US3174846A - Method of briquetting iron oxide fines - Google Patents

Method of briquetting iron oxide fines Download PDF

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Publication number
US3174846A
US3174846A US271938A US27193863A US3174846A US 3174846 A US3174846 A US 3174846A US 271938 A US271938 A US 271938A US 27193863 A US27193863 A US 27193863A US 3174846 A US3174846 A US 3174846A
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fines
coal
iron oxide
temperature
particles
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US271938A
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Andre H Brisse
Donald E Rohaus
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United States Steel Corp
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United States Steel Corp
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    • 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

Definitions

  • This invention relates to an improved method of briquetting iron oxide fines with a bituminous coal binder.
  • iron oxide fines Before iron oxide fines can be charged to a blast furnace or similar reducing reactor, they must be formed into agglomerates large enough not to be blown from the furnace.
  • the agglomerates must have sufiicient mechanical strength to avoid excessive degradation in handling at ordinary temperatures, and also to withstand temperatures and conditions encountered in blast furnace operation.
  • limestone or dolomite can be included in the agglomerates in quantities to make them selfdluxing.
  • Briquetting is one of several processes currently used for agglomeratin'g iron oxide fines. Usually a briquetting process involves pressing the fines into pillow-shaped bodies under high pressures in a roll-type press.
  • the fines can be briquetted at high temperatures without a binder, or at lower temperatures with a binder, such as bituminous coal, pitch, molassess, sulfite liquor and others.
  • a bituminous coal binder serves an additional purpose of furnishing carbon which can be used in the reducing reactions in a furnace. However, it is difiicult to produce coalbonded briquettes which have sufficient mechanical strength. Unless coal is heated to a temperature at which it is plastic, it does not provide a good bonding action, but at such temperatures it oxidizes readily and loses its bonding properties.
  • An object of our invention is to provide an improved method of briquetting iron oxide fines using a bituminous coal binder with or without fiux and obtaining agglomerates which have satisfactory mechanical strength both cold and under conditions found in a blast furnace.
  • a further object is to provide a briqu'etting method which attains the foregoing advantage by heating the materials to a critical apparent temperature range before briquetting, yet preventing the expected oxidation of the coal at this temperature.
  • a more specific object is to provide a briquetting method in which iron oxide fines and flux, if used, are heated to a temperature higher than the optimum briquetting temperature and mixed with low-temperature coal fines and the mixture promptly briquetted without destroying the bonding properties of the coal.
  • the single figure is a schematic liowsheet of our briquetting method.
  • this apparatus is a rotary kiln which has a burner 14 and blower 15. Both the iron oxide and flux fines are minus A inch or smaller, and preferably at least 60 percent minus 16 mesh.
  • a gaseous or liquid fuel in the heating apparatus, preferably with excess air and under oxidizing conditions to obtain efficient combustion and fuel utilization. In this manner We heat the fines to a temperature substantially above that at which we subsequently form the briquettes, as hereinafter explained, but not to a temperature at which the particles sinter or calcine.
  • the coal fines can be at ambient temperature, as when they come from storage, or they can be preare t ice heated to a temperature below that at which they oxidize appreciably, as when they come from a dryer. Therefore We intend the term low-temperature as applied to the coal fines to refer to any temperature below about 200 F.
  • the coal fines preferably are minus 8 mesh.
  • the mixer is a conventional pugmill which is insulated to retain heat. We continue mixing until we obtain a uniformly dispersed mixture of the various types of particles.
  • the mixture contains about 5 to 15 percent by weight coal and the remainder iron oxide and flux. At least 5 percent coal is needed to bond the other particles; if briquettes contain more than 15 percent coal, their strength at high temperatures diminishes.
  • thermocouple 13 in the stream of particles discharging from the mixer 16.
  • the apparent temperature measured by this thermocouple should be in the range of about 600 to 800 F., although we recognize that the ore and flux particles remain at higher temperatures than the coal particles.
  • We adjust the heat input to bring the apparent temperature of the mixture to the foregoing range. For example, if the coal particles are at an ambient temperature of about 70 R, we heat the ore and flux particles to a temperature of about 850 to 1050 F. in the heating apparatus 13.
