Saline Alkali Soil Salt Extraction Using Acid and Vermiculite
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Solution Overview
Problem
Existing methods for improving saline alkali soil are inefficient in removing salt ions, leading to temporary improvements and risks of secondary salinization without comprehensive extraction and separation of salt alkali.
Innovation Solution
A method involving excavation of a foundation pit, use of nitric or phosphoric acid to create a saline alkali pool, application of vermiculite-based evaporating materials, and chemical reactions to form hydrotalcite functional materials for comprehensive salt alkali extraction and soil improvement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical improvement methods (deep tillage and loosening) are used to increase soil porosity, then salt removal is facilitated, but salt ions adsorbed by soil colloids cannot be effectively removed and loose soil provides only temporary improvement
Solution Approach 1:
The patent extracts salt ions from saline alkali soil through multiple mechanisms: (1) Chemical displacement using acids to dissolve carbonate salts and release adsorbed salt ions; (2) Evaporation concentration to precipitate salt crystals from soil solution; (3) Adsorption by vermiculite to capture and concentrate salt ions. This comprehensive extraction approach removes both free and adsorbed salt ions, achieving complete salt removal rather than temporary physical displacement.
Solution Approach 2:
The patent changes the chemical parameters of the soil system by introducing acids (nitric acid or phosphoric acid) that react with carbonate salts to alter the chemical composition and release adsorbed salt ions. The pH and chemical environment are modified to facilitate salt ion dissolution and subsequent removal, transforming the soil chemistry to enable effective salt extraction.
2Productivity
If biological improvement methods (using organisms to immobilize or absorb salt) are used, then salt is temporarily fixed in plants, but without follow-up measures secondary salinization risk remains
Solution Approach 1:
The patent implements continuous salt removal through multiple sequential steps: (1) Chemical displacement to release adsorbed salt ions; (2) Evaporation concentration to precipitate salts; (3) Adsorption by vermiculite to capture remaining salt ions; (4) Recycling the vermiculite for repeated use. This continuous multi-stage process ensures complete salt removal rather than temporary immobilization, eliminating secondary salinization risk.
Solution Approach 2:
The patent recycles vermiculite after adsorbing salt ions by dissolving, separating, and washing it to regenerate the material. The recovered vermiculite is returned to the system for repeated use in salt adsorption, creating a sustainable closed-loop process that continuously removes salt without secondary salinization.
3Reliability
If comprehensive salt extraction and separation is implemented through multiple steps including chemical reactions and evaporation, then complete salt removal is achieved, but process complexity increases
Solution Approach 1:
The patent segments the salt removal process into distinct functional stages: (1) Chemical displacement stage using acids; (2) Evaporation concentration stage to precipitate salts; (3) Adsorption stage using vermiculite; (4) Separation and washing stage. Each stage targets specific salt forms and mechanisms, making the complex process manageable and effective through modular segmentation.
Solution Approach 2:
The patent uses vermiculite as a multi-functional material that performs multiple roles: (1) Adsorbing salt ions from soil solution; (2) Concentrating salts through evaporation; (3) Serving as a recyclable medium for repeated salt extraction. This universal material simplifies the system by combining multiple functions in one component.
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
Achieves rapid and complete separation of salt alkali from saline soil with low energy consumption, enhancing soil fertility and promoting sustainable land use.
Implementation Method 1
The saline alkali soil absorbs heat, evaporates and precipitates saline alkali under the sunlight
Implementation Method 2
The saline alkali soil absorbs heat, evaporates and precipitates saline alkali under the sunlight
Implementation Method 3
a nitric acid solution or phosphoric acid solution is added and a saline alkali pool is obtained
Implementation Method 4
the salt alkali is enriched on the vermiculite or the evaporating material
Implementation Method 5
An alkali solution and an intercalation agent are added into the repeatedly recovered saline alkali solution for reaction to obtain an intercalated Mg—Al hydrotalcite
Data Source
AI summary
A method for extracting and separating salt alkali from saline alkali soil and soil improvement is disclosed. A foundation pit, square convex edge and cylindrical partition are arranged on a saline alkali land. Nitric or phosphoric acid solution is added to obtain a saline alkali pool. A trench is set around, and/or, a cylinder is set in the center of saline alkali pool. The evaporating material is prepared from vermiculite, laid on plastic wrapping material, and/or added into the cylinder. The salt alkali is precipitated and enriched through natural evaporation. The evaporating material enriched with salt alkali is taken out to be dissolved, separated and washed to obtain saline alkali solution and vermiculite or evaporating material. The vermiculite material is returned for reuse, and the above process is repeated. Alkali solution and intercalation agent are added into saline alkali solution to react and crystallize to obtain functional materials.