Coal Bioprocessing Drew Hill BKB Co., Ltd. Outline Coal Coal What is Coal What is Coal Relevance of...
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Transcript of Coal Bioprocessing Drew Hill BKB Co., Ltd. Outline Coal Coal What is Coal What is Coal Relevance of...
Coal Coal BioprocessingBioprocessing
Drew HillDrew Hill
BKB Co., LtdBKB Co., Ltd
OutlineOutline CoalCoal
What is CoalWhat is Coal Relevance of BioprocessingRelevance of Bioprocessing
Advantages of BioprocessingAdvantages of Bioprocessing Why Remove SulfurWhy Remove Sulfur
Coal ProcessingCoal Processing GasificationGasification LiquefactionLiquefaction BeneficiationBeneficiation
ConclusionsConclusions ReferencesReferences
What is Coal?What is Coal?
Over three hundred million years ago Over three hundred million years ago the vegetation of the earth died and the vegetation of the earth died and drifted down to the bottom of the drifted down to the bottom of the swamps. That dead vegetation formed swamps. That dead vegetation formed peat, which is a soggy sponge like peat, which is a soggy sponge like material, and as this material built up material, and as this material built up it was compressed under the earth’s it was compressed under the earth’s surface. Over the millions of years of surface. Over the millions of years of intense heat and pressure compressed intense heat and pressure compressed this organic matter into coal.this organic matter into coal.
Coal is Still Being Coal is Still Being FormedFormed
The process of forming coal is still The process of forming coal is still occurring today in the US in such occurring today in the US in such places asplaces as Great Dismal Swamp of North Carolina Great Dismal Swamp of North Carolina
and Virginiaand Virginia Okefenokee Swamp in GeorgiaOkefenokee Swamp in Georgia Everglades in FloridaEverglades in Florida
Categorizing CoalCategorizing Coal
Coal is broken down into four Coal is broken down into four categories according to the carbon categories according to the carbon content content LigniteLignite (soft) (soft) SubbituminousSubbituminous (medium-soft) (medium-soft) BituminousBituminous (medium-hard) (medium-hard) AnthraciteAnthracite (hard) (hard)
Soft CoalSoft Coal
LigniteLignite This type of coal contains a lot of moisture This type of coal contains a lot of moisture
and breaks apart easily. Of the four types, and breaks apart easily. Of the four types, lignite contains the least amount of carbon. lignite contains the least amount of carbon. Also called brown coal, lignite is used Also called brown coal, lignite is used mainly at electricity-generating plants mainly at electricity-generating plants
Medium Soft CoalMedium Soft Coal
SubbituminousSubbituminous This type of coal has less moisture than This type of coal has less moisture than
lignite. Subbituminous coal is generally lignite. Subbituminous coal is generally used to produce steam for electricity used to produce steam for electricity generation. Reserves of subbituminous generation. Reserves of subbituminous coal are found mostly in the western coal are found mostly in the western United States and Alaska.United States and Alaska.
Medium Hard CoalMedium Hard Coal
BituminousBituminous This type of coal, which contains very little This type of coal, which contains very little
moisture, has high heat value. It is used to moisture, has high heat value. It is used to generate electricity and to produce generate electricity and to produce coke, a , a coal residue used in the steel industry. coal residue used in the steel industry. Bituminous coal is the most plentiful type in Bituminous coal is the most plentiful type in the United States.the United States.
Hard CoalHard Coal
AnthraciteAnthracite This type of coal has the highest carbon This type of coal has the highest carbon
content. Anthracite burns slowly and content. Anthracite burns slowly and makes a good heating fuel for homes. The makes a good heating fuel for homes. The United States has about 7.3 billion tons of United States has about 7.3 billion tons of anthracite, most of which can be found in anthracite, most of which can be found in Pennsylvania. Pennsylvania.
