MCF2 Process for Refractory Gold Ore Recovery
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Solution Overview
Problem
Refractory gold ores are challenging to process due to gold being occluded in sulfide mineral grains or adsorbed by carbonaceous material, leading to low gold recovery rates, especially in double refractory ores where both issues occur, and conventional flotation methods face difficulties with fine-grained sulfides and carbonaceous matter, resulting in poor selectivity and high reagent consumption.
Innovation Solution
The MCF2 process involves multiple stages of comminution and flotation, controlling mineral liberation, classification, and chemistry to optimize gold and silver recovery, using sulfide activators, pH adjustment, and dispersants to inhibit sliming and oxidation, and employing a staged approach to selectively float gold-bearing sulfides while suppressing non-sulfide minerals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional flotation methods are used on refractory gold ores, then the process is simple and operates at standard conditions, but gold recovery is low due to occlusion in sulfide grains and preg robbing by carbonaceous material
Solution Approach 1:
The flotation process is divided into multiple stages: rougher flotation to remove carbonaceous material and gangue, followed by cleaner flotation to concentrate gold-bearing sulfides. This segmentation allows each stage to target specific minerals and resolve the contradiction between simple operation and high gold recovery.
Solution Approach 2:
Carbonaceous material is depressed and removed in the rougher flotation stage before the cleaner stage processes gold-bearing sulfides. This preliminary removal of preg-robbing material prevents gold loss and enables high recovery in subsequent stages.
2Manufacturing precision
If fine grinding is applied to liberate gold from sulfide grains, then gold liberation is improved, but over-grinding occurs causing oxidation of sulfides and generation of slimes that reduce flotation selectivity
Solution Approach 1:
The grinding process uses dynamic classification with cyclones to separate liberated particles from unliberated material at different stages. This allows optimization of grind size for each mineral type and prevents over-grinding of gold-bearing sulfides while achieving sufficient liberation.
Solution Approach 2:
The process uses feedback from rougher flotation performance to adjust grinding intensity. By monitoring recovery and grade in rougher concentrates, the system optimizes grind size to achieve maximum gold liberation while minimizing sulfide oxidation and slime generation.
3Productivity
If flotation reagents are increased to improve recovery of fine-grained sulfides, then gold recovery improves, but reagent consumption increases and selectivity decreases
Solution Approach 1:
Different reagent packages and dosages are applied at different stages: rougher flotation uses reagents optimized for carbonaceous material depression, while cleaner flotation uses reagents optimized for gold-bearing sulfide concentration. This local optimization reduces overall reagent consumption while maintaining high recovery.
Solution Approach 2:
The process changes flotation parameters including pH, aeration rate, and reagent dosages between stages. Cleaner flotation operates at optimized parameters that enhance selectivity and reduce reagent consumption compared to rougher flotation, resolving the contradiction between recovery and reagent use.
4Manufacturing precision
If multiple flotation stages are implemented to enhance selectivity, then flotation selectivity improves and reagent consumption reduces, but process complexity increases
Solution Approach 1:
The flotation circuit is segmented into rougher and cleaner stages with distinct objectives. The rougher stage handles bulk removal of non-sulfide minerals and carbonaceous material, while the cleaner stage concentrates gold-bearing sulfides. This segmentation achieves high selectivity without excessive complexity.
Solution Approach 2:
The flotation circuit design uses standardized cells and reagent packages that can be applied across different ore types. The multi-functional rougher-c cleaner configuration handles both carbonaceous and non-carbonaceous refractory ores, reducing overall system complexity while maintaining high selectivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The MCF2 process achieves high gold and silver recoveries by controlling liberation and chemistry in multiple stages, reducing over-grinding and oxidation, and enhancing flotation selectivity, resulting in improved concentrate grades and reduced reagent consumption, with gold recovery exceeding conventional methods at higher concentrate sulfur grades.
Implementation Method 1
Froth flotation uses differences in physico-chemical surface properties of particles to float various minerals. After treatment with reagents, such differences in surface properties between the minerals within the flotation pulp are emphasized as either hydrophobic (water repelling)/aerophillic (air attracting) on the one hand or hydrophilic (water attracting)/aerophobic (air repelling) on the other. Air bubbles sparged through the pulp attach to and float hydrophobic particles.
Implementation Method 2
The MCF2 process involves multiple stages of comminution and flotation, controlling mineral liberation, classification, and chemistry to optimize gold and silver recovery, using sulfide activators, pH adjustment, and dispersants to inhibit sliming and oxidation
Data Source
AI summary
The present invention is directed to flotation of refractory gold sulfide ores in which the ore is ground, floated, the tailings reground, and refloated to produce gold-bearing concentrates.