Micro-wet treatment process for foundry waste sand

Abstract

The invention provides a micro-wet treatment process for foundry waste sand, which comprises the following steps: S1, crushing the foundry waste sand, and then carrying out magnetic separation and screening; s2, wet treatment is conducted on the screened waste sand through a swing arm type mixing and spraying machine, then wet sand is obtained through cleaning, and the wet sand is dried after heat exchange; s3, roasting in a roasting furnace at the roasting temperature of 800 to 900 DEG C for 10 to 20 minutes; after roasting is finished, steam grinding is carried out in heat exchange grinding equipment, and meanwhile heat exchange with the wet sand in S2 is carried out; and S4, cooling and screening the waste sand subjected to heat exchange to obtain a regenerated sand primary product. According to the method for recycling the foundry waste sand, acid pickling is firstly carried out to remove a part of organic and inorganic impurities, and the subsequent roasting time is shortened; then roasting is carried out, and the roasting temperature and time are adjusted and optimized. Heat exchange grinding is carried out after roasting, water vapor is added in the grinding process, a high-heat micro-wet environment is formed, residual inorganic impurities such as bentonite on the surface of the waste sand are further removed, and meanwhile stripping and desorption of the organic impurities are better facilitated.

Description

technical field [0001] The invention belongs to the technical field of foundry sand recovery, and in particular relates to a micro-wet treatment process for foundry waste sand. Background technique [0002] About 90% of the castings in the foundry industry are produced by the sand casting process. Steel, iron and most non-ferrous alloy castings can be obtained by sand casting. The basic raw materials for making sand molds are foundry sand and molding sand binders. Commonly used molding sand binders can be divided into organic types (for example: phenolic resin, cold box resin, etc.) and inorganic types (for example: clay, water glass, etc. ), and the commonly used foundry sand is silica sand (20-140 mesh particles), generally producing 1 ton of castings will produce 1-1.5 tons of waste foundry sand, a large amount of silica sand comes from nature, the scale development of the foundry industry will inevitably lead to natural silica sand resources The large amount of mining a...

AI Technical Summary

Problems solved by technology

[0003] Although there are many types of waste sand regeneration methods nowadays, there are many problems in these methods. The removal rate of impurity film by dry mechanical regeneration is not more than 80%. The particle size of regenerated sand is getting smaller and smaller. On the one hand, the recovery rate of regenerated sand is greatly reduced (not exceeding 80%). The surface of the reclaimed sand obtained will have cracks, and the acid consumption of regenerated sand is high, which cannot meet the technical quality requirements of foundry sand. On the other hand, a large amount of fine powder is produced, and the technical pressure for secondary treatment and utilization is relatively high; the thermal regeneration method has a good removal effect on flammable organic impurity films such as phenolic resin and cold box resin, but it is not effective for clay, water, etc. The removal effect of inorganic impurity films such as glass is not good; and the tail gas after roasting needs to be purified; the wet mechanical regeneration method has a good removal effect on clay, water glass and other water-soluble inorganic impurity films, but for phenolic resin, The removal effect of organic impurity films such as cold box resin is not good; and the subsequent sand, water, and impurities need to be further separated, and even the sewage generated in the production process needs to be treated for water

[0004] In summary, the existing technologies are all aimed at recycling a single type of waste sand, and there are few studies on the regeneration technology of mixed casting waste sand

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