EP2132345B1 - Melt metallurgical method for the production of metal melts, and transition metal-containing charge for use therein - Google Patents

Description

The invention relates to a melt-metallurgical process for producing a melt according to the preamble of claim 1 with at least one base metal having at least 10 wt .-% iron and at least one further alloying ingredient in a melting vessel, wherein the melt is covered with a slag. The invention further relates to a transition metal-containing, in particular nickel and / or cobalt-containing, additive for producing transition metal-containing, in particular nickel and / or cobalt-containing, alloys, wherein the additive is present as a solid and has a transition metal content of ≥ 15 wt .-%. Furthermore, the invention relates to the use of such an additive in the method according to the invention.

In order to produce iron alloys or steels enriched with certain alloy constituents, it is usually necessary to supply alloy constituents to the melt in order to adjust the composition of the melt. Such constituents may in particular be nickel, cobalt but also vanadium, molybdenum, etc. Ferroalloys such as ferronickel, ferro-cobalt, etc. are often used to adjust the melt composition, but also oxidic components such as NiO or nickel ores such as laterites, which have a corresponding nickel content. However, the addition of these ingredients is always associated with certain disadvantages.

Thus, the provision of ferroalloys to adjust the contents of the alloy components in the melt is relatively expensive and requires a large amount of energy. The use of oxidic minerals to adjust the melt composition has the disadvantage that often a great deal of effort is required to remove unwanted impurities from unwanted trace elements such as phosphorus, tin, arsenic or certain steels cobalt, molybdenum, etc. from the ores. Even by enrichment processes such as flotation, such impurities are not always sufficient to remove. If unwanted constituents such as phosphorus, sulfur, etc. are introduced into the melt by the ores, this also results in a high outlay for the removal of the same from the melt, for example by suitable slag work, the use of a plurality of different slags and the like. Furthermore, the incorporation of ores into molten metals poses other problems, in particular with regard to the kinetics and the extent of the formation of nuclei, since, when ores are used, the particles of the aggregate do not always dissolve sufficiently rapidly and completely in the melt and thus have undesirable effects can have the smelting metallurgy. Furthermore, the introduction of oxidic ores into the melt has a negative contribution to the energy balance, since the melting of the ores is strongly endothermic. This can lead to considerable procedural and metallurgical problems, for example also to increased slagging of alloying constituents such as chromium. Which elements are slagged depends essentially on the thermal conditions at the time of the process implementation.

Furthermore, it is known to directly supply oxides such as nickel oxide, but this also raises the above-mentioned problems. Furthermore, nickel oxide is toxic and carcinogenic, so its use is to be avoided.

The WO 97/20954 describes a melt metallurgical process for the production of ferro-nickel, stainless steel or the like in which nickel, nickel ores or calcined nickel compounds are fed to a molten slag-covering slag.

The EP 583 164 A1 describes a process for producing stainless steel wherein finely divided oxides are mixed with finely divided reducing agents mixed to form agglomerates.

The US 4,919,714 describes a process for refining steel in which gas is injected into a melt with stirring while heat is supplied to the melt surface by a burner and metal oxides are added to the melt.

The WO 03/018850 A1 describes a steelmaking process wherein a solidified hydroxide slurry containing metals from a steel pickling process and at least one fluoride-containing compound is fed to the melt.

The WO 2005/098054 A1 describes a process for producing a flux which can be used in steelmaking, wherein the flux is a fluoride-containing, calcined hydroxide slurry.

The WO 2006/131764 A1 describes a process for producing ferroalloys wherein chromium metal, chromium-containing alloys and chrome ore are fed to a slag-covered melt.

The invention is therefore based on the object, a method for the manufacture of alloy melts enriched metal melts, which are preferably covered with a slag and in mass transfer to provide, which is simple and inexpensive to carry out and which allows a simple way a melt metallurgical control. Furthermore, the object is to provide an additive which can be used particularly advantageously and inexpensively in such a method.

The invention is achieved by providing a method according to claim 1 and providing an aggregate according to claim 15.

The process according to the invention uses adjuvants containing the alloying constituent to be enriched and high contents of molten metallurgically volatile constituents, in particular water and / or carbonate, the low sulfur contents, low contents of slag formers such as calcium and / or magnesium oxide, etc., as well as ores have high contents of the respective alloying ingredient. The water may in particular be present at least substantially or practically exclusively as chemically bound water in the form of water of crystallization and / or hydroxide groups. Such additives can be obtained in particular by the treatment of ores, for example by leaching of laterite ores, if the components to be alloyed nickel and / or cobalt. Optionally, these leaches can be worked up to separate other undesirable components, optionally, the desired alloying constituents can also be separated directly from these leaching by precipitation. The respective precipitates can then be separated and dried, in particular in order to obtain pneumatically or gravity-feedable additives. Optionally, the aggregates thus obtained can be calcined or precalcined in a separate step to the content of the at Addition of the additive to the melt volatilizing components such as chemically bound water, for example in the form of water of crystallization and / or to reduce from hydroxide groups and / or carbonate, without this being always necessary. The content of undesirable constituents which are neither desired alloy constituents nor constituents which volatilize in the addition of the aggregate to the molten metal nor which are slag formers may be ≦ 15-20% by weight, ≦ 5-10% by weight or else ≤ 2-3 wt .-% based on the aggregate used.

