Maybe an efficient way of grinding ore is obvious. I'd also like to see some innovative ways of reducing iron ore to metallic iron that avoids the whole pelletizing, blast furnace, coke route.

A good, bulletproof way of sequestering sulfur in concentrate and waste products for non ferrous mining would be nice too. It would open up huge non ferrous reserves in environmentally sensitive Minnesota.  Nobody said these had to be just over the horizon.

I like to think that increasing the ore grade between (open pit) mine and mill is one development whose time has come. Ultra fast value recognition by scanning of individual rocks, coupled with fast computers already allows rejection of negative value rocks. That technology is here now and widely used for diamond recognition and industrial minerals. However, the rock rejection is done by high pressure air blasts, which accounts for approx. 70% of the operating cost. Once that cost is reduced, base metal pit design (software!) and operation will be changed to suit the new technology and allow in-pit crushing, followed by machine sorting. Mine superintendents will be remunerated on value delivered, not tonnage.

Tony, you may wish to look up http://www.iom3.org/cleveland-institution-engineers where Hisarna has a slide show on a 20 year European development, now a joint venture between Tata Steel and Rio Tinto on steel making which avoids pelletizing, BF and coke oven.

I like your comment about ore sorting and the current limitation being related to operating costs arising from the use of high pressure blast air to move the rock pieces around.

One question though - would the same daily "economically optimum" throughput obtained if the optimization was performed on the basis of $/kg (or $/oz) metal to market rather than $/t?

Very fundamental question! Ultimately, yes, in new base metal mining projects it is also the reduction in capital that will justify ore sorting. However, most readers of this group are not active in greenfield planning. They are looking to optimize existing operations, i.e. lower the operating costs per tonne ore, or per kg product. Discarding, say, 25% of present output of an open pit should allow 25% more (cutoff grade) to be mined and still present the mill with more value in the same tonnage of feed. The latter of course largely depends on the grade / recovery one can obtain with the ore being mined and crushed to a certain size for in-pit sorting. Most people in mineral processing have no idea how their ore(s) would respond to ore sorting; core is not yet assayed on value fluctuation on an inch scale. It is assayed by the meter. Here is an opportunity for developing a core reader with corresponding software.

I believe there is not as much difference between greenfield project development and brownfield production planning as most people perceive it to be.

One key distinction between the two is the accuracy about the costs and revenues. In this, brownfield has an advantage by dealing with real (historic) costs and revenues, throughput capability and mine-mill performance rather than estimates. Any production planning beyond the monthly/quarter time horizon and both are very similar in methodology.

With respect to innovation - greenfield looks upon brownfield for best operating practices as a benchmark for the project being looked up for development. However, this likely overlooks technological opportunities as what might be best practices at the time the project is in production, 10-15 years into the future, would only be a concept not yet accepted in operations. This is not a surprising observation given the large investments for developing a mineral resources to production and the risk adverse nature of most financiers understanding the mineral resource sector enough to be willing to invest in it.

I don't know if there are exploration geologists following this forum as it would be interesting to read about what is the state-of-the-art in their area:

• Systematic photographic archival of drill core before cutting and preparation for assaying was becoming a common practice about a decade ago and should, by now, be considered a best practice.
• Instrumented core "assaying" equipment was the next big thing back then. I have not followed the developments in this area yet would not be surprised to hear that such beast is now available commercially (or near to be).
• The drill chips from the blast holes are often assayed to determine the ore-waste interface and provide data for near-term production planning.

Such information should provide assays over a range of intervals and allow some conceptual.

Now, if one could start to look at variability of assays over short intervals rather than kriging for developing the block model!

The overcoming of the obstacles that prevent deeper mining has to be up there as well. Off planet proposals seem to get more interest without supporting technologies. After all we have barely scraped the surface of our own planet.

Also convincing local stakeholders that tailings storage facilities have some long term value as agricultural land and open pits as dams would allow a few mines to start up. Same applies for oil sands.

Multiple replies here:

• Efficient (fine) communition. It looks like the Metso-University of Queensland alliance could provide some interesting hints to follow-up.

• I concur that dealing with thio species in tailing ponds in a manner which renders them inert on the short and long term would mitigate many of the risks and somewhat appease local stakeholders.

• I concur, we have barely scratched the surface of this planet. However, going deeper may not be the first thing to do. Rather, improving exploration techniques to discover good deposits in currently under-explored areas in Africa, Asia, and South-America and developing them in a sustainable fashion.
  Space, being the last frontier being pushed back by humanity is exotic and appeals the more (wealthy) adventurous persons. I also think there is some speculative visions with meteorites being pure diamond, pure nickel, or pure precious metals!

• Unfortunately, given the recent incident at Mount Polley, it will be even more difficult to convince local stakeholders that tailings management facilities have long term value rather than just being a risk.

