A liquid slag granulating system includes a granulator (1), a granulator connecting part and a granulator drive part. The granulator (1) is disc-shaped or cup-shaped, and a diversion cone is arranged at a center of the granulator (1). The granulator drive part drives the granulator to rotate, thus granulating liquid slag. The system further includes an air supply part.

On molten iron having the P concentration of 2 to 4 mass % and having the Cr concentration of 0.3 to 1.2 mass %, a dechromization treatment is performed by adjusting a basicity (CaO mass %)/(SiO.sub.2 mass %) of slag to greater than 0.1 and 1 or less and supplying an oxygen source with a molten iron temperature falling within a range of 1250 to 1500 C. to manufacture molten iron having the P concentration of 1.9 to 3.8 mass % and having the Cr concentration of less than 0.2 mass %.

A control system and method for dry centrifugal granulation of liquid slag are provided. The control system includes a granulator cold-air control unit and a feeding unit. The granulator cold-air control unit includes a granulator, a rotating shaft, a motor, and a cold-air supply unit. The granulator is fixed to the motor; the cold-air supply unit includes a shaft cooling air channel and an annular cooling air channel; the shaft cooling air channel consists of an inner duct sleeve and a shaft sleeve; the annular cooling air channel consists of the inner duct sleeve and an outer duct sleeve arranged at periphery of the inner duct sleeve, which have different external diameters; the feeding unit includes a slag dropping pipe arranged above the granulator; a sliding gate is arranged at a lower section of the slag dropping pipe, and an accident diversion spout is equipped.

A control system and method for dry centrifugal granulation of liquid slag are provided. The control system includes a granulator cold-air control unit and a feeding unit. The granulator cold-air control unit includes a granulator, a rotating shaft, a motor, and a cold-air supply unit. The granulator is fixed to the motor; the cold-air supply unit includes a shaft cooling air channel and an annular cooling air channel; the shaft cooling air channel consists of an inner duct sleeve and a shaft sleeve; the annular cooling air channel consists of the inner duct sleeve and an outer duct sleeve arranged at periphery of the inner duct sleeve, which have different external diameters; the feeding unit includes a slag dropping pipe arranged above the granulator; a sliding gate is arranged at a lower section of the slag dropping pipe, and an accident diversion spout is equipped.

A method for controlling a particle size of dry centrifugal granulated slag from liquid slag, which is based on a dry centrifugal granulation system for liquid slag, wherein the dry centrifugal granulation system for the liquid slag includes: a temperature control unit, a flow control unit, and a granulator control unit; wherein the temperature control unit is configured to control a high-temperature slag in the liquid slag buffer device to maintain a first set temperature range, and control a temperature of an outflow slag of the buffer device to maintain a second set temperature range; a flow control unit configured to control a flow rate of the high-temperature slag flowing out of the buffer device in a set range to ensure smoothness of the flow; a granulator control unit configured to ensure a smooth operation of the granulator during high-speed rotation.

An exhaust gas treatment method includes: burning a combustible component in exhaust gas by causing the exhaust gas, which is produced in an electric furnace, to flow into a slag holding furnace and supplying oxygen-containing gas into the slag holding furnace; causing the burned exhaust gas to flow from the slag holding furnace to a suction device through an exhaust gas pipe; adjusting an internal pressure of the electric furnace by introducing external air into the exhaust gas pipe through an opening portion provided in the middle of the exhaust gas pipe; and changing an area of the opening portion depending on a variation in the internal pressure of the electric furnace by using an opening area changing unit provided in the opening portion.

An exhaust gas treatment method includes: burning a combustible component in exhaust gas by causing the exhaust gas, which is produced in an electric furnace, to flow into a slag holding furnace and supplying oxygen-containing gas into the slag holding furnace; causing the burned exhaust gas to flow from the slag holding furnace to a suction device through an exhaust gas pipe; adjusting an internal pressure of the electric furnace by introducing external air into the exhaust gas pipe through an opening portion provided in the middle of the exhaust gas pipe; and changing an area of the opening portion depending on a variation in the internal pressure of the electric furnace by using an opening area changing unit provided in the opening portion.

A ceramic and a method of forming a ceramic including milling steel slag exhibiting a diameter of 5 mm of less to form powder, sieving the powder to retain the powder having a particle size in the range of 20 to 400 removing free iron from the powder with a magnet, heat treating the powder at a temperature in the range of 700 C. to 1200 C. for a time period in the range of 1 hour to 10 hours and oxidizing retained iron in the powder, compacting the powder at a compression pressure in the range of 20 MPa to 300 MPA, and sintering the powder at a temperature in the range of 700 C. to 1400 C. for a time period in the range of 0.5 hours to 4 hours to provide a ceramic.

A method utilizing a humic acid substance for renovating and afforsesting slag is provided. A humic acid substance may be utilized for passivation, adsorption, reduction, chelation and immobilization of harmful heavy metal elements in slag, for example, Cr, As, Cd, Ni, Pb, Ba, Hg, Co, Se, Ag and Be, and aggregating the slag, thereby detoxifying the slag and producing artificial earth. The artificial earth may be used in combination with a carrier bacterial fertilizer to continuously produce the active humic acid substance, achieving an effect similar to the combination of blood transfusion and blood production, thereby forming a high-quality artificial soil.

A method utilizing a humic acid substance for renovating and afforsesting slag is provided. A humic acid substance may be utilized for passivation, adsorption, reduction, chelation and immobilization of harmful heavy metal elements in slag, for example, Cr, As, Cd, Ni, Pb, Ba, Hg, Co, Se, Ag and Be, and aggregating the slag, thereby detoxifying the slag and producing artificial earth. The artificial earth may be used in combination with a carrier bacterial fertilizer to continuously produce the active humic acid substance, achieving an effect similar to the combination of blood transfusion and blood production, thereby forming a high-quality artificial soil.