Asbestos is the common name applied to a group of natural, fibrous silicate minerals, which were once one of the most popular raw materials to be used in building materials. Asbestos was mainly used for the production of assortment asbestos cement products. Today it is generally known that asbestos belongs to the group of hazardous materials and shows carcinogenic activity. It is therefore advisable to attempt to dispose of asbestos minerals in asbestos-containing materials and to convert them into a harmless material. One of methods may be microwave thermal decomposition of asbestos minerals. The research was used for old etemit roof ceiling. X-ray analysis indicated the presence of undesirable chrysotile. Its thermal destruction was carried out in a microwave oven in the power of 2500 W. In case the heating time was 15 min, X-ray analysis was confirmed chrysotile change into harmless minerals. Thermal analysis was used for characterization and the thermal behaviour of the asbestos cement sample.

In mineral processing, the use of microwave radiation is important especially in pre-treatment processes. At present, there is an acceleration of processes as well as an increase in the efficiency of metal recovery. One of the main problems in copper recovery from complex sulphide ores is the removal of impurities such as antimony, arsenic, mercury. In the hydrometallurgical processing scheme, the key step is the leaching. The extraction process can be influenced by the selection of suitable leaching reagents or by suitable pre-treatment of the ore. The article describes the effect of microwave radiation on the leaching Sb, As and Hg of tetrahedrite and tetrahedrite concentrate. The samples were irradiated at the power 900 W for 30 seconds. The leaching of irradiated and non-irradiated samples was realized in an alkaline sodium sulphide. The positive effect of microwave radiation was confirmed by an increase in the recovery of Sb and As already after 15 min of extraction. After microwave leaching of irradiated tetrahedrite samples, the yield of Sb was 43.2 %, in irradiated tetrahedrite concentrate, the yield of Sb was 81.3 %.

The presented article focuses on the possibilities of using microwave energy in the treatment of flue dust originating from the production of steel in EAF, as well as flue dust arising in the hot-dip galvanizing process of steel. The mentioned types of waste in the form of flue dust contain significant amounts of zinc (22-43%) and iron (0.6-30%), which could be reused after heat treatment in the sense of a circular economy. Since zinc is also found in the mentioned wastes in the form of a stable spinel structure of franklinite (ZnFe2O4), its treatment through microwave roasting in the presence of suitable susceptors of electromagnetic radiation is a prospective method of obtaining pure metals. The advantage of microwave processing is the volumetric nature of the heating, the faster course of carbothermic reactions and the sufficiently lower temperature of the waste treatment compared to conventional heating.

Thermal analysis describes the changes of physical and chemical properties of materials depending on increasing temperature. Thermogravimetric analysis of rape residue sample has been carried in inert atmosphere. The samples were heated over a range of temperatures that includes the entire range of pyrolysis with three different heating rates of 5, 10 and 15°C min -1 . Thermogravimetric (TG) curves were obtained from experimental data. The results obtained from thermal decomposition process indicate that there are main stages such as dehydration, active and passive pyrolysis. The first region from 50°C is related to the extraction of moisture and adsorbed water in samples. The main pyrolysis process proceeds in a range from approximately 250 to 450°C. The activation energy values as a function of the extent of conversion for the pyrolysis process of rape residue have been calculated by means of the Flynn Wall Ozawa method. The activation energy for the pyrolysis of rape residue was 99–189 kJ.mol -1 in the conversion range of 0.2–0.8. The average activation energy calculated by this method was 142 kJ.mol -1 .

Magnesite belongs to the most significant minerals of Slovakia. According to various statistical reviews Slovakia is in 4th–6th place in the world and its share ranges 2.25–3.63 % of total world production (Reichl et al., 2015; Brown et al., 2015). Magnesite occurs in the belt from Lucenec to Kosice (south of central–east Slovakia) in the form of Fe-variety called breunnerite (commonly 10–30%, but also 8–17% or 5–50% FeCO 3 ), i.e. ferroan magnesite (Mg 0.9-0.7 Fe 0.1-0.3 )CO 3 usually containing about 9% FeO (Šalát and Ončáková, 1966). As to CaO/SiO 2 ratio (modulus C/S >2 or < 2), the both technological magnesite types, namely limy and silica ones occur. For this reason the research on magnesite and magnesia upgrading is focused on calcium and silica reduction. It is also important to observe behaviour of iron in separation process. So, the contribution deals with the magnetic separability determination of calcined magnesite ore fines from the Mútnik deposit (silica type). The content of fines –0.5mm can attain 25–30%. The behaviour of this material in high gradient magnetic field of separator was studied on the basis of magnetic fractions analysis and mass yields. The product of best quality with the content of 81.91% MgO at a mass yield of 82.77% and MgO recovery of 89.19% was won at the induction of 0.06T. An enhancement of magnetic field induction resulted in mass yield growing, recoveries increasing of all components into magnetic product and finally, in its gradual contamination by gangue components. So, a magnetic product with the MgO content of 79.98% at a mass yield of 91.07% and MgO recovery of 95.81% was prepared at the highest induction, i.e. 0.45T. Magnetic separability analysis with regards to feed quality into separation enables to preset the suitable induction of field to achieve the required quality of separation products.

Bentonite is widely used as a sorbent due to its high specific surface area and ion-exchange capacity; however, its properties can be significantly influenced by the presence of additional mineral phases and chemical modification. In this study, the influence of manganese oxides and quartz sand on the sorption properties of bentonite from the Stará Kremnička was systematically investigated, with particular attention to surface characterization by X-ray photoelectron spectroscopy (XPS). The materials were also characterized by X-ray diffraction, FTIR spectroscopy, and zeta potential measurements. XPS analysis revealed that manganese in all modified samples was predominantly present in the Mn(IV) oxidation state, with Mn 2p₃/₂ binding energies of 642.5–642.7 eV, corresponding to MnO₂-type phases. Deconvolution of the O 1s spectra confirmed the presence of lattice oxygen, silicate oxygen, and surface hydroxyl groups. The reason for the modification of mainly natural materials with manganese oxides is their higher affinity for the adsorption of heavy metal cations. The maximum adsorption capacity of natural bentonite was 63.29 mg/g. In bentonite samples modified with manganese oxides, the value increased to 103.09 mg/g for BMn, and to 116.28 mg/g for the MMn mixture. The results demonstrate that sorption behavior is governed by a combination of ion exchange on bentonite and interactions with Mn oxide surface phases, providing new insight into the role of Mn(IV) species in surface-controlled metal binding processes. These findings highlight the importance of surface chemical states in designing efficient bentonite-based sorbents.