| Acid dissolved titanium slag means Ti-containing slag which the grade of titanium dioxide is greater than70%get through reducing smelting of ilmenite in electric furnace, it is used as material of titanium dioxide by sulfuric acid method instead of ilmenite abroad with decreasing energy consumption and by-product, reducing environmental pollution, so become the main material of titanium dioxide by sulfuric acid method, at home, because of the high cost of producing acid dissolved titanium slag and the technology level drops behind, so the main raw material of producing titania pigment is ilmenite. Acid dissolved titanium slag with a relatively high grade, use to do welding electrode covering.Microwave heating technique are widely used in daily life and industrial production as renewable sources, compare with conventional heating method, the microwave heating technique has the characteristics of internal heating and selective heating, can shorten the heating time and reduce energy consumption, improve the heating efficiency. Microwave heating generate heat through molecular polarization of material in microwave field, ensure that the microwave heating has the advantages of clean and pollution-free.This paper based on acid-soluble titania slag as raw materials from a region of Yunnan, aimed at its unique structure and chemical composition, proposed a modification methods of acid-soluble titania slag in microwave field, compared With conventional heating methods, analyzed the changes of chemical composition, crystal form, microstructures, surface functional group and so on after conventional heating and microwave heating. First by X ray diffraction analyzed the material before and after heating to determine phase change, then made SEM image analysis, analyzed the change of microstructure and the internal crystal structure, analyzed crystal form and titani valence state of material using Raman, determined the variation of state and crystal form before and after heating, analyzed the change of surface functional groups by infrared spectrum analysis, defined how the surface functional groups had changed before and after heating. It is concluded that the main chemical composition of acid dissolved titanium slag are Titanium oxides, Fe、FeO、SiO2、MgO、CaO and a small amount of sulfur, phosphorus, carbon, XRD analysis indicates that the main phase is anatase that anosovite solid solution, SEM analysis find that the surface of acid-soluble titania slag with relative smooth surface is Ti, FI-IR spectrum analysis results show that the characteristic peak in466.10cm-1is caused by the vibration of octahedral coordination compound, Raman spectrum analysis show that there are the character peak of Raman vibration in151.7cm-1, in185.5cm-1is the Raman vibration character peak of Ti2O3. in626.6cm"1is the Raman vibration character peak of anatase TiO2.Put100g materials into high temperature microwave reactor which is home made, adjusted the microwave power, under different microwave power recorded the time when rises to1150*℃, obtained the elevated temperature curve and absorption property of acid-soluble titania slag in microwave field.In microwave heating experiments, placed100g materials in a microwave reactor, adjusted power, first controlled heating temperature in1050℃, holding time was respectively10min,20min,30min,40min,50min, and then controlled heat preservation time for60min, heating temperature was respectively850℃,900℃,950℃,1000℃,1050℃, got the influence of temperature and holding time.This paper under the condition of microwave heating studied mainly the influence of heating temperature and holding time on the content of sulfur, phosphorus, and carbon rutile, the content of phosphorus is less, so this article needn’t dephosphorization. Through the study find that with the increase of heating temperature and holding time, the content of sulfur and carbon decrease, the content of rutile increase, along with the transition of the crystal shape in heating process, holding time is short in comparison with conventional heating methods at the same temperature. XRD analysis find that diffraction peak of anatase TiO2and anosovite (M3O5) weaken gradually, the XRD diffraction peak of rutile enhance. Raman spectral analysis find that vibration characteristic spectrum of low valent titanium and anatase become less until disappear, The characteristic peak of rutile increases, show that after treatment in microwave field low titanium low titanium is oxidized, realize transformation of basic implementation,.FI-IR spectral analysis find that existing vibration peak TiO2octahedral is caused by octahedral vibration, with the increase of temperature and the extension of time, the characteristic peak move to the high frequency, have a blue-shift, caused by the crystal transformation. SEM analysis find that the surface produces a lot of crack, separate out a large number of acicular crystals, with the increase of magnification, crystal structure grow coarsening, and the sample surface have a large number of pores, the reason is that internal sulphur and carbon release in the form of gaseous oxide, cracks can improve the surface activity of sample, the removal of sulfur and carbon.The validation test was implemented for microwave heating condition, used Design Expert8.0, adopted central composite design(three factors five levels), designed20experiments, the determination coefficient of model is0.9853, correction factor is0.9721, close to1, show that the model can explain the change of the response value, only a handful of mutations can’t be explained by this model, the P value is less than0.0001, the model is significant, so the model can be used to analyze and predict the experiment, experiment of model design has carried on the analysis of variance, find that the model can well reflect the relationship between independent variables and dependent variable, at the same time get the best process parameters:1000,40min,2.25kw, obtain good results. |
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