The present disclosure discloses a method for refining an iron oxide that is a by-product of a zinc smelting process, the method including a roasting process of roasting the iron oxide, a washing process of washing a roasted iron oxide cake with a washing water, and a filtering process of filtering the washed iron oxide cake, thereby providing refined iron oxide.

The present disclosure discloses a method for refining an iron oxide that is a by-product of a zinc smelting process, the method including a roasting process of roasting the iron oxide, a washing process of washing a roasted iron oxide cake with a washing water, and a filtering process of filtering the washed iron oxide cake, thereby providing refined iron oxide.

A method for recovering a valuable element, by which method metal with a high proportion of a valuable element can be obtained. The method includes adding a reductant to an oxide containing at least one element selected from the group consisting of nickel and cobalt, followed by heating, to thereby reduce the oxide, the reductant contains at least one selected from the group consisting of metallic iron and an iron oxide, and an addition amount of the reductant is 1.3 equivalent or less.

Provided is a technique for increasing the yield of reduced iron, thereby improving productivity when manufacturing reduced iron by heating an agglomerate. This method for manufacturing reduced iron includes: a step in which a mixture is agglomerated, said mixture containing an iron oxide-containing substance, a carbonaceous reducing agent, and a melting point regulator; and a step in which reduced iron is manufactured by heating the obtained agglomerate, reducing and partially melting the iron oxide in the agglomerate, and aggregating the iron component. The particle size of the fine particulate iron generated in the step in which the reduced iron is manufactured is adjusted, and the fine particulate iron is blended into the mixture.

Provided is a technique for increasing the yield of reduced iron, thereby improving productivity when manufacturing reduced iron by heating an agglomerate. This method for manufacturing reduced iron includes: a step in which a mixture is agglomerated, said mixture containing an iron oxide-containing substance, a carbonaceous reducing agent, and a melting point regulator; and a step in which reduced iron is manufactured by heating the obtained agglomerate, reducing and partially melting the iron oxide in the agglomerate, and aggregating the iron component. The particle size of the fine particulate iron generated in the step in which the reduced iron is manufactured is adjusted, and the fine particulate iron is blended into the mixture.

A method for recovery of evaporable substances comprises melting (210) of a material comprising evaporable metals and/or evaporable metal compounds into a molten slag. The molten slag is agitated (212) by a submerged jet of hot gas. The hot gas is controlled (214) to have an enthalpy of at least 200 MJ/kmol, and preferably at least 300 MJ/kmol. At least a part of the evaporable metals and/or evaporable metal compounds are fumed off (216) from the molten slag. An arrangement for the method is based on a furnace with a plasma torch submerged into molten slag in the furnace.

There is provided a method and system for recycling by-products containing large amounts of useful components and discharged in the form of dust and sludge from a coal-based molten iron making process to reuse the by-products in a reduced iron agglomeration process. The system includes: a fluidized reduction furnace reducing fine iron ore; a reduced iron tank connected to the fluidized reduction furnace through a reduced iron discharge pipe for storing the reduced iron and supplying the reduced iron in an agglomeration system; an agglomeration system agglomerating the reduced iron transferred from the reduced iron tank; and a transfer unit transferring compactions of by-products discharged from a molten iron making process through a by-product supply pipe. The compactions of the by-products are supplied to at least one selected from the group consisting of the fluidized reduction furnace, the reduced iron supply pipe, and the reduced iron tank.

There is provided a method and system for recycling by-products containing large amounts of useful components and discharged in the form of dust and sludge from a coal-based molten iron making process to reuse the by-products in a reduced iron agglomeration process. The system includes: a fluidized reduction furnace reducing fine iron ore; a reduced iron tank connected to the fluidized reduction furnace through a reduced iron discharge pipe for storing the reduced iron and supplying the reduced iron in an agglomeration system; an agglomeration system agglomerating the reduced iron transferred from the reduced iron tank; and a transfer unit transferring compactions of by-products discharged from a molten iron making process through a by-product supply pipe. The compactions of the by-products are supplied to at least one selected from the group consisting of the fluidized reduction furnace, the reduced iron supply pipe, and the reduced iron tank.

This method for producing a vanadium compound has an alkaline leaching step for immersing incineration ash in an alkaline solution to cause vanadium to leach from the incineration ash into the alkaline solution and obtain a leachate slurry, a solid-liquid separation step for separating the leachate slurry obtained in the alkaline leaching step into a solid and liquid followed by removing insoluble matter to obtain a leachate, a pH adjustment step for adding acid to the leachate following solid-liquid separation to make the leachate acidic, an aging step for aging the leachate following pH adjustment until a precipitate forms in the leachate, and a separation step for separating the precipitate from the leachate following the aging step.

Methods treat ash from waste incineration, wherein the methods at least comprise: a) the digestion of the ash by a leaching liquor containing phosphate ions in solution such as to form a first solid phase comprising impurities and a first liquid phase comprising phosphate ions; and b) the separation of said first liquid phase comprising phosphate ions from said first solid phase. Step a) is carried out for a duration of less than one hour or at a temperature of more than 40 C.