Limonite is now considered as an important iron ore resource in China due to the rapidly depleting magnetite and haematite reserves. The separation of limonite from calcite by flotation is a problem to be solved, and it was investigated systematically in this paper. Flotation tests show that the recoveries of limonite and calcite are close to 95% within the pH range of 7.5–10.0 using 3 × 10−4 mol/L sodium oleate as collector. However, the flotation of limonite was depressed by calcium ions generated from the dissolution of calcite in the flotation of a mixture of limonite and calcite. The effects of depression on limonite can be enhanced by adding sodium pyrophosphate. Hence, the separation of calcite from limonite can be finished by reverse flotation. Under the test condition, the limonite–calcite mixture with Fe grade of 28.45% was upgraded to a concentrate with 50.5% Fe and 91.50% Fe recovery.
BaryshnikovFA, PopovIV, FedosovaVY.1965. The electrochemical potential, adsorption and floatability of limonite as a function of solution pH. J Min Sci. 1 (2):159–160.
2.
DemirelH, EkmekciZ.1991. Concentration of hematite–limonitic iron ores by high intensity permanent magnetic separator. SME Annual Meeting, Denver, USA; Feb 25–28; Society of Mining Engineers of AIME.
3.
DreybrodtW, EisennlohrL, MadryB, RingerS.1997. Precipitation kinetics of calcite in the system CaCO3–H2O–CO2: the conversion to CO2 by the slow process H+ + HCO3−→CO2 + H2O as a rate limiting step. Geochim Cosmochim Acta. 61(18):3897–3904. doi: 10.1016/S0016-7037(97)00201-9
4.
FlukigerF, BernardD.2009. A new numerical model for pore scale dissolution of calcite due to CO2 saturated water flow in 3D realistic geometry: principles and first results. Chem Geol. 265:171–180. doi: 10.1016/j.chemgeo.2009.05.004
5.
LiC, LuY.1983. Selective flotation of scheelite from calcium minerals with sodum oleate as a collector and phosphates as modifiers. II. The mechanism of the interaction between phosphate modifiers and minerals. Int J Miner Process. 10(3):219–235. doi: 10.1016/0301-7516(83)90012-1
6.
LiuZ, DreybrodtW.1997. Dissolution kinetics of calcium carbonate minerals in H2O-CO2 solutions in turbulent flow: the role of the diffusion boundary layer and the slow reaction H2O+ CO2≒H+ + HCO3−. Geochim Cosmochim Acta. 61(14):2879–2889. doi: 10.1016/S0016-7037(97)00143-9
7.
LuoL-Q, ZhangJ-S, YuY-F.2005. Recovering limonite from Australia iron ores by flocculation-high intensity magnetic separation. J Cent South Univ Technol. 12(6):682–687. (English Edition) doi: 10.1007/s11771-005-0069-y
8.
PengC, CrawshawJP, MaitlandGC, Martin TruslerJP.2015. Kinetics of calcite dissolution in CO2-saturated water at temperatures between (323 and 373) K and pressures up to 13.8 MPa. Chem Geol. 403:74–85. doi: 10.1016/j.chemgeo.2015.03.012
9.
PlummerLN, WigleyTML, ParkhurstDL.1978. The kinetics of calcite dissolving in CO2-water system at 5–60°C and 0.0–1.0 atm CO2. Am J Sci. 278:179–216. doi: 10.2475/ajs.278.2.179
10.
PughR, SteniusP.1985. Solution chemistry studies and flotation behaviour of apatite, calcite and fluorite minerals with sodium oleate collector. Int J Miner Process. 15(3):193–218. doi: 10.1016/0301-7516(85)90035-3
11.
RaoKH, ForssbergKSE.2007. Chemistry of iron oxide flotation. In: FuerstenauMC, JamesonGJ, YoonRH, editors. Froth flotation: a century of innovation.Colorado: Society for Mining, Metallurgy and Exploration, Inc. (SME); p. 499.
12.
RashchiF, FinchJA.2000. Polyphosphates: A review their chemistry and application with particular reference to mineral processing. Miner Eng. 13(10–11):1019–1035. doi: 10.1016/S0892-6875(00)00087-X
13.
SchulzA.1981. Wet high intensity magnetic separation of a complex, fine intergrown, poor limonite ore with a siderite component. Germany: Bundesministerium fuer Forschung und Technologie, Bonn-Bad Godesberg; p. 70.
14.
SongS, LuS, Lopez-ValdiviesoA.2002. Magnetic separation of hematite and limonite fines as hydrophobic flocs from iron ores. Miner Eng. 15:415–422. doi: 10.1016/S0892-6875(02)00054-7
15.
SongQY, XuF, TsaiSC.1992. Magnetic seeding flocculation of weakly magnetic iron minerals. Int J Miner Process. 34(3):219–229. doi: 10.1016/0301-7516(92)90075-8
16.
UsdowskiE.1982. Reactions and equilibria in the systems CO2-H2O and CaCO3-CO2-H2O: a Review. Neues Jahrb Mineral Abh. 144:148–171.
17.
WangD-z, HuY-h.1987. Solution chemistry of flotation (In Chinese). ChangSha: Hunan Science and Technology Press.
18.
YanZ-w, LIUH-L, ZhangZ-w.2009. Influences of temperature and Pco2 on the solubility of calcite and dolomite (In Chinese). Carsologica Sin. 28(1):7–10.
19.
YoungCA, MillerJD.2000. Effect of temperature on oleate adsorption at a calcite surface: an FT-NIR/IRS study and review. Int J Miner Process. 58(1–4):331–350. doi: 10.1016/S0301-7516(99)00057-5
20.
ZhuD-Q, ZhaoQ, Guan-ZhouQ, PanJ, WangZ-Q, PanC-J.2010. Magnetizing roasting-magnetic separation of limonite ores from Anhui province in east China (In Chinese). J Univ Sci Technol Beijing. 32(6):713–718.
