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CA-3060868-C - IRON ORE PELLETS

CA3060868CCA 3060868 CCA3060868 CCA 3060868CCA-3060868-C

Abstract

The application describes pellets comprising particulate iron ore and between 0.05 and 1.0% by weight of an organic binder. The use of such pellets in electric arc furnaces to produce steel is also described.

Inventors

  • Nigel Pickett

Assignees

  • BINDING SOLUTIONS LTD

Dates

Publication Date
20260505
Application Date
20180418
Priority Date
20170418

Claims (14)

  1. 9 Claims 1. A method of producing steel comprising: providing a pellet comprising a particulate iron ore, and between 0.05 and 1.0 % by weight of a polymeric organic binder, the polymeric organic binder comprising polyvinyl alcohol and an organic resin; transporting the pellet to an electric arc furnace; and heating the pellet in the electric arc furnace.
  2. 2. A method according to claim 1, wherein the polymeric organic binder further comprises a polysaccharide.
  3. 3. A method according to claim 1, wherein the organic resin is selected from polyacrylamide resin, resole resin and Novolac resin.
  4. 4. A method according to claim 1, wherein the polyvinyl alcohol is present in the range 0.1 – 0.3 % by weight of the pellet.
  5. 5. A method according to claim 1, wherein the particulate iron ore is magnetic.
  6. 6. A method according to claim 1, wherein the pellet comprises a waterproofing agent.
  7. 7. A method according to claim 1, wherein the pellet additionally comprises up to 20% by weight of carbonaceous material.
  8. 8. A method according to claim 1, wherein the particulate iron ore is capable of passing through a 100μm mesh prior to pelleting.
  9. 9. A method according to claim 1, wherein the pellet is heated under a reducing atmosphere.
  10. 10. A method according to claim 9, wherein the reducing atmosphere comprises hydrogen, shale gas or natural gas.
  11. 11. A method according to claim 1, comprising mixing the pellet with scrap metal. 9149935
  12. 12. A method according to claim 11, wherein a mixture formed by mixing the pellet with the scrap metal comprising up to 50% by weight of the pellet.
  13. 13. A method according to claim 1, wherein the pellet is cold formed.
  14. 14. A method according to claim 14, wherein the pellet is formed without sintering or heating to above 60°C prior to being put in the furnace. CA 3060868

Description

Iron Ore Pellets Field The invention relates to pellets containing iron ore for use in electric arc furnaces and to methods of producing steel from such pellets. Background The production of briquettes from particulate iron and other metal ores is generally known in the art. Typically such particles are bound together using a binder such as cement or clay to form a briquette. Such briquettes are used in a blast furnace or in direct iron reduction (ORI). The briquette is designed to be sufficiently strong to allow the briquette to be successfully transported and to be used within the blast furnace. The briquette must be able to retain its integrity through the blast furnace into the melting furnace, otherwise the performance of blast furnaces or ORI plants can be adversely affected. A problem associated with using cement or clay is that this increases the amount of silica in the iron and slag produced at the end of the process. The high strength required for such briquettes has limited the use of more expensive binders such as starch or polyvinyl alcohol (PVA). Electric arc furnaces heat charged material using an electric arc, for example between two graphite electrodes. As arc forms between the charged material and the electrode. The charge is heated by current passing through the charge and by radiant energy evolved by the arc and can reach 3000°C. Summary Typically they are used to produce steel from scrap metal. Typically shred (from white goods or cars or other light gauge steel) or heavy melt (large slabs of beams) is used. A problem with using scrap metal is that the quality of the steel input (and thus the steel produced) is often poor. The steel often needs relatively expensive sponge iron or pig iron added to it. Scrap metal currently costs c.$280 per ton and sponge iron is often more expensive than this. The Applicant realised that using a less expensive source of iron would allow the production of steel using arc furnaces less expensively. One problem with using alternative sources, such as iron ores, is that the iron ore needs reducing to iron. This is not typically carried 1 9149962 Date re<;ue/Date received 2024-02-07 out in arc furnaces. However, they realised that if they could use iron ore particulate waste and use a reducing atmosphere in the arc furnace, then this could be used. The production of pellets for using in arc furnaces produces different problems to the convention pellets used in blast furnaces. The pellets need to be sufficiently heavy to break through the layer of slag on the top of the arc furnace. However, they must also be porous enough to allow the iron ore within the pellet to react with a reducing atmosphere within the furnace to produce iron. The iron then mixes with the scrap metal to produce the required steel in the arc furnace. The bonds holding the particles together should also be weak enough to allow the particles to melt and disperse into the molten metal evenly. The use of particulate materials increases the surface area of the iron oxide so that it is able to react with the reducing atmosphere more efficiently. Moreover, the inventors realised that if they use an organic binder, then this binder is burnt off within the heat of the furnace and increasing the porosity of the pellet so that it more readily reacts with the reducing atmosphere. The cost of pellets of iron ore is typically a 100% premium to the spot price of iron ore (pellets currently cost some $120 per ton). Accordingly, this process allows the reduction of the price of steel produced by the arc furnace. Moreover, the selection of cheaper reducing gases, also assists in reducing the cost of producing steel using the arc furnace. The invention provides a pellet comprising a particulate iron ore and less than 1.5% by weight of a binder. The binder is typically an organic binder. As discussed above organic binders have the advantage that they typically are burnt off by the heat of the furnace to increase the porosity of the material within the furnace. The particulate material is typically of a diameter 4mm or less, more typically less than 1mm, or less than S00micron or less than 100micron. This may be determined by being able to pass through a sieve. Typically at least 10% by weight of particulate material is capable of passing through a 100μm sieve before to forming into a pellet. More typically a sieve size of 30μm or 20μm is used to sieve the material. At least 50%, 80% or 100% of the material may pass through the sieve. It should be noted that the term "pellet" includes objects commonly referred to as pellets, rods, pencils slugs. Pellets typically have a maximum average diameter of 20mm, more typically 16mm or 15mm, a minimum average diameter of 2mm, especially 5mm or an average diameter of 10-12mm. These object share the common feature of being a compacted form of material and are differentiated principally by their size and shape. 2 9149962 Date re<;ue/Date received 2024-02-07 The binder ma