Coal UseCoal Use
Coal, being used to heat the tunnels Coal, being used to heat the tunnels of cavemen, has been a source of of cavemen, has been a source of energy for as long as man can energy for as long as man can remember. In America the Native remember. In America the Native Americans were using coal as far Americans were using coal as far back as the twelfth century for back as the twelfth century for cooking and heating.cooking and heating.
Coal UseCoal Use Coal continues today to be a Coal continues today to be a
major source of energy in major source of energy in the United Sates as the the United Sates as the American Coal Foundation American Coal Foundation reports in Coal's Past, reports in Coal's Past, Present, and Future “Nine Present, and Future “Nine out of every ten tons of coal out of every ten tons of coal mined in the United States mined in the United States today is used to generate today is used to generate electricity. About 56 percent electricity. About 56 percent of the electricity used in this of the electricity used in this country is coal-generated country is coal-generated electricity.” electricity.”
Coal AbundanceCoal Abundance
The United States has a supply of coal that will The United States has a supply of coal that will last over three hundred years at the current last over three hundred years at the current usage rate which is promising as coal is more usage rate which is promising as coal is more cost effective than oil or natural gas. Current cost effective than oil or natural gas. Current prices of energy as listed by the American Coal prices of energy as listed by the American Coal Foundation in Coal's Past, Present, and Future Foundation in Coal's Past, Present, and Future are: are:
Reported in cost per million Reported in cost per million Btu’sBtu’s
CoalCoal $1.20$1.20
OilOil $4.45$4.45
Natural gasNatural gas $4.30 $4.30
Coal MiningCoal Mining
Surface MiningSurface Mining Room and Pillar MiningRoom and Pillar Mining Longwall MiningLongwall Mining
Surface MiningSurface Mining During surface mining During surface mining
the land is bulldozed the land is bulldozed and leveled off. Next and leveled off. Next the topsoil is cleared the topsoil is cleared and stored for later land and stored for later land reclamation. Next they reclamation. Next they drill smaller holes into drill smaller holes into the overburden, which the overburden, which is rock sitting above the is rock sitting above the desired coal. This desired coal. This overburden is exploded overburden is exploded and removed so the and removed so the desired coal can be desired coal can be picked up and placed picked up and placed into trucks to be into trucks to be separated and prepared separated and prepared for use .for use .
Room and Pillar MiningRoom and Pillar Mining Room and pillar mining Room and pillar mining
requires no blasting and is requires no blasting and is similar to what most people similar to what most people think of when they think think of when they think mining as can be seen by the mining as can be seen by the picture Coal: All you really picture Coal: All you really wanted to know. Large holes wanted to know. Large holes are drilled in the ground are drilled in the ground using a large tungsten drill using a large tungsten drill that follows the coal seam. As that follows the coal seam. As the coal is drilled away it is the coal is drilled away it is added to a conveyor belt and added to a conveyor belt and transported to the surface to transported to the surface to the dump trucks. Once the the dump trucks. Once the desired depth is met roof desired depth is met roof bolts are placed to prevent bolts are placed to prevent collapsing and the drills are collapsing and the drills are backed out. backed out.
Long Wall MiningLong Wall Mining Longwall mining Longwall mining
involves running a involves running a large tungsten cutting large tungsten cutting machine along a wall, machine along a wall, between four hundred between four hundred to six hundred feet, of to six hundred feet, of the coal seam. The the coal seam. The coal knocked off the coal knocked off the wall falls on a large wall falls on a large conveyor which conveyor which transports the coal to transports the coal to the surface.the surface.
