With high-grade gold ore resources becoming increasingly scarce, efficient utilization of tailings has emerged as a critical component of sustainable mining practices. Gold tailings utilization encompasses two main approaches: reprocessing tailings as secondary resources to extract remaining precious metals, and repurposing tailings based on their physicochemical properties into construction materials such as cement additives, wall materials, road substrates, or as backfill material for mined-out areas. When residual gold content in tailings has economic value, secondary processing becomes particularly important.
Overview of Tailings Reprocessing Technologies
Gold tailings reprocessing technologies primarily include flotation, cyanide leaching, and gravity concentration methods. Among these, gravity concentration stands out for its environmental friendliness, simplicity, low cost, and high throughput capacity, making it widely adopted in tailings treatment. Through years of research and practice, Zexin Mining has identified three distinct application scenarios where gravity concentration technology plays a crucial role, each with unique advantages and suitable conditions.
Preliminary Processing: Foundation Role of Gravity Concentration
For tailings with complex composition or uneven particle size distribution, implementing gravity concentration as an initial processing step can significantly enhance the efficiency of subsequent mineral processing. In this application model, gravity concentration primarily serves as a pre-concentration and classification step, creating favorable conditions for subsequent fine separation.
The specific process first involves screening to classify tailings by particle size, followed by preliminary separation using gravity equipment to separate heavy minerals from light minerals. This pretreatment not only improves the processing efficiency of subsequent processes but also reduces reagent consumption and energy usage.
"By introducing gravity concentration pretreatment at the front end of the processing chain, we successfully increased the final recovery rate of specific gold tailings by over 12%," states the R&D Director at Zexin Mining. "Our specially designed spiral sluice system can process large tonnages of tailings at relatively low operating costs while maintaining high capture rates for gold-bearing heavy minerals."
Standalone Process: Gravity Concentration as Core Technology
For tailings with relatively simple mineral composition and significant density differences between valuable components and gangue minerals, using gravity concentration as the primary or sole processing technology often yields optimal results. This application approach is particularly suitable for tailings where gold exists in free form or is associated with heavy minerals.
A project implemented by Zexin Mining at an abandoned gold tailings storage facility serves as a successful example. Most of the gold in this facility existed as inclusions within heavy minerals such as iron compounds. By designing a two-stage gravity concentration process—first using shaking tables for roughing, then concentrating the enriched product, and finally regrinding the heavy sands for liberation—the project successfully increased gold grade from the original 0.8g/t in the tailings to over 16g/t in the concentrate, generating annual revenue exceeding $150,000.
This simplified process route not only requires lower investment costs and simpler operational maintenance but, more importantly, consumes only about one-third the energy of traditional hydrometallurgical processes, demonstrating a perfect combination of economic benefits and ecological efficiency.
Integrated Application: Synergistic Effects in Combined Processes
When processing complex polymetallic tailings, a single mineral processing method often struggles to achieve ideal recovery rates. Practice has proven that combining gravity concentration with other mineral processing methods to form integrated process flows can significantly enhance the comprehensive recovery benefits from tailings.
Zexin Mining's latest comprehensive processing project employs a "magnetic separation-gravity concentration" combined process. This technology first uses high-intensity dry magnetic separation equipment to separate magnetite, hematite, and intergrowths with titanium minerals and garnets from the tailings, then processes the non-magnetic products using gravity concentration to recover residual gold particles.
"The ingenuity of this combined process lies in fully utilizing the physical property differences between various minerals, allowing us to simultaneously recover multiple valuable components from the same batch of tailings," explains Zexin Mining's Technical Director. "Iron concentrate can be sold directly to steel enterprises, while gold-bearing concentrate is sent to smelters for gold extraction, achieving cascade utilization of tailings."
Through intelligent monitoring systems that make real-time adjustments to process parameters, this combined technology has increased comprehensive economic benefits by 17% compared to single processes, fully demonstrating the advantages of technological integration.
Technical Optimization and Efficiency Enhancement
When applying gravity concentration technology to process gold tailings in practical scenarios, multiple factors influence the ultimate recovery effectiveness. Material particle size is one of the most critical factors, as gravity equipment has relatively strict requirements for feed size. Zexin Mining's practice shows that for different types of gravity equipment, priority should be given to particle size analysis and mineral phase analysis to determine the optimal processing size range.
Pulp density is another important factor affecting gravity concentration performance. For shaking table operations, the optimal pulp density typically ranges between 15-25%, while spiral sluices perform best at solid contents of 25-35%. To maintain stable process conditions, automated density regulation systems are essential.
Zexin Mining also pays particular attention to the quality management of process water. In closed-circuit water recycling systems, suspended solids and chemicals accumulated in the water can affect mineral surface properties, thereby impacting separation effectiveness. Installing specialized water treatment facilities to ensure consistency in process water quality has become a standard configuration in Zexin Mining's tailings treatment projects.
Ecological Benefits and Sustainable Development
The value of tailings reprocessing extends far beyond the direct economic returns from recovered metals. By extracting valuable components from tailings, the storage volume in tailings dams can be reduced, lowering safety risks and environmental pressure associated with tailings storage facilities. Processed tailings, having had most sulfides and heavy metals removed, present significantly reduced environmental hazards.
From a resource efficiency perspective, each ton of gold recovered from tailings is equivalent to avoiding the ecological impact of mining approximately 100 tons of raw ore, including reduced land disturbance, water conservation, and lower energy consumption. Additionally, tailings particles after gravity treatment exhibit more uniform size distribution and more stable physical properties, making them more suitable for backfilling mined-out areas or preparing various construction materials.
Future Outlook
Zexin Mining emphasizes that the selection of tailings treatment solutions must be based on comprehensive mineralogical analysis and techno-economic assessment. Only by precisely matching tailings characteristics with process parameters can optimal recovery effects and economic benefits be achieved. Looking forward, we will continue to dedicate ourselves to innovation and optimization of gravity concentration technology, promoting sustainable utilization of mining resources and contributing to the development of a circular economy.
