Sample Paper - Manuscript Preparation 12 J. mt. area res., Vol. 6, 2021 Journal of Mountain Area Research 3D MODELING AND PRODUCTION SCHEDULING OF KHEWRA SALT MINES Azghar Iqbal* Pakistan Mineral Development Corporation ABSTRACT In this study, AutoCAD based 3D Modelling of production scheduling, visualization of mining, and geological features in Khewra Salt Mines are showing. Unmanned Aerial Vehicle (UAV), photogrammetry and GIS Softwares are used to generate 3D surface modelling of Khewra Salt Mining Area. Khewra Salt Mines is the oldest and largest mine of sub-continent in the Salt Range with huge salt reserves from industrial quality to piece grade. Being a state-of-the-art mine consisting of 17 levels, 70 chambers with hundreds of tunnels, a layman pattern of development and manual mining procedure is followed with handy-made planes and maps. Hundreds of levels and cross- section maps were unified to a single 3D Model, presenting all mining features like tunnels, chambers, levels, inclines, and geological deposition of different salt seams with their thickness and qualities, overburden, and surface feature. The quantity of salt excavated since the beginning of mining is calculated for corroboration, and the remaining amounts of different qualities of salt are determined from the model. 3D topographic Modelling can also be used for area, volume calculations, and planning of remedial actions for rainwater inundations inside the mine. KEYWORDS: 3D Modelling, UAV, Photogrammetry, GIS, Salt Range *Corresponding author: (Email: Azghar728@hotmail.com), Phone: (+92-333-9714728) 1. INTRODUCTION Khewra Salt Mines, operating by Pakistan Mineral Development Corporation, is the oldest in the subcontinent in the mineral-rich mountain range called the Salt Range [1], as shown in figure 1. The lithology of this region belongs to the Pre-Cambrian age, comprising of Sahwal Marl Member, Bhandar Kas Gypsum Member, and Billianwala Salt Member [2]. The Sahwal Marl Member's lithology consists of bright and red marl beds with asymmetrical gypsum, 3-100 meter thick beds of dolomite, dull red marl beds with some salt layers, and gypsum 10 meters thick above the top. The Bhandar Kas Gypsum Member is made up of massive gypsum with few clay and dolomite beds (approximately 80 m). Similarly, red marl with a ferruginous content and thick layers of salt (approx. 650 m) comprises the Billianwala Salt Member [3]. The leased area covers 2789.29 acres of land [4]. Salt occurs in the form of an irregular dome-like structure. There are seven thick beautiful alternate bands of red and white color salt seams with a cumulative thickness of about 150 Full length article Vol. 6, 2021 http://journal.kiu.edu.pk/index.php/JMAR Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 13 J. mt. area res., Vol. 6, 2021 meters . At places, rock salt is 99% pure. Salt is transparent, white, pink, reddish to beef-color red [5]. In specific horizons, it is crystalline. Estimated reserves of salt range from 82 - 600 million tons [6]. Khewra salt mines produce approximately 400,000 tonnes of salt per annum [7] through the room and pillar mining method, mining only half of the salt and leaving the remaining half to support tunnel and chamber roofs. The main tunnel extends about 730 meters (2550 ft.) into the mountains from the tunnel mouth [8]. The accumulative length of tunnels is about 40 km covering 144 sq. km, with a total depth of 748 feet [4]. Based on the available survey data and geological knowledge, resource estimates have been made. Iftikhar A. Malik first measured the salt resources of the entire leased Khewra Main Mine area, as given in table 1 [9]. Asrarullah in his Report measured salt reserves by considering each salt seam separately in each chamber [10]. Table 2 describes his reserves calculations up to Chamber-62 and the pillars in between. Seven different qualities and color salt seams exist at different levels in Khewra Main Mine, namely South Pharwala, Middle Pharwala (Upper Pharwala), North Pharwala, Thin Seams, Sujjowal, Buggy, and NLLT as sown in figure 2. The salt seams strike N-E and the dip varies from 10 ° to more than 70 ° and usually dips northward [9]. Mining begins with drilling inclined holes 3 or 4 ft (1.21 m) in length and 50- 58 mm in diameter holes with auger drills. The gun powder charged with cape and fuse is used in the blasting method for initiation purposes [11]. Main Mine is made up of 17 stages. Five levels are higher than ground level, and 11 levels are lower than ground level. The height of each level is 7.62 m, according to available data from 17 levels of the main mine. Rock salt is being extracted through room and pillar mining technique in which 35 to 50 feet width of each room and 35 to 50 feet width of each pillar is developed during exploitation of rock salt and upto 70 chambers are developed in different levels. Out of 90 functioning chambers, 55 are industrial grade salt chambers and 35 are food grade salt chambers. Out of 10 inclines namely Inclines number 02, 22, 23, 26, 28, 38, 40, 43, 47, 52 only 04 inclines are safe and operational [4]. The 3D digitalization of resources using different software makes it easy of understanding the underground geological and mining features [12]. The surface modeling generation through different techniques like UAV and GIS [13] are being used for optimized production scheduling [14]. Similarly, rehabilitation and reopening of abandoned underground mines can be done using a 3D digital mine inventory model [15]. Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 14 J. mt. area res., Vol. 6, 2021 Figure 1: Geological and location map shows Salt Range from River Jhelum to River Indus (modifiied after Ghazi and Mountney, 2009). Table 1: Rock salt resources of Main Mine in a million tons (Salt Resources of Khewra Salt Mines by Iftikhar A. Malik, PMDC, 2001). Mine Measured Indicated Inferred Total Main Mine 264.428 128.137 3144.920 3537.485 Table 2: Rock salt reserves of Khewra Main Mine leased area (Report on the Khewra Mines by Mr. Asrarullah, 1962). Lease No Area (acres) Available as Pillars (MMT) Probable reserves (MMT) Proven reserves (MMT) M.L- JLM-R-SALT (1), Khewra Main Mine 2789.2 49.361 3.464 37.324 Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 15 J. mt. area res., Vol. 6, 2021 Figure 2: Columnar section of salt seams in Khewra Main Mine (Prepared by site management in 1971). 2. OBJECTIVES The objective of the research study is to digitalize the resources through AutoCAD software, develop geological Model from existing maps and generate 3D object file of Khewra Salt Mining area using Unmanned Aerial Vehicle (UAV), photogrammetry and GIS Software for production scheduling as per market demands. 3. COLLECTION OF DATA Maps of levels, the cross-section of chambers, and inclines were collected from the site to gather required features like the height of chambers and working, tunnels, seams, deposition and dipping, level, and surfaces drawn on it are shown in figure 3. Tunnels of Khewra Salt Mines are driven in the West- East direction while chambers are driven in the North-South direction. All these features are shown by their center line in the chambers of the respective cross-section. The extension of chambers in the North-South direction has been divided into blocks of 100 meter having 0 meters Northing in the extreme South of the Mines that increases gradually towards the north. 4. DIGITIZATION OF 2D MAPS AND CONVERSION INTO 3D Cross-sections (E-A and 1-65) scanned and then imported in AutoCAD for digitization. Datum lines at an RL of 274.39m, Northing blocks of 100m, Tunnels in all pillars, excavations in the chambers, seams layers, inclines, and surface line were digitized as shown in figure 4. All 2D maps were converted into 3D in SE Coordinates by the following steps and shown in figure 5. i. Datum lines, level lines, and Northing blocks lines remained unchanged in 3D. ii. In the first 42 chambers (E-A and 1-37), the excavations and openings were Extruded/lofted on both sides of the centerline to 5.334m to a total width of 10.668m. iii. Seams lines of the first 42 chambers (E-A and 1- 37) were also extruded/lofted to 5.334m on both sides of the centerline. iv. Inclines tunnels were lofted obliquely to a horizontal distance of 5.334m on both sides of the centerline of the incline in every chamber. v. Surface lines of the first 42 chambers were also lofted in the same way. vi. In the remaining 28 (38-65) chambers of 15.24m, the centerline of chambers, tunnels, seams, and surfaces were extruded to 7.62m on both sides of the centerline to a total of 15.24m. vii. Inclines tunnels in the remaining chambers were also lofted obliquely to a horizontal distance of 7.62m on both sides of the centerline in each chamber. Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 16 J. mt. area res., Vol. 6, 2021 Figure 3: Previous hand compiled cross-section of Chamber 22. Figure 4: Digitized Cross-section of Chamber # 22. Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 17 J. mt. area res., Vol. 6, 2021 Figure 5: 3D Cross section of Chamber # 2. 5. GENERATION OF 3D MODEL All cross-sections of chambers converted into 3D were placed one by one on the baseline started from chamber E up to last chamber 65. in the lost step, in 3D converted cross-section all features were extended to the next adjacent cross- section feature. A substantial giant 3D Model was resulted in having all underground and surface features at one point, as shown in figures 6, 7, 8 & 9. A different color differentiated these features for easy understanding. Figure 6: 3D Model of first seven chambers showing all feature of salt chambers. Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 18 J. mt. area res., Vol. 6, 2021 Figure 7: 3D Model showing Salt seams and surface of first seven chambers. Figure 8: Top view of tunnels network in Khewra Salt Mines. Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 19 J. mt. area res., Vol. 6, 2021 Figure 9: Oblique view of Inclines in Khewra Salt Mines. 