Liberation Of Valuable Minerals Research Articles

Mineral and Technological Features of Magnetite–Hematite Ores and Their Influence on the Choice of Processing Technology

Analysis of the current technical solutions for the processing of iron ores showed that the high-grade ores are directly exposed to metallurgical processing; by comparison, low-grade ores, depending on the mineralogical and material composition, are directed to beneficiation including gravitational, magnetic, and flotation processes or their combination. Obtaining high-quality concentrates with high iron content and low content of impurities from low-grade iron ores requires the maximum possible liberation of valuable minerals and a high accuracy of separating features (difference in density, magnetic susceptibility, wettability, etc.). Mineralogical studies have established that the main iron-bearing mineral is hematite, which contains 69.02 to 70.35% of iron distributed in the ore. Magnetite and hydrogoethite account for 16.71–17.74 and 8.04–10.50% of the component, respectively; the proportion of iron distributed in gangue minerals and finely dispersed iron hydroxides is very insignificant. Iron is mainly present in the trivalent form—Fe2O3 content ranges from 50.69 to 51.88%; bivalent iron is present in small quantities—the FeO content in the samples ranges from 3.53 to 4.16%. The content of magnetic iron is 11.40–12.67%. Based on the obtained results by the investigation of the features of magnetite–hematite ores from the Mikhailovskoye deposit, a technological scheme of magneto-flotation beneficiation was proposed, which allows producing iron concentrates with 69% of iron content and less than 2.7% silicon dioxide for the production of pellets with subsequent metallization.

Quantitative Ore Texture Analysis with Convolutional Neural Networks

Abstract Liberation of valuable minerals from their gangue matrices depends on the physical properties of the ore, as well as the features of the process used to extract these minerals from the rock particulates. Despite the fact that the texture of the ore is an important predictor of liberation in an ore system, it is only recently that quantitative descriptors of the texture have been included in liberation models. These descriptors can be obtained in a variety of ways, but a general methodology has not yet been established. In this study, recent advances in quantitative ore texture analysis are reviewed and the feasibility of using state-of-the-art computer vision technology based on convolutional neural networks for ore texture analysis is considered.

Quantitative mineralogical characterization of chrome ore beneficiation plant tailing and its beneficiated products

Mineralogical characterization and liberation of valuable minerals are primary concerns in mineral processing industries. The present investigation focuses on quantitative mineralogy, elemental deportment, and locking-liberation characteristics of the beneficiation of tailings from a chrome ore beneficiation plant in the Sukinda region, Odisha; methods used for the study of the beneficiated tailings are QEMSCAN®, X-ray diffraction (XRD), and mineral chemistry by a scanning electron microscope equipped with an energy-dispersive spectrometer (SEM-EDS). The tailing sample was fine grained (69.48wt% below 45 μm size), containing 20.25wt% Cr2O3 and 39.19wt% Fe2O3, with a Cr:Fe mass ratio of 0.51. Mineralogical investigations using QEMSCAN studies revealed that chromite, goethite, and gibbsite are the dominant mineral phases with minor amounts of hematite, kaolinite, and quartz. The sample contained 34.22wt% chromite, and chromite liberation is more than 80% for grains smaller than 250 μm in size. Based on these results, it was predicted that liberated chromite and high-grade middling chromite particles could be separated from the gangue by various concentration techniques. The tailing sample was beneficiated by hydrocyclone, tabling, wet high-intensity magnetic separation (WHIMS), and flotation in order to recover the chromite. A chromite concentrate with 45.29wt% Cr2O3 and a Cr:Fe mass ratio of 1.85 can be produced from these low-grade chromite ore beneficiation plant rejects.

Research of iron ore grinding in a vertical-roller-mill

The total energy consumption for ore comminution will further increase within the next decades. One contribution to minimise the increase is to use more efficient comminution equipment. Vertical-roller-mills (VRM) are an energy-efficient alternative to conventional grinding technology. One reason is the dry in-bed grinding principle. Results of extensive test works with two types of magnetite iron ores in a Loesche VRM are presented here. Within these test works, mill parameters like grinding pressure, separator speed and dam ring height were varied, following a factorial design of the experiments. The effects of the grinding parameters on the liberation of valuable minerals are characterised using mineral liberation analysis (MLA). It is shown how the different mill parameters influence important performance values like energy consumption, production rate and mineral liberation. Via multiple regression analysis, an optimal parameter range can be modelled for both ore types. The parameter predictions have been successfully verified in practical test works.

Understanding microwave assisted breakage

A finite difference quasi-static thermo-mechanical 2-D model of a theoretical 2-phase mineral is constructed. The aim is to simulate the thermal stresses generated and subsequent thermal damage when a rock particle is exposed to high electric field strength microwave energy. The influences of power density and grain size are assessed for a theoretical 2 mm by 2 mm sample of calcite host rock deemed transparent to microwave energy, containing a strongly absorbent circular pyrite phase of varying diameter. The simulations have predicted the extent of microwave heating, thermal conduction and expansion, strain softening and thermally induced fracturing. The stress regime is analysed and it is concluded that fractures are likely to occur around the grain boundary between absorbent and transparent species. This suggests that liberation of valuable minerals can be improved and that a reduction in comminution energy is possible after microwave treatment. The effect of size on peak temperatures is analysed, and it is shown why microwave treatment is less efficient at lower particle sizes for a fixed applied power density.

Ore liberation modelling by minerals topological evaluation

Liberation of valuable minerals from multiphase ores is one of the main goals of a size reduction process. Great importance is thus assumed by models able to give a detailed provisional description of the ore liberationo̧mminution process. In the definition of these models, the hypotheses usually adopted for ore textural and structural characterisation are dramatically simplified due to the great difficulty of translating and incorporating such characteristics in numerical form. This paper describes the possibilities offered by a full colour multispectral image analysis system for evaluating the liberation characteristics of an ore. The procedures and the related algorithms have been developed in order to permit a full recognition and morphological modelling of the different mineralogical species inside the images acquired by optical microscopy. A topological map containing a reduced body of data is related with the liberation characteristics of minerals. The system incorporates all the procedures able both to process the previously derived information and to test different comminution strategies based on the topological assessment of the species and the selected theoretical comminution net.

Experimental verification of the PARGEN simulator for liberation analysis

Liberation of valuable minerals during size reduction is an important aspect of mineral processing technology. In this regard the PARGEN (PARticle GENeration) program was developed in the early 1980's to simulate the characteristics of multiphase particles. This program is useful for the analysis and transformation of polished section data into an estimate of volumetric grade distributions and for the prediction of mineral liberation during size reduction. The appropriateness of simulated PARGEN particles is evaluated by comparing the simulated linear and areal grade distributions with experimentally determined distributions from carefully prepared mono-size, mono-grade particles. In this regard, two samples of mono-size, mono-grade binary particles were used, an iron-oxide/silicate sample and a sphalerite/dolomite sample. A comparison of the results indicates that the PARGEN simulator can be used successfully to predict the characteristics of real multiphase particles.