Tin Reactant Purifies TiCl4 Arsenic Contamination
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Solution Overview
Problem
The chloride process for producing TiCl4 results in arsenic contamination due to the similarity in boiling points of AsCl3 and TiCl4, making existing purification methods inefficient and costly, especially when high arsenic levels are present in the ore, leading to undesirable arsenic levels in TiO2 pigment and titanium metal.
Innovation Solution
Using tin metal to selectively remove arsenic from crude TiCl4, producing SnCl4 and solid arsenic, which are then separated, allowing for a two-stage process to achieve low arsenic levels without significant yield loss or energy-intensive distillation, and also addressing vanadium contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation is used to remove AsCl3 from TiCl4, then arsenic concentration is reduced, but energy consumption increases significantly and TiCl4 yield is lost
Solution Approach 1:
The invention changes the chemical state of arsenic by reacting AsCl3 with tin metal to form solid As and SnCl4, transforming the separation problem from a physical distillation process to a chemical reaction followed by simple filtration. This parameter change from physical to chemical separation method dramatically reduces energy consumption while achieving the same purification goal
Solution Approach 2:
The reaction converts gaseous AsCl3 into solid arsenic metal, creating a phase transition that enables easy separation through filtration rather than energy-intensive distillation. The solid precipitate can be readily separated from the liquid TiCl4 phase, solving the contradiction between purification efficiency and energy consumption
2Productivity
If distillation is used to produce concentrated AsCl3 for disposal, then TiCl4 yield loss is reduced, but the AsCl3 product has no commercial value and requires expensive disposal
Solution Approach 1:
The invention converts the harmful AsCl3 waste product into beneficial solid arsenic metal and valuable SnCl4 coproduct through reaction with tin. Instead of disposing of toxic AsCl3, the process transforms it into marketable materials, simultaneously improving TiCl4 yield and eliminating disposal hazards
Solution Approach 2:
Rather than discarding AsCl3 as waste, the invention recovers it by reacting with tin to produce solid arsenic that can be filtered and disposed of safely, while recovering SnCl4 as a valuable coproduct. This transforms a waste management problem into a resource recovery opportunity
3Manufacturing precision
If carbon adsorption is used to remove AsCl3, then arsenic is removed to very low levels, but many other species adsorb competitively limiting capacity and making it not commercially viable
Solution Approach 1:
The invention extracts arsenic from the mixture through selective chemical reaction with tin metal, pulling AsCl3 out of the TiCl4 stream and converting it to solid arsenic. This selective extraction method avoids the non-selective adsorption of carbon, achieving high purification while maintaining commercial viability through simple filtration and valuable coproduct formation
Solution Approach 2:
Tin metal serves as an intermediary substance that selectively reacts with AsCl3 to form solid arsenic and SnCl4. This intermediary enables selective removal of arsenic without the competitive adsorption problems of carbon, making the process commercially viable while achieving very low arsenic concentrations in the purified TiCl4
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 arsenic levels to below detectable limits in TiCl4, suitable for cosmetics and titanium metal production, while producing a valuable coproduct SnCl4 and reducing energy consumption and disposal hazards, without the formation of toxic byproducts.
Implementation Method 1
contacting arsenic-containing crude TiCl4 with tin to produce purified TiCl4, SnCl4, and solid arsenic
Data Source
AI summary
The present disclosure relates to reacting tin metal with crude TiCl4 containing arsenic to produce pure TiCl4, SnCl4, and an arsenic solid co-product. In some embodiments, the contaminant vanadium is removed as well. The reaction is preferably done in a continuous fashion in two stages for maximum through-put and utility at an elevated temperature. Distillation can be used to purify the TiCl4 produced and simultaneously yield a purified SnCl4 product. The synthesis of SnCl4 in this method utilizes waste chloride to save virgin chlorine which would otherwise be used.