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Classification and advantages of magnesia chrome bricks for copper converter

2021-02-03 11:16:08
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Directly bonded magnesia-chrome bricks are made of high-grade magnesia and chromium concentrates with low impurities such as silico-magnesia-chrome brick manufacturers. They are fired at a high temperature of about 1700℃; in direct-bonded magnesia-chrome bricks, there is a relatively small amount of silicate phase. The silicate phase exists in the matrix in the form of islands, and the periclase-periclase and periclase-composite spinel are directly bonded, so the direct-bonded magnesia-chrome brick has good high temperature resistance, corrosion resistance and Thermal shock resistance.


Combined magnesia-chrome bricks are refractory products made by sintering high-temperature magnesia-chrome or fused magnesia-chrome raw materials at 1750℃ or above; combined with magnesia-chrome bricks, the spinel phase is evenly distributed and the grains are directly bonded. Well, the combined magnesia chrome brick has better corrosion resistance and erosion resistance than ordinary silicate combined magnesia chrome brick and direct combined magnesia chrome brick.


Semi-recombined magnesia chrome brick is located in the use of a part of directly combined magnesia chrome brick raw materials to replace the pre-synthetic raw materials in the recombined bricks. It is a transitional product of recombined bricks and direct combined. Due to the use of high-grade magnesia Compared with recombined magnesia chrome bricks, it has better thermal shock resistance.

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According to the different raw materials and production processes, the magnesia-chrome bricks commonly used in the copper smelting industry can be divided into: 1) ordinary silicate combined with magnesia-chrome bricks; 2) directly combined with magnesia-chrome bricks; 3) combined with magnesia-chrome bricks; 4 ) Semi-recombined magnesia chrome brick; 5) co-fired magnesia chrome brick; 6) fused cast magnesia chrome brick. These 6 types of magnesia-chrome bricks have different thermal shock resistance and erosion resistance. Generally speaking, refractory materials cannot take into account both thermal shock resistance and erosion resistance.


The magnesia-chrome bricks with two different CrO3 contents were treated by vacuum impregnation with magnesium salt solution, and the physical properties and pore size distribution of the samples before and after the impregnation were analyzed. The static crucible method and the autoclave reaction method were used respectively. The slag resistance and hydration resistance of the samples before and after immersion were compared. The results showed that the apparent porosity of magnesia-chrome bricks decreased significantly, the bulk density increased, and the normal temperature compressive strength and normal temperature flexural strength increased significantly after being immersed in the magnesium salt solution; the percentage of pore volume in the sample with a pore diameter> 10 μm The 84.13% before salting dropped to 67.67% after salt immersion; the hydration resistance of the samples after immersion was significantly improved, and the slag resistance was improved to a certain extent.


In order to reduce the porosity of magnesia-chrome bricks and improve its slag resistance, the process of immersing magnesia-chrome bricks with salt is generally used in actual production. The process requires that the selected salt will not cause new pollution to the smelted metal, and will not cause pollution to the environment as much as possible, and it must not adversely affect the performance of the material. Because magnesium salt decomposes at a certain temperature, leaving only Mgo in the pores of the brick will not adversely affect the high temperature performance of the brick. Therefore, this work chooses magnesia salt as the leaching solution for magnesia-chrome bricks, and uses the fusion before and after the salt immersion to combine the magnesia-chrome bricks as the research samples to discuss the influence of salt immersion on the performance of magnesia-chrome bricks.

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