| 1. |
- Dugic, Izudin, 1962-, et al.
(författare)
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The effect of chemical composition on the metal expansion penetration in grey cast iron
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In some grey cast iron components which are cast in sand moulds, the metal sometimes penetrates into the mould producing defects and causing difficulties when cleaning the components. To improve knowledge of the metal penetration mechanism a series of test castings was performed at ITT Flygt’s foundry where the influence of chemical composition was studied. The chemical composition of the melt was changed in the ladle before pouring. The result showed that the carbon and phosphorus content had an influence on metal penetration. The metal penetration tendency decreased when decreasing the carbon content as well as when increasing the phosphorus content. The penetration areas were analysed in a Scanning Electron Microscope (SEM) with Energy Dispersive Analysis (EDS). The analysis showed that the average chemical composition in the penetration zones was close to the initial composition of the alloy. Consequently, no significant macro segregation of carbon or phosphorous could be observed. The whole casting process was simulated with the software MAGMAsoftTM, in order to investigate the solidification characteristics as well as the porosity formation in the casting studied. For this, a special module for cast iron was used, MAGMAironTM, where nucleation and growth of all relevant phases are considered. During simulation it is possible to detect the areas where porosities are likely to be formed. The results show that expansion penetration generally occurs in the same areas depending on the mode of solidification. The inoculation and solidification behaviour will result in excess or deficiency of the metal at the end of solidification, which will lead to either metal penetration or formation of porosities.
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| 2. |
- Ullakko, Kari, et al.
(författare)
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Isothermal Martensite Transformation of Fe-Ni-C Alloys as a Function of Hydrostatic Pressure
- 1990
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Ingår i: Materials Science Forum volumes 56-58. - Zürich : Trans Tech Publiations. ; , s. 197-200
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Konferensbidrag (refereegranskat)abstract
- Isothermal martensite transformation as a function of hydrostatic pressure was studied in Fe-Ni-C alloys. It was observed that the transformation was much the same as it happens as a function of time. Any noticeable differences in the morphology between isothermal and athermal martensite were not seen.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Recina, Viktor, 1968, et al.
(författare)
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Sample preparation and microstructural characterization of the gamma titanium aluminide Ti-48Al-2W-0.5Si
- 1997
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Ingår i: Materials Characterization. - 1044-5803. ; 38:4-5, s. 287-300
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Tidskriftsartikel (refereegranskat)abstract
- Preparing samples that faithfully reveal all microstructural features in γ-TiAl-base alloys for both optical and scanning electron microscope studies is fraught with difficulties. This study demonstrates that satisfactory results can be obtained through mechanical grinding, polishing, and proper etching. A preparation recipe is presented. Nine lots of investmentcast γ-TiAl material with the nominal composition of Ti-48Al-2W-0.5Si have been characterized through optical and scanning electron microscope examinations. The study shows that a small depletion in Al content has a large effect on the microstructure. The duplex microstructure with a lamellar Full-size image (
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Rao, K. Hanumantha, et al.
(författare)
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Size effect of the mode II fracture toughness of rock
- 1999
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Ingår i: Rock mechanics for industry. - Rotterdam : Balkema Publishers, A.A. / Taylor & Francis The Netherlands. - 9058091007 ; , s. 1117-1123
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Konferensbidrag (refereegranskat)abstract
- A new method, compression-shear test, has been developed for determining the mode II fracture toughness K (sub IIC) of rock. The effect of the specimen thickness B, the dimensionless notch length a/W as well as the notch inclination angle alpha on the determination of K (sub IIC) has been experimentally studied. The results show that the apparent mode II fracture toughness K (sub c) decreases as B and a/W increase and becomes constant when B> or =70 mm (i.e. cubic specimen) and a/W>0.5. The K (sub c) is almost independent of alpha in the range of 65 degrees -75 degrees . The constant K (sub c) is about 2-3 times that of mode I fracture toughness K (sub IC) and can be considered as the true mode II fracture toughness K (sub IIC) of rock.
