{"id":4768,"date":"2023-05-16T18:00:15","date_gmt":"2023-05-16T18:00:15","guid":{"rendered":"https:\/\/northamericanmining.com\/?p=4768"},"modified":"2023-05-16T18:56:48","modified_gmt":"2023-05-16T18:56:48","slug":"planning-an-underground-transition","status":"publish","type":"post","link":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/","title":{"rendered":"PLANNING AN UNDERGROUND TRANSITION"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><em>Moving from open pit to underground operations is fraught with complications. <\/em>North American Mining<em> spoke to three experts about the considerations and risks involved.\u00a0<\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>By Jonathan Rowland<\/em><\/p>\n\n\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-4770\" src=\"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png\" alt=\"\" width=\"800\" height=\"478\" srcset=\"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png 1201w, https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348-768x458.png 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><\/p>\n\n\n<p class=\"wp-block-paragraph\">A majority of mining operations begin life as open pits; however, as mining progresses, ore reserves may be proved to extend to greater depths than originally anticipated. To continue exploiting these reserves, the pit must either be extended to access these deeper deposits, or the mine must switch to underground mining methods (or quite possibly a mix of both).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u201cTypically, the decision to transition from open pit to underground operations is an economic one based on the cost of mining \u2013 but there is no industry standard approach,\u201d Andrew Hall, director\/executive lead \u2013 Advisory at AMC Consultants, told <em>North American Mining<\/em>. \u201cSome believe that you should mine the biggest open pit you can to take advantage of potential higher production rates, as well as lower operating and capital costs. Others take a strict cost-analysis approach to determine the depth at which the transition occurs. However, the \u2018optimal\u2019 depth of an open pit lies somewhere between these two limits.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Surface-to-underground transitions are complex undertakings, agreed Peter Terbrugge, corporate consultant and expert in mining engineering at SRK, who has worked on a number of such projects. To make the transition as efficient as possible, \u201crequires extensive planning. For a large mining operation, this planning process will be measured in years, so it\u2019s important to begin as soon as possible to avoid any production gap between the end of open pit mining and the start of underground mining.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>It is never too soon to start planning&nbsp;<\/strong><br>\u201cIdeally planning for an underground transition should start at the early planning stage \u2013 conceptual to feasibility \u2013 of the project,\u201d said AMC\u2019s Hall. However, underground mining is often not on the cards at these early stages: it may only be considered an optional extension, if it is considered at all. In these cases, \u201cthe planning process is often deferred, particularly if the level of knowledge about the orebody at depth is low, or the company does not have the in-house skills to plan an underground mine.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ideally, mines should begin to plan for the possibility of an underground transition at the preliminary feasibility study (PFS) stage, agreed Joe Luxford, managing director at Luxford Mine Management Services. \u201cThe PFS may flag when the transition is likely, if at all, and identify the future drilling program needed to determine the orebody extensions below the open pit and the likely feasibility of an underground operation.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Unfortunately, mining companies still underestimate the timeframes involved in planning an underground transition. SKR\u2019s Terbrugge offered a couple of examples of large diamond mines in South Africa where planning took much longer than anticipated and left the mining companies involved scrabbling to cover production gaps.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u201cThe CEO of one mine asked if we could steepen the slopes of the pit to bridge production until the underground operation was ready,\u201d said Terbrugge. \u201cWe managed to do so with some fancy drilling and by putting additional support in the kimberlite. The operation became more expensive and it was a logistical challenge, as we had to work around development of the underground workings, but we managed to extend the pit life for the three years they were looking for.