LESSON 030425: UNIT OPERATIONS
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Top Hammer
Fundamental Unit Operations and Cycles
Drilling
Blasting
Loading
Haulage and Hoisting
Auxiliary Operations
Cycles and Systems
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Drill Rod- transmits energy from the drill to the bit
Bit - attacks the rock with rotational and/or percussive action
Circulation fluid- cleans the hole, controls dust, cools the bit, and
stabilize the hole
Operating Components of the System:
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Note: Surface: Drilling, Hauling, Loading
Underground: Drilling, Blasting, Hauling, Loading, Hoisting
Fundamental Unit Operations and Cycles
Production = Drilling + Blasting + Loading + Hauling
The top-hammer’s piston hits the shank adapter and creates a shock
wave, which is transmitted through the drill string to the bit. The energy
is discharged against the bottom of the hole and the surface of the rock is
crushed into drill cuttings.
-​ Can drill narrow and short boreholes
-​ Uses water to flush out cuttings.
Down-the-hole Drill
Unit Operations refer to separate actions taken as a part of the mine cycle to
accomplish the overall goal of mine production. In a typical conventional mining
cycle, the unit operations include drilling, blasting, loading, and hauling.
Rock Breakage: Drilling and Blasting
Handling: Loading and Hauling
Rock Breakage
The freeing or detaching of large masses of harder rock from the parent deposit.
2 types of rock breakage:
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Rock Penetration
Rock Fragmentation
Rock Penetration (drilling, boring, or channeling)
-​ Placement of explosives for blasting
-​ Produce a finished mine opening
-​ Extract a mineral product of desired sizes and shape
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Usually called DTH by the professionals
It is a jackhammer screwed on the bottom of a drill string. The fast
hammer action breaks hard rock into small cuttings and dust that is
evacuated by a fluid (air, water, or drilling mud).
Rock Penetration (blasting)
-​ break rock into manageable sizes
DRILLING
-​ Executing bores in soil or rock, and sample/core, product generated in
drilling, provides information to the region surveyed.
-​ A very significant stage, for several projects, in civil construction,
hydrology, mining or geotechnic, for instance.
-​ Most reliable method in retrieving information about coal deposits.
Types of Drilling Rig
1.​ Rotary Drill
2.​ Top Hammer
3.​ Down-the-hole Drill
Rotary Drill
-​ Refers to the use of a sharp, rotating drill bit to cut or crush by applying
downward pressure.
-​ Mostly used to drill big holes in pit mines, petroleum extraction and other
various fields.
Types of Drill-bits:
Roller Cone
-​ Milled tooth/Steel tooth: for softer formation
-​ Drag bits: steel or tungsten carbide
-​ Tungsten carbide insert
Operating components of the system:
1.​ Drill - the mechanical device that converts energy from its original
source into rotational and/or percussive energy to penetrate the rock.
Fixed-cutter Bits
-​ Polycrystalline diamond compact (PDC)
-​ Diamond bits
*natural diamond
*Thermal Stable Polycrystalline (TSP) Diamond
*Impregnated Diamond
Properties of Explosives
1.​ Classification of explosives
2.​ Ingredients
3.​ Blasting properties of explosives
4.​ Initiation Systems
Classification of Initiations
Three types of initiation systems
1.​ Electric; 2. Non-electric ; 3. Electronic
Electric
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Uses electrical currents to initiate detonation.
Electrical currents from the detonator's lead wires or connectors ignite an electric
match which in turn ignites a pyrotechnic delay element that initiates the base
charge. The pyrotechnic delay element burns at an approximated rate.
CFR- Code of Federal Regulations
Ingredients
-​ Principal components of an explosive are fuels and oxidizers
-​ Most common fuels: fuel oil (FO), carbon, aluminum, and
trinitrotoluene.(TNT)
-​ Oxidizers include ammonium nitrate (AN), sodium nitrate, calcium
carbonate.
