US3928022A - Method of producing ferrous metal of constant properties from heterogeneous mixtures - Google Patents

Method of producing ferrous metal of constant properties from heterogeneous mixtures Download PDF

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US3928022A
US3928022A US369841A US36984173A US3928022A US 3928022 A US3928022 A US 3928022A US 369841 A US369841 A US 369841A US 36984173 A US36984173 A US 36984173A US 3928022 A US3928022 A US 3928022A
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compound
liberating
raw materials
halogen
steel
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Henri Langagne
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La Bonvarite
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La Bonvarite
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0025—Adding carbon material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B1/00—Shaft or like vertical or substantially vertical furnaces
    • F27B1/08—Shaft or like vertical or substantially vertical furnaces heated otherwise than by solid fuel mixed with charge

Definitions

  • ABSTRACT A method of producing ferrous alloys, especially cast irons, having predetermined properties and of predetermined quality from heterogeneous raw materials with corrective additives, the quality of the final product being independent of the raw materials used.
  • ozone is continuously added in small amounts as well as a compound for liberating nitrogen, such as hydrogenated nitrogen compounds and organic nitrogenous compounds, and an halogen, such as methyl chloride or chlorobenzene.
  • Liquidus temperature curves are plotted for given temperature and additions of steel, for obtaining the optimum liquidus temperature.
  • the melting is continued as a function of the desired relationship of carbon equivalent, eutectic temperature and amounts of steel, for example, to be added, and tensile strength thereby maintaining the optimum liquidus temperature.
  • the present invention relates to improvements in the selective precision production of ferrous metals, such as cast iron and steel of predetermined properties, by melting heterogeneous raw materials.
  • the method provides inter alia general means which, determined from the operating conditions of a given foundry, may be subsequently used for other foundries.
  • the invention also concerns the cast irons and steel obtained by this method.
  • foundries are required to furnish, as economically as possible, metals having welldefined and constant chemical composition and physical characteristics corresponding to their intended use.
  • metals having welldefined and constant chemical composition and physical characteristics corresponding to their intended use.
  • principal physical properties are very close to the desired properties.
  • cast irons these properties include, inter alia, tensile strength, Brinell hardness as well as the percentage of silicium which contributes to facility of subsequent machining.
  • foundries dispose of very heterogeneous materials such as scrap iron, and steel and iron works rejects, to which there must be added fresh products like new foundry iron or foundry pig in order to render the former materials usable. It is naturally impossible at the beginning to obtain a sufficient chemical analysis of the rejects to be informed, for example, on the carbon and silicium content of the raw materials in order to be able to obtain the desired composition and characteristics.
  • One known method consists in using fresh foundry pig or iron to dilute at least a portion of the impurities of the rejects whose analysis is practically impossible. It is not surprising that for this reason alone the results are uncertain and variable, but this uncertainty and variation are further increased by the type of foundry pig or foundry iron used; indeed, nowadays there is introduced into the blast furnace a percentage of petroleum products, such as fuel oil, as fuel partially replacing the coke. It has been found that pig iron made in part with petroleum products is poorly suited for effecting the aforesaid dilution because endogenetic slag forms during melting and separates during cooling.
  • the empirical corrective charges usually called false charges, do not avoid the formation of endogenetic slag, the cause of numerous rejects, regardless of the value of the carbon equivalent: there has been observed, amongst other things, the fall of the mechanical strength characteristics by the looseness of the grain structure owing to the presence of the impurities or slag, a significant increase in the tendency to form shrinkage cavities or holes and cracks, and excessive porosity.
  • a method furnishing the cupola with very homogeneous high grade pig is also known which enables the reduction of rejects, by introducing into the cupola a certain amount of cetene-forming agent; this operational industrial method is further advantageous by its flexibility in operation, but it does not eliminate the difficulties due to the heterogeneity of the constituents of the mixture treated.
  • the invention provides to utilize the known drawbacks and problems in order to determine, first of all, an optimum liquidus temperature for a desired carbon equivalent and tensile strength and then bring about a change in the melt as a function of this temperature and the results of these corrections which have a nearly immediate effect, thus enabling the manufacture of the end product in a reliable and reproducible manner.
