Title

REACTION BEHAVIOR OF SINGLE SLURRY DROPLET OF1 ZINC CONCENTRATE IN HIGH TEMPERATURE GAS FLOW

REACTION BEHAVIOR OF SINGLE SLURRY DROPLET OF1 ZINC CONCENTRATE IN HIGH TEMPERATURE GAS FLOW

Authorship

Nogam, Hiroshi; Chiba, Masaki; Kitamura, Shin-ya

Nogam, Hiroshi

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Chiba, Masaki

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Kitamura, Shin-ya

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DOI

10.5151/5463-5463-0006

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Abstract

One of the measure route to produced metallic zinc from natural zinc recources is hydrometallurgical path. In this route roasting process of zinc concentrate in which zinc sulfide is converted to zinc oxide is included. Recent change in supply of zinc resources causes operation troubles in this process. To deal with such troubles, it is necessary to clarify the reaction behavior of zinc concentrate slurry. This study investigated the behavior of single droplet of zinc concentrate slurry in high temperature gas flow through experiments and numerical simulations. A slurry droplet of zinc concentrate is suspended by a thin thermocouple and inserted into high temperature gas flow which had uniform velocity. The changes in appearance and temperature of the droplet were recorded. The observation results clarified that the roasting process of the slurry droplet consisted of preheating period, drying period and heating/reaction period. Heat and mass balance equations were applied to each period to analyze temperature variations of the slurry droplets under no oxygen condition. The results showed that the drying period was farther divided into constant drying rate period and decreasing drying rate period. Numerical analyses of heat balance equation on a slurry droplet that took into account heat exchange with gas flow, moisture evaporation and reaction heat were carried out to estimate the temperature variation of the slurry droplet under oxidizing condition. Apparent reaction rate constant used in the analyses was obtained from the difference of temperature variation in no oxygen and oxidizing conditions. The mathematical simulation successfully reproduced the temperature variation obtained in the experiments under various conditions.

One of the measure route to produced metallic zinc from natural zinc recources is hydrometallurgical path. In this route roasting process of zinc concentrate in which zinc sulfide is converted to zinc oxide is included. Recent change in supply of zinc resources causes operation troubles in this process. To deal with such troubles, it is necessary to clarify the reaction behavior of zinc concentrate slurry. This study investigated the behavior of single droplet of zinc concentrate slurry in high temperature gas flow through experiments and numerical simulations. A slurry droplet of zinc concentrate is suspended by a thin thermocouple and inserted into high temperature gas flow which had uniform velocity. The changes in appearance and temperature of the droplet were recorded. The observation results clarified that the roasting process of the slurry droplet consisted of preheating period, drying period and heating/reaction period. Heat and mass balance equations were applied to each period to analyze temperature variations of the slurry droplets under no oxygen condition. The results showed that the drying period was farther divided into constant drying rate period and decreasing drying rate period. Numerical analyses of heat balance equation on a slurry droplet that took into account heat exchange with gas flow, moisture evaporation and reaction heat were carried out to estimate the temperature variation of the slurry droplet under oxidizing condition. Apparent reaction rate constant used in the analyses was obtained from the difference of temperature variation in no oxygen and oxidizing conditions. The mathematical simulation successfully reproduced the temperature variation obtained in the experiments under various conditions.

Keywords

Zinc concentrate; Roasting; Single slurry droplet.

Zinc concentrate; Roasting; Single slurry droplet.