The unique properties of ionic liquids (ILs) drive the growing number of novel applications in different industries. The main features of ILs are high thermal stability, recyclability, low flash point, and low vapor pressure. This study investigated pure chalcopyrite dissolution in the presence of the ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate, [BMIm]HSO4, and a bromide-like complexing agent. The proposed system was compared with acid leaching in sulfate media with the addition of chloride and bromide ions. The results demonstrated that the use of ionic liquid and bromide ions improved the chalcopyrite leaching performance. The best operational conditions were at a temperature of 90 °C, with an ionic liquid concentration of 20% and 100 g/L of bromide.

The effect of NaCl on the leaching of white metal from a Teniente Converter was investigated in NaCl-H2SO4 media under environmental conditions. The copper dissolution from white metal was studied using ferric ions in the range of 1–10 g/L, NaCl in the range of 30–210 g/L, and sulfuric acid in the range of 10–50 g/L. The test without NaCl produced a dissolution of 55%; through the addition of NaCl, the dissolution increased to nearly 90%. The effect of sulfuric acid on the copper dissolution was not significant in the studied range, as the excess sulfuric acid simply increased the iron precipitation. The positive effect of NaCl seems to be related to the action of chloro-complex oxidizing agents in relation to the Cu+2/Cu+ couple. A simplified two-stage mechanism is proposed for the leaching of white metal. In the first stage, the white metal produces covellite and Cu2+, and in the second stage it produces elemental sulfur and Cu2+. The first stage is very rapidly compared to the second stage.

Los aceros dúplex austeno-ferríticos están constituidos por ferrita y austenita en proporciones variables del 30 % al 70 %. Su composición química condiciona los procesos de envejecimiento que sufren durante los tratamientos térmicos, cuando se generan fases que endurecen y fragilizan el material. Este trabajo estudia la evolución de un nuevo inoxidable dúplex con bajo contenido en níquel y alto en nitrógeno y manganeso a 1123 K (temperatura crítica de precipitación) y tiempos de hasta 8 horas, comparándola con las de dos dúplex clásicos (2205 y 2507). El estudio, mediante medidas magnéticas, DRX y microscopías óptica y electrónica de barrido con microanálisis, reveló un comportamiento general similar en los tres aceros. El nuevo material presenta mayor estabilidad inicial, probablemente debido al elevado contenido en nitrógeno y manganeso, aunque produce la mayor cantidad de transformación final debido a la mayor cantidad inicial de ferrita. Para la identificación correcta de las fases se realizó un análisis comparativo determinando las composiciones químicas de las fases generadas. Todos los aceros ensayados están inicialmente constituidos por ferrita y austenita. Tras el envejecimiento, 8 horas a 1123 K, en el acero dúplex 2205 se observa una abundante formación de sigma, siguen presentes la austenita y parte de la ferrita original; en el dúplex 2507 la ferrita transforma totalmente y se identifican austenita, sigma, austenita secundaria y nitruros de cromo; respecto al nuevo dúplex DBNi, tras el tratamiento, se detecta austenita, ferrita, fases sigma y chi y nitruros de cromo. Palabras clave: Acero inoxidable. Acero dúplex. Fase sigma. Fase chi. Composición química. Phase transformation kinetics at 850° C of classic duplex stainless steels (2205 y 2507) and a new one with low nickel and higher manganese content (DBNi)Austenitic-ferritic stainless steels are formed by ferrite and austenite in a variable proportion between 30 % and 70 %. Their chemical composition conditions the ageing processes that can happen during heat treatments, where phases that hardens and brittles the material can be generated. Evolution of a new duplex stainless steel with lower nickel and higher nitrogen and manganese content maintained at 1123 K (critical precipitation temperature) up to 8 hours compared to classical ones (2205 and 2507) is presented. The study, done by magnetic measurements, XRD, optical and scanning electron microscopy and microanalysis, revealed a roughly similar behaviour for the three steels. The new one presents a higher initial stability, probably due to the high nitrogen and manganese contents; however, it also produces the higher final transformation due to the higher initial ferrite. A fine comparative analysis was done to correctly identify any phase; an accurate microanalysis in every generated phase was performed. All the steels tested are initially made on ferrite and austenite. After the ageing treatment, 8 hours at 1123 K, in the 2205 duplex steel a strong precipitation of sigma phase is observed, a...

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The flotation process characterization is typically based on the mineral properties and related to the feed particle size. Laboratory testing allows for the evaluation of the batch flotation kinetics, while plant surveys are carried out for the plant evaluation, and sometimes the rougher flotation stage is also characterized by kinetics, considering either the full sampling of the circuit or the short-cut method. Comparisons of plant and batch results are useful for identifying the scale-up factors. The kinetic evaluation of cleaner stages is less common in plant surveys, and usually, only the overall cleaner and scavenger results are reported. This condition limits a more comprehensive understanding of these stages, which have significant differences from the rougher operation. In this study, the effect of main operating variables in cleaner and scavenger stages, such as finer particle size, higher mass recoveries, higher liberation, particles entrainment, froth recoveries, mineral grades, froth depth, gas rate, and others, was analysed by using an industrial simulation tool that was built from a wide industrial database. For this purpose, data from plant kinetic surveys was used to characterize the mineral feed entering the cleaner–scavenger stage, which allowed for calibrating the simulation tool and predicting the overall circuit performance. The metallurgical results of the cleaner–scavenger bank were compared with those when the bank was operating at a rougher stage (previous operation). The results allowed for evaluating the differences in metallurgical results of the cleaner–scavenger and rougher banks, mainly related to the differences in particle size and liberation as well as in the mass flowrate of collected particles, which affects bubble loading and consequently froth stability, that in turns impacts on froth recovery. The operating conditions and mineral characteristics of each stage also impacted the water recovery and gangue entrainment along the banks. The comparison of predicted recoveries and grades in rougher, cleaner, and scavenger stages showed a good agreement with plant data. These results validated the simulation tool, which is useful and flexible enough to characterize different stages, predict performance and explore new operating conditions.