MAGNETIC ORE MILLING WORK
DURING the Hudson-Fulton celebration of October, 1909, Burgomaster Van
Leeuwen, of Amsterdam, member of the delegation sent officially from
Holland to escort the Half Moon and participate in the functions of the
anniversary, paid a visit to the Edison laboratory at Orange to see
the inventor, who may be regarded as pre-eminent among those of Dutch
descent in this country. Found, as usual, hard at work--this time on his
cement house, of which he showed the iron molds--Edison took occasion to
remark that if he had achieved anything worth while, it was due to the
obstinacy and pertinacity he had inherited from his forefathers.
To which it may be added that not less equally have the nature
of inheritance and the quality of atavism been exhibited in his
extraordinary predilection for the miller's art. While those Batavian
ancestors on the low shores of the Zuyder Zee devoted their energies to
grinding grain, he has been not less assiduous than they in reducing the
rocks of the earth itself to flour.
Although this phase of Mr. Edison's diverse activities is not as
generally known to the world as many others of a more popular character,
the milling of low-grade auriferous ores and the magnetic separation of
iron ores have been subjects of engrossing interest and study to him for
many years. Indeed, his comparatively unknown enterprise of separating
magnetically and putting into commercial form low-grade iron ore,
as carried on at Edison, New Jersey, proved to be the most colossal
experiment that he has ever made.
If a person qualified to judge were asked to answer categorically as to
whether or not that enterprise was a failure, he could truthfully answer
both yes and no. Yes, in that circumstances over which Mr. Edison had no
control compelled the shutting down of the plant at the very moment of
success; and no, in that the mechanically successful and commercially
practical results obtained, after the exercise of stupendous efforts
and the expenditure of a fortune, are so conclusive that they must
inevitably be the reliance of many future iron-masters. In other words,
Mr. Edison was at least a quarter of a century ahead of the times in the
work now to be considered.
Before proceeding to a specific description of this remarkable
enterprise, however, let us glance at an early experiment in separating
magnetic iron sands on the Atlantic sea-shore: "Some years ago I heard
one day that down at Quogue, Long Island, there were immense deposits
of black magnetic sand. This would be very valuable if the iron could
be separated from the sand. So I went down to Quogue with one of my
assistants and saw there for miles large beds of black sand on the beach
in layers from one to six inches thick--hundreds of thousands of tons.
My first thought was that it would be a very easy matter to concentrate
this, and I found I could sell the stuff at a good price. I put up a
small plant, but just as I got it started a tremendous storm came
up, and every bit of that black sand went out to sea. During the
twenty-eight years that have intervened it has never come back." This
incident was really the prelude to the development set forth in this
chapter.
In the early eighties Edison became familiar with the fact that the
Eastern steel trade was suffering a disastrous change, and that business
was slowly drifting westward, chiefly by reason of the discovery and
opening up of enormous deposits of high-grade iron ore in the upper
peninsula of Michigan. This ore could be excavated very cheaply by
means of improved mining facilities, and transported at low cost to lake
ports. Hence the iron and steel mills east of the Alleghanies--compelled
to rely on limited local deposits of Bessemer ore, and upon foreign
ores which were constantly rising in value--began to sustain a serious
competition with Western mills, even in Eastern markets.
Long before this situation arose, it had been recognized by Eastern
iron-masters that sooner or later the deposits of high-grade ore would
be exhausted, and, in consequence, there would ensue a compelling
necessity to fall back on the low-grade magnetic ores. For many years it
had been a much-discussed question how to make these ores available
for transportation to distant furnaces. To pay railroad charges on
ores carrying perhaps 80 to 90 per cent. of useless material would
be prohibitive. Hence the elimination of the worthless "gangue" by
concentration of the iron particles associated with it, seemed to be the
only solution of the problem.
Many attempts had been made in by-gone days to concentrate the iron in
such ores by water processes, but with only a partial degree of success.
The impossibility of obtaining a uniform concentrate was a most serious
objection, had there not indeed been other difficulties which rendered
this method commercially impracticable. It is quite natural, therefore,
that the idea of magnetic separation should have occurred to many
inventors. Thus we find numerous instances throughout the last century
of experiments along this line; and particularly in the last forty or
fifty years, during which various attempts have been made by others than
Edison to perfect magnetic separation and bring it up to something like
commercial practice. At the time he took up the matter, however, no
one seems to have realized the full meaning of the tremendous problems
involved.
From 1880 to 1885, while still very busy in the development of his
electric-light system, Edison found opportunity to plan crushing and
separating machinery. His first patent on the subject was applied for
and issued early in 1880. He decided, after mature deliberation, that
the magnetic separation of low-grade ores on a colossal scale at a low
cost was the only practical way of supplying the furnace-man with a high
quality of iron ore. It was his opinion that it was cheaper to quarry
and concentrate lean ore in a big way than to attempt to mine, under
adverse circumstances, limited bodies of high-grade ore. He appreciated
fully the serious nature of the gigantic questions involved; and his
plans were laid with a view to exercising the utmost economy in the
design and operation of the plant in which he contemplated the automatic
handling of many thousands of tons of material daily. It may be stated
as broadly true that Edison engineered to handle immense masses of stuff
automatically, while his predecessors aimed chiefly at close separation.
