Tag Archives: cyclones

Multotec looks for increased resistance, longer wear life from new ceramic-based solution

A new ceramic-based solution from Multotec has opened the door for a range of componentry to be shaped using pressed alumina ceramics for high wear resistance and longer wear life, the South Africa based company reports.

According to Boyd Butterworth, Sales Engineer at Multotec Wear Linings, the opportunity arose when a chrome smelter in the Steelpoort area of South Africa’s Limpopo province was searching for a more cost-effective solution for certain wear parts in their rotary dryer multi-cyclone arrangement.

“The customer initially required the fabrication and ceramic lining of steel components in the multi-dryer cyclones,” Butterworth says. “The units are employed in the process of drying chromite ore particles and other feed material on its way to the pelletising section of the plant.”

The units are essentially dust cyclones – rather than the process or separation cyclones Multotec supplies – and are subject to aggressive wear. The feed to these multi-dryer cyclones typically consists of chromite ore, reductants such as anthracite, char, coke and coal, and fluxes like quartzite, dolomite and lime.

“The multi-dryer cyclone has four main components, made initially of steel and later lined with ceramics in response to the rapid replacement rate,” Butterworth says. “The wear rate is exacerbated by the high velocity of the material, which is required in order for it to remain in suspension while passing through the system.”

The customer’s eagerness to find a more effective solution allowed Multotec to present an unusual – perhaps unique – concept: solid ceramic components custom-shaped for this specific purpose, the company said.

Butterworth noted that the previous installation of standard ceramic tiles by a competitor did not adequately protect the components from the highly abrasive material which, moving at about 18 m/s, was still leading to frequent component replacements.

“Our proposal was to produce a solid ceramic blade and dome arrangement, as well as to provide the rest of the tube and inlet sections with engineered ceramics, installed at a very high standard,” he says.

Paving the way for this solution was a highly specialised and innovative new fabrication technique that saw the ceramics shaped into various complex and intricate designs while they are in the ‘green phase’ of production, using state-of-the art CNC technology.

“Thanks to this technique, we can produce solid alumina ceramic machine components,” Butterworth says.

The company’s research to date suggests that this might be the first time components like these have been produced from pressed alumina ceramics – making them a pioneering achievement.

Newcrest leverages Eriez HydroFloat tech to help boost Cadia output

Having installed the first full-scale HydroFloat™ cells for the recovery of coarse composited copper and gold at Newcrest’s Cadia Valley operation in New South Wales, Australia, in 2018, Eriez is about to help the miner boost output at the operation.

Today, the Newcrest Board approved two projects moving to the execution phase, being Stage 2 of the Cadia Expansion project and the Lihir Front End Recovery project, in PNG.

The Stage 2 Cadia Expansion project primarily comprises the addition of a second coarse ore flotation circuit in Concentrator 1 (graphic above), using Eriez’s HydroFloat technology, and equipment upgrades in Concentrator 2.

These changes are expected to see plant capacity go from 33 Mt/y to 35 Mt/y, while life of mine gold and copper recoveries could increase by 3.5% and 2.7%, respectively. Alongside this, the company was expecting a A$22/oz ($16/oz) drop in its all-in sustaining costs.

An increase in throughput capacity in Concentrator 2 from 7 Mt/y to 9 Mt/y will be achieved through crushing, grinding, cyclone, pumps and flotation upgrades; while the installation of the second Coarse Ore Flotation circuit on Concentrator 1 and additional upgrades to Concentrator 1 will facilitate an increase in throughput capacity to up to 26 Mt/y, the company said.

“Stage 1, which is already in execution, was designed to maintain production continuity at Cadia through the development of PC2-3 (the next cave development) and increase the processing capacity to 33 Mt/y,” Newcrest said. “Stage 1 comprises an upgrade to the materials handling system and debottlenecking of the Concentrator 1 comminution circuit.”

The rate of ore mined from Cadia is expected to vary over time according to draw rates, cave maturity and cave interaction as further caves are developed, according to Newcrest. From the 2027 financial year onwards, life of mine Cadia mining rates are generally expected to be in the range of 33-35 Mt/y, with an average of 34 Mt/y used for financial evaluation purposes, the company said. Higher mine production rates may be possible, subject to further studies.