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Extending the pit is not always possible, however. Terbrugge cited the example of another major diamond mine that was left to treat low-grade leftovers of the surface operation until underground operations were ready \u2013 some three years behind schedule.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Echoing Terbrugge\u2019s experience, AMC\u2019s Hall agreed that \u201cthe timeframe for an underground transition is typically underestimated,\u201d adding that it is a particular issue when additional knowledge about the orebody is needed to support detailed designs and approvals. \u201cWhen you consider the time needed to complete the required drilling programs, test work, technical studies, approvals, construction, commissioning, and production ramp-up, a transition timeframe of five plus years is not uncommon.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">And timeframes can be much longer. Drawing on his experience, Terbrugge notes planning periods can extend beyond 15 years and up to 20 years for large mining operations. This not only raises the ore gap issue (as mentioned above), but may also impact the quality of the underground operation. According to Hall, if the transition timeframe is underestimated, \u201cshortcuts may be taken to assure production continuity. And with every shortcut comes added risk that the design is a little less optimal, compromising the longer-term future of the mine.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Establishing the transition zone limits<\/strong><br>According to AMC\u2019s Hall, when beginning to plan a transition, it is \u201cgood practice\u201d to first establish the upper and lower limits of the transition zone. \u201cThe lower limit is set by the Lerchs-Grossman ultimate pit limit: the deepest you can economically mine using open pit methods without considering an underground operation. The upper limit it set by the minimum depth you can mine using underground methods, which is typically at the base of the weather profile.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">When these limits have been determined, the Lerchs-Grossman pit \u201ccan be restricted using the opportunity cost of each block to determine the pit limit (instead of the profit), where the opportunity cost is the difference in the value of the block when mined by open pit or by underground methods,\u201d continued Hall. \u201cThe underlying assumption here is that, if a block can be mined by either method, if it is not mined in the open pit, it will be mined underground.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">These two pit depths \u2013 that of the Lerchs-Grossman pit and of the restricted pit \u2013 provide the theoretical upper and lower positions for the base of the pit. \u201cThe optimal position lies somewhere in this transition zone,\u201d concluded Hall, \u201cbut the actual \u2018sweet spot\u2019 depends on a wide range of factors, both technical and non-technical.\u201d&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><br><strong>There is never too much data<\/strong><br>The success of any surface-to-underground transition \u2013 indeed the success of any mining operation \u2013 relies on \u201cthe extent and quality of the technical data available to the project team, which will largely determine the technical and economic feasibility of any potential underground operation. This, in turn, determines the position of the transition from open pit to underground mining,\u201d said AMC\u2019s Hall.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">According to Peter Terbrugge of SRK, this data includes:&nbsp;<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Definition of the orebody \u2013 its shape and footprint, depth extent and variability, 3D geometry, and maximum potential mining depth.&nbsp;<\/li>\n\n\n\n<li>Rock mass characteristics \u2013 major geological structures, jointing in the rock mass, rock types and rock mass quality, and groundwater conditions. These will all \u201caffect the stability of any proposed underground excavations,\u201d said the SRK expert.&nbsp;<\/li>\n\n\n\n<li>Definition of boundary conditions including in situ stresses, topography, and superloading (both positive or negative), presence of groundwater, and blasting and seismicity.&nbsp;<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Obtaining such data is not easy, however. Focus should therefore be on \u201cobtaining as much geological and geotechnical information from the open pit as possible to apply to underground development and operation,\u201d said Luxford.