The present invention provides a method of simultaneously recycling plastics and detoxifying chromite ore processing residue with residual heat from a steel slag. By heating and gasifying plastics with steel slag, followed by catalytically split-decomposing the plastics with catalysts such as chromite ore processing residue, the plastics are thoroughly converted into a energy gas under water vapor gasification. The surface coking of Chromite Ore Processing Residue is avoided. Meanwhile, the energy gas reduces Cr.sup.6+ in Chromite Ore Processing Residue into Cr.sup.3+, and the energy gas is cooled, and CO.sub.2 and Cl in the energy gas are adsorbed by alkaline substances in Chromite Ore Processing Residue. With this method, chromite ore processing residue is detoxified, and steel slag is cooled, furthermore, energy is saved and a energy gas is obtained.

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 %.

The present invention relates to a method and system for recovering carbonate from steel slag, in which it is possible to extract carbonate from steel slag and reuse the extracted carbonate, and to recycle steel slag and make use of CO.sub.2 gas without emission to the atmosphere. Since unreacted metal ions and an acidic solvent are reused in the method and system, it is possible to increase carbonate extraction efficiency and reduce an amount of waste.

A method and apparatus for direct drying of inorganic sludge with a drum drawing process, comprising the following steps: 1) drum mixed drying of slag and sludge: respectively conveying the slag and sludge into a drum (1) in proportion, completing mixing, heat exchange, dehydration, cooling and crushing of the slag and sludge under the rolling action of the drum (1) and a steel ball to achieve cooling, crushing and drying of the slag and sludge, and directly discharging the obtained mixture; 2) slag and sludge separation: separating the steel slag and dry sludge in a manner of combining screening and rotary separation; 3) tail gas treatment: treating dusts, sulfides and organic compounds in tail gas generated by the dry sludge by using wet alkali washing and activated carbon adsorption, and discharging the treated tail gas; and 4) tailing sludge treatment: generating steam and dusts in the drum treatment of the slag and sludge, allowing dusts to enter a tail gas treatment device (4) with steam, aggregating the dusts after wet washing or spraying, and then conveying into a tailing sludge blending device (5) by means of a conveying device, mixing and stirring the tailing sludge and original sludge, conveying the obtained mixture into the drum (1), and drying the mixture to realize zero discharge of undried sludge.

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 for treating desulfurization slag involves conveying desulfurization slag from pig iron desulfurization to a unit where the desulfurization slag is melted at a temperature of at least 1,400 C. In the unit, a thorough mixing is achieved. The treatment takes place in the unit under oxidizing conditions. Sulfur dioxide is generated and collected from the roasting gas and supplied for further utilization.

The present invention relates to a method for producing a potassium sulfate containing fertilizer composition from a sodium sulfate containing residue process stream of a battery manufacturing facility, battery recycling facility, or steel production plant, wherein residue process stream from a battery manufacturing facility, battery recycling facility, or steel production plant is provided; optionally water is provided; potassium chloride is provided; and a reaction mixture is provided comprising said optional water, potassium chloride and residue process stream, and is allowed to react, wherein potassium sulfate is obtained.

The present invention provides a method of simultaneously recycling plastics and detoxifying chromite ore processing residue with residual heat from a steel slag. By heating and gasifying plastics with steel slag, followed by catalytically split-decomposing the plastics with catalysts such as chromite ore processing residue, the plastics are thoroughly converted into a energy gas under water vapor gasification. The surface coking of Chromite Ore Processing Residue is avoided. Meanwhile, the energy gas reduces Cr.sup.6+ in Chromite Ore Processing Residue into Cr.sup.3+, and the energy gas is cooled, and CO.sub.2 and Cl in the energy gas are adsorbed by alkaline substances in Chromite Ore Processing Residue. With this method, chromite ore processing residue is detoxified, and steel slag is cooled, furthermore, energy is saved and a energy gas is obtained.

The liquid steel slag (2) is poured in at least four successive layers (6-8), comprising a lowermost layer (6), an uppermost layer (7) and at least two intermediate layers (8), in a reservoir (3) and the layers of liquid steel slag are allowed to solidify. After having applied the uppermost layer (7), the solidified steel slag is cooled down more quickly by means of water. The average temperature of each of the intermediate layers (8) is kept at least until the start of the water cooling step, and this for at least one hour, above a minimum temperature which is equal to or higher than the temperature at which -dicalcium silicate is formed. In this way, more crystalline phases different from dicalcium silicates are formed so that the formation of fines by the transition of into -dicalcium silicates can be considerably reduced. A glassy material and/or a phosphorus containing compound is preferably added to the liquid slag to further reduce the formation of fines.

The present invention relates to a method and system for recovering carbonate from steel slag, in which it is possible to extract carbonate from steel slag and reuse the extracted carbonate, and to recycle steel slag and make use of CO.sub.2 gas without emission to the atmosphere. Since unreacted metal ions and an acidic solvent are reused in the method and system, it is possible to increase carbonate extraction efficiency and reduce an amount of waste.