Low grade dumped limestone sample having high silica of 8.1%, 36.8% CaO, and 3% Al2O3 has been studied with the aim to reduce the silica level to below 3% for its utilization in iron making. Beneficiation study of the sample was initiated with desliming of the feed sample of −100 µm to remove the siliceous ultrafine particles and to improve the feed quality. Flotation study was carried out by column flotation technique varying the collector dosage, superficial air flow velocity and froth depth to assess their effect on silica reduction and CaO recovery. It was observed that increased collector dosage and superficial air velocity increases the recovery of CaO, and increase in the froth depth reduces the mass flow and silica content in the concentrate. The best result was found at 1.25 cm/sec superficial air velocity, 25 cm froth depth, 1.25 kgpt collector dosage and concentrate assayed 47.3% CaO, 2.8% silica with 72% CaO recovery.

Prospects of utilization of waste dumped low-grade limestone for iron making: A case study

Flotation devices, which exhibit different particle-bubble attachment efficiency owing to the different mineralization patterns, are critical to flotation performance of fine particles. In ...

Application of novel flotation systems to fine coal cleaning

Comparison of flotation performances of intruded and conventional coals in the absence of collectors

This paper compares FTIR (Fourier Transform Infrared Spectroscopy) and contact angle measurements to characterize surface properties of the oxidized coals with different ash contents. FTIR analysis...

Characterizing surface properties of oxidized coal using FTIR and contact angle measurements

Lignite is difficult to float because it owns high wettability. Furthermore, lignite can easily suffer the spontaneous combustion and magmatic intrusions which heat lignite from inside and have a heating impact on lignite properties. The heating process not only changes the physical and chemical properties of lignite but also changes its wettability. In this investigation, the changes in the wettability of lignite before and after the heating process were studied. The temperatures of the heating process were fixed at 500, 600, 700, 800, 900, and 1,000°С. X-ray photoelectron spectroscopy (XPS) and contact angle measurements were used in the characterization of the wettability of lignite surface. Throughout this paper, it was found that the wettability of lignite could be decreased after the heating process. The lowest wettability of lignite surface could be obtained after heating at the temperature of 900°С.

The effect of heating on the wettability of lignite

Surface property plays a very important role on coal hydrophobicity which determines flotation behavior of fine coals. However, coal spontaneous combustion makes coal suffer both oxidation and high temperature heating processes. Coals from the outside of coal piles primarily suffer oxidation process (or combustion process) while coals from the inside of coal piles primarily suffer high temperature heating process. It is necessary to investigate the changes in surface properties of coal before and after high temperature heating process. In this investigation, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), surface area (BET) and contact angle measurements were used to indicate the changes in surface properties of anthracite coal before and after high temperature heating process. Throughout this study, surface properties of coal can be changed significantly after high temperature heating process. Meanwhile, coal hydrophobicity can be also reduced after high temperature heating process.

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Comparison of surface properties of anthracite coals before and after high temperature heating process

A cyclonic-static micro-bubble flotation column (FCSMC) has been widely used in mineral separation. FCSMC includes countercurrent, cyclone and jet flow mineralization zones in a single column. In this study, the energy feature of the three different zones was compared. The turbulent flow was evaluated in terms of the turbulent kinetic energy (k) and the turbulent dissipation rate (e). An appropriate computing model was determined by comparing the flow field value measured by PIV with the results of the Fluent numerical simulation. Jet flow separation exhibited the maximum k and e values among the three columns, whereas counter-current separation displayed the minimum values. The high circulating volumetric flowrate means great energy input and turbulent intensity. The higher turbulent dissipation rate, the smaller the bubble is. The better performance of the FCSMC was mainly attributed to the multiple mineralization steps. The floatability of mineral particles gradually decreases with an increase in flotation time, the mineralization energy gradually increased to overcome the decrease in mineral floatability. By contrast, the countercurrent was beneficial for recovering the coarse particles, and the jet flow was beneficial for recovering the fine particles.

http://www.journalssystem.com/ppmp/pdf-73730-10907?filename=Energy feature of a.pdf

Wencheng Xia

Papers

Comparison of surface properties of anthracite coals before and after high temperature heating process

Energy feature of a multi-flow column flotation process