126 results about "Pig iron" patented technology

A production method of pig iron using a blast furnace with a tuyere includes: charging a first layer containing an iron ore material and a second layer containing coke alternately in the blast furnace; and reducing and melting the iron ore material in the charged first layer while injecting an auxiliary reductant into the blast furnace by hot air blown from the tuyere, in which: an aggregate for letting through the hot air to a central portion of the blast furnace is blended into the first layer; and the aggregate contains a reduced iron molded product obtained through compression molding of reduced iron.

The invention relates to the technical field of solid waste harmless and recycling equipment, in particular to a gradient temperature pyrolysis-melting vitrification integrated treatment device and process for red mud. According to the device, an electromagnetic heating rotary kiln pyrolysis section and an electrode melting section are directly coupled with a material transfer device through high-temperature atmosphere isolation. The process comprises the following steps: granulating red mud, a reducing agent and a flux, feeding into a rotary kiln of which the temperature is accurately controlled by multiple groups of electromagnetic induction coils in a partitioned manner, and sequentially completing dehydration, selective reduction and iron particle polymerization to produce gt; high-temperature pyrolysis slag at 1000 DEG C; the pyrolysis slag directly falls into an electric melting pool to complete melting and iron-slag liquid phase separation under absolute isolation of reducing atmosphere and oxidizing atmosphere by the device, and pig iron and a stable glass body are respectively obtained. Through the design of'hot slag direct melting 'and'energy closed loop', the problems of high energy consumption and complex flow of the traditional process are solved, and efficient recovery of iron resources in the red mud and thorough harmless and high-valued utilization of the residues are realized.

The invention provides a preparation method of a high-wear-resistance alloy lining plate, and relates to the technical field of wear-resistance alloys, carbon steel and pig iron are mixed, heated and melted, high-carbon ferromanganese, medium-carbon ferrochrome and ferrosilicon are added, heating refining is carried out, aluminum powder is added, the mixture is put into a mold, cooling and demolding are carried out, heating homogenization, quenching and cooling are carried out, and a mother plate is prepared; mixing bismaleimide, the composite powder and sepiolite fibers, heating and stirring, coating a mother board with the mixture, firstly applying negative pressure, then applying positive pressure, heating and cooling to obtain a substrate layer; and placing the mother board in magnetron sputtering equipment, sputtering on the substrate layer to obtain a chromium nitride functional layer, and cooling to obtain the high-wear-resistance alloy lining board. The composite powder is prepared by mixing and heating chromium carbide powder and a hydrogen peroxide solution, filtering, mixing with an ethanol solution and gamma-aminopropyltriethoxysilane, heating, condensing and refluxing, washing and drying, and mixing and heating with amine-terminated polyether and N, N-dimethylformamide. The wear-resistant stability of the alloy lining plate can be improved.

The invention discloses high-strength wear-resistant wind power ductile iron and a processing technology thereof, and belongs to the technical field of casting. The processing technology of the high-strength wear-resistant wind power ductile iron comprises the following steps: A1, sequentially adding waste steel, a carburant, pig iron, foundry returns and ferroniobium into an intermediate frequency furnace, standing after all furnace charges are molten, and removing slag; a2, a spheroidizing agent, a nucleating agent, metal antimony, titanium carbide and a covering agent are sequentially added to the bottom of a steel ladle, and then molten iron in the step A1 is poured into the steel ladle for spheroidizing and inoculation; a3, the molten iron obtained after spheroidizing and inoculation is subjected to slagging-off and then poured into a casting mold, and a stream inoculant is added in the pouring process; a4, after pouring is finished, slowly cooling in the sand mold to below 400 DEG C, and removing a casting from the casting mold; and A5, the casting is subjected to pulse current quenching treatment and then subjected to pulse current normalizing treatment, and the high-strength wear-resistant wind power ductile iron is obtained. The prepared high-strength wear-resistant wind power ductile iron is high in strength and good in wear resistance, and the low-temperature impact performance meets the requirement of QT500-14AL.

