We are producing data like never before and machinery is now equipped with sensors that collect data about performance and environment. Efficiently utilising data for predictive maintenance is an example of how digitalization optimises performance and cost effectiveness.
Large gold deposits are becoming increasingly scarce, grades are declining in known reserves, and deposits are becoming increasingly complex to treat.
The race is on. The industry needs to discover more economically viable means of extracting gold from refractory, low-grade ores and thereby increase reserves.
Since 2012, there have been less than ten major gold deposits discovered globally. Looking at the five years prior to 2012, the number of major discoveries was nearly four times as high. In addition, close to one fifth of the global gold production involves refractory ores. While not all new discoveries are refractory, this indicates that it is becoming increasingly harder to find economically viable large gold deposits.
A need for technologies to treat smaller deposits Industry data show that the amount of gold contained in refractory measured and indicated (M&I) resources is approximately double the amount of contained gold in economically viable refractory gold reserves. The only reason that refractory M&I resources are not considered a "reserve" is that they do not meet cut-off grade for economic extraction.
“Lower processing costs reduce the cut-off grade, allowing more ounces to be processed economically. The only difference between a resource and a proven and probable reserve is that the former is uneconomic and no amount of additional drilling will ever make it economic,” says Peter Flanagan, FLSmidth SVP Executive Accounts.
It is capital intensive to process refractory gold ores with current technologies. Hence, the industry faces challenges with developing new efficient technologies to treat smaller deposits. The aim is to reduce processing cost to convert more resources to economically mineable reserves.
"There are a lot of undeveloped refractory gold deposits that have less than 3 g/t gold head grade, and some are coupled with small resources which translates into short mine lives. Currently, those assets have little to no value as greenfield deposits and need a steep change in technology to unlock value," says Flanagan.
Process low-grade stockpiles earlier for pre-treating refractory gold, the main objective is to oxidise the pyrite and arsenopyrite to liberate gold. Initially, the target is refractory gold-bearing iron sulphides where currently pre-treatment is the only solution to recover sulphide mineral matrix, locked inside the gold. To this end, FLSmidth has developed Rapid Oxidative Leach (ROL), a mechano-chemical pre-treatment process for refractory gold ores.
"When we have proven this technology successful, miners will be looking at a completely different life-of-mine plan; by lowering the cut-off grade, more ore will be converted into reserves, extending mine life." Flanagan explains.
FLSmidth’s ROL pre-treatment process is not merely applicable to new gold deposits. According to Peter Flanagan, there could be significant benefits to existing operations as well. "Many existing refractory operations have low-grade stockpiles that are waiting to be processed at the end of the mine life. By adding ROL pre-treatment to an existing operation, it could become viable to process low-grade stockpiles earlier, rather than processing them at the end of the mine life. Reducing the cut-off grade, you can move those ounces forward to generate cash flow earlier and this will increase the asset’s net present value," says Flanagan.
The ROL pre-treatment process technology can be a breakthrough for the gold industry, displacing current refractory processing methods and prolonging mine lifespans.
Concentrator design has a large impact on the flow in production because oversizing in one area will push problems downstream. The challenge is to strike the right balance between equipment flow and recovery of concentrate ore grades.
One way to overcome bottlenecks is to include a consistent design factor throughout the engineering process. This requires solid knowledge of the ore, open and transparent cooperation and sharing of expectations between the mine owner, engineers and equipment suppliers. Setting the design criteria based on shared expectations and common ground enables the parties to design a solution with focus on total cost of ownership, rather than lowest capital investment.
“A consistent design factor on all equipment might mean a slightly larger initial investment. However, it is much more costly to shut down operations and replace undersized equipment at a later stage. The primary reason for focusing on the design factor in comminution is to accommodate periods of harder ore, where the circuit otherwise is designed to process at average rates,” says Dave Rose, Global Process Director for Concentrators at FLSmidth.
For instance, a copper comminution circuits in the range of 100,000 t/d typically have a design factor of 15 percent and this design factor often leads to a production of 115,000 t/d. Consequently, this creates bottlenecks elsewhere in the production line.
Keep it floating
To make sure that the design criteria meets the need of the specific mine - and that all equipment meet these criteria, too - FLSmidth has the advantage over most suppliers by being a full flow sheet provider.
“Since we develop, supply, install and maintain all the necessary equipment and workflow, our customers are sure that all equipment function well together and are sized according to the needs. To meet their needs, we continuously develop new equipment or make improvements on existing equipment, for example our new nextSTEP™ rotor/stator flotation device. Dewatering circuits are generally pretty forgiving on the performance if oversized, but are extremely unforgiving if undersized”, says Rose
The balance between the percent solids, the head grade and the recovery grade is essential. Using too high a design factor in the flotation circuits can introduce other concerns, including recovery and concentration grade because of the change in retention time in the cells.
“While rougher flotation may have high grade and recovery, the cleaners may exhibit negative performance because of higher tonnage rates or higher grade feeding into the cleaners than what was designed for. The volumetric balance is very important. We regularly visit plants where the ore head grade is high and a properly designed flotation circuit is underperforming because the ore does not match the design criteria provided for the circuit. The big challenge with higher head grade is not overloading the cleaner circuits. Concentrate grade may be better but the recovery will be lower, as there are higher value minerals lost in the circuit,” he says.
The best design is made by considering various scenarios in a step-by-step manner through the flowsheet, starting with the comminution circuit. The design has to combine the ore and mineralogy characteristics with the client’s expectations.
