1. Specification Breakdown
Chromite Sand: This is the base material, derived from the mineral chromite (FeO·Cr₂O₃). It is a neutral refractory material, meaning it has high resistance to both acidic and basic slags, unlike silica (acidic) or magnesia (basic) which react with slags of the opposite chemistry. AFS 45-55: This is the most critical technical detail. AFS stands for the American Foundry Society. The AFS Grain Fineness Number (GFN) is a standardized method for expressing the average grain size of a sand. A value of 45-55 indicates a medium-fine and tightly controlled grain distribution. This range is finer than a common 50-100 mesh sand, meaning the particles are smaller on average, leading to a very dense packing.
For Kiln Lining: This defines the application. It will be used to create the protective inner wall of an industrial kiln or furnace, likely in a monolithic (e.g., rammed or poured) lining.
2. Key Characteristics and Advantages of AFS 45-55 Chromite Sand
Exceptional Lining Density: The fine, tightly graded particles pack together with minimal voids. This creates an extremely dense lining that is highly resistant to the penetration of molten metal, slag, and fluxes, significantly extending the lining’s lifespan. High Refractoriness: Chromite sand has a very high melting point (over 1900°C), making it suitable for applications involving steel, iron, and non-ferrous metals. Excellent Thermal Stability: It exhibits low thermal expansion, meaning it resists cracking and spalling during rapid temperature changes (thermal shock).
3. Typical Applications
Induction Furnace Lining: Especially for medium-frequency coreless furnaces melting steel and cast iron, where a dense, durable lining is paramount. Ladle Linings: Used as a working lining or a safety layer in ladles transporting molten metal. Foundry Molding: As a facing sand for large steel castings to prevent burn-on and penetration defects.
4. Important Considerations for Use
Binder Selection: The chromite sand must be mixed with a suitable refractory binder. Common choices include: Resin Binders (Furan or Phenolic) Sodium Silicate (Water Glass) Specialty Inorganic Binders The choice depends on the required curing method (heat-hardening, air-setting, gas-setting) and the desired balance of strength and collapsibility.