TW201303037A - Method for increasing reduction degree when smelting iron alloy - Google Patents

Abstract

This invention relates to a process for increasing the degree of reduction of metal components in chromite concentrates when smelting is suitable for use in the manufacture of stainless steel iron alloys. The chromite concentrate is supplied together with the nickel-containing material so that the desired degree of reduction of the metal component of the iron alloy is achieved by the amount of the nickel-containing material.

Description

Method for increasing reduction degree when smelting iron alloy

The present invention relates to a method of increasing the degree of reduction of a metal component in a material to be treated when smelting is an iron alloy suitable for the production of iron chromium for stainless steel. According to this method, a nickel-containing material is supplied to the iron alloy.

A method is known from WO Patent Publication No. 2010/092234, in which a nickel ore and/or nickel concentrate or an intermediate product precipitated from a solution of nickel ore and/or a nickel concentrate is condensed in a process of iron chromium so that it first The nickel-containing material is produced together with the iron-containing chromite concentrate and the binder particles, and is advantageously dried and calcined in a one-stage heat treatment (sintering) of the nickel-containing material. By heat treatment of the particles, the object is strengthened such that the heat treated object can be transported substantially completely between individual process stages as needed. If desired, the particles can be preheated prior to sintering. The heat treated objects can be transported substantially completely between individual process stages as needed. When an object is transported between individual process stages or process units, the heat treated object can be reduced in size as needed. The sintered and thus reinforced particles are used as materials in the smelting process under reducing conditions, in which case they are received as a smelting product containing nickel-iron alloy (iron-chromium-nickel).

Thus, the aforementioned WO Patent Publication 2010/092234 is primarily concerned with the manufacture of nickel-containing particles via sintering. However, it does not exactly describe the smelting conditions of the sintered particles. However, when describing energy efficiency, it refers to the nickel contained in the particles. The reduction of chromium in the particles, and thus the specific consumption (preferably carbon) of the reducing agent in the manufacture of the iron alloy.

It is surprisingly observed that the nickel contained in the particles not only catalyzes the reduction of chromium in the chromite particles, but also the nickel contained in the furnace feed for the smelting of the chromite is modified in the feed of the smelting furnace during the smelting process. Reduction of all essential metal components (iron, chromium and nickel). The object of the present invention is to make use of this surprising discovery and to achieve a more efficient method for improving the degree of reduction in the smelting process of chromite ore, in which the reduction of the metal component in the chromite during smelting is utilized. It is improved by alloying to a material for melting a nickel-containing material, and at the same time, an iron-chromium-nickel prealloy suitable for producing stainless steel is obtained.

According to the present invention, it is alloyed to a chromite raw material to be smelted in the manufacture of a ferroalloy prior to smelting the nickel-containing material, in which case, when the nickel-containing material itself is intended to be reduced as a metal component in the iron alloy, The nickel material simultaneously increases the reduction of the metal components contained in the feed material. According to the present invention, the degree of reduction of the metal component in the iron alloy can be favorably adjusted by the amount of nickel to be added to the iron alloy, and at the same time, an iron alloy containing a desired nickel content can be obtained as the iron-chromium-nickel alloy having a different nickel content. Iron-chromium-nickel alloys containing the desired nickel content can be used, for example, to make different stainless steels, such as Worthite iron or duplex stainless steel.

In the process according to the invention, at least part of the nickel oxide, at least part of the nickel ore and/or the nickel concentrate or at least partially obtained via leaching and/or via precipitation of the nickel ore and/or nickel concentrate may be used. Nickel intermediate as nickel-containing material. The nickel-containing raw material is supplied to the smelting process together with the iron-chromium raw material. Prior to feeding to the smelting furnace, the nickel-containing material is pretreated such that, together with the iron-chromium raw material, the sintered particles are formed from the nickel-containing raw material, or the nickel-containing raw material is separated from the chromite particles. It is also possible to carry out the treatment before the nickel-containing raw material, so that a part of the nickel-containing raw material to be supplied to the melting furnace is pretreated together with the chromite particles, and a part of the nickel-containing raw material is treated separately from the chromite ore particles. Due to the different pretreatments, the nickel-containing feedstock to be fed to the smelting furnace and to promote the reduction of the different metal components may, for example, be part of a nickel-containing hydroxide intermediate, a partial sulphide or laterite-type nickel concentrate.

