Mine Ventilation Module: I Mine Ventilation - Introduction Dr. Nuhindro Priagung Widodo Teknik Pertambangan Fakultas Teknik Pertambangan dan Perminyakan, Institut Teknologi Bandung 2009 1
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Brief History of Mine Ventilation
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Between 4000 and 1200 B.C., European miners dug tunnels into chalk deposits searching for flint.
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The Laurium silver mines of Greece, operating in 600 B.C. have layouts which reveal that the Greek miners were conscious of the need for a connected ventilating circuit.
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The first great textbook on mining was written in Latin by Georgius Agricola, a physician in a thriving iron ore mining and smelting community of Bohemia in Central Europe. Agricola's "De Re Metallica", produced in 1556, is profusely illustrated.
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A number of the prints show ventilating methods that include diverting surface winds into the mouths of shafts, wooden centrifugal fans powered by men and horses, bellows for auxiliary ventilation and air doors.
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Brief History of Mine Ventilation • Agricola was also well aware of the dangers of
blackdamp, air that has suffered from a reduction in oxygen content, - 'miners are sometimes killed by the pestilential air that they breathe," and of the explosive power of "firedamp", a mixture of methane and air "likened to the fiery blast of a dragon's breath." • De Re Metallica was translated into English in 1912 by
Herbert C. Hoover and his wife, Lou. Hoover was a young American mining engineer who graduated from Stanford University and subsequently served as President of the United States during the term 1929-1933.
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Brief History of Mine Ventilation • The Industrial Revolution brought a rapid increase in the
demand for coal. Conditions in many coal mines were quite horrific for the men, women, and children who were employed in them during the 18th and 19th centuries. Ventilation was induced either by purely natural effects, stagnating when air temperatures on the surface and underground were near equal, or by fire. • George Stephenson, admitted to this practice during the inquiries of a government select committee on mine explosions in 1835. A common method of removing methane was to send a "fireman'' in before each shift, covered in sackcloths dowsed in water and carrying a candle on the end of a long rod. It was his task to burn out the methane before the miners went into the working faces.
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Brief History of Mine Ventilation John Buddle (1773-1843), an eminent mining engineer in the
north of England produced two significant improvements. First, he introduced "dumb drifts" which bled sufficient fresh air from the base of a downcast shaft to feed the furnace. The return air, laden with methane, bypassed the furnace. Buddle's second innovation was "panel (or split) ventilation". Until that time, air flowed sequentially through work areas, one after the other, continually increasing in methane concentration. Buddle originally divided the mine layout into discrete panels, with intervening barrier pillars, to counteract excessive floor heave. However, he found that by providing an intake and return separately to each panel the ventilating quantities improved markedly and methane concentrations decreased. He had discovered, almost by accident, the advantages of parallel layouts over series circuits. The mathematical proof of this did not come until Atkinson's theoretical analyses several decades later 6
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Brief History of Mine Ventilation A crisis point was reached in 1812 when a horrific explosion at Felling, Gateshead killed 92 miners. With the help of local clergymen, a society was formed to look into ways of preventing such disasters. Contact was made with Sir Humphrey Davy, President of the Royal Society, for assistance in developing a safe lamp. Davy visited John Buddle to learn more of conditions in the mines. As this was well before the days of electricity, he was limited to some form of flame lamp. Within a short period of experimentation he found that the flame of burning methane would not readily pass through a closely woven wire mesh. The lamp glowed 'red hot' because of the methane burning vigourously within it, yet the flames could not pass through the wire mesh to ignite the surrounding firedamp. 7
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Brief History of Mine Ventilation • Perhaps the greatest classical paper on mine ventilation was one
