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This third edition of the SME Mining Engineering Handbook reaffirms its international reputation as "the handbook of choice" for today's practicing mining engineer. It distills the body of knowledge that characterizes mining engineering as a disciplinary field and has subsequently helped to inspire and inform generations of mining professionals. Virtually all of the information is original content, representing the latest information from more than 250 internationally recognized mining industry experts. Within the handbook's 115 thought-provoking chapters are current topics relevant to today's mining professional: Analyzing how the mining and minerals industry will develop over the medium and long term—why such changes are inevitable, what this will mean in terms of challenges, and how they could be managed Explaining the mechanics associated with the multifaceted world of mine and mineral economics, from the decisions associated with how best to finance a single piece of high-value equipment to the long-term cash-flow issues associated with mine planning at a mature operation Describing the recent and ongoing technical initiatives and engineering developments in relation to robotics, automation, acid rock drainage, block caving optimization, or process dewatering methods Examining in detail the methods and equipment available to achieve efficient, predictable, and safe rock breaking Identifying the salient points that dictate which is the safest, most efficient, and most versatile extraction method to employ, as well as describing in detail how each alternative is engineered Discussing the impacts that social and environmental issues have on mining from the pre-exploration phase to end-of-mine issues and beyond, and how to manage these two increasingly important factors to the benefit of both the mining companies and other stakeholders
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389
CHAPTER 29 [7.4]
Soft‑Rock (Underground) Mining:
Selection Methods
Antonio Nieto
INTRODUCTION
The soft rocks usually are part of the sedimentary minerals
classication, which is subdivided into clastic, organic, and
chemical. Examples of the soft-rock ores include coal, met-
alliferous shales, oil shales, potash, salt, trona, and possibly
kimberlites. Where coal, metalliferous shales, potash, and
trona occur as economic ores, they are typically laterally
extensive beds in a nearly horizontal inclination but with, at
most, a shallow dip angle. This differentiation is key, because
it enables the application of large-scale mechanization to the
mining process. The economy of scale that results from mech-
anization is often the determinant factor for economic success.
As the capabilities of mechanical cutting expand into more
demanding applications, the possibility exists that ores pre-
viously considered hard-rock deposits, such as the platinum-
bearing reefs in southern Africa, may be cut instead of blasted.
Coal has its origins in the accumulation of plant debris
that becomes buried by sediments. Through a process depen-
dent on time, burial depth, and chemical transformation, the
plant debris becomes coal. Therefore, coal is classied as an
organic sedimentary mineral. Coal varies in quality from lig-
nite to anthracite, with sub-bituminous and bituminous ranked
as intermediate in the progression and the most commonly
mined types worldwide.
Coal is primarily used for electricity generation and steel-
making and is commonly referred to, respectively, as steam
coal and coking coal. Coal with attributes such as an appre-
ciable free-swelling index (FSI) is used to make coke, which
is used in primary production of steel from iron ore. The scar-
city of such coals elevates their value compared to steam coal.
Trona is a carbonate mineral of sodium used to form
soda ash, used in glassmaking and other industrial processes,
including baking soda. It occurs naturally in a few locations
worldwide as laterally extensive evaporate deposits, suitable
for underground mining methods. It is a moderate value ore
and competes with an alternative process that synthesizes the
same product from chemical feedstocks.
Potash is the name loosely applied to a variety of potassium
salts, particularly potassium chloride, which are encountered in
laterally extensive evaporate deposits found worldwide. These
are often associated with intermixed or stratigraphically adja-
cent halite (sodium chloride). Potassium is key to plant growth,
and potash is mainly used as fertilizer, although it is also used
to produce soaps, ceramics, and drugs, among others.
Coal, potash, trona, and salt are the principal soft-rock
ores and, within limits, share similar production methods
that focus on economies of scale. The most common mining
techniques for soft-rock ores are longwall, room-and-pillar
(R&P), and stope-and-pillar. For water-soluble minerals, solu-
tion mining is an alternative. The process of properly selecting
an underground mining method for a particular ore deposit is
critical to the ultimate success of the operation. An improperly
selected method will increase costs, lower productivity, create
unnecessary hazards, and reduce resource recovery. Due to the
complex nature of ore bodies, no two mines are completely
alike, and all operations must adapt to the particular condi-
tions of their deposits.
ORE DEPOSIT CHARACTERISTICS
Numerous considerations must to be recognized when select-
ing the best method to mine a soft-rock ore deposit. Some of
the considerations are based on ore deposit characteristics
favorable to the mining method being considered:
• Ore strength
• Host rock strength
• Deposit shape
• Deposit dip
• Deposit size
• Deposit thickness
• Deposit grade
• Ore uniformity
• Deposit depth
Other characteristics are a function of mining method:
• Operating cost
• Capital cost and development timing
• Production rate
• Mechanization
• Selectivity and exibility
Antonio Nieto, Associate Professor, Mining Engineering Department, Penn State University, PA, USA
390 SME Mining Engineering Handbook
• Health and safety
• Environmental effects
Ore Strength
The material properties of the ore often drive mine design
decisions. Although there are many mechanical properties,
compressive strength is often discussed as an indicative
characteristic inferring structural performance and suitabil-
ity for mechanical cutting. Mining methods such as R&P and
stope-and-pillar depend on the strength of the ore rock to
support the roof and overburden in order to create a struc-
turally stable excavation. In soft-rock applications, the rela-
tive strength of the ore is often weak, with a compressive
strength less than 6,000 psi. This low strength is generally
associated with a low to moderate specic energy of cutting
(kilowatt-hour/ton). This allows the application of mecha-
nized cutting and loading, which is elemental to the success
of many modern mines. As the ore strength increases, the
options for mechanical cutting are reduced, and the appli-
cation productivity declines while costs increase. There is
a marked difference between the cost and productivity per-
formance of mechanized cutting versus drilling and blasting
in the majority of soft-rock applications, with mechanized
methods decidedly preferred.
Table 29-1 gives the strength designations and ranges of
values based on the compressive strength of the material.
It is important to note that the strength and mechanical
properties of a rock are signicantly affected by fracturing and
planes of weakness in the deposit. Fracturing is characterized
by small discontinuities in the rock mass and may be caused by
heat, vapor expansion (as in porphyry deposits), depositional
conditions (i.e., slickensides), or tectonic movement (faults).
Cleat is a fracture system ordinarily observed in coal. Two dif-
ferent fracture directions are typically present: face cleat (pri-
mary direction) and butt cleat (secondary direction). During
exploration, the degree of fracturing should be quantied and
utilized to reduce ore structural properties, potentially lead-
ing to smaller openings, larger pillars, and increased ground
control costs. Limited fracturing may be a positive factor for
some mining methods, because it promotes caving, lowers
blasting requirements, and aids mechanical cutting. However,
excessive fracturing can have a negative inuence on ground
control, water, and gas inows.
