考虑沉降影响的过滤方程式

影响滤饼过滤的因素很多。试验结果表明，当悬浮液中的固体颗粒较大时，颗粒沉降对滤饼过滤的影响就很突出。本文讨论了沉降对滤饼过滤的影响，导出了考虑沉降影响的恒压过滤方程，并进行了实验验证。     

煤泥离心过滤和机械压滤的滤饼层粒度分布及其影响

针对离心过滤和机械压滤过程中煤粒成饼机理的差异,采用分层取样法分析对比了煤泥离心过滤与机械压滤两种不同过滤方式形成的滤饼内部的粒度及水分分布特点,基于沉降理论探讨了离心过滤和机械压滤的成饼过程,并分析了入料级配对离心过滤过程中滤饼粒度分布的影响。结果表明:机械压滤形成的滤饼中,颗粒粒度和滤饼水分沿滤饼厚度的方向无显著变化,而离心过滤形成的滤饼中,颗粒粒度和滤饼水分沿滤饼厚度的方向存在较大变化,距离滤网越近,滤饼层颗粒的平均粒度越粗、水分越低;入料级配对离心过滤的滤饼层粒度的径向分布及脱水效果影响显著,随着入料平均粒度的减小,上述径向分布差异呈现缩小的趋势;沿着滤饼厚度的方向,压滤滤饼中的过滤比阻分布是相对均匀的,在理论分析中可近似为常数,而离心过滤的滤饼层的过滤比阻分布具有非均匀性,影响比阻分布的因素具有复杂性。     

超声波改性阳离子聚丙烯酰胺对煤泥水絮凝沉降及脱水性能的影响

絮凝沉降和过滤脱水是煤泥水处理的常见方法。絮凝效果直接影响煤泥的脱水效果。提出了一种利用超声改性的阳离子聚丙烯酰胺（CPAM）强化煤泥水絮凝脱水过程的新技术。用流变仪研究了超声预处理不同时间的CPAM溶液的特性。通过沉降试验以及浊度测试分析了超声改性絮凝剂对煤泥水沉降的影响。使用聚焦光束反射率测量系统与颗粒观测系统观察不同改性CPAM处理煤泥水时的絮体特性。建立了絮体特性与煤泥水过滤过程所形成的滤饼特性的联系。实验结果表明，经过40 s超声处理的CPAM作用于煤泥水后，煤泥絮凝效果最好，上清液浊度最低，为180 NTU。在该条件下，煤泥的过滤速度最快，与未经超声处理的情况相比，过滤时间减少25 s。此外，在此条件下获得的滤饼水分含量也最低，为29%。因为经过40 s的超声处理后，部分CPAM分子链被超声产生的强烈的机械以及化学作用随机切断，这些被切断的CPAM分子链将煤泥颗粒逐渐聚集成微小絮体，而未被切断的CPAM分子链进一步将这些小絮体连接在一起。煤泥颗粒在聚合物内部通过多组分聚合物的复杂体系得以紧密结合。随着絮体的沉降，形成了更加致密的结构和沉积床。这些致密的絮体构建的沉积层具有较...     

滤饼的可压缩性与滤饼比阻的研究

在对表层过滤特性和沉降的关系进行深入研究的基础上，明确了滤饼都是可压缩性的，其可压缩性分为两大类：滤饼中的颗粒位移或迁移和团聚颗粒的变形，由于它们被压缩机理不同，所以与有关因素的关系也不同，分析和论述了主要关系。     

絮凝剂在金矿尾砂真空过滤脱水中的应用研究

尝试将絮凝剂应用到金矿尾砂真空过滤脱水中,以解决过滤脱水过程能耗高的缺点。开展了絮凝剂 筛选试验和尾砂真空过滤脱水实验,探讨了絮凝剂单耗和真空压力对尾砂真空过滤脱水过程的影响。实验结果表 明：分子量为 2 200 万的阴离子型 PAM（A-2 200）对该尾砂效果最佳;压力为 50 kPa 时,随絮凝剂单耗增加,初始沉 降速度加快,滤饼浓度先缓慢降低、35 g/t 后快速降低,滤饼分层程度先快速减小、35 g/t 后趋缓;在絮凝剂单耗为 35 g/t 时,随压力的增加,沉降速度加快,滤饼浓度先快速增加后逐渐趋缓,滤饼分层越来越严重;絮凝剂单耗和压力 对尾砂过滤脱水速度具有协同效应,絮凝剂单耗在 0~35 g/t 时,滤饼浓度主要受压力影响,滤饼分层程度主要受絮 凝剂单耗影响。研究结论为絮凝沉降技术在尾砂真空过滤脱水中的应用提供数据支撑。     

