An innovative sulfidation roasting method for the efficient flotation recovery of malachite

Abstract

Malachite, a typical copper oxide ore, exhibits strong hydrophilicity; therefore, it also exhibits poor flotation recovery. In this study, sulfidation roasting was applied as a pretreatment strategy to improve the flotation efficiency of malachite. Pyrite was used as the sulfidation agent during roasting, the feasibility of which was verified using thermodynamic calculations. Microflotation experiments demonstrate that the flotation recovery of malachite increased by nearly 70% compared with that of the untreated sample. X-ray diffraction analysis indicates that the malachite decomposed into CuO during roasting and mainly formed CuS and Cu₂S after sulfidation. This result was further supported by X-ray photoelectron spectroscopic analysis, which revealed the presence of S (S²⁻, S₂²⁻, and S_n²⁻) and Cu (Cu⁺ and Cu²⁺) species in different oxidation states on the surfaces of the roasted sample, as well as a notable decrease in oxygen content. In addition, the formation of copper sulfides disrupted the original porous structure, which led to a decrease in internal pore size. The contact angle increased from 43.71° to 89.29° after sulfidation roasting, indicating that the hydrophobicity of malachite improved markedly. Zeta potential results further indicate that the surface electronegativity increased owing to the adsorption of S species. Overall, sulfidation roasting using pyrite improved the floatability of malachite by generating hydrophobic copper sulfides on the mineral surfaces, thereby demonstrating its potential as an effective pretreatment for copper oxide ores.

Keywords

malachite / sulfidation roasting / flotation / phase transformation / microstructural / surface wettability

References

[1] J.B. Wang, W. Liu, L. Chen, X. Li, and Z.G. Wen, Analysis of China’s non-ferrous metals industry’s path to peak carbon: A whole life cycle industry chain based on copper, Sci. Total Environ., 892(2023), art. No. 164454.

[2] Feng QC, Lu WM, Wang H, Zhang Q. Mechanistic insights into stepwise activation of malachite for enhancing surface reactivity and flotation performance. Int. J. Miner. Metall. Mater., 2024, 31(10):2159.

[3] Wang QQ, Yao ZQ, Guo LJ, Shen XD. Exploring the potential of olivine-containing copper–nickel slag for carbon dioxide mineralization in cementitious materials. Int. J. Miner. Metall. Mater., 2024, 31(3):562.

[4] Elshkaki A, Graedel TE, Ciacci L, Reck BK. Copper demand, supply, and associated energy use to 2050. Global Environ. Change, 2016, 39: 305.

[5] S.S. Jena, S.K. Tripathy, N.R. Mandre, R. Venugopal, and S. Farrokhpay, Sustainable use of copper resources: Beneficiation of low-grade copper ores, Minerals, 12(2022), No. 5, art. No. 545.

[6] D. Berdakh, H. Miki, T. Hirajima, et al., Effect of oxidation treatment on the selective separation of molybdenite from chalcocite using flotation, Powder Technol., 431(2024), art. No. 119078.

[7] Zhang QC, Zhang LM, Jiang F, Tang HH, Wang L, Sun W. Ferric ion-triggered surface oxidation of galena for efficient chalcopyrite-galena separation. Int. J. Miner. Metall. Mater., 2024, 31(2):261.

[8] Shen ZH, Wen SM, Wang H, et al.Effect of dissolved components of malachite and calcite on surface properties and flotation behavior. Int. J. Miner. Metall. Mater., 2023, 30(7):1297.

[9] W.T. Xu, J. Wen, C.Y. Zhang, et al., Advances in application of theoretical computations in copper oxide mineral flotation, Miner. Eng., 232(2025), art. No. 109395.

[10] Kongolo K, Kipoka M, Minanga K, Mpoyo M. Improving the efficiency of oxide copper-cobalt ores flotation by combination of sulphidisers. Miner. Eng., 2003, 16(10):1023.

[11] Yang XL, Liu S, Liu GY, Zhong H. A DFT study on the structure-reactivity relationship of aliphatic oxime derivatives as copper chelating agents and malachite flotation collectors. J. Ind. Eng. Chem., 2017, 46: 404.

[12] Fuerstenau DW, Herrera-Urbina R, McGlashan DW. Studies on the applicability of chelating agents as universal collectors for copper minerals. Int. J. Miner. Process., 2000, 58(1–4):15.

[13] Cecile JL, Cruz MI, Barbery G, Fripiat JJ. Infrared spectral study of species formed on malachite surface by adsorption from aqueous salicylaldoxime solution. J. Colloid. Interface Sci., 1981, 80(2):589.

