Abstract
Mineral liberation is an important variable to be considered in the iron ore geometallurgical studies, especially since it provides information leading to the understanding of the ore’s behaviour in the beneficiation process, mainly when harder ores are concerned. Nowadays, the professionals and researchers in the mineral industry have been using complementary techniques for mineralogical characterization. In this way, Mineral Liberation Analyser (MLA) and optical microscopy are amongst the most efficient and important tools in these studies. Together, these techniques can provide information leading to the development of geometallurgical models, including the degree of quartz liberation, mineral modal composition, mineralogical association and particle and mineral size distribution, as well as the spectrum of mineral liberation either by free surface or particle composition. The purpose of this study is to compare the degree of quartz liberation in four different iron ore types observed in optical microscopy and MLA. It also assesses the influence of mineral liberation in the quality of the resulting concentrate, according to the SiO2 content. All the results of the various quartz liberation degrees, determined by both MLA and optical microscopy were very close, as well as the correlation between the mineral liberation and the ore’s response in the flotation process. The investigation provided evidence that the mineral liberation study is an important tool in the prediction of the ore’s behaviour in the beneficiation process.
Highlights
The gradual depletion in high-grade iron ores combined with many decades of extraction compelled the leading Brazilian mining companies to mine more complex ores in order to increase reserves and production rates in the last few years
Harder ores usually require higher grinding energy, resulting in difficulties in achieving the mineral liberation needed for the flotation process, which affects the quality of the concentrate and the production rate
This article aims to compare the values of quartz liberation degree of four different iron ore types observed through optical microscopy and Mineral Liberation Analyser (MLA), and to assess the influence of mineral liberation on the quality of the concentrate obtained, taking into consideration the SiO2 content
Summary
The gradual depletion in high-grade iron ores combined with many decades of extraction compelled the leading Brazilian mining companies to mine more complex ores in order to increase reserves and production rates in the last few years. The ones assigning low Fe content, increased impurities amount, and high hardness. The explotation of these ores results in greater difficulty in processing, mainly in the grinding stage and concentration process (Costa et al, 1998; Das et al, 2007; Rocha, 2008; Rao et al, 2009; Rodrigues et al, 2014; Rodrigues, 2016). Harder ores usually require higher grinding energy, resulting in difficulties in achieving the mineral liberation needed for the flotation process, which affects the quality of the concentrate and the production rate. In an attempt to ensure high production rates and keep the desired quality of the products, professionals and researchers in the mineral industry have been working towards the development of tools capable of predicting the ore’s behavior during processing.
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