The present invention refers to a method and to a control and tracking system of the charge of material transported by a continuous supply conveyor of a metallurgical furnace, particularly an electric furnace for the production of steel.

The technology for producing steel through the use of electric -arc furnaces (EAF) is well established, starting from charge mixtures comprising different types of materials (iron minerals, reduced iron, scrap iron/steel etc.) in different proportions in function of the type and quality of steel that is desired to be obtained.

The supply of the charge of material to the furnace can be of the discontinuous or of the continuous type.

KR100685049, to Posco, US 4,579,524, to GN Kinematics Corp., and EP0526664, to Sibag Schmid Industrieberatung, each describes an apparatus for supplying in a discontinuous manner the charge of material to a metallurgical furnace and a relative system for controlling the single supplied batches of charge of material .

The present invention, on the contrary, refers to a method and to a control and tracking system of the charge of material supplied in a continuous manner to a metallurgical furnace, in particular to an electric furnace for the production of steel, through an apparatus like for example that described in US 6,450,804, the content of which is integrally referred to hereby.

Supplying apparatuses as described for example in US 6,450,804 comprise, in general, a continuous conveyor, for example of the vibrating or of the belt type, which extends alongside the furnace and has an inlet end and an outlet end arranged near a feeding mouth defined on one side of the furnace.

Along the continuous conveyor in sequence starting from its inlet end towards its outlet end, a loading section of the charge of material to be supplied to the furnace, a preheating section of the charge of material loaded and a section for introducing the preheated charge of material into the furnace are defined.

At the loading section, the charge of material to be treated is deposited onto the continuous conveyor through appropriate manipulation devices, of the crane type or manipulator arms type .

The preheating section consists instead of a closed tunnel inside which the charge of material is indeed preheated through appropriate burners and/or by the heat directly or indirectly recovered from the fumes exiting from the furnace.

The introduction section of the charge preheated inside the furnace comprises a device for connecting the continuous conveyor with the furnace, device that is associated in a mobile manner to the feeding mouth of the furnace .

The technologies for producing steel, in general, and those with continuous supply of the charge of material, in particular, provide the maintenance of a predetermined minimum level of liquid metal in the crucible of the furnace to which the charge of material transported by the continuous conveyor is supplied.

In such a context, the need of being able to verify the yield of every single charge of material and to optimise the composition of the charge of material in function of the quality of steel which is desired to be obtained is particularly felt.

From US 5,948,137, to David J. Joseph Company, a system for determining the weight and for analysing the composition of a charge of material continuously supplied to a metallurgical furnace is known, wherein the analysis of the composition is carried out through an analysing device of the so-called "Prompt Gamma-Ray Neutron Activation Analysis" (PGNAA) type. Such a system, however, is difficult to be implemented at the industrial level, both due to the complexity and to the installation and management costs of such an analysis device, and due to the poor safety conditions of a metallurgical site wherein such an analysis device should operate .

From US 6,004,504, to Techint Compagnia Tecnica Internazionale, a method and an apparatus are known for controlling a process for producing steel continuously, wherein in proximity to the inlet of the preheating section, means for detecting the weight and the advancement speed of the charge of material previously supplied on the continuous conveyor along the corresponding loading section, are arranged. The detected weight and speed of the load are used to extrapolate the flow-rate of the charge supplied to the furnace and, also in function of the signals detected by thermal and level probes inserted in the furnace, to estimate the bath level in the furnace.

A method and a control apparatus as described in US 6,004,504, however, do not permit to find out the typology (quality/composition) of the charge of material progressively supplied to the furnace and, therefore, to evaluate the respective yield and to consequently intervene on the recipe of melt in function of the quality of steel which is desired to be obtained.

The purpose of the present invention is that of providing a method and a control and tracking system of the charge of material transported by a continuous supply conveyor of a metallurgical furnace, particularly an electric furnace for the production of steel, which permit to avoid the aforementioned drawbacks of the prior art .

In the field of such a general purpose, one purpose of the present invention is that of providing a method and a control and tracking system of the charge of material transported by a continuous supply conveyor of a metallurgical furnace, particularly an electric furnace for the production of steel, which permit to estimate with sufficient precision, in terms of quality (type) and of quantity, the charge of material supplied to a metallurgical furnace and the time in which it is introduced into the furnace itself.