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| 11. |
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| 12. |
- Wang, Yanmin, et al.
(författare)
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Magnetic aggregation in dispersions of mineral ultrafines
- 1995
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Ingår i: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 16:2, s. 137-154
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Tidskriftsartikel (refereegranskat)abstract
- Particle aggregation can be enhanced in two ways; (a) field-induced magnetic moment and (b) magnetic moment due to the remanent magnetisation. Investigation of the magnetic field-induced aggregation of hematite and chromite in aqueous suspension with the use of a laboratory scale electromagnetic solenoid related the aggregation process to particle size and external magnetic field in the natural pH value of the dispersions. This study have shown that hematite ultrafines in a well-dispersed slurry are selectively aggregated with sized magnetite in the absence of aggregating reagents, high shear rates or an external magnetic field.
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| 13. |
- Yang, Qixing, et al.
(författare)
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Effects of gas jet instability on refractory wear. A study by high-speed photography
- 1992
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Ingår i: Scandinavian journal of metallurgy. - 0371-0459 .- 1600-0692. ; 21:1, s. 15-26
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Tidskriftsartikel (refereegranskat)abstract
- To study influences of gas jet instability on tuyere refractory wear, gas injection was performed in an air-water system with a tuyere of 2 mm inner diameter. High-speed photography was used, with a framing rate of 8000 pictures per second, to film the tip region of a free and a half free tuyere. Characteristics of the cavity formed as a result of the jet instability were measured from the films, and the results were used in equations of bubble dynamics to calculate the pressure generated by the cavity motion. The film sequences show that as a result of the distortion of the gas-liquid interface, a throat in the gas jet is formed about 1.5D (tuyere i.d.) downstream of the tuyere tip. Radially moving gas starts to form an expanding cavity. The radius of the throat increases as it is pushed forward by the cavity expansion. With its radius reaching the maximum, the cavity stops growing. When the cavity collapses, bubble swarms are generated in the region near the tuyere. The cavity expands to 2D-4D (tuyere i.d.) within 1-15 ms. The maximum velocity of the expansion is about 10 m/s and acceleration ranges from 20 to 80 m/s2. The pressure calculated by using the cavity expansion data is in good agreement with the pressure measured at back-attack, which is around one half of the absolute pressure for the gas injection. This implies that the back-attack and cavity expansion are the same phenomenon. Passing the transition point of flow regimes the pressure increases very slowly as the injection rate increases. Occassionally, the cavity does not collapse immediately and it contracts after reaching the maximum radius. The cavity contraction generally takes longer than the expansion, with a velocity of about 2 m/s. The pressure reduction from the contraction is less than 0.1 bar which can not cause the formation of vapour bubbles in the liquid. By the cavity expansion, a liquid flow is set up which deforms and disintegrates gas bubbles nearby. At the moment of disintegration, liquid penetrates the concave side of the deformed bubble. The liquid flow may lead to an impact pressure of 30-90 bar in water and 210-630 bar in liquid steel. This pressure may cause refractory erosion with a pattern similar to that previously observed on H3BO3 disk surface. Besides the pitting erosion of the tuyere refractory, the influences of the jet instability on other factors of the refractory wear are also discussed.
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| 14. |
- Yang, Qixing, et al.
