颗粒度对鞍山式铁矿反射光谱特征的影响研究

Effect of Particle Size on Reflectance Spectra of Anshan Iron Ore

岩矿反射光谱的决定因素是其成分及含量,变异因素主要为颗粒度、粗糙度、观测角度、表面形态等。为明确颗粒度与鞍山式铁矿反射光谱之间的关系,采用SVC HR-1024便携式地物光谱仪对鞍山式铁矿的两种主要铁矿石(赤铁矿、磁铁矿)进行不同颗粒度下的可见光-近红外光谱测试,分析颗粒度对赤铁矿、磁铁矿反射光谱的影响规律,并明确颗粒度的敏感波段与稳定波段,为以后的定量反演工作提供参考。结果表明,颗粒度对赤铁矿、磁铁矿反射光谱的影响规律具有显著差异。当赤铁矿试样粒径由0.03 mm增加到1 mm时,光谱反射率随颗粒度增加而逐渐减小,二者呈现显著负相关关系。但是在不同的波段处,赤铁矿反射光谱受颗粒度的影响程度不同,在350~550 nm波段,反射光谱受颗粒度影响非常微弱,为赤铁矿反射光谱对颗粒度的稳定波段;在550~950 nm波段,反射光谱受颗粒度影响较微弱;在950~1250 nm波段,反射光谱受颗粒度影响较显著;在1250~2500 nm波段,反射光谱受颗粒度影响非常显著,为赤铁矿反射光谱对颗粒度的敏感波段。当赤铁矿试样粒径大于1 mm之后,赤铁矿反射光谱多重叠,受颗粒度影响显著减弱,且二者无明显相关性。当磁铁矿试样粒径由0.03 mm增加到4 mm时,磁铁矿反射光谱对颗粒度的响应非常微弱,颗粒度引起的光谱反射率变化不超过3%,且颗粒度与磁铁矿反射光谱间无相关性,二者间联系微弱。该研究揭示了颗粒度对鞍山式铁矿反射光谱的影响规律,定量分析了颗粒度对赤铁矿、磁铁矿反射光谱的影响程度,并确定了颗粒度与试样反射率符合的函数分布关系,为提高鞍山式铁矿的品位反演精度奠定了良好基础。

Generally,the influence factors of the reflectance spectrum of rocks and minerals can be divided into the decisive factors related to composition and content,and the variant factors,including the particle size,roughness,observation angle and surface morphology.The study is focused on the relationship between the reflectance spectrum and the particle size of Anshan iron ore.Firstly,the reflectance spectra of the two main iron ores(hematite ore and magnetite ore)with different particle sizes are obtained by SVC HR-1024.Then,the influence of particle size on the reflectance spectra of both hematite and magnetite is analyzed.The sensitive waveband and stable waveband of the reflectance spectra related to particle size are extracted.The study indicates the following results.Firstly,the effects of particle size on the reflectance spectra of hematite and magnetite are different.For the hematite,the reflectance decreases with the particle size increase when the particle size is in the range of 0.03 to 1 mm.The effects are different in different waveband for the reflectance spectra of hematite.In the wave range of 350~550 nm,the particle size’s effect can be,neglected and this waveband can be regarded as the stable waveband.The influence is weak in the range of 550~950 nm and become obvious in the 950~1250 nm range.In the range of 1250~2500 nm,the reflectance changes obviously with the particle size.Therefore,this waveband can be regarded as a sensitive waveband.However,when the particle size of the hematite is larger than 1 mm,the particle size’s effect decreased obviously without correlation.For the magnetite,the reflectance changes weakly with an amplitude of less than 3%when the particle size is in the range of 0.03 to 4 mm.There is no correlation between the reflectance and the particle size.This study revealed the quantitative relationship between the reflectance spectrum and the particle size for Anshan iron ore.The results can provide the foundation for improving the inversion accuracy of the ore grading for the Anshan iron.