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Shaft sinking

Shaft sinking is the excavation of vertical or near-vertical openings from the surface downward to provide access to underground mineral deposits in mining operations, typically involving a repetitive cycle of drilling, blasting, debris removal, and structural support to ensure stability and safety.^[1] These shafts serve critical functions, including the transportation of workers, equipment, and extracted materials; ventilation of underground workings; and drainage of water.^[2] Shaft dimensions vary widely, from small prospect shafts (e.g., 5x7 feet) for shallow exploration to large production shafts (e.g., 16x28 feet) capable of handling 6,000 tons per day, with depths reaching over 2,000 feet in challenging geological conditions.^[2]^[3] The conventional method of shaft sinking relies on drill-and-blast techniques, where workers drill holes in patterns such as V-cuts or diamond cuts, load them with explosives (typically 10-70 pounds per foot of advance), detonate to fracture the rock, and then remove the broken material (mucking) using buckets, skips, or mechanical loaders hoisted to the surface.^[1]^[2] Temporary supports, such as timber sets spaced 5 feet apart or steel rings, are installed immediately after each round to prevent collapse, followed by permanent lining with concrete (often 4.5-12 inches thick) or precast cribbing for long-term stability and fire resistance.^[1]^[2] Advance rates in conventional sinking typically range from 4-10 feet per round, with overall progress averaging about two-thirds of the best monthly rate, influenced by factors like ground conditions and crew efficiency.^[4] Ventilation systems, using blowers and tubing (8-20 inches in diameter), are essential to clear smoke and fumes after blasting, maintaining minimum air velocities of 50-100 feet per minute.^[4]^[2] Modern shaft sinking has evolved with mechanized technologies to improve speed, safety, and cost-efficiency, particularly for deeper or softer ground conditions.^[5] Key innovations include raise boring for pilot holes expanded to full diameter, shaft boring roadheaders (SBR) that combine cutting and loading in one machine, and full-face mechanical excavation using tunnel boring machine variants for continuous operation without blasting.^[3]^[6] For instance, the vertical shaft boring method allows rapid sinking in stable rock by drilling and reaming simultaneously, with systems like Master Drilling's SBS reducing personnel exposure from hundreds to as few as 20-80 workers per project.^[7] Automation features, such as wireless communications, laser-guided directional control, and hydraulic mucking units, further enhance precision and minimize risks in gassy or water-bearing formations.^[3]^[8] Recent projects from 2020-2025, including those in China and potash mines, demonstrate these methods achieving depths up to 820 meters with integrated freezing and grouting for ground stabilization, alongside 2024-2025 advancements in robotics and AI integration for greater automation.^[5]^[9]^[10] Despite advancements, shaft sinking remains a high-risk endeavor challenged by geological variability, water ingress requiring grouting or freezing, high pressures in deep shafts, and the need for robust geotechnical planning to mitigate collapses or delays.^[3] Costs are significantly influenced by shaft size, depth, and rock type, with larger dimensions increasing expenses by 60-70% proportionally, though mechanized approaches can reduce overall timelines and labor needs.^[2] Historical examples, such as the United Verde No. 7 shaft (approximately 2,500 feet deep, sunk in the early 20th century), highlight the enduring principles of these practices, while contemporary innovations continue to push boundaries in global mining projects.^[2]^[11]

Fundamentals

Definition and Purpose

Shaft sinking refers to the excavation of vertical, inclined, or sub-vertical openings from the Earth's surface downward through rock formations to reach underground mineral deposits or connect with existing mine workings.^[12]^[13] This process is a cornerstone of underground mining engineering, creating primary access points that differ from horizontal drifts, which follow seams laterally within the mine, or adits, which are near-horizontal tunnels driven from the surface for shallow entry and dewatering.^[14]^[15] The primary purposes of shaft sinking include providing essential infrastructure for ore hoisting and waste removal, transporting personnel and materials, supplying fresh air for ventilation, and managing groundwater through pumping systems.^[13] These functions are vital for the safe and efficient operation of underground mines, particularly in deep-level operations where surface access is otherwise impractical. By enabling direct vertical connectivity, shafts support the overall production cycle, from exploration to extraction, and are indispensable for mines targeting deposits beyond the reach of open-pit methods. Shaft sinking carries substantial economic implications, often comprising a significant portion of total mine development capital costs due to the intensive labor, equipment, and engineering required before production begins. For instance, at the Vaal Reefs South mine, shaft sinking and associated equipment accounted for about 30% of the initial R68.9 million capital outlay (R20.4 million).^[13] This high upfront investment underscores its operational significance, as delays or inefficiencies in shaft construction can defer revenue generation and elevate project risks, making it a critical factor in assessing the feasibility of deep underground mining ventures. The basic process of shaft sinking unfolds in sequential stages, starting with collaring at the surface to initiate the opening, followed by progressive deepening through controlled excavation, temporary stabilization, and permanent lining installation, culminating in completion with integrated hoisting and utility systems at the target depth.^[16]^[17] This structured approach ensures structural integrity and functionality while minimizing hazards in varying geological conditions.

