ISSN (Print): 2376-7952

ISSN (Online): 2376-7960

Content: Volume 2, Issue 1


A Comparative Study of Various Empirical Methods to Estimate the Factor of Safety of Coal Pillars

1Department of Mining Engineering, Indian School of Mines – Dhanbad-04, Jharkhand, India

American Journal of Mining and Metallurgy. 2014, 2(1), 17-22
DOI: 10.12691/ajmm-2-1-3
Copyright © 2014 Science and Education Publishing

Cite this paper:
A. K. Verma. A Comparative Study of Various Empirical Methods to Estimate the Factor of Safety of Coal Pillars. American Journal of Mining and Metallurgy. 2014; 2(1):17-22. doi: 10.12691/ajmm-2-1-3.

Correspondence to: A.  K. Verma, Department of Mining Engineering, Indian School of Mines – Dhanbad-04, Jharkhand, India. Email:


Design of coal pillars in a coal mine remains a challenge inspite of several theories proposed by several researchers over a period of time. India is heavily dependent on coal availability for supply of electricity to it’s billion of citizens. This has burdened the coal industry to increase the coal production which ultimately has lead to extraction of coal pillars also. Coal pillars are used to support the overlying roof rock to prevent it from falling. The dilemma with coal pillar stability is that On one hand, the size of the pillar should be as small as possible to enable maximum recovery of coal, while on the other hand, the pillar should be large enough to support the load of overlying strata. The stability of coal pillars has fascinated several researchers and hence many empirical equations have been proposed over the decades. In this paper, parameters like height of pillar, depth of pillar, compressive strength of coal, depth of the coal seam have been taken as input to estimate factor of safety of coal pillar from two mines i.e., Begonia and Bellampalli. It is found that Greenwald (1941), Salamon and Munro (1967), Sheorey (1992) and Maleki (1992) method has estimated failed cases correctly while Sheorey (1992) & Maleki (1992) have not predicted stable case of pillar correctly which is an interesting finding as empirical relations proposed by Sheorey (1992) is assumed to have good prediction in Indian condition.



[1]  Bieniawski, Z. T, Balkema (1984): A. A. Rock Mechanics Design in Mining and Tunneling; 272 pp.
[2]  Bieniawski, Z. T. (1992): A method revisited: coal pillar strength formula based on field investigations, proceedings, workshop on coal pillar mechanics and design, Bu mines; p 158-165.
[3]  Bieniawski ZT. (1968): In situ strength and deformation characteristics of coal; Volume 2, 325-40.
[4]  Bunting, D. (1991): Chamber Pillars in Deep Anthracite Mines. Trans. AIME; vol. 42, pp. 236-245.
[5]  Christopher Mark. (1981-2006): Chief, Rock Mechanics Section NIOSH-Pittsburgh Research Laboratory Pittsburgh, PA, USA, The evolution of intelligent coal pillar design.
Show More References
[6]  Das, M.N. and Sheorey, P. R. (1986): Triaxial Strength behavior of some Indian coals. Journal of Mines, Metals & Fuels; 34 (3). pp. 118-122.
[7]  Hudson, J.A., Brown, E.T. and Fairhurst, C. (1972): Shape of the complete stress-strain curve for rock. In Proc. 131h Symposium on Rock Mechanics, Urbana, Illinois, Edited by E.J. Cording; pp: 773-795.
[8]  Jaiswal, Ashok, Shrivastva, B.K. (2009): Numerical simulation of coal pillar strength, International Journal of Rock Mechanics & Mining Sciences; Volume 46, 779-788.
[9]  Jawed, M., Sinha, R. K. and Sengupta, S. (2013): Chronological development in coal pillar design for board and pillar workings: A critical appraisal, Journal of Geology and Mining Research; Vol. 5 (1): pp. 1-11.
[10]  Mohan, G. Murali, Sheorey, P.R., Kushwaha. A. (2001): Numerical estimation of pillar strength in coal mines, International Journal of Rock Mechanics & Mining Sciences; Volume 38, 1185-1192.
[11]  Mark, C. (1999): Empirical Methods for Coal Pillar Design. Proceedings of the Second International Workshop on Coal Pillar Mechanics and Design. U.S. Department of Health and Human Services, National Institute for Occupational Safety and Health (NIOSH); IC 9448, pp. 145-154.
[12]  Martin,C.D., Maybee, W.G. (2000): The strength of hard-rock pillars, International Journal of Rock Mechanics & Mining Sciences; Volume 37; 1239-1246.
[13]  Maleki H. (1992): In situ pillar strength and failure mechanisms for US coal seams. In: Proceedings of the workshop on coal pillar mechanics and design, Pittsburgh, US States Bureau of Mines; p. 73-8.
[14]  Mukhopadhyay, G., Mukhopadhyay, S. K., Roychowdhury, M and Parui, P. K. (2010): Stratigraphic Correlation between Different Gondwana Basins of India, journal geological society of india; Vol. 76: pp. 251-266.
[15]  Salamon MDG, Munro. A.H. (1967): A study of the strength of coal pillars. J. South Afr. Inst. Min. Metallurgy; 68:55-67.
[16]  Sheorey, P. R., Das, M. N., Bordia, S. K., Singh B. (1986): Pillar strength approaches based on a new failure criterion for coal seams, International Journal of Mining and Geological Engineering; Volume 4: pp 273-290.
[17]  Sheorey PR. (1992): Design of coal pillar arrays, chain pillars. In: Hudson JA, et al., editors. Comprehensive rock engineering, vol. 2. Oxford: Pergamon; p. 631-70.
Show Less References