• It is cheaper to move and re-process old stockpiles and tailings than blasting rock masses. Some of these stockpiles and tailings from producers in the 19th Century and early 20th Century likely grade the same as currently operating mine-mill facilities. However, there could be some questions with respect to ownership of legacy environmental contamination in addition to implementing processes particularly adapted to aged/oxidized mineralisations (in the case of sulphide minerals).

We are working on an innovation to dramatically increase tailings solids and yet still give an easily pumpable material, so minimal Capex. Disposal footprints and water consumption will be a fraction of current operations, which will transform economics and environmental impact. The same technology could be used to free up currently nonviable resources by allowing them to be pumped easily and safely over long distances as a high solids slurry.

Trying to float finer and finer particles using the same 60 to 100 year old chemistry is a distinct problem. Back when these collectors were first used, molecular structure of chemicals and the crystal structures of minerals were still to be discovered. Not a lot of chemical advancement of collectors as taken place since. We just keep blending the existing chemistry and call it new without fully understanding how they work.

Fine particle flotation is a road block engineers are trying to solve mechanically with nanobubbles. Some pure research in determining the actual chemistry going on at the mineral surfaces would go a long way in developing new chemistry that would be a lot more successful at selective flotation of fine particles than making nanobubbles.

Good point about limited advances regarding new collector-functional groups.

If I remember well, the last truly novel functional group was the S-700 series based on chelation chemistry (a.k.a Klimpel collector) rather than oxidation-reduction chemistry. Most other collectors brought to market since then appear to be re-arrangements of the functional groups on the alkyl chain and blends of collectors.

I have not monitored closely advances for the flotation of oxide minerals. Nevertheless, nothing seems to have been so novel as to be discussed virally by mineral processors at conferences in the last couple of decades. One stumbling block here appears to be the high degree of secrecy surrounding reagent schemes for the flotation of oxide minerals.

There is also one reality for bringing to market new collector chemistries which was not present in the first half of the century of the flotation process: demonstration of being benign for humans and the environment.

From discussions I had with suppliers of mining chemicals at the time the S-700 series came to market, it was indicated that something in the order of 5 million dollars and 5-10 years were necessary to pass through all the hurdles and be allowed to actively market it. Add another 2-1/2 to 5 years for the first real major sale (after extensive laboratory and plant testing) to an operating mine-mill site and the expectation of a decent ROI simply vanishes in smoke.

I've heard that excuse before and if we let it be the rule, nothing will ever be accomplished. First off, we're not testing pharmaceuticals here. If it's taking you 5 to 10 years to develop a new flotation reagent and you're spending $5 million doing it, I think you need new researchers. And as for the hoops, you show it is much safer than what is being used now, I don't think the hurdles will be that big.

I also have been seeing a major shift in the industry as the old guard, who never wanted to change anything and settled for a mediocre recovery, are passing from the industry. The new kids who are taking over plants at relatively young ages (since the industry really didn't do much hiring through the 80's and 90's) are more open to new ideas that have potential to improve their processes.

That fact remains, if you look at it right, is if you create a new chemistry that works well with fine particles, the ROI even after 10 years is going to be worth it because you will have changed the paradigm of flotation reagents. Acceptance is more likely these days and as word gets out, sales will eclipse the current products out there.

And to start this whole process, don't you think it would be nice to find out exactly what chemistry is going on between the reagents and the mineral surfaces?

To clarify - The hurdles to get an innovative industrial chemical approved, without any similarities to existing chemicals are extensive.

The 5 million dollars and 5-10 years mentioned is for the various tests and thorough analysis of the results. This is in addition to the efforts expended to actually develop the reagent. There has been a move towards non-animal toxicity testing of reagents. To get a flavor of these hurdles around the world, one can have a look at http://www.AltTox.org

The thing is, there could be chemicals already out there, already sent through the hoops, that could work wonders in flotation. But without some research into how the chemistry of flotation actually works, no one has a hope of figuring out what other types of chemicals could work.

For this type of research, you can't be doing ROI calculations. They will be negative every time. No other industry that does pure research looks for a return, they see it as something that sets the stage for new products and technologies in the future. There hasn't been hardly any pure research done in flotation chemicals ever.

Perhaps a fund could be set up to get this research carried out at Universities? And not by engineering faculties. This requires chemistry departments.

This is also of interest to us - the grinding media designers. It has always been a concern to overgrind a customers product, but now we are doing target grinds in single stage mills with a F80 of 75mm and target a P80 of under 60um. Media design now has new abilities of targeting finer grinds which is now available because of new design.

Do you really think that the next big step is chemical? In general there is no issue getting particles to be hydrophobic. Rather, the issue is mechanical transfer - getting a 3um particle to do anything other than just follow the water. That's the beauty of approaches such as DAF, which we are approaching with some of the fine bubble generators.