Historical Overview

Shaft sinking originated in ancient civilizations, where manual labor and rudimentary tools were employed to excavate vertical access points in mines. In the Neolithic period from approximately 8000 BCE to 2000 BCE, early miners used wooden wedges, antler picks, and fire-setting techniques—alternating heating rock with fire and quenching it with water—to fracture hard materials, with spoil removed by hand using ox shoulder blade shovels.^[18] By around 3000 BCE in ancient Egypt, metal chisels and hoes enabled the digging of circular shafts exceeding 30 meters in depth, such as those in the Nubian Desert and Timna Valley during the 14th to 12th centuries BCE, where workers relied on carved footholds and basket-hauling for descent and material removal without formal supports.^[18] The Romans advanced these methods from the 1st century BCE onward, employing iron hammers, bars, and wedges alongside fire-setting to sink square shafts up to 200 meters deep, as exemplified by the El Centenillo mine in Spain reaching 650 feet by the 2nd century CE under Emperor Hadrian, with timber bracing providing essential stabilization.^[18] The Industrial Revolution in the 19th century marked a pivotal shift, introducing mechanized aids that allowed for deeper excavations. Steam-powered hoists, adopted in Cornish tin mines from the early 1800s, facilitated efficient material and worker transport in shafts, complemented by Wilhelm Albert's wire rope innovations between 1831 and 1834 for greater durability over traditional hemp ropes.^[19] Gunpowder blasting, integrated into hand-drilling operations by mid-century, accelerated rock fragmentation, enabling progress rates of 3 to 5 meters per month in Cornish operations like Wheal Agar Mine, where shafts reached depths of 105 meters between 1856 and 1860.^[19] These advancements supported the sinking of exceptionally deep shafts, such as those in Cornwall exceeding 1,000 meters by the late 19th century, transforming mining from localized, shallow efforts into large-scale industrial endeavors.^[20] In the 20th century, post-1900 innovations emphasized electrification and standardization, enhancing safety and efficiency in drill-and-blast cycles. The adoption of electric machinery and compressed air tools revolutionized sinking, with pneumatic jumbos standardizing full-face drilling by the 1920s, particularly in South African gold mines where mechanized records were set, such as at Vlakfontein's No. 2 shaft achieving high-speed progress through integrated hoisting and ventilation.^[21] Cement linings emerged as a durable alternative to timber, first widely applied in the 1940s for water-resistant shafts in deep operations.^[22] Following World War II, the 1940s to 1970s "golden age" introduced mechanical mucking machines like the EIMCO 630 and concrete casting systems, enabling record depths such as 1,052 meters at a Canadian shaft completed in 1958.^[22] Raise boring, invented in the late 1950s by Robbins and first commercially used in 1962, allowed non-explosive excavation from below, while full-face shaft jumbos in the 1970s further mechanized vertical tunneling in hard rock.^[23]^[24]

Shaft Design

Types of Shafts

Shafts in mining are classified primarily by their orientation relative to the horizontal plane, depth capabilities, and functional role in accessing orebodies, with vertical, inclined, and sub-vertical (or winze) types representing the main categories.^[25]^[26] This classification influences their application in various geological settings, where shafts serve as primary vertical or near-vertical conduits for personnel, materials, and ore extraction.^[27] Vertical shafts are excavated perpendicular to the surface, at approximately 90 degrees to the horizontal, enabling direct downward access to deep orebodies.^[25] They are particularly suited for hard rock mining operations requiring depths exceeding 1,000 meters, such as in gold mines like South Africa's Vaal Reefs, where shafts reach up to 3,000 meters to facilitate efficient ore hoisting.^[25] The primary advantages include superior hoisting efficiency due to shorter travel distances and higher speeds—up to 20 meters per second (1,200 meters per minute) or more in modern systems—compared to other orientations, along with faster sinking rates of around 66 meters per month in conventional methods and lower operational costs.^[25]^[28] These features make vertical shafts ideal for high-volume production in stable, narrow-vein deposits.^[29] Inclined shafts, angled between 15 and 45 degrees from the horizontal, provide an alternative for accessing shallower or dipping orebodies, particularly in coal mining where integration with conveyor systems is beneficial.^[25]^[30] This orientation simplifies overburden removal during excavation and allows for continuous material transport via belt conveyors along the slope, reducing the need for vertical lifts in softer strata.^[31] Historically more common—comprising about 40% of South African shafts in 1959—inclined designs are now less favored for depths beyond 2,000 meters due to increased length and maintenance demands, such as at 30-degree inclinations where effective vertical depth is limited.^[25] Sub-vertical or winze shafts are near-vertical internal openings driven downward from an existing underground level to connect multiple mine levels, distinguishing them from surface-originating main shafts by their subsurface starting point and lack of surface hoisting infrastructure.^[26] Often smaller in cross-section than main shafts, winzes serve auxiliary roles in exploration or ventilation rather than primary access.^[25] They are common in multi-level operations where direct vertical extension from the surface is impractical. Selection of shaft type depends on orebody geometry, water table conditions, and seismicity, ensuring alignment with site-specific constraints for safety and efficiency.^[32] Vertical shafts are preferred for vertical or narrow orebodies in hard rock environments, such as gold deposits, to minimize deviation and optimize hoisting, while inclined shafts suit dipping coal seams in softer strata for better conveyor compatibility and drainage above high water tables.^[29]^[33] In seismically active regions, vertical designs in competent rock reduce stress concentrations compared to inclined options in unstable ground.^[34]

Key Components

The collar serves as the reinforced top rim of the shaft where it intersects the surface, typically constructed from concrete and designed to anchor the shaft lining while supporting overlying structures and limiting surface water ingress.^[35] The headframe, positioned directly above the collar, is a robust tower-like structure that houses hoisting equipment and sheaves to facilitate the vertical movement of cages, skips, and materials through the shaft.^[36] At the base, the sump functions as a dedicated drainage pit to accumulate groundwater or seepage, enabling systematic pumping to maintain dry working conditions.^[37] Subsurface elements include wall stations, which are intermediate platforms built along the shaft walls at regular intervals to provide access points for maintenance, inspection, or temporary operations without disrupting hoisting activities.^[38] Guides, consisting of rigid rails or channels affixed to the shaft lining, ensure precise vertical alignment and stability for descending or ascending conveyances like cages, minimizing lateral sway during transit.^[39] Bulkheads act as temporary watertight or airtight seals installed across shaft sections to isolate areas during excavation phases or emergencies, preventing fluid migration or pressure imbalances.^[40] Depth-specific features encompass skip pockets, which are recessed bays or loading zones integrated into the shaft walls near the surface and bottom levels for efficiently transferring ore into hoisting skips while allowing continuous operations.^[35] Deflectors, often curved plates positioned adjacent to skip pockets, direct the trajectory of falling material to optimize loading and reduce spillage within the confined shaft space. These components integrate to deliver overall shaft integrity and operational efficiency: the collar and headframe establish a secure surface interface, guides and wall stations support reliable subsurface transit and access, bulkheads enable controlled compartmentalization, and skip pockets with deflectors streamline material handling at endpoints, collectively ensuring structural stability against geological pressures and functional reliability for hoisting, as depicted in a conceptual vertical cross-section showing aligned guides spanning from collar sump. Component configurations may adapt slightly based on shaft type, such as vertical versus inclined designs.^[35]

