铸造旧砂再生工艺及应用的研究

【作者】 刘仲礼；

【导师】 吴勇生；

【作者基本信息】 昆明理工大学 ， 材料加工工程， 2003， 硕士

【摘要】 我国每年要排放1000万吨以上的铸造旧砂，旧砂的大量排放，不但造成资源的浪费，而且对环境造成极大的污染，对旧砂的再生回用已成为铸造行业亟待解决的问题。 本文通过对混合型旧砂和水玻璃旧砂进行不同再生工艺的研究，然后利用再生砂制芯、造型，检验再生砂的可使用性，其目的是使再生砂能全部或部分取代新砂造型、制芯，减少旧砂的排放。 对混合型旧砂的实验结果表明，对混合型旧砂进行干法再生和低温加热+干法再生，再生砂仅能回用于造型。采用选择性再生，即将块状树脂旧砂从混合型旧砂中分离出来，对树脂旧砂进行再生，再生工艺采用干法再生和热气流再生+干法再生，再生砂质量得到极大的提高；其中热气流加热分为低温加热和中温加热，中温加热对比低温加热，再生砂质量提高不大。从经济方面考虑，生产中易采用干法再生和低温加热+干法再生。 对干法再生出来的树脂再生砂进行制芯的工艺实验，实验标准按照生产上的要求来实行。实验结果表明，再生砂只能以部分加入用于制芯；由于再生砂性质的变化，制芯工艺必须做一定的调整，其树脂与固化剂的比值要低于标准值4；在旧砂加入量为30％，树脂加入量树脂加入量2.5％(砂重)，固化剂加入量0.7％(砂重)，树脂与固化剂之比值为3.57，制得的型芯质量达到生产上的使用要求。 对低温加热+干法再生出来的树脂再生砂进行制芯的工艺实验，实验结果表明，再生砂也只能以部分加入用于制芯；再生砂加入量为5％时，制得的型芯质量达到生产上的使用要求；在再生砂加入量为30％时，制芯工艺要做一定的调整，在树脂加入量2.2％(砂重)，固化剂加入量0.7％，树脂与固化剂之比值为3.14时，型芯质量合格。 对水玻璃旧砂的实验结果表明，干法再生和低温加热+干法再生均可生产出质量合格的再生砂，后者比前者更为有效，但经济性不如前者。 从经济性考虑，采用干法再生砂做造型、浇注实验。实验结果表明，采用50％再生砂造型，造型工艺不须调整并能生产出质量合格的铸件。 目前，旧砂再生在效益方面可能无利可图，但却是铸造行业发展的方向，是实现绿色铸造的一个重要环节。更多还原

【Abstract】 In our country, more than ten millions used foundry sand is dumped into the nature every year. The great dumping of used sand is not only a great waste of resource, but also pollutant to environment. Reusing reclaimed sand has become a question that need to be resolved urgently in casting industry.In this paper, different reclaiming technologies of used mixed sand and used sodium-silicate bounded sand are studied, and then reclaimed sand is used to make cores or moulds to test its usability. The purpose is to reduce the dumping of used sand by way of using reclaimed sand to make moulds or cores, totally or partly.The experimental results of used mixed sand indicate that reclaimed sand, which is produced by way of dry reclamation and low thermal + dry reclamation, can be only used to make moulds. The selective reclamation is that used resin bonded sand is divided from used mixed sand, and then used resin bonded sand is reclaimed. Through dry reclamation and thermal + dry reclamation, the quality of reclaimed sand is greatly increased. Thermal reclamation comprises of low and high temperature. Compared with low thermal reclamation, the quality of reclaimed sand is increased a little by way of high thermal reclamation. From the point of economy, low thermal reclamation is preferred .The technological experiment of reclaimed resin bounded sand produced through dry reclamation is made, the way of which is standard. The results indicate that reclaimed sand can be only used partly to make cores. Because of the changes of reclaimed sand s quality, the technology of making cores must be adopted, the specific value of resin and hardener is below the standard value, 4. When 30% reclaimed sand, 2.5%(sand weight) resin, 0.7%(sand weight) hardener are added to * make cores, at this time the specific value of resin and hardener is 3.57, the quality of cores can meet the demand of production.The technological experiment of reclaimed resin bounded sand produced through low thermal + dry reclamation is made, and the results indicate that reclaimed sand can be only used partly to make cores too. When 5% reclaimed sandis added to make cores, the quality of cores is up to standard; When 30% reclaimedsand, 2.2%(sand weight) resin, 0.7%(sand weight) hardener are added to make cores, at this time the specific value of resin and hardener is 3.14, the quality of cores can meet the demand of production.The experimental results of used sodium-silicate bounded sand indicate that the two ways, which are dry reclamation and low thermal + dry reclamation,can all produce eligible sand. The latter is better than the former in quality, but worse in economy.From the point of economy, reclaimed sand which is made by way of dry reclamation is used to make moulds and cast.At present, sand reclamation may not be lucrative, but this is the direction of development, and is a link of green casting.更多还原