Waste acid recovery utilizing monovalent cation permselective membranes through selective electrodialysis

Selective electrodialysis(SED)has surfaced as a highly promising membrane separation technique in the realm of acid recovery owing to its ability to effectively separate monovalent ions through the utilization of a potential difference.However,the current SED process is limited by conventional commercial monovalent cation permselective membranes(MCPMs).This study systematically investigates the use of an independently developed MCPM in the SED process for acid recovery.Various factors such as current density,volume ratio,initial ion concentration,and waste acid systems are considered.The independently developed MCPM offers several advantages over the commercial monovalent selective cation-exchange membrane(CIMS),including higher recovered acid concentration,better ion flux ratio,improved acid recovery efficiency,increased recovered acid purity,and higher current efficiency.The SED process with the MCPM achieves a recovered acid of 95.9%and a concentration of 2.3 mol·L^(–1) in the HCl/FeCl_(2) system,when a current density of 20 mA·cm^(-2) and a volume ratio of 1:2 are applied.Similarly,in the H_(2)SO_(4)/FeSO_(4) system,a purity of over 99%and a concentration of 2.1 mol·L^(–1) can be achieved in the recovered acid.This study thoroughly examines the impact of operation conditions on acid recovery performance in the SED process.The independently developed MCPM demonstrates outstanding acid recovery performance,highlighting its potential for future commercial utilization.

Multi-stage Electrostatic Separation for Recovering of Aluminum from Fine Granules of Black Dross

Separation of aluminum from fine granules of black dross, which is a waste by-product in secondary aluminum production, was investigated. The separation was performed by a multi-stage electrostatic separation method. There are three stages to complete the separation, including preliminary separation, pulse charging enhancement and secondary concentration. Chemical and mineralogical compositions of collection products were analyzed and determined by X-ray diffraction(XRD) and X-ray Fluorescence(XRF). After multistage electrostatic separation, the Al2O3 content of the collection products increases from 50.74% to 69.77%.The mineralogical phase analysis indicates that the final recovery of metallic aluminum phase increases from 8%to 37%, and the aluminum oxide phase increases from 20% to 26%. The research results show the multi-stage electrostatic separation method is effective for recovering of aluminum from fine granules of black dross, and upgrades the black dross to a recoverable material.

Radial Basis Function Neural Networks-Based Modeling of the Membrane Separation Process: Hydrogen Recovery from Refinery Gases

Membrane technology has found wide applications in the petrochemical industry, mainly in the purification and recovery of the hydrogen resources. Accurate prediction of the membrane separation performance plays an important role in carrying out advanced process control （APC）. For the first time, a soft-sensor model for the membrane separation process has been established based on the radial basis function （RBF） neural networks. The main performance parameters, i.e, permeate hydrogen concentration, permeate gas flux, and residue hydrogen concentration, are estimated quantitatively by measuring the operating temperature, feed-side pressure, permeate-side pressure, residue-side pressure, feed-gas flux, and feed-hydrogen concentration excluding flow structure, membrane parameters, and other compositions. The predicted results can gain the desired effects. The effectiveness of this novel approach lays a foundation for integrating control technology and optimizing the operation of the gas membrane separation process.

Recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation: process optimization and mineralogical study

Currently, the majority of copper tailings are not effectively developed. Worldwide, large amounts of copper tailings generated from copper production are continuously dumped, posing a potential environmental threat. Herein, the recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation was conducted; process optimization was carried out, and the corresponding mineralogy was investigated. The reduction time, reduction temperature, reducing agent (coal), calcium chloride additive, grinding time, and magnetic field intensity were examined for process optimization. Mineralogical analyses of the sample, reduced pellets, and magnetic concentrate under various conditions were performed by X-ray diffraction, optical microscopy, and scanning electron microscopy-energy-dispersive X-ray spectrometry to elucidate the iron reduction and growth mechanisms. The results indicated that the optimum parameters of iron recovery include a reduction temperature of 1150A degrees C, a reduction time of 120 min, a coal dosage of 25%, a calcium chloride dosage of 2.5%, a magnetic field intensity of 100 mT, and a grinding time of 1 min. Under these conditions, the iron grade in the magnetic concentrate was greater than 90%, with an iron recovery ratio greater than 95%.

