“ULRICKE FROSSE to ROBERT DENHAM. _4th July, 1585_.
“To his loving friend, Robert Denham.
“Friend Denham,—I have me heartily commended unto
you, you shall understand it we did lack ore more than
14 days ago, for we have found out a way to smelt 24
cwts. of ore every day with one furnace, the Lord be
thanked, and if we may have ore enough from your side
we may, with God’s help, melt with two furnaces in 40
weeks 560 tons of ore, having reasonable provision
made for it, desiring you from hence-forward to send
such ores as you have with as much speed as maybe, not
caring what ore it is. Your ore of St. Dines is very
hard to melt it, hoping we will overcome it what St.
Ust ores will do, we long to see it.
“This I rest, the Lord send you good success with
your mines. And so I commit you to God. From Neath, the
4th of July, 1585.
“Your friend,
“ULRICKE FROSSE.
“When you do send any more ore, if you can, send
of all sorts, the better it will melt and with more
profit.”
The sound principle of obtaining, when possible, one class of copper
ore for the purpose of fluxing off the gangue from ore of another
class, was thus recognised as a profitable feature of practice from
comparatively early times.
Copper mining and smelting in Staffordshire dates back a considerable
time, certainly prior to 1686; the mines were situated at Ecton, and
the smelter was at Elleston, near Ashbourne, where small blast furnaces
were employed. Copper smelting in Lancashire, which is nowadays
conducted on a comparatively extensive scale, appears to have commenced
in 1720 with Cornish ores and smaller importations from the West Indian
and American Colonies. During the 18th century, the chief supply of
the world’s copper ore came from the Cornish mines, which even at
that time, were deep and extensive. It seems, however, that for some
peculiar reason, the Cornishmen were unable to smelt these ores with
profit, nor indeed, to do more with them than to send the material to
South Wales to be treated. There are numerous explanations for their
failure, which have been discussed exhaustively by Percy.
The centre of the copper smelting industry thus came to be located
in the South Wales (Swansea) district, where circumstances were very
favourable. The study of local conditions is one of great importance
for metallurgists, and since this case affords a good example, it will
be of value to refer briefly to those circumstances which rendered the
Swansea district such an excellent centre for the industry.
The extensive collieries in the locality rendered available an abundant
supply of suitable fuel at a low price, and many of the smelters held a
financial interest in them. The large coal was profitably used for home
consumption or export, and the small, which, though dirty, still gave
the long flame required, was very suitable for smelting work, and was
reserved for that purpose.
Further, Swansea was an excellent seaport, situated at a short distance
only from Cornwall, the chief source of ore, and was also readily
accessible to vessels carrying cupriferous ores and products from
South America, Australia, and other parts of the world. This was a
great advantage, in that the Swansea copper smelters, having a large
variety of ores at their disposal, some with basic gangue, others with
siliceous gangue, were in a position to make up furnace charges which
were more or less self-fluxing, and thus avoided the necessity for
purchasing and using barren fluxes. The finished products were also in
a most convenient centre for distribution, at the seaport of Swansea.
At the end of the 18th century, Great Britain was producing 75 per
cent. of the world’s copper, the Cornish mines supplying most of the
copper ore, and the Swansea smelters extracting most of the world’s
supply of metal. Stevens has summarised the position for 1799, showing
that “from the Cornish ores 4,923 tons of refined copper were produced,
and from the Welsh ores of Anglesea 2,000 tons. The great Mansfeld
mine in Germany produced only 372 tons in that year, Spain’s output
was insignificant, and in the United States only a few tons were made.
Russia and Japan probably ranked next to Great Britain as producers,
small amounts of ore from Austria, Scandinavia, and Italy made up the
remainder. Thus at the commencement of the 19th century, the copper
resources of the United States, Spain, Chili, Mexico, Australia,
Tasmania, Canada, and South Africa, which now supply over 90 per cent.
of the world’s metal, were either undeveloped, or only yielded a few
tons each; Great Britain, which produced nearly 7,000 tons of copper at
that time, extracted from its own ore supplies, a hundred years later,
only 550 tons.”
