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LIQUEFACTION

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Carrying solid bulk cargoes involves serious risks, which must be managed carefully to safeguard the crew and the ship. These risks include reduced ship stability, and even capsizing, due to cargo liquefaction.

Liquefaction is now seen as a major hazard for bulk carriers. The topic is receiving increasing attention from all industry stakeholders and from the media, because apart from the too high cost of lives, the loss of a ship and its cargoes is very

expensive and raises the amount of the insurance policy.

The main legislation governing safe carriage of solid bulk cargoes is the International Maritime Solid Bulk Cargoes (IMS-BC) Code, which became mandatory on January 1, 2011

SNF has specially designed FLODRI IOS polymers to capture the water within the ore particles, preventing the rise of pore water pressure, which can lead to liquefaction.

The chemical or metallurgical properties of the ores are not changed, only the physical state is changed.

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LIQUEFACTION is a phenomenon wherein a mass of soil loses a large percentage of its shear resistance, when subjected to transient or periodic loading, and flows in a manner resembling a liquid. Since the holds of bulk carriers are not designed to carry liquid, the following points merit scrutiny:

- The loading conditions: an accident on one vessel is often followed by a new accident, or near-accident, on other vessels that have loaded a similar cargo at terminals in the same area and under the same weather conditions.

- The difficulty to comprehend or to carry out the sampling procedures at loading ports when the ores nature changes (size distribution, clay gangue)

- The effectiveness of the test methods used to determine the Transport Moisture Limit of solid bulk cargoes as dictated by the IMSBC CODE

- The accidents happen very fast: the liquefaction of the cargo affects the stability of the vessel, resulting in the vessel capsizing very quickly, sometimes within a few minutes. There is no time for remedial measures or for safe evacuation of the ship. Such accidents are often associated with tragic losses of crew members.

GLOSSARYIMO: International Maritime Organization is a specialized agency of the United Nations that is responsible for measures to improve the safety and security of international shipping and to prevent marine pollution from ships.

IMSBC Code: Code issued by the IMO to facilitate the safe stowage and shipment of solid bulk cargoes. Concerning safety, solid bulk cargoes are divided into three groups, A B and C.

- Group A: consists of cargoes which may liquefy if shipped at moisture content above their transportable moisture limit - Group B: consists of cargoes which possess a chemical hazard which could give rise to a dangerous situation on a ship. - Group C: consists of cargoes which are neither liable to liquefy (Group A) nor to possess chemical hazards (Group B)

FMP: Flow Moisture Point measure the water content, expressed as a percentage, at which a sample of cargo will begin to lose shear strength. To meet required moisture levels for loading and maritime insurance criteria, the ores must be tested through several analytical trials issued by the IMO, and presented in the 2012 IMSBC Code.

TML: Transport Moisture Limit, maximum moisture content of a cargo that is considered safe for transportation in ships. It is calculated as 90 per cent of the Flow Moisture Point (FMP).

DWT: Deadweight tonnage - Max mass a vessel can carry without risks (cargo + crew + fuel + ballast).

Bulk Carrier Subclass DWT (tonnes)

General Bulker < 10 000

Handysize 10 000 – 40 000

Handymax / Supramax 40 000 – 60 000

Capesize > 100 000

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danger of cargo liquefaction

© Courtesy of the Hong kong Government Flying Service

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LIQUEFACTION ACCIDENTS

The accidents listed resulted in the loss of 214 lives and 21 vessels. The list doesn’t include incidents where vessels have safely reached port.

Date of accident Vessel name DWT ‘000 T Lives lost Lost of Vessel Cargo type Route Ship type

