Papers by Andrea Miškufová
This work provides research and evaluation of the influence of active gama alumina addition on gr... more This work provides research and evaluation of the influence of active gama alumina addition on green and sintered CaO material properties, microstructures and mineralogical phase formation. Experimental results have shown the possibility to prepare more stable CaO with excellent properties by energy saving one-stage burning process of natural ground limestone with small addition of γ-Al 2 O 3 (1 wt. %) at up to 1550°C for two hours. The additive caused increasing of the sintered density but especially significant decreasing of apparent porosity of CaO. X-ray diffraction and energy dispersive X-ray fluorescence analysis confirmed mainly the presence of 3CaO•Al 2 O 3 on the grain boundaries. Formation of other phases during sintering, more specifically 12CaO•7Al 2 O 3 and CaO•6Al 2 O 3 with lower tendency to hydration was also proved. * measured by use of thermal analysis (Derivatograph C MOM, Budapest; heating rate of 10°C•min -1 ) ** measured by use of AccuPyc 1330 V1.
Spent Magnets from Waste Electronic Devices - A Source of Rare Earth Elements
2015-Sustainable Industrial Processing Summit, Mar 9, 2015
Nowadays, one of the significant secondary sources of the rare earth elements (REE) in Europe are... more Nowadays, one of the significant secondary sources of the rare earth elements (REE) in Europe are spent permanent magnets. The main application of Nd-Fe-B permanent magnets is in hard disc drives, but they also become an important part in green technologies, e.g. electric/hybrid vehicles, wind turbines or in other various electric and electronic devices. The European Union raw materials initiative (RMI; Communication on raw materials, COM 2011/25) labelled REE as one of the most critical elements for EU. Nevertheless, today the recycling of REE is counted only to around 1-10%, globally. The absence of REE wastes recycling at individual countries had caused accumulation of wastes, as a result of missing proper technologies. The aim of this work is to introduce the possible methods for recycling and recovery of Nd from spent Nd-Fe-B magnets from waste electric and electronic equipment (WEEE). Moreover, the description and identification of composition of waste Nd-Fe-B magnets from various sources after demagnetisation at Curie temperature are presented. For characterisation of the individual samples, the chemical elemental analysis, X-ray diffraction phase analysis and scanning electron microscopy have been applied. The results indicated different phase and elemental composition of individual spent Nd-Fe-B magnets. Keywords: spent Nd-Fe-B magnets, characterisation, rare earth elements, Nd
A produção de aço a partir de sucata gera uma quantia considerável de resíduo, na forma de pó, co... more A produção de aço a partir de sucata gera uma quantia considerável de resíduo, na forma de pó, contendo diversos metais pesados, sendo assim considerado ambientalmente perigoso. Surge então a necessidade de desenvolver soluções, dentre elas tratamentos que reciclem parte do teor de metais pesados no pó de aciaria. Neste trabalho se estuda o processamento hidrometalúrgico de um pó de aciaria da produção de aços-carbono, em solução de ácido sulfúrico, a fim de extrair o zinco mantendo o ferro insolúvel. São utilizadas condições normais de pressão, e é investigada a dependência da temperatura e concentração de ácido. Obtém-se uma lixiviação de zinco relativamente alta mantendo a maior parte do ferro no resíduo sólido, com concentrações de ácido baixas e temperatura ambiente. Continuando o trabalho investigar-se-á a lixiviação do pó resultanteda produção de aços especiais, que contém menores concentrações de zinco e outros contaminantes como cromo. (PIBIC).
