1. Core Challenges in Hard Rock Gold Processing
Hard rock gold ores are categorized into oxide ores (free gold or oxidized forms) and sulfide ores (gold locked in sulfides). For small-scale operations (1-2t/h), gravity separation is critical due to its low energy consumption and chemical-free operation.
2. Oxide Gold Ore Processing Flow
Characteristics: Oxide ores are typically rich in free gold particles that are not encapsulated within sulfide minerals. For these ores, gravity separation is highly effective due to the density differences between gold and gangue minerals. Techniques such as panning, sluicing, and using gravity concentrators (e.g., shaking tables or centrifugal concentrators) can efficiently recover gold particles. Incorporating gravity separation early in the processing flow allows for the efficient extraction of coarse gold, reducing the load on subsequent processing stages.
Recommended Flow:
Crushing & Grinding
Primary crushing (jaw crusher, feed ≤150mm) → Secondary crushing (hammer mill, output 0-10mm) → Wet ball milling (80% passing 0.074mm).
（鄂破+球磨机选矿现场图片）
Gravity Pre-concentration
Jig Separator (JT Series): Recovers coarse gold (>0.1mm) in grinding circuits, 65%-75% recovery.
Shaking Table (6S Series): Cleans jig tailings for 0.037-0.5mm fines, enrichment ratio up to 300:1.
Cyanidation
Tails from gravity units undergo cyanide leaching, achieving 85%-90% total recovery.
Advantages: Reduces cyanide consumption and tailings liability.
3. Sulfide Gold Ore Processing Flow
Characteristics: Sulfide ores present a more complex challenge due to gold being locked within sulfide minerals like pyrite or arsenopyrite. Gravity separation alone is insufficient for these ores. A combined approach is often employed:
Recommended Flow:
Crushing & Grinding
Three-stage crushing (jaw + cone crushers) → Closed-circuit ball milling (65% passing 0.074mm).
Gravity-Flotation Combination
Centrifugal Concentrator (LY Series): Recovers semi-liberated coarse gold (0.03-0.5mm), 50%-60% recovery.
Flotation: Xanthate collectors recover sulfide-bound gold, 85%-92% flotation recovery.
Concentrate Treatment
Roasting/bio-oxidation followed by cyanidation, achieving 90%-95% total recovery.
Advantages: Gravity pre-concentration reduces overgrinding and flotation costs by 15%-20%.
4. Gravity Equipment Selection & Operation
Jig Separator (JT Series):
Feed size: 0.1-5mm; Dual chambers enhance stratification.
Parameters: Stroke 8-12mm, frequency 200-300 RPM.
Shaking Table (6S-4500):
Water consumption: 2-3m³/t; Adjustable tilt (2°-5°).
Centrifugal Concentrator (STLB30):
200G force, 1-1.2t/h capacity for fine gold.
Maintenance: Clean decks regularly; Monitor water flow stability.
5. Economic & Environmental Benefits
Capital Cost: Gravity units account for 30%-40% (15k−25 thousand for jig + table).
Operating Cost: Energy ≤1.5kW·h/t, zero chemical reagents.
Compliance: Cyanide-free, ISO 14001 compliant.
