Converter Magnesium Gunning Material

BOF large surface filler ,magnesium spray filler,furnace brick and steel hole repair material

1.BOF large surface filler:Adopts high quality magnesia as the main raw material,by adding the special additives such as modified asphalt,flowing agent and sintering agent to be made.The product has the characteristics of excellent spread ability and fast sintering under high temperature.It is suitable for hot repare of converter large surface and steel tapping hole.

2.BOF gunning material:By using high quality magnesia,magnesia-calcium sand as main raw materials and determing reasonably granular coposition,adding additives and binders to be made.The product has the characteristics of convenient construction,high adhesion rate and good corrosion resistance.It is suitable for spouting on converter trunnion and slag line,etc.

3.Fetting brick:Adopts various grades of sintered magnesia,electro-fused magnesia,asphalt and graphite as raw materials and pressed into certain shapes.The product is mainly used for repairing the front and rear surfaces of the converter to improve the service life of the converter.

4.Steel tapping hole repair:It has quick sintering speed,strong corrosion resistance and erosion resistance,very suitable for hot repair and maintenance of steel outlet of converter.

 

The amorphous refractory material used to repair the lining of thermal equipment by spraying construction method. It is composed of refractory aggregates with a certain particle size distribution, binders and additives (including accelerators, plasticizers, sintering aids and mineralizers, etc.), which are generally heat-hardening or gas-hardening materials. Spraying repair is usually a repair method used when the furnace lining is partially damaged prematurely but most of it is still intact. It can make the furnace lining reach balanced or nearly balanced damage. Its characteristics are simple construction, short construction period, no templates and brackets are required for construction, and it can effectively extend the life of the furnace lining and reduce the consumption of refractory materials.

Classification According to the main material of the gunning material, it can be divided into magnesium oxide, magnesium calcium magnesium chromium, magnesium carbon, aluminum silicate and aluminum oxide-silicon carbide-carbon gunning material, etc.; according to the construction method, it can be divided into wet method (mud method) gunning material, semi-dry method (nozzle mixing) gunning material and flame method (melt spraying method) gunning material. According to the use conditions, it can be divided into converter gunning material, electric furnace gunning material, steel ladle gunning material, vacuum degassing device (RH, DH) gunning material, iron ditch gunning material and blast furnace lining gunning material.

The composition, performance and use effect of the refractory gunning material used are different due to different construction methods.

Wet gunning is a method of mixing refractory aggregate, binder, additives and water to make a slurry of a certain consistency, and then spraying the slurry onto the gunning surface through a gunning machine with compressed air. Its characteristics are simple operation, high adhesion rate and rapid sintering, but due to its high water content and fine particles, its shrinkage is also large. At the same time, due to the thin spraying layer, its durability is not very good.

1) First of all, it must have good adhesion. The material can be pressed, gunned and adhered to the red-hot parts. For this, the particle size composition of the material is a very important factor, and the type of binder is also very important.

2) The workability should be good. The material has good wettability with water and can flow smoothly in the pipe and nozzle. This is also closely related to adhesion.

3) Durability should be good. Not only the chemical composition is important, but also the high-temperature strength after attachment. The material after attachment is required to be welded to the furnace wall and sintered well.

The converter gunning materials that can meet the above requirements are magnesia, self-marine, and magnesia in foreign countries. Japan mainly uses magnesia gunning materials, and dolomite is also used. The addition of binders is to make it have good adhesion and facilitate construction and use. Among these binders, there are sodium silicate and phosphate binders. Now the main binder is polyphosphate binder. That is to say, if you want to increase the adhesion rate of the initial gunning, you can use sodium oxalate binder, but its strength decreases at high temperature, and its volume stability is not good, so the adhesion to the furnace wall is weakened, especially during high-temperature blowing, it cannot be expected to have good durability. The superiority of phosphate binder.

The bonding mechanism of gunning material should first consider the viscosity of the gunning material, that is, it is hoped that the viscosity is small during the pressure delivery and the viscosity is large when it is attached to the repair surface. Water has the greatest impact on viscosity, followed by the amount of micropowder, so it is hoped that there will be more water during pressure delivery and gunning, and some water should be evaporated before reaching the repair surface, and when it reaches the repair surface, the water should be reduced and the viscosity should be increased.

The gunning material after attachment is best hardened as soon as possible by the action of the binder, and the amount of micropowder of the main material also has a great effect on hardening, and secondly, the less water, the faster the hardening.

The durability of the gunning material is also very important, so the gunning material must have good slag resistance, and at the same time, it must not peel off, have a large filling density, a low porosity, and no deterioration and peeling due to slag infiltration. Some raw materials have the opposite properties.

Therefore, it is best to determine the performance based on the type of raw materials, particle size composition, type of binder and amount added.

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