At throughput rates of 34 Mt/y, gold recovery improvements from Stages 1 and 2 are expected to achieve LOM gold recoveries of 80.3% and LOM copper recoveries of 85.2% compared to Stage 1 baselines of 76.8% for gold and 82.5% for copper.

The estimated capital cost for Stage 2 is A$175 million, A$5 million lower than the October 2019 estimate, according to Newcrest, which added that timing for delivery remains on schedule, with completion expected late in its 2022 financial year.

The Lihir Front End Recovery project, meanwhile, primarily comprises the installation of flash flotation and additional cyclone capacity, as well as cyclone efficiency upgrades, to improve grinding classification and reduce gold losses through the flotation circuits, Newcrest said.

The flash flotation and cyclone upgrades target the following process improvements:

  • Implement flash flotation to reduce mineral fines generated from overgrinding and send the higher-grade concentrate stream to the autoclaves; and
  • Improve cyclone efficiency to achieve a reduction in unliberated coarse mineral particles entering the cyclone overflow, which are not recovered in conventional flotation.

This is projected to result in LOM gold recoveries increasing by 1.2% and incremental LOM gold production increasing by 244,000 oz. It came with an estimated capital cost of A$61 million.

Multotec builds integrity with hydrocyclone solution at Zambia tailings facility

An innovative hydrocyclone solution from Multotec is allowing a large Zambian copper mine to develop a safe and cost effective tailings storage facility (TSF), the South Africa based company says.

The TSF faced a number of specific challenges, according to Frikkie Enslin, Senior Applications Engineer responsible for cyclones at Multotec, including its extensive planned capacity and the area’s flat topography. The mine’s process plant pumps some 10,000 m³/h of tailings to the TSF, requiring its final circumference to reach about 19 km.

“The flat area around the mine meant there was no suitable topography to provide a natural dam,” Enslin says. “It was therefore vital to create strong walls to retain the slurry from the plant, so that the integrity of the TSF could be assured.”

Simple gravity separation and sun-drying had proved unable to create material firm enough to constitute walls, according to Multotec. In the early days of the plant’s operation, it was shown material being deposited by means of plain spigoting could still not be walked on even after a month of drying in the sun. By contrast, Multotec’s 250 mm GV hydrocyclones were able to deliver an underflow discharge that could be walked on in just two days, the company said. After a week, the material could withstand the weight of an excavator.

The sheer volume of slurry being pumped into the TSF, however, created its own challenge. The hydrocyclones had initially been mounted on metal cradles, which were inundated within a couple of hours. Extracting the cyclone and cradle from the mud for the next placement was difficult and very time consuming.

“The customer needed a solution that would keep the cyclone above the slurry level for longer, and would be easier to move,” he says. “To do this, we designed a cyclone cradle that could be attached to a long wooden pole, giving much greater height, allowing the customer to leave the cyclones in the same position for a much longer time.”

With Multotec’s experience and facilities for custom design and manufacture, the hydrocyclones were then modified to be lighter. This made them easier to handle and manoeuvre, it said.

“Constructed with a lighter metal, these tailor-made units are industry leaders in terms of being lightweight and are rubber-lined to ensure long wear life,” he said. “We also made some innovative improvements to the vortex finders and the cone sections, which are now metal spun.”

Other changes were made to speed up the changing of a spigot, and the moving of the hydrocyclones from one point on the TSF wall to the next. The design now includes a threaded spigot coupling and quick-release connections on the cyclone.

The solution has been so successful to date that over 250 of Multotec’s modified GV hydrocyclones have been installed.

“Just as we collaborated closely with the customer in developing this solution, so we continue our partnership in monitoring the performance of our hydrocyclones as the project goes on,” Enslin says. “An expert applications engineer from our Johannesburg head office visits the site regularly, while our Zambia office in Chingola offers solid technical and field service support. We don’t just sell process equipment, but rather process solutions.”

FLSmidth to boost plant efficiency with SmartCyclone system

With process plant optimisation techniques becoming a necessity for mines looking to maximise their operating performance by keeping costs low, throughput high and downtime to a minimum, FLSmidth has devised an automated monitoring and control solution for reducing cyclone-related process deviations.