Construction Methods

Planning and Preparation

Shaft sinking projects begin with comprehensive site investigations to evaluate subsurface conditions and mitigate risks. Geological surveys involve mapping rock formations, identifying fault zones, and assessing overburden characteristics through methods such as borehole drilling and core sampling. Core drilling provides essential data on rock quality, including rock quality designation (RQD) and core recovery percentages, which inform the stability and excavation feasibility of the shaft. Hydrological studies, including downhole packer testing, measure hydraulic conductivity to quantify groundwater inflow risks, which can exceed 75 m³/hr in permeable zones like sandstones, necessitating preemptive measures such as grouting. These investigations are critical for avoiding costly delays and ensuring safe construction in variable geotechnical environments.^[41]^[42]^[43] The design phase follows, where engineers determine shaft parameters based on site data and project requirements. Typical dimensions include diameters of 4-8 meters to accommodate personnel, equipment, and ventilation systems, with depths varying from shallow overburden to over 1,000 meters in deep mines. Alignment is optimized using geotechnical modeling software that integrates borehole logs and rock mass classifications to predict stress distributions and deformation patterns. Recent advancements as of 2025 include the use of AI-driven digital twins in geotechnical modeling to enhance predictions of rock behavior and optimize shaft alignment. This modeling ensures the shaft path avoids weak zones and aligns with operational needs, such as integration with specific shaft types like production or ventilation shafts. Designs also incorporate preliminary support strategies, such as concrete linings 300-500 mm thick, to handle anticipated ground pressures.^[44]^[42] Regulatory and environmental preparation is integral to project approval and sustainability. Permitting processes require submission of detailed plans to mining authorities, including assessments of potential impacts on air, water, and land use. Environmental impact assessments (EIAs) evaluate effects from shaft sinking, such as groundwater disruption and surface disturbance, and mandate baseline ecosystem surveys for flora, fauna, and water quality. Compliance with standards like ISO 14001 for environmental management systems helps integrate pollution prevention and resource efficiency into operations, as seen in certified mining projects. These steps ensure adherence to national regulations and international best practices, minimizing ecological footprints.^[45]^[46]^[47] Resource allocation encompasses budgeting and phased planning to optimize project execution. Budgets cover labor costs, often at premium rates for skilled sinking crews, equipment procurement like drilling rigs and hoists, and contingencies for geological uncertainties, with engineering completion reaching 40-50% for accurate ±10% cost estimates. Timelines are structured in phases: feasibility studies validate economic viability; preliminary design refines parameters; detailed design produces construction drawings; and mobilization involves site setup and contractor onboarding. Project managers use critical-path methods to monitor progress, ensuring mobilization aligns with regulatory approvals for timely commencement.^[48]

Excavation Techniques

Shaft sinking excavation primarily relies on traditional methods suited to varying geological conditions, focusing on controlled rock removal to advance vertically from the surface. These techniques emphasize safety and efficiency in hard rock environments, where mechanical stability allows for repetitive cycles of material extraction without immediate stabilization. The drill-and-blast method remains a cornerstone for excavating shafts in hard rock formations, involving a cyclic process of drilling blast holes, charging with explosives, detonating, and mucking out the fragmented material. Typically, rounds advance 2-3 meters, with holes drilled using pneumatic or hydraulic jumbo rigs in patterns such as V-cut or pyramid to optimize fragmentation and minimize overbreak. Explosives like ammonium nitrate-fuel oil (ANFO) are commonly loaded into the holes for their cost-effectiveness and reliable energy release in dry conditions, followed by ventilation to clear fumes before mucking with loaders or scrapers. This approach is particularly suitable for hard, competent rock where seismic stability reduces the risk of uncontrolled fracturing.^[2]^[49] Raise boring provides an intermediate mechanical alternative for creating smaller-diameter access points, starting with a pilot hole drilled downward, typically from an upper level to an existing lower opening, and then reamed upward to expand the excavation; for blind shaft sinking from the surface, specialized blind raise boring methods are used to avoid the need for bottom access. A raise boring machine attaches a cutting head to the drill string after pilot breakthrough, mechanically reaming the hole in a bottom-up direction to achieve diameters of 1-2 meters, ideal for ventilation or utility shafts without direct worker exposure to the face. This method uses pilot holes of 0.23-0.38 meters initially, with the reamer following to cut annular rock, supported by stabilization platforms or climbers for equipment positioning during longer bores. It excels in competent rock where precise alignment minimizes deviation.^[50]^[51] Conventional hand-held methods, though less common in modern deep sinking, are employed for shallow or narrow shafts where space constraints limit machinery. Workers use jackhammers or stopers mounted on air legs to drill holes manually, followed by hand-charging explosives and mucking with shovels or small loaders, often with temporary timbering to manage loose faces. These techniques achieve advance rates of 1-2 meters per day, constrained by manual labor intensity and the need for frequent pauses to scale rock and ensure safety. They are best suited to softer or fractured rock in initial collaring phases.^[3] Overall advance rates in shaft sinking vary significantly with rock hardness and method, typically reaching 2-4 meters per day in competent, massive rock under modern drill-and-blast conditions due to efficient cycling and minimal downtime, with historical rates around 1-2 meters per day. Softer or faulted ground reduces rates by increasing fragmentation challenges and ventilation needs, while factors like water inflow or equipment reliability further influence progress.^[2]^[16]