Surprisingly, it has been found that such additives having a very high content of constituents volatilizing in the addition of the additive into the melt can be used in such processes and offer advantages such as the production of relatively pure melts, low metallurgical advantages such as low slagging of other alloying constituents Production costs of the respective melt and the materials produced from these. Surprisingly, it has been found that such processes can be controlled despite the effects occurring with the calcination of the added additives, such as the production of large quantities of water vapor or other volatile gases such as CO ₂ . This applies in particular when the additive is supplied from the upper region of the melting vessel, ie on the slag side. The method according to the invention is particularly applicable when the base metal of the melt, ie the main alloy constituent thereof, is iron or the melt generally contains ≥10-20% by weight of iron or is iron-containing, but also with other base metals which may in general be transition metals. The process is particularly suitable for the production of steels, including low, medium and high alloyed steels. The steels preferably have a high carbon content, for example ≥ 1.5% by weight, ≥ 1.75-2% by weight or ≥ 2.25-2.5% by weight or ≥ 2.75-3% by weight % Of carbon, based on the carbon content of the melt, into which the Aggregate is introduced or based on the end product of the respective Stahlherstellungverfaherns as it is produced in the respective melt vessel. The nickel content of the resulting melt after completion of the addition of a Ni-containing additive may be ≥ 1.5-1.75 wt .-%, ≥ 2-2.75 wt .-% or ≥ 3-4 wt .-%, for example about 5 wt .-% or greater. The process according to the invention is furthermore preferably usable in the preparation of Cr-Fe or Cr-Fe-Ni master alloys which have a Cr content of ≥ 30-35% by weight, ≥ 40-45% by weight or ≥ 45 -50 wt .-% chromium, wherein the carbon content of the melt in the process step of adding the additive according to the invention or the final product ≥ 2-3 wt .-%, ≥ 3.5-4 wt .-% or ≥ 4.5 -5 wt .-% may be and wherein the melt is preferably prepared in a converter process. The carbon content is usually ≤ 8-10 wt .-%. By the method according to the invention is usually a decarburization of the melt instead. The addition of the additive according to the invention therefore usually takes place during a decarburization process carried out by means of a lance or during a refining process or directly preceding or following it.

In general, the addition of the additive according to the invention preferably takes place during a main decarburization phase of the respective process of steelmaking or production of the respective alloy. The additive used according to the invention is thus preferably still supplied to decarburizing melts, it being possible for partial decarburization to take place during the supply of the additive.

Preferably, the additive to be alloyed is introduced into the respective upper space of the melt vessel or converter, ie from above the slag covering the melt, wherein the feed additive outlet is preferably spaced from the slag so that the additive travels through the atmosphere to the slag Melt down to take.

Advantageously, the additive present as a solid is fed by means of a gas stream to produce a slag-free focal spot of the molten metal directly in this. This applies in particular to the use of Ni and / or Co-containing additives, but possibly also in the case of other transition metals, in particular of V, Mo. The focal spot of the molten metal (molten bath surface) thus arises from the fact that the slag from the gas stream at the Appearance is completely displaced, so that the aggregate - taking into account its calcination in the feed from the feeder to the melt - can come into direct contact with the molten metal without having to pass through the slag. With regard to the melt-metallurgical conversion of the aggregate and of the alloy, it has turned out to be advantageous overall when the focal spot has the highest possible temperature, for example from ≥ 1750 ° to 1800 ° C., preferably ≥ 2000 ° to 2200 ° C. or ≥ 2400 ° to 2,500 ° C, more preferably temperatures of ≥ 2,600 ° C. Due to the very high focal spot temperatures (i.e., temperatures of the melt in the focal spot), an extremely rapid absorption of the alloying constituents from the aggregate into the melt takes place.

The calcination of the aggregate can be controlled in such a way, in particular by the conveying speed of the aggregate in the direction of the melt, that this takes place only immediately after or at the outlet from the usually formed as a lance feeder. The calcination may in this case take place partially or predominantly during the transport from the lance to the melt surface, but also to a significant or predominant proportion directly in the focal spot (ie the melt surface exposed by the injection) or in the impact zone of the added aggregate on the molten bath, in which the melt a sink training, instead. The endothermic calcination processes of the additive thus take place before it enters the melt or directly in the focal spot or the impact zone, so that a very fine separation of the aggregates takes place during the calcination and prior to their absorption by the melt. The calcination gases thus penetrate only to a small extent or practically not in the molten metal and calcination of the additive in the nozzle zone, ie before exiting a lance nozzle or the like is avoided. As a result, overall, the energy balance of the manufacturing process is better controlled, which brings with it special advantages in the process management, especially with regard to the prevention of slagging of certain alloying components such. As chromium and the metallurgy of the melt with respect to the introduced by the calcination of the aggregate crystallization nuclei. This also applies, for example, to any injection of said additives by means of underbath nozzles, which penetrate into the melt below the slag.

