Main navigation BUSINESS GROUP FINANCE TALENT NEWS & STORIES MEDIA EN FR MINERALS AND MORE MULLITE Extremely rare in its natural form, mullite is artificially produced for industry by melting or firing various alumino-silicates. The outstanding thermo-mechanical properties and stability of the resulting synthetic mullite make it a key component in many refractory and foundry. KEY FIGURES #1 World’s leading producer of calcined products for the refractory industry #1 Fused and sintered mullite and fused zirconia mullite solutions for foundry coatings and investment castings 1,853°C Melting point of mullite IDEAL FOR REFRACTORIES Although mullite exists as a natural mineral, occurrences in nature are extremely rare. Industry relies on synthetic mullites which are achieved by melting or ‘calcining’ various alumino-silicates such as kaolin, clays, rarely andalusite or fine silica and alumina to high temperatures. One of the best natural sources of mullite is kaolin (as kaolinic clays).. It is ideal for the production of refractories such as fired or unfired bricks, castables and plastic mixes. Sintered mullite and fused mullite is primarily used for the production of refractories and the casting of steel and titanium alloys. 1 / 1 An aerial view of Andersonville site (USA) Mullite does not exist in great quantity in a natural state. It is produced by heating of kaolin (or clays) that transform into mullite with formulation 3Al2O3∙ 2SiO2. PHYSICAL PROPERTIES Good creep resistance Low thermal expansion Low thermal conductivity Good chemical stability Excellent thermo-mechanical stability Excellent thermal shock resistance Low porosity Comparatively lightweight Oxidation resistance GLOBAL BENCHMARK Imerys calcined mullites are recognized as the global benchmark. They are produced from clays mined from the South Georgia kaolin belt in the US, and blended to obtain chemistries between 45% and 70% alumina. Our Technology Center in Lyon (France) and our Tianjin laboratory (China) feature an extensive range of minerals processing, testing and analysis tools focused on high resistance materials. A TOUGH SOLUTION FOR REFRACTORIES For refractory applications, Imerys high-duty, high-alumina mullites make excellent refractory product for bricks and castable due to high refractoriness, strong stability and high temperature behaviour. In this application, Mullite is well known under the brand Mulcoa. In investment casting foundry, Imerys mullite is used under Mulgrain name. Mulgrain is used in Shell used to receive the metal. Mulgrain is ideal for preventing metal-mold reaction as well as thermal shock and cracking in finished foundry parts due to their excellent refractoriness and low thermal expansion. Mullite is an excellent aggregate for refractory bricks. Imerys offers an extensive portfolio of high-quality calcined minerals with different functional properties, making it a privileged partner for the refractories and ceramics industry. REFRACTORIES CONTACT GROUP FINANCE TALENT MEDIA Follow us © Imerys 2021 Cookies Policy Personal Data Legal Terms WE USE COOKIES Our website uses cookies to allow for a personalized experience on our website and improve your user experience. For more information about our cookies please read our Cookie preferences. Mandatory Cookies These cookies are essential to enable you to navigate our website and use its features. These cookies are session-specific and expire after your visit to the website. Performance Cookies These cookies allow us to improve the user experience & performance of our site for our visitors, by measuring website usage statistics such as visits, top pages, and traffic. All information these cookies collect is aggregated and therefore anonymous. Accept all Save my preferences