Hydraulic Mine.]
There are large deposits in the arid portions of the globe where water
for working is not obtainable. To meet such conditions, numerous
inventions continue to be placed upon the market. These devices are all
planned in such a way as to use very little or no water. If water is
required at all, the machines are expected to use it repeatedly. The
machines are built to effect the segregation of the precious contents
gravitationally, electrostatically, pneumatically, and by amalgamation
with mercury. It is too early to say how successful such devices will
prove in commercial operations. Because some of them have not "made
good" does not mean that genius will not yet cope with the situation;
and we look into the future to see large operations efficiently and
economically conducted by dry placer machinery. There are now no
authentic figures obtainable upon this question of dry placering costs.
VIII
OPEN MINING.
Some mention has been already made of open mining. The greatest
development of this sort of mining has come about since the application
of the modern steam shovel to the excavation of ore. This practice was
an American innovation and it is being adopted throughout the world
wherever natural conditions will warrant.
Within the past few years, immense bodies of iron ore have been
discovered in northern Minnesota and the adoption of these immense,
mechanically operated shovels has worked such economies in the mining of
this kind of ore that entirely new cost figures have been established
and tonnages are being produced which, a few years ago, would have
seemed unbelievable. There are about a dozen mines of this "open pit"
type that have each produced over a million tons of ore per year in a
season that must cease with the close of navigation on the Great Lakes.
One mine has shipped over three million tons a season.
At the Utah Copper Company's mine in Bingham Canyon, Utah, a great
deposit of low grade, copper-bearing eruptive rock is being handled upon
a steep mountain-side by this same scheme. This ore averages a little
less than two per cent. in copper, but so economical is the handling of
it in such vast amounts that a neat profit is made above all mining,
transportation and milling charges. When the red metal sells at thirteen
cents per pound, the gross value of this ore is about $5.20 per ton.
This mine has maintained an output of ten thousand tons or more per day
over long periods.
A famous gold mine in Queensland, Australia--the Mount Morgan--is also
being worked by steam shovel methods. The deposit is here in the form of
a small mountain and the operations are gradually razing this landmark
to the level of the surrounding plains.
The mining of low-grade _gold_ ores by open-pit methods has taken hold
in America, and an example of the practice may be found at the Wasp No.
2 mine in the Black Hills. According to published accounts of the
operations of this company, all of the costs of mining and treating the
ore amount to only $1.02 per ton. The ore body is a bed of quartzite
lying nearly flat, and averaging in the neighborhood of only $2.50 per
ton in gold, the only mineral of value. The recovery of this metal is at
the rate of between 75 and 80 per cent. efficiency, or about $2 from
each ton. The net profit is therefore close to one dollar per ton. This
very modern scheme of mining has been made possible through the recent
advances made in the cyanidation of ore, and it is going to pave the way
for many more such mining plants.
[Illustration: STEAM SHOVELS AND CHURN DRILLS, COPPER FLAT, ELY,
NEVADA.]
The Nevada Consolidated Copper Company has conducted vast mining
operations "in the open" at Ely, Nevada, by the use of 95-ton shovels
having a capacity of two and one-half cubic yards per dip. One shovel
has handled as high as 2,800 cubic yards (the equivalent of about 5,500
tons) in nine hours; but this must be recognized as an exceptional
run, and cannot be taken as an average. The ore has a thickness of about
200 feet and covers many acres. As in the majority of such properties,
there is here a large amount of "overburden" to be removed and disposed
of before the ore can be excavated. This process of uncovering the ore
body by the removal of the overburden is called "stripping." The cost
per ton of ore mined is said to average 55 cents.
In an open mine there must be maintained a system of continually
changing tracks placed upon grades (sometimes rather steep) and with
sharp curves. With multiple switches, numbers of small locomotives are
kept busy pulling and pushing up and down the tracks with their strings
of loaded cars and replacing the "loads" with "empties." When such
operations are upon a mountain-side, a very beautiful panoramic view may
be had from the opposite side of the gulch.
Generally, the ore material is disintegrated to some extent. In some
cases, it will actually crumble down before the advance of a steam
shovel. In other mines, it is necessary to drill large holes which are
loaded and blasted.
It is becoming more and more important for the active mining man to post
himself upon the methods and economies of this latter-day mining
practice. The development of this open or surface mining has introduced
entirely new economic ideas. With no costs for timbering of mine
passages, for ventilation, or for hoisting, and with a very material
decrease in manual labor per ton mined, immense masses of rocks are now
really ore, although a few years ago they were nothing but lean, country
rock.
In consequence of the success attained by the pioneers in this kind of
mining, there has been created a demand for properties possessing large
deposits of low grade ore that is workable on this intensive scale.