Advantages of Advantages of BioprocessingBioprocessing
Biological systems offer a number of Biological systems offer a number of advantages over conventional advantages over conventional approaches, though their application is approaches, though their application is not appropriate in every situationnot appropriate in every situation Potential for processing low-grade depositsPotential for processing low-grade deposits Re-processing earlier metal-containing Re-processing earlier metal-containing
wasteswastes Production of less chemically-active tailingsProduction of less chemically-active tailings Lower energy inputsLower energy inputs Other environmental benefits such as zero Other environmental benefits such as zero
production of noxious gases production of noxious gases
Why Remove SulfurWhy Remove Sulfur Acid rain is precipitation Acid rain is precipitation
more acidic than normal more acidic than normal rain and snow, which is rain and snow, which is slightly acidic with a pH slightly acidic with a pH of 5.6 because of the of 5.6 because of the carbon dioxide dissolved carbon dioxide dissolved in itin it
Sites downwind of Sites downwind of industrial areas have industrial areas have had a pH close to 4.5 had a pH close to 4.5 and sometimes as low as and sometimes as low as 2.1 (equivalent to lemon 2.1 (equivalent to lemon juice) juice)
Categories of Coal Categories of Coal ProcessingProcessing
GasificationGasification LiquefactionLiquefaction BeneficiationBeneficiation
GasificationGasification
Coal is combined with steam and air Coal is combined with steam and air at high temperatures and high at high temperatures and high pressurespressures
Produces “syngas” (made up Produces “syngas” (made up primarily of Hprimarily of H22 and CO)” and a solid and CO)” and a solid ash waste product is remains at the ash waste product is remains at the bottombottom
After this the ash is removed and the After this the ash is removed and the gas is purified. gas is purified.
GasificationGasification
GasificationGasification
Primary impurities include gaseous ammonia Primary impurities include gaseous ammonia and sulfur compounds as well as other and sulfur compounds as well as other particulatesparticulates
Uses for syngas includeUses for syngas include Chemical feedstockChemical feedstock Substitute natural gas, after adjusting the Substitute natural gas, after adjusting the
composition for conversion into products such ascomposition for conversion into products such as Pure hydrogenPure hydrogen MethanolMethanol AmmoniaAmmonia Acetic anhydrideAcetic anhydride Various hydrocarbon fuelsVarious hydrocarbon fuels
LiquefactionLiquefaction
DirectDirect One phaseOne phase Two phaseTwo phase
IndirectIndirect
Liquefaction: DirectLiquefaction: Direct
Direct – Aim to add hydrogen to the Direct – Aim to add hydrogen to the organic structure of the coal, breaking it organic structure of the coal, breaking it down only as far as is necessary to down only as far as is necessary to produce distillable liquidsproduce distillable liquids
Many different process, but common Many different process, but common featuresfeatures Dissolution of a high proportion of coal in a Dissolution of a high proportion of coal in a
solvent at elevated temperature and pressuresolvent at elevated temperature and pressure Followed by the hydrocracking of the Followed by the hydrocracking of the
dissolved coal with Hdissolved coal with H22 and a catalyst and a catalyst
Liquefaction: DirectLiquefaction: Direct
Direct One Phase – A single-stage Direct One Phase – A single-stage direct liquefaction process gives direct liquefaction process gives distillates via one primary reactor or distillates via one primary reactor or a train of reactors in seriesa train of reactors in series
Such processes may includeSuch processes may include Integrated on-line hydrotreating Integrated on-line hydrotreating
reactor, which is intended to upgrade reactor, which is intended to upgrade the primary distillates without directly the primary distillates without directly increasing the overall conversion increasing the overall conversion
Liquefaction: DirectLiquefaction: Direct Direct Two Phase – A two-stage direct Direct Two Phase – A two-stage direct
liquefaction process is designed to give liquefaction process is designed to give distillate products via two reactors or distillate products via two reactors or reactor trains in seriesreactor trains in series Primary function of the first stage is coal Primary function of the first stage is coal
