Sabin’s advanced sampling procedures maximize recovery of precious metals from your process or product
To accurately determine the amount of precious metals present in materials for recovery Sabin Metal’s refining plants use three different sampling techniques. These are dry sampling, melt sampling, and solution sampling. Each of these techniques offers specific advantage; selection of the appropriate method depends upon the type of material being processed as well as its estimated precious metals content.
Fundamentally, the principle of sampling involves “reducing” large quantities of 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 scrap materials into a homogeneous 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.
Melt sampling is a process in which a carrier metal such as copper is melted along with the material, with the resulting molten metal poured into ingots which are sampled at the beginning, middle, and end of the pour. Subsequent processing steps yield and extremely high degree of accuracy, with tolerances as close as ± .1% between samples. This technique is generally used with high-grade materials that contain significant amounts of precious metals.
Solution sampling is used for precious metal bearing solutions; it is cost- effective and extremely accurate in determining precious metals content by volume. This technique also involves achieving a homogeneous dispersion of precious metals and other constituents to the molecular level with precisions comparable to melt sampling. Multiple samples are also taken from different parts of the solution for further analysis. In addition to gold cyanide or palladium electroplating solutions, materials that can be easily dissolved in a reagent (such as materials containing palladium) are also sampled with his technique.
Dry sampling used when materials cannot be dissolved in a solution or are inappropriate to melt either because of their structure, or because of the costs associated with melting vs. the possible return. Because it is difficult to achieve homogeneity dry sampling is more complex and potentially less precise than melt or solution sampling. Materials for dry sampling are homogenized, generally by grinding large pieces into smaller and ever finer particles. The material is allowed to fee fall in a stream into a cross cut, timed automatic sampler. Representative samples are taken periodically, generally achieving a sampling accuracy of ± 2%. Precious metal bearing catalysts are usually sampled with this technique. Depending upon the combination of substrate and metal, organics may be burned off prior to dry sampling. Some precious metal bearing materials can be sampled by only one of the three methods described; however, others may be processed by more than one method. Determining which one to use, and when, can be critical with regard to maximizing precious metals recovery. Considerations involve estimating the value of precious metals content in your materials, cost-effectiveness of using one method over another for the highest possible returns, and its practicality which is a function of refining costs, materials value, and other factors.