Fluid bed roasting

Several important applications of fluid beds exist outside the petroleum industry. Fluid bed roasting of pyritic ores is widely used in the metallurgical industry. Calcination of lime is a commercial process. There are also fluidization processes for various nuclear processing steps. 

Zinc sulphide ore For fluid bed roasting of 4 x 30 mesh pellets... 

Saha, D., Becker, J. S., and Gluns, L., Oxygen-Enhanced Fluid Bed Roasting, Productivity and Technology in the Metals Industries, TMS, 1989. 

Thoumsin, F.J. and Coussement, R. (1964) Fluid-Bed Roasting Reactions of Copper and Cobalt Sulphide Concentrates Journal of Metals 831-834. 

Bunk S. Fluid-bed roasting advances. Randol Gold Forum, pp 173-174, September 1990. 

For environmental and economic reasons, the eady practice of roasting zinc sulfide and discharging the sulfur dioxide to the atmosphere gave way to plants where the sulfur dioxide is converted to sulfuric acid. Desulfurization takes place while the ore particles are suspended in hot gases. Called flash-and fluid-bed roasters, these processes are described below. Some plants use combinations of roasters and sintering for desulfurization. 

St. Joe Minerals Corporation uses a fluid-bed roaster to finish the roasting at 950°C of material that has been deleaded in a modified multiple-hearth furnace operated with insufficient oxidation (34). First, sulfur is reduced from 31 to 22% and lead from 0.5 to 0.013%. Somewhat aggregated, the product is hammer-milled before final roasting. Half of the calcined product is bed overflow and special hot cyclones before the boiler remove the other half total sulfur is ca 1.5%. Boiler and precipitator dusts are higher in sulfur, lead, etc, and are separated. 

The ziac concentrate is first roasted ia a fluid-bed roaster to convert the ziac sulfide to the oxide and a small amount of sulfate. Normally, roasting is carried out with an excess of oxygen below 1000°C so that comparatively Htfle cadmium is eliminated from the calciaed material ia this operation (3). Siace the advent of the Imperial Smelting Ziac Furnace, the preliminary roasting processes for ziac and ziac-lead concentrates result ia cadmium recovery as precipitates from solution or as cadmium—lead fume, respectively, as shown ia Figure 1. 

CFB (2) [Circulating fluid bed] A metallurgical roasting process, developed originally for the aluminum industry and now used for many other nonferrous ores. Offered by Lurgi. 

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