1,720,972 research outputs found
Recovery and valuation of ultrafine marble dust contained in waste slurries deriving from carbonatic natural stones processing plants
Full text linkThe research, conducted in Italy and in Spain, aims at recovery and enhancement of marble powder, deriving from marble processing plants, in the building sector. The building industry is very capable of incorporating and reusing different types of waste materials deriving from different industries. The goal of the investigation is to identify potential uses for the sawing sludge as an alternative to its disposal in dumps, a practise no compatible with the concept of sustainable development. By utilizing the stone processing waste retrieved through recovery-recycling operations this material is no longer considered as waste but as primary or secondary raw materials for use in other production processes, thereby pursuing the dual objective of minimizing waste generation and disposal and producing added value. The investigation focused on the marble district area in Orosei (North-East Sardinia). Firstly, chemical physical and mineralogical determinations were carried out in order to characterize the material; secondly, test specimens were prepared to be submitted at the experimental phase, including mechanical studies. The data emerging from the chemical and mechanical analysis demonstrate the feasibility of these uses (concrete production; brick making; plaster industry; autoclaved aerated concrete manufacturing). Economic evaluation is also considered.
---------------------------------------------------------------------------------------------------------------------------------La ricerca svolta, in Italia ed in Spagna, è stata finalizzata al recupero ed alla valorizzazione, nel campo dei materiali per uso civile, del carbonato di calcio micronizzato proveniente dalle torbide recuperate dagli impianti di segagione e trattamento del marmo. Di fatto, il settore edile è capace di incorporare e di riutilizzare svariati tipi di materiali di scarto prodotti da differenti attività industriali. Nello specifico l’obiettivo della ricerca è stato quello di identificare possibili utilizzi per i fanghi di segagione così da ottenere soluzioni alternative al loro conferimento in discarica, procedimento questo non più compatibile con il concetto di sviluppo sostenibile. Attraverso l’utilizzazione dei rifiuti di lavorazione questi prodotti di scarto non vengono più considerati come rifiuti ma come materie prime o seconde da inserire in ulteriori processi produttivi, conseguendo così il duplice obiettivo di minimizzare le generazioni dei rifiuti da smaltire in discarica e di ottenere un valore aggiunto per le imprese detentrici di tali residui. Lo studio si è concentrato sul polo estrattivo di Orosei (Nord-Est Sardegna). In primo luogo si sono effettuate le determinazioni chimiche, fisiche e mineralogiche per caratterizzare il materiale; in secondo luogo, sono stati preparati provini per sottoporli alle successive fasi della sperimentazione. I risultati ottenuti dimostrano la fattibilità delle applicazioni considerate (produzione di calcestruzzi, mattoni per edilizia, stucchi e calcestruzzo areato autoclavato). Nel presente studio è inoltre proposta una valutazione economica
Marble processing for future uses of CaCO3-microfine dust: a study on wearing out of tools and consumable materials in stoneworking factories
Full text linkThe 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
The effects of solar UV radiation on the gloss values of polished stone surfaces
No full textNatural stones, each featuring different physical, mechanical, chemical, mineralogical and petrographic properties, play an important role in construction because they are often used as cladding or paving/flooring materials. The physical and mechanical properties of the materials used as for cladding and/or flooring open areas are affected by both the environment and people. In construction projects, gloss value is one of the most essential physical features of natural stones that is used as a reference for cladding or flooring materials. Solar exposition, often in combination with other environmental factors, has a considerable importance in the aging of natural stones, particularly at lower latitudes. In order to determine the stone behaviour in the areas exposed to sunlight, gloss value was investigated using a thermostatic chamber. In this study, the effect of UV irradiation cycles on the surface brightness of polished natural stones and the relationship between gloss values and some physical, mechanical properties and calcite grain size of natural carbonatic stone samples were elucidated. As a result, it appears that marble samples have less gloss variation if compared with limestones
Recovery of sawdust resulting from marble processing plants for future uses in high value added products
No full textThe disposal of microfine marble sawdust contained in marble slurry waste, currently represents an additional economic burden for dimension stones companies. This is because the sawdust is considered less important in comparison with the crushed calcareous aggregate produced in stone processing
plants. In addition, the sludge is mistakenly viewed as waste that has to be disposed of in landfill. State of the art in recovery and utilisation of calcareous sawdust is mainly aimed in uses as substitute for more expensive ingredient in the building sector. Moreover limestone dust, recovered from marble sawing and
processing slurry, has not yet found real economically feasible industrial usage. Due to the high market value of micronised CaCO3, we study the use of limestone sawdust as functional filler in industrial products having higher added value, such as paper, rubber, paints, pharmaceuticals. Standard requirements
of CaCO3 for this kind of products are very tight, especially those relating to purity level, particle size distribution and brightness. The high Calcium limestone deposit and the factories in Orosei Marble producing area (Sardinia, Italy) allow the production of high quality microfine dust. To evaluate the properties of the sawdust, several analysis were carried out to compare the results with the standard requirements of CaCO3 for paper, rubber and tyre production. The assessment concerns five different factories and it highlights the possible usage of the sawdust produced in Orosei by carrying out simple and inexpensive changes in both stone-working process and wastewater treatment. Finally, a commentary on environmental laws pertaining to the recycle of this kind of waste is also made in this paper
Sustainable reuse of marble sludge in tyre mixtures
Full text linkThe problem of the large amounts of waste products deriving from ornamental stone industrial activities affects not only the environmental impact but also the resources maintenance and the problem of waste management. This paper presents the essential features of an environmentally attractive reuse of what is currently considered a marble waste: marble sludge, recovered from marble sawing and slurry processing. A research is currently carried out in order to join this by-product with possible industrial applications. Simplified rubber formulations, filled with dewatered marble sludge and cross-linked by vulcanization, have been investigated with the objective of making a comparison with tyre compound obtained by using commercial calcium carbonate filler. From this, rigorous analyses have been carried out. The structural effect of calcium carbonate particles on tyre mixtures tensile strength, hardness, rheometric and morphological properties was inspected. The investigation focused on the materials collected by Orosei marble producing area (NE Sardinia - Italy) and it was carried out in cooperation with the Research & Development Laboratory by Marangoni Spa (Italy). The data emerging from the tests demonstrate how environmental burdens in conjunction with stone production could be reduced to much lower levels, by identifying the way to use marble sludge as filler in high added value products
Circular economy in marble industry: from stone scraps to sustainable water-based paints
Full text linkHuge amounts of sludge waste are produced every day during the sawing and processing of carbonate ornamental stones. Most of these materials are landfilled and create serious environmental and health hazards. Thus, it is mandatory to find alternative solutions to recycle them. Since calcium carbonate is the most widely used mineral filler for interior and exterior emulsion paints, this investigation focused on the feasibility of trying out innovative methods of circular economy in a waste processing area. Focusing in the Orosei Marbles’ producing area (North-East Sardinia, Italy), the aim of this study was to compare the performance of water-based paints, through the use of marble sludge waste, as mineral fillers, rather than commercial CaCO3. According to standard normative tests were carried out on paint samples, prepared according to an experimental formulation, after a preliminary chemical and physical characterization of the fillers. The results indicate that the marble sludge waste can be successfully used as mineral filler in water-based paints, and that it requires only light pretreatments consisting of deagglomeration and mechanical dispersion in a wet medium, thus confirming its environmental and economic benefits
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