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PART X
IRONMAKING COURSE
March 12th, Belo Horizonte, Brazil
Coal Mining
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Coal Mining
Ground
DrillingExplosion
CoalCoal LayerLayer
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Coal Mining
Work of coal extracting from its natural environment, processing andtransportation to the place that it will be used.
Disassembly of the coal layer (drilling and / or detonation with explosives),
charging, transporting and crushing to a suitable size for further processing.
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Coal Mining
Stages of the coal industry
1. Exploratory
Geological ResearchGeophysical ResearchDrilling Research
2. Viability Studying
3. ExplorationMining DevelopmentMining OperationCoal processing
4. Transportation
5. Utilization
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Coal Mining
Activities before coal mining
Deposit
GeologyMineralogy
Mining methodsMineral processing
EconomyEnvironment
Planning
Mininh methods seletioninstallation needs
Project and engineering
OPENING AND
DEVELOPMENT
Opening of the pit andtunnels
Stripping
Surfaces and undergroundsconstructions
Coal localization and
avaliation
Local Geology
GeophysicsGeochemistry
DrillingSampling
Reserves evaluation
Drill ing (mash)Pit or tunnel drillingEvaluation
Mining
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Coal Mining
The first stage for the implantation of a mining unit is the establishment of aresearch program, drilling teams, using simultaneously several drilling machines,take the probe evidency.
Probe evidence are samples of 50 mm in diameter for definition of reserves /characterization of coal or 200 mm in diameter, in sufficient quantities for varioustests, including those of washability.
Tests can get information on coal quality on the geological layer characteristics,
providing a perfect project of the mine, of the preparation plant and thesubsequent use of coal.
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Coal Mining
E
X
PL
O
RA
T
O
R
Y
Probe
evidency
Probe or drill ingtower
Drilling columnTubes
First tube: drill
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Coal Mining
Organic Matter
Inorganic
Moisture
Organic Matter
Inorganic
Moisture
Float-Sink
Test
Complete characterization
Mining
BeneficiationApl icat ion
Complete characterization
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Coal Mining
Washability curve
It is made by the determination of the properties (ash, volatile matter and sulfur)of the fractions that sink to a certain density of the dense liquid and float intoanother density a bit higher. It also determines the percentage by weight of eachof these fractions.
Os valores acumulados so calculados, tabelando-se os rendimentos, matriavoltil, cinza e enxofre para os carves flutuados em diversas densidades. O
carvo metalrgico considerado como o flutuado em meio denso a vriasdensidades.
A planta de preparao projetada para remover a poro no-combustvel docarvo a um custo operacional mnimo e um rendimento timo.
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Coal Mining
Types of Coal Mining
UndergroundUnderground
Ground
DrillingExplosion
CoalCoal LayerLayer
Open Pit
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Coal Mining
Stages of coal mining
Mining
Disassembly
Charging Transport
Costs control
Environment
GeologySampling
ResearchDigging stability
Project and engineeringSuply services
EnergyMaintenanceOccupational health andsecurityVentilationWater controlLand recovering
ROM
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Coal Mining
Steps to coal mining:
Depth of coal layer.
Thickness of coal layer.
Quantity and type of sediments overlapped.
Quantity of water encountered.
Presence and quantity of gas in the layer.
Other geological conditions, roof stability, existence of igneous inclusions, dipangle of the layer, existence of flaws.
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Coal Mining
Open pit
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Coal Mining
Open Pit
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Coal Mining
Open Pit
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Coal Mining
Open Pit
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Coal Mining
Open Pit
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Coal Mining
Underground Mining
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Coal Mining
Underground Mining
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Coal Mining
Underground Mining
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Coal Mining
Underground Mining
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Coal Mining
Underground Mining
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Coal Mining
Underground Mining
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Coal Mining
Underground Mining
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Coal Mining
Underground mining
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Coal Mining
Underground Mining
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Coal Mining
Underground Mining
ChambersChambers andand pillarspillars
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Coal Mining
Underground mining Longwall
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Coal Mining
Underground Mining Longwall
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Coal Mining
Underground Mining Longwall
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Coal Mining
Coal Processing
Processing
ROM conversion toconsumable
products
ROM
Comsumption products
ClassificationProcessing
PesquisaDigging stability
Project and engineeringSuply services
EnergyMaintenanceOccupational health andsecurityVentilationWater controlLand recovery
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Coal Mining
Coal processing
RunRun--ofof--MineMine
vvVarietyVariety ofofsizessizes
vvHighHigh contentcontent ofof
impuritiesimpurities
ProcessProcess
vvCrushingCrushing
vvClassificationClassificationvvWashingWashing
vvDryingDrying
WashedWashed coalcoal
vvSmall rangeSmall range ofofsizessizes
vvLowLow contentcontent ofof impuritiesimpurities
The processing method use the density to remove impurities.