The invention relates to a method for measuring and analyzing nickel, silicon and phosphorus in nickel-containing pig iron, in particular to the technical field of detection and analys.The measuring and analyzing method comprises the steps that a nickel-containing pig iron sample is drilled, sampled and separated through a hard alloy drill bit, and a test sample is obtained; sequentially carrying out acid dissolution, solid-liquid separation and constant volume on the obtained test sample to obtain a test solution; measuring the contents of nickel, silicon and phosphorus in the obtained test solution by adopting a full-spectrum direct-reading inductively coupled plasma emission spectrum; a standard curve used in the full-spectrum direct-reading inductively coupled plasma emission spectrum measurement is obtained by dissolving a gradient nickel-containing pig iron standard sample to a constant volume. According to the determination and analysis method provided by the invention, the detection process is designed, so that the nickel, silicon and phosphorus elements in the nickel-containing pig iron with the nickel content of 8-15% can be jointly determined, and a scientific data basis is provided for production management and control.

The regenerated pig iron screening device comprises a grading screening machine box, a pretreatment box and a coarse screening assembly, a feeding mechanism is installed on the top of the side face of the grading screening machine box, and the pretreatment box is placed on the side face, close to the feeding mechanism, of the grading screening machine box and located below the feeding mechanism. The coarse screening assembly is arranged in an inner cavity of the top of the pretreatment box, an inclined guide plate is arranged below the coarse screening assembly, the outer surface of the inclined guide plate and the inner surface of the bottom of the pretreatment box are fixedly installed, a collecting box is fixedly installed on the side face, away from the feeding sleeve and the discharging sleeve, of the pretreatment box, and a vertical spiral feeding machine is fixedly installed on the side face of the collecting box. The raw materials are pretreated through the coarse screening assembly, the feeding granularity range of the raw materials entering the grading screening machine box to be screened is adjusted to a certain degree, the follow-up refining effect and efficiency are improved, and the interference problem of large-particle raw materials on small-particle raw materials is solved.

The invention relates to the technical field of metal product preparation, and discloses a manufacturing process of a high-strength wear-resistant alloy cast iron pan, which comprises the following steps: respectively carrying out magnetic separation impurity removal on a basic raw material and titanium powder, then carrying out vacuum roasting, cooling and discharging to respectively obtain pre-treated pig iron, pre-treated carbon steel and pre-treated titanium powder; preheating an induction furnace, adding the pretreated pig iron, and raising the furnace temperature until the pretreated pig iron is completely molten; then adding the pretreated carbon steel and the reinforced alloy, starting electromagnetic stirring, then adding the pretreated titanium powder, and continuously stirring after adding to obtain a melt; a composite inoculant is added into the melt and stirred, then molten iron is poured into a heat preservation launder for pouring, demolding is conducted after heat preservation, and a pot blank is obtained; the pot bottom and the pot body of the pot blank are subjected to partitioned cooling, then overall cooling and vibration aging treatment are conducted, and then natural cooling is conducted to the room temperature; and after the cooled pan blank is ground and polished, the pan blank is coated with a composite ceramic coating, and the high-strength wear-resistant alloy cast iron pan is obtained.

This invention discloses a method for preparing battery-grade nickel sulfate and iron phosphate using nickel pig iron and ferric phosphate slag as raw materials. The preparation process involves first mixing the ferric phosphate slag with cationic alkyl polyacrylamide to form a uniform mixture. This mixture is then added to dilute acid and stirred to disperse it. Nickel pig iron powder is added, and the mixture is filtered to obtain a leaching solution. The leaching solution is then subjected to nickel-iron separation using resin to obtain an iron-containing solution and a nickel-containing resin. The nickel-containing resin is desorbed to obtain a desorbed solution. A nickel-based pH adjuster is added to this desorbed solution, and the solution is filtered to obtain a nickel sulfate solution. After evaporation and concentration to precipitate crystals, the solution is dried and crushed to obtain battery-grade nickel sulfate. Hydrogen peroxide is added to the iron-containing solution to oxidize ferrous iron to ferric iron. A phosphorus source is added, the pH is adjusted, and the solution is reacted, filtered, and dried to obtain iron phosphate dihydrate. This is then calcined to obtain battery-grade iron phosphate. This invention uses nickel pig iron and ferrophosphate slag as raw materials, and utilizes the ferrophosphate slag to promote the full leaching of iron from nickel pig iron, and nickel pig iron to promote the leaching of phosphate and iron from ferrophosphate. With the addition of cationic alkyl polyacrylamide, it achieves high leaching rates of iron and nickel in a short time, and simultaneously achieves the separation of non-ferrous and nickel metal ions during the acid leaching process, so as to finally obtain high-purity, qualified battery-grade nickel sulfate and ferrophosphate.

