SAG2015 Blog – Edition 2

The morning session of Day 2 started with a dazzling display of DEM work. Modelling has now extended to HPGRs and stresses on SAG liners. The graphics and the level of mathematics and coding never ceases to amaze me.

Simulation followed with further refining of the AG/SAG variable rates in the JK models as well as some new advances from Moly-Cop tools.

The HPGR was up next. Persio Rosario showed us how some finessing of plant layout and use of stockpiles can wipe up to $67M from the CapEx.

The highlight for me was a Metso paper outlining the development of the largest HPGR, 3m x2m rolls and 11.5MW installed power. Huge! And all developed in 4 years. It’s been running for 8000hrs and they have addressed issues such as skewing and re-circulating load. And on the side, the Metso team invented a “transporter” for rolls change out. Impressive to say the least.

After coffee, mill drives were in. Siemens is developing a 42ft gearless drive that can operate at 35MW at 1000m. While Metso launched their Quadrex, using 4 pinions attached to the girth gear to deliver 28MW of power. Oh the options!

I ducked out of the afternoon sessions to attend a tutorial on comminution circuit design by Steve Morrell of CITIC. Happy to report there will be another simulator on the market. Yay!.. it was like an Apple product launch... however this one came with beer! CITIC are working on a Limn based simulator with Morrell’s models and data for design and optimisation of comminution equipment and circuits. Move over JkSimMet!

A couple highlights on Day 3. The first being the IsaMill installation at Arrium. Where an opportunity during commissioning and optimisation of the IsaMill allowed liberation characteristics of the IsaMill product to be compared to that of the ball mill at the same grind size. Interestingly, at P80 of 32um the IsaMill product container more spherical, better liberated particles. No doubt this will be further investigated by the IsaMill team.

Another highlight was the potential of the Outotec HIG mill to take the place of a ball mill, already operating for 40 years in the industrial minerals arena. It is a vertical mill that can be run in open circuit and the largest unit has 5MW installed. Current test work shows it can reduced 5mm feed to 200um in a single stage in a coarse application, and in a fine application down to 53um, with promising power savings… perhaps we have another “HPGR-esque” technology in our midst.

My personal favourite paper came on Day 4. Although when I arrived (little late – still blaming jetlag), I noticed a lot of chatter about the first paper of the day by Paul Staples of Ausenco. Although the strawberry short cake was beckoning, I decided to pull out the flash drive and have a look. And look I did, I couldn’t divert my eyes… and frankly, I’m surprised it did not cause a riot. Mr Staples declared that the reason a number of recent SAG mill installation are not achieving nameplate is that they were not designed properly in the first place. Opps!.. And these errors are costing people money to fix – lots of money. And no, you can’t blame the miners, geo’s or the orebody!...

Back to my fav paper. A paper on circuit optimisation at Batu Hijau. With the help of Walter Valery, Steve Morrell and the mine to mill approach. Batu Hijau showed that when the silos of geology, mining and processing do not exist and people actually work together, great things can be achieved at an operation. Comminution equipment runs at maximum throughput even when the ore changes, as the variations are anticipated and something done about them ahead of time. Way to run a mill, guys!

Next Malcolm Powell told us about a PGM Lonmin operation where increasing grate open area had a massive impact on throughput. Getting slurry transport right at this site meant a whopping 17% increase in PGM recovery. I think they deserve a few beers for that.

After lunch we’re talking HPGR circuit optimisation.  Some free advice I gathered from this session;

  1. conveyors use up a lot of energy (1.3kWh/t at Boddington) so think about your layout,
  2. install VSD on your HPGR and design a plant so that you can choke feed the HPGR.. thank you

This brought us pretty much to the end of another SAG Olympics, para-phrasing Bern Klein in his closing remarks. We’re not sure when the next conference will be, could be 4 years, could be more, but what’s certain is that many great ideas will be exchanged, deals will be done and beer will be drunk.. As for this lass, if I’m lucky enough to attend the next SAG conference and again have the opportunity be enlightened and inspired by the work my peers as we try to wrangle and tame this comminution beast, I’ll be sure to take something for this wretched jetlag…. Safe travels everyone.