Risk Assessment in the Quality Control of Oil Shale in Estonian Deposit
Sergei Sergei SabanovSabanov
DEPA
RTMENT OF MINING
28th Oil Shale SymposiumOctober 13-17, 2008
Presentation outline
IntroductionMining technology overviewRisk assessment in miningMain factors determination of oil shale qualityOil shale enrichment Selective miningConclusion
RUSSIA
ESTONIA
OIL SHALE BEDDING DEPTH, meters
UNDERGROUND OIL SHALE MINING FIELDS
CALORIFIC YIELD, SHOWS ACTIVE DEPOSIT
OIL SHALE RESEARCH FIELDS
MINED OUT AREAS
OIL SHALE OPEN CAST FIELDS
35 GJ/m235 GJ/m235 GJ/m235 GJ/m235 GJ/m235 GJ/m235 GJ/m235 GJ/m235 GJ/m2
25
IDA VIRU COUNTY
SirgalaSirgalaSirgalaSirgalaSirgalaSirgalaSirgalaSirgalaSirgalaopen castopen castopen castopen castopen castopen castopen castopen castopen cast
NarvaNarvaNarvaNarvaNarvaNarvaNarvaNarvaNarvaopen castopen castopen castopen castopen castopen castopen castopen castopen cast
PermiskülaPermiskülaPermiskülaPermiskülaPermiskülaPermiskülaPermiskülaPermiskülaPermisküla
GULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLANDGULF OF FINLAND
AhtmeAhtmeAhtmeAhtmeAhtmeAhtmeAhtmeAhtmeAhtme
PeipsiPeipsiPeipsiPeipsiPeipsiPeipsiPeipsiPeipsiPeipsi
PuhatuPuhatuPuhatuPuhatuPuhatuPuhatuPuhatuPuhatuPuhatu
35 GJ/m235 GJ/m235 GJ/m235 GJ/m235 GJ/m235 GJ/m235 GJ/m235 GJ/m235 GJ/m2
25 GJ/m225 GJ/m225 GJ/m2
25 GJ/m225 GJ/m2
25 GJ/m225 GJ/m225 GJ/m225 GJ/m2
SeliSeliSeliSeliSeliSeliSeliSeliSeli
ViruViruViruViruViruViruViruViruViru
EstoniaEstoniaEstoniaEstoniaEstoniaEstoniaEstoniaEstoniaEstonia
KohtlaKohtlaKohtlaKohtlaKohtlaKohtlaKohtlaKohtlaKohtla
OjamaaOjamaaOjamaaOjamaaOjamaaOjamaaOjamaaOjamaaOjamaa
Underground oil shale Underground oil shale Underground oil shale Underground oil shale Underground oil shale Underground oil shale Underground oil shale Underground oil shale Underground oil shale mining area, mining area, mining area, mining area, mining area, mining area, mining area, mining area, mining area,
abandoned minesabandoned minesabandoned minesabandoned minesabandoned minesabandoned minesabandoned minesabandoned minesabandoned minesAidu Aidu Aidu Aidu Aidu Aidu Aidu Aidu Aidu open castopen castopen castopen castopen castopen castopen castopen castopen cast
Uus KiviõliUus KiviõliUus KiviõliUus KiviõliUus KiviõliUus KiviõliUus KiviõliUus KiviõliUus Kiviõli
OanduOanduOanduOanduOanduOanduOanduOanduOandu
KiviõliKiviõliKiviõliKiviõliKiviõliKiviõliKiviõliKiviõliKiviõli
PuhatuPuhatuPuhatuPuhatuPuhatuPuhatuPuhatuPuhatuPuhatu
303030303030303030
808080808080808080707070707070707070
555555555555555555
606060606060606060
454545454545454545
656565656565656565
505050505050505050
404040404040404040
404040404040404040353535353535353535
151515151515151515
202020202020202020252525252525252525
303030303030303030
808080808080808080
353535353535353535
202020202020202020151515151515151515
252525252525252525
101010101010101010
101010101010101010
Oil shale in Estonia
Annual production of oil shale
Million tonesViru mine 2Estonia mine 5Narva open cast 5Aidu open cast 2Põhja kiviõli open cast 1Ubja open cast 0.3 Average 15 -16
Characteristics of the oil shale and limestone seams
1 kWh ~ 1.4 kg of oil shaleShale oil ~16 %
Calorific value Kerogen Volume weightGJ/t % t/m3
F2 0.17 6.7 19 24 1.72F1/F2 0.18 2.9 8 65 2.10
F1 0.20 11.5 31 19 1.51F 0.42 11.5 33 18 1.51E 0.58 17.5 50 18 1.28
D/E 0.07 2.9 8 67 2.10D 0.06 9.4 27 29 1.59
C/D 0.29 0.6 2 82 2.45C 0.41 14.2 40 26 1.38
B/C 0.12 2.9 8 75 2.10B 0.38 19.2 54 40 1.22
A1/B 0.18 1.3 4 65 2.25A1 0.09 7.5 21 26 1.42
A/A1 0.06 2.9 8 32 2.10A 0.12 15.1 43 32 1.37
Layers index Lithology Thickness, m Compressive
strenght, MPa
Problems
Raw material - extracted rock mass without enrichment does not meet requirements of customers for calorific valuesDecreasing calorific values in peripheral sides of the commercial oil shale deposit will demand additional enrichment of oil shale
Aim
Elaboration of the risk assessment methods for quality control of oil shale in according with technical opportunities of extraction and enrichment processes for various parts of Estonian deposit
Presentation outline
IntroductionMining technology overviewRisk assessment in miningMain factors determining quality of oil shaleOil shale enrichment Selective miningConclusion
Presentation outline
IntroductionMining technology overviewRisk assessment in miningMain factors determining quality of oil shaleOil shale enrichment Selective miningConclusion
Why is Risk Assessment?
