Mining Gold by Aqua Regia
SGS has a global network of laboratories and offers you an unparalleled level of analytical expertise. There are many different analytical methods available in the industry to develop geochemical targets. There are several digestion techniques that can be used depending on the end use of the data – from very weak extraction to complete dissolution. Aqua regia extractions are good for many elements including gold and base metals. SGS experts are always available to assist you with selecting the gold (Au) analysis or assay technique that is fit for your purpose.
Aqua regia is a 3:1 mixture of hydrochloric acid and nitric acid. It is a strong oxidising mixture that dissolves many base metal sulphide minerals as well as gold and platinum. However, it is a partial leach that leaves an undigested silicate and alumina residue as well as refractory minerals such as garnet and spinel. It is possible to vary the sample size from less than 1g up to 20 to 50g depending on the target elements and their expected concentration. Sub-ppb detection limits are possible and base metal detection limits of low ppb are common.
Aqua regia digestion can result in the partial loss of volatile arsenic and antimony. Insoluble barium and lead sulphates can precipitate when sulphide is oxidised to sulphate. This is common since aqua regia is a strong oxidising agent.
SGS has an intensive, ongoing programme to monitor quality in all our labs. Dozens of our labs carry internationally and industry recognised certifications and accreditations. Scopes vary among laboratories.
Partner with SGS today and together we can see if aqua regia extractions are the best digestion technique for your gold assay needs.