Faculty of Engineering and the Built Environment
Department of Mining Chemical and Metallurgical Engineering
MSc in Mining Engineering
Module: MMIN 502 Mine Safety Engineering
Name : Courage Chakanetsa
Reg Number :R176501W
Assignment Number One
Due date: 20 September 2022
QUESTION ONE
(a) As the Mining Engineering Manager, describe your actions on receiving this
information
Give the authority to stop work where Hazard is to allow for further measures to be identified
and employed.
Engage Safety Committees and Safety Representatives.
Allocate sufficient resources for Hazard Control.
Allow implementation of effective risk control measures.
Establish levels of acceptable risk. Ensure that the risks is reduced to levels that are as low as
reasonably practical.
Employee and Contractor Engagement
Develop positive, constructive and effective communications between all interested parties.
Training and Competence
Provision of training and skills required to conduct tasks safely and effectively. Implement a
written hazard communication program and train employees on the hazards they are exposed
to and proper precautions (and a copy of safety data sheets must be readily available). Provide
safety training in a language and vocabulary workers can understand.
Implement a reporting structure to support HSE Improvements.
Update operating procedures and communicate them so that employees follow safety and
health requirements.
Provide medical examinations for employees exposed to the health hazard.
Post, at a prominent location within the workplace, the OSHA poster (or the state-plan
equivalent) informing employees of their rights and responsibilities.
Provide access to employee medical records and exposure records to employees or their
authorized representatives.
Provide to the OSHA compliance officer the names of authorized employee representatives
who may be asked to accompany the compliance officer during an inspection.
Post OSHA citations at or near the work area involved. Each citation must remain posted until
the violation has been corrected.
Assessment Inspection and Audit
Audit and Inspection plans to be developed in consideration of the Hazards and Risks presented
Effectiveness of all corrective actions to be verified prior to close out.
Performance analysis and results of ongoing performance to be published to the company
personnel and its clients as required.
b) What are the key possible causes for this result.
[5 Marks]
Dust particles are generated and can become airborne during many of the extraction and
processing activities associated with producing and processing rock and mineral products.
These activities include:
Drilling
Blasting
Excavating
Loading and tipping
Transporting
Crushing , conveying and screening
Cutting and sawing
Stockpiling
Bagging
Cleaning and maintaining fixed and mobile plant.
The geology of the rock and mining activities to extract and process the rock will determine
the type and quantity of dust particles generated.
1c) Briefly discuss key corrective actions you would consider.
[5 Marks]
Elimination
Adopt production processes that generate less dust (any wet method is likely to generate less
dust than a dry one. Treat the dust at its point of generation, as this is more effective than
capturing airborne dust.
Treat the dust on its transmission path using dust suppression techniques (e.g. water sprays,
chemical additives, local exhaust ventilation (LEV), vacuum).
Substitution with a lesser hazard
Substitute with a less hazardous substance, such as the use of pellets rather than powders, or
replace sand with garnet as abrasive blasting agent.
Separation/isolation of workers from the hazard.
Use remotely operated machinery, such as remotely controlled conveyors.
Engineering controls. Choose appropriate equipment (e.g. correct cutting blades for ore body).
Replace and maintain equipment regularly to ensure cutting blades and picks remain sharp.
Suppress dust by using water sprays on stockpiles and roads, and when using machinery and
cutting equipment. Use additive in water sprays to suppress dust and adjust the droplet size of
the spray according to dust particle size.
Use enclosures (e.g. covered conveyors, enclosed cabs on vehicles, plant and equipment).
Rehabilitate exposed mine land to reduce environmental dust load.
Use ventilation and filtration to minimise dust (e.g. adjust ventilation rates for maximum
efficiency, use local exhaust ventilation when necessary)
Cover product conveyors.
Cover loads for road haulage where practicable.
Administrative controls. Ensure regular maintenance and housekeeping of vehicles.
Maintain unmade roads and ensure ground conditions throughout sites are appropriate to the
machines using them.
Provide training and information to workers on the hazards, risks and controls of dusty tasks,
as well as supervision for workers.
