The method of processing slag or slag mixtures
The invention relates to metallurgy, in particular to a method of processing steel slag or mixtures thereof. The method of processing slag or mixtures of slag containing iron oxide more than 5 wt.% includes supply of steelmaking slag, mixed if necessary with other toxins in the liquid metal bath, which is used tub of steel with a content of less than 1.5 wt.%, mostly less than 0.5 wt.%, after the filing of steelmaking slag bath of steel Naegleria to the carbon content of > 2 wt.%, mostly more than 2.5 wt.%, by introducing carbon or media carbon. In addition, the bath of steel is produced by refining baths of cast iron with oxygen to carbon content less than 0.5 wt.%. The bath temperature set above S. The basicity of the slag during processing is reduced to less than 1.5 and/or set the content of aluminum oxide in the slag is more than 10 wt.%. The weight ratio of slag and steel is 1:3-1:6. To which is supplied to the slag add the native oxide of iron to establish their content in the slag above 8 wt.%. In the liquid metal bath melt additives - scrap, ore fines, sponge iron. Technical Reza, prevent the formation of foamy slag and releases toxins from the bath. 8 C.p. f-crystals, 2 tab.
The invention relates to a method of processing steel slag or mixtures of slag containing iron oxide >5 wt.%, in which steelmaking slags, if necessary, mixed with other wastes and are served in the liquid metal bath.
From application EP 666 930 B1 is already known method of production of steel and hydraulically active binder, in which the steel slag is subjected to recovery when using cast iron and especially due to the carbon in the cast iron, so that, on the one hand, is refining a bath of liquid iron, and the carbon content in the bath is reduced, for example, to less than half of the carbon in the blast furnace pig iron, while iron oxide from steel slag is recovered in the iron and into the liquid metal bath. There is a method mainly been optimized in the sense that small quantities of liquid pig iron can be restored, at least partially, large quantities of steel slag. Significantly reduce the execution time of the method by introducing uvelichenie liquid pig iron usually are dealing with lower temperatures, owing to this it is problematic to obtain rheological properties of the slag and, secondly, when the supply of liquid steel slag in large quantities of pig iron occurs unusually violent reaction, which under unfavorable rheological properties of toxins can lead to the formation of undesirable foaming of slag or waste. Due to the formation of such foamy slag again slows down the reaction, which then requires a relatively long processing time.
The objective of the invention is the improvement of the above method, so that when a relatively short reaction time optimal use of working the heat released in the process, and support during recovery fluidity of steelmaking slag, which reliably prevents the formation of foamy slag and at the same time prevents local amplification reactions with unwanted waste.
To accomplish this, the method according to the invention mainly consists in the fact that, as the liquid metal bath is used tub of steel with a content of<1.5 wt.%, mainly <0.5 wt.%, and that tub of steel after the filing of steelmaking slag NAU is the beginning of recovery slag is liquid metal bath with a relatively low carbon content, provides the steel bath, allowing prevented local extremely violent reaction and deep transformations, which produce large quantities of gas, and therefore no longer produced foamy slag. In order to conduct this type of method is economical and largely autothermal is particularly preferable to directly use the heat released during the process. Therefore, it is preferable to conduct the method according to the invention so that was attended by a bath of liquid pig iron, which is using the refined oxygen content<0.5 percent, with the bath temperature set above S, especially about S, refined bath of steel injected liquid steel slag and after equalization of the temperature in the bath is injected carbon, while adding containing SiO2corrective substances, such as blast-furnace slag, silica sand, and/or containing Al2O3corrective substances type of bauxite to reduce the basicity to <a 1.5% or determine the content of Al2O3>10%. Due to the fact that education baths of steel, which subsequently serves steelmaking slags, for the treatment, the warmth of the process, released during the refining through which heated the initial bath of pig iron, used for temperature compensation with steelmaking slag, which must be done, and due to the high temperature corrective substances and, in particular, corrective substances containing SiO2as those that are required to establish the desired basicity, can melt and make the slag. In the bath of steel, respectively, heated to temperatures above S through the refining process, or directly enter at least the part containing SiO2corrective substances required to establish basicity, so these corrective materials are heated and at least partially melted, or alternatively indirectly impose steelmaking slags. With the liquid steel sakami can be added containing SiO2corrective substances. By adding such substances and, in particular, with the ability to simultaneously introduce additives such as, for example, cooling scrap or ore fines, in the process directly ispol add the native oxide of iron, at the same time, the iron oxides are exposed to significant restoration and similar carriers of iron oxide, which under normal conditions can be processed only with difficulty, such as ore fines, produce large quantities of liquid iron.
In conclusion, due to the introduction of steelmaking slag now achieve a permanent increase in carbon content in the bath of steel and the desired degree of recovery, and media carbon is blown into the bath of steel. The resulting carbon monoxide can be further subjected to afterburning, so you can fully implement deep autothermal process and to refuse additional energy input. The method according to the invention it is expedient to conduct so that the basicity was 1.1 to 1.4, and content With baths >2.5 per cent.
It is also preferred to carry out the method according to the invention in such a way that the steel slag is added to the bath of steel in a weight ratio of 1:3 to 1:6, mostly about 1:4, with a relatively large amount of the metal bath, which after refining process is at a high temperature level, which provides the necessary heat de 150-250 kg/t of steel slag and bauxite in the amount of 200-300 kg/t of steel slag, with selected additives input you can provide sufficient homogenization and full melting and interaction of the fillers in the slag, resulting in possible directly to obtain a product suitable for use in cement technology.
