Improvement and using of furnace refractory material

Open hearth furnace masonry damage mainly caused by slag and liquid steel chemical erosion and high temperature corrosion and spalling. Open hearth is most easily damaged, is the weak link in the whole lining, directly related to the small yield of furnace. Therefore, all the countries take the thin furnace top as an important technical index of open hearth furnace; open hearth furnace life refers to the so-called top life. Enter sixty ages, the world each for open hearth furnace adopting ordinary alkaline brick masonry. China is widely used magnesia brick, the medium-sized open hearth furnace service life reached about 1000 times.

With the development of open hearth oxygen blowing intensified smelting, the production efficiency is improved, but the decline in life. To this end. We must improve the brick quality, development of new varieties, to meet the need of strict furnace smelting process. In this case, the British in the 1959 car developed directly combines the basic brick manufacturing, the key is using high purity raw materials, high pressure shaping and high temperature firing. In order to combine the firebrick and magnesia brick firing temperature and high temperature relation of bending strength. With increasing the burning amyl temperature, direct burning of magnesia chrome brick flexural strength increases, and magnesia brick to 1800 C strength decreases. As is said, in order to obtain the excellent combination of magnesium lead bricks, the sintering temperature should be greater than 1700 DEG C, the best sign about 1800 DEG C firing.

The creep of refractory material

Refractory material especially in the high temperature when subjected to below its ultimate strength under a certain stress will produce plastic deformation, deformation along with the load increasing, and even lead to the failure of materials. This external force generated by the deformation increased with time phenomenon called creep. Creep refractories are its stress compression under certain temperature and pressure effect after certain time generated to represent the creep. Sometimes often to achieve individual variables of time, can also be directly to the deformation or strain rate versus time curve description. The compressive stress strain measuring results is not easy to be keen reflected inside the material phase change, so often in the bending creep or creep (torsional shear creep) said.

Creep refractory material is a function of stress, temperature, time and material structure. Material at higher temperature, stress is bigger, the longer, the greater the creep rate. When the refractory material completely by the crystal structure, creep in addition to bond strength by the relevant and crystal elastic effects of crystal, crystal body is mainly controlled by vacancy diffusion, dislocation movement, the control with the state grain boundary sliding and grain. Crystal defects, grain boundaries are less and less grain combine is strong, not easy to produce serious creep.

When the material containing glass phase, especially when the glass phase as continuous phase, material creep by glass phase control. The higher the amount and viscosity of the glass phase is low, material under low stress can produce viscous flow, so in the high temperature creep is more serious. When the refractory materials containing high temperatures may form an impurity liquid phase, the formation of the impurity quantity of the liquid phase, the viscosity decreases with the increase of the temperature is faster, the more serious the creep.

The grain boundary of the refractory material in the pores or cracks can be directly caused by grain boundary sliding. In addition, in the high temperature materials in liquid phase to solid phase permeable pores in, especially to the infiltration of 25 mu m or less, in the small pores, thus holes exist, through the liquid phase migration also influence of creep. Therefore, the material porosity has great influence on the creep. Improve the porosity, actually can increase the creep rate.

Refractory mortar products structure

Refractory mortar composed of fine powder and a special binder mixing and compounding, natural air drying conditions have good strength and form combined with high strength joints, eventually form similar to the integral prefabricated structure of brick masonry.

JM2600: Air hardened clay, suitable for insulating refractory brick masonry low level, can be used for applying construction method and immersion method.

BLK: an advanced refractory clay, black, water retention property is very good, is designed for lightweight brick masonry and development, but also used in the construction of heavy bricks and high alumina heavy brick. Delivery consistency is suitable for thin layer repairing and painting method construction, about 5% moisture can be applied to the impregnation method construction. For the lightweight heat insulating brick masonry construction mainly, have a small amount of heavy brick, very suitable for single selection BLK mastic.

JM3300: high temper hard clay, suitable for building JM32 insulating brick and heavy high alumina refractory brick.

It is normally provided by type barreled to wet namely, with sealed metal barrels packaging.

Introduction and using range of refractory clay

Refractory clay is also called exothermic or joint material. Used as a refractory products masonry joint material.

By materials can be divided into clay, high alumina, silica and magnesia refractory mud. Composed of refractory powder, binder and additive. Refractory raw materials can be made for almost all of the powder used to compound refractory clay. With refractory clinker powder with the appropriate amount of plastic clay as binder and plasticizer and made known the ordinary refractory clay, the room temperature strength of low, high temperature formed ceramic combination has a higher strength. In hydraulic, air hardening or hot rigid binding material as the known chemical bond binding refractory clay, below the form ceramic combined with temperature before that produce a certain chemical reaction and hardening. Grain size of refractory mortar according to use requirements vary, the ultimate particle size generally less than 1mm, and some less than 0.5mm or more fine.

