File:Report of the State Mineralogist (1892) (14779513231).jpg

Identifier: reportofstatemin17cali (find matches)
Title: Report of the State Mineralogist
Year: 1892 (1890s)
Authors: California State Mining Bureau
Subjects: Mines and mineral resources Gold mines and mining Mineralogy
Publisher: Sacramento : California State Mining Bureau
Contributing Library: University of California, Davis Libraries
Digitizing Sponsor: University of California, Davis Libraries

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lver which might havecondensed in case of irregularities occurring in the furnace operation,the hot-treater dust is run into a settling tank before being dischargedto the dump. Following the last condensing chamber is a second Cot-irell precipitator (Photo No. 23), called the cold treater, to throwdown any remaining mercury mist in the fumes. It is stated that alittle quicksilver is obtained in this cold treater. The incoming electric 220 MINES AND MINERAL RESOURCES. current of 440 volts is transformed to 50,000 volts for the hot treaterand 100,000 volts for the cold treater. The fuel consumption of this furnace is stated to have proven ratherhigh, being approximately 8 gallons of oil per ton of ore treated, asagainst d~6 gallons per ton for a 50-ton Scott furnace. The installa-tion cost of the multiple-hearth type of furnace is much less than it iswith the Scott, being stated to be about $20,000 for a 100-ton plant, or$200 per ton-day capacity (1916; but for 1917 nearly double that).
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Photo No. 23. Cottrell Precipitator, or Cold Treater, at Senator Mine.Photo by W. W. Bradley. The cheapest operation of this type of furnace is obtained with thelarger units or with several units under a single roof, as a singlemachinist can attend to the mechanical features of several units. Torepair the rabble arms or other parts of the interior mechanism, thefurnace must be shut down and cooled off. This is apt to occur oftenerthan interior repairs are required in a Scott furnace, though Herre-schoff units have been in operation on copper ores for more than twoyears without such repairs. It is stated that an 82% recovery of theassay value of the feed was obtained with the Herreschoff furnace for SANTA CLARA COUNTY. 221 the 4 months ending with July, 1917.. The heads assayed approximately0.9% mercury, and contained from 3 to 5 tons, daily, of concentratesassaying up to 4%, which were mixed with the mine-run ore. As the furnace does not work economically on material coarser thanf, th

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