Bauxite Enrichment by Microwave-Magnetising Roasting Using Sawdust as Reducing Agent
Grace Ofori-Sarpong,
Charles Ebenezer Abbey,
Richmond Komla Asamoah,
Richard Kwasi Amankwah
Issue:
Volume 2, Issue 5, September 2014
Pages:
59-64
Received:
8 August 2014
Accepted:
22 August 2014
Published:
10 September 2014
Abstract: As high grade bauxite is getting depleted in several parts of the world, bauxite with high iron content is becoming increasingly important, and this trend has called for studies into the reduction of iron in bauxite. This study investigated the use of microwave energy in the magnetising roasting of high-iron bauxite using sawdust as reducing agent. Mineralogical studies revealed gibbsite and goethite as the main constituents of bauxite. The sawdust utilised had a fixed carbon content of 7.2% and ash, 1.7%. Microwave heating responses of bauxite and sawdust were determined as a function of mass and time, and both materials proved to be active microwave absorbers as they heated rapidly. Magnetising roasting of the bauxite sample was conducted with 20-40% sawdust at temperatures between 870oC and 880oC. After magnetic separation, the major phase in the magnetic fraction was magnetite, while gibbsite and boehmite were the major phases in the non-magnetic fraction. The alumina content of the non-magnetic fraction increased to 87.5% from an as-received sample grade of 53.6%. The use of sawdust in this manner satisfies a dual role of environmental clean-up and bauxite enrichment.
Abstract: As high grade bauxite is getting depleted in several parts of the world, bauxite with high iron content is becoming increasingly important, and this trend has called for studies into the reduction of iron in bauxite. This study investigated the use of microwave energy in the magnetising roasting of high-iron bauxite using sawdust as reducing agent....
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Numerical Investigation of Heat Transfer in 4-Pass Fire-Tube Boiler
Ahmed Rahmani,
Soumia Trabelsi
Issue:
Volume 2, Issue 5, September 2014
Pages:
65-70
Received:
7 September 2014
Accepted:
15 September 2014
Published:
30 September 2014
Abstract: In this paper, the heat transfer in 4-pass 500HP fire-tube steam boiler is numerically investigated. A calculation program is carried out in order to simulate the heat transfer characteristics between the hot gases and the boiler tube internal walls. Especially, the heat flux densities and the corresponding wall temperatures for different operating conditions. On these surfaces, an energy balance is established taking into account the radiation and the convection heat transfer. The model validation consists in comparing the predicted outlet gas temperature with the operating data of the PFTA 500HP fire-tube boiler for several steady-state conditions. The comparison shows that the calculation results are in good agreement with the boiler operating data. Furthermore, a sensitivity study has been carried out to investigate the operating pressure effect on the boiler thermal performances.
Abstract: In this paper, the heat transfer in 4-pass 500HP fire-tube steam boiler is numerically investigated. A calculation program is carried out in order to simulate the heat transfer characteristics between the hot gases and the boiler tube internal walls. Especially, the heat flux densities and the corresponding wall temperatures for different operating...
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