It will be remembered that it was in connection with the development of
Cornish copper mining that the use of steam power in engineering was
introduced and successfully worked out. On account of the increasing
depth and extension of the Cornwall mines, the problem of disposing
of the underground water became urgent, and led to the introduction
of steam engines for driving the pumps, the Newcomen engine being
installed on the Wheal Fortune Mine in 1720. The success of this engine
led to increase both in depth and in extent of the workings, until it
became impossible to cope with the pumping requirements by this means.
At the right moment Watt brought out the modern steam engine, and the
first Watt engine was erected in 1777 at Chasewater, in Cornwall. It
was the introduction of these improved methods of pumping which have
made possible the successful development of present-day mining. Not
only has the steam engine thus led to an increase in the supply of
copper, by enabling the opening up of vaster deposits to be undertaken,
but the development of engineering science which it has brought about,
has caused a further consumption of the increasing quantity of copper
which it has helped to render available for use.
During the first half of the 19th century Great Britain retained its
position as the chief copper producer of the world, and the Swansea
smelters possessed advantages such as have been rarely enjoyed by any
other body of manufacturers. They were able to impose what conditions
they pleased on the producers and sellers of copper ore, as well as on
the consumers of the metal, and as business men, were not slow to avail
themselves of their opportunities to the greatest possible extent,
strengthening their position by the formation of a combination known as
the Associated Copper Smelters of Swansea, which controlled the price
of the metal from 1850 to 1860. Percy gives an interesting account of
the terms imposed by them under the name of returning charges, etc., as
well as of the conditions of sampling, analysis, and sale, which were
strongly in their favour.
During these years of monopoly, the smelters were, on the whole,
conservative in tendency from the metallurgical point of view, and
few great developments in either processes or methods were devised:
nevertheless, they enjoyed great prosperity, and their business
attained such dimensions that Swansea remains one of the greatest
centres of smelting industry in the world. The Welsh smeltermen had,
moreover, acquired such proficiency in furnace management, and such
knowledge of the working and control of copper charges, that their
reputation had spread to all quarters of the world.
Though from 1840 onward, the British copper mining industry commenced
to decline, still for 20 years longer the Swansea smelting works
prospered more and more as new mines were being opened abroad and thus
furnished a constantly increasing supply of rich copper ore, cheap to
purchase and easy to smelt.
It was this development of foreign copper resources, and the
unsatisfactory conditions which the producers received at the hands
of the smelters, which was the cause of the eventual displacement of
Swansea from its position as the leading seat of copper manufacture.
In 1830, the production of copper ore in Chili had commenced and
developed rapidly, Chili soon becoming one of the chief suppliers of
ore to the Welsh smelters, whose independent attitude led to the first
introduction of the copper-smelting industry on any large scale in
America. Owing to the sailing conditions of the time, the simultaneous
coming into port of several ships laden with ore, instead of their
arrival at regular intervals, enabled purchases to be made by the
smelters at a remarkably low figure, the standard price of the metal
being subsequently raised. Mine-owners commenced to seek for a remedy,
their ultimate endeavour being to substitute, for the exportation of
their ores, smelting operations at or near the mines themselves. In
1842 Lambert introduced reverberatory furnaces into Chili, and so great
was his success, that in a short time they were in use throughout
that country. In 1857 he erected the first blast furnace in Chili,
and the smelting industry thereupon grew so rapidly that, whilst from
1856 to 1865 the copper exports from Chili were in the proportions of
ore 21 per cent., regulus 38 per cent., and bars 40 per cent., they
subsequently became ore 1½ per cent., regulus 3½ per cent., and bars
95 per cent. The ultimate effect was a widening of the market for the
finished Chilian product, so that Continental purchasers were enabled
to obtain their supplies of metal direct, instead of being obliged
to purchase from the Welsh smelters on the unsatisfactory terms then
prevalent.
In 1842 the first large copper mines of Australia (Kapunda and later
Burra Burra) were discovered, but developed slowly; and in 1844 the
first copper mines of the Lake Superior district began work—on oxide
ore, not on native metal.
