Conservation Journal

"An International Journal Devoted to Conservation of Environment"


ISSN: 2278-5124 (Online) :: ISSN: 0972-3099 (Print)

Conservation Journal

"An International Journal Devoted to Conservation of Environment"


ISSN: 2278-5124 (Online) :: ISSN: 0972-3099 (Print)

Conservation Journal

"An International Journal Devoted to Conservation of Environment"


ISSN: 2278-5124 (Online) :: ISSN: 0972-3099 (Print)

Conservation Journal

"An International Journal Devoted to Conservation of Environment"


ISSN: 2278-5124 (Online) :: ISSN: 0972-3099 (Print)

Conservation Journal

"An International Journal Devoted to Conservation of Environment"


ISSN: 2278-5124 (Online) :: ISSN: 0972-3099 (Print)

previous arrow
next arrow

Extraction of precious metals in fly ashes

Rekha Rani

Department. of Zoology, Navyug Kanya Mahavidyalaya, Rajendra Nagar, Lucknow- (UP) India   


Although fly ash disposal is of environmental concern the quality of residues can be improved with respect to high value applications. Fly ash is considered as a potential source of aluminium and other strategic metals. Leaching and metal extraction behaviour of fly ash collected from Thermal Power Station have been thoroughly studied using as extractant.Coal fly ash is generated during the combustion of coal for energy production. Its utilisation as an industrial lay-product has received a great deal of attention over the past two decades as more sustainable solutions to waste problems have been sought. The present paper reviews the potential applications for coal fly ash as a raw material: as a soil amelioration agent in agriculture, in the manufacture of glass and ceramics, in the production of zeolites, in the formation of mesoporous materials, in the synthesis of geopolymers, for use as catalysts and catalyst supports, as an adsorbent for gases and waste water processes, and for the extraction of metals. The review then analyses the impact that a multi-stage process could have by examining the technology capable of a series of separations to produce hollow microspheres, enriched carbon, magnetic spheres, fine ash product, and coarse ash product. The applications for these coal fly ash derived products were also reviewed. Since Our Common Future popularized the concept of sustainable development, researchers and industrialists have searched for ways of making industrial processes.

Power plant, Coal, Fly Ashes, Precious Heavy metals

Ayala, J. Blanco, F. Garcia, P.Rodriguez ,P. Sancho, J.,1998. Asturian fly ash as a heavy metals removal material.Fule,77(11): 1147-1154.

Bai, G. Teng, W. Wang, X. Qin, J.G. Xu, P. Li P., 2010. Alkali desilicated coal fly ash as substitute of bauxite in lime-soda sintering process for aluminum production. Trans Nonferr Met Soc China, 20(Supplement 1(0)): 169–75.

Berkgaut V., Singer A., 1996.  High capacity cation exchanger by hydrothermal zeolitization of coal fly ash. Appl Clay Sci.,10(5):369–78.

Erol, M. Kucukbayrak, S. Ersoy-Mericboyu, A.,2008. Comparison of the properties of glass, glass–ceramic and ceramic materials produced from coal fly ash. J Hazard Mater.153(1–2):418 25

Font, O. Querol, X. Huggins, F. Chimenos, J.M. Fernández, AI. Burgos, S. García Peña,F.,2005. Speciation of major and selected trace elements in IGCC fly ash. Fuel, 84:1364–71.

Font, O.,2007 Trace element in integrated gasification combined cycle fly ash: extraction of potentially valuable elements. Ph.D. Thesis. Polytechnic University of Catalonia. UPC.

Font, O. Moreno, N. Dıez ,S. Querol, X. Lopez-Soler, A.Coca, P. et. al.,2009. Differential behaviour of combustion and gasification fly ash from Puertollano Power Plants (spain) for the synthesis of zeolites and silica extraction. J Hazard Mater, 166(1):94–102.

Harris, B.,2003. The removal of arsenic from process solutions: theory and industrial practice. In: Young C, Alfantazi A, Anderson C, James A, Dreisinger D, Harris B, editors. Hydrometallurgy 2003 Proceedings of 5th International Symposium. TMS, Warrendale, 1889–902.

He ,Y. Cheng, W. Cai, H.,2005. Characterization of a-cordierite glass–ceramics from fly ash. J Hazard Mater,120(1–3):265–9.

Holler, H. and  Wirsching, U., 1985.Zeolite formation from fly-ash. Fortschr Mineral, 63(1):21–43.

Hollman, G.G. Steenbruggen, G. Janssen-Jurkovicˇova, M., 1999.A two-step process for the synthesis of zeolites from coal fly ash. Fuel,78(10):1225–30.

