Building Materials from Oxidized Bottom Ash
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Solution Overview
Problem
The reuse of bottom ash and debris from incineration processes in the building industry is hindered by the corrosion of amphoteric metals, leading to unstable concrete products and environmental concerns, as existing methods fail to adequately address granulometric fineness and alkaline reactions.
Innovation Solution
A manufactured item for the building industry using bottom ash and/or debris with oxidized amphoteric metals, processed with lime as a binder to control pH levels and achieve desired mechanical resistances, combined with calcium sulphate for enhanced properties, and optimized grinding and curing processes to produce stable and durable products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If bottom ash and debris are used directly as building materials, then waste utilization is improved, but structural stability deteriorates due to metal corrosion and expansion
Solution Approach 1:
The patent applies preliminary action by performing wet grinding and oxidative treatment on bottom ash and debris before they are used as building materials. The ash is ground in aqueous suspension and exposed to oxygen over time (or accelerated by hydrogen peroxide) to oxidize amphoteric metals like aluminum and zinc beforehand, preventing subsequent corrosion and hydrogen generation that would compromise structural stability. This pre-treatment ensures the material is stabilized before construction application.
Solution Approach 2:
The patent changes physical and chemical parameters of the bottom ash through wet grinding to achieve specific granulometric fineness (all particles below 70 μm, preferably below 60 μm). This parameter change increases surface area for oxidation while controlling the material's reactivity. The chemical parameter of oxidation state is also changed by exposing the ground ash to oxygen or hydrogen peroxide, transforming amphoteric metals from reactive to stable oxidized forms, thereby resolving the contradiction between waste utilization and structural stability.
2Ease of manufacture
If amphoteric metals in bottom ash are not oxidized, then manufacturing simplicity is improved, but harmful effects worsen due to hydrogen generation and concrete expansion
Solution Approach 1:
The patent converts the harmful effect of amphoteric metals (aluminum and zinc) into a beneficial outcome by deliberately oxidizing them during manufacturing. The metals that would otherwise corrode and generate expansive hydrogen gas in concrete are transformed into stable oxide forms beforehand. This converts a potential harm (corrosion risk) into a benefit (stable, non-reactive material), eliminating the harmful effects while maintaining manufacturing feasibility through the wet grinding process.
3Manufacturing precision
If bottom ash is ground to fine particles, then reactivity is improved, but corrosion risk increases due to larger surface area
Solution Approach 1:
The patent applies preliminary action by performing the oxidation treatment immediately after wet grinding while the ash is in fine particle form and high surface area state. By oxidizing the metals at this stage, the large surface area created by fine grinding is converted into stable oxide surfaces, preventing subsequent corrosion. The sequence is critical: grind first to achieve fineness, then oxidize to eliminate corrosion risk, thereby resolving the contradiction between manufacturing precision and corrosion risk.
Solution Approach 2:
The patent changes the chemical parameter of the ash particles by oxidizing amphoteric metals after grinding. The physical parameter of granulometric fineness is maintained at high levels (all particles below 70 μm) while the chemical parameter of oxidation state is changed to stable forms. This dual parameter control allows the material to have both high reactivity (from fine particles) and low corrosion risk (from oxidized metals).
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 solution results in stable, high-mechanical-resistance building materials with controlled expansion phenomena, suitable for various applications, and significantly reduces environmental impact by utilizing waste materials efficiently.
Implementation Method 1
processed with lime as a binder to control pH levels
Implementation Method 2
amphoteric metals contained in bottom ash and/or debris wherefrom the manufactured item is obtained have been substantially oxidised
Implementation Method 3
combined with calcium sulphate for enhanced properties
Implementation Method 4
optimized grinding and curing processes
Implementation Method 5
optimized grinding and curing processes to produce stable and durable products
Data Source
AI summary
A manufactured item for the building industry is disclosed, made mainly of bottom ash and/or debris coming from incineration processes of municipal solid waste or of waste which may be assimilated thereto and/or of RDF and of one or more binders. Such manufactured item may have the shape of small bricks, bricks, blocks, small blocks, curbs, interlocking paving blocks, panels, tiles, prefabricated slabs, beams, elements for walls, modular building elements, indoor and outdoor cladding elements, blocks, rocks, supports. Moreover, a process for the manufacture of an item for the building industry is disclosed, from bottom ash and/or debris coming from incineration processes of municipal solid waste or of waste which may be assimilated thereto and/or of FDR wherein the ash and/or debris undergo an oxidation process of the amphoteric metals and mixed with a binder.