Despite having seen renewed interest and research over the past ten years, in-pit crushing and conveying (IPCC) systems in mining are still relatively few and far between.

While at first this could likely be attributed to trepidation on the part of mining companies (unsuccessful installations in the 1970-80s put many companies off revisiting the technology), today, it is more likely to be due to market conditions and increased CAPEX awareness.

Paul Emerson, global product line director for minerals-material-handling technologies at FLSmidth, tells MM: “We saw a huge interest in IPCC before the global economic crisis. The driver back then wasn’t so much the lower OPEX; miners seemed to be motivated more out of a desire to supplement their trucks with IPCC in order to increase production throughput and reduce traffic congestion in a period when availability of new trucks, tyres and parts, was becoming extremely problematic and expensive.

“However, these first large-scale IPCC pilot systems were not without teething problems, and with an almost overnight reluctance of the industry to spend CAPEX, the appetite for clients to invest in IPCC systems has dwindled in recent years.”

He continues: “That said, we are starting to see a renewed interest in miners wanting to reduce trucking costs again, and a lot more scoping-level budgetary costs being requested recently.”

Of course, capital constraints have impacted equipment sales right across the industry and not just in the IPCC space; the financial results of the major OEMs all attest to this, and miners have kept new investments to their key portfolio assets wherever possible, shunning the riskier development of new mines.

The optimal application for IPCC technology is at greenfield projects, as this allows the open pit to be designed in a way that favours conveying of material rather than truck hauling, so it is likely that this has also impacted on the number of new IPCC installations.

“On the other hand, maintenance, relocation and studies on existing IPCC systems have continued for many mines,” says Thomas Gramling, president of Takraf USA.

Metso, which has a significant presence in the quarrying and aggregates sector, reports a stable but low number of sales from that industry, mainly for smaller installations. Although the company has also seen a high level of interest from miners in recent years, sales in this area have been slow.

Recent research from Goldman Sachs Group indicates that the fall in commodity prices over the past five years will see total global capital spending by mining companies drop about 60% to a US$57 billion next year, from US$145 billion at the peak in 2012. This scenario means that while many vendors and service providers may have new products and solutions ready to go, demand is unlikely to increase significantly in the short term.

Held back by prices

Uncertainty in commodity prices and demand are the most important factors restricting the implementation of IPCC. These systems represent a significant capital investment and the payback period is often measured in years. As such, the use of IPCC technology is often favoured in mines with longer lives.

John McCarthy, product manager at Joy Global, explains: “When commodity prices were continuously declining, many mines weren’t certain about their future. It appears that commodity prices have at least stabilised, which will allow mine management to make decisions with more confidence.”

To increase productivity, miners must improve two of three variables: they must reduce the OPEX for their assets, lower the capital intensity or increase throughput. It is difficult to achieve two of these, let alone all three, and IPCC implementation is no exception.

“One can easily increase throughput by adding trucks and shovels to existing fleets and infrastructure, which has a lower initial CAPEX when compared to an IPCC system, but ignoring the long-term OPEX will be detrimental in the new norm for the mining sector,” Emerson explains.

“On the flip side, the IPCC system is capital intensive and cannot be implemented in the time frame it takes to buy some mobile equipment – so IPCC is not a quick fix to reducing OPEX issues and increasing throughput in the short term. Still, I do believe IPCC will be an increasingly utilised method of moving mined material, particularly in the removal and disposal of overburden.”

Although the advantage of IPCC over trucking prevails in many cases (when both CAPEX and OPEX are considered), the current general hesitation to spend is limiting the uptake of IPCC technologies, even for new projects.

“Lower salaries and cheap oil have reduced IPCC interest due to the lower cost of maintaining an existing truck fleet,” states Gramling. “Furthermore, the current weak mining and minerals market has also increased the competitiveness of haul-truck manufacturers. We believe that once the mining and minerals market rallies and oil prices recover, IPCC systems will recover their cost efficiency, and as a result, the technology will recover and be adopted more widely.”

In addition to the current market situation, a lack of operational knowledge and experience in IPCC in the mining industry still exists, and at brownfield sites, it is more difficult to modify mine plans/designs in order to optimise IPCC solutions.

Erik Isokangas, director of in-the-pit solutions at Metso, says: “Our customers are facing the challenges of reducing operating costs, improving their environmental footprint (reducing energy and water consumption), and working with their local communities to reduce noise, dust, and emissions. They see that IPCC solutions can address many of these challenges. Over the longer-term the limiting factors are being overcome through education and training, and improvements to mine planning software.

