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Bulk leach extractable gold

Decreasing the influence of coarse gold

Bulk leach extractable gold (BLEG) was developed in the 1980s to reduce the impact of nuggety gold. Today, it can be used in exploration for trace gold determinations to provide robust, consistent results. The large sample size utilised can help decrease the influence of coarse gold making results more reproducible. Samples from areas with coarse gold, can use BLEG paired with AAS or ICP-MS finish to report reproducible low-level results.


BLEG analysis

For BLEG analysis, samples up to 3kg are treated with cyanide solution and rolled to increase the interaction between the reagent and sample. Even with agitation, gold encapsulated in silica, or very large Au grains may not be fully dissolved by BLEG methods (Hoffman,et al., 1998).

Bulk leach extractable gold (BLEG) methods

Code Analyte Range (ppm) Description
Au 0.0001-10 BLEG – ICP-MS finish.
BLEG – extraction AA finish. Up to 1kg sample
Au 0.001-50
BLEG – ICP-MS finish.
BLEG – extraction AA finish. Up to 500g sample
Au 0.001-125 Au by accelerated cyanide leach using LeachWELL Assay Tabs™ with AAS finish. 4hr Leach.
500g sample request Au-AA15a
For 1kg request Au-AA15b
For 2kg request Au-AA15c
For 3kg request Au-AA15d
* Silver and copper may also be reported by these methods for an additional fee.
** Silver, Copper, Lead and Zinc may also be reported for an additional fee.



The Importance of Low Detection Levels for Gold


ALS Cyanide Leach Tech Note

04 JUL 2024