Evaluation of Chromite Recovery from Shaking Table Tailings by Magnetic Separation Method

This study aimed to evaluate the chromite recovery from shaking table tailings of Forumad plant by a dry high-intensity magnetic separation. The average feed grade of chromium trioxide (Cr2O3) was 7.62% by XRF. Also, different mineral phases were determined by XRD, identifying the presence of Chrysotile, Augite, Albite, Chlorite and Chromite. Although the Forumad plant usually applies gravity methods utilizing the specific gravity difference between chromite and other gangue minerals, this study applied magnetic separation utilizing the paramagnetic nature of chromite crystals to recover chromite from tailings. 27 tests for 3 factors in 3 levels designed by the Taguchi method with design expert 12 software to determine the optimum conditions for the grade and recovery. Finally, the best condition was identified at 10,000 gauss (or 1 tesla) in the magnetic field intensity, 1 kg/min feeding rate, and 40 rpm drum rotating speed which produced a concentrate with 34.65% Cr2O3 and 59.42% recovery.

Comprehensive recovery of lead, zinc, and iron from hazardous jarosite residues using direct reduction followed by magnetic separation

Lead, zinc, and iron were recovered from jarosite residues using direct reduction followed by magnetic separation. The influence of the coal dosage, reduction temperature, and reduction time on the volatilization rates of lead and zinc and the metallization rate of iron were investigated. The results show that the volatilization rates of lead and zinc were 96.97% and 99.89%, respectively, and the iron metallization rate was 91.97% under the optimal reduction roasting conditions of a coal dosage of 25.0 wt% and reduction roasting at 1250°C for 60 min. The magnetic concentrate with an iron content of 90.59 wt% and an iron recovery rate of 50.87% was obtained under the optimum conditions in which 96.56% of the reduction product particles were smaller than 37 μm and the magnetic field strength was 24 k A/m. Therefore, the results of this study demonstrate that recovering valuable metals such as lead, zinc, and iron from jarosite residues is feasible using the developed approach.

Algorithm for source recovery in underdetermined blind source separation based on plane pursuit

In order to achieve accurate recovery signals under the underdetermined circumstance in a comparatively short time,an algorithm based on plane pursuit(PP) is proposed. The proposed algorithm selects the atoms according to the correlation between received signals and hyper planes, which are composed by column vectors of the mixing matrix, and uses these atoms to recover source signals. Simulation results demonstrate that the PP algorithm has low complexity and higher accuracy as compared with basic pursuit(BP), orthogonal matching pursuit(OMP), and adaptive sparsity matching pursuit(ASMP) algorithms.

Chromatographic separation and recovery of Zn(Ⅱ)and Cu(Ⅱ)from high-chlorine raffinate of germanium chlorination distillation

An anion-exchange-based chromatographic separation approach was developed to selectively recover zinc and copper from the high-chlorine raffinate generated in the process of germanium chlorination distillation using 717 resins based on the coordination difference between Zn^(2+)/Cu^(2+)and Cl^(-).The theoretical calculation and spectroscopic analyses suggested that the coordination between Zn^(2+)and Cl^(-)is much stronger than that between Cu^(2+)and Cl^(-),and the Cl-concentration significantly affects Zn(Ⅱ)and Cu(Ⅱ)species.The factors involving Cl-concentration,resin dosage,shaking speed,and temperature were investigated to determine the optimal condition,and the maximum separation factor of Zn/Cu reached as high as 479.2.The results of the adsorption isotherms,adsorption kinetics,SEM,FTIR,and XPS analyses indicated that the process followed the monolayer uniform chemisorption.Through the continuous adsorption experiments,Zn(Ⅱ)and Cu(Ⅱ)in the high-chlorine raffinate were separately recovered,allowing the reuse of residual waste acid and germanium.

Study on Metals Recovery from -0.074 mm Printed Circuit Boards by Enhanced Gravity Separation

Nowadays study on reutilization of discarded printed circuit boards (PCBs) has great significance for achieving secondary resources recycling and preventing environmental pollution. Physical methods show great potential and advantages on discarded PCBs reutilization, compared with chemical and biological methods. However for the particles of 0.074 mm PCBs, little work has been done in the past because of lower separation efficiency and recovery. In this work, the conundrum of 0.074 mm PCBs reutilization was resolved successfully with the help of Falcon concentrator. Separation mechanism for fine particles with different mass densities in a Falcon centrifugal concentrator was analyzed. The main factors such as magnitude of rotation frequency (centrifugal acceleration), anti-charge water pressure and feeding concentration were studied, and interaction of different factors was analyzed using DesignExpert software. The experimental results show that metals grade of 0.074 mm PCBs and integration efficiency were obtained as 76.89% and 80.77% respectively when feeding concentration was 40 g/L with water pressure of 0.01 MPa and rotation frequency of 50 Hz.

