Method for detecting melting speed of iron alloy for steelmaking

Abstract

The invention relates to the technical field of material performance detection, in particular to a method for detecting the melting speed of an iron alloy for steelmaking, and provides a method for indirectly obtaining the melting speed of the alloy in molten steel by measuring the gravity and buoyancy change of the alloy by adopting sensors such as force measuring equipment based on the principle of a drainage method. The melting condition of the iron alloy in the high-temperature molten steel is continuously measured, and the melting speed is calculated, so that the melting speeds of the iron alloys with different types, particle sizes and densities in the molten steel under the conditions of different components and temperatures are favorably detected, and the selection of the iron alloys which are quickly melted and homogenized in the alloying process in industrial production is conveniently guided; the method has a good application prospect in the field of steelmaking.

Description

Technical Field

[0001] The invention relates to the technical field of material performance detection, in particular to a method for detecting the melting speed of a ferroalloy used for steelmaking. Background Art

[0002] Adding various alloy elements to steel products has a strong effect on improving the performance of steel. Therefore, after the completion of steelmaking in an electric furnace or converter, adding alloys to the molten steel during the steelmaking process to deoxidize and alloy the molten steel is an important step in the entire steelmaking process.

[0003] For high-performance special steel, the amount of alloy added during the steelmaking process is usually large, and multiple alloy elements need to be added, resulting in a large number of alloy types added. The amount of alloy added may reach tens of tons, which can easily cause the temperature of the molten steel in the ladle to drop, and the alloy is difficult to melt quickly. Therefore, it is very important to explore the melting speed of different types of alloys in molten steel and the factors affecting the melting speed. Different melting speeds will not only affect whether the alloy can be completely melted in the ladle, but also cause different alloy element yields. Slowly melting alloys are easy to float to the interface between molten steel and air under the action of the ladle bottom blowing airflow, causing the alloy elements to oxidize at high temperatures, greatly reducing the alloy element yield; at the same time, different melting speeds have a significant impact on the element homogenization of alloy elements in molten steel. Rapid homogenization of alloy elements can enable temperature measurement sampling to obtain accurate results, preventing the detection of low or high components due to uneven composition, which requires more or less alloy, resulting in alloy waste or unqualified products.

[0004] However, the melting of alloys is a high-temperature process at a temperature of about 1600°C. Conventional detection methods are difficult to accurately detect the melting process of alloys in such a high-temperature environment. Under laboratory conditions, the detection of alloy melting rates is mainly carried out through high-temperature thermal experiments or water simulation experiments. Water simulation experiments usually use ice cubes and water to determine the radius change of ice cubes in water through optical observation under the condition of designing specific similarity criteria, so as to determine its melting rate, and then determine the melting rate of corresponding similar alloys through the similarity principle. However, this method has strong limitations. First, there are many types of alloys used in steelmaking, and it is difficult to detect different types of alloys using only ice and other materials; second, water simulation is difficult to simulate the high temperature difference between molten steel and alloys, resulting in the simulated melting time of ice cubes being longer than the melting time of actual alloys. Therefore, the melting rate of alloys measured by water simulation has a large error. For hot experiments, the molten steel is heated to a molten state in a crucible, and the corresponding alloy is directly used. A steel rod is welded on the top and then inserted into the molten steel. The alloy is taken out at a certain time interval and then cooled. The radius of the alloy column is measured, and the alloy melting rate is calculated based on the size change of measurable data such as the radius of the alloy column. Although this method is closer to the actual situation, due to the high temperature of the molten steel, it cannot be observed continuously like water simulation. Each time point is discrete, and the unmeasured points in the middle can only be estimated and fitted based on the size change trend of the measured points. The most intuitive continuous melting situation cannot be obtained. At the same time, if the measurement time points taken are not representative, the wrong melting process may be fitted. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for detecting the melting rate of ferroalloy for steelmaking, aiming to solve the problem that the melting rate of ferroalloy in high-temperature molten steel cannot be continuously and accurately measured at present.

