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International Engineering Congress (1901 : Glasgow.

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present practice, and only 4.64 tons were crushed, showing an
increased output of 35.1 per cent, in favour of the 6.277 tons in
series crushing, and with at least 25 per cent, less slimes.



230 IMPERFECT PULVERISATION OF ROCKS BY STAMPING.

The paper further points out that in dry crushing with rolls, as
soon as the material enters the point of contact and becomes crushed
it sets up a pack in a similar manner to what is done in the
stamping operation. This pack lifts the roll, and consequently
prevents fine crushing, as it allows particles of rock to pass
through ; and if a separation were made, it could be crushed in one
operation to the required size. This is, of course, the reason why
finishing rolls have to be adopted in many instances.

In dry crushing it is essential, as soon as the rock enters the
rolls and becomes crushed, that it should bs spread out so that
the rolls can come into contact with the whole of the material, and
still further reduce it. This result has been secured to a great
extent by the Wegerif Roll (British patent, January nth, 1900,
No. 662), in which the rolls are so mounted, the one partially above
the other, that their axes cross each other, or lie in parallel
horizontal planes, but in different vertical planes, so that the planes
of rotation of the rolls are oblique to each other, and consequently
the particles passing between the grinding faces of the rolls are
subjected to a tearing, disruptive, or spreading action (in addition
to ordinary simple crushing or grinding), whereby the grinding
action is rendered more efficient. This obliquity of the roll-axes
involves a concave hyperboloidal configuration of the grinding or
crushing faces of the rolls, in order that a continuous line of contact
or bite may be obtained. As, however, the direction in which the
material enters between the rolls more or less approaches the
horizontal, but should be wholly in a downwardly inclined direction,
it is essential, in order to secure an even distribution of the material
along the line of bite, that this line of contact should itself be
as nearly horizontal as possible, so that the material fed into the
rolls will not gravitate towards one end of the line of bite. Were
the rolls made in the form of a complete hyperboloid, either one
or both of their axes would necessarily be placed out of the
horizontal, and the efficiency of the rolls would in any case be
seriously impaired.

One of the above-described machines, in a trial run, gave the
following results : it used 14 indicated horse power, crushed at the
rate of 150 tons in 24 hours, and reduced the material to such a
size as would be suitable for catching the coarse gold and easy
cyaniding. A sample of the resulting product was shown.



The Chairman, Mr. J. Stirling, Mr. J. A. Longden, and Mr. D.
A. Louis took part in the Discussion, and the author replied.

A vote of thanks was accorded to the author.



MINING AND TREATMENT OF COPPER ORE AT
THE WALLAROO AND MOONTA MINES, SOUTH
AUSTRALIA."

Paper by H. LIPSON HANCOCK.



Abstract.

INTRODUCTION. The Wallaroo and Moonta Copper Mines are
situated at the northern end of Yorkes Peninsula, about 6 and n
miles respectively from Port Wallaroo, where the smelting opera-
tions are conducted by the same proprietary. The mines have
been in operation for about forty years, and take in the chief
cupriferous resources of the district. At the Wallaroo mines
there are several ore-producing lodes, some of which are
nearly parallel. The general strike of the main ore body
is about North 75 degrees West. At the Moonta mines there
are five ore-producing lodes, bearing on an average North 30 degrees
East. The total value of the ore produced in connection with
these mines has amounted to over 10,000,000. The quantity
of veinstuff raised annually approximates 200,000 tons, giving
about 37,000 tons of dressed ore yielding annually 4800 tons of the
celebrated Wallaroo copper. The hands employed at the mines
number about 2000. The main ore-raising operations are at
depths varying from 1000 to 2000 feet, the deepest being about
2500 feet. The ore as raised consists chiefly of sulphides of copper,
intimately associated with a matrix very similar to the surrounding
rock formation. The bulk of this material needs comprehensive
treatment to afford satisfactory results, the copper contents varying
between 2 and 4 per cent. At the Moonta mines the country rock is
felsite-porphyry a plutonic igneous rock intensely hard, with a
specific gravity of about 2.67. At the Wallaroo mines the rock is
chiefly a metamorphic mica schist of possibly Cambrian age, and
though not so hard as that at Moonta. is tougher, containing consider-
able quantities of hornblendic material; specific gravity about 2.95.
The weight and flaky nature of the waste causes greater difficulties
in concentration. The Moonta mines ore is considerably richer
than the Wallaroo, but the amount of waste in proportion to the
ore much greater. The lodes are on the underlay ; those at Moonta
dip from 50 to 70 degrees. The underlay and intensely hard
nature of the rock making crosscutting expensive, the shafts are
sunk for the most part with the lode. Wheeled skips are utilised



