Sains Malaysiana 52(8)(2023): 2267-2286

http://doi.org/10.17576/jsm-2023-5208-08

Exploring Strategies Post- Revocation of Licensing Exemption for Malaysia's Tailing Processing Industry

(Meneroka Strategi Selepas Pembatalan Pengecualian Pelesenan untuk Industri Pemprosesan Amang Malaysia)

MUHAMMAD ABDULLAH RAHMAT¹, AZNAN FAZLI ISMAIL^1,2,*, ELI SYAFIQAH AZIMAN ¹, NURSYAMIMI DIYANA RODZI^1, RATNA SUFFHIYANNI OMAR^1,2, WAN MOHD RAZI IDRIS^3,4 & TUKIMAT LIHAN⁴

¹Nuclear Science Programme, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

²Nuclear Technology Research Centre, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

³Water Analysis Research Centre (ALIR), Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

⁴Department of Earth Sciences and Environment, Faculty of Science and Technology,

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

Diserahkan: 12 April 2023/Diterima: 18 Julai 2023

Abstract

The extraction of heavy metals and rare-earth elements from tailing residue has caused a significant impact towards the environment as well as the industrial workers as a result from the contamination caused by the processing activities. The radionclide concentration of ²²⁶Ra, ²³²Th, and ⁴⁰K in soil and tailing residue were found to be within the range of 0.31 - 4.97 Bqg^-1 and 1.24 - 4.47 Bqg^-1, 0.16 - 11.07 Bqg^-1 and 1.08 - 8.56 Bqg^-1, 0.22 - 1.24 and 0.18 - 1.32 Bqg^-1, respectively. The radiological impack assessment findings indicated significant overexposure risks where the annual effective dose was estimated to be within the range of  0.7 – 207.6 mSvy^-1 while the excess lifetime cancer risks we found to have exceeded the limit let by the local regulatory body. The correlation between study findings and the enactment of the licensing exemption order was done to identify the effects of non-regulatory compliance to the Atomic Energy Licensing Act. The study also emphasized on the remediation importance of industrial sites before implementing any form of changes towards new regulatory adherence. Hence, the study recommeneds potential remediation techniques but taking into account the operational status of each proceesing plant, degree of contation and possible future use of the contaminated site.

Keywords: Legislative improvement; NORM; Radiological Impact Assessment; tailing processing; waste management

Abstrak

Pengekstrakan logam berat dan nadir bumi daripada sisa amang telah memberi impak yang ketara terhadap alam sekitar dan juga pekerja industri akibat pencemaran yang berlaku di lokasi yang melibatkan aktiviti pemprosesan. Kandungan kepekatan radionuklid ²²⁶Ra, ²³²Th dan ⁴⁰K dalam tanah dan sisa amang masing-masing berada dalam julat antara 0.31 - 4.97 Bqg^-1 dan 1.24 - 4.47 Bqg^-1, 0.16 - 11.07 Bqg^-1 dan 1.08 - 8.56 Bqg^-1, 0.22 - 1.24 dan 0.18 - 1.32 Bqg^-1. Hasil penilaian impak radiologi menunjukkan risiko pendedahan berlebihan yang ketara dengan nilai dos berkesan tahunan berada dalam julat 0.7 - 207.6 mSvthn^-1serta risiko kanser sepanjang hayat didapati melebihi had yang ditetapkan oleh pihak berkuasa tempatan. Hasil kajian ini seterusnya dikaitkan dengan perintah pengecualian pelesenan bagi mengenal pasti kesan akibat ketidakpatuhan terhadap Akta Perlesenan Tenaga Atom. Kajian turut menekankan kepentingan tindakan pemulihan kawasan industri sebelum membuat sebarang perubahan bagi mematuhi akta perlesenan yang baharu. Oleh itu, kajian ini mencadangkan langkah pemulihan dengan mengambil kira status pengoperasian setiap kilang, tahap pencemaran dan juga kebarangkalian penggunaan semula kawasan tercemar.

Kata kunci: NORM; pemprosesan amang; penambahbaikan undang-undang;  pengawalan sisa; Penilaian Impak Radiologi

RUJUKAN

Abdel-Razek, Y.A., Desouky, O.A., Elshenawy, A., Nasr, A.S., Mohammed, H.S. & Elsayed, A.A. 2016. Assessment of the radiation exposures during separation of rare earth elements from monazite mineral. International Journal of Advanced Research 4(4): 144-149. doi:10.21474/IJAR01

AELB. 2010. Atomic Energy Licensing Act 1984, (Basic Safety Radiation Protection) Regulation 2010. Atomic Energy Licensing Act 1984.

