EP0004922B1 - Koks der bei der Herstellung von grauem Gusseisen verwendbar ist; Verfahren zur Herstellung von diesem Koks und Verfahren zur Herstellung von grauem Gusseisen unter Verwendung dieses Koks - Google Patents

Koks der bei der Herstellung von grauem Gusseisen verwendbar ist; Verfahren zur Herstellung von diesem Koks und Verfahren zur Herstellung von grauem Gusseisen unter Verwendung dieses Koks Download PDF

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Publication number
EP0004922B1
EP0004922B1 EP19790101071 EP79101071A EP0004922B1 EP 0004922 B1 EP0004922 B1 EP 0004922B1 EP 19790101071 EP19790101071 EP 19790101071 EP 79101071 A EP79101071 A EP 79101071A EP 0004922 B1 EP0004922 B1 EP 0004922B1
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EP
European Patent Office
Prior art keywords
coke
coal
silicon carbide
iron
coals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19790101071
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English (en)
French (fr)
Other versions
EP0004922A1 (de
Inventor
Edward Daniel Burton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SGL Carbon Corp
Original Assignee
Great Lakes Carbon Corp
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Filing date
Publication date
Application filed by Great Lakes Carbon Corp filed Critical Great Lakes Carbon Corp
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Classifications

    • 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
    • C21C1/08—Manufacture of cast-iron
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
    • C10B57/04—Other carbonising or coking processes; Features of destructive distillation processes in general using charges of special composition
    • C10B57/06—Other carbonising or coking processes; Features of destructive distillation processes in general using charges of special composition containing additives

