Efficient flotation: Designing the optimal bubble

The flotation team knew they could improve the energy efficiency of flotation by rethinking the rotor/stator technology. So they teamed up with aerospace researchers and changed the hydrodynamics of the flotation system.

"Smaller bubbles have better attachment properties than large ones. But if you increase aeration rate to improve throughput, the flotation cells produce larger, not smaller bubbles, so it's really not a straightforward proposition," explains Product Manager of Flotation at FLSmidth, Asa Weber.

Flotation is about creating the proper energy dissipation rate in the cells, to obtain optimal contact between the bubbles and the particles and extracting the minerals.

"We wanted to design a machine that enabled us to increase the air volume and reduce the bubble size at the same time and simultaneously optimise energy dissipation rate. So for the initial technology developmental phase we decided to team up with a range of experts in air dispersion; including aerospace researchers, surface chemistry researchers and the Center for Advanced Separation Technologies at Virginia Tech. We worked with a 3-phase model replicating real world conditions," says Weber.

The combination of mining industry academics and experts from the aerospace industry allowed the team to come up with an innovative design concept for the rotor/stator.

"They admitted it was difficult. They know about high-performance aircrafts and submarines and we wanted them to deal with a three-phased flow problem," Weber laughs.

New rotor/stator low-energy technology

The target was to create a new ultralow-energy flotation system and the team came up with the nextSTEP™ advanced flotation mechanism, featuring a new rotor/stator low-energy technology.

The function of the rotor/stator is to make bubbles, suspend particles and create an environment for bubbles and particles to make contact. "The key is to do it with the least amount of power possible. So we elongated the vane of the rotor and cut slots in the stator to optimise the geometry of the rotor/stator assembly," Weber explains.

We wanted to design a machine that enabled us to increase the air volume and reduce the bubble size at the same time and simultaneously optimise energy dissipation rate
— Asa Weber, Product Manager of flotation, FLSmidth

The new rotor is designed to produce ideal flow streams. It also produces an energy dissipation rate that enhances the bubble-particle attachment. The patented rotor/stator makes energy dissipation more uniform, which results in a higher probability of bubble to particle contact during the flotation process, dramatically improving attachment rates. The jet exiting the rotor is distributed across a larger surface area than in traditional machines and this causes an even flow distribution that increases the wear life of the mechanism, as well as reducing downtime for repairs. On top of the even wear patterns, the rotor can also be run in a reverse direction to further increase the life cycle of the mechanism.

"The nextSTEP rotor/stator provides a step change in flotation, metallurgical performance and energy efficiency," Weber states: "It has the lowest operating power of any forced-air flotation mechanism on the market."

Up to 40% less energy and compatible with all cells from other suppliers

  • 15-40% less energy consumption, while maintaining or improving recovery.
  • Engineered to fit a variety of machine sizes, ranging from the smallest 5 m3 cell up to FLSmidth’s 660 m3 SuperCell™ machine.
  • Interchangeable with FLSmidth's Dorr-Oliver® forced-air flotation mechanisms.
  • Installation of the nextSTEP mechanism can be carried out during scheduled maintenance downtime because the components of the system are common items that must be replaced periodically within ongoing flotation operations.
  • The design is applicable across all mineral applications and can also be retrofitted into cells from other suppliers. An energy saving of 18% was obtained in a copper plant by exchanging the existing rotor/stator in a cell from another supplier with the nextSTEP mechanism.
  • Analysis of the wear characteristics after nine months in operation indicates that the wear life of the nextSTEP will exceed the industry benchmark of two years.

Contact:

Steve Ware, Director for flotation and dewatering: Steve.Ware@FLSmidth.com

Esperanza_Cells_FLS.jpg

An end to tailings dams

With a breakthrough in filtration technology, FLSmidth is proving that a full dry stacked tailings solution is technologically feasible for large scale operations – and that the recovery of up to 95% of process water is economically competitive with desalination, even for high tonnages.

"This is no less than a step change in water management. It is the needed piece of the puzzle towards the only sustainable tailings management; dry stacked tailings maximizing the water recirculated in the process,” states Director of Tailings Solutions in FLSmidth, Todd Wisdom.

As the need for dry stacked tailings has increased, so has the need for larger and larger dewatering equipment to accommodate the huge volumes of tailings requiring treatment. Some large mining operations produce well over 100,000 dry tonnes of tailings per day. Dewatering this massive volume of solids to the geotechnical standard needed for dry stacking requires large filtration areas which, using old technology, would require football fields of filters. These in turn would require an unsustainable amount of piping, valves, pumping, conveyance and maintenance. To reduce the number of filters, FLSmidth decided to develop an economically viable system for dewatering high tonnages to the scale of more than 120,000 tonne/day of tailings.

"As the ore grades decline, miners' revenue per tonne decreases accordingly, so we need to decrease the cost of tailings processing to make the operation economically viable and our solution cost competitive with alternate technologies," explains Todd Wisdom.

