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| 2. |
- Banda, S.M.Herath, et al.
(författare)
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Variation of filter cake permeability with mean pore diameter of the cake
- 1998
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Ingår i: Scandinavian journal of metallurgy. - 0371-0459 .- 1600-0692. ; 17:2, s. 67-72
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that most particles in a filter cake have more than only point contact with each other. Therefore, the Kozeny-Carmen equation is modified by relating permeability to porosity and a mean pore diameter as measured by automatic image analysis in horizontal cross sections of the cake. In filter cakes of chalcopyrite and magnetite, the permeability increases stepwise with the product of porosity and square mean pore diameter.
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| 3. |
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| 4. |
- Das, A., et al.
(författare)
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Surface chemical and adsorption studies using Thiobacillus ferrooxidans with reference to bacterial adhesion to sulfide minerals
- 1999
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Ingår i: Biohydrometallurgy and the Environment toward the Mining of the 21st century. - : Elsevier. - 0444501932 ; , s. 697-707
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Konferensbidrag (refereegranskat)abstract
- Adhesion of Thiobacillus ferrooxidans to pyrite and chalcopyrite in relation to its importance in bioleaching and bioflotation has been studied. Electrokinetic studies as well as FT-IR spectra suggest that the surface chemistry of Thiobacillus ferrooxidans depends on bacterial growth conditions. Sulfur-,Pyrite- and chalcopyrite-grown Thiobacillus ferrooxidans were found to be relatively more hydrophobic. The altered surface chemistry of Thiobacillus ferrooxidans was due to secretion of newer and specific proteinaceous compounds. The adsorption density corresponds to a monolayer coverage in a horizontal orientation of the cells. The xanthate flotation of pyrite in presence of Thiobacillus ferrooxidans is strongly depressed where as the cells have insignificant effect on chalcopyrite flotation. This study demonstrate that:(a)Thiobacillus ferrooxidans cells can be used for selective flotation of chalcopyrite from pyrite and importantly at natural pH values.(b)Sulfur-grown cells exhibits higher leaching kinetics than ferrous ion-grown cells.
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| 5. |
- Deo, N., et al.
(författare)
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Biodegradation of some organic reagents from mineral process effluents
- 1999
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Ingår i: Biohydrometallurgy and the Environment toward the Mining of the 21st century. - : Elsevier. - 0444501932 ; , s. 687-696
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Konferensbidrag (refereegranskat)abstract
- The utility of a soil microbe, namely Bacillus polymyxa, in the removal of organic reagents such as dodecylamine, ether diamine, isopropyl xanthate and sodium oleate from aqueous solutions is demonstrated. Time-bound removal of the above organic reagents from an alkaline solution was investigated under different experimental conditions during bacterial growth and in the presence of metabolites by frequent monitoring of residual concentrations as a function of time, reagent concentration and cell density. The stages and mechanisms in the biodegradation process were monitored through UV-visible and FTIR spectroscopy. Surface chemistry of the bacterial cells as well as the biosorption tendency for various organics were also established through electrokinetic and adsorption density measurements. Both the cationic amines were found to be biosorbed followed by their degradation through bacterial metabolism. The presence of the organic reagents promoted bacterial growth through effective bacterial utilization of nitrogen and carbon from the organics. Under optimal conditions, complete degradation and bioremoval of all the organics could be achieved
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| 6. |
- F., Su, et al.
(författare)
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Computer estimation of flotation kinetic model parameters
- 1998
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Ingår i: 2Papers presented at the APCOM '98 conference, organized by the Institution of Mining and Metallurgy and held in London, United Kingdom from 19 to 23 April, 1998. - London : The Institution of Mining and Metallurgy. - 1870706366 ; , s. 513-524
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Konferensbidrag (refereegranskat)abstract
- The effect of chemical variables on the kinetic parameters of apatite flotation from magnetite has been investigated. The two common first-order kinetic models reported in the literature, i.e., the model with rectangular distribution of floatabilities and the model with fast and slow-floating components (F-S model) have been applied in the evaluation of flotation results. The models are evaluated by fitting the flotation results from batch flotation tests. The results although indicate that both models describe the apatite flotation kinetics well in a wide range of kinetic parameters, the F-S model is found to be better in the goodness of fit to the results from every flotation test and also to describe the flotation performance adequately. The kinetic parameters of the F-S model are varied with a change in chemical variables. In particular, the rate constants ratio Kf/Ks is found to be an important parameter for achieving selectivity between apatite and magnetite, and the effect of reagents dosages on the ratio is discussed. The effect of particle size on the apatite flotation kinetics is also illustrated by analysing the froth products at each flotation time in different size classes.
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| 7. |
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| 8. |
- Forssberg, Eric, et al.
(författare)
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Metals recycling from electronic scrap by air table separation : theory and application
- 1998
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Ingår i: EPD Congress 1998. - Warrendale, Pa. : Minerals, Metals & Materials Society. - 0873393880 ; , s. 497-515
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Konferensbidrag (refereegranskat)abstract
- Metals recovery from electronic scrap by physical separation may provide an alternative to the current recycling approach, through which halogenated flame retardants can result in hazardous dibenzo-p-dioxins and dibenzo-furans. On the basis of a complete sink-float analysis of personal computer and printed circuit board scrap, and in view of the advantages of dry processes for electronic scrap recycling by mechanical separation, air table separation is prioritized in an attempt to separate metals from plastics and glass involved. In the present paper, theoretical and practical considerations of air table separation have been detailed. It has been shown that air table separation is effective for recovering copper and precious metals from this specific waste stream. With the feed rate of 60 kg per hour, the combined grade and recovery of copper, gold, and silver attainable for the two heavy products produced by the air table used in the present study was shown in a table.
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| 9. |
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| 10. |
- Gao, Mingwei, et al.
(författare)
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Prediction of product size distributions for a stirred ball mill
- 1995
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Ingår i: Powder Technology. - 0032-5910 .- 1873-328X. ; 84:2, s. 101-106
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Tidskriftsartikel (refereegranskat)abstract
- Simulation of the ultra-fine grinding process is a formidable task, attended to by many researchers using models from conventional ball mill grinding. It has been realised that the first-order breakage hypothesis is not valid in fine grinding and that the process mechanism differs substantially from that for ball mills. In this paper, the difference between ball mill grinding and stirred ball milling is discussed. A size-energy model is proposed for simulation of stirred ball milling. The product size distributions below 10 μm from a stirred ball mill were simulated by the model satisfactorily. The model is simple and has only two parameters. The model was tested under different milling conditions for a stirred ball mill.
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