Tag Archives: paste

Outotec to deliver ‘unique’ paste backfill plant to OZ Minerals’ Prominent Hill mine

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Outotec says it has been awarded a contract to design and deliver a mine paste backfill system to OZ Minerals’ Prominent Hill copper-gold mine, in South Australia.

The contract price is €15 million ($16.5 million) and it has been booked into Outotec’s 2019 June quarter order intake, the mineral processing company said.

Outotec’s supply includes the design and delivery of a complete paste backfill system, as well as detailed design of the underground distribution network and fill management systems, it said.

The new paste backfill plant will be based on a unique process design, which allows flexibility to use continuously produced fresh tailings or store filter cake to meet the future backfill needs of the underground mining operation, Outotec said. The new facility is expected to have a capacity of 215 m³/h.

“A reliable paste backfill system is critical to the whole mine and its operations. We are pleased to support our customer to improve their tailings management in a sustainable way,” Kimmo Kontola, Head of Outotec Minerals Processing Business, said.

Prominent Hill is a copper-gold mining operation made up of the Malu open-pit mine – which concluded operations last year – the Ankata and Malu underground deposits and a conventional crushing, grinding and flotation processing plant.

Outotec has previously delivered an EPC backfill system, plus build own operate backfill plant for ongoing operation at Prominent Hill.

 

Outotec looks for consistent and efficient dewatering with new paste thickener

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Outotec has introduced the 2nd Generation Paste Thickener to, it says, maximise underflow density regardless of challenging mineralogy and tailings feed-rate variation.

The thickener enables consistent and efficient dewatering performance – even with changing process conditions, according to the company.

“Through consistent performance and high underflow density, the 2nd Generation Outotec Paste Thickener maximises beaching angle in the tailings storage facility to provide safer operations and maximised lifespan,” Outotec said.

The new paste thickener provides ease of operation and reliability for applications requiring a high degree of dewatering, such as minerals tailings, mine backfill, and pre-leach and counter current decantation circuits, according to the company. “The technology is customised to address each operation’s unique drivers, which can include environmental concerns, water recovery, regulatory requirements, tailings management, or limitations on available land space,” the company said.

Outotec has a history of developing paste thickeners, as well as the design and delivery of large-scale paste thickening projects. “This has given us a deep understanding of the key aspects of high-density thickeners, including effective flocculation, dewatering, raking, prevention of rotating mud beds, process control, and the discharge of thickened solids,” it said.

“One such case was the deployment of Outotec paste thickener technology – including a full-scale paste tailings plant and Outotec ACT Thickener Optimizer system – at Yara’s Siilinjärvi apatite mine in Finland (pictured),” Simon Courtenay, Product Manager for the Outotec 2nd Generation Paste Thickener, said. “The plant generates around 10 Mt of tailings a year and, thanks to the Outotec ACT Thickener Optimizer, the paste thickeners can consistently run with a high and stable underflow solids content of 66-68%, regardless of challenging mineralogy and tailings feed-rate variation. This results in average beach slope angles of 3.5° (6.1%) in the tailings disposal area, helping to extend its lifespan. The system has also enabled a 10-20% reduction in flocculant costs.”

The new 2nd Generation Paste Thickener builds on this proven performance with a range of innovative new features, according to the company. For example, vertical load monitoring with the Smart Rake Lift system means the Outotec Paste Thickener is one of the only systems in the world that can detect early formation of rotating beds, enabling counteractions to be taken early, Outotec said.

The system also monitors and actively adjusts the individual hydraulic cylinders to maintain alignment of the rake mechanism. Incorporating vertical load sensing with plant process data in the Outotec ACT Thickener Optimizer control system means the solids inventory within the tank can be maintained to ensure a consistent underflow density, stable process, and improved overall thickener performance, according to the company.

In addition to mechanical improvements, process control has been further developed to stabilise and optimise the performance of the paste thickener, Outotec said.

The company said: “Outotec’s ACT Thickener Optimizer utilises a multivariable controller to manage process changes and the associated delays in the response time of the thickener that can be challenging for traditional control systems. It can also be configured to manage the effects of variable feed types to ensure optimum performance despite changing inputs to the process. Short installation and configuration time of the system is coupled with on-going services to ensure a practical yet flexible long term control solution.