With this breakthrough development in filtration technology, we have made the operating and capital costs of dry stacked tailings competitive with traditional technologies for large scale mines.
— Todd Wisdom, Director of Tailings Solutions

Up to 95% water reuse

To optimize the capital and operating costs of plants operating at large tonnages, FLSmidth came up with the AFP-IV® Colossal™ filter. The filter enables effective dewatering of large volumes of tailings with less than half the number of filters required with competing large filters. The new filter not only increases the amount of water that is returned to the plant for reuse, it is also able to decrease the amount of water that is lost to the environment through evaporation and seepage. These are two major hurdles that can be expensive and difficult to overcome in traditional wet tailings facilities.

To prove the operating and financial benefits of their large format tailings dewatering facility, FLSmidth partnered with a large mining company in Chile and installed a complete tailings filter system to process approximately 10,000 tonnes per day of whole tailings. A full scale implementation of this technology would allow mines to operate with a water make-up ratio of 0.2 m3/tonne, compared to traditional sand dams with a water ratio of 0.7 m3/tonne.

By enabling mines to reuse between 90-95% of their process water, the filter solution would thus enable mining companies in Chile to reduce their fresh water intake by more than 70%.

Beats desalination and eliminates tailings dams

"With this breakthrough development in filtration technology, we have made the operating and capital costs of dry stacked tailings competitive with traditional technologies for large scale mines. A large copper concentrator with a tailings output of 100,000 tonnes per day, for example, could save 200 million m3 of water over ten years by using our dry stacked tailings technology combining thickener and filter with our RAHCO® mobile stacking and conveying system to dispose of the tailings as dry filter cake," states Todd Wisdom. In Chile that would translate into $USD1 billion for desalination.

“Furthermore, our filter solution eliminates tailings dams. Desalinated water will still end up in a pool and risk causing damage. We need to eliminate the need for any pool at all,” he adds.

Technology for high tonnage, high altitudes

FLSmidth's AFP-IV Colossal filter is a filter press, which uses high pressure and fast filtering to achieve much larger single machine capacity and optimal cake moisture concentration. Where vacuum filters are not effective at higher altitudes, and belt presses and centrifuges are only effective for small tonnages, filter presses are able to use higher driving forces to achieve high dewatering rates and can operate effectively at high altitudes. This allows them to have the smallest installed footprint and low installation costs, alongside greater operational flexibility.

"Operational flexibility is needed as the tailings filtration characteristics change over the life of the mine.  For these reasons, we believe that large filter presses like this one will become the equipment of choice for high tonnage tailings dewatering applications," says Todd Wisdom.

The feed to the filter press is pumped from a buffer tank, which has sufficient capacity to allow a constant flow from the tailings thickener during the batch filtration process. The pumping of the feed slurry under pressure into the chambers/cloths, provides the force to build a cake within the chamber. As the cakes form, the pressure to produce a properly compacted cake rises steadily. Most filter presses on tailings applications operate with up to a 15 bar driving force. Using FLSmidth technology, this driving force can easily be reached using just the feed pumps to the filter. After the cake is formed, high pressure air, in the range of 7 to 10 bar, can be blown through the cake to further reduce its moisture content and produce a non-saturated cake, if required.

The cake is formed by the capture of solids on filter cloths which encapsulate the filter chambers. The press is closed by means of hydraulic cylinders and multiple plates, which, on closure, form the chambers that capture the filter cake. The moisture of the discharged filter press cake is in the range of 10 to 25 wt % and can be either saturated or unsaturated depending on the filter design and geotechnical requirements. 

The Colossal filter is the largest capacity filter in the industry. It is capable of discharging 20,000 tonnes of filter cake per day and can recover 600 m3 of process water per hour. That is the equivalent of six Olympic sized pools each day.

"To cover the need of a large mine with 150,000 t/d of tailings, ten filters would probably need to be in operation. In arid climates, the amount of water saved more than offsets the costs of this solution, which notably also saves vast amounts of energy. And it enables mining to continue in areas of the world where access to water is extremely scarce and problematic," Todd Wisdom concludes.

Contact:

Todd Wisdom, Director of Tailings Solutions: Todd.Wisdom@flsmidth.com

New Mill Pulp Lifter is increasing capacity, uptime and wear life

SAG mill installations are the main workhorse in the majority of comminution circuits across the world. But with ever declining head grades, the need for higher throughput circuits has become evident.

To help miners address some of the challenges faced by SAG-based mills, FLSmidth has released a composite rubber and ceramic discharge head pulp lifter that increases SAG mill operating capacity with minimal CAPEX. The solution is designed to increase throughput, minimize downtime and extend the wear life of components.

“It represents a significant advance on traditional cast steel chrome moly pulp lifters,” explains Jack Meegan, FLSmidth’s Product Line Manager for Liners and Wear Parts. “Instead of cast steel, they are made of a combination of cut and fabricated structural steel, rubber and a ceramic matrix used for its exceptional sliding abrasion properties.”

