Impact of Pyrite Textures Prevalence on Flotation Performance in Mount Isa Copper Orebodies

Figures & data

Figure 1. Core photographs showing coarse-grained and fine-grained pyrite macro textures. Annotations: pyrite (py), shale (shale), dolomite (Dol), quartz (qz).

Table 1. Description of selected ore samples.

Orebody	Description	Sample ID
OD1	Ore rich in chalcopyrite, in combination with coarse-grained pyrite	OD1-CGP
OD1	Ore poor in chalcopyrite, in combination with finely disseminated pyrite grains	OD1-FGP
OD1	Ore rich in chalcopyrite, in combination with finely disseminated pyrite, occurring in a high alteration “leached” zone	OD1-Leached
OD2	Ore poor in chalcopyrite, in combination with finely disseminated and “framboidal” pyrite grains	OD2-FGP
OD2	Ore rich in chalcopyrite, in combination with coarse-grained pyrite	OD2-CGP

Table 2. Chemical composition of selected ore samples.

Sample ID	Cu%	Fe%	S%	Si%	Ca%	Al %
OD1-CGP	2.39	7.97	4.16	12.3	12.9	0.54
OD1-FGP	1.52	13.0	10.8	16.3	7.22	1.36
OD1-Leached	1.88	9.48	7.67	30.9	0.54	1.66
OD2-FGP	1.22	16.0	15.4	14.2	6.76	1.46
OD2-CGP	3.28	9.86	7.56	15.4	9.54	0.84

Figure 2. Pyrite (py) texture classes evaluated in this study.

Figure 3. BSE image and mineral map showing the main minerals present in the samples. Sample OD1-FGP. Deleterious groups tetrahedrite, enargite and arsenopyrite.

Figure 4. (a) Original BSE Image. (b) Tiled imaged. Yellow shows tiles classified by hand. Pink shows pyrite (Jefferson et al. 2023).

Table 3. Analytical settings for synchrotron X-ray fluorescence microscopy.

Sample	Region of interest	Scan area [mm]	Pixel size [µm]	Incident beam energy [keV]	Dwell time [ms]	SSA opening [μm]
OD2-FGP	10	33.3x12.2	20	18	2.50	9
OD2-FGP	10A	5.3x3.78	2	18	0.67	9
OD2-FGP	10B	0.7x0.47	1	18	2.00	9
OD1-FGP	8	34x17.55	20	18	2.50	9
OD1-FGP	8A	5.54x4.18	2	18	0.67	9
OD1-FGP	8B	0.77x0.55	1	18	2.00	9

Table 4. Flotation test results.

Sample ID	Head Grade (calculated)		Concentrate Grade (3min)		Recoveries (3 min)
	Chalcopyrite	Pyrite	Chalcopyrite	Pyrite	Chalcopyrite	Pyrite
OD1-CGP	6.66 ± 0.6	3.66 ± 0.3	10 ± 0.6	25.5 ± 4.3	1.23 ± 0.4	5.68 ± 0.7
OD1-FGP	3.92 ± 0.2	16.7 ± 0.8	3.28 ± 0.1	71.8 ± 1.9	2.56 ± 0.5	8.47 ± 1.6
OD1-Leached	5.71 ± 0.3	10.2 ± 1.2	8.64 ± 1.8	41.7 ± 2.1	3.84 ± 1.3	6.41 ± 0.7
OD2-FGP	4.01 ± 0.4	27.1 ± 0.7	1.31 ± 0.2	80 ± 1.8	1.35 ± 0.1	9.26 ± 0.2
OD2-CGP	9.53 ± 0.1	8.75 ± 0.2	6.39 ± 0.5	47.6 ± 2.7	0.56 ± 0.1	2.04 ± 0.9

Figure 5. Entrainment and true flotation recoveries of (a) chalcopyrite and (b) pyrite. Adapted from Yenial-Arslan et al. (2023).

Table 5. Pyrite texture prevalence estimates.

