Enhanced recovery of high-purity Fe powder from iron-rich electrolytic manganese residue by slurry electrolysis

Iron-rich electrolytic manganese residue(IREMR)is an industrial waste produced during the processing of electrolytic metal manganese,and it contains certain amounts of Fe and Mn resources and other heavy metals.In this study,the slurry electrolysis technique was used to recover high-purity Fe powder from IREMR.The effects of IREMR and H2SO4 mass ratio,current density,reaction temper-ature,and electrolytic time on the leaching and current efficiencies of Fe were studied.According to the results,high-purity Fe powder can be recovered from the cathode plate,and the slurry electrolyte can be recycled.The leaching efficiency,current efficiency,and purity of Fe reached 92.58%,80.65%,and 98.72wt%,respectively,at a 1:2.5 mass ratio of H2SO4 and IREMR,reaction temperature of 60℃,electric current density of 30 mA/cm^(2),and reaction time of 8 h.In addition,vibrating sample magnetometer(VSM)analysis showed that the coercivity of electrolytic iron powder was 54.5 A/m,which reached the advanced magnetic grade of electrical pure-iron powder(DT4A coercivity standard).The slurry electrolytic method provides fundamental support for the industrial application of Fe resource recovery in IRMER.

Kinetic mechanism of copper extraction from methylchlorosilane slurry residue using hydrogen peroxide as oxidant

Copper was extracted from methylchlorosilane slurry residue by a direct hydrogen peroxide leaching method.A number of experimental parameters were analyzed to determine the extraction efficiency of copper.The extraction efficiency of copper reached 98.5%under the optimal leaching conditions,such as the hydrogen peroxide concentration of 1.875 mol·L^(-1),the leaching temperature of 323 K,the liquid–solid ratio of 20 ml·g^(-1),and the stirring speed of 300 r·min^(-1).The leaching kinetics of the copper extraction process was then described by the shrinking core model.There were two stages.The first stage was controlled by chemical reactions,while the second stage was controlled by interface transfer and product layer diffusion.The activation energy and kinetic control equations were determined,as well as an explanation of the leaching mechanism of copper extraction based on kinetic analysis and materials characterization.Copper resources can be recovered from the methylchlorosilane slurry residue efficiently and inexpensively with the methods used in this study.

Impacts of solid physical properties on the performances of a slurry external airlift loop reactor integrating mixing and separation

Solid physical properties are vital for the design, optimization, and scale-up of gas–liquid–solid multiphase reactors. The complex and interactional effects of the solid physical properties, including particle diameter, density, wettability, and sphericity, on the hydrodynamic behaviors in a new external airlift loop reactor(EALR) integrating mixing and separation are decoupled in this work. Two semi-empirical equations are proposed and validated to predict the overall gas holdup and liquid circulating velocity satisfactorily, and then the individual influence of such solid physical properties is further investigated. The results demonstrate that both the overall gas holdup in the riser and the liquid circulating velocity in the downcomer increase with the contact angle, but decrease with particle size, density, and sphericity.Additionally, the impact of the particle size on the liquid circulating velocity is also profoundly revealed on a micro-level considering the particle size distribution. Moreover, the axial solid concentration distribution is discussed, and the uniformity of the slurry is described by the mixing index of the solid particles. The results show that a more homogeneous mixture can be achieved by adding finer particles other than attaining violent turbulence. Therefore, this work lays a foundation for the design, scale-up, and industrialization of the EALRs.

Multi-criteria comparative analysis of the pressure drop on coal gangue fly-ash slurry at different parts along an L-shaped pipeline

Disposing of coal gangue and fly-ash on the surface is a risky method with tremendous potential catastrophic consequences for the environment.Backfill mining is a promising practice for turning those hazardous wastes into functional backfill materi-als.Unfortunately,how to efficiently deliver the slurry to the desired places remains under-researched.To address this issue,the computational fluid dynamics software Fluent was used in the current study in addition to a laboratory rheological test to simulate the impact of various parameters on the evolution of pressure at a particular section of the pipeline.Furthermore,the response surface method was employed to investigate how the various components and their corresponding influencing weights interact to affect the pressure drop.This study demonstrates that the pressure drop of the slurry is highly influenced by slurry concentration,speed,and pipe diameter.While conveying speed is the main component in the bend section,pipe diameter takes over in the horizontal and vertical pipe sections.