AELB. 1994. Perintah Perlesenan Tenaga Atom (Kilang Amang Kecil) (Pengecualian) 1994. Akta Perlesenan Tenaga Atom 1984.

Ahmad Fauzan, Y., Jasmi Hafiz, A.A. & Muhammad Hatta, R. 2022. Mineralogy and geochemistry of gold mineralization at Southern Part of Ulu Sokor Gold Deposit, Kelantan, Malaysia. Sains Malaysiana 51(12): 3865-3877. doi:10.17576/jsm-2022-5112-01

Ahmad Tajudin, S.A., Mohammad Azmi, M.A. & Ain Nabila. 2016. Stabilization/solidification remediation method for contaminated soil: A review. IOP Conference Series: Materials Science and Engineering 136(1): 012043. doi:10.1088/1757-899X/136/1/012043

Ahmad, Z.Y. & Jeyanny, V. 2018. Phytoremediation of heavy metals using Acacia mangium in Rahman Hydraulic Tin (RHT) Tailings, Klian. Advances in Plants & Agriculture Research 8(3): 247-249. doi:10.15406/apar.2018.08.00322

Al-Areqi, W.M., Che Nor Aniza Che Zainul Bahri, Amran Ab. Majid & Sukiman Sarmani. 2016. Separation and radiological impact assessment of thorium in Malaysian Monazite Processing. Malaysian Journal of Analytical Sciences 20(4): 770-776.  doi:10.17576/mjas-2016-2004-09

Ali, M.M.M., Zhao, H., Li, Z. & Maglas, N.N.M. 2019. Concentrations of TENORMs in the petroleum industry and their environmental and health effects. RSC Advances 9(67): 39201-39229. doi:10.1039/c9ra06086c

Alnour, I.A., Wagiran, H., Ibrahim, N., Hamzah, S. & Elias, M.S. 2017. Determination of the elemental concentration of uranium and thorium in the products and by-products of amang tin tailings process. AIP Conference Proceedings 1799. doi:10.1063/1.4972913

Ang, L.H., Tang, L.K., Ho, W.M., Hui, T.F. & Theseira, G.W. 2010. Phytoremediation of Cd and Pb by four tropical timber species grown on an ex-tin mine in Peninsular Malaysia. World Academy of Science, Engineering and Technology 62(2): 244-248.

Aslam, S., Yousafzai, A.M. & Javed, A. 2022. Bioaccumulation of hexavalent chromium in commercially edible fish grass carp, Ctenopharyngodon idella. Sains Malaysiana 51(9): 2757-2762. doi:10.17576/jsm-2022-5109-02

Atipo, M., Olarinoye, O. & Awojoyogbe, B. 2020. Comparative analysis of NORM concentration in mineral soils and tailings from a tin-mine in Nigeria. Environmental Earth Sciences 79(16): 1-17. doi:10.1007/s12665-020-09136-7

Atipo, M., Olarinoye, O., Awojoyogbe, B. & Kolo, M. 2020. High terrestrial radiation level in an active tin-mine at Jos South, Nigeria high terrestrial radiation level in an active tin-mine at Jos South, Nigeria. Journal of Applied Sciences and Environmental Management 24(3): 435-442. doi:10.4314/jasem.v24i3.6

Azlina, M.J., Ismail, B., Samudi Yasir, M., Syed Hakimi Sakuma & Khairuddin, M.K. 2003. Radiological impact assessment of radioactive minerals of amang and ilmenite on future landuse using RESRAD computer code. Applied Radiation and Isotopes 58(3): 413-419. doi:10.1016/S0969-8043(02)00347-0

Belyaeva, O., Pyuskyulyan, K., Movsisyan, N., Saghatelyan, A. & Carvalho, F.P. 2019. Natural radioactivity in urban soils of mining centers in Armenia: Dose rate and risk assessment. Chemosphere 225: 859-870. doi:10.1016/j.chemosphere.2019.03.057

Canberra. 2000. Genie ^TM 2000 Spectroscopy Software.

