JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III MINE ENVIRONMENTAL ENGINEERING – II Previous Question Paper (August/September - 2024 - R18)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks.
Part A
What are the control measures of spontaneous combustion of mines?
Answer
- Preventative Measures: These focus on minimizing air leakage into goaf areas. This is achieved through the use of high-quality ventilation seals, pressure balancing techniques, and the systematic extraction of coal pillars to reduce residual coal left in the goaf.
- Monitoring and Detection: Continuous monitoring of mine atmosphere for indicators such as carbon monoxide (CO) levels, the Graham's ratio (CO/O2 deficiency), and temperature increases in return airways helps in early detection of heating.
- Inertization: Injecting inert gases like nitrogen (N2) or carbon dioxide (CO2) into the goaf or sealed areas to displace oxygen and suppress the oxidation process.
- Sealant Application: Application of chemical sealants or fire-resistant coatings on coal ribs and roof to prevent oxygen diffusion into the coal face.
- Hydraulic Methods: Use of water infusion or high-pressure water curtains to cool down hot spots and saturate the coal mass, thereby reducing its reactivity.
- Strategic Planning: Adopting panel-based mining systems to facilitate rapid isolation of affected areas using fire-resistant stoppings or explosion-proof seals in case of an emergency.
List the theories of spontaneous combustion, explain combustion.
Answer
- Theories of Spontaneous Combustion: The primary theories explaining the initiation of spontaneous heating in coal seams include:
- Pyrite Oxidation Theory: Suggests that the oxidation of iron pyrites (FeS2) present in coal generates heat, which subsequently triggers the oxidation of coal.
- Bacterial Theory: Proposes that the action of certain bacteria on coal constituents generates initial heat, though this is considered less significant in modern mining contexts.
- Coal Oxidation Theory (The Adsorption Theory): The most widely accepted theory, which posits that coal has a natural affinity for oxygen. Oxygen molecules are adsorbed onto the coal surface, forming an unstable oxygen-coal complex. This exothermic reaction releases heat, which increases the coal temperature, further accelerating the rate of oxidation in a self-sustaining cycle.
- Explanation of Combustion: Combustion is a rapid exothermic chemical reaction between a fuel (such as coal) and an oxidant (typically atmospheric oxygen). For combustion to occur, the Fire Triangle must be satisfied: the presence of fuel, oxygen, and sufficient heat to reach the ignition temperature. In the context of spontaneous combustion, the process begins as slow, low-temperature oxidation. If the heat generated by this oxidation is not dissipated by ventilation, the temperature rises, accelerating the reaction rate exponentially until the coal reaches its ignition point, resulting in visible fire or smoldering.
What are the advances of firefighting techniques?
Answer
Sign in to view the complete answer paper.
What are the causes of firedamp explosion?
Answer
Sign in to view the complete answer paper.
How mine dust will be produced?
Answer
Sign in to view the complete answer paper.
What are the stone dust barriers?
Answer
Sign in to view the complete answer paper.
What are the causes of mine inundation?
Answer
Sign in to view the complete answer paper.
How noise levels will be prevented?
Answer
Sign in to view the complete answer paper.
How cap lamp can be maintained?
Answer
Sign in to view the complete answer paper.
What are the principles of risk management?
Answer
Sign in to view the complete answer paper.
Part B
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.
Describe various methods adopted to combat fires and explain their advantages and disadvantages.
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.
What are the factors to be considered, precautions have to be taken in while reopening of sealed-off areas?
Answer
Sign in to view the complete answer paper.
Describe assessment and control of mine dust and their associated hazards.
Answer
Sign in to view the complete answer paper.
What are the causes of mine dust explosion, explain prevention and reduction of noise levels.
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.
Answer
Sign in to view the complete answer paper.