Efect of Micro Abrasive Slurry Jet Polishing on Properties of Coated Cemented Carbide Tools

Owing to the popularization of coating technology, physical Vapor Deposition (PVD) coated tools have become indispensable in the cutting process. Additionally, the post-treatment of coated tools applied to industrial production can efectively enhance the surface quality of coating. To improve the processing performance of coated tools, micro abrasive slurry jet (MASJ) polishing technology is frst applied to the post-treatment of coated tools. Subsequently, the efects of process parameters on the surface quality and cutting thickness of coating are investigated via single-factor experiments. In the experiment, the best surface roughness is obtained by setting the working pressure to 0.4 MPa, particle size to 3 μm, incidence angle to 30°, and abrasive mass concentration to 100 g/L. Based on the results of the single-factor experiments, combination experiments are designed, and three types of coated tools with diferent surface qualities and coating thicknesses are obtained. The MASJ process for the post-treatment of coated tools is investigated based on a tool wear experiment and the efects of cutting parameters on the cutting force and workpiece surface quality of three types of cutting tools. The result indicates that MASJ machining can efectively improve the machining performance of coated tools.

Physical model investigation on effects of drainage condition and cement addition on consolidation behavior of tailings slurry within backfilled stopes

Estimation of stressses within the tailings slurry during self-weight consolidation is a critical issue for cost-effective barricade design and efficient backfill planning in underground mine stopes.This process requires a good understanding of self-weight consolidation behaviors of the tailings slurry within practical stopes,where many factors can have significant effects on the consolidation,including drainage condition and cement addition.In this paper,the prepared tailings slurry with different cement contents(0,4.76wt%,and 6.25wt%)was poured into1.2 m-high columns,which allowed three drainage scenarios(undrained,partial lateral drainage near the bottom part,and full lateral drainage boundaries)to investigate the effects of drainage condition and cement addition on the consolidation behavior of the tailings slurry.The consolidation behavior was analyzed in terms of pore water pressure(PWP),settlement,volume of drainage water,and residual water content.The results indicate that increasing the length of the drainage boundary or cement content aids in PWP dissipation.In addition,constructing an efficient drainage boundary was more favorable to PWP dissipation than increasing cement addition.The final stable PWP on the column floor was not sensitive to cement addition.The final settlement of uncemented tailings slurry was independent of drainage conditions,and that of cemented tailings slurry decreased with the increase in cement addition.Notably,more pore water can drain out from the cemented tailings slurry than the uncemented tailings slurry during consolidation.

Kinetics of Selective Hydrogenation of PAHs from FCC Slurry Extract over Ni-W/γ-Al_(2)O_(3) Catalyst

The selective hydrogenation of polycyclic aromatic hydrocarbons(PAHs)from fluid catalytic cracking(FCC)slurry extract was conducted in a batch reactor over aγ-Al_(2)O_(3)-supported bimetallic Ni-W catalyst.For the Ni-W/γ-Al_(2)O_(3) catalyst,the experiment run was divided into three processes according to the reaction conditions used:(1)the absence of hydrogenation as both temperature and pressure increased;(2)the desulfurization of FCC slurry extract under a fixed pressure as the temperature increased;and(3)the selective hydrogenation of PAHs when both pressure and temperature remained constant.The hydrogen consumption could be accurately calculated from the Redlich–Kwong equation of state.The results for the removal of PAHs with hydrogenation displayed an excellent fit to the first-order kinetics.The apparent activation energy was determined to be 20.80 kJ/mol.

