磷矿硫酸预处理过程的微孔化研究

Study on micro-pores of phosphate rock in sulfuric acid pretreatment process

以硫酸法预处理四川马边磷矿为研究对象,采用扫描电镜、能谱分析、比表面积分析等手段研究了磷矿预处理前后颗粒表面的变化。结果表明:处理前磷矿表面镁元素呈均匀分布,而处理后磷矿表面出现明显的孔洞,孔洞可能为白云石分解所致,并且腐蚀后磷矿由许多高度连通性的微小磷矿颗粒组成,在磷矿表面并无镁元素的存在。孔洞的存在增大了磷矿的比表面积和孔容,同时提高了磷矿的分解率和萃取磷酸料浆的过滤性能。在此微观分析的基础上,建立了硫酸预处理磷矿的磷溶出及镁脱除的数学模型。

Mabian phosphate rock from Sichuan Province was selected as the standard samples and pretreated by sulphric acid. Surface change of phosphate rock particles was studied by scanning electronic microscopy （ SEM ） , energy-disper- sive X - ray spectrometer （ EDX ）, and specific surface area （ SSA ）. Results showed that the magnesium element was even distributed on the surface of untreated phosphate rock ; there were obviously many pores on the surface of pretreated phos-phate rock and the pores may be caused by the decomposition of dolomite and the pretreated phosphate rock was made up of many small inter-connective grains, and magnesium element was not found on the surface of pretreated phosphate rock. Existence of these micropores led to the increase of specific surface area and average pore volume of phosphate rock, and this change would help the increase of decompositon rate of phosphate rock and the filtration improvement of final phosphate slurry. Based on the microcomsic analysis, mathematical models for magnesium removal and phosphorus loss from phosphate rock were set up.