RU2016100C1 - Method of lumping metallurgical raw material - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: method comprises steps of mixing components of a charge with a strengthening additive in a mixing drum, moistening, lumping and sintering them in a sintering machine; using as the strengthening additive kimberlyte, had been disintegrated beforehand, with diamonds had been removed out of it. That increases mechanical strength of the agglomerate and its resistance at reduction heat treatment of pellets. EFFECT: enhanced strength of agglomerate. 1 cl, 3 dwg

Description

 The invention relates to metallurgy, and more specifically to the preparation of raw materials for metallurgical processing.

 Numerous methods are known for producing agglomerate and pellets using hardening additives and, in particular, olivine. It has been established that the use of olivine additives during agglomeration and roasting of pellets leads to an improvement in the metallurgical properties of the agglomerate and pellets, including an increase in their strength properties (Metal Bulletin Monthly, 1983, No. 147, p. 53. ..54).

The closest in technical essence and the achieved result method selected as a prototype is a method of sintering ores and concentrates and producing pellets containing olivine by adding olivine-containing material to the iron ore charge. The process of agglomeration was carried out at a temperature reaching layer 1316 ... 1482 ^{° C,} and pellets are calcined at a temperature of 1204 ... 1374 ^{° C,} wherein the olivine content in the charge is 0.5 ... 10% (wt.) (No. N 4518428 USA, 05/07/1984, N 582929, published on 05.21.1985, class C 21 B 5/04, class 75/257).

 The disadvantage of this method is the need to create special industries for the extraction of olivine and olivine-containing rocks, as well as significant energy costs for grinding them to a particle size of 0. ..3 mm, suitable for use when firing pellets and agglomeration. The cost of grinding rocks containing olivine is 18 ... 20 kWh / t (Bond F.C. Work Index Tabulated-Mining Engineering-5 (1953) 3, p. 315, 316). Another disadvantage of this method is that it provides for the use of olivine as a reinforcing additive, and meanwhile there are reinforcing additives that have a stronger effect on the strength properties of the agglomerate (pellets).

 The aim of the invention is to reduce the energy costs of grinding additives, increasing the mechanical strength of the agglomerate (pellets), as well as strength during heat-reduction treatment.

 The goal is achieved by the fact that in the known method of sintering iron ore raw materials, including mixing the components of the charge with a hardening additive in a mixing drum, moistening, pelletizing and sintering (firing) on an agglomeration (firing) machine, pre-ground kimberlite is introduced as a hardening additive, from which it is extracted diamonds.

 Comparative analysis with the prototype allows us to conclude that as a reinforcing additive in the present method, instead of olivine, it is proposed to use pre-ground kimberlite from which diamonds are extracted. These differences allow us to conclude that the claimed technical solution meets the criterion of "novelty." Signs that distinguish the claimed technical solution from the prototype are not identified in other technical solutions when studying this and related areas of technology and, therefore, provide the claimed technical solutions with the criterion of "significant differences".

Kimberlite (another name - "blue clay") is a rock, which is a weathering of olivine. When weathering olivine, the following chemical reactions occur:
(Mg, Fe) ₂ SO ₄ + H ₂ O + CO ₂ -> (Mg, Fe) CO ₃ + Fe ₃ O ₄ + Mg ₆ [Si ₄ O ₁₀ ] (OH) ₈
Mg ₆ [Si ₄ O ₁₀ ] (OH) ₈ + CO ₂ + H ₂ O -> MgCO ₃ + SiO ₂ ˙ and H ₂ O
Thus, cumberlite contains the following minerals: (Mg, Fe) CO ₃ (brinerite, other names - mesatite, siderolesite), Fe ₃ O ₄ (magnetite), Mg ₆ [Si ₄ O ₁₀ ] (OH) ₈ (serpentine), MgCO ₃ (magnesite), SiO ₂ H ₂ O (opal), as well as olivine residues - (Mg, Fe) ₂ SiO ₄ .

 In the earth's crust, kimberlite is found in the form of kimberlite pipes and is the main rock containing diamonds. The finely ground kimberlite (to a particle size of less than 1.0 mm) from which diamonds are extracted is a by-product of the diamond mining industry and must be disposed of. The average energy consumption for grinding kimberlite is 9.66 kWh / t and, unlike olivine, it does not belong to very strong rocks (according to M. M. Protodyakonov), but to rocks with an average degree of strength. (Bond F. C. Work Index Tabulated.-Mining) 5 (1953) 3, P. 315, 316). The use of kimberlite in sintering production does not require its additional grinding, since the size to which it is crushed during diamond mining (0. ... .1.0 mm) is quite sufficient for use in sintering production.

EXAMPLE 1. At a sintering unit of the cup type, sintering of sinter batches containing Olenegorsk and Kovdor iron ore concentrates (in a ratio of 55:45), coke breeze 5% (by weight of the charge), and limestone (for a given basicity of CaO / SiO) were sintered ₂ , 1,6), a return of 35% (by weight of the charge), as well as a hardening additive. Each series included three sintering.

