Editor’s Note: We recently received a question from a scrap metal recycler who read our blog article Catalytic Converter Theft in The News Again, and wanted to know how to calculate the ppm weight of catalyst material analyzed on a handheld XRF analyzer. We have answered the question below as it pertains to a Thermo Scientific™ Niton™ handheld XRF analyzer featuring a calibration for Automotive Catalysts.
Thank you for your question.
Our handheld XRF analyzer featuring a calibration for Automotive Catalysts can display in real time the concentrations of the precious metals platinum (Pt), palladium (Pd) and rhodium (Rh) contained in ceramic catalytical converters.
First of all, the catalytical converter has to be crushed and ground to a fine powder of ideally 250 µm and less (use mortar/grinders and sieves if necessary). Then the fine powder is introduced into a sample cup and subsequently analyzed.
The aim of most handheld XRF users is to determine the value of the pulverized materials. However, the user may face some difficulties in juggling with the different systems of units commonly used in this business.
For a given precious metal element “E” (Pt, Pd or Rh), the value V(E) of this element in the powder is equal to the product of the concentration C(E), the weight of the powder W, the market price of the element P(E) and the discount rate DR for recycling.
The total value of the powder V is the sum of the values calculated for platinum (Pt), palladium (Pd) and rhodium (Rh).
The different terms of the formula given above shall use consistent systems of units, which are described in the following:
C(E) is the concentration of the element E in the powder, which directly depends on the measured value M(E) with handheld XRF and the used unit for M(E) either ppm or %.
W is the weight of the powder measured on a scale in kilograms (kg), metric tons (tons) or pounds (lbs).
P(E) is the market price of the precious metal, it can be expressed in currencies such as € or $ and can be found on websites such as kitco.com, pmm.umicore.com, platinum.matthey.com, etc. Depending on the currency and reference used, € per kilogram, $ per troy ounce, and the desired currency, the market price can be calculated as follows. CRR is the conversion rate for 1€ in $
DR is the discount rate in % , which is the margin of the buyer vs. market price
Assuming a discount rate DR of 30% and a mass of a single converter ceramics of 0.900 kilogram
The handheld XRF analyzer displays measured values M(E) of 0.240% Pt, 0.600% Pd and 0.030% Rh
Market price are for Pt, Pd, and Rh respectively 32260 €, 73137€ and 762980 € per kilogram
Hence the value in Euro is:
V(Pt) = 0.240/100*0.900*32260*(100-30)/100 = 48.77€
V(Pd) = 0.600/100*0.900*73137*(100-30)/100 = 276.46€
V(Rh) = 0.030/100*0.900*762980*(100-30)/100 = 144.20€
Total Value V = 469.43€
Assuming a discount rate DR of 30%and a mass of a single converter ceramics of 2 lbs
The handheld XRF analyzer displays measured values M(E) of 2400ppm Pt, 6000 ppm Pd and 300 ppm Rh
Market price are for Pt, Pd, and Rh respectively $1184, $2684€ and $28000 per troy ounce
Hence the value in $ is:
V(Pt) = 2400/1000000*2*0.4536*1184/0.0311*(100-30)/100 = $58.02
V(Pd) = 6000/1000000*2*0.4536*2686/0.0311*(100-30)/100 = $329.07
V(Rh) = 300/1000000*2*0.4536*28000/0.0311*(100-30)/100 = $171.52
Total Value V = $558.62
I hope that answers your question. We welcome other questions about handheld XRF analysis as well.