Host Rock Strength
The strength of the rock enclosing the ore is also an important
driver in mining method selection. Temporary and permanent
openings must be developed either in the host rock, in order to
access the ore, or with the host rock as roof (back or hanging
wall) or oor (footwall) for the ore openings (entries or cross-
cuts). To execute an appropriate design, the material properties
must be understood. The behavior of the roof and oor can be
pivotal in the success of mechanized mining systems. Floors
that become muddy and easily rutted can disable production
and send maintenance costs skyrocketing.
It is inaccurate to assume that the ore and host material
will have the same characteristics, so each must be indepen-
dently characterized by geomechanical testing.
Deposit Shape
Ore deposits are classied into two broad categories: tabu-
lar and massive. A tabular deposit is at and thin, and has a
broad horizontal extent. This classication typically refers to
materials formed by sedimentation. Similar in shape to tabular
ore bodies, lenticular deposits are shaped like lenses and lack
the large areal extent of most tabular deposits. Most methods
designed to exploit tabular deposits may be adapted to mine
lenticular ones. The ore materials must often be of higher
value than applications such as coal, because production costs
are generally higher but reserve tonnages are lower.
A massive deposit may possess any shape. The ore is often
distributed in low concentrations over a wide area with vary-
ing horizontal and vertical extents. Frequently, the difference
between ore and waste may be a function of grade rather than
rock type. Massive deposits may be unpredictable and require
a considerable exploration investment in order to document and
fully understand the resource. For the purposes of mining method
selection, massive deposits are often accompanied by a more
specic clause like "massive with large vertical extent." These
additions are necessary because the shape of a massive deposit is
variable and may be unsuitable for certain mining methods. The
deposit shape denitions are summarized in Table 29-2.
Deposit Dip
Dip is dened as the angle of inclination of a plane measured
downward, perpendicular to the strike direction. The deposit
dip is more relevant to tabular ore bodies than massive ones,
although it may sometimes be a consideration for the latter.
Deposit dips are categorized and dened in Table 29-3.
Both at-lying soft-rock ore beds, and near-vertical ore
veins may be classied as tabular, but the mining methods
used to exploit them are dramatically different. Several meth-
ods are highly dependent on gravity for material ow and can-
not function in at-lying deposits. Alternatively, low working
slopes are a key factor in the application of mechanization
for cutting and loading as well as material haulage by rubber-
tired, rail, or conveyor-belt methods.
Table 29‑1. Ore strength definitions
Relative Strength Example Material Compressive Strength, psi
Very weak Coal <6 , 000
Weak Shale, siltstone, sandstone 6 ,000–14, 500
Moderate Limestone and sandstone 14 ,500–20, 000
Strong Granite 20 ,000–32,000
Very strong Quartzite >32 , 000
Table 29‑2. Deposit shape definitions
Deposit Type Shape Width Extent
Tabular Flat Thin to moderate Horizontal
Lenticular Flat, elliptical Thin to moderate Horizontal
Massive Any Thin to thick Horizontal and vertical
Table 29‑3. Deposit orientation definitions
Inclination Category Dip Angle, degrees
Low 0 –5
Moderate 5 – 25
Fairly steep 25 – 45
Steep 45 –90
Soft‑Rock (Underground) Mining: Selection Methods 391
Deposit Size
The volumetric size of an ore body must also be considered.
Several of the methods discussed in this chapter rely on large
deposits with long mine lives to justify their high initial capi-
tal costs and promote economies of scale. Other methods sim-
ply do not work efciently in ore bodies, which are either too
large or too small. Deposit size is characterized subjectively
by the terms small , medium, and large. As a generalization,
large ore deposits have tens to hundreds of million cubic yards
of ore and suggest mine lives in the 10- to 50-year range.
Deposit Thickness
Deposit thickness refers to the ore thickness of tabular depos-
its. Thickness plays an important role in opening stability and
may prevent certain equipment from functioning efciently or
mining methods from being effective. The deposit thickness
(nominally the mining extraction height) denitions are listed
in Table 29-4. These denitions are most relevant to mechani-
cal cutting and loading applications, such as longwall or con-
tinuous miner R&P. The thickness ranges roughly correlate
with the types of equipment available to implement a mining
system and the cost/productivity that might be expected.
Deposit Grade
Grade is discussed in terms of the amount/value of recover-
able/salable material in a unit weight or volume of in-place
mineral resource. Where it becomes economically viable to
produce the mineral resource, the in-place resource becomes
ore. As such, the end-outcome economics of different mining
methods may vary the amount of ore that an in-place min-
eral resource may yield. A gold ore may contain as low as
0.1 oz/ton and still be economic, whereas iron ore grades may
approach 60% by weight. Coal is generally characterized by
its attributes—that is, energy content (Btu/lb); percentage of
ash, moisture, and sulfur; FSI; and so forth. Some mining
methods with high operating costs necessitate high-grade ores
in order to be economic. Large-scale methods may be suitable
for large, low-grade deposits, such as bituminous coals. Ore
grades are categorized subjectively and must be investigated
on an individual site basis. Ore grade denitions are provided
in Table 29-5. Value estimates associated with the classica-
tions give some relative sense of the range involved.
Ore Uniformity
The uniformity of the ore in the mineral deposit must be con-
sidered, as poor uniformity may render some mining methods
unviable. It is undesirable to excavate subeconomic material,
unless it is necessary to reach ore or create necessary infra-
structure, such as belt-conveyor galleries. A mineral deposit
may be segmented by faults, subeconomic mineral occur-
rence, or legal/environmental issues. Some mining methods
are well suited to exibility because they can selectively
extract specic sections of a deposit without disrupting the
overall operation. An example of this is the case where an
R&P coal mine adapts the panel geometry while in panel to
reect new ndings about unsatisfactory coal quality, adverse
roof conditions, or insufcient coal thickness.
Other methods, such as longwall mining, limit selectiv-
ity and must produce at least some amount of material lead-
ing to equipment advance in order to continue to the panel's
intended end. Faults with signicant displacements compared
to the bed thickness can seriously disrupt longwall or R&P
operations. In some areas, igneous or sedimentary materials
may be injected into tabular deposits, such as dolerite dykes
in coal seams, and create impediments to mechanized cutting
and loading. An inconsistent feed of material may disrupt pro-
cessing plant performance or require blending, rehandling, or
disposal of mined material. These situations can be anticipated
and minimized with a thorough knowledge of the ore body's
uniformity. Ore uniformity designations are
• Variable,
• Moderate,
• Fairly uniform, and
• Uniform.
