The moisture of dry Chromite sand
Dry Chromite sand is usually used for large, heavy, and structurally complex casting surface dry sand. Dry sand in casting needs to have high sand mold strength, fire resistance temperature, and resistance to molten steel erosion. Besides the sintering temperature and thermal conductivity, the moisture of chromite sand is an important technical index as well.
As is well known, chromite ore sand for casting is a natural mineral raw material that contains impurities such as iron, silicon, and sand. These impurities can affect the refractory temperature and anti-sticking ability of chromite sand during casting and pouring. Therefore, high-quality chromite sand for the foundry needs to be cleaned after the raw ore is crushed, and the commonly used cleaning method is water washing.
The chromite sand after washing has low mud content, low acid consumption value, and low turbidity. It helps to quickly form a compact casting model when using chromium ore sand as molding sand, preventing the problem of molten metal infiltration caused by poor hardening in the coated sand process.
However, after washing with chromite sand, residual water will be generated, and excessive water content in the casting sand can have the following effects:
1. It affects the strength of molding sand, especially coated sand molding sand.
2. This leads to an increase in the gas generation rate and volume of resin sand.
3. Reduce the hardening rate and increase the hardening time, thereby affecting the tensile strength of the molding sand.
Therefore, after the water washing process, we strictly dry the cast chromite sand to control its moisture content within 0.2%, which meets the requirements of no-bake sand casting, investment casting, shell molding, and resin-coated sand casting.