Another purpose of the present invention is that of providing a method and a control and tracking system of the charge of material transported by a continuous supply conveyor of a metallurgical furnace, particularly an electric furnace for the production of steel, which permit to estimate the yield of each charge of material and to manage, in a flexible manner, the loading of different qualities (types) and quantities of charge material in function of the recipe of melt and of the quality of steel that is desired to be obtained.

These purposes according to the present invention are achieved by realizing a control and tracking method of the charge of material transported by a continuous supply conveyor of a metallurgical furnace, particularly an electric furnace for the production of steel, as outlined in claim 1.

Further characteristics are provided in the dependent claims 2-10.

These purposes are moreover achieved through a control and tracking system of the charge of material transported by a continuous supply conveyor of a metallurgical furnace, particularly an electric furnace for the production of steel, as outlined in claim 11.

Further characteristics are provided in the dependent claims 12-18.

The characteristics and the advantages of a method and of a control and tracking system of the charge of material transported by a continuous supply conveyor of a metallurgical furnace, particularly an electric furnace for the production of steel, according to the present invention will become clearer from the following description, exemplifying and not limiting, with reference to the attached schematic drawings, wherein:

figure 1 is a schematic side view of a system according to the present invention applied to a continuous supply conveyor of an electric -arc furnace; figures 2, 3 and 4 schematically show subsequent loading steps onto the continuous conveyor of different charge fractions at as many different loading stations; figure 5 is a block diagram of the method according to the present invention.

With reference to the figures, a control and tracking system 1 of the charge of material transported by a continuous conveyor 2 for supplying a metallurgical furnace 3 is shown, particularly an electric furnace for the production of steel.

The furnace 3 is, preferably, but not exclusively, of the electric -arc type, but it can also be of the induction or plasma type.

The conveyor 2 is, preferably, but not exclusively, of the vibrating type, but it could also be of the belt type or similar.

The conveyor 2 comprises, in sequence starting from its inlet end towards its outlet end, a loading section 2A of the charge of material to be supplied to the furnace 3, a preheating section 2B of the charge of material loaded and an introduction section 2C into the furnace 3 of the preheated charge of material .

Along the loading section 2A at least a first loading station 200 of the material is present, followed by one or more subsequent n-th loading stations 200n.

Downstream of the loading section 2A the preheating section 2B is present, which typically consists of a closed tunnel 4 wherein the charge of material is preheated by the heat generated by appropriate burners and/or directly or indirectly recovered from the fumes exiting from the furnace 3.

The outlet of the preheating section 2B is associated with the introduction section 2C which typically comprises a device 5 for connecting to a feeding mouth 6 obtained on one side of the furnace 3.

The conveyor 2, the furnace 3, the loading 2A, the preheating 2B and the introduction 2C sections are not further described in detail being of the known type, as for example described in US 6,450,804, the content of which is hereby integrally incorporated.

At the first loading station 200 and at each subsequent n-th loading station 200n a respective loading hopper 201, 201n is present, of the fixed or mobile type, belonging to the conveyor 2.

The first hopper 201 and each n-th subsequent hopper 201n are associated with respective detecting means of the weight 202, 202n of the material therein loaded by loading apparatuses which a steelwork plant is usually equipped with, for example of the type with a crane hoist 7.

The detecting means of the weight 202, 202n consist, for example, of sensors, load cells and similar.

At the first hopper 201 and at each n-th subsequent hopper 201n, moreover, marking means 203, 203n are provided respectively of the first charge fraction CI and of each subsequent n-th charge fraction Cn respectively discharged by them onto the conveyor 2 through identification means Ml, Mn.

The identification means Ml, Mn, for example, can consist of an electromagnetic radiation emitter and, in case each charge fraction consists in its turn of a plurality of different materials, each one can be marked with respective identification means Ml, Ml' , Ml'', Ml''' and Mn, Mn' , Mn' ' , Mn' ' ' etc.

At the inlet of each n-th loading station 200n respective recognising means 204n are provided, through the respective identification means Ml, Mn, of the (n- 1) charge fractions discharged in the preceding loading stations and present in the load of material entering them.

Analogous recognising means 240 are present at the inlet of the preheating section 2B.

In case the identification means Ml, Mn are of the electromagnetic radiation emitter type, the recognising means 204n and 240 are of the receiver type.