entitled "On the Theory of the Ventilation of Mines", presented by John Job Atkinson to the North of England Institute of Mining Engineers in December, 1854. • During Atkinson's productive years the first power driven ventilators
began to appear. These varied from enormous steam-driven piston and cylinder devices to elementary centrifugal fans. • Improved instrumentation allowed organized ventilation surveys to
be carried out to measure airflows and pressure drops for the purposes of ventilation planning, although there was no practical means of predicting airflows in other than simple circuits at that time. Atkinson's theory was confirmed in practice. The first successful axial fans were introduced in about 1930. 8
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Brief History of Mine Ventilation In 1943, Professor F.Baden Hinsley produced another
classical paper advancing understanding of the behaviour of airflow by using thermodynamic analyses. Hinsley also supervised the work at Nottingham University that
led to the first practical use of analog computers in 1952 to facilitate ventilation planning. This technique was employed widely and successfully for over a decade. This is now the dominant method used for ventilation planning
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UNDERGROUND EXCAVATION
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Longwall Coal Mine
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Mining Front
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VENTILATION PURPOSES Supply a fresh air into the tunnel for inhalation of workers and all of the
process which happen in the tunnel. Mine ventilation means total air conditioning: 1. Quality control (purifying and removing contaminants) a. Gas control – vapors and gaseous matter, including radiation b. Dust control – particulate matter 2. Quantity control (regulating magnitude and direction of airflow) a. Ventilation b. Auxiliary or face ventilation c. Local exhaust 3. Temperature – humidity control (controlling latent and sensible heat) a. cooling; b. heating; c. humidification; d. dehumidification 13
FACTOR AND CONTROL FOR MINE VENTILATION RISKS
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MINE AIR FLOW PRINCIPLES Air will flow from the place that have a low temperature to place
which have a higher temperature (high pressure to low pressure) Air will flow through a low resistance ventilation airways rather than the higher resistance airways Mine ventilation is essentially the application of the principles of fluid dynamics to the flow of air in mine openings.
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AIR PRESSURE
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THEORY (i)
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MOODY DIAGRAM
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AIRWAY FRICTION
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FAN
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FAN
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FAN
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FAN
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INSTRUMENTS IN VENTILATION SURVEYS
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TRACER GAS METHODS
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TRACER GAS METHODS
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Ventilation Surveys and Simulation
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Strata Gas
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Diesel Exhaust Fumes
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Dust
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Heat
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Workshops and other areas
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Air velocity limits
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Ventilation Planning
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VENTILATION OF ROADWAYS TUNNEL
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VENTILATION OF ROADWAYS TUNNEL
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SCOPE OF A MINE VENTILATION STUDY Review of the various airborne contaminants (dust, gases, radon, heat,
etc) and how these will be managed. Included in this would be filtration, dilution, exhaust or other control strategies and any cooling or heating required, and the location, type and size of such devices. The primary ventilation network at all key milestones in the development, construction and production phases. This should include the system of airways and their sizes, friction factors and shock losses, and the location and specification of all fans and ventilation control devices. This is basically addressing the issue of the volume and distribution of air throughout the mine life. 44
Scope of a Mine Ventilation… Secondary/auxiliary ventilation design. Review of egress and entrapment provisions in the mine over its life.