In the first series, sintering was carried out without additives, and in the second series, olivine (Mg, Fe) ₂ SiO ₄ , preliminarily ground to a particle size of 0 ... 1.0 mm, was used as an additive. In the third series, kimberlite from kimberlite pipes of the Kholmogorsky diamond deposit (Arkhangelsk region. Russian Federation), previously crushed to a particle size of 0 ... 1.0 mm, was introduced as a strengthening additive. This corresponds to the particle size to which kimberlite is ground to completely recover the diamonds. Additional grinding to smaller fractions is not required when using kimberlite during agglomeration. Consumption of reinforcing additives was 2% (by weight of the mixture).

 The result of studying the strength properties of the agglomerate are given in table. 1. The mechanical impact strength of the sinter was determined by the yield of the +5 mm fraction after testing in a standard drum according to GOST 15137-77. The mechanical abrasion resistance of the agglomerate was determined by the yield of the 0 ... 0.5 mm fraction after testing in a standard drum according to GOST 15137-77. The strength of the agglomerate during heat-reduction treatment (hot strength was determined by the yield of the +5 mm fraction after testing on the MISIS design installation according to the method described in the reference book (E.F. Wegman, Brief reference book of a domain manager. -M .: Metallurgy, 1981. - p. 248.).

 From the data table. Figure 1 shows that the introduction of crushed kimberlite, from which diamonds were extracted, instead of olivine, makes it possible to increase both the mechanical impact strength of the agglomerate and the strength of the agglomerate during heat-reduction treatment (the mechanical strength of the agglomerate against abrasion remained practically unchanged).

PRI me R 2. At the Lebedinsky mining and processing plant tested the technology of firing pellets from Lebedinsky concentrate containing 4.7% SiO ₂ , with the addition of olivine and pre-crushed kimberlite from which diamonds are extracted. In the control series, a charge 1 was used, containing, along with the magnetite concentrate of Lebedinsky GOK, also 1.0 bentonite, 5.0% limestone and 2.0% olivine. In the experimental (experimental) series, charge 2 was used, which differed from charge 1 in that 2.0% kimberlite was used in it instead of olivine. The charge was kneaded in a pan pelletizer with a diameter of 1000 m with an angle of inclination ^of 47 and a rotation speed of 15 rev / min.

 After pelletizing the charges, the raw pellets were tested for strength when dropped from a height of 300 mm onto a steel plate and for compression (STP 205-03). The compressive strength of the pellets with the addition of kimberlite was 16.0 N / pellet (raw) and 56.1 N / pellet (after drying), and the control - 13.9 N / pellet and 52.8 N / pellet, respectively.

Pellets were fired in probes (12 kg each) on an OK-306 firing machine according to the regime: Drying 1 65 ^о С, Drying 2 385 ^о С, Heating 710 ... 730 ^о С, Calcination 1180 ... 1240 ^о С, Recovery 750 ... 890 ^о С, Cooling 1 700 ^о С, Cooling 2 270 ^о С.

 The speed of the tape is 2.2 m / min; the layer height is 480 mm;

 After firing, the samplers with pellets were disassembled into layers, after which the compressive strength of the calcined pellets was determined using a P-05 tensile testing machine (GOST 24765-81). Data on the cold strength of the pellets are presented in table. 2.

 An analysis of the data on the cold strength of the pellets shows that the strength of the pellets in the experimental batch practically does not differ in value from the strength of the control pellets, but the spread in the values of the cold strength in the layers for pellets with kimberlite is much lower than for pellets with olivines.

 Calcined pellets were tested for strength in the process of heat recovery in a rotating drum according to GOST 19575-74. Data on the strength properties of pellets during recovery are presented in table. 3.

 An analysis of the results of testing pellets during recovery showed that for pellets with kimberlite added, the yield of the 0-0.5 mm fraction decreased by 3 ... 5 times compared to the control pellets, the yield of the 5 .... 10 mm fraction decreased by 13 .. .26 times, the yield of the +10 mm fraction increased 11 ... 14 times.

Sintered pellets were recovered ^at 800 ° C (hydrogen flow rate of 1.5 l / min) to determine hot strength. Hot strength (minimum strength in the process of heat recovery) was: for pellets with the addition of kimberlite - 400 kN / pellet, for control pellets with the addition of olivine - 260 kN / pellet.

 Thus, the experiments to determine the strength properties of the pellets showed that the pellets with the addition of kimberlite have greater strength during recovery compared with the pellets of the control series.

 Thus, the use of pre-crushed kimberlite as a hardening additive for sintering and roasting pellets can not only reduce the energy costs of grinding the additive, but also increase the mechanical strength and strength during heat-reduction treatment of the agglomerated raw materials, which, in turn, will allow to improve the performance of blast furnace smelting, since the removal of 1% fines from the 0 ... 5 mm fraction from iron ore raw materials allows to increase the productivity of the blast furnace by 1.0% and reduce the consumption of ca 0.5% (rel.).

Claims (1)

 METHOD OF TEXTURING METALLURGICAL RAW MATERIALS, including mixing the charge components with a hardening additive in a mixing drum, moistening, pelletizing and sintering (firing) on an agglomeration (firing) machine, characterized in that, in order to reduce the energy costs of grinding the additive, increase mechanical strength during recovery -thermal processing of agglomerate (pellets), as a reinforcing additive, pre-crushed kimberlite is used, from which diamonds are extracted.

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