Definitions

  • Gray cast iron is distinguished by a relatively high amount of carbon, approximately 3%, which imparts to it the characteristic hardness, castability, wear resistance, and machinability displayed by no other metal.
  • Gray cast iron is unique in its high content of carbon, and in the form of a large portion of this carbon as a separate phase of graphite.
  • the strength, wear resistance, brittleness or conversely toughness, and machinability are all controlled to a large and primary extent by the graphitic carbon content.
  • Graphite in gray iron appears in several forms well-known to the foundry metallurgist, of which the so-called type A, a flake, is preferred, in a pearlitic iron matrix. If the carbon is present as iron carbide, or cementite, the metal will be what is known as white iron, hard, brittle, and unmachinable. If the carbon is present in the correct proportion as graphite in the pearlitic matrix, it will display the characteristic gray color and good machinability of gray iron.
  • gray iron When gray iron is melted in a cupola over a bed of hot coke, it gains some carbon content from the coke, which may be varied by adjusting the coke-iron ratio, the air blast, by additives such as silicon, and by the slag chemistry.
  • the metal will have low tensile strength and be too soft to be commercially useful.
  • the amount and shape, size, and distribution of graphite present in a gray cast iron are usually controlled by the addition of an inoculant to the metal in the cupola, the ladle, or the mold which furnishes seeds for formation of crystals of graphite.
  • Inoculants commonly used are silicon in various forms, such as ferrosilicon or silicon carbide, and graphite itself.
  • Other metals used include chromium, manganese, calcium, titanium, zirconium, aluminium, barium and strontium.
  • Some of the elements function as alloying elements as well, in particular molybdenum, chromium, and manganese.
  • Aluminum and the alkaline earths are the most effective non-graphitic inoculants.
  • Silicon is the principal element used as an inoculant, controlling graphite formation, allowing the formation of the pearlitic iron matrix over a wider temperature range, and thus decreasing the chill depth of the cast metal.
  • the chill depth test is usually conducted by casting a graduated wedge-shaped test piece under specific conditions, and measuring the extent of the white iron from the tip of the wedge. Since the thinner portion cools faster, the tip will be of white iron or iron carbide, which will crystallize earliest, and is light colored, hard, brittle and unmachinable in normal operation.
  • the extent of the chill depth controls principally the thickness of the casting which can be made from a particular melt, a melt with a low chill depth enabling a relatively thinner casting to be poured without the formation of white iron.
  • a thick cross-sectioned casting is made with iron with a greater chill depth to avoid the formation of excess graphite and ferrite.
  • the desired metal consists of graphite flakes in a matrix of pearlitic iron, which is stabilized over a widely varying cooling rate.
  • German Patent DE - C - 714099 discloses the addition of up to 0.2% by weight of silicon carbide to coal during the coking process.
  • a coke suitable for use as fuel in a foundry cupola to produce gray iron characterized by the fact that it contains in its structure from 0.5 to 2.5% by weight of silicon carbide which is blended with the coal or blend of coals used to produce said coke prior to coking said coal or blend of coals, said silicon carbide content being based on the amount of coal or blended coals.
  • the invention also provides a method of producing an improved grade of coke particularly suitable for use as fuel and which acts as a deoxidizer and inoculant in a gray iron foundry cupola, in which coal or a blend of coals is coked in a by-product coke oven, characterized by mixing with the coal or blend of coals prior to coking from 0.5 to 2.5% by weight of carbide based on the amount of coal or blended coals.
  • the invention further provides a method of producing gray iron for castings in a cupola in which the improved coke of the invention is used as a fuel.
  • the silicon carbide used in the practice of this invention is preferably a conventional silicon carbide which is a by-product of the Acheson graphite process.
  • baked carbon electrodes are packed with resistor coke and then covered with a coke-silica mixture and electrically heated to transform the amorphous carbon to crystalline graphite, some of the silica reacts with carbon forming silicon carbide according to the following equation:
  • the commercial grade preferably used in this invention contains approximately 50% to 60% by weight graphite and 20-25% by weight silicon carbide with the remainder a mixture of silicon dioxide and other metallic oxides.
  • an effective amount of the composition consisting principally of graphite and silicon carbide is added to the blend of coals used in making foundry coke.
  • the addition is from 0.2 to 2.5% by weight silicon and preferably from 0.5 to 6% by weight graphite based on the amount of coal or blend of coals.
  • the mix is pulverized and coked in a by-product coke oven (see: Making Efficient Use of Coke in the Cupola, American Coke and Coal Chemicals Institute, Washington D.C.).
  • the resulting coke has superior physical and chemical properties. Its superior hot strength gives improved operation in the cupola; aids in maintaining the physical integrity of the coke in the cupola, avoiding breakdown into smaller particles and consequent plugging which increases the back pressure of the air draft necessary to maintain smooth operation of the cupola. This in turn contributes to operation with less fuel and consequent savings.
  • the silicon carbide decomposes in the hot metal, releasing exothermic heat and lowering the overall coke combustion.
  • the silicon carbide When the silicon carbide is blended into the coal mix, preferably in combination with graphite powder, and consequently pulverized and coked, it is dispersed much more uniformly and homogeneously within the coke particles and is more uniformly and readily available to the liquid iron at the coke-iron interface. This availability aids in promoting the reactions of decomposition of the silicon carbide and its reactions with the iron.
  • the availability of the silicon carbide in the coke also aids in simplifying the operation of the cupola in lessening the need for additional inoculants, reducing labor needed and the possibility of weighing and adding errors.
  • the graphite, and silicon from the silicon carbide act as inoculants for deposition of graphite in the desired pearlitic matrix on cooling and hardening of the metal when cast, thus controlling the grain structure, hardness, strength and machinability of the cast metal, enabling the founder to produce thinner cross-section castings economically and profitably.
  • the coke produced in the above fashion is then used as a replacement for the regular metallurgical coke in a gray iron foundry cupola.
  • the silicon carbide used had the following approximate analysis:
  • Example 2 Ten carloads of coke were made as in Example 1 with 5% of the same type silicon carbide in the blend.
  • the coke produced had a composite analysis as follows:
  • the iron produced with the coke containing SiC had the following analysis as compared to iron produced with regular coke:
  • Silicon melting loss or oxidation loss was reduced 18.9%. Silicon pickup in the iron was 0.07%.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Manufacturing & Machinery (AREA)
  • Metallurgy (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Coke Industry (AREA)

Claims (6)

