The application of ceramic fiber refractory material

Application of ceramic fiber refractory material widely, now to introduce its is mainly used to:

1. The door of various insulation industrial kiln mouth seal, curtain.
2. The high temperature flue, wind tube bushing, expansion joint.
3. Petrochemical equipment, containers, pipelines and heat insulation, thermal insulation.
4. Under the environment of high temperature protective clothing, gloves, helmet, helmet, boots.
5. Automobile engine porcelain heat shield, heavy oil engine exhaust pipe package, Speed Racer composite friction brake pad.
6. High temperature liquid transfer pump, compressor, gas and valve packing, gasket.
7. High temperature electrical insulation.
8. Fire doors, fire curtain, refractory blanket, then spark with cushions and insulation cover fire sewing products.
9. Aerospace, aviation industry with insulation, insulation materials, friction brake pad.
10. Cryogenic equipment, containers, pipelines, heat insulation package.
11. The high-grade office archives, vault, safes and other important places of adiabatic, fire compartment, fire automatic shutter

Solutions to refractory brick shedding used in boiler

Because the boiler pouring material and refractory material damage loss, seriously affect the safe operation of the unit, and even cause non stop accident unit.

In order to ensure the long-term safe operation of the boiler, take the following measures from the operation of the adjustment

• Ignition methods.

1. The ignition temperature process, control the bed temperature and the outlet of the furnace, cyclone separator leg temperature change rate of not more than 80 ℃ / h.
2. By adjusting the fuel door or throttle back to change the oil amount, strengthen with the wind, to maintain the best air fuel ratio, temperature less than 700 ℃ burner piping.
3.  Maintain a volume greater than the minimum fluidizing air flow rate, gas temperature rise faster, by increasing the rise velocity of two air control flue temperature does not exceed the specified value.
4. Bed temperature at 330 ～ 350 ℃ with coal feeding conditions using dynamic way to coal, while adding one or two times volume control the bed temperature and gas temperature from rising too fast, strict monitoring, control the bed temperature and gas temperature change, and the change trend of monitoring oxygen master advanced quantity control the quantity of coal. When the cyclone separator population temperature changes smoothly, gradually changed to continuous coal, used to add less, more in the way of increasing coal, so as to control the bed temperature of furnace outlet flue gas temperature and avoid large fluctuations, reduced the refractories shedding

•    Furnace measures

1. Boiler shutdown process, control the bed temperature, strict furnace exit flue gas temperature drop speed of not more than 80 ℃ / h.
   
2. Slide stop, bed temperature and steam temperature, steam synchronization downhill, by adding one or two times volume decreased bed temperature, to avoid the high bed temperature shutdown period. When the bed temperature below 550 ℃ and the decreasing speed stop to the coal will be a volume is reduced to the minimum fluidizing air flow rate, the two volume is reduced to the minimum, avoid bed temperature drops too fast.
3. Boiler flameout, bed temperature should stop one or two wind turbines operating in more than 400 ℃, prevent the abrupt cooling, fan ventilation and stop running.
4. Fan stops running 4h, bed temperature below 400 ℃ can start fan cooling.

In the boiler start stop, peak shaving, machine breakdown and unit load rejection, strict control of smoke temperature change rate, thus pouring material and refractory protection is not damaged

Several species of castable

   Castable consists of aggregate, binder and admixtures. Depending on the binders can be divided into Portland cement castable, aluminate cement castable, castable sodium silicate, phosphate castable refractory concrete and clay combined with magnesia refractory castable.

   Portland cement castable concrete binder weight accounted for 7% -20%. Portland cement castable cementitious material used, the need to eliminate the role of calcium oxide. When the addition of 50% -100% by weight of cement of clinker fine clay powder as admixture, it combines with calcium oxide and aluminum to form a stable calcium silicate minerals. This refractory concrete stick low cost, available at the following 1000 ℃, temperature fluctuation is not, no acid erosion in places such as basic equipment, flues, chimneys, etc.

Aluminate cement castable based on alumina as binder to bauxite clinker as aggregate and blending material made ​​of hydraulic concrete. The main mineral bauxite is calcium aluminate cement hydration fast. Therefore, this concrete hardening, high early strength.

   Water glass castable is a water glass binder and add the appropriate amount of sodium silicon fluoride gas as hard concrete coagulant made​​. Silicone silicate hydrolysis of the aggregate, admixtures together. This concrete strength is relatively high, but the low refractoriness and load softening point, applies to the following 1000 ℃ require a higher strength, wear resistance, corrosion can antacid site, but not for regular water or water vapor effect place.