Risk assessment is the process of deciding whether existing risks are tolerable and risk control measures are adequate
RISK ANALYSIS RISK EVALUATION
Risk identification
RISK ASSESSMENT
Risk estimation
Risk mitigation
Risk acceptance
Risk analysis is used for performing safety assessment for many different mining systems. Risk analysis includes: scope and risk analysis plan definition, risk identification, risk estimation
Risk identification is the process of determining potential risks and starts with the source of problems, or with the problem itself. Failure can be described on many different levels. Conceptualization of the different possible failure modes for mining systems is an important part of risk identification.
Risk estimation entails the assignment of probabilities to the events and responses identified under risk identification. Probability estimation can be grouped into three general approaches depending on the type and quality of the available data: analytical approach uses logical models for calculating probabilities; empirical approach uses existing databases to generate probability; judgmental approach uses experience of practicing engineers in guiding the estimation of probabilities
Risk Analysis
Risk EvaluationThe principal role of risk evaluation in risk assessment is the generation of decision guidance against which the results of risk analysis can be assessed
Risk mitigation is a selective application of appropriate techniques and management principles to reduce either likelihood of an occurrence or its consequences, or both
Risk acceptance is an informed decision to accept the likelihood and the consequences of a particular risk
Presentation outline
IntroductionMining technology overviewRisk assessment in miningMain factors determining quality of oil shaleOil shale enrichment Selective miningConclusion
Main factors determining oil shale quality
EnvironmentalEnvironmental
Oil shale seam quality deterioration is controlled by two factors -increasing fraction of limestone and decreasing calorific value.
Calorific value and layer thickness vary from place to place within a deposit.
These parameters decrease from the center to the border of a deposit. The variation in the value of the calorific value comes to 0.07 MJ/kg per km.
Main factors determination of oil shale quality
TechnologicalTechnological
Oil shale quality depends on the enrichment process
Oil shale enrichment process depends on the grain-size, the calorific value, the size category distribution and the availability of karst clay
Distribution of size and calorific value directly depend on excavation technology: drilling-and-blasting and mechanical cutting
The share of fine grain-size material (0-30 mm) comprises 30-40% and calorific value is 2.5-3.0 MJ/kg higher than calorific value of raw material (rock mass)
Drilling-and-blastingSize destribution
Drill/Blast
y = 0,0491x0,519
R2 = 0,9906
0,000,100,200,300,400,500,600,700,800,90
0 50 100 150 200 250 300Size, mm
Con
tent
Drilling-and-blastingPower distribution
Drill/Blast
y = -0,265Ln(x) + 11,015R2 = 0,7052
6
8
10
12
14
0 25 50 75 100 125 150 175 200 225 250 275 300
Size, mm
Cal
orifi
c va
lue,
MJ/
kg
The fine grained fraction (3.0-10.0 mm) has calorific value of 11.6-12.4 MJ/kg, but about 5 % of the fine grain > 1 mm which includes clay material will complicate the enrichment process.
Selective mining(Mechanical cutting)
Size distributionSelective mining
y = 0,1124Ln(x) + 0,1639R2 = 0,8677
0,00
0,20
0,40
0,60
0,80
1,00
0 10 20 30 40 50 60 70 80 90 100 110 120 130
Size, mm
Con
tent
Selective mining(Mechanical cutting)
To achieve oil shale with calorific value 11.8-12.5 MJ/kg it is necessary to realize selective cutting not only of limestone and oil shale layers, but separately oil shale layers with concretions
Power distributionSelective mining
y = -0,1114Ln(x) + 12,869R2 = 0,6328
11,0
11,5
12,0
12,5
13,0
13,5
14,0
0 25 50 75 100 125 150 175 200 225 250 275 300 325
Size, mm
Cal
orifi
c va
lue,
MJ/
kg
Presentation outline
IntroductionMining technology overviewRisk assessment in miningMain factors determining quality of oil shaleOil shale enrichment Selective miningConclusion
Oil shale enrichment
AdvantageStructure of oil shale and accompanying breed (limestone) has differences in properties. It gives possibility to easily enrich by gravitational methods.DisadvantageAs a result of the deterioration of oil shale quality in peripheral areas of the deposit, there arise problems in enrichment of the fine grain (0-25mm) fraction.