The next step in the process is recovery, which has to include consideration of the ore grade, recovery variance, as well as operational conditions, such as slurry, density, reagent addition, etc. Next to consider is the variation in recovery and feed rates to determine the best option for sizing of the dewatering equipment.
Lowest power consumption flotation technology on the market
The nextSTEP rotor/stator from FLSmidth reduces power requirements by 15-40 percent and has a better wear distribution, which therefore increases the life span and reduces the total cost of ownership. With reduced OPEX through energy efficiency and significantly improvement of recovery rates and concentration grades, the nextSTEP™ rotor/stator is a step change in flotation.
It is possible to retrofit the nextSTEP rotor/stator into existing flotation cells up to 660m3. The conversion process is simple, low risk, for all makes and models, and proven already with a large number of successfully completed retrofits for flotation cells ranging in size from 5m3 to 250m3.
Key benefits of the nextSTEP™ rotor/stator** • Significant improvement in both metallurgical performance and energy efficiency • Lowest operating power of any mechanical flotation mechanism on the market • Dramatic improvements in attachment rates, which translates into significant recovery increases • Better wear distribution increases product lifecycle and improve total cost of ownership • Designed to be retrofitted in all forced air machines, regardless of make or model
Dave Rose, Global Process Director, Concentrators
Fast start-up, reliable operations and the potential to increase pit-to-plant productivity are some of the likely customer benefits following FLSmidth’s recent acquisition of part of Sandvik Mining Systems.
With the recently finalised acquisition of the Sandvik Mining Systems projects business, FLSmidth has become a single technology provider of full flowsheet technology to the mining industry, with the ability to deliver fast start-up and reliable operations to customers.
The acquisition means a wider range of the customer supply chain, from primary crushing to tailings handling, can be covered by FLSmidth. However, it is more than just technologies; additional expertise for continuous surface mining, in-pit crushing and conveying (IPCC), and minerals material-handling technology is now available to the customer through the expanded FLSmidth offering.
“Our customers will benefit from the most comprehensive combined product portfolio in the industry, and they will be able to increase the productivity of their complete ‘pit to plant’. By knowing what will be coming into processing, we can help bridge the gap between pit operations and the processing plant, thereby increasing overall process efficiency,” says Paul Emerson, Global Product Director for FLSmidth’s Mining Material Handlings systems.
A single supplier optimises productivity
There are numerous advantages in choosing a single supplier. A key element is that maintenance and technical support can be streamlined, which can increase time and cost efficiency. For instance, should a problem arise and the root cause is difficult to identify, it is a clear advantage to only have to enter into dialogue with a single supplier, who can effectively deal with all issues, rather than having to engage with a host of different suppliers. The daily benefits include more clearly defined responsibilities, reduced total cost of ownership and improved productivity.
“In the past decade, mining corporations have gone to great lengths to reduce CAPEX, but currently we see focus changing to total cost of ownership. Especially on greenfield projects, In-Pit Crushing and Conveying can reduce the total cost of ownership as it reduces OPEX and truck costs. Ignoring the long-term OPEX is detrimental in the new norm for the mining sector,” says Emerson.
Another benefit for miners is that a full flowsheet facilitates digital access to all key processes and equipment. “We can now digitalise the entire supply chain to provide pro-active condition monitoring and data collection, identifying damage or wear ahead of any failure, even on mobile IPCC and stacking equipment. The data can be benchmarked with best practise and used to optimise the production. We keep investing in being on the forefront of IPCC systems and Dry Tailing Stacking technologies going forward. This will allow customers to reduce total cost of ownership and increase throughput in order to increase their productivity,” says Emerson.
Paul Emerson, Global Product Director
Reduced flocculent consumption and improved operational performance are the results of a thickener upgrade at a large Australian gold mine.
A leach feed thickener was creating a bottleneck in a gold mine in Western Australia. The installed thickener was a preinstalled ‘off-the-shelf’ product, neither supplied nor installed by FLSmidth. As the on-site maintenance contractor, the client asked FLSmidth’s team of specialists to assess the performance and offer a solution to improve productivity and overall performance. As a result, FLSmidth’s engineers identified several improvements to the thickener’s control set-up.
"The customer realised their feed system was under-sized and hampered by air entrainment. The density-reliant dilution system meant that the feed stream was not being diluted, resulting in high flocculent consumption, poor overflow quality and lower than desired underflow density," explains Dane Smith, Dewatering Product Manager at FLSmidth.
Following test work, a process review and structural analysis of the bridge and thickener tank, the FLSmidth team recommended a combination of the E-DUCÒ feed dilution technology and the E-Volute™ feedwell. The E-DUCÒsystem uses feed stream momentum to induce large volumes of feed dilution prior to the feedwell, thus optimising flocculation due to improved mixing profiles and residence times.
The E-Volute feedwell is characterised by excellent feed stream energy dissipation, optimal mixing energy and shear profiles. Subsequently, it promotes even feed distribution into the thickener with minimal floccule breakage, therefore improving the overall sedimentation performance.
Reduced installation time
Specialists at the FLSmidth Supercentre in Perth completed the project from on-site test work and inspection, to process and mechanical design, fabrication of all components, installation, and finally, commissioning. No other Original Equipment Manufacturer (OEM) has the ability to provide such a breadth and depth of service.
“Having control of the project meant we could keep to the required tight delivery schedule, while remaining in control of quality and planning on-site. This ability helped to shave three full shifts off the installation, allowing the site to return to full production far earlier than they had thought possible,” says Smith.
