Pre-Concentration of Vanadium from Stone Coal by Gravity Using Fine Mineral Spiral
Due to the low grade of V2O5 in stone coal, the existing vanadium extraction technologies face challenges in terms of large handling capacity, high acid consumption and production cost. The pre-concentration of vanadium from stone coal before the extraction process is an effective method to reduce cost. In this study, detailed mineral characterization of stone coal was investigated. It has been confirmed that the vanadium mainly occurs in muscovite and illite. A significant demand for an effective pre-concentration process with simple manipulation for discarding quartz and other gangue minerals is expected. Based on the mineralogical study, a new vanadium pre-concentration process using a fine mineral spiral was investigated. The experimental results showed that the separation process, which was comprised of a rougher and scavenger, could efficiently discard quartz, pyrite and apatite. A final concentrate with V2O5 grade of 1.02% and recovery of 89.6% could be obtained, with 26.9% of the raw ore being discarded as final tailings.
Study of the Dissolution Behavior of Muscovite in Stone Coal by Oxygen Pressure Acid Leaching
The dissolution behavior of muscovite in stone coal during the oxygen pressure acid leaching process was studied. The study showed that the dissolution behaviors of V, Al, and K were similar. K was the most easily leached, followed by Al, and then by V during oxygen pressure acid leaching process. When the reaction temperature exceeded 423 K (150 °C), alunite was generated, which led to vanadium losses because of its absorption performance. The dissolution of the muscovite in stone coal mainly depended on H2SO4 concentration and temperature. O2 had a main effect not on muscovite’s dissolution but on the V3+ oxidation. During the oxygen pressure acid leaching process, (1) the interfacial K in the muscovite lattice was dissolved rapidly, producing a new interface; (2) for charge balance, the interfacial O absorbed hydrogen ions to form hydroxy; (3) the interfacial hydroxy reacted with hydrogen ions and left vacancy as a result of O loss, producing more new surface to expose more Al, V, and Si; (4) the interfacial Al or V was exchanged by hydrogen ions and V3+ was oxidized to V4+ and V5+; and (5) Si hardly reacted with H+ and generated high-Si surface.
Diagnostic and therapeutic studies on chronic diarrhea in dairy animals
The study was conducted to determine the etiology of chronic diarrhea in dairy animals. Seven causes of chronic diarrhea were established in dairy cattle and buffaloes. Balantidiasis in 37.6 per cent, dietary diarrhea in 9.9 per cent, chronic salmonellosis in 6.9 per cent cases of chronic diarrhea, secondary copper deficiency and amphistomiasis in 6.9 per cent, clinical Johne‘s disease in 3.9 per cent and chronic peritonitis in 2.97 per cent of dairy animals, manifest chronic diarrhea. The precise diagnosis could not be established in 24.50 per cent of animals. Lymphosarcoma was confirmed in one of the dairy cattle. Body condition score was associated to the etiology of chronic diarrhea. B. coli infected cattle and buffalo revealed cysts in 32.3 per cent cases while 5 per cent positive cases revealed both cysts and trophozoites. Mean cyst count was 2.73±0.91 hpf in diarrheic animals compared to 0.11±0.447 hpf in healthy animals. Clinical Johne‘s disease was confirmed in four animals. Hematological changes revealed anemia and neutrophilia with morphological changes suggestive of regenerative to degenerative left shift. High plasma phosphorus, hypoproteinaemia and hypoalbuminaemia was seen in clinical Johne‘s disease. Salmonella isolates showed higher in-vitro sensitivity to enrofloxacin (87%), ciprofloxacin (87%), gentamicin (75%), and tetracycline (66.7 %) and were resistant to ampicillin and amoxicillin. Mean cyst count reduction from 2.41±1.16 to 0.11±.33 was observed in oral metronidazole treated group where as reduction of mean cyst count from 2.73±0.918 to 0.18±0.44 in intravenous metronidazole treated group. Recovery rate with oral and intravenous metronidazole was 42.1 and 63.1 per cent respectively. Recovery results in significant decrease in eiosionphil count and increase in total plasma protein in both oral and intravenous treatment groups. Complete recovery response approaches 60 per cent in balantidiasis affected adult dairy animals. Balantidiasis was the major cause of chronic diarrhea and intravenous administration of metronidazole was more effective than oral metronidazole.