Sulfoaluminous Cement Coating for Boron-Rich Aqueous Solutions
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Solution Overview
Problem
Existing methods for coating aqueous solutions containing boron, such as those from nuclear reactors, face challenges with boron inhibiting cement setting, leading to long setting times and unstable boron precipitates, and require lime treatment which has drawbacks like prolonged hardening and potential malfunctions.
Innovation Solution
A process using a specific mixture of sulfoaluminous cement and sand, optionally with gypsum, to coat aqueous solutions with high boron concentrations, adjusting the pH to facilitate faster setting without lime, resulting in a cementitious grout with increased waste incorporation rates and accelerated setting times while maintaining mechanical and fluidity properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional Portland cement is used to coat aqueous solutions containing boron, then the cement setting is inhibited by boron, but the coating process becomes complex and time-consuming
Solution Approach 1:
The patent changes the chemical composition parameters of the cement by incorporating specific additives (calcium chloride, aluminum sulfate, and/or calcium aluminate) in controlled proportions (0-30% by mass of cement) to overcome boron-induced setting inhibition while maintaining process simplicity
Solution Approach 2:
The patent creates a composite cementitious material combining Portland cement with specific chemical additives (calcium chloride, aluminum sulfate, calcium aluminate) that work synergistically to resist boron inhibition and accelerate setting, achieving both simplicity and speed
2Reliability
If lime treatment is applied to remove boron inhibition, then setting inhibition is reduced, but setting times remain long (around a week) and boron precipitates become unstable
Solution Approach 1:
The patent modifies the chemical environment by adding calcium chloride, aluminum sulfate, and/or calcium aluminate which change the precipitation behavior of boron, forming stable compounds while accelerating the setting process to 24-72 hours
Solution Approach 2:
The patent introduces calcium chloride, aluminum sulfate, and/or calcium aluminate as intermediary substances that mediate between boron and the cement matrix, facilitating stable boron incorporation and accelerated setting without requiring lime treatment
3Ease of operation
If the aqueous solution contains high concentrations of boron (≥35 g/L), then the coating application is simplified, but cement setting is severely inhibited
Solution Approach 1:
The patent adjusts the formulation parameters by incorporating calcium chloride, aluminum sulfate, and/or calcium aluminate in specific proportions that enable the cement to handle high boron concentrations (≥35 g/L) without severe setting inhibition, maintaining operational simplicity
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 a significant acceleration of the setting time by a factor of 1.6 to 8.1 compared to traditional lime-treated formulations, with improved fluidity, mechanical resistance, and low expansion, meeting industrial implementation and storage criteria without degrading other properties.
Implementation Method 1
The cement-based composition is mixed with the aqueous solution containing boron to obtain a cementitious slurry constituting a coating; said coating is poured into a container; said coating is allowed to set in the container
Implementation Method 2
the boron contained in the waste inhibits the setting of the cement; The modes of action commonly mentioned to explain the hydration delay caused by boron are of two types: (i) clogging precipitation by formation of an amorphous gel on the surface of the cement grains, prohibiting the ionic exchanges necessary for their hydration, or (ii) chemisorption of borate ions at the end of hydrated calcium silicate chains
Data Source
Figure 1
AI summary
Cement-based composition for coating an aqueous solution containing boron, said composition being composed of a sulfoaluminous cement possibly containing gypsum and a sand. Coating method by cementation of an aqueous solution containing boron in which said aqueous solution is mixed with said cement-based composition. Composition of the cement grout thus obtained.