[14] Zheng YX, Liu W, Qin WQ, et al.Sulfidation roasting of lead and zinc carbonate with sulphur by temperature gradient method. J. Cent. South Univ., 2015, 22(5):1635.

[15] J.S. Zhou, J.F. Lv, Z.Y. Li, and Y.X. Zheng, Self-sulfidation roasting and flotation of electroplating sludge: An innovative technology for metal recovery, Sep. Purif. Technol., 353(2025), art. No. 128583.

[16] Park K, Park S, Choi J, Kim G, Tong MP, Kim H. Influence of excess sulfide ions on the malachite-bubble interaction in the presence of thiol-collector. Sep. Purif. Technol., 2016, 168: 1.

[17] Feng QC, Zhao WJ, Wen SM, Cao QB. Copper sulfide species formed on malachite surfaces in relation to flotation. J. Ind. Eng. Chem., 2017, 48: 125.

[18] J.S. Deng, H. Lai, S.M. Wen, and S.M. Li, Confirmation of interlayer sulfidization of malachite by TOF-SIMS and principal component analysis, Minerals, 9(2019), No. 4, art. No. 204.

[19] Han JW, Chen LL, Zhong XH, Wei XY, Qin WQ. A promising method for recovery of LiMn₂O₄ and graphite from waste lithium-ion batteries: Roasting enhanced flotation. J. Cent. South Univ., 2022, 29(9):2873.

[20] Yu C, Zhu LZ, Ding XM, Guo B. Sulfidation roasting of malachite and its flotation behavior. JOM, 2025, 77(4):2444.

[21] Shen YY, Wang WQ, Guo WB, et al.Treatment of low-grade copper-nickel sulfide ore by gradient sulfidation roasting method. JOM, 2025, 77(5):3430.

[22] X. Rao, C.Y. Zhang, W. Sun, J.H. Chen, and H.L. Zhang, Malachite sulfidation flotation mechanism: Cu–S co-deposition insights, Sep. Purif. Technol., 364(2025), art. No. 132476.

[23] Butler IB, Böttcher ME, Rickard D, Oldroyd A. Sulfur isotope partitioning during experimental formation of pyrite via the polysulfide and hydrogen sulfide pathways: Implications for the interpretation of sedimentary and hydrothermal pyrite isotope records. Earth. Planet. Sci. Lett., 2004, 228(3–4):495.

[24] A. Akbari, E. Akbari, A. Azadmehr, and A. Hezarkhani, Silica-functionalized pyrite core–shell particle as a new mesoporous adsorbent for water-soluble dyestuffs: Characterization, kinetic and thermodynamic studies, J. Environ. Chem. Eng., 9(2021), No. 6, art. No. 106764.

[25] Wang C, Wu ZX, Wang TB, et al.Mechanisms of nano-bubble-enhanced flotation of galena from pyrite. Int. J. Miner. Metall. Mater., 2025, 32(4):817.

[26] Wang ZJ, Shi Q, Zhang GF, Zhu YX, Li BB. Effect of pyrite content on chalcopyrite flotation under different regrinding conditions. Int. J. Miner. Metall. Mater., 2025, 32(1):49.

[27] Han WW, Yang HY, Tong LL. Interaction mechanism of cyanide with pyrite during the cyanidation of pyrite and the decyanation of pyrite cyanide residues by chemical oxidation. Int. J. Miner. Metall. Mater., 2024, 31(9):1996.

[28] Khera RA, Iqbal M, Ahmad A, et al.Kinetics and equilibrium studies of copper, zinc, and nickel ions adsorptive removal on to Archontophoenix alexandrae: Conditions optimization by RSM. Desalin. Water Treat., 2020, 201: 289.

[29] Bessho M, Wajima T, Ida T, Nishiyama T. Experimental study on prevention of acid mine drainage by silica coating of pyrite waste rocks with amorphous silica solution. Environ. Earth Sci., 2011, 64(2):311.

[30] Feng QC, Wen SM, Zhao WJ, Deng JS, Xian YJ. Adsorption of sulfide ions on cerussite surfaces and implications for flotation. Appl. Surf. Sci., 2016, 360: 365.

[31] Ockuly RA, Weese ML, Smucker BJ, Edwards DJ, Chang L. Response surface experiments: A meta-analysis. Chemom. Intell. Lab. Syst., 2017, 164: 64.

[32] Wu SL, Chen R, Chen JY, et al.Optimization of extraction and decolorization of polysaccharides from spirulina platensis by response surface experiment. Sci. Technol. Food Ind., 2024, 45(7):201.

