Crushing plant layout and ventilation system design for the Urad mine was based on our operating experience at similar crushing facilities located at the Climax operations. Low speed conveyors of generous width, adequate exhaust volumes at all ore transfer locations, large hoods and good conveyor skirting have made the Urad underground crusher dust control operations very satisfactory. Good maintenance and clean-up of the crusher facilities have made a clean working area with very low dust exposure.
The ore from the mine is dropped approximately 1000 feet through ore passes to scraping drifts above the crusher and then transferred to the coarse ore bin by 150 h.p. slusher hoists. A reciprocating plate feeder under the coarse ore bin feeds a 48 x 60 jaw crusher.
Belt speeds range from 200 to 350 ft/minute. Belts of generous width and slower operating speeds aid in keeping a clean atmosphere in the crushing area.
The crushing facilities are controlled from a central control room where the operator can observe several ore transfer locations by TV. The crushing plant operated by 3 men per shift, 2 shifts per day, has averaged 6000 TPD. The slusher hoists that feed the coarse ore bin are set up for remote control operations and may occasionally be operated from the central control room; however, the general practice has been to have an operator at the slusher.
Dust collection in the crushing plant is accomplished by two wet dust collectors with a total of 66,000 CFM. The dust collectors exhaust air is discharged to the upper ventilation system of the mine through an 800 ft. vertical raise and then through mine fans to the surface.
The screening area exhaust system has exhaust hoods with 1500 CFM each above the belts near each of the oversize and undersize ore chutes from the screens. The screens are covered and there are no exhaust hoods on top of the screens. Additional exhaust is from the bin above the screens and tail pulley areas. Total exhaust from this area is 36,000 CFM.