A ventilation management plan which covers the day to day operation
and management of the ventilation system and any trigger action response plans (TARPs), standard work or operating procedures (SWPs, SOPs) for ventilation-related tasks, etc. Formal risk assessments covering both the normal operations and dayto-day activities and all credible abnormal operations or events (power failures, fire, collapse of a major airway, etc)
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KEY FACTORS TO BE CONSIDERED BEFORE COMMENCING ANY VENTILATION DESIGN
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Dust, radon and/or methane or other airborne gaseous, fume or particulate contaminants or asphyxiants (e.g. nitrogen) Gas contents of orebody/coal seam and adjacent strata; issues of gas drainage Spontaneous combustion potential Outburst potential Water inundation (flooding) potential Dust audits, silica (or other contaminant) contents of strata Production, development, diamond drilling, raiseboring (or other vertical development) and production drilling schedules Other important schedules or deadlines (e.g. construction schedules) Mining methods, layouts, mine design, etc Manpower schedule, by job type and location – for both production and construction phases
Key Factors To Be Considered …. Major mobile equipment schedules, especially diesel equipment (maximum kW rating,
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dimensions, speed loaded and unloaded, up and down ramp, tonnes moved) Mode of operation of diesel equipment (where travel,when, truck/loader combinations) Diesel fuel usage, average and maximum per shift Fixed electrical plant and efficiencies Any special areas requiring filtered air or special ventilation (e.g. control rooms, crib rooms, offices, ventilation at crusher jaws, transfer points on belts, tipping points) Coal, ore, mullock/waste or other materials handling flowcharts Humidity limits for ore/waste including transfer points Humidity limits for ground control/rock strata Backfill system and operation, type of fill, method of placement Locations of fuel and oil storage, refueling, other major stores, combustible material, etc
Key Factors To Be Considered …. Parking arrangements Special fire fighting standards Special egress or entrapment standards Any maintenance arrangements impacting on egress (outages, inspections, etc) Minimum medical/physical requirements for continuing employment or for visitors Blasting arrangements: development and production, bins, chutes, etc, including
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frequency of blasting: development and production Re-entry times after blasting etc ANFO and other explosives consumption rates: development and production Cement usages and consumption rates Oxidation rates (to SO2 and/or CO2) Working in heat protocols Other special ventilation-related hazard protocols
Key Factors To Be Considered …. Internal corporate ventilation/workplace environment standards for each job type (i.e. typical
ventilation arrangements) Statutory (legislative) requirements Internal (company or mine) generic standards, hazard management plans, etc Any noise criteria (impacting on noise insulation or siting of fans etc) Any sources of dust, e.g. due to cutting, loading, etc Dust controls (e.g. sprays) at drawpoints, tipples, conveyors, roads Other sources of heat Surface climate (WB, DB, BP) by hour for minimum of six years Surface elevation above sea level Depth of mining operations Near-surface virgin rock temperature and geothermal gradient Rock thermal conductivity, thermal capacity, diffusivity, density Maximum heading lengths for auxiliary development, development heights and widths Method of auxiliary ventilation, type and size of ducts, leakage factors 49
Key Factors To Be Considered …. Any existing ventilation circuits, fans (including fan curves), controls etc Any existing cooling devices Usage and policy on air-conditioned cabins in mobile equipment and fixed plant Mining (especially horizontal and vertical development) and ventilation (fan, controls, ducting)
costs Friction (“k”) factors and shock losses used or measured in the operation Any surface considerations (dust from quarrying etc, prevailing winds, grass/bush fires, nearby plant) Surface environmental limits on fans and shafts: noise, dust, water, smell, visual amenity Shaft, raise and other major airway resistances and last time measured Standards in regard to allowable pressures on ventilation doors (airlocks) or other ventilation controls Ventilation or isolation of caved regions or goafs; leakage and pressure balancing Network analysis and validation (comparing to measured data) 50
