MXPA98000765A - Process to produce puzolanas, high-oven synthetic cents, clinkers of belita or alita, as well as raw iron alloys from oxidic slaughters and a provision to carry out such proc - Google Patents

Abstract

The present invention relates to a process for producing pozzolans, slag from synthetic blast furnaces, belite clinker or alite as well as crude iron alloys from oxides slag by reducing the oxidized liquid slags on top of the iron bath, where the carbon blows in the iron bath through the submerged nozzles, with the aim of maintaining a carbon content between 2.5 and 4.6% per

Description

PROCESS TO PRODUCE PUZOLANAS, HIGH OVEN SCRIBES SYNTHETIC, CLINKERS OF BELITA OR ALITA, AS ALLOYS OF RAW IRON FROM OXIDIC SCRAPS AND A PROVISION TO CARRY OUT SUCH PROCESS The invention relates to a process for producing pozzolans, blast furnace slags, belite clinker or alite, as well as raw iron alloys from oxidic slag by reducing the oxidized liquid slag in an iron bath and an arrangement to carry out said process. German Patent No. 26 48 290 describes a process for treating iron-containing metallurgical slags, consisting essentially of mixing blast furnace slag with slag from steel work in order to obtain a final product having a suitable composition. In doing so, it is particularly advantageous to carry out the mixing process through an oxygen feed lance designed as an agitator with the objective of oxidizing the iron granules and producing a homogeneous mixture. The synthetic slag produced has physical properties superior to those of blast furnace slag, therefore it is excellently suited for grading. The residues of free lime correspond approximately to those of the blast furnace slag.

