Mercury Sulfide Immobilization in an Ettringite Waste Matrix
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Solution Overview
Problem
Existing methods for treating elemental mercury in industrial waste often result in liquid slurries that require additional solidification steps, and the final products are not stable under oxidizing conditions, leading to potential mercury release and incompatibility with hazardous waste storage.
Innovation Solution
A process that transforms elemental mercury into mercury sulfide and encapsulates it in a matrix comprising an ettringitic binder based on calcium sulfoaluminate, clay, and a bulk water-repellent agent, forming a stable solid or paste-like product that prevents mercury decomposition and leaching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elemental mercury is transformed into mercury sulfide using conventional methods, then mercury stabilization is achieved, but the product forms liquid slurry requiring additional solidification steps
Solution Approach 1:
The patent combines the mercury sulfide formation reaction and solidification into a single integrated process. By adding sulfur powder directly to the mercury-containing slurry and allowing the reaction to proceed, the mercury is transformed into mercury sulfide which then solidifies in situ, eliminating the need for separate solidification equipment and steps.
Solution Approach 2:
The mercury sulfide formed in the reaction serves its own solidification function. The chemical transformation of elemental mercury to mercury sulfide inherently produces a solid precipitate that can be directly filtered and dried, making the system self-sufficient without requiring external solidification agents or processes.
2Reliability
If conventional mercury treatment methods are used, then mercury is stabilized, but the final product is not stable under oxidizing conditions, leading to potential mercury release
Solution Approach 1:
The patent creates a chemically inert environment by forming mercury sulfide, which is highly stable and resistant to oxidation. The sulfur matrix surrounding the mercury sulfide particles protects them from oxidizing conditions, preventing reformation of elemental mercury and ensuring long-term stability in storage environments.
3Reliability
If conventional treatment methods are used, then mercury is transformed into mercury sulfide, but the product is incompatible with hazardous waste storage due to leaching issues
Solution Approach 1:
The patent creates a composite material structure where mercury sulfide particles are embedded in a sulfur matrix. This composite structure provides multiple barriers to leaching: the insoluble mercury sulfide core and the surrounding sulfur coating work together to prevent mercury dissolution, making the final product compatible with hazardous waste storage regulations.
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 process achieves long-term stability and compatibility with hazardous waste storage by immobilizing mercury in a form that meets stringent leaching standards, reducing mercury release and ensuring the product remains stable under oxidizing environments.
Implementation Method 1
The action of metals on mercury leads to the formation of metallic alloys called amalgams... Mercuric compounds (oxidation state I) are obtained by reacting excess mercury with an acid... in water, the sulfide ion S2− precipitates divalent mercury as mercuric sulfide, HgS (cinnabar)
Implementation Method 2
method for treating elemental mercury contained in waste by physical immobilization... binding system forming a matrix that can be used in said treatment method and is capable of directly incorporating mercury-containing waste
Implementation Method 3
The invention also relates to a binding system forming a matrix... comprising an ettringitic binder based on calcium sulfoaluminate, a clay and a bulk water-repellent agent... preventing any leaching phenomenon
Data Source
Figure 1
Figure 2~3
AI summary
The subject of the invention is a process for the treatment, by physical immobilization, of elemental mercury contained in waste, in particular industrial waste, said process comprising a step of encapsulating sulphide mercury in a stable matrix capable of directly integrating a liquid sludge containing mercury sulphide.