A mercury retort is a sealed heated vessel used to safely separate mercury from gold/silver concentrate before smelting. The concentrate is heated under vacuum above mercury's boiling point (357°C); mercury vapors are drawn through condensers and captured as liquid mercury for sale or safe disposal. The remaining solids (gold, silver, base-metal impurities) go to the smelting furnace.
Why Retort?
Many gold deposits contain natural mercury that ends up in the strip solution and electrowinning cathodes. Smelting Hg-bearing concentrate without retorting would release toxic mercury vapor to the gold-room atmosphere. The retort captures the mercury cleanly and produces a Hg-free concentrate for downstream smelting.
How It Works
Wet concentrate (mercury-bearing sludge from electrowinning) is loaded into trays inside a stainless-steel retort chamber. The chamber is sealed, evacuated, and heated to 400–500°C. Mercury vapor is drawn out by the vacuum, through a water-cooled condenser where it condenses into liquid mercury, and into a sealed collection vessel. The dry solid residue is removed and sent to smelting.
Multi-Stage Mercury Capture
KCA retorts use four stages of capture: (1) primary condenser, (2) shell-and-tube heat exchanger for additional cooling, (3) sulfur-impregnated carbon bed to capture residual vapor, and (4) vacuum pump maintaining negative pressure to prevent any vapor escape. Designed to meet emission limits in every U.S. state.
KCA Model R17E
Process up to 40 cu. ft of wet or dry solids per batch. Fully automated temperature and time control via Smart Controller (SCR) and Eurotherm. Skid-mounted electrical transformer, vacuum pump, and air-water separator included. See our Mercury Retorts page.
Have a project that involves Mercury Retort?
KCA’s engineering bench and Reno metallurgical laboratory have done this before. Let’s talk about your project.
Send an Inquiry