We all know that reducing oxidative loss on the external surface of graphite electrodes is an effective approach to decrease electrode consumption.
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Presently, both domestic and international factories have adopted an anti-oxidation coating process to mitigate the consumption of graphite electrodes. This method involves applying a layer of aluminum and refractory material on the electrode surface through a technique known as alternating spray smelting. The key steps of this process entail initially creating shallow grooves on the exterior surface of the graphite electrode. Subsequently, the electrode is heated to approximately 250°C within a heating furnace. A thin layer of aluminum is sprayed onto the electrode’s surface using a metallic spray gun, followed by applying a refractory slurry onto the outer side of the aluminum layer. Ultimately, the high temperature generated by the electric arc fuses the aluminum and refractory slurry together, forming a conductive and high-temperature oxidation-resistant metal-ceramic layer.
The performance requirements of this anti-oxidation coating are as follows:
Electrical resistivity between 0.07-0.1 Ωm;
Gas impermeability duration exceeding 50 hours at 900°C;
Coating decomposition temperature above °C.
Graphite electrode according to the bearing current density, bending strength, compressive strength, density, resistivity, thermal shock resistance, thermal expansion coefficient and other indicators and uses, divided into ordinary power graphite electrode (RP), impregnated graphite electrode (including antioxidant coated graphite electrode and pitch impregnated electrode), high power graphite electrode (HP) and ultra-high power graphite electrode (UHP) four categories. In principle, various graphite electrodes are configured with ultra-high power graphite electrode nipples of different qualities according to quality indicators.
1.Ordinary power graphite electrode(RP)
The ordinary power graphite electrode is made from ordinary calcined petroleum coke or pitch coke as aggregate,mixed with binder pitch,then under the process of cooled,pressed,baked,graphitized and machined.Compared with high-power and ultra-high-power graphite electrodes,the strength and bulk density of ordinary power graphite electrodes are relatively low,and the current density can be carried is relatively small,which is suitable for calcium carbide,industrial silicon and small current arc furnace.
2.Impregnated graphite electrode(antioxidant coated graphite electrode)
Anti-oxidation coating is a measure used to protect the electrode to reduce oxidation,there are generally two coating processes,one is the"Impregnation"coating,the other is the external coating.Graphite electrode antioxidants are nano-ceramic materials dispersed in aqueous solution,is translucent blue liquid.After the graphite electrode is treated with anti-oxidant YHG-03 negative pressure or pressure impregnation,a layer of high-temperature ceramic protective film is formed on its surface and inside the micropores of the body to effectively isolate the air.It can delay the oxidation rate of electrode and reduce the unit consumption of electrode.It is an effective anti-oxidation impregnating agent for electrode.By introducing graphite electrode anti-oxidation treatment technology,the amount of graphite electrode can be directly saved by about 15%,and it does not bring any negative impact to the production site.
The impregnated graphite electrode is mainly used in the smelting of electric arc furnace steelmaking,yellow phosphorus,etc.
3.High power graphite electrode(HP)
Compared with ordinary graphite electrodes,high-power graphite electrodes in the production process except to adding a part of needle coke to improve the electrode current density,strength,product density,will add one time impregnating and re-baking process,other processes are similar to ordinary graphite electrodes.
High power graphite electrode is mainly used in electric arc furnace steelmaking and chemical industry.
4.Ultra-high Power Graphite Electrode(UHP)
Compared with the high-power graphite electrode,the ultra-high power graphite electrode in the production process will all use needle coke,add a impregnation and re-baking process,the electrode can carry the current density,strength,product density will be greatly improved,other processes are similar to ordinary graphite electrodes.Compared with ordinary and high-power graphite electrodes,because all the use of needle coke,the bending strength of ultra-high power graphite electrodes will be greatly improved,so that it can adapt to large current impact and high performance requirements against thermal shock resistance.