The mill pulp lifter processed more than 28 million tons while improving slurry throughput by 6%. Our customer reached break-even at half of the parts’ lifetime and a throughput benefit to the order of seven digits USD in 12 months
— Jack Meegan, Product Line Manager for Liners and Wear Parts

Half the numbers of parts – half the weight

Fabricated materials weigh less than cast steel, and in some cases, FLSmidth has been able to reduce total lifter weight by 50%. Lower weight allows for the use of larger parts, which has reduced the number of parts that make up the discharge arrangement of the SAG mill by more than 60%. Fewer parts mean fewer liner handler movements during relining, reduced downtime and of course, cost savings.

The redesigned solution not only improves liner performance, but also increases wear life and lowers total replacement costs. The new design is also more robust and allows for effective operation under a wider range of operating conditions without risk of overloading the SAG mill.

With detailed analysis of the processing environment and an understanding of the specific wear mechanisms on the pulp lifters, Meegan explains how his team was able to propose an alternative design: "To increase the slurry rate we had to challenge geometric and operating restrictions. By evaluating mill diameter, head length, rotation, angle of discharge, length and height of pulp directors, grate open area and recirculation of the mills, we were able to simulate a number of alternative designs. We selected and quantified the benefits of each modification made to the existing design and incorporated them into a new mill discharge arrangement. This detailed analysis enabled us to adjust the shape and form of the pulp lifters and center cones for optimized flow and the lowest possible re-circulation of slurry in the assembly."  

For Meegan, the most interesting improvement comes from the optimized geometrical design features: "This was critical to the support we provided to a copper customer in Chile with a 40 foot diameter SAG installation. The mill pulp lifter processed more than 28 million tons while improving slurry throughput by 6%. Our customer reached break-even at half of the parts' lifetime and a throughput benefit to the order of seven digits USD in 12 months."

Contact:

Jack Meegan, Product Line Manager for Liners and Wear Parts: Jack.Meegan@flsmidth.com

A Silver Lining

When Fosterville Gold introduced new ceramic cyclone liners, it was not expecting this simple adaptation to impact on the entire value chain by paving the way for the use of smaller, smarter pumps.

Big is generally seen as beautiful when it comes to designing plant and equipment with the capability to deal with the huge tonnages of low grade ores that characterise many mining operations. Pump manufacturers have risen to the challenge, but not without process issues and problems, as Australia’s largest gold mine in the state of Victoria discovered. 

Owned and operated by Lake Resources, the Fosterville Gold mine poured its one millionth ounce of gold on January 7, 2016. It was a milestone that represented over 11 years of continuous operations with daily throughput averaging a massive 1900 tonnes each day

Originally, the mine needed the super-sized pumps that are typical to operations of this scale to handle the heavy recirculation load through the mill. This recirculating load was a result of over-expanded and worn cyclone apexes. Fosterville found itself facing a continuous – and expensive – maintenance challenge and sub-optimal operations.

With four cyclones in operation, the company was struggling to keep up with the rate at which the rubber underflow apexes were wearing out. Typically, each apex had worn from a diameter of 82mm when new to 105mm after just 672hrs, or four weeks of operations.

And after each fourth replacement, the entire cyclone had to be removed from service and rebuilt with new liners costing approximately $8000 in materials and $1000 in labour each time.

High maintenance costs were not the only problem. Fosterville found that the practice of replacing the worn apexes on a rotational basis introduced a protruding ledge where the new liner met the worn one above it, interrupting the flow of slurry through the cyclone. In particular, retained oversize material was inhibiting the dart plug operation and accelerating the wear of rotors and stators.

The worn apexes also allowed too many fine particles into the underflow which increased the recirculating load and unnecessarily accelerated the wear on mill components and discharge pumps. It also decreased the percentage of the underflow which could report to the flash flotation cell.

Fosterville thought there had to be a smarter way to manage their cyclones.

A smarter way to work

FLSmidth were invited to replace the cyclone liners with FLSmidth Krebs ceramic lined cyclones. These cyclones have underflow apex diameters that feature a lifespan up to twenty times longer than rubber versions. Maintenance takes place on an annual basis when the apex will generally have expanded to 95mm and the flow of slurry is much more consistent.

Moreover, the ceramic lined cyclones are supplied and fitted as a single complete assembly, abolishing the need for a separate stream of maintenance activity to replace just the liners.

“Once the cyclone ceramic liners were installed, the efficiency of the cyclone improved significantly because we were able to reduce recirculating load through the mill and mill pumps,” said Andrew Nash, Fosterville Gold Process Engineer.

In terms of improving the separation process, the overflow p80 sizing became more consistent and much less coarse material could be observed in the flotation cells during shut-down.

For Fosterville it represented a double hit. Maintenance costs and associated downtime were slashed with less wear to mill liners and mill process pumps.

“It is a great example of how a simple adaptation intended to reduce maintenance costs and the damage inflicted by high recirculating loads, can lead to other even greater savings in related processes and generate savings across the entire value chain”
— Adam Noble, Sales Engineer, FLSmidth Krebs

Smaller, more efficient pumps

“The benefit we originally envisaged for Fosterville was overall reduced costs of operation and less wear to mill liners and mill process pumps due to the reduction of recirculating load. But there was another, even more interesting impact on another process. The improved separation process made it possible to install smaller and much more efficient pumps,” said Andrew Nash, Process Engineer, Fosterville Gold.

