Iron alloy is a metal composed of one or more metals or non-metals and iron, for example: silicon manganese (FeMn65Si17) is an alloy of silicon (Si) and manganese (Mn). Ferroalloy is an important raw material for steelmaking and steel casting, which can change the physical and chemical properties of steel and the mechanical properties of castings. Industries such as machinery, national defense, precision manufacturing, and household appliances have higher and higher requirements for materials, and the requirements for ferroalloys are also increasing. higher.
Ferroalloy electric furnace is divided into reduction electric furnace and refining electric furnace. The reduction electric furnace uses carbon as the reducing agent to continuously produce ferroalloys; the refining electric furnace uses silicon as the reducing agent to intermittently produce low-carbon ferroalloys. At present, more than 70% of the world's ferroalloy products and calcium carbide are produced by reduction electric furnaces (submerged heat electric furnaces).
There are two types of electric furnaces: fully enclosed electric furnaces and semi-enclosed electric furnaces.
1. Flue gas characteristics of fully enclosed reduction electric furnace:
Fully enclosed electric furnace produces raw gas during smelting, high temperature, high CO concentration, high dust concentration, flammable and explosive, and the smoke is particularly thin and light, which is easy to spontaneously ignite.
1) The gas volume of the fully enclosed reduction electric furnace is small, and the furnace condition is stable;
2) Furnace gas temperature is 500-800°C higher (rear cooling device);
3) The dust concentration is high, and the dust content is 80-150g/m³ under standard conditions;
4) Flammable, explosive, light smoke and dust, containing corrosive gas;
5) The main components of furnace gas are CO (carbon monoxide) 76-85%, H2 (hydrogen) 5-10%, CH4 (methane) 0-5%, N2 (nitrogen) 4-8%, etc.
2. Characteristics of dust removal flue gas of semi-closed reduction electric furnace:
The semi-closed reduction electric furnace is artificially fed, with poor sealing and unstable furnace conditions.
1) The flue gas temperature is 160-340°C, and air cooling is generally used to cool down;
2) The dust concentration is 2-6g/m³, the dust particle size is fine, ≤2μm accounts for 38%, and 2-20μm accounts for 57%;
3) Dust absorbs moisture and deliquesces, spontaneously combusts, and has strong viscosity;
4) Contains corrosive gas and a small amount of unburned tar;
5) Flue gas components CO2 (carbon dioxide) 4%, N2 (nitrogen) 76%, H2O (water) 2%, O2 (oxygen) 12%, etc.;
6) When there are abnormal furnace conditions such as stinging fire and material collapse during production, the flue gas volume and flue gas temperature will suddenly rise.
The dust removal of the semi-enclosed reduction electric furnace adopts positive pressure reverse blowing bag dust removal and negative pressure pulse bag dust removal.
1) Positive pressure reverse air bag type dust removal process:
Semi-enclosed reduction electric furnace—U-shaped tube cooler—high temperature fan—cyclone separator—positive pressure reverse air bag filter
Positive pressure reverse blowing bag filter usually chooses texturized glass fiber woven filter material, and sometimes the surface needs to be laminated PTFE membrane.
2) Negative pressure pulse jet bag dust removal process
Fully enclosed reduction electric furnace - mechanical air cooler - pulse bag filter - high temperature induced draft fan - negative pressure pulse bag filter using P84 and ultra-fine glass fiber composite needle felt.
