remove Fe via magnetic separation. Marble and limestone sludges exhibit a strong predominance of calcite, confirming their calcium-rich nature. The marble sludge has a very fine particle size distribution, with 90% of the material finer than 100 µm (D90 ≈ 100 µm). Chemically, the sample is dominated by CaO and a high carbonate content (Loss on Ignition ~41%), consistent with the mineralogical analysis, which identified calcite (approx. 90%) as the major phase. The material presents an alkaline natural pH (ranging from 7.6 to 7.9) and demonstrated environmental stability during leaching tests, with pH stabilizing around 8.2–8.5, confirming its suitability for safe valorization in the construction industry. Comprised mainly of fine marble dust, water, and small marble particles, marble sludge can be used as a supplementary cementitious material to enhance the properties of concrete. The limestone sludge presents a particle size distribution ranging from 0.3 to 182 µm. Compositionally, the sample is characterized by high mineralogical purity, with calcite (95.2%) as the dominant phase, which correlates with chemical analysis showing CaO (~54%) as the major oxide and a total carbonate content of 87.5%. The material exhibits an alkaline natural pH (7.6–8.5) and demonstrated chemical stability during batch leaching tests, where pH values settled between 8.2 and 8.5, confirming its carbonate nature and low environmental risk for valorization. The properties of the limestone sludge are suitable for application in building materials such as bricks, tiles and cement.
RkJQdWJsaXNoZXIy MTM0Mzk2