Reduced to its barest, crudest terms, the proposition of magnetic
separation is simplicity itself. A piece of the ore (magnetite) may be
reduced to powder and the ore particles separated therefrom by the help
of a simple hand magnet. To elucidate the basic principle of Edison's
method, let the crushed ore fall in a thin stream past such a magnet.
The magnetic particles are attracted out of the straight line of the
falling stream, and being heavy, gravitate inwardly and fall to one
side of a partition placed below. The non-magnetic gangue descends in
a straight line to the other side of the partition. Thus a complete
separation is effected.
Simple though the principle appears, it was in its application to vast
masses of material and in the solving of great engineering problems
connected therewith that Edison's originality made itself manifest in
the concentrating works that he established in New Jersey, early in the
nineties. Not only did he develop thoroughly the refining of the crushed
ore, so that after it had passed the four hundred and eighty magnets
in the mill, the concentrates came out finally containing 91 to 93 per
cent. of iron oxide, but he also devised collateral machinery, methods
and processes all fundamental in their nature. These are too numerous to
specify in detail, as they extended throughout the various ramifications
of the plant, but the principal ones are worthy of mention, such as:
The giant rolls (for crushing).
Intermediate rolls.
Three-high rolls.
Giant cranes (215 feet long span).
Vertical dryer.
Belt conveyors.
Air separation.
Mechanical separation of phosphorus.
Briquetting.
That Mr. Edison's work was appreciated at the time is made evident
by the following extract from an article describing the Edison
plant, published in The Iron Age of October 28, 1897; in which, after
mentioning his struggle with adverse conditions, it says: "There is very
little that is showy, from the popular point of view, in the gigantic
work which Mr. Edison has done during these years, but to those who are
capable of grasping the difficulties encountered, Mr. Edison appears
in the new light of a brilliant constructing engineer grappling with
technical and commercial problems of the highest order. His genius as
an inventor is revealed in many details of the great concentrating
plant.... But to our mind, originality of the highest type as a
constructor and designer appears in the bold way in which he sweeps
aside accepted practice in this particular field and attains results not
hitherto approached. He pursues methods in ore-dressing at which
those who are trained in the usual practice may well stand aghast.
But considering the special features of the problems to be solved, his
methods will be accepted as those economically wise and expedient."
A cursory glance at these problems will reveal their import. Mountains
must be reduced to dust; all this dust must be handled in detail, so
to speak, and from it must be separated the fine particles of iron
constituting only one-fourth or one-fifth of its mass; and then this
iron-ore dust must be put into such shape that it could be
commercially shipped and used. One of the most interesting and striking
investigations made by Edison in this connection is worthy of note,
and may be related in his own words: "I felt certain that there must be
large bodies of magnetite in the East, which if crushed and concentrated
would satisfy the wants of the Eastern furnaces for steel-making.
Having determined to investigate the mountain regions of New Jersey, I
constructed a very sensitive magnetic needle, which would dip toward the
earth if brought over any considerable body of magnetic iron ore. One
of my laboratory assistants went out with me and we visited many of the
mines of New Jersey, but did not find deposits of any magnitude.
One day, however, as we drove over a mountain range, not known as
iron-bearing land, I was astonished to find that the needle was strongly
attracted and remained so; thus indicating that the whole mountain was
underlaid with vast bodies of magnetic ore.
"I knew it was a commercial problem to produce high-grade Bessemer ore
from these deposits, and took steps to acquire a large amount of the
property. I also planned a great magnetic survey of the East, and I
believe it remains the most comprehensive of its kind yet performed. I
had a number of men survey a strip reaching from Lower Canada to North
Carolina. The only instrument we used was the special magnetic needle.
We started in Lower Canada and travelled across the line of march
twenty-five miles; then advanced south one thousand feet; then back
across the line of march again twenty-five miles; then south another
thousand feet, across again, and so on. Thus we advanced all the way to
North Carolina, varying our cross-country march from two to twenty-five
miles, according to geological formation. Our magnetic needle indicated
the presence and richness of the invisible deposits of magnetic ore.
We kept minute records of these indications, and when the survey was
finished we had exact information of the deposits in every part of
each State we had passed through. We also knew the width, length, and
approximate depth of every one of these deposits, which were enormous.
"The amount of ore disclosed by this survey was simply fabulous. How
much so may be judged from the fact that in the three thousand acres
immediately surrounding the mills that I afterward established at
Edison there were over 200,000,000 tons of low-grade ore. I also secured
sixteen thousand acres in which the deposit was proportionately as
large. These few acres alone contained sufficient ore to supply the
whole United States iron trade, including exports, for seventy years."
