Mining and Manufacturing Chateaugay Products

              The main entrance to the mine is through an 8 ft. x 24 ft., 63 degree
         incline shaft, sunk, mostly in the footwall, to a depth of 1,685 feet, the vein
         being tapped from the shaft at suitable intervals, varying from 150 to 300 feet.
 
              Levels, or drifts, 8 ft. x 12 ft., are driven east and west of the shaft, on
         the strike of the vein.  The drifts are driven on a rising grade of 3/4 of 1 per
         cent in order to facilitate drainage and favor transportation, the loaded cars
         traveling on the down-grade.  As the drifts advance, a permanent 36" gauge
         track is laid, with 40 lb. steel rail, on good, sound, wooden ties, spaced 30"
         apart, ballasted with iron ore, or rock, whichever the drift might be driven
         through.
 
                Wherever the vein is steep enough, which it is in most places, raises
         5 ft. x 8 ft., spaced on 30 foot centers, are driven up into the ore above the
         drift, from which stopes are started, for mining the ore for production.  Chutes,
         usually made of 3 inch hardwood plank and timber, are installed in the bottom
         of the raises, through which the ore, after it has been broken, is loaded into the
         tram cars.  At each end of a stope, a manway raise, 6 ft. x 8 ft., is driven
         through to the level above for ventilation, pipe and ladderways, and to afford
         entrance to the stopes.
 
              There are three kinds of stoping methods used in winning the ore:
         shrinkage, underhand and scraper.
 
              The shrinkage method consists of drilling up into the ore, blasting it
         down, and drawing only enough ore out of the stope each day to leave space for
         the men to work, completing a daily cycle, which is continued until the stope is
         advanced to within 30 feet of the level above, during which time about 40 per
         cent of the ore broken is drawn out daily, and 60 per cent left in.  Thus, when
         the stope is completed, it is full of broken ore which can be drawn out at will.

             The underhand method consists of drilling down into the ore, and
         blasting it from sublevels which have been driven across the stope at 50 foot
         intervals, connecting both manway raises.  As the ore is broken, it falls by
         gravity to the loading chutes below, and can all be drawn out immediately.
 
              The scraper method is used in places where the vein is not steep enough
         for the ore to run by gravity.  At convenient locations, a small, double drum,
         electrically driven hoist is installed, equipped with Ys " steel cables, to which is
         attached a steel scraper.  After the ore has been drilled and blasted, it is scraped
         along the floor to small ore pockets, from which it is loaded by gravity into the
         tram cars. 

    lyon-a36.jpg = fullsize
Drillers Joseph Kwetcian, Arthur Stewart, and Supervisor Dan Evans 

              The drilling of the ore is done by high powered, compressed air drilling
         machines of various types and sizes, depending upon the character of work to be
         performed.  Due to the extreme hardness and abrasiveness of the ore and rock,
         the drill steel used must be of the highest grade obtainable, and it is, therefore,
         made from Chateaugay iron.
 
              Because of the hardness and density of the ore and rock, it is necessary to
         use high explosives in all cases for blasting.
 
              Drill sharpening shops are located on each level for sharpening the drill
         steel, of which thousands of pieces are used and dulled daily.  The drillers,
         including those on development work, average 31 long tons drilled and blasted
         per man per 8-hour day.
 
              The transportation of the ore from the working places to the main
         hoisting shaft is accomplished by electric, storage battery locomotives, and steel,
         Granby type, side dump cars, each having a capacity of six long tons, and
         equipped with roller bearings.  The loading and tramming of each train is done
         by two men, averaging 55 long tons per man per day for the entire mine.
 
              After the ore is trammed to the main hoisting shaft, it is dumped into
         the ore pass which is connected to each level, and at the bottom of which is
         located a large 48" x 36" Jaw crusher for crushing the lumps of ore down to
         8 inches and smaller.  The material from the crusher is discharged by gravity
         into the skip loading bins, where it is loaded into the 8-ton skips, hoisted
         at the rate of 1,800 feet per minute, and dumped automatically into the bins
         above the secondary crushers in the headframe at the top of the shaft.

