Ferromanganese is an important and indispensable material for the steel industry, aluminum alloy industry, and chemical industry. Manganese has a great affinity with oxygen and sulfur, so ferromanganese is mostly used as a deoxidizer and desulfurizer in steel making. Similarly, ferromanganese can also be added to steel as an alloying agent, which can improve the mechanical properties of steel, and increase the strength, hardness, ductility, corrosion resistance, and wear resistance of steel.
Definition & Uses of Low Carbon Ferromanganese
Because high-carbon ferromanganese will cause a carbon increase in steel, we can’t use high-carbon ferromanganese for steel with a strict limit of carbon content. This is where low-carbon ferromanganese comes from. Low carbon ferromanganese is mainly used in stainless steel, high manganese steel, acid-resistant steel tool steel and other alloy steel. The definition of low carbon ferromanganese is that the carbon content is not more than 0.7%.
Main Production Methods of Low Carbon Ferromanganese
There are three production methods of low-carbon ferromanganese: one is the electric silicon heat method, the second is the shaking ladle method, and the third is the oxygen blowing method. The most mature one in our country is the electric silicon heat method. The production of low carbon ferromanganese by electric silicon thermal method is to refine and desilicate the manganese silicon alloy with manganese ore in the refining electric furnace to get low carbon ferromanganese. The carbon content of low carbon ferromanganese depends on the carbon content of the manganese-silicon alloy, and the electrode and raw material enter the alloy with very little carbon. The production of low carbon ferromanganese by electro-silicon thermal method is divided into two forms of hot loading and cold loading according to the different states of furnace charge. The way of hot loading is: the silicon-manganese ferrous water produced in the previous workshop, without casting, directly enters the refining workshop of this project using the tractor, and then starts to produce low carbon ferromanganese by pouring the ferrous water into the refining electric furnace with the overhead crane. The way of cold loading is that the finished lump silicomanganese products which have been cast are crushed and added to the refining electric furnace and then melted before smelting.
Raw materials and standards for low carbon ferromanganese production
There are three kinds of raw materials for the production of low carbon ferromanganese, manganese ore, manganese silicon alloy and lime. Among them, manganese ore should use manganese rich oxide ore, if you use ore with low manganese content and high silica content, not only the recovery rate of manganese is low and the desilicification is slow, but also it is difficult to refine low carbon ferromanganese. And the water content of manganese ore must be low, and the manganese ore with high water content has low yield and high power consumption for refining.
Secondly, the carbon content of low carbon ferromanganese basically depends on the carbon content of silicon-manganese alloy, the lower the carbon content the better, the higher the manganese content the better, the same high iron content is also good for accelerating desilicification and reducing electricity consumption. The last raw material is lime, the lime needed for the production of low carbon ferromanganese, requires a calcium oxide containing more than eighty-five percent, and shall not have carbon inclusions, should not use powder, not burned through the lime. Because the calcium oxide in lime is only involved in the reaction after melting, and the unmelted calcium oxide is not involved in the reaction.