The invention discloses a nodular cast iron material with a thick and large section and a preparation method thereof. The nodular cast iron material is mainly prepared from the following raw materials: 35-50% of pig iron, 30-50% of scrap steel and 0-30% of foundry returns. And the carburant accounts for 0.45%-0.9% of the total amount of the pig iron, the scrap steel and the foundry returns. According to the technical scheme, on one hand, the silicon content is increased, and on the other hand, all alloy elements in the molten iron are subjected to specific proportion regulation and control, such as carbon (C), manganese (Mn) and other main elements and magnesium (Mg) auxiliary elements; through the adjustment, the nodular cast iron material with the thick and large section has good basic mechanical properties, the prepared as-cast nodular cast iron with the thick and large section is ferrite nodular cast iron, the tensile strength Rm of the as-cast nodular cast iron is larger than or equal to 650 MPa, the Rp yield strength is larger than or equal to 500 MPa, and the elongation A is larger than or equal to 7%.

Disclosed is a method for producing steel, ferrous alloys or pig iron, and a melting furnace installation, which use ammonia.

The invention belongs to the technical field of ferrous metallurgy, and particularly discloses a smelting method of high-harmful-element sefstromite, which provides a basis for stable smelting of a blast furnace by determining key indexes of raw materials and fuels, integrating that the grade of ore entering a furnace is greater than 55%, the thermal reactivity of coke is less than 45% and the strength after reaction is greater than 48%, and setting a reasonable smelting parameter range. And the characteristics of local high-harmful-element sefstromite can be handled. The problems that the content of harmful elements in local ore is high, ore blending before iron making and production stability are negatively affected, and the pig iron smelting cost is increased are solved. By utilizing the advantage of low cost and matching with a pre-ironmaking sintered ore batching mode and a pellet batching mode, airflow in a blast furnace is stable and reasonable in distribution, a hearth keeps uniform and active, long-period stable and smooth operation of the blast furnace is realized, the ore and coke blending cost is greatly reduced, and the cost of each ton of molten iron is reduced.

The application discloses an oil well pump of high-speed steel containing aluminum and boron and a preparation method thereof, and belongs to the technical field of metal materials. The preparation method comprises the following steps: taking pure iron, micro-carbon chromium iron, tungsten iron, boron iron, pig iron, vanadium iron, titanium iron and aluminum wire as raw materials, and obtaining high-speed steel melt through vacuum induction melting; graphite mold casting is carried out at 1400-1440 DEG C to obtain a cast blank; the cast blank is sequentially subjected to homogenizing annealing, austenitizing, deep undercooling treatment and tempering heat treatment, and finally the product is obtained. The oil well pump comprises the following chemical components in percentage by weight: Al: 1.06%-1.55%, C: 0.11%-0.25%, B: 1.76%-2.47%, and the microstructure is a tempered martensite matrix and (Fe,Cr)2B hard phase. The product has excellent corrosion resistance, wear resistance and service safety, and the cost is lower than that of traditional materials, can effectively resist downhole corrosion and erosion, prolong the service life of the oil well pump, and is suitable for downhole mining scenes in oil fields.

The invention relates to a method for passivating a magnesium material, comprising the step of coating the magnesium material with urea, where the magnesium material is magnesium, a magnesium alloy containing at least 50% by weight of magnesium, or a mixture of magnesium and one or more such magnesium alloys, and where the coating is carried out by mixing the magnesium material with urea particles. The invention further relates to a passivated magnesium material, in particular magnesium in the form of particles of a magnesium material, which are coated with a coating containing urea or consisting of urea, which can be obtained by said method, the invention also relates to the use of the passivated magnesium material for producing pyrotechnic, coated welding electrodes, refractory products, cored wires or desulfurizers for the desulfurization of pig iron and / or steel.

