EDTA滴定总硬度实验条件探讨

ＥＤＴＡ滴定总硬度实验条件探讨匡向阳彭群英（湖南省永州水文水资源勘测局）１前言水的总硬度包含了碱金属以外的所有金属离子含量的总和。但在一般情况下,除钙、镁离子以外,其它金属浓度都很低,所以通常在ＥＤＴＡ二钠容量法测定钙、镁离子总量后,经过换算成每升水...     

简便快速分离测定卤水中的钙镁钡锶

本文用氢氧化钠溶液ρ（ＮａｏＨ）＝３５０ｇ／Ｌ在９０℃左右将钙镁沉淀分离后，用盐酸溶解其沉淀，以ＥＤＴＡ配位法滴定测得钙和镁的含量。滤液经盐酸酸化后，加适量硫酸将钡沉淀而与锶分离。以重量法测定钡，ＥＤＴＡ配位法测定锶。本法简便、快速，通过多批量样品实测应用，其结果均合符生产要求。     

富含钨钼的试样中铝的测定

在碱性介质中，用钡离子沉淀钨、钼。滤液经盐酸酸化后，用ＥＤＴＡ标准溶液滴定铝。该法用于分析钨铁，钼铁、合金钢及钨矿中的铝，结果满意。     

钛精矿中氧化铝的测定——碱熔、氟盐取代络合滴定容量法

过氧化钠熔样,干过滤沉淀分离大部分钛、铁、锰等共存元素,在酸性溶液在加入过量的ＥＤ－ＴＡ,于ｐＨ５．５～６．０溶液中用氯化钠溶液回滴过量的ＥＤＴＡ,加入氟化钠置换铝—ＥＤＴＡ铬合物中的铝,定量释放出来的ＥＤＴＡ再用锌标液滴定,二甲酚澄指示剂由黄色变成红色即为终点。试验沉淀滤液中ＴｉＯ２含量的回收,研究表明;残留的ＴｉＯ２含量对氧化铝的测定影响的甚微。     

钒的交流示波极谱滴定

在有Ｂｒ＾－存在下的ＰＨ５ＨＡｃ－ＮａＡｃ缓冲溶液中，加入过量ＥＤＴＡ，用ＣｕＳｏ４标准溶液滴剩余的ＥＤＴＡ，以Ｃａ＾２＋在交流示波曲线上的切口指示终点。方法简便、准确，可用于矿石中钒的测定。     

EDTA容量法连续测定钙和镁的改进

改进了用EDTA连续快速测定矿石中钙和镁的方法。在用EDTA滴定钙之后的溶液中加入NH4Cl，使溶液中的碱度降低至pH10左右，以Mg(OH)2沉淀溶解为标志，加入pH10的缓冲溶液，补加K－B指示剂，用同一EDTA标准溶液继续滴定镁。此法克服了用HCl调节pH值法滴定镁结果系统偏高的缺点，经大量生产考察，结果准确，稳定，与分别滴定后从钙镁合量差减法和外检结果十分一臻，对ω（MgO)为21.10%的样品进行精密度试验，其RSD（n=10)为0.6%。     

用2－（2－噻唑偶氮）－5－二甲氨基苯甲酸作络合滴定铜的指示剂

用２－（２－噻唑偶氮）－５－二甲氨基苯甲酸作络合滴定铜的指示剂李秀玲，凌永萍，张瑾山东建材学院应化系济南２５００２２铜合金中Ｃｕ的测定常用方法有碘量法、ＥＤＴＡ容量法。ＥＤＴＡ容量法常用的指示剂有ＰＡＮ和二甲酚橙，但ＰＡＮ在使用过程中水溶性差、变色不...     

