Debra Switzer explains why sustainability in mining requires a holistic, customer-centric approach
In the mining industry, sustainability is a somewhat amorphous term, bandied around and celebrated but too often ill-defined. Part of the problem is that it simply means different things in different contexts. While some mines are located in arid parts of the world and suffer water shortage, others are faced with seasonal typhoons and are prone to flooding.
As an OEM, Weir Minerals, in addition to its commitments to reduce its carbon emissions, works with its customers to understand their sustainability goals and objectives and implement solutions accordingly. When it comes to tailings management, this customer-centric approach is vital because of the bespoke nature of each project. Put simply, no two tailings management solutions are the same. And the ESG challenges each operator faces vary in nature.
To cater to such a wide array of challenges, Weir Minerals has strategically expanded its equipment offering, as well as signing a number of key strategic partnerships with Andritz and Eriez, to ensure that it is better placed to meet all its customers’ needs.
With equipment and expertise that can deliver unfiltered, paste and filtered tailings solutions, as well as comprehensive effluent handling and the ability to reprocess old tailings, miners are increasingly turning to the company for help in solving their most pressing tailings challenges.
One major factor when developing tailings management solutions is the site’s location, which obviously determines the climatic and geological conditions.
For instance, South America is an earthquake prone region; therefore, dam walls need to be able to withstand significant seismic activity. In recent years, a number of catastrophic dam wall failures have had tragic consequences, devastating surrounding communities and causing untold environmental damage.
The dam walls’ geotechnical requirements have underpinned the development of the Cavex DE hydrocyclone. The solution involves utilising tailings to construct TSF dam walls, thereby turning what’s usually a waste product into a usable, valuable product.
Ensuring the structural integrity of the wall is obviously paramount, which means that the sand must have relatively free-draining characteristics – or, in other words, sand that’s 15% passing minus 200 mesh (75µm).
This requirement helps prevent liquefaction, the process by which water-saturated, unconsolidated sediments are transformed into a substance that acts like a liquid.
Typically, tailings would have to pass through several stages of hydro-cycloning to achieve this sand quality; however, with the Cavex DE hydrocyclone, it can be achieved in a single stage.
With a conventional hydrocyclone, around 35-40% of mass is usually sent to the underflow, but, with the Cavex DE hydrocyclone, it is around 45-55% – making it 10-15% more efficient than some other hydrocyclones on the market.
Weir Minerals is committed to optimising its equipment to help miners produce more with less. The Cavex DE hydrocyclone’s design epitomises this approach.
The first classification stage is performed in a cylindrical hydrocyclone and terminated in the expansion zone, which features the wash water injection and an inverted conical body. As the coarse particles travel down the hydrocyclone and migrate to the outside wall of the hydrocyclone, fine particles are trapped and move with the coarse particles into the expansion zone.
The expansion zone creates conditions for the fine particles to be dragged to the first-stage overflow by the ascendent air cone. The probability of fine particles being released from the coarse particles and reporting to the hydrocyclone overflow is further increased when water is injected into the cleansing chamber or expansion zone. The decreasing coarse material is washed, providing an adequate dilution for the classification in the second stage.
The hydrocyclone’s improved efficiency also has benefits in terms of reducing water consumption.
With the rising cost of water in many parts of the world, water efficiency is increasingly becoming a precondition of being able to operate. Although these challenges are site- and region-specific, mines in arid parts of the world – where low rainfall and high evaporation is the norm – are already experiencing acute water-related challenges.
The total water consumption will vary from site to site, but based on research carried out by Weir Minerals, the savings are significant. Compared with conventional hydrocyclones, the Cavex DE hydrocyclone can reduce water consumption by up to 70%.
This holistic approach to sustainability – in which equipment and challenges aren’t viewed in isolation and each operator’s specific requirements are addressed on their merits – is what’s needed if the mining industry is going to reduce its carbon footprint.
Debra Switzer is with Weir Minerals