Hydrotalcite Granulation via Controlled Drying
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Solution Overview
Problem
The production of granular hydrotalcite for immobilizing anionic hazardous substances is costly and time-consuming, and the use of granulating machines or binders reduces the hydrotalcite ratio, leading to lower anion adsorption efficiency.
Innovation Solution
A method involving the drying of a hydrotalcite-like substance with water at a temperature below its dehydration point, maintaining a water content of 70% or lower, and under high humidity conditions to produce granules with a stable morphology and high anion exchange performance, without the need for additional binders or separate granulating stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a granulating machine is used to produce granular hydrotalcite, then the grain size is increased to prevent filter clogging, but a separate granulating stage is required which increases production time and costs
Solution Approach 1:
The invention combines the granulation process with the drying process into a single integrated operation. By controlling drying conditions (temperature, humidity, time), granular hydrotalcite is formed directly during drying without requiring a separate granulating machine or stage, thereby reducing production time and costs while achieving the required grain size
Solution Approach 2:
The hydrotalcite material itself serves as the granulating agent through controlled drying. The material undergoes self-granulation during the drying process where water evaporation and crystal growth naturally form granules of appropriate size, eliminating the need for external granulating equipment
2Ease of manufacture
If a binder is used to produce granular hydrotalcite, then the grains can be formed without a granulating machine, but the use of additional material reduces the ratio of hydrotalcite in the grains, leading to lower anion adsorption capacity
Solution Approach 1:
The invention uses the hydrotalcite precursor material itself to form granules through controlled drying, eliminating the need for external binders. The material undergoes self-organization and granulation during the drying process, ensuring that the final granular product consists entirely of hydrotalcite without contamination from binder materials, thus maintaining maximum anion adsorption capacity
Solution Approach 2:
The invention controls the drying parameters (temperature, humidity, time) to achieve granule formation without binders. By optimizing these parameters, the material forms stable granules with high hydrotalcite content, resolving the contradiction between ease of manufacture and material purity
3Reliability
If powder hydrotalcite is used to immobilize anionic hazardous substances, then the anion exchange effect can be achieved, but pressurization with large pressure is required to press the powder through a filter fabric, leading to large equipment size
Solution Approach 1:
The invention performs granulation before filtration by controlling the drying process to form granules of appropriate size and strength. These pre-formed granules can be easily filtered without requiring high pressurization, thus maintaining the anion exchange effect while reducing equipment size and operating pressure
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 approach results in a cost-effective, high-anion exchange performance hydrotalcite-like granular material with improved adsorption capacity for ions like fluorine, and the ability to immobilize cations, while maintaining morphological stability and large grain size.
Implementation Method 1
drying of a material that contains at least a hydrotalcite-like substance and water at equal to or lower than a temperature at which the hydrotalcite-like substance is dehydrated of crystal water contained therein
Implementation Method 2
If hydrotalcite can work the anion exchange effect to immobilize arsenic, fluorine, boron, selenium, hexavalent chromium, nitrite ion, and other anionic hazardous substances
Data Source
AI summary
A hydrotalcite-like granular material having a grain size of 0.24 mm or larger is produced by drying a material that contains at least a hydrotalcite-like substance and that has a water content of 70% or lower at equal to or lower than a temperature at which the hydrotalcite-like substance is dehydrated of crystal water contained therein, preferably at 90° C. or higher and 110° C. or lower, such that the resulting hydrotalcite-like granular material has a water content of 10% or higher. In this manner, a hydrotalcite-like granular material that has a stable morphology and a high anion exchange performance and that can be produced at a low cost can be produced.