CHAPTER 6.2 Mining Methods Classification System L. Adler and S.D. ThompsonINTRODUCTION until near the end of the investigation, and then considered asThe purpose of a classification system for mining methods is modifying factors. This organization duplicates but tightensto provide an initial guideline for the preliminary selection of others (Hartman 1987).a suitable method or methods. Its significance is great as thischoice impinges on all future mine design decisions and, in SPATIAL DESCRIPTIONturn, on safety, economy, and the environment. Most mineral deposits have been geometrically characterized The choice of a mining method assumes a previous but as to an idealized shape, inclination, size, and depth. Complexcursory knowledge of the methods themselves. It also assumes or composite bodies are then composed of these elements.a brief understanding of ground control and of excavating and Ideal shapes are either tabular or massive, with chim-bulk handling equipment. In the formal mine design proce- neys (or pipes) being subordinated. Tabular deposits extenddure, the choice of mining methods immediately follows geo- at least hundreds of meters (feet) along two dimensions, andlogical and geotechnical studies, and feeds directly into the substantially less along a minor dimension. Massive bodiescrucial milestone diagram where regions of the property are are approximately unidimensional (cubic or spherical), beingdelineated as to prospective mining methods (Lineberry and at least hundreds of meters (feet) in three dimensions. A modi-Adler 1987). This step in turn just precedes the subjective, fication is recommended later to achieve closure with tabularcomplex, and critical layout and sequencing study. deposits. For tabular deposits, the inclination (attitude or dip) To develop the proposed classification system adopted and thickness are crucial. Inclinations range from flat to steephere, many existing ones (both domestic United States and (Table 6.2-2) (Hamrin 1980; Popov 1971).foreign) were examined and incorporated to varying degrees.The result is deemed more systematic, inclusive, and under-standable than its predecessors (i.e., Stoces 1966). Table 6.2-1 Input statement categories Subsequent parts of this handbook elaborate on the selec- Primary Categoriestion and comparison of mining methods. (Dependency) Secondary Categories Natural conditions GeographyINPUT STATEMENT (invariant) GeologyA comprehensive statement has been developed to provide a Economic engineeringrapid checklist of the many important input parameters (Adler Company capabilities Business administrationand Thompson 1987). The three major areas are (1) natural (variant) Monetary aspectsconditions, (2) company capabilities, and (3) public policy(Table 6.2-1). Those parameters appearing early are gener- Management aspectsally the most important. Natural conditions require that a dual Public policy Regulationsthrust be maintained concerning resource potentials and engi- (semivariant) Taxesneering capabilities. An additional basic distinction occurs Contractsbetween geography and geology. For company capabilities, Incentivesfiscal, engineering, and management resources must be recog- State of the art Salient distinctionsnized. This includes the scale of investment, profitability, and (mining engineering) Total systems (design/control)personnel skills and experience. Public policy must be consid- Encumbered (and regulated) spaceered, particularly as to governmental regulations (especially Full-spectrum practice (manage/evaluate)safety, health, and environmental), tax laws, and contract Professionalismstatus. Some of the latter input factors are held in abeyance L. Adler, Professor, West Virginia University, Morgantown, West Virginia, USA S.D. Thompson, Assistant Professor, University of Illinois at Urbana–Champaign, Illinois, USA 349
