SCREENING
“ This is Kwatani ’ s largest order to date and is probably the largest single order for screens ever placed on a company in Africa ,” says Schoepflin . “ We are proud to have won such a prestigious bid in the face of intense competition , showing how our global reputation has been growing .”
The order is for large double-deck multi-slope screens , which feed high pressure grinding rolls ( HPGRs ), as well as for single-deck linear screens feeding concentrators . The screens in this order will installed on isolation frames to minimise the extent to which dynamic loads affect the plant ’ s building structures . Kwatani is well known for its design , manufacture and servicing of large , robust screens which are engineered for tonnage .
“ As the largest OEM for vibrating screens and feeders in Africa , we have had great success on the continent and abroad with our large ‘ banana ’ screens ,” he says . “ These and our other custom engineered screens have been supplied to over 50 countries to date .”
The stringent and lengthy technical adjudication for this project was conducted for the mine by two leading international project engineering houses . “ The size and value of the order ensured that all the mining industry ’ s foremost screen suppliers were enthusiastic participants in the bid . Other indicators of the order ’ s scale are that the screens will consume around 700 t of steel , and will altogether be fitted with 21,000 screening panels .”
Schoepflin notes that an important consideration for customers is not only the proven quality and performance of its screens , but Kwatani ’ s ability to deliver on time . “ Any large capital expenditure decision on a mine is taken with time-sensitive factors in mind ,” he says . “ For instance , the delayed delivery of critical equipment can prevent a mine from meeting its planned production targets . This undermines the financial basis for that decision – an eventuality that no mine can afford .”
The end-customer and the project houses therefore had to have full confidence in Kwatani ’ s capacity . With growing demand from a buoyant mining sector , the company recently added another 3,000 m 2 to its existing 17,000 m 2 facility in Spartan , Johannesburg . Its design and manufacturing capabilities are ISO 9001:2015 certified , ensuring that the latest order to Asia will comply with the highest global standards , he says .
“ We also pride ourselves on the quality and resilience of our supply chain , which underpins our ability to manufacture to demanding deadlines ,” he says . “ We carefully select our supply partners – most of whom are local enterprises – and collaborate closely with them to build their sustainability and responsiveness .”
To keep the project ’ s schedule on track , dedicated in-house project managers and procurement specialists meet regularly with supply partners to ensure a smooth and streamlined process . This has required perfect alignment of all local and global procurement , including motors , drives and steel . The company ’ s agility allowed contracts and prices to be tied down for timeous delivery , despite the global supply chain disruption that lingers from the COVID-19 lockdowns .
“ The scale of the mine ’ s operation indicates that screen efficiency , throughput and performance will be paramount ,” he says . “ We subject all our vibrating equipment to rigorous tests in our in-house testing facilities prior to dispatch .”
This , he explains , enables customers to achieve continuous tonnage while protecting its assets and reducing the total cost of ownership . Even before manufacturing stage , each design is subjected to Finite Element Analysis ( FEA ) as a standard procedure to verify engineering integrity . The screens will be delivered in batches to a South African port , and shipped as break bulk due to their size . Production of the screens is expected to be complete by early 2023 .
Weir Minerals ’ Enduron screens & water savings
Water supply pressures , particularly in arid areas , are one of the most critical issues currently facing the mining industry . There is both an ESG and financial imperatives for miners to use water as efficiently as possible . In many operations , this has been the catalyst for miners to adopt more adaptive strategies and embrace innovative technologies and more efficient processes .
The prospect of reusing and recycling process water is leading a growing number of operators to include Weir Minerals ’ Enduron ® dewatering screen in their flowsheets , Corné Kleyn , Weir Minerals Global Product Manager , told IM .
“ In addition to the environmental benefits associated with reusing process water , capturing fines also reduces energy consumption and associated handling costs . Moreover , the Enduron dewatering screen is also helping reduce many sites ’ environmental footprint by , in some cases , eliminating the need for settling ponds .”
The innovative Enduron dewatering screen has a 45 ° declined feed section and is fitted with slotted apertures across the direction of flow – this sloping deck acts like a vibratory sieve deck . Weir Minerals says its process and product experts work with the customer to ensure the incoming slurry is fed uniformly into this section . The partially dewatered slurry then moves along to the main deck , which is angled at up to 5 ° incline . Water runs down the inclined dewatering deck towards the feed section where it collects in a pool and drains through the apertures , while dewatered solid particles run up towards the discharge section and forms a dry cake . This cake then acts as a filtration bed , trapping finer particles .
The vibrating action conveys the cake up the screen and out of the pool where further dewatering takes place . The cake is finally discharged over the adjustable discharge weir into the product chute .
“ The Enduron dewatering screen can also be adjusted to cater to site-specific requirements . For instance , the speed of the motor can be changed . On the smaller screens , vibratory motors are employed , while the larger ones are driven by geared exciters ,” said Kleyn .
It ’ s also possible to change the angle of the slope to optimise screening . Similarly , by adjusting the discharge weir , it ’ s possible to build up the material bed ; the goal is to get it up to around 200 mm ( depending on the application data ), which is the level at which the screen operates most efficiently . This flexibility allows operators to adjust the machine in order to achieve the optimal operating conditions .
The Enduron dewatering screen can also operate with adjustable division plates . Essentially , these are Linatex ® lined barriers that can be mounted along the length of the screen to allow the operator to decrease the width of the screen . So , if there is a change in the circuit that alters the feed particle-size distribution ( PSD ), the operator can adjust the division pits to ensure the material bed remains at the optimal height .
These can also be adjusted to allow operators to perform multiple applications on the screen simultaneously . For example , you can insert division plates so the screen is divided into three distinct sections and , say , do typical fines dewatering down the centre channel , while the two side channels do sizing .
Vibramech rolls out Vibrasure
Now Southern Africa ’ s largest privately owned vibrating equipment manufacturer , Vibramech told IM that it is has achieved record sales in its 45th milestone year adding : “ The personal touch added by being owner-managed allows for greater flexibility in catering for its customers ’ unique requirements and considerably improves turn-around times in the design phase .”
Vibramech supplies its equipment to mining and mineral processing industries throughout Africa , Eurasia , Australasia , North and South America . The company has extensive experience in gold , diamond , coal , iron ore , manganese , platinum , chrome , nickel , uranium , copper , lithium , mineral sands and aggregate operations . It produces a proven and comprehensive range of vibrating equipment , including , but not limited
42 International Mining | OCTOBER 2022