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Portable XRF and Coal For Mineral Exploration, Grade Control, Blending & Processing

Olympus portable X-ray fluorescence (pXRF) analyzers provide high-performance, real-time geochemical data for rapid multielement characterization of soils, rocks, and ores. Advances in pXRF technology have improved the limits of detection and the number of elements measured while reducing analysis test times. For the coal industry, these advances make it possible to quickly estimate the ash content and other key constituents on site.

Introduction:
the use of pXRF in coal applications

The ability of pXRF technology to measure key light elements (namely sulfur (S), silicon (Si), and aluminum (Al)), has rendered the tool vital in day-to-day decision-making. Decisions are based on the direct measurement of sulfur and the ability to estimate both ashing content and calorific values based on the sum of the light and inorganic major element fraction, namely magnesium (Mg), silicon (Si), aluminum (Al), potassium (K), calcium (Ca), and iron (Fe). Opportunities and applications of pXRF exist in both thermal and coking coal operations and processing.

Additionally, pXRF measures over 30 elements instantly, enabling the trace element content to be characterized, the use of litho-geochemistry to correlate stratigraphy, and the identification of marker horizons within individual coal seams and surrounding geology. The use of pXRF can be beneficial across the entire mining value chain, beginning with exploration drilling activities, routine grade control operations in existing mines, as well as downstream mineral processing and final product delivery.

The value of pXRF

Real-time data enables real-time decision-making, improving productivity and cost savings through better equipment and personnel utilization. The implementation of a successful pXRF program has been demonstrated across many routine mining activities including:

Assisting early stage exploration when the “first boots hit the ground” in the field
Optimizing drilling activities — extending or completing holes more efficiently and saving on extra mobilization and drilling costs
Better ore/waste characterization during ore spotting activities and better optimization of the run of mine activities through blending and stockpile controls
Assisting in mapping and visual ore-body definition
Refinement and fine-tuning of mineral process control and metallurgical decisions and investigations
Rapid in situ final product analysis at any point
Waste characterization, including acid mine drainage (AMD) designation and material management

Analytical performance and applications

Olympus’ latest generation pXRF instruments incorporate many advanced features that deliver excellent results in near real time. These include digitally controlled, Rh-anode X-ray tubes, multiposition automatic filter wheels, and large area silicon drift detectors (SDDs) coupled with proprietary high count rate (HCR) Axon Technology™. These features deliver precise, accurate results, faster test times, lower detection limits, and enhanced performance on the lighter elements (Mg, Al, Si, P S), which are important to the coal business.

This empowers the coal geologist to use a suite of different geochemical tools including:

Almost complete whole rock geochemistry, covering most of the important major and trace elements used for litho-geochemistry and rock-typing
Direct sulfur analysis, mitigating slow and expensive furnace techniques
Ability to use light element proxies to estimate ashing content (ash yield) and, often, to indirectly calculate calorific value (CV)

Figures 1 and 2 illustrate the performance obtained on a large set of diverse coal standards (certified reference materials). Figure 1 shows how a combined light element proxy, as well as silica alone, can be effectively used to estimate ashing content (ash yield).

Figure 1. Excellent correlation between an Olympus portable XRF and certified reference materials enables effective estimation of ashing content using a combined light element proxy (Mg+Al+Si+P+S+Ti+K+Ca +Fe) or just silica alone. Better results are obtained by using a more complete set of elements.

Panoramic view of the giant Sebuku Open Cut Thermal Coal Mine in Southern Kalimantan, Indonesia. This mine is one of several operated by Sakari Resources in the region and shows the large scale and complex interaction of very large equipment and complicated multiseam geology. Olympus portable XRF (pXRF) offers many opportunities to aid rapid decision-making in material allocation, blending, and final delivery to sea barges that transport the coal to regional power stations.