16/12/1988 Mega Taurus 30 20 Yes Nickel Ore Philippines - Japan Handysize

24/08/1991 Melete 72 25 Yes Iron Ore Australia - England handymax

26/08/1998 Sea prospect 21 10 Yes Nickel Ore Indonesia - Japan Handysize

20/05/2005 Hui Long 15 0 Yes Fluorspar Indonesia - China Handysize

27/09/2007 Heng Tai 16 2 Yes Iron Ore India - Bangladesh Handysize

27/11/2007 Mezzenine 19 26 Yes Iron Ore Indonesia - China Handysize

17/07/2009 Asia Forest 14 0 Yes Iron Ore India - China Handysize

30/08/2009 Hodasco 15 6 0 Yes Iron Ore India - China General Bulker

09/09/2009 Black Rose 38 1 Yes Iron Ore India - China Handymax

27/10/2010 Jian Fu Star 45 13 Yes Nickel Ore Indonesia - China Handymax

10/11/2010 Nasco Diamond 57 22 Yes Nickel Ore Indonesia - China Handymax

03/12/2010 Hong Wei 50 10 Yes Nickel Ore Indonesia - China Handymax

21/11/2011 Bright Ruby 26 6 Yes Iron Ore Malaysia - China Handymax

25/12/2011 Vinalines Queen 56 22 Yes Nickel Ore Indonesia - China Handymax

22/01/2012 Sun Spirits 11 0 Yes Iron Ore Philippines - China Handysize

16/02/2013 Harita Bauxite 50 15 Yes Nickel Ore Indonesia - China Handymax

14/08/2013 Trans Summer 57 0 Yes Nickel Ore Indonesia - China Handymax

12/10/2013 Bingo 9 0 yes Iron Ore India - China General Bulker

04/04/2014 Grand Fortune 22 13 Yes Iron Ore North Korea - China Handysize

02/01/2015 Bulk Jupiter 47 18 Yes Bauxite Malaysia - China Handymax

13/10/2017 Emerald Star 57 11 Yes Nickel Ore Indonesia - China Handymax

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North Korea5%

Australia5%

Malaysia

Philippines

India

Indonesia

Cargoes

Nickel Ores and Iron Ores are the main ores involved in the liquefaction accidents. The main contributing factors are:

The cargoes in question are either unprocessed ores or concentrates, which have common characteristics: the fines and the clay contents. The moisture is difficult to control. Thereby, the traditional «can-test» can give misleading results, that is why IMO has issued the IMSBC Code.

Tropical climate of the regions where the respective bulk carriers load.

The locations of the ports where cargoes are loaded are often remote and underequipped to perform an efficient Sampling Method and TML measurement.

Southeast Asian countries were involved in most liquefaction accidents, and casualties, due to:

The exportation of Nickel ores, with high clay content.

The expanding Chinese markets mainly due to the increasing demand for these minerals from China, Japan and South Korea which have amplified Southeast Asian maritime traffic: iron ore fines, mainly exported from India, and nickel ore, mainly exported from Indonesia, the Philippines and New Caledonia.

Shipping Countries

List Of Accidents

LIQUEFACTION ACCIDENTS (1988 – 2017) BY CARGOES AND SHIPPING COUNTRIES

Bauxite5%

Fluorspar5%

Nickel Ore43%

Iron Ore47%

24%

9%

9%

48%

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Handysize Handymax

General Bulker

Handysize25%

Handymax

General Bulker

Ship Class Loss Tonnage

LIQUEFACTION ACCIDENTS (1988 – 2017) BY CARGOES AND SHIPPING COUNTRIES

LIQUEFACTION ACCIDENTS (1988 – 2017) BY SHIP CLASS AND LOSS TONNAGE

CUMULATIVE LIQUEFACTION ACCIDENTS (1988 – 2017)

The Handy subclass bulk carriers (Handysize and Handymax) are frequently used in this area.The total loss tonnage is over 700 000 tonnes.

The suspected liquefaction incidents on bulk carriers continued to occur at a rate of nearly two per year even after the mandatory implementation of the IMSBC Code (red line). So mandatory TML didn’t stop ships from sinking.

The effectiveness of the test methods used to determine the TML of solid bulk cargoes have come under question just like the follow-up of the rules dictated by the IMSBC code (FMP measurement procedures). The FMP nume-rical value can vary widely even for cargoes with the same description. It is not possible to predict the FMP of a given cargo from its description, particle size distribution or chemical composition.

The FMP therefore needs to be determined by laboratory testing separately for each cargo provided by each ship-per. In cargoes loaded with a moisture content above the FMP, liquefaction may occur unpredictably at any time during the voyage.

