| Iron ore as the main raw material for steel industry is an important material basis for social and economic development.Although hematite resource is abundant in China,the quality of iron ore resource is generally unsatisfactory.Flotation is one of the most important methods to improve the quality of hematite concentrate.Reverse flotation using amine collectors has many advantages,such as simple reagents,low cost,low temperature resistance,etc.However,Reverse flotation with amine collectors may led to the sticky mineralized foam,which could not be foam eliminated easily.In this study,pure hematite and quartz samples were prepared for the micro-flotation.Dodecylamine,Dodecyl trimethyl ammonium chloride,GE-609,and N-Laurel ethanediamine were used as collectors.The effects of different factors(collectors,particle size,p H,starch dosage)on mineral flotation behavior were studied in the flotation experiments.The stabilities of the two-phase or three-phase foams of the four amine collectors were evaluated by aeration.The effect of different factors(p H,collectors,reagent concentration,minerals)on the stabilities of two-phase/three-phase foams were studied with and without minerals addition.The interaction mechanism of four kinds of amine collector between quartz and hematite was studied using infrared spectroscopy,X-ray photoelectron spectroscopy,and surface tension testing.The stabilities of two-phase /three-phase foams under different p H values were studied to reveal the foam performance in the flotation system with cationic collector This study was performed to provide valuable insight for overcoming the foam problems in the cationic process.Meanwhile,this work could be used as reference for the flotation of fine hematite.In the flotation experiments of hematite and quartz,the amine collectors showed excellent collecting capability on quartz but weak collecting capability on hematite under the same conditions.A high flotation recovery of quartz could be achieved with a low reagent dosage.When Dodecylamine,Dodecyl trimethyl ammonium chloride and GE-609 were used as collectors,the flotation recovery of quartz reached the greatest value at p H 7,and the flotation recovery of hematite reached the greatest value under low alkaline conditions.When N-Laurel ethanediamine was used as the collector,the flotation recovery of quartz reached the greatest value at p H 4.2,and the flotation recovery of hematite reached the greatest value from neutral to low alkaline.The recovery of hematite and quartz with different grain sizes using with same reagents dosage was as follows:-45+18μm,-106+45μm,-18μm.The results of the mixed flotation of hematite and quartz showed that,the effect of the four cationic collectors on the separation of hematite from quartz indicated the order as follows: Dodecyl trimethyl ammonium chloride,GE-609,Dodecylamine,N-Laurel ethanediamine.The results of two-phase foam stability tests using four kinds of amine collectors indicated that GE609 had the strongest foaming ability with low concentration(0.05%-0.2%),while the stability of Dodecylamine was better than other three kinds of amine collectors.The foams of N-Laurel ethanediamine were stable under low alkaline conditions.The effect of p H on foam half-life using other three kinds of amine collectors indicated the order as follows: acidity,neutrality,alkalinity.When the foam half-life of Dodecylamine,Dodecyl trimethyl ammonium chloride and GE-609 reached the greatest value,the solution concentrations were: 0.2%,0.4%,0.2%.There was no obvious peak value using N-Laurel ethanediamine.The three-phase foam stability tests using four kinds of amine collectors indicated that the pulp concentration and particle size both had a significant influence on the stability of three-phase foam.Compared with hematite,quartz obviously enhanced the foam stability of the four kinds of amine collectors.The half-life of the three-phase foam was increased when adding more quartz particles.Meanwhile,the change of half-life was more obvious with the decrease of particle size,and the-18μm quartz particles had the most significant effect on the half-life of three-phase foam.The results of infrared spectroscopy and X-ray photoelectron spectroscopy indicated that Dodecylamine,Dodecyl trimethyl ammonium chloride,GE-609,and N-Laurel ethanediamine were adsorbed(hydrogen bonds)on the quartz surface by physical adsorption,thereby affecting the floatability of the quartz particles.To verify the effect of p H and concentration on the surface tension of amine collectors,the surface tensions of four kinds of collectors with different concentration were measured at desired p H value(4,7,9).The results indicated that the surface tension of dodecyltrimethylammonium chloride was slightly effected by p H,while the surface tension of Dodecylamine,GE-609,and N-Laurel ethanediamine were obviously affected by p H.Under different p H value conditions,the surface tensions were hardly effected with the increase of concentration when adsorption reached saturation.It can be concluded that the foam stability was not only determined by its surface tension,but also the other factors such as inorganic salts,temperature,environmental humidity. |
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