Key Factors To Be Considered …. Multi-level tipping controls or protocols Ground/fissure water in mine (amount, location, temperature (if very hot)) Location of shafts, fresh and return air raises, distances apart (determines typical auxiliary
ventilation line configurations and lengths) Wetness of shafts. If wet, potential for water corrosion or erosion on fans. Potential for the shaft to be subject to erosion or sloughing or water plugging Natural ventilation pressures; seasonal changes; impacts of refrigeration on natural ventilation pressures Network simulation program used; Other computer programs in use or required to be used Data on ventilation monitoring (e.g. strata gases, diesel exhausts, airflows, on-line monitoring) Recent or relevant ventilation or feasibility studies; Any other safety aspects that need to be considered Any recent ventilation audits completed; Any concerns from the operators or planners about current or future ventilation problems Any telemeter, remote monitoring or remote operation/control requirements 51
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MINE VENTILATION
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COAL UNDERGROUND MINE
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SERIOUS DISASTERS RELATED TO MINE VENTILATION IN JAPAN Date 63/11/9 64/6/1 65/2/22
Mine Miike Yamano Yuubari
Category Dust explosion Gas explosion Gas explosion
66/3/22 66/11/1 68/1/20 68/5/12 68/7/30 69/4/2 70/12/15 72/11/2 73/12/19 75/11/27 77/5/11 79/5/16
Sorachi Honbatsu Bibai Bibai Heiwa Mojiri Sunagawa Ishikari Sunagawa Horonai Ashibetu Minami ooyuubari Yuubari sinkou Ariake Takashima Minami ooyuubari
Gas dust explosion Gas dust explosion Gas explosion Mine fire Mine fire Gas explosion Gas explosion Gas explosion Gas explosion Gas explosion Gas explosion Gas explosion
? ? Spontaneous combustion Blasting Blasting Blasting ? ? Blasting ? Blasting ? Blasting Blasting Static electricity
Gas explosion
Static electricity
１０
Mine fire Gas explosion Gas explosion
Belt conveyor Static electricity Static electricity
８３ １１ ６２
81/10/16 84/1/18 85/4/24 85/5/17
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Cause
Fatalities ４５８ ２３７ ６２ １２ １６ １６ １３ ３１ １９ １９ ３１ １５ ２４ ２５ １１
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Kompas, Senin, 29 November 2004, 02:52 WI 25 Tewas 140 Terperangkap Dalam Kecelakaan Tambang di Cina Tongchuan, Cina, Senin Sedikitnya 25 pekerja tambang tewas dan sekitar 140 terperangkap Minggu (28/11) ketika ledakan gas terjadi di sebuah tambang batubara di Cina utara. Kemungkinan ini merupakan musibah terburuk yang melanda produsen tambang terbesar dunia itu dalam beberapa tahun ini. Dari 293 petambang yang bekerja di bawah tanah ketika ledakan itu terjadi di tambang batubara Chenjiashan di provinsi Shaanxi, Minggu pagi, 127 berhasil menyelamatkan diri atau diselamatkan, kata tim penyelamat menurut Kantor Berita Xinhua. "Mereka yang menyelamatkan diri dari ledakan gas itu terutama pekerja di dekat pintu terbang dan seluruh korban cedera telah dirawat di rumah sakit, termasuk 11 orang yang cedera parah," kata petugas penyelamat di lokasi kejadian. "Seorang pekerja yang diselamatkan mengatakan bahwa meski bekerja di sebuah lokasi sekitar 1.500 meter di bawah tanah, ia terjatuh oleh hempasan arus udara kuat yang ditimbulkan ledakan itu," kata petugas tersebut lagi, Senin (29/11) pagi. Petugas penyelamat mengalami kesulitan mendekati lokasi ledakan karena tingkat karbon monoksida yang tidak aman. Prioritas utama adalah memperbaiki sistem ventilasi yang rusak parah di tambang itu untuk menjamin keselamatan tim penyelamat, kata Zhao Tiechui, wakil kepala Biro Keamanan Produksi Negara. Enam tim penyelamat sedang berusaha menjangkau para pekerja yang terperangkap dan 10 tim tambahan didatangkan untuk membantu mereka. Pemerintah provinsi tersebut telah memerintahkan semua tambang NPW dengan konsentrasi gas tinggi menghentikan operasi mereka untuk pemeriksaan keamanan. 61 ….
AN EXAMPLE OF CONCENTRATIONS OF GASES DOWNWIND OF A FIRE * Saiko to Hoan vol.24,No7,1977
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25
H2(%)
7
CH4(%)
20 Concentration(%)
6 Concentration(%)
O2(%)
CO(%)
5 4
3 2
CO2(%)
15 10 5
1 0
0 0
10
20
30
40
Time(min)
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50
60
70
0
10
20
30 40 Time(min)
50
60
70
HUMAN TOLERANCE TO TOXIC GASES ppm ＣＯ ＣＯ2 ＳＯ2 ＮＯ2 Ｈ2Ｓ
minutes 3000 50000 400 240 1000
30min 1600 40000 150 100 700
1-2 hours 800 35000 50 50 500
8hours 100 32000 8 30 100
HUMAN TOLERANCE TO OXYGEN DEFICIENCY Oxygen (%) 21 17 14 12 9 6
Effects on Human Body None Impaired muscular co-ordination Danger level of self-escape Dizziness, headache, rapid fatigue Unconsiousness Death in 6-8 minutes
* Birch, N.,Passenger Protection Technology in Aircraft Accident Fires. Gower Technical Press, 1988
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AIR TEMPERATURE DOWNWIND OF A MINE FIRE Temperature(℃)
1000
v=3m/s
800
