Our gold deposits start from the surface of an initial pit in Bukit Mantri and the adjacent 2 new pits in Bukit Panjang and Bukit Botak. We are using surface mining techniques by digging into the earth’s surface one layer at a time because the ore bodies are relatively shallow.
First, we will perform grade controls to determine the content of gold in the area to be mined. Thereafter, we will drill holes into the ground and fill them with explosives. After the rock has been broken up by blasting, it is loaded into trucks using excavators. Rocks containing gold and silver are then sent to the processing plant or stockpiling. Rocks with minimal gold content are sent to waste dumps and kept for rehabilitation purposes.
When operating a mine, we use stringent controls to prevent or mitigate any environmental impacts. Our environmental management systems are designed to ensure all environmental considerations – including management, monitoring, maintenance, training and action plans – are incorporated within an overall framework as an integral part of our mining operations.
At all times, Bahvest will operate in compliance with applicable laws, regulations and other legal requirements.
Trucks transport the ore from the mining pits to processing operations. Some ores may be stockpiled for later processing.
We feed ore into a series of crushers and ball mills to reduce the size of the ore particles and expose the mineral. Water is also added, which turns the ore into a slurry. We send this slurry to leaching tanks, where we add cyanide solution to the slurry, which leeches gold and silver into the solution. This process removes the gold and silver from the ore. Carbon granules are then added to the solution. The gold attaches to the carbon and is pulled from the solution. We then “strip” the gold from the carbon by washing it with a caustic cyanide solution. The carbon is later recycled. Next, we pump the gold-bearing solution through electrowinning cells, which extract metals from the solution using an electrical current.
After gold has been processed, the leftover waste materials are called tailings. Tailings contain small amounts of cyanide and other hazardous chemicals, so they must be disposed of in an environmentally safe way. We use a state-of-art Filter Press system to recycle all the wastewater and reuse them in the production system. The tailings which now consist only solid waste are stored in tailings dams, which are lined with impermeable layers. While the cyanide levels in the dam are minimal and safe, steps are taken to keep wildlife away from the dams.
We then smelt the gold, melting it in a furnace at about 1,200 degrees celsius. From there, the liquid gold is poured into molds, creating doré bars. Doré bars are unrefined gold bullion bars containing anywhere from 60 to 95 percent gold. We finally sell the bars to a refinery for further processing into pure gold.