COMMINUTION & CRUSHING
solutions in trials at Peruvian mines .
In a recently produced paper , Javier Zela , an Application Engineer at the company ’ s Perubased subsidiary , and Percy Jimenez , Head of Sales and Technical Support for that same subsidiary , looked at how the trials indicated a sustained increase in throughput rate and a reduction in grinding media consumption .
The case studies consisted of four mills from different mineral process plants ( SAG Mill 40 ft x 26 ft , SAG Mill 32 ft x 32 ft , Ball Mill 26 ft x 40 ft and Ball Mill 16.5 ft x 20 ft ), using basic operating data as supplied by the plant operators .
Three measures of grinding media consumption for optimal control were considered : kg / h , g / t and g / kWh .
“ These three measures are interrelated and all need to be considered when judging the performance of grinding media ,” the authors noted .
The results obtained with ME Elecmetal media as compared directly with a baseline performance showed : n SAG Mill 40 ft x 26 ft with a 28 MW reversible drive fed with 5.5 in ( 140 mm ) balls – circa- 9 % increase in throughput rate , circa 20 % decrease in g / kWh ball consumption and reduction of grate pegging events ; n SAG Mill 32 ft x 32 ft with installed power of 16.4 MW in a single-stage grinding circuit , using 4 in balls – circa-13 % decrease in g / kWh ball consumption ; n Ball Mill 26 ft x 40 ft with a bi-directional 16.4 MW drive and 3.5 in balls where two of the same sized ball mills are operated in parallel – circa-6 % increase in throughput rate and circa-12 % decrease in g / kWh ball consumption ; and n Ball Mill 16.5 ft x 20 ft with installed power of 3.5 MW , uni-directional drive and 3.5 in balls – circa-2 % increase in throughput rate and circa-8 % decrease in g / t ball consumption . Considering that the use of grinding media can represent up to 40 % of operating costs , these results highlight a significant opportunity for improvements , the authors noted .
“ In general , the best quality grinding media will result in improvements in operational and media performance ,” they said . “ This can be evaluated through analysis of the throughput rate and the specific energy consumption ( for operational performance ), and by analysis of media consumption in terms of g / kWh , g / t and kg / h .”
The authors , in this paper , summarised that the operational practices in Peru with two case studies in SAG milling demonstrated improvements due to the increase in rock breakage with an increase in ball size and a reduction in pegging grates events . In the other two case studies in ball milling , there was a demonstrated reduction in grinding media wear .
They concluded : “ Rock breakage inside tumbling mills , and SAG mills in particular , is complex and can be influenced by several factors including ore characteristics and mill operational variables . It is worthwhile to understand the various mechanisms of rock breakage and where they tend to occur in the mill charge , but , in a simplified view , rock breakage can be represented by the mill specific energy consumption ( SEC ).”
Bradken Mill Liners , product development expertise on show
Bradken has recently leveraged a suite of newlydeveloped digital tools to track , report and construct a machine-learning model to help accomplish Freeport-McMoRan Bagdad ’ s target objective of increasing discharge production from its Ø32 ft x 13 ft AG mill .
In 2019 , Freeport Bagdad explored an expansion project that would increase site production by 20,000 t / d . As part of this expansion the AG mills were nominated for optimisation to increase discharge production and maximise potential increases in downstream capacity .
Bradken partnered with Bagdad on the optimisation of its grinding line 3 ( GL3 ) Ø32 ft x 13 ft fixed speed AG mill . GL3 is a bi-directional mill operated with traditional bi-directional radial pulp lifters and top-hat high-low shells . The mill was inspected regularly with planned stoppage and inspection at 42-day intervals .
The mill operated at an average throughput of 814 t / h across a typical liner campaign .
In the recently published study , Bradken outlined how an advanced liner design methodology could lead to a full AG mill liner package with a focus on the shell and discharge end to generate and discharge the product stream . Strategic selection of liner material for grates was used to mitigate risk of major design revisions and provide performance validation in service before revising to align with reline and increases overall reliability needs .
Optimisation efforts significantly improved AG mill performance , Bradken noted , with the final design , featuring a half-row double-wide Bradken Vortex discharge system , yielding a 9.5 % throughput increase and a 2.5 % reduction in overall circuit energy consumption .
“ The collaborative and iterative optimisation process successfully met the customer ’ s
A half-row double-wide Bradken Vortex discharge system was behind a 9.5 % throughput increase and a 2.5 % reduction in overall circuit energy consumption at the Bagdad mine
production goals , showcasing advanced liner design , modelling , material selection and digital tools ,” it said . “ This methodology holds potential for enhancing design optimisation in similar mineral processing circuits .”
Derrick SuperStack for steel
Derrick ® Corporation is partnering with Rungta Steel , one of India ’ s leading and fastest-growing integrated steel manufacturers , to mark what it says is a significant step in its commitment to sustainability and innovation .
The company will implement Derrick ’ s SuperStack ® technology at its iron ore beneficiation projects in Odisha , India .
Rungta Steel is embarking on a plan to establish iron ore beneficiation plants in Odisha capable of producing 3.6 Mt / y of high-grade iron ore concentrate . Additionally , it plans to improve two existing 1.3 Mt / y plants by incorporating Derrick ’ s high-capacity , high-efficiency fine screening technology into currently operating circuits to sustainably maximise resource efficiency .
Derrick India ’ s Country Manager – Mining & Industrial , Amit Jain , said : “ Derrick is thrilled to collaborate with Rungta on these projects that align with our shared efficiency and sustainability goals . Our SuperStack technology is equipped to exceed Rungta ’ s requirements for increased capacity while enhancing overall operation efficiency and product quality .”
SuperStack , designed , engineered and manufactured at Derrick ’ s Buffalo , New York facility , will be integrated seamlessly into closed grinding circuits , bringing significant advantages , increased productivity and improved classification to Rungta Steel ’ s operations , it says . These solutions will provide efficient particle classification within the 250-350-micron size range while simultaneously minimising waste generation and greenhouse gas emissions , Derrick added . IM
50 International Mining | APRIL 2024