The standard name of mid-range magnesia is sintered magnesia. GB / T 2273-1998 combines the two national standards of "magnesia" "high-quality magnesia" into one standard "sintered magnesia". Sintered magnesia is made magnesite, magnesite magnesium hydroxide extracted seawater by high temperature calcination. Strong resistance to hydration. The magnesite is calcined at 700-950 ℃ to escape CO2. The resulting magnesia is a soft porous loose material cannot be used for refractory materials. Magnesia. The primary calcination two-step calcination process using high-temperature equipment such as shaft kilns rotary kilns. Burned magnesia fired with natural magnesite as raw materials is called sintered magnesia; sintered magnesia is divided into 18 numbers according to its physical chemical indicators See GB / T 2273-1998 for details. It is called fused magnesia by using magnesite the like as a raw material after smelting in an electric arc furnace cooling to a molten state; it is called seawater magnesia by extracting magnesium oxide seawater. Magnesia is one of the most important raw materials for refractory materials. It is used to manufacture various kinds of magnesia bricks, magnesia aluminum bricks, ramming materials, furnace repair materials, etc. Containing more impurities, it is used to lay the bottom of steel making furnace.
The mid-range magnesia is produced by using lightly burned magnesium oxide with a MgO content of 97% as the raw material, through ball pressing high-temperature shaft kiln calcination. The sintering degree is good the crystal is dense. It is a high-quality raw material for producing mid-grade magnesium refractory products.
The origin of magnesite is mainly twofold. First, the external genesis is produced in sedimentary rocks: the price of re-burned magnesia. Most of these layered detrital sedimentary rocks carry organic components organisms. In other words, magnesite is formed by biological action under low oxygen conditions;
Second, formed in the hydrothermal veins of medium to low temperature: magnesite is commonly found in metamorphic sedimentary rocks, which are gangue minerals formed after hydrothermal accumulation; in addition, magnesite may also appear in pegmatite.
Common symbiotic minerals are: quartz, pyrite, limonite, goethite, chalcopyrite, sphalerite, cryolite, Galena, barite, calcite, dolomite, fluorite, etc.
Due to the similar crystal structure of each mineral, they have many similar physical properties, including: belonging to the trigonal system, (trigonal)-the crystal form is mostly rhombohedral scalenohedron, there are three groups of well-developed rhombohedral cleavage, transparent rhombohedron The crystal has a phenomenon of double refraction (doublerefraction). In fact, the cations in the mineral composition can completely replace each other to form a series of solid solutions, so the discrimination between minerals may become more difficult.
Magnesia can be divided into fused magnesia, mid-range magnesia, high-purity magnesia re-burned magnesia. High-purity magnesia is produced by flotation purification of natural super magnesite ore, calcined by light burning, fine grinding, ball pressing ultra-high temperature oil shaft kiln. The purpose of high-purity magnesia is that it is a high-quality raw material for making bricks indefinite refractory materials.
Despite the vigorous development of the domestic refractory industry in recent years, some people still believe that China's refractory production is still at the low end compared with international high-end products, the quality market are lacking in competitiveness. According to industry sources, the current low level of modernization of China's refractory industry, backward technology low independent innovation ability are the main obstacles to the development of refractory materials.
In the process of building refractory materials, we must strictly control every detail every link. Only in this way can the construction quality be guaranteed the service life of the refractory materials can be guaranteed. At the same time, it is also crucial to strictly abide by the specifications improve the overall technical level of the construction team. At present, except for some large cement groups in China that have relatively stable maintenance teams, most small medium-sized cement companies rely on foreign construction teams to repair replace refractory materials, thus restricting the overall construction quality of refractory materials to varying degrees.
China's refractory industry has its own advantages, such as cost-effectiveness advantages resource advantages. This is different Japan other resource-deficit countries that mainly rely on imports. How to turn these advantages into market advantages also needs to improve the technical strength of enterprises, increase investment in science technology, improve product quality.
Daling Village, Guantun Town, Dashiqiao City, Liaoning Province
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