lining material. Magnesite refractories are composed of ≥ 85% magnesium oxide (MgO). They have high slag resistance to lime and iron-rich slags, strong abrasion and corrosion resistance, and high refractoriness under load, and are typically used in metallurgical furnaces. Dolomite refractories mainly consist of calcium magnesium carbonate. Typically, dolomite refractories are used in converter and refining furnaces. Magnesia-chrome refractories mainly consist of magnesium oxide (MgO) and chromium oxide (Cr2O3). These refractories have high refractoriness and have a high tolerance for corrosive environments. Neutral refractories These are used in areas where slags and atmosphere are either acidic or basic and are chemically stable to both acids and bases. The main raw materials belong to, but are not confined to, the R2O3 group. Common examples of these materials are alumina (Al2O3), chromia (Cr2O3) and carbon. Carbon graphite refractories mainly consist of carbon. These refractories are often used in highly reducing environments, and their properties of high refractoriness allow them excellent thermal stability and resistance to slags. Chromite refractories are composed of sintered magnesia and chromia. They have constant volume at high temperatures, high refractoriness, and high resistance to slags. Alumina refractories are composed of ≥ 50% alumina (Al2O3). Based on method of manufacture Dry press process Fused cast Hand molded Formed (normal, fired or chemically bonded) Un-formed (monolithic-plastic, ramming and gunning mass, castables, mortars, dry vibrating cements.) Un-formed dry refractories. Shaped These have standard size and shapes. These may be further divided into standard shapes and special shapes. Standard shapes have dimension that are conformed by most refractory manufacturers and are generally applicable to kilns or furnaces of the same types. Standard shapes are usually bricks that have a standard dimension of and this dimension is called a "one brick equivalent". "Brick equivalents" are used in estimating how many refractory bricks it takes to make an installation into an industrial furnace. There are ranges of standard shapes of different sizes manufactured to produce walls, roofs, arches, tubes and circular apertures etc. Special shapes are specifically made for specific locations within furnaces and for particular kilns or furnaces. Special shapes are usually less dense and therefore less hard wearing than standard shapes. Unshaped (monolithic refractories) These are without definite form and are only given shape upon application. These types are better known as monolithic refractories. The common examples are plastic masses, ramming masses, castables, gunning masses, fettling mix, mortars etc. Dry vibration linings