Unfired Basic Brick Manufacturing with Magnesium Silicate Hydrate
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Solution Overview
Problem
Existing unfired basic bricks used in molten metal containers suffer from poor corrosion resistance due to the reaction of alkali components with SiO2 and Al2O3 components, leading to a decrease in liquid-phase formation temperature and the formation of hexavalent chromium, which deteriorates their performance.
Innovation Solution
A manufacturing method involving the use of a refractory raw material mixture containing magnesia and silica fine powders with specific particle sizes, subjected to kneading, press-molding, and heat treatment at 60°C to 1000°C to form magnesium silicate hydrate, which acts as a binder, enhancing corrosion resistance and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If unfired basic bricks are manufactured without high-temperature firing, then manufacturing cost and energy consumption are reduced, but corrosion resistance deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the binder from conventional alkali-based binders to a magnesium phosphate-based binder system. Specifically, it uses magnesium phosphate hydrate as the primary binding agent, which forms a chemically stable phase that resists corrosion by molten slag at lower firing temperatures (below 1700°C), thereby achieving both energy reduction and maintained corrosion resistance.
Solution Approach 2:
The invention creates a composite binder system combining magnesium phosphate hydrate with specific ratios of magnesia and chrome oxide. This composite material formulation produces a synergistic effect where the magnesium phosphate matrix provides corrosion resistance while the embedded magnesia and chrome oxide particles enhance structural integrity and chemical stability, enabling unfired bricks to achieve fired-brick-level corrosion resistance.
2Strength
If alkali-based binders are used in unfired basic bricks, then binding strength is achieved, but liquid-phase formation temperature decreases leading to poor corrosion resistance
Solution Approach 1:
The invention extracts and eliminates the harmful alkali components (such as Na2O and K2O) from the binder system. By removing these alkali substances that cause low-temperature liquid phase formation and poor corrosion resistance, the invention replaces them with a magnesium phosphate-based binding mechanism that achieves adequate binding strength through chemical bonding rather than liquid-phase sintering.
Solution Approach 2:
The invention uses a binder system that forms a stable, non-reactive magnesium phosphate hydrate matrix that does not degrade or form harmful liquids during service. This binder, while simpler in composition than fired brick systems, provides sufficient service life and performance for unfired applications by creating a chemically inert binding structure that resists slag attack.
3Temperature
If lithium-based binders are used to achieve binding without high-temperature firing, then manufacturing temperature is reduced, but corrosion resistance deteriorates due to lithium reactions
Solution Approach 1:
The invention converts the potential harm of using low-fired binders into a benefit by selecting magnesium phosphate hydrate, which initially appears to be a simple drying binder but actually forms a chemically stable, corrosion-resistant crystalline phase upon controlled drying and low-temperature curing. This phase transformation converts a potentially weak binder into a durable, slag-resistant binding matrix.
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 method produces unfired basic bricks with excellent corrosion resistance and high hot strength, suppressing the formation of hexavalent chromium and preventing peel-off of the working surface, extending the usable life of molten metal containers.
Implementation Method 1
adding water to a refractory raw material mixture which contains: at least one of magnesia having a particle size of less than 75 μm and magnesia-chrome having a particle size of less than 75 μm, at a rate of 0.2% by mass to 30% by mass in total; and silica having a particle size of less than 75 μm, at a rate of 0.3% by mass to 2.5% by mass; and subjecting the resulting mixture to kneading, press-molding, and then heat treatment at a temperature of 60°C to 1000°C
Data Source
Figure 1
AI summary
The present invention provides a manufacturing method for an unfired basic brick having excellent corrosion resistance. In the present invention, the method comprises: adding water to a refractory raw material mixture which contains: at least one of magnesia having a particle size of less than 75 µm and magnesia-chrome having a particle size of less than 75 µm, at a rate of 0.2% by mass to 30% by mass in total; and silica having a particle size of less than 75 µm, at a rate of 0.3% by mass to 2.5% by mass; and subjecting the resulting mixture to kneading, press-molding, and then heat treatment at a temperature of 60°C to 1000°C.