Deposit Depth
Another deposit-related consideration that impacts mining
method selection is ore deposit depth relative to the surface.
Shallow deposits are generally more suited for surface min-
ing. Deeper deposits may require progressively greater ground
control measures (increased costs), larger pillar sizes (lower
recovery), or decreased applicability of some mining methods
in order to ensure safety and sustainability. Commonly applied
variations of R&P or longwall mining occur over deposit
depth ranges from 250 to 3,500 ft. The denition of shallow/
moderate/deep is relative depending on the value of the ore
and the strength of the material. A deep coal mine might have
workings to a depth of 3,500–4,500 ft. Alternatively, a deep
gold mine producing from a meta-quartzite reef might have
workings to nearly triple that depth. Classication for deposit
depths are shallow, moderate, and deep.
MINING METHOD CHARACTERISTICS
Every mining method has characteristics that will produce
different outcomes based on the ore deposit to be mined. As
such, prior to selecting the best mining method, the methods
to be applied and their expected outcomes must be clearly
understood.
Operating Cost
The operating cost of a mine is the cost associated with the
production of ore from the primary mining method. The total
cost is higher and incorporates items such as depreciation,
depletion, taxes, and royalties. The operating cost divided by
the number of salable units of production mined creates a met-
ric used to compare efciency between competing production
alternatives—that is, $/ton. When the total cost is the basis of
the metric, it can indicate the potential viability of the project
Table 29‑4. Tabular deposit thickness definitions
Deposit Thickness (T)
Thin (small) T < 5 ft
Moderate 5ft < T < 12 ft
Fairly thick 12 ft < T < 20 ft
Thick (large) T > 20 ft
Table 29‑5. Ore grade definitions
Grade $/ton
Low 10 –50
Moderate 50 –250
High >250
392 SME Mining Engineering Handbook
in total. In mining, the operating cost is composed of xed and
variable expenses. Variable expense totals change in proportion
with activity, such as roof-control cost ($/ft) that typically accu-
mulates with the amount of entry development. In comparison,
xed costs, such as labor and ventilation, stay relatively con-
stant over a moderate range of activity variation. Some methods
are labor intensive or may require a large quantity of materials
in order to operate, thereby necessitating valuable ores to com-
pensate for the greater price of extracting them. Other methods
cost little once implemented but have high initial capital costs.
These methods, such as longwall mining, may be able to exca-
vate large low-grade deposits economically.
Capital Cost and Development Timing
Initial capital cost is dened as the amount of investment
needed before the mine begins to generate revenue. A small
quarry excavating an outcropping limestone bed has little cap-
ital cost because it can start extracting ore almost immediately
with little investment in equipment. Alternatively, a deep pot-
ash mine might have to sink one or more shafts beyond a depth
of 3,000 ft, build a surface plant, and implement a mechanized
mining equipment eet to produce the rst salable ton of prod-
uct. Thus, rst production may come after several years and
tens to hundreds of million dollars have been committed.
Higher capital costs are frequently associated with long
development or start-up times. Equipment manufacturers
often have wait times of months or even years before assem-
bly and delivery of new equipment. Typically, this equipment
is customized for the mine-specic application.
Production Rate
The production rate of a mine is highly dependent on the min-
ing method. A high production rate can accommodate a large
market and may overcome low-value ore if operating costs are
low. The ability to stockpile and blend ores of varying grade
in order to maintain a consistent feed to the mill is typically
advantageous. Higher production is generally more desirable
because mines are rarely opened in areas where selling more
product is disadvantageous. The economics of mines that
can sell product up to the limit of their production capacity
are drastically different than mines that can produce at lev-
els above what their markets can consume. In the latter case,
production enhancement proposals readily embraced by the
former case, intended to distribute xed costs over a larger
total production, are rejected, and the focus sharpens on costs
contributing to the xed component of operating cost.
Mechanization
Mechanization is a critical element of a modern mine.
Utilizing machines to perform production tasks is much safer
and more efcient, in cost or production performance, than
using manual labor. To justify a large capital investment in
equipment, it is common to need a longer mine life and thus a
larger ore body. Highly mechanized mining is safer than less
mechanized methods because fewer workers will be needed
and thus the overall hazard exposure will be lower. Several
methods lend themselves to a high degree of mechanization,
including longwall and continuous miner R&P methods.
Selectivity and Flexibility
Selectivity and exibility can signicantly contribute to the
success of a mining method. It is generally valid to assume
that mining conditions, market prices, and technology will
change over the course of a mine's life, so the mining method
must be adaptable to these uctuations. Sacricing optional
alternatives in any mining method is not desirable unless there
is compelling reason to do so. If commodity prices were to
drop substantially, a portion of the ore in a massive deposit
may become uneconomic to mine. If the mining method is
able to bypass the low-grade sections and continue mining
economic material, the mine will continue to be successful.
Health and Safety
The safety and health of a mine's workers should be the top
priority of every operator. Several methods are inherently
safer than others, because the openings are more stable or per-
sonnel are less likely to be subjected to hazardous conditions.
Although no modern methods are considered to be unsafe, it
bears mentioning that specic health and safety concerns are
often mitigated by the mining method selection. Longwall
mining is recognized as the safest method of mining applied
to soft-rock deposits.
Environmental Effects
The largest environmental impacts of an underground mine typ-
ically fall into three categories: subsidence, groundwater, and
atmospheric emissions. Subsidence is dened as the sinking of
the surface above mine workings as a result of material settling
into the voids created by mineral extraction. It is contentious
in urban or suburban areas where it can affect homes, schools,
and roads. The surface subsidence created by modern long-
wall mines is largely predictable in its timing and magnitude,
in contrast to the unpredictable outcomes associated with some
R&P mines. In this way, longwall subsidence is less hazardous
to human-made surface structures, because impacts occur soon
after mining and rarely change much after initial stabilization.
This allows remediation of surface damage in a time contempo-
rary with mining.
Most areas with a history of mining also have developed
legal processes to address damage from mining-induced sub-
sidence. High-extraction mining methods will foreseeably
induce surface subsidence. If selected, provisions must exist
to mitigate or remedy damages.
Water impacts may arise by accidental causes. Acid-
generating rock of multiple types in excavated ore, waste, or
overlying strata may produce acid mine drainage. Water pro-
duced by the rock mass and mining process must be afforded
appropriate controls, as it will be necessary to keep the mine
drained. In all cases, strict controls must be effectively applied
to mitigate groundwater or surface-water impacts by mining-
related water discharges.
