4. To ensure the mining level to ha

4. To ensure the mining level to have sufficient reserves and reasonable service lifeThis is the most important part of horizontal division. For a mine with an annual design output of 3 million ta, the first level of service should be not less than 30 years.5. Level height is economically advantageousFrom the point of view of the unification of technology and economy, technically reasonable horizontal vertical energy can obtain better economic effect. Favorable horizontal vertical height can be selected through economic comparison method. Economic comparison items include: development work volume and excavation cost, shaft maintenance cost, coal lifting cost, drainage cost, etc. In case of different types and parameters of roadway layout in mining area, roadway excavation, maintenance and transportation cost of coal in mining area should also be compared. According to the comparison results, factors such as technology, management and safety are comprehensively considered.