Development of a High-Temperature Thixotropic Cement Slurry System

Cementing carbonate reservoirs is generally a difficult task.The so-called thixotropic cement slurry has gained considerable attention in this regard as it can help tofix some notable problems.More precisely,it can easilyfill the leakage layer;moreover,its gelling strength can grow rapidly when pumping stops,thereby increasing the resistance to gas channeling,effectively preventing this undesired phenomenon in many cases.High-temperature thixotropic cement slurry systems,however,are still in an early stage of development and additional research is needed to make them a viable option.In the present study,using a self-developed composite high-temperature thixotropic additive as a basis,it is shown that the compressive strength can be adjusted by tuning the proportion of silica sand,the high-temperature retarder,fluid loss additive and dispersant(compatible with the thixotropic additive).According to the tests,the developed high-temperature thixotropic cement slurry system has a 14 d compressive strength of 29.73 MPa at 150°C,and a thickening time of 330 min when the dosage of retarder is 2%.At the same time,the rheological property,water loss,permeability,water separation rate,and settlement stability of the cement slurry system meet the requirements of cementing construction.

Numerical simulation study on multiphase flow pattern of hydrate slurry

The research on the multiphase flow characteristics of hydrate slurry is the key to implementing the risk prevention and control technology of hydrate slurry in deep-water oil and gas mixed transportation system.This paper established a geometric model based on the high-pressure hydrate slurry experimental loop.The model was used to carry out simulation research on the flow characteristics of gas-liquid-solid three-phase flow.The specific research is as follows:Firstly,the effects of factors such as slurry flow velocity,hydrate particle density,hydrate particle size,and hydrate volume fraction on the stratified smooth flow were specifically studied.Orthogonal test obtained particle size has the most influence on the particle concentration distribution.The slurry flow velocity is gradually increased based on stratified smooth flow.Various flow patterns were observed and their characteristics were analyzed.Secondly,increasing the slurry velocity to 2 m/s could achieve the slurry flow pattern of partial hydrate in the pipeline transition from stratified smooth flow to wavy flow.When the flow rate increases to 3 m/s,a violent wave forms throughout the entire loop.Based on wave flow,as the velocity increased to 4 m/s,and the flow pattern changed to slug flow.When the particle concentration was below 10%,the increase of the concentration would aggravate the slug flow trend;if the particle concentration was above 10%,the increase of the concentration would weaken the slug flow trend,the increase of particle density and liquid viscosity would weaken the tendency of slug flow.The relationship between the pressure drop gradients of several different flow patterns is:slug flow>wave flow>stratified smooth flow.

A Comprehensive Method for the Optimization of Cement Slurry and to Avoid Air Channeling in High Temperature and High-Pressure Conditions

Air channeling in the annulus between the casing and the cement sheath and/or between the cement sheath and formation is the main factor affecting the safe operation of natural gas wells at high temperatures and pressures.Prevention of this problem requires,in general,excellent anti-channeling performances of the cement sheath.Three methods to predict such anti-channeling performances are proposed here,which use the weightless pressure of cement slurry,the permeability of cement stone and the volume expansion rate of cement sheath as input parameters.Guided by this approach,the anti-channeling performances of the cement slurry are evaluated by means of indoor experiments,and the cement slurry is optimized accordingly.The results show that the dangerous transition time of the cement slurry with optimized dosage of admixture is only 76 min,the permeability of cement stone is 0.005 md,the volume shrinkage at final setting is only 0.72%,and the anti-channeling performances are therefore maximized.The effective utilization of the optimized cement slurry in some representative wells(LD10–1-A1 and LD10–1-A2 in LD10–1 gas field)is also discussed.

Simulation Research on Coal-Water Slurry Gasification of Oil-Based Drill Cuttings Based on Fluent

In this paper,based on Fluent software,a five-nozzle gasifier reactor was established to simulate the gasification process of oil-based drill cuttings coal-water slurry.The influence of concentration and oxygen/carbon atomic ratio on the gasification process of oil-based drill cuttings coal-water slurry was investigated.The results show that when the oxygen flow is constant,the outlet temperature of gasifier decreases,the content of effective gas increases,and the carbon conversion rate decreases with the increase of concentration;When the ratio of oxygen to carbon atoms is constant,the effective gas content rises and the temperature rises with the increase of the concentration,and the carbon conversion rate reaches the maximum value when the concentration of oil-based drill cuttings coal-water slurry is 65%;When the concentration is constant,the effective gas content decreases and the outlet temperature rises with the increase of the oxygen/carbon atom ratio,and the carbon conversion rate reaches 99.80%when the oxygen/carbon atom ratio is 1.03.It shows that this method can effectively decompose the organic matter in oilbased drill cuttings and realize the efficient and cooperative treatment of oil-based drill cuttings.

