THE EFFECT OF BLUNGER SELECTION ON POST-FIRING PROPERTIES OF ILGIN CLAYS IN CERAMIC PRODUCTION
GENC S. 1,2, KAYACI K. 1, TASKIRAN U. 1, YILDIRIM Y. 1
1 Kale Seramik Çanakkale Kalebodur Seramik San. A.?., Çanakkale, Turkey; 2 ?stanbul Technical University, ?stanbul, Turkey
The Ilg?n clays were deposited in the Neogene lacustrine sedimentary basin at the northern areas of the Çavu?çu lake (Konya, Türkiye). These are classified based on the coal seams of the basin as the under clays and upper clays.
The Ilg?n clays display an apparent stratigtraphy and it begins with the gray colored plastic clays at the bottom, followed by the dark gray colored clays and black colored clays which are interfingered with the lignites. These levels belong to the under clays. The light colored (beige) clays forms the topmost leveles of the Ilg?n clays and represented by the upper clays with respect to the lignite seams.
XRD examinations revealed that the upper clays, alternated with the lacustrine marls, formed from the illite + smectite + kaolinite + quartz + siderite ± dolomite ± aragonite ± hematite paragenesis. Clays interfingered with the lignites contain illite + quartz + dolomite + pyrite + gypsum. The black colored underclays have quartz + gypsum + illite + kaolinite + pyrite, and the gray colored plastic clays of the lowermost levels are characterized by the quartz + kaolinite + illite paragenesis (Ku?çu ve Y?ld?r?mlar, 2016). It is clear that the dark gray to black colors are due to the pyrite and organic materials.
In this study, the Ilg?n underclays are investigated. XRD analysis show that the main mineralogical composition is as follows: quartz + illite + kaolinite + pyrophyllite + goetite + anatase + montmorillonite + feldspar. According to the results of XRF analysis, chemical variations can be outlined briefly as Al2O3 %24-25, TiO2 %1-1.25, Fe2O3 %3.15-3.25 and SO3 0.07.
Dry strenght 40.9 kg/cm2, total firing shrinkage %7.1, water absorption % 0.3 and the fired colors (at 1200 C) L: 64.08, a: 3.62 b: 21.25 measured by the physico-mechanic tests. The main outcome of this study is that the fired colors of the Ilg?n underclays are variable and mostly depend on the blunger processes.
When Ilg?n underclays are processing with a blunger, the color is lighter because the ferrous minerals and carbon compounds remain on the screen residue, however when they are ground in the mill, these impurities are mixed into the raw material and the color becomes darker. In this case, the amount and type of minor minerals of the clays used in the production of ceramics and the application of the selected process significantly affect the post-firing performance. Therefore, before the clay group raw materials are used in ceramic bodies, it is possible to perform the "blunger" process with different methods and to obtain the whitest color possible.