The invention relates to the technical field of ferrous metallurgy, in particular to a method for producing sulfur-containing free-cutting steel by taking molten iron desulfurized slag-off iron as a raw material. The method comprises the following steps: S1, pretreating the drossing iron; s2, preparing raw materials; s3, electric furnace smelting treatment; s4, deoxidation alloying and sulfur content regulation and control; and S5, continuous casting forming. According to the method, molten iron desulfurized drossing iron is used as a main raw material to replace part of common pig iron and scrap steel, high-value cyclic utilization of drossing iron resources is achieved, and the raw material cost is reduced by 15%-20%; by controlling the slag content in the drossing iron and the slag alkalinity in the converter slagging process, the influence of slag charge on molten steel components is avoided, the stability of the sulfur content of the molten steel is improved, and the product percent of pass is improved to 98% or above from 85% or below of a traditional method.

The invention discloses an intermediate frequency furnace lining forming method and a steel mold device, and belongs to the technical field of intermediate frequency furnace linings. The method comprises the following steps: polishing the outer wall of a steel mould device, pasting kraft paper, adding furnace lining sand, ramming and vibrating, adding pig iron, heating a hearth, stopping power supply after heat preservation, cooling by using a fan, chilling and shrinking the steel mould device, taking out the steel mould device by using a crown block, selecting a pipe, adding the pig iron, and tamping in a layered manner, power is supplied to the pipe, the demolding furnace lining is indirectly heated to the sintering temperature and cured, the demolding furnace lining is filled with blast furnace molten iron for furnace baking, the molten iron is discharged after furnace baking is completed, and a formed furnace lining is obtained; the method is suitable for intermediate frequency furnace lining forming, and the purposes that the steel mold demolding operation is simple and rapid, the pollution risk of residues to a furnace lining material is reduced, meanwhile, rapid temperature change is avoided, the cracking probability of a furnace bottom material is reduced, the rework rate is reduced, energy consumption is low, and the furnace building cost is saved can be achieved.

The utility model relates to blast furnace pig iron field, concretely is a kind of blast furnace pulverized coal injection pressure relief system.A kind of blast furnace pulverized coal injection pressure relief system, including injection tank (1) and coal powder bin (2), coal powder bin (2) is located in the side of injection tank (1), still include first pressure relief branch pipe (31), second pressure relief branch pipe (32), bypass pipe (33), main pressure relief pipeline (34), pressure relief cut-off valve (41), regulating valve (42), big pressure relief valve (43), micro pressure relief valve (44), pressure sensor (5) and controller (6), the air inlet of first pressure relief branch pipe (31) is connected the top 1# gas delivery end of injection tank (1), pressure relief cut-off valve (41) and regulating valve (42) are sequentially connected on first pressure relief branch pipe (31), big pressure relief valve (43) is connected in parallel by bypass pipe (33) and regulating valve (42);The air inlet of second pressure relief branch pipe (32) is connected the top 2# gas delivery end of injection tank (1), micro pressure relief valve (44) is connected on second pressure relief branch pipe (32).The utility model is high in efficiency, long in life, protects environment.

The invention relates to a high-aluminum steel smelting and continuous casting process adopting EBT electric arc furnace smelting, LF furnace refining, VD vacuum treatment and CC continuous casting, raw materials comprise pig iron, CrMo steel cuttings, carbon cuttings, high manganese, high chromium, ferromolybdenum, ferrosilicon and aluminum blocks, tapping is carried out after C and P in an electric arc furnace are removed to target values, the aluminum blocks are added into a steel ladle before tapping, the Al content is adjusted in advance, LF furnace deoxidation and alloying treatment are carried out, and the high-aluminum steel is obtained. The temperature is measured after vacuum breaking, sampling is conducted, the weak stirring time is larger than or equal to 15 min after calcium lines are fed, the VD station is switched to the CC station, a water gap of a large ladle is sealed through a long water gap, an overall submersed water gap is adopted for a tundish, molten steel in the tundish is subjected to heat preservation through a carbon-free covering agent and double-layer rice hulls, and an argon blowing stopper rod is adopted for the tundish; annealing treatment is carried out after a continuous casting billet is discharged, the method is suitable for smelting high-aluminum steel through a 60t EBT electric arc furnace, a 60t LF furnace and VOD / VD, and the problem that the Al content is unqualified after VD is solved; ca treatment prevents continuous casting flocculation flow; the molten steel utilization rate is improved through continuous casting production.

