Bisbee daily review., 1908-05-10

| George l.. Walker, author H Walk
 CTS Weekly Copper Letter. in the l General Electric Review. for May
 published by the General Electric
 Company's Publication Bureau. al
 Schenectady. N. Y.
 The cost of producing copper de bends chiefly upon the richness oi the ore and the size of the ore oe' posits: but much depends also on the character of the naturalization and minerals which are associated with the copper Copper ores which do not yield readily to known meth ods of reduction are called refractory. The most refractory ores are those in which the coppers occurs as oxides and carbonates in a highly sihcious gangue; and those ores in which the copper occurs in any of its various mineral forms associated with zinc, nickel. antimony or arsenic are also difficult to smelt and refine.
 1 All Ores Can Be Treated. The theory that there are some ! considerable deposits of high graae ores which cannot be smelted or treated proftably, and the belief that large masses q native copper exist which cannot be cut up. are both un- 1 founded. All of the large masses of copper ever found were cut up and marketed very profitably. Modern metallurgiSts can treat any ore m ex- istence at a good profit, provided it is rich and exists in sufficient quant- ities to warrant the construction O. lagre plants.
 As a result of my personal inspec- 1 tion of practically all the producing i copper mines in the United States and Canada, and the largest one in | Mexico, have come to believe that necessity helps to develop an eco nomical management and attain low | production costs. The management of mine in which there is an abund- ance of rich ore is always prone to overlook many of the small opportun- ities for economy of operation; but the manager who Is forced to con- tfnue development work tirelessly in order to keep 8 mill running on a very poor grade of ore, and from 1t win profits, is pretty sure to give careful attention to every known method of economy and use every one of them to its best possible advant- age Human nature asserts itself in mining as in all other pursuits, and
 
 necessity and invention is never sev- cred.
 Large Deposits, Best Results. In copper mining the best results are practically always obtained from grade ore. To illustrate, in the Co bait silver district 1t costs S60 to S150 per ton to mine ore from veins | xlyh nh wide; while the British Columbia cop per camp ore is extracted from a lode 300 feet thick, trammed half a mile and loaded on railroad cars at a cost of S1.02 per ton.
 Of course it is not practical to set up heavy modern mechanical equip. ment, hoists, electric tramways, etc, to mine a small ore body. The mar rower the vein and the more bunchy the deposit, the greater relatively is the amount of dead work which must be done to mine a given tonnage of ore; hence the cost per ton increases with the narrowness of the vein. Those who know little or nothing of copper mining will be interested in brief summary of the methods by which the red metal is won from
 
 districts.
 Different Methods of Production.
 At Lake Superior native (pureD cop per occurs disseminated, chiefly in small particles, throughout porous called amygdaloid About 120,000,- 000 pounds is produced there annually from this rock which yields an aver DH oA If fSpn to the ton, giving the rock a gross value of only s2.50 on a 15-cent copper market The total average cost of handling this rock, however, is only about s1.S0, which means a produc- tion cost of 10 cents per pound. This does not include the Calumet & Hecla which produces from S5,000.000 to 90, 100000 pounds annually from a conglomerate rock which yields about 40 pounds to the ton at a cost of about g cents per pound. The Tama- rack and Franklin produce 15,000, ,000 to 20,000.000 pounds annually from lower grade conglomerate rock at a higher cost.
 At a cost of IS to 25 cents per ton Lake Superior rock is milled and con centrated, 40 to 80 tons into one. and the mineral. or native copper, Is re- fined by simple smelting or melting process and put into the various shapes ready to be drawn into wire Or rolled into sheets. It commands a higher price in the markets of the world than any other copper. Nat ural conditions are such that the simplest processes in use anywac7e in the world can be employed.
 At Butte, Montana, the leading cop per producing district of the world. the copper ores, chiefly chalcocite and enargite, occur in big Assure veins ih a granite formation. The disposition of the wall rock to cave, necessitating the use of a great deal of strong tim Der and the refilling of stopes, makes the mining cost high.
 The ores are transported a consid- erable distance, the lower grade con centrated in big mills and the higher grade smelted direct A portion of the ores have to be roasted to expel the excess sulphur before smeltins. The arsenic is precipitated to prevent injury to vegetation and. incidentally. 1t is refined and sold, yielding a fair manufacturing profit.
 The matte, the first smelter prod uct, is converted into bullion, about 99 per cent fine. Then the copper is