The SmartCyclone™ system delivers in all three areas for cyclone circuits, according to the company, improving cyclone overflow particle size distribution, predicting and controling cyclone maintenance schedules, and optimising closed-circuit grinding processes.

FLSmidth said: “This equates to monitoring the performance of individual cyclones within a circuit in real time, preventing unplanned breakdowns from occurring and monitoring wear rates while ensuring the cyclones are operating optimally at all times. This translates into higher efficiencies in the plant and ultimately, higher profitability.”

The SmartCyclone closed circuit grinding optimisation system combines a variety of FLSmidth patented technologies, including the FLSmidth Krebs SmartCyclone wear detection sensor technology and the Krebs’ patented roping sensor technology (with patent-pending wireless controller system). This technology immediately identifies if a cyclone is malfunctioning, the company said.

The closed circuit grinding optimisation system also incorporates FLSmidth’s ECS/ProcessExpert® process control software with a new patent-pending SmartWear™ cyclone maintenance algorithm.

One of the largest benefits associated with this software is the ability to develop a uniform operation strategy that outlines the best way to run the plant, according to FLSmidth. “Once this strategy has been established, the necessity to train new operators is reduced.”

Reducing or eliminating manual operation, which decreases the potential for human error, is also one of the overarching benefits of SmartCyclone, the company says.

FLSmidth has more recently enhanced its Krebs SmartCyclone system with wireless technology that
enhances installation by eliminating the need for individual nodes and the interconnecting cables between the sensors and nodes and associated controllers.

It uses a central wireless controller that can handle up to 16 sensors per unit; providing real-time wireless detection and communication of roping and/or wear data. The new wireless controller unit is a handheld device that can be removed from its docking/charging station to sync the individual sensors. Once removed, it goes into battery-power mode and the user can walk to a desired sensor, activate it with a magnet, trigger and set the necessary operating parameters.

Multotec ready for the mineral processing test

Mineral processing specialist, Multotec used a recent media visit to talk up the testing facilities at the heart of its Technology Division.

The South Africa-based company can carry out a range of testwork with its specialised equipment in Spartan, Gauteng, according to Multotec Technology Manager, Faan Bornman.

“Much of our testwork comes from customers who are in the early stages of project development,” Bornman says.

“They need to understand more about how their minerals or material will separate under given conditions. Often there is not a mathematical model that can predict accurately what they can expect.”

Testwork can reduce project risk significantly, providing a solid foundation for the subsequent design and optimisation of process facilities, Multotec says, with Bornman noting that physical testwork is usually the best way of finding out how particles will behave in a process plant.

The equipment available to Multotec customers includes laboratory-scale wet high-intensity magnetic separators, cyclone rigs, filtration equipment, centrifuges, spiral rigs and a screening research rig. There is even capacity to test water purification methods on mine effluent.

“Extensive test work is especially relevant when a customer is wanting to mine and treat less traditional minerals like lithium or graphite,” Bornman says. “As demand grows for commodities like these, we have had customers bring samples to test how our equipment would perform. In these tests, we trial various methodologies and scientifically record and compare the results.”

The R&D laboratory prepares samples and conducts particle size analysis using equipment such as pressure filters, drying ovens, sieves, shakers, sizers and separating funnels. When chemical analysis is required, samples are sent to outside laboratories.

Bornman said his division also receives enquiries from existing customers when they face challenges: “We research the application of different methodologies to customer material, often leading to the development of a new product or improvements to our existing products,” he said.

“In addition to providing a solution for the customer, we are also able to contribute to the efficiency of the industry as a whole, with an updated and commercialised product.”

Screening

When it comes to tests on mineral screening, a test rig – located at Multotec’s Spartan headquarters – delivers two primary benefits, according to Chris Oldewage, Technology Manager at Multotec Manufacturing. First, it facilitates the in-house development process of screening media products. Second, it allows screening media to be tested against customer requirements to ensure the right solution is delivered.

“The ongoing research and development behind our screening media products give the industry opportunities to optimise efficiencies and recoveries,” Oldewage says. “However, changing anything on a plant brings risk of unexpected downtime. Our screening test rig can considerably reduce operational risks by proving any changes before they are implemented on site.”

In the controlled environment provided by the screening test rig, customers can view the actual performance of screening media products with material from their mining operations, Multotec says, with the company’s testing protocols generating the data necessary for detailed process analysis. This facilitates well-informed subsequent decisions, the company said.