The results are convincing
Initial data analysis shows a reduction in flocculent dose of approximately 34 percent and an increase in underflow density by approximately 2 wt. percent during the first two months.
As the plant continues to optimise the new system under FLSmidth’s recommended control setup, flocculent savings are maintained and underflow densities have increased up to 8 percentage points from 48 wt. percent to 56 wt. percent (6 percent on average), limited only by the rake drive torque.
In addition to the achieved flocculent savings, the increase in leach feed density reduced total volumes reporting to the CIL, the minerals recovery process, by around 16.5 percent. Decreasing cyanide and lime requirements while significantly increasing available leach residence time, promoting gold recovery.
The results are such that the 34m leach feed thickener with FLSmidth technology is producing higher densities than the 44m tailings thickener with non-FLSmidth OEM technology.
Dane Smith, Technical Advicor, Dewatering
The 2018 Society of Mining, Metallurgy and Exploration (SME) Annual Conference & Expo provided a forum for more than 6,000 industry professionals from across the world to share innovative ideas, best practices and cutting-edge research in more than 120 technical sessions along with an expansive marketplace of more than 550 exhibiting companies, including FLSmidth.
The SME conference is one of the most important regional opportunities to network with industry customers and suppliers. It also gives a good sense of our competitor’s current positions in the marketplace. According to Joe Dziedzina, FLSmidth Product Manager, HPGR “Due to breadth of attendee types, the event helps provide a real feel for the pulse of the industry.” During the week, booth presence was active and several potential projects were identified.
FLSmidth was event sponsor
FLSmidth served as sponsor for the debate session, which included a several speeches and a panel discussion on the importance of a diverse and inclusive workplace as key driver behind productivity, profitability, emerging innovations and technology advancement in mining.
Demonstrating industry leadership at SME Technical Sessions
Several technical sessions took place during SME, wherein the mining industry's best and brightest gathered to share their knowledge, experience and expertise. The session topics covered some of the most current, relevant research in the industry, and illustrated innovative solutions to many common mining challenges.
On behalf of FLSmidth, Dave Rose served as a session chair on the topic of plant design. During the session, a white paper co-authored by Dave was presented by Jesus Gonzales from Pena Colorada, a close customer of FLSmidth. The paper summarised years of collaboration on throughput expansion, which resulted in the addition of a second comminution circuit at the Pena site.
Dave states, “This site is an important project for FLSmidth. In the many years of working closely with this client, we have installed several pieces of equipment during this expansion, including a SAG mill, ball mill, cone crusher and gyratory crusher, required for the throughput expansion. In addition, we added one new thickener and retrofitted four existing thickeners at the site to accommodate the extra tailings generated by the higher throughput.”
Leadership in developing large-scale tailings filtration
Todd Wisdom, Director Process Line Tailings Systems, presented on Large-Scale Filtration Demonstration Plant. The paper highlighted FLSmidth’s continuing leadership in developing large-scale tailings filtration a viable economic and technical option for large scale mines.
“Through recent advancements in filtration dewatering technology and scale, we are making filtered tailings economically viable for large mines. In presenting these results at SME, our goal was to demonstrate FLSmidth’s industry leadership in improving the sustainability of mining, which is has been increasingly important in the eyes of the general public,” says Todd.
Peruvian mining company Volcan Compañía Minera installs paste thickeners and doubles its capacity in six months.
In the thin air of Cerro de Pasco, high in the Peruvian Andes Mountains, Volcan Compañía Minera’s processing plant more than doubled throughput in six months. The plant now exceeds its original design capacity of 2,500 tonnes a day – and can process as much as 3,000 tonnes. However, half a year earlier, the oxide plant was underperforming as it only managed a throughput of between 900 and 1,200 tonnes of gold and silver-bearing oxide ore per day.
Juan Manuel del Aguila, project engineer at Volcan, and his colleague Luis Loaiza collaborated with FLSmidth’s team in Peru to find a solution to improve the process of recovering silver via cyanide. Volcan’s team of engineers travelled to Salt Lake City, Utah to perform further tests at FLSmidth’s facilities.
“The initial tests in Salt Lake City resulted in a large filtering area, but we also carried out parallel tests to explore other options. It turned out that we could meet the objectives with the EIMCO® Deep Cone® Paste Thickeners. We returned with these results and carried out onsite tests at Cerro de Pasco,” says Manual del Aguila.
“Our engineers installed a pilot thickener plant at the site and after twenty days of testing, we found that it would increase the tonnage at the plant. This allowed Volcan to meet their capacity needs. A solution that required less time and less capital than applying additional filters,” says Walter Gamero, Senior Process Engineer at FLSmidth, Peru.
Cooperation fast-track the process
Volcan awarded FLSmidth an EPC contract to supply two Deep Cone Paste Thickeners, including the required tanks, piping, pumps valves instrumentation, control boards, cables, motors and control system . Only a week after operation, the Volcan oxide plant exceeded its original design capacity of 2,500 tonnes a day.
“We are not limited to just supplying the equipment with a mechanical guarantee but can also apply business models providing guarantees on the performance of the equipment in terms of volumes, availability.” says Gamero. By excessive cooperation between Volcan and FLSmidth, the process was fast-tracked and a success.
Leading test facilities
To find the optimal solution for Volcan Compañía Minera’s processing plant, engineers from Cerro de Pasco travelled to FLSmidth’s R&D centre and test facilities in Salt Lake City, USA. Here, FLSmidth offers leading test expertise in precious metals, base metals, and industrial metals.
