Enhanced Mn^(2+)solidification and NH_(4)^(+)-N removal from electrolytic manganese metal residue via surfactants

Electrolytic manganese metal residue(EMMR)harmless treatment has always lacked a low-cost and quick processing technology.In this study,surfactants,namely tetradecyl trimethylammonium chloride(TTC),sodium dodecyl benzene sulfonate(SDBS),sodium lignin sulfonate(SLS),and octadecyl trimethylammonium chloride(OTC),were used in the solidification of Mn^(2+)and removal of NH_(4)^(+)-N from EMMR.The Mn^(2+)and NH_(4)^(+)-N concentrations under different reaction conditions,Mn^(2+)solidification and NH_(4)^(+)-N removal mechanisms,and leaching behavior were studied.The results revealed that the surfactants could enhance the Mn^(2+)solidification and NH_(4)^(+)-N removal from EMMR,and the order of enhancement was as follows:TTC>SDBS>OTC>SLS.The NH_(4)^(+)-N and Mn^(2+)concentrations were 12.3 and 0.05 mg·L^(-1)with the use of 60.0 mg·kg^(-1)TTC under optimum conditions(solid–liquid ratio of 1.5:1,EMMR to BRM mass ratio of 100:8,temperature of 20℃,and reaction duration of 12 h),which met the integrated wastewater discharge standard(GB8978-1996).Mn^(2+)was mainly solidified as Mn(OH)_(2),MnOOH and MnSiO_(3),and NH_(4)^(+)-N in EMMR was mostly removed in the form of ammonia.The results of this study could provide a new idea for cost-effective EMMR harmless treatment.

Desulfurization of rejected electrolytic manganese metal by electroslag remelting furnace with a water-cooled electrode

Remelting rejected electrolytic manganese metal (EMM) scrap was investigated by electroslag remelting (ESR) process through industrial experiment. The results indicated that the ANF-6 slag (70 wt.% CaF_(2) + 30 wt.% Al_(2)O_(3)) and deoxidizer could promote the desulfurization of ESR manganese in an air atmosphere. Under an air atmosphere, the sulfur in the ingot decreased to 0.0534 wt.% with a desulfurization ratio of ESR manganese of 53.2% by using ANF-6 slag and water-cooled copper electrode electroslag remelting rejected EMM scrap, suggesting its efficient removal. The electroslag ingots exhibited uneven chemical composition in an air atmosphere and cooling condition of the ESR process. The metal manganese could be oxidized by electroslag remelting of rejected EMM scrap in an air atmosphere with MnO content in the final slag of 21.9 wt.%. Besides, the activity of MnO in slag increased with increasing remelting temperature, resulting in a reduction in the slag–manganese sulfur partition ratio and desulfurization ratio. Moreover, with the accumulation of sulfur in slag and the oxidation of metallic manganese liquid, the slag showed a lower cleanliness and more oxidation, leading to an increase in sulfur and oxygen content in the electroslag ingot with the increase in ingot height.

Halogen makes manganese metal batteries rechargeable

Strong interaction between positively charged Mn2+ions and solvent molecules impedes manganese plating process,enabling previous manganese metal batteries non-rechargeable.Now,an innovative halogen-mediated strategy is revealed effective to make manganese metal batteries highly reversible.

Reductive recovery of manganese from low-grade manganese dioxide ore using toxic nitrocellulose acid wastewater as reductant

The hydrometallurgical strategy of extracting Mn from low-grade Mn ores has attracted attention for the production of electrolytic manganese metal(EMM). In this work, the reductive dissolution of low-grade Mn O2 ores using toxic nitrocellulose acidic wastewater(NAW) as a reductant was investigated for the first time. Under the optimized conditions of an Mn O2 ore dosage of 100 g·L-1, an ore particle size of-200 mesh, concentrated H2 SO4-to-NAW volume ratio of 0.12, reaction temperature of 90°C, stirring speed at 160 r·min-1, and a contact time of 120 min, the reductive leaching efficiency of Mn and the total organic carbon(TOC) removal efficiency of NAW reached 97.4% and 98.5%, respectively. The residual TOC of 31.6 mg·L-1 did not adversely affect the preparation of EMM. The current process offers a feasible route for the concurrent realization of the reductive leaching of Mn and the treatment of toxic wastewater via a simple one-step process.

