Simultaneous Effect of Convergence and Reducing Slope of Chute Construction on the Economic of the Plan and Cavitation Index (Case Study: Daharan Dam)

The Daharan Dam, like other dams, is subject to concrete surface wear or cavitation in the chute structure. This article looks into the concurrent effects of decreasing the chute angle and slope profile changes from a single slope to a double slope and the simultaneous latitudinal convergence of the chute structure on the cavitation index and the economy of project. In order to perform this research, the geometric specifications were collected of the dam, and the chute structure as well as those of a flood with a return period of 1000 years, which make up the basis of the spillway design. Taking advantage of the numerical WS77 model, different modes were simulated with a single slope, double slope with fixed latitude, double slope with latitudinal convergence, and the cavitation index and the excavation volumes for each option were calculated. The results indicated that a decrease in slope led to a rise in the cavitation index to over 1.2 and that the convergence of the chute structure positively affected the increase in the cavitation index.

Impact of an artificial chute cutoff on the river morphology and flow structure in Sipaikou area of the Upper Yellow River

Artificial chute cutoff can fundamentally eliminate the threat of flood caused by the meandering river,but it significantly changes its morphodynamic characteristics.Channel adjustments after cutoff are rapid,which makes it difficult to study the interaction between river morphology and flow structure only through field measurement.However,numerical simulations can provide insights into the hydrodynamic characteristics after artificial chute cutoffs.In this study,both field measurement and numerical simulation are employed to investigate the flow structure and bed morphology caused by an artificial chute cutoff in Sipaikou area of the Upper Yellow River in 2018.The measured hydrological data provide boundary conditions and initial values for the numerical model.The field measurement results reveal that the concave bank of the study area is severely scoured up to 270 m after the artificial cutoff,and a 20 m deep scour hole and a 2.26 km long pool are formed at the entrance and near the left bank of the chute channel.The numerical simulation results of velocity at typical cross-sections are in good agreement with the measurement results.Flow separation and stagnation zones are observed near the right bank during the low flow conditions(discharge of at least 902 m^(3)/s),but this phenomenon is not seen during larger flow conditions(discharge exceeds 2000 m^(3)/s).Interestingly,flow recirculation zones are also found near the left and right banks of the scour hole.Further,a long flux belt is formed at the scour hole and the pool.Consequently,the impact of the bed topography on the hydrodynamic characteristics is relatively prominent when the discharge is small,while the impact on the river banks and river bed is more noticeable when the water discharge is large.In addition,high shear stress is observed near the left bank at the downstream of the studied area,which indicates that the left bank at the downstream is still being scoured.These results suggest that bank protection measures along the left bank are required to maintain the effectiveness of the artificial chute cutoff.

Particulate flow analysis in inclined pipes and transfer chutes using tomography imaging,discrete element simulations and continuum modeling approaches

In particulate material transfer systems,traditional shear test based steady state analysis can provide some insight into the strength of the bulk material and subsequent resistive frictional forces during flow.For fast flowing transfer points,dynamic flow conditions dominate and additional modelling techniques are required to improve design guidance.The research presented shows the evolution of a design solution which utilises two distinct processes;a continuum method and a discrete element method(DEM). Initially,the internal structure of dense granular flow,down vertical and inclined pipes was investigated using a twin sensor,12 electrode electrical capacitance tomography device.Subsequently,DEM simulations were conducted using the commercial software,PFC3D.Initially,two particle types and their flow behaviours were analysed:plastic pellets and sand.The pipe angle was varied between 0°and 45°to the vertical.For both the plastic pellets and the sand,good qualitative agreement was found with the spatial particle concentration analysis.Generally,the flow had a dense particle region at its core with the particle concentration reducing away from this core.As expected,at 0°, the core was centrally located within the pipe for both the plastic pellets and sand.At pipe angles 5°or greater,the dense core of particles was located on or near the pipe wall.Average flow velocity analysis was also conducted using the results of wall friction test analysis.The velocity comparisons also showed good agreement between the ECT image analysis and the DEM simulations. Subsequently,the DEM method was used to analyse a complex transfer system(or chute) with the continuum method providing comparative flow analysis with the DEM flow analysis.

Investigation on the Structure of Chute-feed and Card Auto-leveller and Their Selection of Technological Processes

Based on the structure of chute - feed and autoleveHer, an analysis of their working principle and the verification of their practical production results have been carried out. Finally, the future investigation direetiom of chute - feed and card autuleveller are put forward.