Non-electric
-​ Is designed to initiate explosives, including ones charged pneumatically
into a blast hole, in open-pit and underground non-coal mines
Electronic
-​ Utilizes microchip technology to provide delays for blast designs.
Mechanics and Performance factors of penetration:
1.​ Operating Variables- these affect the four components of the drilling
system.
2.​ Drillhole factors- hole size, length, and inclination
3.​ Rock factors- properties of the rock, geological conditions
- aka. Drillability factor
4.​ Service factors- labor and supervision, power supply; job site conditions
Principles of Rock fragmentation
Rock fragmentation- breakage function carried out on a large scale to fragment
masses of rock
BLASTING
Theory of Explosives
In general, an explosive has four basic characteristics:
(1) It is a chemical compound or mixture ignited by heat, shock, impact, friction, or a
combination of these conditions;
(2) Upon ignition, it decomposes rapidly in a detonation;
(3) There is a rapid release of heat and large quantities of high-pressure gases that expand
rapidly with sufficient force to overcome confining forces.
(4) The energy released by the detonation of explosives produces four basic effects;
(a)​ Rock fragmentation
(b)​ Roc displacement
(c)​ Ground vibration
(d)​ Air blast
Blasting Properties of Explosives
1.​ Velocity of detonation
2.​ Detonation pressure
3.​ Borehole pressure
4.​ Density
5.​ Energy output or strength
6.​ Cap sensitivity
7.​ Gap sensitivity
8.​ Water resistance
9.​ Fume class
Principles of Loading & Excavation
Note: The extraction and elevation of minerals either broken or in place, is termed
loading or excavating.
Excavation- implies action of extracting from the solid
Loading- suggests scooping and elevating material without extraction.
Selection of Equipment:
1.​ Performance factors
2.​ Design factors
3.​ Support factors
4.​ Cost factors
TYPES OF LOADING OPERATIONS
HAULING
Principles of Haulage and Hoisting
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The transportation of materials, such as rock or ore, in mining
operations using trucks, conveyors, or other methods
Haulage - primarily horizontal
Hoisting - primarily vertical
Selection of haulage and hoisting equipment:
1.​ Production
2.​ Production rate
3.​ Productivity
4.​ Efficiency
5.​ Availability
6.​ Utility
7.​ Capacity
8.​ Rated capacity
9.​ Swell factor
10.​ Bucket fill factor
11.​ Cycle
UNDERGROUND LOADING AND HAULING EQUIPMENT
AUXILIARY OPERATIONS
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All activities supporting but not directly contributing to the production of ore.
Classification of Mine Auxiliary Operations
1.​ Exploitation- health and safety, environmental control, ground control, power
supply and distribution, water and flood control, waste disposal, material supply,
maintenance and repair, lighting, communication, construction, personnel
transport.
2.​ Development- site preparation, topsoil removal, surface reclamation
3.​ Reclamation- topographic work, revegetation, erosion control, monitoring
LESSON 7: MINERAL DEPOSITS
Mineral deposits
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Natural accumulations of valuable minerals in places within the earth’s crust.
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Usually composed of an aggregate of a mineral or group of minerals in unusually
high concentrations in the form of mineral bodies that can be extracted at the
present time or in the immediate future.
Ore deposit
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A mineral deposit that has been tested and found to be of sufficient size, grade, and
accessibility to be mined at a profit.
Three main groups of mineral deposits:
(a)​ Metallic
(b)​ Non-metallic—industrial
(c)​ Energy mineral deposits
SHAPE AND FORM
1.​ Tabular- mineral deposit lying as a filling between more or less parallel layers of
rock.
2.​ Tubular - the horizontal or subhorizontal tubular bodies with roughly circular
cross sections are called “Mantos”. When the tubular bodies have vertical or
subvertical extensions such as ore bodies are known as “pipes” or “chimneys”
3.​ Vein-type -a type of mineral deposit that consist of a localized zone fracture-filling
minerals
4.​ Stratiform - ore minerals are always confined within specific strata and are
distributed in a manner that resembles particles in a sedimentary rock.
