SU1027232A1 - Method for producing master alloy - Google Patents

Abstract

1. A METHOD FOR PREPARING LIGATURES containing rare earth metals, including penetration of ferrosilicon with rare earth metals and calcium oxides, draining slag and metal, characterized in that, in order to reduce consumption, materials and improve the quality of the master alloy, the slag surface is loaded lime in the amount of 20-50 by weight of slag, then metal is drained, then ferrosilicium is loaded onto the remaining slag in the furnace and smelted, then the resulting slag is drained, after which the remaining metal is loaded into the furnace rare earth metal oxides and flux and smelt them. 2. The method according to claim 1, from l and h, and also with the fact that ferrosilicon is loaded in the amount of 65-95% of the mass of slag remaining in the furnace. 3. The method according to claim 1, about tl ICH and y (L y and I with the fact that the oxides of rare: milling metals load in the amount of 20-40% by weight of the metal remaining in the furnace.

Description

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ISD The invention relates to metallurgy (and, in particular, to methods for the half-mite of ligatures containing rare-earth metals. A method is known for producing ligate containing rare earth metals (REM) f by aluminothermic reduction of REM in the presence of silicon 1/1. The disadvantages of this method are include low recovery of rare-earth metals in the ligature, the presence of aluminum in ligatures (, 3–9), therefore, they cannot be used to process cast iron and a number of steel grades. The closest to the proposed technical essence and reach My result is a method for preparing a ligature containing rare earth metals, including the melting of components of a mixture containing lime, one or several REM oxides, and silicon (elemental or in the form of ferrosilicon). The melting of the mixture is carried out at 14501700 ° G. Then it is drained slag and f2 alloy. However, for a known method, an increased consumption of materials is due to the high content of rare-earth metals in slag. Oxides of rare-earth metals (R OJ are formed with silica - SIO, earth CLO-SiO /, silicates. When appearing in l. 11 | iiiMDjicnKin O SfO / 2 dissociation as a result of the reduction of REM by silicon and the presence of excess CLOd oxides inevitably leads to the formation of REM silicates, which are very strong compounds, as well as a decrease in the activity of REM oxides. In addition, the concentration of impurities in the master alloy is observed. (P, S, C) due to their absorption in the smelting of the master alloy. The aim of the invention is to reduce the 1st consumption of materials for smelting ligatures and to improve the quality of ligatures. This goal is achieved by the method of producing a master alloy containing rare earth metals, including the penetration of ferrosilicon with rare earth oxides of metal and calcium, slag plating and metal onto the slag surface, before plum metal is loaded lime in a quantity of 20-50% by weight the slag is then poured out by metalll, after which the slag is charged with ferrosilicon and melted into the furnace, then the slag formed is drained, after which the rare earth metals and the flux are charged to the metal remaining in the furnace and melted x .. Ferrosilicon is charged in an amount of 65-95 by weight of the slag remaining in the furnace. Oxides of rare-earth metals are loaded in an amount of 2Q-kQ% by weight of the metal remaining in the furnace. The process is carried out as follows. Ferrosilicon SFBSb5, FS75, FSEO), lime (not less than 90 CaO), rare earth oxide concentrate (90-98 are smelted into an electric arc furnace. The amount of silicon specified with ferrosilicon corresponds to the CzO / 51 1.6 ratio. Silicon ferrosilicon reacts with by oxides of rare-earth metals, reducing them by the reaction of 2 2CaO Si02 (1) The metal contains 35-40% rare-earth metals, 3-5 Ca, SI, the rest is iron and impurities. The resulting slag contains 10-20% oxides of rare-earth metals, 55-45% CaO, 27-30% 5102. According to X-ray structural analysis, the basis of the slag is -jp 2 CaO-S 02 Before the metal was released to the surface and lime is loaded in an amount of 20-50% by weight of slag. This technique allows the slag to thicken due to an increase in its melting temperature with an increase in the CaO: O ratio to 3.2-4.0. Then the metal is drained, for which the tap hole is cut. at the metal level. At the same time, the slag in the thickened state remains in the furnace bath. At the top of the slag remaining in the furnace, ferrosilicon is loaded. At the same time, calcium and rare-earth metals are recovered from the slag by the reaction RA03 + CaO + CSi RSij CaSio + (2 4-2,5) CaO-Si02 (2) The resulting metal contains 7-17% REM, 6-15% Ca, 50-65% Si, the rest is iron, and in the slag oxides of REM, 60-65% CaO, 30-40% Si02. The amount of loaded ferrosilicon is 65-95% of the mass of slag left in the furnace. . The slag is drained from the furnace by the slope of the bath or through the upper vent hole. The metal is loaded with a concentrate of rare earth oxides with fluorspar and molten steel. At this, interaction occurs by reaction. CaS 2 CaOvSIOgO Calcium removes impurities of sulfur and phosphorus in the form of sulfides and phosphides into the slag. In metal, the increase in the content of rare-earth metals to 27-50 is observed. The metal is drained from the furnace and poured into molds. Further operations are repeated. The reduction in the specific consumption of materials is achieved due to the high degree of reduction of rare-earth metals in the metal. If the amount of lime is less than 20 of the mass of slag, then slag thickening n occurs and it leaves the furnace when the metal is released. In addition, conditions are not created for the complete recovery of REM from slag due to calcium non-saturation of the alloy. When the amount of lime is increased by more than 50% ot of the slag mass, the latter has an increased viscosity, which makes the reduction processes difficult. In this case, the recovery of rare-earth metals is insufficiently complete, and the alloy obtained at this stage contains more than 15 calcium. If the amount of ferrosilicon loaded onto the surface of the shpak remaining in the furnace is less than 65% of its mass, REM is not fully restored to the alloy. Increasing the amount of ferrosilicon more than 95% of the mass of slag causes an unreasonably high consumption of charge materials. If the amount of oxides of rare-earth metals being loaded onto the surface of the metal remaining in the furnace, less than 20% of its mass, the resulting metal has a low concentration of rare-earth metals. With an increase in the amount of oxides of rare-earth metals more than 0% by weight of the metal, the recovery of rare-earth metals in the alloy proceeds insufficiently. Example. Smelting ligatures) are conducted in an electric arc furnace with a transformer with a capacity of 100 kV-A. When smelting is carried out by a known method, 135 kg of lime, 77 kg of ferrosilicon FS75, 97 kg of a concentrate of REM oxides, 22 kg of fluorspar are loaded into the furnace. After melting, the metal and slag are poured into the set; According to the proposed method, 135 kg of lime, 77 kg 32 .4 FS ferrosilicon 75.97 kg of the concentration of REM oxides, 22 kg of fluorspar are loaded into the furnace. After the charge has been melted, lime is fed to the melt in amounts of 20% of the calculated slag mass (experiment 1, stage M), then metal is released into the mold, and then ferrosilicon and fluorspar are loaded into the slag remaining in the furnace (experiment 1 stage III), melt and slag is poured. A mixture of the concentrate of rare-earth metals and fluorspar (stage 1 experiment) is loaded onto the remaining metal in the furnace, smelted and the metal is released. In Trial 2, the amount of lime used to thicken the metal is 30% by weight of slag, in Trial 3-50%. Experiments 2 and 3 were carried out similarly to experiment 1. The results of the experiments are listed in the table. The ratio of the mass of the slag (Rshl) to the mass of the metal () is publicly known-. According to the method and stage I of the proposed options is 1.1. This makes it possible to calculate the mass of metal and slag at stage 1 of each option: where Rsc is the mass of the charge loaded at stage I of the process. The mass of the metal formed after the melting of the charge given in stage 111 is almost equal to the mass of ferrosilicon given in stage III (PFC). Therefore, the mass of slag discharged in stage III is equal to where PUJ is the mass of charge charged at 111 stages process. The ratio of the mass of slag discharged in stage III to the mass of metal produced in stage IV is for variants 1, 2 and 3, respectively, 1.27; 0.98; 1.07.