In 1850 an enormous development in the Chilian mines commenced, half
the world’s copper being produced from this source; in 1859–60 the
Spanish mines at St. Domingo (Mason and Barry) were re-opened, as
well as the Portuguese mine, the Tharsis. These mines were in reality
operated in order to supply the wants of the sulphuric acid industry,
the ore residues being subsequently smelted for copper at Swansea. In
1862, however, the Henderson wet process for copper was introduced,
for which these materials were very suitable, and the Spanish and
Portuguese supplies became of considerable importance, soon afterwards
coming under the control of a Scottish company.
The competition from these new and abundant supplies of rich ores from
Chili, Spain, and Portugal severely injured the production from the
British mines; increasing supplies led to a fall in the price, and one
native mine after another shut down, the British supply diminishing
with considerable rapidity.
In 1866 the great Calumet and Hecla mine at Lake Superior commenced
operations, and speedily became one of the most important sources of
copper in the world; the Moonta and Wallaroo mines in Australia opened
about the same time, and in 1873 the Arizona mines started producing.
In 1876 the enormous Spanish mines at Rio Tinto were re-opened, and
soon rendered available large quantities of ore. Later, the Tasmanian
supplies entered the markets.
In 1880 a remarkable development in copper mining occurred with the
discovery of the Butte camp in Montana; this is now the greatest
producer in the world.
The later extensions of the copper mining industry occurred in Utah,
Tennessee, and Queensland, whilst within recent years the most
important work on a large scale has been commenced in Tanganyika, in
Nevada, and in Siberia.
The developments in the smelting industry in most of these localities
have proceeded, until the last few years, on very similar lines. During
the first periods following the opening up of mines and works, ore
was shipped to the custom smelters, most often to Swansea; where, in
the early days, many of those connected with the smelting works had
some sort of financial interest in the foreign mines. Later, the ore
underwent its first smelting to matte in the mining district itself,
the matte product being then shipped East for treatment, thus saving
much of the freight-charge on useless gangue, as well as smelters’
heavy returning charges, etc. At a later period the smelting operation
was carried to a still further stage in the mining district, crude
blister copper only being sent to Swansea or elsewhere to be refined.
Gradually, electrolytic refineries were established somewhat nearer to
the mining districts, and in the natural course of events, and where
local conditions are not prohibitive, the probability is that the whole
cycle of operations from mining to the production of refined market
metal will be carried out at the great camps themselves.
At present, however, this is not generally the case, since the
conditions under which the enormous refineries in the Eastern States
of New York, New Jersey, and in Baltimore, etc., operate, allow of
the cheaper production of electrolytic copper at points nearer to
the distributing markets. At Anaconda, indeed, the fully-equipped
electrolytic plant was shut down, owing to the commercial conditions
such as have just been indicated, having rendered the refining of
the anode copper at the Eastern refineries more profitable than
electrolytic treatment on the spot.
=The Chief Features in the Development of Modern Copper Smelting
Practice.=—In the early days of copper smelting, the reduction of the
oxidised ores, which were then chiefly available, was not a problem
of very great difficulty, although losses in slag were likely to be
very high, and the operation generally wasteful. When, however, mines
became deeper and sulphide ores had to be smelted, the problem became
rather more complicated. In the first stages of development, such
ores were probably roasted until as much sulphur as possible had been
driven off, leaving practically an oxide charge to be treated by the
older reduction methods involving the attendant extravagance in fuel
consumption and large losses of copper in the slag.
From these crude and wasteful methods the Welsh process was gradually
worked out, and it will ever rank as one of the finest examples of
highly developed smelting practice in the history of metallurgy,
particularly when the times and working conditions are borne in mind.
The process having received such full treatment from most of the common
text-books, it is not proposed to review it in detail here, since,
moreover, it has been largely superseded by more modern processes.
As will be explained later, copper smelting of sulphide ores is
essentially a fractional oxidation—chiefly of iron and sulphur—followed
by the slagging or elimination of extraneous constituents of the ore.
The Welsh process embodied a series of roastings and slaggings which,
though most admirably adjusted for a substantial concentration of the
copper in each succeeding product, allowed of the formation of slags
in the first stages which carried but comparatively little copper, on
account of the low tenor of the matte; whilst the slags in the later
stages of the process, containing more copper on account of their
association with higher grade matte, were made in such relatively small
quantity that their re-treatment for the recovery of these values did
not involve very much loss of efficiency in the furnace operations.