The facilities include crushing, grinding (including ultra-fine grinding capabilities), gravity separation, hydrometallurgy (ambient and autoclave technology), column leaching and flotation. Flotation equipment includes mechanical test cells from 50 grams to 15,000 grams capacity. The laboratory also offers in-plant consultation services and plant auditing.
Walter Gamero, Process Engineer
FLSmidth is staying on to help a mine in Armenia faced with accusations of causing environmental and social impacts. Active involvement has a greater long-term impact on sustainability than abandoning a site and leaving the problems with the client and the local community.
In 2013, FLSmidth was hired to engineer and provide equipment for a mineral processing facility for a copper mine in Lori province near Teghout in northern Armenia, partly funded by Danish institutions. The equipment supplied for the project was of the highest standard regarding environmental impacts. Local residents and non-governmental organisations raised issues about the construction and operation of the mine, mainly with regard to pollution of rivers; the felling of forests that are home to endangered species and accusations of exploitation of small farmers whose land was expropriated under allegedly questionable circumstances.
In 2017, this came to a head when a Danish non-governmental organisation levied unsubstantiated accusations against the mine operator and FLSmidth. This led to public scrutiny of those involved and caused the withdrawal of the financial guarantee, although this did not contribute to resolution of the concerns. As a supplier to the project, FLSmidth chose a rather different approach. It was well understood from the beginning that pulling out of the project meant leaving it for the customer and the locals to deal with the problems alone. FLSmidth refused to do so, even though the issue under scrutiny (mine and tailings facility) were not in scope of FLSmidth.
“We decided to stay in the area and attempt to make a positive difference by applying our expertise. We believe you can make more of an impact by being present on site, as long as there is trust in the relationship and the aim to solve the problems at hand. We are in regular dialogue with our customer on how best to assist them with their challenges and thus make a positive difference in the area,” said Manfred Shaffer, executive vice president of the minerals division.
ESTABLISH EFFECTIVE COMMUNICATION CHANNELS
As supplier to the project, FLSmidth expects that the customer will take the necessary steps to address and improve conditions surrounding the mine and processing plant. By leveraging the relationship with the customer, a dialogue was immediately established, by the project manager and escalated within the organisation. This allowed proper communication channels to be established at the right levels to review options for overcoming the challenge.
Furthermore, FLSmidth engaged some of the financial parties to identify what their concerns were, prior to their withdrawal. This allowed for a full understanding of the stakeholder expectations. The unsubstantiated claims were discussed directly with the non-governmental organisation and the journalist who levied the accusations. FLSmidth ‘s role was made clear, as well as where the legal responsibilities of each party lie, and how FLSmidth went beyond the legal boundaries to address and support a resolution of the issues.
CUSTOMER: TEGHOUT CJSC
FLSmidth: delivered design, machinery and supervised the construction of the mine facilities, all above ground
Finance: Denmark’s Export Credit Agency (EKF) provided the financial guarantee, and The Danish pension fund, PensionDanmark, partly provided the financing with DKK 350m by extending a loan arranged by a French bank to a Russian bank for further on lending.
Major risks: An identified potential risk to the customer is that the nearby dam, built to stem the flow of liquid waste from the mine, might collapse should a major earthquake strike the area. In 2016, the World Bank published a study on the mineral sector in Armenia, showing that none of the 21 tailings dams reviewed had the appropriate design or management for a seismically active area. Teghout CJSC is currently reviewing the risks and solutions based on the International Commission on Large Dams standards, and has committed itself financially to implement the proposed solution.
- 2008: Order for the mills and grinding area, with associated plant engineering
- 2011: FLSmidth receives order for the balance of equipment and plant engineering
- 2014: All engineering of the plant was done in accordance to local codes and standards and put into operation
- 2017: Financing was withdrawn
Read FLSmidth's 2017 Sustainability Report
Alexander Campbell, Group Sustainability Manager, ARC@FLSmidth.com
By analysing the sound and other process parameters, SAGwise™ adjusts mill load and decreases steel-on-steel impact, resulting in less energy consumption and increased production.
Operating a SAG mill is a costly affair. Yet, a SAG mill is most costly as when it stand still. Therefore, being able to predict the right mill load optimises the output and minimise repairs and standstills is of utmost importance.
Today, experienced plant operators depend on the personnel close to the SAG mill listening to the mill load for critical steel-on-steel impacts. If critical impacts occur, they manually adjust the SAG mill load to make the mill run smoothly. Though this is a qualified way of handling critical impacts, a new digital solution utilises acoustics sensors to reduce downtime and increase the mill’s reliability and productivity.
Acoustic sensors optimise SAG mill operation
The new FLSmidth SAGwise™ process-control uses acoustic sensors and proprietary process control software to predict and adjust the SAG mill operation according to impacts on the mill and other main process variables. The acoustic sensors ensure regular and accurate adjustments to mill loading.
The solution employs state-of-the-art process-control technologies to reduce critical impacts to the desired targets; stabilising and optimising the SAG mill’s operation. The solution embeds multiple process-control technologies, modelling both the process and the human operators.
“Within seconds, SAGwise can analyse audio frequencies as well as on board power usage, mill weight and bearing pressure. It can then automatically take corrective action if needed and adjust parameters such as the mill ore feed rate, mill speed or slurry density. Where an operator might make adjustments every few minutes, this solution can make less drastic adjustments more frequently, down to every 20 seconds or less,” says King Becerra, Global Product Line Manager for Automation Process Optimisation.
