The weekly Alaska citizen., 1917-11-19
TECHNICAL EQUIPMENT AMI PERSONNEL OF THE FAIR
 BANKS STATION.

Iu addition ty office l4FA4t4'r' books. and mineral collection. the .qupmyn, Tor thv Fairbanks S,aton includes ma.u.urllral and chem.- ,al l4borao.. The metanurslcM laboratory contains machinery and cqu.pmsn, with which fl wtII be DOS, 7lblv ,o make milling test, of prac- .ica.g every kui of mineral likely .o bp found ln Alaska
 For breaking the larger Jumps Of orr a cgusher of the rollinsjaw type Is used This hA, reinforced cast ron frame, mansauesesteel jaw plates. and bronze bearings The size oi the Jaw opening Is by 5 inches aHd The machine has ca pac.tl ot approximately ton and a half per hour when making a pro duct ono-haIi Inch in size. l. is de signed 10 crush the hardest rock and the produc, can be made as large as inches or as fine as one quarter inch, fl required
 After the material has passed through the jaw crushor it can be further reduced n a set of Downie- HalHdie open-type rolls II inches in diameter by l9 inches wide These will reduce the product as fine as 20 mesh Their capacity Is approxi- mately to tons per hour, depend ing upon the size of product desired
 For finer grinding Hardinge mill and a Marcy mill are provided. The Hardinge mill consists of two cast iron cones placed base 10 base with short cylindrical section feet in diameter and inches long be tween them. The Marcy mill is cast-irou cylinder 3 feet in diameter by ? feet long, lined with cast man ganese-steel In both ot these ma chimes the ore is fed in at one end with approximately an equal Quanti- Y of water, the ground pulp dis charging automatically and continu- ousl\ al the opposite end The mills are reyolyed and the grinding is ac- eompIished by the rolling and tum- bling action of about 1000 pounds Of steel cannon balls, some as large as inches in diameter. contained within the machines These mills can b. adjusted to grind the ore 10 the size Of flour if desired or by changing the quantity of the ore fed tha product can be made as coarse as 2o-mesh, approximately the size os table salt .The capacities of these machines vary, of course, with the size of the product required. but arD roughly ton per hour.
 The pulp discharged from these machines passes to d Dorr CIassifier which returns 10 the grinding mills any ore that k not ground sufficient F fine. This machine is a rectangu- lar steel box with a sloping bottom and has set of rakes-or hoes which slowly drag the settled Iarg- CT particles upward and deliver them back to the grinding mills. while the finished product oyerflows at the lower end of the cIassifier and IS piped to Pinch Krogh, solid lined centrifugal pump for delivery to any portion of the plant desired.
 For testing free-miIing ores there IS stamp mill having two 250-lb. stamps and silVered copper anal gamating plate IS inches wide and 6 feet long. Screens of different sizes can be placed on the stamp battery and amalgamation tests made on the same ore at different degrees of fineness if desired. Amalgamation plates can be placed inside the stamp mortar if this is found advisable for the ore under treatmnet.
 Screening of the ore in the larger lots will be done on a Colorado I'm pact Screen rect square, for which a number of interchangeable screens of different sizes have been provided For smaller lots a number of hand sleyes or riddles will be used in sizes varying from one-half to 20 mesh For finer sizes a set of test ing sieves with United States stan dard screen sizes is available; and an automatic machine for shaking and tapping the screens in order to assist the finer material to pass through the openings is also includ ed in the screening equipment.
 Two jigs have been provided, one of the regulation Harz- -plunger type having two compartments with screens 10 by 10 inches. This jig is Of the type commonly used on heavi- CT SulDhide ores hut i+ can he uti-