FLSmidth Krebs were invited to install and convert two competitor pumps engaged in primary and secondary mill discharge duties with the Krebs millMAX 10x8-24.

Both pumps featured patented millMAX on-line suction side wear clearance adjustment technology which was developed exclusively for mill discharge duties and then adapted for other severe abrasive slurries.

Adam Noble, Sales Engineer in FLSmidth Krebs explains: “We refer to the Krebs millMAX technology as “zero downtime” impeller gap adjustment. It has removed the down time required for impeller, bearing assembly and pulley/ belt adjustments. This helps eliminate down time while ensuring optimum pump efficiency is maintained and achieved throughout the life of the pump’s wet end.”

The new Krebs Mill Discharge pumps have achieved longer operating hours, consume less power and offer significant cost reductions to the mill pump operations.

The pumps also feature fewer parts and mill discharge pump wet end rebuilds are completed quarterly allowing maintenance planning to reduce spares inventory this in turn helps reduce onsite networking capital

The success in achieving reduced operating costs has led to additional FLSmidth Krebs pump installations throughout the mine and overall savings of more than 40% across mill pump operations.

Finding synergies

Adam Noble believes that the ability to realize synergies such as those that exist between pumps and cyclones is intricately tied in to the company’s 100-year heritage as a supplier to the industry in Victoria and a deep technical understanding of the operational environment.

Fosterville Gold publicly acknowledged the contribution made to its business by installing a Krebs cyclone close to the commemorative plaque that celebrated its one millionth ounce. “I get a real sense of pride whenever I see it, says Noble.

“For me, it is a great example of how a simple adaptation intended to reduce maintenance costs and the damage inflicted by high recirculating loads, can lead to other even greater savings in related processes and generate savings across the entire value chain.”

FLSmidth Krebs were aware that the lessons learned in achieving process improvements for Fosterville Gold could be replicated elsewhere and had wider applications in other minerals and metals processing environments. “In any site where there is a need to process large quantities of rock and slurry whether it is related to coal, iron ore, tin, copper or another ore, the opportunity exists to learn from this example,” says Noble. 

Contact:

Adam Noble, Sales Engineer, FLSmidth Krebs: Adam.Noble@FLSmidth.com

Underwater camera can save 10% flocculants

A small camera system enables operators to avoid overdosing thickeners. That can save up to $100,000 per year in chemicals for a medium size plant.

Over-dosing is a common problem in thickener operation. It increases the operating cost, affects the downstream process and stresses the environment unnecessarily. A new tool has been developed by FLSmidth for real-time floc size monitoring and accurate reagent dosage control.

When flocculants are added to the slurry, particles agglomerate and the settling velocity increases accordingly, which leads to more efficient solid/liquid separation. Although larger floccules settle faster, they are however not always desirable and can sometimes inhibit thickener performance. To achieve the optimum floccules, the dosage rate has to be precisely balanced, and that requires sampling and settling tests. Such tests are not only time consuming, their results are very difficult to trust: "The slurry property and volume flow rate are changing so the characteristics at 10 am will have changed from the sample taken at 8 am – and slurry exhibit hysteresis so the act of sampling can itself alter the settling characteristics and affect the results," explains Technical Manager, Yihong Yang.

Now, an innovation from FLSmidth enables instant and accurate dosage adjustment: A small submersible camera is installed in the thickener feedwell to record floc images and analyze the floccule size in-situ and in real-time. Operators can use the floc images and size information to optimize the flocculant dosage on the spot.

Our ultimate goal is to increase productivity in the operation by making dosage control 100% automatic
— Yihong Yang, Technical Manager

The idea for the floc camera was ignited by the success of FLSmidth's E-DUC dilution technology; with the diluted slurry FLSmidth's R&D team was able to monitor the flocculation using a camera and developed a solution that could be combined with the E-DUC system to further improve thickener performance. The team tested the camera at customers and proved significant results.

“The floc camera system provides not only the floc size information but also other key characteristics, for example the structure. More importantly, the measurement is in-situ and real-time. With this device, up to 10% flocculants can be saved,” explains Yihong Yang. FLSmidth presented the Floc Camera at the SME conference in February in Denver.

Yihong Yang believes that the new tool will be widely adopted in the industry: “Our ultimate goal is to increase productivity in the operation by making dosage control 100% automatic."

Contact: Fred Schoenbrunn, Global Product Manager for ThickeningFred.Schoenbrunn@FLSmidth.com

How IoT can increase production

The mining industry is beginning to open its eyes to the potential of connectivity-based technologies. The Internet of Things (IoT), often defined as the convergence of information and operations technology, has sparked substantial interest, and with just an estimated five percent of mining operations currently making use of IoT, the potential upside is significant.

Applying IoT affects three factors: process optimisation (quality and throughput), maintenance strategies and utility consumption. Understanding the advanced sensing and the data analytics allows plant managers to make good decisions about balancing operations. Equipment may need to be pushed harder in order to meet quotas, but can also be slowed down if necessary.

