Gold ore to the value of nearly £60,000 is mined every week in Canada's largest gold mine. Hollinger Mine, a remarkable example of engineering and one of the world’s greatest producers of gold, rivals the famous mines of the Rand, in South Africa
CAR LOADS OF GOLD-BEARING ORE are hauled by electric trolley locomotives from the working faces in the various levels of Hollinger Gold Mine to the main shaft. There are 200 miles of railway track below the surface in this enormous Canadian mine.
THE largest gold mine on the American continent is Hollinger Mine, in the Porcupine district of Ontario, Canada (see also the chapter on “Canada’s Mineral Wealth”). It is famed for its model equipment and organization. This great Canadian enterprise rivals the famous gold mines of South Africa.
In 1936 Hollinger Mine produced over £3,000,000 worth of gold, and during its first twenty-seven years it yielded £48,000,000 worth of the metal. This huge total, however, was really made in fifteen years, between 1921 and 1936. For the first twelve years of its history Fortune presided over Hollinger Mine with a twisted smile. Over and over again it looked as if the enterprise was not worth carrying on. Then suddenly, in 1921, this mammoth among gold mines began to flourish. Since then it has been setting up a new production record one month only to demolish it the next.
During 1936 over 5,000 tons of ore were hoisted up its central shaft every twenty-four hours. From the beginning of mining operations until December 1936 there have been broken and hoisted from this single mine over 35,000,000 tons of ore.
Three thousand men and £2,000,000 worth of machinery, pushed to the limit, will not be capable of draining the scores of veins of the mine during the active lifetime of the present generation of miners. Engineers have burrowed into the earth’s interior for close upon a mile, but the gold goes still deeper, and one expert, at least, has declared that it may continue down far beyond human reach.
Yet, scarcely more than a generation ago the site was going begging. True, mines had been staked all round it, for the district is rich in the precious metals. Then, one day in 1909, two men, Benny Hollinger and his partner, Alex Gillies, made their way laboriously into Timmins, then a mere patch of brush with a few wooden shanties, some 500 miles from the nearest city and forty-five miles from the railhead. They wandered about, and looked over the ground already staked. Old-timers directed them, freely and casually, to the present Hollinger under the impression that the choice locations had been taken up and that they were sending the newcomers to some of the second-rate property that was left.
Hollinger and Gillies staked twelve claims and decided ownership by tossing a coin. Unsuspectingly they risked millions. Hollinger took the west and Gillies the east. Both properties were eventually combined and are known to-day as Hollinger Consolidated Gold Mines, Ltd. Benny Hollinger’s six claims, however, were the foundation of the record-breaking workings.
Rusty and forgotten, lying among the rocks that hid a thousand fortunes, was an abandoned prospector’s forge. Beside it were some weed-grown workings. No other trace has ever been found of the unknown who had fortune within his fingers and let it slip. The odds are that he never knew he had thrown his chance away. Nor was he the only one. Hundreds of others had worn a trail over the quartz veins. A portage crossed Hollinger Hill, and many a pack-laden woodsman had noted it, only to enlarge upon the difficulties which it added to his enforced walk.
Having staked their claims, the two pioneers began to develop their property. The railway was forty-five miles away. Roads had to be cut through bush and swamp to install machinery. Eight hundred teams of horses and many yoke of oxen were kept moving during the entire summer of 1910, carting equipment and supplies. By 1911 erection of a thirty-stamp mill was on the way to completion when bush fires swept the property. In 1912, when things were once more under way, a six-months strike tangled it all up again. No sooner had the mine recovered from this disastrous strike than the war of 1914-18 broke out and took nearly all the workers. There were several times in its early history when Hollinger backers were about to withdraw.
Working Against Time
Fortunately they hung on, and by sheer grit, perseverance, backed by engineering skill and fine organization, built up an industry which is acknowledged as one of the wonders of the mining world. At Hollinger 3,000 men are toiling continuously in a plant which cost £2,000,000 to create, in a plant which is turning out bullion with the same regularity as another factory might turn out axle grease or pearlheaded pins.
The surface plant of this single mine sprawls over a thousand acres — dotted with giant mills, model factories, workshops and offices. Underground, its tunnels cut back and forth, up and down, through the Earth’s interior. Levels, crosscuts, shafts and the rest of its network of subways would run for a distance of 250 miles if it were possible to straighten them all out into one. The surface plant seen at night from the other side of the drab lake of waste and tailings, which separates it from the town of Timmins, stands out of the dark as if it was a number of grain elevators at some Great Lakes port and as if half the ships of the upper Lakes were being loaded.
