Weir Minerals Cavex 500 CVX Hydrocyclones deliver engineering excellence for MAL

Established in 1995 MAL are a major European bauxite, alumina and aluminium processing company with its largest operations in Hungary.

All bauxite extracted from their mines in Hungary and Serbia is converted to alumina at the Hungarian site, with the company producing 300,000 tonnes of alumina per annum.

The existing system at MAL involved Warman 6/4 pumps transporting material directly from the mill. Whilst the pumps were performing well, Weir Mineral engineers recommended the introduction of two Cavex 500 CVX Hydrocyclones to provide greater efficiency to the system which were subsequently installed in August 2010.

The Installation
A major factor that limited the efficiency of the alumina production were the different compositions of the raw bauxite from Hungary and Serbia. The Serbian bauxite constitutes 30% of the raw material input and is substantially more abrasive than the domestic Hungarian material. This was contributing to approximately 31% of material that went through the mill process being over 90 microns and as such was unsuitable for the next stage in the alumina production process.

Improving recovery
A simple solution involved the installation of two Cavex 500 CVX Hydrocyclones which would allow for the automatic separation and retrieval of the larger solids that could then be transported back into the mill process to break them down further. This had the benefits of eliminating waste, underpinning a more efficient system and increasing the overall system recovery.

The cyclones were installed at an inclination of approximately 35° from the horizontal to coarsen the cut point and also to maintain a more stable underflow. Due to the size of the solids and the density of the liquor, the maximum underflow concentration would be ~62% by weight solids. This underflow density also determines the density of the overflow stream.

Since installation, the cyclones have continued to provide a high level of performance, achieving 1200g/l with an 80mm spigot. With a spigot lifetime of approximately 700-800 hours Weir Minerals have continued to develop a good working relationship with MAL. 

Technical Details
Cavex Hydrocyclones offer many slurry applications in the mining and mineral processing industry.

Providing closed circuit grinding classification for improved efficiency, reduced wear and higher capacity an installation would benefit from improved classification ahead of other process equipment such as flotation cells, magnetic separators, spirals, hindered settling classifiers etc.

Cavex Hydrocyclones also provide better dewatering and desliming efficiency, reducing product loss and improving product recovery.

Featuring unique laminar spiral inlet geometry designed to deliver maximum efficiency; Cavex Hydrocyclones provide maximum capacity and longer wear life than conventional involute or tangential feed hydrocyclone designs.

Not just simply a cone modification, the Cavex Hydrocyclone is designed with an entirely new feed geometry that substantially increases hydraulic capacity whilst minimising localised wear on the feed chamber and vortex finder. These design improvements result in lower operating costs and fewer hydrocyclones required for a given duty.

For grinding circuit applications, Cavex Hydrocyclones increase circuit capacity by minimising the quantity of fines bypassing to the underflow stream. These effects are achieved by maximising the air core diameter created within the rotating mass of fluid in the hydrocyclone and are proven in both laboratory testing and full scale plant operation. 

How do Cavex Hydrocyclones reduce wear and increase capacity?
The design of the Cavex Hydrocyclone laminar spiral inlet geometry provides a natural flow path into the hydrocyclone. This unique shape has no sharp edges, no square corners and allows the feed stream to blend smoothly with the rotating slurry inside the chamber.

The end result is a greatly reduced turbulence throughout the whole hydrocyclone creating more even wear, longer life and a more efficient classification. In conventional hydrocyclones slurry bursts into the cylinder with no flow control and the resulting turbulence is responsible for gouging the liner walls.

Weir Minerals - Linatex
Wilkinson House
Galway Road
Blackbushe Business Park
Yateley
Hampshire
GU46 6GE UK

T: 01252 743000
F: 01252 743030