溢洪道弯道段流态改善试验研究和应用

溢洪道泄槽弯道泄流时,弯道段内易产生横向冲击波,水流紊乱,流态较差,会不同程度地影响溢洪道的正常运行。该文根据广东省部分水库陡槽溢洪道水力模型试验研究成果,介绍改善溢洪道泄槽弯道段流态的断面超高、斜向高低坎、纵向导流墙、阶梯跌坎、弯道前设置消力池等工程措施,并对各种工程措施的适用性进行分析,研究成果可供类似工程设计和运行参考。

储煤筒仓内钢制螺旋溜槽脱落事故分析

螺旋溜槽是块煤仓防碎的重要手段,但在其应用过程中,事故的发生却屡见不鲜。针对某储煤筒仓内钢制螺旋溜槽脱落事故,在现场踏勘的基础上,通过检测、有限元分析和理论计算,分析了钢制螺旋溜槽脱落的原因。结果表明:荷载取值不当是造成此次事故的直接原因,而框架和溜槽结构选型和连接构造不合理是间接原因。溜槽支架宜采用多边形框架结构,也可加设框架间支撑体系;其结构宜选用底板宽度较小的U形或L形;计算时,应取溜槽底板投影一个螺距范围内的全部贮料重力且应考虑放料时的动压;螺旋溜槽计算模型应按空间螺旋曲梁计算,并充分考虑扭矩的影响。

服役环境下动车车底装备滑槽疲劳载荷谱的编制与验证

随着动车组向更高速度发展,对列车轻量化的需求愈发迫切。在现有的动车组平台中,将没有横梁底架的车体改为底架滑槽吊挂能够显著减轻设备框架的质量和体积,实现列车轻量化目的。然而,滑槽吊挂引起的最为关切的问题是结构的疲劳强度能否满足需求。为了了解结构的疲劳强度性能,基于服役中动车组车下设备振动加速度,结合现有标准体系,采用服役全周期内工况组合和载荷外推方法,采用累积损伤原理和疲劳试验加速法,编制107次循环次数下的等效振动幅值,并开展滑槽结构疲劳强度试验。研究结果表明:与既有标准体系相比,考虑服役环境的车下设备垂向载荷小于标准值,横向和纵向载荷大于标准值;当轻量化高速动车组大质量车下设备采用滑槽吊挂方式时,结构可以满足30年设计寿命要求。

湿陷性黄土地区明渠陡槽加墩消能工优化试验

明渠陡槽加墩是一种高效消能工布置方式,在特定条件下具有很高的技术竞争优势,但目前国内相关研究甚少。针对甘肃庆阳小崆峒沟雨水下塬排放工程的明渠陡槽加墩段进行了1∶30大比尺水工模型试验研究,试验发现初步方案沿程水流流态不稳定,存在向外泼溅溢出现象,危及黄土边坡的结构稳定。为此对初步方案进行了优化研究,试验发现,通过缩短消能墩排距,可以显著减小水面波动,使沿程水深分布均匀,流速降低,沿程不再出现水流向外泼溅溢出现象。消能墩排距由H/i缩短至0.5H/i后,在最大设计流量工况下,水面波动减小72.5%,平均流速降低40.1%,总消能率由87.9%提高至94.6%。

高深溜井矿石阶段性流动规律对溜井生产的影响

基于对高深溜井生产实践的长期观察,归纳总结出矿石在高深溜井中的流动规律,提出垂直全断面阶段性流动是高深溜井区别于短溜井特有的工程现象。运用散体材料结构自组织力链和搭拱效应理论,分析了井筒内矿石阶段性流动产生的原因,揭示了高深溜井矿石阶段性流动对溜井生产过程中常见的滞流、堵塞、磨损和片帮现象以及溜井内矿石的混合和分级的影响;分析了溜井内空气气流对散体流动的影响,在正常放矿过程中,流动气体的存在有利于矿石流动和临时平衡拱的破坏;同时,由于受气体的曳力作用,溜井内矿石产生块、粉分级集中现象,助推了井筒内矿石的滞流和堵塞。研究提出矿石的粒级成分、密度、含水量、黏结性及溜井直径、井壁粗糙程度是造成溜井滞流和堵塞的基础因素,垂直全断面阶段性矿石流动特性是造成高深溜井滞流和堵塞的重要原因。

Effect of cross-section shape of rotating chute on particle movement and distribution at the throat of a bell-less top blast furnace

Rotating chutes are widely used to control the burden distribution and enhance the gas distribution in a blast furnace.The chute cross-section shape has a significant effect on the particle movement and distribution.Therefore,this study developed a three-dimensional model of a blast furnace top with rotating chute using the discrete element method.The effect of different chute shapes on the particle movement and radial burden distribution was then investigated.The results showed that the burden stream height at the chute discharge agrees well with the burden stream thickness at the burden surface.A semicircular chute had the largest main striking point,where the chute discharge joins the burden surface,and trapezoidal and rectangular chutes had successively smaller MSPs.The semicircular chute helped to obtain a uniform radial size distribution.The trapezoidal chute helped form an aggregated burden stream at low rotating speeds,while the rectangular shape chute achieved this at higher rotating speeds and different chute angles.