  • the method of the invention for producing cast iron of predetermined quality in starting from heterogeneous raw materials, by melting the said materials with corrective additives of the constituents is characterized in that after charging a furnace, such as a cupola, in a known manner with alternative layers of fuel (coke) and raw materials, it is started up, introduced into the cupola on the one hand small amounts of ozone and on the other hand at least one compound for liberating nitrogen and a halogen at the melting temperature, it is determined for a given temperature and by introducting different amounts of one of the constituents, steel for example, the melting curves corresponding to different liquidus temperatures for a selected range as a function of the eutectic temperature, it is fixed from these curves the amount of steel to be added to any mixture of the available raw materials for a given carbon equivalent CE.
  • a furnace such as a cupola
  • the melting is continued as a function of the desired relationship of carbon equivalent, eutectic temperature, addition of steel, tensile strength so as to directly maintain the optimal temperature, i.e., for elaborating a cast iron of constant quality, independent of the heterogeneous materials employed.
  • the treatment of the impurities which is a selective refining of the raw material not only enables the optimum melting temperature to be subsequently maintained, but also taking into account the foundry standardization according to the invention, permits a meatburization or decarburization of the melt while, if desired, attaining values of carbon equivalent of the eutectic point ranging from 4.20 to 4.60 corresponding to the manufacture of lamellar graphite cast iron and up to a liquidus temperature of 1,300C: it is known that these zones are now considered as the range of malleable cast iron.
  • a compound derived from the distillation of products of plant (vegetable) origin selected from the group of coal, wood and natural resins, is introduced.
  • ammonia hydrazine salts and organic nitro-derivatives in general.
  • Solid hydrazine salts are preferably used in the ladle whereas the other liquid or gaseous compounds are injected into the combustion-supporting air: it has been found that carbides, nitrides or carbonitrides of titanium, zirconium, or aluminium, for example, were neutralized by the nitrogen liberated directly in the metal. Nitrobenzene and hydrazine give very good results in this case.
  • the organic or inorganic products liberating the chlorine which provides satisfaction are slightly chlorinated.
  • the process may be simplified in its whole advantageously be using organic chlorinated solvents capable of dissolving the products of distillation of coals, wood and natural resins.
  • methyl chloride, chlorobenzene and chloronitrobenzene have given total satisfaction.
  • the chloronitrobenzene has the advantage of being able to react during the refining as sole compound. In certain cases it is possible to use an oxyhalogenated compound also liberating oxygen at the melting temperature.
  • the recarburization is preferably carried out most often at the same time as the refining: for this purpose the selection of the compounds is made by taking into account the following observations: the injection of certain compounds coming from the distillation of products of plant origin depending on their origin and physical properties, may bring about the casing of these compounds at the end of the nozzles by coking; however, this problem is avoided when a distillate is selected from the light oil or a heavy oil fraction or even a distillation residue when diluted in an appropriate solvent. Among the solvents yielding good results, the following may be mentioned: cyclohexane, toluol andoxylol.
  • coal tar or wood tar chosen from light, medium or heavy oil fractions, as well as distillation residues or distillates of natural resins such as pine resin or rosins.
  • residues from the manufacture of turpentine also yield good results. All these products are soluable in the above mentioned solvents.
  • the introduction of the recarburizers diluted in a natural gas, (butane or propane) jet or burner has the advantage of reducing the oxydizing power of the gases burned while at the same time increasing the flame temperature of the jet or burner.
  • 2 to 4 liters of a mixture containing 50% coal or wood tar light oil fraction by weight with one of the solvents or refining agents, mentioned above, may be introduced per metric ton of metal.
  • Ozone when controlled, is a compound liberating oxygen at the melting temperature and gives excellent results. With air enriched by 10% ozone it becomes possible to decrease the carbon equivalent to 0.6%.
  • an additive tending to raise the decomposition temperature of ozone to a value close to the melting temperature, in order to avoid a tood rapid decomposition of ozone and thereby obtain a better decarburization, isopropyl oxide and turpentine are possible additives.
  • the oxidation of metalloids, particularly silicium and manganese, remain within reasonable limits, below 15%.
  • Combustion-supporting air is treated by a bank comprising a plurality of ozone generating elements thereby enabling a more or less energetic decarburization. It is found that the carbon equivalent decreases rapidly with air saturated with ozone. Thus, a liquidus temperature which is too low may be raised towards the optimum liquidus temperature.