Later modifications of the process were chiefly devised with the view
to reducing the number of operations, by eliminating the successive
roasting stages, for which purpose oxidised materials, such as roasted
or oxidised ores, were added to the charge.
The Best-Selecting process, and the Nicholl and James process are
likewise valuable and ingenious modifications of the Swansea method for
special work.
In general, however, up to 1880, there had taken place but little
change in principle from the older methods of smelting. The chief
improvements involved a slow change in furnace size, and progress in
several details in practice. The more important of these advances were—
(_a_) _In Roasting Practice._—=1865.= Introduction
of the mechanically driven furnace (the Brückner cylinder);
not, however, adopted for copper smelting till many years
afterwards. Later—Arrangements for using roaster gases for
sulphuric acid manufacture.
(_b_) _In Reverberatory Furnace Smelting._—=1861.=
Gas firing introduced, but with very little success for
copper smelting, even at the present day.
(_c_) _In Blast-Furnace Smelting._—Several very important
changes were introduced in the construction of furnaces.
=1863.= Elongation of the furnace.
Rachette in Germany introduced the elliptical blast furnace. (Intended
first for lead smelting; rapidly adopted for copper matte smelting.)
=1875.= The water-jacketing of blast furnaces.
The Piltz water-jacketed furnace was likewise first employed in lead
smelting, and subsequently introduced into copper smelting practice.
The principle had, indeed, been utilised in certain branches of iron
smelting before this date, but for non-ferrous work the idea was new.
Although the method of water-jacketing was recognised as leading to
great improvement in the working of the furnace, its use was at first
somewhat restricted, owing to various practical difficulties, and the
ultimate great success was effected when in American practice, the plan
of working the two principles of elongated furnaces and water-jacketing
in conjunction, was adopted.
Commencing from 1880, and onwards, however, when production in the Far
West began, enormous advances have been made, both in connection with
the principles of working as well as in practical operation. These
include—
(1) Enormous increase in the size and capacity of furnaces
of both the reverberatory and the blast-furnace type.
(2) The application of the Bessemer process to copper mattes.
(3) The development of the pyritic smelting principle.
(4) The adoption of electrolytic refining.
(5) The use of mechanically rabbled roaster furnaces.
(6) The manufacture of sulphuric acid from blast-furnace gases.
(7) The blast-roasting and sintering of sulphide fines.
With an increased output of ore from the mines, and with increased
consumption, stimulated by the growth of the electrical industry, the
demand for metal increased so quickly that developments naturally
followed with a view to an augmented and rapid production by more
efficient and scientific processes; especially since increased
competition and poorer ore supplies necessitated a very decided
lowering of the costs of production. To meet the enormous present-day
demand for metal with the older methods and furnaces would have been
impossible. The greatest stimulus to the adoption of these new or
modified processes was the shifting of the chief producing centres
from the older and more conservative influences to districts like
the then newly awakening West, where, with ever-increasing—almost
limitless—supplies of ore available, and free from the necessity of
considering the capital invested in old plants, the men in charge of
the work, untrammelled by old smelting customs which might stand in the
way of rapid progress, were in a position to develop their ideas with
originality and vigour.
There may, nevertheless, be recalled the important share which British,
and especially Swansea, workmen had in this great development of the
industry. At many of the greater smelters in these new districts, Welsh
furnacemen are still to be found, and large numbers went abroad in
former days to take charge of such work, especially during the critical
early stages. The principles underlying these modern improvements were,
in many cases, first worked out by scientists in Europe.
=The Price and Cost of Production of Copper.=—The price of copper
has been influenced to an enormous extent by financial speculation,
so that until recent times it has fluctuated very considerably from
year to year, the curve in fig. 1 relating to Best Select copper,
indicating this variation over a considerable period. The price of the
other qualities of commercial copper follows this line fairly closely,
electrolytic copper being from £2 to £4 per ton lower, and standard
copper £3 to £6 per ton. The average value of the standard refined
metal at the present time (December, 1911) is about £56 per ton in
London, and about 12 cents per pound in New York.
