Abstract
For the assessment of clay deposits for some ceramic industry, seven clay samples from different locations were collected by channel sampling method from Injana, Mukdadiyah, Bai Hassan Formations and Quaternary deposits in Bestana village, the study area is located east of Erbil city (NE Iraq).
The mineralogical study revealed the presence of common clay minerals including; kaolinite, smectite, illite and chlorite with some mixed clay and non-clay minerals e.g. quartz, calcite, dolomite and feldspar. The physical properties including grain size analysis and Atterberg limits showed that the raw materials contains clay in high proportion, silt in medium proportion and sand in minor proportion. Plasticity index of the studied samples showed that they are moderately plastic to plastic.
The chemical analysis of the studied samples showed that, the clay raw materials are composed mainly of silica and alumina, which act as refractory material in ceramic industry. In addition to that, there are different proportions of calcium, iron oxides, magnesium, potassium, and sodium, which are considered as flux oxides.
For the evaluation test purpose, 84 rectangular briquettes (1x4x8 cm) were prepared by semi-dry (8%water) pressing method (250Kg/cm²), fired at 800, 900, 1000, 1080ºC, for the evaluation tests of color, linear shrinkage, apparent porosity, water absorption, bulk density, efflorescence and modulus of rupture, and 28cylindrical briquettes (4 cm height and diameter) were prepared for the evaluation test of compressive strength.
The evaluation tests showed changes in the physical and mechanical test results, in which the apparent porosity, water absorption, efflourescence negative linear shrinkage decreased, while bulk density, compressive strength and modulus of rupture increased with increasing firing temperatures. The color of the briquettes varied with different firing temperatures as a function of various mineralogical compositions. The dry sensitivity index (DSI) measured for the studied ceramic briquettes, showed high DSI, drying shrinkage and water content % values, due to this result they require low temperature drying for long periods of time by adding 7.96 to 13.54% water during briquette paste preparation.
Comparing these evaluation test results with the International standard specifications for ceramic industry, this study showed the availability of using all of the studied samples in clay brick industry, floor and wall tile industry, with Injana, Bai Hassan, and Quaternary deposits of Bestana village can be used in roofing tile industry. Samples from Mukdadiyah and Bai Hassan Formations can be used as chemical resistant tiles when fired at 1080oC.
posts:28-2-2017