350 SME Mining Engineering HandbookTable 6.2-2 Tabular deposits classified by attitude and related to Table 6.2-5 Deposits classified by depthbulk handling and rock strength Deposit Depth Attitude UndergroundClass or Dip Bulk Handling Mode Rock Strength (a measure of overburden pressure)Flat ≤20° Use mobile equipment Weak rock (surficial) Class Coal Ore Surface (and conveyors) Shallow ≤61 m ≤305 m ≤61 mInclined 20–45° Use slashers (metal plate Average rock (200 ft) slope (1,000 ft) (200 ft) can also vibrate—as entries possible gravity slides) Moderate 122–244 m 305–457 m 61–305 mSteep ≥45° Gravity flow of bulk solids Strong rock (at depth) (400–800 ft) (1,000–1,500 ft) (200–1,000 ft) pillar problems Deep ≥915 m ≥1,830 m ≥305–915 mTable 6.2-3 Surface pit slopes related to rock strength and time (3,000 ft) bumps, (6,000 ft) (1,000–3,000 ft) burst, closure open pit Maximum Pit SlopeRock Short Term Long TermStrong 41°–45°(–70°)* 18°–20° Table 6.2-6 Deposit classified by geometry and typeAverage 30°–40° 15°–18° Geometric Class Deposit Type CommentsWeak (soils also) 15°–30° 10°–15° Tabular Alluvium (placer) Near surface—weak*Infrequently up to 70°. Flat and Coal (folded too) Weak country rock—an inclined erosion surfaceTable 6.2-4 Underground deposits classified by thickness Evaporites (domes too) Sedimentary Good country rock, thicker Deposit Thickness Metamorphic (folded too)Class Coal Ore Comments Steep Veins Can be weakened orTabular rehealed (gouge and Thin 0.9–1.2 m 0.9–1.8 m Low profile or narrow alteration) (3–4 ft) (3–6 ft) mine equipment Massive Igneous (magmatic) Strong Medium 1.2–2.4 m 1.8–4.6 m Post and stulls Disseminated ores Can be weakened (4–8 ft) (6–15 ft) ≤3.1 m (10 ft) Thick 2.4–4.6 m 4.6–15.3 m Small surface (8–15 ft) pillar (15–50 ft) can equipment; crib problems cave (steep dip) problems deposit tends to be treated as massive. Primarily in flat under-Massive ≥4.6 m ≥5.3 m Pillar problems ground deposits, thickness governs the possible equipment (15 ft) (50 ft) or poor recovery; benching necessary; height (low profile), and in steep ones its narrowness. Also, caving considered in underground mining, the deposit thickness becomes a sup- port problem, especially if effective pillars become so massive that recovery is compromised. When the upper limit of any In surface mining, the inclination limits the advanta- of these concerns is reached (e.g., benching, equipment size,geous possibility of being able to cast waste material nearby, and pillar bulk), closure with massive deposits occurs for allas opposed to hauling it a distance and then storing it. For flat practical purposes. Pillar size vs. recovery can dictate cavingdeposits, especially when fairly shallow, an area can be suc- except where pillar sizes may be decreased because backfill-cessively opened up and the waste can then be cast into the ing is used, such as in postpillar cut-and-fill.previously mined-out strips, a substantial economic advan- Finally, the depth below the ground surface is impor-tage. Casting, in its normal sense, is not restricted to the use of tant (Table 6.2-5) (Popov 1971; Stefanko 1983). For surfacerotating excavators; broadly, it means relatively short-distance deposits, even flat ones, this can obviate casting and requirehauling of waste, which can also be done with mobile loaders increased waste haulage and expanded dump sites. For under-and/or trucks or with mobile bridge conveyors. For steeper ground mining, earth pressures usually increase with depth,(and deeper) deposits, stable pit slopes become important consequently raising the support needs. The ground surface(Table 6.2-3) (Hartman 1987; Popov 1971). Where the deposit location above a deposit must be clearly identified to evaluateinclination exceeds that of the stable slope, both the hanging other parameters (see “Input Statement” section previously).wall and footwall must be excavated and the increased wastethen handled and placed. CORRELATING DEPOSIT TYPES For both surface and underground mining methods, the The inclination (dip) can be roughly related to the depositinclination cutoff values nearly coincide (one for pit slopes, the type (Table 6.2-6). Rocks can also be related to strengthother for face bulk handling mechanisms, whether mechanical (Table 6.2-7) (Hartman 1987). The strength of the deposit andor by gravity). While not identical, they are close enough to its envelope of country rock can then be related to its typeuse similar values (20° and 45°; see Table 6.2-2). (Table 6.2-8). For determining pit slopes, (surface mining) The thickness of a tabular deposit is also important and support requirements (underground mining), these rela-(Table 6.2-4), with reference primarily to underground work tionships become important. Some variations are noted, espe-(Popov 1971). When three or more benches are required, the cially for veins and disseminated deposits.
