Basic properties of refractory material for steel making

• 
  Refractory materials for converter

The furnace cap, tapping converter mouth, before and after the surface, the weld pool and the bottom are made of magnesia carbon brick; the trunnion and the slag line part using high strength magnesia carbon brick. Magnesia carbon brick in MgO content is 70 ~ 75%, the content of graphite is 16 ~ 20%, the bulk density is 2.8 ~ 2.9g/cm3,

the compressive strength of 25 ~ 30MPa.High strength magnesia carbon brick, with the elements of magnesia carbon brick, but the compressive strength of 30 ~ 42MPa.

• With refractory furnace

Furnace hearth, furnace slope and the molten pool for magnesia overall tie, or the use of magnesia carbon brick and tar bonded brick; hot and slag line area, the use of high-quality magnesia carbon brick; the furnace door on both sides and tapping El for magnesia brick, magnetite chrome brick; furnace cover for high alumina bricks or high alumina unfired brick.

• Refractories for UHP EAF

Ultra high power permanent lining for magnesium stone, door jamb magnesia chrome brick, slag line brick, hot spots for magnesia carbon brick, wall of the furnace for magnesia carbon brick, eccentric bottom and pool for magnesia brick, tapping into magnesia carbon brick, high alumina brick furnace cover, tapping hole filling is High-speed Rail dolomite filling material.

• Refractory materials used in open hearth furnace
  

The working conditions of various steel furnace can be seen, refractory material working environment is very bad, therefore, no matter what the use of refractory material, must have the following properties:

1. High temperature resistant has high refractoriness.
2. Erosion and erosion resistance to high temperature of molten steel and slag.
3. The steelmaking furnace for intermittent operation, requirements of the refractory material has good thermal shock resistance and spalling resistance.
4. Has high mechanical strength, impact can withstand the tilting and loading charge without damage.

Functional refractories introduction

What is the functional refractory material? Functional refractory material is a kind of special refractory material to form with the development of iron and steel metallurgy continuous casting technology. Also known as metallurgical refractory material. Or it can be defined as: functional refractory material is with special or special preparation process with special properties and structure of a kind of high-grade refractory materials, plays a role in the process of using specialized in high temperature. In a sense, can be called refractory functional element.

Refractory products currently include functional refractories are: sliding gate, long nozzle, stopper, submerged entry nozzle (also known as the continuous casting three pieces), permeable brick and fixed diameter nozzle. Each product plays a role in the use of special casting process, such as control flow, air blowing agitation; prevent the two oxidation protective casting, decision flow field of molten steel in the crystallizer.

Functional refractories are presented as a separate refractory material, not only because they are single member in the form of application and the special function in use, but also in the fact that this kind of material is required to meet the usually more demanding conditions of use of the special function, to meet the special structure using function according to the special manufacturing process.

Compared with other steel smelting furnace lining refractory products, to a certain extent, the quality which may affect the lining service time, and functional refractory material quality, it may affect the whole casting process can be. This requires a functional refractory material not only with the conventional contact of liquid steel, slag and liquid refractories also to have the advantages of high temperature resistance, basic function, slag and liquid steel erosion and, according to different conditions, with special or special requirements in structure, material, production technology and process in the use of safe and reliable performance.

Unshaped refractory --refractory mud introduction

Refractory clay is also called exothermic or joint material (powder material). Used as a refractory masonry building materials. By materials can be divided into clay, high alumina, and 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 the fire clay. With refractory clinker powder and the amount of plastic clay as binder and plasticizer and made known common refractory clay, its strength at room temperature is low, formed at high temperature ceramics with high strength. Water, gas or heat hard binding material as the known chemical bond with refractory clay, below the form ceramic with temperature before that produce a certain chemical reaction and hardening

Selection of refractory slurry material, should consider and refractory masonry material consistent. Refractory clay except for building materials can also be used to smear method or spraying method is used as a protective coating of the lining of the body.

Mud properties and application of fire:

1. good plasticity, easy construction; high bond strength, anti erosion ability; high refractoriness, up to 1650 ± 50 ℃; anti slag is good; 5, good thermal spalling. Refractory clay is mainly used in the coke oven, glass furnace, hot blast furnace, and other industrial furnace.
2. the application of industry: metallurgy, building materials, machinery, petrochemical, glass, boiler, electric power, iron and steel, cement, etc…

Cause of carbon containing refractories not suitable for using in the Nickel Converter.