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Exploration drilling is another main source of data. But here there are challenges. \u201cAs depth below surface increases, the density of drilling is typically lower, as costs increase and drill site availability declines due to ongoing surface mining operations,\u201d said Hall. \u201cThis means there is less drill core available for logging or samples for test work, reducing confidence in a wide range of key design parameters, including geology, mineral resource estimates, ground conditions, selection of the mining method, capital and operating costs, potential production rates, mined grade, and recovery rates.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">As a result, at the conceptual design stage, \u201cassumptions will need to be made based on existing data, much of which will be interpolated or inferred from the open pit experience,\u201d concluded the AMC expert. \u201cBut as the project matures and access to the deeper parts of the orebody improves, continued data collection is critical to reduce the risks associated with developing the project.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>On top, down below<\/strong><br>Other factors that require consideration include the interaction between the open pit and underground mining development and operations. For example, what effect will surface blasting have on the development of underground operations? Conversely, what impact might the underground workings have on pit stability? There may also be potential dilution of underground reserves from the open pit, especially after it has been abandoned, as well as health and safety issues, such as mudrushes (more on them later).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">There are also issues around infrastructure, both on the surface and underground. \u201cSurface installations, such as tailings dams, rock dumps, mineral processing plant, roads, rail lines and pipelines, should be planned to ensure they are not impacted by underground operations, while underground openings must be secure from any surface effects,\u201d explained SRK\u2019s Terbrugge. Decisions must also be made about the location and size of underground shafts, ore passes, crushers, silos, chambers, ramps and declines, pump chambers, and conveyor excavations, etc.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\">\u201cCave angles and cave crack locations will affect the location of surface infrastructure,\u201d continued Terbrugge, \u201cwhile the location of cave cracks underground will impact the location of shafts and the effect on the pit.\u201d<\/p>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">\u201cThe depth and severity of weathering will be a major consideration when locating decline portals and shaft collars, while you must also consider how ore will be handled from portal or shaft to the mineral processing plant,\u201d added Luxford. \u201cAt the same time, the size of the orebody and planned production rate from the underground workings may require significant changes to ore treatment processes, especially crushing, grinding, flotation, and filter dewatering circuits.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This latter point was also picked up by AMC\u2019s Andrew Hall. \u201cProviding appropriate feed volumes and material types (e.g., oxidation state) to a process plant that has been sized for open pit volumes is a common challenge when moving underground. This requires strategic metallurgical plant reviews to balance underground feed volumes \u2013 which are typically lower, albeit with higher grades \u2013 to achieve acceptable project economics.\u201d This could require throughput reductions (turning off a parallel stream), reduced plant utilization (campaigned milling time), or other geometallurgical considerations (increased hardness with less throughput), which may be counter-intuitive in open pit operations where unit-volume is king.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Administrative locations should also not be overlooked, as Luxford pointed out. \u201cWill the underground operations gradually take over the open pit offices, workshops, etc., as happened at Palabora in the early 2000s, or will they require new facilities?\u201d And then there are the workers. Will underground development and\/or operation be conducted by the mine company\u2019s own technical and supervisory staff or contractors \u2013 and will this raise any union issues?&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Underground mining \u2013 but how?&nbsp;<\/strong><br>Of course, decisions will also need to be made about the method of mining method. Considerations here include fragmentation, layout geometry, draw point sizes and spacing, drifts, and the location, geometry, dimensions, and support requirement of undercuts.