Mining Methods Classification System 351CLASSIFYING SURFACE MINING METHODS Depth Related to Excavating Technique and Stripping RatioDepth Related to Inclination Because of the effects of weathering and stress release, exca-The surface mining classification, although based on the cru- vating becomes more difficult and expensive with depth,cial ability to cast waste material rather than to haul it, has following a continuum from hydraulic action and scoopingother features. These are primarily based on the depth of the through to blasting (Hartman 1987).deposit being a function of its inclination. Flat seams tend to As a matter of definition, the stripping ratio (ratio ofbe shallow, and casting is possible; steep and massive deposits waste to mineral) usually increases with depth. However,trend to depth. From this, a number of relationships result. the relatively inexpensive handling of waste near the surface by casting tends to mitigate this increase, permitting higher ratios. The use of mobile, cross-pit, high-angle conveyingTable 6.2-7 Rocks classified by strength allows greater pit depths and, along with the mineral value, also influences this ratio.Class Compressive Strength ExamplesWeak ≤41.3 MPa (6,000 psi) Coal, weathered rock, Surface Mining Classification System alluvium Based on the foregoing factors, a surface mining classificationModerate 41.3–137.9 MPa Shale, sandstone, limestone, has been developed (Table 6.2-9). The classification incorpo- (6,000–20,000 psi) schist rates information dependent on the intrinsic characteristics of Evaporites, disseminated deposit the geometry of the deposit. Quarrying appears to be anoma- lous because of (1) relatively steeper pit slopes, (2) special-Strong 137.9–206.8 MPa Metamorphic, igneous, veins, (20,000–30,000 psi) marble, slate ized means of excavating and handling, and (3) less critical amount of overburden. “Glory hole” mining or its equivalentVery strong ≥206.8 MPa (30,000 psi) Quartzite, basalt, diabase is making a comeback in very deep open pits using inclinedTable 6.2-8 Deposits related to geometry, genesis, and strength (in order of induration) Strength and Stiffness,Deposits Type Geometry Genesis Deposit/Country Rock ExamplesAlluvium (placers) Tabular-flat Surface-stream action deposition Poor/poor Sand and gravel; precious metals (fans, deltas, meanders, braids) and stones (tin)Erosion surface (swamps) Tabular-flat and thin Swamps (possible dynamic Poor/poor to good Coal (possible folding) metamorphism)Disseminated Massive Underground channels and Poor/poor Hydrothermal ores (porphyry multifaceted advance coppers and sulfides)Vein (can be rehealed) Tabular-inclined (pipes, Major underground channels Poor to good/good Hydrothermal ores (porphyry chimney shoots) (fissures), gouge, alteration (reheal) coppers and sulfides)Evaporites Tabular-flat-thick Interior drainage Good/good Salt, phosphatesSedimentary (bedded) Tabular-flat-thick Shallow seas Good/good Limestone, sandstoneMetamorphic Tabular-flat-thick Dynamic and/or thermal Good/good Marble, slateIgneous (magnetic) Massive Plutonic emplacement Good/good Granite, basalt, diabaseTable 6.2-9 Classification of surface mining methods ExcavationShape, DepositAttitude (dip) Characteristics Stripping Ratio Waste Handling Excavation Mining MethodTabular Flat Near surface Low Onsite Hydraulic, scoop, dig Placers—hydrosluicing, dredging, solution—at depth Shallow Moderate Cast Scoop, dig, light blast Open cast (strip)—area, contour, mountain top Inclined Moderate Moderate (remove Need highwall Auger Auger hanging wall) Haul (to waste dump) Blast Open pit Deep High (remove both Haul (to waste dump) — Open pit hanging wall and footwalls) Saw, jet pierce (joints) QuarryMassive Full range Depends on depth Haul (to waste dump) — Open pit; glory holeNote: In-situ mining is always possible.