碳酸盐岩石中二氧化碳、氧化钙和氧化镁的快速连续测定

沉积的碳酸盐岩石主要是由方解石（CaCO₃）和白云石（CaMg[CO₃]₂）的碳酸盐矿物组成。对于碳酸盐岩石中二氧化碳、氧化钙、氧化镁的测定,在例行的分析中,都是单独取样,分别以吸收重量法或容量法测定二氧化碳,以草酸铵-高锰酸钾容量法测定钙,而镁则根据 CO₂与 CaO 的含量之差数来求得,或用氢氧化钡标准溶液使镁沉淀,于滤液中用盐酸滴定过量的氢氧化钡而测定镁。为了缩短分析时间,简化操作手续,节省试剂,作者提出了在以酸碱容量法测定 CO₂后,在同一份样品中,以 E.D.T.A.络合滴定法进行钙和镁的连续测定方案。通过二年来的实践证明是完全可行的。它的特点是比较经济准确简便快速,因此具有一定的实际意义。     

芒硝,钙芒硝矿中TNa2SO4测定与盐类矿物含量配算方法

用ＥＤＴＡ络合滴定直接测定芒硝和钙芒硝中的ＴＮａ２ＳＯ４。以ＴＮａ２ＳＯ４，Ｔｓｏ４＾２－，Ｃｌ＾－和Ｈ２Ｏ＾＋四因子配算盐类矿物成分，方法简便。     

锰矿中钙镁的络合滴定

大量锰严重干扰钙,镁络合滴定,必须进行分离。常用的硝酸—氯酸钾法,铜试剂—氯仿萃取法,离子交换法等,手续繁琐。 郑臣林等提出在PH3微醋酸性溶液中,用邻菲罗林-硫氰酸钠沉淀分离锰,其组成为Mn-Phen-CNS。可使高达100毫克的锰完全分离,且钙,镁无损失。当试样中含较高量铁时,须加铜试剂(DDTC)辅助沉淀。但由于少量铁被铜试剂还原后生成[Fe-Phen]_ ~2,致使溶液被染成红色,妨碍滴定钙,镁时终点的观察。 本文提出:先在PH6六次甲基四胺介质中沉淀分离铁,铝;然后在同样条件下,用DDTC-Phen-NaCNS沉淀分离锰和其它干扰元素,取滤液进行     

Experimental study on mechanical properties and pore characteristics of the modified lime mortars under freee-thaw cycles北大核心CSCD

石灰土作为路基填料代替宕渣是一种较为经济的方案,但灰土初始强度低、硬化速率慢、碳化时间长,不利于快速施工,需要进行改良研究。利用偏高岭土与石灰发生火山灰反应的原理改良灰土,通过单轴压缩试验和三轴压缩试验,分析改良灰土冻融循环条件下力学参数变化规律,利用图像处理技术提取改良灰土图像表面孔隙,建立孔隙率与强度的关系,并通过研究龄期、石灰含量和含水率变化规律,分析偏高岭土改良灰土的机制。结果表明：偏高岭土能够有效提高灰土材料反应速率,改善灰土力学特性;偏高岭土在一定程度上能够恢复冻融循环导致的灰土力学性能损失,降低冰晶体产生的孔隙;灰土强度达到最优后,其强度随着石灰的增加而降低,而经偏高岭土改良后其强度将继续增加;火山灰反应比灰土碳化过程消耗更多的水分,有效提高了灰土的抗冻性能。     

膨胀土路堤处治效果原位试验研究

介绍了对弱膨胀土路堤采用“膨胀土+石灰土+土工网”分层交错填筑的综合处治方法。通过现场试验测定了不同分层组合填筑结构型式土基的承载力和回弹模量,并分析了二者存在差异的原因。结果表明,采用弱膨胀土-石灰土这种结构作为膨胀土路堤的治理方案和采用弱膨胀土-石灰土-土工这种复合结构型式作膨胀土路堤的包边处理是科学合理的。只要各结构层施工质量能够满足设计要求,采取这种结构形式,一方面可以充分利用沿线的弱膨胀土材料,另一方面又可以充分利用弱膨胀土自身的强度优势,保证路堤的稳定。     