Magnetite is added to water to create an ambient in which multiple density levels arecreated.
Different qualities of coal are produced
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Coal Mining
Coal beneficiation
Tailing bunker
Clean coal Clean coal Clean coal
Thermal Dryer
Clean coal filter
Dewatering screen
Centrifuging
Dewatering screen
Froth Flotation
Tailing
CycloneTailing
Bathing with densefluid
Tailing
Fine coal Medium coal Thick coal
Run-of-Mine
Crusher
Tailing Thickner
Charging
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Coal Mining
Coal beneficiation
Pre-scrubber
Run-of-Mine55 to 60% of ash
1000 t
243 t
17 t
12 t 740 t
60 t 170 t
Scrubber
752 t
Fines (18% ash)Metalurgical Coal
(18% ash)Seam Coal
(30 to 40% ash)Tailings
(70 to 75% of ash)
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Coal Mining
Coal marketing
Consumption products
MARKETING
Coal forcokemaking
and oters uses.
Definition of coal typesStandards and specificationsTransport to the costumers
Materials science and technologyProperties and products uses.Ways of sales.
C l P i f Th C k O Pl
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Coal Preparation for The Coke Oven Plant
C l P ti S t
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Coal Preparation System
Storage yards
Marit ime Terminal
Railway transportation
Conveyors belt system
Dumper wagon
Coal sampler
Magnetic separator
Magnetic separator
Coal bunker
Scales system
Mechanical Mixer
Coal Blend BunkerBlending sampler Coke oven battery
Coal sampling
Crushing system
C D
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Car Dumper
CarCardumperdumperwithwith waterwatersprayssprays
AutomaticAutomatic weighingweighing andand emptyingemptying
Storage in Yards of Steel Industry
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Storage in Yards of Steel Industry
Dead storage (to prevent transportation problems and keep a steady flow) andalive storage (supplies directly the consumer or the means of transport): the coal
is removed from the dead and transferred to the alive.
Silo between regular consumption of coke oven battery and irregular receivingof ships.
Open storage (outdoor):is used for large capacity, due to its lower cost in
relation to the closed storage.
Storage in Yards of Steel Industry
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Storage in Yards of Steel Industry
Thick green belt around the yards.
Covered conveyor belts.
Stacking and removal of coal (distribution-reclaiming).
Individual Stacks by type of coal.
Increase the homogeneity of the coal.
Limiting the storage time to prevent more severe oxidation of coal.
Distribution by Stacker
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Distribution by Stacker
Distribution by Stacker-Reclaimer
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Distribution by Stacker-Reclaimer
Distribution by Stacker-Reclaimer
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Distribution by Stacker-Reclaimer
Maximum height of fall during stacking.Maximum height of fall during stacking.
Maximum height of stacks.Maximum height of stacks.
Stacks located appropriately in relation to the wind direction.Stacks located appropriately in relation to the wind direction.
Water spray systems on conveyor belts before stacking.Water spray systems on conveyor belts before stacking.
Automated system of spraying water in the stacks.Automated system of spraying water in the stacks.
Tailing ponds for contention of the material carried by the wateTailing ponds for contention of the material carried by the waters.rs.
Coal Distribution System by Stacker-Reclaimer
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Coal Distribution System by Stacker Reclaimer
The system consists of a feeder conveyor belt, a conveyor belt of reversecycle and a bucket wheel.