The additive containing the alloying elements is preferably supplied in a stream of solids to the melt, which is surrounded by a gas stream. This can effectively create a focal spot in the melt and avoid interaction or chemical reaction of the aggregate with the slag. At the same time thereby the solids flow can be focused or adjusted in its diameter. Furthermore, the depth of penetration of the additive into the molten metal or the place of calcination can be controlled independently of the solids supply by the gas jacket and / or escape of dusts such as nickel oxide dusts are avoided from the solids flow. Furthermore, escape of volatiles formed during calcination such as H ₂ O, CO ₂ and the like is avoided, which is desirable in certain process controls. The sheathing of the solids flow through the gas or conveying gas flow is thus preferably from the feeder, in particular a gas lance, into the focal spot. Preferably, the conveyor or the lance is cooled, in particular water-cooled. Under certain circumstances, the enveloping gas can at the same time be the conveying gas for the flow of solids. Preferably, the delivery gas is inert with respect to the aggregate, at least until it exits from the supply means such as a lance, or totally inert under the process conditions. The conveying gas may under certain circumstances be air, preferably air enriched with nitrogen or other inert gases, or directly nitrogen or another inert gas such as argon. Preferably, the conveying gas does not have an oxygen content which is increased in relation to air.

The lance may have in a known manner a central tube for supplying solids and radially outside another coaxially arranged tube with a larger diameter or a preferably substantially circular arrangement of mostly several outlet nozzles for the sheath gas. The outlet nozzles of the solids flow and / or the jacket gas can be designed in particular as Laval nozzles. The possibly used carrier gas emerges together with the solids from the central tube. The lance can have a water-cooled jacket.

The device for supplying or blowing in the additives according to the invention can be designed in the manner of a closed system, so that any human contact with the material can be avoided. This is especially important in the case of nickel-containing aggregates. Thus, in a pneumatic system, a silo can be loaded by a means of transport with the aid of compressed air and the dusts can be further supplied by pressure vessels to the feeder or the lance. The exiting from the lance aggregates are encased by a gas stream to minimize losses of aggregates here.

The fact that the calcination of the additives is controlled so that they take place at or after leaving the feeder or lance (preferably not before), can also the existing waste heat from rising exhaust gases and radiant heat from the bath and from the surrounding walls of the melting vessel or converter are used for calcination of the aggregates.

Optionally, in certain metallurgical manufacturing processes, the endothermic effect resulting from the calcination may also be deliberately exploited to lower the bath temperature. For this purpose, for example, the oxygen-containing sheathing gas and / or the conveying gas can be partially or completely replaced by inert gases. The highly exothermic decarburization reaction taking place by the reaction of the oxygen-containing gases with the carbon of the melt will then be partly or completely omitted. It is understood that the gas supply can also be carried out in such a way that a control of the temperature of the melt takes place in a predetermined process, in which the oxygen content of the shell gas and / or the delivery gas depending on process parameters of the manufacturing process such. the focal spot temperature and / or the temperature of the melt is varied elsewhere. If necessary, then the oxygen content of the conveying and / or jacketing gas can be increased and the proportions of inert gases can be reduced and vice versa. The additive to be used according to the invention can thus generally be supplied to the melt during the fresh phase of the metallurgical process, in particular the main fresh phase.

The jacket gas stream may contain ≥ 25 wt .-% or ≥ 50 wt .-% or ≥ 75 wt .-% oxygen, in certain process variants permanently or temporarily also ≥ 80, ≥ 90 or ≥ 95 wt .-% or even ≥ 98 wt .-% contain oxygen or practical be pure oxygen. The oxygen content of the jacket gas stream may be ≦ 95 to 98 wt .-%, optionally ≦ 80 to 90 wt .-% or even ≦ 60 to 70 wt .-%, optionally also ≦ 50 or ≦ 25 wt .-%. The oxygen content of the jacket gas and also of the delivery gas can be adjusted by using inert gases, for example ≤ 10 to 20 or ≤ 5% by weight of the gas, or virtually pure inert gases can be used. The inert gas to be used depends on the respective process conditions, it may for example be nitrogen, preferably argon. Since due to the strong endothermic calcination reaction of the additives used with high levels of volatile calcination components also reduces the bath temperature and the volatile calcination products such as water vapor and / or CO ₂ or reaction products thereof such as oxygen, hydrogen and CO a partial pressure reduction of the oxygen and / or the reaction products in By effecting the focal spot, it is also possible, if appropriate, to dispense with the addition of inert gases in order to control the bath and / or focal spot temperature according to the method of the invention.

Preferably, the delivery gas and / or the shell gas has a composition such that it is also inert with respect to the calcination of the precursor, i. H. no or only a minor reaction of the delivery and / or jacketing gas with the precursor and / or its calcination occurs or no or virtually no heat of reaction is released. This should be done for the period before the aggregate exits the feeder such as e.g. a lance, preferably in general.

If necessary, further solids can be added to the melt together with the at least one additive which contains at least one further alloying constituent, for example further alloy constituents, which may also be of a conventional type, such as ferroalloys, and / or slag Forming substances such as calcium and / or magnesium compounds (eg CaO, MgO, dolomite, etc.), silicates or quartz, without being limited thereto. The content of these further solids in the additive stream may be ≦ 50% by weight, preferably ≦ 20-25% by weight or ≦ 10-20% by weight, in particular also ≦ 5-9% by weight or ≦ 2 4% by weight. Optionally, the additive stream may be free of such further solids.

The aggregate flow supplied to the melt may contain other solids or constituents, such as carbons, hydrocarbons in solid, liquid or gaseous form or other reducing agents such as ferrosilicon, aluminum, ferroaluminum, etc. Preferably, however, the additive to be alloyed contains ≦ 10% by weight or ≦ 5% by weight of such solids or reducing agents, preferably ≦ 2 to 3% by weight or ≦ 1% by weight. The aggregate stream, optionally including gaseous components contained therein, and / or the jacket gas stream may also be free of (particulate) carbon, hydrocarbons and / or other reducing agents. The lance used for the supply of aggregates thus acts not or only to a minor extent in the manner of a burner, with any reactions to take place outside the lance.

