A method for regeneration of foundry mixed old sand

Abstract

The invention mainly relates to the field of casting and discloses a regeneration method of mixed casting used sand. The method comprises the steps of primary sieving, primary magnetic separation, freezing, grinding, secondary sieving, secondary magnetic separation and packaging. The method is simple, convenient to operate and easy to popularize. The recovery rate of used sand reaches up to 94.7%. The casting cost is reduced by 10.4%. Powdered coal and dead clay in the used sand are removed through primary sieving. The density of the used sand is increased. The magnetic separation effect and the refrigerating effect in the post-processing process can be improved. Strong-magnetic impurities in the used sand are removed through primary magnetic separation. Temperature transfer in the later refrigerating process is accelerated. The refrigerating time is shortened. The treatment efficiency is improved. Refrigerating is conducted after primary magnetic separation to improve the brittleness of bentonite and resin on the surfaces of sand particles so as to facilitate grinding and removing fo bentonite and resin. Damage to pellets is reduced. The oolitic rate is reduced to 1.02%. The acid consumption is reduced to 1.66 ml. The ignition loss is reduced to 0.03%. The grinding efficiency is obviously improved.

Description

technical field [0001] The invention mainly relates to the field of foundry, in particular to a method for regenerating foundry mixed old sand. Background technique [0002] Mixed used sand is a mixture of clay used sand and resin used sand. In my country and the world, more than 80% of the castings are produced by sand casting. Generally speaking, for every 1 ton of qualified castings produced, it takes 1~1.3t of waste sand, the recycling rate of old foundry sand in my country is less than 15%. Most of the old sand is disposed of by landfill, which causes a serious waste of natural resources. At the same time, the old sand contains a large amount of aldehydes, phenols, and phenylpotassium. , isocyanide, sulfide and other harmful substances. The old sand is directly discharged or landfilled without treatment. These harmful substances will flow and transfer after rain erosion, which will bring great harm to water and the environment. [0003] At present, the regeneration metho...

AI Technical Summary

Problems solved by technology

[0002] Mixed used sand is a mixture of clay used sand and resin used sand. In my country and the world, more than 80% of the castings are produced by sand casting. Generally speaking, for every 1 ton of qualified castings produced, it takes 1~1.3t of waste sand, the recycling rate of old foundry sand in my country is less than 15%. Most of the old sand is disposed of by landfill, which causes a serious waste of natural resources. At the same time, the old sand contains a large amount of aldehydes, phenols, and phenylpotassium. , isocyanide, sulfide and other harmful substances. The old sand is directly discharged or landfilled without treatment. These harmful substances will flow and transfer after rain erosion, which will bring great harm to water and the environment.

[0003] At present, the regeneration method of mixed used sand is a thermal-mechanical regeneration system, which has the functions of feeding, crushing, magnetic separation, roasting, granulation, grinding, and storage of finished sand. Although the purpose of energy saving has been achieved, the regeneration process is The acid consumption value and oolitic degree of graining are high, which reduces the strength of the sand core and greatly restricts the use of reclaimed sand