5.​ Stratabound- a=ore are exclusively confined within a single specific stratigraphic
unit.
6.​ Massive- mineralization composed of uniformly a large proportion (>60%) of ore
minerals.
7.​ Disseminated- ore containing small particles of valuable minerals, spread quite
uniformly throughout the host rock.
8.​ Stockworks - a complex system of structurally controlled or randomly oriented
veins.
9.​ Lenticular- sedimentary bedding pattern displaying alternating layers of mud and
sand.
Magmatic- magma, and magmatic fluids
Magmas are hot molten rock materials that are liquid at high temperatures but as they migrate
upwards from deep-seated sources, they cool as temperatures fall and crystallize to form solid
minerals.
Magmatic ore-forming processes
(a)​ Dissemination- process of homogenous scattering of ore minerals in a host rock
during the early or late phase of magmatic crystallization. It occurs both in mafic
and felsic magmas.
(b)​ Crystal Settling- a type of magmatic segregation–a process by which one or more
minerals become locally concentrated (segregated) during the cooling and
crystallization of a magma. Rocks formed as a result of magmatic segregation are
called magmatic cumulates. Mineral deposits that are magmatic cumulates are only
found in mafic and ultramafic igneous rocks with low silica content.
(c)​ Liquid Immiscibility- a process in which a cooling magma will sometimes
precipitate droplets of a second magma that has an entirely different composition.
(d)​ Fraction Crystallization - the removal and segregation from a magma of early
formed crystals. This process changes the composition of the magma and results in
the enrichment of certain elements and volatiles in the residual fluids.
Hydrothermal processes precipitate mineral deposit as the result of the actions of
hydrothermal solutions and their reaction with surrounding rocks.
Hydrothermal solutions are the hot aqueous fluids that serve as a very effective medium for
the transportation and enrichment of certain elements.
Clastic Deposition
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Physical processes of erosion, transportation by rivers and streams, and deposition
of clastic materials including sand, silt, clay and resistant minerals can lead to
accumulation of valuable minerals.
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Alluvial mineral deposits are formed in rivers and streams by hydraulic
concentration of heavy, durable minerals such as gold, tin, platinum, and
diamonds.
Evaporation
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Physical process in which water or aqueous solutions vaporize into the atmosphere
due to the effect of heat which may lead to the concentration and precipitation of
useful minerals.
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Marine evaporites formed from ocean water ; Non-marine evaporites formed
from smaller standing bodies of water, e.g. lakes.
Chemical/biochemical precipitation
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This can lead to the precipitation of metals/ minerals held in solution in standing
bodies of water due to reactions,changes in physical conditions or when their
concentrations exceed solubility ranges.
Biogenic Processes
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This can lead to the accumulation of the remains of plants and animal skeletons in
near-shore to deep marine environments.
Diagenesis
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Totality of all the chemical, physical, and biological changes that occur after
sediments are initially deposited, compacted and consolidated (excluding
metamorphism)
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Mineral deposits are formed by alteration, remobilization and leaching of metals
and concentrating them in open spaces w/in the sediment. These are called
diamagnetic mineral deposits.
Regional metamorphism
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Occurs over a large region
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Most widespread and common type of metamorphism
3 types of metamorphism: burial, ocean-ridge, orogenic regional
metamorphism
Contact metamorphism
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Rock mineral and texture are changed, mainly by heat, due to contact with magma
Chemical weathering
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Breakdown of rocks through oxidation and hydrolysis
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Deposits are called residual deposit
Mechanical weathering
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Breakdown of rocks and minerals in temperate climates
MAGMATIC MINERAL DEPOSITS
Disseminated deposits (Ni, Cr, Nb, REE)
- characterized by the random or uniform scattering of ore minerals in igneous host
rocks.
2.​ Layered (Stratiform) deposits (Cr, PGE, Fe, Ti, V)
- occur in layered mafic and ultramafic intrusions as massive sheets, bands, and
lenticular bodies that are conformable with the primary layering of the host rocks.
