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positions Henderson to compete in the contin- uing difficult world-wide molybdrnum mazkets of the 1990s. Molybdenum is a metallic elemen[ used in steel making and the past 12 yeazs have not been kind [o steel nor molybdenum. In 1979, the year the mill reached design capacity, the price of molybdenum was about $10 per pound Molybdenum prices fell N the 198Us and now are at a 17-year low of just over $2 per pound. Henderson hlstor}• The Henderson Mine and Mill facilities are located on the east and west flanks of [he Con- tinental Divide about 80 km (50 miles) west of Denver, CO. The undcrground mine and surface mill sites are linked by 16 km (10 mile) of railroad tunnel and 8 km (5 mile) of sur- facetrackage. The mine, railroad and mill were built betwern 1968 and 1976 a[ a cos[ of $500 million. Each has operated at various levels of production over the past 15 years. The Hrnderson Mine was originally developed using a highly mechanized, panel caving mining system. Over the past ]0 years, mining methods, equipment and railroad oper- ations have been improved to position Henderson as one of the post productive and lowest cost underground mining operations. At the same time, the mill and concentrator facilities were upgraded to reduce costs and improve produc[ quality. Dur- ing this time, manpower was reduced from 2000 to 520 employees. These 520 people increased productivity to 54 t (60 st) per total manshift. They reduced operating costs by 50%. And they dramatically improved safety performance. New mining level The ore body is a massive, complex inmuive molybdenite stockwark that originally contained 272 Mt (300 million st) of ore reserves. The mine was designed for multi-level pro- ducdon The fast 91 M[ (100 million st) were mined hom the 8100 level. An additional 109 Mt (120 million st) will be mined over the next 15 years from the newly developed 7700 level. The remaining ore reserves will be mined on a fume lower level. Preproduction development of the 7700 level requires mining 22,860 m (75,000 ft) of 3.6- z 3.6-m (12- x 12-.ft) drifts and ramps, 610 m (2000 ft) of raises and ore passes acrd ] 50 drawpoints. Also, 48,139 ma (1.7 million cu ft) of metutg was needed for shaft sta[ions, shop maintenance bays attd other rock excavations. This large peproduction development mining pro- gram was completed in 1991 on schedule a[ a cost of $25 million. The layout and design of the 77001eve1 are keyed to a detailed unders[anding of static and dynamic geome- chanics gained from the 8100 level mining experi- ences, 7700 level geologic studies and state-of-the-art computer analyses. The progression of the caving ac[ion will be computer monitored with borehole cables and shear strips. raitroatl has productivit have 30 18~ s[) electric 1 ing 36 kVd track, 48 improvemt toward soli allow fully MIII mode The Hen also benefi modemizat and improv 4.2-m (28- mills have been fitted wii with larger 133-mm (5.25- life by 20%. Mill feeds &o are controlled by optical s power, mill load and grind power reduction. A join[ v ~'~.- Mlne modernlzatlon Henderson Idlll is Inratwd nwar Ute Pass in An ongoing, $10 milhon modem'vation program to funtt:r improve the mine's productivity and reduce operating costs includes the replacement of aging equipment with larg•~ capacity, technologically advanced underground mining equipment. The introduction of larger capacity 5.7 mr (7.5 cu y~i) production LHD's has increased drawpoint loading per duclivity by 70%. Semiautomatic, electrohydreulic drilling equipment has increased emcirncy by 50% :o 90% while improving drilling accuracy and reducing drilling supply and power costs. Electrohydraulic rock bolting equipment allows t}ie safe installation of friction or resin bolts with a 60'Yo enprovements in bolting rates. Remote controled borne wcks apply wet shotcrete at more than [wice the his- roric productivity. Tmck-mounted booms vanspon, s;t and remove concrete drift forms in one-third the time required for manual setting. Although much of the mine modernization has focused on mining equipment, microcomputer systrnts have been introduced to monitor and control mine hoe t- ing, vrntilation, concrete botching and electrical pow;r use. The microcomputer-based power management sys- tem provides real time load shedding to mudmize pet~C in a total plant demand wit titre in electrical demand. The concentrator clew reconfigured wish 14 stag regrinding. This allows hi, ous production of three gr. centra[es. Although plant modifit an imponant factor in the i lotion of mill and concentr titre is providing the key t Oastream, X-ray analysis real time perfomtance mea control of process paramet performance. Future mill and concen [he consolidation of grin reagent control to further with expanded plant auto Summary The modemization of 0 centrator has established tt primary molybdenum pro mill operations and a dec J..~~:..: ~.. ~.. CA ~ /Ln . The Henderson Mill recently processed its 100 millionth ton.