Chibuike, G.U. & Obiora, S.C. 2014. Heavy metal polluted soils: Effect on plants and bioremediation methods. Applied and Environmental Soil Science 2014: Article ID. 752708. doi:10.1155/2014/752708

Conceição, F., Catuane, F., Taímo, S., Carvalho, F.P., Oliveira, J.M. & Malta, M. 2018. Radiological assessment of heavy-mineral sand exploitation in Mozambique. In Naturally Occurring Radioactive Material (NORM VIII). Proceedings of an International Symposium. pp. 244-247.

Department of Environment Malaysia. 2009a. Contaminated Land Management and Control Guidelines No. 3: Remediation of Contaminated Sites. Vol. 3.

Department of Environment Malaysia. 2009b. Contaminated Land Management and Control Guidelines No. 1: Malaysian Recommended Site Screening Levels for Contaminated Land.

Department of Environment Malaysia. 2009c. Contaminated Land Management and Control Guidelines No. 2: Assessing and Reporting Contaminated Sites. No. 2: 48.

Falciglia, P.P., Cannata, S., Romano, S. & Vagliasindi, F.G.A. 2014. Stabilisation/solidification of radionuclide polluted soils - Part I: Assessment of setting time, mechanical resistance, γ-radiation shielding and leachate γ-radiation. Journal of Geochemical Exploration 142: 104-111. doi:10.1016/j.gexplo.2014.01.016

Francis, A.J. & Nancharaiah, Y.V. 2015. In situ and ex situ bioremediation of radionuclide-contaminated soils at nuclear and norm sites. Environmental Remediation and Restoration of Contaminated Nuclear and Norm Sites. pp. 185-236. doi:10.1016/B978-1-78242-231-0.00009-0

Friedmann, H., Nuccetelli, C., Michalik, B., Anagnostakis, M., Xhixha, G., Kovler, K., de With, G., Gascó, C., Schroeyers, W., Trevisi, R., Antropov, S., Tsapalov, A., Kunze, C & Petropoulus, N.P. 2017. Measurement of NORM. In Naturally Occurring Radioactive Materials in Construction: Integrating Radiation Protection in Reuse, edited by Schroyers, W. Woodhead Publishing. pp. 61-133. doi:10.1016/B978-0-08-102009-8.00005-0

García-Tenorio, R., Sanz, E., Burkhalter, E., Manjón, G., Vioque, I. & Diaz, I. 2018. Radiological evaluation of monazite mining in central Spain. In Naturally Occurring Radioactive Material (NORM VIII). Proceedings of an International Symposium. pp. 220-224.

González Henao, S. & Ghneim-Herrera, T. 2021. Heavy metals in soils and the remediation potential of bacteria associated with the plant microbiome. Frontiers in Environmental Science 9(April): 1-17. doi:10.3389/fenvs.2021.604216

Gou, M., Zhou, L. & Then, N.W.Y. 2019. Utilization of tailings in cement and concrete: A review. Science and Engineering of Composite Materials 26(1): 449-464. doi:10.1515/secm-2019-0029

Gunawan, O., Pudjadi, E., Musbach, M. & Wahyudi. 2019. Technologically Enchanced Naturally Occurring Radioactive Materials (TENORM) analysis of Bangka Tin Slag. Journal of Physics: Conference Series 1198: 022006. doi:10.1088/1742-6596/1198/2/022006

Hewson, G.S. 1996. Overview of radiation safety in the tin by-product (amang) industry of South East Asia. Health Physics 71(2): 225-234. doi:10.1097/00004032-199608000-00016

Hinrichsen, Y., Finck, R., Martinsson, J. & Rääf, C. 2021. Maximizing avertable doses with a minimum amount of waste for remediation of land areas around typical single family houses after radioactive fallout based on Monte Carlo simulations. Scientific Reports 11(1): 1-9. doi:10.1038/s41598-021-84103-1

Hou, D. 2021. Sustainable remediation in China: Elimination, immobilization, or dilution. Environmental Science and Technology 55(23): 15572-15574. doi:10.1021/acs.est.1c06044

Hu, N., Ding, D., Li, G., Zheng, J., Li, L., Zhao, W. & Wang, Y. 2014. Vegetation composition and 226Ra uptake by native plant species at a uranium mill tailings impoundment in South China. Journal of Environmental Radioactivity 129: 100-106. doi:10.1016/j.jenvrad.2013.12.012

IAEA. 1989. Measurement of Radionuclides in Food and the Environment. A Guidebook. Technical Report No. 295. doi:10.1016/0265-931x(90)90062-z

Ibeanu, I.G.E. 2003. Tin mining and processing in Nigeria: Cause for concern? Journal of Environmental Radioactivity 64(1): 59-66. www.elsevier.com/locate/jenvrad.

