HEAP LEACHING & SX
The solution stack
Heap leach and SX operations continue to find favour in a market full of processing innovations , Dan Gleeson reports
Cementation Americas ’ Terra Nova Technologies was recently awarded a contract for the supply of two 1,829 mm wide by 76 m long Super Portable ® mobile stacking conveyors by a “ top tier ” mining customer for a large copper mine in the US
Miners must be an adaptable bunch to make money in this industry ; able to react to commodity price fluctuations , labour issues , incoming legislation , site restrictions and investor demands at the drop of a hat .
For those in the heap leach and solvent extraction ( SX ) industries , the change has been significant .
The industry pre-conceptions around heap leach operations have evolved : they are no longer considered a process for oxide-only material ; they can retain their efficacy for decades when properly maintained ; and recoveries can go up – as well as down .
Associations around SX operations have changed for the better , too , with developments showing off modular and accelerated processing options .
These changes have meant more operations are considering or prolonging the use of both processes as opposed to ripping up their existing flowsheets .
Stacking it up
One company to benefit from this trend has been Northern Ireland ’ s Telestack .
“ Heap leaching has experienced exponential growth over the last decade as mining companies seek to increase efficiencies in an increasingly limited supply of ores globally ,” the company commented . “ Mobile equipment provided by Telestack is an ideal option , offering flexibility coupled with custom-designed features without the large upfront costs or high running costs typically found in more traditional methods of heap leaching .”
Sary Arka Copper Processing in Kazakhstan recently commissioned a suite of customdesigned products from Telestack to use in a complete truck-receive , material transfer and heap leaching application for stacking copper ore .
In this application Sary Arka sought the expertise of Telestack to help achieve maximum production rates while keeping production costs low , the company said .
The two-stage installation comprised a Titan T800-6 tracked Truck Unloader , three TCL831 tracked conveyors , a HIC830 tracked Horizontal Index Conveyor and a TS850 tracked Radial Telescopic Stacker . These are used in heap leaching applications to stockpile copper ore at rates of up to 800 t / h .
Stage 1 of the application involves two independent Metso Outotec crushing plants working at 400 t / h . Each plant continuously feeds two lines of 40 t rigid trucks directly via a storage hopper , with each truck drawing the raw material from the crushing plant and reversing onto earth ramps to feed the Titan T800-6 Truck Unloader . This 800 t / h track-mounted unit can be relocated around the site and is fitted with a Cat C4.4 diesel engine , Telestack said .
The Telestack Truck Unloader was fitted with a heavy-duty apron chain belt feeder ( winterised to -30 ° C ), which ensures the surge of material discharging from the truck can be transferred in a regulated and controlled manner . The chain and sprocket driven apron belt ensures there is no
stalling or slipping of the feeder compared with regular “ roller-type ” belt feeders , Telestack said . The flared 6 mm abro-lined reception hopper provides the capability to accept abrasive material such as copper ore from trucks or loaders .
The steel apron bars can absorb the material surge and impact , and the flexible side-seal skirting and ventilated chassis allows any material to be released , protecting the chain and belt . The adjustable material levelling blade on the incline of the feeder helps control the flow of material before it transfers onto the 10 m heavy duty lattice incline .
Stage 2 of the application involves the copper ore being fed onto a series of three TCL831 trackmounted conveyors , which are used to keep the trucks off the heap leach pad to prevent damage to the neoprene layer . Each unit incorporates hydraulic adjustment at the rear and front of each unit to adjust transfer heights accordingly .
Each unit is 31 m long and capable of conveying 800 t / h-plus . To ensure the unit would be fully functional throughout the year , Telestack incorporated several features including winterised belting , winterised grease and bearings , low temperature hydraulic oil , heaters in hydraulic tanks , winterised seals on hydraulic rams and insulated control panels complete with thermostat-controlled heater .
The TCL831 conveyors transfer the copper ore onto a HIC830 track-mounted Horizontal Index Conveyor . This unit enables continuous feed to the stacking conveyor and minimises the amount
20 International Mining | NOVEMBER / DECEMBER 2021