Effect of Chute Rotation on Particles Movement for Bell-less Top Blast Furnace

For the bell-less top blast furnace, when particles move along the chute, the particlesr motion direction and the frictional force acting on them will change due to the chute rotation, which consequently influences the velocity at the tip of chute, changes the burden flow width and impact point, and finally affects the stock profile and gas f[ow distribution. So the influence of chute rotation needs to be considered when calculating the burden trajectory with a mathematical model. The mathematical model was established to analyze the influence of Coriolis force on particle velocity at chute tip as well as height and width of burden flow in chute, and to summarize the effect of Coriolis force on burden distribution, thereby making the calculation result more accurate.

难选氧化锑矿工艺矿物学及选矿回收

采用X射线荧光光谱分析、化学多元素分析、X射线衍射分析、电子探针分析对某氧化锑矿进行工艺矿物学研究,结果表明原矿中锑的含量仅为1.21%,含锑矿物为锑华、辉锑矿,脉石矿物为石英,并且原矿性脆、易泥化,属低品位难选氧化锑矿。在工艺矿物学研究结果的基础上开展对该矿的回收探索试验。采用分级—重选法对矿石进行选别,首先将原矿分级后获得+74μm和-74μm两种产品;对+74μm粒级产品采用磨矿—螺旋溜槽粗选—摇床精选的分选工艺流程进行处理,其中用螺旋溜槽选别-74μm占比为28.03%的原矿,获得的螺旋溜槽粗精矿中Sb品位2.01%、Sb作业回收率28.49%,在此基础上用摇床对螺旋溜槽粗精矿进行精选获得Sb品位6.03%、Sb作业回收率56.90%的摇床精矿;对-74μm粒级产品用悬振锥面选矿机进行选别,获得Sb品位4.87%、Sb作业回收率26.12%的锑精矿。在合适的磨矿细度下,通过多级重选以及多种重选设备的组合,可有效回收该氧化锑矿中的含锑矿物。研究结果可为该难选氧化锑矿的综合回收提供参考。

End wall effect on particle motion in a chute flow

The influence of the end wall of a chute on the rotation of internal characteristic particles is mainly on the z-axis.A measurement device based on inertial measurement technology does not require the assistance of external information;hence,it is especially suitable for measuring the angular and translational velocities of internal characteristic particles.To study the influence of the end wall of the chute on the motions of the internal characteristic particles,the z-axis rotational and translational velocities of the internal characteristic particles in the chute were measured,and it was found that the rotational velocity about the z-axis differs according to the initial position.The z-axis angular velocity of a characteristic particle at the centre fluctuates near 0,and the average value approaches 0.The z-axis angular velocity of a characteristic particle at the left end wall is typically negative.This phenomenon is due to the influence of the end wall on the rotational motions of particles with initial positions that are near the end wall.In addition,the average translational velocity of the characteristic particles is also affected by the end wall.The distributions of the average z-axis angular velocity and the average translational velocity are quantitatively analysed,and the correlation between the tilt angle of the chute and the end wall effect is studied.

煤锁加料溜槽的工艺制造技术研究

本文对煤锁加料溜槽的制造工艺及工艺流程方案进行了分析研究,介绍了煤锁加料溜槽的结构特点、工艺技术及制造难点,为制造运动类部件产品积累了经验。

李官集铁矿溜井三维激光扫描测量及稳定性分析

溜井是矿石运输的主要通道,溜井内部的精细测量是评估井筒健康的重要步骤。为精细测量李官集铁矿0 m中段8#采场溜井内壁的破损情况,通过翼目神HM100型三维激光扫描仪对其进行扫描测量,进行点云数据采集处理、模型建立、成果分析和溜井健康状况评估;进一步通过Rhino-FLAC3D耦合建模分析方法,开展溜井在自重应力及地应力作用下的稳定性分析;最后基于分析结果提出了符合实际的溜井放矿管理和修复措施。结果表明:溜井在自重应力及地应力作用下相对稳定,溜井井壁破损的主要原因为矿石放矿过程中的冲击及磨损作用,为李官集铁矿溜井的安全运行提供基础依据。