On three occasions during the past century, and once at least during
the past decade, the market price of copper has been directly affected
by more or less artificial conditions consequent on financial
manipulation. The first of these instances was the 1850–1860 period,
when the Welsh smelters held the monopoly of the copper trade, and
were in a position to fix their own price; the second was during the
French combination of Secretan during 1887–9, which, as a result of
mere market speculation, caused fluctuations of price which amounted on
one occasion to no less than £35 per ton within twenty-four hours. The
third instance was created by the American combine.
[Illustration: Fig. 1.—Fluctuations in the Price of Best Select
Copper.]
In 1899 the Amalgamated Copper Company was formed in the United States.
This corporation was established in view of the enormously increasing
production of the West, and of the extensive development of electrical
industry which involved a greatly increased consumption of copper; and
it was probably designed to control the world’s copper industry. Prices
were raised gradually for some time, but in 1901 the Trust, as then
constituted, failed, owing largely to trade depression in Europe. Heavy
losses resulted, as well as expensive law suits, and the price of the
metal dropped again with great rapidity. Trade subsequently revived
and expanded, the consumption of copper increased and appeared to
overtake the rate of production, whilst stocks diminished and the price
advanced, until, in 1907, copper was sold at well over £100 per ton.
The American financial panic in the autumn of that year again reduced
prices to a comparatively low figure, and they have, on the whole,
remained fairly steady since, though showing a tendency to decrease.
Production has, meanwhile, increased very largely, and a steady price
of 12 to 13½ cents per pound yields handsome profits to most of the
larger concerns. The present situation in the copper market is such
that the enhanced production has again resulted in an accumulation of
stocks, which has occasioned restricted output on the part of many of
the principal smelters until briskness of trade development shall call
forth increased consumption and more satisfactory prices.
The question of price is one involving certain considerations to which
attention may be drawn. The present conditions and the comparative
steadiness in the copper market have been shown in a recent review to
result in part from:—
(1) The concentration of the copper industry in a few
strong hands, which, whilst maintaining healthy competition,
keeps the market free from such outside pressure as would
reduce the price too much, and by restricting unprofitable
output, brings production and consumption into equilibrium,
making for stability.
(2) The comparative cheapness of money, which has allowed
of the financing for large production, with the prospect of
absorption not being long delayed.
At the same time, some of the richer and more cheaply worked mines of
former times are gradually approaching exhaustion—recent instances of
this will be readily recalled, whilst the disadvantages of having to
work lower-grade deposits at greater depth have also tended to increase
the price of metal. These conditions, on the other hand, have been
counterbalanced by improvements in the mining and metallurgical
processes concerned, by the opening up of new districts, and by the
economies resulting from amalgamation of interests, involving closer
organisation and enormous outputs of material.
Apart from finance, two of the factors most likely to affect the price
of the metal considerably are the possible replacement of copper for
electrical transmission purposes by conductors of other metals; and
further, the enormous prospective production in the newer districts,
such as Utah, Nevada, and Tanganyika, in the course of a few years.
The cost of production of the metal is so dependent on local and
general circumstances as not to admit of analysis in this place.
Questions of locality, transport facilities, proximity to supplies
of every kind, problems of labour, capitalisation, bye-products, and
numerous similar considerations have such an important bearing on each
individual case as to convey a definite meaning only to the man on
the spot. In the same way, detail costs of each stage of the copper
smelting processes are influenced by similar circumstances.
Broadly speaking, the average total cost of production and marketing
at present may be taken as being somewhere about 10 cents per pound
of copper; in certain specially favoured cases, 9, 8, or even 7 cents
per pound. The newly opened low-grade “porphyry” camps at Utah and
elsewhere, which have been commenced under an enormous capitalisation,
anticipate a production at a cost of about 6 cents per pound when
steady and normal running is in progress.
A recent analysis gives interesting information with regard to the cost
of production estimated at different plants. Of the American output of
about 480,000 tons in 1909—
Almost 3·5 per cent.
was produced
at a cost of 7·14 cents per lb. (Nevada).
