Rapid prediction of flow and concentration fields in solid-liquid suspensions of slurry electrolysis tanks

Slurry electrolysis(SE),as a hydrometallurgical process,has the characteristic of a multitank series connection,which leads to various stirring conditions and a complex solid suspension state.The computational fluid dynamics(CFD),which requires high computing resources,and a combination with machine learning was proposed to construct a rapid prediction model for the liquid flow and solid concentration fields in a SE tank.Through scientific selection of calculation samples via orthogonal experiments,a comprehensive dataset covering a wide range of conditions was established while effectively reducing the number of simulations and providing reasonable weights for each factor.Then,a prediction model of the SE tank was constructed using the K-nearest neighbor algorithm.The results show that with the increase in levels of orthogonal experiments,the prediction accuracy of the model improved remarkably.The model established with four factors and nine levels can accurately predict the flow and concentration fields,and the regression coefficients of average velocity and solid concentration were 0.926 and 0.937,respectively.Compared with traditional CFD,the response time of field information prediction in this model was reduced from 75 h to 20 s,which solves the problem of serious lag in CFD applied alone to actual production and meets real-time production control requirements.

Flow Behavior of Clay-Silt to Sand-Silt Water-Rich Suspensions at Low to High Shear Rates: Implications for Slurries, Transitional Flows, and Submarine Debris-Flows

Water-rich clay to sand suspensions show a shear rate dependent flow behavior and knowledge of the appropriate rheological model is relevant for sedimentological, industrial and hydraulic studies. We present experimental rheological measurements of water-rich(40 to 60 wt%) clay to silt(population A) and silt to sand(population B) suspensions mixed in different proportions. The data evidence a shear rate dependent shear thinning-shear thickening transition. At lower shear rates, the suspensions organize in chains of particles, whereas at higher shear rates, these chains disrupt so increasing the viscosity. The viscosity, consistency and yield stress decrease as the A+B fraction decreases as the content of B particles increases. This behavior reflects the competing effects of the lubrication and frictional processes as a function of particle size and water content. Transitional flows form by the incorporation of small amounts of the finer fraction while ‘oceanic floods’ form at the estuary of rivers and the submarine debris-flows increase their velocity by incorporating water. The critical Reynolds number of the studied suspensions is ～2000±100 suggesting that the grainsize plays a major role in the laminar to turbulent transition. Our results have implications for the modeling of sediment flows and the hazard related to floods.

Settlement prediction model of slurry suspension based on sedimentation rate attenuation

This paper introduces a slurry suspension settlement prediction model for cohesive sediment in a still water environment. With no sediment input and a still water environment condition, control forces between settling particles are significantly different in the process of sedimentation rate attenuation, and the settlement process includes the free sedimentation stage, the log-linear attenuation stage, and the stable consolidation stage according to sedimentation rate attenuation. Settlement equations for sedimentation height and time were established based on sedimentation rate attenuation properties of different sedimentation stages. Finally, a slurry suspension settlement prediction model based on slurry parameters was set up with a foundation being that the model parameters were determined by the basic parameters of slurry. The results of the settlement prediction model show good agreement with those of the settlement column experiment and reflect the main characteristics of cohesive sediment. The model can be applied to the prediction of cohesive soil settlement in still water environments.

Suspension mechanism and application of sand-suspended slurry for coalmine fire prevention

North and west China has abundant coal resources, however, such resources make these regions prone to serious mine fire disasters. Although the copious sand and fly ash resources found in these areas can be used as fire-fighting materials, conventional grouting is expensive because of water shortage and loess particles. A new compound material(i.e., a sand-suspended colloid), which comprises a mineral inorganic gel and an organic polymer, is developed in the current study to improve the quality of sand injection and reduce water wastage when grouting. The new material can steadily suspend the sand, through the addition of a small amount of colloid yielding steady sand-suspended slurry. The process of producing the slurry is convenient and quick, overcoming the shortage of sand-suspending thickeners which need heat and are difficult to produce. The space work model based on the theory of the double-electric layer is established to study the suspended mechanism of the solid particles in the sand-suspended colloid.The dispersion effect of the sand-suspended colloid is demonstrated by the incorporation of the electrostatic effect by the double-electric layer and the steric hindrance effect on the sand particles, ensuring the stability of the colloid system and the steady suspension of sand particles in the sand-suspended colloid.Mechanical analysis indicates that the sand is suspended steadily under the condition that the rock sand particles stress on the lower part of the fluid is less than the yield stress of the colloid. Finally, the fireprevention technology of sand suspension was applied and tested in the Daliuta Coal Mine, achieving successful results.

