分光光度法测定磷石膏钙渣中硫酸根含量

钙渣中含有杂质硫酸根，其含量给磷石膏钙渣制备轻质碳酸钙工艺中除杂过程带来负担，同时是影响轻质碳酸钙产品质量的一个重要指标。用铬酸钡分光光度法测定磷石膏钙渣中的硫酸根，建立了一个简单、快速、选择性较好的钙渣中硫酸根的测定方法。在410 nm波长处，硫酸根为0.00～6.00 mg/mL时与铬酸根吸光度呈线性关系，线性回归方程为y=0.168 4x+0.003 2，r=0.999 9，相对标准偏差优于10%，加标回收率在96%～102%。该法可用于测定钙渣中硫酸根含量，操作简单，可行性强，可以满足测定要求并应用于实时监控。

Spectrophotometric determination of sulfate radicals in calcium slag of phosphogypsum

Sulfate radical is contained in calcium slag,which is an important index influencing the quality of precipitated calcium carbonate(PCC) and it will increase the load to the impurity removing process during manufacturing PCC.Barium chromate spectrophotometry was adopted to determine sulfate radicals in calcium slag of phosphogypsum and a simple and rapid determination method with good selectivity has been established.At wavelenth of 410 nm,when the mass concentration of sulfate radicals is at 0.00～6.00 mg/mL and it has a linear relation with chromate radicals.Linear recession equation and the correlation coefficient are y=0.168 4x+0.003 2 and r=0.999 9 respectively.Relative standard deviation is less than 10%,and the standard sample recovery rates are at 96%～102%.This method is applied to the determination of sulfate radicals in calcium slag and has advantages of simplicity and strong feasibility,which can satisfy the determination requirements and can be used for real time monitor.