聚丙烯酰胺对细粒赤铁矿沉降行为的影响

细粒铁精矿在浓缩过滤环节存在沉降速率慢,溢流固体悬浮物浓度高,精矿滤饼含水率高等问题。通过添加絮凝剂产生凝聚、桥连等作用使矿物颗粒形成絮团,可以促进细粒铁精矿沉降。以某赤铁矿精矿为研究对象,阴离子型、阳离子型、非离子型和两性聚丙烯酰胺为絮凝剂,通过沉降试验及赤铁矿表面ζ电位测定来考察聚丙烯酰胺对赤铁矿絮凝沉降行为的影响。结果表明:赤铁矿颗粒与絮凝药剂分子间相互作用方式主要包括静电力、氢键、范德华力、化学吸附等,而ζ电位在这一过程中是否起主要作用以及对这一过程是起促进或者弱化作用主要取决于絮凝剂使用种类、用量和矿浆pH值。试验结果为选择合适絮凝剂更好促进细粒铁精矿沉降提供了理论依据和指导。     

Ecosuc新型节能过滤机

芬兰 Valmet 造纸机公司研制出一种新的过滤方法,可在不耗热能的条件下对矿浆与悬浮物进行机械脱水。此法称为 Ecosuc 法,根据其原理制造的过滤机同真空圆盘过滤机类似,可用于化工、矿业与冶金。此种形式的过滤在选矿中能将固体颗粒从高浓度液体中分离出来,把滤饼水份降到很低。在这种情况下若用普通过滤方法,滤饼会含过多水份,且许多     

表层过滤特性和沉降的关系研究

从料浆沉降和过滤成饼两个角度同时研究过滤速度、成饼速率、滤饼的渗透性,提出了更全面的滤饼比阻关系式,说明滤饼渗透率首先与料浆的浓度和沉降速度有关,因此,也和料浆的预处理及料浆的化学环境密切相关。     

高湿度细粒散体的振动助滤

研究振动对高湿度细粒散体过滤的助滤作用并探讨振动助滤的机理。结果表明 ,对试验所用物料 ,施振对真空过滤和加压过滤都有明显助滤效果 ,对真空过滤平均含湿率可降低 6%～ 7% ,加压过滤降低 5 %～ 8% ,而散体浓度、振动频率和振动方式对过滤效果影响很小。相同条件下 ,加压比真空的过滤效果稍好一些。振动导致散体颗粒的移动和活化以及散体介质的分散 ,使滤饼内部固体颗粒将向滤饼表面移动 ,减弱紧缩活动 ,增大孔隙率 ,降低滤饼比阻 ,从而体现出助滤效果。     

添加絮凝剂对硫精矿过滤过程的影响

由于金山店浮选硫精矿细粒级含量高,-37μm粒级含量达77.47%,导致浓密池长期跑浑。在已经研究了添加絮凝剂改善其沉降的基础上,运用比阻法探讨沉降过程残留絮凝剂对后续硫精矿过滤速率以及滤饼含水量的影响。试验结果表明,所选择的高分子絮凝剂未对过滤过程产生不利影响,均可降低滤饼比阻,并且滤饼比阻随絮凝剂量增大而减小;同时含絮凝剂时的滤饼水分要小于不含絮凝剂时,但滤饼的含水量会随絮凝剂含量增大而增大。     

DEM simulation of cake formation in sedimentation and filtration

This paper presents a DEM study of cake formation and growth in sedimentation and filtration processes with constant flow rate or pressure. The liquid flow is assumed to be one-dimensional and the motion of particles is three-dimensional. Various forces are included to determine the motion of particles, including the particle–particle contact forces, the van der Waals force and the particle–fluid interactions such as buoyancy, drag and lift forces. The effects of the material properties of particles and liquid and the operational conditions are examined. The structures of cakes are also analysed and the relationship between cake porosity and interparticle force is quantified. The microscopic analysis demonstrates that these variables affect the process and the cake structures through their effects on the gravity or cohesive force, which competes in controlling the formation of a cake.     

