Electrochemical refining device and method for preparing ultrapure steel

Electrochemical refining device and method for preparing ultrapure steel

  • CN 110,408,742 B
  • Filed: 08/30/2019
  • Issued: 10/01/2021
  • Est. Priority Date: 08/30/2019
  • Status: Active Grant
First Claim
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1. An electrochemical refining method for preparing ultra-pure steel is characterized in that,the refining method adopts the following electrochemical refining device:

  • the electrochemical refining device comprises a steel ladle, wherein molten steel is arranged in the steel ladle, an argon gas permeable brick communicated with the molten steel is arranged at the bottom of the steel ladle, refined synthetic slag is arranged on the molten steel, two anode electrodes are arranged in the refined synthetic slag, a cathode electrode is arranged on the refined synthetic slag, and an anode signal electrode connected with the molten steel is arranged on one side of the steel ladle;

    the two anode electrodes, the anode signal electrode and the power supply form an anode position feedback electrode device with two anodes spaced from the liquid level of the molten steel;

    wherein, the cathode electrode is arranged 200mm above the interface of the steel slag;

    the anode signal electrode is inserted in a refractory brick gap where molten steel can reach below 300mm on the upper edge of the steel ladle and is welded on the steel ladle shell;

    the thickness of the refining synthetic slag is 250-300mm, and the distance between the bottom ends of the two anode electrodes and the interface of the refining synthetic slag is 100 mm;

    the refining method comprises the following steps;

    s1, selecting the power supply capacity of the direct current power supply according to the tonnage of the ladle;

    selecting a power supply according to the temperature rising speed of 5 ℃

    /min after the refined liquid steel and the temperature of the liquid steel in the steel ladle are basically stable and cannot be rapidly cooled, namely the heated liquid steel reaches the lowest temperature, wherein when the tonnage of the steel ladle is 50t, 60t, 90t and 150t, the power supply capacity is 10000kVA, 12000kVA, 15000kVA and 25000kVA respectively;

    s2, when the primary smelting furnace discharges steel to a ladle of the refining device, the slag of the primary smelting furnace needs to be reduced to enter the refining furnace, and 50% of refined synthetic slag is added to the bottom of the ladle when the steel is discharged;

    s3, argon blowing and stirring;

    s2, positioning the steel ladle filled with the molten steel at a refining station, starting argon blowing by the steel ladle to stir the molten steel, controlling the stirring strength to be 150L per ton of steel except for adding alloy, adding slag charge and feeding aluminum wires for strong stirring, and determining the argon blowing stirring strength through visual inspection due to the difference of air permeability of air permeable bricks, wherein the whole electrochemical refining process is accompanied with argon blowing stirring;

    s4, adding refined synthetic slag;

    blowing argon gas for strong stirring, supplementing refined synthetic slag, and ensuring the thickness of a slag layer to be 250-300 mm;

    when the electrode position is unstable, the thickness of a slag layer is increased;

    s5, feeding an aluminum wire, and adding aluminum to the slag surface;

    s4, after adding the refined synthetic slag, feeding 0.4kg of aluminum wire calculated according to ton steel into the molten steel, adding 10-20mm of aluminum particles into the slag surface according to 0.3kg of aluminum per ton steel, and supplementing the aluminum particles according to the condition of white slag to maintain white slag operation;

    s6, positioning of two anode electrodes;

    putting two anode electrodes into the steel slag, determining a zero position contacting with a steel slag interface according to a short-circuit signal of an anode signal electrode in an electrode device for electrochemical refining, lifting the two anode electrodes upwards by 100mm, fixing the positions of the two anode electrodes, and respectively positioning the two anode electrodes;

    s7, cathode electrode power transmission and arc striking;

    the cathode electrode is powered and falls to reach a given arc striking voltage which is about 200mm away from the steel slag interface, the arc is started, and the preset cathode working voltage is divided into two stages of 200V and 220V;

    s8, electrochemical metallurgical deoxidation and desulfurization;

    under the condition of given direct current constant and stable voltage, heating the molten steel by arc striking of a cathode electrode, wherein the temperature of the molten steel is 1550-;

    in the heating process, in order to keep white slag, silicon carbide or aluminum particles are properly scattered twice to the slag surface, and the reducing atmosphere of the slag surface is maintained;

    so that the alkaline calcium-containing oxide in the steel slag is ionized into Ca2+And O2-O, S from steel is ionized into O under the action of electric field2-And S2-And enters the slag under the driving of an electric field;

    ionized Al in steel slag3+And O in steel2-Al is formed by reaction near the anode electrode2O3S in steel2-With Ca in the steel slag2+CaS is generated by reaction near the anode electrode;

    Al2O3and CaS enter the steel slag, thus completing the electrochemical deoxidation and desulfurization process;

    the sulfur content in the steel is reduced to be below 20ppm in the whole refining time of 40-60 minutes by electrochemical metallurgy deoxidation and desulfurization, and the total oxygen content in the steel is reduced to be below 12ppm, so that ultra-pure molten steel is obtained;

    and S9, sending the ultra-pure molten steel obtained in the S8 to a continuous casting machine to cast a square billet, a slab blank or a rectangular billet.

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