US3197303A - Process for pretreatment of ores in rotary kiln - Google Patents

Process for pretreatment of ores in rotary kiln Download PDF

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Publication number
US3197303A
US3197303A US173539A US17353962A US3197303A US 3197303 A US3197303 A US 3197303A US 173539 A US173539 A US 173539A US 17353962 A US17353962 A US 17353962A US 3197303 A US3197303 A US 3197303A
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Prior art keywords
kiln
charge
coal
reducing agent
zone
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US173539A
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English (en)
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Collin Fredrik Christen
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Elektrokemisk AS
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Elektrokemisk AS
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/003—Phosphorus
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/01—Treating phosphate ores or other raw phosphate materials to obtain phosphorus or phosphorus compounds
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/90—Carbides
    • C01B32/914—Carbides of single elements
    • C01B32/942—Calcium carbide
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/08—Making spongy iron or liquid steel, by direct processes in rotary furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
    • C21B13/105—Rotary hearth-type furnaces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
    • Y02P10/134—Reduction of greenhouse gas [GHG] emissions by avoiding CO2, e.g. using hydrogen

Definitions

  • This invention relates to the pretreatment of ores or other oxides or materials of the type which are customarily treated in a submerged arc smelting furnace.
  • ores or other oxides or materials of the type which are customarily treated in a submerged arc smelting furnace.
  • These include iron oxides, various oxides for producing ferro alloys such as ferro manganese or ferro silicon, and also can be used in the production of calcium carbide and phosphorus.
  • the material to be treated is preheated and preferably more or less reduced in a rotary kiln.
  • carbonaceous material such as bituminous coal, lignite, peat or the like, containing a substantial portion of volatiles is introduced into the kiln in an intermediate zone comprising the longitudinal middle one third of the furnace where the charge has been brought up to such temperature that the coal will be given such a sudden carbonization that the plastic period of the coal is quickly passed and sticking to the lining is avoided.
  • Such coal is introduced into the kiln in such a Way that it falls onto the charge rather than onto the sides of the kiln and air is supplied in the intermediate zone so that the volatiles driven out of the coal will burn with a luminous heat radiating flame in the central part of the kiln to extend the zone of high heat toward the feed end of the kiln.
  • the kiln is provided in the central one-third of its length with a series of pipes that extend into the kiln and are provided on their outer ends with scoops that dip into a mass of the coal.
  • the scoops pick up the coal and then as rotation continues the coal passes through the pipes to the inside of the kiln and drops onto the hot charge at the bottom of the kiln.
  • the kiln is operated at a pressure slightly below atmospheric so that additional air will come in through the scoops after they have delivered their charge of coal.
  • the kiln is fired at the discharge end and any convenient fuel may be employed as oil or gas. If the charge from the furnace is to be introduced into an adjacent electric smelting furnace, gas from such furnace may advantageously be employed.
  • a specially reactive coke is obtained by wholly or partly employing bituminous coal as a reducing agent.
  • the resulting coke has high porosity and consequently high chemical reactivity with large surface area, and
  • the use of such coal has however been largely limited as it causes great problems sincethe coal goes through a plastic interval at temperatures between 400 and 700 C. and at this stage the coal will stick to the lining of the furnace.
  • the coal which is fed more or less continuously so that it drops onto the preheated charge is heated with great rapidity and gives up its volatiles and passes through the plastic stage substantially without contacting the kiln walls.
  • This supplies the coke of a particularly valuable nature and volatile constituents are caused to burn in the central part of the furnace so that the heating zone is extended.
  • the air for burning the volatiles from the coal may be introduced through the same pipes as introduced the coal or additional air pipes as frequently used may be supplied preferably toward the discharge end of the kiln. Also such air may be introduced by supplying excess air to the kiln burner.
  • the remaining carbon required for reduction of the charge is introduced into the feed end of the kiln along with the charge.
  • the carbon introduced into the feed end of the kiln is in the form of coke or other carbonaceous material with a low volatile content of not more than about 25%.
