Choghaie Feldspatından Flotasyon ile Demirin Uzaklaştırılması Iron Removal from Choghaie Feldspar Mine by Flotation

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1 Choghaie Feldspatından Flotasyon ile Demirin Uzaklaştırılması Iron Removal from Choghaie Feldspar Mine by Flotation Ali Ghorbani, Hamed Haghi School of Mining Engineering, University of Tehran, Tehran, Iran ÖZET Bu çalışmada, Choghaie Feldspat sahasından alınmış olan numuneler içerisindeki demir içeriğinin (% Fe 2 O 3 olarak) düşürülebilirliği araştırılmıştır. Elde edilen son ürünün demir içeriği en fazla % 0,2 olmalı, feldspat taneciklerinin serbestleşmesinin sağlanabilmesi için numunelerin d80: 150 mikron tane iriliğine öğütülmesi gerekmektedir. Yapılan testler ile manyetik separasyon, şlam atma ve flotasyon yöntemlerinin kombinasyonu şeklinde uygulanacak bir zenginleştirme devresinin bu işlem için en iyi seçenek olduğu belirlenmiştir. Aero 801, Aero 825 (toplayıcı) ve Çam yağı (köpürtücü) 2,5-3 ph değerinde yapılacak flotasyon işlemi için en uygun reaktifler olarak tespit edilmiştir. Optimum koşullar kullanılarak yapılan test sonucunda elde edilen konsantre demir içeriği % 0,1 olarak belirlenmiş, konsantre ağırlık verimi ise % 69,3 olarak gerçekleşmiştir. ABSTRACT In this research the possiblity of reduction of iron content (as Fe 2 O 3 %) in feldspar samples provided from Choghaie feldspar mine was invesitgated. The iron content of final product should be up to 0.2%. In order to obtain the required liberation of feldspar particles, samples should grinded up to 80% finer than 150 microns. Among the processing tests including magnetic separation, desliming, flotation and combination of some process were detected as the most efficient circuit. Aero 801 & 825 (as collecors), pine oil(as forther) were found to be the most sutiable reagents to float the ore in ph conditions The best result of the whole processing tests produced feldspar concentrate containing 0.1% Fe 2 O 3, weighing about 69.3% of feed weight. 1 INTRODUCTION Feldspar is the most abundant mineral group in the world and makes about 60% of earth crust which is used in ceramics and glass industries as melting material. It can also used as filler (Bayat, et al, 2006; Bozkurt, et al, 2006; Potter, 2006). Mineralogical composition of feldspar can be categorized as triple system (Orthoclase, Albite and Anorthite). In chemical point of view, feldspars are aluminum silicate with Na, K, Fe, Ca or Ba and etc (Rau, 1985; Karaguzel, 2006). Commercial feldspars like Albite (NaAlSi 3 O 8 ) and Orthoclase-Microcline (KAlSi 3 O 8 ) usually contain impurities like clay, mica group minerals (especially Biotite and Muscovite), iron oxides, Tourmaline, Rutile and Sphene. To obtain high quality feldspar concentrate for the ceramics and glass industries, these coloring impurities have to be removed. Although high intensity permanent magnetic rolls are employed for the ores inherently low in iron, flotation is still indispensable for many ores especially the ones containing high amounts of titanium and iron (Orhan, et al, 2006). The samples were provided from zones named 2, 3 of Choghaie feldspar mine in Hamedan, Iran and weigh about 100 kg. Particle size was about cm at the beginning. After 3 phases of crushing, mineralogical investigations like microscopic study of thin and polished sections and also chemical analysis were done. Optimization tests of grinding were performed at dry and wet mill and finally removing the iron impurities by desliming, wet magnetic 202