“Some customers are also going down the path of semi-mobile solutions, which keeps the flexibility of truck haulage while minimising haulage distance.”

It is worth remembering that although challenges still exist, many obstacles from IPCC’s past have been overcome. “We consider it a major step forward that IPCC nowadays is not considered an ‘exotic’ way of mining anymore that can only play a niche role,” says Thomas Jabs, head of mining systems at thyssenkrupp. “Today, the planning of expansions and grassroots projects often start with basic IPCC questions: ‘Do I really need trucks? If yes, how can I limit them?’ Naturally, this leads to IPCC and continuous mining models.”

In this regard, IPCC in mining has come a long way and this can only be a positive thing for the technology’s future.

A step forward

When looking at key technological advances over the past five years, every company interviewed for this article mentioned high-angle conveyors. However, while most of the major OEMs have taken a stab at the technology, this still seems to be a missing link for IPCC success.

The complexities involved with conveying large quantities of primary-crushed materials up steep slopes remain and, unless a completely different approach to conventional mining methods is adopted in order to accommodate conveying at much shallower angles, high-angle conveyors remain the industry’s best solution to this challenge.

“We are currently working on feasibility studies with [a number of] customers proposing very deep pits,” explains McCarthy. “With many of the proposed projects, the customers have made it clear these projects could never be financially viable with traditional mining methods. They need a new way of lifting huge volumes of material from great depths.”

To achieve the required productivity and financial goals, IPCC systems must attain a very high level of utilisation. High-angle conveyors go some way to achieving this, as do remote health monitoring systems. These allow personnel to track and analyse data from the system’s conveyor components, and identify those that require maintenance or replacement prior to failure, giving mine operators time to plan.

Gearless drive technologies have also taken some major steps forward and thyssenkrupp in combination with Siemens have been the frontrunners in this field.

“Many of the installations we have put into operation in the past few years have proven their reliability, which was what the market was waiting for,” Jabs says. “The advantages of this drive technology are very obvious for high-capacity conveyors. Capacity wise, the same is true on the crusher side. We also saw a clear demand for the next size of primary gyratories, and this is why we launched the KB 63-130 gyratory crusher, the biggest gyratory crusher on the market worldwide. The customer feedback and interest at MINExpo 2016 in Las Vegas was very good.”

On the other hand, there is also demand for smaller, more flexible machines, especially on the upstream side. “Fully mobile crusher inquiries today are seldom in the super high-capacity class, but more often in classes around 3,000t/h to gain more flexibility, and also to have more blending options by using two or three smaller machines, instead of one super rig,” adds Jabs.

Meanwhile, Emerson cites FLSmidth’s Dual Truck Mobile Sizer (DTMS), as a key step towards reducing truck fleets. “It is the only real attempt to do something completely different in the pit with the intention of reducing truck fleets substantially, while keeping the flexibility of the truck shovel operation within more traditional mining plans,” he says.

Reducing civil costs

FLSmidth has been working on a number of new products. It recently developed a concept for semi-mobile crushing stations by adapting proven coffer dam technology. “The concept is simple, low capital and OPEX cost effective, in that it eliminates the need for costly retaining walls associated with large semi-mobile or relocatable stations,” explains Emerson. “The cost of the concrete retaining walls makes more frequent relocations of the stations cost prohibitive.”

The system consists of specially designed and fabricated steel panels that make up a floor and retaining wall that is erected within a key cut in a bench, and the earth is then backfilled and compacted around it. It is designed to support the associated loads of earth and trucks feeding a semi-mobile station that is moved in using a crawler transporter after the box retaining wall and floor have been assembled.

The mining client in question bought two low-cost sets of panels that would be used and alternated between moves, making downtime and relocation of the large stations fast and effective, while mitigating the costs associated with concrete retaining walls.

Joy Global is also keen to eliminate the civil works associated with a traditional primary crushing station. These can be a huge investment that is lost with each relocation of the crusher.

In Joy feeder-breakers, the material flows horizontally to the rotating breaker. Most primary crushers require the material to drop vertically. Utilising a horizontal material flow greatly reduces the height of equipment, making it suitable for mobile and semi-mobile applications.

