Dry and hot-wet combined old sand regenerating method and regeneration system thereof

Abstract

The invention relates to a dry and hot-wet combined old sand recycling method and a recycling system thereof, which can be used for casting production. According to the invention, organic fat-cured alkaline phenolic resin old sand is first placed in a centrifugal old sand recycling machine to remove a resin film on the surface of sand as much as possible, and then the sand is cleaned with hot water in a hot-flow old sand recycling machine, and under the action of high temperature and strong stirring, residual resin on the surface of the sand is dissolved in water; sewage discharged is filteredthrough a filter to obtain resin and fine powder, and remaining water is heated and then reused for sand washing; hot recycled sand is cleaned and dehydrated, then sent into a vacuum dryer to be dried, and sieved by a vibrating sieve to be used as new sand, and resin filtered is processed and then used for other purposes; waste hot water produced by cooling a metallurgical electric furnace in therecycling process is heated by a heat pump and then used as sand washing water. The dry and hot-wet combined old sand recycling method can not only produce high quality recycled sand but also realizezero discharge of sewage, avoids harmful smoke pollution caused by thermal regeneration of resin sand, and achieves energy conservation and environmental protection.

Description

technical field [0001] The invention relates to an old sand recycling method and used sand recycling equipment in casting production Background technique [0002] The biggest source of pollution in foundry production is molding materials, mainly old sand. The regeneration and reuse of foundry old sand can greatly reduce the pollution of waste sand, reduce production costs, and improve the economic benefits of enterprises. It is an important measure to implement sustainable development and implement green casting. [0003] In recent years, alkaline phenolic resin sand molding with alkaline phenolic resin as binder has been widely used in foundry production, especially in cast steel production. Compared with furan resin sand, alkaline phenolic resin sand has many advantages, such as: (1) The free formaldehyde in the resin is low, and it is environmentally friendly. (2) Both the resin and the curing agent do not contain harmful elements such as nitrogen, phosphorus, and sulf...

AI Technical Summary

Problems solved by technology

(4) The amount of gas generation is small and the speed of gas generation is relatively gentle

Practice has proved that dry regeneration is not effective for alkali phenolic old sand. The general dry regeneration method is difficult to remove effectively, and the stripping rate is very low

(2) The curing agent organic grease in the ester-cured alkali phenolic old sand is difficult to remove by dry regeneration, and the residual organic grease can shorten the usable time of the regenerated sand and reduce the strength of the sand mold

(3) Most of the alkali metal compounds in the old alkali phenolic sand exist in the resin film, and the low stripping rate leads to many alkali metal compounds remaining in the reclaimed sand, which seriously affects the refractoriness of the reclaimed sand

However, this method also has defects: 1. There are still a small amount of alkali metal compounds remaining in the reclaimed sand, which will slowly accumulate during the repeated use of the reclaimed sand, resulting in a decline in the quality of the reclaimed sand

2. It needs to consume a lot of fuel, which increases the cost of recycled sand

3. The biggest defect is that a large amount of harmful gases and toxic substances will be produced during the regeneration process of old sand, which seriously pollutes the environment

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