The additive used, which may have a high content of chemically bound water, may be prepared for pneumatic conveying and / or gravity promotion suitable. The content of free, only physically bound water (residual moisture) hereby may be ≦ 5% by weight, preferably ≦ 2-3% by weight or ≦ 1% by weight, based on the total weight of the additive. Optionally, however, other types of conveying or feeding into the melt can be selected.

The aggregate may contain ≥ 60-70% by weight, ≥ 75-80% by weight or ≥ 85-90% by weight or else ≥ 95% by weight of the constituents (1) intended alloy components, (2) volatile constituents without negative metallurgical properties and (3) slag emulsions.

The solid additive used may be present in an average or maximum particle size of ≦ 10 mm, ≦ 3 to 5 mm or the like, optionally also in a finely divided form, such as a powder, e.g. with grain sizes of ≤ 0.5-1mm, or in the form of dusts. Optionally, the aggregate may also be in compacted or agglomerated form, e.g. in briquetted, pelleted or granulated form, wherein the briquettes, pellets, etc. burst due to the calcination reaction and evaporation of water and / or CO2 in the supply to the focal spot and can split themselves independently finely.

The method according to the invention can be in particular an AOD method. The melt vessel may each be an argon-oxygen decarburizer (AOD), Creusot-Loire-Uddeholm (CLU) converter, a vacuum-oxygen (VOD) converter or a Cr-converter. Optionally, the melt vessel may be a BOP or Q-BOP converter. Optionally, though less preferably, the process may be an electro-steel process, for example, an electric arc furnace method.

The alloy constituents to be introduced for adjusting the composition of the molten bath may contain ≥5-10% by weight or ≥20-25% by weight, ≥30-35% by weight or ≥40-50% by weight of the additives according to the invention , which may have high levels of chemically bound water or calcining components are supplied. Optionally, ≥ 75% by weight or about 100% by weight of the alloy constituents can also be supplied by the additives used according to the invention.

Depending on the size of the melt vessel or converter, the additive stream may be ≥ 100 kg / min, preferably 200-500 kg / min or more, in each case based on a melt of 100 to 120 tons of metal weight (ie without slag weight), with correspondingly being valid for larger amounts of melt.

The supply of high-aqueous additives according to the invention has proven itself, in particular with respect to nickel- and / or cobalt-containing additives, without being limited to these. The further statements thus relate to additives containing Ni, it being understood that, unless otherwise stated, the same may apply to Co-containing or other additives containing other main alloy constituents, for example Mn, Mo or Cr.

The additive to be used in the process according to the invention can thus be obtained by dissolving or leaching the relevant alloy constituents, in particular transition metals, from an ore, a suitably prepared ore or generally a product containing the alloy constituents, which may for example also be a waste material. After conversion of the respective alloying ingredient whose content is to be increased in the molten metal in the dissolved state, this can be precipitated by suitable means, for example by basic agents such as MgO, CaO, dolomite, etc., which can be optionally used as a slurry, ammonia or Ammonium salts and / or carbonates or the like. Depending on the application, the precipitation can be carried out at elevated temperatures or room temperature, in exceptional cases also under cooling. The resulting precipitate may thus be essentially a hydrous hydroxide, carbonate or a mixed hydroxide / carbonate. Generally, the precipitation of the alloying component forming transition metal is carried out without the use of S-containing precipitants or without means that lead to an S-entry in the precipitate to be recovered. In general, the alloying constituent is thus precipitated in a mold so that the resulting aggregate consists predominantly or practically exclusively of constituents which are present in the calcination of the Aggregate when it is transferred into the upper melting vessel space, apart from the alloy constituent predominantly or practically exclusively volatile components such as H ₂ O, CO ₂ , etc., unlike S-containing gases such as SO _{2 are} melt metallurgically harmless, and / or release slag-forming components , Optionally, the solution containing the alloying ingredient may be treated after dissolution or leaching of the ore or other suitable material to remove certain constituents, such as impurities. It is understood that, where appropriate, the enrichment of the transition metal from the respective source can be done in other ways, for example by extraction methods, even if they are less preferred.

The aggregate can then be treated in such a way that it can be conveyed pneumatically or by gravity; for this purpose, the additive can have a residual moisture of physically bound water of ≦ 5% by weight, preferably ≦ 1 to 3% by weight. It is understood that the residual moisture to be set depends on the respective process conditions.

The ready-to-use additive may have a content of ≥ 10-15 wt .-%, ≥ 15-20 wt .-% or even ≥ 25-30 wt .-% of volatile in the calcination metallurgically harmless ingredients such as H ₂ O and / or CO ₂ , for example, ≥ 30-35 wt .-% or ≥ 35-40 wt .-%. The content of these components is preferably ≦ 65-70% by weight, for example ≦ 60-65% by weight, ≦ 55-60% by weight or ≦ 55-60% by weight. The chemically bound water may in this case be present in particular in the form of water of crystallization and / or hydroxide groups. Optionally, the aggregate may be precalcined to remove, for example, already a portion of the chemically bound water of crystallization, but such a step is not mandatory. The statements made here can generally apply in the context of the present invention.