Air quality in underground mines is typically affected
by the natural liberation of mine gases (i.e., methane [CH4 ],
hydrogen sulde [H2S], and carbon dioxide [CO2]), blasting
by-products and equipment emissions (i.e., nitrogen oxides
[NOx ], sulfur oxides [SOx], and diesel particulate matter), and
mineral dust from ventilation fans. Generally, exposure and
emission thresholds exist for these emissions and are strictly
applied. In the case of coal dust and methane, special precau-
tions are followed to avoid the hazards of re and explosion.
Zero harm is a sustainability principle applied by the
foremost mining enterprises in the context of health, safety,
environment, and communities where mines in their portfolios
actively operate. It is an acknowledged goal that communi-
ties will be forever improved because of the global and local
activities of these mining enterprises.
Soft‑Rock (Underground) Mining: Selection Methods 393
MINE PLANNING
Mine planning has three well-dened stages in order to have a
successful implementation of the project and operation of the
mine: identication, selection, and denition.
Identification
The initial assessment is a review of information about the
potential mining site and involves the analysis of geographic,
geologic, environmental, technical, and economic data. This
assessment helps the mining company to evaluate the advan-
tages and disadvantages of the potential site. In this phase,
resource that has potential to become ore is characterized and
limited mining methods are considered to aid in a coarse valu-
ation of the prospect. At the conclusion of this phase, a limited
number of feasible alternatives for exploiting the opportunity
should be identied and adequately framed for further evalua-
tion in the selection phase.
Selection
The reserve determination from the identication phase is the
basis for semiquantitative mine plan comparisons. Competing
mine design alternatives are compared in pro forma economic
evaluations and investment performance measures such as net
present value, along with scored risk assessments. Uncertainty
that leads to variability of outcomes (risk) will be character-
ized, and mitigating strategies or controls will be developed
should the decision to move into the implementation phase
be approved. The preferred mine design (in terms of nancial
value and technical feasibility) results from this stage of plan-
ning. At the conclusion of this phase, a single preferred alter-
native for the mine plan should be selected for optimization in
the denition phase.
Definition
In this phase, all of the detailed planning and resource estima-
tion of the prior phases are rened and optimized to deliver a
nal plan prior to implementation. The success of this phase
will dene the success or failure of the venture. Gaps in infor-
mation, inaccurate planning, or even human resource failures
can lead to loss of investment, environmental damage, human
injury, and negative community impacts. The key to success
in execution is to invest in front-end planning and design prior
to implementation, which should follow a rigorous plan that
includes sufcient contingency and exibility to manage the
variability that is inevitably encountered.
ROOM‑AND‑PILLAR MINING METHOD
The R&P mining method is a popular mining method for
underground mining in tabular and lenticular deposits, as
shown in Figure 29-1 It is the dominant choice for noncoal
underground mining and is frequently applied in coal mines.
The concept is to sink a shaft or construct a slope or drift,
depending on depth of ore, to the elevation of the mining hori-
zon and begin excavating the ore laterally within the deposit.
Where drilling and blasting are not required, the focus of the
operation is the continuous miner (Figure 29-2), which uti-
lizes a large rotating drum to break the material in front of it.
An internal gathering system then loads the broken ore onto
an onboard conveyor.
The onboard conveyor feeds onto a shuttle car or articu-
lated hauler, which takes the product to an optional mobile
belt feeder. If present, the feeder meters the product onto a
conveyor belt, which in turn carries the ore to the surface.
Alternatives to shuttle cars and rubber-tired haulers (battery-
or diesel-powered) are generally termed continuous haulage
systems and include bridge conveyors, composed of multiple
independent bridge carriers, and exible conveyor trains
using a single continuous belt mounted on a mobile base
frame, with bends to follow a producing machine.
Roof support is an integral part of the mining process
and is usually done with roof bolts and their relative, the
roof truss. In place-change continuous mining, the continu-
ous miner makes a cut, and roof bolts are installed with a
mobile machine called a roof bolter. Of course, ventilation
and face drainage are requirements of any mining method.
Alternatively, in very weak roof conditions, continuous
miners with roof-bolting equipment onboard are common.
These machines, called bolter miners, cut and load the ore
simultaneously with the installation of roof bolts. This
results in in-place mining in contrast to the place-changing
method. Another variation of continuous miner has cutting
rotors that rotate parallel to the working face. These borer
miners are popular in potash and trona mining because of
their weight and power. The inability to adequately venti-
late methane in the face with borer miners has forced their
Pillars
Haulage Level
Figure 29‑1. Room‑and‑pillar method sketch
Courtesy of Dresser Industries.
Figure 29‑2. Continuous miner
394 SME Mining Engineering Handbook
decline in coal mining. Broken ore haulage can be the same
for any of the continuous mining methods, although the
combination of in-place mining with continuous haulage
methods has some advantages.
In the R&P method, a continuous miner excavates the
deposit in a grid-like pattern, driving entries (rooms) approx-
imately 15–20 ft wide at the intended mining height. These
openings run parallel to each other along the long axis of the
workings. Crosscuts, driven in the same manner at an acute
angle to the entries, connect the entries to complete the grid-
like pattern. Pillars are left behind to support the roof, hence
the term room-and-pillar, alternately know as bord-and-pillar .
The optimal or favorable characteristics for R&P mining are
shown in Table 29-6.
This mining method is optimal for minerals with lower
ore strength such as coal, potash, salt, or trona. R&P min-
ing can be practiced with partial extraction to leave behind
larger pillars (lower resource recovery and higher cost) where
concerns exist over ground stability or surface subsidence.
Alternatively, high-extraction mining can be executed where
pillar recovery is done after initial panel development. This
method is productive and cost-effective but has rising con-
cerns associated with ground control during the nal phases
of pillar recovery. Mobile roof supports have been introduced
to help mitigate roof-control concerns and reduce logistics
related to roof support. Although an improvement, mobile
roof supports do not fully address the concern.
Another variation of the R&P method is rib-pillar extrac-
tion, where long, narrow pillars are developed and recovered
in a progressive process intended to improve safety and pro-
ductivity. This technique is effective where some attribute of
the deposit does not lend itself to efcient longwall operation.
Yet another variation of R&P mining, arguably hybridized
with longwall mining, is shortwall mining, in which a con-
tinuous miner works with shuttle cars and specially designed
roof supports similar to longwall shields or chocks. Again, this
method has only found successful application in a few cases.
For the most part, underground soft-rock operators are migrat-
ing to longwall mining, which has left high-extraction R&P
mining on the decline where alternatives are available.
The R&P mining method has distinct advantages: the
foremost that, with a continuous miner, operations are nearly
continuous in nature. Most mining sequences require drilling,
blasting, loading, hauling, dumping, and roof support, as well
as continuous ventilation and drainage. The invention of the
continuous miner eliminated the independent steps of drilling,
blasting, and loading, which substantially increases the overall
efciency of the method and improves general productivity.
