File:A supplement to Ures Dictionary of Arts, Manufactures, and Mines, - containing a clear exposition of their principles and practice. (1864) (14595192618).jpg

Identifier: supplementtoures00hunt (find matches)
Title: A supplement to Ures Dictionary of Arts, Manufactures, and Mines, : containing a clear exposition of their principles and practice.
Year: 1864 (1860s)
Authors: Hunt, Robert, 1807-1877
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Publisher: New York : Appleton and company
Contributing Library: University of California Libraries
Digitizing Sponsor: Internet Archive

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at once completely roasted, the whits from the stamps are sometimes first rag (orpartially) burnt, for al)out six or eight hours. The object of this partial burning is to save 746 METALLURGY. time and expense, nearly three-fourths of it being thrown away after dressing it from thefirst burning. Fig. 423. The machine called originally Bruntons Patent Calciner, for calcining tin 423
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ore, is gradually coming into use in Cornwall, ana is adopted in many of the larger mines.Its operation may be thus briefly described :—A revolving circular tabic, usually 8 feet, or10 feet in diameter, turned by a water-wheel, receives through the hopper the tin stuff tobe roasted or calcined. The frame of the table is made of cast-iron, with bands, or rings,of wrought iron, on which rests the fire-bricks composing the surface of the table. The flames from each of the two fireplaces pass over the ore as it lies on the table, which slowly revolves, at the rate of about once in every quarter of an hour. In the top of the dome, over the table, are fixed three cast-iron frames called the spider, from which depend nu-merous iron coulters, or teeth, which stir up the tin stuff, as it is carried round under them.The coulters on one of the arms of the spider are fixed obliquely, so as to turn the oredownwards from one to the other—the last one at the circumference of the table, project-ing

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