In flotation, I actually think frothless flotation is the future (along the lines of Eriez hydrofloat which is more of an elutriator than a float tank). There is huge money in increasing the particle size of flotation and recovery of coarse locked particles, but this will not happen through a conventional froth layer.

Rolls crushers as a replacement for SAG is a big step, also. Ore grinding ore by flinging rocks at each other is good, but ore grinding ore by induced rock-on-rock pressure is better.

The ore sorters are interesting, but definitely niche solutions. I think ultimately the Commodas/Ultrasort pneumatic units will give way to electromechanical such as the Russian Rados unit. I have not quite bought into the idea of underground sorting of ROM ore, but see the technology as being appealing for small tonnage boutique operations that still use crushing plants on low value open pit ores with higher milling costs than mining costs.

I am still intrigued by some of the failed technologies, such as comminution by microwaves, acoustic shock, hydraulic shock, and other energy intensive technologies that target mineral interfaces. Type of thing that if it ever did work, it would be (literally) groundbreaking.

I think we will be obliged to gradually see less and less water use - consequently James Marsh's comment is extremely relevant. Probably we will be pushed in that direction more quickly than some of the others.

Chemicals can do more than just make a particle hydrophobic. It can create the correct physics needed for a cleaner separation, regardless of particle size. It can keep unwanted minerals from getting into your froth. And I think you'll find, as you work with nanobubbles, you're going to need a new kind of chemistry for that too. To get the physics to do what you want it to do, it's going to need a little chemical help.

Current mineral processing chemistry is ancient, but without it, mining would still be doing bulk ore smelting. Saying "no issue getting particles to be hydrophobic" is equivalent to Bill Gates saying no one needs more than 64K computing power back in the 1980's. Engineered solutions have been proposed constantly over the years and it's come down to small incremental improvement only now. Great improvements come from paradigm shifts, and that comes from taking a whole different view of how the system works. Playing with new grinding technology (or old when you're looking at roll crushers) isn't going to make that shift because you're still doing the same thing, only a little better.

Do you really think engineered mechanical solutions are the only options? And apart from nanobubbles, I still see only grinding technology being considered "the future".

Mechanical may not be your sandbox, but give credit where credit is due.

I think one of the huge chemical gaps is in understanding the role and mechanisms of non-sulphydryl flotation modifiers. When you read Bulatovic's volumes on reagent technology (which are probably as good as or better than anything out there) you can quickly conclude that the use of dispersant, viscosity modifiers, chelants, and three quarters of the physisorbed non-sulphide collectors is essentially empirical. (Even more so for the witches-brews of custom condensates, hydrosols and the like). On the learning curve we go through these spurts where a whole bunch of people start doing cyclic voltametry, then FTIR, then another bunch of people get into TOF-SIMS, and we think we have some models for what is happening, but then it all dies down and it still boils down to "throw it in and see". Anyone who sorts out this mess will have my undying admiration.

When you are trying to transfer 32mW of shell energy to rock largely by flinging steel balls at it, there is big money involved. I had the misfortune about 28 years ago to be inside what was then a very large (32 foot) SAG mill that had been ground out (!!) with a 5" ball charge. It was actually quiet at the start, but then the balls started exploding. Things were cast hemispheres, and they were blowing apart at the seams. One general foreman had one on his desk, and it blew up a week later and went right through the drywall. Nowadays the things are forged, tempered, case hardened, and quite sophisticated in their composition and crystallography. Give us some credit on the control side, though - we don't bounce them off the shell or off each other nearly as much any more. Steel looks like steel, but the stuff we do with it these days represents "quiet innovation". Our Materials group makes a living diagnosing wear, corrosion and failure, and with every analysis we learn.

Quite a few interesting comments in the last day.

Chemistry:

The basic chemistry to get a collector to attach to a mineral particle is fairly well understood - for the oxides as well as the sulphides. What is not is the appreciation and respect of the complexity of the entire reagent scheme (pH, pulp potential, counter-ions, inorganic and organic depressants, etc.) required to do this selectively. This is particularly true for oxide minerals because the metals are essentially in their most oxidized state to start with and one can't use anymore redox reactions which is at the basis of the majority of the sulphide collectors. Also, the oxygen present in the oxide minerals makes a very good base for a hydrophilic surface.

It's about the same situation for frothers - there has been incremental improvements focused on enabling the production and retention of smaller bubbles yet not much beyond that.

Maybe something intriguingly new might arise of the applications of quantum chemical principles?

Physics:

As bubbles and particles get smaller, the magnitudes of the momentum of each get smaller and smaller to the point of i) following the water stream around them and ii) not being sufficient to breakthrough the residual water film surrounding them.

