SU1652366A1 - Fluxed iron ore pellets - Google Patents

Description

The invention relates to ferrous metallurgy and can be used for the production of pellets used in the smelting of iron in blast furnaces or in the preparation of sponge iron in shaft furnaces,

The purpose of the invention is to increase the strength of the pellets after firing and simplify the production technology without reducing their strength during recovery.

If hematite in the amount of 30-60 wt.% Is present in the pellets, there is no significant oxidation of the oxide melt when cooled in an atmosphere containing oxygen. This simplifies the technology of obtaining pellets compared to the prototype, since it allows to obtain pellets on high-performance firing machines without their special sealing and using expensive oxygen-free refrigerants (superheated steam, purified nitrogen, etc.).

When the content of hematite is more than 60%. magnetite less than 20% can not be saved

high strength of pellets in case of reestablishment due to strong waking matits)

In order to maintain high strength in the reduction of pellets containing re-ITit within the claimed limits, it is necessary; flow / 10-shaped slag bond Glass is formed from a sufficiently liquid-fluid melt and has a relatively high initial onset temperature of reduction (700-800 ° C). This okagish with a glass-like linkage is restored at t 709–800 ° С, when the link is softened at W o, and the stress relaxes —— Cooperosity between the mass fractions of a /. flowed is determined by the condition of the mar4. , shielding heme- iinn i-h. g-glass and selected excepi MO- - | 1no.

G, .1gch t.gnah hematite to c; j "poo less

) kO mchost0 last numbered

  atyshg (hematite content approaching m / 60 / O limit exceeds

...

The days of obtaining pellets with a large amount of mr pas i rely on high firing temperatures or an increase in empty

org, -. in concentrate. The restoration of their losses is sharply reduced.

Hpii ratio of hemagitis to cheshu bolee

  soda kan glass when the amount of hemapa is lowering to the lower limit

1C%) below 9%. This is possible at low temperatures and low temperatures.

 P - .. 1-,: gpe rasplvva However, the ocats,, and, PSL.11S1 nme without the insignificant liquid-tipped situation, are not strong and strong

destroyed upon restoration.

The method is carried out as follows.

The components of the charge (iron ore concentrate, flux, binder) are metered to obtain pellets of a given basicity, clumped and subjected to drying, high-temperature calcination at t 1200-1380 ° C and cooling by known methods.

Changes in the content of hematite, magnetite and glass in the pellets are achieved by changing the temperatures, heating rates and oxygen concentrations in the process zones or by mixing in a certain proportion the magnetite and hematite concentrates.

The developed pellets were obtained from two types of concentrates: Kachkanar titanium-magnetite and iron ore concentrate from the West Karazhal deposit, the latter obtained by gravity-magnetic ore dressing and contains hematite and magnetite (H0%) fractions.

PRI me R 1. The mixture for Kakkanar pellets was dosed out of titanium-magnetite concentrate - 91.2%, limestone - 7.8%, bentonite -1.0%.

This mixture provided pellets with a basicity of 1.25 units. and total 59.0%. The components were mixed, lined up to 8.5–9.0% and pelletized in a laboratory drum pelletizer. The firing was carried out in a laboratory agglochash, placing the pellets with a layer of 300 mm in a probe with a diameter of 100 mm from heat-resistant wires, by pumping natural gas into the mixture of air and gels, cooling was carried out with cooled products of burning natural gas, which were obtained in a false bowl, containing

0 pellets.

The presence of refractory oxides of magnesium and titanium in Kachkanar pellets made it possible to burn the upper part of the layer at 1350–1370 ° С, making it possible to regulate

5, the ratio of ore and slag minerals by oxidizing magnetite during heating and dissociation of hematite during firing. In the lower part of the layer, the maximum burning temperature was limited by the resistance of the grate floor of the firing carts and did not exceed 1200-1250 ° C. The content of the melt in the pellets is not enough to form a large amount of glass and shielding the ore grains,

5 in connection with this, the heat treatment mode was selected in such a way that the oxidizing atmosphere was replaced with a weak oxidative one at temperatures of the lower layer of 600 ° C and heating rates of 70-100 ° C / min.

