共查询到20条相似文献,搜索用时 546 毫秒
1.
几内亚红土型铝土矿床地质特征 总被引:3,自引:0,他引:3
几内亚铝土矿资源丰富,并具有品位高,富铝、高铁、低硅、易采、易选之特点,属富含三水铝石的红土型铝土矿.硅铝铁风化壳是本区的含矿岩系,主要矿石类型为蜂窝状、土状和块状铝土矿.矿体多赋存于山体顶部和坡度适中的斜坡上,地形平坦地段和沟谷部位矿体质量差或无矿体.几内亚属于湿热多雨和干湿交替的热带气候,为红土型铝土矿的形成提供了有利条件.广泛分布的富铝基性岩石是铝土矿的母岩,也是形成铝土矿的基本前提. 相似文献
2.
3.
4.
为减少煤炭损失,提高煤炭采出率,在赵家庄煤矿1206工作面运输巷采用窄煤柱沿空掘巷方式。为确定合理的窄煤柱宽度,利用FLAC~(3D)数值模拟软件对不同煤柱宽度下的巷道围岩变形量进行模拟分析,结合极限平衡理论计算结果,确定沿空掘巷窄煤柱宽度应为6 m。 相似文献
5.
涉核地下硐室群核事故产生的钚气溶胶威胁核设施的长期运营安全,现有关于封闭空间内的钚气溶胶扩散行为研究主要涉及简单硐室,而未涉及复杂地下硐室群,复杂地下硐室群核事故钚气溶胶扩散行为尚未得到充分揭示。首先对核事故钚气溶胶源项进行分析,讨论了钚气溶胶颗粒产生的方式和粒径分布特征,给出了硐室内钚气溶胶初始浓度的估算方法;然后通过分析钚气溶胶颗粒的空气动力学行为,给出了适合于描述钚气溶胶颗粒在硐室内传输的本构模型,建立了地下硐室群内钚气溶胶扩散行为模拟方法;最后以某复杂地下硐室群为例,采用Ventsim软件对两种释放场景(缓慢释放和剧烈释放)、不同释放位置条件下钚气溶胶的扩散行为进行了数值模拟,并对硐室群核事故应对措施展开了讨论。结果表明:钚气溶胶在硐室群内的扩散行为主要受核泄漏方式、核泄漏位置、钚气溶胶颗粒粒径以及通风系统的影响,通过合理规划硐室群布局、通风风路、防核泄漏措施等,可有效降低核污染扩散的风险。该研究结果对于地下硐室群核安全设计、核应急处理与核扩散风险管控等措施的制定具有一定的参考价值。 相似文献
6.
目的 研究车辆转向桥前梁在受损情况下的极限承载规律。方法 对转向桥前梁在破片高速侵彻作用下的破坏结果进行数值模拟研究,确定破片正侵彻转向桥前梁不同部位时的侵彻弹道。对含侵彻缺陷的转向桥前梁承受垂直载荷能力进行数值模拟研究。结果 确定了破片正侵彻转向桥前梁不同部位时的侵彻弹道约为圆形通孔。对于直径为1 cm的圆孔缺陷,当位于非易损区时,前梁达到极限承载时在易损区发生断裂,其极限承载能力约为无缺陷时70%;位于易损区时,前梁达到极限承载时裂纹会经过圆孔,其极限承载能力约为无缺陷时60%。以某典型车辆为例,计算得到前梁易损区圆孔缺陷直径超过1.8 cm时,前梁会在车辆的自重下发生塑性屈服。结论 转向桥前梁部件极限承载能力受缺陷尺寸和位置的影响,缺陷尺寸越大,前梁极限承载能力越小。当缺陷位于易损区时,前梁极限承载能力比同尺寸缺陷位于非易损区时更小。该结果可为转向桥功能失效分析提供参考依据。 相似文献
7.
8.
9.
山区高速公路在建设过程中,隧道洞口的开挖往往易造成古滑坡的复活或部分复活,并形成新的滑坡灾害。为了保证隧道进洞口施工的顺利进行,隧道洞口边坡的稳定性动态分析尤为重要。本文结合栗石沟隧道进洞口边坡工程实例,利用FLAC3D软件分别对该边坡在自然状况、坡脚开挖+坡面削坡2m以及坡脚开挖+坡面削坡2m+隧道开挖13m三种工况下的稳定性状况进行了数值模拟分析,并通过分析三种工况下的边坡稳定性系数、边坡剪应变增量变化及塑性区破坏情况,探讨了其剪应变的变化特点和塑性区破坏的规律,以验证边坡削坡卸载方案在隧道施工中的安全性和可靠性。 相似文献
10.
11.
Life cycle assessments of the mining and mineral processing of iron ore, bauxite and copper concentrate were carried out, focussing on embodied energy and greenhouse gas emissions. The results showed that loading and hauling make the largest contributions to the total greenhouse gas emissions for the mining and processing of iron ore and bauxite. In the case of copper ore, the crushing and grinding steps make the largest contribution to the total greenhouse gas emissions for the production of copper concentrate. These results indicate that efforts to reduce the increased greenhouse gas emissions from mining and mineral processing, anticipated in the future as a result of falling ore grades and more finer-grained deposits, should focus on loading and hauling for iron ore and bauxite, while for copper ore the focus should be on grinding. There are a number of new and emerging technologies that could be expected to assist in this task, and these include high pressure grinding rolls and stirred mills for grinding, and further advances in diesel engine technology for loading and hauling applications. 相似文献
12.
