Continuous casting tundish magnesia coating
The present invention relates to a kind of lining material of casting the fused mass container, especially for the unshape refractory of continuous casting of molten steel tundish working lining.
The liner of continuous casting tundish generally inwardly is made up of for three layers heat shield liner, permanent liner and working lining successively from box hat.Because working lining directly contacts with the interior metal melt of bag, after use a period of time, working lining weathers, and lining adhesion residue, must global purge upgrade.Therefore, be, not only can not contain the material that influences steel quality, can not produce public hazards in the use the requirement of working lining material, heatproof corrosion resistant, long service life, easy construction, and remove to disintegrate and also want easily quick, and can not undermine permanent lining, require simultaneously to produce easily, price is more honest and cleaner.Working lining material commonly used at present is silica heat-insulating plate and magnesium chromium matter or the unsetting fireproof coating of dolomite matter.Adopt silica heat-insulating plate, the baking energy is saved in practicable cold bag cast, easy to operate, but corrosion resistance is poor, both has been unfavorable for sequence casting, easily make molten steel infiltrate nonmetallic inclusion again, and the moisture content in the heat-insulating shield easily cause molten steel to inhale hydrogen in the cast of cold bag, influences steel quality.And the advantage of magnesium chromium matter or dolomite matter coating is convenient for production, and price is low, can not cause molten steel to inhale hydrogen, and application property is good, and is easy to scarfing cinder and unpacks.But the Cr in the magnesium chromium matter coating
2O
3Easily produce public hazards.Dolomite matter coating then exists igloss big, and the dope layer pore is many under the high temperature, the shortcoming of poor durability.
Can not influence steel quality when the purpose of this invention is to provide a kind of use, do not produce public hazards, construction, disintegration are all easily convenient, and anti-corrosion resistance to slag is good, and qualities such as long service life more comprehensively are specially adapted to the unshape refractory of continuous casting of molten steel tundish working lining.
The working lining material of realizing above-mentioned purpose is one group of unsetting composition based on magnesia, and its composition and proportion of composing (percentage by weight) are as follows:
Magnesia 91~95% alumina cements 1~3%
Phosphate 1.5~2.5% plasticizer 1~4%
Anti-cracking agent 0.1~0.4% water reducer 0.2~0.6%
Fiber 0.2~0.3%
In above-mentioned prescription, magnesia is body material.Molten steel is not polluted in its high-temperature steel scouring.Its quality index is: contain MgO 〉=95%, SiO
2≤ 4.0%, CaO≤1.6%, particle volume density 〉=3.18g/cm
3, igloss amount≤0.3%.
Alumina cement plays the binding agent effect in component, when low temperature sufficient intensity is arranged, and the health baking is not come off.Its quality index is: contain Al
2O
3〉=50%, CaO 〉=33%.
Phosphate is high temperature adhesives, makes coating at high temperature in conjunction with firm, and anti-slag corrodes.This phosphate can be sodium phosphate trimer or calgon, calcium dihydrogen phosphate etc., preferred sodium phosphate trimer.The quality index of sodium phosphate trimer is: contain P
2O
5>56.5%, PH=9~10.
The adding of plasticizer mainly is the plasticity that strengthens coating, makes coating be easy to smear or spray, and reduces coating falling or bounce-back.Plasticizer can be clay or potato rubber powder, cornstarch etc., is good with clay.The quality requirement of clay is: contain Al
2O
3〉=30%, Fe
2O
3≤ 2%, by particle>90% of 0.09mm sieve aperture, igloss amount≤15%.
Anti-cracking agent mainly is can make to form steam channel in the coating, prevents to toast the floating coat explosion.Anti-cracking agent can be selected aluctyl or Celogen Az, metallic aluminium powder etc. for use, preferred aluctyl.
The adding of water reducer is for composition reduces water consumption when stirring into coating, guarantees that coating structure is even, fine and close.Water reducer can adopt lignin semi-annular jade pendant acid calcium or dextrin, semi-annular jade pendant polyesters material.Preferred lignin semi-annular jade pendant acid calcium.
Fiber can play strengthening action in coating.Fiber can be selected glass fibre or alumina silicate fibre or polyester fiber for use.The preferred polyester fiber.