dissolution and is operated either without a dissolution and is operated either without a catalyst or with only a low-activity catalyst or with only a low-activity disposable catalystdisposable catalyst
The heavy coal liquids produced in this way The heavy coal liquids produced in this way are hydrotreated in the second stage in the are hydrotreated in the second stage in the presence of a high-activity catalyst to presence of a high-activity catalyst to produce additional distillate produce additional distillate
Liquefaction: IndirectLiquefaction: Indirect
Indirect liquefaction involvesIndirect liquefaction involves First, the complete breakdown of the coal First, the complete breakdown of the coal
structure by gasification with steamstructure by gasification with steam Next, the composition of the gasification Next, the composition of the gasification
products is then adjusted to give the products is then adjusted to give the required mixture of Hrequired mixture of H22 and CO, and to and CO, and to remove sulfur-containing catalyst poisonsremove sulfur-containing catalyst poisons
Finally, the resulting ‘synthesis gas’ is Finally, the resulting ‘synthesis gas’ is reacted over a catalyst at relatively low reacted over a catalyst at relatively low pressure and temperature pressure and temperature
BeneficiationBeneficiation
Physical CleaningPhysical Cleaning Chemical CleaningChemical Cleaning Biological CleaningBiological Cleaning
Beneficiation: Physical Beneficiation: Physical CleaningCleaning
Gravity Separation – During physical Gravity Separation – During physical cleaning undesired substances such as cleaning undesired substances such as dirt, rocks, and pyretic sulfur are dirt, rocks, and pyretic sulfur are removed from the coal. When added to removed from the coal. When added to water these impurities separate from the water these impurities separate from the coal due to the difference in the density coal due to the difference in the density of coal and other substances.of coal and other substances.
Magnetic Separation – Use of Magnetic Separation – Use of hydrocyclones to centrifuge out hydrocyclones to centrifuge out unwanted particulates. unwanted particulates.
Beneficiation: Physical Beneficiation: Physical CleaningCleaning
Froth Flotation – Coal Froth Flotation – Coal is coated with a is coated with a chemical, finely chemical, finely ground, and mixed ground, and mixed with water. The with water. The chemical coating chemical coating enables the coal to enables the coal to attach to the rising air attach to the rising air bubbles in the mixture bubbles in the mixture which allows nearly all which allows nearly all inorganic matter to inorganic matter to sink to the bottom of sink to the bottom of the flotation column.the flotation column.
Beneficiation: Chemical Beneficiation: Chemical CleaningCleaning
Chemical treatment involves the use Chemical treatment involves the use of strong acids, bases or salts. It is of strong acids, bases or salts. It is usually applied at elevated usually applied at elevated temperatures, varying between temperatures, varying between 200ºC and 300ºC, and is 200ºC and 300ºC, and is characterized by limited selectivity.characterized by limited selectivity.
Beneficiation: Biological Beneficiation: Biological CleaningCleaning
Bioleaching – Two different Bioleaching – Two different mechanisms for biologically mechanisms for biologically catalyzed oxidation of pyrite (sulfur catalyzed oxidation of pyrite (sulfur combined with iron)combined with iron) DirectDirect IndirectIndirect
Direct BioleachingDirect Bioleaching
Requires direct contact between the Requires direct contact between the bacterium and the pyrite.bacterium and the pyrite.
Generally not favored as with some Generally not favored as with some coals the microorganisms are too coals the microorganisms are too large to fit inside the coal pores.large to fit inside the coal pores.
Reaction:Reaction:2 FeS2 FeS22 + 7 O + 7 O22 + 2 H + 2 H22O → 2 FeSOO → 2 FeSO44 + 2 H + 2 H22SOSO44
Indirect BioleachingIndirect Bioleaching
The indirect method is more The indirect method is more prominent due to the limiting size of prominent due to the limiting size of the coal pores compared to the size the coal pores compared to the size of the microorganism. of the microorganism.