              The mine is splendidly ventilated in a rather unique and inexpensive
         way.  The openings from the old workings to the surface at the extreme
         westerly end of the mine are considerably higher than those on the easterly end.
         During the long, cold winter months, tremendous quantities of ice, hundreds of
         thousands of tons, accumulate in these workings, which cools the air sufficiently
         to cause large volumes to go down into the workings, forcing the smoke and
         gases out through the openings to the surface on the easterly end of the mine.
         The ice, of course, melts considerably during the summer months, but never
         entirely, enough fortunately remaining to insure ample ventilation of the mine
         at all times.
 
              The entire mine is so arranged that the water from all sections drains by
         gravity to points at, or near, the main hoisting shaft, from which it is pumped
         to the' surface by electrically driven pumps.  The quantity of water amounts to
         about 500 gallons per minute.  It is very pure, contains no acids, and is
         therefore not destructive to the pumping equipment.
 
              In many places in the mine, especially on the lower levels, a great deal
         of timbering must be done in order to support the back, or roof, of the main
         drifts, on account of the tendency of the ore and rock to spall and loosen.
 
              The mine, as developed and equipped at the present time, is capable of
         producing 2,000 long tons of ore per 8-hour day, averaging 15 long tons per
         man per 8-hour day for all underground workmen.
 
                             MILLING AND CONCENTRATING
 
              The purpose of milling and concentrating is to beneficiate the iron ore
         by separating and eliminating from it, insofar as is economically possible, all
         of the rock and other materials that might be associated with it when it comes
         from the mine.  The Chateaugay ore, as mined, contains 28 per cent iron.
         By milling and concentrating, the iron content is brought up to 69 per cent.
         Pure magnetite contains 72.4 per cent iron and 27.6 per cent oxygen.
 
              When the ore comes from the mine, it is 8" and smaller in size.  The
         fines, 2 1/2" and smaller, are screened out by a rotary grizzly, and the larger pieces
         crushed to 2 1/2" and smaller, by two 10" x 72" jaw crushers in the headhouse,
         at the top of the main hoisting shaft.  The ore is then conveyed, at the rate of
         250 tons per hour, by a 30" belt conveyor, to two 750 ton storage bins; from
         the bottom of which it is conveyed, at the rate of 250 tons per hour, by a 30"
         belt conveyor to the primary roll house, the first unit of the concentrating
         plant.
 
              The ore is now passed over vibrating screens with one inch square
         openings.  The portion which passes over the screens goes to two 36" pulley
         type, electro-magnetic separators which are set and regulated to discard all
         material containing less than 6 per cent iron.  This material is known as "coarse
         tailings," and is sent to the tailings pile.  The iron bearing material retained
         by the separators is discharged, by gravity, to a set of 20" x 72", plain faced,
         chrome steel rolls, and is ground to 1 1/2" and smaller.
 
              The material that passes through the screens, and which contains about
         4 per cent moisture, by weight, discharges by gravity into a 150 ton bin, from
         which it is elevated about 100 feet, vertically, by a belt and bucket type elevator,
         and discharged into the dryer.  The dryer is a steel stack, about 125 feet high,
         lined with fire brick, and equipped with cast iron baffles, the purpose of which is
         to retard the ore, as it falls down through the stack.  Hot gases, by which the
         ore is dried, are produced by a Coxe stoker, burning birdseye anthracite and
         located near the bottom of the dryer stack.
 
               The material as it comes from the dryer, thoroughly dry, is conveyed by
         a 24" steel conveyor and discharged, along with the material from the rolls, onto
         a 30" belt conveyor, and sent direct to the secondary roll house, the second
         unit of the concentrating plant.
 
               The material is now passed over double deck vibrating screens, having
         10 mesh openings on the bottom deck.  The portion that passes over the screens
         goes to four 36", pulley type, electro-magnetic separators, which are set and
         regulated to discard all material containing less than 6 per cent iron.  This
         material is known as medium size ore tailings, and is sent to the tailings pile.
         The material retained by the separators is discharged by gravity to three sets of
         24" x 54", plain faced, chrome steel rolls.  The material, after leaving the
         rolls, is returned, in closed circuit, to the screens at the top of the building.
 
