Waste Solid Purification for Soda Ash Production
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Solution Overview
Problem
The soda ash production process faces challenges with impurities such as sodium chloride, sodium sulfate, silicates, and organics in waste solids from tailings ponds, which affect product quality and operational efficiency, leading to equipment scaling, foaming, and reduced yield due to the recycling of these impurities.
Innovation Solution
A method involving selective leaching and optional magnesium treatment to reduce impurities in waste solids before recycling them as a feedstock, using a leach medium leaner in impurities to form a purified solution suitable for producing crystalline sodium carbonate, sodium bicarbonate, or sodium sulfite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If waste solids from tailings ponds are recycled as feedstock in soda ash production, then resource utilization is improved and production costs are reduced, but impurity content increases leading to equipment scaling and reduced product quality
Solution Approach 1:
The patent extracts harmful impurities (sodium chloride, sodium sulfate, silicates, organics) from waste solids through selective leaching processes. The leaching process selectively dissolves these impurities into a leachate stream while leaving the valuable sodium carbonate and bicarbonate in the solid residue, which is then recycled to production. This extraction approach enables resource utilization while removing harmful contaminants.
Solution Approach 2:
The patent introduces a leaching process as an intermediary treatment step between waste solid recovery and feedstock recycling. This intermediary process uses leachate to selectively remove impurities, creating a purified solid intermediate that can be safely recycled. The leaching step acts as a mediator that decouples the conflict between resource utilization and impurity removal.
2Manufacturing precision
If impurities are removed from waste solids through leaching and precipitation processes, then product quality is improved, but process complexity and operational steps increase
Solution Approach 1:
The patent employs parameter changes in the form of controlled pH adjustment and temperature variations to drive selective precipitation of impurities. By changing these physical-chemical parameters, the process achieves selective removal of different impurity types (silicates, sulfates, organics) through sequential precipitation steps, maintaining product quality without requiring complex equipment.
Solution Approach 2:
The patent applies a sequential treatment approach where impurities are removed in stages through leaching and precipitation, with each step targeting specific impurity groups. The leachate and precipitated materials are separated and discarded, while the purified solid is recovered for recycling. This staged approach simplifies each individual step while achieving comprehensive impurity removal.
3Productivity
If waste solids are used as feedstock without impurity removal, then production volume is maintained, but operational efficiency decreases due to scaling and foaming issues
Solution Approach 1:
The patent applies preliminary impurity removal actions (leaching and precipitation) to waste solids before they are introduced as feedstock to the production process. This preliminary treatment prevents operational problems such as scaling and foaming from occurring during production, thereby maintaining ease of operation while enabling continued use of waste solids to sustain production volume.
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 reduces impurity content in waste solids, enhancing their value as feedstock, minimizing operational issues like scaling and foaming, and improving product quality by reducing impurities in the soda ash and other derivative products.
Implementation Method 1
a first step: a selective leaching of some impurities
Implementation Method 2
an optional second step: a selective precipitation of some impurities
Data Source
AI summary
A method for removing impurities from a waste solid to provide at least a portion of a suitable crystallizer feed to a process for making crystalline sodium carbonate, bicarbonate, and/or other derivatives. The method comprises: contacting the waste solid with a leach solution to dissolve at least one impurity and dissolving the resulting leached residue. Leaching may include heap percolation. The leach solution may comprise a crystallizer purge liquor, a process waste effluent, a mine water, or mixtures thereof. The method may further comprise adding a magnesium compound to the resulting leached residue during or after its dissolution to remove another impurity. The waste solid preferably comprises a pond solid containing such impurities. The pond solid may be recovered from a pond receiving crystallizer purge liquor(s) and/or other process waste effluent(s). The pond solid may contain sodium carbonate, any hydrate thereof, sodium bicarbonate, and/or sodium sesquicarbonate. The impurities to be removed may comprise sodium chloride, sodium sulfate, silicates, and/or organics.