Spent Selenium Filter Mass Recycling Process
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Solution Overview
Problem
Spent selenium filters pose disposal challenges due to the presence of both unspent active selenium and mercury selenides, making it costly and environmentally problematic to replace them, and existing methods for processing mercury-containing waste are not feasible for reclaiming selenium filter masses.
Innovation Solution
A process involving hydrogen peroxide leaching to extract unspent selenium as selenious acid, followed by aqua regia treatment to dissolve mercury selenide, allowing for separation and reuse of selenium and inert carrier materials, with optional precipitation of mercury as a stable sulphide for safe disposal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If spent selenium filter mass is disposed of conventionally, then disposal costs and environmental impact are high, but the value of selenium and carrier material is lost
Solution Approach 1:
The patent applies discarding and recovering by systematically separating and recovering valuable materials from spent filter mass. The process recovers unspent selenium through oxidation and precipitation, recovers carrier material through magnetic separation, and converts mercury to a stable disposed form, thereby eliminating disposal costs while recovering valuable substances.
Solution Approach 2:
The patent employs parameter changes by altering chemical and physical conditions to enable selective separation. Chemical oxidation transforms unspent selenium into separable compounds, magnetic field application changes the physical state of carrier particles for separation, and chemical treatment converts mercury into a stable non-toxic form for safe disposal.
2Object-generated harmful factors
If high temperature treatment is used to remove mercury from waste, then mercury can be evaporated as selenide, but the method is not feasible for reclaiming selenium filter masses and separation is troublesome
Solution Approach 1:
The patent applies segmentation by dividing the complex treatment process into distinct sequential steps: first treating unspent selenium through oxidation, then handling mercury selenide formation and removal, and finally recovering carrier material through magnetic separation. This segmented approach makes the overall process feasible and manageable for selenium filter mass reclamation.
Solution Approach 2:
The patent uses chemical intermediaries to facilitate separation. Oxidizing agents serve as intermediaries to convert unspent selenium into separable compounds, and chemical treatments act as intermediaries to convert mercury into stable forms, enabling easy separation without direct high-temperature processing of the entire filter mass.
3Reliability
If filter mass is replaced when performance is reduced, then cleaning ability is maintained, but disposal costs and waste tipping fees increase
Solution Approach 1:
The patent enables recovery and reuse of carrier material and selenium compounds from spent filters, transforming what would be disposable waste into recoverable resources. This eliminates the need for complete filter replacement and reduces disposal costs while maintaining filter performance through regenerated materials.
Solution Approach 2:
The patent applies self-service by creating a closed-loop system where spent filter materials are recovered and reused to produce new filter masses. The process essentially services itself by converting waste into reusable materials, eliminating the need for external disposal services and reducing ongoing operational costs.
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 process significantly reduces the volume and cost of disposal by allowing for the reuse of selenium and inert carrier materials, achieving a 95% reduction in disposal costs and minimizing environmental impact by transforming mercury-containing waste into a stable form.
Implementation Method 1
the used and spent selenium filter mass is first treated with a hydrogen peroxide solution, suitably having a concentration of about 50%, for leaching out essentially all of the unspent active substance in the filter mass, which is obtained in the form of selenious acid
Implementation Method 2
The filter mass that has been freed from the solution is then treated with aqua regia, preferably at an elevated temperature, for dissolving essentially all of the mercury selenide contained in the mass
Implementation Method 3
Suitably, the aqua regia solution is heated and aerated to evaporate any excess of aqua regia
Implementation Method 4
SO2 is introduced into the solution after a partial neutralisation by suitable pH adjustment, resulting in precipitation of selenium as elemental selenium, Se(s)
Implementation Method 5
the mercury can be precipitated in the form of some poorly soluble compound other than selenide, such as sulphide. Thus, the solution can reprocessed for reclaiming the selenium it contains, and the mercury content can also be obtained in a form that is suitable for disposal in an environmentally safe manner
Data Source
AI summary
A process for reclaiming spent selenium filter mass containing an inert material. The spent mass is treated with a hydrogen peroxide solution for leaching out selenium content from unspent active substance present in the filter mass to form selenious acid. The filter mass is treated with aqua regia solution to dissolve mercury selenide present in the mass. The aqua regia solution is separated from the mass and isolated. Suitably, the filter mass, which now contains inert carrier material, is transferred with the isolated selenious acid, to production of new selenium filter mass. After partial neutralization of the aqua regia solution, mercury is precipitated out for disposal. Before this, elemental selenium can be separated from the aqua regia solution by adjusting the pH level and used advantageously for production of new filter mass. Thusly, reclaimed selenium content and inert carrier material can be advantageously used for production of new selenium filters.