What is the gold processing plant target ?
The primary objective is concentration and purification. Mined ore might contain only a few grams of gold per tonne (g/t). The plant concentrates this significantly, producing a final product (like doré bars) that can be easily transported and sold to refineries for further purification into pure gold bullion. Without the processing plant, the mined rock has little economic value. It transforms raw geological resources into tradable commodities.
How to Chose a suitable Gold processing plant ?
Detailed ore testing (mineralogy, metallurgical tests) is crucial. It reveals gold’s form (free, locked, refractory), particle size, associated minerals, and how it responds to different recovery methods, directly guiding flowsheet selection.
1. Mineralogy: Identifying all minerals present, their proportions, and textures. Crucially, understanding how gold occurs (its “deportment”).
Metallurgical Testing (Process Amenability): Lab and pilot-scale tests simulating different processing routes (gravity, flotation, leaching) to determine the best recovery method, reagent consumptions, and achievable recovery rates.
2.Key Ore Properties
Gold Deportment: Is the gold present as free-milling native gold? Is it finely disseminated within sulfides (like pyrite or arsenopyrite)? Is it locked within silica? Is it chemically combined (tellurides)? This dictates the processing complexity.
3. Particle Size: The size of the gold grains determines the required grinding fineness for liberation. Coarse gold might suit gravity recovery.
Ore Type: Is it easily leached oxide ore? Or refractory sulfide ore needing pre-treatment (like roasting or pressure oxidation)? Is it alluvial (placer) requiring washing and gravity methods? Are there troublesome elements like arsenic or carbon (preg-robbing)?
4.Understanding Liberation & Variability
Liberation vs. P80: Simply grinding to a target size (e.g., P80 passing 75 microns) isn’t enough. Insight: Detailed mineralogy reveals if the gold is actually freed in a recoverable form at that grind, or if it remains locked. Designing based only on P80 can lead to poor recovery if liberation isn’t understood.
5.Handling Ore Variability:
Test work often uses averages. Insight: Real ore feed varies daily. A robust plant must be designed with flexibility to handle expected variations in grade, hardness, mineralogy, and clay content, not just the average. Designing only for the average courts failure.
6. Byproduct Value
Does the ore contain significant silver, copper, lead, or zinc? A comprehensive testing program will identify these, allowing the design to incorporate circuits for their recovery, adding potential revenue streams.
CIL/CIP: The Workhorse
Carbon-in-Leach (CIL) / Carbon-in-Pulp (CIP): Gold is leached using cyanide solution, and simultaneously (CIL) or subsequently (CIP) adsorbed onto activated carbon.
Best For: Ores where gold is finely disseminated and readily leachable after grinding. Widely used for its efficiency.
Pros: High recovery for suitable ores, well-established technology.
Cons: Requires significant capital investment, uses cyanide, less effective for very coarse gold or some refractory ores.
