GOLD PROCESSING
During the gold mine trial the operation was supplied two Derrick G-Vaults to be entered into operation based on a staggered timeline . The first screen slated for operation in Tank # 8 was run and evaluated side-by-side with the existing wedge-wire screen ’
non-blinding polyurethane screens in the early 1980s . Following initial contributions to advance gold processing technology , Derrick says it has continued to develop new , high-capacity screening equipment such as the Dual Pool ® 800 series screening machine .
It also recently introduced its latest innovation , Trilogy™ surface technology , which it says is its most advanced screen system .
“ Our screen solutions provide leaching circuits with technology that leads to efficient gold recovery and demonstrate our firm commitment to advancing gold processing technology ,” the company said . “ These solutions include trash screens , urethane interstage screens , carbon sizing screens , dewatering screens , tails safety screens , and other processing stages .”
Last year , Derrick Corporation announced the introduction of its new G-Vault ® polyurethane interstage screen for CIL / CIP and Resin in Leach / Resin in Pulp ( RIL / RIP ) processes at gold recovery plants .
The G-Vault Interstage screen is a direct bolt-in replacement for the existing wedge-wire screens but allows re-use of the operating mechanism , according to Derrick . The retrofit involves replacing the wedge-wire screen with the G-Vault screen and then lowering the module back into the tank . The G-Vault offers a significantly higher percent open area than wedge-wire screens – in some cases more than double . This higher open area combined with the abrasion resistant properties and non-blinding technology results in higher throughput , increased life and less maintenance .
Structurally , the G-Vault is comprised of several independent screen sections retained in a stainless-steel cage . The use of replaceable screen sections reduces maintenance costs by permitting replacement of only a heavily worn section , rather than an entire screen .
Through this solution-driven approach , mine management has been the benefactors of an excellent return on investment ( ROI ), Derrick said . The formula for this ROI is combining the wear resistance and non- blinding characteristics of Derrick ’ s polyurethane with accurate cutpoints ( ranging from 500-1,200 microns ) leading to reduced process interruptions and ultimately more stable conditions .
Following the initial commercial launch , Derrick decided to do something different and position metallurgists and operators at the helm of a new product ’ s on-site viability rather than on the tail end of accolades . This would be achieved through Derrick ’ s first ever , “ 60-Day Performance Trial ” a robust equipment trial program that focuses on the “ here and now ” of each site ’ s metrics , instead of a hypothetical set of perceived performance markers .
“ Our performance trial lets the equipment do the talking and make its own justification onsite ,” Jim Colgrove , SVP and Director of Business Development , said . “ Our Application Specialists have been working closely with the foremost authorities in metallurgy and mineral processing to create a tailor-made approach to this program and we ’ re excited to extend it through 2022 .”
Derrick ’ s 60-day program concentrates on a specific set of key performance indicators ( KPIs ) focused on reliability , maintenance and attributable cost savings , with each site
determining what the KPIs are .
For instance , in November of 2019 , Derrick commissioned a trial program where the main charge was to reduce the typical daily cleanings of the screens to de-bottleneck the CIL . The KPIs for this installation were : n No cleaning of the screening surface ; n Minimal wear , defined as no screening surfaces exceeding 1,000 microns ; n No flow loss in comparison with existing equipment ; and n No more than 5 % panel replacement .
The trial entered two G-Vaults into operation and tracked the performance . As a result , it was deemed a success half-way through the trial and measures were taken to outfit the entire CIL with G-Vaults .
Alex Nicosia , the Global Precious Metals Manager for Business Development at Derrick , and co-author of ‘ Interstage Screening Evolution , Retrofitting OceanaGold ’ s Haile Gold Mine ’ s CIL Interstage Screens with Urethane Screening Surfaces and the Increased Savings and Performance ’, said : “ Derrick loves when the odds are stacked against them . From a product development standpoint , it makes way for true innovation and industry change . This case was a true testament for our developers and design teams .”
Derrick is in the middle of an aggressive global rollout of this trial program and has seen a variance in KPIs stated by producers .
“ Considering the idiosyncrasies of each producer ’ s operation can make all the difference when determining success ,” Patrick Stasio , Derrick ’ s Eastern Hemisphere New Product Application ’ s Manager , said . “ What is important for one , may not be as important for another .”
In the case of the aforementioned trial , it has been noted that the G-Vault , allowing for higher flow , can “ self-prime ” as opposed to having to be removed , cleaned and reintroduced into the circuit . This attribute of operating G- Vaults has reduced cleaning times by 85 %. For instance , two operators who were previously assigned to cleaning a screen everyday have been reassigned to other parts of the plant and cleaning is performed on an as-needed basis .
Other operational efficiencies noted by the operators and metallurgy staff included significantly more efficient process load and separation ; an improvement in the overall health of the carbon in the system ; an increase in the amount of carbon being retained in the circuit ; and a reduction in the carbon lost to tailings . This was specifically realised in CIL Tank # 8 where the historical loss of carbon to tailings was substantial .
In addition to these process improvements , the general safety for operators improved .
The retrofit has considerably reduced the
30 International Mining | NOVEMBER / DECEMBER 2021