Magnesium chrome bricks are called according to different production processes

Isa furnace is similar to most nonferrous metal kilns, mainly composed of furnace bottom, furnace stack and furnace top.

The bottom of the Isa furnace is reverse arched and inclined to the vent by about 2%. It can also be built into a flat bottom. The total thickness of the furnace bottom is about 8001000mm, which is generally made of clay bricks, magnesia chrome bricks and magnesia chrome ramming materials.

The following conditions shall be met before the masonry of Isa furnace:

(1) The roof of the workshop around the Isa furnace is installed to prevent rain and snow;

(2) After the installation of the workbench in front of the furnace, it can be used as the material stacking site for bricklaying;

(3) All metal components of the furnace body have been installed;

(4) All installed cooling parts are qualified through on-site pressure test;

(5) There is a location for installing hoisting equipment;

The preparation work fully meets the construction requirements and safety requirements.

1. What is magnesia chrome brick?

Magnesia chrome bricks are refractory products with magnesia Mg0) and chromic trioxide C, 0 as the main components and periclase and spinel as the main mineral components. This kind of brick has high refractoriness, high temperature strength, strong resistance to alkaline slag corrosion, excellent thermal stability and certain adaptability to acid slag. The main raw materials for making magnesia chrome bricks are sintered magnesia and chromite. The purity of magnesia raw materials should be as high as possible. The chemical composition of chromite should be C, 0,30%~45%, and Ca0 should not be greater than 1.0%~1.5%. The production process of magnesia chrome bricks is similar to that of magnesia bricks. In order to eliminate the loose effect caused by the expansion of spinel formed by the reaction of M0 and C, 0, A, 0, or iron oxides during the firing process of bricks, the synthetic common sintering materials can also be used to make magnesia chrome bricks. In addition, there are unburned magnesia chrome bricks, such as unburned magnesia chrome bricks combined with inorganic magnesium salt solution. The production process of unburned magnesia chrome bricks is simple, the cost is low, and the thermal stability is good, but the high temperature strength is far less than that of fired bricks. In the late 1950s, a so-called "direct bonding" magnesia chrome brick was developed. This brick is characterized by pure raw materials, high firing temperature, direct combination between high temperature phases such as periclase and spinel, and island distribution of low melting phases such as silicate. Therefore, the high temperature strength and slag resistance of the brick are significantly improved.

It is an effective measure to eliminate the loose effect by using the fine powder made by grinding and calcining the compact of chrome ore and magnesia to mix with the coarse grains of magnesia to make bricks. Compared with ordinary magnesia chrome bricks, the magnesia chrome bricks made by this method have lower porosity, higher compressive strength, load softening temperature and flexural strength. The magnesia chrome brick made of chrome ore magnesite powder compact and calcined magnesia chrome sand at high temperature has better slag resistance and high temperature strength than other magnesia chrome bricks.

In addition, there are also fused grains of fused magnesia chrome bricks produced from fused magnesia chrome bricks directly cast from fused magnesia chrome materials in electric arc furnace and then combined with magnesia chrome bricks.

Magnesium chrome bricks are mainly used in metallurgy industry, such as building open hearth furnace tops, electric furnace tops, external refining furnaces and various non-ferrous metal smelting furnaces. The high temperature part of the ultra-high power electric furnace wall is made of fused cast magnesia chrome bricks, the high erosion area of the external refining furnace is made of synthetic materials, and the high erosion area of the nonferrous metal flash smelting furnace is made of fused cast magnesia chrome bricks and synthetic materials. In addition, magnesia chrome bricks are also used in the sintering zone of cement rotary kilns and the regenerator of glass kilns.

2. What are the classification of magnesia chrome bricks according to production methods?

Magnesia chrome brick is an alkaline refractory product containing Mg055%~80% and C, 038%~20%, which is composed of periclase, composite spinel and a small amount of silicate phase. Composite spinel includes MgAl2O4, MgFe2O4, MgCr2Oa, FeAl, O, and other spinel solid solutions.

Magnesia chrome bricks have been developed rapidly since the 1960s due to the improvement of raw material purity and firing temperature. At present, according to different production methods, magnesia chrome bricks can be divided into ordinary bricks, direct bonded bricks, common fired bricks, re bonded bricks and fused cast bricks.

(1) Ordinary magnesia chrome brick

This is a traditional product, with chrome ore as the coarse particle and magnesia as the fine powder. Or the two materials are composed of graded particles, and the firing temperature is generally 1550~1600 ℃. The microstructure of this kind of brick shows that there is little direct combination between chrome ore particles and periclase, and most of them are silicate (CMS) cementation or fissure isolation; There are few desolvated phases in periclase and few direct bonding in matrix. This kind of brick has poor mechanical properties and slag corrosion resistance.

(2) Direct bonded magnesia chrome brick

The direct bonded magnesia chrome brick is developed on the basis of ordinary magnesia chrome brick. Its production features mainly include two aspects: first, using pure raw materials, and second, using higher firing temperature. The so-called direct bonding means that there is more direct contact between chrome ore particles and periclase in the brick. Because there is less 502 in the raw materials (controlled below 1%~25%) and less silicate generation, the silicate is squeezed into the corner of the solid particles by means of high-temperature sintering. So as to improve the direct combination of solid phase.

Easy refractory:

The direct bonded magnesia chrome brick has high high temperature strength, slag resistance, corrosion resistance, erosion resistance, corrosion resistance, excellent thermal shock stability and volume stability at 1800 ℃ due to its high direct bonding degree.