[0006] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions: A method for detecting the melting rate of a ferroalloy for steelmaking comprises the following steps: S1. Element content detection and shape processing of the ferroalloy to be tested for melting speed; S2. Measure the size and density of the ferroalloy after processing; S3. Connect the dynamometer to the rigid rod and record the dynamometer reading after the connection is stable; S4. Connect the processed ferroalloy to the rigid rod and record the dynamometer reading after the connection is stable; S5. Detect the element content of the steel sample; S6. Place a sufficient amount of steel sample in a crucible and melt it at high temperature, record the temperature after the melting stabilizes and calculate the density of the molten steel at this time; S7. The processed ferroalloy connected to the rigid rod is preheated and uniformly placed in the molten steel and immersed; S8. Record the change of the dynamometer reading over time until the dynamometer reading becomes stable; S9. Remove the remaining ferroalloy at a constant speed and record the stable reading of the dynamometer after removal; S10. Draw a coordinate graph of the dynamometer reading versus time, and calculate the continuous melting rate of the ferroalloy for steelmaking based on the coordinate graph and the relationship between the volume density.

[0007] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking described in the present invention, wherein: in the step S1, the ferroalloy is detected by direct current spectroscopy before the shape processing, and the alloy elements include C, Si, Mn, Ni, Cr, Al and other elements, and the mass fraction of the alloy elements in the ferroalloy is recorded as oh AC 、oh ASi 、oh AMn 、oh ANi 、 oh ACr 、oh AAl .

[0008] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking described in the present invention, in which: in the step S1, the shape after the outer shape processing is a shape formed by stacking two upper and lower cylinders with different radii, wherein the upper cylinder is used to connect with the rigid rod, and its diameter is close to the cross-sectional diameter of the rigid rod and smaller than the radius of the lower cylinder.

[0009] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking according to the present invention, wherein: in the step S2, the method for measuring the size of the ferroalloy after processing is to measure it by a vernier caliper; the measured diameter of the lower cylinder is recorded as D 0 , the radius is R 0 , the height is recorded as H 0 ; The diameter of the upper cylinder is recorded as D 1 , the radius is R 1 , the height is recorded as H 1 ; Based on the above measurement data, the volume of the lower cylinder can be calculated as V b The volume of the upper cylinder isV t , the total volume of the ferroalloy V a The method for measuring the density of the ferroalloy after processing is to measure the mass of the ferroalloy using a scale. m 0 The alloy density is calculated to be r a = m 0 / V a .

[0010] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking described in the present invention, wherein: in the step S3, the dynamometer is an elastic dynamometer, which can be connected to a computer to read real-time data; the rigid rod is made of refractory material or steel, and its length is sufficient to ensure that the ferroalloy can be delivered into the molten steel; the rigid rod is connected to the dynamometer by a hook.

[0011] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking described in the present invention, wherein: in the step S4, the connection method of the ferroalloy and the rigid rod is: if a refractory rigid rod is used, a height direction hole is punched in the upper cylinder of the ferroalloy, the hole depth is less than the height of the upper cylinder, and the hole diameter is slightly larger than the rigid rod to ensure that the rigid rod can be tightly inserted into the hole. After insertion, the ferroalloy and the refractory rigid rod are punched together in the diameter direction, the hole diameter is slightly larger than the bolt diameter, and the bolt length is guaranteed to completely pass through the diameter direction and be fixed with the corresponding nut; if a steel rigid rod is used, the top surface of the upper cylinder of the ferroalloy is connected to the bottom of the steel rigid rod by welding, and the dynamometer reading when stable is recorded as G 0 .

[0012] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking described in the present invention, wherein: in the step S5, the content of alloy elements in the steel sample is detected by direct current spectroscopy before melting, and the alloy elements include C, Si, Mn, Ni, Cr, Al and other elements, and the mass fraction of the alloy elements in the molten steel is recorded as ω[C]、ω[Si]、ω[Mn]、ω[Ni]、ω [Cr]、ω[Al] .

[0013] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking according to the present invention, in step S6, when the steel sample is completely melted and heated to a stable temperature, the temperature of the molten steel at this time is recorded as T 0 ℃, the density of the temperature-stable pure steel liquid is r T0 , calculated as shown in formula (1); the density of molten steel containing alloy elements is rm The calculation method is shown in formula (2): r T0 = 8523-0.8358(T 0 +273) (1) r m =p T0 -210ω[C]-60ω[Si]-7.5ω[Mn]+6ω[Ni]-550ω[Cr]-164ω[Al] (2).