Ismail, B., Teng, I.L. & Muhammad Samudi, Y. 2011. Relative radiological risks derived from different TENORM wastes in Malaysia. Radiation Protection Dosimetry 147(4): 600-607. doi:10.1093/rpd/ncq577

Ismail, B., Yasir, M.S., Redzuwan, Y. & Amran, A.M. 2003. Radiological environment risk associated with different water system in amang factory. Pakistan Journal of Biological Science 6(17): 1544-1547.

Jumaat, A.H. & Ab Hamid, S. 2023. Monitoring heavy metal bioaccumulation in rivers using damselflies (Insecta: Odonata, Zygoptera) as biological indicator. Sains Malaysiana 52(2): 321-331. doi:10.17576/jsm-2023-5202-01

Khalid, S., Shahid, M., Niazi, N.K., Murtaza, B., Bibi, I. & Dumat, C. 2017. A comparison of technologies for remediation of heavy metal contaminated soils. Journal of Geochemical Exploration 182: 247-268. doi:10.1016/j.gexplo.2016.11.021

Kolo, M.T., Siti Aishah Binti Abdul Aziz, Khandaker, M.U., Asaduzzaman, K. & Mohd Amin, Y. 2015. Evaluation of radiological risks due to natural radioactivity around Lynas Advanced Material Plant environment, Kuantan, Pahang, Malaysia. Environmental Science and Pollution 22(17): 13127-13136. doi:10.1007/s11356-015-4577-5

Kontol, K.M., Ahmad, S.H.S.S. & Omar, M. 2007. Radiological Impact Assessment for Landfill Disposal of NORM Wastes in Malaysia. IAEA.

Lal, A. & Fronczyk, J. 2022. Does current knowledge give a variety of possibilities for the stabilization/solidification of soil contaminated with heavy metals? - A review. Materials 15(23): 8491. doi:10.3390/ma15238491

Lee, S.K., Husin Wagiran, Ahmad Termizi Ramli, Nursama Heru Apriantoro & A. Khalik Wood. 2009. Radiological monitoring: Terrestrial natural radionuclides in Kinta District, Perak, Malaysia. Journal of Environmental Radioactivity 100(5): 368-374. doi:10.1016/j.jenvrad.2009.01.001

Li, B., Wang, N., Wan, J., Xiong, S., Liu, H., Li, S. & Zhao, R. 2016. In-situ gamma-ray survey of rare-earth tailings dams - A case study in Baotou and Bayan Obo Districts, China. Journal of Environmental Radioactivity 151: 304-310. doi:10.1016/j.jenvrad.2015.10.027

Liu, H. & Pan, Z. 2012. NORM situation in non-uranium mining in China. Annals of the ICRP 41(3-4): 343-351. doi:10.1016/j.icrp.2012.06.015

Lloyd, J.R. & Renshaw, J.C. 2005. Bioremediation of radioactive waste: radionuclide - microbe interactions in laboratory and field-scale studies. Current Opinion in Biotechnology 16(3): 254-260. doi:10.1016/j.copbio.2005.04.012

Lorenzo-González, M., Ruano-Ravina, A., Torres-Durán, M., Kelsey, K.T., Provencio, M., Parente-Lamelas, I., Leiro-Fernández, V., Vidal-García, I., Castro-Añón, O., Martínez, C., Golpe-Gómez, A., Zapata-Cachafeiro, M., Piñeiro-Lamas, M., Pérez-Ríos, M., Abal-Arca, J., Montero-Martínez, C., Fernández-Villar, A. & Barros-Dios, J.M. 2019. Lung cancer and residential radon in never-smokers: A pooling study in the northwest of Spain. Environmental Research 172: 713-718. doi:10.1016/j.envres.2019.03.011

Lourenço, J., Mendo, S. & Pereira, R. 2019. Rehabilitation of radioactively contaminated soil: Use of bioremediation/phytoremediation techniques. In Remediation Measures for Radioactively Contaminated Areas, edited by  Gupta, D. & Voronina, A. Springer: Cham. doi:10.1007/978-3-319-73398-2_8

Mohideen, A.H., Thirumalai Arasu, R., Narayanan, V. & Zahir Hussain, M.I. 2010. Bioremediation of heavy metal contaminated soil by the exigobacterium and accumulation of Cd, Ni, Zn and Cu from soil environment. International Journal of Biological Technology 1(2): 94-101.

