Calcium Thiosulfate Production via SO2 Absorption
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Solution Overview
Problem
Current methods for producing calcium thiosulfate are inefficient, resulting in low purity and high byproduct formation, with existing processes either requiring expensive raw materials or generating contaminants like ammonia or sodium chloride, and there is a need for an environmentally friendly method to utilize sulfur dioxide as an air pollutant for its conversion.
Innovation Solution
A process involving the reaction of sulfur dioxide with sulfur and hydrated lime or lime-sulfur, under specific conditions, to produce high concentration and high purity calcium thiosulfate, utilizing sulfur dioxide from industrial sources, and employing a contactor/reactor apparatus for efficient gas-liquid contact and pH control to minimize byproduct formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to produce calcium thiosulfate, then production can be achieved, but the purity is low and byproduct formation is high
Solution Approach 1:
The patent optimizes reaction parameters including temperature (80-95°C), pH (2.5-4.0), and molar ratios of reactants to maximize calcium thiosulfate purity while minimizing byproducts. Specific parameter ranges are identified through experimental data showing peak performance at these conditions.
Solution Approach 2:
The patent converts sulfur dioxide, an air pollutant and harmful substance, into a useful reactant for producing calcium thiosulfate. The harmful SO2 gas is absorbed and transformed into a valuable chemical product, simultaneously addressing pollution and production needs.
2Manufacturing precision
If expensive raw materials are used, then high purity calcium thiosulfate can be produced, but production cost increases
Solution Approach 1:
The patent employs inexpensive raw materials including sulfur dioxide gas, sulfur, and hydrated lime instead of costly chemicals. These readily available, low-cost materials achieve the same production goals without requiring expensive reagents or specialized inputs.
Solution Approach 2:
The patent utilizes sulfur dioxide from industrial flue gases, a waste stream that would otherwise require costly disposal or treatment. By using this waste gas directly as a reactant, the process eliminates the need for expensive pure chemical inputs while simultaneously solving an environmental problem.
3Productivity
If sulfur dioxide is emitted to atmosphere, then industrial process can proceed, but air pollution increases
Solution Approach 1:
The patent captures sulfur dioxide emissions from industrial processes and converts them into a valuable reactant for calcium thiosulfate production. The harmful pollutant becomes a useful chemical feedstock, eliminating emissions while creating additional product value.
Solution Approach 2:
The patent serves multiple functions simultaneously: it produces calcium thiosulfate as a plant nutrient, removes sulfur dioxide pollution from the atmosphere, and utilizes inexpensive raw materials. This multi-functional approach addresses environmental, economic, and productivity concerns in a single integrated 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 achieves high purity and concentrated calcium thiosulfate production with minimal byproducts, utilizing inexpensive raw materials and sulfur dioxide from industrial sources, making it an effective and environmentally friendly plant nutrient solution.
Implementation Method 1
reacting sulfur dioxide with sulfur and hydrated lime or calcium polysulfide to produce calcium thiosulfate
Implementation Method 2
employing a contactor/reactor apparatus for efficient gas-liquid contact
Data Source
AI summary
An efficient batch or semi-continuous method of production of relative high concentration, low byproduct-containing, calcium thiosulfate (CaS2O3) from lime, sulfur or calcium polysulfide, and sulfur dioxide under elevated reaction temperature conditions is described. The product is an emulsion of liquid calcium thiosulfate and solid byproducts. Under the conditions of the art, including the mole ratios of lime to sulfur, the temperature of the reaction process and the sulfur dioxide reaction conditions, including rate and duration, the byproducts are reduced to about 2% by weight.