Magnesium chromium brick manufacturers tell you the characteristics and characteristics of direct bonded magnesium chromium bricks

Magnesium chromium refractory material is a type of refractory material mainly composed of magnesia and supplemented by chromite; After adding magnesia to chromite and being fired at high temperature, there is a significant physical and chemical reaction between magnesia and chromite. The MgO in magnesia and Cr₂O₃ components in chromite diffuse with each other during the sintering process, forming dotted secondary spinel inside periclase and original spinel in chromite; According to the different processes and raw materials used, magnesium chromium bricks form varying degrees of secondary composite spinel and periclase secondary spinel composites during the cooling process, in order to achieve a structure where the various phases are directly combined and the chromite phase is wrapped in magnesium sand.

In the development history of magnesium chromium refractory materials used in the copper smelting industry, Z used silicon bricks to build furnace linings as early as possible. However, due to the high content of FeO and SiO₂ in the slag composition and the high content of SO₂ acidic gas in the smelting atmosphere, the erosion and damage of silicon bricks are very serious. From the 1950s to the 1960s, alkaline bricks have been used in the copper smelting industry, and to this day, after several generations of continuous improvement, The production process and application of magnesium chromium refractory materials in the copper smelting industry are becoming increasingly mature. There are several types of magnesium chromium refractory materials commonly used in the copper smelting industry:

(1) Ordinary silicate bonded magnesium chromium bricks

The magnesium chromium brick combined with ordinary silicate is formed by firing lower grade magnesia and lower grade chromium ore at 1550 ℃. The magnesium chromium brick combined with ordinary silicate contains more silicate phase, and the quantity of secondary spinel is relatively small, forming a microstructure of silicic acid phase wrapped periclase phase.

In ordinary silicate bonded magnesia chrome bricks, the low melting point silicate phase separates and wraps the high melting point periclase and chromite, while the high melting point periclase and chromite are directly bonded with silicate without forming a direct bonding structure. The low melting point silicates are interconnected to form a continuous phase; The silicate phase with low melting point is easily softened and dissolved during use, seriously affecting the load-bearing softening temperature, thermal strength, volume stability and other properties of magnesium chromium bricks; In addition, cracks can propagate through the silicate glass phase, and slag is also more prone to penetration and corrosion from the weak silicate glass phase. Therefore, the thermal shock resistance and slag corrosion resistance of silicate bonded magnesium chromium bricks are poor.

Magnesia is one of the important raw materials for refractory materials, used in the manufacturing of various magnesium bricks, magnesium aluminum bricks, ramming materials, furnace repair materials, etc. It contains a lot of impurities and is used for laying steel furnace bottoms, etc.

High purity magnesium sand is made by flotation purification of natural high-grade magnesite ore and calcination in a light burned, finely ground, and pressed ball ultra-high temperature oil shaft kiln. It is a high-quality raw material for brick making refractory materials.

Medium grade magnesia is produced from lightly burned magnesium oxide with a MgO content of 97% through processes such as ball pressing and high-temperature vertical kiln calcination. The product has good sintering degree and dense crystallization, making it a high-quality raw material for producing medium grade magnesium refractory products.

The purpose of ladle magnesia carbon bricks and magnesia bricks:

Magnesium bricks are widely used in steelmaking furnace linings, ferroalloy furnaces, and mixed iron furnaces in the steel industry due to their good high-temperature performance and strong resistance to alkaline slag; Non ferrous metallurgical industrial furnaces, such as copper, lead, zinc, and tin lining; Lime kilns in the building materials industry; Glass industry regenerator grids and heat exchangers; High temperature calcination kilns, vertical kilns, and tunnel kilns in the refractory material industry.

Classification of magnesia bricks:

Magnesia bricks are generally divided into sintered magnesia bricks and chemically bonded magnesia bricks. Magnesia bricks with high purity and firing temperature are called directly bonded magnesia bricks because periclase grains are in direct contact; The brick made of fused magnesia is called fused and bonded magnesia brick.