(författare)
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Erosion of refractory during gas injection : a cavitation based model
- 1990
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Ingår i: Scandinavian journal of metallurgy. - 0371-0459 .- 1600-0692. ; 19:3, s. 127-137
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Tidskriftsartikel (refereegranskat)abstract
- The problem of tuyere refractory wear has been studied in an air-water model. Erosion tests, with boric acid (H3BO3) disks as refractory simulators, and measurements of back-attack frequency were carried out. The erosion pattern showed two distinct features: isolated elliptical pits and a continuous irregular shear wear pattern. The influence of surface hardness and gas flow rate was investigated. Pitting was found most frequently on disks formed at the lowest pressure (10 tons), but for pressures greater than 20 tons, little difference was seen between disks. When the gas flow was in the bubbling regime, pitting was observed inside the region closest to the tuyere tip, with a maximum at the transition to jetting flow. Occasionally, pits could still be observed when the gas flow rate was rather high (NMa = 1.82). The irregular wear pattern appeared independent of disk surface properties, however sensitive to the gas flow rate. In the bubble flow regime, wear was seen only outside a certain radius, which corresponds to the radius of the bubbles. In the jetting regime, wear was also observed close to the tuyere. The disk weight loss showed a maximum in the bubbling-to-jetting transition region, where the back-attack frequency also reach a maximum. The results support the idea that cavitation erosion, through liquid microjet pitting, is the main mechanical wear agent. A model for the generation and collapse of cavitation bubbles is proposed. Applied to gas injection into liquid metals, the model suggests greater erosion due to higher cavitation intensity, but also indicates ways of reducing cavitation erosion of tuyere refractory.
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| 15. |
- Andersson, Henrik C.M., et al.
(författare)
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Creep crackgrowth in ex service weld metal of 0.5CrMoV
- 1999
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Ingår i: Cape 99.
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Konferensbidrag (refereegranskat)abstract
- Accurate assessment of the integrity of high temperature components will be of ever increasing importance. The reason for this is that many power plants have reached and exceeded their design life and the number of detected defects increases. This is accentuated by the improvement of the methods for non-destructive testing which means that more and smaller defects will be detected. The possibility to assess the influence of defects on the integrity of high temperature components, will be of vital importance to maintain safe and cost effective power plants. The aim of the present work is to increase the understanding of the influence of service exposure on the remaining life of components in a high temperature plant. The investigation aims to creep test exserviceweld material, 14MoV 6 3, from a Swedish power plant. Thematerial has been in service for a period of about 80 000 hours at atemperature of 530-540 °C and with a nominal hoop stress of 52MPa.Both uniaxial and compact tension creep tests have been performedat a temperature of 550 °C. The stress range used was between 130MPa and 170 MPa for the uniaxial creep tests. For the creep crack growth tests the reference stress was ranging between 122 MPa and146 MPa. A remaining life assessment according to the R5 procedure is included, where material data from the present experimental study is used. The analysis suggests that a defect or a crack with a depth of 2 mm and a length of 5 mm can be left unattended for a season of service under the condition that the service parameters are not changed. A comparison with the assessment of cracks, found in the same plant as the material for the experimental studies came from, and their known extension during service, is included. A parametric study where load level and type of initial defect/crack are varied is also included.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Ahlberg, E., et al.
(författare)
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The surface oxidation of pyrite in alkaline solution
- 1990
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Ingår i: Journal of Applied Electrochemistry. - 0021-891X .- 1572-8838. ; 20:6, s. 1033-1039
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Tidskriftsartikel (refereegranskat)abstract
- The collector-less flotation of pyrite has been studied by conventional techniques and is correlated to the electrochemical behaviour of pyrite in alkaline solution (1m NaClO4, pH 11). It was concluded that the initial oxidation of pyrite produces a hydrophobic sulphur rich surface together with hydrophilic iron hydroxide species. Also upon grinding, the surface is covered by hydrophilic species and therefore no significant flotation was obtained in the absence of a collector. However, collectorless flotation was readily obtained in an iron complexing solution like EDTA. This indicates that the remaining sulphur-rich layer is responsible for the floatability of pyrite under these conditions.
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Ayyala, Sekhar, et al.
(författare)
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Aggregate Characteristics in Coagulation and Flocculation
- 1993
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Ingår i: Mineral Processing and Extractive Metallurgy Review. - : Informa UK Limited. - 0882-7508 .- 1547-7401. ; 12:2-4, s. 165-184
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Tidskriftsartikel (refereegranskat)abstract
- Physical characteristics of mineral aggregates (such as density, size, shape, structure and strength) formed by either electrolytic coagulation or polymeric flocculation, need to be critically controlled by optimum conditioning in mineral processing. The present paper discusses the various experimental techniques used to determine these properties. In addition, physical and chemical factors that determine the rates of floe growth and which subsequently influence the floe morphology are summarised. This review also elucidates the hydrodynamic aspects of creeping flow and summarises the various settling velocity equations pertaining to the calcuation of floe density.