Mechanical properties and microstructural evolution of rheocast A356 semi-solid slurry prepared by annular electromagnetic stirring

Nowadays,having an effective technique in preparing semi-solid slurries for rheocasting process seems to be an essential requirement.In this study,semi-solid slurry of A356 aluminum alloy was prepared by three-phase annular electromagnetic stirring(A-EMS)technique under different conditions.The effects of stirring current,pouring temperature and stirring time on microstructural evolution,mean particle size,shape factor and solid fraction were investigated.The rheocasting process was carried out by using a drop weight setup and to inject the prepared semi-solid slurry in optimal conditions into the step-die cavity.The filling behavior and mechanical properties of parts were studied.Microstructural evolution showed that the best semi-solid slurry which had fine spherical particles with the average size of~27μm and a shape factor of~0.8 was achieved at the stirring current of 70 A,melt pouring temperature of 670℃,and stirring time of 30 s.Under these conditions,the step-die cavity was completely filled at die preheating temperature of 470℃.The hardness increases by decreasing step thickness as well as die preheating temperature.Moreover,the tensile properties are improved at lower die preheating temperatures.The fracture surface,which consists of a complex topography,indicates a typical ductile fracture.

A Comprehensive Review of the Influence of Heat Exchange Tubes on Hydrodynamic,Heat,and Mass Transfer in Bubble and Slurry Bubble

Bubble and slurry bubble column reactors(BCRs/SBCRs)are used for various chemical,biochemical,and petro-chemical applications.They have several operational and maintenance advantages,including excellent heat and mass transfer rates,simplicity,and low operating and maintenance cost.Typically,a catalyst is present in addition to biochemical processes where microorganisms are used to produce industrially valuable bio-products.Since most applications involve complicated gas-liquid,gas-liquid-solid,and exothermic processes,the BCR/SBCR must be equipped with heat-exchanging tubes to dissipate heat and control the reactor’s overall performance.In this review,past and very recent experimental and numerical investigations on such systems are critically dis-cussed.Furthermore,gaps to befilled and critical aspects still requiring investigation are identified.

煤层底板含水层区域注浆改造浆液扩散范围现场示踪试验

近年来,为解放底板高承压灰岩水上煤炭资源,华北煤田普遍采用地面定向钻技术,对太原组薄层灰岩进行区域性注浆加固改造(习称“底板区域治理”),以全面封堵灰岩岩溶裂隙并阻断垂向导水通道。该技术中,与浆液扩散范围(半径)密切相关的“水平分支孔”孔间距设计问题,一直备受学界和业界的广泛关注。皖北矿区底板区域注浆工程量大,特别是深部资源开采,将有数十亿元的注浆工程,有必要查清浆液扩散范围真实数据。为此,以皖北矿区恒源煤矿为研究基地,依托Ⅱ63采区底板区域治理工程,设计并实施浆液扩散范围示踪试验,在中间的水平分支孔(Z8-7)投放荧光剂(示踪剂),在两侧的水平分支孔(Z8-6、Z8-8)以及交叉分支检测孔(Z8JC)取岩屑样鉴别荧光水泥,以获得浆液扩散范围,进而在浆液扩散影响因素分析基础上,构建恒源煤矿底板区域注浆治理浆液扩散范围计算公式。结果表明:①综合岩屑现场及室内鉴别结果分析,获得恒源煤矿Ⅱ63采区底板区域注浆浆液扩散范围为38.3~44.0 m,且水泥分布密集区在水平分支孔浆液扩散范围30 m以内,该区域内注浆效果最佳。②通过现场岩屑快速鉴别与室内岩屑精准鉴别,取得的浆液扩散范围基本一致,证明了荧光示踪浆液扩散范围的有效性。③通过对比分析,认为在计算参数、边界约束等符合实际注浆工况条件下,浆液扩散范围理论计算和数值模拟结果,与现场示踪试验实测结果较为接近。④利用示踪试验过程中的压水试验及注浆参数、钻遇构造及水文地质响应等数据,考虑重力、构造、地下水径流等因素影响,借助SPSS非线性拟合软件,得到恒源煤矿Ⅱ63采区底板区域注浆浆液扩散范围计算公式。⑤基于恒源煤矿受注层实际地质、水文地质条件,利用拟合的浆液扩散范围计算公式得出Ⅱ63采区Z8场地浆液扩散范围为37.8~42.9 m,与浆液扩散范围示踪试验实测结果相近,计算公式可在类似条件下推广应用。本次煤矿底板区域注浆浆液扩散范围现场示踪工程试验,不仅取得了浆液扩散范围的真实数据,而且阐明了浆液扩散与多种地质、水文地质因素之间的内在联系,揭示了超深、超长定向钻注浆浆液扩散机理,构建了浆液扩散范围计算公式,为类似条件下底板区域治理工程水平分支孔孔间距的合理设计提供了参考依据。