Graphite electrode production process description:
Raw petroleum coke or pitch coke,after calcination at /℃,with calcined petroleum coke or pitch coke as the aggregate,after crushing and screening,grinding,batching,adding to the kneading pan for preheating till meet the technical required temperature(corresponding to the nature of coal pitch),adding heating and melting dehydrated liquid coal pitch for kneading,and then through cooling material,pressing to make green electrodes.Green electrodes are baked under the protection of insulation material(shaped and prevent oxidation),in order to improve the strength and density of the product,if necessary,the baked product can be impregnated and burned two or three times,and then through graphitization,and finally machined into the specified size of the finished graphite electrode(Nipple).
Antioxygen liquid for quenching graphite electrode belongs to the Graphite Electrodes antioxidant, especially for the Graphite Electrodes antioxidant of Electric furnace steel making production.
Graphite Electrodes is a kind of in the graphite material, be used for Electric furnace steel making production, Graphite Electrodes is by continuous consumption in smelting process, according to consumption of electrode mechanism mainly is the consumption of three aspects: the one, and most advanced and sophisticated starting the arc temperature reaches ℃, the high temperature distillation that causes, the 2nd, side and air reaction oxidation consumption, the 3rd, mechanical loss, and lateral oxidation consumption accounts for the 50-70% of wastage in bulk or weight.How to reduce the Graphite Electrodes oxidation consumption, all carried out big quantity research for a long time both at home and abroad, and obtained multinomial achievement in research.These achievements all are the characteristics according to the many pores of graphite material itself, easy oxidation, adopt the way of spraying or dipping to make antioxidant form anti oxidation layer on its surface at electrode surface, stop up pore, minimizing or secluding air contact with electrode, reach anti-oxidant purpose.It is anti-oxidation that these researchs mainly contain spray, high temp glass base oxidation resistant coating, and boron is coating.But these achievements are because complex process, early investment is too high or the restriction of the too high various conditions of production cost and not being widely used.At present at home practical application wider all be adopt the borate hot solution (as Chengdu Rongguang Carbon Co., Ltd.'s research and development, once classified the CTL hot dipping antioxygen liquid of State Torch Program as, its major ingredient contains Tai-Ace S 150, resin and boric acid) dipping anti-oxidant, this technology is because of boric acid (H 3 BO 3 ) solubleness in room temperature water is very little, has only 4--5H 3 BO 3 G/100ml H 2 O is not if room temperature dipping just reaches oxidation resistant effect, so the mode that all will adopt heating is to improve the solubleness of boric acid in water.The time-consuming electricity that takes of this type of heating dipping rises steadily along with electrovalent, and production cost constantly increases.It is .8 that Chinese patent discloses a kind of application number, name is called " dipping type anti-oxidant that improves graphite electrode performance of electric arc steelmaking ", this antioxidant is to suspend multiplely to think that the material that can play antioxygenation is (as silicon-dioxide in binding agent, aluminium sesquioxide etc.), because these materials can not be dissolved in water and the binding agent, can only make them earlier the fine powder of 0.01-1mm, through stirring they are suspended in the solution during use, and then be deposited on the electrode, from the experiment experience analysis, as long as in the antioxygen liquid water is arranged, antioxidant effect can be not fine.At present Japan's distribution-kind of " SANBO-103 " antioxygen liquid for quenching energetically on Chinese market floods Graphite Electrodes at normal temperatures and pressures.But this cooling bath selling price on Chinese market is extremely expensive, and its application and popularization are restricted.
Graphite material mainly is made of polycrystalline graphite, belongs to ceramic, but it has good heat, electrical conductivity and be called as semi-metal, and fusing point and the chemical stability higher than metal are arranged, and the following ℃ of distillations of normal pressure become gas.But it has a very big shortcoming is exactly will oxidation more than 600 ℃ in air.