Test results show that these adjustments reduce damage to the liners by up to 40 percent. This means less unscheduled downtime and increase in production.
“The one sound operators do not want to hear is the sound of the mills standing still. A gold-processing plant, I visited recently valued their SAG mill downtime at US$ 130,000 per hour, so extending the life and availability of mill liners is crucial to them. The reduced damage improves the mills availability and minimises the down time. This can translate to literally millions more tonnes of ore milled,” says Jack Meegan, Global Product Line Manager for Mill Liners.
ROI in six months
“We want to make sure that our customers are getting more value from their liners as well as from their media. With many mines using $10 million or more on liners per year and 3 or 4 times this cost in terms of grinding media, the savings can be huge,” says Meegan.
Test results also show a reduced energy consumption of up to six percent. Considering that mills are the largest power consumer in minerals processing, this is quite significant. Furthermore, the new solution resulted in a six percent production increase and reduced process variability by up to 30 percent. With these savings, SAGwise can pay for itself within six months or less.
How does it work
Audio sensors close to the SAG mill listen for undesirable high-energy critical impacts. Intelligent software analyses the patterns and adjust feed, speed and pulp density for optimal efficiency to decrease power usage, reduce critical impacts and preserve liner life.
- Increase liner life
- Decrease critical impact by up to 45%
- Up to 6% reduction in grinding specific power consumption
- Up to 30% reduction in process variability
- Minimised downtime
- Reduce ball consumption
Automation systems are more accurate than any person ever can be. By automating berth stockyard operations, BlueScope Steel cuts operational costs, maximise stockyard area utilisation, boost throughput and hedge against uncertainty.
Despite the potential for digital automation to make operations far more efficient, past experiences with automation projects going over budget or overshooting deadlines created hesitation in the mining industry.
BlueScope Steel commissioned the BulkExpert™ automation system, a 3D scanning technology, at its Port Kembla stockyard in Australia, three years ago. The initiative has provided BlueScope Steel with valuable experience to help shape their future automation projects.
When lump ore and fines unload from a ship, they are stacked to the primary or secondary yards with large volumes of iron ore in continuous transit. Each incoming capsize vessel carries another batch to be unloaded and reclaimed. The average turnaround time is 7-10 days for the mixing bed.
When the stacking operation is down, it limits the offloading operation and ships have to stay at the berth. This potentially increases demurrage charges the longer the cargo stays on the terminal.
"Process control and stability at maximum feed rates are some of our key metrics, hence our stacker reclaimer operations were identified as an area of opportunity for automation," says Derek Sheppard, maintenance and asset development manager at BlueScope Steel.
The company considered different options, ranging from complete replacement of the massive machines, which date back to 1974, to simply refining existing processes.
"We determined that upgrading our existing stacker reclaimers was the best option in terms of return on investment. This allowed for automated operations based on orders entered by engineers from a control room environment," he explains.
The old machines with original electrical equipment showed significant corrosion from working in harsh environments. To find the right solution, BlueScope Steel assessed the capacity of the machines and determined that the design throughput rate was sufficient and compatible with the rest of the materials handling equipment.
Sheppard says, "After factoring in restoration, we explored options for automation in order to help ensure repeatability of processes, and that our equipment would operate within design parameters."
For BlueScope Steel, shipping discharge rates and utilisation of stockyard are areas where automation realises significant operational efficiencies. Even though, the payback of less than 18 months is convincing, BulkExpert also provides data on the equipment performance, which can reduce or prevent overload or damage, such as to conveyor belts.
"We knew that operational damage did occur, but we didn’t know the extent to which it was happening until we saw the outcome of automating. It was a revelation to us," Sheppard admits.
In preparation, BlueScope Steel had met with other BulkExpert customers to understand the full scope of the benefits, some of which are difficult to quantify.
Besides significantly reducing operating costs, improved throughput and the reduced risk of demurrage, other benefits include well-structured stockpiles and real-time accounting of stock inventory levels. Automatizing the stockyard reduced flowrate variances by >40% and stacking/reclaiming throughput increased by 90%: from 10-12,000 to 19,000 tpd.
Keep focusing on profitability
Port Kembla, like all integrated steelworks, faces the ongoing challenge of achieving and maintaining manufacturing efficiency to remain profitable throughout the commodity cycle. Sheppard sees automation as the route to ensure effective operations and hedge against uncertainty. "Additionally, labour also adds a significant cost and will always have to be managed to ensure that manufacturing remains cost effective."
The choice between automation versus manual operations inevitably comes down to a financial ROI with efficient, complex and repeatable manual operations having greater longevity over the contrary, according to Sheppard.
"As technology develops and pricing becomes more affordable, the opportunity for digitalization and automation increases. You need to bring the operation to such a profitable level that you are not worried what the steel price will be tomorrow," he adds.
Spot price trading with real-time inventory survey
BulkExpert™ gives a real-time overview of the stockyard inventory, allowing for spot-price trading. With precise data to the decimal on the stock at any given time, companies can either replenish their stock or sell exactly when and where the spot price is right. Currently stock is guesstimated on a weekly basis, making it impossible for companies to sell/buy strategically
Bauxite, coal, iron ore, limestone, quartz, sinter, coke, gabbro, urea, ammonium nitrate and phosphate are some of the commodities handled by BulkExpert systems
Rasmus Stefansen, Global Product Line Manager, Bulk Handling
Even a small saving in operational costs over the life of the mine can often justify higher capital investment up front. The mining industry will realise benefits from shifting its cultural mindset from focus on initial capital investment to total cost of ownership (TCO).
