TYPES OF VENTILATION SYSTEMS IN MINES - CENTRAL BOUNDARY U W Z
- 1. Indian Institute of Technology Banaras Hindu University Varanasi Central, Boundary, U, W and Z ventilation systems Submitted by: Kudire Anil Kumar (16152008) M.Tech Part I Dept of Mining Engineering IIT(BHU), Varanasi Uttar Pradesh Subject: Mine Environmental Planning
- 2. TYPES OF VENTILATION SYSTEMS Depending on the relative position of intake and return airways, ventilation systems in mines can be broadly divided into the following 1) Boundary or Unidirectional 2) Central or Bi-Directional 3) U 4) W 5) Z
- 3. The system is commonly adopted in in-the seam of coal mines where both intake and return shaft are located close by at the centre of the property . Intake and return air from any district travel in opposite directions through parallel roadways usually separated by stopping erected in the cross-section between them . Also return air from a district has to cross the intake in order to join the main return.
- 4. Fig : Central Ventilation
- 5. Fig : Bord and Pillar (Central Ventilation)
- 6. Advantages of central ventilation system 1.The deposit can be worked after short development leading to a quicker start of production. 2.Long development headings are not necessary and hence there is no associated problem of their ventilation. 3.Central pits cause less loss of minerals in shaft pillars.
- 7. sinking of deep pits close together economizes the cost of sinking as certain common facilities can be shared by the pit. On the other hand , boundary pit which are far off necessitate building of road, extension of power lines etc to the sinking site involving extra cost.
- 8. Obviously the central ventilation system allows a substantial leakage because of the number of stopping and air crossing used so that volumetric efficiency is only 40-50% with this system . Disdvantages of central ventilation system
- 9. • In boundary ventilation system, the air flows in unidirectional from the intake to the return through the workings. Fig : Boundary Ventilation (Exhaust fan)D
- 10. Fig : Boundary Ventilation (Forcing fan) • It is commonly adopted in metal mines, where the intake and return shafts are located at the strike boundaries of the mine. • It is the most efficient system necessitating the least use of ventilation control devices and thus resulting in a high volumetric efficiency of ventilation (70-80%).
- 11. D Fig : Boundary Ventilation
- 12. • 1. the boundary ventilation system necessitates the minimum use of ventilation control devices. This apart form saving the capital invested on them as well as the cost of their operation and maintenance, reduces leakage and result in a high volumetric efficiency. It necessitates the minimum use of ventilation control devices. This apart form saving the capital invested on them as well as the cost of their operation and maintenance, reduces leakage and result in a high volumetric efficiency. Different sections of the mine can be independently ventilated by separate fans. There is greater safety because of larger number of outlets to the surface.
- 13. Disadvantages of the boundary ventilation system Separate fan installations increase the cost of their operation ,supervision and maintenance.
- 14. "U Ventilation" where intake air comes in the maingate and returns in the tailgate; there is no connection to any airways behind the face line. If a longwall advancing face is ever used, this is the only means of ventilation available. Face advance GOAF MG TG
- 15. “W Ventilation” is adopted in longwall double unit face where air enters from both the tailgates and leaves from the common maingate for each longwall panel. Face advance GOAF GOAF Face advance MG TG TG
- 16. GOAF "Z or Y Ventilation" where both main and tailgates carry intake air and all the return air is carried to main returns behind the face. TG MG Face advance
- 17. There are other possible variations, especially if more roadways are available at each end of the face, and there can be special cases where layouts are not quite normal, however the majority of faces use one of the above arrangements. For U ventilation, the air flow across the face itself is from main to tail (in the opposite direction to the coal flow and sometimes referred to as as "antitropal" ventilation). For Z ventilation the flow is from tail to main (or "homotropal"). If Uni-di cutting is used the air flow direction will govern the direction of cutting.