B2O3-Mn2O3 Additive for Magnetite Pellet Roasting
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Solution Overview
Problem
High roasting temperatures in the production of magnetite concentrate pellets lead to energy inefficiency and bonding issues, which are difficult to control, affecting the strength and quality of the final product.
Innovation Solution
An additive composed of B2O3 and Mn2O3 is used, mixed with magnetite concentrate and bentonite, to reduce the roasting temperature by promoting the decomposition of Mn2O3 and providing a trace fluid phase for Fe2+ movement, thereby reducing energy consumption and improving pellet strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high temperature roasting is used for magnetite concentrate pellets, then oxidation and consolidation are achieved, but energy consumption increases and bonding problems occur
Solution Approach 1:
The patent changes the chemical composition parameters of the roasting system by introducing calcium flux (CaO) and magnesium flux (MgO) along with their corresponding carbonates. This compositional parameter change enables the roasting process to proceed at lower temperatures (reducing energy consumption) while still achieving effective oxidation and consolidation of magnetite concentrate pellets.
Solution Approach 2:
The patent introduces fluxes (CaO, MgO, CaCO3, MgCO3) as intermediary substances that facilitate the roasting process. These fluxes act as mediators by forming low-melting-point compounds that promote sintering and bonding at reduced temperatures, thereby enabling effective pellet consolidation without requiring high energy input.
2Strength
If calcium flux is added to produce fluxed pellets, then bonding is promoted, but low melting point substances are generated causing uncontrollable liquid phase and bonding problems
Solution Approach 1:
The patent employs a composite fluxing system combining multiple calcium-based and magnesium-based fluxes (CaO, MgO, CaCO3, MgCO3) in specific proportions. This composite approach creates a balanced chemical system where the fluxes work synergistically to promote bonding while the magnesium components raise the melting point, preventing excessive liquid phase formation and maintaining process controllability.
Solution Approach 2:
The patent modifies the chemical composition parameters by introducing magnesium-containing fluxes alongside calcium fluxes. This parameter change adjusts the melting characteristics of the flux system, raising the eutectic temperature and reducing the amount of liquid phase generated during roasting, thereby improving process controllability while maintaining bonding strength.
3Ease of operation
If magnesium flux is added to generate high melting point substances, then bonding control is improved, but oxidation and recrystallization of magnetite are hindered
Solution Approach 1:
The patent merges calcium-based fluxes (CaO, CaCO3) with magnesium-based fluxes (MgO, MgCO3) in a combined fluxing system. This merging allows the calcium fluxes to provide strong bonding promotion while the magnesium fluxes contribute to higher melting points and better process control. The synergistic combination ensures that oxidation efficiency is maintained while achieving improved bonding control.
4Temperature
If low temperature roasting additives are prepared in advance, then roasting temperature is reduced, but alkali metal content affects blast furnace operation
Solution Approach 1:
The patent replaces traditional low-temperature additives containing alkali metals with a fluxing system based on calcium and magnesium oxides and carbonates. These alternative additives achieve the desired low-temperature roasting effect without introducing harmful alkali metals, effectively substituting problematic materials with benign alternatives that do not adversely affect blast furnace operation.
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
The additive significantly lowers the roasting temperature by 50-80°C, enhances pellet strength, and controls the generation of liquid phase to prevent bonding issues, resulting in improved energy efficiency and product quality.
Implementation Method 1
The magnetite concentrate, bentonite with a dosage of 0.7%, calcium flux and the additive are mixed into a mixture, then water accounting for 12-14% of a dry base mass of the mixture is added, and green pellets with a diameter of 10-12.5 mm are prepared in a disc balling machine, preheated at 600-1000° C. for 15-20 minutes after the completion of drying the green pellets to ensure that Mn2O3 is fully decomposed
Implementation Method 2
A melting point temperature of B2O3 is 450° C., B2O3 provides trace fluid phase for the pellets to promote the movement of Fe2+ and accelerate the consolidation of solid phase during the preheating
Implementation Method 3
O2 is slowly released during the preheating, promoting the oxidation and recrystallization of magnetite from an interior
Data Source
AI summary
The present invention discloses additive for reducing the roasting temperature of fluxed magnetite pellets and a method of using it, consisting of components: B2O3, Mn2O3, the B2O3 and Mn2O3 are pure chemical reagents, the mass of the additive is 0.8%, 4% of the dry basis mass of the magnetite concentrate, respectively, the magnetite concentrate, bentonite clay, calcium flux and additives will be dosed with 12-14% water of the dry base mass ratio of the mixture, prepared into green pellets of 10-12.5 mm in diameter in a disc ball making machine, After the pellets are completely dried, preheat them for 15˜20 min at 600˜1000° C. to ensure that Mn2O3 is fully decomposed, then roasting is carried out for 15 min at 1200° C., and after roasting, the pellets are cooled to room temperature to obtain the finished pellets.