MINE FIRES.pdf

MINE ENVIRONMENTAL ENGINEERING

Department of Mining Engineering

National Institute of Technology, Rourkela

Abhijeet Dutta

711MN1172

Submitted by:

Environmental impacts of mine

fires: Global overview.

Fire Risk Assessment using

software.

Dynamics of mine fire. Studies on pillar fire and their

control.

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CONTENTS

Sl. No. Title Page No.

1. Environmental Impacts of Mine Fires: Global Overview 2

1.1. Emissions From Coal Fires 2

1.2. Impacts 3

1.3. Case Studies 4

2. Fire Risk Assessment Using Software 11

3. Dynamics of Mine Fire 21

3.1. Modes of Mine Fire Propagation 22

A. Controlling Mechanism And Stability 24

B. Conditions For The Development of Fuel-Riches Fires 27

C. Composition of Combustion Products 28

D. Fuel Consumption of Timber Fires 29

E. Extension of Timber Fires 31

F. Velocity of Fire Propagation 31

3.2. Temperatures Developed by Timber Fires 33

A. Heat Generated by Fire 33

B. Heat Flow From Rock to Air 35

3.3. Effects of Mine Fire on Mine Ventilation 37

A. Throttling Effect 37

B. Natural Draft Effect 39

C. Combined Throttling With Natural Draft Effects 41

4. Studies On Pillar Fire And Their Control 44

5. References 51

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1. ENVIRONMENTAL IMPACTS OF MINE FIRES: GLOBAL OVERVIEW:

1.1. Emissions from Coal Fires:

Fig. 1A : Emissions from the Centralia, Penn., underground coal fire; subsidence resulting from

burning and subsequent collapse of coal pillars used as roof supports for mining tunnels under the

town is also evident. Centralia, the largest and best known U.S. coal fire, has been burning since

1962 and has resulted in relocation of nearly all of the towns residents.

Self-ignited, naturally occurring coal fires and fires resulting from human activities persist for

decades in underground coal mines, coal waste piles, and unmined coal beds. These uncontrolled

coal fires occur in all coal-bearing parts of the world (Stracher, 2007) and pose multiple threats to

the global environment because they emit greenhouse gasescarbon dioxide (CO2), and methane

(CH4)as well as mercury (Hg), carbon monoxide (CO), and other toxic substances. The

contribution of coal fires to the global pool of atmospheric CO2 is little known but potentially

significant. For China, the worlds largest coal producer, it is estimated that anywhere between 10

million and 200 million metric tons (Mt) of coal reserves (about 0.5 to 10 percent of production)

is consumed annually by coal fires or made inaccessible owing to fires that hinder mining

operations (Rosema and others, 1999; Voigt and others, 2004). At this proportion of production,

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coal amounts lost to coal fires worldwide would be two to three times that for China. Assuming

this coal has mercury concentrations similar to those in U.S. coals, a preliminary estimate of annual

Hg emissions from coal fires worldwide is comparable in magnitude to the 48 tons of annual Hg

emissions from all U.S. coal-fired power-generating stations combined (U.S. Environmental

Protection Agency, 2002).

In the United States, the combined cost of coal-fire remediation projects, completed, budgeted, or

projected by the U.S. Department of the Interiors Office of Surface Mining Reclamation and

Enforcement (OSM), exceeds $1 billion, with about 90% of that in two StatesPennsylvania and

West Virginia (Office of Surface Mining Enforcement and Reclamation, 2008). Altogether, 15

States have combined cumulative OSM coal-fire project costs exceeding $1 million, with the

greatest overall expense occurring in States where underground coal fires are predominant over

surface fires, reflecting the greater cost of extinguishing underground fires (fig. 2) (see

Controlling Coal Fires).

In this fact sheet we review how coal fires occur, how they can be detected by airborne and remote

surveys, and, most importantly, the impact coal-fire emissions may have on the environment and

human health. In addition, we describe recent efforts by the U.S. Geological Survey (USGS) and

collaborators to measure emissions of CO2, CO, CH4, and Hg, using ground-based portable

detectors, and combining these approaches with airborne thermal imaging and CO2 measurements.

The goal of this research is to develop approaches that can be extrapolated to large fires and to

extrapolate results for individual fires in order to estimate the contribution of coal fires as a

category of global emissions.

1.2. Impacts:

Direct hazards to humans and the environment posed by coal fires include emission of

pollutants, such as CO, CO2, nitrogen oxides, particulate matter, sulfur dioxide, toxic

organic compounds, and potentially toxic trace elements, such as arsenic, Hg, and selenium

(Finkelman, 2004).

Mineral condensates formed from gaseous emissions around vents pose a potential indirect

hazard by leaching metals from mineral-encrusted surfaces into nearby water bodies.

Despite this combination of potential health hazards, few studies have concentrated on the

immediate health impacts of coal fires (Finkelman, 2004).

Some gaseous components from coal fires, such as Hg and CO2, pose a global-scale threat.

In the case of Hg, its addition to the atmosphere is thought to eventually contribute to high

levels of the methyl form of Hg in some fish species, consumption of which is the primary

human exposure pathway for Hg.

In the case of CO2 and other greenhouse gases, emissions contribute to climate change,

but data on these emissions are not sufficient for uncontrolled coal fires to be taken into

account as a source category in current climate model projections.

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Fig. 1B : Coal Seam, Wuda, China

Fig. 1C : A Coal Fire in the Mountains of Colorado

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Fig. 1D : Distribution of Coal Fires Around The World

The problem of spontaneous combustion and uncontrolled burning of coal seams is not limited to

the Chinese and Indian coal fields. It can be encountered throughout the world in most coal-

producing countries. With the worlds largest coal reserves, coal fire in the United States mainly

occurs in Pennsylvania. According to data from the National Abandoned Land Inventory System

of the Pennsylvania Department of Environmental Protection, there are currently 140 underground

coal mine fires and 58 burning refuse piles in Pennsylvania. Scientists estimate that Australias

Burning Mountain, the oldest known coal fire, has burned for 6,000 years.

1.3. CASE STUDIES:

Coal fire in China: China is the largest coal producer and consumer worldwide (See Graph 1.7),

even if it accounts for only 11% of the world's total recoverable coal reserves; China supplies 75%

of its energy with coal. The country presently accounts for 28% of the worlds coal use. Due to

mining of its vast coal fields, fires are spreading. It is only within the last years that the topic of

coal fires growing popularity also within the daily media. This is the result of several bilateral and

multi-lateral research initiatives, e.g. the geoscientific Sino-German Research Initiative on Coal

Fire Research. The overall goal of these projects is firstly to get a better understanding of the

physical-chemical as well as mechanic processes of the fires; secondly, projects aim at the set up

of coal fire monitoring and also warning systems; thirdly, projects aim at the support of Chinese

extinction strategies to save the valuable resource coal. The overall goal is to reduce the greenhouse

gas emissions released. Coal reserves of China are concentrated mainly in the northern part of the

country. The coal mining belt stretches 5000 km from east to west and about 750 km in the north-

south direction. Coal fires are spread in this entire belt. The following map showing the distribution

of coal fires in North China gives an idea of the extent of the problem of coal fires in China.