Certified Reference Material	Mg (%)		Al (%)		Si (%)		P (%)		S (%)		K (%)		Ca (%)		Ti (%)		Fe (%)		Combined Elements	Lab Ash %
Certified Reference Material	Lab	pXRF	Lab	pXRF	Lab	pXRF	Lab	pXRF	Lab	pXRF	Lab	pXRF	Lab	pXRF	Lab	pXRF	Lab	pXRF	Combined Elements	Lab Ash %
SARM-18	0.08		1.22	1.48	2.61	3.25	0.003	0.007	0.50	0.76	0.11	0.18	0.12	0.22	0.06	0.06	0.18	0.17	6.13
L/95966	0.07		1.21	1.23	2.04	1.86	0.018	0.022	0.36	0.44	0.15	0.21	0.18	0.28	0.07	0.07	0.50	0.64	4.76	9.35
L/95967	0.09		2.44	2.55	3.10	2.99	0.082	0.079	0.34	0.31	0.05	0.03	0.74	0.92	0.12	0.14	0.50	0.57	7.59	15.94
L/95968	0.12	0.11	1.11	1.11	1.90	1.64	0.027	0.028	0.31	0.34	0.19	0.29	0.11	0.17	0.06	0.05	1.06	1.43	5.18	9.33
L/95969	0.01		1.06	0.93	5.89	7.11	0.003	0.007	0.53	0.71	0.06	0.05	0.01		0.05	0.04	0.18	0.11	8.96	16.65
L/95970	0.01		1.04	1.00	3.19	3.37	0.009	0.017	0.54	0.75	0.05	0.08	0.01	0.01	0.05	0.06	0.41	0.49	5.77	10.76
L/95971	0.08		2.00	2.09	3.50	3.62	0.009	0.011	0.28	0.37	0.11	0.12	0.12	0.15	0.10	0.11	0.34	0.40	6.87	13.90
L/95972	0.05		0.95	0.89	3.98	4.66	0.027	0.030	0.40	0.57	0.13	0.18	0.04	0.05	0.05	0.04	0.24	0.20	6.63	12.42
L/96047	0.03		1.34	1.36	1.95	1.57	0.009	0.021	0.23	0.23	0.02	0.04	0.04	0.09	0.07	0.07	0.10	0.03	3.41	8.05
Ciuden	0.15	0.12	1.88	1.95	2.83	2.73	0.100	0.094	0.59	0.62	0.05	0.05	0.92	1.39	0.13	0.15	0.29	0.26	7.35	14.55
El Cerrejon	0.14	0.10	1.45	1.51	2.46	2.29	0.055	0.056	0.57	0.64	0.10	0.13	0.41	0.66	0.09	0.10	0.40	0.45	5.93	11.53
Sebuku	0.13		1.48	1.71	2.38	2.21	0.027	0.042	0.40	0.54	0.09	0.13	0.29	0.53	0.14	0.17	0.38	0.46	5.80	10.94
Socnica	0.23	0.11	1.06	1.10	1.69	1.29	0.027	0.032	0.43	0.47	0.15	0.22	0.36	0.60	0.05	0.06	0.46	0.54	4.42	8.73
Grosvenor33	0.16	0.11	1.48	1.54	3.46	3.95	0.002		0.43	0.54	0.05	0.05	0.02	0.00	0.04		0.48	0.58	6.78	12.62
Grosvenor35	0.21	0.19	1.68	1.80	4.86	5.78	0.009		0.35	0.37	0.10	0.11	0.09	0.04	0.09	0.09	1.73	1.87	10.24	18.97
Grosvenor38	0.12	0.20	2.79	2.78	14.41	15.50	0.004		0.28	0.26	0.22	0.12	0.04		0.09	0.08	0.14	0.05	18.99	41.22
Grosvenor42	0.07		0.33	0.08	2.60	2.68	0.001		0.49	0.75	0.01	0.02	0.13	0.18	0.02		0.11	0.04	3.75	7.60
GrosvenorSeg8	0.62	0.41	6.97	6.64	17.24	18.76	0.013			-0.02	1.09	1.08	0.47	0.14	0.35	0.34	1.23	1.18	28.53	62.86
GrosvenorSeg10	0.66	0.56	8.00	8.00	28.46	27.54			0.00		1.69	1.74	0.28		0.47	0.45	1.03	1.01	39.31
GrosvenorSeg11		1.03	6.81	7.96	10.40	12.61	0.020		0.00		1.28	1.27	7.57	8.85	0.24	0.26	9.52	9.63	41.62
GrosvenorSeg12	1.67		6.14	5.93	20.95	18.75		0.045	0.00		1.00	0.94	4.43	5.56	0.35	0.34	5.71	5.97	37.54
A1_0092A 003	0.25	0.38	9.62	9.27	18.94	20.10		0.030	3.96		1.77	1.77	0.15		0.48	0.51	3.62	3.16	35.22	75.72
A1_0092A 004	0.38	0.44	9.02	8.35	19.92	19.99			2.97		2.14	2.17	0.11		0.54	0.51	2.90	2.57	34.03	76.36
A1_0092A 010	0.31	0.38	8.89	8.65	19.68	19.87			0.22	0.02	1.63	1.59	0.20		0.56	0.55	0.67	0.61	31.68	71.80
A1_0092A 012	0.13	0.26	2.20	2.75	5.68	6.37	0.182	0.182	0.76	1.00	0.35	0.43	0.45	0.59	0.17	0.19	0.79	0.93	12.70	21.78
A1_0092A 015	0.14	0.16	0.62	0.83	0.69	0.44		0.094			0.02	0.03	0.26	0.54	0.02		1.21	1.63	3.72	6.45
A1_0092A 073	0.15		11.48	11.85	22.07	19.50		0.077	0.09	-0.16	0.69		0.25		0.75	0.75	0.46	0.38	32.39	80.76
A1_0092A 126			0.68	0.56	1.03	0.57	0.052	0.041	0.41	0.42	0.05	0.01	8.70	10.46	0.05	0.04	4.77	4.70	16.81	32.91
ALD	0.06	0.13	0.70	0.58	1.53	1.07	0.002		2.20		0.08	0.09	0.05	0.05	0.04		0.62	0.73	2.65	6.81
ATK	0.07		1.23	0.96	2.92	2.08	0.004		3.59		0.19	0.14	0.03		0.06	0.04	1.61	1.80	5.02	12.76
Bird R003	0.05		0.53	0.38	1.31	0.74	0.003	0.009	3.81	3.55	0.03	0.00	0.15	0.24	0.03	0.05	3.12	2.72	7.68	9.70
UFRGS-1	0.22		8.32	8.35	16.64	17.35	0.011		2.00		0.80	0.61	1.19	0.98	0.38	0.42	2.01	1.83	29.53	66.00
UFRGS-2	0.21		8.17	7.38	14.41	14.22	0.008		3.71		0.75		0.55		0.35	0.33	3.31	3.10	25.02	65.11
UFRGS-3	0.40	0.42	3.84	4.88	10.87	9.00	0.016	0.020			1.01	0.93	0.41	0.10	0.25		3.80		15.34	44.62
UFRGS-4	0.18		4.38	3.27	8.44	8.64	0.018	0.013	3.75	3.66	0.79	0.88	0.30	0.18	0.32		8.17		16.66	44.98
SARM-19			3.86	4.01	6.38	6.19	0.010	0.018	1.36	1.18	0.18	0.08	0.90	1.18	0.18	0.18	1.11	1.05	13.87
SARM-20			5.42	5.65	7.52	7.61	0.050	0.039	0.46	0.20	0.11		1.22	1.52	0.35	0.34	0.75	0.65	16.02