Hui, K.S. Chao, C.Y.H., Pure.,2006. Single phase, high crystalline, chamfered-edge zeolite 4A synthesized from coal fly ash for use as a builder in detergents. J Hazard Mater,137(1):401–9.

Inada, M. Eguchi, Y. Enomoto,N. Hojo, J.,2005. Synthesis of zeolite from coal fly ashes with different silica-alumina composition. Fuel, 84(2–3):299–304.

Jedidi, I. Saidi, S. Khemakhem, S. Larbot, A. Elloumi-Ammar, N. Fourati, A. et. al., 2009.Elaboration of new ceramic microfiltration membranes from mineral coal fly ash applied to waste water treatment. J Hazard Mater, 172(1):152–8.

Jedidi, I. Khemakhem, S. Saidi, S. Larbot, A. Elloumi-Ammar, N. Fourati, A. et. al., 2011.Preparation of a new ceramic microfiltration membrane from mineral coal flyash: application to the treatment of the textile dying effluents. Powder Technol, 208(2):427–32.

Jha, V.K. Nagae, M. Matsuda, M. Miyake, M.,2009. Zeolite formation from coal fly ash and heavy metal ion removal characteristics ofthus-obtained zeolite X in multi-metal systems. J Environ Manage., 90(8):2507–14.

Kazemian, H. Naghdali, Z. Ghaffari Kashani, T. Farhadi, F., 2010. Conversion of high silicon fly ash to Na–P1 zeolite: alkaline fusion followed by hydrothermal crystallization. Adv Powder Technol,  21(3):279–83.

Kersch, C.Van Roosmalen, M. J. E.,Woerlee, G. F. Witkamp, G.J.,2000. Extraction of Heavy Metals from Fly Ash and Sand with Ligands and Supercritical Carbon Dioxide. Ind. Eng. Chem. Res., 39:4670-4672.

Kim, J.K. and  Lee H.D., 2009. Effects of step change of heating source on synthesis of zeolite 4A from coal fly ash. J Indust Eng Chem, 15(5):736–42.

Kikuchi, R.,1999. Application of coal ash to environmental improvement: transformation into zeolite, potassium fertilizer, and FGD absorbent. Resour Conserv Recycl.,27(4):333–46.

Matjie, R.H. Bunt, J.R. Van Heerden, J.H.P., 2005. Extraction of alumina from coal fly ash generated from a selected low rank bituminous South African coal. Miner Eng., 18(3):299–310.

Mishra, T. and Tiwari, S.K., 2006.Studies on sorption properties of zeolite derived from Indian fly ash. J Hazard Mater,137(1):299–303.

Moreno, N. Querol, X. Plana, F. Andres, J.M. Janssen, M. Nugteren, H.,2002. Pure zeolite synthesis from silica extracted from coal fly ashes. J Chem. Technol. Biotech., 77(3):274–9.

Molina, A. Poole, C.,2004. A comparative study using two methods to produce zeolites from fly ash. Miner Eng.,17(2):167–73.

Moriyama, R.Takeda, S. Onozaki, M. Katayama, Y. Shiota, K. Fukuda, T. et al.,2005. Large-scale synthesis of artificial zeolite from coal fly ash with a small charge of alkaline solution. Fuel. 84(12–13):1455–61.

Murayama, N. Yamamoto, H. Shibata, J.,2002. Mechanism of zeolite synthesis from coal fly ash by alkali hydrothermal reaction. Int J Miner Process, 64(1):1–17.

Nayak, N. and Panda, C.R., 2010. Aluminium extraction and leaching characteristics of Talcher thermal power station fly ash with sulphuric acid. Fuel, 89(1):53–58.

Nayak, N. and  Panda, C.R., 2007. J Indian Chem Soc, 84:603.

Park, H.C. Park, Y.J. Stevens, R.,2004. Synthesis of alumina from high purity alum derived from coal fly ash. Mater Sci Eng A., 367(1–2):166–70.

Peng, F. Liang, K. Hu, A., 2005. Nano-crystal glass–ceramics obtained from high alumina coal fly ash. Fuel, 84(4):341–6.

Pickhardt, W.,1989. Trace elements in minerals of German bituminous coals. Int J.Coal Geol., 14:137–53..

Querol, X. Moreno, N. Umana, J.C. Alastuey, A.,2002.Hernandez E, Lopez-Soler A, et al.Synthesis of zeolites from coal fly ash: an overview. Int J Coal Geol.,50(1–4):413–23.

