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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

2023

Vol. 59, iss. 6

art. no. 172458

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).

Thermodynamic Analysis of the Graphite Flake Formation of Low Manganese and Sulfur Gray Cast Iron

Reyes-Castellanos G., Cruz-Ramírez A., Colin-García E., Gutiérrez-Pérez V. H.

Archives of Metallurgy and Materials

2021

Vol. 66, iss. 1

249--258

Low manganese and sulfur gray irons were produced by adding inoculant base Fe-Si with small amounts of Al and Ca in the ladle. The effect of the cast thickness, inoculant amount and shakeout time of the green sand molds were studied on the graphite flake formation by microscopically techniques. A thermodynamic analysis was carried out for the cast iron produced with the FactSage 7.2 software. Stability phase diagrams were obtained for both gray cast irons to different manganese (0.1 to 0.9 wt.%) and sulfur (0.01 to 0.12 wt.%) amounts to 1150°C. It was shown that lower amounts of manganese and sulfur allow forming the 3Al2O3·2SiO2, Al2O3, and ZrO2 solid compounds. The thermodynamic results match with those obtained by SEM-EDS. It is possible to form MnS particles in the liquid phase when the solubility product (%Mn) × (%S) equals 0.042 and 0.039 for heats A and B, respectively.