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1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

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24%

48%43%

9%

74%

2%

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LIQUEFACTIONPrinciple

COMPACTION LIQUEFACTION

Interstitial air

Shaken

Cargoes that are at risk of liquefaction are those containing at least some fine particles and some moisture, although they are not visibly wet in appearance.

The most widely known cargoes are mineral concentrates (Nickel and Iron), but also coal, pyrites, mill scale, sinter/pellet feed, etc.

Even if they look dry in appearance at the time of loading, these cargoes contain moisture in between the particles. During loading, the cargoes are usually in their solid state.

During ocean transport, the heave and pitch as well as the other 4 motions of the ship agitate cargoes resulting in their compaction. This leads to the removal of interstitial air and a reduction of the spaces between particles. If compaction is such that there is more water inside the cargo than there are spaces between the particles, the water pressure inside the cargo can rise sharply and press the particles apart.

This suddenly reduces the friction between particles. The effect of this process is a transition from a solid state to a viscous fluid state in which all or part of the cargo can flatten out to the removed of interstitial air and form a fluid surface. In this condition, cargo may flow to one side of the ship with a roll one way but not completely return with a roll the other way, progressively leading to a dangerous accident like sudden capsizing of the vessel.

The lowest moisture content at which liquefaction can occur is called the Flow Moisture Point (commonly abbreviated FMP).

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STABLE STABLE UNSTABLE

B: Center of buoyancy of hull, – G : Center of Gravity – M: Metacenter (Point of application of the resultant of the forces exerted on a floating solid body.) – MO: Overturning Moment – MR: Restoring Moment.

For a bulk carrier to list, the vessels overturning moment, MO, must exceed the vessels restoring moment, MR. This unstable condition is depicted in Figure. 1 – Right, where it is shown that the centre of buoyancy of the hull, B, stays inwards of the centre of gravity of the vessel, G. The resulting metacentre, M, under these conditions is below the centre of gravity, and causes the overturning moment, MO, which exceeds the restoring moment, MR. This causes the vessel to develop a permanent list and may possibly capsize if measures are not taken to right the vessel.

There are two occurrences resulting from the liquefaction of cargo that can cause a bulk carrier to list:- If the cargo mass as whole begins to behave as a liquid the resulting free surface effect will reduce the metacentric height, and M will be below G. - If partial liquefaction takes place at a point within the cargo mass resulting in the cargo shifting to one side. In that case the centre of gravity will move and the vessel will have a permanent heel angle.

THE RISKS FOR THE VESSEL

HEAVE

YAW

ROLL

PITCH

SWAY

SURGE

6 DEGREES OF LIBERTY

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FLodri ios

ORE IS LESS COMPACTED, THERE’S STILL INTERSTITIAL AIR BETWEEN PARTICLES

NO RISK OF LOSS OF SHEAR STRENGTH - NO LIQUEFACTION

POLYMER ABSORBS WATER, SWELLS AND REMAINS BETWEEN PARTICLES

MECHANISM WITH POLYMER

Superabsorbant polymer FLODRI IOS

Polymer

Addition

Pore Water Less Pore Water

Less Free Water

Swelling

As the ores physical/chemical characteristics can be different in the same shipping, and as the sampling me-thods are difficult to manage in many locations, you’d need to secure the cargoes.

FLODRI IOS absorbs moisture and keeps it for the required time to transport the cargo safely. FLODRI IOS has been developed by SNF to resist under the chemically hostile environment of metal oxides and to keep moisture absorption capacities at a high level, avoiding any moisture loss, strength loss and thus preventing liquefaction. It is not necessary to mix the whole ore cargo with FLODRI IOS, but only with the lower part of the ore cargo, to absorb the expected volume of water separation.

Tests show that on different ores, FLODRI IOS raises the liquefaction point by 4% to 8%, which is a sufficient safety margin in most cases. Ores treated with FLODRI IOS can be safely shipped over long distances even under heavy weather conditions.

