Nicola Careddu

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.

Mine simulation for educational purposes: A case study

This paper presents a new simulation‐based computer program that provides an interactive and visual environment for teaching and learning of mining engineering related subjects. An actual open pit magnesite mine was selected and whole simulation data were obtained from this mine in order to create a simulation application. The program represents this open pit mine in detail using more than hundred variables, 14 windows, and several modules. It is believed that, with its all components, this educational tool can be used for several mining‐related subjects such as drilling and blasting, excavation and haulage, size reduction and magnetic separation at universities to provide fundamental information to the students and anyone dealing with mining engineering related subjects. It may also be used for mining related departments such as geology and geophysics for giving brief information about mining.

Diamond wire sawing in ornamental basalt quarries: technical, economic and environmental considerations

The market interest in ornamental rocks commercially referred to as “stones” has grown significantly in recent years, particularly regarding basalt. This has resulted in the widespread use of diamond wire equipped with sintered diamond beads for precision sawing in basalt quarries, especially those located in the industrialized countries; it also has the advantage of preventing rock damages. Diamond wire has been widely used in up-line cutting and other sawing works in both marble and granite quarries for decades; therefore, performance data about the use of this tool on these two different types of rocks are widely documented in academic literature. However, for basalt sawing, information pertaining to the use of diamond wire is unavailable due to various reasons, but mostly because of to its relatively recent introduction in the basalt quarries and also to the historical low market demand for processed basalt in the past. This study offers a possible solution to this lack of information and provides a technical, economic and environmental assessment of diamond wire used in quarrying basalt for ornamental purposes. After an overview on the state of the art of diamond wire and on the final use of processed basalt, the study describes the experimental plan and the results. These show a tool yield much higher than those measured when diamond wire is used on other silicate dimension stones (e.g. granites). Moreover, the composition of basalt sawdust (sludge) has been analysed in the laboratory and has indicated the absence of polluting materials related to tool wear; therefore, basalt sludge, which is made of water and micronized basalt, can be used as a secondary raw material for the environmental restoration of the area or for any other purpose. Further research on other lithotypes is also proposed.

Rosa Beta granite (Sardinian Pink Granite): a heritage stone of international significance from Italy

Abstract ‘Rosa Beta’ or ‘Sardinian Pink granite’, an Hercynian granitoid from the Italian island of Sardinia, is formally here nominated as a Global Heritage Stone Resource. Rosa Beta is sourced from the Gallura region of northern Sardinia and has been associated with human heritage since prehistoric times. Notably it can be found in construction ranging from prehistoric Tomba dei Giganti, the 1st century Pantheon in Rome and the Renaissance Cathedral in Pisa to early 20th century monuments in Brazil and Egypt. Most importantly, it has also been used very extensively in the late 20th century for significant construction in countries as wide ranging as the USA, Saudi Arabia, Hong Kong, Singapore and Australia.

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.

Sardinian Basalt—an Ancient Georesource Still En Vogue

Commercial basalt that is quarried in Sardinia is a natural resource which is the result of extensive volcanic activity during the Pliocene and Pleistocene ages, following the opening of the Campidano plain and Tyrrhenian Sea rift, when large volumes of basalt and andesite rock naturally moulded extensive areas of the Island. An example is provided by the “Giare” tablelands and several other large plateaus located in central Sardinia. Basalt has formed in many other areas of the Island, where a vast array of monuments dating back to the II–I millennium B.C. document the high workability, durability, and withstanding to weathering of basalt. The complex of circular defensive towers, known as “Su Nuraxi di Barumini” was included in the World Heritage List by UNESCO in 1997. Basalt is currently produced locally, and it is used for architectural and ornamental purposes. It is quarried from stone deposits or mined from huge boulders which are mechanically moved and sawn and then transported and manufactured in plants which are located in various sites throughout the Island. The paper begins with a historical introduction and then focusses on the current state-of-the-art of Sardinian basalt quarrying, processing, and usage. An analysis of the basalt market has been carried out.