Low operating costs and high production rates are typically
associated with modern mechanized R&P mining. Continuous
miners can cut through soft-rock deposits, particularly coal,
with ease, resulting in rapid development rates. R&P mining is
generally more exible than other methods, because continu-
ous miners can move to other working places within a panel
or possibly across a mine with limited difculty. Also, the grid
layout of the mine allows for straightforward ventilation with
consistent airow to all working faces.
The major disadvantage of continuous mining is that it
can only be applied to a limited variety of applications. A con-
tinuous miner cannot operate efciently, if at all, in harder
rocks like limestone or granite, and, thus, its principal advan-
tages cannot be shared.
R&P has been used in a variety of soft-rock applications,
as well as a few hard-rock mining applications, but on a small
scale when compared to coal. To purchase equipment and
perform development excavations, R&P requires a moderate
capital investment. The method is also limited by depth. The
pillar size is dictated by the weight of the overburden above
the deposit, so conceptually the deeper the ore body, the larger
the pillars must be. Larger pillars result in lower recoveries
and overall mining efciencies. Pillars can be recovered after
initial development by utilizing retreat mining (high extrac-
tion). The primary advantages and disadvantages of continu-
ous miner–based R&P mining are summarized in Table 29-7.
The difference between coal and noncoal production
methods are four main factors:
1. Strength. Higher strength generally correlates with
higher specic energy of cutting and lower productivity
in cutting applications.
2. Scale. Coal mines are usually larger in throughput than
other soft-rock mines because of the need to economi-
cally produce a lower value product.
3. Methane (CH4 ). Where most coal mines are "gassy," many
noncoal mines are free of that hazard. In most countries,
coal mines and their related equipment are governed by
strict regulations designed to prevent methane or coal dust
explosions. Large mine explosions are often the product
of methane explosions, which entrain coal dust in the air,
leading to subsequent and more energetic coal dust explo-
sions in rapid succession. Worldwide, systems involving
water or incombustible dust (rock dust) are implemented
to prevent coal dust explosions. Spontaneous combustion
is also a hazard in many coal mines worldwide and is an
attribute of some coal seams, but not all.
4. Coal workers pneumoconiosis, more commonly known
as black lung. This chronic, debilitating disease is related
to excessive exposure to respirable coal dust, usually dur-
ing employment in coal mining. The management of dust
in coal mining is subject to strict regulations but continues
to be an area of industry and regulatory focus.
Table 29‑6. Room‑and‑pillar favorable characteristics
Key Deposit Indicators Characteristics
Ore strength Weak to moderate
Host rock strength Moderate to strong
Deposit shape Tabular
Deposit orientation Flat to shallow
Deposit size/thickness Large, thin
Ore grade Moderate
Uniformity Fairly uniform
Deposit depth Shallow to moderate
Table 29‑7. Room‑and‑pillar advantages and disadvantages
Advantages Disadvantages
Continuous production Moderate capital costs
Rapid development rate Limitation on depth
Excellent ventilation Moderate selectivity and flexibility
High productivity Variable subsidence
Moderate operating cost Higher cost with partial extraction
Good recovery
(with pillar extraction)
Moderate recovery
(without pillar extraction)
Soft‑Rock (Underground) Mining: Selection Methods 395
LONGWALL MINING METHOD
Longwall mining is combined with R&P miningto create
some of the most efcient and highest-producing underground
mines in the world. First, the main entries are driven with
the conventional R&P techniques using continuous miners.
A series of panels branching perpendicular from the mains
or submains are outlined by a 2–3 entry R&P border, leav-
ing a very large solid block (panel) of ore within its connes.
Typical panel dimensions in contemporary coal mines are 800
to 1,400 ft of face length (width) with 6,000 to 15,000 ft of
panel length. In coal, panel tonnages of almost 12.1 million
metric tons are possible. In modern longwall faces, a shearer,
armored face conveyor (AFC), stage loader, and line of pow-
ered roof supports (shields) are assembled in a setup room at
the beginning of the panel before longwall mining commences
(Figure 29-3). Utilities used by a longwall include emulsion
pumps with capacities of 300–500 gpm at 4,000 to 4,800 psi.
Electrical controls powered by 3,300 to 14,400 V provide
power to the longwall face equipment at 1,000–4,160 V.
The shearer moves back and forth across the coal block,
excavating 100% of the ore within its height capability, caus-
ing the material to fall onto the AFC and be transported to
the main belt conveyor system via the stage loader, which
normally has an integral crusher to provide suitably sized
material for conveyor belts. The shields advance sequentially
following the shearer to hold up the roof directly above the
face equipment and advance the AFC to repeat the cutting
cycle. The excavated area behind the shields is allowed to
collapse. Retreat of the longwall progresses, as continuous
miners develop additional adjacent longwall panels. When the
longwall reaches the end of the panel, specialized activities
are executed by a carefully choreographed plan to withdraw
the longwall equipment from the completed panel and rein-
stall it in the next panel. During this process, key elements
of the equipment are refurbished or exchanged with machine
manufacturers for an already refurbished machine or compo-
nent. Commonly, shearers, AFC and stage loader components,
pumps, and selected electrical equipment are refurbished as
necessary to allow high availability in service during the new
panel. For world-class longwalls, production can range from
6.6 to 13.2 million tons per year, with unplanned production
outages resulting in lost opportunity costs estimated to range
from $200 to $1,000/min. A sketch of the longwall mining
method and the components used are shown in Figure 29-4.
In coal seams lower than 60 in., thick plow-type longwalls
are sometimes applied. These systems do not have the pro-
ductivity of higher-height shearer-based systems and are more
vulnerable to abnormal geologic conditions or roof falls on the
face or in the tailgate. However, they are a viable alternative if
mining heights below the limits of shearers are required.
Alternatively, interest is emerging in mining very thick
seams, more than 18 ft in height, by longwall methods. This
has led to development of some very large single-pass long-
wall systems; multilift longwalls, with limited success; and
top-coal caving longwalls, which seem to offer good potential.
Although both retreating and advancing style longwall
systems have been used in the past, most installations world-
wide are now retreating faces. This choice causes higher ini-
tial development but minimizes the huge task of maintaining
gate roads in the caved area behind the face (gob/goaf).
The largest number of longwalls is composed of dated
equipment styles, including low-capacity chock-type roof sup-
ports, or even the earliest style, prop-and-bar or timber roof
support. These are notable only because many such installa-
tions still exist worldwide but are clearly inferior to modern
technology from productivity and safety perspectives.
It is of passing interest that a variation of the longwall
method is also applied to hard-rock gold and platinum reef
deposits in southern Africa. There, drilling and blasting break
the rock, and low-production conveying systems and slushers
clear broken ore from the face. Nonexplosive rock breaking or
cutting is being evaluated but is not yet commercialized.