232 TREATMENT OF COPPER ORE AT WALLAROO AND MOONTA.

instead of cages for raising the ore to the surface; many of these
have iai capacity of 45 cubic feet, holding about 28 or 30 cwt.
of vein stuff. Passes, shoots, and bins are used extensively for
speedy transport, and to facilitate expeditious hauling, which at the
main shafts is at the rate of from 30 to 35 skips per hour. At Wal-
laroo mines overhead stoping is found effective. Ordinary stulls were
formerly used where side pressure was not heavy. Where this
pressure occurred it became necessary to timber with legs and caps.
Where the ore body is sufficiently wide, the roof of the drives is
supported on timber-work pillars, filled with mullock, on either side
of the level. At Moonta both the overhead and underhand systems
of stoping are followed. Whenever sides have been sufficiently
rigid to be self-supporting, the underhand method has been pre-
ferred. The stulls have been of the simplest kind, namely, main
timbers set in " hitches," with suitable " headings."

GRADING PLANT. The landing brace at the shaft is of sufficient
height to admit of sizing by gravity. The ore is dumped on to
iron screens, which separate the various sizes of rocks; these are
discharged into bins, and thence into railway trucks below. Crude
material passing through f-inch holes is kept separate, and treated
on a specially designed jig. Vein stuff passing through holes
J inch and ij inch in diameter is treated separately on another
specially adapted jig. Material rougher than ij inch passes at
the end of the sizing trommel into a bin, and is dealt with on the
picking belt.

REDUCTION PLANT. Rougher material and all crude vein stuff
when poor, are fed into powerful breakers, which rapidly reduce it
to a gauge of about 2,\ inches. It is then elevated, after passing
through a revolving trommel to remove smaller sizes, to be dis-
charged on a travelling belt. The trommel lets through such sizes
as can be cheaply dressed by the various mechanical concentrators,
Boys pick out the different classes of ore from the travelling belt.
The solid ore is sent in the rough or crushed state to the smelters.
Copper ores associated with special minerals are dealt with sepa-
rately. But by far the greater portion of the material which comes
on to the picking belt is low class vein stuff. This is conveyed in
tipping trucks to large hoppers at the various concentrating plants ;
it is then passed, after the addition of water, between large crushing
rolls of the Cornish type, and the reduced pulp is received by a
revolving trommel which removes the coarser stuff, the remainder
going to the jig for concentration.

HANCOCK JIG. This machine was invented by the late general
manager, Mr. H. R. Hancock, some years ago, to treat the immense
quantities of low grade copper at these mines, where it has been
most extensively used ever since ; and it may be safely said that the



TREATMENT OF COPPER ORE AT WALLAROO AND MOONTA. 233

life of this property has been prolonged considerably by the adop-
tion of this invention in connection with the operations. The jigs
have been adopted with great success by several of the Broken Hill
silver mines in New South Wales, and also by mines in other parts
of the Australasian Commonwealth. During the time the invention
has been in use at these mines, about 4,000,000 tons of material
have been passed through the various machines in operation. The
capacity of the jig is great. One machine treats 150 tons of
pulverised material in 24 hours, the cost of treatment being there-
fore low. Shafts, smalls and toppings jigs (also the invention of
Mr. H. R. Hancock) are found exceedingly serviceable for various
classes of material at these mines.

SLIME DRESSING MACHINERY. From 12 to 15 per cent is re-
duced to a fine state in crushing, and carried past the main jigs to
settling pits. There are three classes of slime dressing machinery
in this department, viz. Round tables, belt and table vanners, and
inclined soft treatment tables governed by self-acting gear.

LEACHING TAILINGS. The coarser tailings from the dressing
appliances are placed in suitable positions, where after adequate
exposure to wind and weather, the sulphides corrode and by degrees
become decomposed. These heaps vary in height, but generally
range from 30 to 40 feet, and represent a total area of over 20
acres. The tops of the heaps are laid out in terraces. By a
system of sousing, resting, and draining, a liquid is obtained from
the base of the heap containing from 120 to 250 grains of copper to
the gallon. The process of leaching has been carried on for some
little time, but a plant is now nearing completion that will treat
the large heaps, aggregating over 1,000,000 tons, in a very much
more comprehensive manner from a large central station.



