X-Ray Diffraction

X-Ray Diffraction 

X-Ray Diffraction (XRD) is a powerful analytical technique used to identify and characterize the crystalline structure of minerals and materials.

X-Ray Diffraction  v X Ray Fluorescence

XRD provides imaging on the crystal lattice formed by elements in the mineral while XRF provides elemental composition

Principle of Operation

XRD operates based on the diffraction of X-rays by the regularly spaced atomic planes in crystalline materials. When a beam of monochromatic X-rays strikes a crystalline sample, it is scattered in specific directions.

When the condition is met, a diffraction peak appears at the corresponding angle.

Step 1

Sample Preparation

The sample (ore, rock, or concentrate) is crushed and finely ground (typically <10 µm particle size) to ensure random crystal orientation.

The powdered sample is placed on a sample holder (flat plate or glass slide).

For quantitative work, the sample may be mixed with an internal standard (like corundum) to improve accuracy.

Step 2

 Instrument Setup

The X-ray diffractometer consists of:

X-ray source (commonly Cu-Kα radiation, λ = 1.5406 Å)

Goniometer to control the incident and diffracted angles

Step 3

Data Collection

The sample is scanned through a range of 2θ angles (usually 5°–70°).

The detector records the intensity of X-rays at each angle to produce a diffraction pattern (intensity vs. 2θ).

Step 4

Data Analysis

The resulting diffraction pattern is compared with standard reference databases, such as the ICDD (International Centre for Diffraction Data).

Software identifies and quantifies the minerals present using Rietveld refinement or semi-quantitative methods.

Step 5

Interpretation

Peaks in the XRD pattern correspond to specific mineral phases (e.g., quartz, pyrite, hematite, calcite, etc.).

The relative intensities help estimate the proportion of each mineral phase in the sample.

Mineral Identification

XRD accurately identifies major and minor mineral phases in ores, rocks, and concentrates. Essential for determining ore type and alteration zones during exploration.

Ore Characterization and Processing

Knowing the mineralogical composition helps metallurgists design suitable beneficiation and extraction methods. For example, distinguishing between oxide and sulfide minerals of copper or nickel can guide process selection.

Hydrometallurgy and Leaching Studies

Determines the formation of new mineral phases during leaching, roasting, or smelting.For example, monitoring the transformation of hematite to magnetite during roasting.