2 7th Industrial Minerals Symposium and Exhibition / February 2009, Kusadasi, Izmir, Turkey separation, flotation and combination of all these methods were investigated. 2 MATERIALS & METHODS After three phases of crushing, preliminary sample was divided to seven particle size fraction and new samples were obtained from each fraction for chemical analysis and mineralogical studies. Another sample as head sample was used for chemical analysis. In Table 1 weight percent and major oxides percent of each size fraction is mentioned. 2.1 Mineralogy The main results of mineralogical investigations including microscopic study of thin and polished sections and XRD analysis are like below: 1. Main minerals are quartz and feldspar. 2. Feldspars are mainly from Plagioclase with Albite and small portions of basic feldspars with Microcline and Orthoclase. 3. Impurities are Biotite and Tourmaline. 4. Alteration minerals are Sersite, Kaolinite and Calcite. 5. Semi translucent and opaque minerals are Magnetite, Ilmenite, Hematite, Goethite, Pyrite and Rutile. 6. Minimum percent of feldspar is 50% which 20% of that is potash spar and the rest is soda spar. Grain size of feldspar and quartz are and 100 microns, respectively. 7. Carbonate content is less than 1% and the size is about 50 micron. 8. Heavy mineral content is about 1-2 % and their sizes are about microns. 9. Feldspar degree of freedom from other minerals is about 150 microns. Table1.chemical analysis of different size fraction and head sample. Size (microns) Weight (%) SiO 2 Al 2 O3 Fe 2 O 3 Na 2 O K 2 O sample head Sample Preparation for Tests After mineralogical studies optimization of crushing were performed in Denver laboratory rod mill with dry and wet condition. In each test, 1kg of sample was used and solid percent was 50% in wet rod mill. According to degree of freedom of feldspar (150 microns) and obtaining a product which 90% of particles is smaller than 150 microns, the best retention time in dry and wet mill is 20 and 15 minutes respectively. Since the rest of the concentration circuit is wet, the wet mill is chosen. 2.3 Mineral Processing Instruments In all tests, 1kg of sample was grinded in Denver wet rod mill with 50% solid percent for 15 minutes. Primary tests were done without desliming. In the other tests desliming carried out with initial pressure of 0.5 kg/cm 2 in a hydro cyclone. Using lazar analysis of Fritch, d 90 of slime was 4 microns. Chemical analysis of underflow (product) and overflow (slimes) presented in Table2. Wet low intensity magnetic separation (WLIMS) test were done with separator made by Eriez Company, used concurrent direct with 3 Amperes, 70Volts and 55rpm. The magnetic intensity in this test was 0.2 Tesla. Also wet high gradient 203 Editors: U. Ipekoglu, A.H. Deliormanli, S. Sen, G. Akar, D. Karakus

3 magnetic separator (WHGMS) made by Boxmag Rapid with 1.8Tesla magnetic intensity was used for tests. In this case Amperage, voltage and rotor speed are 42A, 180V and 3rpm respectively. Flotation tests were done in Denver conventional flotation set with 2liters cell capacity. 3 MINERAL PROCESSING TESTS 3.1 Magnetic Separation Results of iron removal from feldspar by wet magnetic separation were represneted in Table3. regarding this table, is postulated that wet magnetic separation is not enough for this sample and flotation is not avoidable to achieve product with Fe 2 O 3 content less than 0.1 %. Table2. Chemical analysis of underflow (product) and overflow (slimes) of hydro cyclone. Size (microns) Weight (%) SiO 2 Al 2 O3 Fe 2 O 3 Na 2 O K 2 O Slime (overflow) product (underflow) Feed (calculated) Table3. Results of iron removal from feldspar by wet magnetic separation. Assay (%) Test Type Sample Type weight (%) SiO 2 Al 2 O 3 Na 2 O K 2 O Fe 2 O 3 Fe 2 O 3 Dist. WLIMS WLIMS & WHGMS *** Product Tail Feed * Product Mid Product Tail Tail1** Feed * * : feed assay were calculated **: WLIMS Tail *** Tail2, Mid Product & Proudct were caused by WHGMS 3.2 Flotation Tests All Flotation tests are carried out in acid Circuits, either with H 2 SO 4 or HF. Reagents normally used in feldspar are H 2 SO 4 or HF, kerosene, fuel oil, amine acetates such as ArmacT, petroleum sulphonate, sulfuric acid, and hydrofluoric acid. For all the grades of feldspar, the iron content should be below 0.1 percent Fe 2 O 3 and that there are definite ratios of K 2 O and Na 2 O to silica (Denver). The first flotation step is to remove mica group minerals. Mica flotation is achieved by considering cationic collector (an amine) at ph 3 using H 2 SO 4. Mica is removed in a froth product. Iron bearing minerals are removed next, this time using an anionic collector, petroleum sulphonate, at ph 3 (Rau, 1985). The production of high grade feldspar requires a final flotation step, again in ph 3. The collector is the same cationic amine as used in mica flotation, but this time the ph is controlled with HF to depress quartz (silica) (Potter, 2006). At first some tests were carried out on sample with out desliming. Chemical 204