(3) goal of the invention:
The objective of the invention is to provide a kind of boron system dipping antioxygen liquid that at normal temperatures and pressures Graphite Electrodes is carried out antioxidation treatment at above deficiency, solve the solubility of boric acid under room temperature state, and the infiltration of antioxygen material counter electrode and the problem of adhesion.Its technical scheme is as follows:
It contains the component of following weight part:
Methyl alcohol 80-100, boric acid 10-15, aluminium dihydrogen phosphate 80-100.
Contact us to discuss your requirements of Antioxidant Graphite Electrode. Our experienced sales team can help you identify the options that best suit your needs.
Hot dipping is consistent on antioxidation mechanism with the cold soaking dual mode, but in the selection and proportioning of antioxidant, and how antioxidant is soaked into and the mode that adheres on the electrode body is different.It contrasts as following table:
Cold soaking Hot dipping Prescription Methyl alcohol, boric acid, aluminium dihydrogen phosphate. Boric acid, resin, Tai-Ace S 150, water etc. Antioxidation mechanism Boric acid in the macerate can dewater and generate B 2O 3, B 2O 3Fusing point 723K, boiling point K has good thermostability.B under the high temperature 2O 3Be in liquid state, volatility is less, and 573-K is the vitreum shape, and tack is strong.Electrode from clamper to the bell position, at this moment surface temperature is the B of molten state during steel-making about 773-K 2O 3Clogged the electrode micro-pore, the boronation glass barriers of its generation has been sealed the reactive site of charcoal, and the diffusion of retardance oxygen delays the oxidation of graphite.And more than the bell lower electrode surface temperature K, B in the reducing atmosphere 2O 3Be reduced and generate B 4C, B 4C fusing point height can form with graphite " mesh grid ", and counter electrode end loose peels off, etch can be played certain protective effect, reduces consumption of electrode. Basic identical Dipping mechanism Methyl alcohol is to boric acid solubleness 17.39% under the room temperature, and is bigger 4 times to boric acid solubleness than water, so need not heat, utilizes the wetting property of methyl alcohol again, the boric acid among the dissolving fully immersed in the hole of electrode body, so need not pressurize; Aluminium dihydrogen phosphate is a kind of mineral binder bond, utilizes its cohesiveness, this polyphenoils of boric acid is bonded in the surface and hole of body, does not need solidification treatment to can be used for producing. Necessary heating for dissolving polyphenoils, pressurization is immersed polyphenoils in the hole, also wants long hot setting afterwards. Energy consumption Be used to lift electrode with seldom measuring electricity, do not need electricity consumption in the steeping process. Whole steeping process all needs electricity consumption that steeping fluid is heated, and keeps solution to be in boiling state.
The present invention is diverse to the processing and the prior art of polyphenoils, and the present invention is dissolved in boric acid in the methyl alcohol earlier, adds in the binding agent behind the formation saturated solution again, boric acid fully can be soaked into electrode deep layer and surface.In choice of Solvent methyl alcohol, ethanol, glycerine have been passed through a large amount of experiment screenings: ethanol is inflammable dangerous; Glycerine viscosity is big, usefulness again behind the dilute with water, and antioxidant effect is very poor.Methyl alcohol is big to the solubleness of boric acid, and wetting property is good, and is safe in utilization.
Be the outstanding effect that checking the present invention obtains, the inventor has made following simultaneous test:
Table one: handle sample and the contrast of untreated samples oxidation-resistance for three kinds
Steeping fluid oxidisability mg/g.h
The present invention 66.31
Japan SANBO-103 242.12
CTL hot dipping antioxygen liquid 216.12
Antioxidation treatment 378.21
Table two: cold soaking electrode physical and chemical index contrast of the present invention:
Project Before the dipping Behind the dipping Dipping effect Folding strength Mpa 13.2 15.8 19.7％ Elastic modulus G pa 10.8 11.5 6.48％ Resistivity u Ω .m 6.2 5.8 -6.45％ Volume density g/cm3 1.67 1.71 2.4％
Annotate: oxidisability=W/ (G*H) (W: oxidation weight loss mg; G: weight g before soaking; H: oxidization time h)
Can find out from above correlation data: with Japanese SANBO-103 antioxygen liquid for quenching and CTL hot dipping antioxygen liquid phase ratio, product of the present invention has better antioxidant effect.And the volume density of the electrode after antioxygen liquid is handled, folding strength increase, and resistivity reduces, and this has not only improved the antioxidant property of electrode, but also makes the physicochemical property of electrode obtain further improving, and has improved quality product.
