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The smallest coal in the world: Coal Mill makes unique multidust
Black coal is a traditional energy commodity, but it has recently been used less and less in the manufacturing industry due to the need for reducing emissions. But there are still some applications that require black coal, even in its special form: as coal dust. In the Czech Republic, this product is made by Coal Mill of the MTX Group. Its products are used by industries that still completely rely on coal dust. However, the company is also trying a new generation of products, which will make it less dependent on coal.
At its plant in Dětmarovice, Coal Mill manufactures products called CF1 and CF2. CF stands for carbo-fuel, which is basically nothing more than ground coal. It is ground so finely it becomes basically a liquid, which is an essential property of these products that are also sometimes called hard coal multidust. But you cannot actually see this ultra-fine dust anywhere at the Coal Mill plant – unless you come here during the regular overhaul, which takes place once every three years, during which the machines are disassembled. “The powder is very fine, but it can sand almost anything like sandpaper," says Coal Mill director Petr Labuzík. Therefore, it is necessary to disassemble everything once every three years, replace the worn parts (such the giant grinding pendulum and the grinding circle in a concrete bed), reassemble everything again and weld it carefully. The routes through which the powder travels and where it is finally stored (two silos in the area) must be sealed perfectly.
Heat, dry and grind
The carbo-fuel production process seems simple, but it is extremely important to ensure the safety of the entire process. There are literally tons of dust produced, with a grind size of 90 micrometers. The giant mill grinds 40 tons of coal per hour, and we can process up to 180,000 tons of material. One pendulum alone weighs one ton. The strict production demands relate to the fact that this is a truly “heavy” industry. Carbo-fuel products are made from hard coal, which must be dried first. “If we started grinding coal when it arrives, it would not work; we would basically end up with a sludge,” says Labuzík. The reason is simple: coal contains about 10% water. So, the first stage is drying the coal. It is heated by gas burners to slightly over 100°C, which means water evaporates from the coal. This also creates an inert atmosphere. “CO2, which is produced by burning gas, displaces oxygen; its share in the atmosphere drops to about 15%,” says Labuzík. Another thing that helps keep the oxygen levels below 8% is the water vapor emitted from the coal. “But even that would not be enough, so we add water into the process, which evaporates, and thus we obtain the oxygen content below the desired limit,” explains Labuzík. The dried coal is first ground coarsely and then finely in a giant pendulum mill. A stream of inert gas that was created in the drying process separates the fine powder from the non-ground coal. The stream then carries the grains away from the grinding site, and they are separated in a cyclone and finish up in a silo, again full of inert gas. The product is then filled into tankers – truck or train – under careful supervision. A railway is located in the area, so the delivery of raw materials and the dispatch of products to customers can be done fully by train.
Specific applications
A sizable number of our customers who buy carbo-fuel are limekilns, because they use it as a fuel source to make lime. Yes, there is a demand for alternative energy sources, but it is not easy, technologically speaking. “Lime tends to absorb all the impurities; therefore, it is used for example in desulfurization in power plants, and so it is not possible to heat it with any fuel, not even many biofuels, during its production. Among the limekilns that use fuel from Coal Mill are the Carmeuse group and Vápenka Vitošov of the CRH group. They either use gas or our ground hard coal, which has a sulfur content below 0.5%, so lime does not lose its purity and its properties,” Labuzík explains. Coal powder is also used as a necessary technological component of production elsewhere. For example, carbo-fuel is applied in metallurgy, where it is used in blast furnaces to heat raw iron during tapping (discharge from furnace), so it keeps its optimal properties. “Our ground coal has replaced reduced crudes, which used to be injected here until now, and has more emissions, especially pollutants,” says Labuzík. “Our fuels burn very easily and efficiently. They can convert over 90% of the stored energy, which means they have a smaller carbon footprint than, say, natural gas,” he adds. Steel mills across Europe use injected powder for heating and the multidust from Dětmarovice is shipped to US Steel Košice or ArcelorMittal in Poland, among other places. Applications in the automotive industry are interesting, too. Besides CF1 and CF2, Coal Mill also makes something called NAYVOC. It is a special mixture of coal, coke and anthracite dust developed in cooperation with the Swedish national institute Swerea, which is used by the Swedish car manufacturer Volvo Group (manufacturer of trucks and buses). They add NAYVOC to their foundry sands. When casting grey iron parts, NAYVOC acts as a reducing agent to capture harmful substances that are formed during this process and must not escape into the air. Ground hard coal thus contributes to more environmentally friendly production. Chemical plants and other plants are among Coal Mill’s customers.
Alternatives for the future
However, Labuzík is aware that the coal products that Coal Mill produces do not have a bright future ahead of them. The company is looking for further opportunities to apply its technology and experience in the future. “Last year, we started experimenting with grinding blast furnace slag, which in ground form is very often used in the production of concrete,” says Labuzík. “In addition, we will also try to process the bottom ash that is produced when coal is burned. We will try to grind it, and it has the potential to be used in construction,” the Coal Mill director adds. “We work with Brno University of Technology, for example, where they are researching what else can supplement or replace cement, and we are therefore looking for other alternatives to materials we could use our capacities for in the future,” concludes Labuzík.
Petr Labuzík
Photo: Barbora Mráčková
He graduated from VŠB – Technical University of Ostrava, coincidentally with the current owner of MTX Group, Petr Otava. Both finished their studies in 2000; a year later Labuzík joined METALIMEX after working in the paper industry. In fact, he has been working for MTX Group for over 20 years. He traded coal and gradually took over various responsibilities and positions. Labuzík was in charge of selling coal to foreign customers. In 2006, another former classmate who worked in the lime industry was looking for coal dust. “Back then we had coal dust as a commodity; more precisely, it was called coarse dust. I sent it to him, but I immediately learned that it wasn’t what he needed and that he needed what we produce today,” says Labuzík. “Nobody offered or knew this product here, so we decided to seize the opportunity and build Coal Mill,” he adds. The company was founded in 2007, and delivered the first ton of products to customers in 2009.
