DE102019219623A1 - Method for determining and controlling or regulating the phosphorus content in a metallic melt during a fresh process of a metallic melt in a metallurgical reactor - Google Patents

Abstract

The invention relates to a method for determining and controlling or regulating the phosphorus content in a metallic melt during a fresh process of a metallic melt in a metallurgical reactor.

Description

Area:

The invention relates to a method for determining and controlling or regulating the phosphorus content in a metallic melt during a fresh process of a metallic melt in a metallurgical reactor.

State of the art:

A steel quality or material properties of a steel are influenced, among other things, by the phosphorus content (% P _St). Therefore it is necessary to measure the average phosphorus content [% P. _m ] to keep a steel melt within narrow limits at the end of a refining process in a metallurgical reactor. For this purpose, the fresh process of the molten steel must be controlled or regulated within the narrowest possible target corridors. An important control or regulation parameter for influencing the average phosphorus content (% P _m ) in the steel melt is, for example, an exact tapping time of the metallurgical reactor. A control or regulation of the fresh process in relation to this tapping time influences both the quality of the steel and the productivity of the metallurgical reactor significantly.

Usually, at the planned end of the refining process or shortly before the metallurgical reactor is tapped, a steel sample is taken from the molten steel and _{analyzed in a laboratory for the phosphorus content [% P m} ]. The result of this analysis is usually available to a plant operator in 3 - 6 minutes and is a basis for a tapping decision by the plant operator.

The accuracy of the analysis of a steel sample from the metallurgical reactor is limited by the fact that only a small sample is taken from a defined point. The plant operator can, for example, with the help of his or her experience of the analysis result on the average phosphorus content [% P. _m ] close the metallic melt.

With a typical fresh time of 14 - 18 minutes, the analysis time of 3 - 6 minutes can have a major impact on productivity. A decision to tap by the plant operator can safely be made with regard to the existing steel analysis with the loss of time due to the analysis duration or the sample is taken 3 - 6 minutes before the theoretical end of the fresh process, but with a corresponding process uncertainty with regard to the steel analysis Mistake. In the worst case, a subsequent incorrect analysis has to be refreshed and the productivity increase due to the early probationary point is lost.

An online determination of the average phosphorus content (% P. _m ) in the steel melt during or at the end of the refining process is the goal of many investigations. These studies and developments are based on a relationship between the average phosphorus content [% P. _m ] in the steel melt and the mean iron oxide content (% Fe _x O _y ) in an associated slag in the metallurgical reactor. For this purpose, the mean iron oxide content (% Fe _x O _y ) in the slag by means of a local measurement of the oxygen activity (ao) in the slag and the assumption that the measurement is representative. From the mean iron oxide content (% Fe _x O _y ) then the average phosphorus content (% P. _S ) derived from the slag. With a known amount of steel and steel analysis at the start of the refining process, as well as an estimated amount of slag at the time of measuring the oxygen activity, both the average phosphorus content [% P. _m ] of the steel melt and a phosphorus distribution Lp in the metallurgical reactor can be calculated. $${\mathrm{L.}}_{\mathrm{P.}}=\frac{\left(\%{\mathrm{P.}}_m\right)}{\left[\%{\mathrm{P.}}_{\mathrm{S.}}\right]}\%$$

The calculation of the average phosphorus content (% P. _S ) in the slag with the help of the measured local oxygen activity ao is afflicted with an error insofar as iron (II) oxide (FeO) and iron (III) oxide (Fe ₂ O ₃ ) are present next to each other in the slag and due to the measurement of the local oxygen activity ao a total value for the iron oxide content (% Fe _x O _y ) is to be determined. It is not possible to determine the present Fe ²⁺ / Fe ³⁺ ratio in the iron oxide content (% Fe _x O _y). The ratio or the content of iron (II) oxide (FeO) and iron (III) oxide (Fe ₂ O ₃ ) in the slag is not only dependent on the oxygen activity ao but also, for example, on other slag constituents. A direct reliable determination of the FeO content or Fe ²⁺ content and thus the reliable determination of the average phosphorus content [% P. _m ] in the steel melt is therefore not possible or at least provided with an uncertainty due to the measurement of the local oxygen activity ao.

