Terra-XRD: Gold Application for mineralogical studies

1. Terra-XRD: Gold Application for mineralogical studies Sonia GÜiza González sonia.guiza@olympusndt.com Geochemistry – International Mining Group (IMG) Olympus NDT Innov-X

3. “XRD provides a fast and reliable tool for routine mineral identification. XRD is particularly useful for identifying fine-grained minerals and mixtures or intergrowths of minerals, which may not lend themselves to analysis by other techniques. Petrophysicists use XRD values to help calibrate mineral volume calculations derived from well log data. While XRD analysis gives quantitative volume fractions of minerals in a sample, these samples are small and can be high graded intentionally or accidentally. The important result is WHICH minerals are present, with less emphasis on QUANTITY of each mineral”. http://www.spec2000.net/09-xrd.htm

4. Contend • Mineralogy/crystallography: some definitions • 1. Methodology XRD-Powder • Terra: Unique points without competence. • 2. Gold mining application: • Exploration: Identify minerals as clays of alteration and sulfurs should get a geological model. • Exploitation: Using mineralogical for plant process improvement

5. Mineralogy/crystallography: some definitions • Lattice • A regular, periodic configuration of points, particles, or objects throughout an area or a space, especially the arrangement of ions or molecules in a crystalline solid. • Unit Cell • Smallest unit the crystal can be divided into using the crystallographic symmetry operations to represent the whole structure

6. Minerals Minerals: ordered network, with repetition of atomic position in the crystalline lattice. Watch minerals, example 1: calcite (CaCO3), aragonite (CaCO3). Steady conditions of crystal growth, i.e. environmental conditions, isotropic crystal growth. Size depends on kinetics and timescale of growth. Same chemical formula, 2 different crystal growth. calcite (CaCO3) aragonite (CaCO3)

7. 1. Terra technology: quick review • Patented vibration cell • Miniature X-ray source • Transmission geometry • Small 2D CCD detector • Energy discrimination for simultaneous XRF

8. Unique points without competition 1) Outstanding technical features: on Mars now as a station of the NASA curiosity robot • ruggedness • size • patented vibration cell 2) Terra: only battery-operated portable system available on the market 3) No cooling system required: small size, light weight 4) No moving parts: low maintenance and no calibration required 5) Low power X-ray source: X-ray tube with the lifetime of the instrument http://www.youtube.com/watch?v=0XaHp6QyP6c http://www.youtube.com/watch?v=2jy52AUjRHM

9. Unique points without competition 6) Patented sample vibration chamber: extremely easy sample prep 7) Mineral identification on the field in a few minutes ? 20 minutes a few days

10. Unique points without competition 8) Operations via the wifi: e.g. measurement start and data visualization on the iphone. • 9) Easy to use instrument: no need of highly qualified people to acquire data 10) SmartSense Detector: Reject x-rays that are not useful for diffraction (select the emission line of the target) and significant better peak background ratios. With SmartSense™ Without SmartSense™

11. Limited amount of sample needed for testing Preparation can be done on site Crush, Sieve, Test. It is that simple. Simple Sample Prep

12. Can you use a hammer? Can you connect to the internet? Great! You can run XRD samples with the Terra/BTX II SIMPLE SOFTWARE

13. Efficient Low power Lightweight Simple sample prep Simple software NASA funded R&D Same answer, half the cost!

14. Compound analysis in a few minutes Patented vibration cell VIBRATION CELL MOVIE matching software XPowder Compound identification Database 10,000 entries

15. Mina Intrepid, New Mexico, US 2. Mining Application

16. XRD Applications mining EXPLOITATION Grade Control Heap Leaching Hazardous Waste Corrosion EXPLORATION Direct Exploration Alteration Mapping

17. 2.1. Gold exploration minerals Type of deposit Type of rock host Deposit shape Tectonic framework Textures minerals Mine mineralogy Alteration mineralogy Gangue mineralogy Associated sulfurs Metals Weathering products Gold Sequences deposition Red are mineralogical studies

18. General characteristics of epithermal gold deposits

19. Minerals gold TERRA-XRD can identify every minerals Gold

21. Mineral Assemblages

22. Identify alteration minerals as clays Six samples from a drilling core taken in the UAE were prepared by the method described above for analysis in the Terra XRD/XRF. The simple mineralogy consisted of different carbonates and other secondary minerals formed by weathering, primarily kaolinite. Approximately 20mg of each sample was loaded into Terra and a twenty minute acquisition produced the diffractograms below. The samples are primarily composed of the phase Kaolinite and varying amounts of other primary minerals such as quartz, calcite, and titanium-Iron oxide. These phases are all strongly diffracting and allow for a quick identification of phases and accurate quantitative compositions.

