Iron Sulphate Monohydrate Crystallization via Pressure Vessel
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Solution Overview
Problem
Existing methods for processing iron sulfate heptahydrate to iron sulfate monohydrate are energy-inefficient and result in high residual moisture and iron content variability, limiting their effectiveness in industrial applications.
Innovation Solution
A process involving heating an aqueous solution of iron sulfate heptahydrate in a pressure vessel above the boiling point to precipitate iron sulfate monohydrate, followed by controlled separation and further processing to achieve a product with low residual moisture and controlled iron content, utilizing superheated steam to enhance crystallization and agglomeration, and optionally recovering iron as iron oxides or hydroxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If thermal drying is used to convert iron sulfate heptahydrate to monohydrate, then the conversion is achieved, but energy consumption is high
Solution Approach 1:
The invention changes the pressure parameter from atmospheric to superatmospheric, allowing the process to occur at temperatures above the boiling point of water. This enables conversion through solubility changes rather than thermal drying, significantly reducing energy consumption while maintaining high conversion efficiency
Solution Approach 2:
The invention utilizes phase transition of water from liquid to vapor at superatmospheric pressure, and exploits the solubility-temperature relationship to induce crystallization. The pressure-induced phase change allows energy-efficient water removal without requiring high-temperature thermal drying
2Use of energy by moving object
If melting process is used to convert iron sulfate heptahydrate, then energy consumption is reduced, but iron sulfate remains in mother liquor
Solution Approach 1:
By changing to superatmospheric pressure conditions, the invention alters the solubility behavior of iron sulfate. The solubility decreases with increasing temperature at these pressures, causing complete or near-complete precipitation of iron sulfate monohydrate and minimizing losses in the mother liquor
Solution Approach 2:
The invention dynamically adjusts temperature and pressure parameters during the process to optimize both energy efficiency and recovery. The controlled pressure-temperature profile ensures maximum precipitation while minimizing energy input, resolving the trade-off between energy consumption and substance recovery
3Duration of action of stationary object
If iron sulfate heptahydrate is stored at temperatures above 25°C, then storage is possible, but it melts in its own crystal water
Solution Approach 1:
The invention changes the pressure parameter to superatmospheric levels, which stabilizes the iron sulfate monohydrate form at temperatures above 25°C. This prevents the melting phenomenon observed at atmospheric pressure, enabling stable storage and transport of the monohydrate product in its desired 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 process achieves energy-efficient conversion of iron sulfate heptahydrate to monohydrate with controlled residual moisture and iron content, increasing yield and facilitating further processing, while minimizing trivalent iron content and optimizing product properties for industrial uses.
Implementation Method 1
heating mixture I to a temperature T1 above the boiling point of mixture I at atmospheric pressure lies
Implementation Method 2
forming iron sulfate monohydrate as a solid and a solution II
Implementation Method 3
the temperature of the ferrous sulfate monohydrate solid falls to a temperature T3 corresponding to the pressure P3
Data Source
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AI summary
The invention is directed to a process for the further processing of iron sulphate heptahydrate to iron sulphate monohydrate. The process comprises the steps: a) forming an aqueous solution or suspension of iron sulphate heptahydrate in a container (mixture I), b) conveying mixture I into a first pressurized vessel and heating mixture I to a temperature T1, which is above the boiling temperature of mixture I at atmospheric pressure, where a pressure P1 is formed and where iron sulphate monohydrate forms as solid and a solution II, c) separating off the iron sulphate monohydrate solid from solution II, d) conveying the separated-off iron sulphate monohydrate solid with adhering solution II into a further pressurized vessel with a pressure P3, where P3 is lower than the pressure which prevails in step c), and where the temperature of the incoming solid with adhering solution II is above the boiling temperature of solution II at the pressure P3 and where a temperature T3 corresponding to the pressure P3 is formed in the further pressurized vessel. Optionally the iron remaining in the solution II is furthermore recovered by reacting solution II in an oxidation reactor with air or oxygen and optionally additives, and iron oxide and/or iron hydroxide being formed in solid form.