Figure 2. Excellent correlation between an Olympus portable XRF and a large collection of coal certified reference materials (CRMs). The graphs above show excellent agreement between the laboratory certified values and the pXRF-derived values for the most important elements of Mg, Al, Si, P, S, K, Ca, Ti, and Fe both in terms of accuracy and precision. The table contains both the lab and pXRF values that these graphs were constructed from. (Data courtesy of School of Biological and Earth Sciences at the University of New South Wales - ACARP Projects).

Sebuku and Jembayan Mine Orientation Studies

Sebuku and Jembayan Mine Orientation Studies

The world-class Sebuku and Jembayan Thermal Coal Mines are located in Kalimantan, Indonesia. Due to the remote location and large-scale operations, there was a requirement to conduct trials of new methods for determining coal classification more rapidly, in near real time. The pXRF orientation work was undertaken on pit-faces and material stockpiles to develop a method for estimating direct sulfur content and ashing yield as part of the routine run of mine (ROM) activities. Viable coal is then blended and washed onsite to obtain the correct quality before being loaded onto barges, where it is then shipped to large thermal coal stations in the region. Figure 3 shows some of the orientation data that was developed at the start of this project and exhibits good agreement between pXRF, sulfur, ashing content, and calorific value that was developed by the geology team at Sebuku and Jembayan.

Data used to assess the usefulness of using pXRF at the Sebuku Mine.

Figure 3. Data used to assess the usefulness of using pXRF at the Sebuku Mine. The top chart shows pXRF versus lab for direct sulfur content, the middle chart shows lab ash content versus lab Si + Al, and the lower graph illustrates the trend between lab ash content and calorific value (CV).