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| 26. |
- Ayyala, S, et al.
(författare)
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Effect of corrosion inhibitors on grinding and flotation of a lead-zinc ore
- 1993
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Ingår i: Minerals Engineering. - 0892-6875 .- 1872-9444. ; 6, s. 929-935
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Tidskriftsartikel (refereegranskat)abstract
- Grinding and flotation experiments on a Pb-Zn ore were carried out to evaluate : 1) wear of the grinding media both in the presence and absence of an inhibitor and 2) effect of the inhibitor on the flotation of Pb-Zn minerals. The percentage reduction in the wear of the grinding media was observed to be between 25-36%, depending on the type of the inhibitor and its critical concentration. The inhibitors used in the investigation were sodium sulphite, sodium nitrite, sodium chromate and sodium silicate. The results indicate that a specific corrosion inhibitor, for example sodium sulphite, may give better recoveries and grades in flotation but is not as efficient as sodium chromate in inhibiting the wear of the grinding media. Pulp solutions (after grinding) analysed for metal ion concentrations showed low Fe. Iron released into the solution as a result of corrosion reactions subsequently forms insoluble hydroxy complexes and may coat the mineral surfaces. Such hydrophilic coatings may adversely affect the floatabilities of minerals. The particle size analysis of the ground product has been carried out and the results are discussed.
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| 27. |
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| 28. |
- 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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| 29. |
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| 30. |
- Berglund, Gun
(författare)
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Pulp Chemistry in Sulphide Mineral Flotation
- 1991
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Ingår i: International Journal of Mineral Processing. - 0301-7516 .- 1879-3525. ; 33:1-4, s. 21-31
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Tidskriftsartikel (refereegranskat)abstract
- Variations in the oxidizing conditions of the pulp and their subsequent effects on flotation were examined for three types of natural sulphide ore, a complex pyrite ore, a sphalerite-galena ore and a chalcopyrite ore. Different gas mixtures ranging from pure nitrogen to pure oxygen were used to control the oxidizing conditions. The use of an oxygen rich flotation gas was found to be a suitable method for changing the oxidizing conditions and improving flotation under controlled conditions. The flotation results were correlated to the oxygen content and the redox potential, parameters which describe the pulp chemistry conditions.
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| 31. |
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| 32. |
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| 33. |
- Björkman, Bo, et al.
(författare)
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Dust forming mechanisms in the copper converting process
- 1996
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Ingår i: Second International Symposium on Extraction and Processing for the Treatment and Minimization of Wastes, 1996. - Warrendale, Pa : Minerals, Metals & Materials Society. - 0873393694 ; , s. 105-114
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Konferensbidrag (refereegranskat)abstract
- A controlled dust generation whereby the dust generated would be enriched with specific metals would considerably facilitate the possibilities of recovering metals from such dusts. A basic understanding of the dust forming mechanisms is of fundamental importance to achieve a controlled dust generation. The present study deals with dust formation in a copper converting process. Dust samples collected from various places in the gas cleaning system were characterised for chemical and mineralogical composition using chemical analysis as well as microprobe analysis. Thermodynamic calculations were used to predict the formation of chemically formed dust at various temperatures and amounts of leakage air to the gas system. The results show that a separation of mechanically formed dust, e.g. SiO sub 2 , Cu and chemically formed dust, e.g. Pb, Zn, As, Bi, could, to some extent, be obtained due to their different particle sizes. A selective condensation of Pb, Zn and As at a various temperatures could, according to thermodynamic calculations, be possible at high temperature. A selective condensation of metals requires an airtight gas cleaning system or a gas cleaning system with a limited amount of leakage air in order to maintain the desired temperature level.