Limit the duration and magnitude of exposure to dust (e.g. worker rotation, job task changes).
Ensure work schedules have adequate rest periods to limit exposure.
Change the location of dumping operations or modify blasting programs to suit weather
conditions.
Ensure higher-order controls are adopted before resorting to PPE.Select the most appropriate
respiratory protection for the task. Ensure training, comfort and fit testing are provided before
use. Respirators should not be shared.
Maintain and store respiratory protective equipment properly.
2a) Outline the actions you would instigate on being informed of the incident.
[10 Marks]
Initiate an emergency mine evacuation plan which provide the road map which miners must
use .
Get information about the location of miners working underground, initiate, conduct, and/or
delegate the following.
Ensure that all underground and surface personnel are notified and made aware of an
emergency as soon as possible.
Account for all underground miners.
Gather miners not dealing directly with the emergency at strategic locations.
Determine the evacuation route to be travelled.
To the extent possible, help determine the safest and quickest route to the surface.
Monitor Atmospheric Conditions. Ensure that mine atmospheric conditions are continuously
monitored for oxygen deficiency, methane content, and elevated carbon monoxide levels.
Instruct personnel evacuating the mine and others not to make ventilation changes. Initiate
sampling of mine gases from mine fans, boreholes, and other locations. Continue to monitor
the fans and returns for mine gases, during and after evacuation. Make every attempt to record
the date, time, and locations of gas readings – indicate the type of gas detectors used. Do not
permit the fan to be stopped, reversed, or speed to be changed. Debrief persons coming out of
the mine to obtain and log information on the conditions underground. Collect all notes and
maps from miners when they have reached the surface.
Contacting Emergency Personnel.
Contact all emergency personnel. This lists the various mine management personnel,
administrators, OSHA Officials, State officials,key mine officials,miners representatives,
police, fire/rescue organizations, and neighbouring nines. Notify family members. Notify
medical support personnel.
Local Coordination. Familiarize local emergency response personnel with the services and
activities that they may be called upon to provide during a mine emergency, such as security,
medical assistance, staging locations, logistics, traffic control, supplies, and the layout of
surface facilities.
Organizing a Command Centre
The Mine Emergency Command System establishes a common framework and practical
procedures for controlling all aspects of a mine emergency.
Establishing Security
Establish security at the mine in order to keep the roads open for mine or emergency personnel,
and to ensure that curious bystanders do not hinder rescue efforts. Incoming traffic on the
roads leading to the mine property should be controlled by authorized personnel to keep
unnecessary vehicles off the roads, and keep these roads open for essential personnel, needed
supplies, and emergency vehicles
Establishing a Fresh Air Base . The fresh air base also functions as a base of communications
for the operation linking the team, the Command Centre, and all support personnel. This is
where rescue/recovery crews begin their exploration of the affected area.
Coordinating Firefighting Personnel
Engage with the fire brigade a and give them information to facilitate on how they can fight
the fire.
Deploying Firefighting Equipment
Provide firefighting equipment used at their mine.
Coordinating Mine Rescue Personnel
Direct many persons who will be performing various tasks during rescue/recovery operations
Deploying Mine Rescue Teams
Mine rescue team are to rescue survivors or recover a mine in the event of a mine emergency.
Establish Press Briefing Area.
Appoint a spokesperson for all entities who is to communicate appropriate information related
to the emergency and brief family members on a regular schedule.
b) Identify the criteria you would establish to determine how the fire is to be fought. [5 Marks]
There is need to consider the direct effects to those in the immediate area of a fire because mine
ventilation systems provide air to all places, How close they are to the fire or whether they are
on the intake side or downstream, How far they are from the nearest unaffected place or safe
haven, How long it would take them to reach a place of safety, bearing in mind such factors as
the loss of visibility in smoke-affected roadways, The type and duration of their self-rescuers.
There will be no dangers of electrocution since the power tripped so you can use firefight in
methods which include use of water to fight the fire.
