Date

2022-2

Author

Baydar, Hazal Melis

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Precipitated calcium carbonate (PCC) is used as a filler and extender in many different industries, particularly in paint, paper, plastic, adhesive, and sealant. Today, high purity limestone is preferred as a raw material for PCC production. In this study, it is aimed to use marble waste as an alternative raw material, which has nearly the same chemical composition as limestone. In this regard, the possibility of recycling the marble waste to produce PCC, a product with added value, was investigated. In the study, PCC production was carried out by the carbonation method, which includes the stages of calcination of stones, slaking of lime with distilled water, and carbonation of milk of lime with CO2. During the production stages, differences between limestone and marble waste were tried to be observed by using limestone as a reference raw material. The optimum calcination conditions were examined at calcination temperature values of 900, 950, and 1000°C for particle size intervals of -25.4+12.7 mm and -12.7+6.35 mm in varying calcination times for marble waste and limestone. As a result of the calcination experiments, it was observed that there was no difference between marble waste and limestone in terms of calcination efficiency. 20 minutes at 1000°C, after reaching the desired temperature with the preheating rate of 15°C/minute, was found to be sufficient to achieve a calcination efficiency of 98% and higher for both particle size intervals. In the hydration of lime experiments, varying lime to water ratios (1:3.5, 1:4.0, and 1:4.5) were examined to observe the reactivity of limes by monitoring the temperature increase during the process. It was observed that the reactivity of lime of marble origin was similar to lime of limestone origin, considering increases in temperature profiles. Carbonation experiments were carried out by using Ca(OH)2 concentrations of 5% and 10% at CO2 pressures of 5 and 10 bar. It was seen that PCCs produced from marble origin have almost the same particle size distributions as PCCs produced from limestone under the same precipitation conditions. The morphology of the produced PCCs was observed as rhombohedral. The result of experiments indicates that marble waste could be an alternative raw material instead of limestone for the precipitated calcium carbonate production.

Subject Keywords

Precipitated Calcium Carbonate (PCC), Marble Waste, Calcination, Carbonation, Recycling

URI

https://hdl.handle.net/11511/96270

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Graduate School of Natural and Applied Sciences, Thesis