微波辐照改变煤泥水沉降过滤性能的机理

针对高灰、细泥含量高的煤泥水固液分离困难、系统复杂和效果差等问题,采用微波辐照预处理方法优化煤泥水沉降过滤特性。探索了微波辐照前后煤泥水的沉降特性,过滤特性,煤泥颗粒表面电性及粒度分布规律。试验结果表明:微波辐照后,煤泥水沉降特性明显改善,絮凝沉降效果显著,药耗降低,最优方案为微波预处理2 min,PAM用量0.75 m L;煤泥水过滤分离性能显著提高,煤泥比阻明显降低,最大降低54%;过滤脱水效果变好,真空抽滤后的含水率最大下降到15.89%;煤颗粒表面的Zeta电位的绝对值减小,最大降低24%,双电层被压缩,颗粒间总的相互作用势能减小,颗粒发生凝聚,产生颗粒粗大化现象,小于10μm的颗粒减少30%左右,大于74μm的颗粒增加3倍多,有利于煤泥水的沉降。     

Solid–liquid separation equipment selection and modelling

The ease with which data may be entered into, and extracted from, electronic databases using Internet based applications is providing new opportunities for understanding and modelling of complex systems. An expert system for solid–liquid separation equipment selection and elimination, using an Internet based interface coupled to such a database, is described. Also, a database containing filtration constants for a variety of different minerals is provided and an illustration of how these constants may be used in mathematical simulations of filtration processes is given. A simple experimental procedure, which can be performed using only a single test where the pressure during filtration is incrementally increased, can provide the necessary filtration constants for the simulation procedure. Hence, the database of filtration constants can be easily expanded using experimental data from this, or similar procedures. An experimental technique that measured the in situ concentration of the forming filter cake, via electrical conductivity measurements, was used to compare the simulated local cake concentrations, using the filtration constants, against the measured ones. The agreement between the simulated cake concentrations and the measured ones was excellent.     

絮凝剂对细粒铁精矿沉降效果的影响

为改善细粒赤铁矿精矿在浓缩脱水过程中存在的沉降时间长、过滤速率低、穿漏现象严重、滤饼含水率高等问题,以巴西某赤铁矿精矿为研究对象,考察了絮凝剂种类及用量、矿浆pH、温度及混匀程度等对赤铁矿沉降行为的影响。结果表明：絮凝剂添加量对赤铁矿精矿沉降效果有显著影响,用量过低时,对改善沉降效果不明显,用量过高时会产生“胶体保护”,沉降速率不再随絮凝剂用量增加而提高;聚丙烯酸钠类絮凝剂在酸性条件下对精矿的沉降效果好,聚丙烯酰胺类在碱性条件下沉降效果较好;温度较低时,不利于絮凝剂与矿物颗粒作用,沉降效果差,温度过高时,絮凝剂发生降解,沉降效果变差;翻转混匀次数少时絮凝剂分子分散不好,精矿沉降速率低,在充分混合时,细粒赤铁矿沉降速率达到最大值,进一步增加翻转混匀次数,会造成絮团断裂,精矿沉降速率降低。试验结果对赤铁矿精矿沉降时选取合适的絮凝剂,提高精矿沉降效果具有重要意义。     

Ultrasonic velocimetry for the in situ characterisation of particulate settling and sedimentation

This paper reports on the development of an in situ ultrasonic velocimetry technique, to study the settling and sedimentation behaviour of particle dispersions. Specifically, the technique utilises a commercial ultrasonic velocity profiler (UVP) equipped with a 1 MHz transducer-receiver, to measure both particle velocities in the dispersion and the evolution of the sediment bed interface with time. It was found in systems of bi-modal non-coagulated glass particles (with a major size-peak of ∼10 μm) that measured velocities suggested dispersion segregation, although generally values were not reliable as particle settling velocities were below the instrument’s threshold. For particle systems coagulated in 1 M KCl, measured dispersion velocities were within the machine’s resolution and a high level of system detail could be extracted from the velocity profile maps, such as the development of hindered settling above the bed and movement of the cloud-front. For both coagulated and non-coagulated dispersions, the evolution of the sediment bed height with time could be measured, by analysing particle velocities in the near-bed region. Bed profiles indicated the non-coagulated particles settled slowly into a compact bed, while the coagulated particle-aggregates initially settled faster into a loosely packed bed that compressed over-time.     

