Mineralogy and potential recovery of rutile (TiO~2) as a by-product in porphyry copper deposits

摘要

Rutile is a common accessory phase in altered porphyry copper ores (up to 1 wt. percent of the host rock), yet it is generally lost to tailings, despite its relatively high price. Ti metal (sponge) is about 5 times the price of Cu, and high-grade rutile concentrate for pigment is comparable in price to copper-sulphide concentrate. This pilot study assesses the feasibility of rutile recovery from ores going through the mill of large mining operations. As a first step, ores and heavy mineral concentrates from Chuquicamata, Chile were analyzed using microscopy, electron probe microanalysis, and various mineral separation techniques. Rutile commonly forms by alteration of sphene (titanite), titanomagnetite, or biotite. In the potassic alteration zone of Chuquicamata, rutile occurs as individual grains surrounding biotite or pseudomorphing sphene, in habits that could lead to easy liberation. In the quartz-sericite alteration zone rutile is intergrown with pyrite, thus decreasing the likelihood of effective separation.