Furthermore, the results of the measurement of the oxygen activity are ao strongly dependent on the position of the sensor in the slag. In the area of the hot spot, the focal point of the blowing lance, the oxygen activity ao is very high due to the oxygen blown in and very low in the area of the CO bubbles resulting from the decarburization reaction. In addition, the slag is a heterogeneous mixture of solid lime, solid mixed phases, liquid components and gas bubbles. The composition of the slag from the different phase components and distribution in the metallurgical reactor changes significantly in the course of the refining process, so that it is difficult to carry out representative oxygen measurements.

If a slag sample is taken from the metallurgical reactor, typically only the liquid portion of the heterogeneous slag mixture is taken and sampled. The slag sample is therefore not a reliable basis for determining the phosphorus content (% Ps) in the slag, as e.g. solid phosphorus phases are not taken and are therefore neglected in the phosphorus determination.

With the prior art described, it is not possible to determine the phosphorus content (% P _m ) in a steel melt with sufficient reliability and / or without delay. As a result, there is no basis for reliable control or regulation of the fresh process with regard to the phosphorus content [% P _m ] of a metallic melt in a metallurgical reactor.

Object of the invention:

The object to be solved by the invention consisted in a method which makes it possible _{to determine a phosphorus content [% P m} ] in a metallic melt with sufficient reliability and / or without delay and to control or regulate the fresh process to set the desired average phosphorus content [ % P. _m ] to provide.

Invention:

The object of the invention is achieved by the features of the method according to the invention according to claim 1 for determining a phosphorus content [% P _m ] in a metallic melt. The local manganese content [% Mn _m ] in the metallic melt is determined and the local manganese content [% Mn _m ] becomes a phosphorus content (% P _m ) of the metallic melt and / or a phosphorus distribution Lp im metallurgical reactor derived from a model.

Definitions:

%:

Percent by weight, percent by weight

Model:

By means of a data processing or control or regulation running on the device for determining the manganese content and / or the control of the metallurgical reactor, the specific manganese content is calculated taking into account system parameters, other measured values, for example temperature, exhaust gas composition and / or other process or system-related assumptions in transferred a phosphorus distribution.

This has the advantage that the determination of the phosphorus content [% P _m ] from the manganese content [% Mn _m ] of the metallic melt shows a better correlation between the measured value and the local phosphorus content [% P _m ] than that Two-stage determination of the phosphorus content (% P _m ) with the help of an oxygen determination and the derived ratio (Fe ²⁺ ) / (Fe ³⁺ ).

Furthermore, suitable methods are available for continuous measurement or online measurement of the manganese content [% Mn _m ] in the metallic melt. Due to the usually higher manganese content [% Mn _m ] in the metallic melt, this measurement has a smaller error than a direct measurement of the phosphorus content [% P _m ].

By deriving the phosphorus content [% P _m ] from the manganese content [% Mn _m ] with a model, influences on the phosphorus content [% P _m ] that are not included can advantageously also be taken into account a measurement can be determined directly and / or known systematic measurement inaccuracies in the analysis of the manganese content [% Mn _m ] in the metallic melt can be taken into account.

The object is also achieved by the method according to independent claim 2. A fresh process of a metallic melt in a metallurgical reactor is carried out as a function of the phosphorus content [% P. _m ] of the metallic melt and / or the phosphorus distribution Lp in the metallurgical reactor is controlled or regulated and from the manganese content [% Mn _m ] of the metallic melt the phosphorus content [% P. _m ] of the metallic melt and / or a phosphorus distribution Lp in the metallurgical reactor derived from a model.

The derivation of the phosphorus content [% P _m ] in the metallic melt by means of a model offers the advantages mentioned above for the accuracy of the determination of the phosphorus content [% P _m ] by taking into account the known influences. By integrating the average phosphorus content [% P _m ] determined in this way into a control or regulation of the fresh process in relation to the average phosphorus content [% P. _m ], a system operator is provided with a reliable instrument for control or regulation with which negative influences on the steel quality can be avoided while at the same time optimizing productivity.