Stream Sediment Geochemical Survey of Gouap-Nkollo Prospect, Southern Cameroon: Implications for Gold and LREE Exploration

1Laboratory of Petrology and Structural Geology, University of Yaoundé I, Cameroon

2Department of Geology, HTTC, University of Bamenda, Cameroon

3Department of Geology, University of Dschang, Dschang, Cameroon

4Institut de Recherches Géologiques et Minières, Yaoundé, Cameroun

American Journal of Mining and Metallurgy. 2014, 2(1), 8-16
DOI: 10.12691/ajmm-2-1-2
Copyright © 2014 Science and Education Publishing

Cite this paper:
Soh Tamehe Landry, Ganno Sylvestre, Kouankap Nono Gus Djibril, Ngnotue Timoleon, Kankeu Boniface, Nzenti Jean Paul. Stream Sediment Geochemical Survey of Gouap-Nkollo Prospect, Southern Cameroon: Implications for Gold and LREE Exploration. American Journal of Mining and Metallurgy. 2014; 2(1):8-16. doi: 10.12691/ajmm-2-1-2.

Correspondence to: Ganno  Sylvestre, Laboratory of Petrology and Structural Geology, University of Yaoundé I, Cameroon. Email:;


Stream sediments play a significant role in geochemistry exploration by identifying possible sources of anomalous element concentration. This work is the baseline stream sediments geochemical study which brings general information on the geochemical dispersion of the metal elements (especially gold) at Gouap-Nkollo prospect (SW Cameroon) with the aim of providing a useful guide for future exploration strategies. For this study a concentration of 47 elements was measured in 10 stream sediment samples using BLEG and ICP-MS methods, but emphasis was given to the following 21 chemical elements: Al, Ca, Fe, K, Mg, Na, P Ag, Au, B, Co, Cr, Cu, Mn, Ni, Ti, Zn, Ce, La Th, U and Zr. Averaged elemental concentration for each samples obtained by statistical analysis showing patterns of enrichment and depletion which may relate to localized mineralization conditions or local lithological changes. Results showed that the stream sediments have high concentrations of Au, Ce and La with average values of 314.85ppm, 19081ppm and 11808ppm respectively for gold, cerium and lanthanum. Cerium and Lanthanum have considerably high concentrations when compared with other Rare Earth Elements (REE) analyzed. These concentrations represent interesting indices for Au and LREE mineralization’s. The geochemical dispersion of the metal elements (especially gold) reveals that high concentrations are recorded in the northern part of the prospect, close to the quartz-tourmaline vein within the quartzite. This result indicates that the Au and other metal elements probably originated from the quartz-tourmaline veins hosted by surrounding rocks. Detailed exploration work including geochemical soil sampling and geophysical survey is highly recommended in the northern part of the Gouap-Nkollo prospect, where anomalous concentrations of Au were observed, for further investigation.



