Shivakumar Angadi

Extraction of copper from copper slag: Mineralogical insights, physical beneficiation and bioleaching studies

Copper slag was subjected to in-depth mineralogical characterization by integrated instrumental techniques and evaluated for the efficacy of physical beneficiation and mixed meso-acidophilic bioleaching tests towards recovery of copper. Point-to-point mineral chemistry of the copper slag is discussed in detail to give better insight into the association of copper in slag. Characterization studies of the representative sample revealed the presence of fayalite and magnetite along with metallic copper disseminated within the iron and silicate phases. Physical beneficiation of the feed slag (~0.6% Cu) in a 2 L working volume flotation cell using sodium isopropyl xanthate resulted in Cu beneficiation up to 2–4% and final recovery within 42–46%. On the other hand, a mixed meso-acidophilic bacterial consortium comprised of a group of iron and/or sulfur oxidizing bacteria resulted in enhanced recovery of Cu (~92–96%) from the slag sample. SEM characterization of the bioleached slag residue also showed massive coagulated texture with severe weathered structures. FE-SEM elemental mapping with EDS analysis indicated that the bioleached residues were devoid of copper.

Characterization and recovery of copper values from discarded slag

In any copper smelter large quantities of copper slag are discarded as waste material causing space and environmental problems. This discarded slag contains important amounts of metallic values such as copper and iron. The recovery of copper values from an Indian smelter slag that contains 1.53% Cu, 39.8% Fe and 34.65% SiO 2 was the focus of the present study. A complete investigation of the different phases present in the slag has been carried out by means of optical microscopy, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. It is observed that iron and silica are mostly associated with the fayalite phase whereas copper is present in both oxide and sulfide phases. These oxide and sulfide phases of copper are mostly present within the slag phase and to some extent the slag is also embedded inside the oxide and sulfide phases. The recovery of copper values from the discarded slag has been explored by applying a flotation technique using conventional sodium isopropyl xanthate (SIX) as the collector. The effects of flotation parameters such as pH and collector concentration are investigated. Under optimum flotation conditions, it is possible to achieve 21% Cu with more than 80% recovery.

Selection of Gravity Separators for the Beneficiation of the Uljin Tin Ore

ABSTRACT Gravity separation is typically used in the beneficiation of tin ores as the density difference between the valuable and associated gangue minerals is significant. In the present investigation, a cassiterite sample collected from the Uljin deposit in South Korea has been subjected to different gravity separators to evaluate the separation efficiency. The selection of gravity units has been made based on performance evaluation following heavy liquid separation and assessment of grade/recovery curves and Tromp curve methods. In addition, a gravity separation index (GSI) has been proposed that is simpler than other methods for assessing the performance of gravity separators.

A kinetic model for the prediction of water reporting to the froth products in batch flotation

Abstract Batch flotation experiments were carried out using coal and graphite samples by varying reagent dosages. The relationship between quantity of water reporting to the froth product with flotation time has been evaluated and is found to follow a first-order rate equation of the form: Ww = Ww ∞{1 − e−kw(t + &phis;)} The ultimate quantity of water Ww ∞ and rate constant kw values were calculated from the experimental data and related with the operating variables using second-order polynomial equations. Influence of the operating variables on Ww ∞ and kw values were quantified and it was found that frother dosage increases Ww ∞ and decreases kw values, indicating frother dosage enhances the froth quantity while decreasing its mobility. The correlation is drawn between mass of ash and mass of water reporting to the froth product and also the influence of the operating variable is analysed on the ratio, i.e. mass of ash to mass of water.

Analysis of Wet High-Intensity Magnetic Separation of Low-Grade Indian Iron Ore using Statistical Technique

The particle separation in a wet high-intensity magnetic separator depends on a number of variables. Applied magnetic field, particle size, and wash water rate play a vital role among them. Influences of these important variables were studied in detail following 33 full factorial designs of experiments using a laboratory/pilot-scale wet high-intensity magnetic separator (Gaustec G-340 Minimag). Statistical analysis of the results indicated that the influence of all these variables are significant (95% confidence level) on the recovery of magnetics and the order of significance follows, particle size > magnetic field > wash water rate. The experimental results used to develop the regression models to predict yield and grade at unknown operating conditions in the study range. Investigations carried out on a wet high-intensity magnetic separator using a low-grade iron ore sample containing 49.27% Fe shows that it is possible to upgrade to 62% Fe in the concentrate with poor yield values. A “tree” procedure (generally used to evaluate the flotation performance) was followed to evaluate maximum possible yield and grade by the magnetic separator. The “tree” procedure results provide useful information about the magnetic separation competence.

Recovery of ferrochrome values from flue dust generated in ferroalloy production – a case study

Abstract Ferrochrome is usually produced by the reduction of chromite ore in a submerged arc or direct current furnace. The production process generates a large quantity of flue dust that contains potentially valuable components, such as ferrochrome, iron and carbides. In many instances, valuable chromite minerals are misplaced in the flue dust along with the slag forming minerals during the reduction process. In the present investigation, mineral beneficiation techniques were used to recover the ferrochrome material in lieu of the pyro‐ and hydrometallurgical techniques, which are currently being practiced. The experimental results show that gravity concentration could enrich Cr values in the concentrate to 42·2% with 37·3% yield from flue dust material containing 37·3%Cr. The beneficiation techniques could only marginally enrich the ferrochrome values because of the complex association of the metallic phase with the slag forming phases.

Comparative separation analysis of direct and reverse flotation of dolomite fines

ABSTRACT In the present investigation, beneficiation of a low-grade dolomite fines was carried out with the aim to remove the siliceous gangue content. Extensive experimental studies on direct and reverse flotation were carried out on low-grade ore by varying the critical process variables, and the performance was compared. The experimental results show that it is possible to reduce the silica content following both direct and reverse flotation processes. Further, direct flotation results show better control over the quality of the product while reverse flotation has an edge on the product yield.