Mine Waste to Supplementary Cementitious Materials
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Solution Overview
Problem
The cement and concrete industries face a need for new sources of pozzolans and supplementary cementitious materials to reduce the carbon footprint and enhance durability, as traditional sources like coal fly ash are declining due to the closure of coal-fired power plants.
Innovation Solution
A process is developed to convert mine waste materials, such as overburden and gangue, into supplementary cementitious materials through crushing, calcining or sintering, and milling, which can be blended with other pozzolans to create a sustainable alternative to traditional cement, meeting ASTM and AASHTO standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional cement is used to provide strength and durability in concrete, then mechanical performance is achieved, but carbon footprint increases significantly
Solution Approach 1:
The patent changes the chemical and physical parameters of supplementary cementitious materials through controlled calcination or sintering at specific temperatures (600-1600°C) and durations (1 second to 10 hours), transforming mine waste into materials with enhanced pozzolanic reactivity that can partially replace cement while maintaining concrete strength
Solution Approach 2:
The patent creates composite supplementary cementitious materials by blending processed mine waste with separate pozzolans, combining the benefits of waste material utilization with the proven performance of traditional pozzolans to achieve both carbon reduction and mechanical strength
2Object-generated harmful factors
If mine waste materials are processed through crushing, calcining, and milling to create supplementary cementitious materials, then sustainability and carbon footprint reduction are improved, but processing complexity increases
Solution Approach 1:
The patent divides the processing of mine waste into distinct sequential stages: crushing to reduce particle size, optional calcining or sintering at controlled temperatures, and milling to achieve target particle size distributions, allowing each stage to be optimized independently
Solution Approach 2:
The patent employs controlled changes in temperature (600-1600°C), time (1 second to 10 hours), and particle size parameters during processing to transform mine waste into supplementary cementitious materials with consistent quality and enhanced pozzolanic reactivity
3Reliability
If particle size of mine waste material is reduced through crushing and milling, then reactivity and performance as SCM are improved, but energy consumption increases
Solution Approach 1:
The patent applies preliminary crushing to reduce particle size before calcining or sintering, creating smaller particles that require less energy for subsequent milling and that heat more uniformly during thermal processing, thereby improving overall energy efficiency
Solution Approach 2:
The patent optimizes particle size parameters at different stages, targeting specific size ranges (e.g., D50 between 1-50 microns for milled material) that balance reactivity enhancement with energy consumption considerations
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 process effectively repurposes mine waste into high-performance supplementary cementitious materials that reduce the carbon footprint of concrete, enhance durability, and meet industry standards, offering a sustainable solution for concrete and cement applications.
Implementation Method 1
calcining or sintering the crushed mine waste material at a first calcining or sintering temperature selected from about 600° C. to about 1600° C.
Implementation Method 2
calcining or sintering the crushed mine waste material at a first calcining or sintering temperature selected from about 600° C. to about 1600° C.
Implementation Method 3
milling the crushed mine waste material or a calcined form thereof, to further reduce particle size
Data Source
AI summary
This invention repurposes mining waste/gangue materials to produce valuable supplementary cementitious materials, such as pozzolans for concrete applications. A process for producing a supplementary cementitious material from a mine waste material, comprises: obtaining a mine waste material; crushing the mine waste material; milling the crushed mine waste material to enhance pozzolanicity via mechanical activation; optionally, calcining or sintering the crushed mine waste material to generate a calcined/sintered mine waste material that is thermally activated to enhance pozzolanicity; optionally, milling the calcined/sintered mine waste material; and recovering a supplementary cementitious material, which may contain a separate pozzolan added at some point in the process. Experimental results demonstrate the disclosed technology for upcycling mining waste materials in the form of overburden, reject materials, and production byproducts, into supplementary cementitious materials. This discovery provides significant benefits to concrete performance and durability, while also substantially lowering the carbon footprint of the concrete.