It has been proved that crystal growth modifier (CGM) can improve particle size distribution (PSD) and the alumina production. However, few researches were reported on whether CGM has an effect on the structure of sodium aluminate liquors. In order to provide fundamental guidance to the application of CGM to seed precipitation, the effect of CGM on the structure of synthesized sodium aluminate liquors was studied. It is shown that there is no new characteristic peak and obvious shift in the Raman spectrum of the liquors after adding a certain amount of CGM. By constructing a comparison function and using calculation function of the software of Raman spectrometer, it is found that CGM might have micro effect on the structure of sodium aluminate liquors via changing the concentration of principal ion Al(OH)(4)(-) in the liquors.

Raman spectroscope is a useful instrument to character the structure of sodium aluminate liquors. As the spectrum of sodium aluminate liquors is not very strong, some environmental factors may affect the spectrum and hinder us from attaining good results. Effect of environmental light on the Raman spectrum of sodium aluminate liquors was investigated. It is concluded that sunlight affects the spectrum of sodium aluminate liquors the most and almost masks it. For the light of fluorescence, it shows strong signal of light in the spectrum. But for the light of desk lamp and display screen, they have a little effect on the spectrum. To attain a good Raman spectrum of sodium aluminate liquors, the optimum operation condition is in a darkroom, or only let screen lamp on if necessary.

Quantitative analysis on oscillation curves of PSD was carried on by applying software called 1stOpt. The results show that all oscillation curves can be expressed as a function. Considering the fitting effect of curves and the complexity of fitting functions comprehensively, a function was adopted to fit typical oscillation curves of particle size distribution(PSD). The correlation coefficients of fitting are all lager than 0.99, and the fitting function is also suitable for PSD curves of most particles. The results can provide a mathematic model for a simulation of PSD of aluminum hydroxide in the seeded precipitation process, and they are also helpful to broadcast and control the PSD of aluminum hydroxide for alumina refinery.