How does pre-burning influence precious metals returns from spent hydrocarbon process catalysts?
Answers
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24/07/2007
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A:
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Richard De Santis, Sabin Metal Corporation, rjdesantis@sabinmetal.com
To accurately determine the amount of precious metals remaining in spent hydrocarbon process catalysts, the catalysts must first be sampled by a series of complex and meticulous procedures. Fundamentally, the principle of sampling involves reducing large quantities of spent precious metal-bearing material (as much as many tons) into small quantities (as little as a few grams). Samples are then extracted for analysis from different fractions and/or different stages of the resultant sub-lot.
The sampling procedure begins by converting precious metal-bearing materials into a homogeneous, free-flowing mass so that molecules of precious metals and other constituents are evenly distributed. Results of sampling the homogeneous mass thus represent an accurate ratio of the precious metals content in the overall matrix.
Spent precious metal-bearing catalysts usually exhibit high loss-on-ignition (LOI) characteristics; this is due to moisture, volatile hydrocarbons and contaminants such as sulphur and carbon. Before spent catalysts can be accurately sampled, contaminants (which have accumulated during their useful lives) must first be removed. Their presence prevents an accurate – and thus fair – determination of remaining precious metals in the entire catalyst lot. Not only is it vital to remove these unwanted elements from the catalyst lot prior to sampling, it may also be required for safety and environmental compliance, as the material is subsequently refined. Pre-burning removes these contaminants to help assure a homogeneous, free-flowing lot prior to sampling procedures.
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