Speech Signal Recovery Based on Source Separation and Noise Suppression

In this paper, a speech signal recovery algorithm is presented for a personalized voice command automatic recognition system in vehicle and restaurant environments. This novel algorithm is able to separate a mixed speech source from multiple speakers, detect presence/absence of speakers by tracking the higher magnitude portion of speech power spectrum and adaptively suppress noises. An automatic speech recognition (ASR) process to deal with the multi-speaker task is designed and implemented. Evaluation tests have been carried out by using the speech da- tabase NOIZEUS and the experimental results show that the proposed algorithm achieves impressive performance improvements.

Hollow Fiber Supported Liquid Membrane for Separation and Recovery of ^152+154Eu and ⁹⁰Sr from Aqueous Acidic Wastes

Separation and recovery of 152+154Eu and 90Sr from radioactive waste using tracer concentration from active material from waste tank in the ET-RR1 Egypt via hollow fiber supported liquid membrane (HFSLM) were achieved. The Polypropylene was used as supporter to carrier 0.5M Cyanex301/kerosene (bis(2,4,4-trimethylpentyl)dithiophosphinic acid and 0.1MEDTA as stripping of 152+154Eu and 90Sr ions from nitrate medium at pH ~3.6. The separation factor was found to be ~4 for 152+154Eu over 90Sr. The aqueous feed of mass transfer coefficient (ki) and the organic mass transfer coefficient (km) were calculated to be (1.52 and 4.5) × 10﹣2cm/s, respectively. In addition, the mass transfer modeling was performed and the validity of the developed model from experimental data was found to join in well with the theoretical values when the Cyanex301 concentration is higher than 1% (v/v). The number of cycles evaluated for complete separation of 152+154Eu and 90Sr is five cycles.

Recovering metals from printed circuit board scrap by a mechanical separation process

A mechanical separation process was developed for recovering metals from printed circuit board(PCB) scrap;it included three steps:impact crushing,sieving and fluidization separation.The mechanism of the technique was based on the difference in the crushabilities of metallic and nonmetallic materials in the PCBs that led to the concentrated distribution of metals in particles of larger sizes and nonmetals mostly in particles of smaller sizes.It was found that crushed PCB particles from 0.125 mm to 1.000 mm contained about 80% of metals in the PCBs.Metals acquired satisfactory liberation in particles smaller than 0.800 mm.The crushed PCB particles were sieved into fractions of different size ranges.Each fraction separately went through a gas-solid fluidized bed operating at a selected optimal gas velocity for the specific size range.Approximately 95% of metals in printed circuit board particles from 0.125 mm to 0.800 mm was recovered by the gas-fluidized bed separator at the selected optimal gas velocity.However,separation of metals from particles smaller than 0.125 mm was not satisfactory.Further study is needed on metal recovery from fine particles.

Recovery and Upgrading of Phosphorus from Digested Sewage Sludge as MAP by Physical Separation Techniques

Physical separation apparatuses;a vibrating screen, a 4-inch hydrocyclone and a Multi-Gravity Separator (MGS) were used to recover phosphorus as MAP (magnesium ammonium phosphate, MgNH4PO4.6H2O) from anaerobic digested sludge of two sewage-treatment plants A and B. For plant A, the MAP grade increased from 0.08% to 88.9% with 90.4% recovery and for plant B, the grade increased from 0.11% to 73.8 with 93.2% recovery. The collected MAP products containing impurities such as organic materials and heavy metals were further upgraded through dry and wet magnetic separation tests at different magnetic flux densities. A dry magnetic separator was tested on both MAP products (MAP-A and MAP-B), while the wet magnetic separation process was exclusively experimented for the removal of impurities from MAP-B. Feed samples, as well as magnetic and nonmagnetic products were analyzed by absorption spectroscopy, XRD, ICP-AES, polarizing microscope observation, and SEM-EDX. The grade of MAP products could be improved by about 4% - 9% after magnetic separation (the most appropriate magnetic force being 15,000 Gauss). During both dry and wet magnetic separation processes, not only heavy metals have been removed, but also nonmagnetic constituents like Al, Ba, and Ca. This may be attributed to the attachment of fine magnetic particles on the nonmagnetic surfaces, rendering them magnetic properties.