Not all soft-rock ores are suited for longwall mining,
which works best in deposits that are laterally extensive, at
lying, of fairly uniform thickness, and primarily free of dis-
continuities such as faults. Coalbeds deeper than 1,000 ft usu-
ally must be extracted by way of longwall mining, because
using R&P methods would require the use of much larger pil-
lars to support the roof and thus reduce the amount of coal that
can essentially be recovered.
Rock bursts, mountain bumps, and outbursts are all man-
ifestations of stored energy release where R&P or longwall
mining has been conducted with some combination of the fol-
lowing conditions present:
Source: Hustrulid 1982.
Figure 29‑3. Klockner Ferromatik shield roof supports on U.S.
longwall faces
Rock Subsidence
Self-Advance Hydraulic
Support Chain Conveyor
Belt Conveyor
Longwall
Drum Shearer
Ore
Figure 29‑4. Longwall method sketch
396 SME Mining Engineering Handbook
• Depth greater than 1,500 ft
• Strong ore or stiff/strong rock members in the nearby
underlying or overlying strata
• Unexpectedly high in-situ horizontal stresses or stress
increases from interaction between workings
• Substantial reservoir or pore pressures of pressurized u-
ids, particularly CO2 or CH4
These events can range from mild thumps of little signicance
to catastrophic events capable of serious equipment damage
and fatal injury to personnel. Expert assistance should be
enlisted to assist the mine planning process where such events
may occur.
The optimal characteristics for longwall mining are
shown in Table 29-8.
Even more so than R&P mining, the longwall method
is exceptionally efcient and has outstanding production
rates and low operating costs. The operation is almost com-
pletely mechanized and recovers an extremely high percent-
age of the ore body. The working face is also safe since the
roof is directly supported at all times by heavy duty shields.
Electronic controls and automation allow personnel to posi-
tion themselves away from most of the recognized hazards. If
conditions allow, longwall mining is the most effective way to
excavate a thin tabular deposit with lower ore strength.
Over the years, signicant improvements to longwall min-
ing equipment have been made to help yield higher production
rates. Shields with high-yield capacities and electro-hydraulic
controls have replaced manually operated frames and chocks.
AFCs have become more robust and powerful with increased
size and speed of the chains, allowing higher conveyor capaci-
ties. The shearers have also become much more powerful and
reliable, which enables more production, less downtime, and
greater equipment longevity.
There are, however, a few disadvantages to longwall min-
ing. First, it requires a substantial capital investment to pur-
chase the highly specialized equipment to create a longwall
section. The development time is signicant because the con-
tinuous miners have to progress the main entries and develop
gate roads for the longwall panel before the longwall can be
installed. Finally, there is little selectivity or exibility after
mining commences. Longwall mines should be large, long-
lived operations, with high production rates, in order to make
certain of an adequate return on the mine operator's invest-
ment. The primary advantages and disadvantages of longwall
mining are summarized in Table 29-9.
SMALL‑SCALE MINING METHODS
Typically, in small-scale mining operations, a more traditional
mining method is favored, where pneumatic drills are used
to drill holes to be charged with explosives, and the ore is
then blasted and hauled away. Small-scale coal mines may
use this method because access to capital is difcult and the
cost of equipment for a continuous miner section is prohibi-
tive. Where conditions and capital availability permit, some
operators employ continuous miners in small R&P mines. The
evolving regulatory and socioeconomic climate is likely to
systematically diminish such small operators in preference for
larger-scale operations.
CONCLUSIONS
The process of selecting the optimum mining method for a
given deposit is complex and requires extensive collection of
geological, metallurgical, and mining-related data. In addition
to the analysis of multiple alternatives, a thorough understand-
ing of the sociopolitical setting, pertinent environmental con-
cerns, and applicable regulations is critically important. This
chapter has discussed the primary deposit characteristics and
the mining method performance variables that are involved
when selecting a mining method for soft-rock extraction.
Because mineable ore deposits exist in all shapes and sizes
and no two are alike, the best method selection process is not
always evident. However, several key tasks should always be
undertaken during method selection for any ore deposit. The
rst step is to identify the mineral resource available. The sec-
ond step is to match the most suitable mining method to the
ore body. As part of this step, it is important to identify per-
tinent economic or environmental factors that may constrain
methods selection.
Above all else, it cannot be overemphasized that mine
planners must value the principle of zero harm, which encom-
passes health, safety, environment, and community impacts.
Failure in any of these areas can affect the sustainability of a
mining operation just as seriously as a planning or execution
failure. A review of numerous case histories of success and
failure highlights the fact that failed projects are usually due
to inadequate deposit characterization, inadequate risk assess-
ment and consequent acceptance of elevated risk, inadequate
planning or overestimation of operating performance, or inad-
equate capital to correctly implement plans. There are many
paths to failure, and the paths to success are few and normally
difcult.
REFERENCE
Hustrulid, W.A. 1982. Underground Mining Methods Hand-
book. New York: SME-AIME.
Table 29‑8. Longwall favorable characteristics
Key Deposit Indicator Favorable Characteristics
Ore strength Low
Host rock strength Weak to moderate
Deposit shape Tabular
Deposit dip Flat to shallow
Deposit size/thickness Large, thin
Ore grade Low and above
Uniformity Uniform
Deposit depth Shallow to deep
Table 29‑9. Longwall advantages and disadvantages
Advantages Disadvantages
Low operating cost High capital investment
High productivity Significant advance development
High recovery Low selectivity
Safest method Predictable subsidence
High production rate Low flexibility
High mechanization
Continuous method
... There are many mechanical characteristics of rock body but the most discussed is usually the compressive strength. The knowledge of this strength is paramount to determine the structural performance and suitability in mechanical cutting (Antonio Nieto., 2011). The strength and deformation features may include the elastic properties, plastic properties and creep properties. ...
... There is a distinctive difference between cost and productivity performance of mechanized cutting if compared with drilling and blasting when its soft rock applicable. Mechanized cutting will be preferred (Antonio Nieto., 2011). These parameters can be measured by a number of rock mass classification system, which is a pointer to assessing the likelihood of impact of rock behaviour to mining activity (Barton, 1974), (Bieniawski Z. T., 1973), (Bieniawski Z. T., 1976), (Bieniawski Z. T., 1989), (Deere, 1968), (Laubscher D. H., 1977). ...
... The flexibility in adaptation should be a factor considered across board to suit the overall system. Since the life of a mine takes a very long time, it is imperative to assume that some factors such as technology, ore grade & market price of ore may alter over time of the mine life, hence the flexibility in selectivity should also be an important factor (Antonio Nieto., 2011). Underground mining method is more selective than the surface mining method counterpart, but the degree of this selectivity depends on the underground mining technique employed , (Hamrin, 2001). ...