Copper properties have been holding a prominent place recently and
stockbrokers carry regular lists of "Porphyries," this nickname having
been coined to cover the companies operating in the low grade porphyry
ores of the Western United States. Not all of these porphyry companies
will use surface mining methods. Some companies in the Globe District of
Arizona have started extensive underground schemes for mining large
tonnages very cheaply by "caving" methods.
IX
CONSIDERATIONS PRECEDING THE OPENING OF MINES.
The word "exploitation" is used by many mining men and engineers to
signify a plan of so opening up ore deposits as to render the contents
removable. The same persons use the word "mining" to mean the operations
involved in the actual extraction of the ore exploited. It is sometimes
difficult to draw any line between the meanings of these two words for,
as handled by different men, with varying shades of intention, they are
sometimes synonymous. Thus, if exploiting an underground mine, which
carries ore right from the surface, means developing the mine in such a
way as to provide for a large, steady production, it is difficult to see
why the ore taken out in this process cannot be said to be "mined."
By "dead work" is usually meant that work of opening up a mine which
will put or keep it in a producing condition but which does not supply
any remuneration in the shape of ore (or coal). Again, as used by some
men, there is little distinction between this work and exploitation.
There may, however, be lines reasonably drawn between these three terms,
and therefore the following definitions are proposed:
_Dead work_ is such work as is necessary to develop an ore body, but it
does not produce any ore. It may be prosecuted for drainage or
ventilation purposes or for creating passage-ways for men and products.
_Exploitation_ is also work performed in opening up or developing a
property, but it does not contemplate the value of the extracted
materials which may, or may not, be of any commercial importance.
Indeed, much ore might be extracted during work which was carried on
merely to define extents or boundaries of ore bodies. In this last
supposition, the original sense of exploration is brought out and this
should serve to fix the definition clearly in mind.
_Mining_ may be restricted to mean the methods and work involved in the
profitable production of the mine's ore (or coal). The term would not be
used to cover operations of shaft-sinking, tunneling, and the like,
unless such work be in the valuable materials. Mining may be said to
begin whenever there is produced an output upon which there is some
profit. Exploitation may be in valuable ground. If so, we may say that
mining is in progress during the exploitation. The driving of levels or
drifts in an ore body--or of entries in a bed of coal--produces the
valuable products of the mine, and we may, therefore, consider that
mining is taking place.
The driving of a crosscut through barren rock to reach an ore body is
dead work; but the driving of a drift or level in a vein is either
exploitation or mining. Dead work produces _no_ ore. Exploitation may,
or may not, produce ore. Mining must produce ore.
Throughout all of the above and the following discussion of this
chapter, the reader should bear in mind the point that the word "coal"
may be substituted for the word "ore" without altering the substance of
the definitions or the conclusions.
Before a mine is opened up, the economist-manager will consider many
items. In the first place, care must be exercised in the _examination of
the title_ to the property. A mineral property may have passed through
the most complicated kind of transfers of fractional interests in the
title, just as is true with ordinary real estate. The abstract must be
traced back clear to the issuance of patent from the Government, and
then on back to the original location. With an undeveloped property (a
prospect), this precaution is essential to estop any possible
pretensions to ownership, by outside parties, in case the ground
subsequently turns out to be exceptionally valuable. It has often been
the case that no obstructions from any adverse claimants have been met
until owners have, in good faith and at great expense, developed
splendid mines. Then suits for possession or partial ownership have been
instituted, sometimes with marked success for the plaintiffs. There are
persons who make it a special line of business to examine titles to
mining property, and it is economy for the average manager to employ
such experienced men to attend to these matters.
_Topographical considerations_ will hold a place in the study preceding
the opening of a new mine. The nature of the surface of the property and
the surrounding country will largely influence in the selection of the
proper site for the mine's mouth. Neglect upon this point has been a
common cause of failure in mining operations.
A mine opening must be away from all dangers of snow-slides,
rock-slides, cloud-bursts and deluges from overflowing streams or
breaking dams. It may make a difference in the mine's ventilation as to
which direction the prevailing winds blow and therefore upon which side
of a hill the mouth be opened.
_Transportation_ facilities must be given due thought. If means are not
already at hand, one must inquire into the feasibility of constructing
some form of carrier; and here, again, will enter the question of the
surface's contour. If a railroad is out of question, possibly an aerial
tramway may be constructed. These modern conveyances stop at no
obstacles of surface configuration and are dependent only upon the
necessity of having the point of delivery lower in altitude than the
point of loading at the mine. With some of the modern improvements in
these installations, mine products are being transported up-hill as well
as down-hill through the application of power. In mining regions, it is
generally the case that the mines, themselves, are above the settlements
in which are the railroads or treatment plants, so that the mine
products will transport readily by the natural force of gravity.