Especially preferred is the addition of a liquid slag ore fines or carriers of iron oxide to their content above 8%, so in one way you are able to accomplish the desired recovery of steelmaking slag and difficult recoverable ore and use the additive for regulating the desired reaction temperature. With the same purpose, it may be desirable to simultaneously melt in the liquid metal bath during refining or after the additive type of cooling scrap or ore fines.
Especially preferred is the addition of native iron oxide with acid gangue minerals, making simultaneously with the recovery of metallic iron at the expense of such native oxide of iron is possible to appropriately reduce the basicity is favorable for manufacturing cement. However, alsoobe the following flow of the liquid slag or mixtures of slag in the bath of steel, at least partially simultaneously with the carburizing baths of steel, and is preferably added in liquid slag or slag mixture corrective substances containing Cao, Al2O3and/or SiO2.
In the end, due to the refinement carried out in the first stage, is achieved particularly favorable energy balance. Thus a significant amount of energy released during the refining bath of pig iron, which can be used directly in the process. For establishing the desired values of the target basicity in principle use any slag enriched in SiO2and in some cases, you can enter the adjustment substances containing SiO2.
Below the invention is explained in more detail using an example embodiment of the invention.
The Converter has processed 8 tons of liquid pig iron at the expense entry 280 nm3oxygen through the bottom nozzle with getting baths of steel. Liquid pig iron has a carbon number of 3.9 wt.%, silicon, about 0.3 wt.%, the rest is iron, approximate analysis. After refining, in which the exothermic reaction occurring at a temperature bath S, distiguish. In this liquid bath of steel were loaded into further 3 t liquid steel slag. The latter had the following composition (table.1):
Due to the relatively low carbon content in the bath of steel immediately after the supply of liquid steel slag significantly reduced the interaction of substances with the reduction reaction of the metal oxides contained in the steelmaking slag. If directly applied pig iron in appropriate proportions, it led to the rapid release of significant quantities of CO, which could lead to severe foaming of the slag or to their release.
After the filing of steelmaking slag in the bath of steel is temperature equalization between the slag and metal bath, resulting in a solid slag components can again fully pass into a liquid state. Temperature equalization leads to temperatures of about S.
In addition to the equalization of temperature in the bath of steel was breathed 580 kg of coal at a rate of 25 kg/min, then was added 370 kg of quartz sand with a speed of 24 kg/min and 535 kg of bauxite with a speed of 28 kg/min
By the end of the desired reaction recovery remained W is th iron may naturally, an appropriate corrective substances or in accordance with the composition of steel slag also contain other than iron, metals.
Using corrective substances was achieved, firstly, the regulation in order to obtain the desired basicity, which seems appropriate for further application of processed slag in cement and there was also a reduction of the metallic oxides, as shown by subsequent data indicative of the analysis (table.2):
Obtained similarly processed steel slag can be granulated in water and are used as grinding in composite cements.
Due to the heat released during the decarburization, it is possible to heat and melt corrective substances necessary for obtaining the desired basicity or to establish a desirable composition for grinding, applicable to the technology of producing cement. Arising in this case is undesirable high temperatures can again be reduced to the desired temperature recovery by adding cooling scrap, ore fines or downloadable substances from process straight voicenote from as necessary, you can dorigatti carbon monoxide formed during the restoration, above the slag bath. Due to this it is possible to simultaneously carry out processing of an increased number of iron ore without any additional power consumption.
1. The method of processing steel slag or mixtures of slag containing iron oxide more than 5 wt.%, including supply of steelmaking slag, mixed if necessary with other toxins in the liquid metal bath, wherein as the liquid metal bath is used tub of steel with a carbon content of less than 1.5 wt.%, mostly less than 0.5 wt.%, after the filing of steelmaking slag bath of steel Naegleria to the carbon content of more than 2.0 wt.%, mostly more than 2.5 wt.%, by introducing carbon or media carbon.
2. The method according to p. 1, characterized in that the bath of steel is produced by refining a bath of pig iron with oxygen to carbon content less than 0.5 wt.%, moreover, the temperature of the bath of steel set above S, mainly about S, then in a bath of steel serves liquid steel slag and after equalization of the temperature of the injected carbon in the bath, and sijainnin slag, quartz sand, and/or set the content of aluminum oxide in the slag is more than 10 wt.% by adding corrective substances containing aluminum oxide, for example, bauxite.
3. The method according to p. 1 or 2, characterized in that the basicity of the slag is brought to a value of 1.1 to 1.4, and the carbon content in the bath of steel is brought to more than 2.5 wt.%.
4. The method according to any of paragraphs.1-3, characterized in that the weight ratio of the added slag and steel is 1:3 to 1:6, mostly about 1:4.
5. The method according to any of paragraphs.2-4, characterized in that type of quartz sand in the number of 150-250 kg/t of slag and/or bauxite in the amount of 200-300 kg/t of slag.
6. The method according to any of paragraphs.1-5, characterized in that the liquid metal bath serves the liquid slag mixture, to which add the native oxide of iron, such as ore fines, for the establishment of the content of iron oxide is above 8 wt.%.
7. The method according to any of paragraphs.1-6, characterized in that after the supply of liquid slag or slag mixtures in the liquid metal bath of steel add the native oxide of iron, for example, the lean ore or ore fines with acid gangue mineral is at least partially simultaneously with the carburizing baths of steel.
8. The way p is containing a series of oxides of calcium, aluminum and/or silicon.
9. The method according to any of paragraphs.1-8, characterized in that the liquid metal bath during or after melt refining additives, for example, cooling scrap, ore fines or sponge iron.