RU2355794C1 - Depletion method of converter slags of nickel-cobalt manufacturing - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy of nickel and cobalt, particularly to depletion method of converter slag of nickel-cobalt manufacturing with extraction of nickel and cobalt. Method includes pouring of molten slag into heated aggregate, introduction into melt of pyrite, heating; melt settling with forming of sulfide mass, containing nickel and cobalt. Then it is implemented discharge, beading and utilisation of depleted slag. Additionally pyrite into melt is introduced in mixture with quartz. Quartz weight in mixture is from 3 up to 10% to weight of depleted slag, and weight of pyrite - 5 up to 10 times exceeding weight sum of nickel and cobalt, attended in depleted slag in oxidised form. Heating is implemented at the temperature from 1200 up to 1350°C. Melt settling before discharge of depleted slag is implemented from 20 - 30 minutes.

EFFECT: portion reduction of nickel and cobalt in dump converter slag .

2 cl, 1 ex

Description

The invention relates to the field of metallurgy of Nickel and cobalt.

A known method of depleting converter slag of nickel-cobalt production with the extraction of nickel and cobalt, including pouring molten slag into a heated unit, introducing pyrite and a reducing agent — coke into the melt, heating, settling the melt to form a sulfide mass containing nickel and cobalt, draining, granulating and disposal of lean slag (1).

The disadvantages of this method, adopted as a prototype, include the following:

- in the known method, the use of a reducing agent is mandatory (screened coke);

- the depletion process must be carried out at high temperatures (at least 1500 ° C). To achieve this temperature, depletion is carried out in electric furnaces.

The above factors determine a rather high cost of the process.

Nickel in the slag is present both in the oxidized form and in the form of sulfides, which are mechanically entangled in the slag. The presence of nickel sulfides in the slag leads to increased losses, reducing the overall recovery of Nickel.

The increased content of nickel sulfides in the slag discharged from the depletion unit is determined by the following factors:

- the formation of magnetite Fe ₃ O ₄ due to the insufficient amount of silicon dioxide, which leads to an increase in slag viscosity and, accordingly, an increase in mechanical losses of nickel;

- a relatively low temperature of depleted slag due to various technological violations (colder slag has a higher viscosity);

- insufficient time for sedimentation of depleted slag (small particles do not have time to enlarge and concentrate in the bottom).

The technical result of the invention is to reduce the mass fraction of nickel and cobalt in dump converter slags and, consequently, their losses.

The technical result is achieved by the fact that in a heated unit (for example, a converter equipped with a gas burner), liquid slag is poured and flux is introduced, which is a mixture of quartz (silicon dioxide) with pyrite (FeS ₂ ). The consumption of quartz in the mixture is from 3 to 10% by weight of depleted slag and is determined by the final silica content of 28 to 32%, and the consumption of pyrite in the flux mixture is from 5 to 10 sums of the mass of nickel and cobalt in depleted slag in oxidized form. Depletion is carried out at a temperature of from 1200 ° C to 1350 ° C.

The simultaneous presence of quartz and pyrite contributes to the destruction of magnetite, a shift to the right of the reaction:

5Fe ₃ O ₄ + FeS ₂ + 8SiO ₂ → 8 (2FeO · SiO ₂ ) + 2SO ₂

In this case, the physicochemical properties of the slag are changed, including the viscosity and melting temperature, which improves the conditions for the sedimentation of sulfide particles, always present in the slag, to the bottom of the melt.

In addition, the combined presence of quartz and pyrites provides a more complete reaction:

3NiO + 2FeS ₂ + SiO ₂ + 1,5O ₂ → Ni ₃ S ₂ + 2FeO · SiO ₂ + 2SO ₂

3CoO + 2FeS ₂ + SiO ₂ + 0,5O ₂ → 3CoS + 2FeO · SiO ₂ + SO ₂ ,

which contribute to the extraction of nickel and cobalt present in the slag in the oxidized form into a sulfide alloy. Due to this, losses of nickel and cobalt with slags are reduced.

Slag settling time 20-30 minutes. The settled slag is poured, granulated and disposed of.

Example

As a unit for depletion and sedimentation of slag, a 30-ton horizontal converter equipped with a gas flame burner of the DBV-225/51 type was used. Converter lining type-setting from chromomagnesite brick of the HPT-1,9,10,35 brands.

20 tons of converter slag with a nickel content of 0.25% in the form of oxides and 0.30% in the form of sulfides, cobalt of 0.30% in the form of oxide and 0.15% in the form of sulfide, silicon dioxide 22% were poured into an empty converter. A pyrite-quartz mixture was introduced into the melt at the rate of obtaining slag with a mass fraction of silicon dioxide of 28%. The mass of silicon dioxide in the bootable mixture was determined from equality.

2022: 100 + X = (20 + X) 28: 100,

where X is the amount of silica introduced with the mixture.

X = 1.66, i.e. for depletion, it is necessary to load silica in the form of a mixture with pyrite in the amount of 1.66 tons

The mass of pyrite (y) in the pyrite-quartz mixture was determined for our example

.

.

Thus, a mixture of pyrite with quartz in the ratio of 0.55 / 1.66 = 1: 3 in the amount of 1.66 + 0.55 = 2.21 tons or 11% of the mass of depleted slag was loaded onto 20 tons of depleted slag. Heating was carried out at a temperature of 1300 ° C, the melt was settled for 25 minutes, the slag was drained, granulated and disposed of.

The lean slag contained: nickel 0.15%, cobalt 0.18%. The resulting sulfide mass was left in the converter. The next portion of converter slag was poured onto it, containing 0.2% nickel in the form of oxides and 0.20% in the form of sulfides, 0.22% cobalt in the form of oxide and 0.12% in the form of sulfide, 24% silicon dioxide. The estimated amount of pyrite-quartz mixture with a ratio of 1: 3 was loaded onto slag. After termination of the reaction of the mixture with depleted slag and sludge for 25 minutes, the depleted slag with a total nickel content of 0.12%, cobalt 0.15% was poured and disposed of. The sulfide mass remained in the converter.

Thus, 80 tons of converter slag was depleted. The result is a sulfide mass in the amount of 2100 kg containing nickel 12.7% and cobalt 3%.

Nickel in sulfide form is absent in lean slag. The result is confirmed by phase analysis of slag.

Information sources

1. I.F. Khudyakov, A.I. Tikhonov, V.I. Deev, S.S. Naboychenko. Metallurgy of copper, nickel and cobalt, part II - Metallurgy, 1977, pp. 212-216.

Claims (2)

1. A method for depleting converter slags of nickel-cobalt production with the extraction of nickel and cobalt, including pouring molten slag into a heated unit, introducing pyrite into the melt, heating, settling the melt with the formation of a sulfide mass containing nickel and cobalt, draining, granulating and utilizing lean slag characterized in that pyrite is introduced into the melt mixed with quartz, the mass of quartz in the mixture being from 3 to 10% by weight of depleted slag, and the mass of pyrite is 5 to 10 times the sum of the masses of nickel and cobal and present in impoverish the slag in the oxidated form. 2. The method according to claim 1, characterized in that the heating is carried out at a temperature of from 1200 to 1350 ° C, the sedimentation of the melt before draining the lean slag lead from 20-30 minutes