Lime stabilization of clay minerals and soils

Clay soil can be stabilized by the addition of small percentages, by weight, of lime, thereby enhancing many of the engineering properties of the soil and producing an improved construction material. In order to illustrate such improvements, three of the most frequently occurring minerals in clay deposits, namely, kaolinite, montmorillonite and quartz were subjected to a series of tests. As lime stabilization is most often used in relation to road construction, the tests were chosen with this in mind. Till and laminated clay were treated in similar fashion. With the addition of lime, the plasticity of montmorillonite was reduced whilst that of kaolinite and quartz was increased somewhat. However, the addition of lime to the till had little influence on its plasticity but a significant reduction occurred in that of the laminated clay. All materials experienced an increase in their optimum moisture content and a decrease in their maximum dry density, as well as enhanced California bearing ratio, on addition of lime. Some notable increases in strength and Young's Modulus occurred in these materials when they were treated with lime. Length of time curing and temperature at which curing took place had an important influence on the amount of strength developed.     

高速公路建设中中膨胀土特性的试验研究

随着高速公路建设的迅速发展,遇到的与膨胀土相关的工程问题也日益增多,以实际高速公路工程为依托,通过室内和现场试验,对中膨胀土的物理力学特性以及中膨胀土经过石灰改性处理后的的效果进行了研究。结果发现：未经石灰改性的中膨胀土在最佳含水量条件下有较高的强度,浸水饱和后膨胀量大,强度衰减很多,水稳定性很差;经石灰改性后的中膨胀土强度有很大提高,水稳定性也较好。这说明在工程建设中只要采取有效的处置措施和合理的施工方法,中膨胀土可以作为高速公路路堤的填筑材料。     

Engineering properties of unfired clay masonry bricks

The shortage of low cost and affordable housing in the UK has led to many investigations into new building masonry materials. Fired clay masonry bricks are conventionally used for mainstream masonry wall construction but suffer from the rising price of energy plus other related environmental problems such as high energy usage and carbon dioxide emission. The use of stabilised unfired clay bricks for masonry construction may solve these problems.This paper reports on the engineering properties of unfired clay bricks produced during the first industrial trial of unfired clay material development carried out at Hanson Brick Company, in Stewartby, Bedfordshire, under the Knowledge Exploitation Fund (KEF) Collaborative Industrial Research Project (CIRP) programme. The mixes were formulated using a locally available industrial by-product (Ground Granulated Blastfurnace Slag — GGBS) which is activated with an alkaline (lime or Portland cement) combined with clay soil. Portland cement was not used in the formulation of the unfired stabilised masonry bricks, except as a control, which is a significant scientific breakthrough for the building industry. Another breakthrough is the fact that only about 1.5% lime was used for GGBS activation. This level of lime is not sufficient for most road construction applications where less strength values are needed and where 3–8% lime is required for effective soil stabilisation. Hence, the final pricing of the unfired clay bricks is expected to be relatively low.The laboratory results demonstrate that the compressive strength, moisture content, rate of water absorption, percentage of void, density and durability assessment (repeated 24-hour freezing/thawing cycles) were all within the acceptable engineering standards for clay masonry units. The paper also discusses on the environmental performance of the unfired clay in comparison to the bricks, used in mainstream construction of today. The bricks produced using this technology can be used for low-medium cost housing and energy efficient masonry wall construction.     

浅谈路基石灰土掺灰剂量施工技术

在施工过程中,石灰土路基掺灰焖料、二次掺灰、摊铺、碾压再到最后的质量检测周期相对较长,那么掺灰剂量如何检测、路基压实标准如何确定,是本文主要探讨的问题。文章介绍了南沿江高速公路QR标石灰土路基施工中,有关掺灰剂量的检测方法和压实度的检测依据,供同行参考。     