Particular preference is given to the essential metallic constituent or main constituent of the aggregate, whose content in the molten metal is to be increased, at least one or more transition metals. The transition metal with the highest content or the transition metals may be present individually or in total ≥ 25-30 wt .-% or 40-50 wt .-%, preferably ≥ 60-70 wt .-%, based on the total metal content of the aggregate, wherein here all metals, including Fe and slag-forming metals such as Ca, Mg, etc. are included. The transition metal or metals are preferably those which, under the present process conditions, are in contact with the melt or after incorporation into the melt reducible oxides, so that the at least one transition metal is converted into the melt by melt metallurgical reaction with the melt in metallic form. The melt thus acts on the transition metal oxide, which is formed by calcination of the additive, or possibly reducing itself to the additive itself. In addition, the transition metal present in oxidic and / or metallic form preferably has not too high or virtually negligible vapor pressure, so that losses due to evaporating metal and / or metal oxide are avoided or minimized. This includes losses due to a material discharge of the metal oxide or the aggregate itself by the escaping calcination gases. An essential component or main component of the additive may be at least one transition metal such as Ni, Co, V, Mo, Mn, Cr, Ti, Zr, W, Nb, Ta or a combination thereof, preferably the transition metal is Ni, Co, Mo or V In particular, Ni or Co may be present in combination, with Ni or Co being the main constituent.

For the production of nickel- and / or cobalt-containing aggregates, it is particularly advantageous to use leaching of laterite or laterite ores, for example saprolite. However, the most weathered product laterite is preferred. For lateitic nickel ores, two types can be distinguished: a very iron-rich Ni-limonite ore containing about 1 to 2% by weight of nickel bound to goethite, or nickel-silicate ores often containing more than 2% by weight of nickel; which is bound in silicates, in particular to serpentine. It is understood that other suitable sources, in particular also ores, are to be used for other transition metals.

For the leaching of Ni / Co, in particular acids can be used, for example sulfuric acid. The leaching is preferably carried out by heap leaching. The leaching can generally be carried out at atmospheric pressure or at elevated pressure, for example by high-pressure acid leaching. Optionally, other methods such as biological leaching, ammonia / ammonium leaching and the like may also be used. This may generally apply to other transition metals derived from ores or other sources. Preferably, the leaching is carried out without the use of sulfides and / or chlorides, which may also apply to the other process steps for the production of the additive.

From the resulting solution or alkali may be previously separated by suitable methods cobalt, for example by means of suitable complexing agents such as phosphonic acids, etc. This also generally applies to the separation of other undesirable components such as unwanted alloying constituents, both for the production of Ni-containing or other transition metal-containing aggregates. Optionally, nickel and cobalt may then be co-precipitated to give so-called mixed precipitates (MHP). This applies accordingly to other mixed transition metal precipitation.

The nickel-containing additive may have a nickel content of ≥ 5-10 wt .-%, for example ≥ 15 to 17 wt .-% or ≥ 20 to 23 wt .-%, optionally also ≥ 25 to 27 wt .-%, including the content of residual moisture or in each case based on a substance having a residual moisture content of about 0 wt .-%. The nickel content is typically ≦ 50-55 wt .-% or even ≦ 40-45 wt .-%, but may also be up to about 60-65 wt .-% or higher. The data relate to the additive to be used in the smelting metallurgical process. The same can also apply to Co-containing aggregates or other first transition metal period transition metals such as V, etc., including mixed aggregates containing two or more alloying constituents, such as Ni / Co aggregates, with higher-grade transition metals, such as Mo, taking into account the ratio the atomic weights of the transition metal of the higher period to that of the first period such as Ni applies.

In particular, the following information relates to a Ni / Co-containing aggregate, which is produced in particular by laterite leaching, but may also generally be considered within the scope of the invention.

The additive can chemically bound water in the form of water of crystallization and / or hydroxide groups in a proportion of ≥ 5-10 or up to 11 wt .-% or ≥ 15 to 21 wt .-%, optionally also ≥ 25 to 30 wt .-% or ≥ 35-40 wt .-%, which may also generally apply to be used in the invention additives. Preferably, the aggregate contains no more than 50-55% by weight or 60-65% by weight of water (including in bound form). If the aggregate is in the form of carbonate or mixed hydroxide / carbonate, the contents shall be deemed to correspond to the content of CO2 and / or chemically bound water.

The sulfur content of the additive is preferably ≦ 5-10% by weight, in particular ≦ 4% by weight or ≦ 2-3% by weight. Preferably, the sulfur content is ≦ 0.5-1% by weight or ≦ 0.2-0.3% by weight. The same can also apply to the content of Cl. This can each generally within the scope of the invention.

If the additive alone is to be used to alloy nickel, vanadium and / or molybdenum in the melt, the Co content is preferably ≦ 2.5-2% by weight, ≦ 1.75-1.5% by weight or ≤ 1.25-1 wt%. In particular, this applies when the aggregate is used to alloy nickel and e.g. Ni is present as the main constituent. The Co content is therefore uncritical with respect to other co-sources of the melt, so that there are no restrictions on the amount in which the aggregate can be used in the respective process in order to avoid undesirably high Co contents ,

Preferably, the content of P, Cu, Sn, Pb, Nb, As, Cd and / or Pd in the aggregate is limited to those values not limited to the amount of aggregate to be added to the respective melt, by the upper limits of said components in the melt to be able to comply. If only Ni is to be alloyed by the additive, this also applies to the components Co, V, Mo, and vice versa. Because the additive can be obtained via an aqueous solution of the respective desired transition metal, the contents of said components can be comparatively easily controlled by known means.