_Climate_ holds an important place in the economics of mining. The
working of very rich pieces of ground may prove a losing proposition in
some portions of the world where the climatic conditions are such as to
render operations possible during only a very small portion of the year.
Extremes of heat or cold, malaria or other pestilential obstacles, long
rainy seasons with floods, and the hostility of native humans, beasts
or insects have accounted for the abandonment of seemingly attractive
mining projects.
The question of _labor_ must be given due thought. It is true that the
best miners on earth are Americans. We do not deny that many of our
miners are of foreign birth, but the fact remains that they perform
better and more intelligent service than do their fellow countrymen who
have not been adopted into our country. Our men are in demand in the
mining development of foreign countries. An American mine manager will
always experience dissatisfaction while endeavoring to get, from natives
in foreign parts, the same efficiency that he is accustomed to receive
from the miners "at home." He may be paying a good deal less per capita
for such labor, but he finds he is actually paying more per ton of
output.
Even within a single country, there are notable differences in the worth
of labor. The natives of some of the Mexican states are far preferable
to those of other states. Within the United States, there may be
discerned material differences between the efficiencies of the citizens
of various sections, when it comes to mining. One cannot procure as
competent miners in some of the agricultural states as in the typical
mining states. This is but to be expected. For instance, there are
deposits of lead ore in the "moonshine" regions of Kentucky which have
never been successfully worked, and the real cause of failure, in the
writer's belief, lies in the inability of superintendents to obtain real
miners either in that region or from the outside. The residents will
never become miners; outsiders will not enter for work under existing
sociological conditions.
The question of _unionism_ is sometimes held by managers as a deciding
one when debating the opening of a mine. While there are those who will
broadly denounce such organizations, there may be found other and just
as successful mine operators who declare that the effects of union
control over their miners are beneficial to their companies' interests.
Probably the greatest objection to unionism raised by operators is that
they resent the dictation that accompanies the inauguration of union
rules in their mines. The owners and managers prefer to run their own
business to suit themselves. Some managers are so imbued with this
conviction of their own rights that they will refuse to open up mines
or, if they are operating, they will close down their mines before they
will submit to the demands made upon them by the union officials.
On the other hand, there are mine managers who prefer the presence of
some central, labor-controlling body; for they believe that the men who
belong to such a large federation or organization will, and do, have
less complaint to make and therefore work more freely than is the case
with the independent laborers. The argument is that these union men are
satisfied because they feel that their interests are being looked after
with a sort of attention that they, individually, could not give.
This is not a place to discuss the crimes that have been laid at the
doors of both the labor organizations and the mine owners' associations.
It is safe to assume that wrong has probably been done by both sides.
But it is furthermore right to believe that most of the crimes were not
authorized, nor recognized, by the officers or the majority of members
of either side. Individual members must not be taken as averages of the
membership in any kind of civil, social or political organization.
It seems entirely wrong that _politics_ should enter into the
considerations of a mine manager whose operations are apparently so
apart from affairs of state; but the fact remains that there are places
where mining operations cannot be carried on without the good will of
certain officials of the state or national governments. It is not
advisable to enter into any compromising terms to gain privileges for
carrying on any legitimate business for there are other, better ways,
generally, of attaining the justice that is deserved.
One must not omit to investigate the _sources of supply_ for all the
needs of a mine and its camp. There are many kinds of materials needed
to keep a mine going. Fuel, machinery, timber, water, food for men and
beasts, lumber, and all household furnishings and necessities must come
from some markets or natural sources. It behooves the cautious manager
to see that all these things may be had in ample amount and at figures
which will not prove annihilating to his business.
In Utah, there are mines which have all their timbers framed in and
shipped from the forests of Oregon, the sawing and framing being done
before shipment to save on freight. The fir of Oregon is shipped to
distant Australia for mining purposes. The arid camps of Nevada get
their supplies of timber from the sister state, California. The Michigan
mines are fortunate in being in a lumber region. Colorado's metal mines
are more favored in the matter of timbers than are the coal mines of the
same state. Most of the coal mines are upon the barren plains, while the
metal mines are chiefly in the wooded mountains.
[Illustration: MILL OF THE PITTSBURG-SILVER PEAK GOLD MINING CO., BLAIR,
NEVADA.]
Water may be too scarce for the needs of a mine or its community. There
may not be sufficient to supply boilers or a mill, or for the domestic
purposes of the workers. On the other hand, water may be so abundant
in the mine workings as to prove a deterrent factor in profitable
operation. With shaft mines, having deep workings and low grades of ore,
if water must be delivered mechanically, the costs for such drainage are
frequently prohibitive of mining. Some mines, in arid regions, have been
fortunate in striking such flows of underground water that it has been
possible to operate mills right at the mines. In this way, the cost of
water hoisting has been more than compensated in the milling benefits
which, in turn, have decreased freights and treatment charges.
