Fire Assay Flux FAQ: Specifications, Ordering and Support Questions

Fire Assay Flux is a core reagent in precious-metal analysis. Whether you are setting up a mining laboratory, sourcing for an existing assay operation, or evaluating suppliers, the questions below address the product's role in the fire assay process, its ingredients and customization options, packaging, and how to place an order.

What is it and what does it do?

The product is a dry yellow powder used as a key ingredient in fire assay. It is a blend of predominantly dry ingredients — including litharge, dense soda ash, borax, and others — that is mixed with mineral samples containing precious metals and heated in a furnace. The heat triggers fusion, precipitating a lead (Pb) button. That button is then treated by cupellation to yield a prill of precious metals from the original sample. This approach can produce results specified in parts per billion.

Typical ingredients and available forms

The most common ingredients globally are litharge, dense soda ash, borax, baking flour or corn meal, silica flour, and silver nitrate. Litharge is available in powder or granular form and in different grades of purity. The composition must be adapted to suit the matrix of the sample being tested.

The finished product ships as a yellow powder, packaged to the buyer’s requirements, with prompt international shipping available.

Custom formulations and consultation

HEBEI FIZA TECHNOLOGY CO., LTD. typically produces the flux to a very specific, customer-supplied recipe. Consultation is available upon request to align the formulation with the sample matrix in use.

Quality control

A high level of quality control is maintained at each stage of production, covering each key ingredient in the blend.

Related consumables in the fire assay workflow

Two other consumables are used alongside the flux in fire assay:

• Cupels — HEBEI FIZA TECHNOLOGY CO., LTD. supplies magnesia cupels (MgO ≥ 98.5%) with a working temperature of 1,000 °C, 70% lead absorption, and a precious-metal recovery rate of 97–98.5%.
• Crucibles — Available in alumina ceramic and clay, sizes 20 g–75 g, working temperature 1,400 °C–1,500 °C, and a service life of 3–5 uses.

Sourcing all three consumables from one supplier simplifies logistics and supports material compatibility across the assay workflow.

Ordering

Contact HEBEI FIZA TECHNOLOGY CO., LTD. directly with your formulation recipe, required quantities, packaging preferences, and destination country. Consultation is available upon request, and prompt international shipping is offered for confirmed orders.

All details on this page are drawn from confirmed HEBEI FIZA TECHNOLOGY CO., LTD. product documentation. Specifications and availability are subject to confirmation at the time of inquiry.