Flotation column

The actual flotation phenomenon occurs in flotation cells usually arranged in batteries (12) and in industrial plants and individual cells can be any size from a few to 30 m in volume. Column cells have become popular, particularly in the separation of very fine particles in the minerals industry and coUoidal precipitates in environmental appHcations. Such cells can vary from 3 to 9 m in height and have circular or rectangular cross sections of 0.3 to 1.5 m wide. They essentially simulate a number of conventional cells stacked up on top of one another (Fig. 3). Microbubble flotation is a variant of column flotation, where gas bubbles are consistently in the range of 10—50 p.m. 

The KEN-FLOTE column (11) is one of several column flotation processes based on a countercurrent principle. The feed slurry containing reagents is iatroduced iato the column just below the froth zone. Air is iujected at the bottom of the column via an air sparger. Wash water is sprayed within the froth zone to reject the entrained impurities from the froth. Test results on this column iadicate that a 6% ash product coal having a combustible-recovery of 75—80% can be obtained. A 70—80% pyrite reduction is also claimed. Figure 2 shows the operation of such a column. 

Another modification is the use of microbubble column flotation (13). In this process, smaller bubbles are generated to enhance the recovery of micrometer-sized particles. A countercurrent flow of feed slurry is also used to further enhance the bubble—particle attachment. The process is capable of produciug ultraclean coals containing less than 0.8% ash. 

The Expanding World of Chemical Engineering, Edited by John Garside and Shintaro Furusaki Column Flotation Processes, Designs and Practices, Julius B. Rubinstein Transport and Chemical Rate Phenomena, Nickolas J. Themelis... 

Finch, J. A. and Dobby, G. S. Column Flotation. (Pergamon Press, Oxford, 1990)... 

Miner. Process Extra. Metall. Rev., 11 187-210 Yarar, B., Haydon, B. C., Kitchener, J. A., 1969. Electrochemistry of the galena-diethyldithio carbamate-oxygen flotation system. Trans. Instn. Min. Metall. Sec.C, 78 C181 - C184 Yekeler Meftuni, Sonmez Ibrahim, 1997. Effect of the hydrophobic fraction and particle size in the collectorless column flotation kinetics. Colloids and Surfaces A Physicochemical and Engineering, 121(1) 9-13... 

Table 5 Column flotation testing of sample A using S-8706D and S-8706...

Finch, J.A. Dobby, G.S. Column Flotation, Pergamon Press Oxford, 1990. 

The influence of small amounts of PVC degrading in PET scrap during reprocessing has been studied (371). An aqueous column flotation technique, utilising pH level and surfactants, has been proposed (311). A continuous thermal separation system, for removal of trace PVC, has also been described (204). Triboelectrostatic separation, based on cyclones, fluidised beds or rotating tubes, has also separated five commonly used plastics, including PVC (30). 

SEPARATION OF PETP FROM PVC USING COLUMN FLOTATION... 

A mixed granulate produced from PETP and PVC postconsumer bottles has been separated using the technology of column flotation. The aqueous separation medium pH and surfactant concentration were optimised with respect to separation efficiency, using Response Surface Methods. The study has shown that column flotation could be used to give close to 100% separation of PVC from PETP in a single operation. 15 refs. 

O. D. Chuk, V. Ciribeni, and L. V. Gutierrez, Froth collapse in column flotation a prevention method using froth density estimation and fuzzy expert systems. Minerals Engineering 18(5) (2005). 

Coffin Vemau, L., Column Flotation of Gaspe., 14th Int. Miner. Process. Technol. Toronto,... 

Miranda EA, Berglund KA (1993) Evaluation of column flotation in the downstream processing of fermentation products recovery of a genetically engineered -amylase. Biotechnol Prog 9 411-420... 

Davis, V.L. Jr. 1993. Implementation of microceU column flotation for processing fine coal. In Coal Prep 93, Proceedings from the tenth International Coal Preparation Exhibition and Conference. Lexington, KT, May, pp. 239-249. 

Luttrell, G.H. and Yoon, R.H. 1994. Commercialization of the microcell column flotation technology. In Proceedings. Eleventh Pittsburgh Coal Conference. Pittsburgh, PA, September, pp. 1503-1508. 

Column flotation A precombustion coal cleaning technology in which coal particles attach to air bubbles rising in a vertical column—the coal is then removed at the top of the column. 

An advanced froth flotation technique called columm flotation has been shown to be superior in obtaining a low-ash clean coal with high recovery of combustible. It has been proved effective in recovering ultra-fine (minus 74 microns) coal. A schematic diagram of the column flotation process is shown in Fig. 17.13. 

Parekh, B. K., Groppo, J. G., Stotts, W. F., and Bland, A. E., Recovery of Fine Coal from Preparation Plant Refuse Using Column Flotation, Column Flotation 88, K.V.S. Society (Eds.), Society of Mining Engineers, Inc., Littleton, CO, 1988. 

Uses Mineral processing surfactant frother for flotation operations where foam builds up exc. for column flotation Properties Liq. 

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