  • coal particles Under ordinary oxidizing conditions bituminous coal particles ignite below 600 F., yet surprisingly in our process the coal particles do not oxidize appreciably even though we take no special measures to prevent their oxidation. It is possible the coal particles may give off volatile matter which replaces air in the relatively confined mixer 16 and thus produces a non-oxidizing atmosphere, and also that the rate of heat transfer is sufficiently slow during mixing that the coal particles do not reach their ignition temperature.
  • a conventional briquetting press 19 illustrated as of the roll type. Heat continues to be transferred from the hotter particles to the cooler as the particles pass through the press.
  • the press compacts the particles under a load of about 30,000 to 65,000 pounds per linear inch of effective roll width and thus forms them into pillow-shaped briquettes.
  • the finished briquettes are of a size about 1 /2 by by inch, and they have satisfactory mechanical strength, both at ordinary temperatures and under conditions prevalent in a blast furnace. They also show a high degree of microporosity which is desirable in materials used in a blast furnace. If the briquettes are formed properly, the coal flows around the other particles. Discrete coal particles in the briquettes are evidence of insufficient mixing or failure of the mixture to reach the proper apparent temperature range. We regard this range as critical, since briquettes formed from mixtures at temperatures outside this range are of noticeably poorer quality.
  • Example 1 We fed a mixture of minus inch Venezuelan iron ore fines and minus /8 inch limestone fines directly into a 15 foot by 2 foot gas-fired rotary kiln, where we heated the particles to a temperature of approximately 950 to 1925 F. We transferred the heated particles to a 5 foot by 1 foot single shaft pug mill, and also fed minus inch Pittsburgh Seam bituminous coal fines at ambient temperature directly into the pug mill alongside the hot orelimestone particles. We mixed the particles to form a uniform mixture which had an apparent temperature of about 725 to 800 F. The mixture contained the different particles in the following proportion by weight:
  • Example 2 We produced briquettes by the same procedure described in Example 1, and tested them the same way, except that the kiln discharge temperature was about 850 to 925 F. and the apparent temperature of the mixture about 600 to 650 F. We found about 70 percent of the product was retained on 3-mesh after tumbling.
  • Example 3 To demonstrate the advantages of heating the particles by the procedure we have described, we mixed similar ore, limestone and coal particles in the same proportions at ambient temperatures. We briquetted the mixture in the same press under similar loading (a) at ambient temperature, (b) heated to about 350 F. in a gas-fired kiln, and (c) heated to about 450 F. We were unable to heat the mixture to any higher temperatures in the kiln without burning the coal particles. We found about 23 percent, 38 percent and 48 percent respectively of the product Was retained on 3-mesh after tumbling in the three tests.
  • we are able to use higher briquetting temperatures than are possible otherwise, thus producing stronger briquettes better suited for blast furnace use.
  • a method of briquetting iron oxide fines comprising heating the fines to an elevated temperature, introducing the heated fines and low-temperature bituminous coal fines to a mixer in proportions to provide about 5 to percent by Weight of coal, mixing the fines for at least 30 seconds to attain a mixture in which the iron oxide and coal particles are uniformly dispersed, the temperature to which the iron oxide fines are heated being adjusted to produce an apparent temperature in the mixture in the range of about 600 to 800 F, and compacting the mixture into briquettes directly following the mixing step and while its apparent temperature remains in said range, the coal itself serving as a binder in the briquettes.
  • a method of briquetting iron oxide fines and flux fines comprising heating iron oxide fines and flux fines to an elevated temperature, introducing the heated fines and low-temperature bituminous coal fines to a mixer in proportions to provide about 5 to 15 percent by Weight of coal and the remainder iron oxide and suificient flux to react with impurities in the iron oxide and coal, mixing the fines for at least 30 seconds to attain a mixture in which the various types of particles are uniformly dispersed, the temperature to which the iron oxide and flux particles are heated being adjusted to produce an apparent temperature in the mixture in the range of about 600 to 800 F. and compacting the mixture into briquettes directly following the mixing step and while its apparent temperature remains in said range, the coal itself serving as a binder in the briquettes.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (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)
  • Manufacture And Refinement Of Metals (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
US271938A 1963-04-10 1963-04-10 Method of briquetting iron oxide fines Expired - Lifetime US3174846A (en)