The objective of using FLODRI IOS is to secure a ship’s trip. Since FLODRI IOS removes moisture, regardless of the ore, and remains efficient during a long trip, it is now possible to consider escaping from the sampling requirements by following these steps:

• Optimal dosage of FLODRI IOS at different moisture content to always control the TML (regardless of the ore and the trip)

• Automatic measurement of the ore moisture.• Automatic and continuous dosage of FLODRI IOS in accordance with the moisture measurement during the

ship’s holds loading.

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Flow Table (FT) Penetration Table (PT) Proctor-Fagerberg (PF) & Modified PF

NOTE:

Flow Table test relies a lot on the operator. The operator must visually determine if the sample is above or below the FMP.

The Penetration test and Proctor/Fagerberg test use measurements to determine whether the FMP has been reached and does not need the operator to interpret visually. These tests are repeatable between operators and laboratories if the same procedure is used.

Nevertheless, the procedure Tests, as written in the IMSBC Code, are not a direct measure of liquefaction.

These tests measure the material’s loss of strength, one of the key precursors to liquefaction, but it is not the only one.

TESTING CAPABILITIES

Thanks to our equipment laboratories, we can assist the customers to conduct the following studies:• Measure the impact of the dosage of the FLODRI IOS on the FMP for each nature of ores.• Simulate trips under representative conditions (hexapod)• Recommend an optimal solution based on the nature of ores (Iron, Nickel, etc.) and the characteristics of the transport (itinerary, type of ships)

SuperAbsorbant

LAB EQUIPMENT USED TO MEASURE THE FMP

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HexapodThe hexapod can replicate ship movements under any weather conditions. It can be loaded up to

1000 kg.

With 2 containers representing 1/90th of a Capesize’s hold, we put between 200 to 300 kg of iron ore. The containers are closed, put on the hexapod, and shaken.

HEAVE

YAW

ROLL

SURGE

PITCH

SWAY

SNF has developed its own program to run the hexapod in partnership with the French oceanographic institute IFREMER. We have written 3 different realistic scenarios: calm, choppy and stormy seas as the hexapod can simulate these different weather conditions. The calculated points are based on real sea conditions. The hexapod can run several voyage scenarios, from Canada to China or from Liberia to China for 2 types of ships, Capesize and Supramax.

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All the files can be combined to form a scenario involving different ores, ship size and weather conditions, which can be discussed and validated with customers.

VOYAGE PARAMETERS

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The voyage from CANADA to CHINA lasts 60 days and the one from LIBERIA to CHINA lasts 45 days.The parameters were set for stormy seas during the whole voyage. The boat speed was fast (75% of max). The ship tested was a Supramax (190m / 32.26m), a small bulk carrier.

These parameters were chosen to test the worst case scenario.

RESULTSAt the start of all voyage, a certificate of assay is issued by AHK or Inspectorate and a TML is measured. The graphs below show that with FLODRI IOS, the TML increases by 10%.At the end of the voyage, new certificate of assay is issued by AHK or Inspectorate and a new TML is measured. The TML has not changed during the voyages.

CONCLUSIONSThe TML measured at the start of the voyage and the one measured at the end (after 45 days and 60 days respectively) are in the same range.

FLODRI IOS remained efficient during all the voyages that were simulated.

No liquefaction will occur in the cargo holds.

Treated Iron Ore shows no loss of shear strength, no liquefaction can occur.

COSTSTo prevent liquefaction one alternative solution is to dry the wet ore before loading. The usual method involves a drum mixer and a burner.

OPEXIn order to be safe, 3% to 4% water per tonne of ore needs to be removed.Just for the fuel, the cost will be from $3.6 to $4.8 per tonne of ore.With FLODRI IOS, the dosage range is between 0.050% and 0.1%, the cost per tonne of ore treatedwill be between $ 1.4 and $ 2.8.

ENVIRONMENTOne litre of fuel removes 10 kg of water and will dry one tonne of ore. This will emit 26 kg of CO2 per tonne of ore treated. In comparison, to treat a Capesize vessel, drying the ore will emit 5200 tonnes of CO2.

FLODRI IOS: no burning – no CO2 emissions.