“Our application-specific design of the thickener begins with the use of methods such as discrete element modelling to understand solid particle movement within the thickener, computational fluid dynamics for feed system design and finite element analysis for structural steel design. Our paste thickening solutions are also designed with ease of maintenance in mind, with a skid-mounted hydraulic power unit for centralised connection of hydraulic hosing from the rake lift cylinders and drive unit.”

Other key design features include:

  • Low profile rakes with tie-cable load sharing that minimise rake drive torque requirements;
  • Rake blades supported by thixoposts to move the rake arm away from the highest density thickened solids;
  • High sidewall and steep tank floor slope for more efficient dewatering of flocculated solids and compaction of the bed, as well as better transport of the solids inward toward the tank discharge point;
  • High installed drive torque to move the rake blades through beds of thickened solids with high yield stress and viscosity, and;
  • Feed systems with break tanks when required for different thickener feed situations, including our patented Vane Feedwell, and break tanks inside the thickener perimeter to save on site layout space.

“Beyond technology and equipment, Outotec provides complete solutions for thickening needs,” the company said. “Proven design features and process guarantees, combined with lifecycle service support, help ensure operational reliability. We can also support customers with ongoing operation and maintenance services after plant commissioning.”

The fine print in FLSmidth’s REFLUX Classifier technology

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FLSmidth has looked to spell out to the mining industry the benefits of its REFLUX™ Classifier (RC™) technology.

The RC is a slurry-based gravity separator designed specifically to upgrade fine minerals generally finer than 2 mm, the company says.

“The key design element is a system of lamella plates or inclined channels and the internal overflow launders. These are contained within the Lamella Settler – the top portion of the RC. The other two main components are an Autogenous Dense Medium Separator underneath the lamella chamber, and a Fluidised Bed Separator beneath that.”

Material from the process plant enters through the slurry inlet and passes over an internal over-size protection screen, removing any tramp or debris that may cause damage to the ceramic underflow valve.

Large, high-density solids quickly sink and settle in the mixing chamber in the middle section of the classifier, forming a fluidised bed of dense material. This bed is created by a series of water jets at the base of the mixing chamber and rejects any trapped lighter particles.

“Lighter and finer particles rise in the RC, through the autogenous zone to the lamella section,” FLSmidth says. “The autogenous section is created by fine suspended solids, and this zone helps convey lighter particles to the lamella section.”

This upper section contains the crucial sloping lamella channels, typically placed 6mm apart – although this distance can be reduced for finer materials. Low density particles rise up through these channels, driven by the upward water flow from the feed. The narrow sloping channels cause a parabolic flow pattern where the flow is fastest midway between the channel walls, the company says.

“The lightest particles are carried by the faster flow before they can settle and they overflow at the top of the channel. They fall into internal launders and are discharged from the RC. The higher density particles tend to slide back along the topside of the lamella channel, where the flow is slower. These particles slide down the slope, back to form the autogenous dense media zone,” FLSmidth says.

Pressure probes monitor the bed density and automatically control the underflow valve to optimise the bed level and density. The fluidised bed keeps particles in suspension and rejects the lighter material up out of the bed, while the denser particles sink and flow out through the underflow valve.

“The valve’s four-link system moves the plug vertically, which reduces wear and provides protection against splashing,” the company says.

In a recent innovation, a modular RC plant, FLSmidth selected the associated equipment – like pumps, screens, dewatering equipment and conveyors – for optimal performance. These modular plants are also automated, using advanced instrumentation and control equipment to keep operations consistent and recoveries high.

Kirkland Lake Gold signs up GR Engineering for Fosterville paste backfill plant

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GR Engineering has won a contract to build a paste backfill plant for Kirkland Lake Gold’s Fosterville mine in Victoria, Australia.

The EPC contract will see the company carry out all process engineering design, supply, construction and commissioning of a plant capable of producing 65 m³/h of paste to fill the stopes in the gold mine. The scope of the work also includes the design of the underground reticulation piping.

GR Engineering is booking A$23.9 million ($17.3 million) for the work, which will start immediately. Completion of the facility is expected in 2019.

This is the second EPC paste backfill contract the ASX-listed company has won in the past few weeks. Earlier this month, Saracen Gold Mines awarded GR Engineering a contract to build and commission a plant able to produce 110-120 m³/h of paste to fill stopes at its Karari underground mine, part of its Carosue Dam operations, in Western Australia.

Kirkland Lake’s Fosterville operation is a high-grade underground mine expected to produce 275,000-300,000 oz of gold this year. It extracts gold via open stoping with cemented rockfill used where applicable and practical.