| At present,sodium silicate sand is one of the most popular molding sands in the foundry industry.Its ester hardening water glass sand process overcomes the defect of poor disintegration of carbon dioxide water glass sand process,and has the advantages of non-toxic and tasteless ester,adjustable hardening speed,strong operability,and less water glass added,so it is popular among foundry workers.Although it is in line with the theme of green environmental protection,with the wide application,the problem of difficult regeneration and reuse caused by the accumulation of acetate has gradually been exposed,which limits the further application of ester-hardened water glass sand.Therefore,it is the general trend to find out the effect of acetate on the properties of ester-hardened water glass sand and to find solutions to the problem of difficulty in regeneration caused by the accumulation of acetate.Based on the basic theory of sodium silicate sand,this paper explores the influence law of acetate,and proposes an idea for the harmless treatment of acetate: carbonizing and harmless acetate,the harmful component of ester-hardened sodium silicate sand chemical treatment,so as to achieve the purpose of its removal.First,through the performance test of water glass sand samples with different acetate contents,the influence rule of acetate was explored.The results show that acetate has the greatest influence on the compressive strength of molding sand,and when its content exceeds0.05%,it will have a destructive effect on the compressive strength of water glass molding sand.And with the increase of acetate content,the usable time of molding sand is greatly shortened,its hygroscopicity is increased,the residual strength is reduced,and the collapsibility is improved.Secondly,through the selection of reagents,the choice of carbonization treatment plan and the implementation of the final carbonization test,the optimal method and reagent parameters of acetate carbonization treatment were determined.The results show that when the carbonization temperature is 500?,the reaction time is 60 s,the dosage of sodium hydroxide powder as reagent is 1%,and the dosage of calcium oxide powder as reagent is0.25%,the effect of carbonization treatment is the best,and the carbonization treatment of acetate The rate is close to 90%.The strength test result has slightly improved,but it is still very low.From the carbonate content test results,it can be seen that it is caused by the accumulation of carbonate.Thirdly,through the orthogonal test of harmless treatment and the comparison of test results,the best way of harmless treatment is determined.The results showed that the horizontal combination of calcium oxide addition of 1.5% and water addition of 3% had the best treatment effect.And repeat the test to test the strength of sand samples,the results are all about 1.275 MPa,and the measured carbonate content is 0.320%,which is far lower than 0.6%,which proves the accuracy of the best treatment effect.The range analysis shows that the range of the added amount of calcium oxide and the added amount of water is 0.151 and0.091 respectively,so the influence of calcium oxide is greater.Finally,the harmless treatment effect was verified by repeated experiments and morphology analysis.The results show that the strength value of the sand samples after repeated testing is about 1.270 MPa,which is similar to the strength value of the X3Y1 level,and the surface smoothness and flatness of the sand samples after the harmless treatment are high,which shows that the combination of X3Y1 has no effect.the effectiveness of the treatment. |
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