[1]  Marjoribanks, R. Geological Methods in Mineral Exploration and Mining. Second Edition, Springer-Verlag Berlin Heidelberg, 2010.
[2]  Plumlee, G.S. The environmental geology of mineral deposits. In: PLUMLEE, G.S. & M.J. LOGSDON (Eds), The Environmental Geochemistry of Mineral Deposits, Part A. Processes,Techniques, and Health Issues, Society of Economic Geologists, Reviews in Economic Geology, 6A, 71-116, 1999.
[3]  Atsuyuki, O., Noboru, I., Shigeru, T., Yoshiko, T., 2005. Influence of surface geology and mineral deposits on the spatial distributions of element concentrations in the stream sediments of Hokkaido Japan. Journal of Geochemical Exploration, 86, 86-103, 2005.
[4]  Robb, L. Introduction to ore-forming processes. Blackwell Publishing, ISBN 0-632-06378-5 p373 pp., 2005.
[5]  Baume,r A., and Fraser, R.B. Panguna porphyry copper deposit, Papua New Guinea. In: CLKnight (ed) Economic geology of Australia and Papua New Guinea I – Metals. Australasian Institute of Mining and Metallurgy, Melbourne, 855-866, 1975.
Show More References
[6]  Embui, V.F., Omang, B. O., Che, V. B., Nforba, M.T. 4, Suh C. E. Gold grade variation and stream sediment geochemistry of the Vaimba-Lidi drainage system, northern Cameroon (West Africa). Natural Science, (5)2A, 282-290, 2013.
[7]  Suh, C.E., Lehmann, B. and Mafany, G.T. Geology and geochemical aspects of lode gold mineralization at Dimako—Mboscorro, SE Cameroon. Geochemistry: Exploration, Environment, Analysis, 6, 295-309, 2006.
[8]  King, R.W. Geochemical characteristics of tourmaline from superior province Archaean lode-gold deposits: implications for source regions and processes. In: Bicentennial Gold ‘88. Geological Society Australia Abstract Series, 2, 445-447, 1988.
[9]  Dommanget, A., Milési, J.P. and Diallo, M. The Loulo gold and tourmaline-bearing deposit: A polymorph type in the Early Proterozoic of Mali (West Africa). Mineralium Deposita 28, 253-263, 1993.
[10]  Anglin, C.D., Jonasson, I.R. and Franklin, J.M. 1996. Sm–Nd dating of scheelite and tourmaline: implications for the genesis of Archean gold deposits, Val d’Or, Canada. Economic Geoogy, 91, 1372-1382, 1996.
[11]  Deksissa, D.J., and Koeberl, C. Geochemistry and petrography of gold-quartz-tourmaline veins of the Okote area, southern Ethiopia: implications for gold exploration. Mineralogy and Petrology, 75, 101-122, 2002.
[12]  Baksheev, I.A., Prokof’ev, V.Y., Yapaskurt, V.O., Vigasina, M.F., Zorina, L.D. and Solov’ev, V.N. Ferric-iron-rich tourmaline from the Darasun gold deposit, Transbaikalia, Russia. Canadian Mineralogist, 49, 263-276, 2011.
[13]  Tornos, F., Wiedenbeck M., and Velasco, F. The boron isotope geochemistry of tourmaline-rich alteration in the IOCG systems of northern Chile: implications for a magmatic-hydrothermal origin. Mineralium Deposita 47, 483-499, 2012.
[14]  Feybesse, J.L., Johan, V., Maurizot, P. and Abessolo, A. Evolution tectono métamorphique libérienne et éburnéenne de la partie NW du Craton Zaïrois (SW Cameroun). In G. Matheis and H. Schandelmeier (Editors), Current research in African Earth Sciences. Balkema, Rotterdam, 9-12, 1987.
[15]  Toteu, S.M., Van Schmus, W.R., Penaye, J., and Nyobé, J.B. U-Pb and Sm-Nd evidence of eburnean and pan African high grade metamorphism in Cratonic rock of southern Cameroon. Precambrian Research, 67, 321-347, 1994.
[16]  Van Schmus, W.R., Toteu, S.F. Were the Congo craton and the Sào Francisco craton joined during the fusion of Gondwanaland? Eostrans , 73(14), Spring Meeting, Supplement p. 365, 1992.
[17]  Penaye, J., Toteu, S.F., Michard, A., Van Schmus, W.R. and Nzenti, J.P. U/Pb and Sm/Nd preliminary geochronologic data on the Yaoundé series, Cameroon: reinterpretation of granulitic rock as the suture of the collision in the « Centrafricain » belt. Comptes Rendus de l’Académie des Sciences, Paris, 317, 789-794, 1993.
[18]  Lerouge, C., Cocherie, A., Toteu, S.F., Penaye, J., Milesi, J.P., Tchameni, R., Nsifa, N.E., Fanning, C.M. and Deloule, E. SHRIMP U/Pb zircon age evidence for paleoproterozoic sedimentation and 2.05Ga syntectonic plutonism in the Nyong Group, South-western Cameroon: consequences for the eburnean-transamazonian belt of NE Brasil and central Africa. Journal of African Earth Sciences, 44, 413-427, 2006.
[19]  Lasserre, M., Soba, D. Age Libérien des granodiorites et des gneiss à pyroxènes du Cameroun Méridional. Bulletin BRGM 2(4), 17-32, 1976.
[20]  Maurizot, P., Abessolo, A, Feybesse, J.L., Johan V. and Lecomte P. Etude et prospection minière du Sud-Ouest Cameroun. Synthèse des travaux de 1978 à 1985. Rapport BRGM, Orléans 85, CMR 066, 274 pp, 1986.
[21]  Sikaping, S. Métamorphisme et minéralisations associées dans le secteur de Gouap-Nkollo (Région du Sud). Unpublished Master thesis, University of Yaoundé 1, 77p., 2012.
[22]  Soh Tamehe, L. Roches à tourmaline et prospection alluvionnaire de l’or à Nkollo (Région du Sud Cameroun). Unpublished Master thesis, University of Yaoundé 1, 82p., 2013.
[23]  Ganno, S. Gouap prospect: iron and gold mineralization potentials. Technical report, pp15, 2012.
[24]  Hoffman, E.L., Clark, J.R. and Yeager, J.R. Gold Analysis – Fire Assaying and Alternative Methods. Exploration and Mining Geology, 7(1, 2), 155-160, 1998.
[25]  Basham, I.R. and T.K. Smith. On the occurrence of an unusual form of monazite in panned stream sediments in Wales. Geology Journal, 18, 121-127, 1983.
Show Less References


