Study On Rare Earth Mineral Separation From Baotou Rare Earth Tailings

With the massive consume of mineral resource, a large amount of tailing is piled up, which not only occupies the large numbers of lands, but also damages the local ecological environment. In fact, there are still many valuable components in tailings, and separation from tailings has been attracting more and more attention around the world. Study of separation technology and process which can effectively recover the valuable resources is of great significance for ensuring the stable development of China’s economy and improving the ecological environment.In this thesis, experiments of separation rare earth minerals from Baotou rare earth tailing were carried out. The tailing mainly contains rare earth6.70%, total iron12.94%, silicon oxide11.7%, fluorine12.50%, calcium oxide30.34%, in which main useful minerals are bastnaesite, monazite, iron ore, fluorite and main gangue minerals are dolomite, calcite, beloeilite, riebeckite, barite, etc. Some tests indicate that many fine useful minerals in the tailing are difficult to be disseminated.Methods of gravity separation, electrostatic separation, magnetic separation were firstly used to concentrate rare earth minerals from the tailing. By applying high-intensity magnetic separation under the conditions that grinding fineness is100%below200mesh and magnetic field intensity is20000Oe, a concentrate could be obtained with rare earth grade8.16%, iron grade23.98%, fluoride grade6.88%. Since the rare earth and iron were concentrated while fluorine grade decreased, high-intensity magnetic separation was used as the first step to separate fluorite from the tailing.The experimental study of flotation shows that the optimum process conditions of rare earth minerals separation are that grinding fineness is98%below200mesh, pH is8, and flotation agent consists of sodium silicate (2kg/t) as inhibitor, alkyl hydroxyl oxime acid sodium (2kg/t) as collecting agent, and sodium fluosilicate (4kg/t) as activator. Under these conditions except for activator, rare earth grade and recovery can respectively reach7.898%、61.63%, while after adding the activator they become8.743%,36.60%. In addition, studies of the flotation effect of two hydroxyl oxime acids collectors provided by mineral processing plant of Baotou Steel were also performed, and the results show that using8#collector whose selectivity is stronger for rare earths and dosing step by step are beneficial to recycling rare earth. After one rough intensity magnetic separation and three flotation concentrations, the final rare earth grade in concentrate is19.87%and recovery is7.10%。Through methods of Zeta-potential measurement, contact angle measurement and FT-IR detection, the surface properties of bastnaesite in aqueous solution were investigated and the mechanisms of alkyl hydroxyl collector oxime acid on the surface of bastnaesite were also discussed.