With the growing demand of steel in the market, there has been a heavy requirement of manganese alloys. This is one of the most probable reasons as to why the manganese industry is on the bloom. With the influx of new technology and optimal choice of raw material melting behavior, reaction mechanisms, and kinetics of silicon manganese has improved a lot.
Any standard proportion of silico manganese alloy contains 67 to 70 wt % of manganese, 17 to 20 wt % silicon, and 1.5 to 2 wt % carbon. They are normally produced from raw materials such as mixture of manganese ore, ferromanganese slag, quartz and fluxes that mostly include dolomite or calcite.
Silico manganese is smelted with dolomite or calcite to increase the slag fluidity and at the same time also help reducing manganese oxide content from the slag. The slag on the other hand ranges between 1573 K and 1653 K as per its composition. Scientifically speaking, increasing the temperature or the silica content in the slag and decreasing the (CaO+MgO)/Al2O3 ratio, increases the metal–slag partitioning coefficient.
Different steps in the production process:
The manufacturing process of silico manganese undergoes preheating, pre reduction and coke bed zone. A furnace is used to reduce the ferromanganese slag and the manganese ore placed at the top of the coke bed. However, it is seen that behavior of the charged materials depends upon the heating and its intensity of reaction with carbon. As this directly affects the consumption of coke and electrical energy. The quantity of slag and its composition and furnace productivity is also affected by and large.
The production process of silico manganese goes through stages such as smelting, and slag formationandreduction. Here is the detailed discussion on the stages:
It revolves round heating and pre reduction in the solid state at 1373 K and 1473 K. The manganese oxide content is reduced to manganese monoxide and iron oxides to metallic iron.
In this stage formation of liquid slag and manganese oxide reduction takes place. Slag samples are taken from the top of the coke bed at 1773 K with ferromanganese in a furnace.
Since, liquid slaghave a low viscosity to percolate through the coke bed, the top of the coke bed is normally kept at 1823 K to 1873 K.
Reduction reactions change the ore composition which in turn changes the melting temperature and other properties of ore. At low temperatures the gas contains carbon dioxide and water near the top of the furnace.
The slag obtained is mostly used as an active source of manganese in the production of silico manganese. Plus, the use of ferromanganese slag in silico manganese production leads to the increase of energy consumption by 500 kWh/t slag.