Abstract: In order to stably operate a boiler using several kinds of solid fuels including depleted ash as fuels, adhesion of ash is suppressed. A calculator (9) preliminarily collects properties of a solid fuel, such as the content rate of ash and the composition of an ash constituent, as data (8). The calculator (9) uses the mix ratio of solid fuels as a parameter and calculates the composition of an ash constituent of the mixed fuels on the basis of the preliminarily measured composition of the ash constituent of each solid fuel. The calculator (9) determines a reference value of the rate of slug by which the ash deposition ratio is reduced on the basis of the relationship between the preliminarily measured ash deposition ratio and the slag ratio. Further, the calculator (9) calculates the mix ratio of each solid fuel using a thermodynamic equilibrium calculation so as to obtain an ash composition in which the slag ratio is not more than the determined reference value.

Abstract: Method and system for producing metallic nuggets includes providing reducible mixture (e.g., reducible micro-agglomerates; reducing material and reducible iron bearing material; reducible mixture including additives such as a fluxing agent; compacts, etc.) on at least a portion of a hearth material layer. In one embodiment, a plurality of channel openings extend at least partially through a layer of the reducible mixture to define a plurality of nugget forming reducible material regions. Such channel openings may be at least partially filled with nugget separation fill material (e.g., carbonaceous material). Thermally treating the layer of reducible mixture results in formation of one or more metallic iron nuggets. In other embodiments, various compositions of the reducible mixture and the formation of the reducible mixture provide one or more beneficial characteristics.

Abstract: The invention relates to a process for the separation and recovery of non-ferrous metals from zinc-bearing residues, in particular from residues produced by the zinc manufacturing industry. The process allows for the valorisation of metal values in a Zn-, Fe- and Pb-bearing residue, and comprises the steps of: subjecting the residue to a direct reduction step, thereby producing a metallic Fe-bearing phase and Zn- and Pb-bearing first fumes; extracting the Zn- and Pb-bearing first fumes and valorising Zn and Pb; subjecting the metallic Fe-bearing phase to an oxidising smelting step, thereby producing an Fe-bearing slag and second metals-bearing fumes; extracting the second metals-bearing fumes and valorising at least part of their metallic content. The main advantage of this process is that an environmentally acceptable output for Fe is obtained.

Abstract: A method of operating a multiple hearth furnace with a plurality of vertically aligned hearth floors includes feeding a first material onto the uppermost hearth floor and moving it over the hearth floor before it falls through a drop hole onto the next lower hearth floor. The first material is processed in this way from hearth floor to hearth floor to the lowermost hearth floor. A second material is fed onto one of the hearth floors to be mixed into the first material. This second material is moved separately from the first material in a separate annular zone of the hearth floor onto which it is fed before it is mixed into the first material, providing an efficient thermal preconditioning of the second material prior to mixing it with the first material without requiring any supplemental equipment.

Abstract: The invention concerns a method for producing melt iron comprising the following steps: a) reducing the iron ore particles to form pre-reduced iron comprising excess free carbon; b) hot process transfer of the pre-reduced iron in a smelting furnace; c) smelting the pre-reduced iron in a smelting furnace to obtain melt iron.

Abstract: The invention relates to a method for producing directly reduced, desulfurized iron in a multiple-hearth furnace which comprises two zones arranged one above the other and each having several hearths. Iron ore is reacted with a reducing agent in a first zone of the multiple-hearth furnace at a temperature ranging from 800° C. to 1100° C. to obtain metallic iron. In addition, the gases are desulfurized using desulphurizing agents, whereby the directly reduced iron is discharged from the multiple-hearth furnace and the desulfurized gases are guided into a second zone where the iron ore is preheated to a temperature ranging from 600° C. to 800° C.

Abstract: A process for thermal treatment of residual materials containing heavy metal and iron oxide, including providing a multiple-hearth furnace having hearths provided one above the other, depositing the residual materials continuously on a top hearth of the hearths, gradually transferring the residual materials to lower hearths of the hearths, introducing reducing agents to at least one of the hearths and reacting the residual materials to form heavy metals and directly reduced iron, exhausting gases containing heavy metals from below hearths of the hearths where the heavy metals are being vaporised, re-injecting at least a part of the gases into the multiple-hearth furnace from above the hearths of the hearths where the heavy metals are being vaporised, and discharging the directly reduced iron together with residues of the reducing agents in an area of a bottom hearth of the hearths in the multiple hearth furnace.

