Method for producing an agglomerate made of fine material containing metal oxide for use as a blast furnace feed material

Abstract

The invention relates to a method for producing an agglomerate, which is used as a blast furnace feed material, by mixing a fine material containing metal and/or metal oxide, a mineral binder, which comprises a mineral raw material and a lime-based material, and optionally other additives to form a mass and solidifying the mass to form an agglomerate, wherein a raw material comprising a silicon oxide fraction of at least 40 wt %, a fine grain fraction of less than 4 m of at least 20 wt %, and a grain size fraction of less than 1 m of at least 10 wt % is used as the mineral raw material. The invention further relates to a blast furnace feed material that can be produced by means of the method according to the invention, and to a pre-mixture for producing the blast furnace feed material.

Claims

1. Agglomerate produced by a sintering process for use as a blast furnace feedstock, comprising metal- and/or metal oxide containing fines, that comprise a proportion of intermediate grain sizes between about 0.2 mm to 0.7 mm of more than 30% wt., and a mineral binder comprising a mineral raw material and a lime-based material, wherein the mineral raw material contains a clay mineral, and comprises a silicon oxide proportion of at least 40 wt. %, and a finest grain proportion of less than 4 m of at least 20 wt. %, and a grain size proportion of less than 1 m of at least 10 wt. %; wherein the mineral raw material comprises short clay that consists of at least 60 wt. % of fine quartz and 20 to 40 wt. % kaolinite and optionally secondary micas.

2. Agglomerate according to claim 1, wherein the metal- and/or metal oxide containing fines and the mineral binder are present in the agglomerate in a proportion of 5:1 to 1000:1 wt.:wt.

3. Agglomerate according to claim 1, wherein the lime-based material is selected from the group consisting of lime, lime stone, quick lime, slaked lime, hydrated lime, dolomite, dolomitic lime, dolomitic quick lime, dolomitic hydrated lime, and combinations thereof.

4. Agglomerate according to claim 1, wherein the metal- and/or metal oxide containing fines are selected from the group consisting of fine ore, fine iron ore, tinder materials, mill scale, top gas dust, returns from the sintering process, metal abrasive dust, metal filings, and combinations thereof.

5. Agglomerate according to claim 4, wherein the agglomerate may contain conventional sintering additives selected from the group consisting of coke breeze, ladle residue, slags, and combinations thereof.

6. Agglomerate according to claim 5, wherein the agglomerate is in the form of a finished sinter.

7. Agglomerate according to claim 1, wherein the agglomerate contains at least 30 wt. % fines containing a grain size proportion of less than 2 mm.

8. Premixture according to claim 1, wherein the mineral raw material comprises a silicon oxide proportion of at least 60 wt. %, and a finest grain proportion of less than 2 m of at least 40 wt. %, wherein the grain size proportion of less than 0.5 m is at least 25 wt. %.

9. Premixture according to claim 8, wherein the mineral raw material comprises a silicon oxide proportion of at least 75 wt. %, and a finest grain proportion of less than 2 m of at least 40 wt. %, wherein the grain size proportion of less than 0.5 m is at least 25 wt. %.

10. Premixture for producing a blast furnace feedstock according to claim 1, containing: metal- and/or metal oxide containing fines, wherein the metal- and/or metal oxide containing fines comprise a proportion of fines with an average grain diameter of less than 1 mm of more than 30 wt. %, and a mineral binder that comprises a mineral raw material and a lime-based material, wherein the mineral raw material contains a clay mineral, and wherein the mineral raw material contains short clay, consisting of at least 60 wt. % of fine quartz and 20 to 40 wt. % kaolinite and optionally secondary micas.

11. Premixture for producing a blast furnace feedstock according to claim 1, containing: metal- and/or metal oxide containing fines, wherein the metal- and/or metal oxide containing fines comprise a proportion of fines with an average grain diameter of less than 1 mm of more than 30 wt. %, and a mineral binder that comprises a mineral raw material and a lime-based material, wherein the mineral raw material contains a clay mineral and wherein the mineral raw material comprises 70 to 90 wt. % silicon oxide, 5 to 20 wt. % aluminium oxide, 0.2 to 1.5 wt. % Fe.sub.2O.sub.3 and 0.1 to 1 wt. % potassium oxide.

12. Agglomerate according to claim 1, wherein the metal- and/or metal oxide containing fines containing ore containing intermediate grain sizes with a grain size proportion of approximately 0.05 mm to 1 mm in a quantity of at least 30 wt. %.

13. Premixture for producing a blast furnace feedstock according to claim 1, containing: metal- and/or metal oxide containing fines, wherein the metal- and/or metal oxide containing fines comprise a proportion of fines with an average grain diameter of less than 1 mm of more than 30 wt. %, and a mineral binder that comprises a mineral raw material and a lime-based material, wherein the mineral raw material contains a clay mineral.

