Effect of surface dissolution on kinetic parameters in flotation of ilmenite from different gangue minerals

The effects of acid surface dissolution on the flotation kinetics of ilmenite(IL)and its common accompanied gangue minerals including olivine-pyroxene(Ol-Px),tremolite-clinochlore(Tr-Cch)and quartz were investigated.The results show that through the surface dissolution the adsorption rate constant for ilmenite increases from 5.272 to 8.441 mol/(g·min)while it decreases for Ol-Px,Tr-Cch and quartz from 6.332,7.309 and 7.774 mol/(g·min)to 5.034,6.223 and 7.371 mol/(g·min),respectively.Also,the flotation experiments on a binary mixture of minerals indicate that after surface dissolution the values of modified rate constant for ilmenite flotation from Ol-Px,Tr-Cch and quartz are enhanced from 36.15,36.52 and 47.86 min-1 to 41.72,45.78 and 56.24 min-1,respectively.This results in the improvement of kinetic selectivity index(SI)in the separation of treated ilmenite from gangue minerals.As evidenced by ICP-MS analysis,the decrease of kinetic parameters for gangue minerals can be due to the removal of Fe^2+,Ca^2+and Mg^2+ions from their surfaces,which results in the lack of enough active sites to interact with collector species.As confirmed by contact angle measurements,this prevents the formation of a stable hydrophobic layer on the minerals surfaces for creating stable attachments between minerals and bubbles.Generally,the improvement of ilmenite flotation kinetics has a negative correlation with the iron content in its accompanied gangue minerals.

Effects of sodium carbonate and calcium chloride on calcite depression in cationic flotation of pyrolusite

In the cationic flotation of pyrolusite using dodecyl ammine(DDA),the depressive effect of sodium carbonate andcalcium chloride on the calcite mineral was investigated systematically through flotation experiments,FTIR analysis,contact anglemeasurements and zeta potential tests.The microflotation experiments showed that both depressant agents decrease the flotationrecovery of calcite significantly.In addition,sodium carbonate acts as activator agent for pyrolusite,and increases its floatability.Theflotation experiments and contact angle measurements indicated that the selective depression effect of sodium carbonate on thecalcite mineral is more than that of calcium chloride.As evidenced by zeta potential and FT-IR analysis,sodium carbonate decreasesthe negative charges on the surface of calcite mineral and subsequently reduces the adsorption of DDA collector through electrostaticforces.At a pH of7.5,using2000g/t DDA and1500g/t sodium carbonate,a pyrolusite concentrate containing almost40%MnOwith71.5%recovery is achieved by carrying out the ore flotation experiments on the tabling pre-concentrate.

Effect of microwave pretreatment on grinding and flotation kinetics of copper complex ore

The present study initially investigates the kinetics of microwave-assisted grinding and flotation in a porphyry copper deposit.Kinetic tests were conducted on untreated and microwave-irradiated samples by varying the exposure time from 15 to 150 s.Optical microscopy,energy-dispersive X-ray spectroscopy,and scanning electron microscopy were conducted to determine the mineral liberation and particle surface properties,and to perform mineralogical analyses.Results showed that the ore breakage rate constant monotonically increased by increasing the exposure time,particularly for the coarsest fraction size(400μm)due to the creation of thermal stress fractures alongside grain boundaries.Excessive irradiation time(>60 s)led to the creation of oxidized and porous surfaces along with a dramatic change in particle morphologies that result in a substantial reduction of chalcopyrite and pyrite flotation rate constants and ultimate recoveries.We concluded that MW-pretreated copper ore was ground faster than the untreated variety,but the two types have slightly similar floatabilities.

Surface modification of ilmenite and its accompanied gangue minerals by thermal pretreatment:Application in flotation process

The effect of conventional thermal pretreatment on the surface properties of ilmenite and its accompanied gangue minerals was investigated using flotation experiments(microflotation and laboratory cell flotation),XRD,XPS and FT-IR analysis and zeta potential and contact angle measurements.After treatment at 600℃ for 25 min as optimal condition,the floatability of ilmenite is improved from 73.5%to 91%at a pH value of 6.3.As demonstrated by XRD and XPS analysis,under this pretreatment condition,the Fe^(3+)content increases by almost 16.5%without any phase decomposition and structural changes in ilmenite.FT-IR analysis and contact angle and zeta potential measurements give evidences that the improvement of ilmenite floatability can be related to the enhancement of collector adsorption and the formation of a more insoluble hydrophobic layer of ferric iron oleate.The ore flotation experiments show that the thermal pretreatment process without making a significant change in TiO2 content of ilmenite concentrate enhances the TiO2 recovery from 65.4%to 73.7%.

Applied Mineralogical Studies on Iranian Titanium Deposits

Qara-aghaj and Skandian as hard rock titanium deposit and Kahnooj one as a placer deposit were investigated from applied mineralogical point of view. The mineralogical studies were carried out using XRD, XRF, optical microscopy, scanning electron microscopy and microprobe analysis. These studies indicated that ilmenite and magnetite are main valuable minerals in the studied ores. Pyroxene, olivine and plagioclase are the main gangue minerals in Qara-aghaj ore while chlorite and plagioclase are the major gangue minerals in Skandian ore. Plagioclase, clinopyroxene, amphibole, feldspate and some quartz are the important gangue minerals in kahnooj deposit. In all three ores ilmenite is mainly in the form of ilmenite grains but some lamellae of ilmenite with thickness between 0.1 to 20 μm have been occurred as exsolution textures inside magnetite grains, where the magnetite here can be referred to as ilmenomagnetite. In the hard rock ores some fine ilmenites have been disseminated in silicate minerals. The liberation degree of granular ilmenite was determined 150, 140 and 200 μm for Qara-aghaj, Skandian and Kahnooj, respectively. So, only the granular form of ilmenite is recoverable by physical methods. Some sphene and rutile as titanium containing minerals were observed mainly inside ilmenite phase in kahnooj ore. Some fine rutile was also found inside Skandian ilmenite while there were not any other titanium minerals inside Qara-aghaj ilmenite. Apatite is another valuable mineral which was found only in Qara-aghaj ore. Using SEM and microprobe analysis it was found that there are different amounts of exsolved fine lamellae of hematite inside ilmenite in Qara-aghaj and Kahnooj ores while it was not observed in Sckandian one. The average contents of TiO2 in the lattice of Qara-aghaj, Skandian and Kahnooj ilmenite were determined 51.13, 50.9% and 52.02%, respectively. FeO content of ilmenite lattice for all three samples is clearly lower than the theoretical content. This is due to the substitution of Mg and Mn for some Fe2+ ions in the ilmenite lattice. V2O3 content of magnetite lattice is up to 1%. So, magnetite can be a suitable source for production of vanadium as a by-product in all three deposits.