Risk Assessment in the Quality Control of Oil Shale in

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


IntroductionMining technology overviewRisk assessment in miningMain factors determining quality of oil shaleOil shale enrichment Selective miningConclusion

Losses in pillars 20-28 %

Technological losses 13%

Oil Shale Mining Technology

Open mining

Selective (surface) mining



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



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



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%



Crushing

Screening

Sieving Flotation

ScreeningSeparation

Crushing

Flotation

Dewatering & Drying


Waste 38%



Crushing

Screening

Sieving Flotation

ScreeningSeparation(radiometric)

Crushing

Flotation

Dewatering & Drying


Waste 51%


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




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


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) 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


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]

[email protected]

Estonian Science foundation (Grand No. 6558, 2006-2009) supported the research

Documents

Risk Assessment in the Quality Control of Oil Shale in