Run-of-mine (0-700 mm) 100% - 9.22 MJ/kg
Selective crushing
Screening
Sieving Flotation
ScreeningSeparation
Crushing
Flotation
Dewatering & Drying
Trade product 71% – 14.41 MJ/kg
Waste 29%
Oil shale enrichment
Run-of-mine (0-400 mm) 100% - 8.37 MJ/kg
Crushing
Screening
Sieving Flotation
ScreeningSeparation
Crushing
Flotation
Dewatering & Drying
Trade product 62% – 11.62 MJ/kg
Waste 38%
Oil shale enrichment
Run-of-mine (0-50 mm) 100% - 7.6 MJ/kg
Crushing
Screening
Sieving Flotation
ScreeningSeparation(radiometric)
Crushing
Flotation
Dewatering & Drying
Trade product 49% – 11.8 MJ/kg
Waste 51%
Oil shale enrichment
Quality-quantitive characteristic of slimes output in “Estonia” mine
0
5
10
15
20
25
Cal
orifi
c va
lue,
MJ/
kg
3.00-1
.001.0
0-0.63
0.63-0
.380.3
8-0.25
0.25-0
.160.1
6-0.10
0.10-0
.070.0
7-0.05
0.05-0
.00
size, mm
Dewatering of slime under using centrifuge is possible to exclude about 60 % of slime having sizes 0.7-1.0 mm. At the same time, slime with dampness 25-30 % will be transported together with non enriched riddling. The solids represent 50 % of size 0.01 mm
Usage of the hydrocyclones, filter-press, pneumatic separators and centrifuges for enrichment of fine grained fraction of oil shale showed the possibility of increasing the calorific value
Oil shale enrichment
Presentation outline
IntroductionMining technology overviewRisk assessment in miningMain factors determining quality of oil shaleOil shale enrichment Selective miningConclusion
limestone 0.37 5.78
H 0.4 5.41
G/H 0.25 5.01
G 0.39 4.76
limestone 0.05 4.37F5 0.06 4.32
limestone 0.22 4.26F4 0.06 4.04
limestone 0.17 3.98
F3 0.37 3.81
limestone 0.11 3.44F1/2 0.17 3.33
limestone 0.18 3.16Fü 0.20 2.98
Fa 0.422.78
E 0.58
2.36
D/E 0.07 1.78D 0.06 1.71
C/D 0.29 1.65
C 0.411.36
B/C 0.12 0.95
B 0.38 0.83
A1/B 0.18 0.45
A1 0.09 0.27A/A1 0.06 0.18
A 0.12 0.12
Seam Lithology Thickness, m
Height from A seam, m
B + C
13% limestone
A +B +C
limestone 27%
Selective mining
Go to backfill
79 % of limestone
Go to backfill
86 % of limestone
A + A1
52% limestone
Go to backfill
63 % of limestone
I
II
III
IV
Extraction 1
Extraction 2
Selective miningUnderground
Selective (surface) mining
Surface Miner
Cutting depth up to 0.6 mCutting depth up to 0.6 m
Cutting widthCutting width -- 2.5 m2.5 m
d0=40mm
– cutting in oil-shale EF (0.43m)
–cutting in limestone seams A/B (0.18m) and C/D (0.25m)
– cutting in oil-shale B/C(0.36m)
Selective (surface) mining
Selective (surface) miningSurface Miner can cut limestone and oil shale seams separately and more exactly than rippers (2-7 cm) with deviations about one centimeterPrimary crushing and fragmentation of mineral rockSeparately extracted limestone (C/D and A'/B) can be left directly in mine, which reduces haul costs and increase run-out oil shale heating value without additional processingLess stress and strain on trucks due to minimum impact of the excavated material Reduce capacity requirements for preparation plants
Improve mineral recovery especially in areas sensitive to blastingDue to precise cutting increase the output of oil shale up to one tonne per square meter The oil yield increase by 30%, up to 1 barrel per tone during the oil shale retorting, on account of the better qualityDecrease mineral losses from 13% to 6% and dilutionReduce oil shale cost price by 20% due to less mineral losses
Selective (surface) mining
Summary
Risk assessment allows selecting suitable means for enhancing the quality of oil shale using different mining technology in various parts of Estonian deposits and has the ability to solve problems of quality control of oil shale in accordance with technical opportunities for extraction and enrichment processes
Conclusions
Risk assessment methods assist in the selection of correct technological aspects for prospective development of mining under various mine-geological conditions
Thank You for Your attention!Thank You for Your attention!
DEPA
RTMENT OF MINING
Contact information:
Sergei Sabanov
Ph.D., Senior Researcher
Department of Mining
Tallinn University of Technology, Estonia
E- mail: [email protected]
Estonian Science foundation (Grand No. 6558, 2006-2009) supported the research