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Meanwhile, the method of mining selected \u201ccan have a very important influence on existing mine surface and underground infrastructure,\u201d said SRK\u2019s Terbrugge. \u201cFor example, caving methods will result in the formation of cave craters, which may grow in size \u2013 and influence \u2013 as mining depth increases. Conversely, cut-and-fill and open-stoping methods preserve a stable rock mass and thus any mine infrastructure; however, should an open stope collapse, it may lead to the development of further failures in the rock mass. All of these potential behaviors should be analyzed when evaluating mining methods.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u201cAnother common challenge is the separation of open pit and underground activities during transition, especially if underground access is from within the pit environment,\u201d added AMC\u2019s Andrew Hall.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u201cTo ensure continuity of production, it is often necessary to develop the underground mine and ramp-up production concurrently with continuing open pit operations,\u201d the AMC expert continued. \u201cThis can impact performance, especially if mine access is not well planned and demarcated. Early identification and development of underground portals within the open pit may therefore ensure more efficient development of both the underground workings and the open pit. Other key interactions that need to be managed include ventilation (dust from pit, location of raises), materials handling (using the pit fleet for surface movements), ore accounting\/reconciliation\/measurement, and the impact of blast vibrations and fumes ingress.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-4771\" src=\"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/mine-7417189_1920.png\" alt=\"\" width=\"800\" height=\"565\"><\/p>\n\n\n<p class=\"wp-block-paragraph\"><strong>Health and safety&nbsp;<\/strong><br>Underground mining obviously presents different health and safety risks than open pit mining \u2013 with a range of different hazards and challenges. There are however a number of specific risks that must be considered when transitioning from surface to underground mining, or when underground workings is taking place beneath a working or abandoned open pit.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">According to SRK\u2019s Peter Terbrugge, \u201cwhen a shaft has been sunk in preparation for underground mining, but open pit operations continue beyond the originally-planned depth, deformation of the shaft may occur as a result of a relaxation of or increase in stresses caused by the deepening on the pit, and consequent encroachment of the pit rim.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The surface-to-underground transition \u201ccan also introduce the risk of mudrushes from within the rock mass \u2013 when mud-forming minerals are present \u2013 or from sumps and surface dams,\u201d continued the SRK expert. These incredibly dangerous events can travel at speeds of 30-40 kph (18.5-35 mph) and occur at the coincidence of four factors: mud-forming materials, water, disturbance in the form of mining or drawing, and a discharge point.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u201cWater ingress into the underground workings from the open pit therefore needs to be carefully managed, particularly when open pit operations have ceased. Some pit dewatering may need to continue through the life of the underground mine.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>A new factor? ESG and the underground transition<\/strong><br>As noted at the start, the timing of any surface-to-underground transition is traditionally based on economics; however, increased focus on ESG factors within the mining industry could bring a new variable into the equation \u2013 and perhaps see mines move underground earlier.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u201cUnderground mining has many environmental advantages compared to an open pit operation,\u201d said AMC\u2019s Andrew Hall. \u201cWhen this is coupled with strong ESG commitments, it creates a positive image for investors and could bring forward the transition, irrespective of what direct cost analysis tells us. At the same time, open pit mines may provide an ideal access point for underground mines.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This only emphasizes the importance of planning any potential shift to underground working as early as possible. Yet underground mining is generally also much more technically challenging, with higher upfront costs. \u201cIt is therefore often an easier decision to mine an additional cut-back and delay developing underground operations,\u201d concluded Hall. \u201cUnfortunately, feasibility evaluation is usually not undertaken early or comprehensively enough, and the optimal transition point is missed and the opportunity lost.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">And so we return to where we began \u2013 and the message emphasized by all contributors. When it comes to transitioning from an open pit to underground working, it is never too soon to start planning!