红层软岩崩解性路用控制方法研究

采用灰色关联度分析法对红层软岩的矿物成分、化学成分、崩解试验等数据进行了分析。分析表明, 水理特性不稳定的粘土矿物始终是影响软岩崩解的主要因素之一, 而不同的化学成分对红层软岩崩解性的影响程度不同。通过以纯水、MgCl2, FeCl3, NaCl, CaCl2盐溶液作为红层软岩岩块浸泡液的崩解试验, 说明纯水浸泡下软岩的崩解性最强, 而所选3种盐溶液对所选红层软岩样品的崩解性均有抑制作用, 其中又以CaCl2抑制作用最强。在此基础上提出公路施工中填筑前以浇水作为加快红层软岩崩解, 填筑压实中以掺入石灰作为抑制软岩崩解路用控制方法。     

Effect of Pozzolanic Reactivity on Compressibility Characteristics of Stabilised Low Lime Fly Ashes

This paper presents the effects of addition of lime and lime along with gypsum on the compressibility behavior of two class F fly ashes. Since the fly ashes develop strength and exhibit lower compression, consolidation testing with conventional duration of load increment may not be appropriate. Hence, an attempt has been made to assess the minimum duration of load increment necessary to study the compressibility characteristics of such materials. Thus compressibility behavior of fly ashes with additives has been studied using conventional consolidation test with different durations of load increments varying from 30 min to 48 h. The results obtained indicated that 30 min of duration of load increment can be used to assess the compressibility behavior of such materials. The effect of lime which reduces the compression is seen to be maximum from the results obtained with the duration of load increment of 30 min but gradually reduces with higher durations of load increment. It has also been observed that the rate of decrease in the compressibility is maximum up to 2.5% lime and gradual thereafter. The compressibility of lime treated fly ashes further reduces when gypsum is incorporated, the optimum gypsum percentage being 2.5. This reduction in the compressibility of fly ashes enhanced by incorporating lime and gypsum makes them versatile in the construction of embankments and for structural fills, particularly reducing the time required in between laying of each lift.     

改良膨胀土筑堤技术研究

利用改良膨胀土作为高速公路路堤填筑材料是宁淮高速公路需要解决的主要问题。尽管室内试验论证可以用石灰改良膨胀土性质,但现场石灰改良土施工还要解决三大问题：石灰拌和均匀性和石灰含量的检测问题、现场压实方法和压实度控制问题、现场压实改良土的胀缩性和强度是否满足高等级公路路床和路基的要求问题。结合宁淮高速公路先导段施工,设计了试验段进行现场试验。试验结果表明,通过合理的施工工艺、有力的质量控制,改良膨胀土能够满足设计要求。改良土已经不具有膨胀土性质,胀缩性低,CBR强度高,是良好的路堤填筑材料。     

Effect of wetting–drying cycles on swelling behavior of lime stabilized sand–bentonite mixtures

In the present study, influence of wetting–drying cycles on swelling pressures of sand–bentonite mixtures used in the construction of sanitary landfills to have an impermeable liner was investigated before and after lime treatment of the mixtures. Swelling pressure tests were conducted to see if the swelling pressures were affected by wetting–drying cycles. First series of specimens were prepared as a mixture of sand and bentonite only. In the first series of specimens, sand was mixed with bentonite in various proportions with their optimum water contents and compacted by using standard proctor energy. In the second series of the specimens, lime in various proportions was added to the mixtures of sand–bentonite. Then, the sand–bentonite mixtures stabilized by lime were compacted with the standard proctor energy at their optimum moisture contents. Five wetting–drying cycles were performed on each specimen and values of swelling pressures were measured at the end of each cycle. Results of swelling pressure tests indicated that the swelling pressure is decreased when lime is added to the mixtures. In addition, decrements were observed on swelling pressures by wetting–drying cycles. The results of the experiments of this investigation showed that the beneficial effect of lime stabilization to control the swelling pressures was partly lost by the wetting–drying cycles. However, the test results indicated that the swelling pressures of the specimens made of sand–bentonite mixtures stabilized by lime were lower than the swelling pressures of the specimens made of only sand–bentonite mixtures.