中文摘要：

采用X射线粉末衍射仪、热重分析仪、透射电子显微镜、比表面积分析仪等研究空气中热处理铜陵新桥天然针铁矿的结构演化。热分析结果表明：针铁矿在154．5℃开始脱羟基向赤铁矿转变，在300℃时相转变完全。煅烧温度250-700℃之间，虽然产物都是赤铁矿，但都保持针铁矿原有的形貌特征，且产物的比表面积和孔结构随煅烧温度变化有明显差异。300℃煅烧产物由于脱羟基水，针铁矿假象颗粒内部出现1～5μm大小的孔，且具有最大的比表面积（107．8m^2／g）；随着煅烧温度升高，由于赤铁矿晶体生长变大，赤铁矿晶体间空隙变大，比表面积逐步降低；煅烧温度大于700℃时，由于赤铁矿晶粒生长开始出现颗粒间烧结现象，针铁矿假象颗粒内部和外部空隙进一步减少，当煅烧温度达到900℃时，针状形貌变成粗短圆柱状，此时比表面积降至最小值为4．8m＆2／g。结果表明：铜陵新桥针铁矿可以在300-400℃空气中煅烧获得高比表面积的纳米孔材料，在环境保护领域具有很大的潜在应用价值。

英文摘要：

A natural goethite from Xinqiao, Tongling was calcined under air atmosphere, and the structure after calcination was characterized by X-ray powder diffraction, transmission electron microcopy and nitrogen adsorption-desorption analysis for specific surface area and pore size distribution, respectively. The results show that the dehydroxylation of goethite occurs to form hematite at 154.5 ℃, while the phase transition completes at 300 ℃. Although the products are hematite and maintain the original morphology of goethite in the calcination temperature range of 250-700 ℃, the specific surface area and pore structure vary with temperature. The pores in the dimension of 1-5 nm appear in the particles of annealed goethite. This is ascribed to the dehydration of goethite at 300℃, and the maximum specific surface area is 107.8 m2/g. The hematite crystal grows up with the increase of calcination temperature, leading to the larger voids among hematite crystal and the decreased specific surface area. The internal and external voids among illusional goethite particles reduce further due to the sintering among hematite particles. The needle-like morphology of goethite changes into the stubby cylindrical at 900 ℃, and the specific surface area reduces to 4.8 m2/g. It is indicated that the nanoporous material with the great specific surface area could be obtained via the calcination of natural goethite from Xinqiao under air atmos- phere in the range of 300--400℃ This mineral has a great potential application in the field of environmental protection.