A bottle roll test is the standard first-stage laboratory test for gold and silver cyanidation. A ground ore sample (typically 1–2 kg) is sealed in a rolling vessel with cyanide solution and tumbled for 24 to 96 hours. The recovery, cyanide consumption, lime requirement, and leach kinetics are measured — the foundational data for every downstream flowsheet decision.
What It Measures
Four key parameters: (1) Recovery — what percentage of the contained gold/silver dissolves into solution. (2) Cyanide consumption — how much NaCN is consumed per tonne of ore. (3) Lime requirement — how much lime is needed to maintain optimal pH (10.5–11). (4) Leach kinetics — how quickly recovery progresses, plotted as a curve over time.
Procedure
Crush ore to target size (e.g. P80 of 75 µm). Place 1–2 kg in a sealed vessel — KCA uses the patented LIFTERBOTTLE™ single-mold rolling vessel for repeatable results. Add cyanide solution and lime, seal, and roll for 24–96 hours. Sample the solution periodically, assay for Au and Ag, calculate cumulative recovery.
Why It Matters
Bottle roll results feed directly into the heap-leach feasibility decision. If a bottle roll shows 85% recovery at 0.5 kg NaCN/t consumption, the project is likely economic. If it shows 40% recovery at 5 kg NaCN/t, the ore is refractory and needs different processing.
Beyond Bottle Roll
Bottle roll is the first-stage screen. Promising ores then move to column leach testing for heap-leach simulation, or to CIL/CIP bench tests for milling flowsheet evaluation. KCA's Reno laboratory runs 100+ projects per year with the full progression.
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