A vote of thanks was accorded to the author.



A NEW DIAGRAM OF THE WORK OF MINE
VENTILATION."

Paper by H. W. G. HALBAUM.



Abstract.

WHEN a gas expands in accordance with Boyle's law, the theoretic
diagram of work is a rectangular hyperbola. When a gas flows
through a given passage, an equally convenient diagram is supplied
by an ordinary parabola. The particular case here considered is
that of a given fan's capacity to ventilate mines of different resist-
ances.

Let the tangential speed of the given fan be u, and let the
total pressure thereby actually developed be H. Then, for the
same fan,

z/ 2

TT Constant = say, G.

Therefore, the tangential speeds are ordinates, and the total pres-
sures abscissae, to all points on the parabolic curve whose parameter
is G. Since G is an inverse measure of the fan's ability to transform
kinetic into potential pressure, G may be called the coefficient of
transformation.

Owing to fluid friction within the fan, and escape of energy in the
final velocity of the air, a portion of the total pressure is lost in
performing useless work. Let this loss of pressure be / when the
volume of the ventilating current is, V. Then, for the same fan,

V 2
= Constant = say, M.

Thus the volumes of air are ordinates, and the losses of pressure
abscissae, to all points on the parabolic curve whose parameter is M.
Since M measures the ability of the fan to pass volume against its
own resistances, M may be called the parameter of the fan. In this
parabola the product of ordinate and abscissa measures the
aerodynamic power lost in useless work.

The balance of the total pressure is h H - /. This is the
effective pressure ventilating the mine. Then, for any given mine,

V 2

- j = Constant = say, m.

So that the volumes of air are ordinates, and the effective pressures
abscissae, to all points on the parabolic curve whose parameter is m.
Since m measures the mine's susceptibility to the ventilative infhi-
ences exerted by the fan, m may be called the parameter of the



NEW DIAGRAM OF T&E WORK OF MINE VENTILATION. 235

mine. In this parabola the product of ordinate and abscissa
measures the useful work performed in the ventilation.

To find m for any mine, it is sufficient to accurately measure V
and h. To find M for a given fan, it is necessary to apply the
parabolic law which affirms that the parameter is equal to the
quotient obtained when the product of the sum and difference of
any two ordinates is divided by the difference of their abscissse.
The volumes passed by a given fan are, under all circumstances,
ordinates to the same M curve, and these are directly measurable.
The corresponding abscissae, however, being the invisible losses of
pressure, are not susceptible of direct measurement. But if two
factive mines of different resistance be constructed, and if the fan
be run at uniform speed on each mine in turn, the difference of the
measurable effective pressures becomes equal to the difference of
the invisible losses of pressure, and thus the difference of the
abscissae in the M-curve becomes mathematically measurable, and
the value of M is then deduced from the parabolic law just quoted.
Having found M, / may be deduced and added to h. The sum is
H, and since V is known,the coefficient of transformation, or G, the
parameter of the remaining curve, is finally ascertained.

The skeleton diagram for the given fan can now be constructed.
It consists of the two parabolic curves whose respective parameters
are G and M. These curves have a common origin, or vertex, and
a common axis, which it is convenient to lay horizontally. From
the common origin, a common scale of ordinates may be erected
perpendicular to the common axis. The w-curve may be dispensed
with as unnecessary, for its abscissa is equal to the difference of the
abscissae of the other curves, and the height of its ordinate is found
on the M-curve. Moreover, to be of any appreciable use, it would
need- to be drawn for a great number of mines, which would confuse
the diagram unnecessarily. In the construction of the diagram,
again, it is convenient to take the tangential speeds in feet per
second ; pressures and losses of pressure in feet of air-column ; and
volumes of air in thousands of cubic feet per minute.

To estimate the work of the fan on any mine m at any speed u,
proceed as follows: From the height u'on the scale of ordinates
draw a line parallel to the common axis until it touches the G-curve.
The length of this line = H. The ordinate to the M-curve erected
at the distance H from the origin is the volume the fan would pass
at the speed if it acted in the open air. The volume obtainable
at the same speed from the mine m is measured by that ordinate to
the M-curve whose abscissa is /. And

/=HX -HLg-

m + M
The effective pressure obtained under the same conditions is



236 NEW DIAGRAM OF THE WORK OF MINE VENTILATION.

h = H-l. And in the same case, the ratios of the useful, useless,
and total aerodynamic powers are the areas of the rectangles hV t
/V, and HV respectively. By multiplying each rectangle by the
weight of 1000 cubic feet of air, the ratios are converted into
actualities.