[0014] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking described in the present invention, wherein: in the step S7, the ferroalloy is heated to a set preheating temperature above the crucible and kept warm for 10 minutes before measuring the temperature. The preheating temperature at this time is recorded as T p .

[0015] As a preferred embodiment of the method for detecting the melting speed of ferroalloy for steelmaking described in the present invention, in said step S7, the ferroalloy is uniformly placed in the molten steel liquid and the immersion depth is: the upper surface of the lower cylinder of the ferroalloy is slightly higher than the steel liquid surface.

[0016] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking according to the present invention, in step S8, the initial reading of the dynamometer at the start of the melting record is recorded as G 1 , time is recorded as 0, and the reading of the dynamometer changes continuously as the melting progresses. The changes of the reading of the dynamometer over time are recorded in real time by computer software and other methods until the reading of the dynamometer becomes stable and unchanged. At this time, the reading of the dynamometer is recorded as G 2 , the dynamometer reading during the melting process is G(t) , time is t , the alloy melting process is completed, and the dynamometer reading is recorded as G 3 , time is recorded as t f .

[0017] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking according to the present invention, in step S9, the stable reading of the dynamometer after taking out is recorded as G 4 .

[0018] As a preferred embodiment of the method for detecting the melting rate of ferroalloy for steelmaking described in the present invention, wherein: in the step S10, the curve of the force value of the dynamometer changing with time is obtained according to the record G(t) The melting rate of the ferroalloy in the molten steel can be calculated, wherev G is the force change speed of the dynamometer, and its calculation method is shown in formula (3); v V is the alloy volume melting rate, which is calculated as shown in formula (4); v m is the melting rate of the alloy mass, which is calculated as shown in formula (5); formula (6) and formula (7) are the starting and ending conditions of melting respectively; formula (8) is the initial reading of the dynamometer G 1 and stable indication G 4 The force curve between G(t) : (3) (4) (5) (6) (7) (8).

[0019] The beneficial effects of the present invention are as follows: The invention provides a method for detecting the melting speed of an iron alloy for steelmaking. Based on the principle of the water displacement method, a method for indirectly obtaining the melting speed of an alloy in molten steel by measuring the changes in the gravity and buoyancy of the alloy is proposed by using sensors such as force measuring equipment. The method can rapidly, in real time and continuously measure the melting conditions of the iron alloy in high-temperature molten steel and calculate the melting speed, which is beneficial for finding out the melting speeds of iron alloys of different types, particle sizes and densities in molten steel under different composition and temperature conditions, so as to guide the selection of iron alloys that melt rapidly and homogenize in the alloying process in industrial production. The method has good application prospects in the field of steelmaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the shape and size of the ferroalloy after processing; Figure 2 It is a schematic diagram of the connection between the iron alloy and the rigid rod; Figure 3It is a schematic diagram of the immersion mode and depth of the ferroalloy in the molten steel; Figure 4 Schematic diagram of the device for detecting the melting rate of ferroalloy.

[0022] Among them, 1-ferroalloy to be tested, 2-upper cylinder, 3-lower cylinder, 4-rigid rod, 5-dynamometer.

[0023] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The present invention provides a method for detecting the melting rate of an iron alloy for steelmaking, which can measure continuous and quantitative melting rate data of the iron alloy in molten steel, and more intuitively obtain the melting state of the iron alloy in the molten steel according to the change of the indication of a connected dynamometer over time, so as to determine in detail the continuous quantitative value of the melting rate of the iron alloy in the molten steel, improve the error of the traditional hot state experiment of intermittent sampling observation measurement and then fitting the full melting process of the iron alloy, simplify the hot state experiment measurement process, will not miss all the characteristic transformation points of the ferroalloy melting process, and greatly improve the accuracy of the measurement result.

[0026] Taking into account the actual melting process of ferroalloy in molten steel, due to the extremely high temperature of the molten steel, the melting state of the ferroalloy cannot be directly observed after the ferroalloy enters the molten steel. The general measurement method is limited by the experimental simulation conditions or the limitations of intermittent measurement of sampling. The ferroalloy melting rate obtained by measurement fitting usually has a certain error, and even wrong results will be fitted when the sampling is not representative.