In t {1blice, the weight of the metal is also given in terms of 1 base ton of the master alloy (30% REM) and the unit cost of charge materials in terms of 1 base ton of the master alloy (30% REM) .5

stage IV. In melted melt at stage I; process, the content of P, S and C, as in the well-known, and is respectively 0.015 and 0.065%. Due to better reducing conditions at the subsequent stages of the process (excess of reducing agent) and higher content of silicon in the final metal ts, the content of impurities decreases by

2535% and is, respectively, 0.011, 0.0035 and 0.045% therefore the quality of the ligature obtained in the IV process is higher than that of the extruded material.

The implementation of the proposed method in comparison with the known makes it possible to increase the extraction of rare-earth metals and the ligature, by 1 base tonne, C30% REM ligature consumption), by 17 (250 kg electrolyergy concentration) of the concentrate of REM oxides. based on 1 base ton of master alloy, taking into account the change in consumption of the remaining components of the charge will be 460-660 rubles

Known479,603 ny 840.

1.41

160,6

Claims (3)

1. METHOD FOR PRODUCING A LIGATURE containing rare-earth metals, including smelting ferrosilicon with oxides of rare-earth metals and calcium, draining slag and metal, characterized in that, in order to reduce consumption, materials and improve the quality of the ligature, they load onto the surface of the slag before draining the metal lime in an amount of 20-50% by weight of the slag, then the metal is drained, after which ferrosilicon is loaded on the slag remaining in the furnace and melted, then the resulting slag is drained, after which the oxide is loaded on the metal remaining in the furnace s rare earth metals and flux and melt them .. 2. The method according to claim 1, with the fact that ferrosilicon is charged in the amount of 65-95% of the weight of slag remaining in the furnace. 3. The method according to claim 1, about t and h a tout and Y with the fact that the oxides of rare earth metals are loaded in an amount of 20-40% by weight of the metal remaining in the furnace. SU 1027232. 1 1027232