   

Phosphate castable based on industrial phosphoric acid binder, sometimes plus the amount of alumina cement as a coagulant and made of hot hard concrete. This is characteristic of concrete cured at room temperature without consolidation, in order to solidify and a certain intensity, to add coagulant. Was heated to 500 ℃ hardened consolidation, and the strength will be improved, but near 800 ℃, low temperature strength of its shortcomings, and strength after the temperature rise. This refractory concrete has excellent fire resistance, abrasion resistance, slag resistance and thermal shock resistance, long-term use under the conditions of 1400-1600 ℃.

   The casting material can be poured directly on the thermal equipment templates, add anchors inside after tamping after a certain curing period can be. Can also be made of prefabricated blocks, such as the vault, ceiling, wall oven, lid, door, etc., than the brick or directly casted, both during construction and replacement much more convenient.

U.S. levy anti-dumping taxes on China Refractories

U.S. Department of Commerce preliminary ruling made ​​by the first half of last year, China's exports to the U.S. decision to impose refractories ~ 91.16% 84.89% anti-dumping duty. The U.S. Commerce Department's announcement that day showed specific products being taxed at least 90% of silica containing silica brick.

This acid refractory is mainly used for masonry coke ovens, blast furnaces, glass kilns and other high-temperature furnaces.

Chinese exports to the U.S. silica brick case began in November 2012. Utah, a refractory company complaint, claiming that Chinese companies of dumping in the United States, asked the U.S. Department of Commerce initiated anti-dumping investigation, the dumping margin was made ​​up 118.47% ~ 290.12%.

U.S. Department of Commerce statistics show that in 2011 Chinese exports to the U.S. totaled about $43,240,000 silica brick, but in 2012 the total value of exports to the U.S. fell to $25.7 million sharply, a decline of nearly 40%.

For the United States frequently waving "trade stick", Chinese Ministry of Commerce has repeatedly stressed that trade protectionism is not only unfair to him, the country, there is no advantage to domestic companies, do not want the United States to measure high-sounding but actually with a strong political background to implementation of trade protectionism, but should abide by its commitment to oppose trade protectionism, with a more rational approach to properly handle trade frictions

Solutions for refractory castable expansion

In the application process of the refractory castable  often appear a certain degree of expansion coefficients, which will affect the quality of the work castable body. So, to the problem of refractory castable how to solve it? Castable refractory is a material made ​​by the granular and powdered materials, and add a certain amount of binder composition and water together.

Luoyang Elon Refractories technical staff tell everyone how to solve the problem of castable expansion:

1.    You can then add refractory castable aluminum dihydrogen phosphate, aluminum dihydrogen phosphate dosage should be controlled at 13% to 15%, but due to the liquid aluminum dihydrogen phosphate refractory generate hydrogen reacts with metallic iron at room temperature, and after pouring the liner body swell, parallel porous loose body.

2.    Since the cement composition contains a certain amount of metallic iron. Therefore, you must add the anti-bulging inhibitors (covert agent), or mixed castable liquid potassium dihydrogen phosphate was added in two hours. The specific method is first added 6% to 7% potassium dihydrogen phosphate in castable mixture , trapped material in the semi-wet state 24h. Before the second plus potassium dihydrogen phosphate, first add 2 to 3% of coagulant, the material mix well, then add the remaining 6-7% potassium dihydrogen phosphate solution, and then mixed evenly pouring. Expansion can be prevented in general.

3.    Porcelain ball mill grinding, or by using a strong acid (such as hydrochloric acid, etc.) washing powder and magnetic separation methods such as using less metal and other impurities into or excluded.

4.   Reduce the amount of cement, mixing inhibitor or improve molding pressure.

Foreign refractory recycling situation

Developed countries attach great importance to the re-use of refractories from resources, environmental protection height to understand, even with the development of laws and regulations strictly limit emissions after the refractory, which greatly promoted the study of the refractory recycling after refractory recycling rate has reached more than 60% and rising.

Japan to scrap steel slabs based raw materials, developed around the bottom of the ladle ramming mixes, ladle castable and styling products, such as: with 85% recycled material and 15% of new material to produce a molten pool area with no burning furnace brick, with 90% recycled material and 10% new material to produce electricity lines slag MgO-C, as well as all recycled materials to produce RH bottom burned magnesia chrome brick. Secondary use of technology Kashima Steel has developed a skateboard brick, using surface grinding, pouring castable recovery method, the Mosaic law makes skateboard ring after the repair has reached a new skateboard using the same effect; scrap iron ditch refractories are repeated use, primarily as A12O3-SiC-C castable aggregate.