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BE646000D BE646000A (fi) 1963-04-10
US271938A US3174846A (en) 1963-04-10 1963-04-10 Method of briquetting iron oxide fines

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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3308219A (en) * 1963-05-16 1967-03-07 Metallgesellschaft Ag Method for making briquettes containing coal
US3328843A (en) * 1965-06-03 1967-07-04 United States Steel Corp Speed-control system for briquetting rolls
US3366717A (en) * 1964-05-18 1968-01-30 United States Steel Corp Method and apparatus for controlling hot-briquetting operation
US3479251A (en) * 1964-08-18 1969-11-18 Stamicarbon Process for the production of molded objects
US3751241A (en) * 1970-12-28 1973-08-07 Bethlehem Steel Corp Method for producing weather-resistant superfluxed metallized pellets from iron-bearing fines and a superfluxed metallized pellet produced thereby
US3917795A (en) * 1970-11-30 1975-11-04 Black Sivalls & Bryson Inc Method of treating coal refuse
US4389178A (en) * 1981-07-31 1983-06-21 K. R. Komarek, Inc. Ram-type feeder for briquetting press
EP0286844A1 (de) * 1987-04-02 1988-10-19 Thyssen Stahl Aktiengesellschaft Verfahren und Anlage zur Herstellung von bindemittellosen Heissbriketts
US4786451A (en) * 1984-02-09 1988-11-22 Doren, Inc. Method of manufacturing a metallurgical addition agent
US4865642A (en) * 1986-11-17 1989-09-12 Iron Tiger Investments Inc. Particle agglomeration process
US5104446A (en) * 1989-09-29 1992-04-14 Iron Tiger Investment Inc. Agglomeration process
US5685524A (en) * 1996-01-16 1997-11-11 Chaparral Steel Company Direct ironmaking or steelmaking apparatus using self-reducing iron oxide pellets
US6409964B1 (en) 1999-11-01 2002-06-25 Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of Natural Resources Cold bonded iron particulate pellets
US20050061207A1 (en) * 2003-09-23 2005-03-24 Hanqing Liu Self-reducing, cold-bonded pellets
US20060278040A1 (en) * 2003-03-10 2006-12-14 Kabushiki Kaisha Kobe Seiko Sho(Kobe Steel, Ltd.) Process for producing reduced matal and agglomerate with carbonaceous material incorporated therein
US20180340240A1 (en) * 2017-05-26 2018-11-29 Novelis Inc. System and method for briquetting cyclone dust from decoating systems

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1583951B1 (de) * 1968-01-23 1972-01-20 Kloeckner Humboldt Deutz Ag Verfahren zur bindemittellosen Heissbrikettierung von vorreduzierten Eisenerzen

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1661636A (en) * 1926-04-07 1928-03-06 Kenneth M Simpson Process for treating flue dust
US1711153A (en) * 1925-07-06 1929-04-30 Consolidation Coal Products Co Ore-dust treatment
US1923803A (en) * 1930-10-16 1933-08-22 Trent Process Corp Briquette and method of producing same
US2794728A (en) * 1953-05-14 1957-06-04 Lesher And Associates Inc Process of making a flowable solid ore-carbon mass
US2823109A (en) * 1954-10-07 1958-02-11 Sudo Koji Process for manufacturing high grade pig iron
US2918364A (en) * 1957-10-30 1959-12-22 Lesher And Associates Inc Method of forming pellets of finely divided coked carbonaceous material and finely divided non-fusing material

