Importance of fine ore chemical composition and high temperature phase relations: applications to iron ore sintering and pelletising

Abstract

In the iron ore industry significant emphasis is placed throughout the mining process on meeting chemical composition specifications for the export of fine ores. However, little has been published on the implications of ore chemical composition for iron ore sinter and pellet product quality. The ore bulk composition and the nature of the minerals in the fine ore both play a critical role in determining the type of high temperature bonding phases that form during sintering and pelletising. This paper uses the experimental determination of phase relations in model sinter and pellet systems such as Fe₂O₃-CaO-SiO₂ (FCS) and Fe₂O₃-Al₂O₃-CaO-SiO₂ (FACS) to examine the links between iron ore chemical composition and the temperatures used during sintering and pellet firing. The phase relations help to establish the critical thermal and compositional parameters that control the bonding phase chemistry, which in turn influences the physical characteristics of the sinter or pellet matrix. Results show that lower Fe grade (<62%Fe) ores and concentrates will typically form SFCA as part of the final assemblage, medium grade (62-65%Fe) ores will form a mixture of SFCA and SFCA-I, while high grade (65-68%Fe) ores will form largely SFCA-I. The SFCA-I phase is the most desirable bonding phase in iron ore sinter and pellets since microstructures composed entirely of SFCA-I show higher physical strength and higher reducibility than microstructures composed predominantly of SFCA.

Keywords

IRON ORE CHEMICAL COMPOSITION HIGH TEMPERATURE PHASE RELATIONS SINTERING PELLETISING

Get full access to this article

View all access options for this article.

References

ISHIKAWA

, SHIMOMURA

, SASAKI

, HIDA

and TODA

: ‘Improvement of sinter quality based on the mineralogical properties of ores’, in Proc. 42nd Iron-making Conference, Georgia, Atlanta, 1983, AIME, Warrendale, 42: 17-29.

LOO

C. E.

, WAN

K. T.

and HOWES

V. R.

: ‘Mechanical prop-erties of natural and synthetic mineral phases in sinters having varying reduction degradation indices’, Iron-making Steelmaking, 1988, 15, (6), 279–285.

CLOUT

J. M. F.

: unpublished data, CSIRO Minerals, 1994.

THOMAS

C. G.

, HAMILTON

J. D. G.

and BOWLING

K. MCG.

: ‘Effects of induration conditions on the structures and properties of iron ore pellets’, in Pellets and Granules Symp., Parkville, 1974, Newcastle and District Branch, AusIMM, 993–106.

KAMPERMAN

: ‘Quality control practices at BHP Iron Ore's Mt Whaleback Mine’, Proc. National Conf. on ‘Iron making resources and reserves estimation’ (ed. Misra

V. N.

and Dunlop

J. S.

), 77–78; 1997, Perth, Aus IMM.

MADAN

, FARQUAR

and RIGGS

: ‘A geologicalevalu-ation system - an illustrative case study’, Proc. National Conf. on ‘Iron making resources and reserves estima-tion’ (ed. Misra

V. N.

and Dunlop

J. S.

), 79–88; 1997, Perth, Aus IMM.

COLLINGS

P. S.

, KHOSROWSHAHI

and NESS

P. K.

: ‘Geo-logical modelling and geostatistical resource estimation of the Hope North Deposit’, Proc. National Conf. on ‘Iron making resources and reserves estimation’ (ed. Misra

V. N.

and Dunlop

J. S.

), 105–116; 1997, Perth, Aus IMM.

POWNCEBY

M. I.

, CLOUT

J. M. F.

and FISHER-WHITE

M. J.

: ‘Phase equilibria for the Fe203-rich part of the system Fe203-CaO-Si02 in air at 1240°-1300°C’, Miner Process. Extract. Metall. (Trans. Inst. MM. Metall. C), 107, 1–10.

POWNCEBY

M. I.

and CLOUT

J. M. F.

: ‘Phase relations in the Fe-rich part of the system Fe203(-Fe304)-CaO-Si02 at 1240-1300°C and p02=5 x10-3 atm: Implications for iron ore sinter’, Miner. Process. Extract. Metall. (Trans. Inst. MM. Metall. C), 2000, 109, 36–48.

10.

PHILLIPS

and MUAN

: ‘Phase equilibria in the system CaO-Iron Oxide-Si02 in air’, J. Am. Ceram. Soc., 1959, 42, 413–423.