基于EDEM仿真的溜槽防冲击研究

为减小溜槽下落煤炭对下部承载设备的冲击,文中设计一种具有防冲击结构的新型溜槽,该结构具有减速轮和减速挡板2个减速装置,可以快速降低煤炭运行速度,减小下落煤炭冲击力,采用Solidworks建立溜槽的三维模型,通过EDEM-MBD耦合建立了不同煤炭在溜槽中的动态过程,以Hertz-Mindlin接触模型对不同煤炭下落过程进行了数值模拟分析,得到不同煤炭在下落过程中的速度和冲击力变化曲线,验证了防冲击结构的合理性。

超深地连墙异形槽段多导管同步浇筑系统设计

某长江大桥南航道桥主跨设计长度为2300m,锚碇结构采用支护转结构复合地下连续墙基础,最大成槽深度83 m。一期槽段创新性的采用现浇钢壳混凝土成墙技术,施工时需要配套新工艺、新装备来解决异形多根导管同步性浇筑的难题。为此,文中提出了多导管一体化同步浇筑解决方案。首先,分析该长江大桥南航道桥锚碇基础结构特点,明确十字形槽段浇筑空间和设计参数;其次,详细设计多导管同步浇筑系统,采用自动化流量分料系统搭配一体化多导管浇筑平台来实现异形槽段的同步浇筑;最后,介绍超深锚碇地连墙异形槽段浇筑工序,在槽位处开展多导管同步浇筑系统功能性试验,顺利完成封底混凝土和二次混凝土浇筑,为今后同类型超深地连墙异形槽段的浇筑提供了参考和借鉴。

湖南某白钨矿分级-重选联合预抛及浮选试验研究

为验证湖南某白钨矿分级-重选联合预抛废在工业上的可行性,进行了工业分流试验和浮选对比小型试验。结果表明,在适宜条件下,采用筛分-螺旋溜槽预抛工艺,可抛掉产率25.50%、钨品位0.034%、钨损失率2.99%的抛废产品;抛废后再进行浮选,精矿产品品位和回收率均高于分级溢流直接浮选所得精矿产品。

某低品位天青石矿选矿试验研究

针对某低品位天青石矿进行了选矿试验研究。该低品位天青石原矿SrSO4品位29.28%,含Sr13.97%,Sr是主要待回收元素,无其他有回收价值的有色金属元素,主要脉石成分为CaO34.17%和SiO24.35%,含S5.51%,其他成分含量较低,有害成分BaO品位为0.4%,占比较低。该矿石中主要含锶矿物为天青石(29.2%),主要脉石矿物是方解石(64.2%)和石英(3.83%),含少量的长石、重晶石、白云石和褐铁矿等矿物。依据目的矿物与脉石矿物密度差异大等特征,开展了摇床和螺旋溜槽重选试验。结果表明,单一摇床在磨矿细度为-0.074mm占45%时,可获得精矿SrSO4品位85.41%、Sr回收率60.86%的试验指标;分级-螺旋溜槽-摇床重选-中矿再磨再选联合工艺在磨矿细度为-0.074mm占45%时,可获得精矿SrSO4品位为91.89%,Sr回收率可达60.88%,精矿含CaO1.33%、BaO0.87%符合优等品质量标准;“分级—螺旋溜槽—摇床重选—中矿再磨再选”工艺的尾矿-0.045mm粒级产率占44.09%,+0.15mm粒级产率占27.30%,SrSO4品位随粒级的降低逐渐升高,尾矿中SrSO4主要损失在细粒级中,其中-0.045mm粒级Sr金属分布占比达71.06%,磨矿过程中应注意减少-0.045mm粒级的产生,降低Sr金属损失。研究结果可为同类矿石的处理提供技术参考。

高深溜井冲击产尘相似模拟试验研究

根据高深溜井的生产工艺特征,分析了冲击产尘规律,基于相似定律,建立了溜井卸矿相似试验模型及除尘测试系统,在实验室开展了溜井卸矿模拟试验,测试了不同治理除尘措施条件下的降尘效率,得出了抽尘卸压组合除尘技术,试验结果应用到现场后,总粉尘浓度由600.8 mg/m^(3)降至5 mg/m^(3),降尘效率达99.1%,呼吸性粉尘浓度从166.7 mg/m^(3)降至3 mg/m^(3),降尘效率达98.2%,降尘效果较好,有效地解决了高深溜井冲击产尘。