| With the emphasis on environmental protection and the development of cleaner production,it is a trend to use the green "non pollution" foundry binder and the used sand recycling technology with low emission.Animal glue adhesive is nontoxic and harmless,can be easily collapsed,can degrade and has a wide application prospect.But effect for the ordinary animal glue to be used as a sand binder is not good,because it is easy to gel at room temperature.so it is necessary for animal glue to be modified to prepare a new foundry binder which is liquid at room temperature.In this thesis,the modification process of animal glue adhesive was mainly studied and the modified mechanism of animal glue adhesive was studied with infrared spectrometer.Based on animal glue sand,the method of used sand reclamation was researched.First of all,the viscosity and adhesive strength of the animal glue were used as the performance index,and the appropriate alkaline hydrolysis process was got by the test.According to the molecular structure of the protein of animal glue,the appropriate modifier was selected,and the optimal amount of modifier and the modification process were determined by a large number of single factor experiments and orthogonal experiments.Ultimately determined alkaline hydrolysis process and the modification process of animal glue adhesive were as followed: the ratio of water to animal glue is determined as 6:5 and the amount of NaOH is 6% of animal glue quality.The alkaline hydrolysis time is 30 min and the alkaline hydrolysis temperature is 50?.Acrylic acid and glycerin is used as modifier,ammonium persulfate as initiator of acrylic,the best ratio(mass ratio)of each materials of modification process is as followed: glycerin: acrylic acid: ammonium persulfate: animal glue =9:15:5:100;the glycerin modification temperature is 55?,the acrylic acid modification temperature is 60?,and the modification time is 105 min.secondly,the modification mechanism theory was analyzed by infrared spectrum.The research results shows the graft copolymerization and ester-crosslinking among glycerol,acrylic acid and animal glue had been happened,so the molecular structure of animal glue is changed.The observation of the fracture of the bonded bridge by scanning electron microscopy shows that the structural change of animal glue adhesive changed the fracture mode of the sand bond bridge,thus affected the tensile strength of the sand.Then,the technological performance of the modified animal glue sand was analyzed.The hardening process in which the amount of animal glue adhesive is 3% to sand,the drying temperature is 180 ? and the drying time is 20 min.The molding sand of modified animal binder can be used for 3 hours after mixture,gas evolution is 13 ml·g-1.At 600 ?for 3 minutes,the residual strength of modified animal glue is 0.18 MPa,and animal glue sand has a good collapsibility after casting.Finally,the reclamation method of used animal glue sand was studied.The results show that dry reclamation,thermal reclamation and wet scrubbing reclamation can meet the process performance requirements of sand.The process of wet scrubbing reclamation is as followed: the ratio of sand to water is 1: 1.4,reclamation time is 7min,the speed of revolutions is 240r/min,and two reclamation is used for a good result,the LOI of recycled sand is 0.25%,the clay content of recycled sand is 0.43%,the AFS fineness is 51.The wet reclamation method has a better effect. |
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