I. Background
Placer gold ore belongs to alluvial, proluvial, or coastal placer deposits. During natural weathering and transport, gold has already been liberated from gangue and mostly exists as individual particles in gravel, with almost no sulfides, so it can be separated without grinding. Compared with lode gold ore, placer gold ore is easier to process and requires a shorter flow. However, if the process configuration is unreasonable, fine gold is likely to be lost with water, and coarse gold may also be lost in the washing and screening stages.
In view of the characteristics of placer gold ore — “gold already liberated as individual particles and mainly recovered by gravity separation” — Henan Hongke Heavy Machinery recommends a multi-stage gravity separation process of “washing and screening — sluice roughing — jig scavenging — shaking table cleaning”: first remove large gravel and clay by washing and screening, then recover coarse gold as early as possible with a sluice, scavenge the sluice tailings with a jig, and clean the rough concentrate with a shaking table to finally obtain heavy placer gold concentrate for smelting.
Note: The specific process and equipment selection should be based on ore particle size composition, mud content, and placer gold particle size distribution. For placer gold ore with high mud content or a large proportion of fine gold, washing, classification, or centrifugal concentrators should be added for supplementary recovery.
II. Applicable Ore Characteristics
This solution is mainly applicable to placer gold ore with the following characteristics:
Gold has been naturally liberated and exists as individual particles in gravel;
Sulfide content is extremely low, and flotation or cyanidation is almost unnecessary;
The ore is mainly gravel, and mud content varies greatly depending on the deposit;
Coarse gold and fine gold coexist and need to be recovered in stages;
It can be applied to both dredger and land-based placer gold operations, and the process can be simplified or modularized.
III. Recommended Process Flow
Process route: washing and screening — sluice roughing — jig scavenging — shaking table cleaning
Raw ore (gravel) → washing and screening (removing large gravel) → sluice roughing → rough concentrate
Sluice tailings → jig scavenging → jig concentrate
Rough concentrate + jig concentrate → shaking table cleaning → heavy placer gold concentrate (sent for smelting)
Process description:
Washing and screening: The raw gravel is first passed through a vibrating screen or rotary scrubber to remove large gravel and fully disperse clay, creating stable feed conditions for subsequent gravity separation.
Sluice roughing: The underscreen product from washing enters a fixed or belt-type sluice, where roughing is achieved by the density difference between gold and gravel to recover coarse gold as early as possible.
Jig scavenging: The sluice tailings enter a jig for scavenging to further recover coarse gold and part of the fine gold not recovered by the sluice.
Shaking table cleaning: The sluice rough concentrate and jig concentrate are combined and sent to a shaking table for cleaning to obtain high-grade heavy placer gold concentrate, which is sent for smelting.
IV. Core Equipment Configuration
Process | Equipment Available from Hongke Heavy Machinery | Function Description |
|---|---|---|
Washing and screening | Vibrating screen, rotary scrubber, feeder | Remove large gravel, disperse clay, and control feed size |
Roughing | Fixed/belt-type sluice, spiral chute | Recover coarse gold as early as possible by density difference |
Scavenging | Jig | Recover coarse gold and part of the fine gold from sluice tailings |
Cleaning | Shaking table | Further clean the rough concentrate and improve gold concentrate grade |
Supplementary recovery | Centrifugal concentrator | Recover fine placer gold and reduce fine gold loss |
Auxiliary | Conveying equipment, pumps, water supply system | Ensure stable operation of washing, gravity separation, and tailings discharge |
Equipment models and specifications should be selected and configured according to project throughput, placer gold particle size distribution, mud content, and site conditions. Hongke Heavy Machinery can assist in equipment matching and process layout based on sand samples and test reports provided by customers.
V. Advantages of the Solution
Short process and low investment: Since gold in placer gold ore has already been liberated as individual particles, washing plus gravity separation is sufficient for recovery, without the need for grinding and flotation. The process is simple, and both investment and operating costs are relatively low.
Early recovery of coarse gold: Sluice roughing is placed at the front of the process, enabling early recovery of coarse gold and reducing the risk of loss in subsequent stages.
Multi-stage gravity separation for more complete recovery: Sluice roughing, jig scavenging, and shaking table cleaning form a multi-stage recovery system that covers both coarse and fine gold.
Strong adaptability: Washing, classification, or centrifugal concentrators can be added according to mud content and the proportion of fine gold, making the solution suitable for placer gold ore from different deposits.
Easy to move and arrange in modules: Land-based placer gold operations can adopt modular configurations, while dredger operations can be equipped with on-board beneficiation systems and tailings discharge systems.
VI. Key Issues to Confirm Before Implementation
To ensure the implementation of the solution, it is recommended to complete the following work before equipment selection and process design:
Placer gold particle size analysis: clarify the proportion and particle size distribution of coarse and fine gold;
Mud content testing: when mud content is high, washing should be strengthened or classification operations added;
Confirmation of throughput and site conditions: determine equipment specifications, layout scheme, and investment budget accordingly;
Confirmation of water supply and tailings discharge scheme: clarify tailings discharge, water reuse, and environmental protection measures;
Confirmation of mining method: land mining or dredger operation requires different equipment configurations.
VII. Hongke Heavy Machinery Service Process
Sand sample property communication → Test recommendations and preliminary process design → Equipment selection and quotation → Process layout and equipment manufacturing → Installation and commissioning → Operator training → After-sales technical service
Henan Hongke Heavy Machinery can provide placer gold ore beneficiation process consulting and equipment supporting services according to customer sand samples and project requirements. We recommend that customers attach importance to placer gold particle size analysis and washing tests in the early stage of the project and determine the final process and equipment configuration based on test data.
VIII. Conclusion
The key to placer gold ore beneficiation lies in rationally configuring the multi-stage gravity separation process of “washing and screening — sluice roughing — jig scavenging — shaking table cleaning” according to gold particle size and mud content, so as to achieve early recovery of coarse gold and minimize the loss of fine gold. Henan Hongke Heavy Machinery is willing to provide pragmatic support from scheme design to equipment operation for placer gold projects with its complete set of gravity separation equipment and process supporting capabilities.
