The copper era., 1902-12-04
Profit From S2 Gold Ore.

Much has been NrlttSE SOhSS' i4H . the chances for profit in two-dollar gold ore, and the following notes show that one company at least is making money on that grade Of ore. This Is the great Treadwell Mining company, operating on Douglas Island, Alaska. The company is noted also for having the largest stamp mill In the world. Douglas island is separated from the mainland by Gastineau channel, which is opposite the mines, three-fourths of a mile in width and 200 to 300 feet in depth. The general coqrses,rs9s s,rssS r9iSIks Iks s.s ]. P .s.asnaIs i,- ,si.ont. t.-IIa : .sys lwall vein
 assis @ .odg ssd this t1hs ss65ass FoasSiy parallel to it. At the Treadwell mine the out crop of the vein is about 1000 feet
 back from the shore and about 300 feet above high tide. Here the vein was
 300 to 100 feet Tn width. It was mined
 by the open cut and pit system until
 recently, but TOW only about eae-eighth
 of the ore mined on Douglas island
 comes from surface pits. Some of the
 shafts and workings on the vein are
 now 100 or 300 feet beneath tidewater,
 but the workings, nevertheless, may
 be considered dry.
 The ore is broken by machine drills, each of which averages from thirty to sixty tons per day. The excavations in the vein are not timbered. but are l hn nf
 stoping continues. Only the ''swell'' of the ore, which amounts to about 30 per cent. of the total tonnage, is taken
 out while the stoping between any of
 the levels Is iu progress. The remain ing 70 per cent. which completely fills the stope and affords solid working floor for the miners, is drawn off through chutes after the stoping of
 the back of ore levels has been com- pleted.
 The walls of the exhausted areas of
 the vein are supported by vertical ribs
 and pillars Of ore left standing while
 the levels are preserved by the hori- zontal pillars left over and under them. The horizontal pillar left on the tram
 ming level is 10 to 15 feet thick, and
 through this pillar chutes are opened
 at convenient interyss..,,s ss,,, Through
 hers used are the mouthpieces of the
 chutes and the posts supporting them.
 Two-ton sram cars are used in the
 mine. a-ld these are loaded at the
 chu-s and made into trains which are ,auled by horses on the endless rope system to the forage bins at the shaft A horse hauls 8 train of six cars. while d twenty-car train is hauled by the rope system. The shafts, with one ex- ceptlon, are vertical, and the hoisting Is done by self dumping skips.
 Two large Gates crushers are install ed at each shaft, which break the ores Is 1t dumps from the skips into sizes suitable for the stamp batteries. | When so crushed the ore falls into forage bins, from which it is hauled y tra inloads with locomotives to the tamp mills. Five thousand tons is hus delivered daily to the mills. of 'hlch 3,OOO tons come from the Tread 7ell mine, the balance being produced the three adjoining properties un- CT the same management. The pro- uction is reduced during the dry or inter season. The gold is free-milling and concen- 'ating, carrying the gold free in the , lartz and combined in the iron 'rltes, of which there is about 9 Der mt. in the ore. The stamp mills ara
 various sizes, the two largest con- r ming 300 and 240 stamps respective I . For each five stamps there are II 70 slx'foot Frue vanners. The stamp IL ty is five tons of ore crushed rough slot screens equivalent to 24 gc ssh. The stamp drop is s inches. 100 re nes per minute. The tailings are W Umwd auUei so run T1s (the Gastineau The concentrates, which are pro- 1 ced at the rate of 100 tons daily. are n uled on barges to the Tacoma elter, where they are treated at 1t of about SS per ton for freight and atment. The returning baroes ng coal from the Vancouver island 1es. Tn he ore is low grade-very low grade only about s2 Der ton .. average costs of treatment Der
 of crude ore are as follows: 5ss ing expenses. which includes all de-
 ' A- '---'--, ..-----.--...S .SiOO ing expense. which includes concen- E ting g...-......-.... ~ ght and treatment On concentrates 1tas
 Total operating expenses .......... ST .2o5s
 eohs'rueuon --'.'.---- -.---.-...-... O775
 Dfand total -..---..- .-.--..-.--. .sl2s2s 'foh' 'appro1imateisl--'.. -..-.......s .7I71