&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Note: For a more detailed discussion of many of the topics covered by this article, see: Stacey, T.R, and Terbrugge, P.J., \u2018Open Pit to Underground \u2013 Transition and Interaction\u2019, in proceedings of MassMin 2000, pp. 97-104; and Luxford, J., \u2018Surface to Underground \u2013 Making the Transition\u2019, in proceedings of the International Conference on Mine Development (Mindev 97), Sydney 1997.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Moving from open pit to underground operations is fraught with complications. North American Mining spoke to three experts about the considerations and risks involved.\u00a0 By Jonathan Rowland A majority of mining operations begin life as open pits; however, as mining progresses, ore reserves may be proved to extend to greater depths than originally anticipated. To continue exploiting these reserves, the&hellip;<\/p>\n","protected":false},"author":8,"featured_media":4770,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_themeisle_gutenberg_block_has_review":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[4],"tags":[2021,614,2022,2023,852],"coauthors":[1635],"class_list":["post-4768","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-features","tag-amc-consultants","tag-mining-operations","tag-open-pit-mining","tag-srk","tag-underground-operations"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.8 - aioseo.com -->\n\t<meta name=\"description\" content=\"Moving from open pit to underground operations is fraught with complications. North American Mining spoke to three experts about the considerations and risks involved. By Jonathan Rowland A majority of mining operations begin life as open pits; however, as mining progresses, ore reserves may be proved to extend to greater depths than originally anticipated. To\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<meta name=\"author\" content=\"Jonathan Rowland\"\/>\n\t<link rel=\"canonical\" href=\"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/\" \/>\n\t<meta name=\"generator\" content=\"All in One SEO (AIOSEO) 4.9.8\" \/>\n\t\t<meta property=\"og:locale\" content=\"en_US\" \/>\n\t\t<meta property=\"og:site_name\" content=\"North American Mining Magazine - Bringing the North American Mining Industry Into Focus\" \/>\n\t\t<meta property=\"og:type\" content=\"article\" \/>\n\t\t<meta property=\"og:title\" content=\"PLANNING AN UNDERGROUND TRANSITION - North American Mining Magazine\" \/>\n\t\t<meta property=\"og:description\" content=\"Moving from open pit to underground operations is fraught with complications. North American Mining spoke to three experts about the considerations and risks involved. By Jonathan Rowland A majority of mining operations begin life as open pits; however, as mining progresses, ore reserves may be proved to extend to greater depths than originally anticipated. To\" \/>\n\t\t<meta property=\"og:url\" content=\"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/\" \/>\n\t\t<meta property=\"og:image\" content=\"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png\" \/>\n\t\t<meta property=\"og:image:secure_url\" content=\"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png\" \/>\n\t\t<meta property=\"og:image:width\" content=\"1201\" \/>\n\t\t<meta property=\"og:image:height\" content=\"717\" \/>\n\t\t<meta property=\"article:published_time\" content=\"2023-05-16T18:00:15+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2023-05-16T18:56:48+00:00\" \/>\n\t\t<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/NAminingmag\" \/>\n\t\t<meta name=\"twitter:card\" content=\"summary\" \/>\n\t\t<meta name=\"twitter:title\" content=\"PLANNING AN UNDERGROUND TRANSITION - North American Mining Magazine\" \/>\n\t\t<meta name=\"twitter:description\" content=\"Moving from open pit to underground operations is fraught with complications. North American Mining spoke to three experts about the considerations and risks involved. By Jonathan Rowland A majority of mining operations begin life as open pits; however, as mining progresses, ore reserves may be proved to extend to greater depths than originally anticipated. To\" \/>\n\t\t<meta name=\"twitter:image\" content=\"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png\" \/>\n\t\t<script type=\"application\/ld+json\" class=\"aioseo-schema\">\n\t\t\t{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"BlogPosting\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#blogposting\",\"name\":\"PLANNING AN UNDERGROUND TRANSITION - North American Mining Magazine\",\"headline\":\"PLANNING AN UNDERGROUND