Gilded scrap boasts stable gold content and high recycling value, covering gilded electronic parts, hardware and industrial accessories. Unlike ore gold smelting, scrap gold recovery focuses on high-efficiency stripping, enrichment and low-loss purification. The mainstream industrial processes include pyrolytic stripping, chemical wet stripping and electrolytic refining.
As a professional manufacturer of full-set gold stripping equipment, we provide standardized and customized recycling production lines with complete technical support. This article concisely presents the core processes, standard formulas, key parameters and equipment advantages for gilded scrap gold extraction.
1. Pyrolytic Gold Stripping
Suitable for thick and large gilded workpieces, this physical high-temperature process features stable operation. Gilded scraps are immersed in molten electrolytic lead (melting point: 327℃) to let gold fully infiltrate into lead liquid. After removing base materials, the gold-bearing lead is cast into precious lead ingots.
Gold and silver can be separated and purified via cupellation or electrolysis. Silver is added in cupellation to form gold-silver alloy. After water quenching, nitric acid parting produces pure gold powder, which is melted into crude gold ingots. Hydrochloric acid is used to recover silver from nitric acid leachate.
2. Chemical Wet Gold Stripping
This universal process applies to most thin-layer gilded small scraps with fast stripping speed. The standard stripping solution is formulated with 75g sodium cyanide (NaCN) and 75g sodium m-nitrobenzenesulfonate per 1000mL water. Adding citrate enables full gold stripping within 3-5 seconds.
Operation Steps: Heat the solution to 90℃ and soak scraps for 1-2 minutes until gold is fully dissolved. Rinse stripped substrates with distilled water three times and reserve the rinsing water for reuse. Dilute saturated gold-bearing solution at 1:5 ratio, adjust pH to 1-2 with hydrochloric acid in a fume hood, then use zinc plates/wires to replace gold.
After precipitation, clean gold powder with water and boil in sulfuric acid to remove zinc impurities. Finally, dry and melt the purified gold powder to obtain crude gold ingots. Replace the stripping solution once it is saturated and ineffective.
3. Electrolytic Purification & Recovery
Electrolysis is adopted for high-purity gold recovery and waste liquid recycling, ideal for refined mass production with a gold recovery rate over 99.5% and gold purity up to 99%.
Standard Electrolytic Parameters: 6V DC voltage, 0.3-0.5A/dm² cathode current density, 40-60℃ constant temperature, 4-8h electrodeposition. Stainless steel serves as the cathode and graphite as the anode.
Electrolytic tail liquid can be recycled by supplementing cyanide and m-nitrobenzenesulfonate, greatly reducing reagent costs and achieving eco-friendly closed-loop production, despite slightly higher equipment and process requirements.
4. Our Equipment Advantages
We supply full-set professional gold stripping and extraction equipment compatible with all three mainstream processes. Our intelligent production lines feature high recovery rate, safe and compliant operation, low consumption and recyclable waste liquid. We provide one-stop services including equipment customization, installation, commissioning and technical training, helping recycling factories achieve efficient and stable gold production.
5. Process Selection Guide
Choose pyrolytic stripping for thick large gilded parts, chemical stripping for universal small thin gilded scraps, and electrolytic purification for high-purity, low-cost cyclic mass production. Matched with our professional supporting equipment, all processes can maximize scrap gold recovery benefits.