Design factors affecting the dynamic performance of soil suspension in an agitated, baffled tank

The effects of particle size, impeller clearance and impeller speed are assessed to show how condition variations influence power consumption in the water-solid slurry suspension in an agitated tank. The energy efficiency of slurry height variation, impeller type and diameter, and solid movement speed has been investigated with six soil series stirred in a soil-water slurry. Coarser sand particles are observed to significantly increase power consumption, while finer particles, for instance clay, decrease the stirring power requirement. The 3-blade HR100 SUPERMIX? impeller manufactured by SATAKE generally performs more efficiently than a conventional4-pitched blade turbine. The impeller's geometric design, including diameter and number of blades influences the impeller's energy efficiency, and HR100 impellers with greater diameters remarkably reduce power consumption. The tests demonstrated that the power required to provide off-bottom solid suspension and solid dispersion can be reduced dramatically by increasing the slurry height rather than by accelerating the impeller, if this option is possible.

防治俯采工作面煤自燃稠化浆体的流变特性研究

针对大倾角俯采工作面煤自燃防治过程中不易灌浆、漏风强度大、浆液无法向高处堆积等问题,以高分子聚合材料、表面活性剂、固相材料为原始材料,制备出不同水土比、稠化剂浓度的浆体并进行悬浮稳定试验,研究稠化浆体的悬浮特性,通过对不同浓度的稠化浆体进行流变特性试验,拟合出流变本构方程,从而研制出一种性能优异、适用于大倾角俯采工作面的稠化浆体材料,最后采用Fluent软件模拟稠化浆体在采空区内的扩散特征。研究结果表明:黄土为稠化浆体最适合的固相材料;当水土质量比为8∶1、稠化剂质量浓度为0.3%时,稠化浆体悬浮性能较好,且屈服应力最小,具有更好的流动性;在采空区内稠化浆体的流动速度与扩散半径成反比,在浆体注入6 h后扩散半径达最大值。

张靖皋长江大桥南航道桥北锚碇地下连续墙槽壁稳定控制技术

张靖皋长江大桥南航道桥为主跨2300 m的双塔双跨吊钢箱梁悬索桥,北锚碇位于长江下游民主沙岛上,地下水水位高,地层以粉砂层和粉质黏土层为主,粉质黏土层力学性能及稳定性差。北锚碇为重力式锚碇,采用双层回字形支护转结构复合地下连续墙基础。地下连续墙共划分为214个槽段,最大深度69.5 m,槽段类型有一字形、L形、T形和十字形。根据地下连续墙结构特点和地质、水文情况,采用液压铣槽机成槽,施工前利用有限元软件模拟分析,确定控制槽壁稳定的关键指标。施工中通过采用三轴水泥搅拌桩加固上部槽壁、分阶段控制泥浆关键指标、填高场地并设置降水井控制槽内泥浆和周围地下水之间的水头差、双重控制成槽垂直度和钢箱(钢筋笼)吊装垂直度,以及优化槽段施工顺序等措施,降低了槽壁失稳的风险,保障了地下连续墙施工质量。

高密度水泥浆技术研究进展

随着油气田开发程度的提高,需要钻探的深井超深井越来越多,各个油田也经常遇到异常高压气层和高压盐水层,使用高性能高密度水泥浆体系可以平衡地层压力,保证作业安全和质量。本文分析了研发高性能高密度水泥浆面临的关键问题,介绍了高密度水泥浆关键技术研究进展,探讨了高密度水泥浆技术发展方向。

Lithium slurry flow cell,a promising device for the future energy storage

Lithium slurry flow cell(LSFC)is a novel energy storage device that combines the concept of both lithium ion batteries(LIBs)and flow batteries(FBs).Although it is hoped to inherit the advantages of both LIBs and FBs,such as high energy density,ease of fabrication,environmental friendly,independent energy and power density,to name but a few.While unfortunately,it still has many challenges to overcome before it becoming the future star in energy storage area.Here in this paper,we briefly recall its history and try to illustrate the main issues that hindering its research as well as application.As a typical interdisciplinary product,LSFC is definitely a promising candidate for large scale energy storage application,while obviously it still has a long way to go.