Italian company has developed a method for recovering the refractory technology, mainly used for recycling of the furnace , tundish , ladle ingot mold and the refractory lining , and the recovered blowing directly into the furnace refractories to protect the furnace wall . American Refractories previously only a small amount of waste recycled , the rest almost completely buried. 1998 U.S. Department of Energy , Department of Industrial Technology and steel producers jointly developed a three-year plan to extend the life of refractories and refractory waste recycling .Refractory Factory cooperation with users to minimize the amount of the waste refractories . The United States also after dolomite brick as a soil conditioner and slagging agents were studied , and achieved good results.

India conducted the first study of waste refractories can be traced back to 1978, first in the steel company to carry out, the use of Indian steel company (now known as TISCO steel Branch) high alumina brick furnace waste generated (60% to 62% aluminum) production castable (56% alumina), fire clay (50% alumina) and fire-resistant plastic. Developed material which is mainly used for the production of cast burner tiles, dampers, tiles, etc., and can meet the requirements within the industry.

Overview of domestic refractories recycling

Our refractories for reuse after a late start, the relatively low recycling rate. According to reports, after the re-utilization of refractories for about 20%, some even use, but also to reduce the product quality for the price.

In recent years, most of the major domestic steel mills and factories have attached great importance to the refractories  recycling and reuse, ongoing research and application of all aspects of the work.

Baosteel better after Refractory reuse the work performed, the main blast furnace trough castable have been recycled as slag trough castable materials, prepared for the regeneration of MgO-C regenerated after treatment with the antioxidant and MgO-C strong slag resistance, long life advantages.

WISCO will use the aluminum-magnesium carbon debris classification, after removal of impurities, manually eradicate sticky residue and buffer layers, and magnetic separation and hydration treatment, using a jaw crusher crushing the material to 25mm or less, and finally with a hammer crusher processed into the desired particle size to produce renewable alumina magnesia.

Jigang aluminum carbon refractories (later abandoned skateboard brick, brick pedestal, outlet, plug the stick) for iron ditch Ramming expected to replace some high-alumina material. Magnesia chrome brick after as raw material, by a certain percentage added to the RH gunning years, with favorable results. Meanwhile, the better the performance of renewable prepared magnesia-chrome brick, cement kilns in non-critical areas and RH have better prospects.

At present, the domestic researchers also proposed: By adding an appropriate amount

in the refractory oxides useful in improving high-temperature performance to optimize the preparation of high quality modified material; through the reduction reaction of the transition temperature materials such as SiC,-Sialon, Mgalon etc. ; adopted by the brick after brick with a skateboard mullite; adopted by the silica brick, with C as a reducing agent synthesis SiC; using brick with a skateboard after synthesis-Sialon; using bricks with the skateboard, with the MgO-C synthetic oxide and non-oxide Mgalon and other composite materials to make products with high strength, thermal shock and erosion resistance, excellent performance, as a new and efficient high-temperature refractory materials for key parts of the equipment in order to achieve efficient use of resources and energy.

Refractory recyclable become refractory industry development trend. To achieve a breakthrough in the refractory industry, we must follow the needs of the community development.

Skateboard brick classification

Skateboarding refractory bricks are casting function, widely used in electric furnace, converter, ladle refining furnace and continuous casting tundish slide gate system. As molten and flow control switch mounted on the bottom of the ladle and tundish, exposed to a high temperature of about 1600 ℃ chemical attack of the molten steel, and a pressure of dozens or even hundreds of tons of liquid per ton of time. Therefore, the requirements skateboard brick with high temperature strength, excellent corrosion resistance, anti-erosion resistance and thermal shock resistance.

Meanwhile, in order to realize the function of opening and closing the flow of steel, brick skateboard sliding surface flatness and parallelism and dimensions must strictly comply with the requirements. Skateboard brick quality directly affect the safety of steel equipment and field operations personnel in the event of skateboard switch failure, rupture and other accidents, resulting in an outflow of molten steel, the consequences could be disastrous.

Material skateboard into high aluminumbrick, aluminum carbon, aluminum zirconium carbon three kinds; divided by the production process is not dipping, dipping, retorting three kinds; By physical and chemical indicators into HBL-55, HBLT-65, HBLT-70, HBLT-75, HBLTG-65, HBLTG-70, HBLTG-75 7 grades.