Study on Effect of Grinding Fineness on Phase Transformation Rate and Mechanical Strength of Phosphogypsum
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摘要:
采用磷石膏制备建筑石膏是规模化消纳磷石膏的重要途径。本文研究了粉磨细度对磷石膏制备建筑石膏物相转化速率及硬化体力学强度与结构的影响。研究结果表明：提高煅烧温度有利于加快磷石膏脱水，合适的煅烧温度为120℃。随着粉磨细度的增加，磷石膏转化为建筑石膏的速率先增加后降低，所制备建筑石膏的抗折强度和抗压强度先增大后降低；未经粉磨的磷石膏制备的建筑石膏硬化体结构松散、孔洞较多、粉化严重，抗折强度和抗压强度仅分别为0.24 MPa和0.57 MPa；当磷石膏平均粒径减小到49.95 μm时，磷石膏脱水速率加快，水化生成的二水石膏晶体粒度均匀，硬化体结构致密、孔洞较少，抗折强度和抗压强度分别提高至1.02 MPa和2.62 MPa。因此，通过粉磨改性不仅有利于提高磷石膏的脱水速率，还能有效改善石膏硬化体的结构，提高建筑石膏的力学强度。
Abstract:Preparation of calcined phosphogypsum (CPG) is an important utilization way for phosphogypsum (PG) on a large scale. In this paper, the effects of grinding fineness on the phase transformation rate, mechanical strength and structure of hardened body of the CPG were studied. The results show that increasing calcination temperature is beneficial to accelerating the dehydration of PG, the appropriate calcination temperature is 120℃. With the increase of grinding fineness, the conversion rate of PG into CPG first increases and then decreases; the flexural strength and compressive strength of the prepared CPG first increase and then decrease; the hardened body of the CPG prepared from non-grinding PG has loose structure, many holes and serious pulverization, and the flexural strength and compressive strength are only 0.24 MPa and 0.57 MPa, respectively. When the average particle size of PG is reduced to 49.95 μm, the dehydration rate is accelerated, the crystal size of dihydrate gypsum is uniform, the hardened structure is dense, and the pores are less, the flexural strength and compressive strength are increased to 1.02 MPa and 2.62 MPa, respectively. Therefore, grinding modification is not only beneficial to increasing the dehydration rate of PG, but also to effectively improving the structure of hardened gypsum and increasing the mechanical strength of CPG.
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