  • Oxyhalogenated salts such as chlorates, have the advantage of acting as both decarburizer and refining agent as indicated above.
  • cast iron it is designated a ferrous alloy containing carbon in an amount greater than the maximum solubility of this element in iron.
  • the maximum solubility in an iron-carbon binary system is attained at 1147C, the theoretical value is 2.06% which gives the unstable or labile system (white pig iron).
  • the amount of carbon is less when the iron contains substantial amounts of alphagenic elements, silicium especially.
  • the iron then cools according to the stable system; the eutectic temperature is 1 15 3C and the percentage of carbon is no more than 2.03%. Therefore, between the unstable and stable systems the eutectic concentration (carbon saturation) varies between 4.25 and 4.30.
  • the formula giving the carbon equivalent (C.E.) enables the comparison of an iron alloy containing carbon, silicium and phosphorus with an iron-carbon binary system.
  • a cast iron of the same chemical composition viz. 3.47% total carbon, 2.40% silicium and 0.10% phosphorus, it is said depending on the country or the technician that 1% silicium is equivalent to 0.33, 0.25 or 0.22 carbon, i.e., the eutectic concentration or carbon equivalent has values 4.30,
  • the carbon equivalent is calculated as a function of the melting rate expressed in metric tons/hour/sq.decimeter (D of the section of the cupola, and the percentage steel of the metal charges uniformly distributed between 0% and 100% for the useful range of liquidus temperature T (between ll50C and 1300C for lamellar graphite cast irons).
  • T liquidus temperature
  • A is the slope of the melting curves and is equal to:
  • the coefficient A can be determined according to the formula:
  • the carbon equivalent (CE) on the basis of a large number of trials is given by the relationship distance
  • the diagram or graph shown in FIG. 2 is constructed which enables the control of the operation of the cupola in order to obtain a given cast iron.
  • This graph shows for given initial eutectic liquidus temperature, coefficients A, and production as well as the correlations between the melting rate, the percentage steel added (ac%) the liquidus distance, liquidus temperature and carbon equivalent relative to the initial eutectic point.
  • D. is the internal diameter of a cupola expressed in meters and measured at a distance between 20 and 30cm above the tuyeres.
  • the coefficients 4.7 5.6 6.0 6.8 represent the production according to the said coeffients: it is said that a cupola having a diameter of one meter, i.e., 1 X 1 D produces 4.7MT, 5.6MT, 6.0MT, 6.8MT/hour when enough air is provided in order to ensure the production of 4.7 D 5.6 D 6 D 6.8 D
  • the production is controlled by the charging rate of the furnace: the cupola having a diameter of 1 meter operating at 6 D absorbs 10 charges of 600 kg per hour, i.e., a charge every 6 minutes; founders commonly define the cupola by D.
  • the coefficient of production P expressed as D varies in practice between about 4.5 and 6.8 for normal melting and the relationships with the corresponding coefficients A are obtained as follows:
  • 10C liquidus temperature is represented by 10 mm and 10% steel is represented by 20 mm; thus 10 mm along the ordinate gives a change in the coefficient A of 0.1 on the abscissa at
  • 10 mm along the ordinate gives a change in the coefficient A of 0.1 on the abscissa at
  • the origin 0 corresponds to 0% steel on the abscissa and on the ordinate, liquidus temperature which was chosen equal to 1150C, eutectic concentration point which is valued at a carbon equivalent of 4.3.
  • the liquidus temperatures along the ordinate are transformed into distances relative to the origin; by dividing this distance by 100 and multiplying it by the coefficient 0.9, the decreasing values of carbon equivalent are obtained which are to be substracted from the value of the carbon equivalent at the origin which in this example is 4.30.
  • the corresponding CE is:
  • the CE corresponding to the liquidus temperature of 1350 is z 4.30 minus 1.8 2.5.
  • the CE is 4.3; at 1205C, the CE is there fore 4.3 4.95 3.805. Therefore, a coefficient A at the liquidus temperature of 1205C with a charge of 55% steel corresponds to a carbon equivalent for an eutectic carbon equivalent of 4.3.
  • the CE corresponding to a liquidus temperature of 1222C is:
  • the corresponding T.liq. 1 150 170 1320C the CE at a liquidus 1320C will be: 4.3 1.53 2.77.
  • the tensile strength will be calculated for this cast iron assuming the value of the cast iron B (basis cast) has a tensile strength equal to 16 kg/mm for a test piece having a diameter d; 30mm. This value is measured at the eutectic carbon equivalent of 4.3.
  • the tensile strength is expressed by the equation RT ax b.
  • the tensile strength curve RT (FIG. 1 curves) 1' is plotted taking as the origin the values of B (RT of the basic cast iron at the eutectic) 16 kg/mm for the curve CE 4.30 at the eutectic of 1150C and B 20 kg/mm for the curve 11' at the eutectic carbon equivalent of 4.40.
  • B RT of the basic cast iron at the eutectic
  • B 20 kg/mm for the curve 11' at the eutectic carbon equivalent of 4.40.
  • Each drop of 0.10 in carbon equivalent increases the tensile strength 3.16 kg/mm one degree C of the liquidus temperature therefore increases the tensile strength by 0.316 kg/mm FIG. 1 was obtained by a series of carefully effected meltings.