v=1m/s 600 400 200 0 50
100
150
200 250 Distance(m)
300
350
400
HUMAN TOLERANCE TO AMBIENT TEMPERATURE Temperature (C) Time (minutes) 64
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60 120
70 65
80 45
100 15
120 10
140 5
150 1
LOWER AND UPPER EXPLOSIVE LIMIT OF SOME COMBUSTIBLE GASES
Combustible gas Methane Ethane Propane Carbon monoxide Hydrogen Hydrogen sulfide
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Limits of explosibility, volume (%) Lower limit Upper 5.0 15.0 3.0 12.5 2.3 9.5 12.5 74.2 4.1 74.2 4.3 46.0
Methane (CH4)
Methane (CH4)
MINE FIRE DETECTIONS
PERFORMANCE OF MINERS RELATIVE TO THE MINE AIR TEMPERATURE
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OPERATIVE AND EFFECTIVE TEMPERATURE
Operative temperature 70
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Effective temperature
THRESHOLD LIMIT (TIME-WEIGHTED AVERAGE) VALUES FOR VARIOUS DUSTS IN DIFFERENT COUNTRIES (AFTER MAJOR, 1978, AND WALTON, 1978) Coal dust (mg/m3) Australia 5;respirable dust containing <= 5 % free silica UK 8;longwall faces
USA 2;respirable dust containin g <=5 % quartz
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Quartz -containing dust (mg/m3)
Asbestos (fibres/ml)
25／(% respirable free silica + 5)
4;for chrysotile and amosite; 2;long -term average for other than crocidolite
3- drivages if quartz >0.45 mg/m3 6if quartz <0.45 mg/m3 6 - other places
0.2;for crocidolite when measured over a 10 minute period; 2; for other types of asbestos averaged over a 4 hour period
10／(% respirable quartz + 2)
2; >5 μm long(8 hour time average)
-weighted
Requirements of underground air in quantity and quality < Coal Mine Safety Regulations of Japan > (Oxygen and carbon dioxide) Article 86 Mine air underground where mine workers work or pass shall contain 19% or more oxygen and 1% or less carbon dioxide. However, this shall not be applied in cases where oxygen concentration is 19% or more and carbon dioxide is 2% or less with permission by the Director-General of MSIB or MSID. 2. The provision of the preceding Clause shall not be applied the working place where human life rescue or the activity regarding safety is conducted in a safe way. (Inflammable gas content in the main return air) Article 87 The inflammable gas content in the main return air shall be kept at 1.5% or less. However, this Article shall not apply to cases where inflammable gas from gas drainage holes or exclusive galleries for drainage gas is released into the main exhaust, under the condition that the ventilation quantity is sufficient to dilute the inflammable gas concentration to 2.5% or less and that permission is given by the Director-General of MSIB or MSID, neither does it apply to cases which are stipulated by Article 104-2 and Article 124. (Inflammable gas content in working places and roadways) Article 88 The inflammable gas content shall be kept at 1.5% or less in underground working places and at 2% or less in underground roadways. However, this Article shall not be applied to cases stipulated in Item 2 and Item 4 in Article 124. Underground temperature) Article 89 The temperature of the working place shall be 37 C or less. However, this provision shall not be applied to the working place where there is activity due to a special reason such as a gush out of hot spring with permission of the DirectorGeneral NPWof MSIB or MSID or human life rescue regarding safety is conducted in a safe way. 72
(Ventilation quantity) Article 90 The ventilation quantity of underground working places shall be decided based on the number of mine workers, the quantity of inflammable gas or harmful gas produced, the possibility of spontaneous combustion, temperature and humidity. 2. Air current and flow volume in underground working place shall maintain adequate speed and volume which is sufficient to dilute and sweep away inflammable gas or harmful gas and fumes of blasting.
Article 91 In all Class-A pits, the ventilation quantity at the entrance of intake shall be 3 m3 /min per person or more and this is based on the maximum number of workers engaging in underground working at the same time. However, when it is required to restrict the ventilation quantity for prevention of spontaneous combustion etc. and with the permission of the Director-General of MSIB or MSID, the ventilation quantity may be reduced.
(Ventilation speed) Article 92 Ventilation speed underground shall be 450 m/min. or less (except an exclusive gallery for ventilation). However, in a shaft the speed may increase up to 600 m/min. 2. The ventilation speed in the preceding Clause may be increased due to a special reason with the permission of the DirectorGeneral of MSIB or MSID.
(General ventilation facilities) Article 94 In a mine having a coal pit where 50 mine workers or more are working, a barometer and a thermometer shall be installed in a proper place.