The selection of refractory slurry material should be considered with the refractory products masonry material consistent. Refractory clay except for joint materials can also be used to smear method or injection method is used as a protective coating liner.

Mud properties and application of refractory: 1, plasticity is good, the construction is convenient; 2, high bond strength, anti erosion ability; 3, high refractoriness, up to 1650 – 50 Deg. C; 4, good slag resistance, invasion; 5, good thermal spalling. Refractory clay is mainly used in the coke oven, glass furnace, hot blast furnace, and other industrial furnace.

The application of industry: metallurgy, building materials, machinery, petrochemical, electric power, boiler, glass, steel, cement and other.

Properties of semi silica refractory

(1) refractory

Higher silica content of semi silica refractory products, refractory degree can reach 650 to 1710 DEG C, close to the silica brick.

(2) load softening temperature

In the semi silica refractory products, forming part of the network structure, so the load softening temperature is slightly higher than the clayey refractory products, up to 1350 to 1450 DEG C.

(3) the thermal shock stability

Semi silica refractory products than the clayey refractory products thermal shock stability slightly worse, the general water cooling times is 10 or so, the reason is quartz expansion coefficient, rapid changes of temperature, volume changes lead to local stress concentration.

(4) the slag resistance

Semi silica refractory products in the chemical nature belongs to semi acidic, so resistant to acidic slag erosion ability.

(5) the line changes heavy firing

In the semi silica refractory products, due to the expansion of high temperature contraction offset silica clay, so the volume stability, than the clayey refractory product reheating linear change.

Refractory brick classification for cement kiln

1, high aluminum brick: Al2O3 content more than 75, refractory degrees higher than clay brick, acid and alkali resistance erosion resistance, suitable for cement kiln etc., the use of long life and high price of refractory brick.

2, the dolomite brick: Hang kiln skin performance is good, good erosion resistance, but there are brick in f-CaO number, hydrated, difficult to transport and storage, production with less.

3, magnesia chrome brick: Hang kiln skin good, used for firing zone, the disadvantage is the thermal shock performance is poor, plus six price Cr is highly toxic, the production and use of magnesite chrome bricks in countries gradually reduced, now with this firebrick production unit as soon as possible to find alternatives.

4, spinel brick: mainly used for transition zone, earthquake good performance, anti good reducibility, but refractoriness slightly worse.

5, anti flaking brick: this brick contains a small amount of ZrO, martensite phase transformation occurred during the heating process of the formation of fine crack, with strong alkali resistance, spalling resistance and slag resistance of good.

6, phosphate brick: Refractory degree is low, but the intensity of heat shock resistance, used for refrigerating machine, such as the use of kiln hood.

7, silicon carbide brick: high temperature (1800 degrees, refractoriness under load in the 1620-1640), small thermal expansion coefficient, high thermal shock have good wear resistance suitable for cooling zone and kiln mouth.

8, the silicon mullite brick: thermal shock resistance, high strength, good wear resistance, suitable for transition zone.

Correct methods to select good quality refractories with low cost

High temperature industrial development cannot do without refractorymaterial function, especially in the iron and steel, nonferrous metals, glass, ceramics, cement, petrochemical, machinery, boilers, light industry, electric power, military and other fields, is the basic material of an operation and technology industrial production, with each field of industry continue to increase, the demand quantity of refractory products is also gradually increasing, which requires every manufacturer increase production, while at the same time ensuring the production quality of the product is the most critical, it is also the fundamental in all areas of normal operation. For how to choose the right refractory is introduced in following four aspects:

1 according to the structure, working characteristics and motion conditions of the furnace and the analysis of material damage reasons, in order to choose the appropriate refractory. Accurate understanding and grasp the temperature changes of all parts of the material, carefully observe the material to prevent by all kinds of destructive effects, such as: high temperature molten metal erosion.

2 familiar with the material chemical composition and physical, work performance, so as to give full play to the characteristics of material.

3 so that all parts of the furnace material reasonable match, in order to avoid the mutual damage at the same time between material, but also take measures to ensure that the service life of the whole.

4 basic principles in satisfying the conditions above, to solve the resource and cost as much as possible. Can choose prices and transport costs low material, at the same time, vigorously develop the recycling, reduce the cost of.

We Xinmi Changxing refractories plant convenient transportation, rich in resources, is the base for the production of refractory materials ideal, high-quality refractory raw materials base believe refractory products can produce satisfactory.