Thermodynamics and Mechanism of Metalothermic Reduction of Molten Salts

The objective of this paper is to present the differences which appear in terms of thermodynamics and structure in the elaboration process of two composite materials produced through an aluminothermic reduction of molten salts. There were conducted two sets of experiments of reduction of liquid Potassium Fluoroborate (KBF 4 ) and the mix of salts (KBF 4 The in-situ composites occured in the mid '80s, offers a termodynamic stability to fine and dispersed particles into the metal matrix due to the growth and germination of the reinforcement particles which takes place into the matrix alloy, assuring a strong link at the particle -matrix interface A1-B System It is agreed that an eutectic exists at low boron contents, and that boron has a low solubility (< 100 ppm) in the solid. However, there is disagreement on the boron solubility in the liquid. The older data, when extrapolated to 660 °C give an eutectic composition of 0.09 wt The boron composition of the hypoeutectic liquid is given by the relation Equation [1] Ti-B system There is a disagreement about the congruent melting temperature of TiB 2 . These data are listed in table 1. The highest reported congruent temperature 3498 K is chosen in the assessed phase diagram as reported in Experimental part There were produced two aluminium metal matrix composites by using pure aluminium and also aluminium alloys (6xxx and 5xxx series) as matrix. In order to obtain the composite materials reinforced with TiB 2 and AlB 2 particles there were used the following salts: Potassium Hexafluorotitanate (K 2 TiF 6 with the melting point of 780°C and molecular mass of 240.09 g/ mol) and Potassium Fluoroborate (KBF 4 with the melting point of 530°C and molecular mass of 125.91g/mol). Also cryolite (Na 3 AlF 6 with the melting temperature at 1027 °C and molecular mass 209.94 g/mol) was used for the metal bath protection and disolution of the formed oxides The two types of composites have been produced in an electric furnace in a graphite crucible, with mechanical stirring at a speed of 200 rot./min

A Bibliometric Analysis of Organic Farming and Voluntary Certifications

Organic farming, characterised by environmentally friendly and sustainable agricultural practices, has gained significant attention throughout the years due to its potential to address critical issues such as food security, environmental sustainability, and public health. Voluntary certification systems play a pivotal role in ensuring the integrity and quality of organic products in the market. Understanding the research landscape surrounding organic farming and voluntary certifications is of paramount importance for scholars, policy makers, farmers, and consumers. In this context, the present study utilizes a bibliometric approach to achieve a deeper understanding of the trends, key contributors, and key terms in these domains via a bibliometric analysis in order to contribute to the broader goals of promoting sustainable agriculture and informed consumer choices. The evolution of the field is traced, shedding light on seminal papers, influential authors, and prolific journals. The research type is quantitative, using Web of Science, VOSviewer, and bibliometric study as instruments. The results show that, for both terms “organic farming” and “voluntary certifications”, papers usually involve three or more authors and use other sources as the unit of analysis, leaving room for improvement and the filling of a gap in the specialty literature. This insight can guide future researchers and policymakers in focusing on critical areas within organic farming and certification systems, further advancing the field and addressing pressing issues related to sustainability, quality, and consumer awareness

Physical Education, Quality of Breathable Air and Their Effects on the Formation of High School Students as Sustainability in Maintaining the Lifestyle. Is the Physical Education Lesson Enough to Create Such Valences?

This study was conducted to emphasize the correlation between the number of physical education lessons with effects on the formation of high school students and the importance of practicing physical activities during the extra-class time in sustainable spaces with quality breathable air. The values were recorded in this cross-sectional study; on a number of 208 high school students; grades 9–12; tested for the level of manifesting their effort capacity acquired during the physical education lessons. The statistical analysis of the processed data highlights the obtained values: Weak 59% and 31% satisfactory for boys; and 53.92% weak; 34% satisfactory for girls. In conclusion; the necessity to carry out extra-curricular physical activities in an unpolluted environment and to acquire useful physical skills in carrying out different activities in society, promotes and generates sustainability in maintaining the lifestyle

Mechanochemical activation of copper concentrate and the effect on oxidation of metal sulphides

This work presents the effect of mechanochemical activation in an attrition mill, in water medium and for different time internals, on the particle size distribution and microstructure of copper concentrate as well as, on the oxidation of the metal sulphides after treatment in an autoclave. Results show that the mean particle size decreased after 30 minutes of milling almost 10 times and the specific surface increased from 0.1 to 4.3 m2/g. Regarding the micro-structural changes, it was found that during the mechanochemical activation the average crystallite size of chalcopyrite decreased, following an exponential trend towards a limiting value of approximately 20 nm, assuming spherical or equiaxed crystallites. The enhanced structural disorder of chalcopyrite is also highlighted by the linear increase of lattice strain with the milling time. Finally, results from the leaching experiments, demonstrated that the mechanical treatment improved the oxidation of sulphides by lowering the reaction temperature and increasing the reaction rates. The above data suggest that the mechanochemical activation of copper concentrate is an efficient method to enhance the hydrometallurgical oxidation of copper concentrate and chalcopyrite in particular.status: publishe