Bioleaching Inoculation for Chalcopyrite Passivation
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Solution Overview
Problem
Current bioleaching technologies are inefficient for processing copper sulfide ores, particularly chalcopyrite, due to passivation issues and low leaching speeds, which limits the recovery of copper from low-grade ores and incurs high operational costs.
Innovation Solution
The process involves continuous inoculation of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans microorganisms, along with native microorganisms, at high concentrations (over 5×10^7 cells/ml) and ferric ions (over 2 g/L) to enhance bioleaching speeds and prevent passivation in sulfide ore heaps, tailings, and dumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional bioleaching technologies are used on sulfide ores, then the process can be applied to oxide ores and secondary sulfides, but the leaching speed is too slow and passivation occurs making it ineffective for primary sulfide ores like chalcopyrite
Solution Approach 1:
The patent changes the parameters of the bioleaching process by using thermophilic microorganisms that operate at elevated temperatures (45-70°C) compared to conventional mesophilic processes. This temperature parameter change prevents passivation of primary sulfide ores while maintaining high leaching speeds, resolving the contradiction between productivity and passivation resistance
Solution Approach 2:
The patent uses isolated thermophilic microorganisms that have been specifically selected and propagated to exhibit enhanced properties compared to native microorganisms. These copied strains with optimized characteristics enable effective leaching of chalcopyrite without passivation, achieving both high productivity and reliability
2Productivity
If high-grade ores are processed using conventional technologies, then profitable production can be achieved, but low-grade ores remain unexplored due to lack of effective beneficiation technology
Solution Approach 1:
By changing the operational parameters to thermophilic conditions and using isolated thermophilic microorganisms, the patent enables effective processing of low-grade sulfide ores that were previously uneconomical. The enhanced leaching speed and prevention of passivation make low-grade ore processing feasible and profitable
Solution Approach 2:
The thermophilic microorganisms self-propagate in the leaching system, maintaining their population and activity without requiring continuous external inoculation. This self-sustaining characteristic reduces operational complexity and costs, improving ease of manufacture for low-grade ore processing
3Manufacturing precision
If mesophilic microorganisms are used in leaching heaps at 25-45°C, then satisfactory recovery is obtained for secondary sulfides, but the process is not financially viable for primary sulfide ores due to low leaching speed
Solution Approach 1:
The patent raises the temperature parameter from mesophilic (25-45°C) to thermophilic (45-70°C) range and uses thermophilic microorganisms adapted to these conditions. This parameter change simultaneously increases leaching speed and maintains high copper recovery, making the process financially viable for primary sulfide ores
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 significantly increases copper extraction rates, making low-grade ore processing financially viable by maintaining high bacterial activity and ferric ion concentrations, thereby reducing bioleaching times and operational costs.
Implementation Method 1
the solubilization or leaching of sulfide ore is favored by the presence of iron and sulfur-oxidizing bacteria
Implementation Method 2
the bio-oxidizing reactions of the iron in the biomass production reactors
Data Source
AI summary
The invention publishes a process to increase the bioleaching speed of ores or concentrates of sulfide metal species in heaps, tailing dams, dumps, or other on-site operations. The process is characterized by the continuous inoculation of the ores or concentrates with isolated microorganisms of the Acidithiobacillus thiooxidans type, together with isolated microorganisms of the Acidithiobacillus ferrooxidans type, with or without native microorganisms, in such a way that the total concentration of microorganisms in the continuous inoculation flow is of around 1×107 cells/ml to 5,6×107 cells/ml. In particular, the invention publishes the continuous inoculation of Acidithiobacillus thiooxidans Licanantay DSM 17318 together with Acidithiobacillus ferrooxidans Wenelen DSM 16786 microorganisms, or with other native microorganisms at a concentration higher than 5×107 cells/ml. In addition to the inoculation of isolated bacteria, the invention includes the addition of oxidizing agents such as the ferric ion produced externally, together with nutrients in the shape of salts of ammonium, magnesium, iron, potassium, as well as air enriched continuously with carbon dioxide to promote bacterial action in the bioleaching process of ores or concentrates.