Abstract: Salt lake resources are rich in China, and the Qarham salt lake in Qinghai Province is the largest potash fertilizer manufacturing base. However, a large amount of byproduct bischofite (MgCl₂·6H₂O) of the potassium fertilizer industry cannot be utilized effectively and are discarded back into the salt lakes. This has become the primary problem after extraction of potassium from salt lake. This paper presents a thermal plasma process for pyrolysis of bischofite. Thermal plasma was used as an ultra-high heat source to intensify the pyrolysis process. At the same time, the high temperature pyrolysis products were deposited to obtain high value-added MgO film. The deposition efficiency of MgO film was high, up to 3.2 mm·min^-1. The particle size on the film was between 10 and 60 nm, and the MgO film exhibited a strong ultraviolet-green photoluminescence emission under the excitation of 325 nm He-Ne laser. The thermal plasma technique is simple and suitable for large-scale continuous process.

Key words: bischofite, film, deposition, pyrolysis, thermal plasma

摘要： 我国盐湖资源丰富，其中位于青海的察尔汗盐湖是我国最大的钾肥生产基地。然而在钾肥生产过程中副产的大量水氯镁石（MgCl₂·6H₂O）目前尚得不到有效的利用，“镁害”已经成为盐湖卤水提钾后的首要问题。本文提出以高频热等离子体为高温热源，强化水氯镁石的热解过程，同时将热解产物沉积得到高附加值的MgO薄膜。研究结果表明，该工艺热解效率高，热解得到高纯的MgO薄膜，沉积效率可达到3.2 mm·min^-1，薄膜颗粒粒径处于10～60 nm之间，具有良好的光致发光性能；同时沉积工艺过程简单，适合大规模连续化生产。

关键词: 水氯镁石, 薄膜, 沉积, 热解, 热等离子体