| The cylindrical ceramsite proppant material was prepared with thesecondary bauxite and pyrolusite as main raw materials, and magnesium slag asauxiliary material. At first, the properties(i.e., chemical components, particlesize distribution and particle morphology) of three raw materials wereinvestigated, and the effects of magnesia slag-doping and sintering temperatureon the property of ceramsite proppant material were analyzed. In theseexperiments, the mechanisms of fracture and sintering were revealed. Then, thispaper used the secondary bauxite, pyrolusite and magnesium slag as rawmaterials, amylocellulose as binder to prepare ceramsite proppant. The prillingand sintering of ceramsite proppant were studied, at the same time, its properties(i.e., crushing rate and acid solubility) were tested. It has outstandingperformance compared with the others in the market. The main contents andresults are as follows:(1) By chemical components and phase composition analysis, particle sizedistribution, and particle morphology, the properties of three raw materials wereinvestigated, it was thought that the main chemical components of magnesiumslag were CaO(66.58wt%) and SiO2(22.79wt%), and its main phase was γ-C2S（2CaO·SiO2）,while the main chemical components of bauxite and pyrolusitewere Al2O3(65.6wt%) and MnO2(56.82wt%), in addition, there were someimpurities(Fe2O3) in all three raw materials; the bauxite and pyrolusite used inexperiments were improved by grinding in factory, they had accordant mediandiameters(11.15μm,11.86μm), while median diameter of magnesium slag was6.436μm. Particle morphology were irregular lumps, which would become flakyby ball-milling with the phenomenon of secondary aggregates happening.(2) Through the single-factor experiment, contrast to X-ray diffraction,scanning electron microscope(SEM) and energy dispersive spectrometer(EDS),the effects of magnesia slag-doping and sintering temperature on the property ofceramsite proppant material were studied according to bulk density, apparentporosity, linear shrinkage rate and compressive strength as investigation indexes. The results showed that the bulk density decreased after increasing first andcompressive strength increased with increasing the amount of magnesiumslag-doping. The sample added magnesium slag of2wt%and sintered at1350℃for3h had bulk density of3.04g·cm-3, apparent porosity of less than1%,compressive strength of180MPa, the phase of the multiphase ceramic includedcorundum, mullite and anorthite. With the sintering temperature increasing, thephase composition essentially unchanged, while samples were deformed at1450℃. The suitable sintering temperature range of themultiphase ceramic is1350℃-1400℃.(3) The scanning electron microscope(SEM) photos showed the distributionand trends of cracks, and the size of pores and grains. It was thought that mullitegrains growed in different directions and were intertwined with corundum grainsfilled in them while they were both wrapped in glass phase, so the material itselfwas very dense; mullite grains played a similar role like whisker in improvingthe compressive strength of the material when the material was pressed. Whenthe material was sintered at high temperature, liquid made mass transfer rate fast,and were conducive to exclude pores, so that the material was more dense.(4) The prilling process of ceramsite proppant was studied in a Eirichintensive mixer and small disc pelletizer, at the same time, the sintering processof it was studied in a box furnace and rotary kiln. The ceramsite proppant hadoutstanding performance compared with the others in the market. It was thoughtthat efficiency and strenghth of green pellets produced in the Eirich intensivemixer was superior to that of small disc pelletizer, but they had worse sphericity,difficult to control; sintering in the rotary kiln was superior to that in the boxfurnace. The ceramsite proppant produced in lab compared with the others in themarket had a higher crush resistance but a higher acid solubility(7.12%). |
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