Mixed Wolframite Scheelite Decomposition via Composite Leaching
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Solution Overview
Problem
Current methods for decomposing mixed wolframite and scheelite ore in China face high leaching agent consumption and costs, with existing processes using sodium hydroxide or sodium carbonate being inefficient and prone to reactor issues, while existing methods are complex and require multiple steps.
Innovation Solution
A method using a combination of sodium phosphate, sodium hydroxide, and calcium fluoride as decomposition agents in an alkaline system to synergistically decompose mixed wolframite and scheelite ore, achieving tungsten extraction in a single step with reduced leaching agent consumption and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sodium hydroxide is used to leach mixed wolframite and scheelite ore at high pressure, then decomposition efficiency is improved, but leaching agent consumption increases to 2-5 times the theoretical amount and leaching cost increases significantly
Solution Approach 1:
The patent uses a composite leaching system comprising sodium hydroxide, sodium carbonate, and calcium fluoride working together. This composite approach allows sodium hydroxide to effectively decompose wolframite while sodium carbonate and calcium fluoride handle scheelite decomposition, reducing overall consumption of each individual agent compared to using sodium hydroxide alone for both minerals.
Solution Approach 2:
The patent optimizes reaction parameters including temperature (90-200°C), pressure (0.4-2.0 MPa), and molar ratios of leaching agents to mineral components. By carefully controlling these parameters, the system achieves high decomposition efficiency while minimizing excess reagent consumption through precise stoichiometric management.
2Productivity
If sodium carbonate is used to decompose mixed wolframite and scheelite ore at high temperature and high pressure, then decomposition is achieved, but reactor caustic embrittlement occurs and safe production is compromised
Solution Approach 1:
The patent lowers the operating temperature range to 90-200°C and pressure to 0.4-2.0 MPa, significantly milder than conventional high-temperature high-pressure processes. This parameter reduction eliminates caustic embrittlement of reactor equipment while maintaining effective decomposition through the synergistic leaching system and extended reaction time.
Solution Approach 2:
The patent introduces calcium fluoride as an intermediary substance that facilitates scheelite decomposition through fluorine substitution, allowing the reaction to proceed at lower temperatures and pressures. Calcium fluoride acts as a catalyst-like mediator that enables effective leaching without requiring extreme thermal and pressure conditions that would compromise reactor integrity.
3Manufacturing precision
If existing ore dressing methods are used to separate wolframite concentrate and scheelite concentrate from mixed ore, then separation is attempted, but tungsten recovery rate is low
Solution Approach 1:
The patent combines the decomposition of both wolframite and scheelite into a single unified leaching process using a composite reagent system. This merging approach converts both minerals to soluble tungstate forms simultaneously, achieving high tungsten recovery without the losses inherent in multi-step physical separation methods that struggle with fine-grained intergrown ores.
Solution Approach 2:
The patent employs optimized chemical parameters including pH control (maintained at 12-14), temperature (90-200°C), and specific molar ratios of leaching agents to ensure complete decomposition of both mineral types. These parameter optimizations maximize tungsten extraction efficiency while minimizing recovery losses.
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 a tungsten decomposition rate above 94% with significantly reduced leaching agent consumption, simplifying the process and lowering costs, while ensuring safe operation by minimizing reactor stress.
Implementation Method 1
adding sodium phosphate, sodium hydroxide, calcium fluoride and water for synergistic decomposition
Implementation Method 2
decomposing mixed wolframite and scheelite ore in an alkaline system
Data Source
AI summary
The present invention discloses a method for effectively decomposing mixed wolframite and scheelite ore in an alkaline system, specifically comprising steps of: grinding mixed wolframite and scheelite ore, putting in an autoclave, adding an appropriate amount of water, and then adding sodium phosphate, sodium hydroxide and calcium fluoride for decomposition, and treating by solid-liquid separation to obtain crude sodium tungstate solution. The present invention has the advantage that the high-efficiency decomposition of the mixed wolframite and scheelite ore can be realized with low consumption of leaching agents. By this method, the mixed wolframite and scheelite ore can be directly treated by an existing tungsten smelting autoclave, with low leaching cost, high decomposition rate and easy industrial application.