According to the above, the preferred composition of coating composition of the present invention and proportion of composing (percentage by weight) thereof are:
Magnesia 91~95% alumina cements 1~3%
Sodium phosphate trimer 1.5~2.5% clays 1~4%
Aluctyl 0.1~0.4% calcium lignosulfonate 0.2~0.6%
Polyester fiber 0.2~0.3%
The production technology of coating composition of the present invention is: after each acceptable material is pressed the proportion of composing weighing, mix.Earlier magnesia and fiber were mixed in planetary-type mixer 3 minutes, simultaneously with alumina cement and plasticizer, phosphate, anti-cracking agent, water reducer premixed in the bevel-type mixer, then above-mentioned two groups of mixtures were mixed in planetary-type mixer 5 minutes again, the coating compound that gets product carries out weighing, packing.
The advantage of coating of the present invention is to be Main Ingredients and Appearance with magnesia, and impurity content is few, does not pollute molten steel, does not produce public hazards, long service life, and production cost is lower
Be several embodiments of the present invention below.
Example 1. is in A steel mill, with component be: magnesia 91%, alumina cement 3%, clay 4%, sodium phosphate trimer 2%, aluctyl (adding) 0.1%, calcium lignosulfonate (adding) 0.4%, 800 kilograms of coating compositions of polyester fiber (adding) 0.2% are poured into and are added water 21% stirring in the horizontal slurry mixer after 15 minutes, pour in the hopper, hang in 18 tons the tundish, two workmans were put on coating on the permanent liner with the spatula trowel through 10 minutes, slag lining thickness 30mm.Health was baked to 1080 ℃ with coal gas after 3 hours, began to be subjected to steel, and steel grade is 30CrMoSi (A), and continuous casting 10 stoves used 570 minutes altogether, the remaining 13mm of slag lining, and melting loss speed is 0.023 mm/min, removes residual lining and cold steel is easy.The steel grade composition that waters meets the requirements.
Example 2. is in B steel mill tundish job site, with component be: magnesia 93%, alumina cement 2.5%, clay 3%, sodium phosphate trimer 1.5%, aluctyl (adding) 0.25%, wooden calcium sulfonate's (adding) 0.2%, the coating dry mixture of polyester fiber 0.25% drops in the flush coater feed bin, and screw(-type) feeder adds a certain amount of water (hydraulic pressure 3.5Kg/cm in the material feeding blender
2) carry out wet mixing.The slip that is coated with after the wet mixing send down in the pipe pump pressure, delivers to shower nozzle by flexible pipe, and compressed air is delivered to nozzle by the flexible pipe of a separation simultaneously, and workman's pistol head is sprayed at coating on 45 tons the tundish permanent liner, the about 30mm of slag lining coating layer thickness.Natural curing 5 hours 20 minutes, be baked to 1050 ℃ with heavy oil then, be incubated and begin to water steel after 0.5 hour, steel grade is stainless steel 1Cr13, continuous casting 8 stoves, 456 minutes times spent, the remaining 14mm of slag lining coating, melting loss speed 0.035 mm/min, residual lining of coating and cold steel dissolve by itself, and permanent liner does not have sintering, erosion.To refine the stainless steel composition up to standard.
Example 3. is in C steel mill, with component be: magnesia 95%, alumina cement 1.5%, clay 1.0%, sodium phosphate trimer 2.5%, aluctyl (adding) 0.4%, calcium lignosulfonate (adding) 0.6%, the coating composition of polyester fiber (adding) 0.3% adds water 20% for 1.8 tons, after in the reverse-flow mixer of brute force, stirring 10~15 minutes, deliver in 60 tons the tundish 60~100 ℃ of tundish permanent liner surface temperatures, three workmans spread upon whole coating on the permanent liner in 15 minutes, and slag lining thickness is 25~30 millimeters.Natural Health preservation adopts coal gas baking 120 minutes after 6 hours, the coating surface temperature reaches 1100 ℃, is incubated promptly to begin to be subjected to steel after 0.5 hour.Connect and water 9 stoves, last 7 hours 42 minutes, remaining coating breaks away from permanent liner together by cold steel deadweight and cold steel, the permanent liner any surface finish, and no sintering phenomenon, institute's steelmaking kind AP steel constitution is up to standard.