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.
