Method for smelting base material of low phosphorous stainless steel by using low-grade limonite containing nickel-chromium

Abstract

A smelting method of low-P stainless steel base using low-grade ironstone containing Ni and Cr comprises the following steps: (1) pre-treating low-grade ironstone containing Ni and Cr to obtain ore powder and lump ore with different grain sizes, producing sintered ore from the pre-treated ore powder and lump ore with addition of fuel and flux; (2) mixing dust, recycled sintered ore, ore powder, binder and reducer, and producing cold pellets and / or pellets containing carbon through pressing at a high pressure; (3) drying the pellets containing carbon and feeding them into a rotary hearth furnace to obtain pre-reduced pellets; (4) smelting thesintered ore with fuel, flux, auxiliary materials, and one or more selected from the group consisting of lump ore, cold pellets, pellets containing carbon and pre-reduced pellets in blast furnace to obtain alloyed iron and / or molten iron containing Ni and Cr; (5) producing clean liquid stainless steel base from the alloyed iron and / or molten iron containing Ni and Cr, and one or more selected from the group consisting of the cold pellets, pellets containing carbon and pre-reduced pellets in electric furnace or converter, wherein the stainless steel base could be fed into furnace directly for steel production; (6) casting the liquid low-P stainless steel base by continuous caster into solid stainless steel base which could be fed into furnace directly for steel production. The method for manufacturing low-P stainless steel base has a low cost, low contamination to environment, high recovery ratio of alloying elements, and few harmful elements, and the method is rich in raw materials.

Description

technical field [0001] The invention relates to a method for smelting a low-phosphorus stainless steel base material by using low-grade limonite containing nickel and chromium, which belongs to blast furnace, electric furnace and converter smelting processes. Background technique: [0002] At present, in the stainless steel smelting process, its raw materials are mainly composed of: blast furnace molten iron + clean stainless steel return steel + high-carbon ferrochrome + high-purity ferronickel, or clean stainless steel return steel + common scrap steel + high-carbon ferrochrome + high-purity nickel Iron is mainly smelted in electric furnaces or converters. With the widespread application of stainless steel, the output has increased significantly year by year, resulting in a shortage of nickel metal, so the price of nickel has skyrocketed. However, the production of high-carbon ferrochromium and high-purity ferronickel by conventional methods has high process costs, complic...

AI Technical Summary

Problems solved by technology

With the widespread application of stainless steel, the output has increased significantly year by year, resulting in a shortage of nickel metal, so the price of nickel has skyrocketed. However, the production of high-carbon ferrochromium and high-purity ferronickel by conventional methods has high process costs, complicated production processes, and low output. Low pollution, serious pollution, consume a lot of energy, and the price is high, and in the subsequent smelting process, it needs to be diluted into stainless steel, resulting in greater waste of energy and manpower

Now some enterprises have switched to non-pure nickel raw materials (mainly nickel, chromium pig iron or ferronickel) to smelt stainless steel, but these nickel and chromium pig iron mainly use 300m 3 The production of the following small blast furnaces has serious environmental pollution, and the nickel and chromium pig iron contains high impurities such as phosphorus and sulfur. Usually, the dilution method is used to add clean stainless steel back to the steel to reduce the phosphorus and sulfur content in the finished product, but at the same time reduce The content of alloying elements such as nickel and chromium is reduced, which brings difficulties to subsequent stainless steel production operations

The low-grade limonite containing nickel and chromium is rich in resources and low in price, but the iron content in this ore is low, the nickel content is low, the chromium content is high, the composition is complex, and there are many gangues, resulting in a large amount of slag in blast furnace smelting, and the viscosity of slag iron Large, it is difficult to smelt with the existing conventional technology