控压固井候凝阶段井口回压控制方法研究与应用

控压固井可以降低窄安全压力窗口井固井漏失的风险,同时还能在一定程度上提高顶替效率。但是目前控压固井在候凝期间还是基于经验来施加井口回压,井口回压控制不够精确,容易导致井漏或气窜。为此,根据水泥水化、失水以及胶凝作用建立了井口回压计算模型,并形成了候凝压力控制方法,用于指导井口回压控制。通过与目前的控制方法相比表明该方法能够精确指导井口回压控制,保证井筒安全。

旋挖灌注桩泥浆悬浮法机械清孔施工技术研究

泥浆护壁旋挖钻孔灌注桩施工工艺是采用人工制作成品泥浆来置换孔中挖出的土、石,利用泥浆对孔壁的静压力和泥浆在孔壁上形成的泥皮来有效防止孔壁坍塌,再利用水下混凝土置换孔内泥浆的成桩工艺。结合桩基施工经验,以某项目泥浆悬浮法机械清孔旋挖施工技术为例,对旋挖钻孔灌注桩施工流程给予细致探讨,为类似工程提供相关经验借鉴。

Investigation of dense slurry suspensions with coaxial mixers:Influences of design variables through tomography and mathematical modelling

The coaxial mixers enhance the suspension of concentrated slurries in an agitated reactor.In this research work,the complex slurry suspension and dissemination behavior in a coaxial slurry mixing system(comprised of a close clearance anchor rotating with a low speed and an inner axial impeller rotating with a high speed)was analyzed employing ERT(electrical resistance tomography,a non-intrusive flow visualization technique),and computational fluid dynamics(CFD).The numerical models were validated by comparing the axial solid concentration profiles generated using the ERT data and the CFD simulation results.The influences of various important parameters such as the diameter of the inner axial impeller,the inner impeller type,and the inner impeller spacing on the hydrodynamic characteristics of the slurry suspensions in a coaxial mixing vessel were thoroughly analyzed.The radial and axial velocity profiles of solid particles were generated using the validated mathematical models.The assessment of energy loss due to the solid-solid collisions,the particle-fluid frictions,and the particle-vessel wall collisions was conducted.The evaluation of optimum inner impeller clearance and inner impeller diameter is essential to attain a high degree of solids suspension and dissemination in a coaxial slurry mixing system.

泥水盾构泥膜形成二维理论分析

在各种复杂环境下采用泥水盾构法修建隧道工程,需要解决在开挖面上如何及时形成安全有效的泥膜支护问题。采用修正的剑桥模型中正常固结黏土各向等压固结曲线规律,建立泥膜固含率与有效应力之间的关系,结合圆球形颗粒孔隙理想模型的渗透率以及泥膜固含率、渗透率和比阻三者之间的关系,确立新的泥膜形成本构关系模型。将泥膜形成一维模型拓展为二维模型,基于增量分析方法分析泥膜的增长规律,给出泥膜滤失量和厚度分别与位置、时间、重度比和盾构直径等因素的关系。结果表明,修正的剑桥模型能够较好地表征泥膜压缩固结特性;对于高压泥浆,泥浆重度对泥膜增长的影响较小,但对超大直径的盾构其影响不可忽略。

水煤浆流化悬浮高效洁净燃烧技术研究与应用

在深入研究的基础上,作者提出了水煤浆流化悬浮高效洁净燃烧新技术,并进行了工程实践。该技术可用于新型系列水煤浆流化悬浮高效洁净燃烧锅炉的开发,并将各种型式的低效链条炉排锅炉、往复炉排锅炉、煤粉锅炉、鼓泡流化床锅炉、燃油锅炉改造成先进水煤浆流化悬浮高效洁净燃烧锅炉。文中介绍了该技术的特点与原理及工程实践。

槽形抛光工具形状对液流悬浮抛光加工效果的影响

为了研究抛光工具形状对液流悬浮抛光加工的影响,基于液流悬浮抛光系统对柱形和槽形抛光工具在加工中的流体动压力与材料去除进行仿真及试验研究。液流悬浮加工以高速旋转的抛光工具和工件构成润滑副,利用CFD软件分别对柱形及槽形2种抛光工具与工件之间的流体进行数值模拟,通过比较2种抛光工具在工件表面流场中形成的流体动压力与流体速度,可知槽形抛光工具有助于增强加工过程中的流体动压力,但对流体速度的提升效果并不明显。通过加工试验,可知在同等加工条件下槽形抛光工具对粗糙度的去除率和去除速率都要优于柱形抛光工具,并能得到粗糙度为21nm加工表面。