A novel electrolytic-manganese-residues-and-serpentine-based composite(S-EMR) for enhanced Cd(Ⅱ) and Pb(Ⅱ) adsorption in aquatic environment

Electrolytic manganese residue(EMR) is the waste slag generated from the electrolysis manganese industry.As a promising exploitable adsorbent,EMR has become a hot research topic.However,EMR’s low adsorption capacity has limited its applications as an efficient adsorbent.In this study,the EMR was mixed with serpentine and calcined(at 800℃ for 2 h) to prepare a composite adsorbent(S-EMR) with its specific surface area of 11.998 m^(2)·g^(-1)(increased compared to the original EMR) and improved adsorption capacities for Cd^(2+)(98.05 mg·g^(-1)) and Pb^(2+)(565.81 mg·g^(-1)).Kinetic studies have shown that the pseudo-first-order kinetics(PSO)model could best describe the adsorption kinetics of S-EMR for Cd^(2+)/Pb^(2+),implying that the chemisorption process is the rate-limiting step.The effects of different interfering ions on S-EMR’ s adsorption for Cd^(2+)/Pb^(2+)may be due to the difference in their electronegativity.Results of response surface methodology tests showed that pH had the highest influence on adsorption,and the removal efficiency of S-EMR reached 99.92% for Cd(Ⅱ) and 94.00%for Pb(Ⅱ).X-ray photoelectron spectroscopy(XPS) analyses revealed that chemical precipitation was the predominant mechanism for Cd^(2+)/Pb^(2+)removal,and the adsorption mechanisms were associated with ion exchange and electrostatic attraction.The results showed that S-EMR could be used as an effective adsorbent for the removal of Cd(Ⅱ)/Pb(Ⅱ) from water bodies,rendering dual benefits of pollution control and resource recovery.

堆存陈化中电解锰渣重金属形态及环境风险演化

为了探究电解锰渣堆存陈化过程对其重金属赋存形态及环境风险演化的影响规律,采用XRF、XRD和SEM等微观试验对比分析了新鲜与陈化电解锰渣的易溶盐含量、化学成分、微观形貌和相变组成等微观特性差异.此外,基于批次浸出试验和改进BCR顺序提取法评估了新陈电解锰渣中重金属和氨氮的环境风险.结果表明,在堆存陈化过程中,电解锰渣的微观结构呈松散演化,易溶盐含量由12.25%降低至4.38%,酸溶态和可还原态重金属占比逐渐减少,重金属Mn由超高风险降低至中风险,但重金属总量仍高达3.28×10^(4)mg/kg,环境风险严峻,氨氮浸出量虽有所降低,但仍然超出15.00mg/L阈值的2.54~3.84倍,部分氨氮和重金属在堆存过程中释放到周围生态中,需采取必要措施对电解锰渣进行处理.

Effects of slag composition and additive type on desulfurization of rejected electrolytic manganese metal scrap by Na2O-containing electroslag

The recycling rate of rejected electrolytic manganese metal(EMM)scrap can be increased by inhibiting the manganese metal(MM)vaporization during the remelting process with electroslag.However,if the latter is achieved by reducing the remelting temperature,the desulfurization behavior will deteriorate.Therefore,Na_(2)O-containing electroslag and metallic additive were used to increase the rejected EMM scrap recovery ratio.The respective high-temperature experiment was conducted in a MoSi_(2) electrical resistance furnace filled with fluid argon at 1673 K using five different types of electroslag with the Na_(2)O content ranging from 5.81%to 15.71%.High-purity metallic magnesium and magnesium calcium alloy additives were used as deoxidizers.The addition of Na_(2)O and metallic additives effectively promoted the desulfurization and deoxidization of MM.The removal of sulfur and oxygen by the interaction between Na_(2)O-containing electroslag melt and molten MM with metallic additive was analyzed from the thermodynamic and kinetic standpoints.The effect of Na_(2)O-containing electroslag volatilization on desulfurization and deoxidization was considered.With an increase in Na_(2)O content in the slag,the mass loss rates of Na_(2)O and electroslag rose,as well as the final sulfur partition ratio.If the Na_(2)O content volatilized in the slag melt did not exceed 10.44%,the sulfur removal ratio was increased by high sulfide capacity and CaO activity in all slags due to the addition of Na_(2)O.The rejected EMM scrap deoxidization ratio grew with the increased activity of CaO and reduced activity of Al_(2)O_(3) in the molten slag,caused by the increased Na_(2)O content in the molten slag.The addition of metallic Mg and Mg-Ca alloy indirectly promoted desulfurization and deoxidization by reducing the MnO content in the rejected EMM scrap and growing slag oxidability.The Mg-Ca alloy could also react with dissolved sulfur and oxygen,directly promoting desulfurization and deoxidization processes.The Na_(2)O content in slag should not exceed 10.44%to ensure the high desulfurization and deoxidization abilities,fluidity and low volatilization of slag.