It has been proved by experiment that fans which are cased,
fitted with evasee chimney, and regulated by sliding shutter, conform
very closely to the law delineated in the parabolic diagram of work.



A vote ot thanks was accorded to the author.



"COKE-MAKING AT THE OLIVER COKE WORKS."
Paper by F. C. KEIGHLEY.



Abstract.

INTRODUCTION. The Oliver Coke Works are located at Oliver,
just outside the borough of Uniontown, Fayette County, Pennsyl-
vania, U.S.A. This location is in the very heart of the choicest
portion of the Connellsville basin of coking coal.

COKE-OVENS. The plants at this time consist of 708 beehive
coke-ovens, 12 feet 3 inches in diameter by 8 feet in height, inside
measurement, which are laid out, for convenience in charging, at
two different points a few hundred feet apart, and known as Oliver
No. i and No. 2. There are 328 ovens at No. i Oliver, and these
are laid out as follows : One row of bank-ovens and one set of
block-ovens, the ovens facing three yards or loading wharves and
two railroad sidings. There are 380 ovens at No. 2 Oliver, laid
out in three parallel sets of block-ovens, the ovens being arranged
to face six coke yards or loading wharves and four railroad sidings.

The Oliver coking plant was erected by Messrs. Oliver Brothers,
of Pittsburg, Pennsylvania, a little over ten years ago ; and, as they
were very extensively engaged in the iron and steel industry at that
time, the works were laid out specially for the manufacture of coke for
blast-furnace purposes. The coal for the coke ovens is taken from
large bins (holding from 400 to 600 tons of coal) located at the
hoisting shafts, and carried to the ovens by a train of three 200
bushels capacity steel larries and a locomotive, at each location.
All tracks, both on the coke-ovens for use of the larries and on
the railroad sidings, are of the standard gauge of 4 feet 8^ inches.

The charges of coal are run into the ovens directly from the
larries, and these charges run for regular work as follows :
Mondays and Tuesdays, 130 bushels of coal per oven; Wednesdays
and Thursdays, 140 bushels of coal per oven; and Fridays and
Saturdays, 175 bushels of coal per oven. In case of shortage of
orders or car-supply, these charges are differently scaled.

The yield of coke per oven varies, of course, with the charge.
The average drawing per oven for a period covering 16 months
was 4,602 tons* of coke. The output of coke for the year ending
December 3ist, 1900, was 466,618 tons. The capacity of the

* Throughout this paper the short ton of 2000 pounds is used.



238 COKE-MAKING AT THE OLIVER COKE WORKo.

works, if run full time every day for a year, is 500,000 tons of coke.
The coke-drawing is all done by hand, by means of scrapers and
forks, and the coke is loaded at the ovens by the drawer into wheel-
barrows, and wheeled directly into the railroad cars. The works
are equipped with 400 25-tons capacity standard-gauge railroad
coke-cars of the open-top drop-bottom type. The coal, of which
this coke is made, is taken from the celebrated Connellsville seam
of coking coal, and is used for coking purposes just as it comes from
the miner's pick. No crushing, washing, screening, or slate-picking
is done; in fact, the coal is so pure that nothing of this kind is
necessary.

ANALYSIS OF COKE.

Moisture. Volatile Matter. Fixed Carbon. Sulphur. Phosphorus. Ash.
0.30 0-645 89.405 0.678 0.013 9.229

ANALYSIS' OF COAL.

Moisture. Volatile Matter. Fixed Carbon.. Sulphur. Phosphorus. Ash.
0.600 2 9-5 63.10 0.94 0.014 5-^5

The yield of coke from coal is about 67 per cent. There is
about 3 per cent, of " breeze " in addition to the above, which at
present is treated as so much waste, and carted to the ash-dumps.
In common with other manufacturers of Connellsville coke, no
attempt is made to utilise the waste-gases and bye-products from
the coke-ovens. The cost of coke-making under the present wage
scale is about 6s. 3d. ($1.50) per ton. It is the intention to increase
the number of coke-ovens to noo, making it the largest coking
plant in the world.



The Chairman took part in the Discussion, and the author replied
by correspondence.

A vote of thanks was accorded to the author.



MINERAL RESOURCES OF THE PROVINCE OF

QUEBEC, CANADA.''

*
Paper by J. OBALSKI.



Abstract.

