How a Gold Bar is Made at the Rainy River Mine
While the ore mined at New Gold’s Rainy River operation in Ontario may not look like anything special from the outside, what’s contained within this mineral-rich rock is something highly valuable—gold. The process to extract, concentrate, and refine this critical mineral uses a combination of highly specialized equipment and chemical processes, each designed to capture every recoverable ounce of this valuable metal from ore to pour.
The process begins with crushing the ore. Large trucks deliver material to a primary crusher that breaks it into smaller rocks. These rocks are then transported by conveyor to a storage area before grinding begins.
Next is the grinding stage, where the ore is finely ground in large rotating mills. The first mill, a Semi-Autogenous Grinding (SAG) mill, uses both ore and steel balls to break the rock into smaller pieces. Some oversized particles are separated and crushed further before being returned to the mill. After that, a ball mill grinds the material even finer.
Part of the slurry is sent through a gravity concentration system, which uses centrifugal force to separate heavier gold particles. These are further processed using a specialized system called intensive cyanide leaching, a common practice in gold mining that dissolves the gold so it can be recovered. Electrowinning is used to recover the metal, which involves using electricity to extract the gold.
The rest of the slurry flows into a thickener, a large circular tank where solids settle, separating water from the slurry. The clear water is recycled, and the thickened slurry is pumped to leach tanks, where cyanide and oxygen are added to dissolve the gold over 24 hours. Gold is then absorbed onto activated carbon in a Carbon-in-Pulp (CIP) system. Once the carbon is loaded with gold, it’s transferred to an elution system, where the gold is removed using a hot chemical solution under high pressure. The gold-rich solution is again processed by electrowinning to produce gold sludge. This material is later melted down using high heat to create doré bars which are then transported for further refining.
After the gold is extracted, the leftover slurry, or tailings, will be processed through a cyanide destruction circuit. This makes the waste slurry safe before it is pumped to a storage facility in the tailings area of the mine site.
Did you know that a portion of the doré from the Rainy River Mine is sent to the Royal Canadian Mint in Winnipeg?
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