Project Overview
This 700TPD hard rock gold beneficiation project is situated in rural Zimbabwe, developed for locally exploited high-grade primary gold ore. Run-of-mine ore features abundant liberated coarse free gold, with average head grade stabilizing at 6g/t. This type of ore cannot adopt conventional single cyanide leaching flows, as unretrieved coarse free gold will directly settle in tailings and cause irreversible resource waste.
The mine owner planned to build a complete integrated beneficiation and smelting factory covering raw ore crushing to finished gold ingot production. After comparing multiple mining service vendors, the client signed a full-package EPC+M+O cooperation with Zhongyi. Our team took charge of ore pre-testing, process route design, plant functional partitioning, equipment fabrication, on-site erection, hot commissioning and long-term site operation management. We complied with local mining safety codes and environmental protection policies to complete construction within the agreed timeline, delivering a fully functional hard rock coarse free gold beneficiation line tailored for coarse free gold ore.
On-Site Mineral Processing Bottlenecks
- Coarse Free Gold Dissipation: A large amount of monomer coarse gold is embedded in gangue. If directly sent to cyanide leaching tanks, oversized gold particles fail to react with lixiviant thoroughly, resulting in massive precious metal waste in leach tailings.
- Unmatched Grinding Circuit: Improper grinding classification parameters easily trigger over-grinding or under-grinding. Excessive fine slime reduces cyanide reaction efficiency, while under-grinding restricts monomer dissociation of gold-bearing minerals.
- Complex Workshop Layout: The integrated production mode covering crushing, grinding, beneficiation, electrolysis and smelting requires scientific zoning; unreasonable layout will increase operating costs and hidden safety hazards.
- Strict Local Compliance Rules: Zimbabwe’s mining bureau imposes strict restrictions on cyanide storage usage and beneficiation wastewater discharge. All production facilities must be equipped with sealed leaching units and complete tailings dewatering facilities.
Customized Beneficiation Technical Route
Based on batch ore dressing tests and onsite parameter debugging, our mineral processing team formulated a mature combined beneficiation flow: one-stage grinding + two-stage closed-loop classification + pre-gravity recovery + CIL leaching + desorption electrolysis + ingot smelting + filter pressing tailings disposal. The biggest highlight of this scheme is embedding gravity recovery unit into the grinding classification circuit, realizing early interception of coarse free gold. This measure effectively lowers tailings grade and maximizes comprehensive resource utilization for the primary gold ore processing line.
Process Layout & Core Equipment Deployment
1. Crushing Circuit
Raw ore is fed quantitatively by disc feeders and delivered to spring cone crushers for secondary medium-fine crushing. Matching vibrating screening equipment is configured to control finished crushing particle size, providing stable qualified feed for the subsequent grinding workshop. The crushing area adopts closed dust removal design to satisfy local industrial safety and environmental protection requirements.
2. Single-stage Grinding & Two-stage Closed-loop Classification
Different from traditional multi-stage grinding, this project adopts single-stage centralized grinding matched with two-stage hydrocyclone classification system. Qualified crushed materials are transported to energy-saving wet grid ball mills for grinding operations. The discharged slurry is graded by two sets of hydrocyclone groups; oversize coarse materials are returned to the ball mill for regrinding to form closed-loop circulation, so as to stabilize grinding fineness and eliminate unqualified particles.
3. Pre-gravity Recovery (Key Optimization)
During the classification process, qualified slurry is shunted to dedicated gravity separation equipment. Liberated coarse free gold is recycled in advance and directly delivered to the smelting workshop for refined processing. This pre-recovery technology is the core to solve coarse gold loss, which can effectively reduce production pressure of the leaching circuit and cut overall cyanide consumption of the entire gold recovery line.
4. Carbon-in-Leach Processing
Gravity separation tailings are pumped to the thickener for concentration treatment, then conveyed to sealed CIL tanks for cyanide leaching and activated carbon adsorption. Fine-grained gold that cannot be recycled by gravity equipment is fully dissolved and adsorbed by loaded carbon. The whole leaching workshop adopts centralized anti-leakage and waste gas collection devices to standardize cyanide management.
5. Desorption Electrolysis & Smelting
Gold-loaded carbon collected from leaching tanks is sent to the desorption electrolysis system for high-temperature and high-pressure desorption and electrolysis. The obtained gold slime undergoes impurity removal and high-temperature melting in the independent smelting workshop, finally producing standard gold ingots for commercial trading.
6. Tailings Dewatering & Water Recycling
Spent leaching tailings are processed by filter presses for pressure dewatering. Solid filter cakes are stacked in anti-seepage tailings ponds in accordance with regulatory requirements. All production wastewater is collected, disinfected and settled, then recycled to crushing and grinding links, achieving zero external discharge of beneficiation wastewater.
Project Core Specifications
| Parameter | Specification |
| Project Location | Zimbabwe |
| Daily Handling Capacity | 700 tons per day (TPD) |
| Processed Ore | High-grade primary hard rock gold ore with coarse free gold |
| Raw Ore Head Grade | 6.0g/t average |
| Overall Processing Flow | Single-stage grinding + two-stage closed-loop classification + pre-gravity recovery + CIL leaching + desorption electrolysis + gold smelting + tailings filter pressing |
| Main Equipment | Raymond mill, spring cone crusher, disc feeder, wet grid-type ball mill, hydrocyclone cluster, gravity concentrator, CIL leaching tank, desorption electrolysis device, chamber filter press |
Project Site
Operational Performance
After two months of trial operation and parameter debugging, all workshops of the integrated beneficiation plant operate stably. Benefiting from the pre-gravity recovery design, the loss rate of coarse free gold is controlled below 1%. Combined gravity and cyanide leaching processing mode significantly promotes overall gold recovery, perfectly matching the characteristics of local high-grade coarse-grained gold ore. The closed water circulation system reduces the client’s daily water procurement cost, and standardized sealed leaching & tailings stacking mode helps the enterprise pass government environmental and safety inspections steadily.
Client Testimonial
“Coarse free gold loss has long been the biggest obstacle restricting our production profit. Zhongyi’s targeted pre-gravity recovery plus CIL combined process solved this core problem efficiently. Their EPC+M+O service covers plant layout, equipment commissioning and on-site staff training. All configured equipment runs stably with low maintenance cost. We are satisfied with the actual operating indicators of the project and recognize Zhongyi’s professional capability in primary gold ore beneficiation.”
Get Customized Ore Processing Solutions
Looking for reliable solutions for coarse free gold primary ore? Zhongyi specializes in customized hard rock gold beneficiation line and one-stop EPC+M+O services for various types of primary gold ore and associated gold ore. We provide ore testing, process optimization, plant construction and long-term operation management. Contact our technical team to acquire professional beneficiation proposals and accurate project budgets.