电解锰渣库周边土壤重金属污染特征评价

中国作为全世界最大的电解锰生产国,电解锰渣堆存造成的土壤污染亟需改善。该研究在中国锰矿资源储量最大的基地——贵州省铜仁市,选取辖区公共电解锰渣库(玉屏侗族自治县蔡溪村),利用湿式消解法及改进的BCR三步提取法对Mn、Zn、Pb、Ni、Cr、Cd 6种重金属元素在电解锰渣库周边土壤中的污染特征、形态分布及风险评价进行分析讨论。Mn、Pb和Cd是对渣库周边土壤环境质量影响最大的重金属。Mn含量变化范围为356~14915 mg/kg,平均值为3828 mg/kg,超过贵州土壤背景值4.8倍。Pb和Cd的平均含量是农用地土壤国家标准风险筛选值的3.1和40.2倍。6种重金属均以可迁移的酸溶解态为主。Mn和Cd的弱酸提取态含量随距渣库坝体越近而显著增加(P<0.05)。普通Kriging空间插值结果发现Mn、Cd、Zn、Pb和Ni 5种重金属含量具有中等强度的空间相关性,其中Mn和Cd含量受到人为活动污染等随机影响较大。Mn和Cd空间分布总体呈东高西低,高值均出现在电解锰渣库坝体附近。主成分分析法显示Mn、Cd和Pb主要受电解锰渣库污染影响;Ni和Zn主要来源于附近农业活动和工业生产;Cr主要受地质背景因素影响。电解锰渣库周边土壤潜在生态风险指数为最高风险等级,其中Cd的贡献比例最大(91%)。

电解锰渣对熟石灰-矿渣体系硫酸盐激发性能研究

电解锰渣(EMR)作为一种工业固体废弃物,含有大量重金属、氨氮及硫酸盐,对环境与人体健康造成巨大危害。为解决这一问题,利用EMR富含硫酸盐的特点,将其作为硫酸盐激发剂,研究了EMR对熟石灰-矿渣体系硫酸盐激发效果、水化机理、微观结构与污染物固化机理的影响。抗压强度、XRD及SEM-EDS测试研究表明,EMR对熟石灰-矿渣体系的激发效果较好,其最佳配比为:质量分数为50%的EMR、质量分数为46%的矿渣、质量分数为4%熟石灰,3、7、28 d抗压强度分别为15.55、27.44、44.52 MPa,相比未加EMR的熟石灰-矿渣体系,3、7、28 d抗压强度分别提升了1.65、1.80、1.97倍。在EMR激发下,熟石灰-矿渣体系的水化产物包括AFt(钙矾石)、C-(A)-S-H(水化硅铝酸钙),并且这些水化产物之间相互交织形成致密网络结构;而熟石灰-矿渣体系的主要水化产物是C-(A)-S-H,且其界面区域缝隙较大。EMR-熟石灰-矿渣体系水化过程中释放的OH-及形成的水化产物AFt、AFM(单硫型水化硫铝酸钙)、C-(A)-S-H能够对EMR中的重金属、氨氮进行离子置换、吸附、封裹与沉淀,最终使该体系浸出毒性满足《污水综合排放标准》(GB 8978—1996)的排放标准。

锰电积用新型阳极研究进展

通过对铅基二元合金阳极、铅基多元合金阳极、钛基阳极、铝基阳极和不锈钢基阳极的分析,总结了各类阳极的特性。这些研究结果为锰电积用新型阳极的研发提供了重要参考,有助于推动电解金属锰行业的成本优化和效率提升。

电解金属锰制液过程中的氧化锰除铁工艺优化

电解金属锰制液工艺中,常利用氧化锰粉将Fe^(2+)氧化成Fe^(3+),以便在后续中和过程中形成氢氧化铁胶体,实现铁的去除。针对低品位氧化锰粉在生产过程中存在除铁利用率低的问题,开展了氧化锰粉除铁工艺优化研究,结果表明:当除铁锰粉粒径≤125μm,初始酸的质量浓度为6.5 g/L,反应温度为60℃,反应时间为90 min时,除铁利用率达到98.4%,实现除铁氧化锰粉的高效利用。