Lining and Support Systems

In shaft sinking, lining and support systems are essential for maintaining structural integrity, preventing ground convergence, and ensuring watertightness after excavation. These systems provide temporary or permanent reinforcement tailored to ground conditions, with installation typically following each blasting and mucking cycle to minimize exposure time.^[2]^[16] Timber lining serves as a temporary support, particularly in soft or unstable ground, using configurations such as wedge-set or square-set timbers to distribute loads and allow for adjustments during sinking. Materials often include 8x8-inch or 10x10-inch posts of durable woods like Douglas fir or Oregon fir, spaced 5-6 feet apart and lagged with 2-inch planks to form a barrier against minor inflows. Pros include rapid installation and adaptability to irregular conditions, enabling sinking to proceed without delays, while cons encompass fire hazards, decay over time requiring replacements, and limited load-bearing capacity in prolonged exposure. Installation involves placing sets 5-50 feet above the shaft bottom using platforms or crews, secured with wedges or turnbuckles in moving ground.^[2]^[16] Concrete lining provides permanent support, commonly installed as cast-in-place monolithic walls or precast segments to achieve long-term stability and seal against water ingress. Mix designs typically feature high-strength formulations, such as 1:2:4 cement-sand-aggregate ratios using Type II/V cement and admixtures for workability, achieving compressive strengths exceeding 4,000 psi after curing. Curing processes involve vibrated placement in 45-foot sections with steel forms stripped after 8 hours, followed by 7-28 days of moist curing to prevent cracking. Precast segments, reinforced with 3/4-inch bars, are assembled in rings 2.5 feet thick on 6-foot centers for efficiency in deeper shafts. Pros include superior durability and watertightness compared to timber, while cons involve higher initial setup time and the need to avoid blasting near uncured concrete. Sequencing entails pouring after advancing 48 feet, integrating with wall stations for load transfer.^[2]^[16]^[44] Steel and composite systems are employed in high-stress areas, such as fault zones or deep excavations, where rigid reinforcement is required to counter rock bursts or squeezing. Steel sets, made from 12-inch I-beams or 8-inch channels, provide immediate support, often combined with concrete lagging or mesh for hybrid composites that enhance tensile strength. Installation follows each excavation round, with sets bolted or welded in place and concreted over for permanence. Pros include high load capacity and reusability in stable rock, while cons feature higher costs and unsuitability for highly deformable ground. These systems may reference key components like buntons for integration.^[2]^[44] Selection criteria for lining systems are determined by rock mechanics, including convergence control to limit deformations, and shaft depth, with deeper excavations (over 1,000 meters) demanding thicker, more robust designs to handle increased hydrostatic and overburden pressures. Timber suits shallow, soft ground; concrete or steel for stable or high-stress conditions; typical thicknesses range from 0.3-1 meter for concrete, scaling with depth and geology assessments from borehole data. Shotcrete may supplement initial supports in weak zones during sinking.^[2]^[44]^[3]

Operational Features

Compartments and Infrastructure

In shaft sinking, compartments are essential subdivisions that organize the internal space for distinct operational functions, ensuring efficient transport and utility distribution while minimizing conflicts between activities. These divisions are typically achieved through robust partitions within rectangular or circular shaft profiles, with the overall cross-sectional area allocated based on production needs, such as ore throughput and personnel movement. In typical designs, approximately half the area is allocated to hoisting compartments for ore and materials, with the remaining area divided between personnel cages, manways, and utility spaces, varying by project needs.^[35] This separation prevents mechanical interference, such as hoisting ropes tangling with utility lines, and is mandated by regulatory standards requiring substantial partitions between manways and hoisting areas.^[52] Manways serve as dedicated compartments for pedestrian access, equipped with fixed ladders to allow safe vertical travel for maintenance and emergency egress. These spaces are typically narrow to optimize shaft efficiency, with dimensions around 1 meter in width by 1.5 meters in height, providing sufficient clearance for a single file of workers.^[2] Ladders within manways feature rungs spaced 25 to 36 cm apart, and rest platforms are incorporated at regular intervals to facilitate breaks during descent or ascent and comply with fall protection standards.^[53] In deeper modern shafts, belt elevators or auxiliary hoists may supplement or replace fixed ladders for personnel access to enhance efficiency and safety. In three-compartment designs prevalent in hard rock mining, the manway often shares space with basic services but remains isolated from primary transport zones.^[29] Hoisting compartments are the largest subdivisions, designed to handle heavy loads via cages for personnel and materials, skips for ore, and counterweights for balance. These areas include rigid guide rails along the shaft walls to stabilize conveyances during rapid vertical movement and loading bays at each level for efficient transfer. Typical dimensions for skip compartments are 1.7 meters by 1.8 meters, accommodating payloads up to several tons, while cage compartments may extend to 2 meters by 4 meters to fit multiple skips or service cars.^[2] In deep operations, such as the Kidd Creek mine in Ontario, a three-compartment shaft configuration supports hoisting from depths over 3,000 meters, with dual hoisting compartments enabling high-volume ore extraction.^[54] Utility spaces occupy dedicated or combined compartments to route essential infrastructure, including piping for water supply and electrical conduits for powering pumps and lighting, as well as provisions for conveyor belts in service-oriented shafts. These areas are sized proportionally smaller than hoisting zones, often 10-20% of the total cross-section, and integrated along compartment walls to avoid obstructing primary paths.^[2] Design standards emphasize compartmental isolation to protect utilities from damage during hoisting, with examples from early 20th-century shafts like United Verde No. 7 illustrating pipe compartments adjacent to but partitioned from skips.^[2] Shaft lining, typically concrete or timber, encloses these compartments to provide structural containment.^[2]

Ventilation and Access

Ventilation systems in shaft sinking ensure the supply of fresh air to the working face while removing contaminants such as dust, fumes, and harmful gases generated during excavation. Auxiliary fans, typically positioned at the surface or intermediate levels, force air through flexible ducting or rigid columns into the shaft bottom, with common setups using a force ventilation approach where fresh air is blown down one compartment and exhausted via another. For an 8-meter diameter shaft, minimum air velocities of 0.5 m/s are maintained to achieve supply rates around 25 m³/s, sufficient for dilution and removal of diesel exhaust and blasting fumes.^[55] Monitoring is integral to these systems, involving continuous sampling for gases like carbon monoxide (limited to 30 ppm occupational exposure) and respirable dust (e.g., silica below 0.1 mg/m³), using sensors placed near the sinking horizon to detect exceedances and trigger adjustments in fan operation. Ventilation ducting often runs alongside power lines in temporary setups, with exhaust volumes approximately 1.5 times the intake to enhance contaminant clearance. Dedicated compartments may house these ducts and fans, separating airflow from personnel and material transport paths.^[55] Access to the shaft during sinking relies on hoisting mechanisms including cages for personnel transport (functioning as elevators) and skips for materials and muck removal, with capacities designed for efficient cycle times—typically 20-30 personnel per cage load in multi-deck configurations. Emergency escapes incorporate ladderways or secondary cages in separate compartments, providing an independent egress route. Signaling systems, required by regulation, employ at least two independent methods (e.g., bell codes and visual indicators) between shaft stations and the hoist room to coordinate movements and prevent collisions during hoisting operations.^[56] During sinking, ventilation integrates via temporary auxiliary setups, including surface fans pushing air through pipes installed in guide compartments, alongside power cables for equipment, to support ongoing excavation without permanent infrastructure. Post-completion, these transition to stationary main fans at the shaft collar, providing sustained airflow for mine operations. Compliance with standards such as those from the Mine Safety and Health Administration (MSHA) mandates minimum airflow velocities exceeding 0.3 m/s in manways to ensure safe travel and contaminant control.^[55]^[57]

