Composite Solidifying Agent for Contaminated Soil Detoxification
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Solution Overview
Problem
Current solidifying agents for contaminated soils, such as those containing heavy metals, dioxins, or strongly acidic soils, face challenges in maintaining long-term non-elution of hazardous components, often resulting in environmental pollution due to high pH values, exothermic reactions, and insufficient strength after solidification.
Innovation Solution
A solidifying and detoxifying agent comprising light burnt magnesite, chrysolite powder, and additional components like anhydrous gypsum or fused phosphate fertilizer, which are mixed with contaminated substances to form a solidified product with effective detoxification and strength, suitable for various types of contaminated soils and ashes, achieving a pH range that complies with environmental standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a cement-type solidifying agent is used, then the soil solidification strength is improved, but the pH value becomes excessively high (pH 14) and remains alkaline for a long period, limiting utilization
Solution Approach 1:
The patent combines multiple solidifying agents (cement-type, lime-type, and gypsum-type) in a composite formulation. This merging allows the system to achieve the strength benefits of cement while the gypsum component mitigates the excessive alkalinity, producing a balanced pH suitable for both strength development and environmental compatibility.
Solution Approach 2:
The invention creates a composite solidifying agent comprising multiple materials with different properties. The composite structure enables simultaneous achievement of high strength and controlled pH, where the synergistic interaction between cement, lime, and gypsum components resolves the contradiction between strength gain and alkalinity control.
2Strength
If a lime-type solidifying agent is used, then the soil solidification is improved, but a highly exothermic reaction occurs during hydration generating large volume of dust and high pH value
Solution Approach 1:
The patent merges lime-type solidifying agent with cement-type and gypsum-type agents in a composite formulation. This combination dilutes the highly exothermic reaction characteristic of pure lime hydration, reducing dust generation while maintaining solidification strength through the synergistic action of all three components.
3Object-affected harmful factors
If a gypsum-type solidifying agent is used, then the pH value after solidification is low (different from cement and lime types), but insufficient strength is produced after solidification
Solution Approach 1:
The patent combines gypsum-type solidifying agent with cement-type and lime-type agents in a composite formulation. This merging allows the system to achieve the pH control benefits of gypsum while the cement and lime components provide the necessary strength development, creating a balanced performance profile.
4Reliability
If conventional solidifying agents are used, then hazardous substance elution is suppressed initially, but elutable hazardous components gradually elute from the solidified substance over time, making non-elution difficult to maintain
Solution Approach 1:
The invention creates a composite solidifying agent system that forms a more stable matrix structure. The multi-component formulation (cement, lime, gypsum) creates interconnected hydration products that provide long-term structural stability, preventing the gradual degradation and re-elution of hazardous substances that occurs with single-component systems.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the solidified matrix by using a composite solidifying agent formulation. This changes the pore structure, crystallinity, and chemical stability of the solidified substance, creating a more robust barrier that maintains hazardous substance immobilization over extended periods.
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 a solidified substance with cement-like hardness and uniaxial compressive strength of 50 KN or more, preventing hazardous component elution and meeting environmental standards, suitable for reuse as reclaimed crushed sand or soil conditioner.
Implementation Method 1
a highly exothermic reaction in hydration reaction to generate a large volume of dust
Implementation Method 2
the hazardous component is suppressed to elute to some extent right after solidification
Data Source
AI summary
A method of solidifying and detoxifying a soil, incinerated ash and coal ash to yield a solidified substance detoxified to a level complying with the environmental standards and a method of detoxifying polluted water containing dioxins and polluted water containing PCB are provided. First solidifying and detoxifying agent contains light burnt magnesite as component (1) and chrysolite powder as component (2), in which a ratio by weight of the component (1) and the component (2) is 1:5 to 5:1, preferably 1:3 to 3:1, more preferably 1:2 to 2:1 and is the solidifying and detoxifying agent applied to one kind selected from soil, incinerated ash and coal ash as well as polluted water containing dioxins and polluted water containing PCB. Other solidifying and detoxifying agent further contains as an additional component a fused phosphate fertilizer and titanium dioxide powder as well as anhydrous gypsum powder, light burnt dolomite and/or calcined lime powder.