Due to the poor wettability of molten slag and graphite, graphite to refractory oxides can greatly reduce the infiltration depth of slag refractory material, thereby reducing the thermal spalling and flaking refractories. Therefore, in the iron and steel industry especially some intermittent production equipment such as hot metal pretreatment tank (or bucket), oxygen converter, electric furnace, ladle, extensive use of carbon containing refractories, and achieved good results. Naturally want to carbon containing refractories used in copper, nickel converter, but the effect is not ideal. The former Soviet Union, Japan and China have in copper or Nickel Converter tried MgO – C, C, but the effect is not ideal.

Why the carbon containing refractories in the iron and steel industry especially the effect of oxygen converter steel making is very good, but in the smelting of copper, nickel converter is not ideal?

Metal melt the iron and steel industry is the Fe.c melt. The blast furnace gas contains large amounts of CO, carbon in liquid iron at or near saturation; natural, blast furnace, hot metal pretreatment tank available carbon and carbon containing material. The important task of oxygen converter steel making is to reduce the carbon in liquid iron, steel will precipitate a large number of CO gas, in iron making, converter, oxygen pressure is very low.

Copper or nickel converter blowing to the matte or ice nickel (nickel matte, ice is Cu – Fe – S or Ni – Fe-s sulfide melt) FeS oxidation in the melt of FeO, into the molten slag.

As long as the partial pressure of CO is less than CO equilibrium partial pressure 5.02 × 105 kPa, carbon refractories in carbon will be oxidized. While copper, nickel converter, CO partial pressure is small, far more than the CO equilibrium partial pressure 5.02 × 105 kPa much smaller; thus in refractories containing carbon, oxidation tendency is very large, it is easy to be oxidized. So the copper or Nickel Converter with carbon containing refractory lining, the use effect is not ideal.

The development prospects of refractory ceramic fiber

Due to rising energy prices, fuel costs will become a bottleneck for the development of ceramic industry control, energy conservation is more important. The more people concerned about the furnace heat loss and, some directly in the original lining layer adhered to the refractory ceramic fibers to enhance thermal efficiency. In the add must be before the kiln wall obvious cracks or spalling parts repair. But the insulating refractory bricks and refractory fiber can not be arbitrary abuse. So far as the basic oxygen steelmaking furnace,

cement rotary kiln lining, due to the high temperature chemical erosion, temporarily can not be used for lining of fiber.

For the continuous heating equipment such as ceramic tunnel kiln, have realized the refractory ceramic fibers used as continuous heating equipment lining, according to some reports, the rapid push board kiln and tunnel kiln energy saving effects of the refractory ceramic fibers are very significant. Especially the ultra high temperature heating, such as sintering temperature in the furnace is 1538 ℃ - 1649 ℃, the best energy saving effects of the refractory fiber.

At present, the ceramic kiln equipment in Europe and America and Japan using all ceramic fiber lining. Not long ago, Japan will gas tunnel kiln decomposition such as carriage structure of segmented manufacturing, then to porcelain factory construction site assembly, all of this is due to the use of ceramic fiber material, greatly saves the cost of more convenient because of the kiln. To promote the study of effect of energy-saving ceramic fiber material modification products from the ongoing.

Refractory ramming material and its characteristics

Refractory ramming material is bonded granular material consists of very high proportion and the proportion of very low and other ingredients, even all the grain, powder material, to the strong pound bulk material to fight the way construction.

Because the ramming material is mainly used for direct contact with the melt, the grain, powder material must have high volume stability, compactness and erosion resistance, used for induction furnace should also be provided with insulation.

Bonded ramming choice should be appropriate, some without bond, some only add a small amount of flux. Acidic castable material commonly used sodium silicate, ethyl silicate, silica gel bonded, the dry ramming material with borate; alkaline ramming material used magnesium chloride and sulfate; often use carbon containing higher at high temperature can be formed with organic carbon and temporary binder. The dry ramming material and fluxing agent amount of iron. Chrome ramming material used to mount pin.

Other unshaped refractory materials compared with similar material ramming material, a dry or semi dry loose,

rely on the strong ramming to obtain compact structure, only the heating to the sintering temperature, the combination will have the strength. Castable refractory after forming, according to the characteristics of mixed hardening, adopt different heating methods to promote the hardening or sintering.

Such as containing inorganic chemical bond, self hardening reached a considerable strength after baking mould; containing thermoplastic carbon mixture, after cooling has considerable strength and release, before use should be rapidly heated and coking; without bond hardening at room temperature, often with a model for sintering in the ramming.