According to a preferred embodiment of the invention, when deriving the phosphorus content [% P _m ] and / or the phosphorus distribution Lp by means of the model, reaction kinetic, thermodynamic, statistically determined relationships, measured values and / or reactor-specific system parameters can be taken into account as influences. The advantage here is that both time-resolved and static influences on the fresh process can be included _{in the derivation of the phosphorus content [% P m] due to the relationships and parameters described.} This advantageously improves the accuracy of the determination of the phosphorus content [% P _m ].

In other equally preferred embodiments of the invention, with known temporal progressions of the influencing _{variables, the manganese content [% Mn m} ] and / or the reactor-specific system parameters, a prediction of the temporal progression of the phosphorus content [% P _m ] and / or the phosphorus is possible Distribution Lp possible. This has the advantage that pre-planning is possible in the entire production chain of the metallic melt and / or, in the event of a forecast deviation from target specifications, the control or regulation can intervene in the fresh process in a preventive manner.

In addition, an iron (II) oxide content (% FeO _s ) or iron oxide content (% Fe _x O _y ) in the slag and / or a carbon content [% C _m ] in the derived from metallic melt and taken into account in the regulation or control of the fresh process. The derivation and consideration of these two parameters is also important for the productivity of the metallurgical reactor and the quality of the metallic melt.

According to a preferred embodiment, the phosphorus content [% P _m ] and / or the phosphorus distribution Lp is continuously derived by means of a continuous measurement of the manganese content [% Mn _{m] of the metallic melt and used for continuous regulation or control.} With the usual short process times of the fresh process, this version has the advantage that deviations in the process can be quickly recognized and responded to. These advantages also result from the fact that the derivation of the contents and / or the phosphorus distribution Lp, the control or regulation of the fresh process and / or a display of the derived contents and / or the phosphorus distribution Lp as well as the associated control or regulation parameters online he follows.

The metallic melt advantageously has iron [Fe] as its main component. In particular, an iron content [% Fe _m ] in the metallic melt of more than 30% is preferred. Ideally the metallurgical reactor is a converter.

The invention is described in detail below in the form of exemplary embodiments. In the method according to the invention for determining the phosphorus content [% P _m ] in the metallic melt and / or a phosphorus distribution Lp in a metallurgical reactor, the manganese content [% Mn _m ] is ideally measured with a spectrometer or the LIBS (laser -induced breakdown spectroscopy) determined continuously and / or online. The determined manganese content [% Mn _m ] is converted into a phosphorus content [% P _m ] of the metallic melt and / or a phosphorus distribution Lp in the metallurgical reactor with the help of further relationships and / or influencing variables.

The relationships taken into account when deriving the phosphorus content [% P _m ] describe, for example, the relationship between a manganese content [% Mn _m ] at a specific measuring point in the metallurgical reactor compared to the average manganese content [% Mn _m ] the metallic melt in the metallurgical reactor. Furthermore, time-dependent effects can be taken into account or suppressed with the aid of thermodynamic or reaction kinetic relationships. With the inclusion of plant-specific influencing variables, which can also be time-dependent, and measured values, the model can be adapted to the respective metallurgical reactor and also take into account, for example, changes in the reactor over time, such as wear and / or temperature fluctuations.

Ideally, the relationships and / or influencing variables are determined in advance and the model is integrated into the control or regulation of the fresh process. The advantageous continuous measurement of the manganese content [% Mn _m ] enables the model to continuously _{calculate a phosphorus content [% P m} ]. This enables online or continuous control or regulation of the process. In the optimal case, time-dependent relationships and influencing variables have been determined in advance, which make it possible to make predictions about the course of the fresh process. This allows the control or regulation to react earlier to possible deviations in the course of the fresh process. An online display for the plant operator is helpful when the plant operator assesses the course of the process. Should there be any deviations in the course of the process that cannot be managed by the control or regulation, the operator can then use his experience to intervene in the fresh process.

According to a preferred embodiment, the model from the manganese content [% Mn _m ] is used to calculate the mean phosphorus content [% P. _m ] derived from the metallic melt and the average phosphorus content [% P. _m ] is the control or regulating variable of the control or regulation of the metallurgical reactor. This has the advantage that the control or regulation can take place without the experience of a system operator. In addition, it is conceivable, by making appropriate changes to the model, to convert both local contents into mean and mean into local contents.

