Search Results (11)

The processing of dimension stones for the construction sector involves transforming rock blocks into slabs via sawing and polishing. This process generates a fine-grained waste composed largely of rock powder derived from the processed rock. Several studies indicate that the rock powder produced as a processing waste can release Ca, Mg, and K. However, alongside the release of macronutrients, there is the possibility of releasing undesirable constituents, such as Na, which is also a component of the minerals forming silicate rocks. This study aimed to analyze the risk of salinization that these materials may cause to soil if applied without a thorough evaluation of their composition. Samples were analyzed in terms of physical, chemical, and mineralogical parameters; exchangeable inorganic constituents; percentage of exchangeable sodium; and sodium adsorption ratio. The data indicate that residues stored in landfills in a random and unsorted manner do not fully meet the criteria established by Brazilian regulations for soil remineralizers. However, their characteristics suggest good potential for use in the agricultural sector, although this would require blending with other agricultural inputs and/or segregating residues from certain types of rocks to comply with current regulations. Full article

Asbestos is a fibrous variety of certain minerals, some of which occur naturally as an accessory to a wide variety of mineral resources. Although asbestos itself has been historically mined for various useful properties, the negative health effects of asbestos dust have greatly diminished it as a useful earth material, as many countries have banned the use of these fibrous minerals based on those health concerns. Resulting regulations of asbestos have focused primarily on intentionally mined material used in product manufacturing, such as building materials made with beneficiated asbestos and their derivative exposures, e.g., airborne asbestos in schools with asbestos-containing materials. The hazards of asbestos as unintended byproducts have not been as extensively considered, although this “contamination” has been repeatedly observed in common earth materials including talc, vermiculite, sand, and gravel. This study reveals such contamination of ornamental and dimension stone commonly referred to as “marble”. Asbestos types that can be associated with certain Indian marble reserves include asbestiform tremolite, actinolite, anthophyllite, and chrysotile asbestos. This case reveals such contamination in a marble reserve in Rajsamand, Rajasthan. At this location, marble dust in slurry is disposed at waste collection points, unfortunately including a location now open to the public that has become a tourist destination. Using Transmission Electron Microscopy (TEM) in this study, dust from this location revealed abundant tremolite asbestos fibres in the disaggregated dust. This poses potential health risks to the workers, bystanders, and tourists that may be exposed to this recognized carcinogen, a known cause of mesothelioma, lung cancer, and other asbestos-related diseases. Full article

Brazil stands out as one of the main producers of dimension stones and, in order to maintain sustainable production, the principles of environmental sustainability have been increasingly desired. The importance of studying sludge from dimension stone processing is not only based on the economic and environmental burden that its waste disposal represents for the sector but also on the opportunity to use a material that can reduce the extraction of other mineral goods. This study aimed to describe the characteristics of this sludge at different stages of the processing to evaluate the differences between the material circulating in the production process and after dehydration, when it becomes a residue to be disposed of. Aluminum, iron, manganese, and barium concentrations were high in the liquid phase of the sludge, but they were reduced considerably in the solubilized extract. The hydrogen potential reduced, falling below the threshold of corrosivity, after the withdrawal of the liquid phase. Elements with concentrations higher than the maximum allowed value for inert wastes come from both the inputs used in the processing and the processed stone itself. Initiatives to segregate materials from different sources and investments for the creation of eco-products that can replace inputs, besides the use of wastes, should be encouraged to work towards sustainable production. Full article

