Research On The Modification Technology And Associated Equipment Of The Total Reclaimed Sand Which Reclaimed From The Used Green Sand Containing Hot-box Or Precoated Sand

Foundry technology is one of the basic forming process of manufacturing mechanical parts.Green sand casting is the most commonly used casting process,a large number of used green sand produced in the casting production every year,which leads to the natural environment pollution and the waste of natural resources.Based on the previous research,the total reclaimed sand reclaimed from the used green sand contain resin sand were obtained by the process of “calcination of 700 ? + dry mechanical reclamation + micro-powder separation”.The reclaimed sand has a good properties,such as the size distribution,the grain shape and the mud content are better than that of new base sand.However,the acid request value of the reclaimed sand is higher than that of new base sand.The casting properties of the hot-box core resin sand mixed by the total reclaimed sand which reclaimed from the used green sand containing hot-box resin sand is lower than the hot-box resin sand mixed by the new sand.The casting properties of the precoated sand mixed by the reclaimed sand reclaimed from the used green sand containing precoated sand basically reaches the precoated sand mixed by the new sand.The total reclaimed sand reclaimed from the used green sand containing hot-box resin sand is chosen as the research object in the paper.The casting properties of the total reclaimed sand reclaimed from this used green sand are improved by chemical modification.The suitable chemical modification process of this total reclaimed sand is “chemical modification + drying+ mechanical reclamation + separation of micro-powder”.The suitable modifier concentration is 0.75mol/L and the amount of modifier adding into the reclaimed sand is 4% of the reclaimed sand weights.Moreover,the placing time of this modified sand is 80 minutes.The hot tensilestrength and the room temperature tensile strength of the hot-box resin sand mixed by the chemical modified sand are better than that of the new sand.The casting properties of the total reclaimed sand which reclaimed from the used green sand containing hot-box resin sand are also improved by mechanical modification.With the number of cycles for mechanical modification increasing,the mud content and the acid request value of reclaimed sand are reduced.And the hot tensile strength and the room temperature tensile strength of the hot-box resin sand mixed by the mechanical modified sand are gradually increased.When the number of cycles for mechanical modification is two,the hot tensile strength and the room temperature tensile strength of the hot-box resin sand mixed by the mechanical modified sand are better than that of the new sand.The total reclaimed sand which reclaimed from the used green sand containing precoated sand is chosen as the research object.The suitable chemical modification process of the total reclaimed sand reclaimed from the used green sand containing precoated sand is “chemical modification + drying + mechanical reclamation + separation of micro-powder”.The suitable modifier concentration is 1.0mol/L and the amount of modifier adding into the reclaimed sand is 3% of the reclaimed sand weights.Moreover,the placing time of this modified sand is100 minutes.The hot tensile strength and the room temperature tensile strength of the precoated sand mixed by the chemical modified sand are lower than that of the new sand.It is revealed that the casting properties of the chemical modified sand which reclaimed from the used green sand containing precoated sand isn't improved by using the chemical modification.However,the casting properties of this total reclaimed sand are improved by mechanical modification.With the number of cycles for mechanical modification increasing,the mud content and the acid request value of reclaimed sand are reduced.The casting properties of the precoated sand mixed by the mechanical modified sand are significantly improved.According to the research route of the chemical modification and mechanical modification of the total reclaimed sand,the equipment needed to complete the completely reclaimed sand modification technology are analyzed in assessment,makes an analysis to equipment needed of the modification technology of the total reclaimed sand and finding that the modified sand mixer needed completing modification of the total reclaimed sand,determined the design plan of the beating cage continuous modified sand mixer and havedeveloped the speed of 960 r/min,driving power for the 4 kw,productivity is 5 t/h of the modified sand mixer of the total reclaimed sand.