drawings.
3. The treatment of "white metal," without roasting, substantially as herein set
forth.
4. In the treatment of "white metal," the admixture of carbon therewith for the
purpose of reduction, as well as for expelling the last traces of arsenic and other
impurities, substantially as herein set forth.
Dated this 30th day of January 1890.
AMBROSE MYALL,
21, Cockspur Street, London, S.W., Agent for the Applicant.