%of CaO in dunite ¼ 0*:*35%

%of Ca in dunite ¼ 71*:*4% � 0*:*0035 ¼ 0*:*25%

y*Ca* ¼ 0*:*0025 (using this value in Eq. 5)

$$\frac{1}{\text{RCO}\_2} = \left(\frac{\mathcal{Y}\_{\text{Mg}}}{\mathcal{M}W\_{\text{Mg}}} + \frac{\mathcal{Y}\_{\text{Ca}}}{\mathcal{M}W\_{\text{Ca}}}\right) \times \text{MW}\_{\text{CO}\_2}(equation\ 5)$$

$$\frac{1}{\text{RCO}\_2} = \left(\frac{0.257}{24.3} + \frac{0.0025}{40}\right) \times 44 = 0.468$$

$$\text{RCO}\_2 = \left(\frac{1}{0.468}\right) = 2.136\text{ (using this value in equation 4)}$$

$$\text{Yield}\,(\text{Rx}) = 2.136 \times \left(\frac{\text{TGA}}{(100 - \text{TGA})}\right) \times 100\% \tag{5}$$

WCO2 = Weight of CO2 present in dunite before carbonation.

Wmineral = Weight of dunite present before carbonation.

1/RCO2 = CO2 storage capacity of dunite. yMg = Weight fraction of magnesium present in dunite which can react with CO2. MWMg = Molecular weight of magnesium (24.3 g/g mol). MWMgO = Molecular weight MgO (40.3 g/g mol). yCa = Weight fraction of calcium present in dunite which can react with CO2. MWCa = Molecular weight of calcium (40 g/g mol). MWCaO = Molecular weight of CaO (56 g/g mol). MWCO2 = Molecular weight of CO2 (44 g/g mol). RCO2 = Mass of dunite required to store unit mass of CO2. TGA = CO2 mass loss from calibration curve. RX = Yield or extent of carbonation. For a detailed description of materials, analytical instruments and

experimental methods, please refer to Chapter 3 of the Ph.D. thesis [2]. Materials, Dunite, heat-activated dunite, heat-transformed dunite, twin sisters mountain dunite, olivine, lizardite and heat-activated lizardite are discussed. Analytical instruments, TGA-MS, XRD, Semi-Quantitative XRD (QXRD), ICP-OES, SEM, EDS, TEM, FTIR and Malvern Mastersizer are discussed. Experimental methods, acid dissolution, regrinding, single-stage carbonation, acrylic reactor testing without temperature and pressure, concurrent grinding both in situ and in operando and two-stage carbonation are discussed. Please refer to these publications for further details [2, 10, 13, 14, 18, 19].

A comparison of elemental composition of dunite by ICP-OES and XRF is provided in **Table 7**.

### **4.3 Magnesite yield results using different feedstocks**

Magnesite yield results using various feedstocks are presented in **Table 8**. Few of these results are presented graphically in **Figure 17**. For already published results, please refer to [2, 19] and [10, 18] and [13, 14]. Soaked dunite especially heatactivated provided the highest yields. This is not evident from literature, especially for heat-activated dunite. However, for raw dunite, some results are presented in Ph.D.

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


### **Table 7.**

*Comparison of elemental composition of dunite by ICP-OES and XRF.*



### **Table 8.**

*Yield results for different feedstocks under various experiment and reaction conditions.*

thesis. Dunite yield calculation is very easy and straightforward, please refer to my Ph.D. thesis publication. Six times higher magnesite yields, or say an increase of 600% [10, 14], or almost two times higher yields in two-stage [13] were achieved using concurrent grinding. Olivine does not accept this much, but still shows some increased trend.

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

**Figure 17.** *Comparison of reactivity of dunite, soaked dunite, heat-activated dunite and lizardite and raw dunite soaked.*

### **4.4 Semiquantitative XRD results authenticity**

Authenticity of QXRD is shown in **Table 5**.

### **4.5 TGA-MS results authenticity**

TGA-MS results authenticity is excellent. Please see the consistency of magnesite results, which are constant. However, these results have variations as per variation of size fraction.

### **Error in Brucite calculation due to slight peak overlap.**

Error and second option of calculation is shown in **Figure 18**. Sr.No. 1. QXRD Calculation details.

**Figure 18.** *The left-hand side image graph shows overlap. The right-hand side shows an alternative option.*


### **More results related to this TGA-MS matching with QXRD.**

A very good match between TGA-MS and QXRD results was obtained when using an olivine peak at 17.3°. Brucite also shows a good match. The same peak points were used for all 3 XRD patterns and they are also similar to the 75 μm dunite analysis which provides more confidence in results. Points are slightly changed for 20–45 μm dunite for olivine peaks as these peaks show a slight variation. Results authenticity is excellent.

### **4.6 Validation of Malvern Mastersizer results**

Relationship between d80 (mean particle size) and Malvern mastersizer RPM for olivine (**Figure 19**). The minimum RPM required for Malvern mastersizer based on feed mean size is given below.