In addition to the main alloying constituent, the aggregate may contain other alloying constituents, such as cobalt (in the case of a Ni aggregate) or nickel (in the case of a Co aggregate), manganese, etc., if these elements are desired or not interfering with the intended use. In the case of a laterite leached Ni and / or Co-containing additive may further contain manganese (for example, ≥ 0.25 to 5 wt .-% or ≥ 1 to 2 wt .-%), wherein the content ≤ 7 , 5 to 10 wt .-% or ≤ 5 wt .-%, cobalt with proportions of ≥ 0.1 to 0.25 wt .-% or ≥ 0.75 wt .-%, wherein the cobalt content ≤ 3 to 5% by weight or ≤ 2 wt .-% may be. The content of alloying agents, including iron, in this case ≥ 1 to 2 wt .-% or ≥ 3 wt .-% and can be ≥ 15 wt .-%, ≤ 10 to 12 wt .-% or even ≤ 8 to 10 wt .-% amount. This also applies generally in the context of the invention.

The aggregate may further contain slag-forming constituents such as Ca, Mg. The content of the slag-forming constituents or the content of Ca and / or Mg in the aggregate may be ≥ 0.5 to 1 wt% or 1.5 to 2 wt%, for example ≥ 3 to 5 wt% , based on the additive free from residual moisture and in each case based on the weight of the metal. The slag-forming components or Ca and / or Mg may be in a form suitable for the melt-metallurgical process, e.g. as oxide, hydroxide and / or carbonate but also silicate. The content of slag-forming constituents may be ≦ 25% by weight or ≦ 15 to 20% by weight, in particular ≦ 10 to 12% by weight or ≦ 6 to 8% by weight, based on that to be used in the process Add additive without residual moisture. The stated contents may be understood as including Mn, Cr, Si, Ti, Si and / or Fe, or excluding these. The above can generally be considered within the scope of the invention.

The invention is explained below with reference to an embodiment, wherein the figure is a schematic representation of the melting vessel (converter) with feeding the aggregate in the form of a lance.

FIG. 1 shows an arrangement for carrying out the method according to the invention, wherein in a melting vessel 1, for example in the form of a converter, a molten metal 2 is provided, which is covered by a slag 3. The melt may be an iron alloy, for example one for producing a Ni-alloyed steel having a nickel content of 1.5 to 30 wt .-%, in particular common Ni or Cr / Ni steels such as 18/8 Cr / Ni steel and / or steels with a P and S content of <0.005 wt .-% or <0.0035 wt .-%, which may apply regardless of the embodiment. The slag is in this case a conventional slag for producing the respective alloy, for example containing high proportions of chromium oxide, MgO, CaO and / or SiO 2, which can intervene in addition to the coverage of the melt in the metallurgy of the melt.

As a feed device for introducing the additive into the melt, a preferably water-cooled lance 4, which is arranged above the slag, is provided, which preferably penetrates into the upper region of the melting vessel 1. The lance 4 consists of a central tube 5 for injecting the solid aggregate into the melt, which is surrounded on the outside by an outer tube 6 or a plurality of circumferentially around the central tube arranged individual tubes, for example ≥ 2-3 or ≥ 4-6 individual tubes. The pipe ends can with nozzle-like outlet openings, z. B. be provided in the form of Laval nozzles in order to inject the aggregate at high speed, preferably supersonic speed, into the melt can. The solid, pneumatically conveyable additive is thus, optionally injected through the central tube in the melt by means of a suitable conveying gas such as oxygen, through the outer tubes 6, a gas stream is ejected in the direction of the molten metal, which sheathed and focused the emerging from the central tube 5 solids flow , The gas jacket 7 serves, on the one hand, to materially shield the solids flow 8 from the environment and to further focus, in particular also with regard to the high proportion of volatile constituents which form during the calcination of the additive. In particular, the gas stream also serves to penetrate the slag at least almost or completely and thereby to produce a slag-free focal spot 9, in which the molten metal 2 is thus exposed. The temperature of the melt in the region of the focal spot can be, for example, 2,400 to 2,600 ° C.

The aggregate is in this case injected into the melt at such a rate that calcination of the aggregate takes place with elimination of H ₂ O, CO ₂ and optionally other volatile constituents, only at or after discharge of the aggregate from the lance nozzle. The decomposition of the additive takes place here due to the high ambient temperatures, eg. B. the heat of radiation of the Schmelzgefäßwandung 1 a, the molten metal and the like predominantly or completely on the way from the lance nozzle 4 a to the molten pool. Any non-calcined fractions of the aggregate are calcined in the focal spot 9 or the impact zone 10 onto the molten metal. During calcination, all volatiles such as H ₂ O, CO ₂ and the like are thus volatilized, so that only the non-volatile constituents, such as metal oxides, enter the melt and are taken up by it.