TRANSITION\",\"author\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/author\\\/jrowland\\\/#author\"},\"publisher\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/#organization\"},\"image\":{\"@type\":\"ImageObject\",\"url\":\"https:\\\/\\\/northamericanmining.com\\\/wp-content\\\/uploads\\\/2023\\\/05\\\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png\",\"width\":1201,\"height\":717},\"datePublished\":\"2023-05-16T18:00:15+00:00\",\"dateModified\":\"2023-05-16T18:56:48+00:00\",\"inLanguage\":\"en-US\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#webpage\"},\"isPartOf\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#webpage\"},\"articleSection\":\"Features, AMC Consultants, mining operations, open pit mining, SRK, underground operations, JRowland\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#breadcrumblist\",\"itemListElement\":[{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/northamericanmining.com#listItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/northamericanmining.com\",\"nextItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/category\\\/features\\\/#listItem\",\"name\":\"Features\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/category\\\/features\\\/#listItem\",\"position\":2,\"name\":\"Features\",\"item\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/category\\\/features\\\/\",\"nextItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#listItem\",\"name\":\"PLANNING AN UNDERGROUND TRANSITION\"},\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/northamericanmining.com#listItem\",\"name\":\"Home\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#listItem\",\"position\":3,\"name\":\"PLANNING AN UNDERGROUND TRANSITION\",\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/category\\\/features\\\/#listItem\",\"name\":\"Features\"}}]},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/#organization\",\"name\":\"North American Mining Magazine\",\"description\":\"Bringing the North American Mining Industry Into Focus\",\"url\":\"https:\\\/\\\/northamericanmining.com\\\/\",\"telephone\":\"+13032830640\",\"logo\":{\"@type\":\"ImageObject\",\"url\":\"https:\\\/\\\/northamericanmining.com\\\/wp-content\\\/uploads\\\/2022\\\/05\\\/NAM_Logo.png\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#organizationLogo\",\"width\":2384,\"height\":646},\"image\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#organizationLogo\"},\"sameAs\":[\"https:\\\/\\\/www.youtube.com\\\/@semcopublishing\",\"https:\\\/\\\/www.linkedin.com\\\/company\\\/naminingmag\\\/\"]},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/author\\\/jrowland\\\/#author\",\"url\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/author\\\/jrowland\\\/\",\"name\":\"Jonathan Rowland\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#webpage\",\"url\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/\",\"name\":\"PLANNING AN UNDERGROUND TRANSITION - North American Mining Magazine\",\"description\":\"Moving from open pit to underground operations is fraught with complications. North American Mining spoke to three experts about the considerations and risks involved. By Jonathan Rowland A majority of mining operations begin life as open pits; however, as mining progresses, ore reserves may be proved to extend to greater depths than originally anticipated. To\",\"inLanguage\":\"en-US\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/#website\"},\"breadcrumb\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#breadcrumblist\"},\"author\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/author\\\/jrowland\\\/#author\"},\"creator\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/author\\\/jrowland\\\/#author\"},\"image\":{\"@type\":\"ImageObject\",\"url\":\"https:\\\/\\\/northamericanmining.com\\\/wp-content\\\/uploads\\\/2023\\\/05\\\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#mainImage\",\"width\":1201,\"height\":717},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/index.php\\\/2023\\\/05\\\/16\\\/planning-an-underground-transition\\\/#mainImage\"},\"datePublished\":\"2023-05-16T18:00:15+00:00\",\"dateModified\":\"2023-05-16T18:56:48+00:00\"},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/#website\",\"url\":\"https:\\\/\\\/northamericanmining.com\\\/\",\"name\":\"North American Mining Magazine\",\"description\":\"Bringing the North American Mining Industry Into Focus\",\"inLanguage\":\"en-US\",\"publisher\":{\"@id\":\"https:\\\/\\\/northamericanmining.com\\\/#organization\"}}]}\n\t\t<\/script>\n\t\t<!