The present application relates to the field of blast furnace smelting technology, and proposes a vanadium-titanium magnetite blast furnace smelting method, which comprises: adjusting the burden structure and the ore grade in the blast furnace smelting process to obtain a slag with a mass content of TiO2 of 23.5-24.5%, and produce molten iron and pig iron; controlling the mass content of MgO in the slag to be 7-9%, the mass content of Al2O3 to be 13.5-15%, the slag basicity R2 to be 1.06-1.10 times, and R3 to be 1.38-1.42 times to optimize the fluidity of the slag; controlling the oxygen enrichment rate of the blast furnace to be 4.0-6.0% to make the mass content of Ti(CN) in the slag less than 0.5% and reduce the deterioration of the fluidity of the slag; and controlling the temperature of the molten iron to be 1430-1460 DEG C to make the mass content of titanium in the pig iron be 0.18-0.28% to optimize the separation of slag and iron. The present application realizes that the blast furnace can maintain stable and efficient smelting when the mass content of TiO2 in the slag is 23.5-24.5%.

The invention belongs to the technical field of wind power steel, and particularly relates to an electric furnace smelting process for reducing the sulfur content of wind power steel 18CrNiMo7-6. The production process route comprises the steps of molten iron, scrap steel and nickel-containing pig iron, EAF electric furnace primary smelting, LF external refining, VD vacuum degassing, CC continuous casting, slow cooling (annealing) and inspection and warehousing. According to the electric furnace smelting process for reducing the sulfur content of the wind power steel 18CrNiMo7-6, the core technology is that nickel-containing pig iron is added into an electric furnace to replace electrolytic nickel or nickel plates and other materials with high value, the productivity is improved, and the production cost is reduced; meanwhile, the content of the S element at the end point is effectively controlled, the technological operation of electric furnace blowing is combined, slag overflowing in the VD vacuum process is effectively controlled by optimizing the smelting mode and controlling the proportion and usage amount of waste steel, nickel-containing pig iron and blast furnace molten iron, the product quality is improved, and the market application prospect is wide.

The invention provides a treatment method for reducing the nitrogen content of molten iron, which comprises the following steps: smelting to obtain first molten iron in a blast furnace, and sampling and analyzing the first molten iron to obtain first titanium content and first nitrogen content in the first molten iron; according to the first titanium content and the first nitrogen content, titanium-containing pig iron is added into the iron ladle, then the first molten iron is introduced, second molten iron in the iron ladle is obtained, and the precipitation temperature of titanium nitride in the second molten iron is larger than or equal to 1400 DEG C; and the second molten iron is conveyed to a KR procedure, stirring treatment is conducted to promote titanium nitride to be separated out, and after slagging-off treatment is conducted, standby molten iron is obtained. The titanium-containing pig iron is added to control the precipitation temperature of titanium nitride to be larger than or equal to 1400 DEG C, KR stirring is combined, the nitrogen content of molten iron can be reduced to be smaller than or equal to 0.0050%, a pure molten iron raw material is provided for a smelting converter, and the production cost is reduced.

A method for manufacturing pig iron in an electrical smelting furnace including a vessel, the method including the following successive steps: loading DRI product in the vessel, melting the DRI product to form a pig iron layer topped by a slag layer and, tapping the pig iron into a ladle, and adding a carbon containing material directly in the pig iron in the runner of at least one of the smelting furnace tap holes. It also deals with the manufacturing of steel from the pig iron and the associated electrical smelting furnace.

