Phosphorus Recovery from Alternative Fuels via Calcium Binding
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Solution Overview
Problem
Current methods for recovering phosphorus from phosphorus-containing materials like fuels and sewage sludge are inefficient due to the poor phytoavailability of phosphorus in ash and the economic challenges of using orthophosphoric acid, leading to phosphorus being vitrified at high temperatures and not being available for recovery.
Innovation Solution
A method involving a thermochemical reaction of phosphorus-containing materials with calcium-containing particles in a moving bed reactor, followed by separation of phosphorus-enriched fines, which are then acidified to produce phytoavailable phosphorus, enabling its reuse as a fertilizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorus-containing materials are subjected to high-temperature combustion or gasification, then energy is recovered and ash is produced, but phosphorus is vitrified at high temperatures and becomes unavailable for recovery
Solution Approach 1:
The patent introduces calcium-containing particles into the moving bed reactor before or during the thermochemical conversion process. These particles react with phosphorus-containing materials at lower temperatures to form calcium phosphates, preventing the vitrification that would otherwise occur at higher temperatures and render phosphorus unrecoverable. This preliminary chemical binding action preserves phosphorus availability while still enabling energy recovery.
Solution Approach 2:
Calcium-containing particles serve as an intermediary substance that facilitates phosphorus recovery. These particles react with phosphorus to form calcium phosphates, which can be easily separated from the ash. The calcium-containing particles act as a mediator that transforms phosphorus from an unavailable vitrified state into an available, separable form without requiring extreme temperatures.
2Loss of substance
If orthophosphoric acid is used to recover phosphorus from ash, then phosphorus can be extracted, but the method becomes uneconomic on an industrial scale due to large quantities of acid required
Solution Approach 1:
The patent uses calcium-containing particles (such as calcium carbonate or calcium oxide) as a disposable or regenerable reagent that is far cheaper than orthophosphoric acid. These particles react with phosphorus to form calcium phosphates, which can be separated and processed. The calcium-containing material can be obtained from inexpensive sources and potentially regenerated, making the process economically viable for industrial-scale phosphorus recovery.
Solution Approach 2:
The patent changes the chemical parameters of the system by using calcium-containing particles instead of orthophosphoric acid. This substitution fundamentally alters the chemistry from an acid-based extraction process to a precipitation-based separation process, which requires fewer chemical reagents and reduces operational costs significantly.
3Device complexity
If phosphorus is recovered directly from ash, then the process is simpler, but the phytoavailability of phosphorus is poor and it cannot be used as fertilizer
Solution Approach 1:
The patent transforms the chemical form of phosphorus locally within the ash matrix by reacting it with calcium-containing particles to form calcium phosphates. This local chemical transformation creates phosphorus compounds with specific properties (calcium phosphates) that have both good phytoavailability and ease of separation. The local quality change occurs at the molecular level where phosphorus is converted into a bioavailable form.
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 method effectively recovers phosphorus in a phytoavailable form, reducing impurities and allowing its return to natural material cycles, enhancing soil fertility and addressing the limitations of existing technologies.
Implementation Method 1
thermochemical reaction of a phosphorus-containing material such as, for example, a phosphorus-containing alternative fuel, in the presence of calcium-containing particles in a moving bed reactor
Implementation Method 2
separation of wear or fines enriched with phosphorus from the moving bed reactor
Implementation Method 3
reaction of the wear or fines enriched with phosphorus obtained from step ii) with an acid in order to obtain a phytoavailable phosphorus-enriched useful or recyclable material
Data Source
AI summary
The present invention concerns a method for recovering phosphorus by thermochemical reaction of a phosphorus-containing material such as an alternative fuel, for example, in the presence of calcium-containing particles in a moving bed reactor and subsequent separation of fines enriched with phosphorus from the moving bed reactor. Furthermore, the present invention concerns the use of a recyclable material obtained by the method as a fertilizer or fertilizer additive.