14. Premixture according to claim 13, wherein the premixture contains 50 to 99 wt. % of metal- and/or metal oxide containing fines and 1 to 20 wt. % of conventional additives and mineral binder.

15. Premixture according to claim 14, wherein the mineral binder comprises 30 to 98 wt. % lime-based materials and 2 to 70 wt. % mineral raw material.

16. Premixture according to claim 15, wherein the premixture contains 0 to 30 wt. % additives, selected from the group consisting of coke breeze, ladle residue, slags, and combinations thereof.

17. Agglomerate produced by a sintering process for use as a blast furnace feedstock, comprising metal- and/or metal oxide containing fines, that comprise a proportion of intermediate grain sizes between about 0.2 mm to 0.7 mm of more than 30% wt., and a mineral binder comprising a mineral raw material and a lime-based material, wherein the mineral raw material contains a clay mineral, and comprises a silicon oxide proportion of at least 40 wt. %, and a finest grain proportion of less than 4 m of at least 20 wt. %, and a grain size proportion of less than 1 m of at least 10 wt. %; wherein the mineral raw material comprises 70 to 90 wt. % silicon oxide, 5 to 20 wt. % aluminium oxide, 0.2 to 1.5 wt. % Fe.sub.2O.sub.3 and 0.1 to 1 wt. % potassium oxide.

18. Agglomerate produced by a sintering process for use as a blast furnace feedstock, comprising metal- and/or metal oxide containing fines that comprise a proportion of intermediate grain sizes between about 0.2 mm to 0.7 mm of more than 30% wt., and a mineral binder comprising a mineral raw material and a lime-based material, wherein the mineral raw material contains a clay mineral, and comprises a silicon oxide proportion of at least 40 wt. %, and a finest grain proportion of less than 4 m of at least 20 wt. %, and a grain size proportion of less than 1 m of at least 10 wt. % wherein before the sintering process the agglomerate has a mass humidity that is set at a value of 2 to 20 wt. %.

19. Agglomerate, produced by a sintering process for use as a blast furnace feedstock, comprising metal- and/or metal oxide containing fines, that comprise a proportion of intermediate grain sizes between about 0.2 mm to 0.7 mm of more than 30% wt., and a mineral binder comprising a mineral raw material and a lime-based material, wherein the mineral raw material contains a clay mineral, and comprises a silicon oxide proportion of at least 40 wt. %, and a finest grain proportion of less than 4 m of at least 20 wt. %, and a grain size proportion of less than 1 m of at least 10 wt. %, wherein the mineral raw material comprises approximately 83 wt. % silicon oxide, approximately 13 wt. % aluminium oxide, approximately 0.7 wt. % Fe.sub.2O.sub.3 and approximately 0.4 wt. % potassium oxide.

Description

(1) In the following the invention is illustrated in more detail by way of an example.

(2) Five different sinter belt mixtures (mixture 1, 2, 3, 3a, 3b) are produced. In order to produce mixtures 3a and 3b fines, comprising a defined proportion of intermediate grain sizes, are mixed with the respective binder and conventional sinter excipients and the mass humidity is adjusted. For the mixture according to the invention 3b a mineral raw material is used as the binder, comprising a silicon oxide proportion of at least 40 wt. %, and a finest grain proportion of less than 4 m of at least 20 wt. % and a grain size proportion of less than 1 m of at least 10 wt. %.

(3) Mixtures 1, 2 and 3 are produced without the addition of binder. Then the mixture is mixed with water and layered on a sinter belt. The mixture has a specific gas permeability, which can be measured using the pressure loss in an air flow forced through the mixture. A low pressure loss indicates a good gas permeability. A good gas permeability is desirable in the sintering process since it leads to a good burning through of the sinter cake.

(4) In the following table, the pressure losses for mixtures 1, 2, 3, 3a, 3b are illustrated. A comparison of mixtures 1, 2, 3 shows that an increase in the proportion of intermediate grain sizes leads to an increase in pressure loss and to a reduction in gas permeability. A comparison of mixtures 3, 3a shows that through the addition of CaO as binder an improved gas permeability can be achieved.

(5) Using the example 3b according to the invention it was possible to prove that through use of the special mineral binder a mixture with a particularly good gas permeability can be obtained.

(6) TABLE-US-00001 Proportion of ore containing inter- Mass Pressure mediate grain sizes humidity loss Mixture (wt. %) (wt. %) Binder (Pa) 1 7 6.6 0 340 2 21 7.6 0 580 3 36 7.6 0 1300 3a 36 7.6 CaO 780 (1.6 wt. %) 3b 36 7.6 mineral binder 420 (2.4 wt. %)