However, the scientific efforts of coal fire mapping, monitoring, prevention and fighting have been

restricted to a few sites only. The most important of these locations are Ningxia area, Xinjiang area

and Wuda area.

Coal Fires

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Fig. 1E : Map of China showing various mine fires that occurred.

Fig. 1F : Coal Fire in China

Not to Scale

Coal Mine Fires

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The Centralia Coal Mine Fire: The story of the Centralia mine fire began in 1962, when fire

was discovered just outside the borough in an abandoned strip mine used as an illegal garbage

dump (fig. 3.2). After initial fire-fighting efforts failed, the blaze ignited an outcropping of coal

and spread under the town by way of abandoned mine shafts and tunnels. Slowly but inexorably,

about one-third of Centralia was directly affected by fires, an area locally known as the "impact

zone."

Despite the prominence of coal companies in the town's past, the fire was not due to corporate

malfeasance, because there was no active mining where the fire started. Moreover, while coal

companies generally kept ownership of subsurface mineral rights throughout the anthracite

region, Centralia was an exception - the borough had acquired these rights early in the twentieth

century. Therefore, the responsibility for extinguishing or containing the fire fell to various

branches of government.

Between 1962 and 1980, a number of engineering projects were undertaken in an attempt to deal

with the fire, but all attempts failed. Thereafter, some people began to express concern about the

fire's potential health and safety effects. In 1969, three families were evacuated from their homes

owing to the presence of poisonous gases. In 1976, supralethal concentrations of carbon

monoxide were found pouring from a borehole within 27 feet of another Centralia home. Three

years later, a service station was ordered to close because of rising gasoline temperatures in its

underground storage tanks. Then, in 1970, the federal government purchased seven properties

considered to be unsafe; others followed. More and more residents complained of physical

illnesses that they attributed to the fire. Some, however, regarded such complaints as

overreaction.

Origin of the Centralia Mine Fire: Indeed, the community was divided over the seriousness of the

fire. Some residents, mostly in the "impact zone," viewed it as a dangerous and imminent threat

that necessitated strong and swift action to protect residents. These people were also more likely

to have children living at home and less likely to have lived in Centralia all their lives. Others,

while feeling threatened, saw the fire as a distant hazard. Still others believed there was "no

problem," that people were becoming concerned without good reason. According to such a view,

coal-related hazards and disasters add an important element to local culture (Wallace 1981). The

"disaster subculture" of the region integrated the mine fire into a normative response: people might

not like it, but they would have to bear it! Moreover, many of those who had lived in Centralia for

all or most of their lives felt a very strong attachment to their homes and land, making them

reluctant even to consider the possibility of relocation due to hazard.

These different interpretations nourished a conflict that was just barely contained within the normal

political system. The way was prepared for emergence of insurgent grass-roots groups on different

sides of the issue. All that was needed was a dramatic event to illustrate that existing political

institutions were unable to prevent a real calamity. That event took place on 12 February 1981,

when a 12-year-old boy noticed a hole opening in the ground. As he approached it, the void

widened and he fell in. Fortunately, the boy was able to hold onto a tree root until pulled to safety

by a cousin. Confidence in the local political system had been dealt a grievous blow; it eroded

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away completely a few weeks later when an elderly man narrowly avoided death after being

overcome by carbon monoxide in his home.

These two near-death incidents spurred a portion of the community to organize Concerned Citizens

against the Centralia Mine Fire. The Concerned Citizens were convinced that the fire posed a real

and imminent danger to people who lived in the impact zone. By means of letter-writing

campaigns, trips to the state and national capitols, and various marches and demonstrations, the

Concerned Citizens urged government leaders to do whatever was necessary to protect residents

from the fire, even if that meant relocation.

Concerned Citizens immediately sought and received the assistance of national environmental

interest groups, including Rural American Women. From such organizations they learned the

techniques of direct political action. Centralia was featured in reports by national news media and

government officials began to take greater notice of its plight. But the confrontational tactics of

Concerned Citizens did not meet with the approval of many fellow citizens in Centralia. The latter

believed that publicity was a ploy to force the government to buy homes and relocate their

occupants. To these people, the spectre of relocation was more frightening than the fire, because

it portended destruction of the community they loved more surely than an uncertain fire.

The outcome of these differences was a two-year period of intense intracommunity conflict. Town

meetings ended in shouting or fist fights. Telephone threats were made, car tyres slashed, and at

least one fire-bombing occurred. Many neighbours - and even some family members - no longer

spoke to one another. The atmosphere of the period was graphically recounted by one resident:

The breakdown of communality in Centralia illustrates an important point. Direct action may be

helpful in moving a larger political system to act on the grievances of a particular community. At

the same time, it may be extremely divisive within the community, sapping some of the strength

that would be available for a response to the problem that threatens. Time and again,

representatives of the state and federal governments asked Centralians to come to some kind of

agreement about what they wanted the government to do. That consensus never developed:

government agencies and leaders were left to deal with several factions, each with its own proposed

solutions to the problem. Finally, in July 1983, a government-financed engineering study

concluded that the fire was much worse than anyone had thought. Then burning under about 200

acres of land, it had the potential to spread under 3,700 acres, including all of the borough of

Centralia. Swiftly, the US Congress passed a bill that authorized US$42 million to pay for the

voluntary relocation of residents and businesses. This action opened a wider split in the

community. On one side, a grassroots Homeowners' Association formed to help residents get a fair

settlement price from the government. But an opposing group, the Citizens to Save Our Borough,

also formed, with the objective of keeping Centralia a viable corporate community.

Voluntary relocation began in early 1984 amid an atmosphere of tense coexistence between the

contending groups. It also took place out of the spotlight of the mass media because neither group

actively sought to attract their attention. Most Centralians who chose relocation were pleased with

their financial settlements. As agreements were reached with government agencies, families

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moved, mainly to other communities within the region, near where friends and relatives lived. One

by one the vacated homes were boarded up and then demolished. Grass and trees were planted on

the empty building lots but they became expensive to maintain and were eventually replaced by

wild flowers. Each year during the late spring and summer, Centralia displayed a tranquil and

colourful mantle that belied the fire below. Meanwhile, nothing further was done about the mine

fire itself.

By 1991, all who wanted to relocate had gone, leaving 58 people who wished to remain. Many of

those had been active in Citizens to Save the Borough and had now become leaders of Centralia's

normal political structure. In their new role they sought to maintain Centralia's viability despite

the handicaps of a tiny population, virtually no local tax revenue, and diminished social services.