German Patent No. 26 11 889 mentions a process for producing hydraulic lubricants from metallurgical waste and lime. In an integrated steel plant, approximately 400 kg of metallurgical waste is formed per tonne of crude iron in the production route from metal to steel, 48% is blast furnace slag and 35% is slag from steel works. The balance includes waste, waste and metallurgical dust. The idea on which the invention is based consists of mixing these metallurgical wastes with lime in appropriate proportions of weight in the liquid state and quenching the melt to form granules, with the aim of producing a cement clinker. Basically, all known converters in the steel plant are suitable for mixing and melting while fuel and oxygen are supplied. However, the low blow converter, OBM is particularly advantageous, since its lower nozzles are suitable for introducing fuel and fine lime. The melting process is carried out in an oxidizing manner, the oxides are present in the finished melt in the dissolved state. A process for producing cement from metallurgical slags is known from South African Specification Patent 94/0521. According to this process, acidic high-ash slags are mixed with slag from basic steel works in liquid state at high temperatures, exceeding 1700 ° C. In order to produce an advantageous cement clinker, the mixing ratio can vary between 30% and 80% of blast furnace slag and between 20% and 70% slag to the converter. According to this invention, the melting of the mixed slag is cooled slowly until it reaches a temperature of 1000 ° C in a first step and, after that, more quickly in a second step, the final solidified product is finally ground. South African Specification Patent 94/05222 shows and describes a process for producing crude iron and cement clinker. A melting gasifier comprising a fluidized coal bed is provided, in which the necessary energy is generated by supplying oxygen, an iron bath comprises a slag layer which is present therein. First, the limestone and iron metal are loaded in the previously heated tank. There, they are dried and calcined and finally, they are synthesized with the calcium ferrite to the greatest extent before placing it in the melting gasifier. The heat for preheating the tank is generated by burning the waste gases from the melting gasifier by means of the previously heated air. The molten iron from the reduced iron metal collected within the melting gasifier and the liquid slag in the cement clinker composition are removed from the melting gasifier in the liquid state. The proposal of the invention is to introduce into the melting gasifier toxic waste substances which contain, for example, dioxin, furan, PBC and chlorides. The slag to the liquid steel work converter can likewise be added in an amount acceptable for the production of cement clinker. Another process for producing hydraulically active steel and binders, for example cement, is described in Australian Patent No. 400 037. The idea of this invention resides in refining crude iron by adding steel slag and using the high iron oxide content of steel. the steel slag with the aim of eliminating carbon and silica from crude iron. For example, the steel slag is melted with 0.5 parts by weight of liquid crude iron and this mixture is maintained at 1660 ° C for six hours, therefore it is able to reduce the FeO and MnO content of the steel slag from 30.5% up to 10.5%. The final slag obtained can be used as a cement clinker. When processed oxides slag, slag containing chromium oxide, in particular, is a problem in the production of ground cement admixtures since the chromium content of these slags would have to lie substantially below 500 ppm. In relation to the parameters required from the metallurgical slag point of view to work with oxidic slags, it has been recognized so far that the iron oxide content of an iron bath used for the reduction can be of great importance. With different fillers, the reduction in an iron bath results in final products that are not able to be precisely controlled and, in particular, when slag containing chromium oxide is used, the removal of the necessary chromium can not be easily secured with an iron bath. However, it is known that blowing carbon in the iron bath, where this is done, has proven that a very high carbon content will result in local overheating and negative reactions in the course of the reduction. The control of the precise process, and easy, has not yet been achieved due to the parameters observed in the reduction of oxidic slag. The invention seeks to provide a simple and economical mode of a process using conventional reactors, such as low blow converters without applying blow technologies that have not been tested and hot-setting technologies, which allow the values required to remove the chromium In an effective way, which is going to be precisely observed, it is a primary objective to carry out the process quickly and simply. The economy will be improved, in particular, by avoiding regional overheating as well as excessive foam. In addition, the carbon and oxygen breath is secured in a way that refines the raw iron while the carbon blow is avoided with conventional hot-blast and blow-off technologies, and simultaneously the respective amounts are reduced, thus avoiding that the coal is blown through and that the iron is discharged as well as the excessive production of foam during the course of the process. To achieve this objective, the process according to the invention consists essentially in that the carbon is blown in the iron bath through submerged nozzles in order to maintain a carbon content between 2.5 and 4.6% by weight. Due to the fact that the carbon content is maintained within narrow limits, which varies between 2.5 and 4.6% by weight, over saturation and, therefore, the carbon flotation, which involves the risk of being burned subsequently, is avoided. in the boundary layer, on the one hand. Furthermore, it is observed that the removal of the chromium is done in a surprisingly fast way by keeping the carbon content within the indicated limits. While the reactions of the chromium removal so far, take 15 to 30 minutes, it has been shown, surprisingly, that the removal of the chromium can be completed within a few minutes when the concrete limit values are observed. indicator for carbon content. In an advantageous way, the process is carried out under a carbon content that is adjusted between 2.5 and 3.2% by weight. In a particularly advantageous way, the height of the iron bath is adjusted to be between 300 and 1200 mm, where, after exceeding the iron bath height of 1200 mm, the raw iron is capped and the amount of carbon blown it is controlled as a function of a measuring cylinder. When adjusting that the height of the iron bath is between 300 and 1200 mm, the operation can be carried out at a normal pressure by means of conventional nozzles, without involving the risk of blowing through them. By using conventional nozzle technologies, well-measured pressure controls can be applied, which will ensure that the amounts of oxygen and carbon can actually be controlled, in view of safely maintaining the desired carbon values in the iron bath . The control of the process according to the invention, in a particularly simple form, allows a simple control and better consistencies of the respective desired final products. The coercive measures provided, in particular, for the complete chrome removal operation and as quickly as possible, can be observed in a sound echo device or a sound level monitor that is used as a measurement probe and the Carbon and / or additional CaO that is blown in the iron bath when the foam appears. Surprisingly, it has been found that simple probes, such as the sound echo device or a monitor for sound levels, are sufficient to ensure the desired control and, therefore, obtain reproducible results. In order to avoid the risk of local overheating and to safeguard the desired reduction potential respectively, even in the immediate contact with the molten slag, it is an advantage to proceed in such a way that the air or oxygen is blown in the iron bath and the hot air (700 to 1200 ° C) is blown into the liquid slag, which floats in an amount exceeding the blow in the bath by a factor of 2 to 3. In this way, the melting of the partially solidified slags is ensured , as well as the overheating of the slags, substantially improving the reduction of the chromium oxide content of the slags, in the course of 60 to 80% after burning at a heat transfer efficiency of 75 to 95%. Accordingly, highly liquid slags can be reacted rapidly with the carbon content of the iron bath, thus causing the chromium oxide content of the slag to fall to values well below 300 ppm or even lower. below 100 ppm, in a few minutes coconuts.

