钼酸铵生产流程中含钾矿物的释钾机理研究

Potassium release mechanism of potassium-bearing minerals in ammonium molybdate production process

钾在钼酸铵及后续钼产品中作为一种有害元素,通常希望其含量越低越好。本工作通过模拟不同实验条件对水洗降钾的影响,用ICP、分光光度计及SEM-EDS等传统物相检测方法对钼酸铵生产流程中各阶段矿物进行定性分析,并结合先进的自动矿物参数分析系统(MLA)进行定量分析,得出提高水洗温度、细磨钼焙砂和添加Na2CO3可提高水洗降钾效果。实验数据和热力学分析结果进一步表明,在钼精矿焙烧过程中云母会生成正长石和钡铁云母,在此基础上进一步分析了不同含钾矿物的释钾行为,得出4种含钾矿物进入钼酸铵产品的难易程度为:正长石>云母>钡铁云母>伊利石。研究结果对低钾钼产品的生产及其应用具有重要意义。

Potassium is a harmful element in ammonium molybdate and subsequent molybdenum products,and its content is usually desired to be as low as possible.Through exploring the effects of changing cooling mode,roasting temperature,mineral particle size,washing temperature,and adding Na2CO3 on washing potassium reduction,qualitative analysis of minerals in different stages of ammonium molybdate production process was carried out by ICP,spectrophotometer,and SEM-EDS while quantitative analysis was carried out by advanced MLA technology.The results showed that rapid cooling,increasing the temperature of water washing,fine grinding molybdenum calcine,and adding Na_(2)CO_(3) can improve the effect of potassium reduction in water washing.However,increasing the roasting temperature was not conducive to the release of potassium in water in molybdenum calcine,and changing the particle size of molybdenum concentrate had no significant effect on potassium reduction in water washing.Because the potassium content in molybdenum concentrate was very low,the traditional phase detection method had some errors.Through MLA detection,it could be found that there are four potassium-bearing minerals in the ammonium molybdate production process,namely muscovite,orthoclase,anandite,and illite.The potassium releasing behavior of potassium-bearing minerals was analyzed and the difficulty of four potassium-bearing minerals entering ammonium molybdate products was as follows:orthoclase>muscovite>anandite>illite.The results of MLA analysis showed that the muscovite can decompose into orthoclase and anandite during the roasting process of molybdenum concentrate.The initial reaction temperature of decomposing mica into orthoclase was 727 K.As the most harmful mineral in the process of ammonia leaching potassium mineral,orthoclase was not only from the raw material of molybdenum concentrate but also produced in the process of high-temperature roasting.The transformed muscovite decomposed extremely easy and thus greatly improved the proportion of orthoclase in the subsequent washing and ammonia leaching process,which was extremely difficult to remove and hence the formed orthoclase was relatively easy to enter into the ammonia immersion compromised product quality.The research results are of great significance for the production and application of low potassium molybdenum products.