RU2389811C1 - Procedure for preparation of charge to melting for production of nickel matte out of oxidised nickel ore - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: procedure consists in drying crude ore, in separation ore into fractions +2 mm and -2 mm, in mixing small fractions of ore -2 mm with sulphidiser, flux and coke breeze and in briquetting. As flux there is added shale with 8.0-10.5 % weight of its contents in charge. Nickel sulphidiser containing 10-25 % wt of sulphur, not less, than 5 % wt of nickel and iron are introduced to charge as sulphidiser. Amount of sulphidiser added into charge is 20 % wt.

EFFECT: raised extraction of nickel into matte at simultaneous decrease of specific consumption of coke at melting briquettes out of oxidised nickel ore in shaft furnaces.

2 cl, 1 ex

Description

The invention relates to the field of non-ferrous metallurgy, in particular to the production of nickel matte in shaft furnaces.

A known method of processing oxidized nickel-containing ores [1], including pulping ore into pulp, washing ore pulp for at least 1 min, sorting the washed ore in a humid environment to separate at least a fine fraction using a screen with a mesh size between 80 μm and 3 mm to separate fine particles from granular particles so that no more than 10 wt.% fine fraction remains in the granular fraction, heavy-medium separation of the granular fraction at a separation density of 1.7-2.5 to obtain a light fraction and heavy fraction and extraction of light fraction, separated in the form of enriched ore.

The disadvantage of this method is the complex enrichment scheme using a large amount of water and special equipment for washing the ore and the difficulty of dividing wet clay materials on a screen.

A known method of preparing oxidized nickel ores for smelting [2], including mixing different types of ore (averaging their composition), sorting ore by size (screening), crushing large pieces of ore and gypsum, drying the ore in drying drums, mixing dried ore with a sulfidizer ( pyrite, gypsum), production of briquettes. In mine smelting of briquettes from oxidized nickel ores, coke consumption is 32-35%. The matte yield is 7-10% by weight of dry briquettes, while the nickel content in the matte is 13-15%.

The disadvantage of this method is the high consumption of coke per tonne of nickel produced in matte, especially when using ore with a high content of magnesium oxide.

The closest analogue is the method of preparing the charge for smelting for the production of matte from oxidized nickel ores, including drying the crude ore to a residual moisture content of less than 7%, screening the coarse fraction, separating the ore into fractions +2 mm and -2 mm, mixing the fine ore fraction with a sulfidizer and fluxing and briquetting [3].

The disadvantage is the high consumption of reducing agent - coke.

The objective of the invention is to reduce the specific consumption of coke when smelting briquettes from oxidized nickel ore in shaft furnaces, increasing the extraction of Nickel in matte.

This object is achieved in that in a method comprising drying raw ore, separating ore into fractions of +2 mm and -2 mm, mixing a small fraction of ore with a sulfidizer, flux and coke breeze and briquetting, according to the invention, shale is introduced as a flux when it is contained in the charge 8.0-10.5 wt.%, and as a sulfidizing agent - nickel sulfidizing agent containing 10-25 wt.% sulfur, not less than 5 wt.% nickel and iron.

Drying of oxidized nickel ore to a residual moisture content of less than 7% contributes to the effective subsequent separation of ore particles by size, and this allows to increase the nickel content in the ore and reduce the content of magnesium oxide. An increase in the nickel content in the ore helps to reduce the specific consumption of coke during mine smelting.

Separation of ore into coarse (+2 mm) and fine (-2 mm) fractions after drying makes it possible to efficiently separate particles of size less than 2 mm from large pieces of ore on conventional equipment. Due to the fact that nickel is concentrated in a fine fraction, its separation from ore allows increasing the total nickel content in the briquetting mixture.

Selective grinding of a large fraction of the ore allows nickel minerals to be separated into a separate phase, separated from non-metallic minerals and gangue.

An increase in the nickel content in the ore helps to reduce the specific consumption of coke during mine smelting.

The use of a sulfidizer of the specified composition can reduce the consumption of lumpy coke.

To obtain the sulfidizer used, any known methods can be used, including the method of mine smelting of oxidized nickel ores, OHP smelting in a flame furnace (open-hearth or reflective furnace), smelting in a liquid bath, etc.

The lower limit in the nickel sulfidizer (5%) is established taking into account the fact that with a lower nickel content, for example 4%, there is an extremely high yield of sulfidizer, and when it is used for subsequent processing of oxidized nickel ores to matte, the coke consumption increases significantly. and nickel recovery is 90.7% (versus 91.6% nickel recovery for the sulphidizing agent containing 5% nickel).

The lower limit for sulfur (10%) is established on the basis that alloys with a lower sulfur content have a high melting point (up to 1400 ° C), as a result of which coke consumption increases markedly. The upper limit of sulfur content in the sulfidizer (25%) was established experimentally and is dictated by the need for metallization of the sulfidizer in order to reduce coke consumption and sulfur emissions into the atmosphere during subsequent processing of oxidized nickel ores with the proposed nickel sulfidizer.