However, different identification and recognition means are not excluded, for example, based upon the application to the different charge fractions or to the different materials forming each charge fraction of an appropriate paint .

Downstream, with respect to the advancement direction of the conveyor 2, of the first hopper 201 and of each subsequent n-th hopper 20In means for detecting the overall dimensions 205, 205n are arranged respectively of the first charge fraction CI and of each subsequent n-th charge fraction, i.e. of the charge exiting from the n-th loading station 200n, present on the conveyor 2.

Analogous means for detecting the overall dimensions 215n and 250 are arranged at the inlet of each n-th loading station 200n and of the preheating section 2B.

The means for detecting the overall dimensions 205, 205n, 215n and 250 comprise means for acquiring the profile respectively of the first charge fraction CI exiting from the first loading station 200, of the charge exiting from each subsequent n-th loading station 20On and of the charge entering the n-th loading station 200n and of the preheating section 2B on at least one plane transversal to the advancing direction of the conveyor 2.

In a preferred embodiment, such means for acquiring the profile of the charges of material present on the conveyor 2 are of the radar scanning type. However, alternative embodiments of the optical, of the laser scanning type or other, for example, are not excluded.

Downstream, with respect to the advancing direction of the conveyor 2, of the first hopper 201 and of each subsequent n-th hopper 20In means 206, 206n are arranged for detecting the advancing speed respectively of the first charge fraction CI and of each subsequent n-th charge fraction Cn, that is of the charge of material exiting from the n-th loading station 200n, along the loading section 2A of the conveyor 2.

Analogous means for detecting 216n, 260 the advancing speed of the charge are arranged at the inlet of each n-th loading station 200n and of the preheating section 2B.

In a preferred embodiment, the means for detecting

206, 206n, 216n and 260 the advancing speed respectively of the first charge fraction CI, of the charge exiting from the n-th loading station 200n, of the charge entering the n-th loading station 20On and of the charge entering the preheating section 2B comprise means for acquiring a plurality of images of the respective charges in delayed times, the images and the relative acquisition times being then mutually correlated and processed through appropriate composition and processing algorithms to obtain therefrom an estimate of the advancing speed of the respective charge of material.

However, different embodiments of the means for detecting the speed of the charges of material of the type, for example, of radiation, laser devices or other are not excluded.

In case the means for detecting the advancing speed of the charges of material are of the type based upon the acquisition of a series of subsequent images of the charges of material themselves, such images can be used and processed also in order to get information pertaining to the size and to the overall dimensions thereof, of the fractions that form them or of the different materials that form each fraction.

Moreover, the possibility is not excluded that the means for detecting the overall dimensions of the charges of material may actually coincide with the means for detecting the advancing speed of the same charges of material, in case the latter are based upon the acquisition of a series of successive images of the charges themselves .

The system 1 also comprises a processing and control unit 10 that receives at the inlet the detected data and the signals transmitted by each of the means for detecting the weight 202, 202n, the marking means 203, 203n, the recognising means 204n, 240, the means for detecting the overall dimensions 205, 205n, 215n and 250 and the means for detecting the speed 206, 206n, 216n and 260.

The processing and control unit 10 moreover receives at the inlet the signal transmitted by means for detecting the weight of the molten metal tapped from the furnace 3, which are associated with the ladle for collecting the tapped melt metal and not shown in detail, or by systems for weighing the furnace, through the difference of quantity tapped as for example described in EP1872074.

The processing and control unit 10, moreover, is associated with memory means containing an archive of recipes of melt and with means for controlling and driving the loading devices (crane hoist 7) operating in a store of charge materials, not shown.

With particular reference to the block diagram of figure 5 and to the sequence of steps illustrated in figures 2-4, the method according to the present invention implemented by a system as described above is now illustrated.

Once a predetermined charge recipe has been set for the n-th melt of metal to be obtained (step 100 of the diagram) , the processing and control unit 10 determines (steps a) and a'); step 101 of the diagram) the typology and the weight of material of a first charge fraction CI and of each possible subsequent n-th charge fraction Cn to be loaded respectively into the first loading station 200 and into the possible subsequent n-th loading stations 200n for obtaining the predetermined recipe.

On the basis of the division, in terms of quality and quantity, of the charge material in different charge fractions Cl-Cn thus established, the loading devices (crane hoist 7) supply the first hopper 201 of the first loading station 200 with the first charge fraction (step b) ; step 102 of the diagram) , of which, the means for detecting the weight 202 detect the actual weight (step c) .