The nickel-containing material to be utilized in the process according to the invention is preferably a nickel-containing hydroxide intermediate from a mining or other hydrometallurgical process, the intermediate product being from a laterite type and/or a nickel sulfide ore and/or Or a solution of the nickel-containing concentrate of the sulfided ore is precipitated. Such nickel-containing hydroxide intermediates are, for example, pressure leaching from lime-type or sulfide-type nickel or nickel concentrates, atmospheric leaching or heap leaching of nickel-containing intermediates, and receiving from nickel-containing materials. A nickel-containing precipitated product of a solvent extraction solution, a stripping solution or a refining solution of a solvent extraction process or an ion exchange process. In the method of the present invention, a nickel carbonate or nickel sulfate material may also be used as a raw material. Further, the sulfurized nickel concentrate itself and the hydrometallurgical precipitated nickel sulfide intermediate are suitable as the nickel-containing raw material for this method.

According to the present invention, the amount of the nickel-containing material to be supplied to the smelting furnace is adjusted to 5 to 25 weights based on the total mass of the pretreated material to be supplied to the smelting furnace Within the range of %, preferably 10-20% by weight. When adjusting the amount of nickel-containing material to be supplied to the smelting furnace, it is considered in each case to achieve an energy-efficient favorable reducing condition and/or to produce an iron-chromium-nickel prealloy suitable for the production of favorable stainless steel. A small amount of nickel-containing raw material is used, and the degree of reduction is kept low. In this case, an iron inconel having a low nickel content is produced. Such a low nickel content iron alloy is particularly useful for the manufacture of advantageous prealloys of the two-phase stainless steel grade. When a nickel-containing raw material is added in a larger amount, the degree of reduction is increased, and the nickel content in the smelted product is also large. Such a large chromium content of iron chromium nickel can be advantageously used to manufacture a Worthfield iron-based stainless steel grade having a high nickel content.

In the treatment to be supplied to the nickel-containing raw material of the smelting furnace, the composition and microstructure of the nickel raw material are advantageously considered in accordance with the method of the present invention. If the nickel-containing raw material is, for example, a nickel-containing intermediate product of a mining or other hydrometallurgical process precipitated from a solution containing a nickel solution, the intermediate product is particularly subjected to calcination at a higher temperature as a pretreatment, and the nickel-containing raw material is treated beforehand. It is carried out together with the production of chromite particles and sintering of the particles. Conversely, a material such as a nickel-containing raw material such as nickel oxide, nickel ore and/or a nickel concentrate, according to the process of the invention, which does not require any other basic heat treatment at higher temperatures, except for possible drying, contains nickel. The raw materials can be fed into the melting furnace along with the feeding of the chromite particles. The microstructure and composition of the nickel-containing material may also advantageously separate the pre-treated feedstock from the chromite ore and feed the nickel-containing feedstock to the sinter of the chromite ore prior to feeding to the smelting furnace.

In the method according to the invention, smelting with preheating equipment is advantageously used The furnace is such that the feed enters the smelting furnace through the preheating equipment into the smelting furnace. According to the invention, the pretreated nickel-containing feedstock is also conducted to a preheating apparatus wherein the nickel-containing feedstock will be in contact with at least the other materials to be fed to the smelting furnace. In the smelting furnace, the nickel-containing raw material is smelted together with the chromite particles into an iron-chromium-nickel having a desired composition, which can be advantageously utilized, for example, in the manufacture of a Worthian iron-based or two-phase stainless steel depending on its composition.

According to the present invention, when the smelting system of the nickel-containing raw material is advantageously carried out in a closed submerged arc furnace, one of the carbon oxide gases generated in the reduction and smelting can be utilized, for example, on chromite particles. Sintering and possibly other pre-treatments and preheating, on the other hand, for example, in different steps of the manufacturing process for producing stainless steel from iron-chromium-nickel smelting products.

The method according to the invention is described in more detail by means of the accompanying examples.

[Examples]

Forming a mixture of iron and chromium-containing chromite concentrate and nickel-containing intermediate product, adding 1.2% by weight of bentonite as a binder and 3% by weight of slag forming material (flux, limestone or ash) stone). In Table 1, the weight % of the contents of chromium, iron, nickel, carbon and sulfur in the mixture were presented, to which 10% by weight (Test 1) and 20% by weight (Test 2) of nickel hydroxide were added. Further, in Table 1, a mixture in which no nickel hydroxide was added to the mixture was used as a reference material (REF).