Samples		OD1-CGP	OD1-FGP	OD1-Leached	OD2-FGP	OD2-CGP
Area, px	Area Py A (px)	1,026,475	1,893,426	1,482,646	3,194,125	1,193,163
	Area Py B	83,232	1,374,991	1,412,255	4,525,845	705,261
	Area Py C (px)	427,153	6,828,058	1,334,740	4,709,116	725,292
	Area Py D (px)	4,422	54,087	13,208	25,266	8,175
	Total A Py	1,543,163	10,189,694	4,244,631	12,506,320	2,655,790
	A Other Sulfides	2,516,622	1,806,429	2,435,268	949,322	3,821,227
% Area	Py A % (total pyrite)	66.5	18.6	34.9	25.5	44.9
	Py B	5.39	13.5	33.3	36.2	26.6
	Py C	27.7	67	31.4	37.7	27.3
	Py D	0.29	0.53	0.31	0.2	0.31
	Py/Other Sulfide	0.61	5.64	1.74	13.2	0.7

Figure 6. XFM results. Ore sample OD2-FGP. Area of interest identified with distinct pyrite textures (10A). Framboidal pyrite textures (10B). Annotations: pyrite (py), chalcopyrite (cpy), dolomite (Dol), quartz (qz).

Figure 7. XFM results. Ore sample OD1-FGP. Area of interest identified with distinct pyrite textures (8A). Framboidal pyrite textures (8B). Annotations: pyrite (py), chalcopyrite (cpy), dolomite (Dol), calcite (cal), quartz (qz).

Figure 8. Semi-quantitative XFM element fluorescence maps of ore sample OD2-FGP (10B) showing As, Ca, Cu, Fe, K, Pb, S and Zn concentrations. Minimum concentration shown in dark blue, and maximum concentration in bright yellow.

Figure 9. Semi-quantitative XFM element fluorescence maps of ore sample OD1-FGP (8B) showing As, Ca, Cu, Fe, K, Pb, S and Zn concentrations. Minimum concentration shown in dark blue, and maximum concentration in bright yellow.

Figure 10. Box and whisker plots of trace elements in pyrite grains by texture class, showing As, Co, Ni, and Cu concentrations in ppm. Framboidal (PyD), fine-grained agglomerated (PyB), coarse-grained (PyA), and fine-grained disseminated pyrite (PyC) are presented in the graph in that order.

Figure 11. Representative time-resolved depth profiles for fine (PyC) and framboidal (PyD) pyrite grains analyzed in this study, showing Pb, Fe, Cu, Sb, As, Co and Ni intensities.

Table 6. Probability analysis of pyrite prevalence and natural floatability of pyrite and chalcopyrite.

Probability (P)		Pyrite Recovery		Chalcopyrite Loss
		Total	True Flotation	Total	True Flotation
Area, px	A Py A	83%	82%	0%	33%
	A Py B	76%	74%	1%	32%
	A Py C	94%	95%	27%	7%
	A Py D	90%	92%	39%	26%
	A Py E	68%	69%	36%	59%
	Total A Py	94%	94%	16%	14%
% Area	Py A	94%	94%	51%	29%
	Py B	36%	32%	25%	3%
	Py C	85%	88%	40%	32%
	Py D	43%	47%	44%	54%
	Py E	43%	42%	80%	78%
Feature Transformation	LN_ A Py A	90%	89%	15%	18%
	LN_A Py B	83%	82%	36%	8%
	LN_A Py C	98%	98%	40%	15%
	LN_A Py D	96%	97%	48%	28%
	LN_A Py E	49%	50%	49%	65%
	LN_A Total Py	97%	97%	35%	7%
	LN_Py A	96%	97%	49%	28%
	LN_Py B	41%	38%	27%	7%
	LN_Py C	90%	92%	43%	32%
	LN_Py D	27%	32%	46%	59%

Figure 12. Correlation area in pixels of fine-grained pyrite (Py C) vs pyrite recovery.

Figure 13. Correlation area in pixels of framboidal pyrite (py D) vs pyrite recovery.

Figure 14. Correlation prevalence in % of coarse-grained pyrite (Py A) vs pyrite recovery.

Jefferson, M., G. Forbes, E. Brown, C. Curtis-Morar, A. Parbhakar-Fox, and E. Forbes 2023. An object-based image recognition approach methodology for pyrite texture quantification in flotation performance studies, procemin 2023, Chile.

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Yenial-Arslan, U., M. Jefferson, C. Curtis-Morar, and E. Forbes. 2023. Pathway to prediction of pyrite floatability from Copper Ore Geological Domain Data. Minerals 13 (6):801. doi:10.3390/min13060801

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