IM 2016 August 2016 | Page 85

HOISTING TECHNOLOGY it to address the increase in large hoisting projects and provide greater scheduling agility to support the needs of more demanding mining customers emerging from the prolonged industry slump.
In Australia, MCA Engineering offers high quality mine shaft hoisting equipment for sale and hire“ to work with mining companies in minimising initial infrastructure spend on costly construction.” MCA told IM it delivers this equipment to the market“ coupled with guarantees around its safety and quality to ensure the job is done right.”
Included in this system is a 24 m construction headframe – MCA has developed this frame to provide access to new and existing shafts for the purpose of ground support or shaft maintenance allowing access to a depth of 1,200 m.
The company also offers the MCA 1200 Class Winder, it says“ the latest in innovation in rope winding equipment for the mining industry.” Designed and manufactured in accordance with relevant Australian Standards and Guidelines, the MCA 1200 Class Winder’ s compact design provides a small footprint for installation,“ while its hydraulic drive offers exceptional performance. The 1200 Class Winder’ s design allows unprecedented fine control with large rope loads.”
The design includes grooved shells RHLL to 36 mm interchangeable rope sizes; bolt on brake discs( 2,000 mm diameter); spring applied hydraulic release brake calipers( 200 % capacity each path); a dual redundant brake return poppet valve system; a planetary drive reducing footprint but with increased torque and control; and integrated shaft to winder communication MDG 2005.
MCA recently won a shaft refurbishment project with Glendora’ s CSA mine in Cobar, New South Wales to provide shaft services to equip their No 1 shaft to a depth of 1,000 m. The project requires an MCA 24 m construction head frame, two MCA 1200 Class Winders( Sil 2 control), a working stage and cage for men and materials. The cage is delivering 4 m x 9 m DN150 pipes in a pack to the stage, which is equipped with a
hydraulic crane that will lift the service elements into place against the shaft wall. it is anticipated MCA will install 108 m of pipe per shift. The equipment will also be used to install a new loading station in modules from the surface speeding up the construction underground, and can lower components 1,200 m with a weight of 48 t if necessary. This system is also suitable for shaft sinking.
In the Elko gold mine application, the braking speed is low at 500 rpm, but the stopping time required is between three and five seconds, meaning that the peak disc temperature and power dissipation during the stop are high.“ Our selection is based on providing enough braking torque to deal with the static out-of-balance load, in addition to considering the dynamic stopping duty,” explains Powell.“ Modern control systems
offer lower hoisting cycle times and high
Rapid stopping brakes for Nevada hoist
Twiflex, a member of the Altra Industrial Motion Group, a leading global supplier of power transmission components, has provided a parking and emergency brake for use on hoists at a gold mine in Elko County, Nevada. The VCSD-VR brakes are installed on a motor pinion, operating on a 1.168 m diameter disc to produce a total torque of 128 kNm. The Twiflex VCSD- VR is a spring-applied, hydraulically-released disc brake which has been designed for use in harsh environments, while providing superior performance in heavy duty dynamic and emergency stopping applications. According to Steve Powell, Product Manager for Twiflex, when selecting brakes for
production levels, all of which affect the brake selection.”
The VCSD-VR is a large pad( 28,990 mm 2 each pad) version of the popular Twiflex VCSD( 15,700 mm 2 each pad); both brakes producing a braking force between 11 kN and 60 kN. Due to its increased braking path, the large pad version enables higher rubbing speeds and greater thermal capacity( the ability to absorb and dissipate heat) to be achieved. In addition to testing the braking torque at the start of each shift, hoist operators carry out visual checks of the calipers and condition of the disc surface. To assist with maintenance, Twiflex brakes incorporate a monitoring system to signal brake-pad wear and loss of braking force. Twiflex says it is continually investigating new materials to meet the demands of the mining market and has
mine hoists, it is important to consider factors
The Twiflex VCSD-VR is a spring-applied, hydraulically-released disc brake which has been designed for use in harsh environments
invested in modern test equipment at its UK plant in
Bedford. The company can
such as the depth of the shaft, stopping profile, drum design and payload in order to calculate the braking torque required for each application. For mine hoists, Twiflex typically aims to provide a braking solution which offers over two million braking cycles to meet exacting industry requirements. Twiflex’ s VMS brake range for hoists produces up to 460 kN braking force at a nominal 0.4 coefficient of friction and 2 mm air gap( distance between pad and disc face).
provide full testing capability including a climatic chamber(-75 ° C to + 180 ° C), a fatigue room for brake cycling and a fully automated 40 kW stop / start inertia rig for dynamic stopping.
“ All Twiflex modular brakes are subject to a cycling test and pressure test before leaving the factory. For mine hoists, all critical brake components undergo non-destructive testing. The main limitation for brake manufacturers is the friction material and the brake pad swept
area, which needs to be carefully selected for the
The MCA 1200 Class Winder
operating cycle.”
A unique Twiflex feature, which helps to
reduce maintenance costs and contributes to
risk mitigation on-site, is the‘ Parked Off’ design
which is included on all Twiflex modular brakes.
Unlike conventional mechanical lock-out
systems where a nut and centre bolt
arrangement is used to hold the spring force and
prevent the brake from closing during
maintenance, the‘ Parked Off’ feature actively
removes the spring force, meaning when
hydraulic pressure is removed there is no force
acting on the pad and therefore no possibility of
an unexpected closure. IM
AUGUST 2016 | International Mining 83