Given a mountain of rock containing only one-fifth to one-fourth
magnetic iron, the broad problem confronting Edison resolved itself into
three distinct parts--first, to tear down the mountain bodily and grind
it to powder; second, to extract from this powder the particles of iron
mingled in its mass; and, third, to accomplish these results at a cost
sufficiently low to give the product a commercial value.
Edison realized from the start that the true solution of this problem
lay in the continuous treatment of the material, with the maximum
employment of natural forces and the minimum of manual labor and
generated power. Hence, all his conceptions followed this general
principle so faithfully and completely that we find in the plant
embodying his ideas the forces of momentum and gravity steadily in
harness and keeping the traces taut; while there was no touch of the
human hand upon the material from the beginning of the treatment to its
finish--the staff being employed mainly to keep watch on the correct
working of the various processes.
It is hardly necessary to devote space to the beginnings of the
enterprise, although they are full of interest. They served, however, to
convince Edison that if he ever expected to carry out his scheme on the
extensive scale planned, he could not depend upon the market to supply
suitable machinery for important operations, but would be obliged to
devise and build it himself. Thus, outside the steam-shovel and such
staple items as engines, boilers, dynamos, and motors, all of the
diverse and complex machinery of the entire concentrating plant, as
subsequently completed, was devised by him especially for the purpose.
The necessity for this was due to the many radical variations made from
accepted methods.
No such departure was as radical as that of the method of crushing the
ore. Existing machinery for this purpose had been designed on the
basis of mining methods then in vogue, by which the rock was thoroughly
shattered by means of high explosives and reduced to pieces of one
hundred pounds or less. These pieces were then crushed by power directly
applied. If a concentrating mill, planned to treat five or six thousand
tons per day, were to be operated on this basis the investment in
crushers and the supply of power would be enormous, to say nothing of
the risk of frequent breakdowns by reason of multiplicity of machinery
and parts. From a consideration of these facts, and with his usual
tendency to upset traditional observances, Edison conceived the bold
idea of constructing gigantic rolls which, by the force of momentum,
would be capable of crushing individual rocks of vastly greater size
than ever before attempted. He reasoned that the advantages thus
obtained would be fourfold: a minimum of machinery and parts; greater
compactness; a saving of power; and greater economy in mining. As this
last-named operation precedes the crushing, let us first consider it as
it was projected and carried on by him.
Perhaps quarrying would be a better term than mining in this case, as
Edison's plan was to approach the rock and tear it down bodily. The
faith that "moves mountains" had a new opportunity. In work of this
nature it had been customary, as above stated, to depend upon a high
explosive, such as dynamite, to shatter and break the ore to lumps
of one hundred pounds or less. This, however, he deemed to be a most
uneconomical process, for energy stored as heat units in dynamite at
$260 per ton was much more expensive than that of calories in a ton of
coal at $3 per ton. Hence, he believed that only the minimum of work
should be done with the costly explosive; and, therefore, planned to use
dynamite merely to dislodge great masses of rock, and depended upon the
steam-shovel, operated by coal under the boiler, to displace, handle,
and remove the rock in detail. This was the plan that was subsequently
put into practice in the great works at Edison, New Jersey. A series of
three-inch holes twenty feet deep were drilled eight feet apart, about
twelve feet back of the ore-bank, and into these were inserted dynamite
cartridges. The blast would dislodge thirty to thirty-five thousand tons
of rock, which was scooped up by great steam-shovels and loaded on to
skips carried by a line of cars on a narrow-gauge railroad running
to and from the crushing mill. Here the material was automatically
delivered to the giant rolls. The problem included handling and crushing
the "run of the mine," without selection. The steam-shovel did not
discriminate, but picked up handily single pieces weighing five or six
tons and loaded them on the skips with quantities of smaller lumps.
When the skips arrived at the giant rolls, their contents were dumped
automatically into a superimposed hopper. The rolls were well named, for
with ear-splitting noise they broke up in a few seconds the great pieces
of rock tossed in from the skips.
It is not easy to appreciate to the full the daring exemplified in these
great crushing rolls, or rather "rock-crackers," without having watched
them in operation delivering their "solar-plexus" blows. It was only
as one might stand in their vicinity and hear the thunderous roar
accompanying the smashing and rending of the massive rocks as they
disappeared from view that the mind was overwhelmed with a sense of the
magnificent proportions of this operation. The enormous force exerted
during this process may be illustrated from the fact that during its
development, in running one of the early forms of rolls, pieces of rock
weighing more than half a ton would be shot up in the air to a height of
twenty or twenty-five feet.
