What precautions should be taken during the recycling and reuse of silica sol waste shells?

1、 Differentiation

The spent silica sol shell for recycling cannot be mixed with dewaxed shell that has not been baked, because there is water, gel, other volatile matter and wax on the surface of the shell that has not been baked, which will affect the strength of the shell if mixed with recycled sand.

2、 Magnetic separation

The recycled mullite sand must undergo one to two strong magnetic separations to remove iron oxide from the sand or iron containing sand that has not been completely removed from the original new sand, otherwise it will affect the strength of the mold shell at high temperatures.

3、 Mixing

Due to the fact that there is a certain proportion of recycled coarse sand using waste silica sol shell, it is not possible to recycle all of it. Therefore, it is best to mix recycled sand with new sand in a certain proportion for shell making. Long term use can reduce production costs, while also reducing the proportion of sand that can be recycled multiple times to a very low level, and avoiding some unfavorable factors that may arise when using sand that has been recycled multiple times.

4、 Dust removal

Due to the manufacturing characteristics of silica sol shell, it is impossible to completely separate the original powder sand during the crushing and screening process of recycled sand. Therefore, the friction between the sand particles during the use of recycled sand can generate secondary dust pollution, leading to a deterioration of the working environment for workers and not conducive to their physical health. Therefore, it is recommended to use water curtain dust removal to solve the problem of secondary pollution of dust.

5、 Concentration

Due to the limited source and recovery rate of waste silica sol shell, it is suitable to build production lines for recycled sand in areas with dense precision casting enterprises, but not too much. Because the recycling process generates a large amount of dust, air pollution is relatively serious. If there is too much dispersion, on the one hand, the dust removal process during recycling will consume a lot of energy, and on the other hand, the quality of the recycled sand made is difficult to guarantee.

6、 Recycling equipment

Recycling equipment should not be simplified. Based on the production process characteristics of silica sol precision castings, there is a large amount of powder, iron oxide, and iron blocks mixed in the waste shell. From the early drying, separation, crushing, and screening of iron blocks for dust removal, to the later magnetic separation of finished sand powder, not only includes all the equipment for normal production of new sand powder, but also includes more equipment for iron block separation, dust removal, and strong magnetic separation of sand powder in the later stage. Without these new process measures, the quality and stability of the recycled sand powder cannot be guaranteed.