We all know it from when we buy household appliances – the cheapest option is usually the most expensive in the long run due to break downs, repair bills, electricity costs and the shorter life time of the equipment. This also applies to the mining industry - except the numbers are a lot bigger.
“Mining corporations are aware that their operational costs by far exceed their capital costs and that a small reduction of operational costs can justify a much larger capital investment. Yet for many reasons, we still see customers happy to implement cheaper, lower quality equipment into the flowsheet and accept the higher operating costs that go with it. To maintain productivity in the industry, we need to create more awareness and change this mindset,” says Michael Woloschuk, global industry director of gold at FLSmidth.
Better performance and no unscheduled stops
There are several reasons why higher capital investment can reduce the total cost of ownership during the lifetime of a mine. Firstly, original equipment is more robust and achieves operating hours per year, increasing annual throughput. Higher quality wear parts and the rise in digital equipment monitoring and performance measurement technologies has led to predictive maintenance and optimisation of performance. Furthermore – just like with the household appliances – quality OEM equipment also has lower energy consumption. During the lifetime of e.g. a SAG mill this has a significant impact on the bottom line.
“The big bang for your buck is to increase productivity and in potential revenue generation, higher recoveries, higher throughput, and higher equipment availability. For a gold plant producing about 280,000 ounces per year, simply increasing plant availability by three and a half days annually results in some $3.5 million in added revenues every year at the current gold price. ” says Mike Woloschuk.
FLSmidth agrees with other OEMs that miners will profit from this long-term perspective rather than focusing on short-term gains. Read an interview with Michael Woloschuk and representatives from Outotec and Metso on the subject in CIM Magazine.
Michael Woloschuk, Global Key Industry Director, Michael.Woloschuk@FLSmidth.com
Utilizing EcoTails™, jointly developed by Goldcorp and FLSmidth, Goldcorp aim to take a large step towards reusing maximum water and eliminating wet tailings dams. Watch VP of Goldcorp explain why EcoTails is a cornerstone of their Towards Zero Water (H2Zero) initiative.
The world’s fourth largest gold miner, Goldcorp, aims to dramatically reduce fresh water consumption and ultimately eliminate conventional slurry tailings. The EcoTails™ process and associated fast filtration and stacking technologies developed by FLSmidth are the key enablers. A key step in that process is the introduction of the filter technology EcoTails™, jointly developed by FLSmidth and Goldcorp.
“EcoTails truly has the potential to reduce the environmental impact of the mining industry, and we are proud to work on this project with Goldcorp’s Towards Zero Water strategy,” says Todd Wisdom, director of tailings systems at FLSmidth
Sustainable waste management
EcoTails is a new way of thinking about mine waste management and water conservation. In essence, it blends filtered tailings with waste rock in transit and this creates a geotechnically stable product called GeoWaste™.
When blended properly, GeoWaste is easy to convey and has a high strength when stacked. EcoTails™ and GeoWaste makes dry stacking possible for large scale mining, even in areas with high seismic activity. In many instances, it is both economically and environmentally a competitive solution to wet tailings dams.
An industry-wide solution
Goldcorp and FLSmidth collaborated closely to develop and test EcoTails™. Currently, the project is undergoing a prefeasibility study due for completion in the first quarter of 2018, and as a parallel track, it is being developed as a potential solution at one of Goldcorp’s mine sites where water resources are scarce and valuable.
“The results are very promising, and I believe that when we have fine-tuned and proven the technology, we will see the solution implemented across the industry. It makes mining safer and more sustainable without increasing lifecycle costs. Right now the lifecycle costs for an EcoTails solution are close to those of thickened tailings and dam solutions,” says Todd Wisdom.
Increase productivity by reusing up to 95 percent of process water
The EcoTails solution makes it possible to reuse 90 - 95% of the process water, and since water is a large operational cost, this alone will significantly reduce total cost of ownership for many mines around the world.
“This is the essence of sustainable productivity improvement: miners are challenged by investors to deliver good returns that are also environmentally and socially responsible. Water management will be the limiting factor for many mines in the coming years. With less risk and more water recovered, EcoTails is competitive on a total cost basis – that should be interesting for the industry at large," says Todd Wisdom.
Todd Wisdom, Director of Tailings Solutions: Todd.Wisdom@flsmidth.com
Plant managers rely on FLSmidth’s PlantLine™ Service Agreements to help improve productivity and reliability
In order to achieve maximum value, performance and reliability from their process and quality control systems, plant managers in 180 cement and minerals plants around the world are turning to FLSmidth and their PlantLine™ Service Agreement.
PlantLine Service Agreements provide plant managers with 24/7 access to a remote support team who provide a high priority response as urgent issues arise, as well as routine support, maintenance and training.
In the video below, you will meet some of the managers who have established a PlantLine Service Agreement, and will learn of the value it delivers.
“Because of PlantLine, our system reliability improves and we get prompt service on time… with 24/7 support you can call any time and they give you immediate support.” KPC Limited
“We have the service agreement to increase our production, to reduce our costs and to reduce our downtime. At the end of the day, we’re getting a very high synergy. This is the target.” CRH Group
LiveConnect™ Go2FLS technology is the backbone to FLSmidth’s PlantLine™ Service Agreements. It’s a state-of-the-art system that facilitates secure, remote access to critical plant systems, via the internet. Go2FLS recently celebrated its 10th birthday – that’s 10 years of outstanding remote service, troubleshooting, and engineering and commissioning support from a team comprised of up to 50 simultaneously-working supporters.
