Preliminary exploration of andalusite in the east of Fariman: mineralogy, geochemistry, and mineral processing for production of acidic refractory minerals
Andalusite, silimanite and kyanite are aluminosilicate polymorphs that are formed due to metamorphism of argillic rocks. Silicon and aluminum oxides are the main forming agents of these minerals that have high melting point and can be used as acidic refractory materials. Refractory materials are those that have mechanical and thermal strength at temperatures above 1000 C and their yield point was above 1520 C. The elements with refractory property include La, Ta, Al, Si, Mg, Ca, Cr, Zr, Be, Th and Ce that are found as composites in the minerals. For example, Al and Si as alumina and silica are the most important factors in kyanite and clay minerals. Andalusitic refractories have good strength against abrasion and creep and are used in high fountain steel smelters.
Iran that has resources of andalusite, is an importer of this type of refractory. There are two low grade (20%) andalusite mines in the east of Iran near Nehbandan and Fariman.
The results of mineralogy study on 20 samples by XRD and thin and polished sections show that quartz and andalusite are main forming minerals of Fariman deposit, plus to biotite, muscovite and feldspar. There is less than 1% opaque minerals in this deposit. Application of Image analyzer for this deposit yielded a 20% grade of andalusite. In some areas such as Qandab the grade reaches to 27%. In the processing test, the alumina content increases from 13% to 52% and silica decrease from 72.86% to 44.79%. After crushing the samples show better liberty.
Considering the grade, mineralogy, geochemistry, and ore dressing test of Fariman deposit, it is applicable for production of acidic refractory martial. The product can be used for steel plants of country.