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HOMERecycling of Sodium Chloride

Recycling of aqueous brine solution (Sodium Chloride) containing organo-tin complex


case-study-recycling-of-brine-picIn this project the experimental development work was done to achieve technological and product advancement for recycling of aqueous brine solution contaminated with Organo –Tin complexes; the by-product from a chemical manufacturing of PVC stabilizers and PVC composites. This byproduct, which contained 22% dissolved sodium chloride (NaCl) and ppm levels of Organo- Tin complexes. The customer made a decision to develop a recycling or reusing alternative for the byproduct. Our team has examined several chemical reactions and techniques related to Tin organic complexes and its chemical stability. The main issue to reuse spent aqueous brine solution contaminated with Organo-Tin complexes (spent Sodium Chloride) is to reduce soluble Tin content in NaCl solution to meet product specification for industrial applications. We proposed to reduce soluble Tin content in NaCl solution to very low levels by decomposing the Organo-Tin complex to non-soluble form with subsequent precipitation and separation of non-soluble Tin concentrate. Based on known regime results it was recommended to test variables such as pH, temperature, retention time, mixing methods, which could lead to increased efficiency of Tin separation from NaCl solution. Customer has decided to conduct lab and bench-scale tests in order to identify a type and optimum concentration of additives, pH, temperature and other parameters that could be used for further testing to reduce soluble Tin content in NaCl to very low levels which would lead to a product with best chance to be applied on the market. The results of the lab tests were to be used to develop a pilot-scale study. The pilot system consisted of a reactor to carry out a series of experiments to investigate different processing regimes. After Tin precipitation a liquid/solid separation technique was tested to optimize process of Tin separation from sodium chloride. The goals of this project were to establish an optimum reaction regime including type of additives, its concentration and feed rate, reaction time, maximum temperature and agitation to achieve highest efficiency of the process. The set of operating protocols that were used for the pilot-scale trials were later adapted to the full-scale system.

 
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