Flotation Tailings Neutralize Reactive Sulfates in Gold Ore Processing
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Solution Overview
Problem
The high cost of lime consumption remains a significant challenge in the neutralization of pressure oxidation residues from refractory gold ores, particularly when conventional methods are used, as they require expensive neutralization agents like lime or sodium hydroxide to manage reactive sulfates such as basic iron sulphate and jarosite.
Innovation Solution
The process involves using flotation tailings rich in acid consumers to neutralize reactive sulfates produced by pressure oxidation, where the tailings are heated and contacted with the pressure oxidized slurry to partially neutralize liquid-phase reactive sulfates, followed by further neutralization with limestone or lime, significantly reducing the amount of lime and limestone required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional neutralization methods using lime or sodium hydroxide are employed, then the reactive sulfates are neutralized effectively, but the cost of neutralization increases significantly
Solution Approach 1:
The flotation tailings, which are normally a waste product from the concentrate production process, are utilized to neutralize the reactive sulfates in the pressure oxidation discharge. This self-service approach converts a waste stream into a useful neutralizing agent, reducing the need for external lime or sodium hydroxide additions while maintaining effective neutralization of basic iron sulfate and jarosite.
Solution Approach 2:
Instead of discarding the flotation tailings as waste material, the process recovers their neutralizing capacity by adding them to the pressure oxidation discharge. This recovery approach extracts value from what would otherwise be discarded material, significantly reducing lime consumption while effectively managing the reactive sulfates.
2Reliability
If more lime is added to neutralize reactive sulfates, then the neutralization is more complete, but the process cost increases
Solution Approach 1:
The flotation tailings serve as a cheap, readily available neutralizing agent compared to expensive lime or sodium hydroxide. Although the tailings have limited neutralizing capacity, they provide sufficient neutralization for the reactive sulfates at a fraction of the cost of conventional agents, making the process more economical.
Solution Approach 2:
The flotation tailings act as an intermediary substance between the reactive sulfates and the final neutralized product. They provide a cost-effective medium through which the neutralization reaction occurs, reducing the need for direct addition of expensive lime while achieving the desired neutralization completeness.
3Quantity of substance
If flotation tailings are used to neutralize reactive sulfates, then lime consumption is reduced, but the complexity of the process increases
Solution Approach 1:
The neutralization step is merged with the existing process flow by incorporating flotation tailings addition at the pressure oxidation discharge stage. This combining of functions allows the tailings to perform neutralization as part of the existing process sequence, reducing lime consumption without requiring separate, complex neutralization systems.
Solution Approach 2:
The flotation tailings serve multiple functions: they act as a neutralizing agent for reactive sulfates, serve as a source of additional acid consumers (carbonate minerals), and utilize an existing waste stream from the concentration process. This multi-functionality reduces process complexity by eliminating the need for separate neutralization systems while achieving effective sulfate management.
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 substantially decreases lime and limestone consumption, making the precious metal recovery process more economical by utilizing the acid consumers in the flotation tailings to neutralize reactive sulfates, thereby reducing the need for expensive neutralization agents.
Implementation Method 1
contacting the heated tailings with the liquid component of the pressure oxidized slurry to neutralize, at least partially, liquid-phase reactive sulfates
Implementation Method 2
the tailings are heated and contacted with the pressure oxidized slurry
Implementation Method 3
Pressure oxidation oxidizes sulfide minerals, rendering the residue non-refractory. These two iron compounds are very desirable because they are chemically stable.
Data Source
AI summary
The present invention is directed to flotation of refractory gold sulfide ores and to pressure oxidized residue neutralization using flotation tailings that have been contacted with an off gas of pressure oxidation.