[0027] The method of the present invention makes certain assumptions to facilitate the actual operation during the detection process and the calculation and processing of the subsequent detection results: the unmelted ferroalloy remains in a solid state and its density remains unchanged. As the ferroalloy melts, the alloying elements in the molten steel increase, but the effect on the density change of the molten steel is very small and can be ignored. Therefore, during the melting process, the volume of the ferroalloy that is only immersed in the molten steel changes. The change in volume causes the gravity of the solid part of the ferroalloy and the buoyancy of the molten steel to change. Therefore, the volume change of the ferroalloy melted in the high-temperature molten steel can be understood by measuring the change in the combined force on the solid ferroalloy in the molten steel, and the ferroalloy mass melting rate and the ferroalloy melting rate can be calculated through the numerical relationship between density and volume.

[0028] like Figure 1-4 As shown, the basic principle of the present invention is the idea of ​​water displacement method. The solid ferroalloy is subjected to constant changes in gravity and buoyancy due to the constant changes in the melting volume of the solid ferroalloy in the molten steel. By processing the shape of the ferroalloy 1 to be tested, and connecting it with the dynamometer 5 through the rigid rod 4, the change of the resultant force of the ferroalloy 1 to be tested in the melting process in the molten steel can be obtained. The basic principle can be described by the following formula: The overall force reading of the dynamometer is G The relationship between force and time is G(t) It indicates that, for the analysis of stress conditions, G(t) = G 杆 +G t +G b (t)-F b (t) ,in, G 杆 is the weight of the rigid rod 4, G 杆 = m 杆 g ; G t is the weight of the ferroalloy upper cylinder 2, G t = r a V t g ; G b is the weight of the ferroalloy lower cylinder 3, F b is the buoyancy of the ferroalloy 1 to be tested under the influence of the molten steel, the gravity of the ferroalloy lower cylinder 3 and the buoyancy of the ferroalloy 1 to be tested under the influence of the molten steel vary with time and the amount of melt, and are therefore expressed as G b (t) and F b (t) , G b (t) = r a V b (t)g , F b (t) = r m V b (t)g ,in, V b (t) Represents the change in volume of the lower cylinder of ferroalloy with time.

[0029] The connection method between the ferroalloy 1 to be tested and the rigid rod 4 is (such as Figure 2 As shown): If a refractory rigid rod is used, a hole in the height direction is made on the upper cylinder of the ferroalloy. The hole depth is less than the height of the upper cylinder, and the hole diameter is slightly larger than the rigid rod to ensure that the rigid rod can be tightly inserted into the hole. After insertion, the ferroalloy and refractory rigid rods are punched together in the diameter direction. The hole diameter is slightly larger than the bolt diameter. The bolt length is guaranteed to be able to completely pass through the diameter direction and be fixed with the corresponding nut (as shown Figure 2 If a steel rigid rod is used, the top surface of the ferroalloy upper cylinder is connected to the bottom of the steel rigid rod by welding (as shown in (b)). Figure 2 (shown in (a)).

[0030] In the alloy melting process, two very close moments t1 and t2 are taken. The time interval between t1 and t2 is Δt, The force relationship between them is: ΔG=G(t 2 )-G(t 1 ) , where the forces at time t1 and t2 are G(t 1 ) and G(t 2 ) , ΔG The force on the dynamometer changes due to the melting of the alloy.

[0031] During the melting process of the alloy, the volume of the lower cylinder of the ferroalloy changes with time. V b (t) It means that the volume of the lower cylinder of the ferroalloy at t1 and t2 is V b (t 1 ) and V b (t 2 ) The change in volume between two moments is ΔV express, V b (t 1 ) and V b (t2 ) The relationship between them is: V b (t 2 ) = V b (t 1 +Δt) = V b (t 1 ) - ΔV Therefore, the stress conditions at t1 and t2 are G (t 1 ) and G(t 2 ) They are: G(t 1 ) = m 杆 g+r a V t g+r a V b (t 1 )g-r m V b (t 1 )g G(t 2 ) = m 杆 g+r a V t g+r a V b (t 2 )g-r m V b (t 2 )g but ΔG=(ρ a -r m )ΔVg , ΔV=ΔG / ((ρ a -r m )g) when Δt When it approaches 0 and The ratio of is the speed of force change at time t1 v G , as shown in formula (3), and then according to the relationship between mass volume and density, the volume melting rate can be obtained v V and mass melting rate v m As shown in formula (4) and formula (5): (3) (4) (5).

