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    In-situ capturing carbon dioxide capture by mechanochemical of K-feldspar with calcium oxide
    (Polish Soc Ecological Engineering-Ptie, 2025) Achimovicova, Marcela; Tothova, Erika; Balaz, Matej; Zubrik, Anton; Briancin, Jaroslav; Balaz, Peter; Erdemoglu, Murat
    Capturing carbon dioxide (CO2) emissions is necessary for a multi-faceted approach to combating climate change. It is only one of several essential strategies, including reducing emissions at the source, enhancing natural carbon sinks such as minerals and rocks, and transitioning to renewable energy sources. This pioneering study used abundant and cheap K-feldspar mechanochemically modified with CaO for in situ CO2 sequestration during planetary ball milling. These innovative novel in situ CO2 capture experiments consisted of two simple steps. The first step involved the mechanochemical modification of K-feldspar using CaO and the subsequent second step, direct in situ CO2 sequestration in the same milling chamber during milling. X-ray diffraction patterns demonstrated the formation of the calcite phase, and elemental analysis confirmed the binding of approximately 1.69% carbon, representing a CO2 mineralization ratio of 6.05% after 60 min of milling with CO2 gas. Infrared spectroscopy, and thermogravimetric analysis equipped with mass spectroscopy verified CO2 mineralization of CaO-modified K-feldspar. The morphology of the product after CO2 capture containing calcite and unreacted K-feldspar was monitored by scanning electron microscopy.
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    Modification of tetrahedrite Cu12Sb4S13 thermoelectric performance via the combined treatment of mechanochemistry and composite formation
    (Elsevier, 2024) Balaz, Peter; Burcak, Arda Baran; Aydemir, Umut; Mikula, Andrzej; Nieroda, Pawel; Balaz, Matej; Findorakova, Lenka
    Tetrahedrite Cu12Sb4S13 with its low thermal conductivity represents a flagship in sulphide thermoelectrics. However, to achieve a reasonable figure-of-merit ZT (measure of thermoelectric efficiency), adequate doping or special sample processing is needed. In this work, a different approach (without doping) is illustrated for the two tetrahedrite-containing systems. In the First approach binary composite tetrahedrite Cu12Sb4S13/chalcopyrite CuFeS2 was prepared by mechanochemical leaching with the aim to obtain partly decomposed tetrahedrite. In this approach, the alkaline leaching medium (Na2S + NaOH) was applied to extract Sb from tetrahedrite thus changing its composition. The obtained composite (formed from its own phases in an intrinsic mode) shows low values of ZT = 0.0022@673 K in comparison with the non-treated tetrahedrite where ZT was 0.0090@673 K. In this case the extremely high electric resistivity (6-20 m Omega cm-1) was documented. In the second approach binary composite tetrahedrite Cu12Sb4S13/muscovite KAl2(AlSi3O10)(OH)2 (formed from its own and foreign phases in an extrinsic mode) was prepared by two-step mechanical activation in which combined treatment of industrial vibratory milling and subsequent laboratory planetary milling was applied. The addition of a foreign phase, muscovite, did not give extraordinary thermoelectric performance results. However, the two-step milling process (without the addition of foreign phase) gives the value of ZT = 0.752@673 K which belongs to the highest in the tetrahedrite thermoelectric community. In this case, the two-times increase in specific surface area and the increased amount of tetrahedrite in comparison to famatinite are suspectable for this effect. Both applied nontraditional approaches to synthesize tetrahedrite composites form a platform for potential modification of its thermoelectric performance.
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    AN OVERVIEW OF SURFACE ANALYSIS TECHNIQUES FOR CHARACTERIZATION OF MECHANICALLY ACTIVATED MINERALS
    (Taylor & Francis Inc, 2012) Erdemoglu, Murat; Balaz, Peter
    Surface characteristics of particles; such as structure, morphology, and chemical composition of surface have a major effect on its response to metallurgical processing operations. In order to understand the characteristics and reactivity of the system, information on the physical topography, the chemical composition, the chemical structure, the atomic structure, the electronic state, and a detailed description of bonding of molecules at the surface are required. Most of the instrumental techniques used for identification of major/minor and bulk/surface characteristics of substances now can be easily utilized as well for the characterization of mechanically activated minerals. This article is concerned with several representative identification techniques which are currently used for characterization of the materials prepared by mechanochemical processes. Fundamental aspects of spectroscopic (Infrared, Raman, and X-ray photoelectron), electron microscopic (Scanning electron microscopy and Transmission electron microscopy), and probe microscopic (Scanning tunneling microscopy and Atomic force microscopy) techniques used for surface characterization of mechanically activated minerals are overviewed.
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    Utilizing Taguchi method and in situ X-ray powder diffraction monitoring to determine the influence of mechanical activation conditions on the physico-chemical properties and Al leachability of K-feldspar
    (Elsevier, 2024) Balaz, Matej; Birinci, Mustafa; Senturk, Kader; Achimovicova, Marcela; Balaz, Peter; Tampubolon, Imelda Octa; Stolar, Tomislav
    K-feldspar represents an important natural resource of potassium and aluminum. Within the framework of this study, the K-feldspar was mechanically activated in a planetary ball mill under different conditions planned according to 4(3) Taguchi orthogonal array experimental design. As outputs, specific surface area (S-BET), median particle size (d(50)), amorphization degree of mineral phases , and Al recovery were used. It was found that the initial d(50) value of 293 mu m could be reduced to 6.7 mu m and the S-BET value of 4.7 m(2)/g could be increased up to 32.5 m(2)/g upon milling. Both microcline KAl3SiO8, and albite NaAl3SiO8 could be almost completely amorphized, whereas quartz SiO2 still maintained some crystallinity even under the most intensive conditions. Increasing S-BET and decreasing the d(50) values did not lead to a significant improvement in Al leach recovery, whereas a clear relationship between the amorphization of microcline and the recovered aluminum was found. Analysis of Variance (ANOVA) showed that increasing ball-to-powder ratio is the most beneficial for the improvement in Al recovery. In situ powder X-ray diffraction monitoring performed in an oscillation ball mill under synchrotron irradiation has shown very rapid amorphization of microcline phase at the beginning. However, amorphization of microcline was only partial after two hours of the treatment in this mill, apart from almost complete process in the planetary ball mill. In the end, regressions for the calculation of Al recovery by knowing the values of input parameters were calculated. In general, by just using mechanical activation without the subsequent roasting process that is commonly used to boost metal recoveries, it was possible to quantitatively recover aluminum from K-feldspar.