Phosphate-Enriched Fertilizer Granules With Two-Stream Heavy Metal Removal
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Solution Overview
Problem
Existing methods for recycling phosphate from incineration residues produce fertilizers with low phosphate content and high heavy metal concentrations, leading to waste and environmental issues, and require additional phosphate components from conventional sources, which are costly and unsustainable.
Innovation Solution
A two-stream process for producing phosphate-enriched, heavy metal-depleted fertilizer granules by separating and precipitating phosphates, using a reactant to dissolve and separate heavy metals, and combining the resulting phases to create a fertilizer with enhanced phosphate availability and reduced heavy metal content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If leaching processes are used to extract phosphorus from incineration residues, then phosphate purity is improved, but heavy metal separation becomes more complex and expensive
Solution Approach 1:
The process is divided into two independent streams: Stream A handles phosphate extraction and purification, while Stream B handles heavy metal separation. This segmentation allows each stream to be optimized for its specific function, reducing overall process complexity while maintaining high phosphate purity in Stream A and effective heavy metal removal in Stream B.
Solution Approach 2:
A solvent extraction step is introduced as an intermediary process between incineration and fertilizer production. The solvent selectively dissolves phosphorus compounds while leaving heavy metals in the residue, which is then separated. This intermediary step simplifies subsequent processing by pre-concentrating phosphate and pre-separating heavy metals before the main fertilizer production line.
2Quantity of substance
If conventional phosphate components are added to increase phosphate content, then fertilizer phosphate concentration is improved, but cost and sustainability are worsened
Solution Approach 1:
The process enables self-service by recovering and concentrating phosphate from incineration residues through the two-stream process. Stream A extracts and concentrates phosphate from the residue, producing a phosphate-rich product that can be directly used in fertilizer formulation. This eliminates or reduces the need for conventional phosphate rock processing, making the system self-sufficient and sustainable.
Solution Approach 2:
Instead of discarding incineration residues as waste, the process recovers valuable phosphate components through selective dissolution and separation in Stream A. The phosphate is concentrated and purified, then reused in fertilizer production. This recovery approach replaces conventional phosphate inputs and reduces dependency on non-renewable phosphate rock resources.
3Reliability
If incineration temperatures are increased to improve nutrient availability, then phosphorus plant availability is improved, but heavy metal concentration is worsened
Solution Approach 1:
The process extracts and separates heavy metals from the incineration residue through Stream B, which is dedicated to heavy metal removal. By taking out heavy metals as a separate stream, the process eliminates the trade-off between incineration temperature and heavy metal concentration, allowing optimal incineration conditions to be used for nutrient availability while heavy metals are subsequently removed through the separation stream.
Solution Approach 2:
The process converts the harmful concentrated heavy metals in incineration residue into a separable stream that can be disposed of or treated separately. By using the concentration effect of incineration to bring all components together, then applying selective dissolution and separation, the harmful heavy metals are isolated in Stream B while the beneficial phosphate is recovered in Stream A, turning a problem into a manageable separation task.
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 process results in a fertilizer with higher phosphate concentration and lower heavy metal content, improving plant growth and soil health without additional conventional phosphate components, thus being more sustainable and cost-effective.
Implementation Method 1
a reactant is added to dissolve and react with the inorganic secondary phosphate and/or to convert the inorganic secondary phosphate by reaction in such a way that a phosphate which is more readily soluble in neutral ammonium citrate is formed
Implementation Method 2
Addition of a heavy metal precipitation agent during the preparation of the raw material dispersion and/or during the incubation time and/or after the incubation time
Implementation Method 3
Precipitation of phosphate from the phosphate-containing liquid phase
Data Source
AI summary
A phosphate-enriched, heavy metal-depleted fertilizer granulate includes at least one inorganic secondary phosphate, which is produced by a two-stream process, wherein a raw material dispersion is fed to process stream A and process stream B, in which this raw material dispersion either is produced in process step a) from at least one inorganic secondary phosphate and at least one reactant and this produced raw material dispersion is fed divided to process stream A and B or in process step a′) the inorganic secondary phosphate is first divided, are produced separately from one another and these separately produced raw material dispersions are fed to process stream A and B. The proportion of a liquid phase is greater than 30% and the incubation time between inorganic secondary phosphate and reactant is between 1 to 100 minutes.