Iron recovery from copper-slag with lignite-based direct reduction followed by magnetic separation

21 5 2011 5 Vol.21 No.5 The Chinese Journal of Nonferrous Metals May 2011 1004-0609(2011)05-1165-06 ( 100083) 39.96%( ) CaO 100:30:10 1 250 50 min 85% 43µm 92.05% 81.01% 30 µm TF09 X758 A Iron recovery from copper-slag with lignite-based direct reduction followed by magnetic separation YANG Hui-fen, JING Li-li, DANG Chun-ge (Civil and Environmental Engineering School University of Science and Technology Beijing, Beijing 100083, China) Abstract: In order to recycle iron from copper slag with total iron content (TFe) of 39.96%(mass fraction), a technique with lignite-based direct reduction followed by magnetic separation was presented. After analysis of chemical composition and crystalline phase, according to experimental mechanism, the tests for studying the effects of different parameters on the recovery of iron were carried out. The results show that the optimum parameters are proposed as follows: the mass ratio of copper slag/lignite/cao is 100:30:10, the reduction temperature is 1 250, the time is 50 min, and the particle size of 85% roasted product is smaller than 43 µm, under which the direct reduction iron powders with TFe of 92.05% and iron recovery rate of 81.01% are obtained. After reduction, the fayalite (Fe 2 SiO 4 ) and magnetite (Fe 3 O 4 ) in copper slag are reduced to metallic iron. The metallic iron particles whose sizes are mainly larger than 30 µm, are loosely supported on the surface of slag particles. So the monomer dissociation of metallic iron particles is easily achieved by grinding, then the dissociated metallic iron particles are recovered via magnetic separation method. Key words: copper slag; direct reduction; grinding; magnetic separation; metallic iron 800 t Fe Cu Zn Pb Co Ni Au Ag Fe (TFe>27%) [1] [2] [3 5] [6] Cu Zn Pb Co [7 13] Fe Fe Fe (Fe 2 SiO 4 ) [14 17] Fe 3 O 4 Fe 2 O 3 [15, 18] Fe Fe Fe 2 SiO 4 Fe 2010-05-31 2010-09-29 13691283453 E-mail: yanghf@ustb.edu.cn

1166 2011 5 Fe 3 O [16 17] 4 [16] [17] Fe 2 SiO 4 Fe 3 O 4 Fe 2 SiO 4 Fe Fe 1 1.1 2~3 mm ARL-ADVANT XP X 30 1 1 TFe Cu Zn Pb S P 0.12 m(cao+mgo)/m(al 2 O 3 +SiO 2 )=0.12 1 Table 1 Main chemical composition of received copper slag (mass fraction, %) TFe SiO 2 Al 2 O 3 CaO MgO 39.96 20.16 2.99 2.0 0.76 Cu Pb Zn S P 1.45 0.77 0.85 0.72 0.30 1 XRD Fig.1 XRD pattern of received copper slag Fe 2 SiO 4 Fe 3 O 4 [19] Fe 3O4 + 2C = 3Fe + 2CO2 (1) Fe2 SiO4 + 2C = 2Fe + SiO2 + 2CO (2) Fe2 SiO4 + CaO + 2C = CaSiO3 + 2Fe + 2CO (3) 2 (1) (2) (3) G Θ 1 XRD 1 Fe (Fe 2 SiO 4 ) (Fe 3 O 4 ) ( ) 37.09% 43.52% 13.18% 6.21% 0.19% CaO 2 (1)~(3) G Θ Fig.2 Relationship between standard free energy ( G Θ ) and temperature for reactions (1) (3) 1.2 Fe 2 SiO 4 Fe 3 O 4 843 K Fe 3 O 4 Fe 3 O 4 FeO Fe Fe 2 SiO 4 298~1 600 K FeO 2 G Θ Fe 3 O 4 Fe 2 SiO 4 1 045 K CaO Fe 2 SiO 4

21 5 1167 Fe 2 SiO 4 Fe 2 SiO 4 Fe 3 O 4 Fe 2 SiO 4 CaO Fe 3 O 4 Fe 2 SiO 4 1.3 100 g CaO 111 ka/m (4) Fe Fe R Fe =w(fe r )m r /[w(fe s )m s ] (4) R Fe Fe w(fe r ) Fe m r w(fe s ) Fe 39.96% m s 100 g XRD CuK α 40 kv 100 ma 8( )/min 10º~100º 3 Fe Fig.3 Effects of lignite ratio on iron recovery rate Fe 2.2 CaO Fe 30% 1 200 40 min (50% ) 43 µm CaO Fe 4 2 4 ( ) CaO (CaO ) 2.1 Fe CaO 15% 1 200 40 min (50% ) 43 µm Fe 3 3 Fe Fe 30% 4 CaO Fe Fig.4 Effects of CaO ratio on iron recovery rate 4 CaO Fe CaO Fe CaO CaO 10% CaO

1168 2011 5 Fe CaO 50 min CaO CaO Fe 2 SiO 4 2.3 Fe 30% CaO 10% 40 min (50% ) 43 µm Fe 5 6 Fe Fig.6 Effects of reduction time on iron recovery rate 5 Fe Fig.5 Effects of reduction temperature on iron recovery rate 5 Fe Fe 1 200 Fe 2 (1) (2) (3) G Θ Fe 3 O 4 Fe 2 SiO 4 1 300 1 250 2.5 Fe 30% CaO 10% 1 250 50 min Fe 7 7 Fe Fe Fe Fe Fe 85% 43 µm Fe 92.05% Fe 81.02% 2.4 Fe 30% CaO 10% 1 250 (50% ) 43 µm Fe 6 6 Fe 7 Fe Fig.7 Effects of grinding rate( 43 µm) of boasting product on iron recovery rate