电解煤浆制氢过程中煤阶及矿物的影响与煤结构演化研究进展

电解煤浆制氢(CSE)是一种在温和条件下实现电化学制氢与煤炭低碳清洁利用的新技术。电解煤浆制氢的理论分解电压仅为0.21V,实际消耗的能量约为电解水制氢的1/3~1/2,具有能耗低、污染小,可与煤基精细化学品制备、煤岩显微组分分离等过程集成的优点,但煤转化率低、煤浆电解机理不清晰等问题仍具有极大挑战性。本文讨论了CSE机理研究现状,概述了煤阶及矿物质对CSE的电氧化活性的影响,总结了CSE过程中煤表面元素、官能团结构、煤碳骨架结构在阳极区电化学氧化的变化规律,讨论了阴极区电化学还原对煤表面润湿性、Zeta电位等煤表面性质的影响,以及阴极区添加煤浆的电还原制氢及其耦合技术,以期为CSE制氢与煤低碳清洁利用提供理论支撑。此外,本文还展望了CSE的发展方向,提出了高性能CSE电极催化材料开发及煤氧化-还原反应调控机理研究是该技术获得突破的关键。

水平联合竖直排水板真空预压处理工程废浆试验研究

传统真空预压法(VP)在加固工程废浆时存在预制竖向排水板(PVD)易淤堵、周围土体形成土柱以及真空度随深度衰减等问题,考虑到预制水平排水板(PHD)在真空预压法处理软土地基中的特点,提出一种水平联合竖直排水板真空预压(PHD-PVD-VP)处理工程废浆的方法。通过4组大型室内模型试验,对工程废浆加固过程中的排水、沉降以及孔隙水压力进行监测,并借助扫描电镜得到的排水板滤膜微观图片,分析不同初始PHD真空压力下PHD-PVD-VP对工程废浆的加固效果。试验结果表明,PHD-PVD-VP处理工程废浆时减少了土颗粒径向移动速率,延缓“土柱”的形成及缓解土颗粒嵌入排水板滤膜的淤堵效应,提升了土体整体固结效果;40 kPa的初始PHD真空压力使PHD-PVD-VP对工程废浆的排水固结效果最佳,处理后土体的平均含水率和十字板剪切强度分别为40.9%和25.5 kPa,有效地缓解了PHD和PVD的淤堵并改善了土体固结的均匀性。通过微观结构分析发现,PHD初始真空压力的大小同时影响着PHD与PVD滤膜的淤堵情况,从而影响其排水性能,40 kPa的初始PHD真空压力使得两种排水板的排水性能都得到充分发挥。

