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Bond´s work index estimation using non-standard ball mills

Arellano-Piña Ramón, Sanchez-Ramirez Elvia Angélica, Pérez-Garibay Roberto, Gutiérrez-Pérez V.H.

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 6

art. no. 172458

EN

Ore concentrators seek the stability of processes by feeding blends of rocks with average hardness and ore content. Therefore, large amounts of samples must be characterized in a short time. The Bond Work Index (𝑊𝑖) is a common technique for the estimation of hardness and energy requirement for comminution using ball mills. However, this technique is time-consuming (close to 5 hours) and liable to experimental errors. This work contributes to obtaining new models for rapid Bond Work Index estimation using non-standard dimensions mills. This was done by proposing grinding tests using four types of ores and four mills of different dimensions, including the standard Bond ball mill (BBM). For all tests it was kept constant: (a) critical speed (91%), and (b) mill charge by volume (10.5%), varying the amount of fresh feed according to its density. The results showed that using the non-standard mills (between 20 and 35 cm in diameter), the Bond´s model constants (𝛼=0.23; 𝛽= 0.82, and 𝛾= 44.5), are unable to predict the Work Index properly. Therefore, these constants must be recalculated using linear models based on mill diameter. With the models proposed for 𝛼, 𝛽, and 𝛾, the Bond Work Index (kWh/t) can be rapidly estimated (less than 2 hours) and show a high accuracy for mills of non-standard dimensions (R2= 0.96).

2

Selective leaching of copper from near infrared sensor-based preconcentrated copper ores

Ambo Amos Idzi, Iyakwari Shekwonyadu, Glass Hylke J

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 1

204--218

EN

Copper oxide ore was pre-concentrated using near infrared sensor-based method and classified as product, middling and waste. The product and middling fractions were leached with ammonium chloride reagent. The effect of temperature, ammonium chloride concentration, solid- liquid ratio, stirring speed and particle size experimental variables were investigated. Mineralogical and chemical analysis of the ore fractions indicated that copper content was in accordance with the preconcentration strategy, with the product having a higher concentration than the middling and waste. The rate of copper extraction was found to be higher in the product than in the middling sample which further supports the near infrared classification, QEMSCAN®, X-ray diffraction, SEM mineralogical and X-ray florescence and Inductively coupled plasma Mass spectrometry chemical data. It was revealed that the leaching rate increases with increasing ammonium chloride concentration, temperature and decreasing ore particle size, stirring speed and solid-liquid ratio. Analysis of the experimental data by shrinking core model indicated that the dissolution kinetics follow the heterogeneous reaction model for the chemical control mechanism where the activation energies of 45.9 kJ/mol and 47.5 kJ/mol for product and middling fractions respectively were obtained. Characterization of the residue obtained at optimum leaching condition with X-ray diffraction suggests that copper was selectively leached when compared to the profile of the raw ore. The trace levels of metals associated with abundant X-ray diffraction profiles of residue found in the leachate further confirm the selective leaching process.

3

Characterization and beneficiation of iranian low-grade manganese ore

Mehdilo A., Irannajad M., Hojjati-Rad M. R.

Physicochemical Problems of Mineral Processing

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2013

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Vol. 49, iss. 2

725--741

EN

The mineralogical studies indicated that the Charagah ore deposit contains approximately 17% pyrolusite, 78% calcite and 3–4% quartz. Pyrolusite as a main valuable mineral is found in the forms of coarse and fine pyrolusites. The coarse grains pyrolusite with simple texture is liberated at 180 micrometers. Another kind of pyrolusite with particle size finer than 10 m is disseminated inside gangue phases. This kind of pyrolusite has important effect in beneficiation processes and can affect the manganese grade of the concentrate and its recovery negatively. By jigging machine a pre-concentrate with 20% MnO and a final tailing with about 13% manganese loss are obtained. Using tabling technique or wet high intensity magnetic separation (WHIMS) and also their combination with jigging machine, production of a final pyrolusite concentrate with suitable grade but average recovery is possible. By jigging-tabling a concentrate with – 500+45 m size fraction, 44.3% MnO and 61.3% recovery is obtained while jigging-WHIMS produces a concentrate containing 52.6% MnO with a recovery up to 56.6% and d80 = 180 m.