工业硫酸锰的净化和高纯无硒电解金属锰的制备

开发一种高纯度无硒电解金属锰的制备技术,以替代传统工艺中使用的有毒二氧化硒,对于工业应用具有重要的意义。研究通过深度净化硫酸锰溶液,并使用亚硫酸铵替代二氧化硒进行电解,利用硫化钡去除溶液中的重金属,聚合硫酸铁和二氧化锰联合净化溶液中的钙和镁杂质。结果表明,当硫化钡添加量为0.1 g/L时,锌的去除率高达98.00%;二氧化锰和聚合硫酸铁的质量比为2∶1时,净化效果最佳。亚硫酸铵的添加量控制在0.6~0.8 g/L时,电解过程稳定,所得电解锰的纯度可达99.97%,硒含量低于0.0001%。研究证实,所提出的制备工艺能够满足生产DJMnA牌号金属锰的要求,具有实际应用的可行性。

含锰废水沉淀渣资源化利用的研究

含锰废水沉淀渣是电解金属锰生产废水和渣库渗滤液处理的产物,主要以Mn、Ca、Mg的氢氧化物形态存在,可用于电解金属锰生产的制液降酸工序。结合金属锰的制液工艺,开展了含锰废水沉淀渣资源化利用的研究,研究表明:含锰废水采用石灰处理后,沉淀渣Mn含量5.77%,Ca含量32.04%,Mg含量6.44%,该渣用于电解金属锰制液工序的降酸环节,在降酸量相同的情况下,含锰废水沉淀渣的使用量为碳酸钙粉用量的2.67倍,降酸后的溶液中Fe的含量由11.58 mg/L降低至1.3 mg/L,对比碳酸钙粉降酸工艺,Fe含量降低87.6%,其他微量杂质含量基本一致,渣的锰含量低0.35%,沉淀渣用于电解金属锰降酸工艺更具优势。说明含锰废水沉淀渣用于电解金属锰制液工艺,可降低其制液辅材消耗,同时也有利于溶液杂质含量的降低,稳定溶液质量,实现了含锰废水沉淀渣的资源化利用。

堆存锰渣中重金属污染物性质及固化研究

为了解决锰渣的无害化处理,对某堆存锰渣进行了全量、形态和固化分析。结果表明:堆存锰渣中含有大量重金属污染物,且大部分污染物的可溶性形态占比较高,其中全Mn含量超过相关标准限值,浸出液中Mn^(2+)、Ni^(2+)浓度超过排放限值。选用石灰石作为固化剂对堆存锰渣进行固化后,浸出液中Mn^(2+)、Ni^(2+)的含量显著下降,当其加入质量分数为2%时,浸出液中Ni^(2+)的浓度达到排放标准要求,增至6%后Mn^(2+)浓度达标;固化后堆存锰渣中污染物的可溶性形态占比明显降低,残渣态占比升高,污染物活性显著下降,表明石灰石对堆存锰渣无害化处理有较好的效果。

电感耦合等离子体发射光谱法测定电解金属锰中的硒含量

随着电解金属锰在储能材料生产领域的应用日益广泛,生产企业和研究机构为了保障和提高锰基储能材料的性能,对电解金属锰中杂质元素的检测也提出了更为严格的要求。研究提出了一种采用电感耦合等离子体发射光谱快速测定电解金属锰中硒含量的方法,方法的线性范围为0~3.0μg/mL,线性方程为y=4303.6 x+56.269,相关系数R^(2)=1.0,加标回收率为98.99%~100.80%,精密度为0.68%~0.96%。方法具有试剂用量少、检测速度快、检出限低和精密度高等优点,为电解金属锰中硒含量的快速准确检测提供了一种新的技术途径。

Building Ultra-Stable and Low-Polarization Composite Zn Anode Interface via Hydrated Polyzwitterionic Electrolyte Construction

Aqueous zinc metal batteries are noted for their costeffectiveness,safety and environmental friendliness.However,the water-induced notorious issues such as continuous electrolyte decomposition and uneven Zn electrochemical deposition remarkably restrict the development of the long-life zinc metal batteries.In this study,zwitterionic sulfobetaine is introduced to copolymerize with acrylamide in zinc perchlorate(Zn(ClO;);)solution.The designed gel framework with hydrophilic and charged groups can firmly anchor water molecules and construct ion migration channels to accelerate ion transport.The in situ generated hybrid interface,which is composed of the organic functionalized outer layer and inorganic Clcontaining inner layer,can synergically lower the mass transfer overpotential,reduce water-related side reactions and lead to uniform Zn deposition.Such a novel electrolyte configuration enables Zn//Zn cells with an ultra-long cycling life of over 3000 h and a low polarization potential(~0.03 V)and Zn//Cu cells with high Coulombic efficiency of 99.18%for 1000 cycles.Full cells matched with MnO;cathodes delivered laudable cycling stability and impressive shelving ability.Besides,the flexible quasi-solid-state batteries which are equipped with the anti-vandalism ability(such as cutting,hammering and soaking)can successfully power the LED simultaneously.Such a safe,processable and durable hydrogel promises significant application potential for long-life flexible electronic devices.

