Influence of cations Ca2+, Mg2+ and Zn2+ on the flotation and surface charge of smithsonite and dolomite with sodium oleate and sodium silicate.

using sodium oleate and sodium silicate. Microflotation test results demonstrated recoveries of 95% and 5% for smithsonite and dolomite, respectively, from 2.5 ? 10?5 M sodium oleate and 50 mg/L sodium silicate at pH 9.5. The smithsonite was depressed by the cations Ca2+ and Mg2+ and, the dolomite was depressed by Zn2+ cations, which was probably caused by the reaction of these cations with the oleate anions in the solution, decreasing the concentration of collector available for adsorption onto the minerals. The powerful depression of smithsonite caused by Ca2+ cations compared with that caused by Mg2+ cations can be considered to have occurred because of the higher concentration of Ca2+ in the solution. From the zeta potential measurements at pH 9.5, we concluded that the predominant species of oleate and of sodium silicate were adsorbed onto both minerals, and the silicate species prevented the adsorption of oleate anions onto dolomite. The decrease in the negative zeta potential of both minerals after cation conditioning can be related to the electrostatic attraction between the cations and the negative sites on their surfaces. The negative zeta potential of smithsonite increased at a concentration of 1 ? 10?6MCa2+ and Mg2+,whereas the potential decreases at a concentration of 1 ? 10?3 M, which can be related to a lower concentration of oleate anions being available for adsorption

Effect of EDTA on quartz and hematite flotation with starch/amine in an aqueous solution containing Mn2+ ions.

In this paper, a detailed study of the influence of Mn2+ ions on quartz and hematite flotation (at pH 10.5 with starch/amine as depressor/collector) in the absence and presence of ethylenediaminetetraacetic acid (EDTA) is presented. By using zeta potential measurement and a careful analysis of manganese species present in water for dosages in which manganese hydroxide precipitated, we confirmed that the depression of both minerals by Mn2+ ions is due to the following: (i) the adsorption of Mn hydroxy complexes (Mn2(OH)3+ and Mn(OH)+); (ii) Mn2+ and mainly (iii) the precipitation of Mn(OH)2 on mineral surfaces. These effects hindered the adsorption of amine species on the surfaces of the minerals (quartz and hematite). EDTA was used to complex Mn2+ to restore the recoveries of both minerals. This was confirmed by the species distribution diagrams of Mn and EDTA?Mn in water. Conditioning with starch followed by amine at pH 10.5 enabled a selective separation of these minerals

Influence of sodium fluorsilicate addition on manganese minerals and quartz floatability with sodium oleate.

Esse trabalho apresenta e discute resultados de ensaios de microflota??o e determina??o de potencial zeta dos minerais rodonita, rodocrosita e quartzo, na presen?a de fluorsilicato e oleato de s?dio em pH 9 e pH 11. Verificou-se que, para concentra??es de Na2SiF6 abaixo de 10mg/L, houve maior depress?o do quartzo em rela??o ? rodonita no valor de pH 9 e que a flotabilidade da rodocrosita foi pouco afetada para os valores de pH 9 e 11. Resultados de medidas de potencial zeta versus pH indicaram que o ponto isoel?trico da rodonita (pH=2,8) coincidiu com o reportado em literatura, enquanto que os valores determinados para quartzo (pH<2,0) e rodocrosita (pH=10,8) apresentaram pequena diverg?ncia. Para os tr?s minerais, a presen?a de oleato e/ou silicato de s?dio foi capaz de tornar mais negativa a magnitude do potencial zeta dos tr?s minerais em meio b?sico. Fundamentando-se nos resultados experimentais e, tamb?m, na especia??o dos reagentes estudados (oleato e fluorsilicato de s?dio), foi poss?vel fazer infer?ncias sobre mecanismos de adsor??o dos mesmos sobre os tr?s minerais de interesse.This work presents and discusses results from zeta potential measurements and flotation response of rhodonite, rhodochrosite and quartz, in the presence of sodium fluorsilicate and sodium oleate. At concentrations of Na2SiF6 smaller than 10mg/L, at pH 9, quartz is more intensively depressed than rhodonite, whereas the flotation response of rhodochrosite is slightly affected either at pH 9 or pH 11. Results from measurements of zeta potential versus pH indicate that IEP of rhodonite (pH=2.8) is similar to those reported in literature, whereas the value o IEP of quartz (pH<2.0) and rhodochrosite (pH=10,8) differ slightly from literature. Zeta potential of rodonite, quartz and rhodochrosite, in the presence of sodium fluorsilicate and/or sodium oleate, become more negative at basic medium. Based on the experimental results and collector (sodium oleate) plus depressant (sodium fluorsilicitate) speciation, some inference on the adsorption mechanisms of these reagents upon rhodonite, quartz and rhodochrosite is maintained

