SCREENING TECHNOLOGY installation will add 10 Mt / y of high-grade Fe ( Direct Reduction ) pellet feed with a significant reduction in production costs to the Carajás complex . The start-up is expected to be in the second half of 2021 .
Vale currently operates over 170 Derrick Stack Sizer ® machines in six of their Brazilian iron ore concentration plants . “ Derrick ’ s SuperStack offers advantages of economies of scale and helped to prompt Vale in making the decision to adopt this new technology .”
Derrick has also announced that 12 Derrick Stack Sizer fine screens are being used to produce premium concentrate with 70.5 % iron content at the Central Iron Ore Enrichment Works ( CGOK ) of Metinvest Group , Ukraine . The CGOK production line was upgraded to incorporate fine screens in the spring of 2019 . The fully upgraded concentrator is now capable of producing highgrade pellet for Direct Reduction of Iron ( DRI ) technology .
Derrick screens have been successfully used in iron ore since the 1950s processing all types of iron ore , from removing fine impurities in Direct Shipping Ore sinter products to scalping relatively coarse (+ 45 to 75 μm ) middlings and size control in pellet concentrates . “ Some of the greatest benefits of fine screening have been achieved by replacing hydrocyclones in grinding circuits . The improved classification of fine screens results in a shift in the grind / grade relationship . In other words , a similar grade can be achieved at a coarser grind size or a higher grade at the same grind size compared to cyclone classification . Screen classification also allows for increase mill throughput that results in a lower power and steel consumption per tonne . Fine screening can allow for lower grade ores to be processed more economically and can be used to produce higher grade and more valuable products . Typical operating cost is 1 to 2 US cents per tonne and paybacks for the capital costs are often measured in weeks .”
A large installation of 8-deck SuperStacks is to be commissioned at the Vale Carajas mine Gelado project , transforming iron ore tailings into concentrate product
Golden success for Derrick ’ s G-Vault Interstage screen
Derrick also recently announced the introduction of its new G-Vault ® polyurethane interstage screen for carbon in pulp / carbon in leach ( CIP / CIL ) processes at gold recovery plants . Due to the higher open area ( a 20 % increase in some cases ), abrasion and blind resistance of the surface , the new interstage screen increases performance and reduces maintenance by creating a more efficient separation while eliminating the washing and deblinding procedures typically required for stainless-steel wedge wire screens .
G-Vault screens are available in a variety of sizes , with screen apertures ranging from 500 to 1,200 microns . The G-Vault Interstage screen is a direct bolt-in replacement for the existing wedgewire screens but allows re-use of the operating mechanism . The retrofit involves replacing the wedge-wire screen with the G-Vault and then lowering the module back into the tank . Combining the wear resistance and non-blinding characteristics of Derrick ’ s polyurethane , the G-Vault screen produces increased micron consistency with reduced process interruptions and extended intervals between cleaning cycles .
The G-Vault is composed of several independent screen sections retained in a
304 stainless steel cage . The use of replaceable screen sections benefits operators by permitting replacement of only a heavily worn section , rather than an entire screen . “ Field testing conducted in North and South America , Africa and Asia has demonstrated that G-Vault screens have the ability to increase
had a ground man that did nothing but constantly clean up ; that was his job . Now we don ’ t have a ground man . We haven ’ t shoveled the tail wheel or cleared anything out from under the conveyor since we installed these cleaners . I ’ m amazed by CleanScrape ® , it ’ s been on for a year now and I haven ’ t touched it . This material is sloppy , it ’ s just muck that we ’ re running . And then you look at the return side of the belt and the proof is right there . Absolutely phenomenal . Try it out for yourself , it ’ s amazing .
– Trey Poulson | Fairplay Gold Mine , CO , USA
visit martin-eng . com | 800.544.2947 or 309.852.2384 | cleanscrape @ martin-eng . com
® Registered trademark of Martin Engineering Company in the US and other select locations . © 2020 Martin Engineering Company . Additional information can be obtained at www . martin-eng . com / trademarks and www . martin-eng . com / patents .
OCTOBER 2020 | International Mining 47