  • the value of B is similarly calculated for an iron cast at the liquidus temperature of 123 3 and manufactured with 55% steel, whereby the cupola operates with a coefficient A 1.5; the test piece has a tensile strength of 42.1 kglmm z calculation of the liquidus distance 1233 1150 value of the tensile strength obtained by the liquidus distance 0.315 kg X 83 26.14 kglmm the value of B at the eutectic is:
  • the carbon equivalent at 1150C goes from 4.30 to 4.40 and then to 4.50; according to this rule, the values of B will increase successively from B 16 to B 18 and then to B 20.
  • the preparatory step which is the refining of the materials therefore enables subsequent melting with complete certainty, a pratically immediate effectiveness of the corrections which corresponds to savings in time and great economy by the consistency of the quality and the substantially total elimination of rejects.
  • the blast air is therefore enriched with ozone (7 to 10%) while also injecting at the tuyeres, for example, a mixture of fluorobenzene, chloronitrobenzene and isopropyl etheroxide. It is found that after a quarter of an hour to a half-hour the liquidus temperature reaches the optimum temperature of 1217C. The production of ozone is then stopped while carrying on the refining. If the liquidus temperature starts to rise, recarburization is brought into play by using, for example, a tar diluted in chlorobenzene and fluorobenzene. The amounts of recarburizer to be injected will be 2 to 4 liters per metric ton of metal in order to avoid coking at the injector.
  • the metal manufactured by this method has astonishing foundry and physical properties.
  • the metal becomes very sensitive to inoculation, 0.05% of an inoculent increases its characteristics by 3 kg/mm with 0.10% it gains 5 kglmm
  • the metal keeps its fluidity in the ladle, even after one hour irrespective of its carbon equivalent.
  • the finely divided graphite gives it excellent friction properties.
  • the perlite is very regular in parallel lamellae.
  • the cementite is in bands narrower than the ferrite in the ratio of l to 2.
  • Examined under an electron microscope the perlite observed in a jet piece having diameter of 30 and 300 practically maintains the same structure. Machining is effected in considerably less time and with considerably less tool wear.
  • the metal is more creep resistant than steel.
  • Flame hardening gives it a Brinell hardness of more than 550; and, the hardened surface is rather insensitive to scaling and shock.
  • the resilience is 0.85 for east irons having a tensile strength of 35 kg/mm it encreases to more than 1.9 for cast irons having a tensile strength of 55-60 kglmm
  • the shear strength is greater by 2 to 3 kg up to a tensile strength 50 kglmm above 50 kglmm the shear strength is the same as the tensile strength.
  • the compressive strength is times the tensile strength.
  • a mm hole drilled at 10 mm from the edge of a 60 mm bar resisted up to a pressure of 1000 bars.
  • the metal was absolutely freontight and vacuum-tight.
  • test piece which was only subjected to recarburization; this test piece was taken just before the refining was begun;
  • a method of producing cast irons having predetermined properties from heterogeneous raw materials by melting said raw materials with corrective additives comprising the steps of charging a furnace with alternate layers of fuel and raw materials, starting the operation of the furnace, continuously introducing ozone into the furnace as well as at least one compound liberating nitrogen and a halogen at the melting temperature of the raw materials, determining melting curves corresponding to different liquidus temperatures for a select range of raw materials as a function of the eutectic temperature by introducing different amounts of one constituent of the raw materials for a given temperature and plotting a diagram thereof, determining from this diagram the amount of said one of the raw materials to be added to any mixture of available raw materials for a given carbon equivalent in view of obtaining the optimum liquidus temperature corresponding to said mixture and the corresponding tensile strength, continuing the melting as a function of the desired relationship of carbon equivalent, eutectic temperature, amounts of said one of the raw materials to be added and tensile strength, thereby directly maintaining the optimum temperature for the desired production.
  • the nitrogen-liberating compound is a member of the group consisting of hydrogenated nitrogen compound, including ammonia and hydrazines, and organic nitrogenous compounds, including nitrobenzene and organic nitrated derivatives.
  • halogen-liberating compound is a solvent of the group consisting of products of distillation of coal, wood and natural resins.
  • halogen-liberating compound is at least one member of the group consisting of methyl chloride, chlorobenzene and fluorobenzene.
  • the natural resins are atleast one member of the group consisting of pine resins and colophanes.
  • a method according to claim 16 further comprising adding a compound for slowing the decomposition of ozone.
  • aid slowing compound is a member of the group consisting of ether oxide and turpentine.
  • oxygenated compound is an oxygenated salt capable of liberating at least one of chlorine and fluorine at the melting temperature.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
US369841A 1972-06-15 1973-06-14 Method of producing ferrous metal of constant properties from heterogeneous mixtures Expired - Lifetime US3928022A (en)