By maintaining the above conditions and, in particular, the condition in relation to the height of the iron bath, it is possible to minimize the quantitative control in relation to the average of oxygen fed and the average of the carbon that is blown to a point where the Negative marginal effects are eliminated completely. For very high carbon contents, the carbon will not dissolve in the iron bath. Thus, the carbon will float in the bath, being burned extensively without any effect (this is called "blow through"). For very low carbon contents, the iron bath will be relatively viscous at operating temperatures of 1500 ° C to 1550 ° C, so that only a small portion of carbon will be removed through the bath, for kinetic reasons. The carburization with slight losses of blow through will be easy only during a short period of time, in which the temperature reaches approximately 1600 ° C up to 1650 ° C. By controlling the process according to the invention, the operation can be performed at an average oxygen feed below 150m3 / min and the average carbon blow below 200kg / min, therefore quantities are consumed substantially low carbon even during prolonged periods of reaction time in the converted. Furthermore, in the tests carried out, it was shown that, for carbon contents in iron below 2.5% by weight, the chromium oxide content of the slag remains substantially high and can not be further reduced, in order to obtain the desired low values in the reproducible form. In a particularly advantageous manner, the process control can be carried out in such a way that the pressure inside the blow ducts up to the openings of the nozzles in the iron bath is controlled as a function of the height of the bath, which increases with the increase in the height of the bathroom. In this way, the complete mixture of the carbon in the bath is ensured, at the same time, without the occurrence of local refinement, in excess, or local overheating.