The giant rolls were two solid cylinders, six feet in diameter and five
feet long, made of cast iron. To the faces of these rolls were bolted a
series of heavy, chilled-iron plates containing a number of projecting
knobs two inches high. Each roll had also two rows of four-inch knobs,
intended to strike a series of hammer-like blows. The rolls were set
face to face fourteen inches apart, in a heavy frame, and the total
weight was one hundred and thirty tons, of which seventy tons were in
moving parts. The space between these two rolls allowed pieces of rock
measuring less than fourteen inches to descend to other smaller rolls
placed below. The giant rolls were belt-driven, in opposite directions,
through friction clutches, although the belt was not depended upon for
the actual crushing. Previous to the dumping of a skip, the rolls were
speeded up to a circumferential velocity of nearly a mile a minute, thus
imparting to them the terrific momentum that would break up easily in a
few seconds boulders weighing five or six tons each. It was as though a
rock of this size had got in the way of two express trains travelling
in opposite directions at nearly sixty miles an hour. In other words,
it was the kinetic energy of the rolls that crumbled up the rocks with
pile-driver effect. This sudden strain might have tended to stop the
engine driving the rolls; but by an ingenious clutch arrangement the
belt was released at the moment of resistance in the rolls by reason of
the rocks falling between them. The act of breaking and crushing would
naturally decrease the tremendous momentum, but after the rock was
reduced and the pieces had passed through, the belt would again come
into play, and once more speed up the rolls for a repetition of their
regular prize-fighter duty.
On leaving the giant rolls the rocks, having been reduced to pieces not
larger than fourteen inches, passed into the series of "Intermediate
Rolls" of similar construction and operation, by which they were still
further reduced, and again passed on to three other sets of rolls
of smaller dimensions. These latter rolls were also face-lined with
chilled-iron plates; but, unlike the larger ones, were positively
driven, reducing the rock to pieces of about one-half-inch size, or
smaller. The whole crushing operation of reduction from massive boulders
to small pebbly pieces having been done in less time than the telling
has occupied, the product was conveyed to the "Dryer," a tower nine
feet square and fifty feet high, heated from below by great open furnace
fires. All down the inside walls of this tower were placed cast-iron
plates, nine feet long and seven inches wide, arranged alternately in
"fish-ladder" fashion. The crushed rock, being delivered at the top,
would fall down from plate to plate, constantly exposing different
surfaces to the heat, until it landed completely dried in the lower
portion of the tower, where it fell into conveyors which took it up to
the stock-house.
This method of drying was original with Edison. At the time this adjunct
to the plant was required, the best dryer on the market was of a rotary
type, which had a capacity of only twenty tons per hour, with the
expenditure of considerable power. As Edison had determined upon
treating two hundred and fifty tons or more per hour, he decided to
devise an entirely new type of great capacity, requiring a minimum of
power (for elevating the material), and depending upon the force of
gravity for handling it during the drying process. A long series of
experiments resulted in the invention of the tower dryer with a capacity
of three hundred tons per hour.
The rock, broken up into pieces about the size of marbles, having been
dried and conveyed to the stock-house, the surplusage was automatically
carried out from the other end of the stock-house by conveyors, to
pass through the next process, by which it was reduced to a powder. The
machinery for accomplishing this result represents another interesting
and radical departure of Edison from accepted usage. He had investigated
all the crushing-machines on the market, and tried all he could get.
He found them all greatly lacking in economy of operation; indeed, the
highest results obtainable from the best were 18 per cent. of actual
work, involving a loss of 82 per cent. by friction. His nature revolted
at such an immense loss of power, especially as he proposed the crushing
of vast quantities of ore. Thus, he was obliged to begin again at the
foundation, and he devised a crushing-machine which was subsequently
named the "Three-High Rolls," and which practically reversed the above
figures, as it developed 84 per cent. of work done with only 16 per
cent. loss in friction.
A brief description of this remarkable machine will probably interest
the reader. In the two end pieces of a heavy iron frame were set three
rolls, or cylinders--one in the centre, another below, and the other
above--all three being in a vertical line. These rolls were of cast
iron three feet in diameter, having chilled-iron smooth face-plates of
considerable thickness. The lowest roll was set in a fixed bearing at
the bottom of the frame, and, therefore, could only turn around on its
axis. The middle and top rolls were free to move up or down from and
toward the lower roll, and the shafts of the middle and upper rolls were
set in a loose bearing which could slip up and down in the iron frame.
It will be apparent, therefore, that any material which passed in
between the top and the middle rolls, and the middle and bottom rolls,
could be ground as fine as might be desired, depending entirely upon the
amount of pressure applied to the loose rolls. In operation the material
passed first through the upper and middle rolls, and then between the
middle and lowest rolls.
This pressure was applied in a most ingenious manner. On the ends of the
shafts of the bottom and top rolls there were cylindrical sleeves, or
bearings, having seven sheaves, in which was run a half-inch endless
wire rope. This rope was wound seven times over the sheaves as above,
and led upward and over a single-groove sheave which was operated by the
piston of an air cylinder, and in this manner the pressure was applied
to the rolls. It will be seen, therefore, that the system consisted in a
single rope passed over sheaves and so arranged that it could be varied
in length, thus providing for elasticity in exerting pressure and
regulating it as desired. The efficiency of this system was incomparably
greater than that of any other known crusher or grinder, for while a
pressure of one hundred and twenty-five thousand pounds could be exerted
by these rolls, friction was almost entirely eliminated because the
upper and lower roll bearings turned with the rolls and revolved in the
wire rope, which constituted the bearing proper.