The coal is carried by the feed conveyor to an intermediate transfer point,
where it is transferred to a reverse conveyor belt, which takes the coal tothe point of storage.
Coal Distribution in Yards
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Coal Distribution in Yards
It should prevent the occurrence of segregation that makes the particles
of larger diameter be located in the outer and bottom stack zones and the
smaller diameter in the inner and higher stack zones. This arrangement
facilitates the movement of air currents through the larger particles, which
carry oxygen to the border region with smaller particles, due it has higher
specific surface are susceptible to oxidation, may generate hot points. It canlead to located deterioration of coal.
Segregation in Coal Stacks
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Segregation in Coal Stacks
Stacking Methods
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g
WWindrowindrow ,, chevronchevron ee conecone--shellshell
Windrow Method Parallel Stacks
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It is (with the stacker) a series of parallel stacks along the tyard, covering theentire area of the stack soil.
When the first series of steps is completed a second row of stacks is constructedby filling the gaps in the first serie of stacks.
The process continues until the entire stack is built (it can be flat-topped or not).
The advantage of this type of stack is that it avoids the segregation (thearrangement of thicker material for each step is restricted by the triangular
section)
The thick material is distributed consistently throughout the stack.
The method can be applied only if the scope of the stacker reaches the extremity
of the yard.
Chevron Method
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Consists in crossing from one side to another throughout the length of the courtwith the stacker arranged to feed the center of stack.
A small stack of triangular section is deposited along the length of the court in thefirst step of the stacker.
In the second step in the opposite direction a second chevron of coal will beplaced on the top of the first.
As the number of steps increases the stack increases in height and thickness of
chevrons reduces progressively (the same amount of material trying to cover aperimeter of increased cross section).
If there is thick coal the main disadvantage of these methods is that there will be
segregation and larger particles tend to be deposited in the lower and outsideparts of the stackl.
Depending on the method of reclaiming used this method may not give the resultsof homogeneity required.
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Evaluation in Yards Emissions
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Method for measuring emissions with wind tunnel (for stacks).Method for measuring the exposure profile (transfer points).Method of measurements of wind barriers (green belt).Quantification of settable dust (point counting technique on body-of-evidence produced from samples collected in different parts of the plant andin locations close to it).
Dreinage Water in Yards
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Drainage water from coal stacks may have three undesirable aspectsregarding the viewpoint of use:
high acidity, resulting from oxidation of pyrite (neutralization is madeby adding lime or limestone);
contain particulate matter in suspension by mechanical drag made
by percolation water (this material may have dimensions such that itbehaves as colloid, dispersing in the liquid mass with slowsedimentation rate), and
contain heavy metals (such as Fe, Pb, Zn, Cd and Hg) dissolved inwater, resulting from the leaching action of acidic water (these metalscan be precipitated at higher pH and removed with particulate materialin devices called classifiers or thickeners).
Unstacking: Reclaimer or Jib-Loader
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Unstacking of Coal in Yards
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With Reclaimer: the unstacking of coal is made by the bucket wheels whichtransfer the coal to reverse conveyor belt (now goes in the opposite direction)and will discharge it in the feed conveyor, which takes the coal for further
processing.
Types of Unstacking
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BenchBench cutcut, module, module cutcut ee harrowharrow cutcut..
Oxidation During Coal Storage
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Coal is a pyrophoric substance "spontaneous combustion" .
WIND
If the O2 penetrates the stack, itoxidizes.
Increase oftemperature.
If the heat generated is not wellremoved, it eventually ignites.
+ O2 H2O CO2+ + HEATC
H
Oxidation Consequences
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Reducing of rheological propertiesDecrease of the mechanical strength of coke
Control problems with charge density.
Variations in the coke production.Overheated charges.
Carbon deposit
Ovens deterioration
Increase of coke reactivity.
Decrease of coking rate.
Fines generation and difficult of handling.
Spontaneous combustion.
Sponge effect when adding oil.
Monitoring Oxidation Level
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Systematic monitoring of coal received quality (rheological properties)Observation and petrographic analysis
Extraction method with probe.
Steps to Prevent Oxidation
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Stacks compressionMonitoring and eliminating hot pointsMinimize pressure of the winds