## **4.7 Validation of olivine yields through QXRD measurements and matched TGA-MS**

### *4.7.1 20: 45 μm olivine crushed carbonated sample QXRD*

20–45 μm olivine crushed carbonated reference sample is mixed with 20% silicon and the sample is then scanned for semiquantitative analysis for 3 hrs. This is a reference experiment in which grinding media is not used. The reaction was done at 180°C and 130 bar. **Table 9** shows QXRD results matched with TGA-MS results.

**Figure 19.** *Relationship between mean particle size and Malvern Mastersizer minimum RPM.*


**Table 9.**

*QXRD analysis and yield from QXRD compared with yield from TGA-MS.*

### **4.8 Olivine yield calculation**

Mass of MgCO3 ¼ 5*:*3% from QXRD ð Þ ¼ 0*:*053 g*:* ¼ 0*:*053*=*84 ¼ 0*:*000628 moles

MgCO3 ➔ MgO + CO2. Moles CO2 = 0.000628 moles. Mass CO2 = 0.000628 \* 44 = 0.02766. Yield = (0.02766/1) \* 100 = 2.76% ≥ (1%) from TGA-MS.

### *4.8.1 20–45 μm olivine crushed concurrent ground sample QXRD*

20–45 μm olivine crushed concurrent ground sample is mixed with 20% silicon and the sample is then scanned for semiquantitative analysis for 3 hrs. This is a concurrent grinding experiment in which grinding media is used. The reaction was done at 180°C and 130 bar. **Table 10** shows QXRD results matched with TGA-MS results.

### **4.9 Yield calculation**

Mass of MgCO3 ¼ 76% from QXRD ð Þ ¼ 0*:*76 g*:* ¼ 0*:*76*=*84 ¼ 0*:*009 moles

MgCO3 ➔ MgO + CO2. Moles CO2 = 0.009 moles. Mass CO2 = 0.009 \* 44 = 0.396. Yield = (0.396/1) \* 100 = 39.6% ≥ (34.1%) from TGA-MS, reference [14].

### *4.9.1 Validation of EDS for 20–45 μm dunite resin embedded samples*

Various particles analysis indicate the authenticity of EDS analysis (**Figures 20**–**22**). From our earlier articles, a significant difference in morphology of silica-rich layers, especially core and shell part is visible [14]. However, EDS analysis especially silicon shows no significant difference as depicted in above Figures (20–22). However,


### **Table 10.**

*QXRD analysis and yield from QXRD compared with yield from TGA-MS.*

**Figure 20.** *20–45 μm dunite sample (embedded in resin) ten particles analysis.*

**Figure 21.**

*20–45 μm dunite reference carbonated (8 h) sample (embedded in resin) eleven particles analysis and consistency of EDS analysis.*

as reported earlier, Mg/Si ratio difference [13, 14] is there to confirm the presence of silica-rich layers. This may be taken as one of the key findings of this chapter.

## **5. Conclusions and recommendations**

Suppliers may give wrong materials, but a variety of analyses will determine this. Semiquantitative XRD (QXRD) results authenticity is excellent. TGA-MS results

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

### **Figure 22.**

*20–45 μm dunite concurrent ground carbonated (8 h) sample (embedded in resin) seven particles analysis and consistency of EDS analysis.*

authenticity is excellent. No doubt left on TGA-MS and QXRD results matching. ICP-OES results match with XRF results is excellent. EDS results graphically shown are excellent. Routine calibration of measuring instruments must be performed. This very instrument to instrument. Reputed researchers will know the frequency of calibration. The key to calibration is that calibration results match with standard calibration figures/charts or numbers provided by the supplier of the instrument. I recommend contacting the supplier directly or indirectly if calibration curves results are not matching as per intended results. I recommend using pure standard materials for calibration of TGA, MS, ICP-OES, XRD, SEM, EDS, TEM, Malvern Mastersizer, ATR, TPD and other measuring instruments.

## **Acknowledgements**

Muhammad Imran Rashid acknowledges The University of Newcastle, (UoN), Newcastle, NSW, Australia for awarding a Postgraduate scholarship and enabling to use all research facilities especially from Research Division, EMX unit, University of Newcastle, Newcastle, Callaghan Campus, NSW, Australia. Mineral Carbonation International support is beyond imagination. Ms. Kitty Tang support in Malvern Master sizer analysis, Ms. Jennifer Zobec, Ms. Yun Lin and Mr. Huiming provided inevitable support in XRD, QXRD, SEM/EDS/EDX, Simulated QXRD, and TEM. Mr. Scott Molloy support in equipment installations, modifications and difficult amendments is unforgettable. Mr. Glenn Bryant support in ATR analysis and other analyses is highly appreciated. Ms. Jane Hamson support in initial trials of TGA and ICP-OES results is fundamentally acknowledged. Mr. Scott Molloy also helped with TGA-MS especially MS calibrations. His support keeps my work continuous. My advisor Dr. Geoff Brent imaged me with his industry knowledge and capabilities. Fellow students are also acknowledged. Everyone supported me from the heart. I enjoyed cultural diversity and especially food and particularly Lamb.

*Mineralogy*