1·8 " 7·98 " (Baltic, Superior).
10·5 " 8–9 " (Utah, etc.).
48·3 " 9–10 " (Boston and Montana,
Calumet and Hecla, etc.).
9·0 " 10–11 " (Utah Consolidated,
Tennessee, etc.).
20·0 " 11–12 " (Anaconda, Arizona, Cananea).
1·8 " 12–13 "
1·1 " 13–14 "
1·4 " 14–15 " (Tamarack).
1·1 " 15–16 "
1·1 " 16–17 "
0·1 " 17·09 "
=Copper Statistics.=—The outstanding features which attract
attention in the statistics of copper production will be most readily
seen from the curves of fig. 2. The enormous increase within recent
years in the total output of metal, and the overwhelming proportion
produced by the United States of America, is clearly indicated. The
curves also show the practical extinction of the native supply of Great
Britain and the steady output of Spain and Germany.
An analysis of the total production for the year 1910 is given in the
following Table I.:—
TABLE I.—THE PRODUCTION OF COPPER (Short Tons of 2,000 lbs.).
1909. 1910.
─┐
U. S. A., 549,114 543,125 │
Canada, 26,998 28,801 │ 1909. 1910.
Newfoundland, 1,546 1,210 ├─ North America,
Mexico, 63,085 68,899 │ 644,058 645,927
Cuba, 3,315 3,892 │
─┘
─┐
Argentina, 672 336 │
Bolivia, 2,240 2,800 ├─ South America,
Chili, 40,079 39,463 │ 60,911 63,101
Peru, 17,920 20,502 │
─┘
─┐
Spain and Portugal, 58,447 56,386 │
Germany, 25,150 27,675 │
Russia, 19,880 24,987 │
Norway, 10,170 11,676 │
Hungary, 5,152 5,550 ├─ Europe, 127,283 135,738
Sweden, 2,240 2,240 │
Italy, 3,052 3,606 │
Austria, 1,809 2,386 │
Turkey, 896 672 │
Great Britain, 487 560 │
─┘
Japan, 52,640 51,520
Africa, 16,738 17,030
Australasia, 38,528 45,153
_______ _______
Total, 940,158 958,469
═══════ ═══════
[Illustration: Fig. 2.—Annual Production of Copper.]
In Table II. is indicated the distribution of the American production
among the various States.
TABLE II.—NORTH AMERICAN PRODUCTION OF COPPER
(in Short Tons of 2,000 lbs.).
1909. 1910.
Alaska, 2,028 2,504
Arizona, 146,021 149,803
California, 26,679 22,897
Colorado, 5,244 5,063
Idaho, 3,885 3,108
Michigan, 113,624 110,700
Montana, 156,918 143,121
Nevada, 25,917 31,944 (about 6,000 tons in 1908)
New Mexico, 2,567 1,816
Utah, 50,219 62,521 (about 35,000 tons in 1908)
Wyoming, 44 90
South and East, 11,409 9,098
Other States, 1,973 463
———- —-———-
Totals, 546,538 543,125
There will be noticed a decline in the production of the United States
during the year 1910, resulting from the present movement to restrict
output whilst the large accumulated stocks of metal are being absorbed.
The movement is probably more or less temporary, and is being largely
directed by American financiers who are endeavouring to bring about an
international agreement on the subject.
Regarding the American output, the marked movement for curtailment in
Montana has reduced the output of that State to such an extent, that
the position it gained in 1909, of being the greatest producing State
once more reverts to Arizona. The increases from Nevada and Utah, in
which developments on a large scale are commencing, may be noted.
References.
Percy, John, “Metallurgy (Copper).”
Gowland, William, Presidential Address,
_Trans. Inst. Mining and Metallurgy_,
vol. xvi., 1906–7, pp. 265–291.
Stevens, H. J., “The Copper Handbook.”
Brown, N., and Turnbull, C. C., “A Century of Copper.”
_Engineering and Mining Journal_, “Copper Production.”
May 6th, 1910, p. 891.
_Mineral Statistics of the United Kingdom._
_Mineral Industry._