The Use of Magnesite Waste as Feldspar Replacement in the Production of Ceramic Wall Tiles

摘要

The waste utilized in this work is the coarse fraction of inactive magnesia (MgO) that is discarded whenever only very fine magnesia active particles are required. This inactive magnesia is the magnesite (MgCO_3) raw material over fired at around 1000℃, when treated in a simple primitive method onsite, in the South Eastern Desert of Egypt. It is suggested as total or partial replacement of the fine expensive potash feldspar in the basic mixture used for manufacturing ceramic wall tiles from Egyptian raw materials. The experimental program includes assessment of nine Egyptian raw materials, using XRF and XRD. On the other hand, the magnesite waste was subjected to XRF and XRD, DTA and TGA. Two mixtures were prepared so as to replace 50 mass-% and 100 mass-% (total replacement) of fine feldspar by the waste, while a third mixture involves total replacement of fine feldspar by waste and reduction of glass sand from 12 to 7 mass-% while increasing the cheaper coarse feldspar content from 18 to 23 mass-%. Mixtures of glazed and unglazed samples were prepared, pressed into tile form, dried and fired through a fast single firing technique. Physical, chemical and mechanical properties were then measured and compared to both ISO and Egyptian Standards. Fired samples were also subjected to SEM in order to assess the existing phases and minerals. All the prepared mixtures showed conformity to both Egyptian and International standards of ceramic wall tiles.