M - Foundry Additives Glossary
Is a refractory mineral called magnesium carbonate (MgCO3). It has some contaminants present, such as iron carbonate (FeCO3) and ferric oxide (Fe2O3) present. Its specific gravity is 3.1 and it is fused at 3929°F. (2165° C.). For foundry preparation and use it is a very valuable refractory aggregate particularly where basic refractories are required. Magnesite, when finely ground, is added to chrome sand mixtures as (MgO). MgO is also used as a foundry sand in certain mixtures. Where basic lined furnaces are in operation, dead burned magnesite is used. It is a hard, dense, granular material obtained by calcining magnesite rock at a temperature high enough to form a product inert to atmospheric moisture and carbon dioxide. It is chiefly magnesia (MgO) and is a basic refractory. In the casting of manganese steel, olivine sand or chromite Hevi-Sand containing 10% to 15% MgO addition is an excellent core sand base.
An oxidizing agent, MnO2, can be made synthetically or may be found as an ore, known as "bog manganese" or "wad." It has many uses in the foundry, one use being in core sand mixtures for oxidizing purposes. Small amounts are used, such as 0.25 percent.
MENHADEN OIL (See: CORE OIL-OILS)
An oil obtained by steaming or boiling fish caught along the U.S.A. Atlantic coast line. It is also called, "Porgy Oil," "Whitefish Oil," and in the South it is called, "Fatback" and "Moss Bunker." The oil contains 27% oleic acid, stearic acid and a few fats, so that it polymerizes as easily as vegetable oil used in core oils.