               The material that passes through the screens is sent to a 30 foot, centri-
         fugal air separator for taking out all of the minus 100 mesh material, which is
         sent direct to the wet magnetic separators, in the concentrator house, the third
         and last unit of the concentrating plant.  The coarse material from the air
         separator, which is minus 10 mesh, and plus 100 mesh, is conveyed, by a 30"
         belt conveyor, direct to the bins over the dry, magnetic separators, in the con-
         centrator house.
 
               The minus 10 mesh, dry material now passes over 16-30", drum type,
         electro-magnetic separators, making a concentrate containing 69 per cent iron
         and better, and a tailing containing not more than 3 per cent iron.  The mid-
         dlings from these separators fall by gravity to 16 similar type separators
         directly below, which also make a concentrate containing 69 per cent iron and
         better, and a tailing containing not more than 3 per cent iron.  The middlings
         from these separators are returned to the bins at the top of the building in closed
         circuit.  The concentrates are sent to two 500-ton storage bins, at the top of
         the sintering plant and the tailings are sent to the tailings pile.
 
               Because the minus 100 mesh material cannot be efficiently separated on
         dry drum type magnetic separators, it is sent to 8 belt type wet magnetic separa-
         tors where, as it passes over the magnetic field, the tailings or gangue is thor-
         oughly washed out by a spray of water.  These separators make a 70 per cent
         iron concentrate, and a tailing containing not more than 2 per cent iron.  The
         concentrates are sent to the storage bins above the sintering plant.
 
               The ore tailings, or rock that has been separated from the ore, has
         become a very valuable by-product during the last ten years.  Each commercial
         size is stored separately in piles above a concrete tunnel, through which a 36"
         belt conveyor takes it to railroad cars for shipment to market.

              The concentrating plant has a capacity for treating, efficiently, 2,000
         long tons of ore in 8 hours as it 'comes from the mine, from which 800 long tons
         of concentrates, containing 69 per cent iron, are produced.
 
                                                 SINTERING
 
              The purpose of sintering is to improve the physical character of the
         concentrated ore by fusing the ore particles into a cellular mass, which makes it
         much more desirable for use in the blast furnaces, where most of it goes.
 
              Sintering is accomplished, at this plant, by means of a Dwight & Lloyd,
         continuous machine, 6 ft wide and 69 ft. long, comprised of a series of perfor-
         ated grates, known as pallets, which are mounted on wheels for traveling on a
         continuous track.
 
              The concentrated ore is first mixed with about 5 1/2 per cent by weight
         of anthracite.  The fuel is about the size of granulated sugar, very high
         in carbon, and low in ash, and is known as Anthrafine.  It is produced by the
         Hudson Coal Company, and is most desirable as a fuel for sintering purposes.
 
              As the fuel and the concentrated ore are being mixed, by means of a pug
         mill, a small amount of water is added as a temporary binder.  This mixture of
         ore and fuel is spread evenly on the pallets of the sintering machine, to a thick-
         ness of about 6 inches, and the fuel is immediately ignited as it passes under an
         oil heated ignition furnace, comprised of high temperature, refractory brick,
         and a retort, or combustion chamber, suspended by a steel and cast iron frame.
 
              Combustion is assisted by a downward current of air, drawn through
         the mixture, or bed, the entire length of the machine, by a large induced draft
         fan.
 
              The speed at which the machine travels is regulated so that, by the time
         the material reaches the discharge end, the fuel is entirely burned out and the
         process completed.  The sinter is then discharged over a set of stationary grizzly
         bars, spaced one inch apart, which take out the fines, allowing only the coarse
         material to go to the railroad car for shipment.  The fines are returned, by
         means of an inclined belt conveyor, and are mixed with the incoming feed to
         the sintering machine.
 
              The plant has an output capacity of 50 long tons of sintered ore per
         hour, and can be opearted, continuously and efficiently, 16 hours daily, (two
         8-hour shifts) or 24 hours daily, (three 8-hour shifts,) by suspending opera-
         tions one day each week for maintenance and repairs.

   Go to Mine History Page 5 ........                                        

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