Effect of Hydrochloric Acid on Leaching Behavior of Calcareous Phosphorites

Document Type : Research Article


Department of Chemistry, Bahauddin Zakariya University, Multan 60800, PAKISTAN



The bulk of the world's phosphate reserves is located in sedimentary horizons that contain appreciable amounts of carbonate. During beneficiation of phosphate rocks, huge amounts of oversize phosphate rocks are rejected from crushers. This reject also mostly contains low tricalcium phosphate and high carbonate content. In this study, experiments have been carried out to reduce/eliminate carbonate content by leaching the ground phosphate rock with dilute hydrochloric acid solution. Effects of hydrochloric acid concentration, reaction time, temperature and liquid/solid ratio (vol./wt. basis) on the process have been studied. Under the reaction conditions, some of the apatite may be dissolved to form soluble monocalcium phosphate during the selective leaching. However, by specifying the pH of the process the lime milk can be used to recover the dissolved apatite. It has been observed that upon treatment of the ground rock with dilute hydrochloric acid, the P2O5 percent can be raised up to the industrially acceptable level due to the selective reduction/elimination of calcium carbonate content of the sample, depending on the reaction conditions as well as nature and size of the raw phosphate particles used for analysis.


Main Subjects

[1] Good,  P. C., Beneficiation of Unweathered Indian Calcareous Phosphate Rock by Calcination and Hydration, US Bureau of Mines, Report No 8154, Washington (1976).
[2] Hignett,  T.P., Doll, E. C.,  Livingston, O. H. and Raistrick, B., “New Developments in Phosphate Fertilizer Technology”, Carpentier, L. J. (Ed.) Sci Pub Co Elsevier (1977).
[3] Lawver, J. E., Mcclintock, W. O. and Snow , R. E., Miner Sci Eng., 10, 278 (1978).
[4] Lodha, T. R., Sinha, N. K. and Srivastava, A. C., Chemic Age of India, 35, 15 (1984).
[5] Hsieh, S. S., Ind. Eng. Chem. Res., 27,594 (1988).
[6] Ray, H. and Robert, J. P., Miner. Proc., 10, 13 (1969).
[7] Robinson, N., “Fisons’ Experience on the effect of Phosphate Rock Impurities on the Phosphoric Acid Plant Performance”, ISMA (IFA) Orlando (1978).
[8] Mew, M. C., “World Survey of Phosphate Deposits”, 4th Ed. The British Sulfur Corp. Ltd, London (1980).
[9] Baudet, G., Chron.  Rech. Min., Special issue on Phosphates, 67 (1988).
[10] Somasundaran,  P., 11th Int.  Miner. Proc. Cong. Cagliari, 2,155 (1975).
[11] Hanna, H. S. and Somasundaran, P., In. “Flotation of salt type minerals”, Fuestenau M.C. (Ed), p.p. 197-272, A.M .Gandin Memorial Volume, AIME, New York.(1976).
[12] Lawver, J. E., Weigel, R. L., Snow, R. E. and Huang, C. L., 14th Int .Miner. Proc. Cong. Session, iv Flotation, Paper iv-20 (1982).
[13] Al-Fariss, T. F., Ozbelge, H. O. and  Abdulrazik, A.M., Rock. Fert. Res., 29, 203 (1991).
[14] Hignett T. P., Proc. Int. Cong. Phos. Comp., 401 (1980).
[15] Hollick, C. T. and Wright, R., Trans. Insti. Miner. Metall., Section A-Mining, 95, A150 (1986).
[16] Ciccu,R., Ghiani, M., Peretti, R., Stta, F. and Zucca, A., Proc. Int. Cong. Mineral. Processing, 433 (1993).
[17] Brierley, C., Pour la Science, 60, 38 (1982).
[18] Harrison, J. R., Ann. Rev. Microbiol., 38, 265(1984).
[19] Hutchins, S. R. and Davidson, M. S., Ann. Rev. Microbiol., 40, 311 (1986).
[20] Costa, A. C. A., Medronho, R. A. and Pecanha, R. P., Biotechnology Letters, 14, 233 (1992).
[21] Crago,  A., Process  of  Concentrating Phosphate Minerals, US Patent No 2, 293,640 (1940).
[22] Moudgil, B. M. and Chanchani R., Miner and Metall Proc., 2, 13 (1985).
[23] Moudgil, B. M. and Chanchani, R., Miner and Metall Proc., 2, 19 (1985).
[24] Ince, D. E., “Effect of Sodium Chloride on the Selective Flotation of Dolomite from Apatite”, Ph.D. Thesis, University of Florida (1987).
[25] Moudgil, B. M., Ince, D. E., Vasudevan T. V. and Sober, D., Miner and Metall Proc., 7, 53 (1990).
[26] Zhong, K.,Vasudevan, T. V. and Somasundaran, P., Miner Eng., 4, 563 (1991).
[27] Arafa, M. A., Modell. Meas and Cont., 43, 1 (1993).
[28] Judd, J.C. and Harbuck, D. D., Marine Georesources and Geotechnology, 11, 245 (1993).
[29] Alfantazi, A. M. and Amaratunga, L. M., J. Mines Metals and Fuels., 41, 54 (1993).
[30] Kangnian, Z., Yin, H. and Hengxing, X., J. Youse Jinshu., 46, 31 (1994).
[31] Zafar, I. Z., Anwar, M. M. and Pritchard, D. W., Int. J. Miner. Proc., 43, 123 (1995)
[32] Baumann, A. N. and Snow, R. E., Proc. 2nd Int. Cong. Phosphate Comp., April 21-25, Boston (1980).
[33] Hegner,P. and Pacl, Z., Report  No  PTE/74/12, 21P, Research   Institute   of  Inorganic  Chemistry,  40060 USTI NAD Labem Czechoslovakia, (1974).
[34] El-Jalead, I. S., Abouzeid, A. Z. M. and El-Sinbawy, H. A., Powder Technology, 26, 187 (1980).
[35] Sadeddin, W. and Abu-Eishah,S. I., Int. J. Mineral Proc., 30, 113 (1990).
[36] Abu-Eishah, S. I., El-Jallad, I. S., Muthaker, M., Touqan, M. and Sadeddin, W., Int. J. Mineral Proc., 31,115 (1991).
[37] Zafar, I. Z., Fert. Res., 34, 173 (1993).
[38] Zafar, I. Z., Anwar, M. M. and Pritchard, D. W., Fert. Res., 44, 133 (1996).
[39] Zafar, I. Z., Anwar, M. M. and Pritchard, D. W., J. Nutrient Cycling in Agroecosystems, 46, 135 (1996).
[40] Annon., Phosphorus & Potassium, 125, 29 (1983).