# Process Mineralogy of Micro/Nano Silicon-Carbon Ore Obtained from Jiangxi, China
## 3 Results
### Ore Morphology  
As shown in Figure 4a, SEM-EDS revealed many cracks and holes as well as circular pits and marks on the ore surface. These may have been caused by biodeterioration. As shown in Figure 4b, unevenly shaped micron-scale quartz pieces, nanoparticles, and nano-needles were found on the ore's surface. A small amount of nanoscale needle-like quartz crystals were also observed on the surface of the ore (Figure 4c). Figure 4d shows the elemental distribution of the ore surface over the marked area A, as determined by EDS analysis. The main elements in this ore were identified as C (42.51 wt%), O, and Si. Combined with the thermal analysis and XRD results, the mass percentage of carbon obtained by EDS was much higher than 10.77%. This means that carbon was mainly enriched on the surface of the mineral or in some special structures instead of being uniformly distributed throughout the mineral structure. A small amount of aluminum (4.64%) was also detected. This mainly came from aluminum silicates.  
Figure 3: (a) DSC-TG curves and (b) FTIR spectra of the ore sample.  
The morphology of the carbon-free sample is shown in Figure 5a. After chemical treatment with NaClO, there were still some holes, cracks, and nano-sized quartz particles. However, no needle-like structures were found on the surface of the sample. To verify the carbon removal effect of NaClO, EDS analysis was performed on area B. As shown in Figure 5b, the main elements in the particle were O, Si, and Al, with O having the highest mass fraction (60.64%). Most of the carbon in the mineral was removed without damaging the basic structure of the quartz. This method was helpful for eliminating interference from fixed carbon and analyzing the original quartz morphology. It was also helpful for the purification of quartz at 60 \({}^{\circ}\)C.  
The morphology of the quartz removal sample is shown in Figure 6a-c. Comparing Figure 6a with Figure 4b reveals that needle-like structures and holes remained in the sample after chemical treatment with NaOH. This means that the main element of this needle was carbon. Furthermore, Figure 6b,c show that the quartz in the sample was corroded by NaOH, resulting in large numbers of holes and depressions on the surface. Hollow, thin-walled structures were also found. EDS analysis of the elemental content  
Figure 4: (**a–c**) SEM images of one sample and (**d**) EDS elemental spectrum of area A.  
Figure 5: (**a**) SEM image of the carbon-free sample and (**b**) EDS pattern of area B.  
of area C (Figure 6d) shows that carbon was the most common element on the surface of the sample (70.48 wt%). This means that the observed nano needle-like structures were encapsulated by fixed carbon, which prevented them from being corroded by NaOH. Silicon only comprised 2.30% of the mass fraction, indicating that NaOH had a good removal effect on silica. The sample was also found to contain small amounts of Na, K, and Al. Comparing these results with the elemental composition data presented in Table 1 reveals that Na and K represent impurities remaining in the mineral structure after chemical treatment with NaOH; aluminum originated from the original ore sample. The Al content increased significantly with decreasing Si content. These results show that NaOH was able to remove most of the silicon. Although some impurities remained (in the form of ions), this method still helped reveal the morphology of fixed carbon within the ore.