352 SME Mining Engineering HandbookTable 6.2-10 Structural components located and described for underground miningComponent (time dependent) Location/(Material) Loaded by Supported by CommentsRoof (can deteriorate, slough, Back and hanging wall Main roof—all, especially Pillars and fill, also arched Spans ~3 m (10 ft) for coal toslake—dry and crumble) (envelope) overburden (cap rock) (1/5) 30.5 m (100 ft) for rock Immediate roof—body Artificial supports can remove Spans ~3.1 m (10 ft) (stand-up time)Pillars and walls (can Sides, deposit and waste All—especially overburden Floor Critical:deteriorate—slough, slake) (horses mainly deposit) 1. Stiffness: (slenderness ratio: approximately 10/1 [coal] to 1/3 [rock]) 2. Strength (material) 3. Percentage recoveryFloor (can settle and heave) Footwall (envelope) All—through pillar watch Country rock can be Critical: water compacted, removed, drained 1. Stiffness 2. Strength (bearing capacity especially if water) 3. Heave (deep-seated)Fill (for permanent stability) Crushed waste, sand, water All—especially as pillars Footwall and floor Good mainly to support hanging are removed wall. Requires greater than angle of slide and confinement.Artificial support (limited time) External: Timber (props, sets, Mainly immediate roof Floor Deterioration (chemical and cribs, stulls, posts); concrete stress) gunite (mesh) Internal: Bolts (headers), Mainly immediate roof Anchorage in roof, etc. Anchorage a concern trusses, cables, grout, cementationhoisting. Glory hole mining utilizes a single large-diameter Ground Controlraise located in the lowest point of the pit, down which all Ground control requires knowledge of the structure (opening),blasted material is dumped. The bottom of the hole feeds material (rock), and loads (pressures). Structural componentsinto crushers and a conveying system, which transports the are detailed in Table 6.2-10. Earlier tables detailed the depositmaterial to the surface through a horizontal or inclined drift by its depth and detailed rocks by strength (Tables 6.2-5 and(Darling 1989). 6.2-7, respectively). From the point of view of support, the In contrast to the underground classification, the surface roof, pillars, and fill are of primary concern.one is not formed into a matrix. This is because depth andtherefore the excavating technique, waste handling, and strip- Main Roofping ratio are all functionally related to the deposit geometry, The main roof (sometimes the hanging wall) is distinguishedparticularly the seam inclination. No preceding classification from the immediate roof by being the critical load transferringrecognizes this relationship (Hartman 1987; Lewis and Clark element between the overburden and pillars. The immediate1964; Morrison and Russell 1973; Stout 1980; Thomas 1973). roof can be removed (mined out) or supported artificially and lightly. The main roof is defined as the first close-in, compe-CLASSIFYING UNDERGROUND MINING METHODS tent (strong) seam. If it is only marginally competent, heavyNormally, two major independent parameters will be consid- artificial support may keep it stable; if not, then caving can beered that form a matrix, unlike for surface methods. These two expected. For a flat seam, the vertical (perpendicular) loads onparameters are (1) the basic deposit geometry, as for surface the main roof are largely due to the overburden and its ownmethods, and (2) the support requirement necessary to mine body load. Horizontal (tangential) loads or pressures will tendstable stopes, or to produce caving, a ground control prob- to be uniformly distributed, resulting in a low stress concentra-lem (Boshkov and Wright 1973; Hamrin 1980; Hartman 1987; tion. If bed separation occurs above the main roof, this stressLewis and Clark 1964; Thomas 1973). uniformity is enhanced; but at depth, overburden loading tends to decrease separation. Body loads are invariant, whereasDeposit Geometry edge loads—particularly those due to the overburden—Deposit geometry employs the same cutoff points for tabular can be shifted (pressure arching). The main roof is often suf-deposits as in the surface classification, but for different rea- ficiently thick so that it can be arched below 1/5 (i.e., at lesssons. Flat deposits require machine handling of the bulk solid than 1 horizontally and 5 vertically) to increase stability. Aat or near the face; steep ones can exploit gravity (Table 6.2-2), guideline for coal is that stable spans are usually less thanwith an intermediate inclination recognized. If stopes are 3 m (10 ft), whereas for hard rock they are generally less thandeveloped on-strike in steep seams as “large tunnel sections” 30 m (98 ft).or “step rooms” (Hamrin 1980), machine handling can still be For an inclined seam, the main roof is the hanging wall,used. The resulting stepped configuration causes either dilu- and the results are similar to a flat seam. Pressures perpen-tion or decreased recovery, or both. Because this face can also dicular to it are more significant then tangential ones, and bedbe benched, stope mining simply reproduces tunneling. separation due to gravity is less likely.