This invention provides a method for removing copper ash in short-kiln smelting, belonging to the field of non-ferrous metal smelting. The method provided by this invention enriches the copper element in the copper ash into matte as much as possible, thereby maximizing the copper recovery rate. The smelting process of this invention includes three stages: oxidation, reduction, and slag refining. In the oxidation stage, only copper ash is added, without any auxiliary materials; in the reduction stage, the auxiliary materials are pig iron filings and anthracite; in the slag refining stage, no auxiliary materials are added; the oxidation and reduction stages mainly release low-copper and low-lead materials, minimizing lead content in the furnace; the slag refining stage releases high-copper, low-lead matte and low-copper, low-lead tailings. This invention achieves copper enrichment and improves copper recovery rate by adjusting the existing smelting mode and feedstock without using a new smelting furnace, using a smaller amount of auxiliary materials, resulting in better smelting economic benefits.

The invention discloses a crucible-loss-free sintering process for a quartz sand furnace lining of a medium-frequency electric furnace, which relates to the technical field of sintering of furnace linings of medium-frequency electric furnaces and comprises the following steps: polishing the outer surface of a steel mold with upper and lower cone angles, and attaching a layer of demolding medium; the periphery of the steel mold is filled with quartz sand, the quartz sand is rammed to be compact, a furnace lining sand body is formed, and a ballasting module is arranged in an inner cavity of the steel mold; the steel mold is placed in a medium-frequency electric furnace body, first-stage heating is carried out, and the furnace lining sand body is preliminarily cured and formed; heating is stopped, the steel mold is subjected to chilling treatment, the steel mold is shrunk and disengaged, and a preformed furnace lining without a metal inner container is obtained; putting a protective tube with a sealed bottom and pig iron in the protective tube into the mold cavity of the preformed furnace lining, carrying out second-stage heating, and fully mixing blast furnace molten iron into the preformed furnace lining to finish final sintering of the furnace lining; through the modular separated sintering process, crucible loss is avoided, cost is reduced, and quality and efficiency are improved.

The invention belongs to the technical field of ferrous metallurgy, and particularly discloses a deoxidation alloying production method of pig iron for a converter, which comprises the steps of selecting pig iron components and controlling the smelting process of the converter, and specifically comprises the following contents: the selected pig iron components comprise 3.8-4.2% of C, 1.2-1.8% of Si, 0.8-1.2% of Mn, 0.08-0.12% of V, less than or equal to 0.08% of P and less than or equal to 0.03% of S; the final temperature is estimated according to the pig iron adding amount of molten steel components, and the scrap steel adding amount is controlled according to the estimated result. HRB400E is used as a key material for buildings, components are required to be accurately controlled, mechanical properties are stable, anti-seismic indexes reach the standard, and component uniformity optimization, temperature stability and deoxidation inclusion control of molten steel can be achieved through the pig iron deoxidation alloying process; through cooperative regulation and control of the pig iron amount and the scrap steel amount, the converter end point temperature and molten steel components can be stabilized, smelting fluctuation is reduced, and meanwhile reasonable introduction of the V element is beneficial to optimization of the mechanical property of steel and improvement of the product quality stability.

The invention discloses a method for preparing high-purity pig iron based on vanadium-containing molten iron two-step converter smelting, and belongs to the technical field of ferrous metallurgy. The method comprises the following steps: injecting vanadium-containing molten iron with specific components into a converter, and sequentially carrying out first-step blowing vanadium extraction and second-step blowing dephosphorization; in the vanadium extraction stage, the oxygen blowing strength is controlled to be 2.5-3.5 Nm / (min.ton), the final temperature is 1350-1380 DEG C, semisteel with V smaller than or equal to 0.05% is obtained, and vanadium slag with V larger than or equal to 12% is recycled; in the dephosphorization stage, 15-25 kg / ton of a lime-based dephosphorization agent is added, the oxygen blowing strength is controlled to be 1.5-2.5 Nm / (min.ton), the final temperature is 1320-1350 DEG C, and P is smaller than or equal to 0.015%; then the semi-steel is transferred into an LF furnace for deep desulfurization until S is smaller than or equal to 0.015%, and the content of C and Si is adjusted; and finally, the C1 / C2-grade high-purity pig iron meeting GB / T 718-2024 is obtained through casting. The method realizes efficient recovery of vanadium resources and low-cost preparation of high-purity pig iron, and is compact in process, low in energy consumption and suitable for industrial application.

