Application of Microwave Technique for Dehydration of Sludge Generated in a Stainless Steel Plant

Iwasaki, Kazuo; Mashiko, Ken Ichi; Saito, Yoshitami; Yoshikawa, Noboru; Todoroki, Hidekazu; Shoji, Tetsuya

doi:10.2355/isijinternational.49.596

Cited by 8 publications

(13 citation statements)

References 11 publications

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“…One of the reasons why microwave manner is more beneficial is attributed to the fact that heat is directly input center of the powdery specimen while heat is input from outside by an electric furnace. This behavior observed in the previous study 16) is shown in Fig. 1 where red region is hematite formed as a result of decomposition of goethite.…”

Section: Introductionsupporting

confidence: 74%

“…Basically the set-up of the specimen contained in the crucible was the same as in the previous study. 16) Thus the detailed explanation is omitted here. The specimens were heated from a room temperature to the aimed temperatures of 200, 300, 400 and 500°C controlled by PID flowing nitrogen gas with 500 mL/minute.…”

Section: Effect Of Quantity and Apparent Density On Dehy-mentioning

confidence: 99%

“…It was estimated that specimen neighbored by C particles partially attained high temperature over 1 200°C because C can be induced by microwave. Dehydration of sludge generated in a stainless steel plant 16) was subsequently tried resulting in successful drying. The sludge was proved not to be in the form of hydroxide but to contain adhered water.…”

Section: Introductionmentioning

confidence: 99%

“…Followed by the previous study, [13][14][15][16] this study basically aims at understanding what the optimum ratio of goethite to graphite, to which microwave induces, is to decompose goethite FeO(OH) to hematite Fe2O3. This trial mainly focuses on the pretreatment of poor iron ores involving limonite or pisolite as well as that of sludge in which hydroxides are dominant.…”

Section: Introductionmentioning

confidence: 99%

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Dehydration Behavior of Goethite Blended with Graphite by Microwave Heating

et al. 2011

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In ironmaking and steelmaking processes, dehydration of wet substances and minerals combined by H2O are often recognized to be a key to stable practices. This study aims at understanding dehydration behavior of goethite blended with graphite by microwave treatment simulating drying wet sludge and poor iron ore with combined water.Firstly blend specimens with various conditions, powdery or pelletized, were heated by microwave apparatus. Dehydration rate of goethite increased with increasing temperature. Denser specimen of pelletized was confirmed to be less effective to heat up the whole part. It was found that surplus addition of graphite decreased efficiency in dehydration rate. Thus, it was estimated that a specimen with smaller amount of graphite, whose blend ratio of FeO(OH):C was 1:1, had sufficiently larger distance between graphite particles, through which microwaves could adequately penetrate into the core of the specimen. To prove this hypothesis, Network Analyzer helped evaluate penetration depth of microwave by the measurement of permittivity. The measured results showed that penetration depth decreased with increasing apparent density consistently with the heating behavior by microwave treatment. At the blend ratio of 1:2 of FeO(OH):C, however, the specimen was estimated to behave as if it was under percolation.

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Section: Introductionsupporting

confidence: 74%

Section: Effect Of Quantity and Apparent Density On Dehy-mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dehydration Behavior of Goethite Blended with Graphite by Microwave Heating

et al. 2011

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“…It can be seen that the wave length became shorter as an increase of average ε'. (Iwasaki et al 2009). It was observed that penetration distance decreased as the increase of graphite fraction and the degree of compression of the powder mixture.…”

Section: Dielectric Heatingmentioning

confidence: 99%