Metal Sulfate Crystallization With Pre-Leaching Impurity Removal
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Solution Overview
Problem
The presence of calcium, magnesium, and/or lithium impurities in feedstocks used for producing crystallized metal sulfates for batteries leads to processing difficulties such as contamination, higher energy consumption, and unwanted solids formation due to low solubility of calcium sulfate salts, resulting in supersaturated process streams.
Innovation Solution
A treatment process involving pre-leaching with a lixiviant to selectively extract a first portion of impurities, refining the feedstock to remove a second portion, and crystallizing the metal sulfate from the leached solution, with optional basification of the mother liquor to convert remaining impurities to basic metal salts for reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional processing is used without pre-leaching, then the process is simpler, but impurity removal efficiency is poor and product purity is low
Solution Approach 1:
The patent applies preliminary action by implementing a pre-leaching step before the main crystallization process. The pre-leach circuit selectively removes calcium and magnesium impurities from the feedstock using sulfuric acid leaching, creating a cleaner input for the subsequent crystallization stage. This preliminary purification action prevents impurity carryover and improves final product purity without requiring complete impurity removal in the main process.
Solution Approach 2:
The patent segments the impurity removal process into two distinct stages: (1) pre-leaching in a separate circuit that targets calcium and magnesium removal, and (2) main crystallization that produces the final metal sulfate product. This segmentation allows each stage to be optimized for its specific function, with the pre-leach circuit handling impurity removal and the main circuit focusing on product crystallization, thereby improving overall manufacturing precision.
2Productivity
If sulfate-media based processes are used, then metal sulfate crystallization is effective, but calcium sulfate low solubility causes unwanted solids formation and process difficulties
Solution Approach 1:
The patent applies the extraction principle by removing calcium and magnesium impurities from the feedstock in the pre-leaching circuit before the sulfate-media crystallization process. By extracting these problematic impurities early using acid leaching and selective precipitation, the patent prevents them from causing unwanted calcium sulfate solids formation in the main crystallization circuit, thereby eliminating the harmful effect while maintaining crystallization efficiency.
Solution Approach 2:
The patent applies preliminary anti-action by pre-treating the feedstock to remove calcium and magnesium impurities before they can cause harmful calcium sulfate precipitation in the main process. The pre-leaching circuit performs this anti-action by selectively dissolving and removing these impurities, preventing the subsequent formation of unwanted solids that would otherwise interfere with the crystallization process and product purity.
3Manufacturing precision
If multiple impurity removal steps are added, then impurity reduction is improved, but energy consumption increases
Solution Approach 1:
The patent applies parameter changes by utilizing pH control and selective precipitation chemistry to achieve efficient impurity removal. The pre-leaching process uses controlled acidification followed by selective base addition to precipitate calcium and magnesium as carbonates or hydroxides. This parameter-based approach (pH adjustment, selective precipitation) achieves high impurity removal efficiency without requiring multiple energy-intensive separation steps, as the chemical parameters naturally drive the separation process.
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 effectively reduces impurities, improving the purity of crystallized metal sulfates and reducing energy consumption by selectively removing calcium and magnesium impurities, thereby enhancing the efficiency and quality of battery materials production.
Implementation Method 1
pre-leaching the feedstock with a lixiviant to selectively extract a first portion of the impurities
Implementation Method 2
crystallizing the metal sulfate from the leached solution
Implementation Method 3
basification of the mother liquor to convert remaining impurities to basic metal salts
Data Source
AI summary
A treatment process for crystallizing a metal sulfate involving pre-treating a feedstock comprising calcium, magnesium, and/or lithium impurities, the pre-treating involving pre-leaching the feedstock in the presence of a lixiviant, selectively extracting a first portion of any of the impurities from the feedstock, and forming a leached solution comprising an uncrystallized metal sulfate and any remaining impurities; and/or refining the leached solution and removing a second portion of any of the remaining impurities; and crystallizing the uncrystallized metal sulfate from the leached solution to form a crystallized metal sulfate. So processed, the crystallized metal sulfate may be battery-grade or electroplating-grade.