Enhanced Dry Separation of Aluminium from Composites by Ozone
The Possibilities for Obtaining of Rare Earths from Spent Fluorescent Lamps Phosphor
2015-Sustainable Industrial Processing Summit & Exhibition, Dec 15, 2015
Hydrometallurgy, Mar 1, 2018
The aim of this work was to study and describe Y, Eu and accompanying elements (Zn, Cd) leaching ... more The aim of this work was to study and describe Y, Eu and accompanying elements (Zn, Cd) leaching behaviour from the phosphors of waste cathode ray tube screens in low concentrated sulphuric acid solutions under both non-oxidizing and oxidizing conditions (H 2 O 2). Thermodynamic study showed that non-oxidizing acid leaching leads to elemental sulphur and hydrogen generation followed by formation of H 2 S(g). In the presence of oxidant in the leaching system SO 2 (g) or H 2 SO 4 formation is possible. PbSO 4 was formed during leaching independently from the presence of the oxidant. Y, Eu and Zn dissolution without using H 2 O 2 in 0.4 M H 2 SO 4 at 80 °C attained 6, 9 and 8 % respectively. The appropriate content of H 2 O 2 in leaching solution was determined as 3.9 v/v %. The highest leaching efficiency of Y and Eu (around 90-95 % after 20 minutes) was achieved by using the leaching solution (400 ml 0.4 M H 2 SO 4 , 60 ml 30 v/v % H 2 O 2) at 80 °C and L/S ratio 23. Under these conditions Zn extraction was relatively low (20 %) in comparison with Cd extraction (80 %). The study also reveal that high leaching efficiency of both Y and Eu (around 90 %) was achieved with even more diluted leaching solution (400 ml 0.05 M H 2 SO 4 , 60 ml of 30 v/v % H 2 O 2) at 60 °C, L/S ratio 23 after 20 minutes of leaching. Zn and Cd extractions reached 20 % and 55 % respectively. Activation energy values calculated for Y and Eu leaching in the solution (400 ml 0.4 M H 2 SO 4 with 60 ml of 30 v/v % H 2 O 2) refer to diffusion mechanism in the range 40-80 °C (Ea = 14.85 kJ/mol and 16.47 kJ/mol respectively). In contrast , Ea values for Y and Eu leaching in (400 ml 1 M H 2 SO 4 , 60 ml of 30 v/v % H 2 O 2) suggest a mechanism change at the temperature around 40 °C. The leaching of Y as well as Eu up to 40 °C is controlled by diffusion and at higher temperatures by chemical reaction.
Keywords: chal co py rite, ther mal treat ment, sul fur, sulfidation, X-ray dif frac tion phase a... more Keywords: chal co py rite, ther mal treat ment, sul fur, sulfidation, X-ray dif frac tion phase ana lyse, cop per, leach ing, sul fu ric acid Ab stract The cop per leach ing from chal co py rite is rather com pli-cated pro cess due to its re frac tory na ture. There fore a big ef fort is paid to find more ef fec tive method for this pro cess. One pos si ble method is the ther mal treat ment of raw chal-co py rite ma te rial with sul fur. The cop per from prod ucts of ther mal sulfidation of chal co py rite con cen trate should be better leachable, while iron prod uct could be less leachable, what is an ad van tage. Ther mal sulfidation of the chal co py rite con cen trate was re al ized by heat ing of sam ples at tem per a tures of 300, 350 and 400 °C dur ing 1 hour at nor mal pres sure 0.1 MPa. The used amount of sul phur was 0, 0.5, 1, 2, 3 grams per 3 grams of con cen trate. More over, one sulfidation ex per i-ment was re al ized in evac u ated quartz tube. Achieved prod ucts wer...
The Possibilities for Obtaining of Rare Earths from Spent Fluorescent Lamps Phosphor
Hydrometallurgical Treatment of Used Nd-Fe-B Magnets
Ab stract The ki netic study of hydration pro cess of sintered CaO pellets by X-Ray dif frac tion... more Ab stract The ki netic study of hydration pro cess of sintered CaO pellets by X-Ray dif frac tion method was stud ied in this work. Sintered CaO pel lets were in tro duced in opened sys tem, which was continuosly sup plied with wa ter steam. The actual tem per a ture as well as rel a tive hu mid ity were changed by tem per a ture change in wa ter ther mo stat. Hydration exper i ments were real ised at the se lected rel a tive humidities of 98, 57, 37 and 21 %. At cho sen in ter vals the pel lets were sub mit ted to X-Ray dif frac tion phase anal y sis. The observed char ac ter is tics was the rel a tive in ten si ties I (101) Ca(OH)2 / I (200) CaO ra tio. This re veals the for ma tion of the new phase Ca(OH) 2 and the miss ing phase CaO at the pel let sur face. It fol lows from ex per i men tal re sults that tem per ature plays more im por tant role in the hydration pro cess as rel a tive hu mid ity. The ap par ent ac ti va tion en ergy E A of 3.6 kJmol-1 was de ter mined. Based on achieved ex per i men tal re sults the nu cle ation (diffusional) con cept of hydration pro cess was spec i fied.