This means that conclusions can also be drawn about the iron (II) oxide content (% FeO) or iron oxide content (% Fe _x O _y ) in the slag and / or carbon content [% C _m ] in the metallic melt, it is also possible to closely control these influencing variables, which are important for the quality of the steel and productivity of the plant. Table 1: Designations description description (% P _St ) Phosphorus content in steel [% P. _m ] Average phosphorus content of a steel melt [% P _m ] Phosphorus content of a steel melt L _P Phosphorus distribution (% Fe _x O _y ) Average iron oxide content of a slag a _O Oxygen distribution [Fe] iron [% Fe _m ] Iron content in the melt (FeO) Ferrous oxide in the slag (Fe ₂ O ₃ ) Ferric oxide in the slag (% Fe _x O _y ) Iron oxide content in the slag [% Mn _m ] local manganese content [% Mn _m ] medium manganese content melt [% C _m ] Carbon content in the melt

Claims (12)

Method for determining a phosphorus content ([% P _m ]) in a metallic melt during the fresh process of the metallic melt, comprising manganese ([Mn]) and phosphorus ([P]), in a metallurgical reactor where - a manganese content ([% Mn _m ]) is determined in the metallic melt; - from the manganese content ([% Mn _m ]) the phosphorus content ([% P _m ]) of the metallic melt and / or a phosphorus distribution (Lp) in the metallurgical reactor is derived by means of a model. Method for controlling or regulating the fresh process of a metallic melt, comprising manganese ([Mn]) and phosphorus ([P]), in a metallurgical reactor, wherein - the fresh process depends on a phosphorus content ([% P _m ]) of the metallic melt and / or the phosphorus distribution (Lp) in the metallurgical reactor is controlled or regulated; and - from the manganese content ([% Mn _m ]), the phosphorus content ([% P _m ]) of the metallic melt and / or a phosphorus distribution (Lp) in the metallurgical reactor is derived by means of a model. Method according to one of the preceding claims, characterized in that when deriving the phosphorus content ([% P _m ]) and / or the phosphorus distribution (Lp) by means of the model, reaction-kinetic, thermodynamic and / or statistically determined relationships are taken into account as influencing variables can be. Method according to one of the preceding claims, characterized in that when deriving the phosphorus content ([% P _m ]) and / or the phosphorus distribution (Lp) using the model, measured values and / or reactor-specific system parameters can be taken into account as influencing variables. Method according to one of the preceding claims, characterized in that with known temporal progressions of the influencing variables and the manganese content ([% Mn _m ]) a prediction about the temporal progression of the phosphorus content ([% P _m ]) and / or the Phosphorus distribution (Lp) is possible. Method according to one of the preceding claims, characterized in that an iron oxide II content ((% FeO _s )) and / or iron oxide _{content ((% Fe x} O _y )) in the slag can be derived from the model. Method according to one of the preceding claims, characterized in that a carbon content ([% C _m ]) in the metallic melt can be derived by means of the model. Method according to one of the preceding claims, characterized in that by means of a continuous measurement of the manganese content ([% Mn _m ]) of the metallic melt, the phosphorus content ([% P _m ]) and / or the phosphorus distribution (Lp) continuously derived and used for continuous regulation or control of the fresh process. Method according to one of the preceding claims, characterized in that the derivation of the contents and / or the phosphorus distribution (L _P ), the control or regulation of the fresh process and / or a representation of the derived contents and / or the phosphorus distribution (Lp ) and the associated control or regulation parameters are carried out online. Method according to one of the preceding claims, characterized in that - the phosphorus content ([% P _m ]) derived with the model is the mean phosphorus content ([% P. _m ]) of the metallic melt; and - control or regulation variable of the control or regulation of the metallurgical reactor the average phosphorus content ([% P. _m ]) is. Method according to one of the preceding claims, characterized in that the metallic melt has iron ([Fe]) as the main component, preferably an iron content ([% Fe _m ]) of more than 30% iron ([Fe]). Method according to one of the preceding claims, characterized in that the metallurgical reactor is preferably a converter.