Automated gold search and applications in process mineralogy

摘要

An image-analysis program written at CANMET per-forms anautomated search for precious minerals. The program can search, for example,for gold minerals in polished sections. The search involves a meander ofapproximately 100 x 100 fields (Back-scattered electron images) at amagnification of x400, which allows gold grains as small as 1 #mu#m indiameter to be detected. Typically, an overnight search of a -45-#mu#m productwill scan ca 1 500000 particles, providing data that are not easily obtainedthrough manual operation of an optical microscope. The program follows thesequence: location of grains of correct brightness; acquisition of gold X-rays(AuL#alpha#) from such grains by wavelength-disper-sive spectrometry; filteringto remove artefacts; and recording of the images and stage location for subse-quent retrieval. At the end of the run the program allows the operator to verifyand identify the grains so found. The approach has already been applied in manystudies of gold ores for commercial clients and three case histories are described.