Polysulfide Depressants for Molybdenite Flotation Safety
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Solution Overview
Problem
Current molybdenite flotation processes face health, safety, and environmental concerns due to the use of toxic reagents that form hydrogen sulfide, often resulting in low recovery rates or requiring multiple stages of flotation.
Innovation Solution
The use of alkaline earth polysulfides or alkaline polysulfides as depressing reagents at elevated pH levels to maintain the oxidation-reduction potential for molybdenite flotation, separating it from copper and iron sulfides without adding metal anions or thiosulfates, and manufacturing these reagents on-site to minimize toxicity and handling risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional reagents like Sodium hydrosulfide are used for molybdenite flotation, then separation effectiveness is improved, but health and safety hazards increase due to hydrogen sulfide evolution
Solution Approach 1:
The patent changes the chemical parameters of the flotation system by using polysulfides (S3 2-, S4 2-, S5 2-) instead of traditional sulfide reagents. This substitution maintains the depressant function for copper and iron sulfides while operating at elevated pH levels (9-11), which prevents hydrogen sulfide evolution and eliminates the associated health and safety hazards while preserving separation effectiveness
Solution Approach 2:
The patent converts the harmful effect of low pH (which causes H2S evolution from traditional reagents) into a beneficial operating condition by maintaining elevated pH levels. This approach eliminates the harmful hydrogen sulfide gas while maintaining effective mineral separation through the use of polysulfide depressants that function optimally in alkaline conditions
2Productivity
If multiple stages of flotation are used to achieve high recovery rates, then molybdenite recovery is improved, but process complexity and time consumption increase
Solution Approach 1:
The patent achieves high molybdenite recovery in a single stage by changing the chemical parameters - specifically using polysulfide depressants at elevated pH levels (9-11) combined with optimized reagent dosages. This single-stage process achieves recovery rates comparable to or exceeding traditional multi-stage processes while significantly reducing process complexity and time consumption
3Manufacturing precision
If traditional reagents are used for flotation, then separation performance is maintained, but environmental hazards increase due to toxic substance handling
Solution Approach 1:
The patent changes the chemical composition and pH parameters of the flotation system by using polysulfide depressants (S3 2-, S4 2-, S5 2-) at elevated pH levels (9-11). This substitution eliminates the need for toxic traditional reagents like Sodium hydrosulfide and Ferro Cyanide, thereby removing environmental hazards while maintaining effective separation performance through the same depressant mechanism
Solution Approach 2:
The patent converts the harmful environmental impact of toxic reagent handling into a beneficial outcome by using polysulfides that do not evolve hydrogen sulfide gas and are less toxic. The elevated pH operating condition (9-11) further enhances safety by preventing H2S formation, thus eliminating environmental hazards while preserving separation performance
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
This approach achieves high molybdenite recovery with reduced hydrogen sulfide evolution, improved safety, and cost-effectiveness, comparable to traditional methods like Sodium hydrosulfide but with lower health and environmental hazards, allowing for efficient separation and recovery of molybdenite from complex ore bodies.
Implementation Method 1
a series of flotation cells, wherein various chemical treatments result in floating of molybdenite while copper-containing and iron-containing minerals do not attach to a gas bubble and therefore do not float
Implementation Method 2
chemical depressants are used to accomplish this separation in a flotation process after an initial or bulk concentrate is produced. Added reagents depress the other sulfides by inhibiting their flotation, allowing primarily just molybdenite to attach to the gas bubble
Implementation Method 3
The invention relates to the use of Alkaline (earth) Polysulfide reagents as depressing reagents in dosages such that the flotation pulp oxidation-reduction potential (ORP) is maintained in a range in which Molybdenite will float
Implementation Method 4
The use of alkaline earth polysulfides or alkaline polysulfides as depressing reagents at elevated pH levels to maintain the oxidation-reduction potential for molybdenite flotation
Implementation Method 5
achieves high molybdenite recovery with reduced hydrogen sulfide evolution, improved safety
Data Source
Figure 1
AI summary
A method of depressing copper sulfides and iron sulfides in a molybdenite floatation recovery process uses alkaline or alkaline earth potysulftdes at high concentrate pH. The method of enriching molybdenite content from a slurry having molybdenite and at least one of iron sulfides and copper sulfides can include the steps of adding an effective amount of a depressing reagent selected from one or more alkaline poly sulfides, alkaline earth polysulfides, or a mixture thereof, to the slurry, wherein the pH of the slurry is greater than about 8.0; and passing a gas through the slurry to separate material by selective flotation, recovering the molybdonite from a froth.