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Cited By (7)

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Publication number Priority date Publication date Assignee Title
US5224985A (en) * 1989-05-20 1993-07-06 La Bonvarite S.A.R.L. Process and apparatus for the melting of metals in the cupola furnace operated without coke
US20050139026A1 (en) * 2003-11-27 2005-06-30 Koyo Seiko Co., Ltd. Rack and pinion steering apparatus and method of manufacturing rack shaft
US7233886B2 (en) * 2001-01-19 2007-06-19 Smartsignal Corporation Adaptive modeling of changed states in predictive condition monitoring
US20080071501A1 (en) * 2006-09-19 2008-03-20 Smartsignal Corporation Kernel-Based Method for Detecting Boiler Tube Leaks
US8239170B2 (en) 2000-03-09 2012-08-07 Smartsignal Corporation Complex signal decomposition and modeling
US8311774B2 (en) 2006-12-15 2012-11-13 Smartsignal Corporation Robust distance measures for on-line monitoring
US10295965B2 (en) 2013-09-06 2019-05-21 GE Intelligent Platforms, Inc Apparatus and method for model adaptation

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5224985A (en) * 1989-05-20 1993-07-06 La Bonvarite S.A.R.L. Process and apparatus for the melting of metals in the cupola furnace operated without coke
US8239170B2 (en) 2000-03-09 2012-08-07 Smartsignal Corporation Complex signal decomposition and modeling
US7233886B2 (en) * 2001-01-19 2007-06-19 Smartsignal Corporation Adaptive modeling of changed states in predictive condition monitoring
US20050139026A1 (en) * 2003-11-27 2005-06-30 Koyo Seiko Co., Ltd. Rack and pinion steering apparatus and method of manufacturing rack shaft
US7631428B2 (en) * 2003-11-27 2009-12-15 Jtekt Corporation Rack and pinion steering apparatus and method of manufacturing rack shaft
US20080071501A1 (en) * 2006-09-19 2008-03-20 Smartsignal Corporation Kernel-Based Method for Detecting Boiler Tube Leaks
US8275577B2 (en) 2006-09-19 2012-09-25 Smartsignal Corporation Kernel-based method for detecting boiler tube leaks
US8311774B2 (en) 2006-12-15 2012-11-13 Smartsignal Corporation Robust distance measures for on-line monitoring
US10295965B2 (en) 2013-09-06 2019-05-21 GE Intelligent Platforms, Inc Apparatus and method for model adaptation

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AT338852B (de) 1977-09-26
ES415921A1 (es) 1976-05-16
GB1440246A (en) 1976-06-23
FR2187919B1 (pt) 1974-10-25
FR2187919A1 (pt) 1974-01-18
DD105629A5 (pt) 1974-05-05
BE801015A (fr) 1973-12-17
DE2329772C3 (pt) 1989-01-12
ATA523673A (de) 1977-01-15
CA993193A (en) 1976-07-20
DE2329772A1 (de) 1974-01-10
DE2329772B2 (de) 1978-01-19

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