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Decree of The Minister of Mines and Energy No. 555.K/26/M.PE/1995 on General Mining Occupational Safety and Health Part Eight Ventilation Article 369 General Provisions
(1) At any underground mine : a. the Technical Mine Manager shall ensure that an adequate supply of fresh air is available at every work site with the requirement that the oxygen content in air shall be no less than 19.5 percent and the carbon dioxide content shall be no more than 0.5 percent; b. it is prohibited to send any employee to work at any work site that contains dust smoke or vapours in concenhations that may be disruptive to health and c. airflow shall be sufficiently adequate to reduce or remove concentrations of smoke from blasting as soon as possible. 74
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Article 369 General Provisions (2) When the presence of combustible and explosive gases is detected in any mine ventilation system, the Technical Mine Manager shall take appropriate corrective measures. (3) The volume of fresh air passing through the ventilation (4) system shall : a. be calculated based on the maximum total number of workers at the work location with the requirement that no person shall receive less than 2 cubic meters per minute for the duration of work and b. an additional 3 cubic meters per minute for every degree of horse power where a diesel machine is being operated. (5) The Mine Inspector may order the Technical Mine Manager to increase the quality and volume of fresh air flow at any section of the mine.
(6) It is prohibited to re-circulate air in any ventilation system.
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Article 370 Ventilation Standards (1) The air temperature in any underground mine shall be maintained at between 18 degrees Celsius and 24 degrees Celsius with maximum relative humidity at 85 percent. (2) Apart from the requirements of paragraph (1) letter a the ventilation conditions at the work site shall : a. for an average of 8 hours : 1) 2) 3) 4)
have a carbon monoxide (CO) volume of no more than 0.005 percent; have a methane (CH4) volume of no more than 0.25 percent; have a hydrogen sulphide (H2S) volume of no more than 0.001 percent and , have a nitrous oxide (NO) volume of no more than 0.0003 percent.
b. over any 15 minute period : 1) CO must not exceed 0.04 percent and 2) NO2 must not exceed 0.0005 percent.
(3) Flame safety lamps or any other suitable device shall be used to test for any lack of oxygen. (4) Any location that does not require ventilation shall be sealed and signs prohibiting entry thereto shall be installed. 76
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Article 370 Ventilation Standards (5) In every sealed area, stoppings shall be provided with a pipe and a valve to permit sampling of the atmosphere and measurement of the pressure behind such seal. (6) The ventilation velocity shall be no less than 7 meters per minute and shall be increased in accordance with work requirements and after blasting. (7) All airways shall be of adequate dimensions for the quantity of air they are designed to pass. (8) The Technical Mine Manager shall appoint an employee who shall be in charge of supervising ventilation of the mine and the name of the said employee shall be recorded in the Mine Book. (9) The quantity and quality of air being distributed to every work area shall be determined at intervals of at least once per month (10)
The locations at which measurements are taken shall include:
a. every main intake airway, as near as practicable to the entrance of the shaft or outlet; b. at every split where air leaves the main airfIow, as near as possible to the junction; c. where the split serves a working district : 50 meters from the first working place at which the air enters, and 50 meters from last working place at which the air leaves the district; d. in the district return airway, as near as practicable to the junction with the main return airway. e. any other place stipulated by the Mine inspector.
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Article 370 Ventilation Standards (11) Sampling to determine & oxygen content (O2), carbon dioxide content (CO2), carbon monoxide content (CO) and nitrous oxide content (NO2) of the air taken under normal working conditions shall be implemented at intervals of at least once per month at the following places: a. 30 meters from the working face of development headings; b. 15 meters from the winzes and shafts and c. at the base of the up-cast shaft and at any stope with only one access way.
(12) Sampling for the purpose of determining the carbon monoxide content (CO) and nitrous oxide (NO2) content at any location or at the end of any shaft where a diesel machine is being operated shall be carried out at intervals of at least every seven days. (13) Results of findings of the requirements of paragraph (11) and paragraph (12) shall include the time and location of where the samples were taken as well as the time of the most recent blasting.
(14) Temperature shall be measured regularly at locations as required in paragraph (10) letter c and d, and where the temperature exceeds 24 degree Celcius, the said place shall be inspected every week. 78
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Article 370 Ventilation Standards (15) Measuring for dust concentrations at lower than l0 microns shall be carried out as often as practicable but no less than once every three months except where otherwise stipulated by the Chief Mine Inspector. (16) When any changes are made to the direction or distribution of airflow which affects the amount of air entering or leaving and area, air measurements shall be carried out as soon as possible after the said change is made. The results of air measurements as required in paragraph (16) shall be recorded in the ventilation book.
(17) (18)
Ventilation measuring shall be carried out by a competent person.
(19) Sampling as specified in paragraph (1) and (2) shall not be required where according to the judgment of the Chief Mine Inspector the condition of ventilation in the mine is adequate.
