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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

Non floated product

FeiOj Grade (%)

Figurę 9. Washability and grade-recovery curves - flotation of Z type clay

The very fine fraction of the raw clay, amounting almost 50%, is very rich in iron and the overflow of the 2^nd hydrocyclone increases significantly the grade in iron of the product Processed Clay (OF_h²+UF_f).

Although not satisfying yet the targets (to reduce the iron/titanium grade to a vaiue under 2%), the results of the bench flotation tests were encouraging, as it was possible to reduce about 1% in the iron grade, which represents a considerable amount of materiał.

3.2. Pilot plant tests

The best results, achieved with the flow sheets depicted in Figs. 3 and 4, and by using the operational conditions shown in Tables 4 and 5, are presented in Tables 8 and 9, respectively, for V and Z type clays.

Table 8

Best results of Pilot plant tests - V type clay

	Wt(%)			Assay:	s(%)					Distribution (%)
		SiOz	ai2o3	KzO	NazO	Fe203	TiOz	SiOz	AlzOj	KzO	NazO	Fe;05	TiOz
Feeci	100.0	57.46	23.76	2.64	0.18	3.53	1.01	100.00	100.00	100.00	100.00	100.00	100.00
OFs	3.7	57.20	22.30	2.39	0.17	6.72	0.93	3.68	3.47	3.35	3.50	7.04	3.41
UFS	96.3	57.47	23.82	2.65	0.18	3.4 1	1.01	96.32	96.53	96.65	96.49	92.96	96.59
OFh'	68.3	53.00	21.55	2.32	0.27	2.46	0.66	63.00	61.93	60.1 1	42.73	47.57	44.82
UFh'	28.0	68.37	29.36	3.44	0.14	5.72	1.87	33.32	34.59	36.54	53.76	45.38	51.77
UF„^2	8.6	65.50	17.00	2.14	0.15	3.70	0.96	9.80	6.15	6.97	7.44	9.01	8.17
Processed	59.7	51.20	22.20	2.35	0.14	2.28	0.62	53.20	55.78	53.14	46.32	38.56	36.65

Table 9 Best results of Pilot plant			tests	Z type clay
	Wt(%)			Assays (%)							Distribution (%)
		SiO;	Al,O,	K,0	Na,0		Fe,0,	TiO,	SiO,	AlzO,	K,0	Na,0	FezO,	TiO,
Feed	10.0	66.80	15.32	1.04	C	J9	5.79	1.36	100.00	100.00	100.00	100.00	100.00	100.00
OFs	13.0	60.10	1 1.40	0.76	c	36	15.76	1.20	1 1.70	9.68	9.51	8.23	35.39	1 1.50
UFS	87.0	67.80	15.90	1.08	c	10	4.30	1.38	88.30	90.32	90.49	91.77	64.61	88.50
OFc	85.8	68.30	15.60	1.08	c	11	4.29	1.38	87.73	87.40	89.24	99.56	63.57	87.28
UF,	1.2	52.70	7.50	0.39	c	30	21.87	0.91	0.95	0.59	0.45	0.00	4.53	0.80
OFh	64.8	62.30	19.70	1.39	c	11	4.48	1.47	60.44	83.35	86.74	75.19	50.14	70.22
UFh	21.0	77.86	1.76	1.03	c	32	2.75	0.81	24.48	2.41	20.83	4.43	9.97	12.54
OFf	2.5	73.30	6.30	0.49	c	34	6.13	3.95	2.74	1.03	1.18	8.97	2.65	7.28
UFf Processed	18.5	84.95	1.00	0.30	0	02	3.69	0.90	23.53	1.21	5.34	3.90	11.79	12.27
Clay	83.3	67.33	15.55	1.15	0.09		4.30	1.34	83.96	84.56	92.09	79.09	61.93	82.49

(OF„+ UF_f)

In what concerns V type clay the results, although not attaining the target values, could be considered as sufficient. The processed clay (OF_H²), constituting 60% in weight of the raw clay, presents 2.28% grade in Fe₂0₃ and 0.26% in TiOz. Almost 50% of the Fe₂0₃ could be rejected.

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