0 Under these conditions, oxidation is slightly developed and is not strictly zonal in nature. A weakly oxidizing atmosphere (2-4% 02) during firing and cooling allows maintaining up to 50% of magnetite with a minimum content of glass and obtaining pellets weakly deteriorating during reduction.

Example. The mixture of pellets from concentrates West Karazhal

0 contained 88-90% concentrate, 8-10% limestone and 1% bentonite. This mixture provided pellets with a basicity of 0.8 units. and total 57%. The conditions for their preparation and heat treatment did not differ from

5 described above. The absence of refractory oxides in the West Karazhal concentrates and a significant amount of silica (up to 8%) do not allow pellets to be obtained at high temperatures and to dissociate hematite. Therefore

adjustment of the phase ratio was carried out by mixing magnetite with the hematite fraction. In order to preserve mgnite, roasting was carried out in an atmosphere with low oxygen content.

The compositions, metallurgical properties and conditions for obtaining pellets represent the i3 table. 1 and 2. In experiments 1–12 and 17, it was used as an alc Kakkanersky concentrate, and in rJsNfc 13–1 o and 18 was a concentrate of the West Karazhal deposit.

Comparison of the properties of the proposed okata; (her (experiments 2-6 and 14, 16) with the prototype; epim "- 1 13) shows that they have more lHL.uyu strength in the original G. OSTU. im and Bt, tm ayu-s. by degree, with: i-; and P; .. socr; agyue; .g; gsh. And is. h-zstnue okatysh- oh; -ehdeny overheated pz.pm, and gredl "lsmus. -.orods.oderkchsh (" m / gymovymi-1. -vj-.l. that significantly / darrh & Olop 0 –r; (swarm: csdstvz. In og-te / containing, not hect-tsita was pih (20%), and Ms is hyetkgch higher (60% j, tsm nnogo ppe- In h-echestone of the refrigerant and a used purified nitrogen. In spite of this propriety of such pellets, the NRM is proposed. An increase in the concentration of hemegite saerh (magnetite below 20%) leads to a burning sensation of burning and reprocessing (experiments B and 16). From experiments 9 and 0 it follows that the exit is beyond s proposed ogkoshenm hematite to stechlu leads to either reduce the strength of the reduction (Experiment 9) or to reduce recoverability (experiment 10).

From experiments 11 and 12 it follows that the decrease in the amount of glass below the limit. Limits leads to increased destruction of the pellets at low temperatures. and the increase - to reduce POP,.

Thus, the use of the proposed pellets instead of the known pules makes it possible to obtain an effect in the blast furnace by increasing the strength and the concomitant reduction of fines during the round.

Formula v sb. G e nl C: yyusopann chelezor -dny s-gat .-- sh, sodrkhaschi 1 nazhit, hematite, glass, and li-tal / .ic w / 1koucho link, characterized in that, in order to increase its strength, after roasting and simplifying its production without reducing its strength during recovery, it contains the ingredients in the following ratio, wt%:

Hematite30-60 Mdgnetit20-50 Steklo9-20 Crystalline slag bondElkal

and the ratio of the mass fraction of hemotitis

to glass is 3.0-3.3.

5,160,020,019,30,73,13,08,024,0

5,060,020,018,02,03,32,88,025,1

14,530,050,09,011,03,32,48,024,0

18,020,060,06,014,03,31,98,023,5

VHO / T - 70 ° C / min;

t "c - I360-C; Of - 4.5Z;

0 ° - 6Z

vHOrp - 80 ° C / min;

trf- 1340eC, of - 5.0Z;

 7.5Z

vMarf - 120 C / min;

tojr- 1280 ° C; of - 3.0

0 "A 5.0

  150 ° C / min;

Jf. oiS4

(purified nitrogen)

Claims (3)

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