Separation of manganese from calcium and magnesium in sulfate solutions via carbonate precipitation

The separation of manganese from sulfate solutions containing 14.59 g/L Mn2+, 1.89 g/L Mg2+ and 1.54 g/L Ca2+ was preformed successfully by carbonate precipitation. The results of thermodynamic analysis and tests indicate that carbonate precipitation holds better selectivity for manganese over magnesium than hydroxide precipitation and the feeding method is the most critical factor for minimizing the co-precipitation of calcium and magnesium. Furthermore, with adding MnSO4 solution to NH4HCO3 solution, the effects of the initial NH4HCO3 concentration, NH4HCO3 amount, solution pH value, reaction temperature and time on carbonate precipitation were evaluated and the optimum precipitation conditions were obtained. Under the optimum conditions, the precipitation rates of Mn2+, Ca2+ and Mg2+ are 99.75%, 5.62% and 1.43%, respectively. Moreover, the prepared manganese carbonate was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX). The results demonstrate that the product can be indexed to the rhombohedral structure of MnCO3.

Bio-cementation for tidal erosion resistance improvement of foreshore slopes based on microbially induced magnesium and calcium precipitation

In most coastal and estuarine areas,tides easily cause surface erosion and even slope failure,resulting in severe land losses,deterioration of coastal infrastructure,and increased floods.The bio-cementation technique has been previously demonstrated to effectively improve the erosion resistance of slopes.Seawater contains magnesium ions(Mg^(2+))with a higher concentration than calcium ions(Ca^(2+));therefore,Mg^(2+)and Ca^(2+)were used together for bio-cementation in this study at various Mg^(2+)/Ca^(2+)ratios as the microbially induced magnesium and calcium precipitation(MIMCP)treatment.Slope angles,surface strengths,precipitation contents,major phases,and microscopic characteristics of precipitation were used to evaluate the treatment effects.Results showed that the MIMCP treatment markedly enhanced the erosion resistance of slopes.Decreased Mg^(2+)/Ca^(2+)ratios resulted in a smaller change in angles and fewer soil losses,especially the Mg^(2+)concentration below 0.2 M.The decreased Mg^(2+)/Ca^(2+)ratio achieved increased precipitation contents,which contributed to better erosion resistance and higher surface strengths.Additionally,the production of aragonite would benefit from elevated Mg^(2+)concentrations and a higher Ca^(2+)concentration led to more nesquehonite in magnesium precipitation crystals.The slopes with an initial angle of 53°had worse erosion resistance than the slopes with an initial angle of 35°,but the Mg^(2+)/Ca^(2+)ratios of 0.2:0.8,0.1:0.9,and 0:1.0 were effective for both slope stabilization and erosion mitigation to a great extent.The results are of great significance for the application of MIMCP to improve erosion resistance of foreshore slopes and the MIMCP technique has promising application potential in marine engineering.

Flotation separation of spodumene and albite with activation of calcium ion hydrolysate components

It is difficult to separate spodumene and albite by flotation with calcium ion as activator.In this study,microflotation experiment,solution chemistry calculation,density functional theory(DFT)calculation and X-ray photoelectron spectroscopy(XPS)analysis were conducted to investigate the effect mechanism of c alcium hydrolysate on the flotation separation of spodumene and albite.Results show that the weak interaction intensity of Ca^(2+)with O atoms on the mineral surface makes it difficult to activate minerals effectively.The O atom in the hydroxyl group of Ca(OH)^(+)and Ca(OH)_(2)can be strongly bonded with Al atom on the mineral surface,which greatly improves the adsorption strength.After the activation of Ca(OH)^(+),the adsorption forms of collectors on the surface of spodumene and albite are quite different,and the adsorption intensity on the surface of spodumene is higher,which is conducive to the flotation separation of spodumene and albite.After the action of Ca(OH)_(2),the adsorption of the collector on the albite surface is stronger than that of spodumene,which is not conducive to the flotation separation of the two minerals.By adjusting the initial concentration of calcium ions and pulp pH,Ca(OH)^(+)is the main active component,which is the key to improve the separation effect of spodumene and albite.

