Sodium Sulfate Treatment Using KOH and Ammonia Crystallization

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Solution Overview

Problem

Industrial processes produce sodium sulfate waste that contributes to elevated water salinity and stratification, necessitating stringent regulations and inefficient disposal methods, with a need for more effective sulfate removal and reuse strategies.

Innovation Solution

A method using potassium hydroxide and ammonia to precipitate sulfate from sodium sulfate solutions, forming potassium-based sulfates for reuse as fertilizers and sodium hydroxide for industrial chemicals, enhancing solubility reduction and crystallization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional disposal methods (landfilling or conversion to potassium sulfate/Glauber salt) are used for sodium sulfate waste, then sulfate discharge is limited, but the solution is not practical and does not address the growing waste problem

Engineering Contradiction:

Improvesulfate dischargeVSAvoidpracticality of disposal method

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The invention converts harmful sodium sulfate waste into valuable potassium sulfate product through a chemical reaction using potassium hydroxide. The sulfate that was previously a pollutant is transformed into a marketable fertilizer ingredient, eliminating the need for landfilling while creating economic value from waste.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention changes the chemical composition parameters of the waste solution by adding potassium hydroxide and ammonia, transforming sodium sulfate into potassium sulfate. This parameter change enables the waste to become a useful product that can be discharged or utilized, solving both the disposal practicality and environmental harm issues.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If potassium hydroxide is added to precipitate sulfate, then sulfate removal efficiency is improved, but the process requires additional chemicals and process complexity

Engineering Contradiction:

Improvesulfate removal efficiencyVSAvoidprocess complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

Ammonia serves as an intermediary substance that facilitates the precipitation reaction between potassium hydroxide and sulfate. The ammonia forms intermediate compounds that enhance the precipitation efficiency, allowing for effective sulfate removal while maintaining a relatively simple process flow.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention uses a composite chemical system combining potassium hydroxide and ammonia to achieve superior sulfate removal. The synergistic interaction between these two chemicals creates a more effective treatment process than either chemical alone, improving productivity without proportionally increasing complexity.

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If ammonia is added to the reaction mixture, then sulfate precipitation is enhanced, but the process requires precise concentration control

Engineering Contradiction:

Improvesulfate precipitation completenessVSAvoidconcentration control

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The invention implements feedback control by monitoring the concentration of ammonia in the reaction mixture and adjusting the addition rate accordingly. This ensures that the ammonia concentration remains within the optimal range (at least 10 g/l) to maximize sulfate precipitation while avoiding excessive ammonia that could cause operational difficulties or environmental issues.

Inventive Principle:

Principle #23Feedback

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 method achieves efficient sulfate removal and conversion to valuable products, reducing environmental impact and waste, while being cost-effective and low-temperature processed.

Implementation Method 1

mixing at least the potassium hydroxide with the first solution to obtain a reaction mixture, whereby obtaining a first solid fraction comprising precipitated sulfate

Methodology Applied

Scientific EffectPrecipitation: Precipitation

Implementation Method 2

Thanks to the method according to the invention, solubility of the sulfate is lowered which enables better crystallization/precipitation of the sulfate

Methodology Applied

Scientific EffectSolubility reduction:

Data Source

PatentEP4613710A1Method for treating a solution containing sodium sulfate

Publication Date: 2025.09.10 UMICORE BATTERY MATERIALS FINLAND OY

AI summary

A method for treating a first solution containing sodium sulfate obtainable from an industrial process, the method comprising: providing the first solution, preferably the first solution is alkaline; providing potassium hydroxide, preferably in solid form and/or as a second solution containing potassium hydroxide of 25 wt.% or more, such as in the range 25-75 wt.%; mixing at least the potassium hydroxide with the first solution to obtain a reaction mixture, whereby obtaining a first solid fraction comprising precipitated sulfate and a first liquid fraction comprising sodium hydroxide; and recovering the first solid fraction and the first liquid fraction; wherein the method further comprises providing a source of ammonia (NH3) to obtain a concentration of NH3(aq) in the reaction mixture of at least 10 g/l.