Method for smelting magnesium and co-producing ferrochrome-containing liquid with ferrosilicon bath stair reduction silicothermic method

Abstract

The invention relates to a method for smelting magnesium and co-producing ferrochrome-containing liquid with a ferrosilicon bath stair reduction silicothermic method, belongs to the technical field of nonferrous magnesium metal extraction and also belongs to technical field of chromium-containing stainless steel and ferrochrome smelting of ferrous metallurgy. Ferrosilicon bath much higher in theoretical chemical demand quantity is used as a silicothermic reducing agent and carrier of chemical reaction, reaction interfacial area is increased and convective heat transfer and mass transfer abilities are strengthened to realize reinforcement of reduction process through intense stirring. After reduction is completed, magnesium smelting reduction slag is eliminated, excessive ferrosilicon is mixed with a new batch of magnesium ore to smelt magnesium until the concentration of ferrosilicon liquid is lower than that of lower silicon, and lower ferrosilicon liquid is mixed with chrome ore to carry out chromium reduction to obtain chromium-containing stainless steel mother liquid. The excessive ferrosilicon bath is respectively used for smelting magnesium and ferrochrome at high concentration and low concentration, ferrochrome raw material is completely utilized, the reaction efficiency is high, energy is saved, carbon, phosphorus and sulphur in the ferrochrome liquid are little, and the co-production cost of magnesium and stainless steel liquid is obviously reduced in comparison with sum of the production cost of magnesium and the production cost of stainless steel liquid.

Description

technical field [0001] The invention belongs to the technical field of non-ferrous metal magnesium extraction metallurgy, also belongs to the technical field of smelting chromium-containing stainless steel and ferrochrome alloy in ferrous metallurgy, and particularly relates to a method for co-producing chromium-containing ferroalloy liquid by silicothermal magnesium smelting. Background technique [0002] Magnesium and magnesium alloys are the lightest metal structural materials. They are used in transportation, electronic products, building materials, aerospace and other fields to bring energy-saving effects. They are known as "the third metal" and "the first metal of the 21st century Green Metallic Materials". Mineral resources of major metal materials such as steel and aluminum are gradually being exhausted, while metallic magnesium is very rich in mineral resources, and seawater contains even more abundant magnesium resources, which can be used by humans for thousands o...

AI Technical Summary

Problems solved by technology

[0014] 1. The reactant ferrosilicon and calcined white react chemically in the form of solid phase contact, the reaction rate is slow, and the reduction reaction cycle in a typical process is as long as 10 to 12 hours, which is inefficient;

[0015] 2. The flame is used for external heating, and the heat is gradually transferred from the outside of the reactor to the inside. The cycle is long, the heat energy loss is large, and the heat energy utilization rate is low. According to professional analysis, the heat energy utilization rate of a typical process is only about 20%;

[0016] 3. Because the external heating method limits the volume of the reactor, the inner diameter of a typical horizontal tank is within 400 mm, and the amount of material charged at one time is small. The output of raw magnesium in a single tank is only 20-30 kg for 10-12 hours at a time, and the floor area is large. , on-site management is difficult, and it is not easy to realize large-scale production and mechanized operations;

[0017] 4. Ferrosilicon containing 75% silicon is used as the reducing agent. Generally, the consumption per ton of magnesium ferrosilicon is 1.05 to 1.20 tons, that is, silicon far exceeds the theoretical consumption value and causes waste, and at the same time all iron elements are wasted;

[0018] 5. Horizontal tanks generally use expensive heat-resistant steel containing nickel and chromium, which consumes quickly and costs high;

[0019] 6. The smoke pollution is serious, the working environment is harsh, and the negative impact on the surrounding ecological environment is great;

[0020] 7. It requires manual loading, slag removal, and cleaning of crystalline magnesium, which is labor-intensive and difficult to achieve automated operations

But this process still has several deficiencies: the first is that ferrosilicon is still seriously excessive in excess of the theoretical consumption value, resulting in the waste of all remaining high-temperature iron elements and part of silicon elements

However, due to the high vacuum degree of the reaction system described in this patent, the magnesium vapor is directly condensed into solid crystalline magnesium, which is easy to block the vacuum system and cannot realize continuous production.

Chinese patent CN201010145505.9 proposes a method for smelting and reducing silicon to smelt magnesium by adding silicon and aluminum oxides to form a multi-element molten slag system, so that the reactants and products form ferrosilicon liquid and multi-element slag, both in liquid phase , to improve the reaction kinetics conditions, but in the three examples, the excess of silicon and iron causes a large waste of silicon and iron elements, even reaching half of the waste of silicon elements

[0024] Chinese patents CN201080000976, CN201010255097, and CN201010255111 provide methods and devices for smelting magnesium in vacuum circulation, so that ferrosilicon liquid and magnesium ore can be fully mixed, and the circulation flow under vacuum and normal pressure is realized through the dipping tube, and good reaction kinetics are obtained. conditions, and continuous slagging, but only provides supplementary silicon to the residual ferrosilicon after magnesium smelting, thus becoming a comprehensive utilization path for different silicon-containing ferroalloys, and has not yet fully utilized the chemical function of silicon as a high-quality metallurgical reducing agent

Usually in dolomite calcined white powder, the raw material for magnesium refining, the atomic ratio of calcium to magnesium is close to 1:1 or slightly higher than 1, and magnesium accounts for 23-25% of the mass of calcined white powder. Since the reduction rate of magnesium is usually about 80%, magnesium The amount of ore added is generally 6-6.5 tons per ton of magnesium, and more than 75% of ferrosilicon added per ton of magnesium is only 1.0-1.1 tons, so even if the furnace charge is completely melted, the amount of slag is 600% of the amount of molten metal, and the slag phase in the molten pool occupies The fluidity is far less than that of the molten metal-based molten pool, resulting in low efficiency of chemical reaction, heat transfer, and mass transfer in the molten pool

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