The gas passed through the central tube 5 via the flow of solids may be air, a gas depleted of oxygen or inert gas. The jacketing gas performed by the outer tubes 6 may be air, an oxygen-enriched gas or pure oxygen, an inert gas, or mixtures of these. The oxygen content must be adapted to the respective process conditions such as the heat balance of the melt metallurgical process. Optionally, further solids such as alloy constituents, slag formers or the like can be supplied to the melt with the additive stream, without this being absolutely necessary. Preferably, the additive stream does not contain reducing agents such as carbon, ferrosilicon, aluminum or the like. In particular, the process according to the invention can be an AOD process, optionally also an electrometallurgical process.

Surprisingly, it has been found that the feeder of aggregates for adjusting the alloy content of the melt using highly hydrous substances is possible, whereby the manufacturing cost of the respective alloy can be significantly reduced, in particular because the aggregate cost-effectively and other costly process steps such as slag work to reduce the sulfur content of the melt, etc. avoided can be. Such a process is especially given by the fact that the additive is injected directly into the very hot, slag-free focal spot.

The aggregate can be obtained in particular by leaching of laterites, for example by leaching using sulfuric acid at atmospheric pressure or at elevated pressure, but optionally also by other leaching methods. From the acidic liquor, the nickel-containing additive can then be precipitated by suitable precipitating agents such as a MgO and / or CaO slurry, by addition of carbonates such as sodium carbonate, calcium carbonate, dolomite, etc., by addition of ammonia or ammonium compounds to form essentially a nickel hydroxide. Nickel carbonate or mixed nickel hydroxide / carbonate to produce. The reaction with the precipitating agent can be carried out at elevated temperatures, for example at 30-80 ° C or higher, in suitable periods of, for example, a few minutes to 1 hour. Optionally, in a preceding process step cobalt can be separated by suitable methods, for example by extraction methods.

The aggregate can be pre-dried to a residual moisture, which allows a pneumatic delivery of the same. Residual moisture here is to be understood as meaning physically bound water which can be removed at temperatures of ≦ 120 to 150 ° C. in a suitable period of time, for example in one to two hours. The aggregate can be prepared for a gravity feed suitable.

Optionally, the aggregate may be mechanically worked up to obtain a suitable grain size or size, optionally also compacted or agglomerated.

In the case of a nickel-containing additive, the nickel content thereof is typically about 15 to 55% by weight, in particular about 20 to about 40% by weight, based on the predried aggregate (without residual moisture). The content of chemically bound water in the form of water of crystallization and / or hydroxide is typically 30 to 50 wt .-% or 40 to 50 wt .-%. It is understood that optionally the aggregate can be precalcined at higher temperatures in order to reduce the water and / or carbonate content, without this being absolutely necessary.

In the following two typical analyzes of the nickel-containing additive are given. The products were each obtained by leaching of laterites by means of 80% strength sulfuric acid at 90 ° C. for 0.5 hours (about 20 g of ore, slurried in 80 g of water, 100 g of sulfuric acid). Leaching times of <1 or <0.75 hours have generally been found to be advantageous. The liquor was partially neutralized by dolomite and then mixed with a MgO slurry to produce a nickel hydroxide precipitate.

The filtered precipitate was dried to a residual moisture of about 1.5 wt .-% (at 120 ° C for 2 hours), the content of chemically bound water was 55 wt .-% (composition 1) or 45 wt. % (Composition 2), calculated in each case as the weight loss of the material dried to a residual moisture content of about 0% by weight after thermolysis at 750 ° C. for 4 hours until constant weight. It will be appreciated that the thermolyzed material may still contain a level of carbonate or other ingredients which decompose only at elevated temperatures.

It is understood that the composition of the additive may vary depending on the ore or nickel-containing starting material used. The following analysis data refers to a material that has been dried at 120 ° C for 2 hours to a residual moisture of about 0% by weight (ie, including water of crystallization). Composition 1 (in% by weight) Ni 24 al 0.75 Ca 0.75 Co 1.5 Cr <0.05 Fe 0.75 Mn 4.0 mg 6.0 Water content (crystal water) 50 Ni 38 al <0.05 Ca 2 Co 0.5 Cr <0, 05 Fe 2.5 Mn 1.5 mg 2.5 Water content (crystal water) 40

It is understood that in general, apart from ores, if appropriate, other substances for the preparation of the invention used It is possible to use additives from which nickel-containing or transition metal-containing aggregates can be produced in a corresponding manner, and in which the transition metals can preferably be obtained by suitable leaching on the basis of a water-containing leaching agent.

Furthermore, it is understood that the inventive method is not limited to the use of Ni / Co-containing additives, but also other alloying constituents, in particular transition metals such as Mo, V or the like can be added in a corresponding form of the molten metal. Preferably, in each case the additives are each injected from the top of the melting vessel in this in a region of the molten metal of very high temperature, in the case of slag-covered melts in a slag-free focal spot.

