In July, Finnish mining equipment supplier Metso Outotec won a €45 million (US$47 million) order for sustainable crushing, screening, and grinding technologies for a greenfield iron ore project in South America.

Metso Outotec said the comminution circuit flowsheet developed for the new concentrator plant in cooperation with Metso Outotec represents "the most sustainable technology currently available".

Conventional horizontal mills have been replaced with the combination of the company's HRCe high pressure grinding rolls and Vertimill grinding mills to achieve better energy-efficiency, said the company.

By utilizing this flowsheet, the plant is expected to save 25% of installed power compared to a conventional HPGR/ball mill circuit and over 40% compared to a conventional SABC circuit.

Metso Outotec's scope of delivery consists of the engineering, manufacturing, and supply of Superior MKIII primary gyratory crusher, HP Series cone crushers, HRCe high pressure grinding rolls, vibrating feeders as well as banana, horizontal and dewatering screens and Vertimill stirred mills. In addition, Metso Outotec will provide installation and commissioning advisory services and wear and spare parts.

Mining Magazine editor Craig Guthrie talked over the project with Christoph Hoetzel, SVP of the Grinding business line at Metso Outotec.

Can tell us more about how you came up with the concept of an environmentally friendly circuit flow sheet?

We have been working hard in the field of energy-efficient comminution for quite a while. If you look into our stirred mills offering, including our Vertimill, HIGmill and Stirred Media Detritor (SMD), we are the leaders in energy efficient grinding solutions. There is also the HRCe and original HRC series of High pressure grinding rolls (HPGR)  - those machines have unique advantages that make them really energy efficient.

For instance, the HRCe is able to produce a finer product, because of its flanges. And the Vertimill, can accept a relatively coarse feed for stirred mills. Combining them make quite the energy-efficient duo and leads to a truly Planet Positive flowsheet.

Each product has been in similar applications for a while. But why we're quite proud of this particular order is the fact that it's the first time that it's all been put together. In total, you can say it is a huge step in terms of energy savings for the customer.

There are certainly some headline-grabbing figures around the customers' energy consumption savings, does this suggest that more customers are more willing to put all these solutions together?

I believe so. But the most important aspect that sometimes is forgotten is we need to really look into this holistically. You can build the most energy-efficient circuit in the world, but at the end of the day, you also need to make sure that you reach your capacity. You need to ensure high-quality output levels with high equipment availability, but also with low energy and low wear.

So it's always horses for courses. And that is really something to understand when combining solutions. This is one of the advantages that we have. Because we have everything needed - we don't have to sell you a certain machine, because it's the only thing we have.  It is like that saying, ‘If the only tool you have is a hammer, everything looks like a nail'. This isn't true for us. Everything needs to be in balance and considering all aspects holistically to provide the most efficient and cost-effective solution. And the customer is in the driver's seat.

The market is shifting towards more energy-efficient equipment. And different type of circuits are becoming more viable. Especially over the long term, energy cost, and water is also another aspect, that's driving more of those decisions. It may not be for everybody, - it's not that every single circuit will be set up like this, because for some, it still doesn't make sense from a practical point of view or from an investment point of view.

So why was this particular circuit a good fit for this South American customer?

There were several aspects. Firstly, for our HRCe, the customer was familiar with the technology, and very happy with its high performance. And so they really saw the combination was quite low risk.

Secondly, we have multiple Vertimills running in similar ‘coarse' grinding applications for quite a while, and those have proven their superior energy efficiency while also providing very low total cost of ownership due to their excellent wear performance.

The only thing was to basically put it together. Also we had the whole comminution circuit from the primary crushing all the way to the Vertimill product, which also includes all the classification equipment in between - which plays a very important role. Classification equipment is like the glue that holds the circuit together, and for this project it was a given.

Then in the end, it also comes down to the material properties. If you have other projects that then opt for a traditional circuit, there might be specific reasons related to the ore. You might have a certain clay content in your feed, or maybe high moisture in your feed. At the end of the day, in our business, we always need to see what is the material that we need to process. We can't just say we have great machines, but we need to take care about the material in the best way possible for our customers. That is where the fun is.

When we talking about the adoption and take up of cleaner, more energy efficient combination or grinding technologies. What challenges do the miners face that impact their decisions?

If you look into building a mine or concentrator, there is a lot of risk that is involved in that. Even if you did a lot of testing campaigns, there is still some uncertainty, especially if you're talking about something greenfield.

Risk comes at a cost and requires trade-offs. Handling the risk is an important aspect. And I think you're covering that by ensuring that you base decisions on proper data. That's also where testing can come into play.

So, that's one aspect. And then obviously, there is the need to ensure you work with partners that have a proven track record, good equipment and who will be there for you across the lifetime of your mine. When it comes to the plant, first and foremost, it needs to produce what it is built for. And it needs to do this in the most reliable and cost-efficient way.

Finally, if the technology ticks all these boxes then it's a really good choice.

And maybe for some customers the balance might not be there all the time. So that's why I'm saying we need to apply this holistic approach. If we are looking into the fine-grinding space for example, we have all the major technologies in that area.

So, we can actually look into it, where if we select a machine, it is due to the energy efficiency, but also ease of operation, wear behaviour and media consumption.

The same holistic approach is applied if we are looking into how to combine our high-pressure grinding rolls, horizontal mills and stirred mills into the most beneficial combination. The best solution needs to tick all those boxes for our customers.