斜窄流内固粒在斜板面上沉积与滑落的研究

基于对斜窄流澄清—浓密箱斗生产作业的数年观察与实测,经长期试验研究查明了斜窄流内固粒在斜板面上沉积与滑落的主要规律。在斜窄流的沉降区段,粗粒或重粒率先沉积,最细粒或轻粒沉积在板面的顶部区域。沉积物沿倾角为α的板面连续滑落,先决条件是其重力的下滑分力大于表面阻力。优选板材、优化设计与制做使表面阻力减至最小,板面顶部区域沉积物积累的厚度、质量与重力达到一定值,自行滑落即发生且持续。板间通道堵塞的主要原因在于箱斗内沉积物过量。     

基于最小沉降速度的浓缩机入料装置改进研究

 本文运用“浅池理论”给出假设条件,推导出浓缩机底流量不可忽略和可忽略两种情况下煤泥颗粒的最小沉降速度公式,并分析煤泥颗粒最小沉降速度的影响因素。在此基础上,对浓缩机入料装置进行改进,改变了入料液流的方式和方向,增加了水平流动层的厚度,稳定了浓缩机入料流态,改善了煤泥颗粒沉降的路线,有效提高了煤泥颗粒沉降速度的稳定性。     

短程快速分离细粒的斜窄流重力过程及单元集成设备

研究了在斜窄(上升)流中以短距离快速分离细粒的固液分离、固粒分级、沉渣浮油等重力过程,固粒在斜窄流底板面上的沉积与滑落以及在箱斗的沉积层内搅动剪切以助排底流的机理,研制了四种用途的单元集成斜窄流沉降分离设备。在相同的使用条件下,这些新设备单位占地面积的生产能力为其同类普通设备的3~8倍,已在包括新疆和西藏的23个省、区矿冶、钢铁、化工、轻工及环保等领域应用推广。     

Interference of coarse and fine particles of different shape in mixed porous beds and filter cakes

In solid–liquid separation the knowledge of solids packing structure is important to control permeability and dewaterability. In particular, cakes formed in filtration are often represented by the composition in coarse and fine particles. In this work cakes were modelled by mixing a bed of coarse (spheres) and fine (kieselguhr of three types and kieselgel) particles with a wide size distribution, in order to obtain beds with different proportions of plate and rod-like particles. Size ratio of glass beads to kieselguhr particles were in the range 23–30. Porosity and permeability were measured for a range of large particle fraction in the mixture from 0 up to 1.0. The fractional porosity of each particle fraction was introduced as a parameter. The approach proposed in this work was also successfully applied to different published filtration data. It was found that (1) the presence of more than 10% of fines in the coarse granular bed significantly reduces the cake permeability; (2) to improve cake permeability the volume fraction of filter aid in suspension must be at least 50–60% of total solid volume; (3) obtained data may be used to control the porosity of a mixture, if the fractional porosity of large and small particles is known or to estimate mixture tortuosity.     

褐煤热解半焦在污泥调质与深度浓缩脱水中的应用

为解决当前污泥脱水难的问题,以褐煤热解半焦作为污泥调理剂对污泥进行调质处理,并采用污泥重力浓缩脱水的实验方法探讨了褐煤半焦对污泥调质与深度浓缩脱水的影响。结果表明:用半焦对污泥进行调质,能够改善污泥的浓缩脱水性能、沉降性能以及浓缩污泥的机械脱水性能,当100 g污泥中加入2 g半焦时,浓缩污泥的含水率由调质前的91.13%降低至调质后的78.05%,浓缩污泥经真空抽滤后所得滤饼的含水率由调质前的65.00%降低至调质后的49.50%。污泥浓缩前20 min内,污泥的平均沉降速率由调质前的2.67 mL/min提高至调质后3.25 mL/min。通过污泥调质前后的粒度分析和半焦的扫描电镜图像分析,探讨了半焦对污泥调质与深度浓缩脱水的机理,其机理主要表现在半焦对污泥的吸附作用及半焦对污泥亲水性能的消弱作用。