西石门铁矿北区高应力破碎矿体崩落法开采技术

西石门铁矿北区新探矿体为缓倾斜破碎厚-中厚矿体，且地压显现严重，属于极度难采矿体。矿山采用无底柱分段崩落法开采，开采中存在设备运行不畅、采场结构不稳、巷道破坏严重等问题。为缓解高应力破碎条件带来的开采问题，从设备选型、采场结构参数确定、巷道布置方式及回采顺序、支护措施等方面对回采技术进行了改进。在确保设备运行顺畅的前提下，确定了软弱围岩条件下铲运设备需由1.5 m³增大至2 m³，巷道断面尺寸应由3 m×3 m增大至3.2 m×3.1 m；综合考虑巷道稳定性、矿体条件、凿岩能力、满足放出体发育等条件，确定了采场结构参数为分段高度13 m、进路间距12 m；以适应地压活动规律为原则确定了回采进路以垂直走向布置为佳，开采顺序为从已采矿体边界向上盘退采；分析了地压严重以及开挖后易短时间冒落的围岩支护要求，提出了超前锚杆+U型钢拱架的支护措施；根据散体流动参数确定了最小边孔角为50°，根据出矿口废石的出露位置将崩落步距调整为1.6 m。上述参数和支护措施在西石门铁矿北区高应力破碎矿体开采过程中得到了成功应用，增强了无底柱分段崩落法开采该类矿体的适用性。

Caving Mining Technology for High Stress Fractured Orebody in the Northern Mining Area of Xishimen Iron Mine

The new prospecting orebody in the northern area of Xishimen Iron Mine belongs to gently inclined，fractured and thick to medium thickness orebody with serious ground pressure，which is extremely difficult to mining.Pillarless sublevel caving mining method is adopted in the mine，problems such as poor operation of equipment，instability of stope structure and roadway failure seriously are existed during the mining process.In order to alleviate the mining problems caused by high stress and fragmentation，the mining technology is improved from the aspects of equipment selection，determination of stope structural parameters，roadway layout，mining sequence and support measures.On the premise of ensuring smooth operation of equipment，it is determined that the scraper should be increased from 1.5 m3 to 2 m3 and the roadway section size should be increased from 3 m×3 m to 3.2 m×3.1 m under the condition of weak and soft surrounding rock；the section height is 13 m and the route spacing is 12 m which are determined by considering the stability of roadway，orebody conditions，rock drilling capacity and the development of discharge body；based on the principle of adapting to the law of ground pressure activity，it is determined that the mining route is better laid out vertically and the mining sequence is better to withdraw from the boundary of the orebody to the upper wall；supporting requirements of the surrounding rock with large ground pressure and easy to fall in a short time after excavation are analyzed，and the supporting measures of advanced bolt and U-shaped steel arch are proposed；the minimum side hole angle is 50°，which is determined according to the flow parameters of bulk，and the caving step is adjusted to 1.6 m according to the outcropping position of waste rock at the ore outlet.The above parameters and support measures have been successfully applied in the mining process of high stress fractured orebody in the northern area of Xishimen Iron Mine，therefore，the applicability of mining such orebodies of sublevel caving mining method without bottom pillar is enhanced.