JNTU
JNTU B.Tech II MINE ENVIRONMENTAL ENGINEERING - I Previous Question Paper (December - 2018 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
(25 Marks)
Mention the various sources for CO gas in mines.
Answer
Carbon monoxide (CO) in mines primarily originates from the following sources:
- Incomplete combustion of organic materials, such as coal or timber, during mine fires or spontaneous heating.
- Explosives used in blasting operations, which produce CO as a byproduct of detonation.
- Exhaust emissions from diesel-powered machinery and equipment operating underground.
- Oxidation of coal at low temperatures, which can release CO into the mine atmosphere.
What are the Physiological effects on workers when they are exposed to different percentage levels of CO2 in mines?
Answer
Carbon dioxide (CO2) is a non-toxic but asphyxiating gas that affects the human respiratory system by displacing oxygen and stimulating the respiratory center in the brain. Its physiological effects depend on the concentration levels:
- 0.5% to 1.0%: Prolonged exposure may lead to a slight increase in the breathing rate and depth, though it is generally considered the threshold for long-term occupational exposure.
- 2.0% to 3.0%: Workers experience noticeable respiratory distress, including panting, increased heart rate, and headache. Physical exertion becomes significantly more difficult.
- 5.0% and above: This level causes severe dyspnea (labored breathing), dizziness, confusion, and potential loss of consciousness. At concentrations exceeding 10%, death can occur rapidly due to acute asphyxiation and respiratory failure.
Define Relative, Specific and Absolute humidity.
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Write short note on equivalent orifice.
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What is natural ventilation?
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List various artificial aids to natural ventilation.
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What is Ascensional and Descensional Ventilation?
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Explain how to match duct size with auxiliary fan for providing ventilation at face.
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What are the different types of ventilation survey?
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What are the various quality and quantity measuring instruments?
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Part B
(50 Marks)
Explain Graham’s ratio and its importance.
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Explain in brief analysis of mine air using orsat apparatus with neat sketch.
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Sample of air collected in the intake and return gates of advancing longwall face show 0.2% and 0.7% CH4 respectively. Calculate the methane emission per ton of coal and also comment on the degree of mine, if the production from the face average 1000 ton per day and air quantity of 20 m3/s circulate along face.
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Write short note on methane layering.
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What are the various effects of heat and humidity on mine workers?
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What is air cooling power? How to measure cooling power of air using kata thermometer.
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Calculate relative humidity at face in a mine having DBT 28°c and WBT 23°c.
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Explain methods to improve cooling power of mine air.
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Discuss in detail the auxiliary ventilation and importance of their installation in mines.
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What is the purpose of reversing ventilation? Explain the procedure and method of reversal of ventilation?
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Draw neat layouts showing central and boundary ventilation of bord and pillar mine.
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What are the differences between evasee and diffuser?
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Explain with neat sketches types of auxiliary ventilation.
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Explain the two laws involved in ventilation network analysis with neat sketches.
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Explain how do you determine air quantity for a new mine.
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In the ventilation network shown in figure, a differential pressure of 1500 Pa is acting across the circuit and a natural ventilation pressure of 300 Pa is acting in the direction of airflow within mesh ABEFA. A regulator R is constructed in the right most branch of the network to limit the airflow in that branch to 20m3/s. The resistances of all the airways in Ns2/m-8 are indicated beside the network. Calculate the airflow in different branches of the network.
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