The same cautious foresight exercised by Edison in providing a safety
device--the fuse--to prevent fires in his electric-light system, was
again displayed in this concentrating plant, where, to save possible
injury to its expensive operating parts, he devised an analogous factor,
providing all the crushing machinery with closely calculated "safety
pins," which, on being overloaded, would shear off and thus stop the
machine at once.
The rocks having thus been reduced to fine powder, the mass was ready
for screening on its way to the magnetic separators. Here again Edison
reversed prior practice by discarding rotary screens and devising a form
of tower screen, which, besides having a very large working capacity
by gravity, eliminated all power except that required to elevate the
material. The screening process allowed the finest part of the crushed
rock to pass on, by conveyor belts, to the magnetic separators, while
the coarser particles were in like manner automatically returned to the
rolls for further reduction.
In a narrative not intended to be strictly technical, it would probably
tire the reader to follow this material in detail through the numerous
steps attending the magnetic separation. These may be seen in a
diagram reproduced from the above-named article in the Iron Age, and
supplemented by the following extract from the Electrical Engineer,
New York, October 28, 1897: "At the start the weakest magnet at the top
frees the purest particles, and the second takes care of others; but the
third catches those to which rock adheres, and will extract particles
of which only one-eighth is iron. This batch of material goes back for
another crushing, so that everything is subjected to an equality of
refining. We are now in sight of the real 'concentrates,' which are
conveyed to dryer No. 2 for drying again, and are then delivered to
the fifty-mesh screens. Whatever is fine enough goes through to the
eight-inch magnets, and the remainder goes back for recrushing.
Below the eight-inch magnets the dust is blown out of the particles
mechanically, and they then go to the four-inch magnets for final
cleansing and separation.... Obviously, at each step the percentage of
felspar and phosphorus is less and less until in the final concentrates
the percentage of iron oxide is 91 to 93 per cent. As intimated at the
outset, the tailings will be 75 per cent. of the rock taken from the
veins of ore, so that every four tons of crude, raw, low-grade ore will
have yielded roughly one ton of high-grade concentrate and three tons of
sand, the latter also having its value in various ways."
This sand was transported automatically by belt conveyors to the rear of
the works to be stored and sold. Being sharp, crystalline, and even in
quality, it was a valuable by-product, finding a ready sale for
building purposes, railway sand-boxes, and various industrial uses. The
concentrate, in fine powdery form, was delivered in similar manner to a
stock-house.
As to the next step in the process, we may now quote again from the
article in the Iron Age: "While Mr. Edison and his associates were
working on the problem of cheap concentration of iron ore, an added
difficulty faced them in the preparation of the concentrates for the
market. Furnacemen object to more than a very small proportion of fine
ore in their mixtures, particularly when the ore is magnetic, not easily
reduced. The problem to be solved was to market an agglomerated material
so as to avoid the drawbacks of fine ore. The agglomerated product must
be porous so as to afford access of the furnace-reducing gases to the
ore. It must be hard enough to bear transportation, and to carry the
furnace burden without crumbling to pieces. It must be waterproof, to a
certain extent, because considerations connected with securing low rates
of freight make it necessary to be able to ship the concentrates to
market in open coal cars, exposed to snow and rain. In many respects the
attainment of these somewhat conflicting ends was the most perplexing
of the problems which confronted Mr. Edison. The agglomeration of the
concentrates having been decided upon, two other considerations, not
mentioned above, were of primary importance--first, to find a suitable
cheap binding material; and, second, its nature must be such that
very little would be necessary per ton of concentrates. These severe
requirements were staggering, but Mr. Edison's courage did not falter.
Although it seemed a well-nigh hopeless task, he entered upon the
investigation with his usual optimism and vim. After many months
of unremitting toil and research, and the trial of thousands of
experiments, the goal was reached in the completion of a successful
formula for agglomerating the fine ore and pressing it into briquettes
by special machinery."
This was the final process requisite for the making of a completed
commercial product. Its practice, of course, necessitated the addition
of an entirely new department of the works, which was carried into
effect by the construction and installation of the novel mixing and
briquetting machinery, together with extensions of the conveyors, with
which the plant had already been liberally provided.
Briefly described, the process consisted in mixing the concentrates with
the special binding material in machines of an entirely new type, and in
passing the resultant pasty mass into the briquetting machines, where it
was pressed into cylindrical cakes three inches in diameter and one and
a half inches thick, under successive pressures of 7800, 14,000, and
60,000 pounds. Each machine made these briquettes at the rate of sixty
per minute, and dropped them into bucket conveyors by which they were
carried into drying furnaces, through which they made five loops, and
were then delivered to cross-conveyors which carried them into the
stock-house. At the end of this process the briquettes were so hard
that they would not break or crumble in loading on the cars or in
transportation by rail, while they were so porous as to be capable of
absorbing 26 per cent. of their own volume in alcohol, but repelling
water absolutely--perfect "old soaks."
