Daim ntawv thov: Lub nplhaib tiaj tus siab gradient sib nqus sib nqus yog dav siv hauv cov ntub dej hematite, limonite, siderite, chromite, ilmenite, wolframite, tantalum thiab niobium ore thiab lwm yam tsis muaj zog hlau nplaum, thiab cov khoom tsis yog xim hlau, xws li quartz, feldspar rau tshem tawm impurity hlau thiab purification. .