At least now they could act with the full backing of their community, for those who remained in

Centralia shared both a common experience and a common outlook on the future. They would stay

and accept the consequences!

In early 1992, however, their efforts received a severe setback when state agencies ordered the

remaining citizens to depart. Residents were given one final opportunity to participate in the long-

standing relocation plan, with the alternative of having their property seized by the government

under its power of eminent domain. At the time of writing, Centralia's remaining citizens are

engaged in a legal battle to prevent the state-mandated extinction of their depleted town.

The Centralia case presents an instructive example of social devastation wrought by a chronic

technological disaster (Couch and Kroll-Smith 1985). In this case, different interpretations of the

environmental threat led to severe intracommunity conflict and fragmentation. As a consequence,

the social community died long before most of the physical community of Centralia was relocated.

The experience of many modern industrial disasters is one of "surprise." Here the victims were not

surprised by the mine fire; they were astonished by the unsympathetic, hostile, and divisive

reactions of their neighbours. This was the unprecedented aspect of their disaster. About the only

thing most Centralians agree upon is that they have received a "dirty deal" from the government

that was supposed to protect them; this heightened their alienation and diminished their ability to

cope with the problems facing them (Couch and Kroll-Smith 1991).

Definitional Stages Outcomes Political Stages

Pre-Event

No Problem

Warning

Threat

Impact

Relocation and/or

Techfix

Pre-Issue

Non-Issue

Contained Issue

Public Issue

Political Issue

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Centralia provides an example of a failed "techfix" that was followed by relocation. After trying

to implement a "techfix" for nearly two decades, the government relocated most of the population

but allowed those who defined the situation as "not dangerous" to remain. In the end, however, the

government decided that a "techfix" to protect the remaining residents was not practical or

financially feasible and it attempted to force relocation of the remaining residents.

In this regard it is interesting to contrast Centralia with Love Canal. The latter contamination case

in New York State provided an example of relocation first, followed by a "techfix." Residents

living near that toxic waste disposal site were first relocated, then remediation efforts got under

way. Finally, most of the affected area was officially declared safe for habitation. Subsequently,

some new residents moved into the neighbourhood. But many others disagreed with the

government's contention that Love Canal was safe, and controversy continues over the adequacy

of the "techfix".

In light of the history of Centralia and other contaminated communities it is clear that - unlike

places affected by natural disasters such communities rarely experience "amplified rebound"

(disproportionately fast and altruistic recovery) after the event (Fritz 1961). In fact. even the

concept of "recovery" is problematical. Recovery implies the regaining of something that was lost.

At least on the community level, this seldom happens with industrial contamination. Social change

is just too great, to talk of recovery in this sense. What happens is more akin to a transformation -

a major change to something new, not a return to what had been. After a contamination disaster,

people come to hold a very different view of the world, their community, and the roles played by

various social institutions. New cultural norms develop that help people deal with the ongoing

uncertainty that attends the breakdown of their physical and social environments. New community

power structures are born and may become institutionalized. In some cases, such as Minamata,

communities survive but in radically altered states. And in some cases, like Centralia, communities

die.

Coal Mine Fire in Morwell [Monday, September 1, 2014;ABC News]: In February this year the

Hazelwood coal mine fire caused havoc in the community of Morwell south east of Melbourne.

Seven months on many Morwell residents say they're still waiting for their health concerns to be

addressed. The Hazelwood coal mine fire affected the town of Morwell in Gippsland, south east

of Melbourne for 45 days earlier this year. The blaze cloaked the town in toxic smoke and ash,

sparking major health concerns and calls for an evacuation. Community group Voices of The

Valley says there's been no recognition of the adverse health effects caused by the fire seven

months down the track. Then there's the ongoing financial damage caused by the fire to individuals

and businesses. They lost a lot of money, some of them may have closed their doors and then

you've got the personal people where either their health was affected or they actually had to fork

out money to either leave home, stay home and take extra precautions or whatever they needed at

that particular time. An independent inquiry led by former Supreme Court Justice Bernard Teague

heard evidence from community members, fire fighters and the mine operation GDF Suez. They

haven't even faced cleaning up their homes yet. One because they haven't been able to afford to,

they may have insurance but they can't afford the excess and they're scared that they're going to

pay extra money next year, the year after if they actually use their insurance - which is a shame

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because that what insurance is for. People with illnesses, elderly being uprooted and having to be,

to move home because of the effects of the fire and also, the degree to which they were kept in the

dark for quite a period of time as the fires were unfolding.

2. FIRE RISK ASSESSMENT USING SOFTWARE:

A dynamic comprehensive fire risk assessment and risk analysis software named FIRE is available

as a freeware and can be downloaded from the following link:

http://www.onsafelines.com/fire-home-page.html#.VAt-ZsJdXz4

Fig. 2A : Fire Risk Assessment Software, FIRE, Designed and developed by Brian G. Welch

FIRE is a comprehensive fire premises risk management and risk analysis program, designed to

be used by both the safety professional and those with part time safety responsibilities. FIRE as a

risk assessment tool has a primary objective to reduce the overall risk to employees and employers

by making fire premises risk management simpler, less bureaucratic and more efficient. FIRE as

a fire premises risk assessment management software program provides guidance for the safety

professional and risk assessors from the initial risk assessment planning stage, through to advice

on undertaking the risk assessment, documenting the findings and producing reports.

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FIRE stands for First Aid Risk Assessment Managements and is a comprehensive risk management

and analysis program, designed to be used by both the safety professional and those with part time

safety responsibilities.

FIRE provides guidance for the safety professional and risk assessors from the initial risk

assessment planning stage, through to advice on undertaking the risk assessment, documenting the

findings and producing reports.

FIRE allows organizations to manage their risk assessments efficiently and effectively by easily

guiding the assessor through the whole risk assessment process and then keeping track of who,

where, when, and what has been achieved as well as actions and recommendation still outstanding.

FIRE allows instant access to performance and tracking information. All risk assessments can be

quickly and easily located and where necessary printed in a professionally designed and standard

format. The risk assessment input screens are logically laid out and then allow all the right

questions to be asked and recorded. The questions are preset; however hopefully they are the right

questions. The program also allows the user to create two pages of their own questions. Once you

input your risk assessment the program allows you to print the assessment in a professional looking

report. Each assessment type has the facility to record not only the assessment findings but also

any risk assessment briefing required for that specific risk assessment as well as how and when

individuals were briefed. The program also allows for tracking of remedial action by who, where,

when, etc. The reports also have a section for statistical data on risk assessment performance and

outstanding actions.

Additional Features

Build your own question sets. Users can now create addendum A & B pages for their risk

assessments which allow up to an additional 12 user defined questions to be added.

Replicate Risk Assessment - Allows for standard / template risk assessments to be created

and then instantly replicated and amended to suit different circumstances.

Spell check on all memo fields - ability to build own specialised words dictionary.

