Production method and application of reclaimed sand used for foundry cold cores

Abstract

The invention provides a production method of reclaimed sand used for foundry cold cores. According to the method, foundry used sand and an activator bloedite are used as raw materials, the foundry used sand is evenly covered with the bloedite, and the obtained reclaimed sand is long in high-temperature heat-resistant time, high in high-temperature compressive strength and small in gas volume. According to the production method of the reclaimed sand used for the foundry cold cores, in a use process of the provided reclaimed sand, the bloedite is decomposed into sodium oxide and magnesium oxide under the high-temperature action, the sodium oxide and the magnesium oxide have fluxing action, and thus the melting point of silicon dioxide is lowered from 1111 DEG C to 711 DEG C, so that energy consumption is greatly reduced; in a pouring process, organic resin in the foundry used sand is decomposed into carbon under the high-temperature action, the carbon is reacted with the sodium oxide, the magnesium oxide and the silicon dioxide, which is the main component of the foundry used sand, to form dense glass layers on sand core wall surfaces in contact with surfaces of castings, and thus molten iron is prevented from permeating into the sand cores, so that sand adhesion to the castings is avoided; and the provided method is wide in raw material source and low in cost, resources are recycled, and green production of the foundry industry is promoted.

Description

technical field [0001] The invention belongs to the technical field of reusing foundry old sand, and in particular relates to a preparation method and application of regenerated sand for foundry cold cores. Background technique [0002] The engine and cylinder head of traditional trucks usually use casting methods in the manufacturing process, and the recycling of old casting sand to replace new sand in the casting process is an urgent requirement and necessity to realize energy saving and emission reduction of enterprises and green production of my country's foundry industry trend. The inner cavity of the cylinder block and the cylinder head of the truck is complicated, and the sand core is made of special sand coated with a layer of phenolic resin. , The amount of gas released when the resin burns is large. If the gas stays in the casting, the body of the engine will not be dense, causing fatal problems such as oil leakage. The resin content of cold core sand is only abou...

AI Technical Summary

Problems solved by technology

The inner cavity of the cylinder block and the cylinder head of the truck is complicated, and the sand core is made of special sand coated with a layer of phenolic resin. , The amount of gas released when the resin burns is large. If the gas stays in the casting, the engine body will not be dense, causing fatal problems such as oil leakage.

The resin content of the cold core sand is only about 11% of that of the hot core sand, which greatly reduces the risk factor. However, under the condition of 1411°C, the heat resistance of the cold core sand is poor, which will cause the inner cavity of the casting to deform and reduce the dimensional accuracy.

[0003] Conventional foundry old sand regeneration process, the regenerated sand produced by it, due to the problems of residual resin film, residual binder, high mud content, high pH, ​​etc., when preparing cold cores, not only the strength of the sand core is low, but also the refractoriness is serious Not enough, a large amount of new sand must be mixed

Adding ferrochrome sand, pearl sand, ceramsite sand and other methods to prepare cold cores can make up for the above-mentioned defects of insufficient refractoriness, but it will cause a sharp increase in the production cost of the foundry, and ferrochrome sand is an imported resource, which is restricted by others; Both sand and ceramic sand are high-alumina refractory materials, and their production consumes raw materials such as aluminum ore and bauxite that are restricted by the country, and consumes a lot of energy and is inconvenient to use.

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