Thus, with never-failing persistence and patience, coupled with intense
thought and hard work, Edison met and conquered, one by one, the complex
difficulties that confronted him. He succeeded in what he had set out
to do, and it is now to be noted that the product he had striven so
sedulously to obtain was a highly commercial one, for not only did the
briquettes of concentrated ore fulfil the purpose of their creation, but
in use actually tended to increase the working capacity of the furnace,
as the following test, quoted from the Iron Age, October 28, 1897,
will attest: "The only trial of any magnitude of the briquettes in
the blast-furnace was carried through early this year at the Crane Iron
Works, Catasauqua, Pennsylvania, by Leonard Peckitt.
"The furnace at which the test was made produces from one hundred to one
hundred and ten tons per day when running on the ordinary mixture. The
charging of briquettes was begun with a percentage of 25 per cent.,
and was carried up to 100 per cent. The following is the record of the
results:
RESULTS OF WORKING BRIQUETTES AT THE CRANE FURNACE
Quantity of Phos- ManDate
Briquette Tons Silica phorus Sulphur ganese
Working
Per Cent.
January 5th 25 104 2.770 0.830 0.018 0.500
January 6th 37 1/2 4 1/2 2.620 0 740 0.018 0.350
January 7th 50 138 1/2 2.572 0.580 0.015 0.200
January 8th 75 119 1.844 0.264 0.022 0.200
January 9th 100 138 1/2 1.712 0.147 0.038 0.185
"On the 9th, at 5 P.M., the briquettes having been nearly exhausted,
the percentage was dropped to 25 per cent., and on the 10th the output
dropped to 120 tons, and on the 11th the furnace had resumed the usual
work on the regular standard ores.
"These figures prove that the yield of the furnace is considerably
increased. The Crane trial was too short to settle the question to what
extent the increase in product may be carried. This increase in output,
of course, means a reduction in the cost of labor and of general
expenses.
"The richness of the ore and its purity of course affect the limestone
consumption. In the case of the Crane trial there was a reduction from
30 per cent. to 12 per cent. of the ore charge.
"Finally, the fuel consumption is reduced, which in the case of the
Eastern plants, with their relatively costly coke, is a very important
consideration. It is regarded as possible that Eastern furnaces will
be able to use a smaller proportion of the costlier coke and
correspondingly increase in anthracite coal, which is a cheaper fuel
in that section. So far as foundry iron is concerned, the experience at
Catasauqua, Pennsylvania, brief as it has been, shows that a stronger
and tougher metal is made."
Edison himself tells an interesting little story in this connection,
when he enjoyed the active help of that noble character, John Fritz,
the distinguished inventor and pioneer of the modern steel industry
in America. He says: "When I was struggling along with the iron-ore
concentration, I went to see several blast-furnace men to sell the ore
at the market price. They saw I was very anxious to sell it, and they
would take advantage of my necessity. But I happened to go to Mr. John
Fritz, of the Bethlehem Steel Company, and told him what I was doing.
'Well,' he said to me, 'Edison, you are doing a good thing for the
Eastern furnaces. They ought to help you, for it will help us out. I am
willing to help you. I mix a little sentiment with business, and I will
give you an order for one hundred thousand tons.' And he sat right down
and gave me the order."
The Edison concentrating plant has been sketched in the briefest outline
with a view of affording merely a bare idea of the great work of its
projector. To tell the whole story in detail and show its logical
sequence, step by step, would take little less than a volume in itself,
for Edison's methods, always iconoclastic when progress is in sight,
were particularly so at the period in question. It has been said that
"Edison's scrap-heap contains the elements of a liberal education,"
and this was essentially true of the "discard" during the ore-milling
experience. Interesting as it might be to follow at length the numerous
phases of ingenious and resourceful development that took place during
those busy years, the limit of present space forbids their relation. It
would, however, be denying the justice that is Edison's due to omit all
mention of two hitherto unnamed items in particular that have added
to the world's store of useful devices. We refer first to the great
travelling hoisting-crane having a span of two hundred and fifteen feet,
and used for hoisting loads equal to ten tons, this being the largest
of the kind made up to that time, and afterward used as a model by many
others. The second item was the ingenious and varied forms of conveyor
belt, devised and used by Edison at the concentrating works, and
subsequently developed into a separate and extensive business by an
engineer to whom he gave permission to use his plans and patterns.
Edison's native shrewdness and knowledge of human nature was put to
practical use in the busy days of plant construction. It was found
impossible to keep mechanics on account of indifferent residential
accommodations afforded by the tiny village, remote from civilization,
among the central mountains of New Jersey. This puzzling question was
much discussed between him and his associate, Mr. W. S. Mallory, until
finally he said to the latter: "If we want to keep the men here we must
make it attractive for the women--so let us build some houses that will
have running water and electric lights, and rent at a low rate." He set
to work, and in a day finished a design for a type of house. Fifty were
quickly built and fully described in advertising for mechanics. Three
days' advertisements brought in over six hundred and fifty applications,
and afterward Edison had no trouble in obtaining all the first-class men
he required, as settlers in the artificial Yosemite he was creating.