Critical raw materials (CRMs) supply is a challenge that EU countries have to face, with many thinking about domestic procurement from natural ore deposits and anthropogenic deposits (landfills and extractive waste facilities). The present research focuses on the possibilities linked to the supply of CRMs and the potential for exploiting rare earth elements (REEs), investigating a large variety of extractive waste and siliceous rocks in the Piedmont region (Northern Italy). Indeed, the recovery of REEs from the extractive waste (EW) of siliceous quarries and other siliceous ore deposits can be a valuable way to reduce supply chain risks. Starting with a review of the literature on mining activities in Piedmont and continuing with the sampling and geochemical, mineralogical, petrographic, and environmental characterization of EW facilities connected to siliceous dimension stones, of kaolinitic gneiss ore deposits, and of soils present near the investigated areas, this study shows that the degree of REEs enrichment differs depending on the sampling area (soil or EW) and lithology. The concentration of REEs in the EW at some sampling sites fulfils the indicators of industrial-grade and industrial recovery; the high cumulative production and potential market values of EW and the positive recovery effects through proven methodologies indicate a viable prospect of REE recovery from EW. However, REE recovery industrialization faces challenges such as the difficulty in achieving efficient large-scale recovery due to large regional differences in REE abundance, the mismatch between potential market value and waste annual production, etc. Nonetheless, in the future, EW from dimension stone quarries could be differentially studied and reused based on the enrichment and distribution characteristics of trace elements. The present paper shows investigation procedures undertaken to determine both CRMs potentialities and environmental issues (on the basis of literature data employed to select the more-promising areas and on sampling and characterization activities in the selected areas), together with procedures to determine the waste quantities and tentative economic values of REEs present in the investigated areas. This approach, tested on a large area (Piedmont region), is replicable and applicable to other similar case studies (at EU and non-EU levels) and offers decision makers the possibility to acquire a general overview of the potential available resources in order to decide whether and where to concentrate efforts (including economic ones) in a more detailed study to evaluate the exploitable anthropogenic deposits. Full article

This review paper examines extraction methods in the dimension stone industry. Traditional techniques, like thermal shock, hammer and chisel, and plug and feather, were used historically. However, advancements in technology have led to the adoption of mechanized methods. Diamond wire cutting is a highly efficient technique that reduces waste and ensures quality. Challenges like high costs and wire breakage remain. Circular diamond saws and frame sawing are explored as alternative methods. Stone characteristics influence machinery selection and researchers have studied the impact on extraction efficiency. Controlled blasting with explosives shows promise and requires further exploration and optimization. Full article

Climate change concerns have goaded countries toward seeking renewable energy options (bio-energy being one of them) to replace/supplant the conventional fossil-fuel alternatives (coal, oil and natural gas) commonly used now. Fuel pellets—at the confluence of the forestry, agriculture, waste management and bio-energy sectors—when produced from biomass residues, serve the dual purpose of ensuring energy security and environmental sustainability. By valorizing more and more organic wastes to bio-energy products, one could, to use the old adage, ‘kill two birds with one stone’. Social LCA is a method used to analyze a very wide range of social issues associated with the stakeholders in a value chain—workers, local community dwellers, society, global consumers, banks, investors, governments, researchers, international organizations and NGOs. In this analysis, the authors commence with a highly focused, niche literature review on the social dimension of sustainability in the African energy/bio-energy sector. The streamlined social footprint analysis inspired by the relatively lesser number of such studies for this sector in Africa is not a novel addition per se to the S-LCA knowledge base. The purpose of the application is to shed light on something in Zambia that must be understood better so as to bring about much-needed alterations in the direction of sustainable development. While the questions addressed to four different groups of stakeholders encompass a clutch of sustainable development goals, gender equality (SDG 5) and the need for greater interest on the part of governments and investors (SDG 9) to look at sustainable alternatives to the status quo stand out as concerns that need to be tided over. This paper and the streamlined social footprint analysis carried out are all the more relevant and timely when one considers some key changes that have happened in Zambia over the last five years—the implementation of the National Energy Policy in 2019 and the creation of the Ministry of Green Economy in 2021. These are verily harbingers of positive change auguring well for future developments in the bio-energy (and bio-pellets) sector, not just in Zambia but, by way of emulating and learning, in other countries on the continent. Full article

The problems generated by the ornamental stone extraction and processing industry caused by the inadequate disposal of this waste can negatively affect rivers, lakes, streams, and even natural water reservoirs. This study discusses and evaluates the potentiality and challenges of dimension stone waste (DSW) recycling generated from a Brazilian dimension stone processing industry in Portland cement formulations. Cement pastes with different amounts of DSW (10–30 wt.%), quartz (10 wt.%), and calcium carbonate (10 wt.%) were prepared and characterized in the fresh and hardened states. The results showed that DSW can be used in cement formulations, and its reactivity is governed by the size of the particles. With up to 10% DSW in place of cement, the samples had greater workability and compressive strength at 28 days compared with the reference mix. However, the strength was lower at early ages (3 and 7 days). When DSW is milled, the strength of the samples containing the waste matched the reference values at all ages, and the recommended replacement limit rose to 20%. On the other hand, the particle size reduction significantly decreased the workability. The use of DSW in cement-based formulations is encouraged due to the strong presence of stone processing and cement companies in Brazil and worldwide. Full article