[33] Jaafari J, Yaghmaeian K. Optimization of heavy metal biosorption onto freshwater algae (Chlorella coloniales) using response surface methodology (RSM). Chemosphere., 2019, 217: 447.

[34] Ali Hosseini S, Samadani Langeroodi N, Bahlakeh G, Khalafi M, Ramezanzadeh B. A detailed electronic-scale DFT simulation and a response surface methodology for the removal of Fe (III) ions from aqueous solutions. J. Dispersion Sci. Technol., 2024, 45(2):342.

[35] Li JC, Li GX, Qiu F, et al.Nucleation and growth control for iron- and phosphorus-rich phases from a modified steelmaking waste slag. Int. J. Miner. Metall. Mater., 2023, 30(2):378.

[36] Biesinger MC. Advanced analysis of copper X-ray photoelectron spectra. Surf. Interface Anal., 2017, 49(13):1325.

[37] H.L. Zhang, Q.Q. Zhou, S.Y. Lin, et al., Surface modification of malachite with tetraamminecopper (II) and its effect on sulfidation flotation, Miner. Eng., 189(2022), art. No. 107882.

[38] C.W. Wang, L. Sun, Q.Q. Wang, et al., Adsorption mechanism and flotation behavior of ammonium salt of N-Nitroso-N-phenylhydroxyamine on malachite mineral, Appl. Surf. Sci., 583(2022), art. No. 152489.

[39] G.B. Cheng, Y.Q. Ma, A. López-Valdivieso, and W.Z. Yin, Selective depression of phenoxyacetyl chloride on magnesite: Implications for effective flotation separation of magnesite from dolomite, Miner. Eng., 218(2024), art. No. 109017.

[40] Feng QC, Wen SM, Deng JS, Zhao WJ. Combined DFT and XPS investigation of enhanced adsorption of sulfide species onto cerussite by surface modification with chloride. Appl. Surf. Sci., 2017, 425: 8.

[41] Feng QC, Zhao WJ, Wen SM. Surface modification of malachite with ethanediamine and its effect on sulfidization flotation. Appl. Surf. Sci., 2018, 436: 823.

[42] Tang ZD, Xiao HX, Sun YS, Gao P, Zhang YH. Exploration of hydrogen-based suspension magnetization roasting for refractory iron ore towards a carbon-neutral future: A pilot-scale study. Int. J. Hydrogen Energy., 2022, 47(33):15074.

[43] Yuan S, Xiao HX, Yu TY, Li YJ, Gao P. Enhanced removal of iron minerals from high-iron bauxite with advanced roasting technology for enrichment of aluminum. Powder Technol., 2020, 372: 1.

[44] Q. Zhang, Y.S. Sun, P. Gao, and Y.X. Han, Hydrogen-based mineral phase transformation of bastnaesite: Detailed assessment of physicochemical properties and flotation behavior, Chem. Eng. J., 500(2024), art. No. 156992.

[45] Choi J, Choi SQ, Park K, Han Y, Kim H. Flotation behaviour of malachite in mono- and di-valent salt solutions using sodium oleate as a collector. Int. J. Miner. Process., 2016, 146: 38.

[46] M.F. Liu, D.X. Chen, B. Hu, et al., New insights into the activation mechanism of ammonium ions on the malachite sulfidization flotation, Miner. Eng., 205(2024), art. No. 108452.

[47] Li FX, Zhou XT, Zhao G, Lin RX. A novel decyl-salicyl hydroxamic acid flotation collector: Its synthesis and flotation separation of malachite against quartz. Powder Technol., 2020, 374: 522.

[48] C.H. Zhang, Y.H. Su, T.S. He, et al., The role of copper ions in improving the flotation of chalcopyrite at low temperatures, Miner. Eng., 220(2025), art. No. 109091.

[49] C. Su, D.W. Liu, J.P. Cai, and P.L. Shen, Ammonium-amine co-activation: Promoting the sulfurization of azurite and its effect on xanthate adsorption, Molecules, 28(2023), No. 21, art. No. 7376.

[50] I. Park, D. Uchida, S. Jeon, K. Aikawa, N. Hiroyoshi, and M. Ito, Microencapsulation-based surface modification for improving flotation separation of Cu–Zn mixed sulfide minerals, Miner. Eng., 213(2024), art. No. 108756.

[51] Z. Yang, G. Huang, G.H. Zheng, and C.H. Yang, Investigation on coal floatability and pore characteristics using acidification method, Sep. Purif. Technol., 330(2024), art. No. 125398.

Rights & permissions

University of Science and Technology Beijing