Claims (26)

1. Method for the production of a metal melt comprising at least one base metal containing iron at a percentage of ≥ 10% by weight and at least one further alloying component, the production taking place in a melting pot with slag covering the melt, wherein at least one additive containing the above-mentioned further alloying component in the form of a transition metal is added to the melt as a solid to enrich the same with the alloying component, wherein the additive comprises:

   (i) as a further alloying component a transition metal chosen among nickel, cobalt, vanadium or molybdenum or a combination of two or several thereof, and that percentage of nickel, cobalt, vanadium and/or molybdenum alone or in combination in said additive is 15 to 60% by weight,

   (ii) 20-60% by weight of a melt-metallurgically harmless volatile component in the form of H₂O (including chemically combined water in the form of water of crystallization and/or hydroxide groups) and /or CO₂,

   (iii) 0.5-25% by weight of slag formers,

   (iv) ≤ 5% by weight of sulfur,

   wherein said additive is obtainable by the preparation of ores, waste products or other products containing the said alloying component under conversion of the alloying component to a dissolved state, the precipitation of the alloying component as hydrous hydroxide, carbonate or mixed hydroxide/carbonate, and additional steps if required,
   and wherein the additive containing the alloying component is directly supplied to the metal melt while producing a slag-free focal spot of the slag-covered metal melt.
2. Method according to claim 1, characterized in that the additive is supplied to the melt in such a manner that a calcination or decomposition of the additive takes place at least substantially only during or after leaving a feeding device that is provided and prior to or during the impingement on the metal melt or in an impact zone.
3. Method according to one of the claims 1 or 2, characterized in that the additive is supplied to the melt in a solid material stream enveloped by a gas stream.
4. Method according to one of the claims 1 to 3, characterized in that the focal spot has a temperature of ≥ 1,750°C.
5. Method according to one of the claims 1 to 4, characterized in that the enveloping gas stream has an oxygen content of ≥ 25% by weight or is oxygen, at least substantially.
6. Method according to one of the claims 1 to 5, characterized in that the enveloping gas comprises for ≥ 75% by weight at least one inert gas or consists of one or more inert gases, at least substantially.
7. Method according to one of the claims 1 to 6, characterized in that the solid material stream containing the additive that contains the alloying component comprises further additives that contain alloying components and/or further metallurgically active substances and/or slag-forming substances.
8. Method according to one of the claims 1 to 7, characterized in that the solid material stream containing the alloying additive comprises ≥ 10% by weight of reducing agents, including carbon, hydrocarbon and ferrosilicon.
9. Method according to one of the claims 1 to 8, characterized in that ≥ 5 to 10% by weight of the alloying component, which is the main component of the additive, are fed to the melt via said additive.
10. Method according to one of the claims 1 to 9, characterized in that the additive contains nickel and/or cobalt as a main alloying component.
11. Method according to one of the claims 1 to 10, characterized in that the additive substantially is a crystallization water-containing salt, hydroxide, carbonate or mixed hydroxide/carbonate.
12. Method according to one of the claims 1 to 11, characterized in that the additive consists for ≥ 70-80% by weight of the components (1) alloying components desired as intended, (2) volatile components negative meltmetallurgical characteristics, and (3) slag formers.
13. Method according to one of the claims 1 to 11, characterized in that additive contains percentages of further alloying components.
14. Method according to one of the claims 1 to 13, characterized in that the method is an AOD method.
15. Transition metal-containing additive for the production of transition metal-containing alloys in melt metallurgical processes, wherein the additive is present as a solid and comprises:

    (i) 15-60% by weight of said further alloying component, which is a transition metal chosen among nickel, cobalt, vanadium or molybdenum or a combination of two or more of the same,

    (ii) 20-60% by weight of melt-metallurgically harmless volatile components in the form of H₂O (inclusive of combined water in the form of water of crystallization and/or hydroxide groups) and/or CO₂,

    (iii) 0.5-25% by weight of slag formers,

    (iv) ≤ 5% by weight of sulfur,

    and wherein the additive is obtainable by the preparation of ores, waste products or other products containing the said alloying component under conversion of the alloying component in a dissolved state, by the precipitation of the alloying component as a hydrous hydroxide, carbonate or mixed hydroxide/carbonate, and by additional steps if required.
16. Additive according to claim 15, characterized in that the additive includes ≥ 20% by weight of combined water in the form of water of crystallization and/or hydroxide groups.
17. Additive according to claim 16 or 17, characterized in that the content of sulfur is ≤ 2% by weight.
18. Additive according to one of the claims 15 to 17, characterized in that the additive contains further alloying components.
19. Additive according to one of the claims 15 to 18, characterized in that the content of said further alloying components is ≥ 3% by weight.
20. Additive according to one of the claims 15 to 19, characterized in that the content of slag formers is ≤ 20% by weight.
21. Additive according to one of the claims 15 to 20, characterized in that the additive is present in a state conveyable pneumatically or by gravity or in compacted state.
22. Additive according to one of the claims 15 to 21, characterized in that the additive is obtainable or obtained by leaching laterite ore laterite-like ores, preferably by using acids.
23. Additive according to one of the claims 15 to 22, characterized in that the additive is obtainable or obtained by the precipitation of hydroxide and/or carbonate from an aqueous solution, if necessary after previous preparation of the solution.
24. Additive according to one of the claims 15 to 23, characterized in that after a thermal treatment at 705°C, said additive suffers from a weight loss of 20 to 60% by weight until it has reached its constant weight.
25. Use of a transition metal-containing additive according to one of the claims 15 to 24 for the production of transition metal-containing alloys in meltmetallurgical processes, wherein the additive according to the claims 15 to 24 is supplied to a metal melt containing at least one base metal with at least 10% by weight of iron to enrich the same with the alloying component, wherein the production of the alloy takes place in a melting pot with slag covering the melt while feeding the additive and wherein the process is an AOD process, CLU process, VOD process, BOP process or Q-BOP process.
26. Use of a transition metal-containing additive according to claim 25 in a method according to one of the claims 1 to 24.

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