Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B13/00—Making spongy iron or liquid steel, by direct processes
  • C21B13/0006—Making spongy iron or liquid steel, by direct processes obtaining iron or steel in a molten state
  • C21B13/0013—Making spongy iron or liquid steel, by direct processes obtaining iron or steel in a molten state introduction of iron oxide into a bath of molten iron containing a carbon reductant
  • C21B13/002—Reduction of iron ores by passing through a heated column of carbon

Definitions

• the invention relates to a method for removing sulfur in the melting of pig iron in a coal fluidized bed.
• the invention now aims to avoid such a separate desulphurization of the melt and to carry out most or all of the desulphurization work not only of the coal but also of the melt in the smelting reactor.
• the invention essentially consists in that lumpy and granular desulfurizing agent is introduced into the carbon fluidized bed and in the slag layer, that the portion of the desulfurizing agent for the coal spines is in the grain size range of 0.5-5 mm and the portion of the desulfurizing agent for the Slag in the grain size range of 5 - 50mm is introduced and that the proportion of lumpy desulfurizing agent in the total mixture is selected to be less than or equal to 50% by weight.
• Such a control possibility is achieved according to the invention by introducing the proportion of the desulfurization agent for the coal fluidized bed in the grain size range of 0.5-5 mm and the proportion of the desulfurization agent for the slag in the grain size range of 5-50 mm, these two proportions being varied within wide limits can and in this way an adjustment of the heavy weight of the desulfurization reaction to the fluidized bed or the slag layer can be achieved.
• the desulfurization reaction with CaO is endothermic and preferably takes place in the direction of higher temperatures.
• the feedstocks intended for post-desulphurization have already been metered into the melter gasifier in granular and / or lumpy form and whirled together with the coal according to their grain size. They bind the carbon sulfur in a solid, liquid or sublimed state of aggregation or, in the case of a coarser grain, immediately fall through the fluidized bed and slowly dissolve in the slag layer in close contact with the melting iron sponge.
• the heavy weight of the desulfurization reaction can be shifted into the fluidized bed or into the slag layer by varying the lumpy or granular fraction of the desulfurization agent.
• manganese, calcium, magnesium, alkalis or rare earths in the form of oxides, carbides, carbonates, alloys, mixed metals or in metallic form can be used as the desulfurizing agent.
• the use of calcium carbonate alone has the disadvantage that, when charging directly into the carburetor, considerable amounts of energy are required to drive off and convert C0 2 .
• Calcium carbide is therefore used according to the invention in a particularly preferred manner as a desulfurization agent. The desulfurization reaction with CaC 2 takes place with the release of energy and preferably in the direction of low temperatures.
• Calcium carbide also acts as a deoxidizer to reduce the FeO content in the slag.
• the reaction products CaO and CaS are taken up by the slag.
• the process according to the invention is advantageously carried out in such a way that the granular and the lumpy portion of the desulfurization agent is introduced above or laterally into the carbon fluidized bed.
• the desulfurization agent can be introduced in a simple manner together with coal, aggregates or recycling materials.
• the desulfurizing agents are at least partially introduced in agglomerated form.
• the invention is explained in more detail below using an exemplary embodiment.
• About 1000 kg of coal were used in a smelting gasifier per ton of pig iron.
• the coal had a sulfur content of 1.0%.
• the sulfur was composed of 60% organically bound sulfur and 40% inorganic sulfur (pyrite, sulfide, sulfate-S). Most of the inorganic sulfur was released during the degassing of the coal and went into the reducing gas. The remaining sulfur, approx. 6-7 kg / t pig iron, was converted into the gaseous state in the fluidized bed during combustion in front of the nozzles or gasification of the coked coal (S-Dampf, S0 2 , COS).
• the gaseous sulfur came into contact with the fine-grained CaC 2 and was bound to CaS.
• About 4 kg of S were converted into CaS in this way.
• the remaining 3 kg were either absorbed by the aggregate lime or by the hot sponge iron that fell through the fluidized bed.
• the iron sponge containing Fe was then desulfurized on contact with the lumpy calcium carbide floating on the slag surface.
• the reaction product CaS dissolved in the slag.
• the sulfur content of the slag was between 2 and 3% and the sulfur in pig iron was 0.1%.

Landscapes

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

Applications Claiming Priority (2)

Publications (2)

Family

ID=3517920

Family Applications (1)

Country Status (5)

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• 1983
  • 1983-05-04 AT AT0164683A patent/AT387036B/de not_active IP Right Cessation
• 1984
  • 1984-04-26 EP EP84890076A patent/EP0128131B1/de not_active Expired
  • 1984-04-26 DE DE8484890076T patent/DE3462925D1/de not_active Expired
  • 1984-04-30 US US06/605,282 patent/US4566902A/en not_active Expired - Fee Related
  • 1984-05-04 JP JP59090086A patent/JPS59208007A/ja active Granted

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