Querol, X. Alastuey, A. Lopez-Soler, A. Plana, F. Andres, JM. Juan, R. et al.,1997. A fast method for recycling fly ash: microwave-assisted zeolite synthesis. Environ Sci Technol., 31(9):2527–33.

Querol, X. Umana, J.C. Plana, F. Alastuey, A. Lopez-Soler, A. Medinaceli, A. et. al., 2001.Synthesis of zeolites from fly ash at pilot plant scale. Examples of potential applications. Fuel, 80(6):857–65

Rıos, R. C.A., Williams. CD, Roberts CL.,2009. A comparative study of two methods for the synthesis of fly ash-based sodium and potassium type zeolites. Fuel,88(8):1403–16.

Sarkar, A. Rano, R. Mishra, K.K. Sinha, I.N., 2005. Fuel Process Technol.,86(11):1221.

Sarkar, A. Rano, R. Udaybhanu, G. Basu ,A.K., 2006.Fuel Process Technol.,87(3):259.

Shabtai, Y.and Mukmenev, I. A., 1996.Combined chemical-biotechnological treatment of coal fly ash (CFA). J Biotechnol.,51(3):209–17.

Shigemoto, N. Hayashi, H. Miyaura, K., 1993. Selective formation of Na-X zeolite fromcoal fly-ash by fusion with sodium-hydroxide prior to hydrothermal reaction. J Mater Sci., 28(17):4781–6.

Sokolar, R. Vodova, L., 2011.The effect of fluidized fly ash on the properties of dry pressed ceramic tiles based on fly ash-clay body. Ceram Int.,37(7):2879–85.

Swaine, D.J.,2000. Why trace elements are important. Fuel Process Technol., 65–66:21–33..

Tanaka, H. Fuji, A. Fujimoto, S. Tanaka, Y., 2008. Microwave-assisted two-step process for the synthesis of a single-phase Na-A zeolite from coal fly ash. Adv Powder Technol., 19(1):83–94.

Tanaka, H.  and Fuji A., 2009.Effect of stirring on the dissolution of coal fly ash and synthesis of pure-form Na-A and -X zeolites by two-step  process. Adv Powder Technol., 20(5):473–9.

Tolhurst,L. 2015. Commercial recovery of metals from coal ash. WOCA, Nasvhille TN 5-7 May.

Turiel, J.L.F.  and Carvalho W.D., 1994. Cabanas M, Querol X, Soler AL. Mobility of heavy metals from coal fly ash. Environ Geol.,23:264–70.

Vasilopoulos. K.C. Tulyaganov, D.U. Agathopoulos, S. Karakassides, MA. Ferreira, JMF. Tsipas, D.,2009. Bulk nucleated fine grained mono-mineral glass–ceramics fromlow-silica fly ash. Ceram Int., 35(2):555–8.

Walek, T.T. Saito, F. Zhang, Q.,2008. The effect of low solid/liquid ratio on hydrothermal synthesis of zeolites from fly ash. Fuel,87(15–16):3194–9.

Yao, Z.T. Xia, M.S. Ye, Y. Zhang, L., 2009. Synthesis of zeolite Li-ABW from fly ash by fusion method. J Hazard Mater., 170(2–3):639–44.

Yavuz, C.T. Prakash, A.Mayo, J.T. Colvin V.L., 2009. Magnetic separations: from steel plants to biotechnology. Chem Eng Sci., 64(10):2510–21.

Zhang, L. & Xu, Z.,2016. An environmentally-friendly vacuum reduction metallurgical process to recover germanium from coal fly ash. Journal of Hazardous Materials 312, 28–36, doi:10.1016/j.jhazmat.2016.03.025.

Zhang, L.and Xu, Z.,2017. Application of vacuum reduction and chlorinated distillation to enrich and prepare pure germanium from coal fly ash. Journal of Hazardous Materials 321, 18–27, doi:10.1016/j.jhazmat.2016.08.070.

Zyryanov, V.V. Petrov, S.A. Matvienko, AA., 2011. Characterization of spinel and magnetospheres of coal fly ashes collected in power plants in the former USSR. Fuel ,90(2):486–92

Rani, R. (2017). Extraction of precious metals in fly ashes. Environment Conservation Journal18(3), 141-151.


Received: 19.06.2017

Revised: 12.08.2017

Accepted: 05.09.2017

First Online: 21.12. 2017



Publisher Name:  Action for Sustainable Efficacious Development and Awareness (ASEA)

Print : 0972-3099

Online :2278-5124