Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B1/00—Preliminary treatment of ores or scrap
  • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
  • C22B1/24—Binding; Briquetting ; Granulating
  • C22B1/242—Binding; Briquetting ; Granulating with binders
  • C22B1/243—Binding; Briquetting ; Granulating with binders inorganic
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B1/00—Preliminary treatment of ores or scrap
  • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
  • C22B1/24—Binding; Briquetting ; Granulating
  • C22B1/242—Binding; Briquetting ; Granulating with binders
  • C22B1/244—Binding; Briquetting ; Granulating with binders organic
  • C22B1/245—Binding; Briquetting ; Granulating with binders organic with carbonaceous material for the production of coked agglomerates

Definitions

• the invention relates to a method for producing alloy blanks in order to provide a molten metal in a melting furnace with at least one alloy component or to increase the portion of the latter in the molten metal, a blank mixture being produced using an alloy element containing the at least one alloy component or being made of the latter, from water and a binding agent, and the blank mixture being processed into an alloy blank that can be placed in the melting furnace. Furthermore, the invention relates to an alloy blank and to use of the latter.
• a further example is the addition of iron materials as an alloy element by means of alloy blanks containing the latter (see DE 44 16 699 A1, DE 297 03 389 U1, DE 1 143 837 B, DE 197 12 042 C1, WO 2005/118892 A1, DE 10 2005 062 036 A1) in iron melts, the addition taking place first and foremost for reasons relating to recycling.
• This can also be combined with the addition of silicon (see EP 1 624 079 A1).
• Such alloy blanks can also be used in vertical chamber reduction furnaces (see DD 139 601 C) or for coolant loading in steel converters (DE 25 01 636 A).
• a blank mixture which contains portions of alloy element, water, binding agent and an additive in the form of a support grain such as e.g. sand.
• This blank mixture is then compacted into the alloy blank, either in a stone compression mould or in a shaker (WO 2005/118892 A1). So that this is possible, the blank mixture must have a ductile or crumbly consistency.
• the water used here is measured such that it is just sufficient to bring about setting of the binding agent and to achieve the required consistency.
• the compression of the blank mixture is a complex working process and requires the presence of a suitable press. With the aid of the press and the setting process the alloy blanks must become so solid that they can be placed as bulk material in a melting furnace and can pass through the melting furnace largely undamaged.
• the grain structure of the blank mixture is essential in order to achieve this solidity. Alloy elements in the form of dust, for example filter dusts or casting house dusts, cause difficulties here. Relatively coarse alloy elements, for example crushed scrap fragments, cuttings or the like are not ideal either. Difficulties with solidity also occur if a carbon carrier is processed as an alloy element.
• the object underlying the invention is to provide a method for producing alloy blanks which is inexpensive and with which alloy blanks can be produced using alloy elements with sufficient solidity, even in dust form or piece form.
• This object is achieved according to the invention in that when producing the blank mixture at least as much water is added so that the blank mixture can be poured, and that at least as much binding agent is added so that the alloy blank produced from the blank mixture has a strength of at least 4 N/mm 2 , preferably at least 5 N/mm 2 , after at the latest seven days setting time at 20° C. and that the blank mixture is poured into a casting mould and setting takes place in the latter without applying any external pressing effect, and finally the alloy blank thus produced is removed from the mould.
• the idea underlying the invention is not to compress the blank mixture, but to produce it by means of casting, a pourable blank mixture initially being produced, and the latter then being poured into a casting mould and being allowed to set, the aforementioned setting time starting when all of the blank mixture has been poured into the casting mould. It has been proved that with this method alloy elements both in dust form and in coarse pieces can be processed to form an alloy blank of sufficient solidity without this requiring the use of a press.
• the method can be implemented inexpensively and can be used for many purposes because it is suitable for alloy elements of a wide variety of types and many different grain sizes to the point of chunkiness.
• Metals even those of which the molten metal is substantially made, in particular iron, but also copper, zinc, chrome, manganese, nickel, molybdenum, titanium or vanadium, can be considered as an alloy element.
• the iron can also be in the form of iron alloys such as FeSi, FeMn, FeCr, FeNi, FeMo, FeTi or FeV.
• Metal oxides and ores, such as FeO, Fe 2 O 3 , MnO are also suitable.
• the alloying agent can also be a metallic silicon, for example in the form of SiC.
• the method according to the invention is however also suitable for the processing of carbon carriers and/or uncombined carbon as an alloy element, for example graphite, coke breeze, petrol coke, pitch coke, compact dust etc. They can be used for the carburisation of the molten metal.
• the alloy element can also be a mixture of at least two of the aforementioned alloy components or alloy elements.
• the lower limit for the added water is determined by the property of the pourability of the blank mixture.
• cement is used for this purpose.
• the latter is to be understood as the property whereby a level surface is established on the open side of the blank mixture poured into the casting mould, without any further measures, such as for example shaking or levelling off.
