Pt 29.543 Pd 39.838 Rh 110.92 Au 61.71 Ag 0.752

Resources & Articles

Precious Metals in Dental Scrap (Crowns & Bridges)

Some dental scrap, such as crowns and bridges, are a rich source of precious metals, mainly Gold and
Palladium .
The use of precious metals for crowns, bridges and some other dental restorations has been known and
implemented for years.
Below are some of the main alloys in dental restoration use:
High Gold – 60-90% Au
High Palladium – 50-80% Pd
Mix Gold Palladium & Platinum – with total of 60-98% PM
Pallacast – Palladium Silver (~25% Pd 70% Ag may also contain 3% Au)
In most markets, “base metals” such as Cobalt, Chrome and Nickel are mainly
used as dental alloys. Thus, the dental scrap is a mix of unknown crowns and
bridges, and also the precious metals content is unknown.
The following process is suggested in order to determine the value of the scrap:
Collection – The scrap (crowns and bridges, metal powder) may be collected from dental labs & dental clinics
Separation – When scrap quality is low (high Co, Cr, Ni content) then “Pre XRF assaying” to the bridges could be an advantage, in order to
separate the non-precious bridges from casted scrap. The resulting ingot will be much more homogeneous.
Casting – The preferred method is by induction furnace, adding fluxes to absorb all ceramic and dirt from the casted ingot.
Sampling – There are two main techniques to assay the scrap :
1. Using “Vacuum Pin Tubes” to produce a sample from a molten
metal pool.
2. Drilling the ingot – it is important to drill from top and bottom
minimum 2 points each.
Assay – There are a few methods for assays. A preliminary XRF assay,
before sending the scrap to the refiner, is a sufficient method. The
main point is to make sure that the ingot is homogeneous (if both
samples, bottom and top, have the same results).
Refining – The actual refining of precious metals is a complex process, as well as selling the metal (especially Pd, Pt, Rh). You probably need a reliable refinery. Please take a look at our article “Cost Structure of Precious Metals Refining”

Ami Gur
AG Metals Ltd.
Precious Metals Expert since 1996

word image 9
word image 8
word image 26