[0032] The melting rate of ferroalloy for steelmaking can be obtained by the above principle method and data processing method. This method has excellent operability and adaptability.

[0033] Studies have shown that when the initial temperature of the ferroalloy surface is low, the ferroalloy will first solidify into a metal steel shell on the surface after entering the molten steel, and then the steel shell melts and the ferroalloy body begins to melt. The traditional sampling observation method is difficult to grasp the time of steel shell solidification and melting, while the method of the present invention can be based on the measured G(t) To determine whether the steel shell is solidified, and to continuously and accurately record the solidification and melting degree of the surface steel shell. The specific calculation method is shown in equations (9) to (14), and its principle is the same as the above melting stage. It can be clearly seen that the solidification and melting stage of the steel shell is different from the melting stage of the ferroalloy. v G , v V and v m .

[0034] (9) (10) = + (11) (12) (13) (14) in, V t is the volume of the upper cylinder of the ferroalloy sample, V b (t 1 ) for t 1 The volume of the upper cylinder of the ferroalloy sample at time ΔV For t 1 Time has come t 2 The volume change of the lower cylinder of the alloy sample during the time period of time, when the steel shell solidifies ΔV Greater than 0, when melting occurs ΔV Less than 0, r ml is the density of molten steel, r ms is the density of the solidified steel shell, r ms Generally greater than r ml When the steel shell solidifies ΔV Greater than 0, the dynamometer reading increases; when the steel shell melts ΔV When the temperature is less than 0, the dynamometer reading decreases; when the ferroalloy melts, the dynamometer reading decreases, but the v Different, so in G(t) There are obvious inflection points in each stage, thus obtaining the precise melting process.

[0035] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0036] Example 1 High carbon ferromanganese is one of the most commonly used ferroalloys in the alloying process of converter steelmaking. Almost all steel grades have requirements for manganese content. The most commonly used manganese-containing ferroalloy to supplement manganese in the alloying process is high carbon ferromanganese. Therefore, the melting rate of high carbon ferromanganese under different conditions is explored under laboratory conditions to guide the control of different conditions in industrial production to achieve the optimal ferromanganese melting situation. The following parameters of the experimental design are discussed as shown in the table: First, large blocks of high carbon ferromanganese with different carbon contents are selected and processed into the sample shape described in step S1, wherein the size of the upper cylinder should be adapted to the rigid rod, so the size of the upper cylinder of each sample remains unchanged as H 1 25mm× D1 25mm, the lower cylinder size is processed into different heights and diameters according to the experimental plan H 0 × D 0 Then, in steps S2 and S3, the dimensions of the sample are determined again using a vernier caliper, and the volume of the lower cylinder of the ferroalloy sample is calculated based on the measured data. V 0 And the overall density of the sample r a . Use rigid rods, nuts and bolts made of refractory materials to connect the sample and the rigid rod. Then connect the sample to be tested and the rigid rod force measuring equipment respectively according to step S4. A frame of load-bearing force measuring equipment is set up above the furnace mouth of the tubular furnace. The frame has two layers for placing and supporting the force gauge. The upper layer is used to preheat the ferroalloy sample when the force gauge and the ferroalloy sample are placed; the lower layer is used as the placement layer for immersing the sample in the molten steel. The height of the lower layer should meet the depth of immersing the sample in the molten steel described in the key points of step S7. Put enough electrolytic iron into the crucible, and add carbon powder and other alloys to meet different C content and other alloy element contents in the molten steel, and put the crucible into the tubular furnace for heating. Heat to the molten steel temperature targeted by the test plan, use a vacuum tube to sample and detect the content of each element in the molten steel according to step S5, and calculate the density of the molten steel under the current experimental conditions and element content according to step S6. At the same time, the sample is placed on the upper part of the tube furnace for preheating, and the temperature of the sample is detected by a temperature measuring gun. When the sample temperature reaches the target preheating temperature, the sample is immersed in the molten steel in the crucible according to step S7, and the computer equipment starts recording according to step S8. G(t) When the curve reaches stability, take out the sample according to step S9 and process it according to step S10. G(t) Curve, get the v G , v V , v m After that, replace the sample and repeat the experiment according to the above steps. After the melting speed of the samples of different conditions and sizes of all schemes are tested, the results of each group of experiments are obtained. G(t) Curve, calculation and processing to obtain each group v G , v V , v m , Comparison of different parameters by scheme v , analyze and obtain each parameter v The influence of different conditions is compared by controlling the variables. v The change of the parameter can be obtained. v The influence of law: (1) The larger the size of the lower cylinder of the ferroalloy sample, the longer the time it takes for the molten steel to solidify and form a crust on the surface of the sample, the later the start time of the melting of the alloy body, and the higher the initial melting speed of the subsequent alloy body.