Challenges and Advancements

Geological and Safety Considerations

Shaft sinking operations must contend with a variety of geological challenges that can compromise stability and progress. Faults and fractures in the rock mass pose significant risks by allowing sudden inflows of water or ground collapse, necessitating careful geotechnical mapping prior to excavation.^[58] Swelling clays and other expansive soils, common in sedimentary formations, expand upon exposure to moisture, leading to pressure on shaft linings and potential deformation.^[59] High water inflow from aquifers is particularly problematic in regions with abundant groundwater, such as Polish mining areas, where inflows can flood workings and erode unlined sections, often requiring dewatering systems with pumps handling capacities around 1,000 L/min to maintain dry conditions.^[60]^[61] Safety measures in shaft sinking prioritize hazard mitigation through continuous monitoring and protocols. Ground support systems, including rock bolts and mesh, are routinely inspected using convergence gauges and extensometers to detect movement early and prevent collapses.^[62] Gas detection for methane and other flammable gases is mandatory, with portable and fixed sensors alerting workers to concentrations exceeding 1% by volume, as required by federal regulations, to avert explosions in confined shaft environments.^[63]^[64] Evacuation plans involve designated refuge chambers, secondary egress routes, and regular drills, ensuring rapid response to emergencies like flooding or ground failure.^[62] Shaft sinking contributes to a substantial portion of underground mining fatalities, with historical data indicating elevated risks from falls, inundations, and structural failures during these operations.^[65] Risk assessment employs standardized tools like the Rock Mass Rating (RMR) system to predict stability and inform support requirements. The RMR evaluates factors such as rock strength, joint spacing, and groundwater conditions on a scale from 0 to 100, with scores below 40 signaling poor stability that demands immediate reinforcement during sinking.^[66]^[67] Training programs for sinkers emphasize fall protection, including harnesses and guardrails around open shafts, as mandated by safety standards to reduce injury rates from heights exceeding 10 meters. Environmental safety focuses on preventing groundwater contamination during shaft sinking through impermeable barriers and controlled dewatering. Watertight segmental linings and pre-grouting seal aquifers to minimize leakage of sediments or chemicals into surrounding water tables, while treated sump water discharge avoids pollutant introduction.^[68]^[60] Artificial ground freezing and cementitious grouts further isolate excavations, ensuring compliance with environmental regulations that limit drawdown impacts on nearby ecosystems.^[61]

Modern Innovations

Since the late 1980s, full-face excavation methods have revolutionized shaft sinking by adapting tunnel boring machine (TBM) technology for vertical applications, enabling faster progress in challenging ground conditions while minimizing worker exposure. Herrenknecht AG pioneered the Vertical Shaft Sinking Machine (VSM) in the 1990s, a compact system that performs simultaneous excavation, muck removal via hydraulic grizzly and clamshell, and precast concrete segment lining, achieving sinking rates of up to 5 meters per day in stable rock and soft ground.^[69] This innovation has been deployed in projects worldwide, including a 45-meter-deep shaft in the Ballard Siphon Project, USA, where rates reached 2.6 meters per day at a 9.8-meter diameter.^[70] Complementing the VSM, Herrenknecht's Shaft Boring Roadheader (SBR), introduced in the 2010s, uses a boom-mounted cutter head for blind shafts in soft to medium-hard rock up to 120 MPa strength, supporting diameters up to 8.3 meters and depths exceeding 1,000 meters, as demonstrated in the Jansen potash mine in Canada.^[71]^[6] These machines reduce cycle times compared to traditional drill-and-blast by integrating full-face cutting and immediate stabilization, with average advances of 3 meters per day and peaks over 7 meters in favorable conditions.^[7] Automation and robotics have further enhanced safety and precision in shaft sinking operations post-2000, particularly through remote-controlled equipment and AI-driven monitoring systems that limit human presence in hazardous underground environments. Remote-controlled drilling jumbos and loaders, such as those from Epiroc, allow operators to perform blast hole drilling and mucking from surface control rooms, reducing exposure to dust, fumes, and collapse risks during excavation cycles. In Australian operations, automated ground control systems integrate real-time sensors with numerical modeling to predict and adjust for rock stability during sinking, achieving consistent progress in variable geology.^[24] Canadian projects employ advanced geotechnical monitoring for dynamic stability analysis, as discussed in industry proceedings.^[72] These technologies have improved productivity while cutting incident rates, with robotics handling repetitive tasks like bolting and meshing in real time.^[73] Sustainable practices in modern shaft sinking emphasize reduced environmental impact through advanced lining techniques and energy-efficient power sources. Slurry walls, constructed using bentonite or polymer slurries to form impermeable barriers during excavation in water-bearing soils, provide temporary support while minimizing groundwater inflow, which cuts dewatering volumes by recycling the slurry and lowering overall water consumption compared to open-cut methods.^[74] This approach, often integrated with segmental concrete linings, enhances eco-friendliness by preventing contamination of aquifers and enabling reuse of bentonite, as applied in urban shaft projects for reduced hydraulic disruption.^[42] Additionally, integration of renewable energy sources, such as solar arrays and wind turbines for surface hoisting and ventilation systems, has become standard in remote mining sites to lower carbon emissions; for instance, hybrid solar-diesel setups power sinking operations, reducing fuel use in sunny regions.^[75] These practices align with broader green mining goals, prioritizing low-permeability materials and energy optimization to support long-term site rehabilitation.^[76] A notable case study is the Oyu Tolgoi copper-gold mine in Mongolia, where hybrid shaft sinking methods combined conventional drill-and-blast with mechanized support systems to complete key infrastructure by 2023 as part of a seven-year underground expansion. Shaft 2, the primary production shaft reaching 1,284 meters depth, utilized remote monitoring and automated mucking alongside traditional excavation to navigate complex geology, achieving handover in 2019 ahead of full operations ramp-up.^[77] Subsequent ventilation shafts 3 and 4, sunk to over 1,100 meters each using similar hybrid techniques with precast lining, were advanced in 2023 and commissioned in the third quarter of 2024 to support block caving at depths up to 1,300 meters, demonstrating improved safety and efficiency in a seismically active area.^[78]^[79] This project, managed by Rio Tinto, incorporated sustainable elements like water recycling in slurry stabilization, contributing to the mine's goal of becoming one of the world's largest copper producers with minimized environmental footprint.^[80]