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| 34. |
- Björkman, Bo, et al.
(författare)
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Kinetics of Impurity Elimination During Roasting
- 1994
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Ingår i: Extraction and processing for the treatment and minimization of wastes, 1994. - Warrendale, Pa : Minerals, Metals & Materials Society. - 0873392612 ; , s. 825-842
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Konferensbidrag (refereegranskat)abstract
- Four different arsenic containing dusts from the Boliden plant, Boliden Mineral AB, Sweden have been examined. A kinetic study of the arsenic elimination was performed in a laboratory scale roasting furnace for roasting furnace ESP dust and smelting furnace ESP dust. Characterisation and thermodynamic calculations were carried out to determine the mineralogy, and the stability of compounds in the dusts studied. The characterisation methods used were chemical analysis, X-ray diffraction analysis and microprobe analysis. It was found in the experiments that a high degree of As elimination was obtained for roasting furnace ESP dust and a low degree for smelting furnace ESP dust. Derived kinetic models are given. A prediction of the As-elimination for settling furnace dust and converter ventilation dust is presented
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| 35. |
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| 36. |
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| 37. |
- Björkman, Bo, et al.
(författare)
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Thermodynamic conditions for the reduction of dioxins during combustion of the organic parts contained in electronic wastes
- 1999
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Ingår i: REWAS '99. ; , s. 937-648
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Konferensbidrag (refereegranskat)abstract
- Electric and Electronic scrap contains about 30% plastics which are treated with halogenated flame retardants. During the combustion of these wastes, halogenated flame retardants can produce dibenzo-p-dioxins and dibenzo-furans. Their reduction can be performed by optimization of combustion parameters e.g. temperature in the combustion chamber, concentration of oxygen, temperature of flue gas at exit, residence time in the cooler, and HCl and H2O mixed in secondary air. The thermodynamic calculations show that, with an oxygen content of 0.1 mole, the total amount of dioxins/furans starts to reduce at 700°C and no formation of these isomers can be observed at 1000°C. However, these molecules are formed even at high temperature and the influence of chlorine on their reduction is negligible with an oxygen content of 1E-5 mole. On the other hand, the presence of SO2 in the gas mixture minimizes the dioxin emissions and the high concentration of water reduces the ratio of dioxins and furans in a given system
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| 38. |
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| 39. |
- Björkman, Bo, et al.
(författare)
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Waste reduction through process optimization and development
- 1996
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Ingår i: JOM. - 1047-4838 .- 1543-1851. ; 48:3, s. 45-49
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Tidskriftsartikel (refereegranskat)abstract
- In this article, the possibilities of optimizing metallurgical processes based on minimization for waste reduction and application requirements for the reuse of waste products are discussed together with the possibilities of treating existing waste in direct connection with the process involved. Some results from ongoing projects on controlled dust generation and an outline of an ongoing research program are also described.
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| 40. |
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| 41. |
- Bååth, Lars, 1948-
(författare)
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A method to simultaneously measuring the position of more than one surface in metallurgical processes
- 1997
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Patent (populärvet., debatt m.m.)abstract
- A method for measuring the position of at least one surface in a metallurgical process which includes the steps of providing a metallurgical melt, the metallurgical melt including at least a metal portion and a slag layer, providing a signal generator for generating signals at a plurality of frequencies over a frequency band, and providing an antenna for receiving the signals generated by the signal generator and for transmitting circularly polarized radio waves at the plurality of frequencies over the frequency band. The invention further includes the steps of disposing the antenna adjacent the metallurgical melt, transmitting the circularly polarized radio waves from the antenna toward the metallurgical melt, the circularly polarized radio waves being transmitted by the antenna at the plurality of frequencies over the frequency band, receiving reflected images of the transmitted radio waves through the antenna, the received reflected images of the transmitted radio waves having a substantially opposite circular polarization from the transmitted circularly polarized radio waves, determining a phase displacement between the transmitted radio waves and the received reflected images of the transmitted radio waves, transforming the determined phase displacement from a frequency to a time plane, and determining from the time plane transform a position of at least one surface of at least one of the metal portion and the slag layer.
