Development and progress of refractory materials for dolomite manufacturers

The dolomite refractory material represented by dolomite powder is the traditional refractory material since the invention of Thomas converter in 1879. As mentioned above, the price of dolomite sand belongs to the new refractory material as refractory brick, which is an ancient and young refractory material. Material. It is a refractory material that is frequently used for the bottom material and repair material of the well-known open hearth and electric furnace.

The dolomite refractories used as refractory bricks were not used at that time for reasons other than the absence of Thomas converters, and there were many places with high temperature and humidity in Japan. That is to say, raw dolomite (CaCO3, MgCO3 ) produced by the sintering of free lime (free) caused by the phenomenon of hydration collapse. However, compared with foreign countries with low temperature and low humidity, the problem of hydration is relatively large. Thomas successfully imparted hydration resistance to raw dolomite bricks by blocking the outside air, but did not completely solve the hydration problem. In fact, most of the research on dolomite refractories before World War II has tended to water resistance and resistance, the so-called stability, which is also related to the classification of dolomite refractories.

Dolomite sand 40-80 mesh manufacturers

dolomite sand price

General dolomite refractories are divided into:

(1) Completely stable dolomite;

(2) Semi (quasi) stable dolomite.

(1) In order to add other components such as SiO2 to remove free substances; (2) In order to reduce free or water resistance by other methods (adding tar, etc.), it is also called stable dolomite.

The research on stability began around 191. Many studies were carried out in Europe to study Fe2O3, Al2O3, Cr2O3, SiO2, ZrO2, etc. as stable components. As a result, SiO2 has received attention for its refractory properties. Therefore, The first industrial example seen was the stable dolomite brick made by adding Sudanite rock in England in 1935. In addition, other calculation methods of multi-component mineral composition were also proposed. However, in the Second World War, due to the reasons of refractory resources, except for the actual effect of the use of electric furnaces in the United Kingdom, even in Europe and the United States, there was no formal application.

Japan has studied the stability of dolomite from before World War II, and has also conducted continuous research after World War II. Some of them are used in the lining of melting phosphate fertilizer manufacturing furnaces, which are not very sufficient in quantity and quality, and their applicability in the steel industry is not very transparent. Around 1953, when the LD steelmaking furnace was introduced to Yawata Company, the stable dolomite brick developed by Kyushu Refractory Company was selected as one of the candidate refractory materials for converters. Officially used on the actual stove in 1957. Since then, this stable dolomite brick has made a great contribution to the development of LD converter steelmaking after its introduction as a refractory material for LD converters in Japan, together with the tar dolomite bricks discussed in the following chapters.

The chemical composition of this stable dolomite is MgO--SiO2 system, and the mineral composition is MgO-3-SiO2 system. Because of its free content, it has the same high affinity as its literal meaning. Larger restrictions are welcome due to the Japanese climate. Due to the presence of disilicate, powdering occurs along with the phase transition. Except for the addition of trace amounts of P2O3 and B2O5 as inhibitors, the price of dolomite sand has no components. Its manufacturing process is shown in Figure 1. In order to manufacture stable ore sand, because dolomite and stable substances (minerals containing SiO2 such as serpentine) should be reacted in a rotary kiln at high temperature, this kind of refractory brick is also It is called reburned dolomite brick.

Various companies have tried the application and development of tar dolomite bricks as semi-stable refractory bricks in LD converters.

The countermeasures for semi-stable tar-type dolomite bricks are:

(1) Dolomite sand (semi-stable, containing free), used in sintering.

(2) Sand is used for the fine powder part.

(3) After adding tar, kneading and molding, drying treatment is performed.