单膜双室电沉积金属锰联产EMD的影响因素

针对传统膜电解法单独电解金属锰或电解二氧化锰(EMD)工艺存在资源利用率低、污染环境的问题,采用单膜双室电解法将金属锰与EMD进行同槽电解,且在阳极回收硫酸,并考察了阴极液硫酸铵浓度、电解液Mn^(2+)浓度、阳极液初始硫酸浓度、电流密度4个因素对电沉积效果的影响。结果表明:在阴极液硫酸铵浓度为120 g/L、电解液Mn^(2+)浓度为40 g/L、阳极液初始硫酸浓度为0.6 mol/L、阴阳两极的电流密度分别为400 A/m^(2)和800 A/m^(2)的条件下,进行6 h电解,得到阴极锰产率可达78.22%,酸回收率为62.41%,EMD产率为23.7%,电能消耗仅为5675 kW·h/t,槽电压为5.86 V。同时发现对锰产率影响最显著的因素是电流密度,对EMD产率及酸回收率影响最显著的因素是阳极液初始硫酸浓度和电流密度。在最佳实验条件下的阴极产品金属锰板表面光洁密实、具明显银白色金属光泽、晶粒分层聚集、颗粒粒度均一、并呈现蜂窝状组织,整体形态良好。

脉冲加热惰性气体熔融热导法测定电解金属锰中氮含量

采用脉冲加热惰性气体熔融热导法,使用氧氮氢分析仪测定电解金属锰中氮的含量。将电解金属锰样品置于石墨套坩埚中,在分析功率4.0 kW条件下,通过选择最佳的分析条件,用钢铁标准样品建立校准曲线,确立了电解金属锰中氮的测定方法。氮的释放完全且结果稳定性较好,实现了对电解金属锰中氮含量的快速准确测定,满足日常分析工作的要求。

电解锰行业清洁低碳改造绩效评价分析研究

以电解锰行业为例,本文介绍了该行业的发展现状及污染治理推行状况。针对行业内存在的突出环境污染问题,结合清洁低碳改造方案,构建了清洁生产关键指标评价体系,评价了清洁低碳改造取得的绩效。重点分析了2017年-2021年该行业的锰粉消耗、综合能耗、重铬酸钾消耗等关键性清洁生产指标的变化情况。分析结果显示,综合能耗由2017年的7100kW·h/t(以Mn计,下同)降低到2021年的6500kW·h/t,二氧化硒消耗也呈逐年降低趋势。对于经过多轮改造的某企业,其单位产品取水量、阳极泥产生量、锰渣中水溶性锰含量(干基)等3项评估指标都可以达到国内领先水平,在行业内处于顶尖水平,为行业减污降碳、绿色转型起到引领作用。

调控LiPF6基电解液溶剂化结构稳定富锂锰基正极界面

富锂锰基正极材料具有高比容量和低成本的优势,有望成为下一代高能量密度金属锂电池的正极材料。然而在实际应用中,其相对于金属锂高达4.8 V的充电截止电压,会引发电解液氧化分解失效,导致正极与电解液的界面恶化使得电池难以稳定循环。为此本文开发了以1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚(TTE)充当促配位溶剂的六氟磷酸锂(LiPF6)基新型高电压电解液。实验与表征结果说明,适量TTE引入后具有更多锂盐阴离子参与锂离子配位的溶剂化结构的电解液,能够在正极表面形成5 nm厚且富含氟元素的正极电解液中间相(CEI),稳定正极界面并抑制正极层状结构的退化。使用新型电解液的富锂锰基正极对金属锂扣式电池,以99.8%的平均效率循环400次后,仍有83.9%的容量保持率(0.5 C)。组装1.25 Ah的富锂锰基正极对金属锂软包电池,在0.04 C下能够提供370 Wh/kg的质量能量密度,在0.08 C下循环45次后,仍有80%的容量保持率,表现出良好的应用前景。本研究有助于推动富锂锰基正极的应用,为高能量密度金属锂电池的研发提供实验依据。