-- All in One SEO -->\n\n","aioseo_head_json":{"title":"PLANNING AN UNDERGROUND TRANSITION - North American Mining Magazine","description":"Moving from open pit to underground operations is fraught with complications. North American Mining spoke to three experts about the considerations and risks involved. By Jonathan Rowland A majority of mining operations begin life as open pits; however, as mining progresses, ore reserves may be proved to extend to greater depths than originally anticipated. To","canonical_url":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"BlogPosting","@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#blogposting","name":"PLANNING AN UNDERGROUND TRANSITION - North American Mining Magazine","headline":"PLANNING AN UNDERGROUND TRANSITION","author":{"@id":"https:\/\/northamericanmining.com\/index.php\/author\/jrowland\/#author"},"publisher":{"@id":"https:\/\/northamericanmining.com\/#organization"},"image":{"@type":"ImageObject","url":"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png","width":1201,"height":717},"datePublished":"2023-05-16T18:00:15+00:00","dateModified":"2023-05-16T18:56:48+00:00","inLanguage":"en-US","mainEntityOfPage":{"@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#webpage"},"isPartOf":{"@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#webpage"},"articleSection":"Features, AMC Consultants, mining operations, open pit mining, SRK, underground operations, JRowland"},{"@type":"BreadcrumbList","@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#breadcrumblist","itemListElement":[{"@type":"ListItem","@id":"https:\/\/northamericanmining.com#listItem","position":1,"name":"Home","item":"https:\/\/northamericanmining.com","nextItem":{"@type":"ListItem","@id":"https:\/\/northamericanmining.com\/index.php\/category\/features\/#listItem","name":"Features"}},{"@type":"ListItem","@id":"https:\/\/northamericanmining.com\/index.php\/category\/features\/#listItem","position":2,"name":"Features","item":"https:\/\/northamericanmining.com\/index.php\/category\/features\/","nextItem":{"@type":"ListItem","@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#listItem","name":"PLANNING AN UNDERGROUND TRANSITION"},"previousItem":{"@type":"ListItem","@id":"https:\/\/northamericanmining.com#listItem","name":"Home"}},{"@type":"ListItem","@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#listItem","position":3,"name":"PLANNING AN UNDERGROUND TRANSITION","previousItem":{"@type":"ListItem","@id":"https:\/\/northamericanmining.com\/index.php\/category\/features\/#listItem","name":"Features"}}]},{"@type":"Organization","@id":"https:\/\/northamericanmining.com\/#organization","name":"North American Mining Magazine","description":"Bringing the North American Mining Industry Into Focus","url":"https:\/\/northamericanmining.com\/","telephone":"+13032830640","logo":{"@type":"ImageObject","url":"https:\/\/northamericanmining.com\/wp-content\/uploads\/2022\/05\/NAM_Logo.png","@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#organizationLogo","width":2384,"height":646},"image":{"@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#organizationLogo"},"sameAs":["https:\/\/www.youtube.com\/@semcopublishing","https:\/\/www.linkedin.com\/company\/naminingmag\/"]},{"@type":"Person","@id":"https:\/\/northamericanmining.com\/index.php\/author\/jrowland\/#author","url":"https:\/\/northamericanmining.com\/index.php\/author\/jrowland\/","name":"Jonathan Rowland"},{"@type":"WebPage","@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#webpage","url":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/","name":"PLANNING AN UNDERGROUND TRANSITION - North American Mining Magazine","description":"Moving from open pit to underground operations is fraught with complications. North American Mining spoke to three experts about the considerations and risks involved. By Jonathan Rowland A majority of mining operations begin life as open pits; however, as mining progresses, ore reserves may be proved to extend to greater depths than originally anticipated. To","inLanguage":"en-US","isPartOf":{"@id":"https:\/\/northamericanmining.com\/#website"},"breadcrumb":{"@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#breadcrumblist"},"author":{"@id":"https:\/\/northamericanmining.com\/index.php\/author\/jrowland\/#author"},"creator":{"@id":"https:\/\/northamericanmining.com\/index.php\/author\/jrowland\/#author"},"image":{"@type":"ImageObject","url":"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png","@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#mainImage","width":1201,"height":717},"primaryImageOfPage":{"@id":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/#mainImage"},"datePublished":"2023-05-16T18:00:15+00:00","dateModified":"2023-05-16T18:56:48+00:00"},{"@type":"WebSite","@id":"https:\/\/northamericanmining.com\/#website","url":"https:\/\/northamericanmining.com\/","name":"North American Mining Magazine","description":"Bringing the North American Mining Industry Into Focus","inLanguage":"en-US","publisher":{"@id":"https:\/\/northamericanmining.com\/#organization"}}]},"og:locale":"en_US","og:site_name":"North American Mining Magazine - Bringing the North American Mining Industry Into Focus","og:type":"article","og:title":"PLANNING AN UNDERGROUND TRANSITION - North American Mining Magazine","og:description":"Moving from open pit to underground