There is no such thing as the end of the day’s work. At the surface, the mill runs ceaselessly, staffed by a thousand men, working in eight-hours shifts. Below, there is twice that number. At the shafts they split up and disappear in little gangs, a score or so in a group, dropping off at different levels and working as independent units. In the gloom of the levels, faces acquire a grey sameness that makes all miners look somewhat alike, but this underground battalion is a curious assembly of names — MacDonalds, Manzinis, Ostojichs, O’Rourkes, Shulaks, Hawkins, Costellos, Belangers, Landowskis, Schneiders, Holgevacs and even Smiths. This mixture of races has one particular trait in common, the desire to do more than a day’s work in each eight hours. This desire should not create the impression that Hollinger miners are unique among the Earth’s inhabitants, for much of the underground work is done on a contract basis.
AT THE 1,250-FEET LEVEL in Hollinger Mine, below 800 feet the railway tracks are laid to a gauge of 3 feet. The levels are all connected with one another and with the surface by vertical shafts, which contain hoisting machinery, ventilating and pumping equipment and the like.
Time at Hollinger is not something to put in, but to work against. This contract system is an added driving force, but Hollinger miners are not lazy men at any time. Underground, they work rapidly and almost automatically. They have every sort of mechanical assistance. Pipe lines carry compressed air to every vein where operations are proceeding. Drills, sometimes eight to ten feet long, bite viciously into the ore, and explosives finish the job. It takes 250 boxes of dynamite a day and 10,000 cubic feet of compressed air a second to keep things going. The rock, ripped out of the veins, is shovelled into cars. If there were a more rapid, effective and efficient way of loading, the present method would be forthwith replaced. A glimpse at the other processes in the business of extracting gold proves that every step has been taken to eliminate all waste effort. Affairs underground are controlled as carefully and precisely as the moves in a chess tournament. They must be, for even a comparatively slight delay would seriously upset the smoothness and swiftness of the process. The mill, hundreds of feet above the miners’ heads, has a large and everlasting appetite and it is operated continuously, day and night, without any intermission.
Five thousand tons of raw ore are a huge amount of rock to come out of one hole in the ground every twenty-four hours, day in and day out. It could not be removed with the methods in vogue two decades ago. Even with the most advanced systems and the most modern mechanical aids, it can be handled only with almost superhuman organization.
There are, for instance, no pathetic mine mules in this establishment. Everything is electrified and, where possible, made automatic. On every level where ore is being taken out, a dwarf of an electric railway runs from vein to shaft. There are 200 miles of track in this hidden transportation system, and an additional seven miles are operated above the surface. The underground rolling stock comprises 750 1½-tons cars, 618 3-tons cars, twenty-one trolley locomotives and seven storage-battery locomotives. In addition there are 254 mine-service trucks, thirty-six contractor’s trucks, 154 timber trucks for distributing timber and thirty-five wooden body scrap cars. From the 800-feet level up, tracks are laid to a gauge of 18 in. and below that level to a gauge of 3 feet.
Central Shaft 3,158 Feet Deep
Every ton of ore mined comes to the surface by the central shaft. This opening into the mine is 8 ft. 2 in. by 32 ft. 8 in. and is 3,158 feet deep. It is built up of massive timbering divided in cross section into several compartments. Four are reserved for hoisting. Other compartments accommodate the ventilation equipment, pump rods, water pipes, electric cables and so forth. There are twenty-three shafts in the mine altogether, four sunk from the surface, the others being sunk from different levels; the aggregate length is over four miles. At each shaft mouth the hoisting machinery is the most modern and efficient obtainable. In the engine room, a separate building away from the shaft, the engineer at the levers knows to an inch the exact position of the cage, though it may be half a mile below him. He can control its rise and fall within half an inch and is able to check its drop almost instantly.
From the shafts branch off the levels, one below the other, as if they were corridors in a tall office building. Down to the 300-feet level they are 100 feet apart, thence 125 feet apart to the 800-feet level, and below that depth 150 feet apart. The lowest point reached by the shafts is 5,300 feet, over a mile. The levels in turn are connected by cross-cuts or drives, the whole forming a complicated network of subterranean passages, striking off in all directions. An underground tourist, left to himself in the mine, could be hopelessly lost in a few minutes.
There are more miles of streets, so to speak, in this little section of the earth’s interior than there are roads in any one of many Canadian towns. This maze of tunnels is constantly changing. New levels are continually being cut and old ones altered. During 1936, 62,114 feet of drifting (main levels) and 25,641 feet of cross-cutting were formed. A vein may be exhausted, filled with waste sent down from the top, abandoned and forgotten.
ON THE SURFACE. Hollinger Gold Mine, situated at Timmins, Ontario, covers an area of more than 1,000 acres, with its giant mills and refining plant, workshops, model factories and offices. From the start of operations to December 1936 more than 35,000,000 tons of gold-bearing ore had been brought up from this one mine. Work is continuing at the rate of nearly 6,000 tons a day.
