Critical Analysis of Indian Soda Lime: Scope of Improvement

Abstract

Soda lime is one of the most popular carbon dioxide absorbent materials to be used for closed-circuit life saving safety breathing apparatus in mining industries. A trained rescue person uses it during a situation such as a fire, explosion or emission of toxic gasses in underground mines. This paper evaluates the chemical composition and physical properties of soda lime using specific parameters (moisture, carbon dioxide gas absorption, granule shape and fine particle size) which plays an important role in its application in breathing apparatus. Results indicated that soda lime moisture content, fine grains and hardness ranged between 11.6-18.3%, 0.2-1.9g, and 70-90%, respectively. The CO₂ absorption rate was observed to be 20.0 to 57.0 minutes compared to standard UK Protosorb soda lime CO₂ (135 minutes). X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscope (SEM) analysis of the samples were carried out to understand the changes in molecular structure of the material before and after CO₂ absorption. The XRD result indicated presence of portlandite (48.5%),calcite (49.6%) and potassium rhenium sulfide telluride cyan acetate (PRSTCA) (1.84%) before CO₂ absorption and calcite/ calcium carbonate (89.4%) portlandite (3.38%) and octasodium d-potassium tetra hydrogen dihydroxo tetra telluride dipalladate (7.2%), 20-hydrate was observed after CO₂ absorption. EDS of sample 6 indicated presence of carbon (4.94%), oxygen (39.80%) sodium (3.36%) and calcium (51.90%) before CO₂ absorption and carbon (6.27%), oxygen (36 96%), sodium (1.37%) and calcium (55.40%) after CO₂ absorption.