This is also important for the subsequent burning (enlargement of the bath surface approximately 20 times in relation to the "still" fusion surface as opposed to the gas space of the converter). In a particularly advantageous manner, the process is carried out in such a way that the inert or oxidation gases are optionally charged with solids and are blown on the lower part of the surface of the iron bath at an average total blow of 2.5. NmVmin.ton of cast iron up to 25 NmVmin.ton of cast iron, preferably from 5 NmVmin.ton of cast iron up to 15 NmVmin.ton of cast iron. By means of this blowing average it is easy to ensure sufficient agitation of the bath inside the iron bath reactor, therefore equalization of the concentration and homogenization of the molten iron and the slag layer is safeguarded. Based on the control according to the invention, it has been possible to supply and remove the liquid slag continuously, as opposed to the method applied up to now of the process. This is due, in particular, to the reaction times that are substantially reduced and the process parameters that are followed more precisely, therefore it is allowed to complete the reaction and, in particular, complete the removal of the chromium in really short times of just a few minutes. In order to safely avoid unwanted local overheating, one can proceed, advantageously, in such a way that the amount of carbon blown per unit of time is reduced and / or, at least partially, replaced by CaO afterwards. of exceeding the limit temperature in the slag or gas space. Particularly advantageous for melt blowing are lime, dolomite, bauxite, refractory clay, fluorine, calcium carbide and / or other slag flows, preferably below and / or above the surface of the iron bath. In order to adjust the carbon content in the iron bath and to equal the temperature prevailing inside the iron bath reactor, we prefer to blow coal, coke, coal slag, lignite coke, petroleum coke, graphite and / or other carbon carriers in the molten iron below the surface of the bath together with a converter gas and, at the same time, feed gases containing oxygen and / or oxygen in the molten iron for the combustion, at least partial, of the carbon. In a particularly economical manner, the process is carried out in such a way that the CO and H2 reaction gases emerging from the molten iron are subsequently burned, at least partially, in the gas space of the iron bath reactor. blow, on top, oxygen, air, hot air, optionally enriched with oxygen and thus, generate heat that is transferred to the melter. Therefore, it is possible to improve the thermal efficiency of the process. By doing this, the nozzles installed stationary in the upper part of the conical portion of the converter can be used in the iron bath reactor to carry out the process according to the invention, or spears can also be introduced, for burning Afterwards, the inverter can be blown through the inverter's mouth or it can be blown into the converter from the position above the converter's mouth. A combination of nozzles and nozzles can also be conceived. By applying this subsequent burning technique, liquid and gaseous fuels can also be used to supply emergy during the process control and to adjust the carbon content within the molten iron. The energy is provided by breaking down the gaseous and liquid hydrocarbons present in the molten iron, which normally exceeds the energy recovered by burning the carbon potion in CO, and therefore, these fuels can cause the fusion to cool, unless the subsequent burning of the reaction gases is carried out under simultaneous conditions of new heat transfer for fusion. In order to obtain a complete reduction, as fast as possible, of metal oxides, in particular, chromium oxide of the fusion, a simple form of the process can be performed so that the partial pressure of the CO that prevails within The reactor of the iron bath is at least temporarily reduced by introducing nitrogen, argon and / or other inert gases through the submerged nozzles and interrupting the supply of oxygen-containing gases to the bath surface. A particularly advantageous application of the process according to the invention resides in the treatment of oxidic slag which occurs in large quantities, e.g. slag derived from waste from incineration plants, blast furnace slag and slag from steel works. , by mixing and liquefying two or three of the slags mentioned above. A product, desired for the production of cement, can be processed relatively quickly as a function of the precise analyzes thereof and optionally after the addition of the appropriate flows. As a rule, these slags are loaded in the iron bath reactor in the cold state. However, if one or more of these slags are available in the liquid state, the liquid charge is preferred, with the aim of improving the economy of the process. The process, in a particularly advantageous manner, can be carried out in powders and / or other residual earth substances, which are blown, in addition, in the iron melting below the surface of the bath partially or together. Dusts and / or residual substances can be derived, for example, from the disposal of incineration or metallurgical plants and thermal processes and can include hazardous waste, dust, debris, debris and contaminated chemicals. In a particularly advantageous manner, one or more residual substances are charged to the iron bath reactor above the surface of the iron bath in liquid or solid form. Alternatively, one can also proceed in such a way that two or more waste substances are loaded in the iron bath reactor, previously mixed, in liquid form or as a solid substance. The process according to the invention can be carried out in simple conventional converters, particularly, in low blow converters, the technical adaptation for the purpose of optimizing the process control, only a small structural expense is required. Due to the particularly simple construction of these converters, the safety in the operation can increase substantially, particularly. The arrangement according to the invention, to carry out the process of the same, comprises a low blow converter that is characterized in that the converter is designed to be reduced as regards the cross-sectional or inclined area in a corresponding region at the height of the desired iron bath and equipped with at least one probe to detect the formation of foam, to determine the concentration of carbon within the iron bath and / or the temperature of the slag and / or the gas space, whose signals are transmitted to the control circuit to provide the carbon and / or the plugged iron bath. In this way, the height of the desired iron bath can be obtained at low amounts of iron bath, so that the introduction of the required carbon can also be reduced as well. In the following, the invention will be explained in more detail with reference to the drawings and by means of exemplary embodiments. In the drawings, Figure 1 illustrates the relationship between the carbon content of the pipe and the reduction of Cr203 from the slag. In Figures 2 and 3 the arrangements for carrying out the process according to the present invention are schematically represented.

