Calcium Phosphate Reactant Production for Heavy Metal Immobilization
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Solution Overview
Problem
Existing calcium phosphate reactants used for heavy metal immobilization are too fine, leading to handling issues in sludge blanket treatment and excessive phosphate release, which can cause eutrophication and environmental pollution.
Innovation Solution
A process to produce calcium phosphate reactants with adjusted Ca/P molar ratios and pH levels, resulting in particles with larger diameters and higher specific surface areas, which are less soluble and have improved adsorption capacity, reducing phosphate emissions and enhancing heavy metal immobilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If calcium phosphate reactants with high specific surface area are used for heavy metal immobilization, then adsorption capacity is improved, but particle size becomes too fine causing handling issues and reactant loss in decantors
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Ca/P molar ratio (1.4-1.8) and pH (5-10, preferably 7-8) during reactant production, along with controlled stirring parameters, to obtain calcium phosphate particles with optimized characteristics: high specific surface area (about 130 m2/g) while maintaining adequate particle size (weight-average diameter less than 10 μm but sufficient for handling) to prevent excessive loss in decantors while retaining heavy metal adsorption capacity
2Quantity of substance
If fine calcium phosphate particles are used to increase surface area, then heavy metal adsorption is improved, but phosphate release increases causing eutrophication risk
Solution Approach 1:
The patent applies parameter changes by optimizing the Ca/P molar ratio to 1.4-1.8 and controlling pH at 5-10 (preferably 7-8) during production, which creates calcium phosphate particles with a specific crystalline structure and surface properties that provide high heavy metal adsorption capacity while simultaneously reducing phosphate solubility and release, thus mitigating eutrophication risk
3Reliability
If particle size is reduced to increase specific surface area, then reactivity is improved, but particles are easily entrained out of reactors causing reactant loss
Solution Approach 1:
The patent applies parameter changes by controlling the Ca/P molar ratio (1.4-1.8), pH (5-10), and stirring conditions during production to obtain calcium phosphate particles with an optimized size distribution: high specific surface area (about 130 m2/g) for high reactivity and heavy metal adsorption, while maintaining weight-average diameter characteristics that reduce excessive entrainment in decantors, thus balancing reactivity with reactant retention
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 produces calcium phosphate reactants with larger particle sizes and higher specific surface areas, effectively immobilizing heavy metals while minimizing phosphate release, thus addressing handling issues and environmental concerns.
Implementation Method 1
a source of calcium and a source of phosphate ions in water are used in a molar ratio that is adjusted so as to obtain a Ca/P molar ratio of between 0.5 and 1.6, and the source of calcium is reacted with the phosphate ions
Data Source
AI summary
A process for producing a calcium phosphate reactant, according to which: in a first step, use is made of a source of calcium and a source of phosphate ions in water, in a molar ratio that is adjusted so as to obtain a Ca/P molar ratio of between 0.5 and 1.6, and the source of calcium is reacted with the phosphate ions at a pH of between 2 and 8, in order to obtain a suspension (A) of calcium phosphate, and in a second step, added to the suspension (A) are an alkaline compound comprising hydroxide ions in order to set a pH of more than 8 and an additional source of calcium in order to obtain a suspension (B) of calcium phosphate reactant having a Ca/P molar ratio of more than 1.6. A calcium phosphate reactant obtainable by such a process.