  • the distance between the spaced feed points in the intermediate zone of the kiln is not more than about three times the inside diameter of the kiln and preferably about twice the inside diameter of the kiln.
  • a typical rotary kiln for commercial production of 'iron sponge or prereduction of iron ore and subsequent electric smelting may have an inside diameter between 2 to m. and a length of 50 to 100 m. The distance between the feed points in the intermediate zone for these kilns will be from about 4 to In.
  • a plurality of feeders may be employed in the intermediate zone of the kiln. For example excellent results have been achieved in a kiln 3 m. in diameter and 100 m. long by spacing five feeders in the intermediate zone of the kiln arranged 30, 36, 42, 48 and 54 meters away from the discharge end of the kiln.
  • the desired high temperature in the intermediate zone of the kiln is best achieved by feeding approximately the same amount of coal into the kiln at each of the five spaced feed points and if the coal is fed at two or more feed points all the carbon required for reduction of the charge may be introduced into the intermediate zone of the kiln. Feeding coal into the intermediate zone of the kiln at two or more spaced feed points is of particular advantage in the production of carbide. In such case the temperature in the kiln may be kept sufiiciently high for calcination of the limestone without building up objectionable deposits on the Wall of the kiln.
  • FIG. 1 shows a side view of the kiln.
  • FIG. 2 is a section on line 2- 2 of FIG. 1.
  • FIG. 3 shows the kiln of FIG. 1 with a plurality of feeders positioned in the intermediate zone of the kiln.
  • the charge may be introduced from a storage hopper 14 through a pipe 16, which. is provided with a control valve 18.
  • the smoke and exhaust gases pass into a smoke chamber 20 and then are taken to a flue by pipe 22.
  • the kiln At the discharge end the kiln is provided with a discharge pipe 24 and a usual burner 26 for oil or gas. It is understood that air will also be introduced through the burner 26. If desired, the discharge pipe 24 may pass directly into an electric smelting furnace as is well understood in the art and gas from such a smelting furnace may be used as fuel for the burner 26. Up to this point the kiln is conventional.
  • a container 32 runs under the kiln in the zone of the scoops 30 and has an upwardly extending portion 34 which follows the contour of the kiln.
  • a hopper 36 is provided for the coal which may be connected with feeder 38 and discharge pipe 40 which discharges the coal, or other non-coked fuel into the upwardly extending portion 34.
  • I employed a kiln 8.3 meters long having an internal diameter of .55 meter. Powdered Hematite ore having an Fe content of about 60% was used. For part of the test the ore was mixed with the full quantity of gas coke and passed through the kiln in the usual manner with the pipe 28 closed off. In the other case one-half of the carbonaceou material was mixed with the charge in the form of gas coke and the other half was made up of powdered coal taken from the Longyear Mine in Spitzbergen, with 60% fixed carbon and 40% volatiles. This was introduced at about the central zone of the kiln and after the charge had reached a temperature of about 800 C.
  • the kiln was run at the same feeding rate and a temperature of 900 to 1000 wa maintained between the point where the coal was fed in and the discharge end of the kiln.
  • the kiln in this case was oil fired from the discharge end and the rate of feeding was about 300 kg. of charge per hour.
  • the kiln illustrated in FIG. 3 is identical to the kiln shown in FIG, 1 with the exception that two of the feeders illustrated in FIG. 2 are located in the intermediate zone of the kiln. As shown in FIG. 3 the distance between the spaced feed points is about twice the interior diameter of the kiln. As a result of feeding coal into the intermediate zone of the kiln at a plurality of spaced points the temperature of the charge may exceed the softening point without building up objectionable deposits on the wall of the kiln.
  • a process of heating in a rotating cylindrical kiln metal oxides of the type which are smelted and reduced in an electric furnace which comprises introducing into the feed end of said kiln a charge of said metal oxide and from about one third to about two thirds of the amount of carbonaceous reducing agent required for reducing all of said metal oxide, such carbonaceous reducing agent having a relatively low volatiles content up to about 25% by weight, heating said charge to a temperature of at least about 800 C., dropping upon said heated charge, while the same is located in a zone corresponding to the longitudinal middle third of said kiln, the remaining two thirds .to one third or" carbonaceous reducing agent required for complete reduction, said second-mentioned carbonaceous reducing agent having a relatively high volatiles content greater than about 25% by weight and being dropped upon said heated charge from a plurality of feed points spaced apart from each other a distance not greater than about three times the inside diameter of said kiln, and introducing suflicient air in said dropping zone to ignite and burn with

