Bioleaching Heap Temperature Control via Microbial Inoculation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The biological leaching process for chalcopyrite ore is ineffective due to the temperature gap of 50°C to 60°C, where mesophilic microorganisms die and thermophilic microorganisms are not activated, preventing the heap temperature from reaching the thermophilic zone necessary for effective bioleaching.
Innovation Solution
The method involves using multiple build-up reactors to cultivate specific microorganisms active at different temperature ranges, with continuous inoculation of mesophiles, moderate thermophiles, and thermophiles into the heap, supplemented with CO2, to maintain optimal microbial populations and heat generation, and using an auxiliary heap to recirculate leach solution and introduce active microorganisms to the main heap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a biological leaching process is started on a heap at ambient temperature, then microorganisms are introduced to generate heat, but the heap temperature cannot readily rise above 60°C because mesophilic microorganisms die and thermophilic microorganisms are not activated in the 50°C to 60°C temperature gap
Solution Approach 1:
The patent applies preliminary action by pre-heating the heap to thermophilic temperatures (above 60°C) before introducing thermophilic microorganisms. This preliminary heating action bypasses the problematic 50°C to 60°C temperature gap where no active microorganisms exist, ensuring that when microorganisms are introduced, the environment is already suitable for their activation and sustained activity.
Solution Approach 2:
The patent changes the temperature parameter from ambient temperature to thermophilic temperature (above 60°C) as a prerequisite condition. By changing this fundamental parameter before introducing microorganisms, the system transitions from a state where microbial succession fails to a state where thermophilic microorganisms can immediately become active and maintain high temperature conditions.
2Quantity of substance
If air stream is directed into the heap to deliver oxygen and carbon dioxide, then microorganisms receive necessary gases, but the air flow rate must be decreased to conserve heat due to the cooling effect
Solution Approach 1:
The patent changes the temperature parameter to thermophilic range (above 60°C) which fundamentally alters the heat loss dynamics. At these elevated temperatures, the relative cooling effect of air infiltration is reduced, and the system can tolerate higher air flow rates while maintaining temperature, thus resolving the contradiction between gas delivery and heat conservation.
3Quantity of substance
If raffinate flow rate is increased to drain liquid from the heap, then liquid is removed, but heat extraction via raffinate increases and the flow rate must be reduced to conserve heat
Solution Approach 1:
By maintaining the heap at thermophilic temperatures (above 60°C), the patent changes the thermal state of the system. This temperature parameter change reduces the temperature differential between the heap and the raffinate, thereby reducing heat extraction per unit volume of raffinate. Consequently, higher raffinate flow rates can be sustained while maintaining heat conservation, resolving the contradiction between liquid drainage and heat loss.
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 ensures successful transition to thermophilic conditions, maintaining high microbial activity and increasing heap temperature, thereby enhancing the effectiveness of the bioleaching process by maintaining thermophilic microorganisms and maximizing heat generation and copper recovery.
Implementation Method 1
Energy which is generated by the activity of suitable microorganisms which are introduced into the heap or which occur naturally gradually increases the heap temperature
Implementation Method 2
An air stream AS is directed into a heap to deliver oxygen and carbon dioxide to the microorganisms
Implementation Method 3
Heat extraction via the raffinate increases with the raffinate flow rate
Implementation Method 4
a heap of chalcopyrite or ore is heated and then inoculated with at least one thermophilic culture
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method of conducting a bioleaching process including the steps of forming a main heap, culturing at least one microorganism which exhibits bioleaching activity in a predetermined temperature range, monitoring the temperature in the main heap, which is a result, at least, of microbial leaching activity and inoculating the heap with the cultured microorganism at least before the temperature reaches the predetermined range.