_Machinery_ is usually purchased at centres of mining supplies and
manufactures. San Francisco, Los Angeles, Salt Lake City, Denver and
Chicago are the principal _rendezvous_ in the West for mining men in
need of machinery. Mexico City is, similarly, the outfitting point for
the mines of southern Mexico. The United States holds the supremacy of
the world in the matter of equipping mines and mills, large orders of
American-made mining machinery being shipped to even the antipodes.
The nearer a property is to a depot of supplies, the less is bound to be
the cost of getting goods onto the ground. It is this last item--the
delivery of goods--that must be recognized as a very pertinent, and
sometimes a critical, factor upon the cost side of mining accounts.
Mines that are remote or in rugged countries are frequently dependent
upon animal transportation. In some cases, machinery going to the mines
must be so built that it may be taken apart into small portions suitable
for loading upon the backs of horses or burros, or even, in the Andes,
upon the frail llamas.
Operations, if planned to be conducted for a long term of years and
therefore warranting the installation of large and expensive plants,
should be based upon the holding of extensive ore-bearing ground. Here
enters the notion of the _shape and size of a mining property_.
With some kinds of mining ground, the best form for the holdings would
probably be a compact, approximately equilateral tract, covering a
reasonably large acreage. This would be the case with ores that occur in
sedimentary beds, for instance, where it is advisable to have the mining
plant centrally located so as to work expeditiously the entire area.
This would apply to a region like the Cripple Creek District, which
contains innumerable veins running in all directions but displaying no
outcrops.
In other instances, the most desirable shape might be long, narrow
strips so laid off as to contain the strikes of persistent lodes or
veins, as those of the wonderful Comstock Lode region. It is not acreage
that counts here so much as lineal extent.
In the Transvaal, land is held in rectangular blocks. The first owners
of the ground took it up for agricultural purposes. This same statement
is also true of the mining properties in the Joplin District of Missouri
and Kansas.
In the case of the South African properties, every company has definite
boundaries to which operations may be planned. Hence it is possible for
the management to so plant any mine as to operate it at a given rate
for a predetermined life of the enterprise. The work is planned to
maintain a certain output that will exhaust the ore bodies in just so
many years, and all the equipment may thus be purchased with the
forecast that it will serve its purpose and perform its economic share
within the prescribed time.
This notion will be more readily understood when we consider the various
types of ore bodies. With properties wherein there is no possible way of
predicting the number, size, and worth of discoverable ore bodies, the
life is wholly problematical and it is therefore difficult for a manager
to decide how much he should expend in the initial equipment.
X
MINE OPENINGS.
In every new mining project, there is much to be considered concerning
the expediency of opening up through shafts, inclines or adits. More
attention has lately been given to this subject than formerly. There are
very good reasons for the selection of any one of these kinds of mine
openings.
The words shaft, incline, and tunnel have been handled with careless
meanings by mining men. It is time that some definitions be accepted so
that everybody will use these terms with the same meanings.
A shaft has loosely been any steep opening sunk through the ground. An
incline--sometimes spoken of also as an incline shaft--has been taken to
mean an opening resembling a shaft, but not very steep and not
approaching verticality. Right here, there has been too much latitude
of speech and it has entailed the necessity of many awkward
explanations.
By a tunnel has been intended any (approximately) horizontal passageway
driven from the natural surface. Objection to this use of the word rests
in the strict definition of a tunnel, which states that it must have
both ends open to the natural surface of the earth, as for example, an
irrigation or a railroad tunnel. A level passageway which has but one
end open to daylight is not properly spoken of as a tunnel. In mining
practice, practically every horizontal opening of this nature is open at
only one end, and it is an adit rather than a tunnel. If the precaution
of speaking of it as a "mining tunnel" is observed, very well, for this
may be taken to be an expression synonymous with adit. The latter term
is, however, shorter and more correct.
For the sake of a uniform usage, the following definitions are proposed.
Their use will conform with the usages of those well-informed persons
who adhere to correct speech.
A _shaft_ is a truly vertical mine passage which may, or may not, be
sunk in or along an ore or a coal body.
An _incline_ is any mine passage which occupies a sloping position and
which may, or may not, maintain a uniform inclination throughout its
length. It may be sunk along, or in, a pitching vein or seam and it may
thus conform to the irregularities of the dip of such body. It is
neither horizontal nor vertical. Such an inclined passage following a
seam of coal is known as a _slope_.
It sometimes happens, especially in coal mining, that a sloping
passageway is driven through barren rock either to get at known bodies
by the shortest means or to establish uniform grades for tracks. In a
strict sense, these are not inclines or slopes, for they do not even
approximately follow, nor parallel, bodies of value. The miner's term
for such an opening is _rock slope_.