Two-Stage Calcium Extraction for High-Purity PCC From Waste
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Solution Overview
Problem
Existing methods for producing high purity calcium carbonate precipitate rely heavily on virgin materials, which are energy-intensive and environmentally detrimental, while industrial by-products like oil shale ash are underutilized and often discarded, posing environmental risks due to high alkalinity and toxic metals.
Innovation Solution
A multistage method using ammonium-based aqueous solutions to extract calcium from industrial wastes like oil shale ash, followed by carbonation to produce high purity calcium carbonate, simultaneously capturing CO2 and producing a silica-rich residual material suitable for industrial use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If water is used as the calcium extracting agent, then the process is simple and easy to operate, but large quantities of water are required and energy consumption for pumping and heating increases
Solution Approach 1:
The patent changes the extraction parameter from water to ammonium-based solution, which fundamentally alters the extraction efficiency and reduces the volume of liquid required. This parameter change resolves the contradiction by maintaining operational simplicity while dramatically reducing water consumption and associated energy costs for pumping and heating.
2Manufacturing precision
If mined limestone is used as feedstock for calcination, then high purity calcium carbonate can be produced, but the process is energy intensive and has large carbon footprint
Solution Approach 1:
The patent extracts calcium directly from industrial waste materials using ammonium-based solutions, bypassing the need for mined limestone and the energy-intensive calcination process. This extraction approach maintains product purity while eliminating the high energy consumption associated with traditional calcination.
Solution Approach 2:
The patent converts industrial waste materials, which are typically discarded as harmful by-products, into valuable calcium carbonate feedstock. This approach eliminates the need for energy-intensive mining and processing of virgin limestone while simultaneously solving waste management problems.
3Productivity
If single stage extraction is used, then the process is simpler and faster, but the residual material contains high concentrations of contaminants and requires extensive treatment
Solution Approach 1:
The patent divides the extraction process into multiple sequential stages, where each stage progressively removes calcium and reduces contaminant concentration in the residual material. This segmentation allows the process to achieve both speed and environmental compliance by treating the residual stream in a controlled, stepwise manner.
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 reduces energy consumption, minimizes environmental impact, and produces a commercially viable calcium carbonate product while valorizing industrial wastes, capturing CO2, and generating a usable silica-rich residual material.
Implementation Method 1
A two stages extraction method for synthesizing precipitated calcium carbonate using ammonium based aqueous solution as the calcium extracting agent
Implementation Method 2
water is used as the calcium extraction solvent
Implementation Method 3
the calcium carbonate is precipitated by passing carbon dioxide through an aqueous suspension of calcium hydroxide
Implementation Method 4
calcium carbonate precipitate
Data Source
AI summary
Present invention relates to a multi-stage method for preparing high purity calcium carbonate precipitate from wastes and by-products containing high concentrations of calcium and silica. The calcium and silica rich material is introduced into a stirred reactor containing the extraction solution. The calcium rich solution, produced in the reactor, is separated from residual material and a gas containing carbon dioxide is passed into the said solution to precipitate calcium carbonate. The calcium carbonate precipitate is then separated from solution. The recovered solution and residual material, from previous extraction stage; is stirred in a reactor to further extract calcium from the residual material. After separating the solids from solution, carbon dioxide containing gas is introduced into solution to again precipitate calcium carbonate. Calcium carbonate precipitate is then separated from solution. The residual material produced from the process is characterized by high silica content.