Influence of Mineralogy on the Dry Magnetic Separation of Ferruginous Manganese Ore—A Comparative Study

Magnetic separation is often considered pertinent for manganese ore beneficiation when the ore is abundant with siliceous rich gangue mineral phases. However, the process is deemed to be inapposite for the ferruginous type of ore, and remains a grey area of research. In the present investigation, two different types of manganese ore were studied in detail to understand the influence of mineralogy on their magnetic separation performance. Detailed experiments were performed by varying the critical variables of the dry magnetic separator, and the separation features were studied. The ore samples were thoroughly characterized by various techniques, including an automated advanced mineralogical tool. The mineralogical results revealed that primary manganese bearing minerals in both the ores are rich in cryptomelene, pyrolusite, psilomelane, and bixybyite. Similarly, the major gangue minerals were alumina-bearing minerals and iron-bearing phases (hematite and goethite). The optimum grade that could be obtained from single-stage dry magnetic separation was 35.52% Mn, and with a Mn:Fe ratio of 1.77, and 44% Mn recovery in the case of sample 1; whereas, a 33.75% Mn grade, with a Mn:Fe ratio of 1.66 at Mn recovery of 44% was reported for Sample 2. It was observed that both samples had a similar input chemistry (~28% Mn, ~1 Mn: Fe ratio) however, they had distinctive mineralogical assemblages. Furthermore, it was observed that the liberation of manganese mineral was in a course size range, i.e., 300 to 450 µm, while the association of iron and manganese bearing phases was lower in sample 1 when compared to sample 2.

Remote Observation in Habitat Suitability Changes for Waterbirds in the West Songnen Plain, China

Being one of the most important habitats for waterbirds, China’s West Songnen Plain has experienced substantial damage to its ecosystem, especially the loss and degradation of wetlands and grasslands due to anthropogenic disturbances and climate change. These occurrences have led to an obvious decrease in waterbird species and overall population size. Periodic and timely monitoring of changes in habitat suitability and understanding the potential driving factors for waterbirds are essential for maintaining regional ecological security. In this study, land cover changes from 2000 to 2015 in this eco-sensitive plain were examined using Landsat images and an object-based classification method. Four groups of environmental factors, including human disturbance, water situation, food availability, and shelter safety, characterized by remote sensing data were selected to develop a habitat suitability index (HSI) for assessing habitat suitability for waterbirds. HSI was further classified into four grades (optimum, good, general, and poor), and their spatiotemporal patterns were documented from 2000 to 2015. Our results revealed that cropland expansion and wetland shrinkage were the dominant land cover changes. Waterbird habitat areas in the optimum grade experienced a sharp decline by 7195 km2. The habitat area in good suitability experienced reduction at a change rate of −8.64%, from 38,672 km2 to 35,331 km2. In addition, waterbird habitats in the general and poor grades increased overall by 10.31%. More specifically, the total habitat areas with optimum suitable grade, in five national nature reserves over the study region, decreased by 12.21%, while habitat areas with poor suitable grade increased by 3.89%. Changes in habitat suitability could be largely attributed to the increase in human disturbance, including agricultural cultivation from wetlands and grasslands and the expansion of built-up lands. Our findings indicate that additional attention should be directed towards reducing human impact on habitat suitability for sustainable ecosystems.

Flotation study on low-grade antimony ore of qilla abdullah, Balochistan, Pakistan

A low-gradeantimony deposit originating from district Qilla Abdullah, Balochistan Province of Pakistan, containing stibnite as an economical mineral was beneficiated by froth flotation technique. Flotation parameters such as particle size of the feed, pulp density, pH of the pulp, agitation speed, type and dose of reagents (i.e. collector, frother, activator, regulator and modifier) and the conditioning time were studied on the basis of single-factor variation experiment in order to get the optimum grade and recovery. Regrinding of the rougher concentrate followed by cleaning andrecleaning of rougher concentrateensured a final concentrate grade of 65.12% Sb@ 85.79% recovery. This concentrate is suitable for the extraction of metal and production of chemicals. DOI: http://dx.doi.org/10.3329/bjsir.v49i2.22003 Bangladesh J. Sci. Ind. Res. 49(2), 95-102, 2014

THE EFFECTS OF INCREASING DIETARY ROUGHAGE LEVEL AND SLAUGHTER WEIGHT ON THE FEEDLOT PERFORMANCE AND CARCASS CHARACTERISTICS OF BULLS AND STEERS

A serial slaughter experiment is described comparing 45 bulls and 44 implanted steers. Nine of each "sex" were slaughtered at the start of the trial and the remaining 71 were fed diets containing three roughage levels (20%, 50% and 80% alfalfa–brome hay) to two pen-average slaughter weights (450 kg or 580 kg). Cattle were about 12 mo old at the start of the trial, and bulls were heavier (290 kg vs. 269 kg) than steers. Increasing the level of roughage in the diet resulted in a significant decrease in average daily gain (ADG), and an increase in feed intake and feed per kilogram gained to both slaughter weights. Differences in digestible energy (DE) intake were not significant. Apparent digestibilities of dry matter, crude protein and DE were significantly decreased, and acid detergent fiber significantly increased, by increasing levels of roughage. Bulls grew faster than steers and required less feed per unit of gain to both slaughter weights. Increasing the level of roughage decreased warm carcass weight, dressing percent and all measures of carcass fatness to both slaughter weights. Cattle fed low levels of roughage reached an optimum grade (A1) at a lower carcass weight than those fed high levels of roughage, and remained in that grade for a shorter period of time. Fat-free body size tended to increase with roughage level. Steer carcasses were fatter than those of bulls and had lighter sample muscle weights and smaller sample muscle to bone ratios. Based on present feed costs the lowest roughage diet produced the cheapest liveweight gain.

Flotation Studies on Scheelite Concentrate of Chitral, NWFP, Pakistan

A scheelite concentrate, containing 32% WO3, obtained from an indigenous tungsten ore of Chitral, NWFP, Pakistan, has been beneficiated by froth flotation technique to produce high quality tungsten concentrate assaying 64.8% WO3 with 84.47% recovery. This paper presents results on the optimization of flotation parameters like pH, pulp density and reagents. The optimum grade and recovery have been obtained at a feed size of 80 % passing 74 μm, pulp pH of 10.5, pulp solids 25%, oleic acid 0.30 kg/t, polyglycol 0.02 kg/t and sodium silicate 0.125 kg/t of the feed. The obtained tungsten concentrate meets the specifications required to produce tungsten metal and tungsten based chemicals. Key words: Scheelite Concentrate; Beneficiation; Flotation; Grade; Recovery DOI: http://dx.doi.org/10.3329/bjsir.v46i1.8115 Bangladesh J. Sci. Ind. Res. 46(1), 123-126, 2011