Microbial Rare Earth Leaching Agent Without Ammonia Nitrogen Pollution
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Solution Overview
Problem
Existing leaching methods for ionic rare earths are polluting, costly, and inefficient, with issues such as ammonia nitrogen pollution and high chemical raw material usage, and current methods for indium selenide and tin disulfide production are complex and not suitable for large-scale application.
Innovation Solution
A method involving domestication of microorganisms with activated mineral powder and sesbania gum modification to create a leaching agent, and simple liquid-phase methods for indium selenide and solvothermal methods for tin disulfide production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ammonium sulfate in-situ leaching technology is used, then the leaching process is established for ionic rare earths, but the total ammonia nitrogen in the leaching solution pollutes the water body
Solution Approach 1:
The patent changes the chemical composition parameters of the leaching agent by replacing ammonium sulfate with a microbial system (Bacillus subtilis) that produces organic acids in situ, transforming the leaching mechanism from chemical salt-based to biological acid-based, thereby eliminating ammonia nitrogen pollution while maintaining effective rare earth leaching
Solution Approach 2:
The patent employs self-service by utilizing Bacillus subtilis bacteria to naturally produce organic acids (such as gluconic acid, citric acid) during the leaching process, eliminating the need for external addition of chemical leaching agents. The microbial system serves itself by using the rare earth minerals as both substrate and target, reducing chemical raw material input while achieving effective leaching
2Productivity
If hydrochloric acid solution is used as a leaching agent, then leaching can be carried out, but the leached slag becomes acidized and the pH of the supernatant is too low requiring treatment
Solution Approach 1:
The patent changes the pH parameter profile by using biologically produced organic acids instead of strong mineral acids. The organic acids provide sufficient acidity for leaching (pH 2-6 range) while being less aggressive than hydrochloric acid, preventing extreme slag acidification and producing a supernatant with manageable pH that requires minimal neutralization
Solution Approach 2:
The patent uses disposable microbial cells (Bacillus subtilis) that can be easily added and removed from the system. The bacteria perform the acid generation function temporarily during leaching, then can be filtered out, leaving a clean leaching solution without the need for complex acid neutralization and slag treatment required by hydrochloric acid methods
3Productivity
If many chemical raw materials are used in the preparation process of the leaching agent, then the leaching rate of ionic rare earths can be improved, but the cost of rare earth extraction increases
Solution Approach 1:
The patent implements self-service by using Bacillus subtilis bacteria to autonomously produce the necessary organic acids during the leaching process. The bacteria utilize the rare earth minerals themselves as carbon and energy sources, eliminating the need for external addition of chemical raw materials while achieving high leaching rates (93.7% as reported in similar studies)
Solution Approach 2:
The patent applies universality by using Bacillus subtilis as a multi-functional agent that simultaneously serves as the leaching mechanism provider, pH regulator, and potential flocculating agent. This single microbial system replaces multiple chemical raw materials that would otherwise be needed for leaching, pH control, and sludge management, reducing both cost and chemical input
4Productivity
If wood vinegar is used in collaboration with NH4+ to leach rare earth under acidic environment, then the leaching rate can reach up to 93.7%, but the supernatant still contains ammonia nitrogen requiring improvement
Solution Approach 1:
The patent changes the chemical composition parameter by completely replacing the wood vinegar + ammonium sulfate combination with a pure microbial system. The Bacillus subtilis produces organic acids naturally, achieving similar pH levels (2-6) and leaching rates without introducing ammonia nitrogen, thus maintaining productivity while eliminating the harmful pollutant
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 achieves a high leaching rate of ionic rare earths without ammonia nitrogen pollution, and produces indium selenide and tin disulfide nanomaterials suitable for photocatalytic degradation and adsorption of organic dyes efficiently and economically.
Implementation Method 1
When rare earth ions encounter chemically more active electrolyte cations (K+, Na+, Mg2+, Ca2+ and NH4+, etc.), rare earth ions can be exchanged and resolved from clay minerals
Implementation Method 2
the diffusion resistance in the exchange process is reduced
Data Source
AI summary
A preparation method of an ionic rare earth leaching agent includes the following steps: (1) domestication microorganisms with rare earth activated mineral powder culture medium to obtain a microbial suspension; (2) amplifying and culturing the microbial suspension and additives to obtain the amplified culture medium; and (3) mixing the modified sesbania gum with the amplified culture medium to obtain the ionic rare earth leaching agent. The activated mineral powder is the active metal-containing mineral powder in nature, which has excellent cation exchange function after activation, and the activated mineral powder and ionic rare earth mineral powder are used as the medium components to domesticate microorganisms, so that microorganisms can survive in the above-mentioned ionic solution and improve the leaching rate of synergistic leaching ionic rare earth.