[0037] (2) The higher the preheating temperature, the shorter the solidification crust time on the surface of the ferroalloy sample, the smaller the crust thickness, and the faster the melting rate of the ferroalloy body, but the ferroalloy yield decreases. Long-term high-temperature preheating causes oxidation on the ferroalloy surface.

[0038] (3) The carbon content of high carbon ferromanganese and the carbon content of molten steel have a comprehensive effect on the melting of ferroalloy samples. The carbon content affects the density of molten steel and ferroalloy samples, and the carbon content affects the melting point of ferroalloy samples. The mass transfer of carbon between solid and liquid also affects the heat transfer between solid and liquid. The lower the carbon content of high carbon ferromanganese, the higher the melting point, the surface solidified steel shell does not change much, the longer the melting time, the slower the melting speed. The higher the carbon content of molten steel, the melting time of ferroalloy samples does not change much, the surface steel shell solidification time is shorter, and the thickness of the solidified layer is greater.

[0039] (4) The higher the temperature of the molten steel, the shorter the surface crusting time, the smaller the crust thickness, and the faster the ferroalloy sample melts.

[0040] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for detecting the melting rate of ferroalloy for steelmaking, characterized in that: The following steps are involved: S1. Element content detection and shape processing of the ferroalloy to be tested for melting speed; S2. Measure the size and density of the ferroalloy after processing; S3. Connect the dynamometer to the rigid rod and record the dynamometer reading after the connection is stable; S4. Connect the processed ferroalloy to the rigid rod and record the dynamometer reading after the connection is stable; S5. Detect the element content of the steel sample; S6. Place a sufficient amount of steel sample into a crucible for melting, record the temperature after the melting stabilizes and calculate the density of the molten steel at this time; S7. The processed ferroalloy connected to the rigid rod is preheated and uniformly placed in the molten steel and immersed; S8. Record the change of the dynamometer reading over time until the dynamometer reading becomes stable; S9. Remove the remaining ferroalloy at a constant speed and record the stable reading of the dynamometer after removal; S10. Draw a coordinate graph of the dynamometer reading versus time, and calculate the continuous melting rate of the ferroalloy for steelmaking based on the coordinate graph and the relationship between the volume density.

2. The method for detecting the melting rate of ferroalloy for steelmaking according to claim 1, characterized in that: In step S1, the shape after the outer shape processing is a shape formed by stacking two upper and lower cylinders with different radii, wherein the upper cylinder is used to connect with the rigid rod, and its diameter is close to the cross-sectional diameter of the rigid rod and smaller than the radius of the lower cylinder.

3. The method for detecting the melting rate of ferroalloy for steelmaking according to claim 1, characterized in that: In step S2, the method for measuring the size of the ferroalloy after processing is to measure it with a vernier caliper; the measured diameter of the lower cylinder is recorded as D 0 , the radius is R 0 , the height is recorded as H 0 ; The diameter of the upper cylinder is recorded as D 1 , the radius is R 1 , the height is recorded as H 1 ; According to the above measurement data, the volume of the lower cylinder is calculated as V b The volume of the upper cylinder is V t , the total volume of the ferroalloy V a The method for measuring the density of the ferroalloy after processing is to measure the mass of the ferroalloy using a scale. m 0 The alloy density is calculated to be ρ a = m 0 / V a .

