The Metallurgy of Silver, Gold, and Mercury in the United States, Volume 1

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J. Wiley & sons, 1887 - Amalgamacion - 558 pages
 

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Page 81 - Made of cast iron, its size is limited ; made of tank iron, there does not appear to be any reason why it should not be of double the size, except the uncertainty of being able to purchase the supply of lead to work continuously.
Page 146 - No. 3. This fusion for the treatment of tub residues takes place once a month, and lasts a week. All the plate slag produced during this operation is put directly back into the furnace. B. Roasting and Smelting the White Metal.
Page 123 - The pile is lighted at night, because the moisture in the fuel makes sulphureted hydrogen, which would annoy the men in the day-time. The fire, except in case of accident, burns until the roasting is complete. The sampler takes charge of the piles. He has little to do except to throw fine ore on the cover when he sees that there is too much flame. He has two or three assistants, and with them he does all the weighing and sampling, and takes care of the piles. When the pile is finished the outside...
Page 143 - The fireman keeps up the tire during the night, and the refiner takes it at 7 am, and then skims off the slag and exposes the surface of the bath. Considerable sulphurous acid is given off, probably from the reduction of the sulphate of iron in the cement copper. The charge is worked for a " set," which takes three to four hours.
Page 134 - J per cent, is left so as to be sure that no sulphate of silver is decomposed. This operation with the bar lasts one hour, so that at the end of four hours the charge is ready to be withdrawn. At the end of the third hour assays commence to be made, and samples are constantly taken until the end of the operation. The 'first assay generally shows that the sulphate of silver is free, but it is reduced almost instantly to a metallic state by the suboxide of copper present, and spangles are formed which...
Page 127 - ... as there are always grains of it in the slag, and the loss would be greater. The slag is carefully calculated, so that it shall not be too basic, or otherwise it would cut the fire-brick to get silica. The charge is evenly distributed over the surface of the hearth, which is almost at a cherry-red heat. It takes six men, working in groups of three at a time, nearly a quarter of an hour to make the charge. As soon as it is made, the charging door is built up and luted or closed with sand. The...
Page 145 - When there are no tellurium ores, the charge of gold ores of the first class is made to amount to 3,400 pounds. The treatment is exactly the same as before. A poor slag containing only two ounces of silver and a trace of gold is produced ; it is very much poorer than those of the previous fusion. It has otherwise very nearly the same composition as the others, but there is no zinc, either as blende or oxide, in it. The matte contains: — Copper 60 per cent. Gold 55 ounces. Silver 130 „ Sulphur...
Page 126 - ... with the chimney was constantly burning out, and needed frequent repairs. The immediate effect of the introduction of these holes in the roof was the saving of fuel and more equal distribution of heat. An opening has recently been made in the foot of the chimney for the introduction of cold air, and both...
Page 130 - The cold calcined ore from the cubs is thrown on to the crusher-floor, and shoveled into bins, from which it is carried by an endless chain to a hopper which communicates with, the charging-trough. The charge and balls revolve together at the rate of 37 revolutions per minute. The ore which is ground sufficiently fine, passes through the spaces between the bars and falls into the stationary cylinder, which is hopper-shaped at the bottom, and communicates with a trough, through which an endless chain...
Page 134 - ... scintillate and sparkle, forming a most beautiful reaction. To make the assay, a sample of the hot charge is simply thrown into cold water in a small dish. The heat of the ore is so great that the temperature of the water is raised to boiling. Whatever silver is in the state of sulphate is dissolved by the boiling water. If there is any suboxide of copper present, the spangle reaction takes place. At the end of the fourth hour the exposure of the surfaces to oxidation from the action of the bar...

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