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Fe-Ore Mineralization Heavy & Light Element Analysis


The Olympus DELTA couples an ultra high resolution Silicon Drift Detector (SDD) with a powerful 4W X-ray tube, delivering the fastest, most precise analysis available today in a handheld X-ray Fluorescence (XRF) analyzer. SDDs provide three major improvements over traditional Si PiN Diode X-ray detectors: 1) the ability to detect and process 10× more X-rays in a given amount of time, 2) better energy resolution, and 3) improved peak-to-background ratio. The result is far better precision and lower limits of detection for Mining and Exploration applications.

Unprecedented Performance in Iron Ores & Associated Trace Elements:

Optimal feed grade for iron ore concentrates is usually in excess of 60% Fe by weight, with less than 0.20% P, 3-7% silica, less than 5% Al, and low S and Ti.

Delta Handheld XRF in inspector's hand

The inclusion of even small amounts of some trace elements can have profound effects, both good and bad, on the behavior of iron in a blast furnace. The DELTA analyzer, with SDD technology, now enables the determination of all important phases of iron ores. Fe content can be accurately and precisely determined over a broad analytical range (30% to 80% Fe). Mn, Ti, Al, Si, P, and S can also be accurately analyzed, along with 25 other elements.

Data Result Graphs of Fe, Mg, Titanium
Iron, Manganese, Titanium, Aluminum, Silicon and Phosphorus Performance on Typical Hematite Rich, Banded Iron Ore. (90 sec test time in AIR using a DELTA SDD Analyzer)

Light Element Analysis and Sample Preparation

In Field Portable X-ray Fluorescence (FPXRF) analysis, light elements (LE) are generally regarded as those with Atomic number (Z) less than 18 (Argon) and usually refer to the group: Mg, Al, Si, P, S and Cl. The investigation of Bauxite deposits is dominated by this LE suite, particularly Al, Si + Ca and K, and the mineralization style is often hosted in a coarse crystalline matrix. Therefore, they are significantly influenced by high sample heterogeneity and in order to achieve meaningful (decision level) analytical quality it may be necessary to undertake some form of sample preparation. This can involve a coarse crush and if necessary, pulverizing of the sample to 200μm and then placing into an XRF sample cup using Polypropylene film supports (as opposed to Mylar film which cannot be used for looking at LE).

Why Use FPXRF?

The aspect of “True Portability” with the latest generation of XRF essentially enables the ability to bring a “miniaturized version of the laboratory” into the field, with obvious limitations. Olympus is clear and transparent about these limitations: (1) Higher LOD’s than lab-based techniques; (2) Lower precision than lab-based techniques (higher ± values but no compromise on accuracy above LOD’s; (3) Less repeatable results.

FPXRF should not to be seen as a replacement for the laboratory and should be used in conjunction with laboratory and industry standard reporting protocols such as determined by the ASX (JORC CODE) and the TSX (43-101). The main advantage of FPXRF lies in the ability to generate dynamic, real-time, spatially registered geochemical data sets, rapidly.

The Geoscientist can now immediately postulate the elemental characteristics of the observed regolith or lithology dynamically, making informed decisions while still in the field, at the exact location of the sample of interest. Instant and interactive approaches to exploration project management, target delineation and associated vectoring towards mineralization are now possible. This results in significantly reduced time-frames with less time intensive reiterations, such as excavating samples and sending them to the lab with the associated “normal” lengthy turnaround times and lags. FPXRF can be thought of as being a pre-screening tool used to select the best and most appropriate sample to submit to the Laboratory for comprehensive and more detailed analysis.

Additionally, the ability to refine your sampling program in the field real-time means that you can easily increase sample density and resolution instantaneously.

These field based efficiency gains are advancing project time-frames and assisting companies to better utilize their time in the field and maximize their exploration budget.

LOD's: The Million Dollar Question

The determination of the analytical limit of detection (LOD’s) depends on many aspects, not directly related to the instrumentation of choice. Some of these influences include (influential factor denoted in brackets):

  • The energy of excitation or X-ray source (instrument). Note: This is not all about obtaining the maximum voltage (or keV). It is reliant on the process of fine-tuning both the X-ray voltage and current to maximize the received count rate and therefore analytical precision (instrument).
  • The Atomic Number and associated response of element(s) being analyzed (sample).
  • Concentration of elements present (sample).
  • Relative density and matrix composition (sample).
  • Sample size, granularity and surface geometry (sample and user).
  • Length of test run (user).
  • The quality of the instrument calibration and QC samples used to “tweak” the instrument (user and instrument).

Delta Handheld XRF Analyzer testing steel

“As such, the sample is the most influential factor with regards to determining lod’s when using FPXRF”

Olympus IMS
ProductsUsedApplications

Combining a Silicon Drift Detector (SDD) and a 4W optimized X-ray tube, the DELTA Professional provides superior performance in speed, LODs, and elemental range. It analyzes Mg and higher for Alloys and Mining. The DELTA Professional is the best value solution from Olympus for handheld XRF.
The TERRA Mobile XRD System, a high performing, completely contained, battery operated, closed-beam portable XRD, provides full phase ID of major, minor and trace components with a quick XRF scan of elements Ca – U. Its unique, minimal sample prep technique and sample chamber allow for fast, in-field analysis.
The BTX Benchtop XRD System is a fast, low cost, small footprint, benchtop XRD for full phase ID of major, minor and trace components and quick XRF scan of elements Ca – U. Its unique, minimal sample prep technique and sample chamber allow for fast, benchtop analysis rivaling the performance of large costly lab units.
DELTA Mining and Geochemistry Handheld XRF Analyzers provide immediate results to help determine the next course of action for the entire process – exploration, ore grade/process control, environmental sustainability. On-site detection of metals, minerals and contaminants. GPS-GIS-XRF for instant metal mapping, time, cost savings.
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