11.

OSBORN

E. F.

and MUAN

: ‘Phase equilibrium diagrams of oxide systems’; 1960, Columbus, Ohio, American Ceramics Society.

12.

MUAN

and OSBORN

E. F.

: ‘Phase equilibria among oxides in steelmaking’, 114–115; 1965, MA, USA, Addison-Wesley.

13.

YANG

C. K.

, SHOJI

and TAKENOUCHI

: ‘Phase relations in the system CaO-A1203-Fe203-Si02 — Mineralogical study on sintered iron ores’, 2nd report, Nippon Kogyo Kaishi (J. MM. Metall. Inst. Jpn), 1978, 94, 575–580.

14.

STENLAKE

R. W.

, PEPPER

M. D.

and OSTWALD

: ‘The influence of alumina on the sintering characteristics of an Australian iron ore’, Proc. 3rd Int. Symp. on ‘Agglomeration’, Nuremberg, West Germany, 1981, European Federation for Chemical Engineering 1-17.

15.

MODEL

M. S.

, MALYSHEVA

T. YA

, LYADOVA

V. YA

, CHUGUNOVA

N. V.

, VLASOVA

E. V.

and ASTAKHOVA

G. K.

: ‘Solid solutions of calcium alumoferrite and silicoferrite in the iron enriched region of the system CaO-Fe203-A1203-Si02’, Russ. Metall., 1987, 2, 1–7.

16.

DAWSON

P. R.

, OSTWALD

and HAYES

K. M.

: ‘Influence of alumina on development of complex calcium ferrites in iron ore sinters’, Miner. Process. Extract. Metall. (Trans. Inst. MM. Metall. C), 1985, 94, 71–78.

17.

INOUE

and IKEDA

: ‘The solid solution state and crystal structure of calcium ferrite formed in lime-fluxed iron ores’, Tetsu-to-Haganè (in Japanese), 1982, 68, 2190-219 9.

18.

HAMILTON

J. D. G.

, HOSKINS

B. F.

, MUMME

W. G.

, BORBIDGE

W. E.

and MONTAGUE

M. A.

: ‘The crystal structure and crystal chemistry of Ca23Mg08Al1 5Sii Yes 302o (SFCA): solid solution limits and selected phase rela-tionships of SFCA in the Si02—Fe203—CaO(—A1203) system’, Neues Jahrbuch Miner. Abh., 1989, 161, 1–26.

19.

MUMME

W. G.

, CLOUT

J. M. F.

and GABLE

R. W.

: 'The crystal structure of SFCA-I, Ca318Fe3+904A1174Fe2+0165i06020% Neues Jahrbuch Miner. Abh., 1998, 173, 93–117.

20.

SASAKI

and HIDA

: ‘Consideration on the properties of sinter from the point of view of sintering reactions’, Tetsu-to-Haganè (in Japanese), 1982, 68, 563–571.

21.

AHSAN

S. N.

, MUKHERJEE

and WHITEMAN

J. A.

: ‘Struc-ture of fluxed sinter’, Ironmaking Steelmaking, 1983, 10, (2), 54–64.

22.

CLOUT

J. M. F.

and MANUEL

J. R.

: ‘Fundamental investi-gations of differences in bonding mechanisms in iron ore sinter formed from magnetite concentrates and hematite ores’, Powder Technol., 2003, 130, 393–399.

23.

HSIEH

L.-H.

and WHITEMAN

J. A.

: ‘Effect of oxygen potential on mineral formation in lime-fluxed iron ore sinter’, ISIJ Int., 1989, 29, 625–634.

24.

PATRICK

T. R. C.

and POWNCEBY

m I.

: ‘Stability of SFCA (silico-ferrite of calcium and aluminium) in air: solid solution limits between 1240°C and 1390°C and phase relationships within the Fe203-CaO-A1203-5i02 (FCAS) system’, Metall. Trans. B, 2002, 33, 79–89.

25.

POWNCEBY

M. I.

and PATRICK

T. R. C.

: ‘Stability of SFC: solid solution limits, thermal stability and selected phase relationships within the Fe203-CaO-Si02 (FCS) system’, Eur. J. Mineral., 2000, 12, 455–468.

26.

ALLEN

W. C.

and SNOW

R. B.

: 'The orthosilicate-iron oxide portion of the system Ca0-“Fe0”-5i02, J. Am. Ceram. Soc., 1955, 38 264–280.