Fire Assay Crucibles

Westref supplies high-quality multi-trip clay crucibles for the analysis of precious metals using the fire assay method. Our robust crucibles are made from superior ceramic materials made to withstand extreme temperatures and have the ability to suit a wide range of matrices encountered in . A wide variety of crucible sizes are available to fit your laboratory’s testing needs. Increase your productivity and reduce operational costs with these quality yet cost-effective crucibles.

With over 40 years’ experience in the ceramic industry, we offer unsurpassed expertise and service. Consultation is available upon request.

  • Over 40 years experience in the ceramic industry
  • Capacity to suit any size of commercial laboratory
  • Custom sizes available
  • Prompt shipment

Common crucible sizes:

  • 30g
  • 40g
  • 50g
  • 45T/55g
  • 65g
  • 75g

Other crucible types:

The minerals industry uses a wide variety of crucible types. These include:

  • Silicon Carbide
  • Graphite
  • Platinum
  • Porcelain

Westref’s network is at our disposal to source these other types of crucible on request.

What are fire assay crucibles?

This relatively simple looking ceramic (we call them pots) made of fire clay and proprietary additives, has an extremely long history in the gold business. Its use is referenced in historical texts that are more than 3000 years old, which when you think about it, is no surprise really. A crucible is, in simple terms, a ceramic cup.

A modern fire assay crucible is not that far removed from those of the past with the exception of the additional science behind it’s composition. Modern crucibles are made for laboratory use rather than refining and so are required to be exacting in their specifications. Additionally they should be strong enough to withstand huge changes in temperature through multiple uses.

The crucible is used for the first part of the fire assay fusion process. The following process is typical:

  • Flux and sample are added to the crucible
  • The above additions are mixed together inside
  • Heat is applied to the crucible and mixture by placing the pot in a furnace at > 1000oC
  • After a pre-determined period of time the crucible is removed and the molten contents are poured into a cast iron mould
  • The crucible is cooled and ready for it’s next use however, it may be disposed of if the previous sample contained high quantities of gold.

Finding Your Perfect Crucible

Fire assay can be considered the most reliable method for determining the content of precious metals — such as gold, silver, or platinum — in ores. When you’re making use of the fire assay process, a critical piece of equipment is your crucible. Let the family-owned business, Westref, take care of your fire assay needs with their range of fire assay equipment and consumables.

Although crucibles can be used in casting processes, they are the ideal candidate for processes that make use of molten metal. They are made to be non-reactive and withstand repeated exposure to extremely high temperatures. Westref supplies crucibles composed of a proprietary blend of clay made to customer’s specific requirements. Across a wide range of sizes, these superior quality ceramic crucibles are designed to withstand extreme temperature shocks.

If you require an alternative material, Westref is able to source other types of crucibles that are made up of silicon carbide, graphite, platinum, or porcelain.

silicon carbide graphite crucible

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Industrial Crucibles are designed for specific applications and this would determine their shape, size, and material. Crucible sizes can range from as small as a teacup or may be large enough to hold several tons. The different shapes for crucibles are:

  • Barrel-shaped
  • Conical/tapered
  • Cylindrica
  • Wide-form
  • High-from

tapered graphite crucible

The material your crucible is composed of must correlate to the type of furnace and heating method that is used. Some furnaces may have a slower heating rate and, thus, the crucible needs to be designed with high thermal conductivity to ensure energy is captured. Some of the types of furnaces used are:

  • Fuel Fired
  • Electric Resistance
  • Induction
  • Pit Furnace

A crucible may be designed to be removed from the furnace, but it can also be fixed within the furnace. Most laboratory applications make use of removable whereas factories often make use of fixed crucibles. Removable crucibles are designed to have an “A” shape which ensures they can be gripped with tongs. Choosing your crucible design largely depends on the intended application. What materials are you handling? Are you working in a laboratory with small samples or a large factory? Influencing factors that will determine your crucible parameters are:

  • The capacity, dimensions, and type of furnace used
  • The alloys to be melted
  • Melting and holding temperatures
  • The temperature change rate
  • Fluxes used
  • How slag is removed

Making use of a flux dispenser system will ensure a safe and efficient fire assay process. Westref revolutionized the fire assay industry when they created the first successful automatic flux dosing system. With a customizable flux dispensing machine, your needs can be cost-effectively met.

If you’re in need of crucibles, flux mixers, fire assay flux, or furnaces, contact us now.

CONTACT US FOR A QUOTE ON THIS PRODUCT

“Reliable, driven, family business that provides quality products and will work diligently with its partners towards mutual success.”

Anonymous customer survey submission, 2016

“I hope you can keep producing such wonderful products and expand the range of your products”

Head of Fire Assay

“We have been using Western Refractories Fire Assay Flux, Crucibles and Cupels for the past six years at our Laboratory in Metro Perth and have had virtually no issues with the quality of the products or timely supply.”

Laboratory Manager Perth, Western Australia

“WR’s level of support, commitment to partnering, response time and desire to constantly improve are exceptional.”

Procurement Lead Perth, Western Australia
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