Ferromanganese smelting

Used as a deoxidizer and alloy additives in steelmaking, is the largest amount of ferroalloys. The manganese use for melting ferromanganese, general require ferromanganese content manganese from 30 to 40%, manganese and iron ratio is greater than 7, and phosphorus and Mn ratio is less than 0.003. Smelting manganese carbonate before the first block to be made by sintering after roasting. High phosphorus and iron ore is generally only used proper proportions or through the selective reduction of refining low iron phosphorus manganese-rich slag.

Carbon ferromanganese in international standard is content 75 to 80% of manganese, to adapt to the low grade manganese ore raw materials, china provisions manganese lower grades (electric furnace ferromanganese more than 65% of manganese, blast furnace ferromanganese manganese more than 50%). Carbon ferromanganese smelting blast furnace in the past, with the development of the electric power industry, electric furnace was gradually increased.

According to metal powder supplier, blast furnace smelting generally use less than 1000 m 3 blast furnace, equipment and production process is generally the same as the blast furnace. In the process of falling from the roof, the high prices of manganese oxide (MnO2, Mn2O3, Mn3O4) with increasing temperature, gradually restored to MnO by CO, but MnO only direct reduction into a metal by carbon at high temperatures, so smelting ferromanganese requires a higher temperature of the furnace hearth, this refining ferromanganese blast furnace using a high coke ratio (1600 kg / ton) and air temperature (1000  above). To reduce the manganese loss, the slag should be maintained high basicity (CaO/SiO2 greater than 1.3). Due to the coke rate high and low indirect reduction, yield refined ferromanganese blast furnace gas containing CO than the blast furnace, roof higher temperature (350 ). Oxygen enriched blast can increase the temperature of the hearth, lower coke rate, increase production, and due to the decrease in gas volume can reduce the roof temperature, a significant role in the improvement of ferromanganese smelting.

The reduction smelting of ferromanganese have flux method (also known as low the manganese slag law) and no flux method (high manganese slag) two kinds. Flux method principle is the same as blast-furnace process, just electricity instead of heating coke in blast furnace. Through add lime to form a high basicity slag (CaO/SiO2 1.3 to 1.6) to reduce the loss of manganese. Flux method smelting lime to form alkalinity is lower (CaO/SiO2 less than 1.0), with high manganese’s low iron low phosphorus manganese-rich slag. This method is less slag, reduce power consumption, and because of the lower slag temperature can reduce manganese evaporationloss, and the byproducts manganese-rich slag (25 to 40% manganese) can be used as raw material for smelting manganese silicon alloy to achieve a higher manganese recovery (90%).

Manganese silicon alloy use a closed or semi-closed reduction smelting furnace. Generally use containing silica, phosphorus, manganese or another with addition of silica as raw materials. Manganese-rich slag containing high silica is a good raw material for smelting manganese silicon alloy containing phosphorus. Smelting consumption generally about 3500 to 5000 kW • / ton. The furnace raw material first for pre-treatment, including whole, warm-up, pre-reduction and powder sintering, significant improved the electric furnace operation and technical economic indicators.

The high basicity slag can make the manganese reduced in the slag, reduce the manganese loss caused by the spoil. Charge preheating or loaded liquid manganese silicon alloy helps shorten the refining time and reduce power consumption. Medium and low carbon ferromanganese also through liquid silicon manganese alloy, manganese ore and lime melt mixing each other to produce.

Source:http://www.mhcmp.com