The introduction of shale as a flux in the charge allows to give it new properties, as a result of which the fusibility of the charge increases, the proportion of endothermic reactions decreases, the cost of the charge decreases due to the reduction in the consumption of expensive coke. The new properties of the charge are due to the structure of shale, which is an alternation of limestone, gypsum, calcium oxide with small impregnations of organic components - carbon and hydrogen, which play the role of a reducing agent and fuel in the charge. Component of slate - gypsum acts as a sulfidizer. The amount of sulfidizer in the charge decreases in proportion to the amount of sulfur contained in the shale.

Carbon and hydrogen introduced with shale can reduce the amount of coke introduced into the charge, taking into account the coke consumed in the endothermic decomposition of limestone. The lower limit of the shale content in the charge of 8.0 wt.% Is determined from the conditions of formation on the wall of the reactor and the deterioration of the lance. With a decrease in the shale content in the charge of less than 8.0%, there is no fire on the lance and lining is formed on the wall, and the lance freezes gradually.

The upper limit of the content of shale in the charge of 10.5 wt.% Due to the increased consumption of shale.

The properties of oil shale make it possible to carry out the complexity of its use (mineral and organic components) and increase the processability of the charge due to its fusibility, which leads to an increase in the productivity of the process.

An example of a specific implementation.

Oxidized nickel ore containing, wt.%: Fe ₂ O ₃ = 15.4; Ni = 1.42; CaO = 1.3; MgO = 19.6; SiO ₂ = 44.2; moisture = 27.5, dried in a drying drum to a residual moisture content of not more than 7%, was screened with a separation into fractions of +2 mm and -2 mm, a large fraction was selectively crushed and divided into two fractions on a pneumatic classifier: light (with a density of less than 2, 7 g / cm ³ ) and heavy (with a density of more than 2.7 g / cm ³ ), which was removed from the composition of the charge, and the light fraction and the -2 mm fraction were mixed, coke breeze was additionally introduced into the charge, shale in the amount of 9.5% and a sulfidizer in an amount of 20%. The mixture was briquetted. At the same time, shale is a fluxing-reducing additive, fuel and sulfidizing agent. During testing, during the observation of melting, coke was gradually removed from the charge. Coke consumption for galosh was reduced by up to 12.5 abs.% Of the mass of all coke fed to the smelting. In the course of research, samples of all smelting products were taken, and the condition of the tuyere belt was estimated using lances. Tests showed that during the test period, technological parameters did not deteriorate, despite a 2% increase in the content of SiO ₂ in the slag. In general, the introduction of shale into the smelting improves the performance of the process, for example, matte metallization during the test period increased by 6-12%, and an increase in metallization led to a decrease in non-ferrous metal losses with dump slag. Slag analysis confirms the reduction of nickel losses with dump slag from 0.164 to 0.15% while increasing the productivity of the furnace.

During the tests, the condition of the tuyere belt improved. The decrease in coke consumption is due to two reasons. Replacing calcareous flux (marble, limestone) with calcareous shale does not require coke for an endothermic reaction, decomposition of calcium carbonate, since shale itself has a calorific value. Thus, the introduction of shale in the mixture allows to achieve a double effect in reducing the proportion of coke in the mixture. The use of coke heat for reduction and smelting and the exclusion of coke heat for decomposition with the thermal effect of the combustion of combustible carbon of oil shale ensures a reduction in the operating costs of the charge due to the saving of expensive coke and improves the processability of the charge.

As a result of this preparation, the nickel content in the ore increased by up to 1.96%, the magnesium oxide content decreased by up to 18%. During testing, the parameters of the furnace and coke consumption were recorded. Stein and slag were discharged from the furnace.

An analysis of the above results shows that the use of the method of preparing the charge for smelting for the production of matte from oxidized nickel ores can reduce the specific consumption of coke in a shaft furnace.

Information sources

1. Application for patent of the Russian Federation No. 98115383/03 from 05.08.1998, publ. in BIPM 2000, No. 13.

2. Zeidler A. A. Metallurgy of copper and nickel. M .: GNTI for ferrous and non-ferrous metallurgy, 1958, p.245-279.

3. RF patent 2234546, publ. 08/20/2004.

Claims (2)

1. The method of preparing the mixture for smelting for the production of matte from oxidized nickel ores, including drying crude ore, dividing the ore into fractions +2 mm and -2 mm, mixing a small fraction of ore -2 mm with sulphidizer, flux and coke breeze and briquetting, characterized the fact that shale is introduced as a flux when it is contained in a charge of 8.0-10.5 wt.%, and as a sulfidizer, a nickel sulfidizer containing 10-25 wt.% sulfur, at least 5 wt.% nickel and iron . 2. The method according to claim 1, characterized in that the sulfidizer is introduced in an amount of 20 wt.% From the charge.