Zoombox to support text input to memo fields.

Read-write or Read-only login - Allows risk assessments to be display on terminals without

the risk of unauthorised amendments.

Allow reports to be exported to either Pdf or Xps formats.

FIRE covers the following elements of a Fire Premises Risk Assessment:

Sources of Ignition

Sources of Combustible Materials

Consideration to those at Risk

The Building Occupants

Policy, Procedures and Instructions (which may be in place)

Fire Precautions Management (which may be in place)

Means of Escape

Training

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Maintenance of existing systems

FIRE as a risk assessment software program allows organisations to manage their risk assessments

efficiently and effectively by easily guiding the assessor through the whole fire premises risk

assessment process and then keeping track of who, where, when, and what has been achieved as

well as actions and recommendations still outstanding. FIRE allows instant access to performance

and tracking information. All fire premises risk assessment management software can be quickly

and easily located and where necessary, printed in a professionally designed and standard format.

FIRE is a "One Stop Shop" risk assessment program and as such is one of the most useful risk

assessment and risk management tools on the market. It will cover almost all of your companys

fire risk assessment requirements within one program. Pound for pound FIRE is probably the best

value risk management software you can buy. We are so convinced you will agree we have

provided a fully functional demo-version.

System Requirements

Supported Operating Systems: Windows Vista, Windows XP Service Pack 2 (plus

Windows 7 32 & 64 bit) and Win 8.

Computer: Any windows computer that runs one of the above operating systems at a

reasonable speed, graphic adapter minimum resolution higher than 800 x 600 and 16-bit

High colour.

Inputting First Data

It is recommended that the following tables be part or fully populated prior to entering your first

risk assessment. This will make entering the assessment easier.

1. Companies 2. Locations 3. Company Structure i.e. Department / Teams etc 4. Employee / Staff details

However, although recommended it is not essential that this information is entered immediately,

as a clever feature of FIRE is that it has been designed to accept data inputting on-the-fly an as

such if the company, location, team, employee, etc., can be entered from the record input screen

by simply double clicking on the appropriate drop-down list. Names, etc., once entered into the

drop down box becomes available next time around automatically, this will be a real time saver.

Note: This will be the only time you need to enter details listed below. FIRE will use the

information entered here throughout the entire application. This allows for efficiency of

operation and accuracy of data. All changes made to this table will be cascaded to all related

records, allowing for one-time edit and updates.

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Company Table

The first data users should add is their company or their client's company into the company

table. You may use FIRE to record risk assessments for different companies, and clearly health

and safety consultancies will need to build-up a list of their clients. FIRE does not restrict on the

number of companies you may wish to record risk assessments against. However, data printed on

the headers and footers from the risk assessments and statistical reports available from FIRE will

only bear the companies' details of the license holder. The companies table is available via the

Company Structure ribbon button. Then simply add the company names into the companies table,

FIRE will automatically generate a unique ID reference number.

Locations Table: Next users should add is the various locations for their company(s) or their clients

company(s) into the locations table. The locations table is available via the Company Structure

ribbon button. Simply add the various location for your company or clients set-up into the

locations table, FIRE will automatically generate a unique ID reference number.

Risk Rating is calculated by multiplying the likelihood against the severity, e.g. taking a likelihood

of 4, which is classified as Probable, and multiplying this against a severity of 2, which is classified

as a Minor Injury 1st aid required, would give you an overall risk rating of 8, which would be risk

rated as a low risk. A high risk, but minor effect may appear to need less in terms of risk

management than a low risk, with serious, irreversible, effect. However, it may need more

attention, particularly if it is likely that more people will be affected. High hazard does not equate

to high risk!

Fig. 2B : Risk Matrix in software

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Fire Risk Assessment

The chances of fire starting will be low if there are few ignition sources and if combustible

materials are kept away from them. In general fire is likely to start in one of the following ways:

Accidentally, such as when smoking materials are not properly extinguished.

By act or omission, such as when electrical equipment is not properly maintained or when refuse is allowed to accumulate near to a heat source.

Deliberately, such as intentional setting fire to external storage or rubbish bins.

Premises should be critically examined to identify any potential accidents, any acts or omissions that might allow a fire to start and to evaluate risk. This should include situations

that may present an opportunity for deliberate ignition. Having also considered the people

likely to be at risk and the likelihood of fire occurring, it is important to make an assessment

of the adequacy of existing fire safety measures and the need for additional measures.

The risks caused by flammable materials and substances in the workplace can be reduced

in various ways:-

By removing or eliminating them from the workplace or reducing their quantities to the absolute minimum required.

By replacing them with non-flammable or less flammable alternatives. By ensuring that they are handled, transported, stored and used safely. By ensuring that different kinds of flammable materials and substances are

adequately separated.

The fire precaution strategies will cover such areas as:

Means of escape. Keeping the premises free from obstruction and clear of combustible refuse. Opening doors and barriers in case of fire. Marking of exits and provision of adequate lighting. Means for fighting fire. Provision for the fire brigade to be called in the event of fire in the premises and

for facilitating firefighting by the fire brigade.

Means for detecting fire and for giving warning in case of fire. Fire-resisting construction and materials for use in internal walls and ceilings. Instruction and training. Preparation of emergency plans. Prevention of smoking. Supervision of construction and maintenance contractors. Hot working permits. Records to be maintained

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Fire Risk Assessment Input Forms:

FIRE has been designed to be modular, in this we mean if you learn how to input records into the

Fire module the principles are appropriately the same for all the other risk assessment types

covered by the application. This will greatly increase the speed at which new user can become

accustomed to and prolific in managing their risk assessment responsibilities via FIRE.

Header Tab:

Fire Reference No: Unique identification allocated to the risk assessment (duplicate Ref IDs are

not permitted)

Location / Site: Identifies where the Fire risk assessment applies to.

Premises Being Assessed: Records details of premises being fire risk assessed.

Assessor One and Two: Records the details of the any individuals assisting in the risk assessment

process, typically the employees with fire duty responsibilities etc. this will vary from company

to company.

Date: Fire assessment undertaken on.

Time: Fire assessment undertaken at,

Review Date: Date the Fire risk assessment should be reviewed for accuracy and continuing

suitability.

Review Not Required: Prevents the program from placing the Fire assessment on the overdue

remainder report after its review date is past. Typically used where companies are leasing,

renting or unlikely to be in the same premises next time the review is due.

Navigation Bar: Provides the following ways to navigate through records:

First Record

Previous Record

Number of Record within Record-set

Next Record

Last Record

Filter Box

Search Box

Duplicate Record: Will replicate an exact copy of the Fire risk assessment and allocate a unique

and temporary reference ID.

The tabs across the Fire input form are split into logical groups of questions that would be asked

during a Fire Risk Assessment. The layout my change slightly from tab to tab but the principal

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is then same throughout. Questions on the left, followed by a yes / no / na and blank response

and any relevant comments. Some questions may have check box yes / no responses only, the

reason will be evident in such cases.