New skip discharging mechanism for vertical shaft mines increases ore hoisting capacity while reducing maintenance cost. With a significantly lower total cost of ownership the Crank Type Dump Mechanism (patent pending) is a unique alternative to hydraulic actuated systems.
The hoisting system is the heart of the business for underground mines; if the hoist malfunctions, production comes to a halt; therefore simplicity of maintenance is as crucial as operational reliability.
When a mine is designed the hoisting system is designed with a capacity exceeding the mine's expected throughput. The lifespan of the mine is however often decades with plenty of parameters changing over the years from ore quality to the depth of the mine; even on a daily basis there are variations in throughput. The daily average very rarely is linear. This means that the designed capacity of the hoisting system might meet the average throughput, but not the peaks. A hoist completing one cycle is lifting one skip from 900 metres up to ground level in 120 seconds; if the underground mining production exceeds the hoist capacity by 5% for a peak lasting a couple of hours then a bottleneck is eminent at the hoist system.
If it is repetitive and mundane; simplify!
While the majority of underground mines are operated with a traditional scroll discharge system for skips, the shaft system of new mines is designed with far more efficient hydraulic or pneumatic discharge mechanisms.
Mechanical design engineer in FLSmidth, Francois Koekemoer, explains that it was the frustration of looking at the various types of solutions that are currently on the market that gave him the initial impetus to develop a far simpler alternative: "Two years ago I was looking at a hydraulic design for a hoisting system at a platinum mine in South Africa - it just seemed too complex and costly to convert electrical energy via hydraulics into linear motion for such a mundane repetitive task of opening and closing a skip door; a large oil reservoir is required and a comprehensive list of multiple control valves, accumulators and coolers all add up to specialized maintenance, fire hazards and increased capital expense. Surely it must be possible to design a more cost effective solution, I thought. Initially I went for a rack and pinion gear design that led to a crank motion concept that would be ideally suited. I then sketched out some concepts and when I had the Crank Type Dump Mechanism (CTDM) I knew it was solid," Koekemoer explains: "The velocity and torque profiles generated by the crank motion are perfect for this particular application, where the opening and closing of a skip is required. Where possible the design makes use of standard components, such as motor and gearbox, which are off the shelf and not bespoke."
Payback of less than 6 months
The originality of the CTDM is the system’s operational simplicity. "The scroll type is super robust and requires almost zero maintenance but is very inefficient with regards to the hoist production cycle. When replacing a scroll option with the CTDM we expect a production increase of 10-15% depending on the current hoisting cycle. The hydraulic type is more efficient than the scroll type, but not as robust due to the complex control and sensitive associated hydraulic components. The CTDM, however, delivers the same efficiency as the hydraulic system, but it is robust and requires very little and very simple maintenance," says Koekemoer.
The CTDM technology is a simple mechanical system that comprises a gearbox assembly, and swing arms; all well-known components. The system does not require speed control as the crank motion naturally produces acceleration, constant speed and deceleration through an opening or closing cycle.
"The CTDM is significantly cheaper in total cost of ownership than the hydraulic system; the low level of complexity makes it possible for the operators to maintain the CTDM themselves without the need for specialists. Also the CTDM only uses power when actuated, this compared to a hydraulic unit which has pumps running continuously to charge accumulators and therefore generating heat," says Koekemoer. Both as a retrofit or as a new installation the CTDM can be custom-designed to accommodate the type of skip used as well as shaft specific parameters. The payback for a retrofitted CTDM can be in as little as six months.
Benefits of the Crank Type Dump Mechanism
- Can be used for all commodities in all production shafts; either on top of a retrofitted traditional scroll discharge system or instead of a hydraulic or pneumatic discharge system
- Low capital investment
- Increasing ore hoisting capacity of the scroll system by 10-15% - which makes it optimal for mines that have to go deeper, thereby prolonging the hoist cycle time, while maintaining output
- Significantly lower maintenance cost compared with a hydraulic based alternative
Watch the Crank Type Dump Mechanism in animation
Francois Koekemoer, Mechanical Design Engineer of mine shaft systems, FLSmidth: Francois.Koekemoer@FLSmidth.com
The race is on to discover a more economically viable means of extracting gold from refractory low-grade ores. FLSmidth's Rapid Oxidative Leach (ROL) process could unlock significant value in the gold space
Gold deposits are becoming increasingly complex to treat and grades continue to deteriorate in known reserves. Today, approximately 15-20 per cent of the world’s current gold production involves refractory ores that must be pre-treated prior to downstream recovery by cyanidation.
Ores are refractory for many reasons but commonly because gold occurs as tiny inclusions or submicroscopic gold within a sulphide mineral matrix. This mineral matrix must be physically and chemically altered to liberate the gold for subsequent leaching.
Mike Woloschuk, FLSmidth’s global Industry Director for gold says there are many undeveloped gold deposits where the resource head grade is simply too low to be economically viable using current refractory processing technologies.
"The industry needs a step change in technology that will significantly reduce processing cost, thereby lowering cut off grades for refractory resources. We believe ROL for gold has this potential."
