Is sodium silicate reusable?
Sodium silicate in the state of crushed glass was charged in an autoclave (dissolver) with sodium hydroxide and water. It was concluded that reusing of wastewater generated from liquid sodium silicate manufacturing process resulted in cheaper and environmental-friendly product.
Why Silica sand is used in foundry?
Composition and Thermal Stability Crystalline silica has a higher melting point (1610 °C) than iron, copper or aluminium and other common metals. This enables castings to be made by pouring molten metal into moulds made from silica sand and a binder.
How do you harden sodium silicate?
Sodium silicate can be hardened in a number of ways: by adding weak acids (CO2 gas or organic esters), by adding various powders (di-calcium silicate, anhydrite etc.), or by removing water. CO2 gas and liquid ester hardeners are the most widely used of the silicate processes.
What is sand reclamation?
Sand reclamation is the process by which foundry sand is reconditioned without significantly affecting its physical properties. During the sand reclamation process, binders and coatings that adhere to sand grains during casting production are removed to recycle sand for subsequent use.
Is sodium silicate water soluble?
Properties. Sodium silicates are colorless glassy or crystalline solids, or white powders. Except for the most silicon-rich ones, they are readily soluble in water, producing alkaline solutions.
What is in foundry sand?
Foundry sand consists primarily of clean, uniformly sized, high-quality silica sand or lake sand that is bonded to form molds for ferrous (iron and steel) and nonferrous (copper, aluminum, brass) metal castings. In addition to green sand molds, chemically bonded sand cast systems are also used.
How is foundry sand made?
Waste foundry sand 4.1) is a discarded material coming from ferrous (iron and steel) and nonferrous (copper, aluminium, and brass) metal-casting industry to create molds and cores. Molding sands are manufactured by using virgin silica sands with the addition of binding agents (e.g., bentonite clay and organic resins).
What happens when sodium silicate is heated?
At 100–105 °C (212-221 °F), sodium silicate loses water molecules to form a glass seal with a remelt temperature above 810 °C (1,490 °F). A sodium silicate repair can last two years or longer. The repair occurs rapidly, and symptoms disappear instantly.
What is thermal reclamation?
Thermal Reclamation is actually a combination of Mechanical Attrition Reclamation and Thermal Reclamation. In this process, mechanically reclaimed sand is heated to a temperature of about 800°C. Heating takes place in a specially-designed furnace where the sand is both fluidised as well as heated.
What will dissolve sodium silicate?
Bring purified water to a low simmer (approximately 175 degrees) on an electric stove. Stir sodium silicate powder into hot water with a long-handled metal spoon. Continue stirring until the powder is completely dissolved.