SU926047A1 - Process for depleting slags from the copper and nickel production - Google Patents

Description

(5) METHOD OF LACKING SLAVES OF COPPER-NICKEL

PRODUCTION

, The invention relates to color metallurgy, in particular to the processes of depletion of copper-nickel slags. The closest to the proposed technical essence is the process of depletion of slags of copper-nickel production, including their restoration, for example, by ferrosilicon in an electric furnace 1. The disadvantage of the known method is a high consumption of ferrosilicon, which significantly increases the cost of slag depletion, and low resistance lining electric furnaces. This is due to the fact that the used ferrosilicon, containing about kS% silicon, has a higher density than slag (+ 5-5.0 g / cm versus 3f5, 0 g / cm slag). Moreover, the density of ferrosilicon increases rapidly with decreasing silicon content and enrichment with non-ferrous metals. Thus, by reducing the silicon content in ferrosilicon to 15–20%, its density increases to 6.5 g / cm. In this connection, a considerable part of silicon contained in ferrosilicon (up to 50) does not have time to react with slag oxides and sinks into matte, where it reacts with iron oxides dissolved in the matte, causes a significant increase in the matte temperature (by 80%). 120 C) and deteriorates the conditions of the furnace lining in a matte bath. In addition, the metallized ferrosilicon alloy with non-ferrous metals is practically insoluble in matte. Having a higher density, this alloy is lowered onto the bottom. chi, in the future does not have contact with the slag and gradually forms an accumulation on the furnace hearth. The purpose of the invention is to reduce the cost of both slag and increasing the durability of an electric furnace lining. The goal is achieved by using a mixture of ferrosilicon and solid carbonaceous fuel in the weight ratio of 1: (2-8) according to the copper-nickel slag depletion method. , and the process is carried out at 12001300 ° C. The feed to the furnace of this mixture makes it possible to significantly reduce the consumption of ferrosilicon (by more than 50% as compared with the known method without degrading the indicators of depletion) and, consequently, reduce the costs of the slag depletion. Reducing the consumption of ferrosilicon is provided by reducing the degree of its oxidation by oxygen in the atmosphere of the furnace. In addition, the reduction reactions of metal oxides of iron, cobalt, and nickel-silicon are accompanied by the release of a large amount of heat, while similar reactions with carbon are endothermic. Therefore, a mixture of ferrosilicon with a solid carbonaceous reducing agent makes it possible to improve the conditions for the reactions of reduction of metal oxides to carbon. In this case, ferrosilicon is an intensifier of metal reduction reactions by carbon. At the same time, this makes it possible to lower the temperature of the forming metallized phase and slag, and, consequently, to improve the working conditions of the electric furnace futher furnace. The ratio of ferrosilicon: solid carbonaceous reducing agent is determined by the silicon content in ferrosilicon and is maintained at a limit of 1: 2-1: 8, which corresponds to 0.080, 15 kg of silicon per 1 kg of the mixture. The upper limit (0.15) is used predominantly when using ferrosilicon containing 40–50th cream of g lower (0.08) when using ferrosilicon with 70–75% silicon. Industrial tests show that an increase in the silicon content in the oxide above (0.15) leads to the predominance of metal reduction reactions with silicon, an increase in the melt temperature and deterioration of the lining working conditions, and an increase in the cost of depletion. By reducing the silicon content in the mixture below 0.08, the depletion rate deteriorates. The process is carried out at a temperature of 1200-1300 ° C. Increasing the temperature over is impractical due to the deterioration of the working conditions of the furnace lining; when the temperature drops below 1200 ° C, the viscosity of the slag and the metal losses associated with it in the form of mechanical suspension of the alloy beads significantly increase. The proposed method provides a stable process of depletion at the temperature of the melt / -a lower than in the known method. It is advisable to introduce ferrosilicon with a silicon content of 50-75%, for example FS-75 or substandard ferrosilicon, containing 50-70% silicon. The latter has a lower cost than the brands and FS-75, and less deficiency. Due to the fact that the density of ferrosilicon decreases with increasing silicon content in it (FS-45-, 5-5.0 FS-75-3 3 g / cm), with the introduction of lighter ferrosilicon, the reduction zones of metal oxides with silicon and carbon. This creates favorable conditions for the use of excess heat, released during the course of the reduction of the reaction of oxides of silicon, to endothermic reactions involving carbon. The convergence of these zones allows you to create a more intense movement of hot slag relative to the fixed layer of the reducing agent and accelerate the course of carbon reduction reactions. In addition, the introduction of ferrosilicon richer in silicon can significantly increase the utilization rate of silicon for the reduction of metal oxides in slag. Thus, when the brand is supplied to a ferrosilicon furnace, the silicon utilization rate for the reduction of metal oxides in the slag does not exceed 50%, when FS-75 is supplied more than 75%, which significantly reduces the consumption of the latter without affecting the metal recovery indicators. The consumption of ferrosilicon is maintained within the range of 0.3-0.9% by weight of the depleted slag, which is respectively 0.01-0.05 kg of silicon per 1 kg of oxygen bound to the slag iron. An increase in the consumption of ferrosilicon over 0.9% leads to an over-metallization of the matte, an increase in its temperature and the formation of scaling on

hearth furnace. Reducing the flow rate below 0.3 from slag impairs the recovery of metals from slag.

. It is also advisable to crush the ferrosilicon before heating the mixture. The optimum grain size of ferrosilicon is 5.0-0.1 mm. When melted, coarser ferrosilation gives larger droplets of the melt, which quickly descend into the matte, carrying along a large part of the unreacted silicon in the slag; smaller, gives small drops that take a long time to settle the slag, and can cause a decrease in metal recovery. .

The main advantages of the proposed method in comparison with the known method are a reduction in the consumption of expensive ferrosilicon by about 50 without a decrease in the recovery rates of non-ferrous metals; the possibility of improving the working conditions of the lining of an electric furnace by reducing the temperature of the matte bath by 50-100 ° C; the possibility of using cheaper substandard ferrosilicon.

Example. 120. t of converter slag containing,% N1 0.87; Co 0.55; StOr.ii; Fe (jgyj.50;, load a mixture of anthracite shtyb and ferrosilicon, containing 75% silicon, in a weight ratio of 8: 1 in an amount of 3 tons.

Silicon consumption is 0.01t-0.020 kg per 1 kg of oxygen bound to slag iron. Additionally, matte is poured into the furnace in an amount of 20-30% by weight of slag, or sulphide materials (high-sulfur sulphide ore) 8 are loaded in an amount of 25-35% by weight of slag. In addition, 4-5 tons of quartz flux are loaded into the furnace. After 1.5 to 2 hours at 1200-1250 ° C, the slag is sent to a dump, rich in matte for conversion. Extraction of cobalt reaches 80-85%, nickel 95-98%.

Claims (1)

1. USSR author's certificate No. 717145, cl. From 22 to 7/0, 1978.