“If a mine is pushing a lot of product through its equipment, inducing extra wear and potential damage, they could balance the trade-off between increasing revenue through the extra input and the increasing maintenance costs due to wear and tear on the machine,” said Greg Weaver, Global Product Line Director, Digital Solutions for FLSmidth.

In a crusher, for example, sensor data might indicate that the mantle has worn to a certain level. The system could then adjust the opening and operation of the crusher to maintain the desired particle size, even if the machine is somewhat worn.

Unplanned maintenance outages increase the pressure on maintenance teams and costs. The predictive aspect of IoT takes those worries away.
— Greg Weaver, Global Product Line Director, Digital Solutions, FLSmidth

Improving productivity in South America

As an example of how IoT can work in practice, Greg Weaver tells the story of a copper mine in South America that was experiencing premature wear on its mill liners: “FLSmidth installed an impact meter that measured the acoustics within the mill and then adjusted the speed and several other variables on the mills to optimise performance. Analysing the data provided by IoT, we saw an increase in production by 8.75 percent. The programme also lowered energy consumption by 8.7 percent and the number of critical impacts between the balls and the mill shell was reduced by 46.9 percent.”

All those benefits were accomplished through data analysis: “The process control system factors those parameters into data ecosystems, adjusting speed, feed rates, etc. The mill itself had 25 to 30 parameters that were analysed and adjusted for optimisation. This is far superior to anything that could be done manually.”

What data can do

The ability to manage and interpret data gives added power to process control systems. With access to more data, machine learning and historical information, process control systems are becoming more stable and rugged, but at the same time within reach. “The reason IoT programmes are now really starting to gain momentum is because of the decreasing cost of the sensor packages,” Weaver said. He points out that sensor technology and sensors costs are becoming so inexpensive that engineers can instrument equipment that could not be economically justified in the past.

But to truly benefit from IoT and the data-driven decision making it enables, it requires certain competencies within the organisation. “For an organisation to use and implement IoT, they must have a maintenance organisation able to harvest the benefits from the information provided, one that understands and acts on the information given,” explains Skage Hem, Vice President for Mining R&D, FLSmidth.

Compelling potential

FLSmidth develops solutions based on IoT technologies and provides them to mines on a customised basis, looking at specific needs and best way of implementation. Skage Hem explains that FLSmidth’s approach is about improving the performance of individual pieces of equipment, while also optimising the benefits of IoT across the entire plant:

“We can either provide the sensor packages or assist with interpreting key operational data. If a mine does not have access to the operational data, the first step would be to install the technology and then develop maintenance strategies around it and keep it on a practical level. Then we could begin to look at integrating data into process optimisation decisions.”

He emphasises the enormous potential of IoT, which is already being realised in several other industries. “There is a five to 10 percent cost reduction just waiting to happen and these would be big numbers for the mining business. And, the cost to implement is not at all proportional to the savings.”

Contact:

Skage Hem, Global Vice President for Mining R&D: SRHE@FLSmidth.com

Greg Weaver, Global Product Line Director, Digital Solutions: Greg.Weaver@FLSmidth.com

SmartCyclone delivers new opportunities for process optimisation

A unique combination of wireless and sensor technology brings condition monitoring capabilities to traditional hydrocyclone processes.

Condition monitoring is becoming increasingly important as a means of improving equipment and plant productivity. The SmartCyclone is a universal hydrocyclone conditional monitoring and encompassing process optimization solution, with a special focus on closed-circuit grinding optimization. Using process sensors with advanced control software, reductions in costly production interruptions and improved recovery rates can be realized.

SmartCyclone features include wireless wear detection and roping detection sensors, combined with process sensors such as cyclone feed pressure and valve status, that acutely measure the operating efficiency of both individual cyclones as well as the entire cyclone circuit within an 'island of optimization'.

“The SmartCyclone is the first control solution to target the closed-circuit grinding process with a dedicated automation philosophy.  Using wireless sensor technology, it helps optimise the flotation feed and maximise production,” says Jon Culbertson, Sales Director, FLSmidth Krebs.

An industry breakthrough

With a SmartCyclone-equipped process, the cyclone sensors can help indicate the functional state of the cyclone by monitoring the conditions of the slurry flow for each cyclone individually to optimize downstream particle size. This particle size distribution has a direct impact on the efficiency of downstream processes, such as flotation.  The sensors also report the wear status of the cyclone components, so that parts purchasing and maintenance operations can be planned with greater control. Finally, the sensors also report when a cyclone is experiencing an upset, such as 'roping' - a breakdown in the classification. 

SmartCyclone is pioneering a new segment of control solutions. It is one of the first to formally target the closed-circuit grinding process with a dedicated automation philosophy using sensors
— Jon Culbertson, Sales Director – FLSmidth Krebs

New opportunities for productivity

Using the SmartCyclone, plants can achieve maximum process efficiencies through quick upset condition identification and correction, resulting in less process downtime and reduced flotation feed variation leading to:

  • Improved mineral recovery
  • Stabilized cyclone operation
  • Continuous wear monitoring and management
  • Predictable cyclone circuit maintenance
  • Increased production capacity by permitting the process to be operated closer to the limits of the cyclone manifold design
The roping sensor is synced to the wireless handheld controller

The roping sensor is synced to the wireless handheld controller

Handheld simplicity

The new wireless SmartCyclone sensor system operates with a centralized, handheld wireless controller that can communicate with up to 16 wireless sensors per unit providing real-time detection and communication of roping and wear data from the SmartCyclone sensors for forwarding to the control room workstation.

