Oxidation of Indian Ilmenite: Thermodynamics and Kinetics Considerations

Natural Ilmenite (FeO.TiO2) is the primary source for the extraction of titanium dioxide (T1O2). Oxidation-reduction process is used for production of synthetic rutile from ilmenite by separation of Fe-oxides from TiO2. In this paper thermodynamics and kinetic aspects of oxidation reactions of ilmenite are discussed. Ilmenite with53% TiO2 used for investigation is a bit different from conventio-nal feed materials used for up-gradation processes. The slag route is generally employed for processing of low grade ilmenite with 58% TiO2 are used for production of syn-thetic rutile. Therefore detailed understanding oxidation - reduction behaviour of ilmenite is essential for selec-tion and optimisation of suitable up-gradation process

Study of Liquid Phase Formation during the Sintering of Chromite Pellets and its Effect on the Properties of Pellets

For production of ferrochrome in submerged arc furnace (SAF), chromite ore is used in the form of lumps, briquettes and sintered pellets.The sintered pellets are preferred as a feed in SAF as it improves the furnace performance. During sintering of the green chromite pellets, bentonite reacts with silicate gangues in the chromite and forms the liquid phase which acts as a bin-der. The physical and metallurgical properties of the sintered pellets depend on the formation of liquid phase. The properties sintered pellets samples collected from the sintering plant were evaluated in the laboratory. The compressive strength of the samples varied significantly from 5 kg/pellet to 305 kg/pellet. The microstructure of the sintered pellets revealed that the porosity and form-ation of liquid phase affects the compressive strength of the pellets. In addition of this the oxidation of chromite grains during cooling of also influences the strength of the pellets and its metallurgical properties. The results of characterization studies are presented in this research work to relate the liquid phase formation and pellet properties for improved metallurgical applications

Ultra fine chromite concentration using spiral concentrator

The conventional chromite beneficiation circuit utilises spiral concentrator for recovering chromite fines and as its efficiency decreases with respect to the decrease in particle size. Pilot scale studies have been performed to understand the effect of different process parameters which influence the separation of ultra fine chromite fines from a typical plant tailing. The process parameters of spiral concentrator such as feed rate (m3/hr), feed pulp density (% solids by weight) and splitter position (cm) are considered for the study. Splitter position has major influence on both grade and recovery of the concentrate fraction of spiral concentrator. Maximum grade of 48.54% Cr2O3 can be achieved in the concentrate fraction of spiral concentrator with 20.41% Cr2O3 recovery. Performance of spiral concentrator at different combination of process parameters was analysed with 3D surface plots

Influence of shaking table process parameters on concentration of chromite plant tailings

Conventional chromite beneficiation plants of India discards large tonnage of chromite values as plant tailing. In the present investigation, a typical chromite beneficiation plant tailing of Sukinda region has investigated by using wet shaking table for the effective utilisation of the natural resource. In this context, the effect of different process variables such as wash water flow rate, deck tilt angle and feed flow rate has analysed. The interactional effects between different process variables has analysed in terms of 3D response surface plots. It was found that the Cr2O3 content has improved to 61.37% from a feed assaying 24.26%. It was envisaged that deck tilt angle has influence major on both grade and recovery of concentrate fraction of shaking table and in case of interactional effects, the interaction between deck tilt angle and feed flow rate has major influence compared to the others. Second order quadratic equations have developed for the prediction of grade and recovery of concentrate fraction of shaking table

Selenium partitioning between slag and matte during smelting

Copper concentrates usually contain a number of minor as well as precious elements, the control of which in copper smelting processes is often a key to the quality of the anode copper produced and may also have a bearing on the overall economics of the process. During copper smelting, the copper concentrates are partially oxidized to form slag and matte. The molten slag and matte are separated from each other in the settler. The matte being heavier in density settles at the bottom of the furnace and slag being lighter in density floats over the matte and is eventually discarded off. During the separation, selenium is distributed between slag and matte. Selenium is a value added by-product of copper process. The lower recovery of selenium from the copper process is attributed to the high loss of selenium to the discarded slag. Knowledge of the distribution and form of selenium in slag and matte is very important in the control of the selenium loss, although to date very little is known regarding their distribution. The samples of slag and matte were collected from the smelter exit before their separation. Selenium was added in different proportions in the sample. The experiments involving slag-matte separation were performed at 1250A degrees C for 4 hours of soaking time under inert atmosphere in a vertical tubular furnace. The distribution of selenium and the mechanism by which selenium is dissolved in matte and slag have been established by this study

New prospective for the utilisation of Indian lateritic chromite overburden

Nickel laterites form ~75% of known nickel resources whereas majority of nickel is produced from sulphide sources. Nickel bearing laterite and chromitiferous overburden are the only source of nickel available in India. In India, 5,000,000T of such overburden is generated each year in addition to the 140,000,000T that has already been accumulated over several years of mining and it is estimated to increase with the consumption of chrome ore. With the depletion of sulphide deposits and for the future supply of nickel, the industry must develop for the utilization of laterite ore bodies, especially limonite deposits. In this study, the recovery of nickel associated within the goethite was attempted by employing combination of physical and pyro-metallurgical route from the lateritic ore received from Sukinda region of India. The rejects of the beneficiation process contains chromite which can be used as a feed for the ferro chrome plants. Through physical beneficiation the iron enrichment achieved was 52.74% with a weight percent recovery of 59.67% having Ni-0.9% from the feed assaying 46.73% Fe (T), 0.76% Ni. This beneficiated overburden was used as a feed for the production of pig iron nuggets. Composite pellets of overburden containing lime and coal were reduced at 1400°C for the production alloy pig iron nuggets. The nuggets produced from this route contain C~ 3%, Ni~1.7%, Cr~1.5% and Fe-Rest. Recoveries of iron, chromium and nickel are >95%, >95% and ~30%, respectively