Manganese is currently the most widely used alloying element in steel. An appropriate amount of manganese can effectively increase the strength of steel, eliminate the thermal embrittlement effect of sulfur on steel, and improve the hot workability of steel without significantly reducing plasticity, impact toughness, and the content of manganese in ordinary carbon steel is about 0.3 to 1.5%. At present, the manganese content in rebar with the largest steel production is generally 1.0-1.5%.
At present, the manganese content in molten steel is controlled by adding low-carbon ferromanganese and silicon manganese into molten steel. The price of high-carbon ferromanganese containing 64% manganese is about 7,000 yuan/ton, and the cost of silicon manganese ferromanganese containing 64% manganese is about 8,000 yuan/ton, which is relatively expensive. The consumption of manganese alloys accounts for a large part of the alloy cost of steel mills. On average, it takes about 120 yuan/ton of steel to add 1% manganese to molten steel. However, manganese ore is currently highly cheap. The price of manganese ore containing 50% manganese is around 1500 yuan/ton. Compared with ferro manganese, the cost of adding manganese to molten steel with manganese ore can be reduced by 70%.
At present, the conventional method of increasing manganese in steel plants is to first cool the hot manganese alloys (silicon-manganese alloys, high-carbon ferromanganese alloys, medium-carbon ferro manganese alloys, and low-carbon ferromanganese) and then transport them to steel plants to increase manganese. Manganese alloys are expensive. , the cost of the alloy is high, and the heat of the hot manganese alloy is lost, resulting in a waste of energy.
However, if the manganese ore is directly added to the molten steel during the converter smelting process, the recovery rate of manganese is low, and most of the manganese enters the slag in the form of MNO, and the recovery rate of manganese is about 10-30%. The application number is 201310478304.4, low-carbon ferromanganese 8004 (a smelting method for increasing the manganese content in molten steel at the end of a small converter), which provides a process specifically for the characteristics of a small converter, which can effectively implement the direct converter process and add manganese ore on the small converter. The recovery rate of manganese in manganese ore can only reach 37%, and the recovery rate of manganese is still very low.