Results

TML with FLODRI IOS on African DSO TML with FLODRI IOS on Canadian DSO

B

G G

B

M R

M

G

B

M O

M

Bauxite4%

Iron Ore54%

Nickel Ore38%

Fluorspar4%

Bauxite7%

Nickel Ore47%

Iron Ore46%

North Korea3%Brazil

7%Australia4%

Malaysia7%

Philippines10%

India28%

Indonesia41%

North Korea5%

Brazil18%

Indonesia49%

India2%

Philippines8%

Malaysia9%

Australia9%

Capesize8%

General Bulker8%

Handysize42%

Handymax42%

Handysize179 000T

16%Capesize398 000T

36%

Handymax529 000T

47%General Bulker15 000T

1%

Handysize30%

Handymax52%

Capesize18%

20

15

10

5

0

16

18

12

14

8

10

4

6

0

2

9.3

13.6

18.3

Natural State FLODRI IOS (0.05%)

FLODRI IOS (0.1%)

TML with FLODRI IOS on african DSO

20

15

10

5

0

7.4

12.6

15.4

Natural State FLODRI IOS (0.05%)

FLODRI IOS (0.1%)

TML with FLODRI IOS on canadian DSO

45 Days

FMP start FMP end

FMP Results African Ore

+4%

+5%

+5%

+3%

B

G G

B

M R

M

G

B

M O

M

Bauxite4%

Iron Ore54%

Nickel Ore38%

Fluorspar4%

Bauxite7%

Nickel Ore47%

Iron Ore46%

North Korea3%Brazil

7%Australia4%

Malaysia7%

Philippines10%

India28%

Indonesia41%

North Korea5%

Brazil18%

Indonesia49%

India2%

Philippines8%

Malaysia9%

Australia9%

Capesize8%

General Bulker8%

Handysize42%

Handymax42%

Handysize179 000T

16%Capesize398 000T

36%

Handymax529 000T

47%General Bulker15 000T

1%

Handysize30%

Handymax52%

Capesize18%

20

15

10

5

0

16

18

12

14

8

10

4

6

0

2

9.3

13.6

18.3

Natural State FLODRI IOS (0.05%)

FLODRI IOS (0.1%)

TML with FLODRI IOS on african DSO

20

15

10

5

0

7.4

12.6

15.4

Natural State FLODRI IOS (0.05%)

FLODRI IOS (0.1%)

TML with FLODRI IOS on canadian DSO

45 Days

FMP start FMP end

FMP Results African Ore

+4%

+5%

+5%

+3%

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CONCLUSIONThe impact of the suspected liquefaction of solid bulk cargoes on human life and industry assets has been significant. It was determined that liquefaction was the suspected cause for 21 incidents reported from 1988 to 2017 which resulted in

214 casualties.

Sadly, the incidents continued to occur after the mandatory implementation of the IMSBC Code in 2011.

SNF offers a solution using superabsorbant polymers.

FLODRI IOS stabilizes wet cargoes for up to 60 days at least, without any loss of properties.FLODRI IOS is used at very low dosages, 0.050% to 0.1%.

FLODRI IOS has no other effect on the ores than a physical removal of water from the pores, the treated ores keep the same chemical and metallurgical properties.

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SNF sasZAC de Milieux

rue Adrienne Bolland42163 Andrézieux Cedex

FRANCE

+ 33 (0)4 77 36 86 00info@snf.frwww.snf.fr

SNF HOLDING Co.PO Box 250

1 Chemical Plant roadRiceboro, Georgia 31323

UNITED-STATES

+1 (912) 884 3366info@snfhc.comwww.snfinc.com

SNF (CHINA) FLOCCULANT Co. Ltd.Taixing economic development zone

West of Tongjiang roadTaixing City Jiangsu Province 225442

CHINA

+86 523 767 6300commercial@snfchina.com

www.snfchina.com

All

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Publ

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SNF

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While SNF makes reasonable efforts to ensure the information is accurate and up-to-date, SNF makes no warranties or representations, express or implied, as to the accuracy, completeness, or any other aspect of the information on this document and assumes no liability in connection with any use of this information. Nothing herein shall be construed as a recommendation or license to use any information found that conflicts with any patent, trademark or copyright of SNF or others, and SNF makes no representations or warranties, express or implied that any use of this information will not infringe any such patent, trademark or copyright.

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