Abstract

The aim of this study is separation of uranium anomalies based on geophysical airborne data by utilizing the Concentration-Area (C-A) fractal model in Mahneshan 1:50000 sheet, NW Iran. Threshold values for the different anomalies of uranium were computed with the statistical method which shows that uranium anomaly commences from 282.1 eppm. Furthermore, the C-A log-log plot of uranium shows existence of two stages of uranium enrichment in this area. The major enrichment for U starts from 331.1 eppm. High intensity anomalies (>562.3 eppm) in the area are located in the central and northern parts of the area. The comparison between achieved results and fault’s position patterns shows a positive correlation between uranium anomalies and the faults system in the area. However, mica-schists host high intensive uranium
anomalies in the central part of the area. Results analyzed by the C–A fractal model certify that the interpreted anomalies based on the fractal model are accurate in comparison with the chemical analysis of lithogeochemical samples collected from the geophysical airborne anomalies.

Abstract

In this study, the results of mechanical activation of fly ash from thermal power plant “Nikola Tesla”- Obrenovac are presented. This study aimed high degree of fly ash reactivity by different types of mechano-activators. The mechanical activation of fly ash in the three types of mechano-activators: vibratory ring mill, planetary ball mil and conventional ball mill was investigated.
The all mechanical activation experiments were based on kinetic model. The mechanically activated fly ash, from each type of mechano-activator, was examined particularly by application of different analyses: the X-ray diffraction method, specific surface area, as well as, particle size distribution.
The obtained results of mechanically activated fly ash by vibratory ring mill were indicated on slight tendency of agglomerates, while this tendency is more pronounced in the planetary ball mill. The best experimental results were achieved by vibratory ring mill, where decreasing crystal state, gross distortion and enhanced reactivity were occurred. Enhanced reactivity is less prominent at the mechano-activators such as planetary and conventional ball mill.

Abstract

The Kremikovci deposit of siderite ore is localized at 15 km NE from Sofia town (Bulgaria). The running characteristics of siderite ores are investigated by complex methods of research. The siderite ore mineral composition dominates by siderite, barite and quartz. Microscopic polished sections have been studied to assess the size of liberation. Crushing and grinding tests have been established to achieve the assessed the liberation size. Separation on a spiral concentrator, after grinding has been performed. The separation tests have been carried out with raw and calcined siderite ore. A high iron recovery has been achieved. Second series of tests were performed with “Jones” type wet high intensity magnetic separator. The laboratory test run as follow: after grinding the raw ore has been calcinated, followed by low and high intensity magnetic separation. After calcination an enrichment in a low intensity magnetic separator gave high iron content, compared to the wet high intensity magnetic separation, but the quartz content in the magnetic product occured. Concerning the different electrostatic properties of the siderite and the gangue minerals, raw siderite ore has been also tested in electrostatic separator. Finally amine flotation tests of raw and calcined ore have been carried out. On the basis of the laboratory results siderite ore beneficiation method has been analyzed.

Abstract

The Multi-Gravity Separator (MGS) is novel enhanced gravity equipment for the separation ultra-fine minerals. The present investigation studied on the effects of different process variables on the performance of a multi-gravity separator for concentration of ultra-fine ferruginous chromite. The results revealed that, shake amplitude and wash water flow rate play a dominant role in controlling the grade (%Cr₂O₃) of the concentrate fraction whereas tilt angle and drum speed influence much on the recovery (%Cr₂O₃) of the concentrate fraction. It was found that the MGS could produce a concentrate of 45.69% Cr₂O₃ with 56.41% recovery from a feed assaying 21.06% Cr₂O₃ and 23.02% of Fe (T). In addition to this, optimized conditions were determined for producing metallurgical grade chromite concentrate (>40% Cr₂O₃) with 60% recovery. Different correlations were made for predicting the silica and iron content of the concentrate fraction.

Abstract

In this paper characterization studies are carried out on beach and dune sand samples collected from different locations of Konark-Ramachandi coastal stretch. Representative beach and dune sand samples were collected covering ~7 kilometres distance. Characterization studies reveals that d 80 passing size for beach sand samples varies from 378 μm to 438 μm and for dune sand samples it varies from 440 μm to 482 μm. The THM content of beach sand samples vary from 16.8% to 18.2% and for dune sand THM varies from 9.9% to 12.3%. Total Magnetic Heavy Minerals (TMHM) percent of beach sands varies from 12.6% to 15.4% and for
dune sand it varies from 6.5% to 9.2%. Beneficiation studies were carried out on composite bulk sample prepared from all beach and dune sand samples. The THM content of composite sample was found to be 16.7 %. Results of beneficiation studies show that ilmenite concentrate shows 6.0% yield with 99.4% grade. Garnet concentrate shows 4.8% yield with 94.0% grade. Sillimanite concentrate recovered with 2.7% of yield and 97.3% grade. The rutile concentrate obtained is 97.2 % grade with a yield of 0.11%. Zircon concentrate recovered shows yield of 0.13% with 98.0% grade.

Abstract

Samples of the large Jos Minesfield tailings were subjected to microscopic, sieve and chemical analyses. The <1 mm undersize of the ore was fed into the wet high intensity magnetic separator (WHIMS) at pulp density, feed and flow rates of 1.33 kg/m³, 250 kg/h and 188 ³/h, respectively; to yield middlings, rougher and pre-concentrate. The sun-dried 355 μm WHIMS undersize of the mixture of middlings, rougher fraction and the pre-concentrate was then wet gravity concentrated on the Wilfley shaking table to give the concentarate, middlings, tailings and rougher concentrate. The middlings obtained from the Wilfley shaking table was further recycled. The products obtained were also subjected to chemical analysis. The results obtained showed that the sub-hedral columbite assayed 12.5, 45.5 and 2.95 % in the tailings as-received, the final concentrate and final tailings respectively, with 2.30% silver oxide. The recovery and separation efficiency of the process were determined as 58.47 and 51.4 %, respectively. The good recovery of silver oxide and the reasonable operating efficiency makes the wet processing route economic and acceptable for the tailings dump.