Bulletin . .5% mercury. By thus eliminating the veryfine material from the ore which has a tendency to interfere with the furnace draughtand to hold back the volatilization of the quicksilver, the capacity of the Scott furnacehas been raised to about 75 tons daily. On account of the large percentage of finescoming from the mine, some of this ore was being added to the coarse-ore furnacecharge. Naturally this interfered in a more marked degree with the capacities of thetwo coarse-ore furnaces than the extreme fines did with the Scott. The eliminationof practically 32 tons daily of the extreme f
Bulletin . .5% mercury. By thus eliminating the veryfine material from the ore which has a tendency to interfere with the furnace draughtand to hold back the volatilization of the quicksilver, the capacity of the Scott furnacehas been raised to about 75 tons daily. On account of the large percentage of finescoming from the mine, some of this ore was being added to the coarse-ore furnacecharge. Naturally this interfered in a more marked degree with the capacities of thetwo coarse-ore furnaces than the extreme fines did with the Scott. The eliminationof practically 32 tons daily of the extreme fines by concentration has thus relievedthe No. 2 and No. 3 furnaces of fine ore, giving them also, freer action and increasedcapacity. The concentrates after drying are charged with ore to the Scott furnace. -*Oj9. cit., p. 499.^See p. 305, ante. ^•Bradlev, W. W., et al. Mines and mineral res. of Monterey et al. counties;Chapters of State Mineralogists report, 1915-1916, Cal. State Min. Bur., p. 73, QUICKSILVER RESOURCES. 341 Since the above was written, the phmt and practice at New Idriahave been improved and expanded materially. The accompanyingflow-sheet (see Plate XLII) indicates the part that concentration is atpresent playing at this the largest producing quicksilver mine in theWestern Hemisphere. The drawing gives the flow-sheet, as of May,1917. Though there have been some changes of details, since, this willgive a good, general idea of the New Idria practice, quite is stated that before the ball-mill was added, a New Standard tablehandling screened 8-mesh fines from the- San Carlos only, showed lessslimed cinnabar in the tailings than since. The underground work-ings of this company are divided into two groups; designated the NewIdria, and the San Carlos, respectively. The reduction plant is sta-tioned at the former (see Photo No. 21, ante), while the latter is con-nected with it by an aerial tram 2 miles in length. Two-thirds of thegrizzly (1) fine
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