6. CORROBORATION OF THE MODEL 3D Model generated was corroborated with the production history of the mine. The record shows a total of 21.299 million MTs production. The tonnage calculation from the 3D Model volume is 18.646 million MTs. The remaining difference is of the salt excavated from other adjacent leases like Khura, Sohal, New Mines, and Makrach, etc. 7. 3D TOPHOGRAPHIC MODELLING 3D Surface Model and topographic Modelling of Khewra Salt Mines are generated using Unmanned Aerial Vehicle (Drone), photogrammetry, and GIS software as shown in figures 10 and 11. The ODM quality report Dataset Summary provides information of the area covered, processing time, reconstructed images, detected and reconstructed features, Average Ground Sampling Distance (GSD), reconstructed points, reconstructed components, and Geographic reference as given in figure 12. Orthophoto and Digital Surface Model generated is shown in figure 13, Feature and reconstructions details are shown in figure 14, Survey Data and Geographic reference details are shown in figure 15 while track details are shown in figure 16. Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 20 J. mt. area res., Vol. 6, 2021 Figure 10: 3D Surface Model of Khewra Salt Mines generated using Unmanned Aerial Vehicle (Drone), photogrammetry and GIS softwares. Figure 11: 3D Topographic Model of Khewra Salt Mines generated using Unmanned Aerial Vehicle (Drone), photogrammetry and GIS softwares. Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 21 J. mt. area res., Vol. 6, 2021 Figure 12: ODM Quality Report Dataset Summary Processed with ODM version 2.4.1. Figure 13: Orthophoto and Digital Surface Model generated. Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 22 J. mt. area res., Vol. 6, 2021 Figure 14: Feature and Reconstruction details of the Digital Surface Model generated. Figure 15: Survey Data and Geographic reference details of the Digital Surface Model generated. Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 23 J. mt. area res., Vol. 6, 2021 Figure 16: Track details of Unmanned Aerial Vehicle (UAV) for generating 3D Surface Model. CONCLUSION i. 3D Modeling of underground room and pillar mining operations and salt seems in CAD provides a computerized mineral inventory of raw material. ii. Mineral inventory of salt of various grades are maintained and updated as a CAD and GIS file. iii. Production schedules for various working faces are prepared for planning and monitoring of weekly, monthly and annual progress. iv. 3D Surface/topographic Modelling can be used for maintenance and monitoring of changes in surface topography. v. 3D topographic Modelling can also be used for area, volume calculations, and planning of remedial actions for rainwater inundations inside the mine. vi. Different salt seams thickness, quality, and dipping are visualized for development and future mining. REFERENCES [1] E. R. Gee, "The age of the Saline Series of the Punjab and of Kohat.," in Proceedings of National Academy of Science, 1965. [2] S. J. SAMEENI, "The Salt Range: Pakistan's unique field museum of geology and paleontology," in Notebooks on Geology, 2009, pp. 65-68. [3] Asrarullah, "P. Geology of the Khewra Dome," in 18th and 19th combined session of All Pakistan Science Conference Part III, Hyderabad, 1967. [4] C. S. P. Iftikhar Ahmad, Interviewee, Leased Area of Khewra Salt Mines. [Interview]. 2018. [5] PMDC, "Pakistan Mineral Development Corporation Ministry of Energy (Petroleum Division), Government of Pakistan," 18 12 2019. [Online]. Available: http://www.pmdc.gov.pk/?p=KhewraSaltMi nes. [6] W. Dickinson, "Salt Products in North America and Outlook for the Future," in Sixth International Symposium on Salt, vol-2, 1983. [7] D. Ateeq-ur-Rehman, " A report on Salt production of Pakistan," 2015. [Online]. [8] P. Arfan Shah (DGM Salt, Interviewee, Production of Khewra Salt Mines. [Interview]. 2018. [9] I. A. Malik, "Salt Resources of Khewra Salt Mines," 2001. [10] Asrarullah, "Khewra Salt Mine," 1962. [11] Y. Majeed, M. Z. Emad, G. Rehman & M. Arshad, "Block Extraction of Himalayan Rock Salt by Applying Conventional Dimension Stone Quarrying Techniques," Journal of Mining Science , p. 15, 2019. [12] M. N. &. Z. S. Kirgizbaeva, "Use of geographic information systems at creation three- dimensional models of mine object," 2015. [13] G. Caumon, P. Collon-Drouaillet, C. L. C. de Veslud, Sophie Viseur, J. Sausse, "Surface- Azghar Iqbal, J. mt. area res. 06 (2021) 12-24 24 J. mt. area res., Vol. 6, 2021 Based 3D Modeling of Geological Structures," 2009. [14] Jitesh Gangawat, "Optimization Of Production Planning In Underground Mining," 2014. [15] T. Makkonen, R. Heikkilä, J. Jylänki, S. Fraser, "Reopening an Abandoned Underground Mine 3D Digital Mine Inventory Model from Historical Data and Rapid Laser Scanning,," 2019. [16] P. M. D. Corporation, "Pakistan Mineral Development Corporation Ministry of Energy (Petroleum Division), Government of Pakistan," 18 12 2019. [Online]. Available: http://www.pmdc.gov.pk/?p=KhewraSaltMi nes. This work is licensed under a Creative Commons Attribution 4.0 International License. Received: 05 April 2021. Revised/Accepted: 18 July 2021. http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/