The screening rig is made up of three test platforms: a vibrating screen, a sieve bend and a static drain screen platform. The vibrating screen can conduct classification tests, wet and dry dewatering tests, product development tests and plant screen simulations. The static drain screen and sieve bend screening test platforms are wet classification, drainage and dewatering tests.

Multotec Process Engineer, PJ Pieters, said accurate scaling of a customer’s on-mine process is vital for achieving representative and relevant test results.

“We gather a range of key data from customers on our test work questionnaire,” Pieters said. “This includes their material tonnages, volumes of water, screen sizes in operation and aperture sizes on panels among other information.”

This ensures sample sizes are representative and the tests accurately reflect what is taking place in the mine’s processes. Tests, meanwhile, are conducted in triplicate runs to ensure a sound scientific basis for the findings.

Oldewage said: “By removing the risk that mines face in trying new solutions, our testing capability smooths the way for valuable innovation to improve screening performance.”

The screening test facility at Multotec also includes a small Lucotec screen and a small wedgewire trommel screen, both for small-scale verification test work.

Cyclones

Multotec’s large scale cyclone rig, meanwhile, can test the performance of a range of cyclone sizes, up to 450 mm diameter. Tests related to classification, desliming and dewatering, as well as dense medium separation using density tracers, can be conducted.

Among the benefits to customers is the ability to test large volumes of samples, as the rig includes a 1,750 litre sump and a 6/4 pump, Multotec said. Flexibility is provided by a variable speed drive connected to the pump, to vary the flow rates as required by the cyclone size.

Dry samples usually need to be blended before testing, and wet samples may need to be dried before blending. The resulting samples from the test must also be scientifically prepared for particle size and chemical analysis. The precision at each stage is vital, as bulk samples as large as 200 kg may need to be reduced to as little as 100 g.

The rig’s infrastructure also includes two Multotec vezin samplers, which are compliant with the highest design standards to provide reliable samples, according to Multotec. “These help to minimise the common errors of manual sampling and ensure that the integrity of the sample is retained,” the company says.

In addition to using the test rig to analyses the customer’s process flowsheet – with Multotec engineers identifying where its range of classification and other products can add value – the company also uses the cyclone test rig for its own product development.

“This on-going process has resulted in a range of cyclones that are lighter, more cost effective, environmentally-friendly and energy efficient,” the company said. “They all contribute to helping customers lower their cost per tonne in a low footprint, sustainable plant operation.”

Spirals

Multotec says its spiral test rig has been adapted in response to the industry’s need to re-treat chrome dumps and upgrade ultra-fine chrome.

Again, located at the company’s headquarters in Spartan, the rig allows eight to 10 different spirals to be erected at a time.

Jeantelle Rust, R&D Engineer at Multotec Process Equipment, said: “With the drive to process tailings in the chrome sector, we have been running tests on a more compressed spiral with a reduced pitch. This reduces the velocity of the very fine particles.”

This configuration works particularly well when dealing with fine material, hence its application in tailings, Rust said. The spiral could offer a cost-efficient way of separating ultra-fine chrome material and recovering valuable product, according to the company.

Rust said: “Such a solution presents an attractive commercial proposition to industry and will also address environmental concerns presented by tailings dumps.”

Using a “mouth-organ product box”, the material being tested on the spiral rig is split into eight product fractions, not just the usual three for product, middlings and tailings. This helps optimise the mass balance for reporting purposes, according to the company.

The spiral test rig has also been used to evolve designs that deal with coarser material, Multotec said. “Customers were looking for a solution to the ‘beaching’ of coarse coal product on the spiral’s surface, for instance,” it explained.

Rust said: “We were able to modify the angles and diameter of the trough to address this challenge. Our ability to make small adjustments to the equipment, and to test material repeatedly at full scale, is the key to finding practical solutions.”

Multotec has also conducted research for producers of mineral sands where head grades were steadily dropping. This necessitated the treatment of larger tonnages, requiring higher capacity spirals.

“Space constraints on the customer’s site meant that adding spirals to their process was not an option,” Rust said.

“Wider spirals were thus tested for higher throughput, with different angles to minimise losses.”