Abstract In recent times, there were various campaigns against environmental degradation and a need to save the earth. This led to a call for cleaner source of energy to eliminate carbon emission into the environment. Gradually, rechargeable household equipment became common in the society and not so long the introduction of an electric powered vehicles. This vehicle uses lithium ion battery as an energy storage device which require high amount of lithium compound to build. There are, however, other several applications of the lithium. Every lithium ion battery applications have a demand for lithium which ranges from 10g for a smart phone to 100kg for a type S Tesla truck and even higher for German made vehicles, not overlooking other applications like the use in power tools, electric grid (smart electricity), laptops and mobile phones etc. These have volume requirements especially for electric vehicles and plug-in- electric vehicles and smart electricity. In line with world future electric vehicle demand prospect, there was a raw material supply panic in the lithium industry that warranted revamping of abandoned mines across the globe, while producing mines increased production and tens of exploration projects are ongoing in different phases: All in search for lithium resources to meet demand. The major source of lithium is the lithium brine mineralization found mainly in the South American lithium triangle followed by the pegmatite. Lithium mineral is majorly found in the Green Bush belt of North West Australia; this mineralization is known as the spodumene. Other forms of lithium minerals are the Hectorite, Jadarite, Lepidolite, Petalite etc. Every form of these mineralization comes with a unique technique of mining and extraction. Lithium is known to be used in ancient time majorly for ceramic and glass making but in recent times, the need for a cleaner environment overtook those needs and lithium now has vast utilities but the use in battery is 56% and may grow further in this decade according to predictions. This reality and predictions are the major drive in the mining industry for a focus on lithium mining and extraction and most recently, a look into new lithium technologies and recycling. This thesis then comes into play to abate mistakes made by old mine companies. Mistakes made from phases of feasibility studies to mine planning down to metallurgy; thereby steering the lithium industry toward industry 4.0 and maintain a sustainable practice. To qualify a project for mining activities, the ore in place is not the only factor to be considered, though, the ore plays about 60 % of the influence according to (FraserInstitute, 2020). There are several economic and technical factors like the investment attractive index, policy attractive index of a jurisdiction or a country which plays a major role plus other unmentioned factors before a mining project is considered economical. These major factors and other minor ones must cross a benchmark to set a project on the path of potentiality. In this thesis, a comparative tool was designed to determine the most potential of a set of lithium mining projects in their early stage of feasibility, thereby determining the most potential of the compared projects. The 'House of Quality' tool set was used as the comparative tool; this is an empirical tool which was applied after several graphical comparison has been done but no specific result was gotten. The House of Quality compared criteria of all parameters of the ten (10) mining projects namely: i. Cinovec lithium-Tin project, ii. Finniss project, iii. Flagship Manono lithium project, iv. Goulamina lithium project, v. Greenbushes, vi. James Bay, vii. Kathleen Valley, viii. Mt Holland, ix. San Jose lithium project, x. Seymour lake, against each other, then produced Greenbushes of Western Australia as the most potential of the ten lithium projects analysed. A sensitivity analysis was conducted on the tool to check the flexibility of House of Quality tool, this was done by changing the scale of the tool and the result came out showing little to no impact. Therefore, this tool can be applied to adjusted criteria and parameters or can also be used for the assessment of other metals.
... farming, healthcare, communications, water, energy supply, transport, space technology and construction of cities [1]. With the ever increasing population, the demand for base metals, particularly iron, copper and aluminum will double from 2010 to 2025 [2]. To put only the demand for iron ore in perspective, the World needs five more Rio Tinto Pilbara Mine operations producing nearly 200 MT iron ore annually [2]. ...
... With the ever increasing population, the demand for base metals, particularly iron, copper and aluminum will double from 2010 to 2025 [2]. To put only the demand for iron ore in perspective, the World needs five more Rio Tinto Pilbara Mine operations producing nearly 200 MT iron ore annually [2]. In addition, the copper demand from 2010 to 2035 will equal all copper consumed in the last century [2]. ...
... To put only the demand for iron ore in perspective, the World needs five more Rio Tinto Pilbara Mine operations producing nearly 200 MT iron ore annually [2]. In addition, the copper demand from 2010 to 2035 will equal all copper consumed in the last century [2]. The greatest challenge the mining industry faces today is to meet such exponential growth in the demand for minerals and metals. ...
Mining in 21st century faces with numerous challenges. In addition, mining at depth is faced with extreme geo-stress uncertainties, geomechanics, and cost, demanding sophisticated design and site-specific planning. The extraction of ores necessitates advance delineation of ore bodies to minimize the cost of extraction and processing thereof. Besides, waste and tailings concentrations need to be minimized and preferably eliminated. New underground support systems, once designed to cater to usual stress re-distributions of excavations, are now faced with extremely high demands of structural strength, thus necessitating a paradigm shift in design philosophy. Such improvement of mine support systems from conventionally passive to active and de-stressing concepts must withstand enormously high sequentially transiting loads from static to dynamic stress states. The new complex mining environment is also a challenge for mine health and safety, which issue is of great concern for regulators, mine workers, and mine owners. Ultra-deep mines now require automated digital systems to monitor the real-time well being of people, mining equipment, and underground excavations. The authors of this paper believe that the existing knowledge, technologies, and techniques in the mining industry have reached their limits, and it is time to re-imagine the technical services knowledge and skills requirements in the context of the 21st century and innovate for efficient, safe and sustainable mining. To accomplish these complex and urgent needs of the mining industry, international collaboration is required. The success of the WITS-NUST collaboration (detailed in another paper), have encouraged the authors to extend their earlier collaboration to embark upon qualifications design for the development of the global 21st Century Technical Mining Services Professional.
... Metal mines are developed using mining methods, including shrinkage stopping, sublevel stoping, cut and fill mining, block caving, and panel caving. Detailed characteristics of the deposit are taken into account in deciding the mining method to be used for development [17]. The factors involved in deciding the mining method to be chosen for a deposit are outside the purview of this paper. ...