深部巷道围岩裂隙注浆加固浆液扩散规律研究

目的为了解决深部巷道围岩裂隙注浆加固难题,方法采用现场矿压观测、数值模拟等方法,结果研究得到深部巷道围岩破坏特征:深部巷道呈现“顶、帮、底”全断面大变形现象,围岩破坏深度显著增加;深部巷道围岩由浅至深形成裂隙发育区、裂隙扩展区和原生裂隙区,其中裂隙扩展区裂隙较小,注入难度较大。采用数值模拟方法,分析裂隙特征、注浆压力、浆液水灰比等因素对浆液扩散特征的影响规律,结果表明:裂隙开度对浆液扩散半径影响显著,而裂隙粗糙度的影响较小;对于裂隙开度较大的裂隙发育区,采用常规注浆压力;对于裂隙扩展区,裂隙开度较小(小于0.10 mm),应采用高于10 MPa的注浆压力;浆液扩散半径与注浆压力、水灰比呈正比,但对于深部微围岩裂隙而言,注浆压力存在临界点,不应盲目增大注浆压力,选取水灰比时,应综合考虑浆液扩散半径和浆液析水效应。结论对于注浆工程而言,选取浆液配比及注浆压力时,应考虑巷道开挖后围岩裂隙开度的发育状态。

沼液配施化肥对蜜柚产量、品质及土壤重金属的影响

在福建省平和县,以8年生琯溪蜜柚为试验树,田间定位连续3年施用养猪场猪粪沼液,研究等量氮磷钾条件下不同比例沼液与化肥配施对蜜柚产量、品质及土壤重金属和盐分的影响。结果表明,与施用纯化肥(采用普通尿素、过磷酸钙和硫酸钾,每年株施N、P_(2)O_(5)和K_(2)O分别为950.0、600.0和850.0 g)相比较,沼液替代25%化肥(以氮计,不足的氮、磷、钾养分用化肥补足)和替代50%化肥处理有增产优势,同时对果实品质无负面影响,沼液替代100%化肥无增产作用且会使果实品质下降;所有沼液处理会降低裂果率;沼液替代25%化肥不会加重果实粒化率,其他沼液处理会加重果实粒化率。随沼液替代比例和施用年限的增加,土壤中Cu和Zn含量显著增加,但均低于农用地土壤污染风险管控标准(GB 15618—2018),土壤电导率随沼液替代比例的增加而增加。沼液替代25%化肥在蜜柚果园应用的综合效果较好,可在生产上推广,但更长期施用沼液的影响还需进一步评估。

电渗热固结处理顶管废弃泥浆的减量化研究

针对顶管废弃泥浆渗透性差、含水率高、承载力低等特点,采用电渗热固结法对其进行减量化研究,并探究不同温度条件下电渗热固结的处理效果。选取EKG电极板作为电极,分析在40℃、60℃、80℃等不同加热温度下,泥浆固化过程中的排水量、排水速率、温度、电流等参数的变化趋势,对比电渗热固结前后泥浆的物理力学特性变化。结果表明:电渗热固结能够有效促进泥浆的排水,提高固结效率,降低含水率,增强固化泥浆的承载力和抗剪强度;在其加热到一定程度时,裂缝进展过快,泥浆导电性减弱,加热效率降低,且加热的温度越高,加热效率越低;电渗热固结对顶管废弃泥浆减量化应用具有一定的有效性与可行性。本文的研究成果可为其实际工程应用提供借鉴与参考。

废水泥浆对陶粒加气混凝土砌块性能的影响研究

在废水泥浆中的水取代全部拌合水的条件下,探究废水泥浆中的粉体以等量取代或系数为0.65~1.05折算取代部分粉煤灰时,对陶粒加气混凝土和易性及陶粒加气混凝土砌块抗压强度、干密度、干燥收缩、导热系数的影响。研究表明,水胶比为0.45,当废水泥浆浓度为0~18%时,按等量取代后,砌块28 d平均抗压强度为5.51~5.54 MPa,干密度为728~730 kg/m~3,干燥收缩值为0.28~0.41 mm/m,导热系数为0.137~0.145 W/(m·K);当废水泥浆浓度为20%时,按系数为0.75~0.95折算取代后,砌块28 d平均抗压强度为5.18~5.43MPa,干密度为732~743 kg/m~3,干燥收缩值为0.35~0.42 mm/m,导热系数为0.146~0.178 W/(m·K),此时,砌块符合JG/T 504—2016对CA5.0B07砌块要求。