High Temperature Treatment of Selected Iron Rich Bauxite Ores to Produce Calcium Aluminate Slags

The Pedersen process is a method to produce alumina from Al-containing sources, and it is a more material-efficient method than the current commercial Bayer process, since the formation of bauxite residue (red mud) is avoided, and the bauxite can be holistically consumed. The smelting reduction (SR) part of the Pedersen process yields pig iron and a calcium aluminate slag, and the latter is a feedstock material for alumina extraction via alkaline leaching. In the present study, three different bauxite ores (Greek, Turkish and Jamaican) were smelted with lime to ease the process and control the slag chemistry and coke for the carbothermic reduction of iron oxides. The slags produced were analyzed with XRD, XRF, and EPMA to identify the phases and chemical compositions. According to the results, the slags composed of Al-containing leachable phases. Moreover, it is shown that the amount and distribution of both the leachable and non-leachable phases in the slags depend on the ore chemical composition. The results are discussed regarding the characteristics and potential leachability of the slags. Standard leaching tests were performed to examine the actual leachability.

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THE INFLUENCE OF HUMIDITY ON THE RESPONSE OF SPARTAN APPLES TO PRE-STORAGE HIGH TEMPERATURE TREATMENT

Canadian Journal of Plant Science ◽

10.4141/cjps78-169 ◽

1978 ◽

Vol 58 (4) ◽

pp. 1111-1113 ◽

Cited By ~ 2

Author(s):

P. D. LIDSTER ◽

S. W. PORRITT

Keyword(s):

Weight Loss ◽

High Temperature ◽

Relative Humidity ◽

Treatment Period ◽

Titratable Acidity ◽

Temperature Treatment ◽

Soluble Solids ◽

High Temperature Treatment ◽

Reduced Rate ◽

And Control

A reduced rate of softening during 7 mo storage at −0.6 °C and control of breakdown that resulted from pre-storage heating of Spartan apples was not dependent on the relative humidity (RH) during the high temperature period. Weight loss during the 4 days at 38 °C and 95–100% RH was 0.23 and 1.97% at 5–10% RH. Decay was controlled more effectively at the higher level of humidity. Changes in soluble solids and titratable acidity were not affected by RH during the treatment period.

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High temperature treatment on the eggs of the mosquito, Culex quinquefasciatus Say and its effects on the subsequent stages developed therefrom

Journal of the Asiatic Society of Bangladesh Science ◽

10.3329/jasbs.v39i2.17864 ◽

2014 ◽

Vol 39 (2) ◽

pp. 247-257 ◽

Cited By ~ 2

Author(s):

Humayun Reza Khan ◽

Md Mosarraf Hossain

Keyword(s):

High Temperature ◽

Culex Quinquefasciatus ◽

Room Temperature ◽

Head Capsule ◽

Temperature Treatment ◽

High Temperature Treatment ◽

Control Room ◽

Egg Hatching ◽

Mean Diameter ◽

And Control

The eggs of Culex quinquefasciatus Say (Diptera: Culicidae) were exposed to 40oC for different exposure periods (viz. half an hour, one, two and four hours) and control (room temperature, 28±6oC); the percentage of egg hatching ranged from 74.14 to 96.33 (F=215.593, P<0.05), larval mortalities were from 24.52 to 0.00% (F=73.287, P<0.05), pupal mortalities ranged from 10.2 to16.71% (F=34.056, P<0.05), mean larval periods ranged from 127.9 to 155.3 hours (F=124.002, P<0.05), mean pupal periods ranged from 30.5 to 36.1 hours (F=10.531, P<0.05), lengths of 2nd instar ranged from 3.82 to 4.67 mm (F=16.50, P<0.05), lengths of 3rd instar ranged from 6.195 to 7.195 mm (F=7.558, P<0.05), lengths of 4th instar ranged from 7.395 to 8.025 mm (F=3.961, P<0.05), mean diameter of the head capsule of 1st instar larvae was 0.316 to 0.384 mm (F=8.308, P<0.05), that of 2nd instar larvae was 0.395 to 0.468 mm (F=4.953, P<0.05), that of 3rd instar larvae was 0.652 to 0.71 mm (F=2.629, P>0.05), that of 4th instar larvae was 0.806 to 0.91 mm (F= 13.871, P<0.05), length of the cephalothorax of pupae ranged from 1.862 to 2.062 mm (F=0.662, P>0.05), body length of male adults ranged from 3.41 to 3.58 mm (F=0.59, P>0.05), and that of female ranged from 3.75 to 4.09 mm (F=1.98, P>0.05), mean egg- rafts laid per female ranged from 1.4 to 2.0 and mean numbers of eggs per raft were 230 to 260. DOI: http://dx.doi.org/10.3329/jasbs.v39i2.17864 J. Asiat. Soc. Bangladesh, Sci. 39(2): 247-257, December 2013

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The Utilization of Bauxite Residue with a Calcite-Rich Bauxite Ore in the Pedersen Process for Iron and Alumina Extraction

Metallurgical and Materials Transactions B ◽

10.1007/s11663-021-02086-w ◽

2021 ◽

Author(s):

Adamantia Lazou ◽

Casper Van Der Eijk ◽

Kai Tang ◽

Efthymios Balomenos ◽

Leiv Kolbeinsen ◽

...

Keyword(s):

Calcium Aluminate ◽

Bauxite Residue ◽

Reduction Process ◽

Analytical Techniques ◽

Pig Iron ◽

Mass Ratio ◽

Smelting Reduction ◽

Bauxite Ore ◽

Metal Phases ◽

Alumina Recovery

AbstractMetallurgical grade alumina is produced worldwide through the well-known Bayer process, which unavoidably generates bauxite residue (BR, also known as red mud) in almost equal amounts to alumina. This study aims the valorization of BR through a smelting-reduction process to obtain calcium aluminate slags that can be a proper feed for alumina recovery via the Pedersen process. It investigates the thermodynamics and characteristics of the slags and pig iron produced from mixtures of BR, a bauxite beneficiation byproduct, and lime. In this context, the evolution of the different phases in the slags is studied with advanced analytical techniques and thermodynamic calculations. According to the results, a CaO/Al2O3 mass ratio within 1.3 to 1.4 in the slags can yield more Al2O3-containing leachable phases, such as CaO·Al2O3 and 12CaO·7Al2O3. The cooling dictates the amount and the characteristics of these phases, and the slower cooling rate yields improved slag characteristics. The distribution of the elements between the slag and metal phases shows that iron is separated, and the majority of the P, Cr, Ni, and V are distributed in the produced pig iron, while S, Ti, and Si are mostly concentrated in the slags.

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