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Dec 29, 2019

Can coal washing be done more sustainably?

Paul A. Gallagher
Paul A. Gallagher
Regional Product Support Manager
More than half of the 250 mining industry executives interviewed rated “license to operate” as the biggest risk to their business according to EY’s 11th annual report*. A growing middle class and rapid urbanization, especially in fast-developing countries, boost the demand for energy production and raw materials, such as coal. Let’s take a look at coal preparation and how it can be improved both environmentally and economically. 
Stack of coal.

Today, coal supplies a third of all energy used worldwide and makes up 38% of electricity generation. In addition, industries such as iron & steel, cement, fertilizers, and pulp & paper rely on coal for their processes and energy requirements. Given the position of coal in the global energy framework and the legitimate environmental concerns related to it, the production of clean coal technologies is essential to accomplish both efficient energy production and a reduced environmental footprint. This is where coal washing comes in.

What is coal washing?

Depending on its quality, coal needs to be “washed” with water and chemicals to remove sulfur and impurities before it can be burned in a power plant. Coal washing, or coal beneficiation, is widely seen as an efficient method for getting the most from run-of-mine coal. On the other hand, it is a water-intensive process: typically, washing one ton of coal consumes about 45 m3 liters of water. As environmental regulations tighten, mechanized mining increases impurities in run-of-mine coal and production rates continue to surge, there is a constant need for improving coal quality.

Less water- and energy-intensive coal production

Metso’s coal washing solution includes factory fitted and self-contained modules optimizing beneficiation capacity. In other words, this means technologies that enable maximizing the ore recovery while using less water and energy or other consumables in the process.

Let’s take dewatering, a part of the beneficiation process, as a concrete example. The Inclined Plate Settler (IPS) is typically an integral component in a coal washing plant. Metso’s IPS is a modular and compact sedimentation and dewatering system utilizing lamella clarification technology that reduces the floor area and flocculant chemicals needed. Flocculants are chemicals that are used in water treatment processes to improve the settling of small particles. The lamella technology allows utilizing less flocculants in the process, which decreases the impact on the environment.

Another key feature is water conservation. With enhanced water conservation, zero outflowing wastewater discharge and lower carbon emissions, the solution contributes to a more sustainable process.

A more sustainable process contributes to reduced operating costs

Sustainability and cost/operational efficiency can and should go hand-in-hand. The Metso coal washing solution was designed to meet our customers’ need for greater flexibility and efficiency in addition to sustainability aspects. Our philosophy is to offer to the industry a comprehensive solution from concept to equipment, operations and services throughout the plant lifecycle.

Modularity makes the solution highly expandable to individual customer requirements. Having a compact and portable solution is especially beneficial when transporting equipment to remote sites with minimal infrastructure, a reality in which an increasing number of the coal producers operate. Also, referring to the lamella technology mentioned above, using less chemicals in the process reduces operating cost.

Towards joint innovations for a more efficient tomorrow

As coal use will continue to be significant in the future, greater efforts are needed by governments and industry alike to develop more environmentally and socially sustainable and efficient technologies to ensure that coal becomes a much cleaner source of energy. Metso continues developing cutting-edge solutions to help our customers make their operations more sustainable.

We have specialists focusing especially in the beneficiation of various indispensable minerals that make our modern lifestyle possible. Working in close collaboration with colleagues and customers around the world, we aim to enable smarter and more sustainable mineral recovery. We are always open for ideas and feedback, so do not hesitate to join the discussion!

*Top 10 business risks facing mining and metals in 2019–2020 report

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