The system’s handheld wireless controller unit allows the user to easily set operating parameters for any desired sensor. When the controller unit is reconnected to its docking station, it charges itself and communicates live operating data back to the control room.

The SmartCyclone solution comes in three levels of sophistication from a basic cyclone monitoring system to an expert system for incorporating additional sensors and control algorithms to maximize process throughput and further reduce variations in cyclone overflow particle size distribution.

Contact: Barry Buttler, Product Technology Manager, Cyclones: Barry.Buttler@flsmidth.com

On the hunt for vibrations

In the mining industry interest in vibration analysis is growing. Avoiding unexpected shutdowns is a simple way to increase productivity. Steen Christian Knudsen tells about FLSmidth's Smart Parts program.

In the old days, we used screwdrivers and fingernails – today, FLSmidth uses transducers and advanced calculation software. But the basic premise remains the same: as an audible fingerprint every machine in the world has its own unique vibration profile. Much like a physician listening to a patient's heart murmur, by listening to a machine’s vibrations, it is possible to predict and diagnose whether a bearing or a gear is in need of replacement or repair, and when.

With sensor cost reduced, increased power of computers, and the ability to connect to the internet everywhere – referred to by one of today’s popular buzz terms as the Internet of Things – the condition monitoring of machines is moving from offline to online.

Steen Christian Knudsen is Technical Manager overseeing FLSmidth's Smart Parts program: “We are creating some really amazing opportunities with the speed at which we can send vibration data and other data sets, and then correlate in many different ways with various operating parameters. It is now possible to know when to have spare parts delivered or have them printed in 3D, on site. Vibrations from rotating machines are especially useful in this respect, as they are so sensitive to changes in the condition of the machine.”

By augmenting human intelligence the software makes experts more effective and it enables us to constantly optimise operations
— Steen Christian Knudsen

Investment in condition monitoring and root cause analysis is well worth it; vibrations from rotating machines such as SAG mills can indicate changes in the condition of the machine, as well as help sort irregularities between those that are urgent repairs and maintenance versus those that can be monitored or addressed during planned shut downs at a later date. With $100,000 in lost earnings for every hour that a gyratory crusher lies idle, it is crucial to know the correlation between reduced operation and prolonged maintenance.

Intelligence augmentation

Monitoring equipment no longer need to be decoded on site, but can be analysed by FLSmidth from the cloud, where it can be accessed by vibrations experts anywhere in the world.

Using different mathematical software tools, the vibration teams carry out signal processing on the vibration measurements, typically by analysing the frequency of the vibrations, the amplitudes and modulations in the vibrations and the frequencies of the frequencies – the so-called cepstrum. This allows the vibrations specialists to analyse when a machine component needs to be scheduled for replacement, and how to operate the machine to get the optimal production until then.

In May 2016, FLSmidth entered into collaboration with General Electric to integrate vibration measurements into their Predix platform, which will allow customers to compare their equipments' vibration data with other parameters, such as temperature and flow.

“Now that will enable us to discover some highly interesting connections. The software is able to correlate measurements with one another, recognise patterns and get the equipment to operate accordingly. By augmenting human intelligence the software makes experts more effective and it enables us to constantly optimise operations,” says Steen Christian Knudsen.

“When I use my tools, I am simply simulating what our eyes, ears and brain are doing every second on a subconscious level. I break down noise into a fine collection of distinct sounds, each with its own pitch, timbre and strength; the specific sound pattern indicates exactly which part of the equipment or process is at risk of malfunctioning and to what extent.” 

“When I use my tools, I am simply simulating what our eyes, ears and brain are doing every second on a subconscious level. I break down noise into a fine collection of distinct sounds, each with its own pitch, timbre and strength; the specific sound pattern indicates exactly which part of the equipment or process is at risk of malfunctioning and to what extent.” 

Contact: Steen Christian Knudsen, Technical Manager, Global R&D, FLSmidth: SCHK@FLSmidth.com

 

In-pit mobility

More than half of the operating cost of mining is moving ore and waste around. So where autonomous trucks and drills are part of Rio Tinto's development programme, Vale's Serre Sul mine in Brazil has chosen IPCC. A conveying concept from FLSmidth, originally developed for oil-sands, is attracting attention.

Paul Emerson is not in doubt; in-pit crushing and conveying (IPCC) is not only the most efficient way of removing overburden it is a trend. Mining Magazine agrees; they awarded FLSmidth's Coffer Dam Concept, a concept for semi-mobile sizing stations, most innovative transport.

