Post-Combustion Chamber SO3 Decomposition in Ore Roasting
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Solution Overview
Problem
The existing processes for handling and treating off-gas in copper and gold concentrate roasting face issues such as accretion formation, corrosion, and high effluent treatment costs due to sulfur dioxide (SO3) concentrations, which lead to equipment damage and increased operational expenses.
Innovation Solution
A process that combines the first and second stage roasting off-gases with oxygen-containing warm oxidizer gas for post-combustion in a post-combustion chamber, ensuring complete combustion and reducing SO3 content, along with temperature control using direct or indirect cooling methods to prevent accretion and corrosion, and utilizing preheated air to minimize additional heating requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If post combustion is performed with ambient temperature air, then combustion efficiency is improved, but accretion formation in gas ducts increases
Solution Approach 1:
The invention preheats the combustion air before introducing it to the post-combustion chamber. This preliminary heating action prevents the air from being at ambient temperature, thereby avoiding the formation of accretions in gas ducts while still achieving efficient combustion of the process gas.
Solution Approach 2:
The invention changes the temperature parameter of the combustion air from ambient temperature to a preheated state. This parameter change eliminates the harmful effect of accretion formation while maintaining the beneficial combustion efficiency, as the preheated air prevents condensation and accretion in the gas ducts.
2Object-generated harmful factors
If preheated air is used to prevent accretion on cold surfaces, then accretion risk is reduced, but investment cost and operating costs increase
Solution Approach 1:
The invention uses the hot process gas exiting the roasting reactor to preheat the combustion air through a heat exchanger. This multi-functional approach serves two purposes: it recovers heat from the process gas that would otherwise be wasted, and it preheats the combustion air to prevent accretion. This eliminates the need for separate heating equipment, reducing both investment and operating costs.
Solution Approach 2:
The invention converts the hot process gas, which would normally require cooling and represent a waste heat source, into a useful resource for preheating the combustion air. This transforms a potentially harmful hot stream into a beneficial heat source, eliminating the need for additional heating equipment while preventing accretion.
3Object-generated harmful factors
If equipment is well insulated to prevent accretion, then accretion formation is avoided, but heat recovery efficiency decreases
Solution Approach 1:
The invention uses a heat exchanger to transfer heat from the hot process gas to the combustion air through fluid-to-fluid heat transfer. This pneumatic/hydraulic heat exchange mechanism allows efficient heat recovery without requiring direct thermal contact or extensive insulation, thereby maintaining heat recovery efficiency while preventing accretion through proper heat exchange design.
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 reduces the risk of accretion and corrosion, lowers effluent treatment costs, and allows for efficient heat recovery and steam superheating without external equipment, thereby optimizing gas cleaning and energy production.
Implementation Method 1
post combustion of the process gas component and treating the process gas in subsequent gas cooling and dust removal steps
Implementation Method 2
post combustion operating with said reducing and sulphide rich first process gas component and said second gas component as oxidizer
Implementation Method 3
Gas cooling during two-stage roasting can either be made by direct cooling with water injection in a cooling tower or through indirect cooling through cooling coils
Implementation Method 4
separation of calcine and process gas in cyclones
Implementation Method 5
dust cleaning in electrostatic precipitator
Data Source
AI summary
The present invention concerns a process and a plant for treating ore concentrate particles containing valuable metal and having at least arsenic and sulfur containing components. The process comprises a two-stage roasting process comprising a first roasting step (1) made in a first roasting reactor (16) and a second roasting step (3) made in a second roasting reactor (17). A gas mixture is formed from the first process gas component (2) obtained from the first roasting step(1)and from the second process gas component (4) obtained from the second roasting step (3). Post combustion of the gas mixture is made in a post combustion chamber (6). The post combustion operates with said reducing and sulphide rich first process gas component (2) and the second process gas component (4) as oxidizer gas in order to decompose SO3 in the gas mixture to reduce the SO3 content. The risk of accretion formation and corrosion in the post combustion chamber and in subsequent steps is reduced. Finally the exit gas (7) is exposed to subsequent gas cooling and dust removal steps (8 to 11).