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F. Durao etat. / The European Journal of Minerał Processing and Environmental Protection Vol.4, No.3, 1303-0868, 2004, pp. 272-281

Z type clay, with much higher iron and titanium contents than V tyjDe clay, can be easily processed in terms of iron minerals but not in terms of titanium minerals. It could be recovered morę than 80% of the feed in the processed clay (a mixture of the hydrocyclone overflow (OFh) with the non floated materiał (UFf)) with a FezOj grade of 4.3%. It was possible to reject morę than 20% of FezCh.

4. CONCLUSIONS

The objective of this study was to process two raw clays from important deposits in Spain with high iron/titanium contents and very fine grain size. The industrial objective was to obtain an iron/titanium grade bellow 2%. This objective was a challenging one.

Although the proposed target was not completely accomplished. a reduction of the content in colouring elements could be achieved. In what concerns Z type clay. a raw clay with almost 6% in Fe2C>3 and 80% of its mass finer than 10nm, the best results were achieved through a combination of size separation by screening and hydrocycloning, followed by froth flotation of the iron/titanium bearing minerals of the underflow products by using sulfonate based collectors in an acidic Circuit. The finał product is a mixture of the non floated product with the hydrocycloning overflow product. A 1.5% decrease in Fe203 grade was achieved in a product that represents 83% in weight of the raw clay.

V type clay. with a grade in Fe2C>3 of almost 4%. being 80% of its mass finer than 5nm, could not be upgraded by froth flotation. However, morę than 40% by weight of the iron minerals could be removed with a simple fine size separation flow sheet, although the Fe₂03 content of the finał product could not be decreased to less than 2.3%.

ACNOWLEDGEMENTS

This study was performed within the scope of the European Project DGXII N^fl BE-96-3700, “Controlled Processing for Ceramic Pastes Components”, under the financial support of the Brite-Euram III Program. The authors wish to thank the European Comission and the partners of the proJect, especially Minera Sabater S. L., for their permission to publish this paper.

NOMENCLATURE

Subscripts_Superscripts

OF - Overflow,	H - Hydrocyclone	1 - 1⁵¹ step
Oversize, Floated	F - Flotation	2 - 2^nd step
UF - Underflow,	S - Screen	3 - 3^,d step
Undersize, Unfloated	C - Classification (spiral)

REFERENCES

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Durao. F.O., Cortez. L., Carvalho, M.T., Setas Pires, C, Felicio, A., Rodrigues, I., Lourenęo, R., Tareco, G, Brito, G., Controlled processing of raw materials for ceramic pastes components. Proceedings of 2 lst IMPC, 2000, Romę, Italy, Cl 1. pp. 32-39.

Finch, J.A. and Dobby, G.S., Column Flotation, 1990. Pergamon Press. 180 p.

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