Nickel Ore Analysis: Boosting Mining Quality with WDXRF

Accurate analysis of nickel ores is essential for efficient mining, optimized production, and regulatory compliance. Wavelength Dispersive X-ray Fluorescence (WDXRF) provides rapid, reliable elemental data, helping ensure consistent quality and profitability in nickel processing.

Overview

In addition to mineralogical analysis, accurate chemical analysis of nickel ores is crucial for optimizing production, ensuring quality, and maintaining profitability and compliance.

If nickel ore is not analyzed correctly, several negative consequences can occur. Misjudging the quality and grade of the ore can lead to inefficient processing and refining, resulting in lower yields and higher costs. Without accurate chemical analysis, processing plants may operate suboptimally, wasting energy and resources on unsuitable ore. This can lead to significant financial losses due to the overestimation or underestimation of the ore’s value, affecting overall profitability.

Additionally, poor analysis can result in inconsistent product quality, impacting downstream applications and customer satisfaction. Inefficient processing due to incorrect analysis can also lead to increased waste and environmental pollution. Failure to meet industry standards and regulations due to inaccurate analysis can result in legal penalties and reputational damage.

This article will discuss nickel and its importance, how it is processed, and how WDXRF is an important analysis tool to make sure mining and processing operations meet customer requirements.

About Nickel

Nickel (Ni) is a transition element with both ferrous and nonferrous properties, associated with iron and sulfur. As explained in the USGS National Minerals Information Center, it is mined from laterites, containing nickeliferous limonite and garnierite, and magmatic sulfide deposits with pentlandite. These nickel bearing minerals require different processing methods to separate the nickel metal from the ore. Most nickels ores are primarily sold as refined metal or ferronickel.

About 65% of nickel in the Western World is used for austenitic stainless steel, 12% for superalloys and nonferrous alloys due to their corrosion resistance. The USGS site notes that the aerospace industry heavily uses nickel-based superalloys for jet engine parts. These superalloys are also used in land-based turbines. The remaining 23% of nickel consumption includes alloy steels, rechargeable batteries, catalysts, coinage, foundry products, and plating.

According to the U.S. Geological Survey, Mineral Commodity Summaries, January 2024, most secondary nickel is in the form of nickel content of stainless-steel scrap. Nickel in alloyed form is recovered from the processing of nickel-containing waste. Most recycled nickel has been used to produce new alloys and stainless steel. In 2023, recycled nickel in all forms accounted for approximately 57% of apparent consumption.

Nickel ore processing

Nickel ore processing involves several steps to extract nickel from its ores depending on the mineralogy of the ore deposit. Nickel laterite ore deposits are one of the two main types of nickel ores (the other being sulfide ores) and account for the majority of global nickel resources. Extracting and refining nickel from laterite ores is complex and energy-intensive due to the ore’s chemical composition and physical characteristics. Multiple processing steps are required to separating nickel from ores and turn it into a pure metal.

Here is a high-level overview of the main process:

Mining: Nickel ore is extracted from either open-pit or underground mines. The type of mining depends on the location and depth of the ore deposit.
Crushing and Grinding: The extracted ore is crushed dry and then ground in wet grinding mills to a fine powder in order to create a slurry from which the nickel-containing minerals can be liberated from the host rock.
Concentration: The ground ore is subjected to various concentration processes depending on the mineralogy in order to increase the nickel content. This can include:
- Sulfide ores
  - Froth Flotation:
    - A process where the finely ground ore is mixed with water and chemicals to create a frothy mixture in a flotation cell. The nickel-containing sulfide minerals attach to the bubbles and float to the surface, thereby separating the value bearing minerals from the gangue minerals.
    - The initial froth concentrate is further refined and upgraded into a sellable concentrate so it can be purified into metal at a Smelter.
- Laterite ores
  - High-Pressure Acid Leach (HPAL):
    - Crushed and ground ore is mixed with sulfuric acid.
    - The slurry is heated to 240–270°C under high pressure (3.4–5.6 MPa) in an autoclave.
    - Nickel and cobalt are leached into solution.
    - The solution is then neutralized and precipitated to recover nickel and cobalt.
    - The precipitate must undergo further refining to purify and separate the metals into a sellable product.
- Magnetic Separation: Used if the nickel ore is magnetic.
Smelting: The concentrated ore is then smelted in a furnace to produce a nickel-rich matte. This involves heating the ore to high temperatures in the presence of a reducing agent (such as coke) to separate the metal from the slag.
Refining: The nickel matte is further refined to produce pure nickel. This can be done through:
- Hydrometallurgical Processes, such as leaching with acids or ammonia, followed by solvent extraction and electrowinning.
- Pyrometallurgical Processes, such as converting and refining in an electric furnace.
Electrorefining: In some cases, the nickel is further purified by electrorefining, where impure nickel is dissolved in an electrolyte solution and pure nickel is deposited onto cathodes.
Final Processing: The refined nickel is then processed into various forms, such as ingots, sheets, or powders, depending on the intended use.

Each of these steps involves various chemical and physical processes to help ensure the efficient extraction and purification of nickel from its ores. And to make sure the finished product meets requirements, samples should be analyzed throughout the process.

Nickel Analysis

Nickel ore processing requires fast, reliable analysis to maintain efficiency. Slow lab-based methods delay decision-making and impact productivity. WDXRF Spectrometers can provide rapid, repeatable nickel analysis in just minutes.

Wavelength Dispersive X-ray Fluorescence (WDXRF) plays a crucial role in nickel ore analysis by providing accurate and precise elemental composition data. WDXRF works by directing X-rays at a sample, causing elements to emit characteristic secondary (fluorescent) X-rays. These emitted X-rays are then dispersed by wavelength using a crystal, and detected, allowing for precise identification and quantification of the elements present in the sample.

Here are the key roles of WDXRF in nickel ore analysis:

Elemental Quantification: WDXRF is used to determine the concentrations of various elements in nickel ore, including nickel, iron, sulfur, and other trace elements. This helps in assessing the quality and grade of the ore.
Quality Control: It ensures consistent quality of the ore by monitoring the elemental composition during different stages of processing, from mining to refining.
Efficiency: WDXRF is a rapid and non-destructive analytical method, allowing for quick analysis of multiple samples without altering their physical state.
Accuracy and Precision: WDXRF provides high accuracy and precision in measuring elemental concentrations, which is essential for making informed decisions in ore processing and refining.
Compliance: It helps in meeting regulatory requirements and industry standards by providing reliable data on the elemental composition of nickel ores.

Summary

Accurate nickel ore analysis is vital for maximizing mining efficiency and product quality. WDXRF technology offers rapid, precise elemental measurement, enabling mining operations to optimize processing, reduce waste, and meet environmental and regulatory standards. This summary highlights how advanced analytical techniques support profitable and responsible nickel production.