Determination of 9 Major and Minor Elements in Beryllium Ore by ICP-OES with Acid Dissolution

Beryllium ore is one of the scarce metal minerals in China. Beryllium ore is widely used mineral resources, but it has complex components, and is always concomitant with other metallic minerals. Accurate determination of primary and secondary elements in beryllium ore is significant for its comprehensive utilization. Inductively coupled plasma-optical emission spectrometry (ICP-OES) has been used in elemental analysis of beryllium ore. However, there are some disadvantages: It is considered that beryllium concentrate is difficult to completely decompose by acid dissolution; determination of beryllium concentrate by alkali fusion has serious matrix interference; the existing research focuses on analysis of a single type of beryllium ore.

To establish a multi-element simultaneous determination method, which is suitable for various types of beryllium ore samples and has little interference with the matrix of instrumental analysis solution.

Beryl, hsianghualite and helvite samples were selected in the experiment. Digestion effect on beryllium ore under eight different acid digestion conditions were compared, such as digestion on electric heating board, high pressure sealing, microwave digestion, different kinds of acid digestion and extraction acid. The weight of the sample, the volume of the acid, the digestion time and instrument measurement were optimized. At the same time, according to beryllium ore’s mode of occurrence of elements, the best spectrum lines of each element were determined.

(1) The results show that the best mixed digested acid on electric heating board is nitric acid-hydrochloric acid-hydrofluoric acid-perchloric acid. The best extracted acid is hydrochloric acid, which is better than nitric acid or aqua regia. The high-pressure sealing method cannot completely dissolve Al, Ca and Mg elements of beryl, and the microwave method has poor effect on the digestion of Mg elements of beryl.　　(2) The digestion conditions are determined. Weigh the sample of 0.1000g into polytetrafluoroethylene crucible, moisten the sample with a small amount of deionized water, and add 2mL nitric acid-3mL hydrochloric acid-5mL hydrofluoric acid-1mL perchloric acid; cover and place the crucible on electric heating plate; decomposing at 120℃ for 2h, then 150℃ for a further 2h; remove the lid and boil away perchloric acid at 190℃; extract with 4mL 50% hydrochloric acid and add deionized water to 25mL. The solution is determined by ICP-OES. The detection limit of Be is 0.0001%, which is lower than the boundary grade of beryllium ore. The detection limit of other elements is better than the existing standard method, and the precision RSD of each major element is <5%. By verification of standard materials, the accuracy of the method meets the needs of beryllium ore determination. The analysis accuracy and precision of three real beryllium ore samples from fields is satisfying.　　(3) By optimizing the conditions of mixed acid digestion and instrument determination of the existing method, the established method can also accurately determine concentrate sample, and the matrix of the solution is simple to be determined by the instrument.

In this study, a mixed acid decomposition ICP-OES method for simultaneous determination of 9elements including Al, Be, Ca, Fe, K, Na, Mg, Li and Mn in beryllium ore has been established, which can be applied to different types and contents of beryllium ore. The established method provides necessary technical support for the research and exploration of beryllium ore.