Resin-coated sand prepared from recycled sand

Abstract

The invention discloses resin precoated sand prepared from reclaimed sand, belonging to the technical field of reclaimed sand. The resin precoated sand is prepared from the following raw materials in percentage by weight: 10%-80% of reclaimed sand and 20%-90% of roughing sand. A preparation method of the resin precoated sand comprises the following steps: mixing the reclaimed sand and the roughing sand and heating the mixture in a heater of a sand mixer to form hot sand, and placing the hot sand in the sand mixer when the temperature of the sand is 125-135 DEG C; and sequentially adding 1wt%-4wt% of phenolic resin based on the hot sand, 9wt%-20wt% of a curing agent based on the phenolic resin and 0.1wt%-0.2wt% of an isolator based on the hot sands to the hot sand for mixing. The resin precoated sand prepared from the reclaimed sand has the advantages of lower use level of resin, lower gas sending amount, lower thermal expansion and lower thermal expansion speed compared with those of resin precoated sand prepared from usual dry sand, so that the high casting size precision and the low casting gas waste deficiency can be obtained in the casting process, the yield of castings is improved, the manufacturing cost of casting enterprises is lowered, and good economical benefits are obtained.

Description

technical field [0001] The invention belongs to the technical field of reclaimed sand, and in particular relates to resin-coated sand prepared from reclaimed sand. Background technique [0002] As a high-efficiency molding material widely used in the foundry industry, resin-coated sand has been greatly developed. Based on the requirements of the casting process, resin-coated sand needs to have various performance guarantees. The resin-coated sand material undergoes core making, core assembly, molding, and pouring to produce castings with qualified dimensions. [0003] The casting pouring process is a thermal process. Different metals have different pouring temperatures. The pouring temperature of non-ferrous metals is usually 660-710°C, and the pouring temperature of ferrous metals is usually above 1350°C. Obviously, it is the resin coating of the main material of the mold (core). The sand material must ensure the external dimensions of the core during the process of coolin...

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Problems solved by technology

[0010] Furthermore, for raw sands with the same particle size number and particle distribution, the same particle surface cleanliness, and the same basic oxide content, when the particle properties (angle coefficient) are different, the different specific surface areas of the sand particles will result in the same amount of resin added. The uniformity of the resin coating when wrapping is different;

[0011] Fourth, when the above-mentioned three states of the original sand are the same but the moisture contained in them is different, it will cause the resin-coated sand to increase in burning loss at high temperature, and the gas generation will increase, resulting in an increase in gas waste products of castings;

[0012] Fifth, raw sands of different qualities have different mineral components, so they exhibit different thermal expansion properties in high-temperature environments.

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