RHI Magnesita presents innovative spinosphere technology

ANKRAL RX combines hot strength, clinker melt resistance and flexibility in rotary kiln bricks

ANKRAL RX is the first representative of a completely new series of rotary kiln bricks, the ANKRAL X-Series. Further products are already being developed to offer tailor-made products for different customer requirements.  

First installations for testing purposes have been in operation successfully since the beginning of the year, some of them in kilns with particularly challenging operating conditions. Further installations are planned and will be set up in the near future.

(English) With the new, innovative spinosphere technology, RHI Magnesita is launching a product with unprecedented properties. After just over a year, our team in Research & Development succeeded in solving a problem that has been a hard nut to crack for the entire industry for a long time.

(English) Stefan Rathausky, Head of the Business Unit Cement/Lime


ANKRAL RX combines hot strength, clinker melt resistance and flexibility in rotary kiln brick

The first development based on the spinosphere technology is ANKRAL RX. Due to the choice of synthetic sintered magnesia as a basis, the brick exhibits very high chemical resistance to alkali salts. Thanks to the use of the new technology, the alumina content of the new brick amounts to only 4.5%. In comparison, a conventional magnesia spinel brick with comparable thermal shock resistance and flexibility would require an Al2O3 content of roughly 10-12%, which would, however, impair both its hot strength and clinker melt resistance.

Due to its low alumina content, ANKRAL RX is particularly suitable for kilns with high thermal loads and unfavorable clinker compositions involving a high risk of clinker melt infiltration, however, without compromising on flexibility. Hence, ANKRAL RX can be used to cover a wide range of application cases which may arise from the complex interaction of thermal, chemical and mechanical stresses in the rotary kiln.

(English) Our customers will benefit from the new technology because it is now possible to achieve product properties for the most highly stressed areas of the rotary kiln which were previously incompatible with existing technologies. Clinker melt resistance and flexibility are no longer a contradiction.

(English) Stefan Rathausky, Head of the Business Unit Cement/Lime


Focus previously either on flexibility or hot strength

When the development of rotary kiln bricks began, chrome ore, a naturally occurring iron chrome spinel, was used. Due to the risks for people and the environment combined with the formation of hexavalent chromium and increased requirements driven by the use of alternative fuels, chrome ore was replaced by magnesium aluminate spinel (MgO.Al2O3), which is still the standard in many products today.  

However, the use of spinels to increase thermal shock resistance (TSR) and flexibility is associated with a weakening of essential properties such as hot strength and clinker melt resistance. This is attributable to the formation of low-melting calcium aluminate phases in reaction with CaO, which is abundant in the clinker, but also to the secondary phases present in the brick.

This results in a dilemma in the development of bricks with high flexibility. An increase in the amount of spinel, in particular MA spinel, invariably leads to a reduction of hot strength and clinker melt resistance. In the past, the focus therefore had to be placed either on flexibility and TSR or on hot strength and clinker melt resistance when developing new products.



Get in touch

Heinz Telser
Vice President Sales Cement & Lime
+43 69918706362

Further Information

Press Release