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Article 371 Natural Ventilation (1) Use of natural ventilation shall be approved by the Chief Mine Inspector. (2) When every part of the mine continuously makes use of natural ventilation the requirements of Article 369 and Article 370 shall be fitted with a ventilation fan at the surface which shall be used when required. (3) Based on the size of the mine and the condition of the environment of work sites at the mine the Mine Inspector may require that an auxiliary ventilation fan is necessary with a capacity of no less than what is required to distribute an adequate quantity of air which is required to workers when evacuation must be carried out.
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Article 372 Ventilation Fans (1) Whenever practicable, surface ventilating fans (main fans) shall be equipped with the following: a. b. c. d. e. f. g.
an alternative power source; a water gauge; either an automatic fan rotation indicator or an automatic air pressure indicator; an efficient air lock; a fan drive and fan house both of which must be fireproof; fireproof air ducts and pressure relief devices; equipment that is capable of reversing the direction of the flow of air and on which regular testing must be carried out and h. other safety devices which shall be stipulated by the Chief Mine Inspector.
(2) The Technical Mine Manager shall provide instructions to the operator of the ventilation fan about the rotation speed of the said fan. (3) The operator as required in paragraph (2), shall test the ventilation fan, and observe the water gauge and the automatic indicators at intervals of at least every 2 hours.
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Article 372 Ventilation Fans (4) When the measuring devices and the automatic ventilation pressure recorder are not available, the operator of the ventilation fan shall record the rotation speed of the wind fan and the pressure as indicated on the water gauge every two hours. (5) As required in paragraph (2), the operator shall make a report to his/her supervisor of the following : a. any damage, deviations or the stopping of the ventilation fan and b. unusual variations in pressure as indicated by the water gauge.
(6) Every ventilation fan at the surface of a mine that is not attended shall be fitted with permanent monitoring equipment which sends early warnings of the presence of any defects in the operation of the ventilation fan to a location that is always manned. (7) The intake (suction site) of fans shall be provided with an adequate guard or screen. (8) Depending on the size and the environmental conditions of the mine, the Mine Inspector may determine the need for a reserve ventilating fan available for immediate use and capable of producing sufficient airflow.
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Article 372 Ventilation Fans (9) The ventilation fan housing, the air duct connections, the fan house, and other buildings in the vicinity of the ventilation fan shall be constructed of non combustible materials, However, where made from combustible materials the wind fan and surrounding buildings shall be adequately protected from fire. (10) The up-cast shaft connected to a drift or air duct to the ventilation fan shall be fitted with an airlock which prevents the occurrence of short circuits of airflow. (11) It is prohibited to build any combustible structure within a distance of 50 meters of the ventilation fan house. (12) The auxiliary ventilation fan shall be installed underground while other ventilation fans may also be installed after approval is obtained" to ensure that disruptions to the safety and health of underground mine workers will not occur. (13) All underground main fans shall have controls placed at a suitable protected location remote from the fan preferably on the surface. An independent alternative power supply from the surface shall be provided. (14) It is prohibited to stop a ventilation fan except where approval has been obtained from the ventilation supervisor. 83
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Article 372 Ventilation Fans (15) It is prohibited to install an booster fan underground except where a ventilation survey has been conducted.
(16) All ventilating fans installed and used to ventilate active workings of the mine, shall be operated continuously while persons are underground in the active areas except for scheduled production cycle shutdowns or planned fan maintenance or adjustment. All persons underground in the affected areas shall be advised in advance of such scheduled fan shutdowns. No blasting operations shall be allowed during any fan stoppage. (17) In the event of a fan failure due to malfunction, accident, power failure or any other such unplanned or unscheduled events, all mine workers shall leave any area ventilated by the fan except any employee who is repairing the said ventilation fan. Ventilation shall be maintained and restored to normal before any mine worker enters any area affected by the ventilation system.
(18) All ventilation fans shall be maintained in accordance with the manufacturer's instructions or the written schedule as specified by the Technical Mine Manager.