One-step crosslinking preparation of tannic acid particles for the adsorption and separation of cationic dyes

In this study,a new tannic acid adsorbent(ethylene glycol diglycidyl ether crosslinked tannic acid,TAEGDE)for adsorptive removal of dyes from water was prepared using EGDE as a cross-linking agent.The resultant TA-EGDE was in particulate form with rough surface morphology and a diameter ranging from 10 to 30μm.The adsorption performance of the TA-EGDE was evaluated in a flow-through mode using water samples contaminated with methylene blue(MB)and two-component mixed dyes,respectively.The TA-EGDE provided adsorption capacity up to 721.8 mg·g^(-1)at 65°C for MB.It showed a high removal efficiency(99%)of MB(50 mg·L^(-1))from the water sample and could recovery 90%of the adsorbed MB by eluting with acidic ethanol aqueous solution.The excellent adsorption of MB and neutral red on the TA-EGDE may be the result of the synergy of electrostatic interaction andπ-πinteraction.Furthermore,the TA-EGDE could separate dyes from water samples contaminated with twocomponent mixed dyes with a separation coefficient ranging from 1.8 to 36.5.The anionic TA-EGDE would be an effective adsorbent to remove and recycle dyes from the contaminated water.

Field Utilization of Dried Water Hyacinth for Phosphorous Recovery from Source-Separated Human Urine

This research demonstrated the feasibility of converting source-separated human urine into a solid fertilizer by means of continuous absorption and solar thermal evaporation using dried water hyacinth as adsorbent. In a preliminary experiment, the dried petioles of water hyacinth (DWH) absorbed urine in a mean rate of 18.78 ml·g-1 within 7 d, retrieving about 3.46% urine dissolved solids (UDS). In an advanced experiment, the DWH’s capacity of urine absorption declined from an initial 2.73 L·kg-1·d-1 to 0.68 L·kg-1·d-1, with a requirement of material change in about 25 effective days and an average ratio of 25 (L) to 1 (kg). Phosphorus (P2O5) concentration in the adsorbent increased from 0.46% (material baseline) to 3.14% (end product), suggesting a satisfactory recovery of the element. In field application, the urine was discharged, not in wet weather, onto the DWH via a tube connected to a waterless urinal. There are several ways to use the UDS-DWH as P(K)-rich fertilizer, e.g., making soluble fertilizer for foliage spraying to encourage prolific flowering and fruiting. Apparently, utilization of water hyacinth waste to recover dissolved plant nutrient elements from source-separated urine will benefit the environment in a wide range of perspectives. The herein innovative use of water hyacinth is also expected to be useful in the recycling of certain dissolved hazardous materials.

基于ERAS理念下产后乳胀护理方案对母婴分离产妇心理及泌乳的影响

目的探究加速康复外科医学(ERAS)理念引导下的产后乳胀护理方案对母婴分离的产妇泌乳及心理的影响。方法选取2022年8月至2023年8月于商丘市第一人民医院分娩且母婴分离的160例产妇作为研究对象,采用随机数表法分为对照组和观察组各80例。对照组产妇实施常规产后乳胀护理方案,观察组产妇采取ERAS理念引导下的产后乳胀护理方案,两组产妇均接受1周的护理干预。比较两组产妇干预1周后的泌乳时间、泌乳量、乳房肿胀程度;采用视觉模拟评分法(VAS评估两组产妇干预前、干预3 d、干预1周后乳房的胀痛严重程度;并比较两组产妇干预前、干预1周后的心理状况评分[状态-特质焦虑量表(STA-I)和爱丁堡产后抑郁量表评分(EPDS)]和健康状况调查问卷(SF-36)评分;采用Spearman相关分析法分析乳房肿胀程度与心理状态的相关性。结果观察组产妇的泌乳时间为(30.22±5.81)h、明显早于对照组的(46.38±7.59)h,泌乳量、Ⅰ级乳房肿胀程度占比分别为(469.51±22.31)mL、50.00%,明显多(高)于对照组的(337.81±33.17)mL、31.25%,差异均有统计学意义(P<0.05);干预3 d和1周后,观察组产妇的VAS评分分别为(3.04±0.99)分、(1.05±0.38)分、明显低于对照组的(4.33±1.02)分、(2.82±0.85)分,差异均有统计学意义(P<0.05);干预1周后,观察组产妇的STA-I、EPDS评分分别为(30.25±3.05)分、(3.76±1.05)分,明显低于对照组的(38.11±3.78)分、(6.89±1.83)分,SF-36评分为(88.51±4.38)分,明显高于对照组的(78.36±4.25)分,差异均有统计学意义(P<0.05);经Spearman相关分析结果显示,产妇乳房肿胀程度与STA-I和EPDS评分均呈正相关(r=0.160、0.234,P<0.05)。结论ERAS理念护理方案可改善母婴分离产妇的泌乳异常、胀痛,减轻焦虑抑郁,提升生活质量。