微磨料浆体射流的浆体配制及钻孔性能研究

微磨料浆体射流技术是在微磨料水射流加工技术基础上发展起来的一种新技术。通过添加分散剂和悬浮剂来提高浆体的沉降稳定性;为了配制出优质钻孔浆体,研究了磨料质量浓度、磨料种类、分散剂体积分数和悬浮剂体积分数对钻孔加工的影响,并研究了分散剂体积分数和悬浮剂体积分数对浆体沉降稳定性的影响。研究结果表明:磨料质量浓度存在最佳取值;分散剂并非一定能改善颗粒的沉降稳定性,这与磨料种类、磨料质量浓度和分散剂体积分数等有关;悬浮剂能够改善浆体的悬浮性,其体积分数影响浆体的沉降稳定性和钻孔效果。

不同波段紫外光在TiO_2悬浊液中的消光特点

为确定TiO2 催化剂悬浊液对不同波段紫外光的消光规律 ,本试验以 4 CBA Na为模型污染物 ,针对催化剂/污染物悬浊液体系在不同催化剂投加量下 ,对UVA、UVB和UVC波段光子的消光效果进行了测定 .结果表明 ,各悬浮体系对各波段紫外光的消光基本上符合比耳定律 ,即随着入射光程的增加 ,光强呈现负指数衰减 ;紫外光在催化剂悬浊液中的消光系数随催化剂投加量的增大而增加 ,其增加规律可以用二次多项式表示 ;污染物溶液本身对UVB和UVC紫外光有吸收 ,UVB和UVC紫外光在催化剂 污染物悬浮体系中的消光系数可视为污染物与催化剂颗粒的消光系数之叠加 .催化剂悬浊液对紫外光的消光系数随紫外光波长的减小而增大 ,这意味着使用短波长的UVC作为光催化降解光源可以提高能量利用效率 .

水煤浆流化-悬浮燃烧技术在胜利油田的应用

研究开发了水煤浆流化-悬浮燃烧新技术，介绍了该技术的原理、特点及其在胜利油田的应用情况，该技术具有燃料适应性强、启动迅速、高效低污染等特点。胜利油田的实践证明，水煤浆流化-悬浮燃烧的中小型工业锅炉效率高达到85％～91％，大大高于目前我国燃煤工业锅炉平均效率水平，节能率在20％以上；在环保方面，该技术利于减少城市运煤过程中原煤的损耗与污染，利于减少大气中的飘尘、SO2、NOx、CO2等污染物的排放，环保效益也十分突出。结合现场实践情况，分析了水煤浆流化-悬浮燃烧技术的应用前景，对水煤浆代油、代煤燃烧的推广应用及节能环保事业具有重要的意义。

氧化铈抛光液悬浮性和再分散性研究

考察分散剂、p H以及分散介质对氧化铈抛光液悬浮性和再分散性的影响,通过静置一定时间表征氧化铈抛光液的沉降行为、吸光度和zeta电位大小。结果表明:在制备悬浮性、再分散性好的氧化铈抛光液时,分散剂L的最佳质量分数为2%;p H为10.7时抛光液的悬浮稳定性最好;水和乙醇混合作为分散介质能明显改变抛光液的沉降行为,并且水与乙醇的最佳质量比为4∶1。

利用声发射技术测量搅拌釜的淤浆悬浮高度

根据颗粒运动碰撞搅拌釜壁面产生声波的机理,结合声信号的频谱分析、小波分解和R/S分析,获得了代表颗粒运动的特征信号频段(d1、d2频段)。同时,基于声波特征信号频段能量沿搅拌釜轴向的规律性变化,提出了声波法测量搅拌釜淤浆悬浮高度的判据,即当声波特征信号频段能量或声波特征信号频段能量比出现阶跃性变化时的高度为淤浆悬浮高度。以水-玻璃珠体系为例,研究发现,无论是盘式涡轮还是桨式叶轮的搅拌桨,基于声信号测定淤浆悬浮高度的判据都能较好地得到验证,与目测法相比,其平均相对误差小于10%,具有较高的精度。由此,获得了一种简单快捷、灵敏准确、非侵入式的搅拌釜淤浆悬浮高度测量技术,能够实现淤浆悬浮高度的实时监控。