Exemplary embodiment: 30 tons of molten raw iron and 20 tons of liquid slag are mixed in a pouring cauldron, which in principle was removed the silica, at the end of which was blown lime. Then, coal is blown in the iron bath. The slag is loaded in two equal portions, and the second slag is added after blowing 50% of the amount of carbon calculated for the total melt, and the residual amount of carbon is blown. The content of chromium oxide is reduced from its original amount of 1200 ppm to 100 pmm in a period of less than 5 minutes, the carbon content of the iron bath was a minimum of 2.65%. It was found, after conducting a number of tests, that the reduction of chromium oxide content in the slag in justifiable values could not be guaranteed with the carbon contents below 2% by weight. As apparent from Figure 1, the content of chromium oxide in the slag with carbon contents of 2% by weight in the slag can be reduced to 500 ppm, in most cases, which does not seem acceptable for the Subsequent uses in the cement industry. Moreover, in values above 2.5% by weight of carbon in the iron bath, the values well below 500 ppm, can be assured in a reproducible way, these values are continuously improved with the carbon content increasing up to approximately 3.5% In addition, the chromium oxide contents of the slag decrease for carbon contents of 3.5 to 4.6% by weight that remains substantially linear, where the control of the economic process is no longer safeguarded after exceeding the upper limit of 4.6% by weight due to the side effects mentioned above. In Figure 2 a first arrangement for carrying the process according to the invention is illustrated in more detail. The oxidation reactor for melting is denoted by the number 1, into which the solid slags are introduced. The slags may be of various origins, slag from incineration plants or metallurgical slags as well as mixtures of different slags which are useful inter alia. The viscous slag, which has been largely liquefied, by means of a pusher 2, can be introduced into a first oxidation space, in which the copper can be sedimented and separated from the liquid slag 3 by means of thermal dissociation and It is withdrawn via the lower outlet 4. In the partial region of the oxidation reactor for melting, in which the slag is already present, other products are also arranged, such as, for example, light fractions as well as incineration waste filter dusts or blast furnace powders that can be blown and melted, for example by using a cyclone 5, where these powders, for example can also be removed from the upper region 6 of the oxidation reactor for melting and charged back into the cyclone for melt by means of a cell wheel lock 7. The amount of gas of the charged powder is removed from the top 6 of the oxidation reactor for melting after purification in a cyclone hot gas which can be further purified by cooling with quenching water as indicated by number 8, the residual heat is recovered, for example in the heat exchanger 9. After the final purification in a counterflow activated coke filter 10 , the pure gas can be discharged by means of a blower 11. The liquid slag 3 reaches the lower blow converter 12, in which the carbon, nitrogen and oxygen are charged through the lower nozzles. The converter is designed so that it narrows in its portion adjacent to the nozzles so that the liquid raw iron bath can reach the respective desired bath level of between 3C0 and 1200 mm, even with a slight amount of crude iron. The liquid slag 3 floats in the raw iron bath, where the LD slag can also be supplied to the slag from the oxidation reactor for fusion on this side. The fusion, or the maintenance of the required slag temperature, in order to obtain highly liquid slag can be assured by blowing oxygen in the upper part in the direction indicated by arrow 13, where the lower blow converter 12, in This case is designed as a converter that can be tilted, so it can be emptied at regular intervals. Zinc and lead can be removed from the gas space of the converter 12 in the gas phase together with C02 and / or CO, the resulting gas mixture after the condensation of zinc and lead is fed into the hot cyclone 5. The respective amount of scoria withdrawn and free of chromium up to its maximum point, it can be granulated and furthermore used in the granulated form. The raw iron that is obtained in addition can be processed in steel works at once. In the embodiment according to Figure 3, the slag is continuously charged into an iron bath reactor 14. Again an oxidation reactor for melting 1 is provided, in which the slag is preheated and / or the combustion of iron takes place. The oxygen is blown in the oxidation reactor for melting by means of concentric nozzles 15, in order to achieve the desired temperature. The material that has been incipiently melted to the maximum point by means of the pusher pusher 2 is transferred to the space in which the slag 3 is collected. There, the necessary temperature can be maintained by means of a burning lance 16, with the transfer continuous slag in the consecutive iron bath reactor 14. The oxygen and carbon fed in this embodiment is carried out in the lower region of the iron bath, where the height of the iron bath above of the oxygen and / or carbon blow nozzles is controlled between 300 and 1200 mm according to the desired. As in the representation of Figure 2, an echo-sound device 17 is available inside the iron bath reactor to verify foam formation, with and pressure, respectively. The height of the crude iron bath can be detected by means of conventional methods and establish the desired control. With the representation according to Figure 3, the zinc, lead and carbon monoxide can be discharged from the reactor of the iron bath 14, through the release means 18, the amount of slag treated during the step supplies a granulator for the production of pozzolanic granulates through a key 19. The arrangements illustrated schematically in Figures 2 and 3 are suitable for loading various combustion residues or slags, and can also be immediately pyrolyzed, in addition to slag of incineration waste, therefore it is able to partially save the fossil energy for the heating and melting of the slag. By carrying out the proposed control by means of the height of the bath and / or the detection of impermissible operational states, such as for example excessive foam, the procedure mode can be optimized and automated to a greater degree, where, in particular, also allowing the operation continuous can ensure a good economy, as is apparent from the arrangement illustrated in Figure 3.

