Method and Materials Case Study: Dak Sa gold mine is located in Phuoc Son district, Quang Nam province in the South Central Coast region of Vietnam. It is currently Vietnam's largest gold mine, with a deposit of 30 tonnes, processing capacity of 180000 ore tonnes /y. Choosing suitable cyanide treatment process Choosing suitable cyanide treatment process requires the consideration many factors such as processes for treatment untreated solutions or slurries and the desired level of treatment. Several proven and effective chemical treatment processes have been developed for the removal of cyanide from gold ores processing. In Đak Sa gold ore processing plant, the Inco sulphur dioxide/air process has been selected appropriately in reducing free and weak acid dissociable (WAD) cyanide concentrations to low levels for discharge. Wastewater containing cyanide are treated in a two-stage chemical destruction to decrease the concentration of residual cyanide and heavy metals in the wastewater before discharging to a surface impoundment then the tailings pond. Cyanide treatment process has been investigated. Samples were collected in the tailings pond in Dak Sa gold mine from August 2021- March 2022. The level of cyanide and metal levels the samples were measured at the laboratory in the center for environment consultancy and technology (CECT).