operations is fraught with complications. North American Mining spoke to three experts about the considerations and risks involved. By Jonathan Rowland A majority of mining operations begin life as open pits; however, as mining progresses, ore reserves may be proved to extend to greater depths than originally anticipated. To","og:url":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/","og:image":"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png","og:image:secure_url":"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png","og:image:width":1201,"og:image:height":717,"article:published_time":"2023-05-16T18:00:15+00:00","article:modified_time":"2023-05-16T18:56:48+00:00","article:publisher":"https:\/\/www.facebook.com\/NAminingmag","twitter:card":"summary","twitter:title":"PLANNING AN UNDERGROUND TRANSITION - North American Mining Magazine","twitter:description":"Moving from open pit to underground operations is fraught with complications. North American Mining spoke to three experts about the considerations and risks involved. By Jonathan Rowland A majority of mining operations begin life as open pits; however, as mining progresses, ore reserves may be proved to extend to greater depths than originally anticipated. To","twitter:image":"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png"},"aioseo_meta_data":{"post_id":"4768","title":null,"description":null,"keywords":[],"keyphrases":{"focus":{"keyphrase":"","score":0,"analysis":{"keyphraseInTitle":{"score":0,"maxScore":9,"error":1}}},"additional":[]},"primary_term":null,"canonical_url":null,"og_title":null,"og_description":null,"og_object_type":"default","og_image_type":"default","og_image_url":null,"og_image_width":null,"og_image_height":null,"og_image_custom_url":null,"og_image_custom_fields":null,"og_video":"","og_custom_url":null,"og_article_section":null,"og_article_tags":[],"twitter_use_og":false,"twitter_card":"default","twitter_image_type":"default","twitter_image_url":null,"twitter_image_custom_url":null,"twitter_image_custom_fields":null,"twitter_title":null,"twitter_description":null,"schema":{"blockGraphs":[],"customGraphs":[],"default":{"data":{"Article":[],"Course":[],"Dataset":[],"FAQPage":[],"Movie":[],"Person":[],"Product":[],"ProductReview":[],"Car":[],"Recipe":[],"Service":[],"SoftwareApplication":[],"WebPage":[]},"graphName":"","isEnabled":true},"graphs":[]},"schema_type":"default","schema_type_options":null,"pillar_content":false,"robots_default":true,"robots_noindex":false,"robots_noarchive":false,"robots_nosnippet":false,"robots_nofollow":false,"robots_noimageindex":false,"robots_noodp":false,"robots_notranslate":false,"robots_max_snippet":"-1","robots_max_videopreview":"-1","robots_max_imagepreview":"large","priority":null,"frequency":"default","local_seo":null,"breadcrumb_settings":null,"limit_modified_date":false,"ai":null,"created":"2023-05-16 18:00:17","updated":"2025-06-30 23:41:59","seo_analyzer_scan_date":null},"aioseo_breadcrumb":"<div class=\"aioseo-breadcrumbs\"><span class=\"aioseo-breadcrumb\">\n\t\t\t<a href=\"https:\/\/northamericanmining.com\" title=\"Home\">Home<\/a>\n\t\t<\/span><span class=\"aioseo-breadcrumb-separator\">&raquo;<\/span><span class=\"aioseo-breadcrumb\">\n\t\t\t<a href=\"https:\/\/northamericanmining.com\/index.php\/category\/features\/\" title=\"Features\">Features<\/a>\n\t\t<\/span><span class=\"aioseo-breadcrumb-separator\">&raquo;<\/span><span class=\"aioseo-breadcrumb\">\n\t\t\tPLANNING AN UNDERGROUND TRANSITION\n\t\t<\/span><\/div>","aioseo_breadcrumb_json":[{"label":"Home","link":"https:\/\/northamericanmining.com"},{"label":"Features","link":"https:\/\/northamericanmining.com\/index.php\/category\/features\/"},{"label":"PLANNING AN UNDERGROUND TRANSITION","link":"https:\/\/northamericanmining.com\/index.php\/2023\/05\/16\/planning-an-underground-transition\/"}],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/northamericanmining.com\/wp-content\/uploads\/2023\/05\/munkh-erdene-eenee-lrnc1AdZ8wA-unsplash-e1684259923348.png","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/posts\/4768","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/comments?post=4768"}],"version-history":[{"count":3,"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/posts\/4768\/revisions"}],"predecessor-version":[{"id":4804,"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/posts\/4768\/revisions\/4804"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/media\/4770"}],"wp:attachment":[{"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/media?parent=4768"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/categories?post=4768"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/tags?post=4768"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/northamericanmining.com\/index.php\/wp-json\/wp\/v2\/coauthors?post=4768"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}