Claims (17)

Claims

1. A process for producing pozzolans, slag from synthetic blast furnaces, belite clinker or alite as well as raw iron alloys from oxidic slag by reducing the oxidized liquid slag on top of the iron bath, characterized in that the carbon is blown in the bath iron through the submerged nozzles, with the aim of maintaining a carbon content between 2.5 and 4.6% by weight.

2. The process according to claim 1, characterized in that the height of the iron bath is adjusted to between 300 and 1200 mm, where, after exceeding the height of the iron bath of 1200 mm, the crude iron is cap and the amount of carbon blown is controlled as a function of a measuring probe.

3. The process according to claim 1 or 2, characterized in that the carbon content is adjusted between 2.5 and 3.5% by weight.

The process according to claim 1, characterized in that the echo sound devices or the sound level monitor is used as the measuring probe and that carbon and / or additional CaO is blown in the iron bath when there is presence of foam.

5. The process according to claim 1 or 2, characterized in that the air or oxygen is blown in the iron bath and that the air or oxygen is blown in the floating slag, in an amount exceeding the amount of breath in the bath by a factor of 2 to 3.

The process according to any of claims 1 to 5, characterized in that the pressure within the blow ducts towards the nozzle openings in the iron bath is controlled as a function of the height of the bathroom, therefore rises with the increase in the height of the bathroom.

The process according to any one of claims 1 to 6, characterized in that, optionally, the oxidation or inert gases charged with solids are blown below the surface of the iron bath at a total average blow from 2.5 NmVmin.ton of cast iron to 25 NmVmin.ton of cast iron, preferably from 5 NmVmin.ton of cast iron up to 15 NmVmin.ton of cast iron.

The process according to any one of claims 1 to 7, characterized in that the liquid slag is continuously supplied and removed.

9. The process according to any of claims 1 to 8, characterized in that the amount of carbon blown per unit of time is reduced and / or at least partially replaced by CaO, after exceeding the limit temperature within the space of the slag or gas.

The process according to any one of claims 1 to 9, characterized in that the coke coal, carbon fines, graphite and / or other carriers are blown into the molten iron below the surface of the bath together with The converter gas, at the same time, feeds the oxygen and / or the oxygen-containing gases in the molten iron for the at least partial combustion of the carbon.

11. The process according to any of claims 1 to 10, characterized in that the gases of the CO H2 reaction emerging from the molten iron are then burned at least partially in the gas space of the bath reactor. iron when blowing oxygen, air, hot air optionally enriched with oxygen in the upper part and therefore, the heat generated is transferred for fusion.

12. The process according to any of claims 1 to 11, characterized in that the partial pressure of CO inside the iron bath reactor is reduced, at least temporarily, by introducing nitrogen, argon and / or other Inert gases through the submerged nozzles and interrupt the supply of oxygen-containing gases on the surface of the bath.

13. The process according to any of claims 1 to 12, which is characterized in that lime, dolomite bauxite, refractory clay, fluorine spar, calcium carbide and / or other slag flows are blown into the melt, preferably below and / or above the surface of the iron bath.

14. The process according to any of claims 1 to 13, characterized in that the powders and / or other residual substances of earth are further blown in the iron melt below the surface of the Bath partially or jointly.

The process according to any of claims 1 to 14, characterized in that one or more residual substances are charged to the iron bath reactor above the surface of the iron bath, in liquid form and / or solid.

16. The process according to any one of claims 1 to 14, characterized in that two or more residual substances, previously mixed, are charged to the reactor of the iron bath, in liquid form or as a solid substance.

17. An arrangement for carrying out the process according to any of claims 1 to 16, comprising a lower blow converter, characterized in that the converter is designed to have a reduction in the cross-sectional or narrow area in the region corresponding to the height of the desired iron bath and equipped with at least one probe to detect the formation of foam, to detect the carbon concentration inside the iron bath and / or the temperature of the slag and / or the gas space, these signals are transmitted to a control circuit for the carbon ratio and / or bleeding of the iron bath.