4 7th Industrial Minerals Symposium and Exhibition / February 2009, Kusadasi, Izmir, Turkey reagents and result of these tests are presented in Table4. regarding this table to achieve product with Fe 2 O 3 content less than 0.1 % desliming process (elimination of particles less than 10 microns) with hydrocyclone is necessary. Some tests were carried out on deslimed samples. The Chemical reagents and result of these tests are presented in Table5. The conditions, chemical ragent and product assay of most important tests are presented in Table6. Also one test is carried out with combination of wet magnetic separation and flotation but the result is not cosiderable and final proudct weight percent and its Fe 2 O 3 content are 48.12% and 0.18% respectively. Table4. Results of iron removal from feldspar by flotation without desliming. Chemical reagent * Final Product No. collector(s) Ionic Cationic frother other Weight (%) Fe 2 O 3 (%) 1 Aero845 Armoflote MFA Aero845 Armoflote MFA13 MIBC Aero825 Flotigam EDA0160 Aerofroth Flotinor FS-2 Flotigam EDA0160 Aerofroth Flotinor FS-2 Flotigam EDA0160 MIBC Oil Aero801 Flotigam EDA0160 Pine Oil Aero801 Flotigam EDA0160 Pine Oil Oil * Other main reagent: sulfuric acid (H 2 SO 4 ) for ph control and HF for silica depressant - Solid Percent: 60 % (during conditioning time) Table5. Results of iron removal from feldspar by flotation with desliming. Chemical reagent * Final Product No. collector(s) Ionic Cationic frother other Weight (%) Fe 2 O 3 (%) 8 Aero801 Armoflote MFA13, Flotigam EDA0160 Pine Oil Flotinor FS-2 Armoflote MFA13 Pine Oil Aero801 Flotigam EDA0160 Pine Oil Flotinor FS-2 Flotigam EDA0160 MIBC Aero801 - Pine Oil Aero801 Armoflote MFA13 Pine Oil Aero841 Armoflote MFA13 Pine Oil Scrubbed Aero801 Aero827 - Pine Oil Aero801 - Pine Oil Aero801 Aero825 - Pine Oil * Other main reagent: sulfuric acid (H 2 SO 4 ) for ph control and HF for silica depressant - Solid Percent: 60 % (during conditioning time) 205 Editors: U. Ipekoglu, A.H. Deliormanli, S. Sen, G. Akar, D. Karakus

5 Table6. conditions, chemical ragent and product assay of most important flotation tests. Test number Chemical reagent (gr/ton) Product assay (%) H2SO4 HF Aero 800 series Flotinor. Armoflote. Flotigam. frother SiO 2 Al 2 O 3 Na 2 O K 2 O Fe 2 O * *: 1000 (gr/ton) Aero (gr/ton) Aero Solid Percent: 60 % (during conditioning time), multi stages of frothing is available 4 CONCLUSION 1. Desliming using hydro cyclone is necessary after grinding and application of hydro cyclone can remove more than 35% of iron content in the head sample and other iron impurities caused by grinding process. 2. Wet magnetic separation for iron in this feldspar is not enough. Also combination of wet magnetic separation with flotation was not successful enough for removing iron impurities. 3. Suitable method for iron removal is flotation in acid environment. 4. The best product of feldspar flotation has highest grade with 0.06% of Fe 2 O 3. in this case weight percent of product was 69.3% 5. Appropriate chemical reagents are Aero801 & Aero825 as collectors (each 1000 gr/ton), sulfuric acid for ph control and pine oil. concentration of Turkish feldspars, Mineral Engineering, Vol.19, pp Bozkurt, V., et al., 2006, Recovery of feldspar from trachyte by flotation, Mineral engineering, Vol.19, pp Denver, 1980, Mineral Processing Flowsheets. Karaguzel, C., et al., 2006, Concentration of K- feldspar from a pegmatitic feldspar ore by flotation Mineral Processing, Vol.81, pp Orhan, E. C., et al., 2006, Amine oleate interactions in feldspar flotation, Mineral engineering, Vol.19, pp Potter, M. H., 2006, 7 th Edition of Industrial Minerals & Rocks, SME, pp Rau, E., 1985, SME Mineral Processing Handbook, SME, Vol.2, section29, pp SME, 1980, REFERENCES Bayat, O., et al., 2006, Combined application of different collectors in the floatation 206