Cluster analysis applied to recognition of different types of friable siliceous itabirites from Brucutu Mine.

A an?lise de agrupamento ? uma t?cnica de estat?stica multivariada que permite separar as unidades amostrais em grupos homog?neos internamente e heterog?neos externamente. Neste estudo essa t?cnica foi aplicada, atrav?s do software R, com o objetivo de estratificar em subgrupos os min?rios classificados como itabiritos silicosos fri?veis da Mina de Brucutu, Quadril?tero Ferr?fero-MG. A matriz de dados era composta por 3.519 amostras e 10 vari?veis granulom?tricas e qu?micas. A an?lise hier?rquica de agrupamento mostrou que as amostras podem ser subdivididas em quatro grupos, e ent?o, as mesmas foram agrupadas pelo m?todo n?o hier?rquico K-means. Atrav?s da an?lise das caracter?sticas de cada grupo formado, os mesmos foram classificados e relacionados com a geologia da jazida. A Tipologia 1 (itabirito silicoso fri?vel rico e fino), ? localizada no topo do dep?sito e estratigraficamente acima das rochas intrusivas m?ficas. A Tipologia 2 (itabirito silicoso fri?vel pobre e grosseiro) ? marcado pela dire??o NW-SE, evento Brasiliano. A Tipologia 3 (itabirito silicoso fri?vel pobre e fino) ? dispersa ao longo do dep?sito, dificultando sua correla??o com alguma fase geol?gica. A Tipologia 4 (itabirito semi-compacto pobre) concentra-se na regi?o SW do dep?sito.Cluster analysis is a multivariate statistical technique that allows to separate the sample units into internally homogeneous and externally heterogeneous groups. In this study the cluster analysis was applied through R software, with the aim of stratifying into subgroups the ores classified as friable siliceous itabirite from the Brucutu Mine, Quadril?tero Ferr?fero, state of Minas Gerais, Brazil. The data matrix consists of 3519 samples and 10 variables related to granulometric and chemical data. The hierarchical clustering analysis showed that the samples could be subdivided into four groups, and then they were grouped by the non-hierarchical K-means method. Through the analysis of the features of each group formed they were classified and related to the geology of the deposit. Typology 1 (friable, Fe-rich and fine siliceous itabirite) is located at the top of the deposit and stratigraphically above the intrusive mafic rocks. Typology 2 (? friable, low grade and coarse siliceous itabirite) is marked by NW-SE direction, Brasiliano event. Typology 3 (friable, low grade and fine siliceous itabirite) is dispersed throughout the deposit, making it difficult to correlate with some geological phase. Typology 4 (low grade semi-compact itabirite) is demarcated by concentration in the SW region of the reservoir

Physical, chemical and mineralogical characterization of a Brucutu iron ore sample.

