水玻璃砂的化学—机械干法再生及应用

根据水玻璃砂再生回用理论,通过加入RCT改性剂和水溶性树脂对水玻璃砂进行化学改性,加以软机械再生-通过砂块与砂料之间的摩擦而去掉旧粘结膜,从而实现水玻璃砂的化学-机械干法再生。获得的再生砂可直接用于面砂。     

水玻璃砂旧砂干法再生的研究

回顾了水玻璃砂技术的发展以及干法再生的理论研究现状,介绍了复合吹气解决水玻璃砂隐蔽过吹欠缺问题,通过对多种旧砂再生的实验数据分析,为水玻璃砂旧砂实现干法再生提供依据.水玻璃砂干法再生工艺简洁、设备投入小、再生成本低,可在行业内推广应用.     

水玻璃旧砂"冰冻-机械"再生试验

根据水玻璃旧砂残留粘结剂的水溶性特点,进行了水玻璃旧砂“冰冻-机械”再生试验研究。通过单因素试验测试了“冰冻-机械”再生水玻璃旧砂的影响因素,通过正交试验优化了水玻璃旧砂“冰冻-机械”再生的工艺参数。采用较优的工艺参数对水玻璃旧砂实施“冰冻-机械”再生,脱膜率可达到43.1％。进行了液氮制冷连续“冰冻-机械”再生水玻璃旧砂试验,它与冰箱冰冻水玻璃旧砂模拟的“冰冻．机械”再生脱膜率相近;利用自然冰冻条件对水玻璃旧砂实施“冰冻．机械”再生在我国的北方地区进行,再生效果与实验室模拟试验相似。与其他常用再生方法对比,“冰冻-机械”再生的效果远远优于其他常用再生方法。     

用RCT改性剂组成的全系统水玻璃砂及其应用

根据新型水玻璃砂强度、溃散及再生回用理论所研制的ＲＣ系改性水玻璃砂,避免了以往水玻璃砂改造中添加材料所造成的顾此失彼的现象,很好地解决了水玻璃砂强度与溃散性等诸性能不能兼顾的矛盾,特别是其化学再生作用使水玻璃砂通过“化学－机械再生”法而获得实用的全系统水玻璃砂。     

水玻璃改性对水玻璃砂再生循环使用性能的影响

水玻璃改性技术在提高水玻璃砂强度,改善其溃散性的同时,也对水玻璃旧砂经干法再生后循环使用的砂性能产生了影响。试验测试了水玻璃旧砂受热温度对其溃散性的影响,比较了普通水玻璃和改性水玻璃在水玻璃旧砂溃散性上的区别,测试研究了多次循环使用后水玻璃再生砂残留强度的变化,分析了所用改性水玻璃粘结剂对水玻璃旧砂再生回用后的性能产生影响的原因和机制。结果表明,水玻璃改性有利于水玻璃砂的再生循环使用。     

水玻璃旧砂再生的质量控制

对水玻璃砂再生的质量控制进行了数理分析。结果认为,水玻璃砂采用螺旋振动再生,脱膜率是一定的,通过调整新砂加入量,即可使Na2O%的含量趋于并达到一个稳定的水平上,从而可以实现水玻璃干法再生砂的单一砂使用。     

水玻璃旧砂的干法回用与湿法再生

根据水玻璃旧砂的特点和对其再生砂的不同使用要求,本文提出了“水玻璃旧砂干法回用与湿法再生”的观点。认为:如作背砂使用,水玻璃旧砂只需进行破碎、去磁、筛分、除尘等干法回用处理,没有必要对旧砂粒进行高强度的机械碰撞磨擦处理;但如作单一砂或面砂使用,水玻璃旧砂必须进行湿法再生,力求获得高的脱膜率。本文通过试验研究和比较水玻璃旧砂及其干法再生砂与湿法再生砂的性能特征,以及背砂、面砂(或单一砂)的使用要求,论证了上述观点的正确性。     

水玻璃砂的再生

介绍了水玻璃旧砂湿法、干法和热法的再生原理,并简要说明了其应用情况.通过阐述人们对水玻璃硬化机理的认识,说明了水玻璃旧砂化学再生的基本原理,并对近年来水玻璃旧砂化学再生方面的研究及应用情况进行了总结概括.     