21 5 1169 3 3.1 30% CaO 10% 1 250 50 min XRD 8 XRD 8 9 Fig.9 Microstructure of roasted product under optimized reduction conditions 8 XRD Fig.8 XRD pattern of roasted product under optimized reduction conditions 9 9 30 µm 5 µm 10 XRD Fig.10 XRD pattern of obtained direct reduction iron powders 2 Table 2 Main chemical composition of obtained direct reduction iron powders(mass fraction, %) TFe SiO 2 Al 2 O 3 CaO MgO 92.05 3.65 0.67 1.58 0.57 Cu Pb Zn S P 0.16 0.021 0.005 0.001 0.028 3.2 10 XRD 10 2 Fe 4 1) Fe

1170 30% CaO 10% 1 250 50 min (85% ) 43 µm Fe 92.05% Fe 81.02% 2) 30 µm REFERENCES [1],,,,,,. [J]., 2009(2): 8 11. CAO Hong-yang, FU Nian-xin, WANG Ci-gong, ZHANG Li, XIA Feng-shen, SUI Zhi-tong, FENG Nai-xiang. Selective precipitation and separation of Fe components from copper smelting slags[j]. Multipurpose Utilization of Mineral Resources, 2009(2): 8 11. [2] ALTER H. The composition and environmental hazard of copper slag in the context of the Basel convention[j]. Resources, Conservation and Recycling, 2005, 43(4): 353 360. [3] SHI C J, MEYER C, BEHNOOD A. Utilization of copper slag in cement and concrete[j]. Resources, Conservation and Recycling, 2008, 52(10): 1115 1120. [4] KHANZADI M, BEHNOOD A. Mechanical properties of high-strength concrete incorporating copper slag as coarse aggregate[j]. Construction and Building Materials, 2009, 23(6): 2183 2188. [5] JABRI K S A, HISADA M, ORAIMI S K A, SAIDY A H A. Copper slag as sand replacement for high performance concrete[j]. Cement & Concrete Composites, 2009, 31(7): 483 488. [6] KAMBHAM K, SANGAMESWARAN S, DATER S R, KURA B. Copper slag: optimization of productivity and consumption for cleaner production in dry abrasive blasting[j]. Journal of Cleaner Production, 2007, 15(5): 465 473. [7] BANZA A N, GOCK E, KONGOLO K. Base metals recovery from copper smelter slag by oxidizing leaching and solvent extraction[j]. Hydrometallurgy, 2002, 67(1/3): 63 69. [8] ARSLANA C, ARSLANA F. Recovery of copper, cobalt, and zinc from copper smelter and converter slag[j]. Hydrometallurgy, 2002, 67(1/3): 1 7. [9] RUDNIK E, BURZŃSKA L, GUMOWSKA W. Hydrometallurgical recovery of copper and cobalt from reduction-roasted copper converter slag[j]. Minerals Engineering, 2009, 22(1): 88 95. 2011 5 [10] MAWEJA K, MUKONGO T, MUTOMBO I. Cleaning of a copper matte smelting slag from a water-jacket furnace by direct reduction of heavy metals[j]. Journal of Hazardous Materials, 2009, 164(2/3): 856 862. [11] SARRAFI A, RAHMATI B, HASSANI H R, SHIRAZI H H A. Recovery of copper from reverberatory furnace slag by flotation[j]. Minerals Engineering, 2004, 17(3): 457 459. [12] CARRANZA F, ROMERO R, MAZUELOS A, IGLESIAS N, FORCAT O. Biorecovery of copper from converter slag: Slag characterization and exploratory ferric leaching tests[j]. Hydrometallurgy, 2009, 97(1/2): 39 45. [13],,. [J]., 2001, 11(2): 302 306. DENG Tong, WEN Zheng, LIU Dong. Leaching of copper residue with oxygen in sulfuric acid with participation of chloride[j]. The Chinese Journal of Non ferrous Metals, 2001, 11(2): 302 306. [14],. [J]., 2001, 11(5): 881 885. DENG Tong, LING Yun-han. Process mineralogy of cobalt-bearing copper converter slag[j]. The Chinese Journal of Non ferrous Metals, 2001, 11(5): 881 885. [15],. [J]., 2009, 18(2): 9 12. HAN Wei, QIN Qing-wei. Recovery of copper and iron from copper slag[j]. Mining & Metallurgy, 2009, 18(2): 9 12. [16],,,,. [J]., 2009(1): 71 74. LIU Gang ZHU Rong WANG Chang-an WANG Zhen-zhou GAO Feng. Experiment of molten oxidation iron extraction in copper slag[j]. China Non ferrous Metals, 2009(1): 71 74. [17],,,,,. [J]., 2009, 9(2): 284 188. CAO Hong-yang, FU Nian-xin, ZHANG Li, XIA Feng-shen, SUI Zhi-tong, FENG Nai-xiang. Migration and precipitation behavior of Fe components in copper smelting slag[j]. The Chinese Journal of Process Engineering, 2009, 9(2): 284 188. [18]. [J]., 2003, 13(2): 83 88. WANG Heng. Recovery of copper and iron In the converter slag from a copper smelter[j]. Journal of Guangdong Non-ferrous Metals, 2003, 13(2): 83 88. [19]. [M].. :, 2006. GUO Han-jie. Course of metallurgical physical chemistry [M]. 2nd ed. Beijing: Metallurgical Industry Press, 2006. ( )