Analysis of Precious Metals December 28, 2022 – Posted in: Metals – Tags:

Precious metals necessitate careful examination because of their greater market value, and purity is a factor when dealing with these metals or products made from them. Various alloys must identified and their composition confirmed. Fortification, although not always obvious, can significantly impact the value. The range of precious metals analysis is from trace to 100%. Except for the strongest acids, most of these metals are resistant to dissolution. Some traditional analysis techniques, such as burn experiments, take longer and necessitate a high degree of expertise.

Gold, platinum, iridium, palladium, osmium, silver, rhodium, ruthenium, and rhenium are classified mainly as precious metals. All are transition metals with high financial worth due to their scarcity and unique properties. There entire industries dedicated to recovering precious metals from sources like scrap jewellery, industrial waste, and junked vehicle catalysts. At the other end of the manufacturing chain, exploitation of ores with minimal precious metal content is financially sustainable. Higher prices and the greater possibility of new technology make it feasible to rework old mine dumps, extracting metals left behind by older, less efficient extraction methods. Evaluating these sources necessitates sub-parts-per-million analysis.

Conventions and Karats

Bullion refers to valuable metals in larger quantities that traded by weight. This term also pertains to gold coinage when the price determined by the purity and mass of the coin rather than its market price. Several conventions have emerged to define the purity of the metal in jewellery and other consumer products like silver tableware. These far more widely used in the industry than the concentration units employed by analysts. Pure 24-karat gold is too soft for jewellery and is prone to scraping and deformation.

As a result, gold frequently alloyed with other metals; silver and copper are the most common material elements. Intensities can strictly managed to produce metals with the appearance of gold but very little actual substance. In small quantities, metals like zinc also utilized to enhance stiffness. These alloys can still be sold as “gold,” though most countries have a gold content limit below which the term cannot used. White gold is yet another popular jewellery alloy in which gold is malleable and ductile with materials like palladium or nickel. White gold can rhodium-plated when used in jewellery. Rhodium is also “white,” and when it neglected, it can inaccurate in some analysis tools.

The Role of Analysis

Elemental analysis is essential in the precious metals industry. Common functions involve:

  • Purification and structure validation, which include hallmarking, for commercial reasons.
  • Alloy Identification
  • Impurities and adulteration testing
  • Analysis of recycled waste and processed materials
  • Process Control
  • Prospecting

The concentration level used in these evaluations ranges from pure metal to sub-ppm. They also come across a vast variety of sample types, ranging from precious metals to jewellery to “sweeps” from the workplace to scrap products to bulk environmental samples.

Different Methods of Analysis

The traditional analysis method involves:

  • The acid test
  • Conductivity
  • Fire assay

The modern analysis method involves the following:

  • Energy-dispersive X-ray fluorescence (EDXRF) and optical emission spectrometry (OES)
  • Inductively coupled plasma optical emission spectrometry (ICP-OES)
  • ED-XRF Analysis of Precious Metals
  • Spectro MIDEX and spectrocube

Recycling Process

Motor catalysts and industrial wastes are two primary sources of reprocessed precious metals (e-waste). Precious metal-containing elements (such as catalytic converters or printed circuit boards) are eliminated and delivered to specialized treatment companies. In the case of emissions controls, the PGM catalyst is usually deployed on ceramic particles with a metal content ranging from 0.2%. This is extracted from its steel compartment and milled into small particles containing the PGMs in preparation for further processing. Printed wiring panels and other electronic waste typically ripped up before being exposed to blast furnaces and/or leaching processes to extract precious metals. Prices determined by analyzing this powdered or shredded material.

Payment should determined by research. Outcomes of adequate precision that can acquired instantly, in-house, by personnel lacking special analytical abilities would be excellent. Certainly, relying on time-consuming and costly environmental analysis, or lower-priced but possibly less accurate testing and development, is a distinct disadvantage for any person in a transfer of funds. Unfortunately, conventional testing procedures are either too unreliable or time-consuming, or they necessitate the use of a properly equipped laboratory.