| 1. |
- Dwari, Ranjan, et al.
(författare)
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Characterising electron transfer mechanism in tribo-electrification of pyrite through contact angle measurements
- 2008
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Ingår i: Open Mineral Processing Journal. - : Bentham Science Publishers Ltd.. - 1874-8414. ; 1, s. 6-17
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Tidskriftsartikel (refereegranskat)abstract
- Coal beneficiation by tribo-electrostatic method depends on tribo-charging attributes of coal and ash forming minerals. The tribo-electrification behaviour of pyrite mineral contacted with different materials has been investigated through charge measurements and the charge acquisition is probed through surface energy calculations from liquid contact angle data. Liquid contact angle on pyrite powder after tribo-electrification is determined by Kruss tensiometer using Washburn's equation. The sample holder in tensiometer is specially fabricated with different materials serving the purpose of tribo-electrification and contact angle measurement. The acid and base parameters of pyrite surface determined with van Oss acid-base approach using liquid contact angle data after tribo-electrification with different materials revealed the charging phenomena and electron transfer mechanism. The results showed an explicit correlation between the charge generated by pyrite powder and surface acceptor (acid)-donor (base) electronic state underlying the work functions of contacting surfaces. Thus a method for characterising the changes in surface energetic structure of solids during contact electrification in terms of surface acid-base parameters has been illustrated for the first time.
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| 2. |
- Gahan, Chandra Sekhar, et al.
(författare)
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Study on the possibilities to use ashes, EAF dust and lime sludge as neutralising agent in bioleaching
- 2008
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Ingår i: Open Mineral Processing Journal. - : Bentham Science Publishers Ltd.. - 1874-8414. ; 1, s. 26-36
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Tidskriftsartikel (refereegranskat)abstract
- Studies were conducted to investigate the possibilities to use combustion ashes, electric arc furnace (EAF) dust and lime sludge as neutralising agent with reference to a commercial grade slaked lime. To maintain optimum pH during biooxidation of pyrite the acid produced has to be neutralised. Batch bioleaching was performed on a pyrite concentrate in 1-L reactors, using a mixed mesophilic culture at a temperature of 35ºC. Neutralising agents were added regularly to adjust pH to the desired level of 1.5. The ashes used were Bioash, Waste ash and Coal & Tyres ash, representing ashes generated from combustion of biomass, a mixture of wood chips and municipal waste, and a mixture of coal and tyres. The dust used was an EAF dust produced in a scrap-based steel plant, while the sludge used was Mesalime produced in a paper and pulp plant.The study aimed to investigate the possibility to replace the conventionally used lime or limestone with by-products, based on their neutralising capacity and to observe eventual toxic effects on the bacterial activity. The bioleaching efficiency was similar for all the neutralising agents used except Waste ash, when compared with slaked lime. The extent of pyrite oxidation was in the range 69-75% for all neutralising agents, except Waste ash, which had a pyrite oxidation of 59%. The Waste ash contained a large number of potentially toxic elements and the chloride concentration of 11% probably had a negative effect as observed on the lower redox potential and pyrite oxidation. The EAF dust has a good potential to be used as neutralising agent in bioleaching processes for zinc recovery from zinc sulphides, due to the high content of zinc, however the chlorides present should be removed prior to its use. The neutralising capacity, as determined by the amount needed for neutralisation during bioleaching, were rather high for EAF dust, Bioash and Mesalime with 37 g, 33 g and 29 g, respectively as compared with 22 g needed for slaked lime. However, Waste ash and Coal & Tyres ash had lower neutralising capacities with 81 g and 57 g needed, respectively. It is concluded that the replacement of lime or limestone with ash, dust or lime sludge can render considerable cost savings to the bioleaching operation. In addition, it is a means for sustainable use of natural resources, which would provide opportunities to recycle elements present in them like for example zinc.
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| 3. |
- Kota, Hanumantha Rao, et al.
