Drainage sand for ladle drainage has four basic requirements:
Diversion sand in the ladle water mouth for a long time in a high temperature state, the requirements of the sintering layer of high refractoriness; diversion sand filled into the mouth of the water directly in contact with the molten steel, the beginning of the sintering temperature should not be too high; in the process of use, the diversion sand to withstand a greater static pressure of molten steel, in order to prevent taut material, the diversion sand is required to have a very good mobility, as much as possible between the particles of the friction is small; the diversion of sand in the high temperature, to prevent the diversion of sand in the use of process Automatic fall or can not effectively support the upper material. Based on the above requirements, to meet in the practical application of four common types of diversion sand:
Magnesian-olivine, siliciclastic, zirconic, and chromic drainage sands.
1. Magnesia olivine drainage sand. The basic performance of magnesium olivine diversion sand can meet the basic requirements of diversion sand, is a kind of cheap diversion sand. But the actual application, mold casting of automatic pouring rate can reach 95%, but in continuous casting, automatic pouring rate is low. In the steel mill now, the proportion of the use of this type of diversion sand is about 15-20%.
2. Silica sand diversion sand. Silica sand melting point of about 1680-1700 ℃, the application of more, but the quartz sand at 1200 ℃ or more will be due to the phase change caused by a large volume expansion, resulting in filling sand and water mouth wall adhesion increases, unreasonable to open the pouring of filling sand free fall, and even appear "bridge" phenomenon. In addition, the quartz sand after artificial processing shows that there are many angles and irregularities, so the natural mobility is poor, easy to cause "taut material"; and the irregularity is easy to affect the self-opening rate. However, the silica diversion sand is currently the most used kind of diversion sand, accounting for about 50%-60%.
3. Zircon sand generally w(ZrSiO4) ≥97%, free w(SiO2) ≤2%, w(impurity) ≤1%, melting point is higher than 1800℃. Zircon has been used as casting sand and continuous casting lead sand material due to its excellent properties such as low thermal expansion, good thermal conductivity, high bulk density, good stability, not easy to be wetted by the liquid steel, etc., and at the same time, it is in the shape of round particles. Zircon sand is less prone to sintering than silica sand, but it is limited by the high price, and is mostly used for intermediate ladle diversion.
4. Chromite composition w(Cr2O3), 32-35%; w(FeO), 14-17%; w(MgO), 12-18%; w(Al2O3), 16-
25%; w(SiO2) , 2-12%. melting point about 1730-1750°C. The chromium diversion sand is made of chromite and additives, and has the advantages of high specific gravity, good fluidity, high melting point, and no excessive sintering. In the chromium diversion sand, chromite is continuously distributed when the amount of chromite added is greater than 60%, and this distribution helps to form a continuous sintered layer. Under high temperature, FeO in chromite reacts to dissolve and form secondary spinel, which changes the volume of the sintered layer and produces cracks, so that when the slide plate is opened, the unsintered diversion sand in the lower part of the spout flows out rapidly, and the cracks in the sintered layer expand rapidly, and the sintered layer is completely destroyed under the action of the static pressure of molten steel, so that it can achieve the purpose of automatic opening of the pouring. Chromium quality diversion sand is used by most large steel mills, accounting for the whole ladle with diversion sand of 30% or so, especially the refining ladle.
Contact: Mr. Cao
Tel：0379-68527919
Mobile：13903798882
Address: Caopo Village, Cailing Township, Yichuan County, Luoyang City, China
Website: http://www.lykerd.com/