We owe to Mr. Mallory a characteristic story of this period as to
an incidental unbending from toil, which in itself illustrates the
ever-present determination to conquer what is undertaken: "Along in
the latter part of the nineties, when the work on the problem of
concentrating iron ore was in progress, it became necessary when leaving
the plant at Edison to wait over at Lake Hopatcong one hour for a
connecting train. During some of these waits Mr. Edison had seen me play
billiards. At the particular time this incident happened, Mrs. Edison
and her family were away for the summer, and I was staying at the
Glenmont home on the Orange Mountains.
"One hot Saturday night, after Mr. Edison had looked over the evening
papers, he said to me: 'Do you want to play a game of billiards?'
Naturally this astonished me very much, as he is a man who cares
little or nothing for the ordinary games, with the single exception of
parcheesi, of which he is very fond. I said I would like to play, so we
went up into the billiard-room of the house. I took off the cloth, got
out the balls, picked out a cue for Mr. Edison, and when we banked for
the first shot I won and started the game. After making two or three
shots I missed, and a long carom shot was left for Mr. Edison, the cue
ball and object ball being within about twelve inches of each other, and
the other ball a distance of nearly the length of the table. Mr. Edison
attempted to make the shot, but missed it and said 'Put the balls back.'
So I put them back in the same position and he missed it the second
time. I continued at his request to put the balls back in the same
position for the next fifteen minutes, until he could make the shot
every time--then he said: 'I don't want to play any more.'"
Having taken a somewhat superficial survey of the great enterprise under
consideration; having had a cursory glance at the technical development
of the plant up to the point of its successful culmination in the making
of a marketable, commercial product as exemplified in the test at the
Crane Furnace, let us revert to that demonstration and note the events
that followed. The facts of this actual test are far more eloquent than
volumes of argument would be as a justification of Edison's assiduous
labors for over eight years, and of the expenditure of a fortune in
bringing his broad conception to a concrete possibility. In the patient
solving of tremendous problems he had toiled up the mountain-side of
success--scaling its topmost peak and obtaining a view of the boundless
prospect. But, alas! "The best laid plans o' mice and men gang aft
agley." The discovery of great deposits of rich Bessemer ore in the
Mesaba range of mountains in Minnesota a year or two previous to the
completion of his work had been followed by the opening up of those
deposits and the marketing of the ore. It was of such rich character
that, being cheaply mined by greatly improved and inexpensive methods,
the market price of crude ore of like iron units fell from about
$6.50 to $3.50 per ton at the time when Edison was ready to supply his
concentrated product. At the former price he could have supplied the
market and earned a liberal profit on his investment, but at $3.50 per
ton he was left without a reasonable chance of competition. Thus was
swept away the possibility of reaping the reward so richly earned by
years of incessant thought, labor, and care. This great and notable
plant, representing a very large outlay of money, brought to completion,
ready for business, and embracing some of the most brilliant and
remarkable of Edison's inventions and methods, must be abandoned by
force of circumstances over which he had no control, and with it must
die the high hopes that his progressive, conquering march to success had
legitimately engendered.
The financial aspect of these enterprises is often overlooked and
forgotten. In this instance it was of more than usual import and
seriousness, as Edison was virtually his own "backer," putting into the
company almost the whole of all the fortune his inventions had brought
him. There is a tendency to deny to the capital that thus takes
desperate chances its full reward if things go right, and to insist that
it shall have barely the legal rate of interest and far less than the
return of over-the-counter retail trade. It is an absolute fact that the
great electrical inventors and the men who stood behind them have had
little return for their foresight and courage. In this instance, when
the inventor was largely his own financier, the difficulties and perils
were redoubled. Let Mr. Mallory give an instance: "During the latter
part of the panic of 1893 there came a period when we were very hard
up for ready cash, due largely to the panicky conditions; and a large
pay-roll had been raised with considerable difficulty. A short time
before pay-day our treasurer called me up by telephone, and said: 'I
have just received the paid checks from the bank, and I am fearful
that my assistant, who has forged my name to some of the checks, has
absconded with about $3000.' I went immediately to Mr. Edison and
told him of the forgery and the amount of money taken, and in what an
embarrassing position we were for the next pay-roll. When I had finished
he said: 'It is too bad the money is gone, but I will tell you what to
do. Go and see the president of the bank which paid the forged checks.
Get him to admit the bank's liability, and then say to him that Mr.
Edison does not think the bank should suffer because he happened to have
a dishonest clerk in his employ. Also say to him that I shall not ask
them to make the amount good.' This was done; the bank admitting its
liability and being much pleased with this action. When I reported to
Mr. Edison he said: 'That's all right. We have made a friend of the
bank, and we may need friends later on.' And so it happened that some
time afterward, when we greatly needed help in the way of loans, the
bank willingly gave us the accommodations we required to tide us over a
critical period."