1. Koks, der geeignet ist für die Verwendung als Brennstoff zur Erzeugung von grauem Gußeisen in einem Kupolofen, dadurch gekennzeichnet, daß er in seinem Gefüge 0,5 bis 2,5 Gew.% Siliciumcarbid enthält, das der Kohle oder dem Kohlegemisch, die bzw. das zum Erzeugen des Kokses verwendet wurde, vor dem Verkoken der Kohle oder des Kohlegemisches beigemischt wurde, wobei der angegebene Silicium-carbidgehalt auf die Menge der Kohle oder des Kohlegemisches bezogen ist.
2. Koks nach Anspruch 1, dadurch gekennzeichnet, daß er auf die Menge der Kohle oder des Kohlegemisches bezogen 0,5 bis 6,0 Gew.% Graphit enthält.
3. Koks nach Anspruch 2, dadurch gekennzeichet, daß der Kohle oder dem Kohlegemisch vor dem Verkoken Siliciumcarbid in Handelsqualität beigemischt wurde, das bei der Erzeugung von Graphit nach dem Achesonverfahren als Nebenprodukt angefallen ist und etwa 20 bis 25 Gew.% Siliciumcarbid und 50 bis 60 Gew.% Graphit enthält.
4. Verfahren zum Erzeugen eines Kokses von höherer Qualität, der besonders als Brennstoff geeignet ist und der in einem Kupolofen zur Erzeugung von grauem Gußeisen als Desoxidationsmittel und Impfstoff wirkt, wobei Kohle oder ein Kohlegemisch in einem Nebenprodukt-Koksofen verkokt wird, dadurch gekennzeichnet, daß der Kohle oder dem Kohlegemisch vor dem Verkoken 0,5 bis 2,5 Gew.% Carbid, auf die Menge der Kohle oder des Kohlegemisches bezogen, beigemischt wird.
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß Siliciumcarbid in Handelsqualität beigemischt wird, das 20 bis 25 Gew.% Siliciumcarbid und 50 bis 60 Gew.% Graphit enthält.
6. Verfahren zum Erzeugen von Graugußeisen in einem Kupolofen, dadurch gekennzeichnet, daß als Brennstoff ein Koks nach einem der Ansprüche 1 bis 3 verwendet wird.
EP19790101071 1978-04-14 1979-04-09 Koks der bei der Herstellung von grauem Gusseisen verwendbar ist; Verfahren zur Herstellung von diesem Koks und Verfahren zur Herstellung von grauem Gusseisen unter Verwendung dieses Koks Expired EP0004922B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US89657978A 1978-04-14 1978-04-14
US896579 1992-06-10

Publications (2)

Publication Number Publication Date
EP0004922A1 EP0004922A1 (de) 1979-10-31
EP0004922B1 true EP0004922B1 (de) 1981-07-15

Family

ID=25406441

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19790101071 Expired EP0004922B1 (de) 1978-04-14 1979-04-09 Koks der bei der Herstellung von grauem Gusseisen verwendbar ist; Verfahren zur Herstellung von diesem Koks und Verfahren zur Herstellung von grauem Gusseisen unter Verwendung dieses Koks

Country Status (3)

Country Link
EP (1) EP0004922B1 (de)
JP (1) JPS5513776A (de)
DE (1) DE2960478D1 (de)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101768457B (zh) * 2010-01-28 2013-03-13 鞍钢股份有限公司 非煤系复合添加剂及其在炼焦中的应用
CN101768458B (zh) * 2010-01-28 2013-03-13 鞍钢股份有限公司 一种焦炭性能改善剂及配煤炼焦方法
US10767238B2 (en) * 2016-04-15 2020-09-08 Elkem Asa Gray cast iron inoculant
CN109988590B (zh) * 2017-12-29 2021-04-27 新疆八一钢铁股份有限公司 一种大型高炉使用低热态强度焦炭的冶炼方法
CN110951939B (zh) * 2019-11-25 2021-08-10 凌幸福 硅质发热剂

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE714099C (de) * 1933-03-17 1941-11-25 Kurt Baum Dr Ing Verfahren zur Beeinflussung des Schmelzvorganges von Brennstoffaschen
US2119521A (en) * 1935-10-10 1938-06-07 Carborundum Co Cast iron and the manufacture thereof
US2527829A (en) * 1948-11-12 1950-10-31 Electro Refractories & Alloys Foundry additives
GB980214A (en) * 1962-12-03 1965-01-13 Foseco Int Cupola additive

Also Published As

Publication number Publication date
DE2960478D1 (en) 1981-10-22
EP0004922A1 (de) 1979-10-31
JPS5513776A (en) 1980-01-30

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