Heat, Smoke, and Steam Heat, smoke, are other hazards of direct firefighting and will
determine how close firefighters can get to a fire and how long they can work. Working in a
hot, smoky, or steamy atmosphere can be extremely uncomfortable and dangerous.
The build up of explosive gases, such as methane and hydrogen, are very real hazards for teams
during direct firefighting. So the amount of gases in the area is to be considered before fighting.
Ventilation. Should be considered Adequate ventilation over the fire area should help to carry
the smoke, heat, and steam away from the team.
Firefighting Equipment available , Use fire fighting equipment easily accessible rather than
wait for the fire to spread.
When progress cannot be made by fighting fire directly or when other conditions, such as
inaccessibility and probable dangerous accumulations of explosive gas, make sealing
advisable, Mine fires should be sealed.
2(c) Detail the key steps to be taken to return the mine to normal operation post the fire
Before exploring is begun, a preliminary examination should be made of all openings and
escape ways.
Establish communication to keep in touch with outside when crews are advancing.
Establishing ventilation If the ventilating fan has not been destroyed or damaged so, it should
be kept running.
Initiate incident analysis where
A safety inspection should be thoroughly conducted around the switch room and affected areas
to ensure that there are no further hazards. Safety professionals assist the analysis team in the
development of conclusions and recommendations.
Maintenance assists in determining if the lack of preventive maintenance, or any maintenance
procedure, contributed to the incident.
Management reviews incident reports, assists in developing recommendations, and assigns
personnel to oversee corrective action.
After the area affected by a mine fire has been explored, the bodies removed, fires (if any)
extinguished or sealed, and the inspectors and mine officials have completed their
investigations, crews should be set to work building permanent stoppings, cleaning haulage
roads and air courses, and making repairs a necessary to safe operation of the mine.
When all necessary repairs and changes have been made, the States mine inspector should
examine the mine before regular work is started and if in his judgment the mine is in safe
condition, operations may be resumed.
3(a)
Marks]
Briefly define what is “soft wall blasting” and list its potential benefits.
[10
A technique used in surface and underground blasting in which a row or closely spaced drill
holes are loaded with decoupled charges (charges with a smaller diameter than the drill hole)
and fired simultaneously to produce an excavation contour without fracturing or damaging the
rock behind or adjacent to the blasted face.
Benefits include :
Reduced risk of over break or blast damage
Improved long-term integrity and durability of exposed rock surfaces
Reduced costs of shortcrete
(3b)Outline how you would plan this task and the process you would follow to achieve the
project scope.
Obtain specific details about areas of weak burden and potential highwall instability and design
for blasting operations considering these faults.
Drill a group of aligned, triad boreholes in the rock body, the triad group comprising a larger
central borehole for explosive charging and one, empty, smaller, close-spaced, parallel satellite
borehole on each side of the said central borehole.
Drill a series of group of triad boreholes at intervals along a line of desired crack or fracture
in the rock.
Charge the said larger central borehole in each of triad groups with explosives; and
Detonate the charged boreholes to produce a flat plane crack or fracture intersecting each of
the triad groups and in alignment.
Conduct a post-blast inspection to be certain the blast area is safe.
4A) What issues will need to be considered as part of the proposal to mine the new seam
directly below the existing mine workings.
These are design factors to consider for longwall mining multiple seams.
1)The sequence or order in which the seams will be mined. The mining sequence determines
the type of interaction the longwall developments will experience.
2)The design of the gate road pillars, which will define the magnitude of the interaction.
3)The layout of the gate roads and longwall panels, which will define the location of the
interaction.
4)Depth and interburden thickness, will influence interaction magnitude and location and must
also be considered in the design process. The greater the parting thickness between two seams
being mined, the less the interaction between the seam.
5)Parting characteristics. Rock type will influence a multi-seam situation differently.
Sandstone layers tend to be relatively massive and are known to span much wider panels than
thinly laminated shales.
6)Relative location of layouts. In high-extraction layouts such as long wall the gate roads of
the lower seams must be located below those of the upper seam in order to protect them from
high stresses from the upper seam.