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
  • Electrically Operated Instructional Devices (AREA)
US173539A 1961-02-24 1962-02-15 Process for pretreatment of ores in rotary kiln Expired - Lifetime US3197303A (en)

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NO139223A NO118749B (enrdf_load_stackoverflow) 1961-02-24 1961-02-24

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US3197303A true US3197303A (en) 1965-07-27

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US (1) US3197303A (enrdf_load_stackoverflow)
ES (1) ES274865A2 (enrdf_load_stackoverflow)
FI (1) FI40291B (enrdf_load_stackoverflow)
GB (1) GB935353A (enrdf_load_stackoverflow)
NO (1) NO118749B (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3272616A (en) * 1963-12-30 1966-09-13 Int Nickel Co Method for recovering nickel from oxide ores
US3317308A (en) * 1962-10-16 1967-05-02 Electro Chimie Metal Process for reduction of iron ores
US3328161A (en) * 1962-12-07 1967-06-27 Metallgesellschaft Ag Process for reducing iron ore pellets
US3407059A (en) * 1965-04-22 1968-10-22 Selas Corp Of America Reducing a mixture of ores and carbon
US3486883A (en) * 1964-10-09 1969-12-30 Metallgesellschaft Ag Process for the production of iron sponge
WO2001073137A3 (en) * 2000-03-30 2002-01-10 Midrex Internat B V Method of producing metallic iron and raw material feed device

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US890563A (en) * 1908-02-06 1908-06-09 George A St Clair Method of treating cooper ores.
US2484911A (en) * 1945-04-21 1949-10-18 Seil Frances Merritt Rotary kiln
US2593398A (en) * 1943-06-11 1952-04-22 Kalling Bo Michael Sture Method of reducing ores without melting
US2754197A (en) * 1952-09-26 1956-07-10 Wienert Fritz Otto Method and a rotary kiln for the manufacture of sponge iron
US3029141A (en) * 1960-03-21 1962-04-10 Canada Steel Co Process for the reduction of iron oxide

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US890563A (en) * 1908-02-06 1908-06-09 George A St Clair Method of treating cooper ores.
US2593398A (en) * 1943-06-11 1952-04-22 Kalling Bo Michael Sture Method of reducing ores without melting
US2484911A (en) * 1945-04-21 1949-10-18 Seil Frances Merritt Rotary kiln
US2754197A (en) * 1952-09-26 1956-07-10 Wienert Fritz Otto Method and a rotary kiln for the manufacture of sponge iron
US3029141A (en) * 1960-03-21 1962-04-10 Canada Steel Co Process for the reduction of iron oxide

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3317308A (en) * 1962-10-16 1967-05-02 Electro Chimie Metal Process for reduction of iron ores
US3328161A (en) * 1962-12-07 1967-06-27 Metallgesellschaft Ag Process for reducing iron ore pellets
US3272616A (en) * 1963-12-30 1966-09-13 Int Nickel Co Method for recovering nickel from oxide ores
US3486883A (en) * 1964-10-09 1969-12-30 Metallgesellschaft Ag Process for the production of iron sponge
US3407059A (en) * 1965-04-22 1968-10-22 Selas Corp Of America Reducing a mixture of ores and carbon
WO2001073137A3 (en) * 2000-03-30 2002-01-10 Midrex Internat B V Method of producing metallic iron and raw material feed device
US6630010B2 (en) 2000-03-30 2003-10-07 Midrex International B.V. Zurich Branch Method of producing metallic iron
EP2221388A1 (en) * 2000-03-30 2010-08-25 Kabushiki Kaisha Kobe Seiko Sho "Method of producing metallic iron and raw material feed device"

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Publication number Publication date
GB935353A (en) 1963-08-28
NO118749B (enrdf_load_stackoverflow) 1970-02-09
ES274865A2 (es) 1962-04-16
FI40291B (enrdf_load_stackoverflow) 1968-09-02

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