When the detected actual weight reaches the value determined in step a) (step 103 of the diagram) , the first charge fraction CI is discharged onto the conveyor 2 (step d) ; step 104 of the diagram) .

The marking means 203 associate, with the first charge fraction CI, the respective identification means Ml (step e) ; step 105 of the diagram) or Ml, Ml' , Ml' ' and Ml' ' ' in case, for example, the first charge fraction CI comprises a plurality of different materials .

The means for detecting the overall dimensions 205 then detect the two- or three-dimensional overall dimensions of the first charge fraction CI in outlet from the first charge station 200 (step f) ; step 106 of the diagram) and the detecting means of the speed 206 detect or permit to estimate (step g) ; step 107 of the diagram) the advancing speed of the first charge fraction CI along the loading section 2A of the conveyor 2 and the arrival time (step g) ; step 108 of the diagram) of the same entering a possible subsequent n-th loading station 200n of a further n-th charge fraction Cn or to the preheating section 2B.

The estimate of the arrival time of the first charge fraction CI to the possible subsequent n-th loading station 200n or entering the preheating section 2B occurs through the processing of the estimated speed and of the length of the conveyor 2, that is of the distance between the first loading station 200 and the n-th loading station 200n and the inlet of the preheating section 2B.

In case a further n-th loading station 200n is present, where n>2 , the first charge fraction or the (n-1) charge fraction discharged onto the conveyor 2 advances towards it (step 109 of the diagram) .

At the inlet of the n-th loading station 200n the

(n-1) charge fractions discharged into the preceding loading stations are identified by the recognising means 204n through the respective identification means Ml, Mn (step I) ; step 112 of the diagram) .

Always at the inlet of the n-th loading station

200n, the means for detecting the overall dimensions 215n detect the overall actual dimensions of the charge of material entering it (step II) ; step 110 of the diagram) .

Afterwards, the position is estimated, with respect to the charge entering the n-th loading station 200n, at which to perform the discharge of the n-th charge fraction Cn in function of the actual overall dimensions of the charge of material entering the n-th loading station 200n and of the distribution of the (n- 1) charge fractions previously discharged onto the conveyor 2 (step III) .

Always at the inlet to the n-th loading station 200n, the means for detecting the speed 216n detect or permit to estimate the advancing speed of the charge entering the n-th loading station 200n along the loading section 2A and the arrival time of the discharge position estimated at the n-th loading station 200n (step IV; step 111 of the diagram) .

When the position of the charge of material entering the n-th loading station corresponds to the estimated position, the n-th charge fraction Cn is discharged onto the conveyor 2 (step V) ; step 113 of the diagram) .

For each n-th loading station 200n, in an analogous way to the first loading station 200, on the basis of the division, in terms of quality and quantity, of the charge material in different charge fractions Cl-Cn established by the processing and control unit 10, the loading devices (crane hoist 7) supply the n-th hopper 201n of the n-th loading station 200n with the n-th charge fraction Cn (step b' ) ; step 102' of the diagram), of which, the means for detecting the weight 202n detect the actual weight (step c') .

When the detected actual weight reaches the value determined in step a') (step 103' of the diagram), the n-th charge fraction Cn is discharged onto the conveyor 2 (step d' ) ; step 104' of the diagram).

The marking means 203n associate the respective identification means Mn (step e'); step 105' of the diagram) with the n-th charge fraction Cn.

The means for detecting the overall dimensions

205n then detect the two- or three-dimensional overall dimensions of the n-th charge fraction Cn, that is, of the charge of material exiting from the n-th loading station 200n (step f); step 106' of the diagram) and the means for detecting the speed 206n detect or permit to estimate (step g' ) ; step 107' of the diagram) the advancing speed of the n-th charge fraction Cn, that is, of the charge exiting from the n-th loading station 20On along the loading section 2A of the conveyor 2 and the arrival time (step g' ) ; step 108' of the diagram) of the same entering a possible subsequent loading station 200n+l of a further charge fraction Cn+1 or the preheating section 2B.

Exiting from the last loading station (step 114 of the diagram) , the charge of material consisting of the various charge fractions CI, C2 .. Cn, of each of which, on the basis of the data detected and estimated, the type (quality) , the weight, the position and the actual speed and the relative overall dimensions are known, comes to enter the preheating section 2B.