“Before the financial crisis the industry was in a rush to supplement their trucks with IPCC solutions; not to reduce the operating cost, but to increase production throughput, and reduce traffic congestion, in a period when availability of new trucks, and even more so tires and parts, was a challenge,” Paul Emerson admits. He is the Global Product Director for Minerals Material Handling solutions in FLSmidth and according to him, industry interest in low-energy transport is returning with renewed interest.

No hands no frills transport

The advantage of IPCC over traditional trucks is lower long-term costs. A single haul truck not only has a big up-front expense, but high operational expenses for tires, fuel and maintenance as well as a large supporting infrastructure and operating personnel. While IPCC also requires an up-front expenditure, the solution has minimal downtime and lost production – and the system doesn’t need constant monitoring. Fewer trucks also means less noise and dust pollution, less carbon footprint from lower energy consumption and related emissions, as well as a reduction in water consumption used for dust control. By reducing operating personnel and truck congestion in pits, safety is improved.

“For miners set on increasing productivity, transport costs are very prominent on the operational budget," Emerson explains. To increase productivity, miners must improve two of three variables: Capital investment, operating cost, and throughput: “It is tempting to increase throughput by adding trucks and shovels to existing fleets and infrastructure, but ignoring the long term operational costs will be detrimental in the new norm for the mining sector," Emerson predicts.

The Coffer Dam Concept

The Coffer Dam Concept, using semi-mobile sizing stations, is simple, low capital investment and operating cost-effective. The concept eliminates the need for costly retaining walls associated with large semi-mobile or relocatable stations. In essence, the concept is a system of specially designed and fabricated steel panels that make up a floor and retaining wall. These walls are erected within a simple key cut in a bench, and the earth is backfilled and compacted around it. The solution is designed to take all the associated loads of the earth and trucks feeding a semi-mobile station that is moved in using a crawler transporter after the box retaining wall and floor has been assembled.

Dual Truck Mobile Sizer is the only truck fed mobile sizer station developed in the market that can be fed by Ultra Class Mine trucks (400 ton payload)

Dual Truck Mobile Sizer is the only truck fed mobile sizer station developed in the market that can be fed by Ultra Class Mine trucks (400 ton payload)

Improved operating costs, environment and safety

  • Reduced downtime: Two low cost sets of panels can be used and alternated between moves, making downtime and relocation of large stations fast and effective.
  • Reduced costs: The cost of concrete retaining walls commonly in place at mine sites makes more frequent relocations of the stations cost prohibitive. Two sets of stationary retaining walls cost around 20% of the equivalent concrete set up, but are reuseable with every relocation. By reducing the number of trucks, costs for fuel, labour and maintenance associated with hauling material over long distances will also be reduced.
  • Reduced carbon footprint: Fewer trucks on site results in reduced dust and noise pollution, reduced fuel consumption and emissions, lower energy consumption and less water consumption (wetting of roads for dust control).
  • Improved Safety: By reducing trucks or replacing them with crushing and conveying systems, many safety incidents can be eliminated or reduced simply by having fewer truck operators on the roadways within, to and from a mine site as well as minimizing injuries related to truck maintenance and operation.
FLSmidth is commissioning this QB4 system at Cananea mine in Mexico for Groupo Mexico. The system is conveying 12,000 tph of crushed copper ore onto their permanent leach pad. This is the largest copper heap leachy stacking system in the world to date topping Radomir Tomic (11,500tph) also built by FLSmidth.

FLSmidth is commissioning this QB4 system at Cananea mine in Mexico for Groupo Mexico. The system is conveying 12,000 tph of crushed copper ore onto their permanent leach pad. This is the largest copper heap leachy stacking system in the world to date topping Radomir Tomic (11,500tph) also built by FLSmidth.

Contact: Paul Emerson, Global Product Director for Minerals Material Handling solutions, FLSmidth: Paul.Emerson@flsmidth.com

 

New wear liner increases wear resistance 15 times

FLSmidth has released a new patent pending wear liner product, FerroCer® Impact, which helps mining companies reduce production downtime.

Helgi Gudbjartsson, Global Launch Manager, FLSmidth: Helgi.Gudbjartsson@flsmidth.com

As heavy bulk materials pass from station to station in a minerals processing plant, processing equipment is stretched to the limits of its capabilities. The wear rate of components, typically in chutes and hoppers is very high. The cost of replacing worn down consumables makes up a substantial proportion of the total maintenance expenses, so anything that can be done to reduce wear and increase equipment lifetime will have a significant impact on operating cost. The right choice of wear protection can contribute significantly to reducing maintenance costs and equipment downtime.

Current practice for wear protection usually involves wear liners or panels, which are bolted or welded onto the equipment. Different wear liners are applied in different situations, depending on factors such as type of ore, drop height, material lump-size distribution, and angle of impact. Each wear liner has its own advantages and disadvantages. Common types include hard-metal liners, heavy-duty rubber or rubber/ceramic composite liners, each with their own strength and weakness:

High in density, metallic wear liners are heavy – up to 40 percent heavier than ceramic. The hardest metals are particularly expensive and difficult to work with. Furthermore, they have significant limitations when operating in either of the temperature extremes. While hardness is reduced at higher temperatures, impact strength is reduced at lower temperatures.