Tip: When in the yes / no / na field the response can be toggle between the 3 possible answers by

a) Double clicking the mouse whilst hovering over the field,

b) Pressing the space-bar whilst the field has the focus i.e is highlighted yellow.

Header Page Button: Quickly return you to the header details page from any tab

Jump to Actions Button: Quickly takes you to the actions tab for entering any concerns found

during the Fire risk assessment.

Back to Previous Button: Quickly returns you back to the tab you were working in when you

clicked on the Jump to Actions Button. This allows user to quickly flick between the findings

page and the actions tab for easily entering concerns without losing their place within the Fire

input form.

Data entered into any fields in the Fire assessment input pages is replicated into a professionally

designed Fire risk assessment report.

The Fire risk assessment asks question to covers the following areas;

Fire Sources

Those at Risk

Policy and Procedures

Fire Precautions

Means of Escape

Training

Maintenance

General Risk Assessments (task based)

Task based risk assessment is a method for systematically examining a job to identify hazards,

evaluate the risks and specify appropriate safeguards. Task based risk assessments are normally a

team based exercise whereby employees familiar with the task assist the assessor in producing the

document risk assessment. Involving employees and safety representatives in the risk assessment

process is a highly effective way of identifying hazards and developing solutions that work.

Risk assessments demonstrate that due regard for employees health and safety at work have been

given appropriate consideration. The risk assessment process requires either acceptance of a

satisfactory level of risk, or actions to control and reduce risk further.

mk:@MSITStore:D:/Program%20Files/On%20Safe%20Lines%20QHSE%20Software/Fire%20Premises%20Risk%20Assessment%20Management/FIRE.chm::/IDH_Topic10_8.htm

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So the first step is to identify the task that you need to identify is we need to establish what is

actually done. This may seem self-evident. However, experience indicates that this is not always

as easy as many infer. Observation and scrutiny may reveal that workers complete a task in entirely

a different method than is indicated from the working procedures, purely because they have found

that their own approach works best, requires less exertion or is faster. Alternatively, it may be that

they have found ways to negate with a specific problem or event that has not been formally

identified and assessed.

So you need to visit the work location and view the task to determine what really takes place. Note

that you will often need to observe the whole task, since merely watching part you may miss

important events that could be significant to your risk assessment findings. You will also need to

ask questions to ensure that you are aware of events or factors not apparent at the time which,

however, may also influence the risk assessment findings. Questions such as: Does it ever get at

clogged or "How do you clear excess material? can reveal aspects of possible exposures or

injuries that you might otherwise not identify.

A risk assessment is not necessarily something precise, since it deals with uncertainty, namely the

possibility of an event occurring that could result in a worker being exposed to possible damage

to health. A further uncertainty is the estimation of the assessor as to whether such exposure could

result in damage to health and the significance of such damage

Duplicate Risk Assessment

FIRE offers users the facility to replicate entire risk assessments.

The facility to be able to replicate an entire risk assessment will allow assessors to duplicate similar

risk assessment activities and then make minor changes as necessary. This makes FIRE an

extremely efficient application for those with health and safety responsibilities to have in their

toolbox.

Replicating a risk assessment is as simple as clicking on the duplicate button on the risk assessment

input form.

Assessors can create template risk assessments, which hold all the core assessment details and then

use the duplicate button to quickly and efficiently create a new risk assessment which will be part

populated.

The newly created risk assessment will be given a temporary Ref ID number. The user then has

the option to re-number the assessment to match their own numbering convention or leave as is.

COMPUTER SIMULATION OF EFFECTS OF MINE FIRE:

For the design of fire escape plans and for the layout of fire detection systems, the following points

are essential:

1. The paths through which the combustion products of a potential fire will flow.

mk:@MSITStore:D:/Program%20Files/On%20Safe%20Lines%20QHSE%20Software/Fire%20Premises%20Risk%20Assessment%20Management/FIRE.chm::/quantitative_assessments.htmmk:@MSITStore:D:/Program%20Files/On%20Safe%20Lines%20QHSE%20Software/Fire%20Premises%20Risk%20Assessment%20Management/FIRE.chm::/quantitative_assessments.htm#Risk_Rating

19

2. The concentration of gases at the steady-state conditions.

3. The times at which the combustion products will reach the different parts of a mine.

4. The transient concentration of gases.

The computations procedure accounts for airway resistances, interaction of fans and thermal

exchange with the airway walls. The buoyancy-induced natural ventilation is calculated directly

from the airway temperatures, which change in a quasi-steady state manner owing to thermal

diffusion into the airway walls. The fire is quantified by its heat production in determining the

effects of natural ventilation.

The mine ventilation program is used to simulate the airflow in a multilevel mine network by

designing each junction (crosscut and intersection) and branch (airway) with an identification

number. Internally, the program forms closed paths (meshes) throughout mass is applied to each

junction. The program develops solutions to the airflow rates and temperatures throughout the

mine. When one or more fires are simulated, the program calculates the smoke concentration in

each airway in the steady-state mode based upon an airflow rate computed for a fixed time after

the inception of the fire. These airflow rates are further utilized to calculate the smoke spread

throughout the mine network under the condition of one or more fires of various durations.

PROGRAM LOGIC:

Thee computation procedure consists of dividing the mine atmosphere into control volumes

of homogeneous concentrations that advance with flow throughout the ventilation network.

When control volumes meet at junctions, new control volumes are generated. Waves

represent the boundary between control volumes.

The core part of the program is designed in the form of a triple-nested DO-loop. All three

loops start at the beginning of the program.

The outer DO-loop, ending with the last program statement, controls the simulation-time

IDUR and provides output at the end of every time interval INC.

An intermediate loop updates the state of ventilation system MULT times in time

increments XINT until another INC is completed.

The innermost loop updates the condition of each airway in increments XINT.

The real-time computational feature of the computer program enables the user to reorganize the

following:

1. Airways that have subcritical byproduct-of-compositional concentrations for a period of

time adequate for rescue measures before reaching a critical level concentration.

2. Airways that remain subcritical for long times. The word critical is applied to those

airways that are unsafe for human occupancy.

The output of the program presents in ascending order those airways that have contaminated air

by highest wave number for the airway, the gaseous concentration (percent volume) of the

contaminated air behind the front of the wave and the starting time for the wave.

20

Fig. 2C : Flow chart of real time concentration programs with modification for miners; exposures

(JF, end junction of airways). (From Greuer, R.E., Proc. 3rd Int. Mine Ventilation Congr.,Howes,

M.J.. and Jones, M.J., Eds., Institute Mining and Metallurgy, London, 1984, 407)

21

3. DYNAMICS OF MINE FIRE:

A computational fluid dynamics (CFD) program can be applied to fire spread along combustibles

in a ventilated mine entry. The rate of flame spread was evaluated for the ribs and roof of a coal

mine entry; timber sets; and a conveyor belt. The CFD program models char forming materials

with temperature dependent thermal properties. The program solves three dimensional time

dependent flow equations with a mixture fraction model for the gas phase reactions. Radiant heat

exchange is evaluated for non-scattering gas.