THE province of Quebec covers an area of 347,000 square miles,
being twice as large as the British Islands, and extends for about
1700 miles from east to west and 600 miles from north to south,
with a population of less than 2,000,000. It is practically crossed
from east to west by the water-courses formed by the St Lawrence
and Ottawa rivers, dividing the country into two well-defined dis-
tricts, which are drained by numerous and important rivers. The
tributaries are only navigable for small lengths of their courses,
but they are of great use for the drifting down of timber and afford
important waterfalls, which are beginning to be used for motive
power.

The country north of the St. Lawrence and Ottawa rivers is
formed of metamorphic and eruptive rocks, known under the general
name of Laurentian. The southern shore comprises several series
from the Cambrian to the Devonian, with a few eruptive mountains,
forming a continuation of the Alleghany chain. The immediate
valley of the St Lawrence and Ottawa rivers is formed by Lower
Silurian limestone and shales ; while towards the south the older
Cambrian and pre-Cambrian rocks have been brought to the surface
by a great fault running north-eastward. Devonian rock appears
only at the surface in Gaspesia. forming the eastern part of the
province, and Anticosti island.

Only a relatively small part of that large territory has been pro-
spected ; but nevertheless, from the geological study which has been
made, we know what kind of minerals may be expected, although
new discoveries may happen.

In the Laurentian formation the following minerals occur : Phos-
phates of lime, mica (white and amber), plumbago, magnetite, titanic
iron, felspar, etc.. In the other series, occupying the south, are
found copper ores, magnetite, haematite, alluvial gold, asbestos,
chromite, soapstone, etc.

In the central district there are important indications of com-
bustible gas and oil, and in the extreme west oil has been found.
On both shores of the St. Lawrence the rock is generally covered



240 MINERAL RESOURCES OF QUEBEC.

by alluvial drifts. Peat, bog iron ore, clay, and marble are found
in abundance ; while, where the rock outcrops, there is a large supply
of material which is used for building and ornamental purposes and
for lime-making.

Amongst this great variety of minerals must be deplored the
absence of coal, which has to be obtained from Nova Scotia and
Pennsylvania; but in many mining districts wood, so plentiful in
this province, is used as fuel, and several trials are being made
just now for the preparation and industrial use of peat.

IRON. Although the iron industry in this district is the oldest
established in North America there are only two small furnaces
using bog ore, and they produce the highest quality of charcoal
pig iron, 6700 tons having been made last year. Several attempts
were made 30 or 40 years ago to smelt the magnetic ore found in
the vicinity of Ottawa, the magnetic sand of Moisic, and the titanic
ore of St. Urbain, but without financial success. Several mines
of magnetite and haematite are scattered through the province, but
the most important are the magnetic sand-deposits of Moisic, St.
John, and Natashquan, on the northern shore of the Gulf. It is
estimated that many million tons of ore, containing 70 per cent,
of iron, practically free from phosphorus or sulphur, could be ob-
tained by a proper concentration getting rid of the titanium, which
is found as titanic iron with the sand : several machines have been
introduced for this purpose.

COPPER. In the vicinity of Sherbrooke large bodies of copper
ore, yielding an average of 4 per cent, of copper, 35 per cent, of
sulphur, and a little silver, are regularly worked with an average
output of 30,000 to 40,000 tons a year. Part is used on the spot
for the manufacture of sulphuric acid, the remainder and the burnt
ore being shipped to the United States. Several other deposits,
some of them of high-grade ores, were extensively worked about
25 years ago, and abandoned later for several reasons, but they may
be again reopened.

GOLD. In the Beauce district alluvial gold has been worked in
an intermittent manner; the total production has been estimated
at ,400,000 (2,000,000 dollars). Actually these alluvials are only
worked on a small scale.

ASBESTOS. The asbestos industry is one of the most important
having produced last year ^150,000 (750,000 dollars) of raw
material. The mines of asbestos are located in a serpentine belt,
which is extensively worked at Thetford, Black Lake, and Danville.
Asbestos is shipped to the United States and Europe.

CHROMITE. Chromite is found near Black Lake. The ore is
variable in quality, but contains less than 50 per cent, of sesqui-
oxide of chromium ; it is concentrated to reach that grade. About



MINERAL RESOURCES OF QUEBEC. 41

2500 tons are obtained yearly, and sent mostly to the United States.
MICA. In the Ottawa county amber mica is found and worked
at many places, the value at the mines of the output being about



Online LibraryInternational Engineering Congress (1901 : GlasgowReport of the proceedings and abstracts of the papers read → online text (page 21 of 37)