Production of precipitated calcium carbonate from marble wastes

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Maden Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2013

Öğrenci: NURETTİN SEZER

Danışman: ALİ İHSAN AROL

Özet:

The aim of this study was to investigate the production of precipitated calcium carbonate from marble wastes. Limestone is used as the source for the production of precipitated calcium carbonate. Marble wastes primarily constitute of CaCO3. As the major content of the marble waste and limestone are the same, marble wastes can be used as an alternative source for the production of precipitated calcium carbonate. By this way, both the adverse environmental effects of marble wastes can be prevented and the wastes can be used as a cheaper source for precipitated calcium carbonate manufacturing industry. Waste samples were dissolved in pure water in an autoclave of 1 liter capacity by addition of CO2 gas. Contained aqueous carbonates were precipitated by evaporation of the CO2 in the solution. Concentration of dissolved carbonate species was examined for each test. Microstructure of the marble wastes used in the experiments and the precipitated calcium carbonate obtained from the experiments was investigated by Scanning Electron Microscopy, and their chemical analyses were carried out. The results of the chemical analysis were comparatively evaluated. The studies revealed that the precipitated calcium carbonate can be produced from marble wastes. By the experimental studies, the required conditions for production have been determined. In general, the experimental results in different conditions revealed that high CO2 pressure, lower ambient temperature and high stirring speed had positive effect in the dissolution of waste samples. The best result was obtained as 4.73 g/L dissolved CaCO3 under the conditions of -250 +106 µm particle size, 1400 rpm stirring speed, at 2 h, 8 °C and 10 atm CO2 pressure. The study recommends marble wastes as an alternative resource to manufacture precipitated calcium carbonate with sufficient quality to meet the industrial requirements.