Graziella Marras

Marble Processing for Future Uses of CaCO3-Microfine Dust: A Study on Wearing out of Tools and Consumable Materials in Stoneworking Factories

The demand for Limestone/Calcium Carbonate (LCC) has substantially grown up for the last three decades due to the widespread use of CaCO3 in many industrial applications, not only in construction but also in other important sectors (e.g., environmental, food, pharmaceutical, paper, etc.). LCC is currently produced within the quarry and in laboratory (during crushing, milling, washing, etc.). In dimension stone industry, almost 30% of the block (squared or shapeless) is lost during sawing/cutting/processing. In the case of the Orosei Marble (East Sardinia, Italy), the sludge deriving from processing is mainly composed of Calcium carbonate and it has a great potential as secondary raw material or by-product as long as the chemical properties of the sludge meet the parameters required by current environmental laws. The research presented in this paper aims to explain how tools wear out and how consumables end up in the sludge.

An Investigation of Colour Properties of Orosei Limestones (Italy) by Using Computer Program

In this study, a new computer program developed to determine the colour properties of natural stone products is introduced. The program can scan any digitalised picture of natural stone products and produce several statistical results such as mean, variance, minimum and maximum colour values, skewness and kurtosis values of the colour histogram, energy, contrast, entropy and homogeneity values of the data which may be used to classify the typology and/or quality of natural stone products. As a case study, Orosei limestones (Sardegna, Italy) were used. There are several typologies of Orosei limestones such as Nuvolato (Cloudy), Venato chiaro (Light veined), Venato medio (Medium veined), Venato scuro (Dark veined), Perlato chiaro (Light pearled), Perlato medio (Medium pearled) and Perlato scuro (Dark pearled). The remarkable results produced by the program are presented.