Magnesium compound as sulfur dioxide absorbent

• Main Author: Muhammad Rafiq Mohd Rosli
• Other Authors: Lim Tuti Mariana
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering; Engineering::Environmental engineering::Environmental pollution
• Online Access: https://hdl.handle.net/10356/149856
• Institution: Nanyang Technological University

In the scrubbing process at power plants as well as incineration plants, flue gas containing Sulfur Dioxide (SO2) is treated with either Lime (CaO) or Limestone (CaCO3) used as absorbents. This process suffers from several drawbacks such as scaling and byproduct disposal issues as the process merely converts air pollutants into solid waste which need to be disposed off properly, typically through land-filling and adds burden to land scarcities. Therefore, there is a need to find an environmentally friendly alternative to effectively remove 2 pollutant whilst introducing benefits to the end user. This study focuses on the application of Magnesium Oxide (MgO) recovered from brine, bittern and ore mining waste as an alternative absorbent. An experimental scrubbing setup is designed from the scratch in order to run preliminary tests in the lab, studying waste-recovered magnesia’s properties in absorbing SO2 gas. The effluent mixture to be treated is designed to mimic that of constituent gases found in power plant flue gas. Slurry mixing times, flow rate of gas introduced into slurry as well as purity of MgO used are tested as part of the design process to create a setup capable of yielding accurate and repeatable outcomes. The overall results show that magnesia based absorbent has an average efficiency of 96% when bubbled with the synthesized flue gas mixture, which is much superior to lime or limestone scrubbing average efficiency of around 80%. Furthermore, the byproduct of MgO, magnesium sulfate (MgSO4) which is a valuable mineral chemical with widespread applications including agricultural (as macro nutrient), medical, construction etc. Consequently, beside value add, it can also eliminate the need for landfill disposal associated with lime or limestone scrubbing and hence providing sustainable solution on SO2 emission. Due to budget constraint, flowmeter was not provided, and it is recommended to include this apparatus in the future for more accurate measurements. Likewise, the byproduct MgSO4 can be further evaluated to determine the percentage yield of MgSO4.