将这段话翻译成学术英语论文以平煤神马焦煤中煤为研究对象中煤的灰分为3410粒度较细中间密度级含量较高有解离再选的潜力原中煤粗粒级物料直接分选可选性为极难选；XRD分析表明中煤主要的矿物质是石英中煤与水的接触角为824°。

This paper focuses on the study of Pingmei, Shenhua, Jiaomei, and Zhongmei coal, with a specific focus on Zhongmei coal. The ash content of Zhongmei coal is 34.10%, and the particle size is fine. The intermediate density fraction contains a high proportion of the material, which has the potential for disassociation and reselection. Direct separation of coarse-grained Zhongmei material is extremely difficult. XRD analysis shows that the main mineral in Zhongmei coal is quartz, and the contact angle between Zhongmei coal and water is 82.4°.