1887 $4.644 1888 4.530 1889 4.480 1890 4.374 1891 4.170 1892 4.906 1893 3.375 1894 3.029 1895 2.786 1896 2.750 1897 2.520 1898 2.260
In connection with this table of smelting cost should be considered the changes developed during the interval 1887-1889, outlined as follows:
CONDITIONS OF SMELTING IN 1886 AND 1899 CONTRASTED TO SHOW THE PROGRESS OF DEVELOPMENT
────┬───────────────┬────────────┬───────────────┬─────────────┐ │AREA OF FURNACE│ HEIGHT OF │BLAST PRESSURE,│ FORE HEARTH │ │ AT TUYERES, │CHARGE FROM │ LB. PER │CAPACITY, CU.│ │ IN. │TUYERES, FT.│ SQ. IN. │ FT. │ ────┼───────────────┼────────────┼───────────────┼─────────────┤ 1886│ 30 × 100 │ 11 │ 1 │ 6 │ │ │ │ │ │ │ │ │ │ │ 1899│ 42 × 140 │ 16 │ 3 to 4 │ 128 │ │ │ │ │ │ ────┴───────────────┴────────────┴───────────────┴─────────────┘
────┬────────────┬────────┬───────────────┬───────────────┐ │ SLAG │ FUEL │ SLAG REMOVED, │MATTE REMOVED, │ │ SETTLED │ │ LB. PER TRIP │ LB. PER │ ────┼────────────┼────────┼───────────────┼───────────────┤ 1886│ │ │ │ TRIP │ │ In pots │Charcoal│ By hand │ By hand │ │ │ │ 280 │ 200 │ 1899│ │ │ │ │ │In furnaces │ Coke │ By locomotive │ By horse │ │ │ │ 3000-6000 │ 2000-3000 │ ────┴────────────┴────────┴───────────────┴───────────────┘
I believe that there is room for further improvement in the substitution of mechanical transportation within the works for hand labor, and that the fuel cost can be materially reduced by replacing the coke, which at present contains 16 to 22 per cent. of ash, by a fuel of purer and better quality.
_Cost of Refining by the Parkes Process._—In general it may be stated that the average cost of refining base bullion is from $3 to $5 a ton. This amount is based on the cost of labor, spelter, coal, coke, supplies, repairs and general expenses. When the additional items of interest, expressage, brokerage and treatment of by-products are considered, which go to make up the total refining cost, the amount may be stated approximately as $10 per ton of bullion treated.
Variations in the cost occur from time to time, and are due to several causes, principally the irregularity of the bullion supply and its consequent effect on the work of the plant. When the amount of bullion available for treatment is small, the plant cannot be run to its maximum capacity, and the cost per ton will naturally be increased. To illustrate this variation, the average cost per ton of base bullion refined during nine months in 1893 was: