Y. Rama Murthy

Processing of Ferruginous Chromite Ore by Dry High-Intensity Magnetic Separation

ABSTRACT Mineral and morphological characteristics of chromite ore strongly affect the separation efficiency while upgrading the low-grade deposits. Usually, chromite ore enrichment is carried out by using gravity separation due to high-concentration criterion between chromite and other minerals. However, chromite ore from Sukinda region, India, is a typical ore body with high iron content in the chromite spinel as well as gangue content in the form of oxide and hydroxides of iron-bearing minerals. So, the separation efficiency reduces by gravity method due to the lower value of concentration criterion. To address this, dry magnetic separation is an alternative approach to separate these iron-bearing gangue minerals from the chromite. This work investigated on the application of different dry high-intensity magnetic separators to separate the chromite grains from ferruginous chromite ore deposits of India. Prior to the separation, two different ore deposits of Sukinda region are subjected to detailed mineral, chemical, morphological, as well as magnetic properties characterization to visualize the separation. Tests confirm the effect of magnetic field strength along with other process parameters that influence the process of the separation of iron-bearing gangue minerals. The results on these separators are related to the influence of mineralogy, process parameters, and magnetic property of minerals, based on the experimental and statistical analysis of the process. Also, effect of desliming of the low-grade deposit prior to the dry magnetic separation is highlighted.

Dry High-Intensity Magnetic Separation in Mineral Industry – A Review of Present Status and Future Prospects

ABSTRACT High intensity dry magnetic separators are in use for various applications in the mineral as well as coal processing industries. Evaluation of the performance of these separators treating different minerals has become an active research topic. Several attempts have been made by different researchers and technologists to understand the separation behavior of particles in each of these separators treating different types of para-magnetic minerals. Despite all these efforts, these separators are yet to find widespread applications to treat different para-magnetic minerals. Therefore, the present status of these separators with a brief description of their operating principles, applications, and modeling are reviewed in this article. Also, the research work needs to focus on each separator has been highlighted.

Multiobjective optimisation of spiral concentrator for separation of ultrafine chromite

Chromite beneficiation plants generate large amount of tailings with significant amounts of ultrafine chromite minerals. In the present investigation, Box−Behnken experimental design was used to model the effects of feed rate, feed pulp density and splitter position on the performance of a spiral concentrator for separating the ultrafine chromite values from the plant tailings. Splitter position has a major influence on both grade and recovery of the concentrate fraction of spiral concentrator. Second-order quadratic models were used for describing the performance of spiral concentrator. Multiobjective optimisation of process parameters was carried out for achieving both in grade and recovery which were higher than 40% and 30% Cr2O3, respectively.

Recycling of ferromanganese gas cleaning plant (GCP) sludge by novel agglomeration

Ferroalloy industries rely on minerals which are not available in pure form. The total value chain is very cost intensive and market driven. From mineral and environment conservation point of view every possible aspect must be explored for the economic utilisation of waste and low-grade ores. Unlike other metallurgical processes, Ferro alloys production generates a wide variety of waste rich in manganese/chrome which has a potential for recycling back. Fine size, high moisture content and presence of alkalis categorise this material into hazardous waste and economically non-viable. The challenge is to convert such anthropogenic material into a suitable feedstock for the furnace. In this article, the results of smelting trials carried out in electric arc furnace (EAF) using novel extruded briquettes (BREX) produced from the wastes of ferroalloy plant is discussed. The briquette produced by this technique exhibit high physical and metallurgical property and can replace the natural ore as a charge to some extent. Extruded briquettes (BREX) can be efficiently used as one of the essential charge component (up to 30% of the ore part of the charge) for the Silicomanganese smelting thus improving technical and economical parameters of the furnace and decreasing the self-cost of the Silicomanganese production.

Study of the kinetics of the magnesium leaching from serpentine bearing chromite overburden rocks for mineral carbonation

ABSTRACT Characterisation and leaching studies have been carried out on serpentinite rock samples collected from Sukinda mines, India. Dissolution characteristics of samples have been studied using HCl, H2SO4 and HNO3 acid. Effect of particle sizes, solvent concentrations, reaction temperatures and reaction time have been investigated. It was found that Mg recoveries vary between 54.95% and 98.12%. Leaching of fine particles of <53 µm sizes using H2SO2 solution of 1 M at 70°C for 2 h can recover maximum 93% Mg with lowest Si content (6.6%). Kinetic studies indicated that dissolution of Mg follows product layer diffusion mechanism and activation energy calculated was 37.88 kJ mol−1. CO2 treatment of leach liquor resulted in precipitation of magnesium carbonates and hydroxides at a solution pH adjustment between 7 and 10. The study revealed that these rocks can be used for CO2 fixation and H2SO4 can be the best solvent.