4. The method for detecting the melting rate of ferroalloy for steelmaking according to claim 1, characterized in that: In step S3, the dynamometer is an elastic dynamometer, which is connected to a computer to read real-time data; the rigid rod is made of refractory material or steel, and its length is sufficient to ensure that the ferroalloy can be delivered into the molten steel; the rigid rod is connected to the dynamometer by a hook.

5. The method for detecting the melting rate of ferroalloy for steelmaking according to claim 1, characterized in that: In the step S4, the connection method of the ferroalloy and the rigid rod is: if a refractory rigid rod is used, a hole in the height direction is made in the upper cylinder of the ferroalloy, the hole depth is less than the height of the upper cylinder, and the hole diameter is slightly larger than the rigid rod to ensure that the rigid rod can be tightly inserted into the hole. After insertion, the ferroalloy and the refractory rigid rod are pierced together in the diameter direction, the hole diameter is slightly larger than the bolt diameter, and the bolt length is guaranteed to be able to completely pass through the diameter direction and fixed with a corresponding nut; if a steel rigid rod is used, the top surface of the upper cylinder of the ferroalloy is connected to the bottom of the steel rigid rod by welding, and the dynamometer reading when stable is recorded as G 0 .

6. The method for detecting the melting rate of ferroalloy for steelmaking according to claim 1, characterized in that: In step S5, the steel sample is tested for the content of alloying elements by direct current spectroscopy before melting. The alloying elements include C, Si, Mn, Ni, Cr, and Al. The mass fraction of the alloying elements in the molten steel is recorded as ω[C], ω[Si], ω[Mn], ω[Ni], ω[Cr], ω [Al] ; In step S6, when the steel sample is completely melted and heated to a stable temperature, the temperature of the molten steel at this time is recorded as T 0 ℃, the density of the temperature-stable pure steel liquid is ρ T0 , calculated as shown in formula (1); the density of molten steel containing alloy elements is ρ m The calculation method is shown in formula (2): ρ T0 = 8523-0.8358(T 0 +273) （1） ρ m =ρ T0 -210ω[C]-60ω[Si]-7.5ω[Mn]+6ω[Ni]-550ω[Cr]-164ω[Al] （2）。 7. The method for detecting the melting rate of ferroalloy for steelmaking according to claim 1, characterized in that: In step S7, the ferroalloy is heated to the set preheating temperature above the crucible and kept warm for 10 minutes before measuring the temperature. The preheating temperature at this time is recorded as T p The ferroalloy is uniformly placed in the molten steel liquid and immersed to a depth such that the upper surface of the lower cylinder of the ferroalloy is slightly higher than the surface of the molten steel liquid.

8. The method for detecting the melting rate of ferroalloy for steelmaking according to claim 1, characterized in that: In step S8, the initial reading of the dynamometer at the start of the melting record is recorded as G 1 , time is recorded as 0, and the reading of the dynamometer changes continuously as the melting progresses. The change of the reading of the dynamometer with time is recorded in real time until the reading of the dynamometer becomes stable. At this time, the reading of the dynamometer is recorded as G 2 , the dynamometer reading during the melting process is G(t) , time is t , the alloy melting process is completed, and the dynamometer reading is recorded as G 3 , time is recorded as t f .

9. The method for detecting the melting rate of ferroalloy for steelmaking according to claim 1, characterized in that: In step S9, the stable reading of the dynamometer after taking out is recorded as G 4 .

10. The method for detecting the melting rate of ferroalloy for steelmaking according to claim 1, characterized in that: In step S10, the curve of the force value of the dynamometer changing with time is obtained according to the record. G(t) The melting rate of the ferroalloy in the molten steel can be calculated, where v G is the force change speed of the dynamometer, and its calculation method is shown in formula (3); v V is the alloy volume melting rate, which is calculated as shown in formula (4); v m is the melting rate of the alloy mass, which is calculated as shown in formula (5); formula (6) and formula (7) are the starting and ending conditions of melting respectively; formula (8) is the initial reading of the dynamometer G 1 and stable indication G 4 The force curve between G(t) : （3） （4） （5） （6） （7） （8）。

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