HOISTS AND WINDERS
Koepe type 4-rope hoisting machine with direct AC synchronous drive at KGHM ' s Rudna mine supplied by MWM Elektro
Confidence in conveyance
The fundamentals of hoisting have not changed since the early days of large-scale underground mining – but the control systems , efficiency , safety and level of automation have advanced beyond recognition – Paul Moore looks at some recent developments
New solutions for improving operational safety and sustainability within the mine shaft have been developed that are really making a difference in the hoisting industry . FLSmidth , whose hoisting division is FLS Mine Shaft Systems based in Orillia , Ontario , has introduced three new solutions in recent years : the patented Cage Guardian™ Safety Brake for steel guides , the skip Crank Type Dump Mechanism ( CTDM ) and a new onboard conveyance battery charging system .
For decades , many North American mine shafts have operated using wood guides for cages transporting personnel when hoisted via a drum hoist with a single head rope attached to the conveyance . “ Safety in transporting personnel in a vertical mine shaft is imperative , and redundancies are set in place to ensure safety requirements are met ,” said Matt Goddard , Head of Mine Shaft Systems at FLS . Wood guides , being a natural product , have many disadvantages over the use of engineered steel guides . Not only is their use having an environmental impact on forests and becoming increasingly less cost effective , but their variability in natural properties also make them less desirable and unpredictable for control . FLS has successfully developed , tested and proven to meet the most stringent regulations a new mechanical safety device which functions on steel guides , which would typically not require guide replacement in the case an event should occur . “ The advantages on operating with engineered steel guides are numerous . The Cage Guardian uses traditional spring-actuated mechanical activation to effectively clamp onto the guide while an independent braking system mounted to the cage dissipates the kinetic energy to stop and hold the cage ,” Goddard
added . “ The latest tests verify performance for the Cage Guardian for large four-guide cages with synchronised actuation , a cage load of up to 28,500 kg ( 70 kN / guide ) and a hoist speed of 7 m / s , effectively capturing the largest range of cage size normal for single-rope conveyances .”
The new and innovative Crank Type Dump Mechanism is a unique skip discharging mechanism designed by FLS which can increase hoisting capacity through reduced cycle times vs conventional scroll-type discharge . “ Reduced overall cycle time leads to increased production rates of as much as 8-10 % ( or more ),” said Goddard . Furthermore , the CTDM improves simplicity in design and lowered energy consumption over the alternative hydraulicallyoperated dumping mechanisms to dynamically open and close the skip in a short burst of
The FLS patented Cage Guardian™ Safety Brake for steel guides energy , realising only a single open / close cycle through each complete skip cycle . “ Hydraulically controlled systems are continuously energised and operated on ‘ standby ’ for most of the time while actually providing any useful output less than 10 % of the time ,” Goddard explained .” By switching to a simple electro-mechanical drive , the system complexity is also reduced and the requirements for fire suppression are eliminated .”
Finally , mine conveyances commonly carry personnel , whether for the regular transport of persons to perform work underground or for conducting inspections and maintenance within the shaft itself . Onboard communications systems are frequently used but require onboard batteries as a power source . It ’ s quite common for operators to have to remove spent batteries for re-charging at the end of every shift and replacing them with replenished batteries .
Now , FLSmidth has designed a new onboard battery charging system which uses the kinetic energy of the hoisted conveyance during each cycle to continuously charge the batteries while the conveyance is being hoisted . This not only simplifies maintenance requirements but uses inherent energy through hoisting instead of relying on external energy sources to recharge batteries . “ The elimination of having to lift heavy batteries from an internal compartment commonly in the roof of the conveyance also eliminates risk of injury ,” Goddard said . “ The new system is compact and easy to mount using FLSmidth ’ s own heavy-duty guide rollers and is an efficient and effective way to replenish battery charge .”
In the market itself , FLS has won a major order to supply a 6 m dual-drum , dual-clutch rock lift for a copper mine in South America . It says the incorporation of proven FLS technology will enable the mine to meet its goals of extending its operational life by an additional 30 years . The design uses cages with a capacity of 20 t to achieve a production of 379 t per hour . The scope of the order includes FLS ' s complete supply of mechanical , electrical and control systems , complete field installation and commissioning supervision , as well as strategic spare parts . This is another example of FLS ’ s ability to contribute to customer sustainability .
Tophat profiles
British Steel ’ s Special Profiles business is based in the north of England , UK , and manufactures high-quality steel profiles for a wide range of demanding industrial sectors . One of those is the mining industry where the company ’ s tophat
AUGUST 2023 | International Mining 29