Breaking new ground
FLSmidth is pioneering a mechano-chemical pre-treatment process known as the Rapid Oxidative Leach (ROL) for refractory gold ores. Sally Rocks, senior R&D chemist believes her team has made an extraordinary breakthrough which will have a profound effect on the industry.
"We have discovered an economically viable method to process low-grade stockpiles and low-grade refractory gold deposits," she states.
"Initially, we are targeting refractory gold-bearing iron sulphides where the gold is locked inside the sulphide mineral matrix and cannot be recovered without pre-treatment."
Unlike other refractory processing techniques that require ultrafine grinding or high temperatures and pressures, the FLSmidth ROL gold process uses the application of mechanical energy coupled with oxidation under atmospheric conditions.
The process relies on Stirred Media Reactors (SMRt) to accelerate the oxidation of sulfide minerals. "Other technologies have relied on ultrafine grinding to increase the surface area of the particles. While ultrafine grinding is sometimes effective, it also requires a lot of energy and thus incurs a very high cost. We have successfully engineered a new low-energy process without having to ultrafine grind," she continues.
In the ROL process, the abrasion of the particle surfaces which occurs when the SMRt is activated is balanced to match the leach rate of the particles. Sally Rocks explains: "Judicious use of mechanical energy allows us to accomplish chemical reaction rates that are otherwise impossible without the use of high temperatures or pressures. The end result is a process that uses simple equipment and low-cost operating conditions for refractory gold pre-treatment."
She points out that the ROL process is still under development but initial batch studies have shown very positive results. FLSmidth is now working with several gold customers, to develop the process on a more significant scale.
Limitations of current technology
At present, the main refractory gold processing methods include ultrafine grinding, pressure oxidation (POX), roasting, or bioleaching.
Pressure oxidation, roasting and bioleaching have been successful in oxidizing refractory sulphide minerals to expose gold in solid solution that cannot be recovered by ultra-fine grinding alone.
However, POX and roasting have high capital intensity due to the extreme operating temperatures and pressures, exotic materials of construction and the ancillary equipment required to provide reagents and environmental controls.
Bioleaching operates at low slurry density and has comparatively longer residence time, often several days, which inflates the size of the leaching circuit. Bio-oxidation is also very sensitive to cyanide and thiocyanate as they are toxic to bacteria, so it is necessary to keep the pretreatment and cyanidation systems separate.
Pressure oxidation and roasting have high processing costs. Although processing costs can vary widely depending on power and reagent consumptions associated with sulphide oxidation, recent industry information indicates POX ranges between $50-65 per ton and roasting about $25-35 per ton. Mike Woloschuk states that processing costs are typically the highest component of plant operating costs for refractory deposits. This means that at a gold price at $1250/oz gold, these current methods need 0.6-1.6 g/t Au just to cover processing costs. Many miners are faced with the dilemma that their refractory gold deposits are either too small to justify the capital outlay for current refractory processing technologies, or too low grade to cover the operational costs, or both.
Increasing economically mineable reserves
FLSmidth is working closely together with miners to unlock value, develop more productive operations, improve energy efficiency, reduce consumables consumptions, and lower operating costs, Mike Woloschuk says. "The industry continues to focus on increasing margins through optimisation initiatives, and the ROL pre-treatment is a technology we believe has the potential to unlock significant value in the gold space. When you couple low operating cost with low capital intensity, it has significant impact on the asset Net Present Value," he explains.
"Due to the high capital intensity and high processing costs of current refractory processing methods, only assets with long mine life and high grades are achieving investment hurdles. There are a lot of undeveloped refractory gold deposits that have less than 3 g/t gold head grade, and some are coupled with small resources which translates into short mine lives. Currently those assets have little to no value as greenfield deposits and they need a step change in technology to unlock value," he concludes.
Industry data on known refractory gold deposits show that the amount of gold contained in refractory measured and indicated (M&I) resources is approximately double the contained gold in refractory gold reserves. Woloschuk says, some portion of those M&I resources did not meet cut-off grade using current processing methods. These are deposits that are sufficiently drilled and some portion of the M&I resources would convert to economically mineable reserves at a lower cut-off grade.
Large deposits are becoming increasingly scarce. Since 2012, there have been less than 10 major gold deposits discovered globally. Looking at the five years prior to 2012, the number of major discoveries were nearly four times as many. While not all of these discoveries where refractory this is an indication that there isn’t the abundance of large gold deposits left, so the industry needs to find ways to treat smaller deposits going forward.
Extending mine life
FLSmidth's ROL process is not merely applicable to new deposits. According to Woloschuk, there could be significant benefits to existing operations as well: "Many existing refractory operations have low grade stockpiles that are waiting to be processed at the end of the mine life. If you add ROL pretreatment to an existing operation, it could become viable to process low grade stockpiles earlier, rather than processing them at the end of the mine life. By reducing the cut-off grade, you can move those ounces forward to generate cash flow earlier and this will increase the asset Net Present Value."
The FLSmidth ROL technology could be a game-changer for the gold industry displacing current refractory processing methods, Woloschuk says. "When we have proven this technology successful, miners will be looking at a completely different life of mine plan; by lowering the cut-off grade, more ore will be converted into reserves, extending mine life."
Michael Woloschuk, global industry director for gold: Michael.Woloschuk@FLSmidth.com
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.
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.
Steve Ware, Director for flotation and dewatering: Steve.Ware@FLSmidth.com
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.
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.
Todd Wisdom, Director of Tailings Solutions: Todd.Wisdom@flsmidth.com
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.”
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."