This study investigates the cyclic behavior of sand mixed with waste tires by using a series of strain-controlled cyclic direct shear tests under constant normal load (CNL) conditions. Crushed Stone Sand (CSS) was used in the experimental studies. The sand grains have angular shapes and sizes changing from 1.0 mm to 2.0 mm. Two different types of waste tires were used in the experiments; (i) tire crumb (TC), and (ii) tire buffing (TB). The TC grains have an angular shape and size between 1.0 mm and 2.0 mm, whereas TB grains used were found to be fiber-shaped, with dimensions changing from 1 mm to 9 mm, and an aspect ratio of about 1:5. The tests were carried out under 100 kPa vertical effective stress on the sand with 0%, 2.5%, 5%, 7.5%, and 10% waste tire contents. The testing results were found to be highly dependent on both the type and amount of waste tires in the mixtures. Furthermore, the behavior of the mixtures was estimated by the Bayesian Regularization Neural Network (BRNN) prediction model, for further use by researchers. The performance of the proposed BRNN model was found to provide a quite high correlation coefficient (R² = 0.96). Full article

The growing demand for raw materials requires the optimization of extractive processes and innovative approaches, such as the recovery of quarrying and processing waste. Waste materials from gneiss (ranging from blocks up to residual sludge) used as dimension stone (Beola and Serizzo from Piedmont, northern Italy) were characterized for chemistry, mineralogy, and petrography: quartz and feldspars (plagioclase and K-feldspar) are the most abundant minerals, followed by micas (biotite and minor muscovite) and traces of chlorite and epidote (allanite). Quartz and feldspars could be reused in the industrial minerals sector, especially in the ceramics industry; depending on the purity requirements of the raw materials, some mica separation treatments may be required. The most critical issues relate to the small grain size and the relative abundance of mica in some commercial varieties. The presence of allanite opens new possibilities for the recovery of rare earth elements (REE, critical raw materials). Full article

Natural dimension stone processing generates large volumes of stone waste, which have a significant impact on the environment, as well as on the efficiency and profitability of the stone-processing plant. The article presents the characteristics of waste produced as a result of natural dimension stone processing and the structure of the waste production process. Solid stone scraps and sludge were distinguished. On the basis of the performed analyses, it was shown that stone waste constitutes 10–35% in relation to the quantity of the processed stone material, with the quantity of sludge being even threefold greater than the volume of solid scraps. According to the circular economy principles, the aim should be to reduce the amount of waste generated by reducing primary resources in favour of secondary material. Reducing the volume of stone waste is possible through rational planning of stone production while at the same time maximising the efficiency of stone material usage and introducing the most modern processing machines. This significant volume of stone waste encourages efforts to find solutions for both its management and reduction. This paper reviews the utility potential of stone waste. Sensible use of waste is important to increase the profitability and productivity of processing plants while incentivising environmental protection. Full article

Marble is currently a commonly used material in the building industry, and environmental degradation is an inevitable consequence of its use. Marble waste occurs during the exploitation of deposits using shooting technologies. The obtained elements most mainly often have an irregular geometry and small dimensions, which excludes their use in the stone industry. There is no systematic way of disposing of these massive mounds of waste, which results in the occurrence of landfills and environmental pollution. To mitigate this problem, an effort was made to incorporate waste marble powder into clay bricks. Different percentage proportions of marble powder were considered as a partial substitute for clay, i.e., 5–30%. A total of 105 samples were prepared in order to assess the performance of the prepared marble clay bricks, i.e., their water absorption, bulk density, apparent porosity, salt resistance, and compressive strength. The obtained bricks were 1.3–19.9% lighter than conventional bricks. The bricks with the addition of 5–20% of marble powder had an adequate compressive strength with regards to the values required by international standards. Their compressive strength and bulk density decreased, while their water absorption capacity and porosity improved with an increased content of marble powder. The obtained empirical equations showed good agreement with the experimental results. The use of waste marble powder in the construction industry not only lowers project costs, but also reduces the likelihood of soil erosion and water contamination. This can be seen to be a crucial factor for economic growth in agricultural production. Full article