Exploration of amino trimethylene phosphonic acid to eliminate the adverse effect of seawater in molybdenite flotation

In this investigation,a chelating agent of amino trimethylene phosphonic acid(ATMP) was introduced to eliminate the adverse effect of seawater in molybdenite flotation.Microflotation results presented that high flotation recovery of molybdenite was achieved in freshwater using kerosene as the collector,but it was significantly decreased in the presence of seawater when pH> 9.5.Among the main ions in seawater,magnesium and calcium ions played a more detrimental role than others.After the addition of ATMP,molybdenite floatability can restore in seawater.Zeta potential distribution and solution chemistry calculation results illustrated that the decreased molybdenite floatability was attributed to the interaction of positive Mg(OH)_(2)(s)(major) and CaOH^(+)(minor) components with the molybdenite surface.The magnesium/calcium ions of positive components of Mg(OH)_(2)(s) and CaOH^(+) interacted with the ionized species of ATMP and then produced ATMP-calcium/magnesium complex,leading to the electrostatic repulsion between molybdenite and ATMP-calcium/magnesium complex that was restoring the molybdenite flotation.Hence,the ATMP can be utilized as an appropriate reagent to improve molybdenite flotation in seawater.

Formation of magnesium calcite mesocrystals in the inorganic environment only by using Ca^(2+)and Mg^(2+)and its biological implications

Magnesium calcite(Mg-calcite)mesocrystal is widespread in the biominerals with specific functions.Until now,it remains challenging to obtain Mg-calcite mesocrystals without organic additives and the formation mechanism of Mg-calcite mesocrystals in the ocean is not clear yet.We report here the synthesis of corn-like Mg-calcite mesocrystals from pure amorphous calcium carbonate(ACC)via a facile method only by using Ca^(2+)and Mg^(2+).The obtained Mg-calcite is composed of many nanocubes with common crystallographic orientation,which shows very good single crystal feature.In the crystallizing procedure,the ACC nanospheres rapidly agglomerate into Mg-calcite corn-like mesocrystal by oriented attachment(OA)in a certain direction,which belongs to the non-classical nucleation.By this method,the molar ratio of Ca^(2+)and Mg^(2+)plays a vital role in the whole crystallization procedure,which may shed a new light on disclosing the mechanism behind for the effect of seawater in the formation of biological Mg-calcite in nature.

燃煤锅炉烟气湿法脱硫废水中重金属及钙镁离子沉淀规律研究

燃煤锅炉烟气湿法脱硫废水中的重金属及钙镁等离子危害较大,开展其沉淀去除规律的研究有利于废水中有用元素的资源化回收和废水的回用。采用碱液沉淀法对脱硫废水进行分级处理,对沉淀产物采用SEM-EDS等手段进行表征。结果表明,采用氢氧化钙作为沉淀剂可以实现去除重金属、回收镁资源及去除氟化物和降低废水硬度等多种目标。在去除重金属离子的过程中,当脱硫废水pH值为9.0~9.5时,废水中的重金属离子可得到有效去除且达到污水排放标准,镁离子几乎没有损失,钙增加率也较低,仅为4.6%以下;将废水pH值调整为9.5~9.7可有效回收废水中的镁元素,镁的回收率在62%以上,回收效果较好。在碱性条件下,向废水中投加Na_(2)CO_(3)可有效降低废水中的钙离子和残留的镁离子,实现废水降硬的目标。不同pH值下沉淀物的SEM-EDS能谱显示,对脱硫废水进行梯级pH处理可以达到分级去除重金属污染物和回收镁元素的目标。通过对脱硫废水中重金属及钙镁结垢离子的沉淀规律研究,实现了废水的分质分盐有用成分的资源化回用,避免了产生杂盐危废造成二次污染的可能,达到了脱硫废水的零排放的目标。

低碱条件下糊精与钙离子协同作用对闪锌矿与黄铁矿浮选分离的影响

闪锌矿与黄铁矿的浮选分离大多在高碱条件下进行,但这会导致药剂用量大、设备腐蚀严重等问题,为此,采用清洁高效的有机抑制剂糊精作为黄铁矿的抑制剂,通过矿物表面润湿性检测、吸附量测试以及红外光谱检测阐明糊精与矿物之间的作用机理,并利用浮选溶液化学理论分析钙离子、糊精与黄铁矿三者之间的吸附方式。研究结果表明:在弱碱性条件下,糊精单独作用时,对黄铁矿的抑制效果不佳,但加入钙离子后,糊精对黄铁矿的抑制作用显著增强;在弱碱性条件下,钙离子会以Ca(OH)^(+)的形式强烈地吸附在黄铁矿表面,同时,Ca(OH)^(+)与糊精之间也具有很强的吸附力,促进糊精在黄铁矿表面的吸附,从而加强了糊精对黄铁矿的抑制,实现闪锌矿与黄铁矿的浮选分离。