[Table 1]

The mixture containing the binder and presenting the materials in Table 1 was pelletized and sintered. A portion of the sintered particles are typically fed into a smelting furnace having a slag forming agent and a reducing agent.

The materials according to Table 1 were smelted, and the contents of chromium, iron, nickel, carbon and cerium in the relevant smelting products were presented in Table 2 and the recovery of the metal components of chromium, iron and nickel in the smelting product was further exhibited. The carbon content is composed according to the composition and balance of the metal alloy. The feed batch has considerable carbon so that the carbon is also slightly enough to reduce the hydrazine to the smelting product. The feed alloy has cerium oxide in the raw material and in the overall production supply.

For the production of a portion of the sintered particles on a laboratory scale, thermogravimetric measurements were carried out to monitor the reduction of chromium, iron and nickel metal components at different temperature zones with a maximum temperature of 1550 ° C under conditions representative of the smelting process. degree. Table 3 presents thermogravimetric measurements of the degree of reduction of chromium ( _Crmet /Cr _tot ), iron (Fe _met /Fe _tot ), and nickel (Ni _met /Ni _tot ) at temperatures of 1400 ° C and 1550 ° C.

The addition of the nickel-containing raw material to the particles substantially increases the degree of reduction of chromium and iron at a temperature of 1550 ° C. When the nickel reduction is increased to nearly 100% by the nickel content of the test 2, the chromium simultaneously exceeds 15% and the iron exceeds 70. %. The reduction in the degree of reduction of all metal components (chromium, iron, and nickel) in the sintered particles by the addition of the nickel-containing raw material while reducing the need to use coke as a reducing agent in achieving the reduction conditions of the smelting process.

Claims (16)

A method for increasing the degree of reduction of a metal component in a chromite concentrate when smelting is suitable for use in the manufacture of a stainless steel iron alloy, characterized in that the chromite concentrate is supplied together with the nickel-containing material so that the amount of the nickel-containing material is utilized The desired degree of reduction of the metal component of the ferroalloy is achieved. The method of claim 1, wherein the nickel-containing raw material is supplied in an amount of 5 to 25% by weight, preferably 10 to 20% by weight based on the total amount of the material to be supplied to the melting furnace. The method of claim 1 or 2, wherein at least 2.6% of the chromium contained in the reduced chromite concentrate is reduced during the smelting. The method of any of the preceding claims, wherein at least 37.4% of the iron contained in the reduced chromite concentrate is reduced during the smelting. A method according to any one of the preceding claims, wherein at least a portion of the nickel-containing feedstock is supplied to the smelting furnace in the granules produced from the chromite concentrate. The method of any of the preceding claims, wherein at least a portion of the nickel-containing feedstock is pretreated separately from the chromium concentrate particles prior to being supplied to the smelting furnace. A method according to any one of the preceding claims, wherein at least a portion of the nickel oxide is supplied to the smelting furnace as a nickel-containing raw material. The method of any of the preceding claims, wherein at least a portion of the nickel ore and/or nickel concentrate is supplied to the smelting furnace as a nickel-containing material. The method of any of the preceding claims, wherein the nickel-containing intermediate obtained at least in part via leaching and/or via precipitation of nickel ore and/or nickel concentrate is supplied to the smelting furnace as a nickel-containing feedstock. The method of claim 9, wherein the nickel-containing intermediate product obtained at least in part via pressure leaching of the laterite type or the sulfided nickel or nickel concentrate is supplied to the melting furnace. The method of claim 9, wherein the nickel-containing intermediate product obtained by at least partially leaching the laterite-type or sulfide-type nickel ore or nickel concentrate via the atmosphere is supplied to the melting furnace. The method of claim 9, wherein the nickel-containing intermediate product obtained at least in part by heap leaching of the laterite type or the sulfide type nickel or nickel concentrate is supplied to the melting furnace. The method of claim 9, wherein the nickel-containing precipitated product of at least a portion of the nickel-containing solvent extraction solution is supplied to the melting furnace. The method of claim 9, wherein the nickel-containing precipitated product of at least a portion of the nickel-containing stripping solution is supplied to the melting furnace. The method of claim 9, wherein at least a portion of the nickel-containing precipitated product containing the nickel refining solution is supplied to the melting furnace. The method of any one of claims 1 to 9, wherein a portion of the nickel concentrate, a portion of the nickel-containing intermediate obtained via leaching and/or via precipitation of nickel ore and/or nickel concentrate is supplied to Used as a nickel-containing material in the melting furnace.