No one man could hope to know, with mathematical exactness, the geography of Hollinger’s subterranean workings. The veins already opened number nearly a hundred. Thirty-one surveyors are always on the job. Every week they plot on a detailed chart in the general offices the new developments, the alterations and all the changes in the underground railways and highways. Were this not done regularly Hollinger might easily become a muddle and its underground operations might be hopelessly tangled.
The mine workings extend over an area 1⅜ miles long, with a maximum width of three-quarters of a mile and to a depth of at least 4,860 feet. Extraction of ore by stoping is confined at present to horizons above the 2,750-feet level, and development work goes on below that level only. Thus, above the 2,750-feet level drives or cuts are made into the vein or reef, dividing it into blocks, called “stopes”. The operation of cutting out the blocks, removing the valuable parts and filling in the cavities with the rubbish, or with the material lowered from above is termed stoping.
In the drives, or cross-cuts, a drilling crew consists of four — a driller, a helper and two muckers. A round of twenty holes is drilled into the face of the workings, explosives are rammed home and fired, and from 30 to 50 tons of rock are broken. The loosened material is thrown by hand into waiting cars and hurried away to the crusher. In the development headings the broken rock is removed by scrapers, mechanically operated devices consisting of a portable steel loading slide on which is mounted a scraper. The scraper, resembling a giant scoop, burrows into the debris, which is hauled out by hoist ropes.
Tests Every Few Minutes
As the gangs blast and drill, tests are made every few minutes. By means of fifteen hundred assays a day the exact value of the ore that each little group of men is tearing loose is known almost to the cent. One of the most remarkable features of this large-scale drive for precious metal is the fact that the value of the ore per ton, as it is sent up. is virtually constant. The veins vary in richness, but the orders, are that the rock coming to the surface crushers must be worth approximately eight dollars (about 33 shillings a ton). This is not high-grade ore. There are veins in Hollinger worth triple that figure, but, by keeping steadily at the eight-dollar mark, and mixing the output from different levels, the rich with the low-grade, almost all of it can be used. At the 2,900-feet level, close to the central shaft, is the crushing plant. It is equipped with a 4 feet by 6 feet jaw crusher driven by a 200 horse-power motor at 120 revolutions a minute. Every bit of ore, from every part of the mine, comes here, spilling down chutes from the upper levels and hauled in from all parts of the workings. Here it is mixed for the mill by being pounded into pieces the size of a man’s head, when it is ready for hoisting to the surface. The orders are to make it average eight dollars a ton. During 1936 the average value of the hundreds or thousands of tons of ore hoisted to the surface was seven dollars and ninety-nine cents a ton.
From seven in the morning till eleven at night the gangs concentrate on getting the daily yield. Five thousand tons was the daily average for 1936. Since then this figure has advanced nearly another thousand. This record breaking is one of the marvels of Hollinger Mine.
WEIGHING A BRICK OF GOLD, the product of Hollinger Mine. Having been extracted from the ore, the gold is refined by smelting and cast into bars of bullion. Each brick, though small in bulk, is worth about £5,000, and a week’s production is valued at nearly £60,000. The average gold value of a ton of ore is eight dollars, or about 33 shillings.
Another marvel of the mine is its unique organization. From nearly midnight till morning special crews go down to get everything ready for the next sixteen-hours attack. They are charged with the maintenance and repair of all rock drills, hoists and air jacks, car dumps and water supply system; lubrication of mine cars and trucks, and repairs to cars that do not need sending to the surface shops; the installation and maintenance of all doors by which the shafts can be cut off from the workings on each level; the installation and maintenance of trolleyguard boxes; and the painting of identification signs at the intersections of headings.
At the 1,100-feet level is a repair shop, to which all machines which cannot be “doctored” on the job are brought for repairs. A factory at the surface is devoted exclusively to resharpening drills. Its capacity is 4,000 drills every eight hours. In another shop are made all the buckets, ore cars, skips and tanks used in the mine.
The duty of these special underground crews is to prepare and secure everything ready for the next day’s operations. Within half an hour of their departure a thousand men descend the mine. An observer following these men would find that they seem to be utterly swallowed up. The rattle and purr of drills may be heard in the distance. A headlight cuts through the level and a train roars past, the operator of the locomotive appearing to be part and parcel of the machinery. There is a rumble from the other end as the cars dump their loads.
It would still be dim underground under the most powerful of lights, and there is something spectral about a gang of miners, with their figures silhouetted out on the rock wall of a tunnel by their working lights. But the air is comparatively pure, and the workings are not wet — just damp enough to prevent dust. The dust in the shafts is controlled by the simple expedient of having fine-water sprays continually at work.
