OCR

drilling and blasting work to completion of area site preparation. Load and haul remained under Utah-Emkay direction, equipment used consisting of 2'1/2 CY P & H model 955 shovels and 15 CI Euclid Model 36TD rear-dump trucks. The first structural concrete in the concentrator building was poured January 22, 1955, and the final area concrete pour was made in July 1959. The initial steel in the fine ore bin section of the concentrator was erected in June 1958, and all area structural steel erection was complete in April 1959. The completed primary crusher installation was tested on July 10, 1959 using mine waste, and on July 20 all crushing and conveying facilities from the primary crusher through to the fine ore storage bins were placed in operation, furnishing a supply of bedding material for the milling and tailings equipment. The concentrator grinding bay was placed in operation August 5, 1959. Final transfer of all appurtenant mill and area shop facilities was accomplished prior to October 1, l959. Major items of included work quantities were as follows: 2,613,000 CY of excavation, 76,700 neat line CY of reinforced concrete, 6,616 tons of structural steel, and 77,650 CY of lean concrete backfill. Of academic interest is the following information concerning mill facilities: design capacity is 30,000 dry tons each 24 hours producing 1,130 dry tons of 33% copper concentrate per day for rail shipment to the smelter at Ilo. The 60" 'Traylor Type TC Bulldog gyratory primary crusher will handle 3,000 tons per hour to minus 8" discharge. Too two secondary and four tertiary crushers are respectively 7' Symons Standard Head and Short Head Heavy Duty Cone crushers. The grinding equipment of the concentrator comprises 7 each l0'-0" by 14' two-trunnion type Marcy open end rod mills, 14 each 10'-6" by 13' Allis-Chalmers overflow ball mills, and 7 each 8'-0" by 13' Marcy overflow regrind ball mills. Feeder conveyors from the fine ore bins will handle an aggregate total of 2,000