Kuliah 3 - Mine Gases

8/10/2019 Kuliah 3 - Mine Gases

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ine

ases

Rini Novrianti Sutardjo Tui



Occurrence of Mine Gases

Drilling

Blasting

Using diesel

engines

Mining coal

Underground

explosion and fires

Oxidation



Composition of Fresh Air

Element % volume % weight

Nitrogen (N2) 78.09% 75.53%

Oxygen (O2) 20.95% 23.14%

Carbon dioxide (CO2) 0.03% 0.046%

Argon (Ar), dll 0.93% 1.284%

Oxygen content in mining is always kept at safe level, which is

between 19.5% to 23.5% volume.

Fresh air is assumed to always contain 0.03% carbondioxide and also always contain moisture.



Need of Fresh Air

Oxygenconsumption

(lt/min)

Energy expenditure

(kal/min)

Heart rate during

work (beats/min)

Light 0.5 – 1.0 2.5 – 5.0 60 – 100

Moderate 1.0 – 1.5 5.0 – 7.5 100 – 125

Heavy 1.5 – 2.0 7.5 – 10.0 125 – 150

Very Heavy 2.0–

2.5 10.0–

12.5 150–

175

Respiratory rateper min

Inhaled airin3/min

(10-4 m3/sec)

Consumed oxygencfm (10-5 m3/sec)

RespiratoryQuotient

Relaxed 12 – 18 300–

800(0.82 – 2.18)

0.01 (0.47) 0.75

Moderate work 302800 – 3600(7.64 – 9.83)

0.07 (3.29) 0.90

Heavy work 40 6000 (16.4) 0.10 (4.70) 1.00

Dr. Lucien Brouha



Amount of Air Needed for Respiratory

Minimum Need of O2,19.5%

In respiratory, the amount of oxigen will decrease 0.1 cfm; therefore, theequation for the quantity of oxygen is:

0.21Q – 0.1 = 0.195Q

Maximum Content ofCO2, 0.05%

If the grade of respiratory is 1.0; then,the quantity of CO2pada in respirating will increase 1.0 x 0.1 = 0.1 cfm.

0.0003Q + 0.1 = 0.0005Q

sec102.37.6195.021.0

1.0 33 mcfmQ sec01.03.21

0003.00005.0

1.0 3mcfmQ



Effects of Lack of Oxygen

O2 Content in the Air Effect

17% Increasing respiratory rate

15% Dizzy, sounds of ringing in ears, faster heart beat

13% Losing consciousness

9% Pale and unconscious

7% Jeopardizing life

6% Spasm and death



Toxic Hazards

These gases induceinflammation intissues such as theskin, etc when

come into contact(nitric oxide,nitrogen dioxide,partially oxidizedhydrocarbons)

There two types:simple and chemical.Simple asphyxiantexcludes oxygen fromthe lung (carbon

dioxide andmethane). Chemicalashyxiant deprives

the oxygen-carryingcapacity (carbonmonoxide).

These gasesdestroy thetissues with which they come

into contact(nitric oxide,hydrogensulphide, sulphurdioxide).

AsphyxiantGases

IrritantGases

PoisonousGases



Mine Gases

Name SymbolSp.

Gravity

(air = 1)

Physical

Properties

Harmful

Effects

Main SourceTLV – TWA

(%)

TLV-C

(%)

FatalPoint

(%)

Oxygen O2 1.1056Odourless,colourless,tasteless

Non toxic Normal air

Nitrogen N2 0.9673Odourless,colourless,tasteless

Asphyxiating Normal air, strata

Carbondioxide

CO2 1.5291Odourless,

colourless, slightacid taste

AsphyxiatingBreathing, fire,

combustion,explosion

0.5

Methane CH4 0.5545Odourless,colourless,tasteless

Asphyxiating,explosive

Blasting, dieselengine, organic

decay 5-15

Carbonmonoxide

CO 0.9672Odourless,colourless,tasteless

Asphyxiating,explosive

Blasting, fire,incompletecombustion

0.005 12,5-74

HydrogenSulphide

H2S 1.1912

Rotten eggodour,

colourless, acid

taste

Irritant,poisonous,explosive

Strata water, blasting

0.001 4-44

Sulphurdioxide

SO2 2.2636Irritating odour,colourless, acid

taste

Irritant,poisonous

Diesel engine,combustion ofsulphide ore

0.0005

Nitrogenoxide

NO, NO2,N2O

1.5895

Distinct smell,reddish browncolour, bitter

taste

Irritant,poisonous

Blasting, dieselengine,

incompletecombustion

0,0005



Prevention of Exposure

Exposure ofpersons tomine gases

Preventionof

formationof gases

Preventionof

exposureof persons

Removal

of gases

Dilutionof gases



Carbon Monoxide

Poisonous even in low concentration, andaccumulative in blood

Explosive when its content inthe air reaches 12.5% - 74%



Carbon dioxide

Increasing quantity of CO2, is caused by :

Gas from coal seam, mine fire, blasting, engine emission, coaloxidation, acid water reaction to carbonate rocks.

Effects of over-quantity of CO2:0.5%, increasing respiratory 3.0%, respiratory rate becomes 2x normal condition5.0%, respiratory rate becomes 3x normal condition10.0%, humans can only last several minutes



Control of Gases from Blasting

t

AN Q

20

It was indicated that the fumes extend to a distanceof about 20 m from the face (Szechy, 1976).

Volume flowrate of

fresh airrequired,

m 3/s

Crosssectionalarea of tunnel

Numberof times

air is to beexchanged

Time withinwhich the

fumesshould bediluted

For rapid diffusion, air velocity in the tunnel is within range 0.7 – 1.0 m/s



Control of Exhaust Emission

Principal Pollutants ConcentrationCarbon dioxide 100,000 ppm

Carbon monoxide 2,000 ppm

Nitric oxide 900 ppm

Nitrogen dioxide 100 ppm

Sulphur dioxide 215 ppm

aTLV

e

cc

qc

Q

Volume flowrate of

fresh airrequired,

m 3/s per kW

Concentrationof gas, ppm

Exhaustquantity,

m 3/kW

TLV of gas, ppm Ambientconcentration

of gas in normalair, ppm

The ambientconcentration of

carbon dioxide andcarbon monoxideare 2,000 ppm and10 ppm

Kuliah 3 - Mine Gases

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