微咸水-腐植酸肥耦合滴灌条件下钙镁离子质量浓度对灌水器堵塞的影响

【目的】探明腐植酸肥施用条件下不同钙镁离子质量浓度对灌水器堵塞物质形成的影响效应与作用机制。【方法】以微咸水中钙镁离子耦合腐植酸肥滴灌为研究对象,选取4种不同额定流量(1.6、1.1、1.4、1.75 L/h)的非压力补偿内镶贴片式灌水器(FE1—FE4),其中设置3组钙离子质量浓度微咸水处理,离子质量浓度分别为100、150、200 mg/L(G1、G2、G3),3组镁离子质量浓度微咸水处理,离子质量浓度分别为100、150、200 mg/L(M1、M2、M3),以地下微咸水灌溉为对照(CK),研究不同离子质量浓度的灌水器平均流量(Dra)、滴灌系统灌水器的堵塞率分布、灌水器堵塞物质干质量(DW)动态变化规律,并分析了灌水器内部堵塞物质矿物组分。【结果】与CK相比,G1、G2、G3、M1、M2、M3处理的Dra分别降低了21.58%~29.68%、35.02%~39.71%、45.62%~55.68%、14.25%~20.41%、24.89%~45.69%、35.22%~56.75%,堵塞物质干质量分别增加了124.62%~178.49%、174.23%~230.33%、235.59%~270.09%、67.14%~120.28%、136.96%~191.18%、203.54%~213.35%。与G1、G2、G3处理相比,质量浓度相同镁离子处理M1、M2、M3处理的堵塞物质干质量分别降低了16.41%~27.26%、4.77%~13.60%、6.82%~15.34%。【结论】钙镁离子质量浓度的增加均显著加剧了灌水器的堵塞;在相同离子质量浓度条件下,镁离子处理显著减少了灌水器内堵塞物质的总量,因此镁离子在一定程度上能够降低灌水器堵塞风险。

离子微聚式物理除垢在油田供热系统中的应用

油田供热站锅炉,反冲洗水富含置换出来的钙镁离子,在高温下,造成反冲洗水管道结垢严重。通过介绍离子微聚式物理除垢技术原理,根据该技术在油田的应用分析,证实该技术在防垢除垢上的有效性,通过现场应用分析,可以看出离子微聚式防垢除垢效果明显,适用于污水排放管道系统。

钙镁离子对白云石浮选矿浆流变性的影响研究

磷矿反浮选脱镁过程中,白云石溶解和回水循环利用导致矿浆中钙镁离子增多,影响白云石的浮选行为,进而影响磷灰石与含钙脉石矿物的分离,因此调控含钙脉石矿物浮选行为的研究是磷矿石分选的研究热点。本研究以常见的含钙脉石矿物——白云石为对象,在不同钙离子和镁离子浓度下进行单矿物浮选试验、矿物颗粒分布和矿浆黏度测试,分析了钙离子和镁离子对白云石浮选流变性的影响,结果表明:弱酸性条件下,钙镁离子在改变矿浆黏度的同时也能影响浮选结果;钙离子对白云石有一定抑制作用,随着钙离子浓度升高,白云石上浮率先降低后有一定程度的上升,矿浆黏度则表现出先上升后下降的趋势;镁离子可以活化白云石上浮,随着镁离子浓度升高,白云石的上浮率先增加后趋于稳定,矿浆黏度表现出先下降后稳定的趋势。

褐藻胶生产废钙水处理及回用方法研究

作为一种天然产物,因使用安全、易加工及稳定性好等优良的性质,褐藻胶在食品、保健品、医药等健康产业中的需求日益增加。但是,褐藻胶生产过程中水资源需求量大,同时也排放大量的废水。每生产1 t褐藻酸钠消耗大约1000 t淡水,排放约900 t废水,其中,约90%的废水为废钙水。综述废钙水的处理技术和回用方法,分析废钙水处理及回用存在的问题,为废钙水的处理回用技术的发展提供参考。

浅谈本科生应如何开展创新创业项目——以化工组项目为例

大学生应积极响应国家号召,充分利用高校提供各类资源,申报大学生创新创业训练项目,从而科研实践中不断提高个人创新创业能力。项目组成员在经过大量文献资料的阅读、专业课程的学习后,选择以膜处理污水处理工艺为切入点,研究钙镁离子阻垢产物的相关特性。此次科研实践活动让项目组成员收获颇多,在锻炼个人科研综合素质的同时,也教会了成员们科研工作离不开团队合作的理念,为项目组成员今后学习工作产生深远影响。

