Acid Solution Preheating via Off-Gas Direct Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current hydrometallurgical processes for leaching sulfidic metal concentrates generate excessive heat, which is wasted as hot water vapor off-gas, while external energy sources are used to warm acid solutions, leading to high energy costs and carbon dioxide emissions.
Innovation Solution
Recover thermal energy from hot water vapor off-gas by bringing it into direct contact with the acid solution, eliminating the need for conventional heat exchangers and reducing external energy requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If external heating energy sources (oil, natural gas) are used to warm up the acid solution, then the acid solution reaches the required temperature for the leaching process, but this results in high energy costs and carbon dioxide emissions
Solution Approach 1:
The invention converts the harmful waste heat contained in the off-gas (which was previously vented to atmosphere) into a useful resource for preheating the acid solution. The hot water vapor in the off-gas, previously representing energy loss, is now utilized to warm the acid solution, thereby reducing external energy consumption and carbon dioxide emissions while maintaining the required process temperature
Solution Approach 2:
The invention recovers thermal energy from the off-gas that would otherwise be discarded to the atmosphere. By capturing the waste heat from the leaching process and using it to preheat the acid solution, the system transforms a discarded energy stream into a valuable resource, significantly reducing the need for external heating energy
2Loss of energy
If conventional heat exchangers are used to recover heat from off-gas, then heat recovery is achieved, but sulfur compounds in the off-gas accumulate on cold surfaces causing operational problems
Solution Approach 1:
The invention introduces water as an intermediary substance to transfer thermal energy from the off-gas to the acid solution. Instead of direct contact between off-gas and acid solution (which would cause sulfur compound accumulation), water vapor condenses on the acid solution surface, transferring heat without allowing sulfur compounds to accumulate on cold surfaces
Solution Approach 2:
The invention uses a spray nozzle system to atomize water into fine droplets that are injected into the off-gas stream. This pneumatic-hydraulic approach creates a large surface area for heat transfer while keeping the water droplets suspended in the gas phase, preventing sulfur compound accumulation and enabling efficient thermal energy recovery
3Object-generated harmful factors
If hot water vapor off-gas is vented directly to the atmosphere through a gas scrubber, then the off-gas is safely discharged, but considerable thermal energy is wasted
Solution Approach 1:
The invention converts the harmful waste heat in the off-gas into a useful resource. The hot water vapor that was previously representing pure energy loss is now captured and used to preheat the acid solution, transforming an environmental and economic liability into a process asset that reduces external energy consumption
Solution Approach 2:
The invention recovers thermal energy from the off-gas stream before discharge. By passing the off-gas through a spray chamber where water droplets absorb thermal energy, the system captures waste heat that would otherwise be discarded to the atmosphere, converting it into useful heating capacity for the acid solution
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
Significantly reduces energy costs and carbon dioxide emissions while increasing energy efficiency by effectively warming the acid solution using the recovered heat, without affecting the leaching process.
Implementation Method 1
When the off-gas is brought into direct contact with the acid solution, the hot water vapor contained by the off-gas condenses onto the surface of the cooler acid solution according to the liquid-gas equilibrium
Implementation Method 2
The heat of the hot water vapor contained by the off-gas is recovered by bringing the off-gas into direct contact with the acid solution
Data Source
Figure 1~2
AI summary
A method for leaching a sulfidic metal concentrate in hydrometallurgical production of metal in a leaching process from which hot water vapor containing off-gas is conducted out and to which an acid solution warmed up to an elevated temperature is conducted. The acid solution is warmed up to an elevated temperature by bringing off-gas of the leaching step into direct con¬ tact with the acid solution.