Ceramic wear liners can be difficult to attach to existing chute work, requiring special adhesives or suspension within an elastomeric matrix. They can also detach easily from the substrate if surface preparation is poor or if the adhesives and elastomers are incorrectly prepared. They are extremely difficult to cut and cannot be bent or formed.

Such challenges have had a significant impact on maintenance procedures and costs. A general issue facing the industry is the loss in production time because of wear liners frequently needing to be replaced and the time it takes to install new liners.

A typical example could be for material of a common ore, such as gold, copper or nickel, with a hard impact velocity of more than 7 m/s. In such a situation, the wear liner may have an average lifetime of one or two months at most. The replacement procedure can take a whole shift, putting the process flow on pause for several hours resulting in significant production losses.

With units of wear liners weighing anywhere between 20 and 40 kg apiece, safety is also a concern. A special lifting mechanism is often needed in addition to the scaffolding, allowing maintenance personnel to safely access the installation points.

Composite structure of steel and ceramic components

FLSmidth has developed a wear liner solution specifically to address the challenges of operating crushing equipment, particularly related to wear liner longevity and installation time as well as the safety of personnel involved.

A unique composite structure of steel and ceramic components, FerroCer® Impact provides the advantages of both ceramic and metallic materials. Combining the superior abrasion resistance of a ceramic with the strength, toughness and malleability of a metal, it handles hard and abrasive materials in medium to high impact applications.

Traditional metallic liners wear down too quickly and ceramic liners tend to crack or disintegrate. FerroCer Impact has been shown to increase wear resistance by a factor of up to 15 times compared with traditional wear solutions, depending on the ore type and application. This allows minerals processing plants to achieve a total cost of ownership less than half that of other liners.

Light panels

FerroCer Impact panels are lighter and less bulky than traditional metallic liners. Each panel comprises a number of ceramic inserts enclosed within a matrix of cast metal. The matrix protects the more vulnerable side faces of the inserts and ensures that only the wear face of the ceramic is exposed to material impact.

The tapered geometry of the ceramic inserts and corresponding holes within the matrix act to wedge the inserts within the matrix and prevent material particles and fluids from causing them to be ejected from the matrix.

This design also enables the remaining wear life of the ceramic inserts to be visually assessed. As the exposed surface of the insert is progressively worn away, its area and face width increase. There is a direct correlation between an insert’s face width and height so that the one can be readily calculated from the other. 

The FLSmidth FerroCer® Impact panel consists of a metal matrix and ceramic inserts

The FLSmidth FerroCer® Impact panel consists of a metal matrix and ceramic inserts

Ease of installation

The panels’ low weight (approximately five kilograms) and compact shape make them quick and easy to install using nothing more than standard hand tools. FerroCer Impact can be installed in chutes, hoppers, bins, guides, deflector plates or any place where bulk material is conveyed in a mine or minerals processing plant.

Outstanding performance

In one nickel processing plant, the FerroCer Impact panels were installed in a conveyor discharge chute downline from the primary crusher unit where the material drops six meters from one conveyor belt down to another one. The hardness of the nickel ore is approximately five on the Mohs scale. After installation, the plant has until now operated for 319 days (and still running), and it operated at full production of 900 mtph with lump sizes of up to 250mm in diameter. This was a big step up from the previous liner, which had lasted less than three weeks on average.

On a different site, FerroCer Impact panels were installed in a chute downstream from the primary crusher of a gold mine where the drop height is two meters and the lump size up to 400mm in diameter. The previous liner type, consisting of heavy-duty rubber bars, typically lasted no longer than six weeks. After the first 17 weeks in operation, the wear measurements taken on site indicate that the new FerroCer panels will last at least another 80 weeks, making them at least 10 times better than the previous liner solution.

Low total cost of ownership

Chutes and hoppers are amongst the most heavily threatened pieces of equipment in the industry. Like conveyor belts, solid handling equipment is exposed to extensive erosion and abrasion from excavated materials of varying sizes. The impact, trajectory and volume with which some of the material is transported through the chutes and hoppers can have detrimental effects on their structure. This can leave equipment affected by cracks, holes and wall thickness loss as a result. By extending service life FerroCer Impact answers an important need in the minerals processing industry. It combines long wear life, ease of installation and affordable pricing to achieve a total cost of ownership which is less than half that of other liners. Its low replacement rate results in greatly reduced lost production time for mines.

Read more at: www.ferrocer.flsmidthminerals.com

The picture is from industry trials where lumps of gold ore up to 400mm in diameter have been through the primary crusher and fall 2 meters through a transfer chute on to a conveyor belt. The FerroCer Impact panels have already outperformed the rubber/steel bars previously installed by 3 times and are nowhere near worn down.

The picture is from industry trials where lumps of gold ore up to 400mm in diameter have been through the primary crusher and fall 2 meters through a transfer chute on to a conveyor belt. The FerroCer Impact panels have already outperformed the rubber/steel bars previously installed by 3 times and are nowhere near worn down.