Here the recognising means 240 recognise in the discharged charge of material the first charge fraction CI and possible further charge fractions Cn subsequently discharged onto the conveyor 2 by means of respective identification means Ml, Mn (step h) ; step 115 of the diagram) .

Always at the inlet to the preheating section 2B, the relative means for detecting the overall dimensions 250 detect the actual overall dimensions of the charge of material comprising the first charge fraction CI and possible further charge fractions Cn subsequently discharged onto the conveyor 2 (step i) ; step 116 of the diagram) .

In the same way, the means for detecting the speed 260 detect or permit to estimate the advancing speed of the first charge fraction CI and of possible further charge fractions Cn subsequently discharged onto the conveyor 2 along the preheating section 2B and the relative arrival time to the introduction section into the furnace 2C (step 1) ; steps 117 and 118 of the diagram) .

Even in such case, the arrival time of the charge or of the different charge fractions to the introduction section 2C into the furnace 3 is estimated on the basis of the data of the speed of the charge fractions previously processed and of the length of the conveyor 2.

On the basis of the data pertaining to the type (quality) , the weight, the actual position, the advancing speed and the overall dimensions of the single charge fractions, it is possible to estimate the weight and the typology of the charge actually introduced into and present in the furnace 3 (step m) ; step 119 of the diagram) .

The data pertaining to the type (quality) , the weight and the overall dimensions of the single fractions also permit to estimate the average density of each of them.

At the end of the melting and refining treatment

(step 120 of the diagram) and of the tapping of the melt metal (step 121 of the diagram) , means for detecting the weight associated with the ladle for collecting the melt metal or to the melting furnace, acquire, directly or indirectly by subtraction, the weight of the tapped melt metal (step n) ; step 122 of the diagram) .

Such data is processed by the processing and control unit 10 for estimating the yield of the treated charge (step o) ; step 123 of the diagram) thus creating a record on the basis of which it is possible to optimise the formulation of the melt recipes in function of the quality of steel being produced.

Then the recipe of the subsequent melt is determined.

It is specified that the time sequence of the steps could be different from that described; for example, the marking of the single charge fractions could occur before they are discharged onto the conveyor 2, the detection of the overall dimensions can occur before or after the detection of the speed, these last detections (of the overall dimensions and of the speed) , moreover, can be based upon a common series of successive images of the charge of material in successive instants of time.

Moreover, the various steps of the method according to the present invention occur in real time with the continuous supply process of the charge of material in the furnace .

The method and the system according to the present invention permit to know the typology (quality) and the weight of the charge fraction discharged onto the continuous conveyor at each loading station and to determine, at any instant of time, its position, its overall dimensions and its advancing speed along the loading section and also along the preheating section of the conveyor itself, thus keeping track of it.

On the basis of such information, the method and the system according to the present invention permit, in particular, to estimate the typology (quality) and the weight of the charge of material introduced into and processed in the furnace in a determined time interval, thus being able to estimate the yield.

The method and the system according to the present invention, thanks to the fact that they permit to know, at any instant of time, the position, the weight, the overall dimensions and the advancing speed of a specific charge fraction of a known type (quality) , being the same "marked" and "monitored" in its course along the continuous conveyor, permit to define, modify and program the melt recipes in a flexible manner in function of the different qualities of metal which are desired to be produced. This also occurs during the advancing of the charge along the conveyor itself, modifying, for example, the charge fraction of a determined loading station or the process in the furnace .

The detection of the overall dimensions of the charge of material entering and exiting from each loading station and of the weight of the single charge fractions permit to evaluate the choice and the positioning of the subsequent charge of material for a better distribution of the same, both in the horizontal and in the vertical direction along the continuous conveyor, in terms of quality, weight and size as well.

The marking of each single charge fraction and/or of the components and the recognition thereof along the entire continuous conveyor, along with the detection or estimate of its advancing speed along the continuous conveyor, permit to know its actual position and its advancing state towards the furnace and to determine the typology and the weight of the charge processed in a determined time interval inside the furnace.

The method and the system thus conceived can undergo numerous modifications and variants, all covered by the invention,- moreover, all details are replaceable with technically equivalent elements. In practice the materials used, as well as the sizes, could be any according to the technical needs .