**4.2 Yield calculation from dunite carbonated product**

For magnesite yield calculation, please refer to earlier publication [10]. Carbonated products were heated in TGA from 25 to 1000°C and mass losses due to decomposition of different phases present are identified. To identify the evolving gases generated during heating, the TGA-DSC (Setsys Evolution 1200) was coupled with a mass spectrometer (Thermostar Quadrupole). Lizardite decomposes over the same temperature range (300–600°C) as the magnesite and this can introduce a slight systematic error in magnesite yield estimation (leading to an over-estimation of the magnesite yield) unless the mass loss in this period can be quantitatively attributed to loss of H2O or CO2 from the sample. To distinguish between these species, the ion current from the m/z = 44 ion (CO2 + ) from mass spectrometer was calibrated using sodium bicarbonate samples and a calibration curve for CO2 concentration is obtained, which is used to quantify CO2 mass loss (distinguishing CO2 production from the loss of water vapour which occurs simultaneously) and thus render more accurate estimation of the magnesite yield. CO2 peak areas were calculated using the

*Testing and Validating Instruments for Feedstocks of Mineral Carbonation DOI: http://dx.doi.org/10.5772/intechopen.101175*