(författare)
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Challenges in sulphide mineral processing
- 2011
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Ingår i: Open Mineral Processing Journal. - : Bentham Science Publishers Ltd.. - 1874-8414. ; 4, s. 7-13
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Tidskriftsartikel (refereegranskat)abstract
- Scientists and technologists in world over are making large efforts to streamline the conventional technological schemes of ore processing, in particular froth flotation towards reducing overall costs, limiting the use of dangerous substances, decreasing waste streams and improving waste disposal. Hitherto, search for such innovations has been performed mainly empirically and there is an urgent need to shift these technologies to be more innovative and effective. Understanding of the fundamental concepts of aquatic chemistry of minerals-selective adsorption and selective redox reactions at mineral-solution interfaces would impact innovating conventional flotation process. Molecular-level knowledge and coherent understanding of minerals contacted with aqueous solutions is required which underlie great opportunities in controlling mineral-solution interfaces towards the grand challenge of tomorrow's science and mineral processing technology.Aqueous redox chemistry of sulphides and adsorption mechanisms, the problems of metal sulphides selectivity against pyrite and fine particle flotation have been highlighted and discussed in the light of literature. The requisite knowledge and research needs to address these issues have also been briefly presented.
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| 4. |
- Kota, Hanumantha Rao, et al.
(författare)
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Mixed anionic/non-ionic collectors in phosphate gangue flotation from magnetite fines
- 2011
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Ingår i: Open Mineral Processing Journal. - : Bentham Science Publishers Ltd.. - 1874-8414. ; 4, s. 14-24
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Tidskriftsartikel (refereegranskat)abstract
- Scientists and technologists in world over are making large efforts to streamline the conventional technological schemes of ore processing, in particular froth flotation towards reducing overall costs, limiting the use of dangerous substances, decreasing waste streams and improving waste disposal. Hitherto, search for such innovations has been performed mainly empirically and there is an urgent need to shift these technologies to be more innovative and effective.Understanding of the fundamental concepts of aquatic chemistry of minerals–selective adsorption and selective redox reactions at mineral–solution interfaces would impact innovating conventional flotation process Molecular-level knowledge and coherent understanding of minerals contacted with aqueous solutions is required which underlie great opportunities in controlling mineral–solution interfaces towards the grand challenge of tomorrow’s science and mineral processing technology. Aqueous redox chemistry of sulphides and adsorption mechanisms, the problems of metal sulphides selectivity against pyrite and fine particle flotation have been highlighted and discussed in the light of literature. The requisite knowledge and research needs to address these issues have also been briefly presented.
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| 5. |
- Kuyumcu, Halit Z., et al.
(författare)
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Biocoagulation and its application potentials for mineral bioprocessing
- 2009
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Ingår i: Open Mineral Processing Journal. - : Bentham Science Publishers Ltd.. - 1874-8414. ; 2, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- The well-known sorting processes like density separation, separation in magnetic or electric fields and flotation, are not suitable to apply successfully within a particle-size range smaller than 10 μm. Due to insufficient selectivity of above mentioned enrichment processes the concentrate recovery at this particle size range is extremely poor, which influences accordingly the techno-economic efficiency of mineral processing negative.Based on a process design idea, investigations confirm that the biocoagulation of microorganisms and solid particles can be used to generate coarser sized coagulates which are more suitable for sorting. Experimental investigations showed that microorganisms like Saccharomyces cerevisiae and Yarrowia lipolytica and sulphide particles like galena and sphalerite below 10 μm coagulate effectively. Theoretical thermodynamic and extended DLVO theory calculations are in good agreement with microorganisms adhesion onto metal sulphides but not on silicates and selective biocoagulation of sulphides. Furthermore it has been demonstrated that flotation is suitable for the separation of the selectively formed biocoagulates.
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| 6. |
- Oghazi, Pejman, et al.
(författare)
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Classifying best access points for return of external flows into flowsheets
- 2011
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Ingår i: Open Mineral Processing Journal. - : Bentham Science Publishers Ltd.. - 1874-8414. ; 4, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- External flows are process streams that come from auxiliary processes or events. They are re-routed into the ordinary flowsheet since they are thought to be too valuable to be sent to any tailings pond. External flows come from multiple sources, e.g. drainage sumps, spillage thickeners, depleted products etc. Therefore, external flows may fit or notfit into an existing flowsheet depending on several factors like, flow rate frequency, dilution ratio variation, chemical and mineralogical composition, particle size or particle morphology. By using Particle Texture Analysis to investigate external flows and compare them with existing ordinary flows it is possible to pinpoint from a process mineralogy via point to what extent the external flow fits into the ordinary processing flowsheet. Results from this information category helps to reach a higher quality of process knowledge and control for every step in the concentrator. Results show that some recycled flows reconnected to the main flow are not connected to the best point. A side effect of the analysis is that some flows may be sent to later grinding stages. Thus, decreasing the load on the primary mill, and increasing the retention time.
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