再生砂在铸钢件上的应用及质量控制

旧砂再生循环使用是减少铸造成本的有效途径,合理使用再生砂,减少或避免铸造缺陷产生是再生砂使用的重要环节。文章介绍了热干法联合再生系统,酯硬化水玻璃再生砂的质量检验标准,生产常用的混砂配方,分析了酯硬化水玻璃再生砂的工艺性能。通过酯硬化水玻璃自硬砂工艺使用经验,针对生产过程中容易出现的问题进行分析,并给出了应对措施和解决方案。     

水玻璃旧砂再生回用技术

概述了水玻璃旧砂的特点以及水玻璃旧砂再生回用技术的进步。介绍水玻璃旧砂的湿法再生技术和干法再生系统。分析了水玻璃旧砂再生仍然存在的问题，提出了三种较佳的水玻璃旧砂再生方案：对于采用“面砂一背砂”制的工厂，应进行干法回用处理；对于采用单一砂的工厂，应进行湿法再生；而最理想的方法是“干法回用、湿法再生”。     

树脂旧砂的热法再生

介绍了树脂旧砂热法再生的原理及沸腾式树脂旧砂热法再生装置,研究发现,热再生砂和同种新砂相比,角形系数、发气性和受热膨胀性降低,粒形更趋圆整,砂子的集中度、型砂的抗拉强度提高,铸造工艺性能优于同种新砂。     

A new low-cost method of reclaiming mixed foundry waste sand based on wet-thermal composite reclamation

A lot of mixed clay-resin waste sand from large-scale iron foundries is discharged every day; so mixed waste sand reclamation in low cost and high quality has a great realistic significance. In the study to investigate the possibility of reusing two types of waste foundry sands, resin bonded sand and clay bonded sand which came from a Chinese casting factory, a new low-cost reclamation method of the mixed foundry waste sand based on the wet-thermal composite reclamation was proposed. The waste resin bonded sand was first reclaimed by a thermal method and the waste clay bonded sand was reclaimed by a wet method. Then, hot thermal reclaimed sand and the dehydrated wet reclaimed sand were mixed in certain proportions so that the hot thermal reclaimed sand dried the wet reclaimed sand leaving some water. The thermal reclamation efficiency of the waste resin bonded sand was researched at different heat levels. The optimized wet reclamation process of the waste clay bonded sand was achieved by investigating the effects of wet reclamation times, sand-water ratio and pH value on the reclaimed sand characteristics. The composite reclamation cost also was calculated. The research results showed that the properties of the mixed reclaimed sand can satisfy the application requirements of foundries; in which the temperature of the thermal reclamation waste resin bonded sand needs to be about 800 oC, the number of cycles of wet reclamation waste clay bonded sand should reach four to five, the optimal sand-water ratio of wet reclamation is around 1：1.5, and the pH value should be adjusted by adding acid. The mass ratio of hot thermal reclaimed sand to dehydrated wet reclaimed sand is about 1：2.5, and the composite reclaimed sand cost is around 100 yuan RMB per ton.     

Investigations of physicochemical properties of dusts generated in mechanical reclamation process of spent moulding sands Mth alkaline resins

Mechanical reclamation processes of spent moulding sands generate large amounts of post- reclamation dusts mainly containing rubbed spent binding agents and quartz dusts. The amount of post- reclamation dusts, depending in the reclamation system efficiency and the reclaim dedusting system, can reach 5%-10% in relation to the total reclaimed spent moulding sand. The proper utilization of such material is a big problem facing foundries these days. This study presents the results of investigations of physicochemical properties of post- reclamation dusts. All tested dusts originated from various Polish cast steel plants applying the mechanical reclamation process of moulding sands with alkaline resins, obtained from different producers. Different dusts, delivered from foundries, were tested to determine their chemical composition, granular characterization, physicochemical and energetic properties. Presented results confirmed assumptions that it is possible to utilize dusts generated during mechanical reclamation of used sands with organic resins as a source of energy.     

Inlfuence of wet activation of used inorganic binder on cyclically refreshed water glass moulding sands hardened by microwaves

