Armando Corrêa de Araujo

The Effect of Reagents on Ultrafine Iron Ore Vacuum Filtration

Abstract Continuous vacuum filters normally carry out the final removal of water from iron ore products. The objective of this investigation is to check the possibility of enhancing the industrial performance of a horizontal belt filter by adding one flocculant and two surfactants to the filtration feed slurry. The mineral sample came from the Iron Quadrangle (State of Minas Gerais, Brazil). X-ray diffraction showed a predominance of hematite and small amounts of quartz and goethite. The filtration tests were performed at laboratory scale using a modified Buchner funnel apparatus, which was connected to a scale/computer system. The results indicated: a) the best filtration condition was achieved near the zero charge condition; b) cake moisture, cake porosity, cake formation time and the specific cake resistance were pronouncedly influenced by the flocculant addition; and c) surfactants tested were not able to significantly reduce the cake moisture.

Adsorção de coletores aniônicos em silicatos

The understanding of the adsorption mechanisms of collectors is of primary importance for the optimization and, eventually, the feasibility of the flotation process. Although anionic collectors are included in the main reagents used in various flotation systems, only a few studies of adsorption of these reagents in silicate flotation systems have been carried out when compared with the large number of studies developed with sparingly soluble minerals and oxides. The present work makes a concise revision of the adsorption mechanisms for the main anionic silicate collectors, carboxylic and sulfonic acids and sulfates. Carboxylic acids are emphasized due to their ability to form insoluble salts with metallic cations.

Estudo de rotas de concentração para amostras de barita

In the present work flotation concentration of 4 types of barite was investigated, aiming for at least 60% of BaO and less than 6% of SiO2 in the concentrate. Flotation testing of different collectors, alone and in combinations, was performed. Because of the the presence of sulfides in the samples, a prior sulfide flotation step was performed for their removal in order to warrant the highest BaO final grades. The best results of the four barite samples showed that the objective was achieved with the BaO grade higher than 64%, the SiO2 grade lower than 3,3% at a BaO recovery of at least 79%. The concentration route for each barite was different; in the blue barite the best collectors were cetyl-sterayl sulfate and soy bean oil, in the white barite was the mix of sulfossuccinate and sulfonic acid, in the T3 barite was the soy bean oil and in the so called tailing barite was the sulfossucinate.

Adsorção de misturas de coletores em silicatos

Despite the fact that over 70 years ago the industrial flotation practice already considered the mixture of oils as chain extenders, detailed studies on interactions between flotation reagents appeared only in the sixties. The initial work investigations were dedicated to the study of the mixtures of anionic or cationic reagents with alcohols. Publications during the last 20 years have been related to the adsorption of collector mixtures: at the alumina-water interface, the feldspar flotation, and the reverse flotation of hematite. The present work reviews the main aspects of collector mixture in the flotation and shows the microflotation results of some silicates with the combination of anionic and cationic collectors.

Consistencia, Fluidez y Viscosidad de Pastas Minerales de Relaves de Hierro

Se presentan las caracteristicas de viscosidad aparente, altura de abatimiento y angulo de reposo de pastas minerales preparadas a partir de una mezcla lama/relave de hierro, ademas de algunas caracteristicas del componente solido de la pasta. La metodologia aplicada para caracterizar las pastas minerales considera el uso de ensayos de abatimiento (slump), de canaleta (flume) y viscosimetria. Los resultados muestran que la parte solida correspondiente a la mezcla de relaves esta compuesta predominantemente de hematita con menores cantidades de cuarzo, goetita, gibsita y caolinita, con una distribucion granulometrica muy fina (inferior a 25 mm); los ensayos de abatimento y de canaleta mostraron ser herramientas muy simples para caracterizar consistencia y fluidez de pastas minerales; pueden alcanzarse angulos de reposo proximos a 5° sin mayores dificultades; y las pastas adensadas con 70 y 72.5% en solidos mostraron comportamientos tixotropicos al considerar el ciclo reologico 11001 rpm.