“The lower height reduces the cost of any civil works such as a retaining wall, explains McCarthy. “With mobile applications, the lower height also makes it easier for excavators and wheel loaders to dump into the hopper, improving their productivity. The low centre of gravity makes relocation easier; in many applications the machine is dragged with dozers.”

Advanced conveying

FLSmidth also has a major focus on dry tails stacking. As part of developing a complete system from plant to waste area, the company claims to have designed and built the world’s highest capacity filter press, which is being commissioned later this year at a large copper mine in Chile.

In order to deal with the resulting large dumps of filter cake, FLSmidth developed a special feeder that bridges the batch process to continuous conveyance.

“On the back of this development, we investigated its use for IPCC applications to combine an apron feeder, dribble belt and discharge conveyor into one unit – the Incline Hybrid Apron Belt (HAB) Feeder,” Emerson explains.

Although still at the conceptual stage, this would allow more compact truck tip or shovel-fed stations that could feed to a secondary station housing the mineral sizer, all of which would enable the use of smaller, more compact and mobile in-pit equipment.

With the problem of high-incline conveying material out of large open pits, and the complexity of going from batch delivery of material from trucks and shovels to a continuous belt conveying system, FLSmidth has also investigated the use of its mine shaft systems in openpits.

“We have considered using a larger throughput, heavy-duty, adaptation of a dual skip Blair multi-rope hoist configurations with gearless drives and synthetic fibre ropes as a method of out-of-pit conveying,” says Emerson.

To date, all of the components are commercially available to support this concept. A recent scoping study by FLSmidth, considering 25% of the material from a 1,250m-deep pit, indicated an average OPEX saving of around US$75 million per annum for the out-of-pit haulage.

Healthy, happy system

Joy Global has been working on its integrated JoySmart Solution for conveyors. The remote health monitoring technology was recently deployed on a 1,300m-long conveyor system at a US coal operation. Joy’s experts took baseline readings of the system during commissioning and once the system was in regular operation, excessive start-up torque was detected. The JoySmart team used the baseline readings to quickly target the problem area, and personnel were immediately sent to the site to investigate the problem.

They confirmed there was excessive vibration on the head drive pulley due to a faulty coupling. Left undetected, this could have lead to damage of the four 1,850kW gearbox shaft assemblies, which are long lead-time items. Normal production was able to continue while the teams monitored the anomaly and resolved the problem, saving the customer months of downtime and the potential for US$2 million in gearbox replacements.

Joy Global is supplying a third mobile feeder-breaker to a customer that has been operating two similar units supplied 23 years ago. The machine is mounted on crawlers and is remote controlled using a radio pendant.

“The machine matches the capacity of a Joy L-1350 loader, which has a payload of 40.8t,” explains McCarthy. “The mobile feeder-breaker hopper design allows it to work with two smaller wheel loaders if needed; one on each side. The mobility of wheel loaders allows them to dig a short distance away from the crusher and still maintain reasonable production.”

R&D is underway to allow the feeder-breakers to also be used in harder, more abrasive applications.

Concentrating hard

This year, Metso successfully commissioned its largest, fully mobile jaw crusher, the Lokotrack LT200E with a mobile apron feeder, Lokolink system, and spreader at Polymetally’s Altay copper-gold operation in Kazakhstan. Peak throughput has so far exceeded the design specification by more than 10%. “This is a fully mobile system that’s designed to crush both ore and waste in the pit,” says Isokangas.

Metso has recently launched a new fleet-management system, Metso Metrics. This is a cloud-based, real-time remote monitoring and data visualisation system. Equipment operation and maintenance data is transmitted by satellite to Metso servers. Service specialists monitor the performance of the machines and provide support to ensure the equipment is receiving the best possible care and maintenance.

Metso announced in October that it is supplying a semi-mobile IPCC solution to Tibet Julong Copper for the Qulong copper mine in China, one of the largest greenfield copper projects in the world. Qulong has a proven copper reserve of more than 7Mt. The in-the-pit mining and concentrator operations will be located on the Qinghai-Tibet Plateau. The mine will be built in three phases during 2016-2018, and after completion it will produce 560,000t/y of copper.

Among other key mineral processing equipment, Metso is supplying two PG60110E gyratory crushers that were booked in October, and a further two units are expected to be booked in phase three of the project.
Metso has recently sponsored IPCC research at the University of Queensland’s School of Mechanical & Mining Engineering in Australia. The programme is centred on developing models for estimating the effective utilisation of IPCC systems.