ReactionsReactionsFeSFeS22 + 14 Fe + 14 Fe3+3+ + 8 H + 8 H22O → 15 FeO → 15 Fe2+2+ + 16 H + 16 H++
+ 2 SO+ 2 SO44
2 Fe2 Fe2+2+ + 2 H + 2 H++ + O + O22 → 2 Fe → 2 Fe3+3+ + H + H22OO
BioleachingBioleaching
Bioremediation of Mine Bioremediation of Mine WaterWater
Acidic, sulfur rich wastewaters are Acidic, sulfur rich wastewaters are produced from the mining process of coalproduced from the mining process of coal
Contain many free metals such as iron, Contain many free metals such as iron, aluminum, manganese, and other metalsaluminum, manganese, and other metals
Generally, the mine water is controlled Generally, the mine water is controlled during the mining operation, as the water during the mining operation, as the water table level is kept low, but once the table level is kept low, but once the mines are abandoned the water table mines are abandoned the water table reboundsrebounds
Bioremediation of Mine Bioremediation of Mine WaterWater
Two main methods are used todayTwo main methods are used today WetlandsWetlands BioreactorsBioreactors
WetlandsWetlands
AdvantagesAdvantages Low maintenanceLow maintenance Solid-phase products of water treatment Solid-phase products of water treatment
are retained within the wetland sedimentsare retained within the wetland sediments DisadvantagesDisadvantages
Expensive to installExpensive to install Require more land area than is available Require more land area than is available
or suitableor suitable Performance is less predictable than Performance is less predictable than
chemical treatment systemschemical treatment systems
WetlandsWetlands Aerobic wetlands are used to treat net alkaline Aerobic wetlands are used to treat net alkaline
waters using the oxidation of ferrous iron, and waters using the oxidation of ferrous iron, and subsequent hydrolysis of the ferric iron subsequent hydrolysis of the ferric iron produced, which is a net acid-generating produced, which is a net acid-generating reaction seen below:reaction seen below:
4Fe2+ + O2 + 4H+ → 4Fe3+ +2H2O4Fe2+ + O2 + 4H+ → 4Fe3+ +2H2O4Fe3+ + 4H2O → 4Fe(OH)3 + 12H+4Fe3+ + 4H2O → 4Fe(OH)3 + 12H+
Shallow systemsShallow systems Work by surface flowWork by surface flow
Macrophytes are rooted plants submerged, Macrophytes are rooted plants submerged, floating, or emergent present within a stream floating, or emergent present within a stream Aesthetic reasonsAesthetic reasons Regulate water flowRegulate water flow Stabilizing the accumulating ferric precipitates Stabilizing the accumulating ferric precipitates
BioreactorsBioreactors
Occur in compost bioreactorsOccur in compost bioreactors GenerateGenerate
Net alkalinityNet alkalinity Biogenic sulfideBiogenic sulfide
Treat mine waters that areTreat mine waters that are Net acidicNet acidic Metal-rich Metal-rich
BioreactorsBioreactors
Compost for bioreactors are a mix ofCompost for bioreactors are a mix of Biodegradable materials such as Biodegradable materials such as
manure manure Slow degrading material, depending on Slow degrading material, depending on
local availability, such aslocal availability, such as PeatPeat SawdustSawdust StrawStraw
BioreactorsBioreactors First, contaminated water is forced through a layer of First, contaminated water is forced through a layer of
compostcompost To reduce iron and sulfateTo reduce iron and sulfate
Then, through a layer of limestoneThen, through a layer of limestone To add alkalinityTo add alkalinity
Finally, into a sedimentation pond and/or an aerobic Finally, into a sedimentation pond and/or an aerobic wetlandwetland to precipitate and retain iron hydroxides to precipitate and retain iron hydroxides
ConclusionConclusion
Biological systems offer a number of Biological systems offer a number of advantages over conventional advantages over conventional approachesapproaches Potential for processing low-grade Potential for processing low-grade
depositsdeposits Processing metal-containing wastesProcessing metal-containing wastes Can remove finely dispersed sulfurCan remove finely dispersed sulfur Control pH of mine waterControl pH of mine water Lower energy inputsLower energy inputs
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