红外拟合光谱分析微波对重晶石浮选的影响机理

目前浮选提高重晶石品位的方法通常采用新型浮选药剂从低品位重晶石矿中进行分选，采用微波加热预处理矿物可提高浮选回收率，但微波对浮选药剂与矿物的作用机理还不清楚。微波加热技术近年来用于矿物加工、冶金与材料制备等领域，具有反应速度快、产品指标高等优点。以油酸钠为捕收剂，对微波预处理后的重晶石纯矿物进行浮选，并对不同微波作用时间下的重晶石浮选样品进行红外光谱检测，通过红外拟合平滑光谱和二阶导数光谱计算分析，研究微波对重晶石浮选的影响机理。浮选试验结果表明，未经微波预处理的重晶石，在油酸钠用量为55 mg·L-1、pH值为8.0的条件下，浮选指标最佳，回收率为91.41%；而对比之下，经微波作用后的重晶石进行浮选，随着微波处理时间的增加浮选指标逐渐提高，且在微波作用60s时的回收率最高，达95.27%。基于浮选试验的红外光谱分析表明，重晶石未经微波预处理进行浮选，与油酸钠作用，在波数为3 004 cm-1处-CH₂-的对称伸缩振动峰、2 953 cm-1处-CH₃的反对称伸缩振动峰、1 119和1 077 cm-1处SO2-₄的非对称伸缩振动峰均发生了红移，说明油酸钠在重晶石表面发生化学吸附；而经微波预处理后的重晶石浮选时，在波数为2 853 cm-1处-CH₂-对称伸缩振动峰、2 923 cm-1处-CH₂-反对称伸缩振动峰、2 958 cm-1处-CH₃反对称伸缩振动峰、1 181，1 122和1 086 cm-1处SO2-₄非对称伸缩振动峰、982 cm-1处SO2-₄对称伸缩振动峰、635和610 cm-1处SO2-₄弯曲振动峰，其峰位并未发生红移，但峰强随着微波作用时间的增加明显加强，且微波作用60 s时其峰强增加最明显；对微波处理后的红外光谱进行拟合平滑光谱和二阶导数光谱计算发现，在波数为2 958，2 923，2 853，1 181，1 122，1 086，982，635和610 cm-1处峰面积均有不同程度的增加，且在微波作用60s时峰面积分别增加了1.84%，259.12%，761.15%，235.72%，145.61%，198.50%，641.16%，549.67%和744.97%，表明微波预处理并未诱发重晶石表面发生化学反应，但强化了捕收剂油酸钠与重晶石矿之间的化学吸附，使其与重晶石表面的化学吸附更加致密，吸附量增加，因此重晶石回收率增加，浮选指标提高。

Influence Mechanism of Microwave on Barite Flotation Based on Infrared Fitting Spectrum Analysis

At present, methods of separating from low-grade barite ore are usually adopted to improve the grade of barite in flotation by using new flotation reagents, and the recovery of flotation can be improved by microwave pretreatment of the mineral before flotation, but the mechanism of microwave on flotation reagents and minerals are not yet known. In recent years, microwave heating technology has been used in mineral processing, metallurgy and material preparation and so on, with the advantage of fast reaction speed and high product index. In this paper, sodium oleate was used as a collector in the flotation tests of the pure barite mineral after microwave pretreatment, and the infrared spectrum detection was carried out for the barite flotation samples under different microwave heating times. The effect mechanism of microwave on barite flotation was discussed by the infrared spectral analysis of fitting smooth spectrum and second derivative spectrum. The flotation test results showed that the barite without microwave pretreatment had the best flotation index and recovery of 91.41% under the conditions of sodium oleate dosage of 55 mg·L-1 and pH value of 8.0. In contrast, the flotation index of barite treated with microwave increased gradually with the increase of microwave treatment time, and the recovery rate of barite treated with microwave in the 60 s was the highest, reaching 95.27%. Infrared spectrum analysis based on flotation test showed that in the flotation of barite without microwave pretreatment interacted with sodium oleate, the red shift of -CH₂- symmetric stretching vibration peak at wavenumber 3 004 cm-1, -CH₃ antisymmetric stretching vibration peak at wavenumber 2 953 cm-1, SO2₄ asymmetric stretching vibration peak at wavenumber 1 119 and 1 077 cm-1 were all found, indicating chemical adsorption of sodium oleate on the surface of barite was happened; By contrast, in the flotation of barite after microwave pretreatment interacted with sodium oleate, the red shift of -CH₂- symmetric stretching vibration peak at wavenumber 2 853 cm-1, -CH₂- symmetric stretching vibration peak at wavenumber 2 923 cm-1, -CH₃ antisymmetric stretching vibration peak at wavenumber 2 958 cm-1, SO2-₄ asymmetric stretching vibration peak at wavenumber 1 181，1 122 and 1 086 cm-1, SO2-₄ symmetric stretching vibration peak at wavenumber 982 cm-1, SO2-₄ bending vibration peak at wavenumber 635 and 610 cm-1 were not found, but the peak strength increased significantly with the microwave heating time, and the peak strength increased most significantly with the microwave heating time of 60 s. The fitting smoothing spectrum and the second derivative spectrum calculations of the infrared spectrum after microwave pretreatment showed that the peak area at wavenumber 2 958，2 923，2 853，1 181，1 122，1 086，982，635 and 610 cm-1 increased to different degrees, and under microwave heating 60 s, the peak area respectively increased by 1.84%, 259.12%, 761.15%, 235.72%, 145.61%, 198.50%, 641.16%, 549.67% and 744.97%. It indicates that microwave pretreatment does not induce a chemical reaction on the barite surface, but strengthens the chemical adsorption between sodium oleate collector and barite ore, make the chemical adsorption on the barite surface denser, and the adsorption quantity increased, so the barite recovery increases and the flotation index improves.