Fires in a mine create a hazardous environment for mine personnel due to toxic gas and low

visibility. The primary toxic gas emission is carbon monoxide (CO). Fire spread expands the

emissions source. Important for controlling the spread of a fire over combustible surfaces is an

understanding of how rapidly the fire will spread. Fire spread in a coal mine will depend upon the

thermal and physical properties of the material, the imposed ventilation, and the entry dimensions.

Coal mine solid combustibles include coal, conveyor belts, and wood supports which can undergo

the complex process of char formation. These fuels, because of their physical distribution, can

result in fire spread over considerable distances in a coal mine. Liquid combustibles, such as diesel

fuels and transformer fluids, will generally be limited to a localized region, although their

combustion products can be transported by ventilation for extensive distances. Past research [1]

on fire spread has generally been limited to one dimensional ignition models which do not consider

the char formation process within the solid, and the buoyancy generated flow. With high speed

computational capability, it is possible to model fire spread in a mine entry with particular attention

to the entry dimensions, air ventilation velocity, fuel combustion properties, and char formation

process. From this capability relationships between fire spread velocity and ventilation for a

particular mine entry configuration can be developed. This information can be used to develop

measures to control fire spread and to project CO and smoke emissions and their transport through

the mine ventilation network.

22

3.1. Modes of Mine Fire Propagation:

(Sengupta, M. et. al., Mine Environmental Engineering, Volume 2, Page No. 145)

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3.2.

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3.3.

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Case Study:

Dynamics of coal fire in Jharia Coalfield, Jharkhand, India during the 1990s as observed

from space:

Jharia Coalfield in Jharkhand, India, is known for being the exclusive storehouse of prime coking

coal in the country. The coalfield is also known for hosting the maximum number of known coal

fires among all coalfields in India. In the present investigation, an attempt was made to study the

coal fire dynamics of Jharia Coalfield during the 1990s from medium resolution satellite thermal

IR data such as Landsat-5 TM and Landsat-7 ETM+ data (acquired in 10.412.5 mm spectral

region). The dynamics of coal fire was addressed on the two following aspects:

(i) Changes in the spatial extent of fire-affected areas

(ii) Propagation of coal fire during the 1990s.

A marked decrease in the spatial extent of fire-affected areas during the 1990s was observed in

this study. The spatial coverage of surface and subsurface coal fires was found to change from

0.42 and 2.06 km2 respectively, in 1992, to 0.33 and 1.36 km2 respectively, in 1996 and 0.08 and

1.60 km2 respectively, in 2001. Using the three available satellite thermal datasets acquired in

1992, 1996 and 2001, an attempt was made to find the net lateral propagation during 199296 and

19962001. The propagation of coal fire was found to be more erratic than regular in nature.

During 199296, the net lateral propagation was in general towards south and at places towards

west, whereas during 19962001 it was in general towards north.

Decrease in the spatial extent of coal fire might have occurred due to several reasons as described

below.

(i) Various reclamation measures were adopted by Bharat Coking Coal Limited (BCCL), Dhanbad

for arresting coal fire and restricting the propagation of fire:

(a) Removal of fire-affected coal seams, particularly the fire-affected portions of the affected coal

seams from the unaffected coal seams by selective opencast mining operations.

(b) Dumping of the fire-affected portions of the affected coal seams and overburden dumps at a

safe place to let them burn out naturally and completely.

(c) Surface blanketing by incombustible materials, e.g. fly-ash, soil and sand followed by dozing,

compaction and dense plantation. Over 22 million cubic metre of surface blanketing work has been

carried out so far by BCCL for combating coal fire.

(d) Quenching coal fire by water-pooling of fire-affected opencast quarries to extinguish/alleviate

fire from the affected portions.

(e) Isolation of fire by trenching around the fire-affected coal seams.

(f) Isolation of fire by construction of sand/cement grout cut-off barriers.

(g) Hydraulic stowing/blind flushing through boreholes. More than 50 million cubic metre of sand

has been stowed below ground.

43

(h) Infusion of inert gas. Over 3 million cubic metre of nitrogen gas has been flushed below the

ground to control fires.

(ii) Besides, in many of the age-old coal fires, coal or coaliferous hydrocarbon matter required for

burning might have been exhausted due to continuous and uncontrolled burning over a period of

time

Fig. 3A : Subsided seam fire (a and c) and debris fire (b and d) at Rajapur, near Jharia town.

Photographs (a) and (b) were taken in 1992 whereas photographs (c) and (d) were taken in 2005

from the same sites but different spots. Photographs are representative of the scenario.

(a) (b

)

(a)

(d)

)

(a)

(c)

)

(a)

44

4. STUDIES ON PILLAR FIRE AND THEIR CONTROL:

Introduction:

Pillar fires are quite common in most of the coal producing countries- which call for special

attention and modus operandi to deal with it. Such pillar-heating-mostly from endogenous origin-

could occur in working areas or, in old workings. They could be quite frequent for room and pillar

or, bord and pillar workings, for both during development stage or, depillaring operation.

The volume of ventilating air flowing past affected pillar in main or, in sub main entry, may dilute

the combustion products to an extent as to miss its detection at an early stage of heating. Thus,

there are instances that a patch of concealed heating may ultimately culminate to such an extent as

to compel sealing of a large area of the mine.

This calls for a closer look at this problem for developing a guideline as regards the following

points, viz.

Cause / Origin of pillar fire for identification of the vulnerable pillars.

Early detection system.

Control measures for immediate implementation as well as long term methods for

preventing future flare up.

Consolidation of the pillar.

Detailed treatment of the above, have been made along with case studies.

Identification of the Vulnerable Pillars

Pillars of the highly succeptible coal seams, particularly with crushed surfaces or fractured cleats

and/or having geological disturbances/having ball coal or line of slip-are all vulnerable to

endogenous heating for obvious reasons. In fact, that is why incidences of pillar fires are observed

to be quite frequent in higly succeptible coal seams of Ranigunj measure, India ( Shamla seam,

Kajora seam etc.) or in D-seam of Colorado Westmore Coal Co., USA and such other places. All

such vulnerable coal pillars, particularly having high ventilation pressure differential between its

intake and return sides, should be closely monitored for any signs of heating. The focus of heating

is usually observed to originate at a shallow depth, 1.5 3.0 m, from the surface-depending on the

scope of air leakages within the coal massive. The heating would however extend towards the air

entry points, if it remains undetected or, unattended.