References

[1]
Mine Shaft Sinking Methods - 911Metallurgist
Mar 28, 2017 · Conventional mine shaft sinking methods involve the performance of a cycle of different operations—drilling and blasting, removal of smoke ...
[2]
[PDF] SHAFT-SINKING PRACTICES AND COSTS
Different. methods of sinking are, of course, necessary in specific instances. because of variations in the depths and sizes of shafts, the material.
[3]
Shaft Sinking - an overview | ScienceDirect Topics
Shaft sinking has a cost which is related significantly to the dimensions of the shafts and the geology of the formation being drilled through.
[4]
[PDF] Hard Rock Miners Handbook Rules of Thumb - 911 Metallurgist
The average rate of advance for shaft sinking will be two-thirds of the advance in the best month (the one everyone talks about). Source: Jim Redpath. 10.03.
[5]
Shaft Sinking from 2007 to 2020: Mechanical excavation
Apr 29, 2020 · The two major developments in shaft sinking between 2007 and 2020 are the successes in mechanical excavation and the number of shafts sunk in China.
[6]
SBR Shaft Sinking | Shaft Boring Roadheader | DMC Mining Services
DMC is a global leader in SBR technology with the most experience and know how to use it best. We successfully delivered the first SBR project in the world.
[7]
[PDF] Lubambe-Mine-New-Shafts-Sinking-Project-EIS.pdf
Apr 1, 2025 · 3) Shaft Sinking Methods – Vertical Shaft Boring method and Shaft Drill and Blast method were evaluated. Vertical Shaft Boring Method is ...
[8]
The Future is Boring - E & MJ - Engineering & Mining Journal
“There have been shaft-sinking projects using conventional methods with 350 personnel working. More common right now is between 80 to 180 persons,” Jordaan ...Missing: modern | Show results with:modern
[9]
[PDF] Shaft Sinking Innovation and Technology - redpath deilmann
The introduction of wireless communi- cations has led to substantial devel- opment of enhanced safety features throughout the sinking plant. Using a.Missing: modern methods 2020-2025
[10]
Modern and innovative shaft sinking and construction technology ...
Aug 6, 2025 · The article deals with the drilling and pipe casing of freezing holes up to 820 m deep to construct shafts in potash and salt mines with a ...
[11]
Shaft sinking innovations in IM September 2025 - LinkedIn
Sep 5, 2025 · The depth charge From concurrent processes to new mechanised blind sinking technology, the shaft sinking market continues to innovate, ...
[12]
Glossary of Mining Terms - SEC.gov
Shaft - A vertical or inclined excavation in rock for the purpose of providing access to an orebody. Usually equipped with a hoist at the top, which lowers and ...
[13]
[PDF] The influence of economics on the design of mine shaft systems
The purpose of this paper is to review some of the more important economic criteria that must be taken into account when planning the number, type, size, ...
[14]
Mining Terms | Department of Environmental Protection
... mining machine and transferring it to an underground loading point, mine railway or belt conveyor system. Sinking - The process by which a shaft is driven.
[15]
What are the differences between shaft mining and drift mining?
Jul 24, 2025 · Shaft mining is typically used for accessing deep deposits, while drift mining is often employed when the deposit is exposed on a hillside or ...
[16]
Mine Shaft Sinking - 911Metallurgist
Feb 17, 2021 · This paper is one of a series prepared by the Bureau of Mines on shaft sinking methods and costs in various districts throughout the United States.
[17]
[PDF] Guidance Note QGN 30.3 Shaft construction metalliferous mines
This process involves installing the sinking stage into the shaft and the roping up of the sinking stage and associated conveyances to the various winder drums.
[18]
Shaft sinking prior to 1600: Ancient times - CIM Magazine
Apr 1, 2020 · Shaft sinking in the Egyptian period and early Roman period was carried out by prisoners of war and criminals, and conditions were terrible.
[19]
Shaft sinking from 1800 to 1900: Cousin Jacks - CIM Magazine
Apr 3, 2020 · Cornish miners, or “Cousin Jacks” as they were called, were to be found all across Latin America sinking shafts and developing mines.
[20]
https://www.suffolklatchcompany.com/blogs/news/the-industrial-revolution-and-tin-mining-in-cornwall-and-devon-a-deep-dive
[21]
Shaft sinking from 1900 to 1940: Start of the modern era
Apr 6, 2020 · The introduction of compressed air and electrical power into mines at the beginning of the 20th century had a great impact on shaft sinking ...
[22]
[PDF] PAPERS PRESENTED TO THE CONFERENCE - Sciences Po
wet, some of the shafts recently sunk are lined with concrete and cement, and equipped with steel and are in consequence comparatively dry. The graph on ...
[23]
Shaft sinking from 1940 to 1970: The golden age - CIM Magazine
Apr 8, 2020 · Evolution of shaft sinking systems in the western world and the improvement in sinking rates (Part Five)
[24]
[PDF] Considerations for large-diameter raiseboring
The development of the first raiseboring machines akin to modern machines (as described in Section 1.2) came in the late 1950s by Robert Cannon and the Robbins ...
[25]
Shaft sinking from 1970 to 2007: Mechanical excavation
Apr 16, 2020 · Shaft boring machines were developed by the Wirth company in Germany and have been designed both as reaming V-moles and full-face excavators.
[26]
[PDF] review of some aspects of shaft design - SAIMM
:For the purpose of this paper there are only two types of shaft: (i) inclined shafts, and. (ii) vertical shafts. In the past, a large number of inclined ...
[27]
[PDF] Working Group n° 23 Shaft Design and Construction - ITA Activities
Winding shaft : A shaft used for hoisting miners or materials, also called hoisting or service shaft. Winze : A vertical or inclined underground opening driven ...
[28]
Lesson 10.1: Orebody Access | MNG 230 - Dutton Institute
