The story behind SIX-S

Sustainability is becoming one of the key drivers of society and the mining industry has recognised its critical role in going forward. Mining companies recognise that reducing their carbon footprint and other emissions is key to obtaining and maintaining operating permits. SIX-S is committed to increasing productivity in a sustainable way.

In addition to increasing societal pressures, mining companies are also aware that the transition to clean and green energy will be mineral and metal intensive. Not only is the per capita consumption of minerals increasing, but also the number of elements extracted through mining activities are growing. This development is driven, among other things, by the mega-trends of urbanisation and increasing mechanisation. Around 1900 some 20 chemical elements (Co, Mn, Pt, W, Au, C, Ca, V, Mo, Mg, Si, Ti, Zn, Fe, Cu, Sn, Al, Cr, Pb, Ni) were extracted and processed industrially. Around the year 2000 this number has increased to about 50 (Cd, Ru, Pd, Ir, Rh, As, Os, Zr, Ta, Ce, Ca, Ge, In, Te, Ag, P, U, Co, Mn, Pt, W, Au, Ru, Bi, C, Ca, V, Mg, Mo, Si, Ti, K, Sb, Zn, Fe, Cu, Sn, Al, Cr, Pb, Ni, U, REE) [Van Schalk & Reuter, 2012].

However desirable, it is also clear that the circular economy concept has theoretical, technical and commercial limits. Even with a very ambitious and technically highly challenging recycling rate of 90%, further recyclables have to be added to the 10% loss due to increasing per capita consumption and population growth.

Another fundamental factor is climate change. This enormous challenge for present and future generations can only be met if we, as consumers, all change our behaviour and consume fewer raw materials, while our societies simultaneously need a complex supply of raw materials for the green transition to a climate-neutral energy supply. Copper is needed throughout the transition from a fossil to a sustainable energy supply, e.g. for the transmission of energy (cables) as well as for generation (generators) and drive technology (motors).

For these reasons, humanity continues to depend on the supply of mineral raw materials. As experts and part of the mining industry, SIX-S feels obliged to promote sustainable and sensible production. The means to achieve this are optimisation of existing processes as well as the use of innovative technologies to increase productivity and improve resource efficiency, while reducing waste and negative environmental impacts. In this sense, we see the use of our subject-matter experience, intelligence and strategy as an important contribution.

We consider careful planning of projects and their embedding in an overall strategy to be essential for a targeted and sustainable pathway for technical and economic development. It is irrelevant whether a small and short-term project is to be embedded in a medium-term strategy or whether it is the development of a long-term strategy. A holistic, interdisciplinary approach coordinated towards the company’s goals is what distinguishes the development of sustainably effective projects.

As individuals, entrepreneurs and engineers, we use the instrument of strategy to assess and take on risks in a targeted and conscious manner in order to achieve a potential profit and to actively manage risks.

The original meaning of the Latin “rixicare” is “to quarrel” or “to battle”. When the modern spelling of the Arabic original was first adopted into English, the word carried a positive connotation in the sense of working or making a profit. The modern meaning is defined in the Oxford English Dictionary as “the likelihood of danger, damage or other negative events that can be avoided by taking preventive actions”. The preventive intention is a mental state that represents a commitment to perform one or more actions now, and in the future.

Improvements and innovations always mean change. Changes affect technical facilities as well as organisations and operational processes. But what perhaps affects the most important changes concern the attitudes and behaviours of the agents involved (individuals, companies, organisations). Involving all stakeholders and actively shaping change is therefore an important part of a successful strategy. SIX-S wants to contribute!

One out of five classic types of unit operations in minerals processing, separation is the one that divides material streams according to its value. It is the central value generation process in the mining value chain.

The processes for mineral raw materials can be divided into five groups.

Crushing (comminution), classification (separation by size), sorting (separation by property), transport and dewatering. Crushing processes reduce the average particle size and serve to create increasedheterogeneity and to expose the valuable material parts and components. Processors call this liberation.

Classification separates the bulk material streams according to the particle size. An example of this is the commonly known sieve.

Transport connects individual process steps with each other and can be either continuous on a conveyor belt, hydraulic or pneumatic. Or it takes place discontinuously, e.g. with the help of shovels or trucks.

Dewatering processes serve to separate solid and liquid phases at the end of the aqueous treatment process. The products are dewatered before transport and the process effluent slurries, also called tailings, are dewatered before being deposited on site.

The most important method of adding value is phase separation of particles in which two or more particle streams are generated from one stream that differ in their physical or chemical properties. In this process, the particles themselves remain intact, but are directed in different transport directions by the introduction of separation forces. The optimisation of separation processes holds a large, still mostly untapped business potential. However, this disruptive revenue-generating process can only be optimised on the basis of carefully generated data based on appropriate sampling procedures and analysis and a clear geometallurgical understanding of the separation behaviour.

Sensor-based ore sorting is a disruptive technology in mining that addresses mega-trends such as the reduction of ore grades and the increasing effort to reduce the specific resource input per tonne of product produced. Sensor-based ore sorting, either for bulk materials such as in shovels, trucks or on belts, or for individual particles, is not limited to a specific mineral commodity, but depends on the heterogeneity / liberation characteristics of the ore.

Different sensors and various alternative sorting locations along the flow-sheet of the mining value chain allow a wide range of applications in all segments of mineral production for a variety of mineral commodities, such as:

• Ferrous metals
• Non-ferrous metals
• Industrial minerals
• Coal
• Diamonds

The use of sensor technology for ore sorting enables separation according to completely new criteria, and opens up new possibilities for the industry. Sensor-based sorting is a separation process that requires no process chemicals or water and offers significant energy-saving potentials when used to separate barren by-products before energy- and water-intensive treatment processes.

Low-cost sensors for Process Analytical Technology (PAT) detecting selected properties of material streams are becoming increasingly available. There also exists a range of high-cost sensor technologies. Many decisions are become increasingly ‘automated’ and accelerated as the relevant data basis is available in real time. Crucially however, such data are still subject to the requirement of representativeness with regard to the complex materials and process being monitored.

Applications of Process Analytical Technology (PAT) are possible for:

• Ore characterisation
• Production plant surveys
• Mineral processing monitoring and control
• Sorting

The natural heterogeneity of mineral commodities increases the complexity for application of modern PAT sensor technology, which requires a clear understanding of conditions and requirements from the Theory of Sampling (TOS). This forms the basis for generating information from on-line data, which in turn is essential for automated or manual decision-making. This requires calibration and validation closely related to sampling. There is a minimum of comprehensive competence needed to avoid creating worthless data that, in the worst case, can lead to wrong decisions. Instead, high-quality information is provided, which is essential for a data-based and active process controland economic success.

The Theory of Sampling (TOS) provides the science-backed basis and the tools to generate reliable information about ores, mineral processing and product streams. TOS forms the basis for information-based decisions, as well as for the professional use of sensor-based Process Analytical Technology.

Currently sampling in mineral processing leads a somewhat stepmotherly existence, although it has great economic potential. Procedures and standards are unfortunately often only a compendium description of common best practices without much of demonstrable theoretical, practical, technological or economic background.

Especially in the area of pre-concentration, e.g. in sensor-based ore sorting, adequate sampling is essential for professional risk management and project development. This is due to the high sample quantity required for particle sizes larger than ~10mm. Professional sampling practice has the potential to increase company revenue by millions if the production processes are actively adapted to the changing properties, ie. to changing heterogeneity of the materials, minerals or raw ore. Therefore on-line representative sampling is the indispensable basis for all professional analyses and activities along the full value chain from ore to aliquot to reliable decision making.