Submerged-arc welding slags: Characterization and leaching strategies for the removal of aluminum and titanium
Journal of Hazardous Materials, 2013
In the present study, submerged-arc welding slags were characterized by applying a variety of met... more In the present study, submerged-arc welding slags were characterized by applying a variety of methods, including X-ray fluorescence, X-ray diffraction, particle size, Raman spectroscopy, and scanning electron microscope with energy dispersive X-ray analysis. The content of Al proved to be quite similar within neutral and acid slags (10-14%), while that of Ti proved to be much higher in acid slags (approximately 10%) than in neutral slags (<1%). The presence of spinel structures associated with Al species could also be identified in the analyzed samples. This characterization study was accompanied by leaching tests performed under changing operating conditions in an attempt to evaluate to what extent the Al and Ti bearing components could be removed from the slags. The leaching work involved three distinct strategies: (i) NaOH leaching followed by H(2)SO(4) leaching, (ii) acid leaching (HCl and H(2)SO(4)) using oxidizing/reducing agents, and (iii) slag calcination followed by H(2)SO(4) leaching. In the best result, 80% of Al was extracted in one single leaching stage after calcination of the acid slag with NaCl+C at 900 °C. By contrast, the removal of Ti proved to be unsatisfactory.
Materials
The paper describes cementation as a suitable method applied in the refining of EAFD leachates in... more The paper describes cementation as a suitable method applied in the refining of EAFD leachates in order to obtain required purity of ZnO for specific industrial application. For study of cementation conditions, the leachate from alkaline leaching with (NH4)2CO3 was used. The leachates contained a high amount of zinc (8000–12,000 µg/mL) and a low content of impurities such as iron, lead, copper, chromium and manganese in the range of 1–21 µg/mL. Cementation conditions were predicted by thermodynamic study, theoretically confirming the viability of the proposed experiments at the considered pH = 8–9. Cementation experiments were carried out using powdered zinc and aluminium (5 g/L) as cementation agents in the first phase separately. To increase the cementation efficiency, their combination was used (2.5:2.5 g/L or 5:5 g/L) at temperatures of 20, 40, 60 and 80 °C for 30 min. The optimum cementation conditions were established as: Zn:Al = 5:5 g/L, 60 °C. Under the given conditions, 100...
Životné prostredie, 2018
Metallurgy, including the iron and steelmaking segments has extremely important roles in the worl... more Metallurgy, including the iron and steelmaking segments has extremely important roles in the world economy, and this creates a higher business profile for the Slovak Republic. The integral part of all business and human activities should be the ultimate protection of the environment, and this environmental protection should be independent of all society's production and social activities. This paper identifies the current and intended environmental activities and the goals of the European Union, industry and research and development sectors, and it focuses especially on metallurgical and environmental interaction. Our aim is to bring the current status and trends of iron and steel metallurgy to the closer attention of the scientific community, and therefore we examine these trends in relationship to iron and steel metallurgy and the environmental protective aspects in technology and innovation.
This work focuses on the hydrometallurgical processing of EAF steelmaking dust in laboratory cond... more This work focuses on the hydrometallurgical processing of EAF steelmaking dust in laboratory conditions. The behavior of calcium under the influence of sulphuric acid as the leaching agent is discussed. Due to calcium presence the acid is continuously consumed, gradually leaching the calcium phase from EAF dust as well as other zincand iron-containing phases. A thorough composition analysis of the input sample of EAF dust was performed. A kinetic study of calcium showed that its leaching is a very fast process, but most of the calcium reacting with sulphuric acid is precipitated from the solution in the form of CaSO4∙2H2O. This causes greater sulphuric acid consumption, and therefore it is necessary to study the calcium behavior during processing of EAF dust. This work is narrowed with calcium behavior during leaching of EAF dust in sulphuric acid and effect of calcium to extraction other metals into solution.
