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Russian Scientists to Improve Efficiency in Producing Essential Building Materials

© AFP 2021 / Kirill KudryavtsevРабочий на строительных лесах у главного входа ВДНХ, Москва
Рабочий на строительных лесах у главного входа ВДНХ, Москва - Sputnik International, 1920, 08.12.2021
Scientists from the National University of Science and Technology "MISIS" (NUST "MISiS") - along with colleagues from Belarus - have developed a new technology for obtaining raw materials for the production of building materials.
According to researchers, environmentally friendly technology is much easier and cheaper to use than analogues, according to a study published in the Journal of Environmental Chemical Engineering.
Anhydrous calcium sulfate (anhydrite) is the essential element for producing building materials. The scientists noted that although the cost of gypsum (the base for obtaining calcium sulfate) per ton is about $20 (approximately 1500 rubles), whereas the cost of anhydrite is $300 to $400 per ton mainly because of high-temperature needed during its production.
To lower the cost and simplify the technology for producing anhydrous calcium sulfate, scientists have proposed a way to produce it in an aquatic environment in one stage of synthesis. To date, it has been produced from sulfuric acid and the carbonate component in two main stages: production of gypsum and then obtaining anhydrite from it.

The researchers proposed a method for producing anhydrite from spent sulfuric acid and lime slag. The purity level of the product obtained is not less than 99 percent.
Most of the technologies for producing anhydrite are based on high-temperature firing (between 800° and 1000° Centigrade) in rotary kilns. The technology proposed by the scientists allows for direct synthesis of anhydrite under 45° to 55°C. Furthermore, the synthetic anhydrite can be derived from industrial waste, which brings savings in resources and fuel.
The advantages of this method are threefold: simpler technology, low synthesis temperature and low synthesis pressure. The cost of the anhydrite obtained via the new method will remain at level with the raw material, gypsum.

The new technology can be applied at plants that make sulfuric acid or lime slag, or the factories producing dry building mixtures. The results of the study can be used in construction, chemical, medical and other industrial sectors.

"We researched the most pragmatic ways of synthesis. We used industrial waste as raw materials, which is almost not reusable; it can be rarely reused in simple and 'cheap' industrial processes. By inserting a bit of chemistry into the recycling process, we were able to get a quite expensive product," Valentin Romanovsky, the leading expert of the Structural ceramic nanomaterials research centre of NUST MISiS said.

Today, the team of scientists is faced with the task of activating the binding properties of the material as well as studying its main properties, since the full potential of the anhydrite has not yet been sufficiently researched.

Preliminary studies have shown that its main characteristics are not inferior to, but more often exceed the main characteristics of the anhydrite obtained with the thermal method. In the future, the researchers will develop composite materials as well as dry building mixtures based on synthetic anhydrite.
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