Abstract
Abstract The study aimed to characterize the mineral wools obtained from wastes of the cutting step of marble and granite, in order to evaluate the possibility of their use on an industrial scale. Mixtures of marble and/or granite wastes were prepared in order to reach the chemical composition of rock and glass wools. The batches were melted in an electric arc furnace in laboratory scale at 1450oC and casted with water, in order to obtain a higher cooling rate. Characterization work was performed in batches that formed vitreous material, and with superior incorporation of the residues: 11.7% and 14.6% of marble waste with glass wool and rock wool, respectively; 78.3% and 91.6% of an association of marble and granite wastes with glass wool and rock wool, respectively. Computational thermodynamics was used in order to obtain the main phases at 800oC and determine the liquid and solid content at 1400, 1450 and 1500oC. In addition, the materials obtained were characterized via chemical analysis using X-ray fluorescence, DTA, X-ray diffraction and SEM. The results indicate that the marble and granite waste are composed mainly of CaO (34.7 wt.%) and SiO2 (66.3 wt.%), respectively. An amorphous crystalline structure was obtained in all tests, indicating that this material can be used as an insulation material. The crystallization temperatures were determined around 800oC.
Highlights
The Brazilian production of ornamental rock was 9.5 Millions of tons in 2015, in which 52.58% was finished product, i.e. polished plates or other finishing
The waste generated by the ornamental rock sector is mainly composed of oxides, where the marble waste is composed mainly of CaO and magnesium oxide (MgO), and the granite waste is composed mainly of SiO2 and Al2O3
Vitreous materials were formed using residues from the ornamental rock cutting step in the proportion of: 11.7% and 14.6% of marble waste with glass wool and rock wool, respectively; 78.3% and 91.6% of an association of marble and granite wastes with glass wool and rock wool, respectively
Summary
The Brazilian production of ornamental rock was 9.5 Millions of tons in 2015, in which 52.58% was finished product, i.e. polished plates or other finishing. During the step of the blocks sawing to obtain the plates, it is estimated that there is a loss in the range of 20-30% of the blocks. This suggests a waste production in the range of 1.0-1.5 millions of tons per year (Mashaly et al, 2016). The waste generated by the ornamental rock sector is mainly composed of oxides, where the marble waste is composed mainly of CaO and MgO, and the granite waste is composed mainly of SiO2 and Al2O3. This waste is deposited in a tailings dam close to the companies, which causes serious environmental problems (Junca et al, 2015).
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