3.​ Massive sulfide deposits (Ni, Cu, PGE) —- volcanic and plutonic subtypes
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Occur predominantly within mafic/ultramafic intrusions, rarely in
ancient (Archean) basaltic lavas___komatiites
4.​ Pegmatite deposits (Sn, Nb, Ta, Li,U)
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Very coarse-grained igneous bodies formed from residual volatilerich fractions of granitic magma by the process of crystallization
fractionation or magmatic differentiation.
HYDROTHERMAL MINERAL DEPOSITS
1.​ Vein deposits
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Most widespread or classical form of hydrothermal deposits.
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Occur as tabular, elongated bodies that occupy openings in rocks in
rocks within a fairly well-defined zone of mineralization.
2.​ Porphyry type deposits
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Refers to a group of large and low grade, intrusion-related deposits
comprising veins
3.​ Volcanogenic massive sulfide deposits
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Created by volcanic-related hydrothermal events in submarine volcanic
environments
4.​ Sedimentary exhalative (SedEx) deposits
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Mineral deposits of Pb-Zn-Ag formed by precipitation of metals into
sea water, through the release of ore-bearing hydrothermal fluids
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Exhalative refers to the process of venting hydrothermal solutions into
submarine environments
5.​ Epithermal-Geothermal deposits
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Small group of hydrothermal deposits of Au-Ag closely associated with
volcanic geothermal fields and formed at shallow depths, at low
pressure and temperature.
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Attributed to the action of heated groundwater associated with
geothermal sources.
6.​ Mississippi valley type (MVT) deposits
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Varied family of epigenetic lead-zinc ore deposits that occur
predominantly in carbonate host rocks, particularly dolomites and
limestones.
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PLACER DEPOSITS
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Used to describe deposits formed by mechanical accumulation of valuable detrital
and resistant minerals released by weathering from appropriate source rocks and
concentrated on slopes, riverbeds or beaches.
TYPES OF PLACER DEPOSITS
(a)​ Residual placer- concentrations of heavy, weathering-resistant minerals that
accumulate near their source rock, formed when lighter materials
(b)​ Eluvial placer- formed on hillslope from withered material; are not acted on by
streams but by rainfall and wind.
(c)​ Alluvial placer- formed by the concentration of heavy minerals in river or stream
sediments where water velocity slows, allowing these denser particles to settle out.
(d)​ Beach placer- forms on seashores where wave action and shore currents shift
materials.
(e)​ Aeolian placer - formed by the mechanical concentration of weathered debris in
arid or semi-arid regions where wind is the primary agent of transport and
deposition.
(f)​ Fossil placer- formed by the concentration of heavy minerals through gravity
separation during ancient sedimentary process and now preserved in older
geological formations.
(g)​ Bench placer- found in an old, high0lying stream terrace, where the stream has
eroded and left the deposit elevated.
(h)​ Glacial deposit- formed by glacial erosion and deposition, where heavy minerals
are concentrated due to gravity and the sorting action of glacial meltwater.
(i)​ Flood gold deposit - where fine gold particles, carried and redistributed by
floodwaters, that are deposited on gravel bars as the floodwaters recede, forming a
type of placer deposit.
(j)​ Tertiary gravel- formed during the tertiary geological period, where valuable
minerals like gold are concentrated in gravels and other unconsolidated sediments.
SEDIMENTARY MINERAL DEPOSITS
1.​ Evaporite Deposits- formed by evaporation of lakes or sea water
which result in the concentration of dissolved substances that
precipitate from the water.
2.​ Chemical Precipitate Deposits - in which the ore minerals are
precipitated from the solution as a result of chemical or biochemical
reactions in lake or sea water to form stratiform mineral deposits.
3.​ Sediment Hosted ( stratiform) deposits- a significant group of copper
deposits that occur within sedimentary rocks ranging from shales,
siltstones, and sometimes in carbonate.
4.​ Biogenic Deposits - formed by the accumulation of the skeletal
remains of organisms including plants, animals and microorganisms.