In this study the hydrometallurgical processing of BOF sludge in the sulphuric acid solutions und... more In this study the hydrometallurgical processing of BOF sludge in the sulphuric acid solutions under atmospheric pressure and temperatures up to 100 °C is investigated on a laboratory scale. The influence of sulphuric acid concentration, temperature, time and liquid to solid ratio (L:S) on the leaching process was studied. The main aim of this study was to determine optimal conditions when the maximum amount of zinc passes into the solution. Key words: basic oxygen furnace dust and sludge, hydrometallurgy, leaching, zinc, sulphuric acid
Metals
Copper anode furnace dust is waste by-product of secondary copper production containing zinc, lea... more Copper anode furnace dust is waste by-product of secondary copper production containing zinc, lead, copper, tin, iron and many other elements. Hydrometallurgical Copper Anode Furnace dust recycling method was studied theoretically by thermodynamic calculations and the proposed method was verified experimentally on a laboratory scale. The optimum condition for leaching of zinc from dust was identified to be an ambient leaching temperature, a liquid/solid ratio of 10 and H2SO4 concentration of 1 mol/L. A maximum of 98.85% of zinc was leached under the optimum experimental conditions. In the leaching step, 99.7% of lead in the form of insoluble PbSO4 was separated from the other leached metals. Solution refining was done by combination of pH adjustment and zinc powder cementation. Tin was precipitated from solution by pH adjustment to 3. Iron was precipitated out of solution after pH adjustment to 4 with efficiency 98.54%. Copper was selectively cemented out of solution (99.96%) by zin...
Utilization of plants for stabilization and cleaning up of metal contaminated soil and water Phyt... more Utilization of plants for stabilization and cleaning up of metal contaminated soil and water Phytoremediation has been defined as the use of green plants and their associated rhizospheric microorganisms to remove, degrade, or contain contaminants located in soisl, sediments, groundwater, surface water, and even the atmosphere. Categories of phytoremediation include phytoextraction or phytoaccumulation, phytotransformation, phytostimulation or plant-assisted bioremediation, phytovolatilization, rhizofiltration, pump and tree, phytostabilization, and hydraulic control. Phytoremediation of heavy metal contaminated soils basically includes phytostabilization, phytoextraction, rhizofiltration and phytovolatilization. Selection of plants for phytoremediation of metals depends on a particular application.
The influence of limestone from Gombasek site (Slovakia) milling on the CaO refractory material p... more The influence of limestone from Gombasek site (Slovakia) milling on the CaO refractory material preparation by using of XRD was studied in this work. The vibrational mill VM-4 (Czech Republic) was used for this purpose. Limestone charges of 50 g, 75 g, 100 g and milling time 1, 2, 3, 4, 5, 10, 15, 30, 60, 90 min were choosen. The granularity of milled limestone is diminished as well as the amount of structure deffects is increased by milling. That is why the diffraction peak intensities are lowered and half-width of diffraction are broadened. The peak intensity to half-width diffraction ratio was studied characteristics. It was shown, that the charge amount increasing is followed by lower disintegration of milled limestone and milling time up to 10 minutes is sufficient for dense CaO clinker preparation with relative bulk density 93 % of theoretical CaO density when burning temperature of 1560°C is used.
Metals
Due to the increasing demand for battery raw materials, such as cobalt, nickel, manganese, and li... more Due to the increasing demand for battery raw materials, such as cobalt, nickel, manganese, and lithium, the extraction of these metals, not only from primary, but also from secondary sources, is becoming increasingly important. Spent lithium-ion batteries (LIBs) represent a potential source of raw materials. One possible approach for an optimized recovery of valuable metals from spent LIBs is a combined pyro- and hydrometallurgical process. The generation of mixed cobalt, nickel, and copper alloy and lithium slag as intermediate products in an electric arc furnace is investigated in part 1. Hydrometallurgical recovery of lithium from the Li slag is investigated in part 2 of this article. Kinetic study has shown that the leaching of slag in H2SO4 takes place according to the 3-dimensional diffusion model and the activation energy is 22–24 kJ/mol. Leaching of the silicon from slag is causing formation of gels, which complicates filtration and further recovery of lithium from solutions...
Metallurgy and Foundry Engineering, 2016
This paper shows a review of literature data on the possibilities of indium recovery from ITO lay... more This paper shows a review of literature data on the possibilities of indium recovery from ITO layers of waste LCD and LED displays. A short characterization of indium, its compounds, resources, production, and applications is presented. The structure and operation of LCD displays are shown. A detailed overview of the ITO leaching process is presented. Methods of indium(III) ion separation from the leachate solutions (SX, HoLLE, IX) as well as recovery of the final products (precipitation, cementation, electrowinning) are also shown.
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Papers by Andrea Miškufová