However, does one needs to grind the minerals to 5 um at the first place?

OK, let me say first that I have spent plenty of time optimizing grinding circuits, playing with different media (looked into some chrome balls to cure an oxidizing problem, yes still chemistry...), and fixing mill bottlenecks, so the mechanical is a "sandbox" I am well versed in. But as a chemist, I see how chemistry can adjust the physics to improve the mechanics in mineral processing. Like the chrome grinding balls experiment. Mechanics are not the only "sandbox" to play in. I agree grinding is very important since it is also the biggest cost in mineral processing and very necessary (can separate minerals from each other when they're still locked together). The second sandbox, however, should not be ignored.

I am happy you saw alot of the chemistry as empirical, because it is.. I worked with Bulatovic many years ago at Lakefield Research. Flotation expert in the first degree, but he was an engineer, not a chemist. I'm a chemist first and an engineer second, so I tend to look at things a little differently. I understand the chemistry, to be viable, needs to be relatively simple and economic (no massive pharmaceutical sized chemicals here). But to develop truly new chemistry, you need to know what is actually going on with the current chemistry. That knowledge we either don't have or is out there somewhere in a bunch of remote journals. To make great advances in this "sandbox", that knowledge needs to be found.

Combining chemistry and mechanics is the way to create the new technologies for mineral processing. Like I said earlier, perhaps it's time to get that chemistry lined out. Can be useful in developing new grinding media, etc. as well. Nothing conditions chemistry better than a ball mill. 

I have used a combination of starvation dosages of collectors and the electrochemical model of the flotation of sulphides with quite a good success rate in developing flow sheets and resolving problems over the years.

A good theory, often developed form empirical data, is one that works most of the time. Exceptions are worth noting as they i) points to missing elements in the theory and ii) may lead to avenues not much explored before.

Physics and chemistry are discussing. But it may have value and shape of the particles, -geometry? For example in the cement activity more when the particles have sharp peaks.  It is known that bubbles better fixed on the sharp peaks of the particles.  Perhaps this case, the usual sizes of the particles recovered as smaller. 

Different types of mills to obtain different particle shape, the best sphericity of the particle in the Raymond mill and ball mills, autogenous.

Yes, we all know empirically that sulphide collectors adhere to sulphide particles. Some selectively to just copper or copper activated minerals. But does anyone know exactly "HOW"? If we want to find new science for flotation chemicals, something that could work better than sulphide collectors or better for selective non-sulphide flotation, we have to find out the HOW. Otherwise we're stuck with the same chemistry we've been using for flotation for the last 50-60 years and there will be no advancement in the technology past mechanical flotation cell design.

Particle shape is another avenue to explore. One problem, however, is I don't think we have alot of control on particle shapes. Too much of that control is in the hands of Mother Nature. Gentlemen, would that go back to grinding media research?

I remember an investment banker once talking about a thing he called "sizzle". It's what you get from a neat sounding technology that helps attract investment. Going into space and mining asteroids and meteors has that kind of "sizzle". It gives that adventure feeling, the final frontier, it's exciting.

What that banker told me next was "Be careful about sizzle. At the end of the day, it has to make economic sense."

For me, that means space mining will probably not happen in my lifetime. On the other hand, the technology development needed to do space mining would still have to be done. Just don't let a banker do an ROI calculation on it. For these kind of investments, you need visionaries with more money than they know what to do with. Folks who want to do it for the fun of it. These people do exist (Branson comes to mind) and they are the ones that will make it happen some day. Banks will only jump in when there's money to be made.

Advancements in Mechanization is what is needed to move operations into space. I trust all advancements on earth will be able to translate into space - soon. We need to be more innovative/conservative in the way we are using earth's resources, else we/mankind will not have developed enough to be able to mine space and to meet the needs of future generations (Future generations of people, animals, plants and sea life!). At present, we are using up the earth's resources too fast - exploiting the earth to make a fast buck! This is troublesome and has to stop. I hear stats stating we have enough coal for the next 40 yrs, oil for the next 50 yrs, copper for the next? yrs and steel for the next? yrs. And then what?

Yes - we need to be innovative but are we being innovative in the required areas? How do we do gravity separation when there is no gravity? Do we need to worry about energy use in comminution and ejector systems when we have a large source of solar energy on Venus or possibly a neutron star for energy in the future?

Future mineral processing innovation with rising price of metal in future, is to plan for mss mining with maximum recoveries( may be 100% )of main and secondary minerals by innovative process system including sorters, crushers, grinders, floataion and liquid-solid separation with cheaper solar energies instead of depending on national grids. The basic reserch of the new process may be more efficiently done at Univeristy or Govt sponsored laboratories. Aim should be for zero dischrge concept including full utilistion of tailings.