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The rare-earth elements (REEs) have gained enormous economic and scientific attention due to their distinct properties and new applications. Nepheline syenite rock is an important primary source of rare earth minerals. The nepheline syenite rocks from the Rairakhol area, western Odisha, have been characterized for their rare earth mineralogical and textural characteristics. Preliminary beneficiation studies of these rocks were carried out to upgrade the REE values using falcon gravity separation and floatation technique. Hornblende, biotite, K-feldspar, albite, and nepheline are the major mineral constituents of the nepheline syenite where REE-bearing minerals occur as accessory minerals. The REE mineral phases present are zircon, sphene, apatite, allanite, britholite, and REE phosphate, with grain sizes ranging from 10 to 50 microns. Allanite and britholite occupy the intergranular spaces of major mineral phases and occur as thin lines or veins whereas sphene and zircon occur as inclusions within major mineral phases. The flotation study shows that the total REE content of the froth product could be enriched to 1696 ppm, which is three times more than the total REE content (563 ppm) of the feed sample. [ABSTRACT FROM AUTHOR]

The work illustrates the physico-chemical, petrographic characteristics and flotation response of low-grade oxidized coking coal containing 39.5% ash. The maceral composition, surface oxidation, and particle liberation are the factors that affect coal flotation. The oxidized coal requires more collectors than the freshly ground coal. The flotation process modeling and optimization of −0.5 mm coal fraction was carried out using response methodology and central composite rotatable design (CCRD). The diesel, MIBC, and sodium hexametaphosphate are used as collectors, frothers, and depressants to maximize the coal grade, yield, and combustible recovery. At an optimum dosage of 1.35 kg/ton collector, 0.2 kg/ton frother, and 0.5 kg/ton depressant, it is possible to achieve 11.3% ash-clean coal with a 50.72% yield from 39% feed ash coal. The ash, yield, and combustible recovery model prediction matched well with the experimental results. The R2 of the ash, yield and combustible recovery model are 0.9676, 0.9662, and 0.9692, respectively. The work highlights that Indian coal can upgrade for metallurgical use using a flotation process. [ABSTRACT FROM AUTHOR]

The present article reports a novel process for the recovery of potash values from mica scrap (K2O 8.72%) using Linz-Donawitz Slag (LDS) and NaCl. Acid leaching of ground mica powder suggests a maximum of 22% potassium extraction. The roasting coupled water leaching process, using a mixture of LDS and NaCl, could extract a maximum of 93% potash at 900°C for 30 min roasting. The roasting temperature is the key parameter during the extraction process. The possible potash recovery mechanism is discussed on the basis of XRD, EPMA, and SEM-EDS studies of various feed and processed products. [ABSTRACT FROM AUTHOR]

The study focuses on the use of microwave energy in the reduction roasting followed by magnetic separation studies of an Indian Banded Hematite Jasper (BHJ) ore assaying about 48% Fe. Two coals having different origins have been used as the reductants, and the effects of their petrographical characteristics on the microwave-assisted carbothermic reduction have been discussed. The impacts of various process variables such as microwave power, time, ore and coal size have been studied and subsequently optimized using the Taguchi based statistical design. Microwave power and time are found to be the most influential factors, while the particle sizes of the ore and coal play less significant roles. The coal having higher vitrinite reflectance and lower mineral matter is found to be a better reductant in the microwave roasting as it has given rise to a magnetic concentrate of ~64% Fe with a recovery of 68.4% at process conditions such as a power of 6 kW, time of 16 min and C/Fe ratio of 0.15. In contrast, even at the same C/Fe ratio, the coal having lower vitrinite reflectance and higher mineral matter could generate a concentrate with an iron recovery of 34.59%. The X-Ray Diffraction, optical micrographic, Scanning Electron Microscopic (SEM) and Vibrating Saturation Magnetometry (VSM) studies have been used to characterize the microwave roasted products with an intention to understand the phase changes. [ABSTRACT FROM AUTHOR]

Siliceous manganese ore, associated with the banded iron formation occurs in large volume in northern Odisha, India. It is a sub-grade ore containing 21% Mn, 60% SiO2 and 3% Fe, hence do not find any use and considered as waste. Such ore does not respond to any physical beneficiation techniques because of intricate microstructure and poor liberation of Mn-phase. It could only be up-graded to 32% Mn with 36% yield and 52% recovery by processing it through mineral separator followed by WHIMS. Siliceous manganese ore along with calcite and coke in appropriate ratio, when charged to a plasma reactor, a product with slag metal ratio of 2.5:1 was obtained within a period of 10 min. Electron probe micro-analysis of the metal confirmed it to be ferrosilicomanganese while the slag constitute of tricalcium silicate (C3S) with around 5% Mn in adsorbed state. [ABSTRACT FROM AUTHOR]