Key Technologies for the Harmless Disposal of Gold Concentrate Cyanide Residue

The cyanidation process for gold extraction, boasting a history of over 100 years, still prevails in current gold industrial production. Its popularity stems from its simplicity and high gold recovery rate. Nevertheless, this process generates a large quantity of gold tailings. The output of cyanide residues from gold concentrates has been increasing annually. Statistics indicate that the national gold industry churns out approximately 80 million to 100 million tons of cyanide residues each year.

Long - term stockpiling of these cyanide residues creates multiple problems. Firstly, it occupies a vast amount of land. Secondly, the highly toxic cyanides in the residues can release toxic gases and form acidic wastewater. Additionally, various metal ions can contaminate surrounding water bodies and soil via surface water or groundwater, endangering human health. Paradoxically, cyanide residues from gold concentrates contain valuable resources like Cu, Pb, Zn, Fe, Au, S, and Si that remain under - recovered. Thus, safely dissociating toxic components, efficiently separating and recovering valuable resources, and achieving large - scale utilization of de - cyanided tailings have become global research priorities and challenges.

United Chemical Co., Ltd.’s Solution: A Holistic Project

In response to these challenges, United Chemical Co., Ltd. initiated the “Research and Application of Key Technologies for the Harmless Disposal and Resource Utilization of Cyanide Residues from Gold Concentrates” project.

Gradient - Controlled De - cyanidation and Flotation Recovery

The “New Technology for Gradient - Controlled De - cyanidation and Flotation Recovery of Valuable Elements” was adopted to comprehensively recover Cu, Pb, and Zn from gold cyanidation tailings. As a result, lead concentrates and copper concentrates were produced.

Pyrite Interface Activation and Combined Processing for Iron and Gold Recovery

Next, the “New Technology for Pyrite Interface Activation and Combined Mineral Processing and Metallurgy for Iron and Gold Recovery” was implemented. This technology efficiently separated and recovered Fe and Si from the de - cyanidated flotation tailings, yielding sulfur concentrates and high - silicon tailings.

Sulfuric Acid and Iron Pellet Production

Sulfur concentrates were used to produce concentrated sulfuric acid through weak - oxygen roasting. The roasted sulfur slag was pelletized. Subsequently, the “High - Temperature Iron - Gold Separation Technology” was applied to produce iron pellets and gold mud enriched with Cu, Pb, and Zn.

High - Silicon Tailings Recycling

The “New Technology for Phase - Change Regulation and Full - Component Recycling of High - Silicon Tailings” enabled the transformation of high - silicon tailings into European - style interlocking ceramic tiles.

Technical and Research Breakthroughs

This project tackled the “four difficulties” associated with cyanide residues from gold concentrates: accurately understanding toxic components, regulating and directionally separating their behaviors, recovering valuable components, and recycling tailings. It introduced an innovative interdisciplinary approach, integrating mineral processing, metallurgy, and environmental science. The research spanned the entire innovation chain, from uncovering scientific causes to developing control technologies and conducting engineering demonstrations.

On the scientific and technological front, it systematically revealed the occurrence patterns of toxic components in cyanide - containing highly toxic hazardous waste. At the application level, it developed technologies for the safe dissociation and stable disposal of toxic components, the coordinated extraction of valuable components, and the high - value utilization of tailings resources.

Impressive Industrial Application Results

After the industrial application of the project's achievements, the recovery rate of valuable metals from cyanide residues of gold concentrates exceeded 90%. This accomplishment realized the Harmless disposal and full - component Resource utilization of cyanide residues from gold concentrates. Annually, the project produced around 8.000 tons each of lead concentrates and copper concentrates, over 300.000 tons of high - sulfur concentrates, over 200.000 tons of concentrated sulfuric acid and oxidized pellets, approximately 700 kg of gold, and more than 90 million European - style interlocking tiles. Evidently, the project has brought about remarkable economic, environmental, and social benefits.