溶剂萃取法去除硫铵废水中钙镁的实验研究

为了去除硫酸铵废水中的钙、镁离子,保证后续水处理工艺的顺行,提高硫酸铵固体的质量,回收镁资源,实验用溶剂萃取法去除硫酸铵废水中的钙、镁离子。使用P 204和煤油作为萃取剂,调节硫酸铵废水pH值及P 204的皂化度,实现硫酸铵废水中钙、镁的分步去除。通过确定溶液pH值、相比等实验条件,为此方法的产业化应用提供数据支撑。

镁离子调控无定形碳酸钙制备一水碳酸钙结晶过程

无定形碳酸钙(Amorphous Calcium Carbonate,ACC)在生物矿化中具有重要作用,其结晶过程受到了人们广泛的关注。镁离子(Mg^(2+))能够有效调控ACC的结晶转变过程,但其调控ACC转变为一水碳酸钙(Monohydrocalcite,MHC,CaCO_(3)·H_(2)O)晶体的作用机制并不清楚。本研究使用Mg^(2+)作为添加剂,采用自动电位滴定系统,原位研究了ACC到MHC的转变过程,发现Mg^(2+)能够提升ACC的稳定性,抑制方解石和球霰石的形成。ACC向MHC转变的过程中,首先发生部分溶解,随着Ca^(2+)被消耗,溶液中Mg/Ca摩尔比提高。Mg^(2+)进一步吸附在ACC颗粒表面,抑制ACC表面溶解,促使其从内部溶解,形成富含Mg^(2+)的中空结构以及尺寸更小的纳米颗粒。随后,MHC通过颗粒聚集的方式结晶生长。这些结果解释了Mg^(2+)调控ACC通过非经典结晶方式转变为MHC的机理,加深了对以ACC为前驱体的生物矿化机制的理解。

工业烟气镁法脱硫废水处理及硫酸盐资源化利用

利用脱硫废水制备七水硫酸镁晶体是一种低成本且环保的晶体生产方法,但是废水中含有的杂质会影响所得到的晶体品质。文章对废水进行两步蒸发法可控去除金属杂质离子及钙离子后,在结晶区析出硫酸镁。实验结果表明:脱硫废水经Fenton氧化处理和活性炭吸附脱色处理以及两步蒸发法去除钙离子后,再经过可控蒸发、过三次母液循环得到晶体并对其进行分析。Mg^(2+)含量不低于17.22%,Ca^(2+)含量不高于0.11%,SO_(4)^(2-)含量不低于65.15%。XRD分析表明,脱硫废水处理后得到的七水硫酸镁产品符合行业标准HGT 2680—2009要求。

废旧锂离子电池回收过程中钙镁渣制备电池级碳酸锂研究

以废旧锂离子电池回收过程中产生的钙镁渣为原料,通过复分解浸出-净化-沉锂-碳化分解工艺制备电池级碳酸锂。结果表明,在MgSO_(4)·7H_(2)O用量为理论量的1.1倍、初始pH值1.5、反应时间2.0 h、固液比1∶6、反应温度90℃、终点pH值3.5条件下,Li浸出率为98.39%,浸出液中Li质量浓度为18.03 g/L。浸出液通过树脂除氟、碱液除杂、碳酸钠沉锂,制备出纯度为95.11%的粗制碳酸锂。粗制碳酸锂通过碳化-树脂除钙镁-热解工艺制备出质量分数为99.64%的电池级碳酸锂。该工艺锂回收率为95.08%,经济价值高,具有良好的工业应用前景。

盐酸中Ca^(2+)、Mg^(2+)、Fe^(3+)含量超标的原因及处理

介绍了盐酸中Ca^(2+)、Mg^(2+)、Fe^(3+)含量超标原因的快速排查及处理措施。

两碱法卤水净化影响因素研究

以低硝型卤水为研究对象,利用“Na OH-Na_(2)CO_(3)”法对卤水中钙镁离子净化进行深入研究,通过跟踪反应时间、反应温度、过碱量、两碱添加顺序等对净化效果及精卤中残留碳酸根离子浓度影响,来确定合理工艺条件,为生产应用提供参考。

多流路在线分析仪在盐水精制中的应用

介绍了盐水精制过程中使用的卤水浓度在线分析仪、钙镁含量在线分析仪、硫酸根含量在线分析仪、游离氯含量在线分析仪和过碱量在线分析仪的测量原理及使用经验。

一次盐水精制工序在线监测仪的应用

介绍了一次盐水精制工序两碱含量在线监测仪、钙镁含量在线监测仪和氯化钠浓度在线监测仪的测量原理,对比分析了在线检测数据与人工检测数据,为稳定生产和降低成本奠定了基础。