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1711153A (en) * 1925-07-06 1929-04-30 Consolidation Coal Products Co Ore-dust treatment
US1661636A (en) * 1926-04-07 1928-03-06 Kenneth M Simpson Process for treating flue dust
US1923803A (en) * 1930-10-16 1933-08-22 Trent Process Corp Briquette and method of producing same
US2794728A (en) * 1953-05-14 1957-06-04 Lesher And Associates Inc Process of making a flowable solid ore-carbon mass
US2823109A (en) * 1954-10-07 1958-02-11 Sudo Koji Process for manufacturing high grade pig iron
US2918364A (en) * 1957-10-30 1959-12-22 Lesher And Associates Inc Method of forming pellets of finely divided coked carbonaceous material and finely divided non-fusing material

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3308219A (en) * 1963-05-16 1967-03-07 Metallgesellschaft Ag Method for making briquettes containing coal
US3366717A (en) * 1964-05-18 1968-01-30 United States Steel Corp Method and apparatus for controlling hot-briquetting operation
US3479251A (en) * 1964-08-18 1969-11-18 Stamicarbon Process for the production of molded objects
US3328843A (en) * 1965-06-03 1967-07-04 United States Steel Corp Speed-control system for briquetting rolls
US3917795A (en) * 1970-11-30 1975-11-04 Black Sivalls & Bryson Inc Method of treating coal refuse
US3751241A (en) * 1970-12-28 1973-08-07 Bethlehem Steel Corp Method for producing weather-resistant superfluxed metallized pellets from iron-bearing fines and a superfluxed metallized pellet produced thereby
US4389178A (en) * 1981-07-31 1983-06-21 K. R. Komarek, Inc. Ram-type feeder for briquetting press
US4786451A (en) * 1984-02-09 1988-11-22 Doren, Inc. Method of manufacturing a metallurgical addition agent
US4865642A (en) * 1986-11-17 1989-09-12 Iron Tiger Investments Inc. Particle agglomeration process
EP0286844A1 (de) * 1987-04-02 1988-10-19 Thyssen Stahl Aktiengesellschaft Verfahren und Anlage zur Herstellung von bindemittellosen Heissbriketts
AU610466B2 (en) * 1988-01-21 1991-05-16 Iron Tiger Investments Inc. A particle agglomeration process
US5104446A (en) * 1989-09-29 1992-04-14 Iron Tiger Investment Inc. Agglomeration process
US5685524A (en) * 1996-01-16 1997-11-11 Chaparral Steel Company Direct ironmaking or steelmaking apparatus using self-reducing iron oxide pellets
US6409964B1 (en) 1999-11-01 2002-06-25 Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of Natural Resources Cold bonded iron particulate pellets
US6676725B2 (en) 1999-11-01 2004-01-13 Her Majesty The Queen In Right Of Canada As Represented By The Minister Of Natural Resources Cold bonded iron particulate pellets
US20060278040A1 (en) * 2003-03-10 2006-12-14 Kabushiki Kaisha Kobe Seiko Sho(Kobe Steel, Ltd.) Process for producing reduced matal and agglomerate with carbonaceous material incorporated therein
US7674314B2 (en) * 2003-03-10 2010-03-09 Kobe Steel, Ltd. Process for producing reduced metal and agglomerate with carbonaceous material incorporated therein
US20050061207A1 (en) * 2003-09-23 2005-03-24 Hanqing Liu Self-reducing, cold-bonded pellets
US7896963B2 (en) 2003-09-23 2011-03-01 Hanqing Liu Self-reducing, cold-bonded pellets
US20180340240A1 (en) * 2017-05-26 2018-11-29 Novelis Inc. System and method for briquetting cyclone dust from decoating systems

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