This iron-ore concentrating project had lain close to Edison's heart and
ambition--indeed, it had permeated his whole being to the exclusion
of almost all other investigations or inventions for a while. For five
years he had lived and worked steadily at Edison, leaving there only on
Saturday night to spend Sunday at his home in Orange, and returning to
the plant by an early train on Monday morning. Life at Edison was of the
simple kind--work, meals, and a few hours' sleep--day by day. The little
village, called into existence by the concentrating works, was of the
most primitive nature and offered nothing in the way of frivolity or
amusement. Even the scenery is austere. Hence Edison was enabled
to follow his natural bent in being surrounded day and night by his
responsible chosen associates, with whom he worked uninterrupted by
outsiders from early morning away into the late hours of the evening.
Those who were laboring with him, inspired by his unflagging enthusiasm,
followed his example and devoted all their long waking hours to the
furtherance of his plans with a zeal that ultimately bore fruit in the
practical success here recorded.
In view of its present status, this colossal enterprise at Edison may
well be likened to the prologue of a play that is to be subsequently
enacted for the benefit of future generations, but before ringing down
the curtain it is desirable to preserve the unities by quoting the
words of one of the principal actors, Mr. Mallory, who says: "The
Concentrating Works had been in operation, and we had produced a
considerable quantity of the briquettes, and had been able to sell
only a portion of them, the iron market being in such condition that
blast-furnaces were not making any new purchases of iron ore, and
were having difficulty to receive and consume the ores which had been
previously contracted for, so what sales we were able to make were at
extremely low prices, my recollection being that they were between $3.50
and $3.80 per ton, whereas when the works had started we had hoped to
obtain $6.00 to $6.50 per ton for the briquettes. We had also thoroughly
investigated the wonderful deposit at Mesaba, and it was with the
greatest possible reluctance that Mr. Edison was able to come finally to
the conclusion that, under existing conditions, the concentrating plant
could not then be made a commercial success. This decision was reached
only after the most careful investigations and calculations, as Mr.
Edison was just as full of fight and ambition to make it a success as
when he first started.
"When this decision was reached Mr. Edison and I took the Jersey Central
train from Edison, bound for Orange, and I did not look forward to the
immediate future with any degree of confidence, as the concentrating
plant was heavily in debt, without any early prospect of being able
to pay off its indebtedness. On the train the matter of the future was
discussed, and Mr. Edison said that, inasmuch as we had the knowledge
gained from our experience in the concentrating problem, we must, if
possible, apply it to some practical use, and at the same time we must
work out some other plans by which we could make enough money to pay
off the Concentrating Company's indebtedness, Mr. Edison stating most
positively that no company with which he had personally been actively
connected had ever failed to pay its debts, and he did not propose to
have the Concentrating Company any exception.
"In the discussion that followed he suggested several kinds of work
which he had in his mind, and which might prove profitable. We
figured carefully over the probabilities of financial returns from the
Phonograph Works and other enterprises, and after discussing many plans,
it was finally decided that we would apply the knowledge we had gained
in the concentrating plant by building a plant for manufacturing
Portland cement, and that Mr. Edison would devote his attention to the
developing of a storage battery which did not use lead and sulphuric
acid. So these two lines of work were taken up by Mr. Edison with just
as much enthusiasm and energy as is usual with him, the commercial
failure of the concentrating plant seeming not to affect his spirits
in any way. In fact, I have often been impressed strongly with the fact
that, during the dark days of the concentrating problem, Mr. Edison's
desire was very strong that the creditors of the Concentrating Works
should be paid in full; and only once did I hear him make any reference
to the financial loss which he himself made, and he then said: 'As
far as I am concerned, I can any time get a job at $75 per month as
a telegrapher, and that will amply take care of all my personal
requirements.' As already stated, however, he started in with the
maximum amount of enthusiasm and ambition, and in the course of about
three years we succeeded in paying off all the indebtedness of the
Concentrating Works, which amounted to several hundred thousand dollars.
"As to the state of Mr. Edison's mind when the final decision was
reached to close down, if he was specially disappointed, there was
nothing in his manner to indicate it, his every thought being for the
future, and as to what could be done to pull us out of the financial
situation in which we found ourselves, and to take advantage of the
knowledge which we had acquired at so great a cost."
It will have been gathered that the funds for this great experiment
were furnished largely by Edison. In fact, over two million dollars were
spent in the attempt. Edison's philosophic view of affairs is given in
the following anecdote from Mr. Mallory: "During the boom times of 1902,
when the old General Electric stock sold at its high-water mark of about
$330, Mr. Edison and I were on our way from the cement plant at New
Village, New Jersey, to his home at Orange. When we arrived at Dover,
New Jersey, we got a New York newspaper, and I called his attention to
the quotation of that day on General Electric. Mr. Edison then asked:
'If I hadn't sold any of mine, what would it be worth to-day?' and after
some figuring I replied: 'Over four million dollars.' When Mr. Edison
is thinking seriously over a problem he is in the habit of pulling his
right eyebrow, which he did now for fifteen or twenty seconds. Then his
face lighted up, and he said: 'Well, it's all gone, but we had a hell of
a good time spending it.'" With which revelation of an attitude worthy
of Mark Tapley himself, this chapter may well conclude.