Optimisation of Dump Slope Geometry Vis-à-vis Flyash Utilisation Using Numerical Simulation

1Department of Earth Sciences, Indian Institute of Technology Bombay, Mumbai, India

2Mine Fire Division, CSIR-Central Institute of Mine and Fuel Research, Dhanbad, India

American Journal of Mining and Metallurgy. 2014, 2(1), 1-7
DOI: 10.12691/ajmm-2-1-1
Copyright © 2014 Science and Education Publishing

Cite this paper:
S.P. Pradhan, V. Vishal, T. N. Singh, V.K. Singh. Optimisation of Dump Slope Geometry Vis-à-vis Flyash Utilisation Using Numerical Simulation. American Journal of Mining and Metallurgy. 2014; 2(1):1-7. doi: 10.12691/ajmm-2-1-1.

Correspondence to: S.P.  Pradhan, Department of Earth Sciences, Indian Institute of Technology Bombay, Mumbai, India. Email:


Stability of waste dump is now gaining importance due to increasing depth and size of mine. Management of dump nearby mining areas is one of the most critical and crucial task for mine management due to limited land and other governing laws related to environment and forest conservation. In this paper, a study was conducted to establish the effect of slope angle on the stability of waste dump for accommodation of flyash is carried out. Based on numerical simulation, it was found that the dump slope of 60 m height with 36° slope can be critically stable with 20% flyash randomly mixed with overburden materials whereas flatter slopes provide higher factor of safety. Keeping other parameters constant, the optimum slope of 32° is the best possible to accommodate the mine dump for its long term stability. These findings were further supported by study of maximum velocity vectors and shear strain rates in every case and the extent of damage zone due to tensile pull. It is hoped that this technical note will find utility wherever a design of dump of chosen material type is being planned where the wastes can be managed alongside ulitisation of flyash.