Early Detection of Fire

The detection system includes, like all other mine fire detection techniques-compositional analysis

of the environment surrounding the pillars (CO/O2 deficiency %, CO/CO2 ratio and other fire

indices) as well as the surface temperature profile studies using infra-red temperature measuring

devices, for any indication of a heated patch. But in view of the possibility of missing the CO

evolution etc. results-being too small to detect in general body samples (at least in the initial stage

of heating), brattice curtain may be hung from roof to floor all around the concerned pillar(s) rib.

45

Monitoring of the curtained off zone is thereafter made, for early detection of heating for necessary

measures.

A typical case study developing the above approach is shown below:

Case Study:

A USBM study was made in three fire prone pillars of D-seam in Colorado Westmore Co.- having

vertical cleats with enough space of air leakages within (Timco et al., 1991). The three pillars with

their dimensions and intake as well as return galleries in the two sides of the pillar C being on the

intake side, had no measurable pressure difference across the faces. But pillars A and B located

between return (exhaust type ventilation system) and intake (belt entry side) did have a pressure

differential 0.7 in w.g. (175 pa)-as measured using magnehelic pressure gauge in the cross cut.

Hot patches could be identified at the pillar surface, using Hughes Probeya Infra-red Camera. In

order to get closer monitoring results, thermo-couples were installed within the small diameter

bore holes drilled through the pillars A, B and C, reaching at various depths.

Any temperature rise is expected to be accompanied with evolution of CO in the same location.

Hence, small diameter copper sampling pipes were also fitted within the bore holes for necessary

monitoring of CO evolution if any (bore hole mouths kept plugged when not in use).

Fig. 4A : View of the three pillars evaluated (Timco, et al. 1991)

The general body sample within the air lock between pillars A and B were found to get stabilized

at 26 ppm CO level. In order to enable pillar emission sampling prior to the gas getting diluted

with mine ventilating air stream-brattice curtains were hung all around the pillar A (considered

most vulnerable from ventilation studies) from roof to floor, at a distance of 1 m from the pillar

wall. CO sensors were then placed between the pillar rib and isolation curtained off, as shown in

46

fig.2. Trend of CO values were then monitored from curtained off zone as well as in cavities in the

bore holes kept plugged. CO values thus measured show as high as 200 ppm at places.

The above is a typical case study which can be a guide line for monitoring pillar fires-both for its

early detection and identification of hot patches, as well as assessment of status of heating.

The methodology thus developed include-

Surface temperature profile studies all around vulnerable pillars with the help of infra-red

temperature measuring devices.

Temperature measurement within the coal massive (inner core) drilling bore holes at

various depths, depending on the fire situation and nature of fissures/cleats.

Recording of CO values in ppm level, if any, in the general body samples around the pillars.

Studies of the trend of fire indices from compositional analysis of the bore hole samples,

as well as the ascertaining the status of fire.

In most of these cases the fire was shallow, to a depth of 1.5 to 3 m within the pillar wall.

Ventilation pressure difference across the affected pillars were observed to be around 35-38 w.g.

After loading out the fire, the above pressure difference was much reduced by proper

reorganization of ventilation. Sodium silicate infusion in the crushed pillars proved to be effective

in many cases for reducing their spontaneous heating risk (Kanjilal, K.K. et. al.,1968).

Though most of the pillar fires can be dealt with by ddigging out and colling-cum-water slurry

infusion within, but there are instances in Ranigunj field in India itself, where pillar fores

ultimately led to closure of the entire mine (may be because of the faulty combat measures or being

detected too late) as shown in Table 1.

Sl.

No.

Name of the Colliery Date of occurrence

of fire

Methodology used for

controlling

1. South Samla Colliery, Samla Seam 12/06/90 Water Infusion Alone

2. North Searsol Colliery, Kenda Seam 01/10/90 Water Infusion Alone

3. Haripra Colliery, Chora eam, 1st and 20th

level

06/08/92 Water Infusion Alone

4. South Samla Colliery, Samla Seam, Pillars at

7 and 8 deep off 7th level

16/02/95 Water infusion-cum-

digging out with subsequent

cement injection/protective

coating

5. Girmint Colliery 28/08/89 Water infusion-cum-

digging out with subsequent

cement injection/protective

coating

6. Naba Kajora Colliery, Pillar Fire at S.T. 26B 13/02/95 Could not be controlled

taking recourse to all the

combat measures for

controlling the advancing

pillar fires and the mine had

to be ultimately sealed off.

47

PILLAR FIRES ASSOCIATED WITH ADJACENT FIRES:

A new dimension with an all out concerted efforts, tapping all aspects of combat technique-are

needed in case of pillar fires associated with adjacent fires-particularlt when the pllar concerned

is the shaft illar threatening the closure oof the entire mine. A case study made for fire combat in

South Tisra shaft pillar fire, 10th seam, Jharia field, India, is worth mentioning (Thakur, D.N. et

al.,1991).

HISTORY OF FIRE:

The pillar concerned, shaft pillar of pit No.1 of 10th seam, South Tisra Colliery, got surrounded

by an advancing old fire from its three sides (Fig. 3). AG section goaf fire affected the eastern

side of the shaft pillar as well as its north-eastern edge.

Fig. 4V : Part plan of South Tisra Colliery, BCCL. (Not to scale) (Thakur, D.N., 1991)

48

The southern side of the pillar was threatened from advancing BJ goaf fire-which severly

affected the thin barrier (15m) separating BJ goaf fire from the shaft pillar.

Previous attempts to isolate two goaf fires (which got initiated in 1971-72, from surface fires in

Bantulsi Shrubs made in festive ritual Holidahan) could not be contained and controlled by usual

methods of isolation stoppings, trenches and surface dozing.

Status of Heating:

The situation reached such a stage that in mid-1979 temperature recording made within the shaft

pillar itself as well as the barrier pillar between the shaft and BJ goaf, showed more than 600C at

a depth of 6 ft within. The operators in the blind end of the gallery of the haulage plane between

AJ and BJ section could hardly stay more than 15 min, with general body temperature as high as

40-430C high humidity.

CO percentage in the goaf showed 1000 ppm. Flames could be seen and cracking sound heard near

the north-eastern edge in the overhead surface corresponding to the shaft pillar.

It was a matter of weeks only that the shaft pillar was going to be eaten away from the advancing

fire threatening the mine and also an overhead railway line running a few pillars away in its dip

side.

Control/Halt of Fire Advance:

The measures adopted to put an immediate alt of the advancing fire, as well as cool down the

affected shaft pilar and consolidate it, were as below:

Infusion of CO2 from surface, in its north-eastern edge within the sealed gallery through an

existing stowing connection. One ton of CO2 could be infused within two days covering

10 hours in the particular zone where tongue of flames could be seen from the surface.