-
![Ankit Jha]()
- Alex Verburg
- Purushotham Tukkaraja
Background Underground mines have several hazards that could lead to serious consequences if they come into effect. Acquiring, evaluating, and using the real-time data from the atmospheric monitoring system and miner's positional information is crucial in deciding the best course of action. Methods A graphical user interface–based software is developed that uses an AutoCAD-based mine map, real-time atmospheric monitoring system, and miners' positional information to guide on the shortest route to mine exit and other locations within the mine, including the refuge chamber. Several algorithms are implemented to enhance the visualization of the program and guide the miners through the shortest routes. The information relayed by the sensors and communicated by other personnel are collected, evaluated, and used by the program in proposing the best course of action. Results The program was evaluated using two case studies involving rescue relating to elevated carbon monoxide levels and increased temperature simulating fire scenarios. The program proposed the shortest path from the miner's current location to the exit of the mine, nearest refuge chamber, and the phone location. The real-time sensor information relayed by all the sensors was collected in a comma-separated value file. Conclusion This program presents an important tool that aggregates information relayed by sensors to propose the best rescue strategy. The visualization capability of the program allows the operator to observe all the information on a screen and monitor the rescue in real time. This program permits the incorporation of additional sensors and algorithms to further customize the tool.
... Jaw crushers are classified, according to the location of this pivoted swinging plate, into Blake, Dodge, and Universal crushers. The Blake crusher is considered the most common, where the swinging plate is pivoted at the top [6]. This crusher can be a double toggle or single toggle. ...
- Khaled Ali Abuhasel
Crushing is a vital process for different industrial applications where a significant portion of power is consumed to properly blast rocks into a predefined size of fragmented rock. An accurate prediction of the energy needed to control this process rarely exists in the literature, hence there have been limited efforts to optimize the power consumption at the crushing stage by a jaw crusher; which is the most widely used type of crusher. The existence of accurate power prediction as well as optimizing the steps for primary crushing will offer vital tools in selecting a suitable crusher for a specific application. In this work, the specific power consumption of a jaw crusher is predicted with the help of the adaptive neuro-fuzzy interference system (ANFIS). The investigation included, aside from the power required for rock comminution, an optimization of the crushing process to reduce this estimated power. Results revealed the success of the model to accurately predict comminution power with an accuracy of more than 96% in comparison with the corresponding real data. The obtained results introduce good knowledge that may be used in future academic and industrial research.
... Again the demand consists of two pits that were The most economic and environmentally friendly solution was found to be the installation of sprinklers alongside the haul road. In underground mining operations, a formula for estimating cost of piping systems was suggested by Adler (1992) as: ...
... An open pit mine is an excavation or cut made at the surface of the ground for the purpose of extracting ore and which is open to the surface for the duration of the mine's life (Fourie, 1992). Basically a mine is an excavation made in the earth for the purpose of extracting useful minerals (Gregory, 1983). ...
... Depending on the terrain where the mining operation is located it may be difficult to obtain resources necessary to maintain the equipment. Mining is also a very energy intensive process requiring both electricity and fuel to provide energy equipment operation[1,2]. The majority of load haul dump vehicles, LHDs, in underground mining operations are currently powered by diesel. However, with recent advancements in battery technology it is becoming more feasible, both physically and economically, to convert larger equipment, such as LHDs, from diesel power to battery[3][4][5]. ...
- Richard S. Schatz
-
![Antonio Nieto]()
- Serguei N. Lvov
LHD's are expensive vehicles; therefore, it is important to accurately define the financial consequences associated with the investment of purchasing the mining equipment. This study concentrates on long-term incremental and sensitivity analysis to determine whether it is feasible to incorporate current battery technology into these machines. When revenue was taken into account, decreasing the amount of haulage in battery operated equipment by 5% or 200kg per h amounts to a $4.0×10⁴ loss of profit per year. On average it was found that using battery operated equipment generated $9.5×10⁴ more in income annually, reducing the payback period from seven to two years to pay back the additional $1.0×10⁵ investment of buying battery powered equipment over cheaper diesel equipment. Due to the estimated 5% increase in capital, it was observed that electric vehicles must possess a lifetime that is a minimum of one year longer than that of diesel equipment.
-
![Boris Verbrugge]()
This chapter presents an exploratory analysis of different stages in the gold production cycle, notably exploration, mining, processing, and refining. It analyzes key technological changes, as well as changes in the constellation of actors involved in each of these stages. This exploratory analysis reveals that gold production is accessible to smaller and less powerful players, including small miners, traders, and refiners. It also reveals linkages that connect these actors to one another, and to larger mining companies and refineries. In many cases, these linkages span across the formal-informal divide. Finally, it draws attention to how both the accessibility of gold production and the linkages between the various actors involved in it are facilitated by the material properties of gold.
Deep‐sea mining refers to the retrieval of marine mineral resources such as manganese nodules, ferromanganese crusts and seafloor massive sulfide deposits, which contain a variety of metals that serve as crucial raw materials for a range of applications, from electronic devices to renewable energy technologies to construction materials. With the intent of decreasing dependence on imports, supporting the economy and potentially even overcoming the environmental problems related to conventional terrestrial mining, a number of public and private institutions have re‐discovered their interest in exploring the prospects of deep‐sea mining, which had been deemed economically and technically unfeasible in the early 1980 s. To date, many national and international research projects are grappling to understand the economic environmental, social and legal implications of potential commercial deep‐sea mining operations: a challenging endeavor due to the complexity of direct impacts and spill‐over effects. In this paper, we present a comprehensive overview of the current state of knowledge in the aforementioned fields as well as a comparison of the impacts associated with conventional terrestrial mining. Furthermore, we identify knowledge gaps that should be urgently addressed to ensure that the world at large benefits from safe, efficient and environmentally‐sound mining procedures. We conclude by highlighting the need for interdisciplinary research and international cooperation. This article is protected by copyright. All rights reserved
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![Carlos Enrique Arroyo Ortiz]()
- Adilson Curi
- Pedro Henrique Campos
The choice of fleet type and sizing to be used in mining operations is surely important, for taking this decision the engineers need to have enough information in order to get the most benefit and efficiency of each piece of equipment. In this process, technical, geometrical, geographic and, uppermost, economic variables are involved. Furthermore, the market offers a different range of brands, models and capacities of equipment, which can deliver similar results of those which are expected. At the moment, there is a shortage of reliable and appropriate systems to evaluate the type and the sizing of a fleet, because most of them allow the work with just one piece of equipment at a time and not with the whole fleet, so it is needed to do a manual calculation. One solution is the use of a stochastic and deterministic simulation for it is possible to determine the quantity and type of equipment used in an activity in a deterministic way and simulate possible combinations of them all. In this scientific work, it is intended to use the software "Arena" to evaluate and determine the appropriate fleet selection in an iron ore project.
- W.A. Hustrulid
Sections discuss: mine design considerations; stopes requiring minimum support (includes room-and-pillar mining and sublevel stoping); stopes requiring some additional support other than pillars (includes shrinkage stoping, cut-and-fill stoping, undercut-and-fill mining, timber-supported system, top-slice mining, longwall mining and shortwall mining); caving methods (sublevel and block caving); underground equipment; financial considerations; design; and mine ventilation.
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