Compared with prior art, the present invention has following advantage:
1, select for use methyl alcohol that boric acid is dissolved, make its solubleness reach 17.39%, make and in the process that Graphite Electrodes is flooded, need not heat, utilize the wetting property of methyl alcohol again, the boric acid among the dissolving is fully immersed in the hole of electrode body, so need not pressurize, at normal temperatures and pressures, Graphite Electrodes is put into the cold soaking pond after tens minutes of filling steeping fluid, electrode is hung out solution, natural airing gets final product.This cold soaking operation is very easy, time saving and energy saving.
2, aluminium dihydrogen phosphate is a kind of mineral binder bond, utilizes its cohesiveness, this polyphenoils of boric acid is bonded in the surface and hole of body, does not need solidification treatment to can be used for producing.
Find out by table 1 that 3, with the CTL hot dipping antioxygen liquid phase ratio of Japanese SANBO-103 antioxygen liquid for quenching and domestic usefulness, product of the present invention has better antioxidant effect.
4, the volume density of the Graphite Electrodes after antioxygen liquid of the present invention is handled, folding strength increase, resistivity reduces, this has not only improved the antioxidant property of Graphite Electrodes, but also makes the physicochemical property of Graphite Electrodes obtain further improving, and has improved the Graphite Electrodes quality.
5, product price of the present invention only has 1/9 of Japanese SANBO-103 antioxygen liquid for quenching.With the CTL hot dipping antioxygen liquid phase ratio of domestic usefulness, cost is suitable, but energy consumption is extremely low, and product energy consumption of the present invention only is 1/400 of a CTL hot dipping antioxygen liquid.The applicant with the Graphite Electrodes of product of the present invention dipping climb Great Wall special steel limited-liability company of steel group on probation after, receive very good effect, the electrode unit consumption has reduced by 15%, has reached desired result fully.
6, raw material that product of the present invention uses is all nontoxic, harmless, and the solution for preparing can be recycled, and need not discharge, and is easy and simple to handle, and no dust, noise do not have any infringement to human body and environment.
We all know that reducing oxidative loss on the external surface of graphite electrodes is an effective approach to decrease electrode consumption.
Presently, both domestic and international factories have adopted an anti-oxidation coating process to mitigate the consumption of graphite electrodes. This method involves applying a layer of aluminum and refractory material on the electrode surface through a technique known as alternating spray smelting. The key steps of this process entail initially creating shallow grooves on the exterior surface of the graphite electrode. Subsequently, the electrode is heated to approximately 250°C within a heating furnace. A thin layer of aluminum is sprayed onto the electrode’s surface using a metallic spray gun, followed by applying a refractory slurry onto the outer side of the aluminum layer. Ultimately, the high temperature generated by the electric arc fuses the aluminum and refractory slurry together, forming a conductive and high-temperature oxidation-resistant metal-ceramic layer.
The performance requirements of this anti-oxidation coating are as follows:
Through testing, it has been established that compared to graphite electrodes of the same quality but lacking anti-oxidation coatings, coated electrodes can reduce net electrode consumption per ton of electric furnace steel by 20% to 30%, and power consumption per ton of steel by approximately 5%. When employing anti-oxidation coated graphite electrodes in electric arc furnace steel plants, modifications to the electrode holder are necessary. The inner diameter of the holder should be suitably enlarged, and a few arc-shaped graphite pads should be embedded to facilitate current conduction through the graphite electrode via the pads. Direct contact between the anti-oxidation coating and the graphite electrode holder can lead to electric sparks on uneven contact surfaces, potentially damaging the holder.
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