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Article 373 Ventilation Fan Systems (1) Before any auxiliary fan is installed below ground the Underground Mine Manager must be satisfied that a sufficient quantity of air is reaching the fan to prevent recirculation of air, and this air is not polluted by dust, smoke, or hazardous gases. (2) Auxiliary ventilation fans shall be equipped with grounding devices. (3) Auxiliary ventilation fans may only be activated, operated and turned off by the authorized employee. (4) Auxiliary fans shall be installed at a point at least 5 meters from the nearer side of the entrance to the place to be ventilated by it. (5) When two or more auxiliary fans are installed in a series the requirements of paragraph (4) shall only apply to one of the said fans. (6) Any forcing type auxiliary ventilation fans shall be installed at the intake airway and exhaust type auxiliary ventilation fans shall be installed at the return airway. (7) There shall be installed and maintained with every auxiliary fan an air duct to within a distance from the working face of 5 times the square root of the roadway cross-section, measured in meters.
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Article 373 Ventilation Fan Systems (8) When an auxiliary fan fails to function all workers shall be prohibited from entering any place ventilated by the fan until the said place is declared safe following an inspection by the operational supervisor. (9) Compressed air may not be used solely for ventilation except in narrow and steep raises. (10) Air for ventilation in raises shall be provided such that the flow can be controlled from a valve at the foot of the raise. Development raises shall be provided with two air valves, one at the foot of the raise and one at the end of the steel pipe inside. (11) Ventilation pipes for raises must be independent of service pipes and fitted at the outlet with a diffuser. (12) Where compressed air is used for ventilation the air shall be sampled at monthly intervals to determine CO, NO2 and oil mist content No air shall be used if the analysis exceeds the limits specified in paragraph 2 of Article 370.
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Article 374 Ventilation Circuits (1) The main intake airway and the main return airway shall be made in separate shafts or adits.
(2) The Chief Mine Inspector may grant exemption of the requirements in Paragraph (1). (3) Ventilation in the shaft may only be made with the following provisions : a. vent tubing may be used at the same opening at the time of development of the shaft or slope and b. the intake airway and return airway at the single shafts shall be provided with air curtains.
(4) Fresh air that enters through the downcast shaft shall be properly distributed to all work places as required. (5) Where any abnormality occurs to the ventilation circuit or any abnormal change occurs in the flow of air, the underground mine workers shall inform the operations supervisor. (6) All airways shall be kept clear to permit free passage of air.
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Article 375 Prevention of Air Leakage (1) Any shaft or outlet to the surface that is corrected via a drift to ventilation fans at the surface and which are normally used for hoisting or transportation shall be fitted with efficient air locks and be well maintained.
(2) Every drift which connects main intake airways to the main return airway or which connects the intake and return airways shall be fitted with two adequate doors and shall be well maintained to reduce leakage of air to a minimum. Where this is not possible other means must be used. (3) Any drift which requires prevention from short circuiting of air flow shall be fitted with no less than two adequate doors and be well maintained. Where this is not possible one door is allowable with one or two ventilation curtains. (4) A space shall be provided between the ventilation door or ventilation curtain in order that when one door or ventilation curtain is opened the other door or ventilation curtains closed to prevent air from passing. (5) Ventilation doors shall be capable of closing automatically and ventilation curtains must be fireproof.
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Article 375 Prevention of Air Leakage (6) It is prohibited to prop a ventilation door open except where and for so long as it is necessary to allow a vehicle to pass through it. Any door no longer required to be shut shall be removed and placed in a position in which it will not obstruct the airflow. (7) Every person shall properly close any door or ventilation curtain through which he/she passes. (8) Only authorized employees shall change ventilation regulators.
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Article 376 Ventilation Plans
Apart from the requirements of Article 19, the ventilation plan shall include the following information : a. the name of the mine and b. the most up-to-date map or series of maps with the scale no larger than I : 5000, and which includes : 1) 2) 3) 4) 5) 6) 7)
the direction and distribution of airflow: the location of the main ventilation fan, the booster ventilation faq and auxiliary fans; the location ofthe air regulator doors, stoppings, and ventilation doors: the location of undercasts or overcasts, and other crossings; the location of seals at abandoned work site areas; the location ofareas not ventilated; the location of workshops, fuel storage areas, the hoist room, compressors, battery charging rooms, and explosive magazines and 8) air measuring stations and the latest ventilation measurements taken.
c. data on the main fan, the booster fan and auxiliary fans including the name of the manufacturer, the type, the size of the fan, the speed of the fan, the size of the blades, pressure at several points and motor brake horsepower rating; d. the number and type of vehicles using fuels underground including the horsepower of the said machines and e. any other information requested by the Chief Mine Inspector. 90
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