[1]  Bishop, A W, The stability of tips and soil heaps. Quarterly Journal of Engineering Geology & Hydrogeology, Vol. 6, Nos. 3 & 4, 1973, pp. 335-376.
[2]  Chang, Y L and Huang, T K, Slope stability analysis using strength reduction technique. Journal of the Chinese Institute of Engineers, Vol. 28, No. 2, 2005, pp. 231-240.
[3]  Cundall, P, Explicit finite difference methods in geomechanics. In Numerical Methods in Engineering, Proceedings of the International Conference on Numerical Methods in Geomechanics, Blacksburg, Vol. 1, 1976, pp. 132-150.
[4]  Dawson, E M, Roth, W H and Drescher, A, Slope stability analysis by strength reduction. Géotechnique, Vol. 49, No. 6, 1999, pp. 835-840.
[5]  Girard, J M and McHugh, E, Detecting problems with mine slope stability. In: 31st Annual Institute on Mining Health, Safety, and Research, Roanoke, VA, 2000.
Show More References
[6]  Han, J and Leshchinsky, D, Limit equilibrium and continuum mechanics based numerical methods for analyzing stability of MSE walls. Proceedings of the 17th Engineering Mechanics Conference, ASCE, 2004.
[7]  Hebil, K E, Spoil pile stabilization at the Paintearth mine, Forestburg, Alberta. International Symposium on Geotechnical Stability in surface mining, Calgary, Canada, Vol. 181, 1986, pp. 8.
[8]  ISRM, Commission on Standardization of Laboratory and Field Tests, Suggested methods for the quantitative description of discontinuities in rock masses. International Journal of Rock Mechanics and Mining Science & Geomechanical Abstracts, Vol. 15, 1978, pp. 319-368.
[9]  ISRM, Rock Characterization Testing and Monitoring. ISRM Suggested Methods, International Society for Rock Mechanics, Pergamon Press, 1981, pp. 211.
[10]  Itasca, FLAC/SLOPE Users’ Guide. Itasca Consulting Group, Command Reference, FISH and Theory and Background, Minneapolis, 1995.
[11]  Janbu, N, Discussion of dimensionless parameters for homogeneous Earth. Journal of the Soil Mechanics and Foundations Division, ASCE, Vol. 93, No. SM6, 1967, pp. 367-374.
[12]  Kuraz, V, Soil properties and water regime of reclaimed surface dumps in the North Bohemian brown-coal region - a field study. Waste Management, Vol. 21, 2001, pp. 147-151.
[13]  Lakshmikantha, H, Report on waste dump sites around Bangalore. Waste Management, Vol. 26, 2006, pp. 640–650.
[14]  Monjezi, M and Singh, T N, Slope Instability in an Opencast Mine. Coal International, 2000, pp. 145-147.
[15]  Pradhan, S P, Vishal, V and Singh, T N, Stability of slope in an open cast mine in Jharia coalfield, India -A Slope Mass Rating approach. Mining Engineers’ Journal, Vol. 12 No. 10, 2011, pp. 36-40.
[16]  Pradhan, S P, Vishal, V and Singh, T N, Influence of bio-stabilisation on dump slopes-A discrete element modeling approach. 47th US Rock Mechanics / Geomechanics Symposium, San Francisco, USA. 2013, ARMA-736.
[17]  Rai, R and Singh, T N, Cost benefit and its environmental impact in mining. Journal of Industrial Pollution Control, 20, No. 1, 2004, pp. 17-24.
[18]  Sarkar, K, Vishal, V and Singh, T N, 2012. An empirical correlation of index geomechanical parameters with the compressional wave velocity. Geotechnical and Geological Engineering.
[19]  Singh, T N and Chaulya, S K, External dumping of overburden in open cast mine. Indian Journal of Engineers, Vol. 22, Nos. 1 & 2, 1992, pp. 65-73.
[20]  Singh, T N and Monjezi, M, Slope Stability Study in Jointed Rockmass - A Numerical Approach. Mining Engineering Journal, Vol. 1, No. 10, 2000, pp. 12-13.
[21]  Singh, T N, Chaulya, S K and Singh, J, Effect of mine waste disposal on environment and its protection. Eurock 93, Lisbon, Portugal, 1993, pp. 283-391.
[22]  Singh, T N, Pradhan, S P and Vishal, V, Stability of slopes in a fire-prone mine in Jharia Coalfield, India. Arabian Journal of Geosciences, Vol. 6, No. 2, 2013, pp. 419-427.
[23]  Swati, M and Joseph, K, Settlement analysis of fresh and partially stabilised municipal solid waste in simulated controlled dumps and bioreactor landfills. Waste Management, Vol. 28, 2008, pp. 1355-1363.
[24]  Turer, D and Turer, A, A simplified approach for slope stability analysis of uncontrolled waste dumps. Waste Management and Research, Vol. 29, 2011, pp. 146-156.
[25]  Vishal, V, Pradhan, S P and Singh, T N, Instability assessment of mine slope-A Finite Element Approach. International Journal of Earth Sciences and Engineering, Vol. 3, 2010, pp. 11-23.
[26]  Vishal, V, Pradhan, S P and Singh, T N, Mine sustainable development vis-a-vis dump stability for a large open cast mine. Proceedings of International Conference on Earth Sciences and Engineering, 2010, pp. 7-14.
[27]  Vishal, V, Pradhan, S P and Singh, T N, Tensile strength of rock under elevated temperature. Geotechnical and Geological Engineering Vol. 29, 2011, pp. 1127-1133.
[28]  Watters, R J, Influence of internal water and material properties on mine dump stability. Geological Society of America Abstracts with Programs, Vol. 37, No. 7, 2005, pp. 394.
Show Less References