Openings that are driven within the ore and follow the seam or vein are known as adits when they are driven in metalliferous veins or drifts when driven in coal ...
[29]
[PDF] intro_to_mining.pdf - Mining and Blasting
Sandy or running ground, especially if wet, offers difficulties in shaft sinking. A shaft-sinking plant consists of a headframe, hoisting equipment, an air ...Missing: textbook | Show results with:textbook
[30]
Mine Shafts of Michigan - Mining History
Most of the deep copper mine shafts were at an angle, ranging between 28 to 73 degrees in angle of descent, so the depth at the bottom of an inclined shaft ...
[31]
Advantages of High Angle Belt Conveyors (Hac) in Mining
Increased depth in the mines looking for steep conveyor path. The classic means of transportation are not able to cope with high gradients.<|separator|>
[32]
Mining method selection for extracting moderately deep ore body ...
May 17, 2022 · There are several factors that influence the selection of a mining method: Physical, mechanical and chemical characteristics of an ore-body and ...Missing: seismicity | Show results with:seismicity
[33]
[PDF] Water Control For Shaft Sinking | 911 Metallurgist
Finally, there is the economics of shaft sinking. While the shaft is be- ing sunk no ore is being produced and there is every incentive to minimize costs.
[34]
[PDF] Seismic response to mining the massive ore body at South Deep ...
Jun 25, 2019 · A mining method, specific to the geometry of the ore body, is utilized and comprises an initial destressing cut followed by massive mining in ...
[35]
10.1.3: Odds and Ends | MNG 230: Introduction to Mining Engineering
The shaft collar is the name given to the point where the shaft intersects the surface, and it is also a structural component of the shaft. It is typically ...
[36]
Shaft Sinking - 911Metallurgist
Nov 8, 2020 · The equipment was the same as that used at the main shaft. The air shaft followed a drill hole tapped by an entry from the main shaft, so that ...
[37]
Definition of sump - Mindat
An excavation made underground to collect water, from which it is pumped to the surface or to another sump nearer the surface. Sumps are placed at the bottom of ...Missing: function | Show results with:function
[38]
https://www.iso.org/obp/ui#!iso:std:iso:19426:-1:dis:ed-1:v1:en
[39]
Shaft Guides and Top Hat Guides in Mining | HMT International
Apr 8, 2025 · Shaft rails and guide rails play a vital role in stabilizing skips, cages, and counterweights, ensuring smooth operations.
[40]
[PDF] Appendix B Shaft Sealing Construction Procedures
The Sealing Contractor will construct a temporary structural steel bulkhead over the shaft at the surface. The bulkhead will be sufficiently strong to ...
[41]
[PDF] Conventional Transfer Chute - Martin Engineering
Deflectors, or “kicker plates,” are often included in the original plan or installed at start up to steer the material flow. During the start-up of a new ...
[42]
[PDF] Impact of Geotechnical and Hydrogeological Parameters upon Shaft ...
In order to obtain information in support of engineering design for shaft sinking, field investigations including, bore hole drilling, core sampling and logging ...Missing: studies | Show results with:studies
[43]
Selection of shaft construction method - ScienceDirect.com
This document reviews the different construction methods, discusses the conditions in which they can be applied, and points out the advantages and ...
[44]
Influence of Hydrogeological Investigation's Accuracy on ... - MDPI
The following work presents the influence of the rising level of accuracy of geological data gathered in the area of shaft sinking in the Silesian Coal Basin.Missing: site | Show results with:site
[45]
Geotechnical Design Considerations For Mine Shafts
Control of ground conditions is a key factor in the design and sinking of shafts, as these conditions may vary considerably throughout the length of a shaft ...
[46]
[PDF] Environmental Impact Assessment Guidelines for the Mining Sector
Mine development works include: access roads, civil, residential and industrial constructions, opening the deposit (i.e. in open cut mines), shaft sinking and ...
[47]
[PDF] Environmental and Social Impact Assessment (ESIA) Guidelines for ...
This Guideline has been developed to inform regulators, environmental assessment experts, investors, mining communities and other stakeholders on the procedures ...<|control11|><|separator|>
[48]
[PDF] IRMA STANDARD v.1.0 - JUNE 2018
Assessment and Management of Environmental and Social Risks and Impacts, and the ISO 14001 Standard for Environmental Management Systems, which some ...Missing: shaft | Show results with:shaft
[49]
[PDF] Project management, and the design of shaft-sinking projects - SAIMM
Daily sinking reports record the work achieved against the work planned, and include all the safety statistics and the delays, both unavoid- able and those ...<|control11|><|separator|>
[50]
Preconditioning blasting for rockburst control in a deep shaft sink
However, ANFO is a gassy explosive whereby the rock is fractured more by the expansion of gasses rather than by shock energy, which is the main mechanism of ...
[51]
[PDF] Large Diameter Vertical Raise Drilling and Shaft Boring Techniques ...
Raise drilling in South Africa started in 1968 with machines capable of drilling 1.2 meter diameter raises up to a length of 90 meters.
[52]
Key technologies of drilling process with raise boring method
The raise boring method is a way to excavate shaft by back reaming the pilot hole using drill rigs. The drill rig plays a significant role in underground ...
[53]
Part 16 - Mine Shafts and Hoists
Shaft sumps. (1) A bulkhead or other suitable stop shall be placed in every working shaft to prevent that part of the hoisting conveyance carrying people from ...Missing: deflectors | Show results with:deflectors
[54]
https://www.mining-technology.com/projects/kidd_creek/
