白云石掺杂制备高强度压裂支撑剂及其机理探讨

Effects of dolomite additive on bauxite-based fracturing proppant:phase composition,microstructure,performance

以氧化铝(Al2O3)含量67%(质量分数)的铝矾土为主要原料,白云石为烧结助剂制备了高强度压裂支撑剂;并通过烧结制度优化、物相分析与微结构表征,初步探讨了支撑剂强度提升机理。研究表明,白云石可以促进煅烧过程中液相的生成,从而起到以下作用:(1)降低制品烧成温度;(2)促进棒状莫来石晶相的发育;(3)填充孔隙,强化晶粒间的粘结作用。对比实验发现,液相对晶粒的粘结作用以及交错棒状莫来石结构是样品机械性能提升的主要原因。当白云石添加量为3%(质量分数)时,样品性能最佳,在1290～1400℃温度范围内处理的样品破碎率<6%;1350℃煅烧样品破碎率降至2.9%,样品体积密度为1.75g/cm3,视密度为3.12g/cm3。

High-strength fracturing proppant was prepared J from bauxite （67wt AI（）3） and dolomite. The mi- cro-mechanism related with the strength improvement was addressed with systematic sintering experiments as well as phase composition/microstructure characterization. The results indicate that the addition of dolomite promotes the formation of liquid phase during sintering process. Liquid phase of samples plays three rules dur ing sintering process： （1） depressing the sintering temperature; （2） facilitating the growth of rod-like mullite; （3） filling pores/bonding particles. Analyses suggest that the mechanical strength enhancement was introduced by the appearance of the interlocked rod-like mullite and the cross linkage of particles by the liquid phase. The best performance of our proppant was achieved by 3wt//0 dolomite addition; the proppant exhibits a breakage ratio of less than 6 （69MPa） with a 1290 1400C sintering process, and this breakage ratio was depressed down to 2.9 with a sintering temperature of 1350 C. The bulk density and apparent density of the 1350（2 sintered proppant are 1.75 and 3.12g/cma , respectively.