Infusion cum stowing of water slurry using solid inerts like, 50 kg of dolomite (MgCO3

and CaCO3 mix) per ton of sand, puncturing stopping in BJ section. The inert slurry was

supposed to smother the blazing fire behind the barrier, as well as strengthen the battier

between the BJ fire and the shaft pillar.

Stowing a mixture of sand and dolomite in the southern edge, eastern side, as well as

northern side of the shaft pillar for creating an inert barrier all around it. Of course ripping

of coal/shell were made before hand, so that the inbye goaf fire cannot jump through the

roof.

Injection of alum and sodium silicate slurry, followed by cement and water slurry within

the shaft pillar through bore holes drilled to a depth of upto 6 ft. This was supposed to

consolidate, strengthen as well as cool the shaft pillar. The infusion operation was

continued til the liquid oozed out fromo the surface wall or, forced out through adjacent

bore holes, ensuring saturation point to have been reached.

Continued operation of surface dozing, with creation of intermittent pools (using bentonite

mud flooring, to stop water seepage), for eliminating breathing from shallow OB to the

underground fire zone.

49

All the above operations were continued for nearly 12 weeks and carried out simultaneously

all together, along eith the monitoring of fire.

Application Methodology:

The equipment needed for the infusion operation of the above gel consisted of the following:

1. Mixing chamber: A drum containing the solution to be infused fitted with a funnel for

charging the liquid and a pressure gauge, along with safety valve.

Fig. 4C : Gel infusion set-up (Banerjee, S.C. et al.,1992)

2. Infusion gun for infusing the liquid within coal massive, fitted with a casing as well as

rubber seals (spongy rubber ball type), so that the liquid charge within is not thrown

out on applying infusion pressure.

3. Nitrogen cylinder fitted with a regulator, in order to build up pressure (around 40-60

psi) in the mixing chamber for charging the solution within.

The operational stages are below:

1. Compositional survey of the fire area as well as monitoring the surface temperature

profile as coal surface using IR thermometer, to locate the site of heating and

thereby choose the spot of gel infusion within.

2. Drilling of boreholes (4cm diameter) at selected infusion points to a depth of 2-4 m

within the coal massive, which is usually known to be the most vulnerable zone,

50

prevented by making gel infusion within and thereby consolidating the pillar

concerned.

FIRE DATA

It had a longwall system of mining with seam thickness 9 m, OB 425 m, shaft pillar 60 m X 15 m

with gallery height 4.5 m. The particular zone, in the corss cut J1-J3 of shaft pillar, started showing

signs of heating indicating traces of CO (upto 45 ppm) and temperature above the ambient level

(>350C) in January 1983.

CONTROL MEASURES

Gel infusion (hydrogel of silicic acid, SiO2.nH2O using sodium silicate and ammonium

phosphate mix) operation through nearly 50 boreholes of 35 mm diameter, drilled within the coal

massive upto a maximum depth of 4 m, could consolidate outer layer of the fractured zone up to

3-4 m from the surface, considered vulnerable. Nearly 5000 litres of gel was used to be infused to

consolidate it, within 3-4 months.

EFFECTIVITY

The area got cooled and consolidated by 4 months, to the extent that subsequent monitoring

continued more than six years (till September 1989), did not show any signs of heating, showing

nil CO, temperature at ambient level. (Banerjee, S.C., 1994).

COMPENDIUM

1. All coal pillars with crushed surfaces/cleavages etc. and having appreciable ventilation

pressure differential across its sides are vulnerable to endogenous heating. The risk gets

aggravated with rise in spontaneous heating susceptibility of the seam concerned.

2. Surface temperature profile studies using infrared temperature measuring devices, should

be routinely carried out in such vulnerable pillars. In order to ascertain and follow up the

status of fires, as may be required during fire combat operation, thermo-compositional

studies within the small dia. bore-holes drilled at vulnerable points, may also be done.

Sealed bore-holes are however to be kept plugged when not in use.

In certain cases where fire gases (CO etc.)evolved gets too diluted (with ventilating air) to

its detection, brattice barrier may be hung all around from roof to floor, a little away from

the pillar rib (1m) and studies made of environment in the curtained off zone.

3. Combat designs to be followed for dealing with approachable pillar fires, as developed

from case studies are briefed below:

In case of shallow and small patches of fires it may simply be dug out and quenched

with profuse water, following usual precautions of loading out the fire.

If the heating is deep seated one, covering rather than a wider zone, it should be

cooled not with water, but with continued and repeated operations of hydrogel of

silicic acid along with monitoring of fire. This operation, besides cooling gets the

micro-cracks and fissures of the pillars filled up with gel mass and thus create an

impermeable core, all around and thereby consolidating the pillar.

51

Fire combat operation, however, reach a different dimension if the pillar gets

threatened from other advancing fires around it, besides its own endogenous

heating. In such cases, other fires are to be kept at bay, taking recourse to usual

combat methods, besides simultaneous and repeated gel infusion operation and

related measures for cooling and consolidating the pillar. This becomes particularly

important for saving the shaft pillar from the engulfing fire.

4. In order to prevent future flare up of pillar fires the measures to be adopted are:

Ventilation reorganization so that the pressure differential between its intake and

return side is minimized and thereby restrict air ingress within.

Adequate consolidation of the pillar with gel infusion and also surface plastering

where applicable for creating an air impermeable core all around.

In fact, gel infusion operation has been found to be a useful method to safeguard fire

advancements through fuel bodies.

5. REFERENCES:

1. Sengupta, M., Mine Environmental Engineering, Volume 2, CRC Press Inc., U.S., 1990,

Chapter 4, Page No. 145 to 167.

2. Whiller, A., Notes on Psychrometry in Mining, 2nd Int. Mine Vent. Congress, Reno,

Nevada, 1978.

3. Hartman, H.L. Psychrometry, refrigeration and heat transfer process, in Mine Ventilation

and Air Conditioning, Hartman, H.L., E.d., John Wiley & Sons, New York, 1982, 595.

4. Fenton, J.L., A Survey of Underground Mine Heat Sources, Masters thesis, Montanna

College of Mineral Science & technology, Butte, 1972.

5. Whiller, A., Estimation of Heat Pickup by Ventilation Air Stopes, Research Report 2/73,

Chamber of Mines in South Africa, Johanesburgh, 1973.

6. Mousset-Jones, P. and McPherson, M.J., The determination of in situ rock thermal

properties and the simulation of climate in an underground mine, Int. J. Min. Geol. Eng.,

4, 197, 1986.

7. Vost, K.R., In situ measurements of thermal diffusivity of rock around underground

airways, Trans. Inst. Min. Metall. (London), 85, A57, 1976.

8. Voss, J., Determination of thermal parameters in underground roadways amd faces,

Gluekauf, 106(5), 215, 1970.

9. McPherson, M.J., The application of computers to environmental planning for

underground mines, in Proc. 14th APCOM Symp., Ramani, R.V., Ed., SME-AIME, 1976,

481.

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