A caracteriza??o de um min?rio permite a previsibilidade do seu comportamento frente aos processos de concentra??o. Apenas dados granuloqu?micos nem sempre s?o suficientes, sendo o reconhecimento das esp?cies minerais, suas propor??es, forma de gr?os e liberabilidade tamb?m fundamentais. Neste trabalho ? apresentada a caracteriza??o f?sica, qu?mica e mineral?gica de um min?rio de ferro da mina de Brucutu/Quadril?tero Ferr?fero-MG. Foram realizadas an?lises granulom?tricas por peneiramento e granul?metro a laser, qu?micas por fluoresc?ncia de raios X e mineral?gica por microscopia ?ptica e difra??o de raios X. Baseado nos resultados obtidos, o min?rio foi classificado como fri?vel, com teor global de Fe igual a 42,9% e SiO2 de 36,1%. Os minerais de ferro identificados foram hematita e goethita e, o principal mineral de ganga o quartzo. Na fra??o +1,0 mm o quartzo ocorre majoritariamente em part?culas mistas com os gr?os de hematita e goethita. Abaixo desta granulometria, o mesmo ocorre como part?culas livres. Acima de 0,15 mm a hematita ? predominantemente porosa, e abaixo de 0,15 mm granular. A goethita encontra-se associada ? hematita granular em todas as fra??es granulom?tricas.The characterization of an ore allows the predictability of its behavior in relation to the concentration methods. Only size and chemical analyses are not always sufficient, and the recognition of mineral species, their proportions, grain form, and liberability are also fundamental. In this work the physical, chemical and mineralogical characteristics of an iron ore from Brucutu mine in Quadril?tero Ferr?fero is presented. Particle size analyses were carried out by sieve and laser granulometer, chemistry by X-ray fluorescence and mineralogical by optical microscopy and X-ray diffraction. Based on the results obtained, the ore was classified as friable, with an overall Fe content of 42.9% and SiO2 of 36.1%. The iron minerals identified were hematite and goethite, and the main gangue mineral was quartz. In the fraction +1.0 mm the quartz occurs mainly in mixed particles with the hematite and goethite grains. Below this size, the same occurs as free particles. Above 0.15 mm the hematite is predominantly porous, and below 0.15 mm granular. Goethite is associated with granular hematite in all size distribution

The molecular structure of the borate mineral inderite Mg(H4B3O7)(OH)-5H2O - a vibrational spectroscopic study.

We have undertaken a study of the mineral inderite Mg(H4B3O7)(OH)_5H2O a hydrated hydroxy borate mineral of magnesium using scanning electron microscopy, thermogravimetry and vibrational spectroscopic techniques. The structure consists of ?B3O3?OH?5_2_ soroborate groups and Mg(OH)2(H2O)4 octahedra interconnected into discrete molecules by the sharing of two OH groups. Thermogravimetry shows a mass loss of 47.2% at 137.5 _C, proving the mineral is thermally unstable. Raman bands at 954, 1047 and 1116 cm_1 are assigned to the trigonal symmetric stretching mode. The two bands at 880 and 916 cm_1 are attributed to the symmetric stretching mode of the tetrahedral boron. Both the Raman and infrared spectra of inderite show complexity. Raman bands are observed at 3052, 3233, 3330, 3392 attributed to water stretching vibrations and 3459 cm_1 with sharper bands at 3459, 3530 and 3562 cm_1 assigned to OH stretching vibrations. Vibrational spectroscopy is used to assess the molecular structure of inderite

Precipitation of a layered double hydroxide comprising Mg2+ and Al3+ to remove sulphate ions from aqueous solutions.

This work presents an alternative route to remove sulphate ions from aqueous solutions, which is simple and fast, and its efficiency of sulphate removal is slightly influenced by temperature (26 ?C?70 ?C) and pH (4?12). The lowest residual sulphate concentration was about 60 mg L?1, which was observed in continuous experiments using wastewater (26 ?C, pH 6 and initial sulphate concentration of 630 mg L?1). All these outcomes together have not been observed in the current most used processes of sulphate precipitation, i.e. gypsum and ettringite precipitation. Sulphate removal experiments were carried out in the batch and continuous systems using synthetic solutions. In these conditions, about 75% of sulphate ions were removed for an initial ion concentration of 1800 mg L?1. A continuous test was also performed using a wastewater sample in addition to a synthetic solution. The system reached steady-state conditions after four residence times (40 min) in the experiment with synthetic solutions, whereas three residence times (30 min) were necessary for the tests with the wastewater (initial sulphate concentration of 630 mg L?1). In the latter case, the sulphate removal efficiency was approximately 90%. The characterisation of the experimentally precipitated solids was carried out by DRX, FTIR, SEMEDS, elemental analysis and thermal analysis. These techniques showed that, except in pH 4, the sulphate removal process occurred due to the precipitation of a layered double hydroxide, comprising Mg2+ and Al3+ as its metallic ions and nitrate (due to the salts used for precipitation) and sulphate anions occupying its interlayer space