Wednesday 8th Jul, 2020

Copper concentrate bulk bagger fuels throughput

By implementing an automated bulk bagging and palletising system, Vale has improved its capacity, flexibility and safety at one of the largest copper mining facilities in the world.

By implementing an automated bulk bagging and palletising system, Vale has improved its capacity, flexibility and safety at one of the largest copper mining facilities in the world.

Vale Canada Limited operates one of the largest integrated mining facilities in the world in Sudbury, Ontario. The complex has been in operation for more than 100 years, mining and processing ores containing nickel, copper and other metals.

In 2012, the Sudbury plant began a billion-dollar Clean Atmospheric Emissions Reduction (AER) project to reduce sulphur dioxide stack emissions by 85 per cent.

Previously, Vale refined nickel and copper in Sudbury but after analysing the total life of the mines and the long-term projections of mine capacity in the region, the company decided to focus on nickel production and sell copper concentrate to other companies instead of refining it in-house.

The ore mined on site is first ground into a flour-like powder, says Tom Zanetti, Senior Project Manager on the Clean AER Project. A flotation process removes waste rock and the resulting bulk concentrate is sent to a smelter, which produces a high-grade material containing both nickel and copper. Another flotation process separates the nickel and copper concentrates before Vale refines the nickel concentrate into metal on site.

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The copper concentrate, after de-watering and drying, has a texture similar to that of sand and contains 60 to 70 per cent copper. It is conveyed to two large feed hoppers positioned above the dual bulk bag filling stations, each hopper holding 10 tonnes, enough to fill five bulk bags.

Vale worked with Canadian company Ionic Engineering to design a material handling system capable of packaging the concentrate into bulk bags at a rate of 24 to 32 tonnes per hour by integrating a Flexicon automated bulk bag filling system.

To handle the volume, Francois Nzotungwanimana, Operations Manager at Ionic Engineering and Project Engineer on the bulk bagging project, specified the dual bulk bag fillers, roller conveyors and a central pallet dispenser comprising the Flexicon system. 

In addition, Ionic designed the electrical and control systems, sourced labelling machines and other equipment, designed safety systems and performed the systems integration including programming, electrical and safety. The Ionic Engineering team also performed additional mechanical design and safety engineering.

Pallets automatically dispensed to bulk bag fillers

Flexicon’s Project Engineering Division integrated a pallet dispenser, pallet turntables, two 7.5-metre-long roller conveyors, and two swing-down bulk bag fillers into the process. The pallet dispenser is positioned between – and at a right angle to – the mirror-image bag filling lines.

A forklift loads 10 to 14 pallets at a time onto the pallet dispenser. When one of the bulk bag fillers calls for a pallet, the dispenser lifts all except the bottom pallet, which is sent to the left or right filler by the powered roller conveyor. A turntable then rotates the pallet 90 degrees to align it with the filler.

Automating bulk bag filling operations

Once a pallet is in place, the filler’s swing-down fill head lowers and pivots from horizontal orientation to vertical, positioning the discharge chute and bag strap hooks within reach of an operator standing on the plant floor. This eliminates the need to step on roller conveyors or strain to reach overhead connection points, improving the site’s safety processes.

After the operator has placed the bulk bag loops over automated latches and fits the bag spout over an inflatable spout seal, the rest of the filling cycle can be completed automatically with the push of a button.

The fill head pivots back to horizontal, raises to filling height and inflates the bag to remove creases. After several safety conditions are met, a knife gate valve opens, allowing the respective overhead feed hopper to gravity-discharge into the bulk bag at maximum feed rate. This occurs as displaced air from the bag is vented through a filter sock to contain airborne dust.

At timed intervals, a densification deck below the pallet vibrates to stabilise the bag while load cells continually monitor the weight of the copper concentrate as the bag is filled up to two tonnes.

The controller closes the knife gate valve, releases the bag loops and deflates/disconnects the spout. A powered roller conveyor then moves the palletised bag out of the filler and onto several accumulating powered roller conveyors.

The filled bag stops at the last accumulating conveyor where an automated labeller applies an identification label, before being rolled onto a gravity-feed roller conveyor toward a ramp that stops it in position for unloading. A forklift can then transfer the bags to a storage area, ready for shipment to customers.

By using the dual bulk bag filler configuration, Vale was able to benefit from improved capacity, flexibility, and redundancy for its bag filling process in the limited space available. Automatic pallet dispensing also reduces the wait time and the likelihood of worker injury.