13.
以青溪大桥桥基岩溶洞穴围岩工程地质条件定性-半定量-定量分析为基础,在岩土自重和桩基的外附荷载作用下,对桥墩所在位置的溶洞顶板稳定性进行综合评价。利用自行研制的钻孔多点位移计对施工荷载施加过程中溶洞及项板岩体的变形进行现场监测,该仪器综合了传统多点位移计和收敛计对深部岩体和岩层表面分别进行监测的优势,利用同一组数据对施工影响下溶洞洞体和顶板的变形规律进行分析。结果表明,在重大施工荷载作用下保证8.0 m溶洞顶板厚度是安全稳定的,大大节约了溶洞处理费用,并为类似的岩溶洞穴稳定性施工提供了有力的技术支持。 相似文献
14.
Mining is a water intensive activity, and reducing water consumption is a key requirement in moving toward a more sustainable mining industry. This paper identifies mine water reduction, reuse and recycle options, and demonstrates cases where these options have been implemented around the world. A mine water system model is developed and used to show potential water saving strategies through six scenarios. Apart from the base case, these scenarios include the introduction of evaporation reduction strategies, paste tailings disposal, filtered tailings disposal, ore pre-sorting and a combination of the most effective options. The results of the modeling show how an open-pit copper mine with a traditional layout can move from having an average water withdrawal of 0.76 m3/t of ore processed to 0.20 m3/t of ore processed or lower. A key result of the modeling is the discovery that a combination of ore pre-concentration and filtered tailings disposal can reduce water consumption by 74% or more. This finding demonstrates an opportunity to significantly lower water consumption on mine sites. 相似文献
15.
《Journal of Cleaner Production》2003,11(7):753-765
This article assesses solid and hazardous wastes that would be generated through the production of new, lightweight, fuel-efficient vehicles. In these vehicles, steel is replaced with aluminum, titanium, magnesium, plastics, and glass and carbon fibers. In addition to total volumes, we pay particular attention to a subset of highly toxic chemical constituents in hazardous waste. The article also examines capacity in the United States to manage the solid and hazardous waste generation changes. Finally, we review the distribution of environmental impacts that changes in material composition would cause. The estimated generation of solid and hazardous wastes for each of the three new vehicles is greater than wastes for a base vehicle, although the United States has sufficient waste management capacity to handle these increases. Production of a subset of chemical constituents of hazardous waste, specifically those that are highly toxic, will decrease in most cases for the three new vehicles. Moving to these new materials could reduce mining for iron ore in the United States but increase the mining of bauxite for aluminum, magnesium, titanium, and other materials in such major countries as Canada, China, and Russia and in many small, developing countries, such as Guinea, Jamaica, and Sierra Leone. 相似文献
16.
17.
为考察城市不同下垫面降雨径流中颗粒粒径分布及与污染物的关系,2020年7—8月在相同降雨条件下对天津市某居民区油毡屋面、塑钢屋面、水泥瓦屋面和沥青路面的6场降雨事件进行采样,分析降雨径流污染特征及颗粒物分布. 结果表明:①沥青路面降雨径流中悬浮颗粒物(suspended solids, SS)浓度最高,与油毡屋面、塑钢屋面和水泥瓦屋面径流SS浓度在统计上有显著差异(P<0.05);②不同下垫面降雨径流中颗粒物粒径主要分布在10~200 μm之间,4种下垫面中值粒径(D50)浓度在计量上均有显著差异(P<0.05);③粒径在10~50 μm的颗粒物占比最大,在油毡屋面、塑钢屋面、水泥瓦屋面和沥青路面径流中占比分别为30.95%、25.53%、30.41%和50.47%,粒径大于300 μm的颗粒物体积分数占比最小;④降雨径流中颗粒物是污染物的主要载体,径流中化学需氧量(COD)和总磷(TP)主要以颗粒态形式存在,而总氮(TN)主要以溶解态形式存在. 通过对降雨径流中颗粒物粒径分布和污染物赋存形态的研究,以期为城市径流污染控制及雨水净化方法的选取提供数据支撑. 相似文献
18.
19.
20.
以抚顺西露天矿为研究区,利用GMS (groundwater modeling system)数值模拟软件在分析矿区及其周边区域地质及水文地质条件的基础上,针对地层岩性和地质构造特点,建立数学模型;结合工作区地质勘探资料及对充水因素的分析,建立水文地质模型,对涌水量作出预测,提出平衡状态时排水井的布置方案。结果表明:根据矿坑的地形特点分别在南北两侧安置5口深度为100 m,长度为100 m,排水量为10~20 m3/d的水平井,并且在模拟区矿坑最低处按照100 m的间距安置4口深70~100 m,排水量为20 m3/d的竖井时,矿坑中不会有水溢出。 相似文献