Natural Ventilation
Nature has her own ventilation system in action, foolproof, always working. The central shaft is a huge vent with a constant blast of used air pouring out of it, while the other shafts automatically act as intakes. Although Hollinger Mine would be considered a dry mine in many parts of the world, a considerable volume of surface water finds its way into the workings and has to be pumped out. The largest volume of water pumped from the mine in any one day was on April 30, 1934, when 2,887,000 gallons were discharged to the surface. This was equivalent to a flow of 1,998 gallons a minute.
The ore comes up the central shaft in skips, six tons to a load, in lumps the size of a man’s head. The skips dump the ore automatically into chutes which carry it to the crushers. From here it passes to the grinders, but as it does so limestone is added, 85 lb. of lime to every ton of ore. The grinder, a machine-age adaptation of the old pestle and mortar, crunches the rock endlessly.
After the grinders come the rollers. The ore is crumbled to half-inch sizes between two steel cylinders, and dropped on an endless belt, ready for the mill. Hanging over the belt is a powerful electro-magnet which snaps up every bit of iron or steel which may have fallen into the ore — nails, spikes, bolts, fragments of piping, bits of metal the size of a pinhead. The ore now passes to the 1,500-tons storage bin, sixty feet below the surface.
IN THE DEVELOPMENT HEADINGS of Hollinger Mine a mechanically operated scraper, resembling a giant scoop, burrows into the debris left by a blast. A round of about twenty holes having been drilled, explosives are rammed home and fired. Between 30 tons and 50 tons of rock are brought down and hauled out by the scraper. The photograph shows the 1,700 feet level.
Though the ore is now about to pass through the final processes, there is nothing of the precious metal about its appearance. It is neither more nor less glittering than the crushed stone on a country road. Cars carrying seven tons, operating on an incline, carry the ore from the underground bin to the top of the mill for further grinding. The cars dump their loads automatically. The grinding is performed in two stages by rod mills and by tube mills. As the ore passes to the rods a solution of cyanide of potassium is slowly added. The rods are 7 feet in diameter, 15 feet long and weigh 27 tons. They resemble nothing , so much as a battery of huge round-doored bank vaults in solemn revolution. They pound the mixture into coarse sand, and pass it on to the tube mills, from which it emerges, after more cyanide solution has been poured in, as a liquid mud.
The cyanide performs a simple but important service. In it, the pure gold dissolves as sugar dissolves in water. To give the cyanide every chance to do its work, the muddy mixture is poured into agitators — steel tanks fifty feet high — where blasts of compressed air are forced through and it bubbles steadily for twenty hours. By this time, the cyanide has dissolved all the gold worth while.
The sediment which remains, therefore, is paste, and the sooner it is eliminated the better. The mixture is washed and rewashed until it is free of mud and the gold-laden solution can be poured off into separate tanks. This solution, a liquid as clear as crystal, looks as if it contained less gold than the waters of an ordinary river. For all its innocent appearance it is deadly poison. A sip would be fatal. Every part of the building is plastered with warning signs.
Precious Sludge
Even the task of disposing of the waste mud which has now been taken out of the mixture is a problem in itself. There are several thousand tons of it to throw away each day. To haul it off and dump it would involve tremendous expense. The whole lake which once sparkled beside the mine has now been filled with it. As traces of the deadly cyanide mixture may still remain in it, a year must pass before vegetation of any sort will grow in the mine waste. So it is again mixed up, this time with water, and forced by powerful pumps through three miles of pipe line to be poured off into some abandoned claims.
All that remains to be done in the mill is to filter the gold out of the cyanide solution. Zinc dust is added to it, and the new mixture flows into huge box-shaped filters. It is squeezed through sheet after sheet of paper-covered canvas, which catches the gold and zinc while the cyanide drips through. The filtered solution goes back to be mixed with ore once more. Theoretically, it goes on and on for ever.
Once a week the sheets are removed from the filters. On them is seven days’ production of gold. Even yet it is far from recognizable. Perhaps the most accurate description of it is that it is a dirty sludge. The final product of the mill, it is carried to the refinery— gold, with the added zinc and a small amount of silver. The process of refining, though complex, is a standard one. The mixture is smelted and the gold poured off, molten, to cool into bars of bullion. Exactly 96 per cent of all the gold in the ore is secured by this process. To get the remaining 4 per cent would cost more than it is worth.
The finished product, as far as bulk is concerned, of a day’s operations might almost be wheeled off in a perambulator. Bulk, however, means nothing. Each small brick is worth £5,000 and a week’s production is valued at nearly £60,000. If Hollinger Mine were to stop suddenly for good, the gold market of the world would doubtless feel the shock.
A NEWLY CAST BAR OF GOLD from the refinery, on cooling, is cleaned by chipping with a hammer. This removes the slag which adheres to the gold. The gold, before being refined by smelting, contains small amounts of zinc and silver.