The invention relates to the technical field of repair welding, and discloses a repair process for patching a turbine shell and a pig iron valve shell with nickel plating, tin hanging and lead soldering, which comprises the following steps of: patching and welding, removing shell materials at corresponding positions of the corroded valve shell or turbine shell to form a notch, manufacturing a repair welding plate consistent with the notch in shape by using a plate, and welding the repair welding plate with the shell notch, a hydrostatic test is carried out after welding to ensure no leakage; nickel plating is conducted on the welded and repaired valve shell or turbine shell according to the nickel plating process requirement; tinning is conducted on the inner surface of the valve shell or the turbine shell after nickel plating, pure tin powder is adopted for tinning, the inner surface of the valve shell or the turbine shell is preheated through a flame drying gun, the pure tin powder is placed on the preheated surface of the valve shell or the turbine shell after burning, molten tin powder is arranged on the inner surface of a heating area, and tinning is conducted on all the inner surfaces needing to be repaired in this way; and lead welding: after tin plating is completed, a layer of lead-antimony alloy is welded on the inner surface of the valve shell or the turbine shell subjected to tin plating. The corrosion resistance of the valve casing of the exhaust valve is greatly improved, so that the service life of the valve casing is effectively prolonged.

The invention discloses a cathode non-phosphorus pig iron cold-state assembly production process for aluminum electrolysis. The cathode non-phosphorus pig iron cold-state assembly production process comprises the steps that a first groove is formed in a cathode carbon block; forming a blind hole in the first groove; forming a through hole in the cathode metal bar; the cathode metal bar is subjected to insulation treatment, so that a connecting part and an insulation part are formed on the cathode metal bar, and the current distribution of the cathode assembly is improved; the connecting part of the cathode metal bar is inserted into the first groove in the length direction of the cathode carbon block, and a cavity is formed in the first groove; fixing pieces are adopted to sequentially penetrate through the through holes and the blind holes so as to assemble the cathode carbon block and the cathode metal bar; the telescopic block is arranged in the cavity; and the telescopic blocks in the cavity are fixed by adopting cathode paste to form a cathode group. According to the application, the cathode can be cast without phosphorus pig iron, so that the problems that the contact voltage drop between the cathode carbon block and the cathode metal bar is relatively high and the cathode voltage drop is increased year by year when the phosphorus pig iron is used for casting are avoided, the cathode voltage drop is effectively reduced, and meanwhile, the service life of the cathode is prolonged.

The present application relates to high-purity pig iron manufacturing technology field, especially to a kind of high-purity pig iron casting system and its flow control method, it includes iron runner, hydraulic mechanism, pouring pipeline and conveying mechanism, the hydraulic mechanism is cascaded hydraulic mechanism, the iron runner is connected with the upper end of pouring pipeline by flow guide pipeline, the middle section of pouring pipeline is provided with balance valve, angle sensor is installed on the balance valve, the conveying mechanism is provided with several casting molds, the bottom end of pouring pipeline is guided to any one casting mold.The present application is realized to the flow rate automatic control of molten iron by the cooperation of hydraulic mechanism and balance valve set on pouring pipeline, simple and efficient;In the casting process of high-purity pig iron, both can guarantee the product casting quality of high-purity pig iron, and can guarantee the efficient high-purity pig iron casting operation efficiency;Not only can reduce the investment and maintenance of scale monitoring equipment, but also can reduce the input of manpower, realize the purpose of cost reduction and efficiency increase.

The invention provides a method for reducing and eliminating accumulation at the center of a high-titanium vanadium titano-magnetite blast furnace smelting hearth, which comprises the following steps of: during material distribution, independently adding titanium-free metallized pre-reduced pellets into the center of a blast furnace; the metalized pre-reduced pellets are prepared from the following components in percentage by mass: 75 to 90 percent of TFe, 2 to 4 percent of C, 0.005 percent of P, 0.004 percent of S, 2.5 to 4.5 percent of SiO2, 2.2 to 4 percent of Al2O3, 0.5 to 1.2 percent of MgO, 0.2 to 0.8 percent of CaO and 0.05 to 0.15 percent of Mn. The method provided by the invention not only solves the technical problem of quickly reducing and eliminating the accumulation in the center of the hearth, but also can improve the blast furnace yield and smelting strength and reduce the pig iron cost.