23. Stack of all samples to show comparison of phases

24. Pattern Comparison • 13 samples with intensities normalized to 100% for visualization • 12 minute acquisition time Co-Ka energy • Note the similarities in peak positions and phases present or absent • Waterfall plot of 13 samples showing the change in mineralogy through depth • Range = Red at 2350 – Blue at 6250

25. Semi-quant Rietveld refinement data from Terra in blind comparison to lab based system.

26. Identify sulfurs Py= pyrite, Ga = galene, Sph = sphalerite Cpy = calcopyrite

27. Fifteen samples form a Copper ore mine in Turkey were prepared by the method described above for analysis in the Terra XRD/XRF. The complex mineralogy consisted of many different sulfides and other secondary minerals formed by weathering. Approximately 20mg of each sample was loaded into Terra and a twenty minute acquisition produced the diffractograms below. Terra XRF analysis allows us to identify the elements fluorescing in the sample thereby allowing us to deduce the other phases present in the sample. This tool coupled with the XRD analysis helps give Terra the full range for unknown sample identification.

29. 2.2. Using mineralogical for plant process improvement • Understanding the mineralogy and it’s texture will allow development of a theoretical grade-recovery curve, setting the upper limit for recovery with a certain concentrate grade.  Overlaying this on actual grade recovery results will help interpret these, and identify potential improvements or fundamental limitations for that feed material. • Metal distribution may be across multiple minerals, each with their own size distributions, alteration types, and association • Understanding these factors will help guide metallurgical test work, flowsheet design, mine planning and metal recovery optimization. • Often changes in mineralogy effect the way the ore processes. • In floatation processes, some minerals can float along with the metal, which reduces the grade of the concentrate. • Reagents can be added to the floatation cell if mineralogy is known. http://www.minassist.com.au/site/products.html

31. Clays as alteration hydrothermal The Terra XRD/XRF was used to analyze 6 samples taken from the Bald Mountain gold mine, near Elko Nevada. The samples were divided into three groups of two based on there performance in a leach pad. The Samples that absorbed the leach solution were labeled “BAD” while the samples that allowed for optimum irrigation were labeled “GOOD” and the intermediate was labeled “FAIR”. The samples were received ground and powdered to less than 150um, a 15mg scoop of each sample was run for 10 mins. The bad material is full of clays that expand and absorb the leaching solution, haulting the percolation, resulting in an incomplete processing of the ore material. By identifying the ore rock with clays we can divert that material away from the leach pads to allow for proper irrigation.

33. Waterfall Stack of Samples Bad Fair and Good

34. Conclusions • Terra-XRD can provide qualitative and quantitative mineral composition to identify indicator minerals that can the geologist can use to help identify where in the alteration sequence the sample was taken. • Can be used to identify ore that contains minerals that cause a problem in the processing of ore.

35. Scopes to XRD mineralogical analysis “Rocks, sediments, and precipitates are examples of geologic materials that are composed of minerals. Numerous analytical techniques are used to characterize these materials. One of these methods, X-ray powder diffraction (XRD), is an instrumental technique that is used to identify minerals, as well as other crystalline materials. XRD provides the researcher with a fast and reliable tool for routine mineral identification. XRD is particularly useful for identifying fine-grained minerals and mixtures or intergrowths of minerals, which may not lend themselves to analysis by other techniques. XRD can provide additional information beyond basic identification. If the sample is a mixture, XRD data can be analyzed to determine the proportion of the different minerals present”. http://pubs.usgs.gov/info/diffraction/html/