Muhammad Abdullah Rahmat, Aznan Fazli Ismail, Nursyamimi Diyana Rodzi, Eli Syafiqah Aziman, Syazwani Mohd Fadzil, Norsyahidah Mohd Hidzir, Mohd Idzat Idris, Irman Abdul Rahman & Faizal Mohamed. 2023. A window into the future: Case study of long‑term radiological risk modelling posed by unregulated mining waste repurposing activities. Environmental Monitoring and Assessment. Springer International Publishing, 1-18. doi:10.1007/s10661-023-11308-4

Muhammad Abdullah Rahmat, Aznan Fazli, Eli Syafiqah, Nursyamimi Diyana, Faizal Mohamed & Irman Abdul Rahman. 2022. The impact of unregulated industrial tin-tailing processing in Malaysia: Past, present and way forward. Resources Policy 78: 102864. doi:10.1016/j.resourpol.2022.102864

Muhammad Abdullah Rahmat, Aznan Fazli Ismail, Nursyamimi Diyana Rodzi, Eli Syafiqah Aziman, Wan Mohd Razi Idris & Tukimat Lihan. 2021. Assessment of natural radionuclides and heavy metals contamination to the environment: Case study of Malaysian unregulated tin-tailing processing industry. Nuclear Engineering and Technology 54(6): 2230-2243. doi:10.1016/j.net.2021.12.013

Muhammad Aqeel Ashraf, Mohd Jamil Maah & Ismail Yusoff. 2013. Evaluation of natural phytoremediation process occurring at ex-tin mining catchment. Chiang Mai Journal of Science 40(2): 198-213.

Nasirian, M., Ismail, B. & Abdullah, P. 2008. Assessment of natural radioactivity in water and sediment from amang (tin tailing) processing ponds. The Malaysian Journal of Analytical Sciences 12(1): 150-159.

Nurrul Assyikeen Md. Jaffary, Kok Siong Khoo, Nor Hasimah Mohamed, Mohd Abd Wahab Yusof & Syazwani Mohd Fadzil. 2019. Malaysian Monazite and its processing residue: Chemical composition and radioactivity. Journal of Radioanalytical and Nuclear Chemistry 322: 1097-1105. doi:10.1007/s10967-019-06813-1

Omar, M., Sulaiman, I., Hassan, A. & Wood, A.K. 2007. Radiation dose assessment at amang processing plants in Malaysia. Radiation Protection Dosimetry 124(4): 400-406. doi:10.1093/rpd/ncm212

Permana, S., Soedarsono, J.W., Rustandi, A., Maksum, A., Widana, K.S., Trinopiawan, K. & Anggraini, M. 2018. The enhancement of uranium and thorium in Bangka Tin Slag. Atom Indonesia 44(1): 37-42. doi:10.17146/aij.2018.529

Qi, C. & Fourie, A. 2019. Cemented paste backfill for mineral tailings management: Review and future perspectives. Minerals Engineering 144: 106025. doi:10.1016/j.mineng.2019.106025

Qureshi, A.A., Tariq, S., Ud Din, K., Manzoor, S., Calligaris, C. & Waheed, A. 2014. Evaluation of excessive lifetime cancer risk due to natural radioactivity in the rivers sediments of northern Pakistan. Journal of Radiation Research and Applied Sciences 7(4): 438-447. doi:10.1016/j.jrras.2014.07.008

Roed, J., Andersson, K.G., Barkovsky, A.N., Fogh, C.L., Mishine, A.S., Ponamarjov, A.V. & Ramzaev, V.P. 2006. Reduction of external dose in a wet-contaminated housing area in the Bryansk Region, Russia. Journal of Environmental Radioactivity 85(2-3): 265-279. doi:10.1016/j.jenvrad.2004.03.039