Mining Methods Classification System 353Table 6.2-11 Deposit and structural components related to underground mining methods Structural Main Components RatedDeposit Geometry Roof and Floor (pillars, walls)* Underground Mining Methods TypeTabular Flat (and inclined) Good Good Room-and-pillar (spans ≤6 m [20 ft]); Self-supported stope-and-pillar (spans ≤31 m [100 ft]) Good Poor Room-and-pillar; stope-and-pillar Supported Poor (roof collapses about Good Longwall; pillaring Caved free-standing pillars) Poor Poor Immediately above Caved Steep Good Good Sublevel stoping (spans 6–31 m [20–100 ft]); Self-supported then filled large tunnel section Good Poor Hydraulicking—coal (spans 6–21-m [20–70-ft] arch); Supported then filled shrinkage Poor Good Cut-and-fill Poor Poor Sublevel caving and top slice spans ≥6 m (20 ft) Caved (for gravity flow)Massive Good Good Vertical slices† Self-supported Good Poor Vertical slices Supported then filled Poor (cap rock) Poor Block caving (spans ~34 m [110 ft] active— end stope used)*Rated as to strength (and stiffness of pillar).†Horizontal slices can introduce the many problems associated with multiple-seam mining.Pillars mining. Because of settlement and shrinkage away from a flatPillars serve to support the main roof and its loads, primar- back, it is marginally useful for flat deposits.ily the overburden acting over a tributary area. Pillar material When timbering is densely placed, especially with squareconsists mainly of the seam itself and sometimes waste incor- sets, it rivals pillars. It, too, is usually filled as stoping pro-porated within the seam. Pillars must not only be sufficiently gresses (overhand mining). These relationships are summa-strong but also must be sufficiently stiff, a frequently over- rized in Table 6.2-11 and lead into the formal classification.looked requirement. If pillars are not adequately stiff, but stilladequately strong, the roof will collapse about the still free- Underground Mining Classification Systemstanding pillars, especially when differential pillar (and floor) Based on an understanding of bulk handling and grounddeflection occurs. The minimum slenderness ratio for pillars to control, the underground classification system shown inavoid this crippling is inversely proportional to the recovery. Table 6.2-12 closely follows previous ones. The primary dif-The mining of flat, thick seams of coal dramatically reflects ference is that sometimes shrinkage stoping is consideredthis relationship and is a factor in classifying seam thicknesses self-supported rather than supported. However, although the(Table 6.2-4). For massive deposits, even in strong rock, this broken mineral provides a working floor, it is still supportingmakes freestanding pillars of doubtful value. Upper slender- the hanging wall (roof). On the other hand, when the stopeness ratios range from about 10/1 for coal to 1/3 for rock. is drawn empty, it remains substantially self-supported untilContinuous vertical pillars are used to separate vertical stopes fill is introduced. The disadvantages of the shrinkage methodin hard rock that employ steep, tabular stoping methods. Even are unique: (1) an uncertain working floor, (2) dilution duewith stable ground, these are usually filled soon after mining to sloughing and falls of rock, (3) possibly adverse chemicalfor long-term stability. When massive deposits along with effects, and (4) tying up about two-thirds of the mineral untiltheir cap rock are weak, caving is necessitated, usually per- the stope is drawn.formed as horizontal lifts or as block caving. Caving always Vertical crater retreat mining is included in the classifica-requires a sufficient span 9 m (30 ft), good draw control, and tion between sublevel and shrinkage stoping (Hamrin 1980).also risks dilution and/or poor recovery. Soft or nonuniformfloors (footwalls) act the same as do soft and irregular pillars. OTHER FACTORS While subordinated, there are additional factors that must beFill closely evaluated. These deal with the broad impacts on theFill, often a sandy slurry consisting of crushed waste, cement, environment, health and safety, costs, output rate, and oth-and water, can be readily introduced into confined (plugged), ers. They are usually evaluated on a relative basis, althoughinclined, and steep tabular stopes. When drained and dried, numbers may also be employed (Table 6.2-13) (Boshkovthis hardened slurry provides permanent resistance to ground and Wright 1973; Hartman 1987). An example of wheremovement, especially for the walls or pillars. It is widely used the environmental considerations on the surface are begin-in all but the caving methods. It is either run in progressively ning to affect mining methods is in the use of high-densityas a stope is mined out or done all at once at the end of stope paste backfilling in order to return most of the tailings back