Abstract: Process for thermal treatment of residual materials containing oil and iron oxide in a multiple-hearth furnace, which has several hearths one above the other, the residual materials containing oil and iron oxide being mixed with a solid reducing agent, introduced continuously into the multiple-hearth furnace, charged on the top hearth and transferred gradually to the lower hearths, the residual materials containing oil and iron oxide being dried in the top hearths, the oil subsequently evaporated and pyrolised and the reducing agent reacting with the iron oxides to form directly reduced iron, the directly reduced iron being discharged with residues of reducing agents in the areas of the bottom hearth of the multiple-hearth furnace.

Abstract: The invention relates to a method for the heat treatment of residues containing heavy metals, carried out in a multiple-hearth furnace which is divided into three zones, each of which comprises several stacked levels. Said method consists of the following steps: continuous feeding of the heavy-metal residues into the top level of the first zone of the multiple-hearth furnace, the residues being gradually transferred to the second zone and dried during the transfer; continuous feeding of reducing agents and desulfurizers into the top level of the second zone, whereby the reducing agents and desulfirizers are mixed with the dried residues and the mixture is heated to approximately 800° C., calcined during heating and gradually transferred to the third zone; heating of the mixture to approximately 1000° C. in the third zone, whereby the metals are reduced and the waste gases resulting in said third zone are drawn off and treated separately; and discharge of the mixture from the multiple-hearth furnace.

Abstract: The present invention is concerned with a method for the pre-reduction of laterite fines in a reactor, preferably a fluidized bed, with reducing gases generated in situ by adding a reducing agent such as a carbonaceous material in the fluidized bed chamber, fluidizing the bed with an oxidizing gas and maintaining the reactor at a temperature sufficiently high to partially combust the coal and generate a reducing atmosphere. The reactor bed discharge calcine product has a carbon content of about 0.1%, and the composite reactor product has a carbon content lower than 2.0%.

Abstract: A process for thermal treatment of residual materials containing heavy metal and iron oxide, including providing a multiple-hearth furnace having hearths provided one above the other, depositing the residual materials continuously on a top hearth of the hearths, gradually transferring the residual materials to lower hearths of the hearths, introducing reducing agents to at least one of the hearths and reacting the residual materials to form heavy metals and directly reduced iron, exhausting gases containing heavy metals from below hearths of the hearths where the heavy metals are being vaporised, re-injecting at least a part of the gases into the multiple-hearth furnace from above the hearths of the hearths where the heavy metals are being vaporised, and discharging the directly reduced iron together with residues of the reducing agents in an area of a bottom hearth of the hearths in the multiple hearth furnace.

Abstract: A method for producing reduced iron comprises agglomerating a raw material mixture containing a carbonaceous reducing agent and an iron oxide-containing material into small agglomerates, heating the agglomerate within a heat reduction furnace, thereby solid reducing the iron oxide in the agglomerate to produce solid reduced iron, or further heating the solid reduced iron, melting the metallic iron produced by the reduction, and coagulating the molten metallic iron while separating the slag component contained in the small agglomerates to provide granular metallic iron, which is characterized by using a agglomerate having a particle size of 10 mm or less or 3-7 mm, preferably less than 6 mm, more preferably 3 mm or more and less than 6 mm as the small agglomerates.

Abstract: A process of recovering iron values and separating zinc oxides and other contaminants from steel mill waste metal oxides, such as blast furnace dust, BOF dust, mill scale and oily sludges, characterized by iron metallization levels up to 95% or more and zinc oxide removal in excess of 99%, and including the steps of blending the oxides with coke breeze in an amount sufficient to provide a total carbon content of 16% to 22%, the coke breeze having a particle size of 50% or more plus 60 mesh or larger, briquetting the blend to form briquettes having a thickness ranging from 1/2" to 3/4", and firing the briquettes in a rotary hearth furnace to metallize the iron and evolve zinc and other oxide contaminants.

Abstract: A method and apparatus for producing, in a reactor, a suitable prereduced product for final reduction from material containing metal oxide. The material is preheated in a fluidized bed by means of hot gases from a subsequent prereduction stage. The hot material is smelted and prereduced in a flame chamber utilizing hot reducing gases from a subsequent final reduction stage. The prereduced material is completely reduced in the final reduction stage.