Roh, C., Kang, C.K. & Lloyd, J.R. 2015. Microbial bioremediation processes for radioactive waste. Korean Journal of Chemical Engineering 32(9): 1720-1726. doi:10.1007/s11814-015-0128-5

Sanusi, M.S.M., Ramli, A.T., Hashim, S. & Lee, M.H. 2021. Radiological hazard associated with amang processing industry in Peninsular Malaysia and its environmental impacts. Ecotoxicology and Environmental Safety 208: 111727. doi:10.1016/j.ecoenv.2020.111727

Schoenberger, E. 2016. Environmentally sustainable mining: The case of tailings storage facilities. Resources Policy 49: 119-128. doi:10.1016/j.resourpol.2016.04.009

Shittu Abdullahi, Aznan Fazli Ismail & Supian Samat 2019. Determination of indoor doses and excess lifetime cancer risks caused by building materials containing natural radionuclides in Malaysia. Nuclear Engineering and Technology 51(1): 325-336. doi:10.1016/j.net.2018.09.017

Shittu Abdullahi, Aznan Fazli Ismail & Muhamad Samudi Yasir. 2020. Radioactive investigation of Malaysia’s building materials containing NORM and potential radiological risks analysis using RESRAD-BUILD computer code. International Journal of Environmental Analytical Chemistry 102(9): 2000-2012. doi:10.1080/03067319.2020.1746778

Shittu Abdullahi, Aznan Fazli Ismail, Supian Samat & Muhamad Samudi Yasir. 2018. Assessment of natural radioactivity and associated radiological risks from tiles used in Kajang, Malaysia. AIP Conference Proceedings 1940. doi:10.1063/1.5027916

Solehah, A.R. & Samat, S.B. 2018. Radiological impact from natural radionuclide activity concentrations in soil and vegetables at former tin mining area and non-mining area in Peninsular Malaysia. Journal of Radioanalytical and Nuclear Chemistry 315(2): 127-136. doi:10.1007/s10967-017-5654-7

Syarbaini, Warsona, A. & Iskandar, D. 2014. Natural radioactivity in some food crops from Bangka-Belitung Islands, Indonesia. Atom Indonesia 40(1): 27-32. doi:10.17146/aij.2014.260

Thoburn, J.T. 1994. The tin industry since the collapse of the international tin agreement. Resources Policy 20(2): 125-133. doi:10.1016/0301-4207(94)90025-6

UNSCEAR. 2000. Sources and effects of ionizing radiation, United Nations Scientific Committee on the effects of atomic radiation UNSCEAR 2000 report to the General Assembly. UNSCEAR Report I: 1-556.

Vishwakarma, G.S., Bhattacharjee, G., Gohil, N. & Singh, V. 2020. Current status, challenges and future of bioremediation. Bioremediation of Pollutants. pp. 403-415. INC. doi:10.1016/B978-0-12-819025-8.00020-X

Wu, D. 2020. Traditional treatment of mine waste. In Mine Waste Management in China: Recent Development. Singapore: Springer. doi:10.1007/978-981-32-9216-1.

Yen, L.V. & Kartini, S. 2013. Phytoremediation using Typha angustifolia L. for mine water effluence treatment: Case study of ex-mamut copper mine, Ranau, Sabah. Borneo Science 33: 16-22.

Zaidan Kandar, M. & Bahari, I. 1996. Radiation-induced chromosomal aberrations among TENORM workers: Amang- and ilmenite-processing workers of Malaysia. Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis 351(2): 157-161. doi:10.1016/0027-5107(95)00174-3

Zhang, Q., Zhang, B., Chen, Q., Wang, D. & Gao, X. 2021. Safety analysis of synergetic operation of backfilling the open pit using tailings and excavating the ore deposit underground. Minerals 11(8): 818. doi:10.3390/min11080818

Zhao, X., Fourie, A. & Qi, C.C. 2020. Mechanics and safety issues in tailing-based backfill: A review. International Journal of Minerals, Metallurgy and Materials 27(9): 1165-1178. doi:10.1007/s12613-020-2004-5

Ziajahromi, S., Khanizadeh, M. & Nejadkoorki, F. 2014. Total effective dose equivalent assessment after exposure to high-level natural radiation using the RESRAD code. Environmental Monitoring and Assessment 186(3): 1907-1915. doi:10.1007/s10661-013-3504-9

*Pengarang untuk surat-menyurat; email: aznan@ukm.edu.my