354 SME Mining Engineering HandbookTable 6.2-12 Classification of underground mining methods based on deposit geometry and support Degree of SupportDeposit Shape, Attitude (dip) Unsupported (open stopes) Supported CavedTabular Flat (mobile bulk handling) Room-and-pillar; stope-and-pillar Some degree of artificial support for Longwall (shortwall); pillaring (especially room-and-pillar and stope-and-pillar room-and-pillar) Inclined (mixed bulk handling) Above with scrapers Above with scrapers Longwall (difficult) Large tunnel section (on-strike) Large tunnel section with artificial support Steep (gravity bulk handling) Coal hydraulicking Shrinkage stoping; cut-and-fill stoping Sublevel caving Sublevel stoping Timbered stoping (square sets, stulls, Top slicing (control dilution-and-recovery) gravity) Vertical crater retreat Fill as needed Shrinkage stoping Gravity fill as neededMassive Immediately above mine in vertical slices. Immediately above in horizontal lifts Fill—gravity placement. block caving (bulk mining) To remove pillars, can mine and then fill horizontal lifts.**For ground control problems, especially those associated with coal, treat as if they were to be extracted by thick-seam and/or multiple-seam mining. As pressure increases (especially with depth), or as rock strength decreases, shift right for suitable method (toward supported and caved).Table 6.2-13 Secondary factors to be considered when selecting a mining method Output (t/h) and Relative Flexibility/ % Recovery/ ProductivityMethod Cost Selectivity % Dilution Environment Safety and Health (t/employee) Miscellaneous Surface MiningPlacers and 0.05 Low/high High/low High impact, and water Fair Moderate Need water; impact ofdredging pollution weatherOpen-cast 0.10 Moderate/ High/low Blasting can lead to frequent Fair High Flat topography and moderate claims and water pollution impact of weatherOpen-pit 0.10 Moderate/ High/low Ground disturbance, waste Slope stability (slides) High Impact of weather moderate piles, and some water problemsQuarry 1.00 Low/high High/high Ground disturbance and Slope stability Very low Skilled workers and waste piles impact of weather Underground MiningRoom-and-pillar 0.30 High/high 50–80/20 Subsidence and water Ground control and High Pillaring common(coal) pollution ventilationStope-and-pillar 0.30 High/high 75/15 Good Ground control and High Benching common ventilationSublevel stope 0.40 Low/low 75/15 Fill to avoid subsidence Less, blast from long Moderate Fill common holesShrinkage 0.50 Moderate/ 80/10 Fill to avoid subsidence Poor floor (collapse) Low Tie up 2⁄3 of ore moderate plucking and stored broken during draw mineral*Cut-and-fill 0.60 Moderate/ 100/0 Fill to avoid subsidence Some Low Sort in stope highTimbered 1.00 Moderate/ 100/0 Fill to avoid subsidence Smolder, and fall (of Very low Sort in stopesquare set high personnel)Longwall 0.20 Low/low 80/10 Subsidence and water Good Very high High capital ≤12° dip pollution ≤2.4 m (8 ft) thickSublevel caving 0.50 Low/low 90/20 Severe subsidence disruption Fair and stored broken High Cave width ≥9.2 m(top slicing) mineral* (30 ft)Block caving 0.20 Low/low 90/20 Severe subsidence disruption Air blasts and stored High Tie up mineral broken mineral**Can pack (cement), oxidize, and smolder.
Mining Methods Classification System 355underground (in order to obtain mining permits from environ- Hamrin, H. 1980. Guide to Underground Mining. Stockholm:mental agencies). Atlas Copco. pp. 12–31. In addition, innovation is always occurring and some Hartman, H.L. 1987. Introductory Mining Engineering. Newis currently of proven value. These include rapid excava- York: Wiley.tion, methane drainage, underground gasification, and retort- Lewis, R.S., and Clark, G.B. 1964. Elements of Mining, 3rding (Hartman 1987). Many methods are now automated and ed. New York: Wiley. pp. 378–403, 404–416.robotized. Lineberry, G.T., and Adler, L. 1987. A procedure for mine design. SME Preprint 87-48. Littleton, CO: SME.ACKNOWLEDGMENTS Morrison, R.G.K., and Russell, P.L. 1973. Classification ofThis chapter has been revised from the corresponding chapter mineral deposits and rock materials. In SME Miningin the previous edition of this handbook. Engineering Handbook. Edited by A.B. Cummins and I.A. Given. New York: SME-AIME. pp. 9-2–9-22.REFERENCES Popov, G. 1971. The Working of Mineral Deposits. TranslatedAdler, L., and Thompson, S.D. 1987. Comprehensive input by V. Shiffer. Moscow: MIR Publishers. statement for mine design. SME Preprint 87-71. Littleton, Stefanko, R. 1983. Coal Mining Technology: Theory and CO: SME Practice. Edited by C.J. Bise. New York: SME-AIME.Boshkov, S.H., and Wright, F.D. 1973. Basic and parametric pp. 52, 84–87. criteria in the selection, design and development of under- Stoces, B. 1966. Atlas of Mining Methods. Prague: UNESCO. ground mining systems. In SME Mining Engineering Stout, K. 1980. Mining Methods and Equipment. New York: Handbook. Edited by A.B. Cummins and I.A. Given. McGraw-Hill. New York: SME-AIME. pp. 12-2–12-13. Thomas, L.J. 1973. An Introduction to Mining. New York:Darling, P.G. 1989. Glensanda: A “super quarry” for the Halsted Press (Wiley). future. Int. Min. Mag. (May): 31–36.