• the solidity of the alloy blank with the same binding agent portion becomes less the higher the portion of water, i.e. it is a compromise between seeking good pourability of the blank mixture on the one hand and the ultimate solidity of the alloy blank on the other hand.
• a fluxing agent as is normally used when producing concrete, for example lignin sulfonate, melamine formaldehyde sulfonate, naphthalene formaldehyde sulfonate, polycarboxylates or hydroxycarboxylic acids and salts of the latter (see standard EN 934-2).
• the portion of the fluxing agent should come within the range of 0.01 to 0.5% by weight in relation to the weight of the blank mixture.
• Good processability is produced when as much water and optionally fluxing agent is added to the blank mixture so that the blank mixture has a spread value (measured according to standard DIN EN 459-2, but without stroke thrusts) of at least 15 cm, preferably 19 cm, and advantageously no more than 21 cm.
• a spread value measured according to standard DIN EN 459-2, but without stroke thrusts
• values of 15 to 18 cm spread value shaking of the blank mixture in the casting mould is recommended for the purpose of preventing cavities between the casting mould and the blank mixture as well as shrinkage holes in the alloy blank.
• the weight ratio of water to solid in the blank mixture should not exceed a value of 0.8.
• the binding agents generally used for building materials in particular hydraulic binding agents such as cement, can be considered as binding agents. Since the binding agent for the use of the alloy blank provided according to the invention constitutes a foreign material, the portion of the binding agent should not be very much higher than required in order to achieve the solidity provided according to the invention. It is therefore advantageous if the highest value cement possible is used because then the binding agent portion can be kept low. There is then a connection with the quantity of water added for the purpose of achieving pourability such that the quantity of binding agent must be higher the higher the water content. In order to achieve rapid setting one can also add to the cement a setting accelerator which accelerates the setting and hardening process. The addition of binding agent should not exceed 40% by weight in relation to the whole blank mixture, better it should however be no higher than 20% by weight, always with the proviso, however, that the aforementioned minimum solidity is achieved.
• a support grain is added to the blank mixture. It should have a grain size of maximum 1.5 cm. Preferably sand should be used, and the support grain should advantageously be present with a weight portion of 5 to 40% in relation to the whole blank mixture.
• the invention makes provision such that the blank mixture in the casting mould is shaken and/or the open surface of the latter is smoothed. Shaking is particularly recommended if the water content and optionally the fluxing agent content is so small the there is a risk of shrinkage holes forming or the casting mould not being completely filled.
• the surface should preferably be sprayed with water immediately after the casting process.
• the surface can be provided with a covering impermeable to moisture or dispensing moisture.
• the method according to the invention is suitable both for the use of an alloy element present in small piece form, preferably with an average extension of 0.5 to 5 cm, but also for an alloy element which is added in dust or powder form, in particular with a grain size of below 0.1 mm. Both forms of alloy element can be combined with one another here, preferably in a weight ratio of 20:80 to 80:20.
• casting moulds can be used the internal volume of which corresponds to the predetermined shape of the alloy blank.
• a tub-shaped large mould can also be used, the interior of which is sub-divided into individual moulds, the large mould being filled with the blank mixture in a single casting process.
• the interior of the large mould can be sub-divided into the individual moulds by bars reaching up from its base. It is then possible to fill the individual moulds with the blank mixture so that the alloy blanks thus produced are separated from one another.
• the large mould can also however be filled to such a height that the open surface of the blank mixture lies above the bars, and so a one-piece structure in the form of a large blank similar to a (turned over) block of chocolate is produced. After removal from the mould this large blank is then broken in a breaker into individual pieces which form the alloy blanks. Breaking can also be implemented here by breaking the bars between the individual blanks so that the individual blanks thus formed form irregularly moulded blank pieces.
• the subject matter of the invention is also an alloy blank which can be obtained with the aid of the method described above, and to the use of this alloy blank by placing into a metal melting furnace when melting metal, preferably in a cupola furnace, converter, blast furnace or induction furnace.
• alloy blanks for example, were produced by the method according to the invention.
• EMC80 is to be understood as a SiC raw material which contains 80% pure SiC, the remainder being non-reacted free C and SiO 2 .
• the special agent 1 specified in Example 3 is the binding agent marketed by HeidelbergCement Bauscher für Geotechnik GmbH & Co. KG under the name “CEM-ROCK 489”, whereas the special agent 2 specified in Example 4 is also marketed by Heidelberg Zement Bauscher fur Geotechnik GmbH & Co. KG under the name “CEM-ROCK MFG”.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Geochemistry & Mineralogy (AREA)
• Geology (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Mold Materials And Core Materials (AREA)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)

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• 2010
  • 2010-07-08 DE DE102010031101A patent/DE102010031101A1/de not_active Ceased
• 2011
  • 2011-06-07 EP EP20110168903 patent/EP2405025B1/de active Active
  • 2011-07-08 US US13/178,727 patent/US20120167715A1/en not_active Abandoned

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