In addition to the above, the following
Issues affect multiple seam interaction.
1. Depth of cover. As the depth of mining increases, multiple seam mining induces a
greater potential stress concentration.
2. Mining sequence. Generally, undermining is better that overmining when geotechnical
considerations outweigh economic benefits. Overmining tends to cause subsidence and
damage to the upper seams.
3. Stability of the immediate roof of the seam mined. This is dependent on aspects such
as the strength, discontinuities, water content, and moisture sensitivity of the roof above
the seam mined, which (among other factors) give rise to a coal mass rock rating
(CMRR) value (Mark and Molinda, 2005). CMRR values of greater than 65 are
considered high, and those less than 40 as weak.
4. Stability of the immediate floor of the seam mined. Unstable or weak floor tends to
break or be slippery, making it difficult to manoeuvre or operate machinery. It is
preferable for the floor to be competent.
4b) Outline the options and strategies you could implement to reduce gas content in the target
seam. (Give advantages and disadvantages for all options).
[10 Marks]
There are multiple gas drainage methods. Which can be clustered into three types based on the
borehole trajectory.
SIS methane drainage, UIS methane drainage, and cross-measure borehole methane drainage.
SIS methane drainage
In the SIS methane drainage method, the well is drilled from surface to the targeted coal seam.
A well is drilled from surface. Then it goes along the coal bed, finally intersects the vertical
production well with an installed PCP Pump. Furthermore, in every coal seam, there are two
wells in a chevron pattern drilled to cross the same production well.
Advantages
High safety level and good methane drainage performance,
Disadvantages
It may be time consuming and expensive
UIS methane drainage
The in seam borehole is drilled from the roadway in coal. First, the borehole is drilled, after
which a drainage pipe is put into the borehole. The external end of the drainage pipe is always
connected with the drainage main pipe in the roadway. Then the borehole section near the
opening is sealed through adopting multiple sealing materials, e.g. cement, polyurethane and
other materials Finally, free methane in coal is drained out by taking advantage of negative
suction pressure, during which time the absorbed CH4 desorbs and supplies the methane source
of drainage.
Advantages
UIS methane drainage, inseam boreholes are directly drilled from the coal-seam roadway. Thus
the drilling costs and time of this drainage method decrease.
The drainage patterns are more effective in shielding the safe advancing of roadway and in
reducing methane emissions during longwall mining.
Disadvantages
This method poses great threats to the workers’ safety, particularly, when the coal seam has
high in-situ stress and great methane gas content, as the borehole drilling is conducted inside
the coal seam.
During the UIS methane drainage, negative suction pressure is applied to drain the methane
from coal seam. This could increase the methane drainage efficiency. However, it also causes
a pressure difference between the drainage borehole and the roadway, which results in the
ventilation air leaking from the roadway rib into borehole through fractures around borehole.
This air leakage could decrease the extracted methane concentration due to the leaked air in the
borehole, thus reducing the methane-drainage efficiency.
Cross-measure borehole methane drainage Cross-measure borehole generally is drilled through
multiple rock layers to the targeted methane-bearing coal seam. On the basis of the drilling site,
there are four types of cross measure boreholes. The borehole can be drilled (i) from the surface,
(ii) from the roadway in the mined seam, (iii) from the roadway in the roof rock strata of the
targeted seam, and (iv) from the roadway in the floor rock strata. The first two types of crossmeasure boreholes are mainly used to drain the released methane due to mining activities,
particularly in the gob area and the overburden strata of the longwall mining panel. In contrast,
the last two types of boreholes generally extract the methane from the targeted virgin coal
seams.
Disadvantages
Time consuming and expensive.
When affected by mining activities, Gas Gob Vent holes borehole casing likely experience
three failure modes, resulting from tension, shear, and compression.
Advantages
High safety level and good methane drainage performance.
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Author links open overlay panelJ.Richard Eiser1Mathew P.White8
Controlling
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https://www.business.qld.gov.au/industries/mining-energy-water/resources/safetyhealth/mining/hazards/dust/contr
mines