The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with “dry” or “wet” activation of inorganic binder in waste moulding sand mixtures physicaly hardened by microwave radiation. The sand mixtures consisting of high-silica sand and water-glass with average molar module 2.5, were subjected to the folowing cyclical process: mixing the components, compacting, microwave heating, cooling-down, thermaly loading the mould to 800 °C, cooling-down to ambient temperature, and knocking-out. After being knocked-out, the waste moulding sands were subjected to either dry or wet activation of the binder. To activate thermaly treated inorganic binder, each of the examined processes employed the surface phenomenon usualy associated to mechanical reclamation. The study also covered possible use of some elements of wet reclamation to rehydrate waste binder. To evaluate the effectiveness of the two proposed methods of waste binder activation, selected strength and technological parameters were measured. After each subsequent processing cycle, the permeability, tensile strength and bending strength were determined. In addition, the surface of activated sand grains was examined with a scanning electron microscope. Analysis of the results indicates that it is possible to re-activate the used binder such as sodium silicate, and to stabilize the strength parameters in both activation processes. Permeability of the refreshed moulding sands strongly depends on the surface condition of high-silica grains. The wet activation process by wetting and buffering knocked-out moulding sands in closed humid environment makes it possible to reduce the content of refreshing additive in water-glass. The moulding sands cyclicaly prepared in both processes do not require the addition of fresh high-silica sand. The relatively high quality achieved in the refreshed moulding sands alows them to be reused for manufacture of next moulds. Thus, the two proposed methods for cyclicaly processing used moulding sands containing sodium silicate, subject to microwave hardening, are suitable for economic and ecological circulation moulding mixtures.     

水玻璃砂的发展

越恶霸虎严格的环保法规要求,必将给污染最少的水玻璃砂带来大发展的机遇,水玻璃砂理论和技术的进步,使得CO2法的水玻璃加入量有可能降低到2.5%-3.0%,有机酯法为2.0%-2.5%,微波法为0.5%-0.8%,再加上水玻璃旧砂化学再生法的发明,在不久几年内,水玻璃砂的溃散性和旧砂回用将接近或达到树脂砂的水平,水玻璃砂第三次大发展的条件日趋成熟。     

水玻璃砂的干法再生

水玻璃砂的干法再生主要是解决溃散性和脱膜率问题.采用各种方法,降低水玻璃加入量是提高水玻璃砂溃散性的有效途径.把水玻璃砂加热到一定温度,使水玻璃膜变脆,然后进行机械再生,可以获得较好的再生效果.     

Biodegradable materials as binders for IVth generation moulding sands

This paper focuses on the possibility of using the biodegradable materials as binders(or parts of binders' compositions) for foundry moulding and core sands. Results showed that there is a great possibility of using available biodegradable materials as foundry moulding sand binders. Using biodegradable materials as partial content of new binders, or additives to moulding sands may not only decrease the toxicity and increase reclamation ability of tested moulding sands, but also accelerate the biodegradation rate of used binders, and the new biodegradable additive(PCL) did not decrease the strength and thermal properties. In addition, using polycaprolactone(PCL) as a biodegradable material may improve the flexibility of moulding sands with polymeric binder and reduce toxicity.     

Resols hardened by Methyl Formate—a Contribution to raising Occupational and Environmental Standards in the Foundry

The introduction of some advanced methods of mould and core production may well have an adverse effect on the health and well-being of the operator, or lead to a deterioration in the internal and external environment of the foundry. In this presentation the authors discuss the use of sands bonded with an alkaline phenolic resin, hardened by methylformate vapour. Points examined include chemical changes during thermal destruction of the sand binder during pouring, solidification and cooling of the casting, and during the subsequent reclamation of the sand. It is concluded that this particular process offers a number of environmental advantages in addition to its production attributes.     

Industrial treatment processes for recycling of green foundry sands

Abstract

Three treatment processes for the reclamation of green moulding sands coming out from a cast iron foundry located in Northern Italy are considered in this study. A wet mechanical treatment, a dry mechanical treatment and a dry mechanical plus heat treatment are compared to evaluate the efficiency of each process and to point out the best regeneration solution for the recycling of reclaimed sand in foundry operations. The inflow and the outflow samples of each process were characterised by means of particle size analysis and the determination of silica, loss on ignition, acid request, oolitic and some metals contents. A final evaluation of the three processes was performed taking into account the obtained quality of recovered silica sand and the economical aspects; the wet mechanical and the dry mechanical plus thermal treatments are most effective for the recovery of green moulding sands coming out from the considered foundry plant for cold box core production.     

砂群运动的有色示踪分析

砂群在振动混砂机混砂桶内做复杂的螺旋运动,试验里对砂群运动的影响因素进行了研究,用有色分格砂层的方法,对砂群运动进行示踪,显示出砂粒在随砂群整体做旋转运动的同时,在底部做由内向外、桶壁处由下向上、顶部由外向内、中心由上向下的运动,呈翻腾状.砂群的外缘线速度与振幅间有正比关系.