[55]
Kidd Creek Mine Near Timmins, Canada | The Diggings™
PRESENTLY 17 DEG WINDING RAMP AND 3 COMPARTMENT SHAFT SERVE 7 LEVELS TO 853 M. ORE INDICATED TO OVER 1219 M DEPTH. WASTE TO ORE 1. 8: 1. ULTIMATE OPEN PIT ...
[56]
[PDF] VENTILATION FOR SINKING VERTICAL, SUB VERTICAL ... - SAIMM
Thus the ventilation requirements for sinking a shaft or decline must be designed in conjunction with the overall mine design and infrastructure and the ...
[57]
Federal Mine Safety & Health Act of 1977, Public Law 91-173, as ...
... cage, platform, skip, bucket, or cars shall be provided. (d) There shall be at least two effective methods approved by the Secretary of signaling between ...
[58]
30 CFR Part 75 Subpart D -- Ventilation - eCFR
In exhausting face ventilation systems, the mean entry air velocity shall be at least 60 feet per minute reaching each working face where coal is being cut, ...<|control11|><|separator|>
[59]
(PDF) Shaft Sinking and Lining Design for a Deep Potash Shaft in ...
Aug 22, 2015 · This paper describes key geotechnical issues in the design and excavation of mine shafts in weak sedimentary rocks that are commonly encountered in potash ...
[60]
Water Hazard Assessment in Active Shafts in Upper Silesian Coal ...
Aug 13, 2011 · The exposed rock fragments had a tendency to swell when exposed to flowing water and/or water vapour condensation in the shaft, and fall into ...
[61]
Polish Experiences in Handling Water Hazards during Mine Shaft ...
The geological structure of most Polish mining regions is rich in groundwater, making shaft sinking difficult. In recent years, more than a dozen shafts, ...
[62]
Control Water Flow during Shaft Sinking - 911Metallurgist
Jun 4, 2017 · These include such items as muddy conditions, freezing of water in the shafts, added equipment maintenance, reduction in ground stability and ...
[63]
[PDF] Emergency Response Planning For Shaft Sinking
Modern shaft sinking utilizes mechanized mining methods using equipment such as electrical hydraulic jumbos. This includes electrical equipment, hydraulic ...
[64]
[PDF] Handbook for Methane Control in Mining - CDC Stacks
Limit fan shutdown times when workers are in the shaft to a maximum of 15 min. Monitor the methane level in the air during fan shutdowns. Gas sampling. Preshift ...
[65]
30 CFR Part 77 Subpart T -- Slope and Shaft Sinking - eCFR
A plan providing for the safety of workmen in each slope or shaft that is commenced or extended after June 30, 1971.Missing: definition | Show results with:definition
[66]
https://link.springer.com/article/10.1007/s12517-022-09469-6
[67]
Sequential stress control and delayed support in deep shaft ...
Feb 14, 2022 · Rock mass quality classification, RMR stability charts, and convergence-confinement theory information was combined to determine the time ...
[68]
A Primary Support Design for Deep Shaft Construction Based on the ...
Jul 14, 2022 · A new support scheme for the deep shaft is proposed, using long bolts to restrain severe deformations, metal mesh, and a double reinforcement bar to improve ...Missing: alignment | Show results with:alignment
[69]
Mitigating Groundwater Risk with Watertight Segmental Shaft ... - WSP
Jun 20, 2020 · Any water that leaks into a structure like a shaft usually needs to be actively managed so that the required environment can be maintained. In ...
[70]
Vertical Shaft Sinking Machine (VSM) - Herrenknecht AG
The simultaneous operations (excavation, muck removal, shaft lining, and sinking) enable sinking rates of up to 5 meters per shift with VSM technology.Missing: contamination prevention
[71]
Ballard Siphon Project - Herrenknecht AG
With a boring diameter of 9.8 meters, a 45 meter deep shaft was sunk at a rate of up to 2.6 meters per day. ... Safe and fast full-bottom shaft sinking to depths ...
[72]
Shaft Boring Roadheader (SBR) - Herrenknecht AG
The Shaft Boring Roadheader (SBR) was developed for the mechanized sinking of blind shafts in soft to medium-hard rock with up to 120 MPa.
[73]
Automation of ground control for mine shaft sinking – a step forward
Today, ground control during the sinking of mine shafts is usually assisted through numerical modelling. Prior to shaft sinking, the numerical model is ...
[74]
Equipment and Operations Automation in Mining: A Review
Oct 1, 2024 · This paper provides a comprehensive overview of the current state of automation in mining, examining the technological advancements, their applications,
[75]
Unreinforced slurry walls as temporary support of excavation for ...
Slurry walls, also known as diaphragm walls, are commonly used as temporary and/or permanent support of excavation for construction of shafts in soft ground ...Missing: sinking sustainable practices
[76]
Renewable energy in the mining industry: Status, opportunities and ...
This paper highlights the importance of integrating renewable energy (RE) into mining projects by a comprehensive review. •. The feasibility and application ...
[77]
Sustainable Mining Practices: A Look at New Innovations
Aug 29, 2024 · Mining companies can also achieve sustainable mining by integrating renewable energy sources. Mines switch increasingly to using clean energy ...Missing: shaft slurry walls
[78]
Rio Tinto completes Shaft 2 development at Oyu Tolgoi mine in ...
Nov 5, 2019 · Global mining group Rio Tinto has completed development of Shaft 2 at the Oyu Tolgoi mine in Mongolia. ... Oyu Tolgoi project by mid-2023.
[79]
Oyu Tolgoi Ranks No.1 on TOP-100 List for Third Consecutive Year
Jul 4, 2025 · In 2024, Oyu Tolgoi's skilled workforce successfully completed the development of Shaft 3 and Shaft 4—the world's largest ventilation shafts ...Missing: 2500m hybrid methods
[80]
Orica and Oyu Tolgoi partnership drives mining innovation and ...
Aug 21, 2025 · ... completion of a seven-year underground expansion in 2023, Oyu Tolgoi is now on track to become one of the top copper producers globally.