The Iron Mines of North America.

Progress, Volume V, Issue 5, 1 March 1910, Page 165

The Iron Mines of North America.

It is the hoast of the Americans that they can Manufacture iron and steel cheaper than any other country in the world, in spite of unexampled distances between mine and works, and between works and deep water on the coast. How it is done we propose to show in the follow ing article First there is an advantage in the character of their mines. It has been said that if Nature had set out with the determination to assure the United States the premier position in the si eel industry of the world, she could scarcely have done so more effectively than by spreading out around Ihe western and southern shores of Lake Superior the huge deposits of iron ore that Uiere abound. Not only is there enormous abundance of ore, but it lies, especially in the Mesabi mine, on the surface, so that the ears run at once into the middle of it, and are at once loaded up by steam shovels. In addition, this ore is as good in quality as it is enormous in quantity, the greater part of it running over fifty per cent, of iron. It is a vast body of splendid ore lying in many mountain ranges, the most important of which are the Meniminee, Marquette, and Gogebic ranges in Michigan and the Vermillion and Mesabi ranges in Minnesota. The mines are from twenty to seventy-five miles from the shores of Lake Superior.

Then there is the ingenious, economic system of handling the ore. Eight lines of railway convey it to as many shipping ports on Lake Superior, where the ore is unloaded into twenty-six docks, having a total storage capacity of 1,326,616 tons. The total haulage capacity of these railways for one day is a quarter of a million tons. The record for this class of fast

work is held by the Duluth, Mesabi and Northern. The enormous supplies of ore in the region operated by these gigantic exploiters is worth note. Shipments began on a modest scale in 1885 from the Gogebic, in Wisconsin, and the Vermillion mines, in Minnesota, and the output from the latter alone to date has been twenty-eight million

tons. The most famous of these Lake Superior mines, however, are those of the Mesabi range, which extends for an unbroken distance of eighty miles and includes no less than eighty-six mines. The geological formation of the region is peculiarly favourable to mining, the grea: part of the ore bodies lying horizontally, and being covered by a shallow bed of

glacial drift. The ore all along this immense distance is rich, varying between 47 and 61 per cent, of pure iron, with en average throughout of probably 57 per cent. The first of the mines of this great range was opened in 1890, and in 1907 there had been taken out seven and 'twenty million tons of ore. It is estimated that the excavation done

to date is equal to that estimated for the whole of the Panama Canal. "With this enormous work there has been associated a corresponding inventive power, with the result that the huge tonnage is now moved in a minimum of time and for a minimum of cost. From first to last no human hand ever touches the ore from the moment the car enters the mine till the mineral is in the stock pile at the end of its journey. This stock pile is one of the great features of the system. It holds six months' supply of ore," and is designed for the winter months, during which the lake is not navigable, and the work <? O es on. nevertheless, at a rate that never stops for a moment. The trains of ore as they arrive are run out directly over long elevated docks, which are continuous rows of ore bins. The hinged bottoms of the cars are released on arrival in position, and the loads dropped into the ore pockets, where the ore remains until the steamers come alongside for loading. Hinged to the bottom of these pockets are long rows of metal chutes, and as a chute is lowered into position over the hatch of the steamer the gate at the bottom of the pocket is opened, and the ore slides into the ship's hold by gravitation. These overshipping piers can load six million tons of ore in a season ; they have loaded a boat of 5,700 tons in 30i/-> minutes, and another of 10,000 tons in 39min. One of the piers of the Northern Company is 73 feet above water level, is 62y 2 feet wide, nearly half a mile long, and storage capacity of 90,000 tons. From the mine in the west of Lake Superior to the southern Lake Erie port, ]000 miles off, the ore is taken and deposited on the stock pile at a cost of 1 dollar 80 cents, or seven and fourpence a ton. The iron ore steamer has been specially designed for this trade. Its chief object is economical loading, carriage, and unloading of iron ore in bulk. It is long and of shallow draught, in character is like a great elongated hopper, as seaworthy as she is commodious. Water ballast gives steadiness, and at the same time makes the hold of such a shape that the buckets of the cranes are of maximum efficiency. In our illustration of the " Wolvin" (one of these steamers), the elongated hopper is 43 feet at top, and 24 feet at bottom, extending for 400 feet of the length of the vessel, which is 560 feet long. 56 feet broad, and 32 feet deep. The tanks have a ballast capacity of 800 tons, the ship is stiffened by a system of arched girders supporting the hatch covers and the decks, and there are thirty-three hatches, each nine feet by 33. The biggest cargo ever carried by this boat was 11,800 tons, but since she has been at work vessels of a capacity of 14,000 tons have been built for the trade. In August, 1907, the traffic through the Lake canals was 487,000 tons in a single day, carried in 121 vessels. The total traffic of all kinds for that year was 52,280,000 tons, of which sixty-eight per cent, was contributed by iron ore. For the unloading of the steamers a special type of machinery has been designed and brought to great perfection. The best type is the Hulett Automatic Ore Unloader. Four of the same have been known to take over 7000 tons in 4% hours out of the "Wo;lvin." At Gary there are now five of these unloaders, and soon there will be ten. The plant consists of a massive walking beam with a pivoted vertical arm

carrying a bucket of ten tons capacity. It is constructed on the principle of a Priestman dredger, with wide, grasping jaws. As the bucket descends into the hold the two halves open horizontally like jaws and make a wild grab. The machines are carried on two tracks 62 feet apart, spanning two railway tracks laid parallel to the edge of the dock. They are operated by electricity, each weighs about 450 tons, and they require each three men to work them. The average capacity of each is 300 tons an hour. As each bucket load is lifted it delivers its load to a conveyer car, which when fuU, travels back to the rear of the machine and discharges into hoppers at the rear.