玻璃分相联用机械化学法脱除废旧含铅玻璃中重金属铅

传统分相法采用热酸浸提工艺脱除CRT锥玻璃分相产物中重金属铅,酸浸过程强酸消耗量大,废酸无法回用,易引发酸污染。目的 为了绿色、高效回收CRT锥玻璃分相产物中重金属铅,方法 采用乙二胺四乙酸(EDTA)作为浸提剂,通过机械化学法研究锥玻璃中重金属在快速分相和机械活化浸出过程中的迁移转化规律,揭示影响重金属脱除率的主要因素和作用机制。结果 结果表明:在分相处理过程中锥玻璃所含Pb,K,Ca等元素主要富集在呈连通结构的富B_(2)O_(3)相中。在随后湿法球磨浸提过程中,分相产物中富B_(2)O_(3)相在机械活化作用下快速溶解到水中,同时富B_(2)O_(3)相中所含金属离子与EDTA形成可溶络合物,且可从分相产物中脱除。锥玻璃所含Pb,K,Ca等金属脱除率随EDTA添加量增大、球磨转速提高、球磨时间延长等不断提升,但随液固比增大呈先升高后降低趋势。当EDTA添加量(质量分数,下同)为80%,球磨转速500 rpm,液固比0.8时,球磨处理30 min,分相产物中Pb,K,Ca,Al脱除率分别达到98.79%,94.92%,95.17%,65.71%,获得SiO_(2)质量分数超过92%的高硅氧玻璃粉末。结论 研究结果可为含重金属玻璃绿色、高附加值利用提供借鉴与参考。

变压吸附分离技术在催化干气乙烯回收中的应用

介绍了深冷分离技术、吸收分离技术和变压吸附分离技术3种催化干气乙烯回收技术。某石化公司炼油结构调整,催化干气产能由15×10^(4) t/a扩至21×10^(4) t/a,考虑变压吸附分离技术操作简单、无需辅助原料,操作条件变化后装置运行能快速平稳,以及综合能耗低等优势,仍继续采用该技术。根据扩能改造设计原则,将原两段法工艺改为一段法工艺,并将同时处于抽空步骤的塔数由2塔增加为3塔,处于吸附步骤的塔数由4塔增加为5塔。结果表明,产品质量相当时,扩能改造后综合能耗降低约14%,运行指标优于改造前。在减少碳排放的背景下,变压吸附分离技术因综合能耗低于其他技术,更具应用优势。

功率超声对废旧锂离子电池资源化回收利用过程的影响研究进展

近些年,随着电动汽车行业的快速发展,电动汽车动力电池常用的锂离子电池废弃物保有量也随之激增。废旧锂离子电池的资源化回收利用不仅可以避免固废堆放导致的环境问题,还可以为新电池的制造提供原材料。功率超声被证明是强化废旧锂离子电池资源化回收利用的一种有效手段,独特的物理和化学效应是产生强化效果的主要机制。本文在介绍超声空化理论的基础上论述了超声波强化废旧锂离子电池资源化回收利用的路径,并综述了超声波辅助技术在废旧锂离子电池金属集流体表面电极材料剥离过程、电极材料资源化回收过程、电极材料修复过程中的应用与研究进展。最后,论述了超声波辅助技术在工业化应用中存在的不足,展望了超声波在废旧锂离子电池资源化回收利用中工业化应用的前景。

河南某含金银硫化铜矿选矿试验研究

对河南某含金银硫化铜矿开展了工艺矿物学和选矿试验研究。结果表明:矿石中主要有用元素铜含量为0.82%,伴生的有益组分为硫、金和银,主要有用金属矿物为黄铜矿、辉铜矿和黄铁矿,脉石矿物主要为石英。试验以新型药剂TB1021为铜硫分离捕收剂,采用混合浮选—铜硫分离工艺获得铜精矿和硫精矿,硫精矿再经摇床重选回收部分微细粒铜精矿。混合浮选采用丁基黄药和丁铵黑药组合捕收剂,总药剂用量为120 g/t,采用一粗两精三扫工艺流程;铜硫分离浮选采用新型捕收剂TB1021,采用一粗三精三扫工艺流程。最终获得铜品位为15.21%、铜回收率为80.13%,金品位为3.02 g/t、金回收率为66.51%,银品位为160.43 g/t、银回收率为41.82%的铜精矿,以及硫品位为49.13%、回收率为54.34%的硫精矿。