Tag Archives: SAG mill

FLSmidth’s SAGwise makes an impact on mill consumables

Just over a year since launching its SAGwise™ total process control solution for semi-autogenous (SAG) mills, FLSmidth is putting some savings statistics behind the sensory and process optimisation system.

SAGwise is designed to optimise the use of the three main consumables in SAG milling: power, media and liners.

Winston Mokoena, Key Account Manager at FLSmidth, said the solution reduces critical impacts inside the mill by up to 45%. This adds life to wear liners and grinding balls, helping to prolong liner life between maintenance and giving mills more uptime, he added.

“SAGwise can improve mill production by 6% and substantially reduce process variability,” Mokoena said. “This ensures that the mill provides a constant and optimal feed to the next stage of the process, effectively facilitating better performance of downstream operations.”

Among the challenges mill optimisation tries to address is too little material in the mill, or too much. Too little leads to critical impacts between the grinding media and the mill liners, damaging both elements without producing value. If the mill is overfilled with mined material, on the other hand, this results in grinding inefficiencies.

“The SAGwise system uses four or eight unidirectional or bidirectional audio sensors located in close proximity to the mill, which detect the analogue sounds and convert them into digital signals for analysis by a processing unit,” FLSmidth said. “This unit uses the sound patterns and other process variables to determine the necessary adjustment to the mill’s feed, speed and pulp density.”

So direct are the improvements that can be achieved by this solution that customers can pay back their investment in less than six months, depending on the commodity value and the specific mill environment, according to FLSmidth.

“The parameters that are monitored by SAGwise include the mill’s power consumption, load impacts, mill load and pulp density,” Mokoena said. “The system then responds to these parameters by controlling the mill speed, the feed rate and the water to achieve the ‘sweet spot’ where the mill runs at optimum efficiency.”

Norilsk Nickel chooses Metso Megaliner for Talnakh concentrator

Norilsk Nickel has recently switched out the chrome and molybdenum alloy lining of a SAG mill at its Talnakh concentrator in Russia as the company looked to increase the life of these all-important wear parts.

Sever Minerals and Norilsknikelremont (a subsidiary of Norilsk) were contracted to complete the mill relining project, using liners supplied by Metso’s global team, which also used the OEM’s Megaliner™ concept.

The new lining is more durable, weighs less and ended up being safer to install than previous the previous lining, according to Norilsk.

A Norilsk spokesperson told IM that the mill lining was replaced with two elements, the Metso Poly-Met; a rubber-steel combination installed on the front-facing part of the mill; and the Metso Megaliner, which has large shell or head liners used to protect the drum.

The spokesperson added: “The cladding manufacturers guarantee that the mill can work for 5,600 hours uninterrupted (that is about eight months non-stop). The previous version required the SAG mill to be stopped for replacement every six months.”

By developing the technology, adopting better project management and using the specialised equipment, Norilsk said it was able to reduce the time taken to replace the mill lining by three days.

The Megaliner is, according to Metso, a new, innovative mill liner concept, dramatically improving worker safety and maximising mill availability. Each shell or head liner covers a large area, has few attachment components and an attachment system which gives a safer working environment for the installation crew, it said.

The weight of the mill lining also came down with the switch from pure metal to a metal-rubber compound, Norilsk said.

“The new mill liner weighs close to 130 t, which is 120 t less than the old mill liner. The average weight of one mill liner element is 1.8 t (elements have different configurations and respective mass),” the spokesperson said.

This reduced weight came with other benefits.

“Due to the lower weight of the capstan, the new mill liner is more wear resistant and better technologically-equipped to cope with an increased number of planned tasks,” the spokesperson explained.

Amplats goes down innovation path for further operational gains

In Anglo American Platinum’s 2018 results, the company revealed how its latest technology and innovation efforts were coming along.

Amplats, in 2018, recorded earnings before interest, taxes, depreciation and amortisation (EBITDA) of ZAR14.5 billion ($1.03 billion), compared with ZAR11.99 billion a year earlier, as total platinum group metal production rose 4% to 5.19 Moz.

In the company’s strategic overview of the business – under a section titled: “Extracting the full potential from our operations through our people and innovation” – the company talked up several processes it was pursuing to “drive improvement in operational performance from current levels”. This was through “greater stabilisation and process optimisation, towards best in class in the industry, known as P100”.

Amplats said: “The next step is to operate our assets and equipment at levels beyond what is currently thought to be possible in the industry, known as P101.”

Examples of areas of P101 improvement include increasing the rope shovel performance at its massive Mogalakwena PGM mine (pictured) in South Africa, from 26 Mt/y to over 45 Mt/y, increasing throughput at the concentrators by over 10%, boosting operating time of concentrators to over 94%, increasing recoveries of concentrators to over 83% and increasing the operating factor at processing facilities (defined as availability multiplied by utilisation).

“Beyond P101, a number of step-change technologies are being developed and deployed, including coarse particle flotation, which can reduce energy intensity by over 30%; advanced fragmentation and shock-break technology at concentrators, which has the potential to also reduce energy intensity by 30%; and fine recovery of chrome and PGMs, in conjunction with bulk sorting, which can lead to a 10% increase in feed grade and recoveries,” Amplats said.

Shock-break technology at concentrators has the potential to eliminate the use of SAG mills, according to Amplats. The company is piloting this technology after successful tests of Mogalakwena pebbles indicated a more than 50% saving in power consumption.

Pilot plant trials, “leveraging Element 6 wear resistant tools”, started in April 2018, according to Amplats.

To “unlock” this additional value through P101 and a number of FutureSmart Mining™ technologies and digitalisation, additional investment in a number of fast payback, value enhancing projects is required, Amplats said. “This is expected to deliver EBITDA margin uplift of 5-8% on a mine-to-market basis, within a three- five-year-time horizon, before the benefit of any expansion projects using 2018 prices and exchange rates”.

Capital guidance, including for these fast-payback and P101 investment projects will be in the region of ZAR1.5–1.8 billion in 2019, and around ZAR2 billion for each of 2020 and 2021.

Independence Group’s nickel output SAGs on mill liner issue

A SAG mill liner issue at Independence Group’s Nova nickel operation in the Fraser Range of Western Australia has seen the miner miss its annual production guidance for the financial year.

The problem, which saw a reduction in processing plant availability in the second half of June, resulted in an 800 tonne shortfall in nickel output, Independence said. The company produced 22,258t in the 12 months to the end of June, compared with its 23,000-27,000t guidance.

Independence said it is rectifying the situation: “The SAG mill liners are currently being replaced in a planned processing plant shutdown and are not expected to affect availability or productivity going forward.”

Even with this setback, the company produced 7,344t of nickel metal in the June quarter, up 23% from the March quarter. Independence noted that, as planned, tonnes mined, and milled, ore grades and metallurgical recoveries continued to improve.

Nova has a nameplate 1.5 million tonne per annum ore capacity with a primary crushing, two-stage grinding and differential flotation circuit. It has both a 2.4MW SAG mill and 2.4MW ball mill.

The mine, which produced its first concentrate in October 2016, is expected to average more than 26,000t of nickel, 11,000t of copper and 1,000t of cobalt annually.