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| 42. |
- Bäckman, Jonas, et al.
(författare)
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Influence of ingate system design on mechanical properties for a cast A1-10Si-0.38Mg alloy
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this work the influence of the ingate system design on the as-cast mechanical properties of an Al-10Si-0.38Mg alloy have been clarified. The Weibull distribution has been seen to describe the spread in mechanical properties very well. The Weibull modulus has therefore been used as a measure of the soundness of an ingate system. Different ingate systems were investigated, including: expanding systems, pressurised systems, systems with and without filter, systems with different designs of the connection between the downsprue and the runner, and systems with and without an additional pocket at the end of the runner. The modification index of the microstructure was also measured in order to investigate if the spread in data is more dependent on the modification index than on the ingate system design. The results showed that a high Weibull modulus is more dependent on the ingate system design than on the modification index of the microstructure. The ultimate tensile strength was not significantly affected by the ingate system design, while the fracture elongation seemed to be more dependent on the melt quality than on the ingate system design. The Weibull modulus indicates that expanding systems are better than pressurised systems, and that the use of a filter in the runner is very beneficial. An additional pocket at the end of the runner has no beneficial effect when using a filter. The connection between the downsprue and the runner should have a rounded bend and the change in cross-section between the downsprue and the runner should be chamfered and not sharp.
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| 43. |
- Chauhan, H. S., et al.
(författare)
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Direct- and inverse-photoemission investigations of the electronic structure of Cd(0001)
- 1993
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Ingår i: Physical Review B Condensed Matter. - : American Physical Society. - 0163-1829 .- 1095-3795. ; 48:7, s. 4729-4734
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Tidskriftsartikel (refereegranskat)abstract
- Photoemission and inverse angle-resolved photoemission spectra are presented for Cd(0001). The data are interpreted in terms of interband transitions, density-of-states effects, and excitations of surface states.
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| 44. |
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| 45. |
- Cheng, Y.F., et al.
(författare)
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TEM study of the early stages of the precipitation process in strip-cast Al3003 alloys
- 1992
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Ingår i: Journal of Materials Research. - 0884-2914. ; 7, s. 3235-3241
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Tidskriftsartikel (refereegranskat)abstract
- The precipitation behavior, especially the early nucleation stages, of the industrial strip-cast Al3003 alloys was investigated by using transmission electron microscopy (TEM). An icosahedral quasicrystalline phase was found as secondary particles in these strip-cast alloys after heat treatment for a few seconds. Three different nucleation paths are proposed based on the TEM observations. They have the same origin, viz. (Mn, Fe)-containing Mackay icosahedra, and are governed by the composition of alloys, especially the Mn and Si content.
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| 46. |
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| 47. |
- 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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| 48. |
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| 49. |
- de Leeuw, N.H., et al.
(författare)
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Modeling the competitive adsorption of water and methanoic acid on calcite and fluorite surfaces
- 1998
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 14:20, s. 5900-5906
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Tidskriftsartikel (refereegranskat)abstract
- Atomistic simulation techniques were used to investigate the interaction between the minerals calcite and fluorite with water and methanoic acid. The relative adsorption energies suggest that methanoic acid preferentially adsorbs onto fluorite surfaces, while adsorption of water is energetically preferred over methanoic acid on the calcite cleavage plane in agreement with experiment. The coverage and configuration of adsorbed methanoic acid on the surfaces depends largely on lattice spacing between the cations, and bridging between surface calcium atoms is highly favored. These findings have given an insight into interactions at the atomic level which indicate that modeling techniques should be capable of predicting adsorption behavior and designing collector molecules, which is of central importance to the mineral processing technique of flotation
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| 50. |
- 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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