A kind of smelting special slag former containing active element steel and preparation method thereof
Technical field
The invention belongs to smelting slag making materials technical field, provide a kind of medium-frequency induction furnace that is applicable to adopt non-oxidizing process to smelt the special slag former containing the active element steel such as titanium, boron, zirconium and rare earth especially.
Background technology
Often containing active element such as one or more titaniums, boron, zirconium and rare earths in modern steel material, these active element mainly play crystal grain thinning, stop grain growth, increase the effects such as hardening capacity in steel.But these active element are very easy oxidization burning loss in the smelting process of steel, not only reduces the recovery rate of these elements, and be difficult to the accurate control realizing chemical composition.
The oxidizing reaction of active element is nearly all carried out at slag-molten steel interface, namely the oxidization burning loss of active element and slag component and character closely related.At present, in smelting iron and steel, the main ingredient of slag is FeO, CaO and SiO
2, usually adopt lime (CaO), fluorite (CaF
2) etc. slag making materials, under this slag system condition, the recovery rate of active element is usually lower.The character of slag mainly comprises the character such as basicity, viscosity and oxidation capacity, and wherein, the oxidation capacity of slag determines the oxidization burning loss degree of active element, and slag oxidation capacity is stronger, and in molten steel, active element oxidization burning loss is more.
The oxidation capacity of slag depends primarily on the activity a of FeO in slag
feO, a
feOlarger, the oxidation capacity of slag is stronger, and the active element in molten steel is more oxidized.In fact, when medium-frequency induction furnace adopts non-oxidizing process steel-making, the FeO in slag can regard the conveying medium of oxygen as: when the oxygen in air enters slag, the FeO in slag is oxidized, forms high oxide Fe
2o
3; At slag-molten steel interface, Fe
2o
3reduced by active element, again form FeO; Visible, the oxygen in air is exactly reacted by the oxidation-reduction of FeO, enters into molten steel continuously, causes the oxidization burning loss of active element, and recovery rate reduces.
Summary of the invention
The object of the invention is the recovery rate in order to improve active element in smelting steel process, accurately controlling the chemical composition containing active element steel such as titanium, boron, zirconium and rare earths, a kind of special slag former can protecting active element is provided.
The present invention specifically provides a kind of special slag former smelted containing active element steel, and it is characterized in that, the composition proportion of described slag former is mass percent:
CaO:50~70%
CaF
2:5~15%
MgO:5~15%
B
2O
3:3~5%
Al:5~15%
TiO
2:5~10%
All the other are inevitable impurity.
Present invention also offers the preparation method of described slag former, it is characterized in that: with conventional Wingdale, fluorite, magnesia, borax, aluminium bits and rutile for raw material, hand-crushed, maximum particle size is no more than 25mm, mix drying (adopting con-ventional drying equipment), make slag former meet following masses per-cent:
CaO:60~65%
CaF
2:6~10%
MgO:9~13%
B
2O
3:3~5%
Al:7~12%
TiO
2:7~10%
All the other are inevitable impurity.
When the steel that medium-frequency induction furnace adopts non-oxidizing process to smelt containing active element such as titanium, boron, zirconium and rare earths, slag former of the present invention is compared with conventional slag former, its viscosity is slightly high, at more than 0.1Pas when 1600 DEG C, effectively can weaken the diffusion of FeO in slag blanket inside and transmission, reduce the activity a of FeO
feO, thus reduce molten steel air-breathing, reduce the oxidation capacity of slag, play the effect of the oxidization burning loss reducing active element, improve recovery rate.
Embodiment
Raw material of the present invention adopts Wingdale, fluorite, magnesia, borax, aluminium bits and rutile.
Embodiment
Wingdale, fluorite and rutile are carried out hand breaking, and maximum particle size is no more than 25mm, considers to be worth doing mix with magnesia, borax and aluminium, makes slag material meet mass percent shown in table 1.Gained slag material is sent in conventional heating roasting plant and carries out drying, drying temperature 200 DEG C, 4 hours time of drying.Slag former is used for the low alloy steel containing active element 1.0%Ti, the recovery rate of active element Ti is in table 1.
The recovery rate of table 1 slag former Ingredient percent and active element Ti
Above-described embodiment, only for technical conceive of the present invention and feature are described, its object is to person skilled in the art can be understood content of the present invention and implement according to this, can not limit the scope of the invention with this.All equivalences done according to spirit of the present invention change or modify, and all should be encompassed within protection scope of the present invention.