High-carbon chromite hot stove slag iron separation optimization method

Abstract

The present application relates to the technical field of iron smelting, and particularly relates to a high-carbon chromite hot furnace slag iron separation optimization method. The content comprises the following steps: obtaining the temperature of molten iron and the temperature of furnace slag, respectively estimating the instantaneous density values of the molten iron and the furnace slag, and obtaining the density ratio of the molten iron and the furnace slag; based on the density ratio of the molten iron and the furnace slag, constructing an interface height dynamic positioning model to obtain the layered interface height; introducing a layered shear disturbance intensity calculation formula to quantize the shear force and obtain the shear disturbance intensity; based on the shear disturbance intensity, combining the layered interface height, adjusting the molten iron furnace slag outlet opening ratio, and performing separation optimization based on the molten iron furnace slag outlet opening ratio. The technical problem that in the process of slag separation, mainly relying on the experience of operators and fixed structure adjustment, unable to realize the dynamic response control of the layered interface height, and easily affected by interface disturbance, temperature gradient and other factors to cause the technical problems of layered failure and frequent mixed flow phenomenon are solved.

Description

Technical Field

[0001] This invention relates to the field of iron smelting technology, and in particular to an optimized method for separating iron from slag in a high-carbon ferrochrome ore furnace. Background Technology

[0002] In the smelting process of high-carbon ferrochrome submerged arc furnaces, slag-iron separation is a crucial step before molten iron tapping, and its efficiency directly determines the alloy purity, resource recovery rate, and energy utilization level of the final product. Currently, most enterprises still use physical separation methods based primarily on gravity settling, supplemented by slag baffles or grate structures. In traditional processes, operators rely on their experience to judge the stratification state and manually adjust the iron and slag tapping processes, which has significant limitations. Specifically, the physical properties of molten iron and slag are not significantly different at high temperatures; for example, the density and viscosity differences change dynamically with temperature fluctuations, making it difficult to accurately determine the stratification interface. Furthermore, during iron tapping, the height of the stratification interface often fluctuates with changes in flow rate and furnace temperature, and is easily damaged by shear disturbances and fluid instability, leading to slag mixing into the molten iron or molten iron flowing into the slag pool. This reduces the purity of the molten iron or wastes alloy resources, and causes erosion and wear on equipment such as grates, increasing operation and maintenance costs. Summary of the Invention

[0003] This invention provides an optimized method for separating slag and iron in a high-carbon chromite submerged arc furnace, which solves the technical problems of relying mainly on operator experience and fixed structure adjustment during slag separation, making it impossible to achieve dynamic response control of the layering interface height; and being easily affected by factors such as interface disturbance and temperature gradient, leading to layering failure and frequent mixing phenomena.

[0004] An optimized method for separating slag and iron in a high-carbon ferrochrome submerged arc furnace, according to the present invention, includes the following steps:

[0005] S1. Obtain the temperatures of molten iron and slag, and estimate the instantaneous density values ​​of molten iron and slag respectively to obtain the density ratio of molten iron to slag; based on the density ratio of molten iron to slag, and combined with a density ratio threshold, determine the density separation potential between molten iron and slag; when stable stratification physical conditions are met, based on the density ratio of molten iron to slag, combined with dynamic viscosity and flow velocity, construct a dynamic positioning model of the interface height to obtain the stratification interface height; the specific construction formula of the dynamic positioning model of the interface height is as follows:

[0006] ,

[0007] in, At any moment The instantaneous height of the slag-iron stratification interface relative to the bottom in the slag grate represents the stratification interface height; This refers to the working depth of the slag grate; At any moment The weighted fusion temperature of molten iron temperature and slag temperature; It is molten iron at all times Weighted fusion temperature The dynamic viscosity at the following levels; It is the slag at all times Weighted fusion temperature The dynamic viscosity at the following levels; It is a moment The flow rate of molten iron; It is a moment The slag flow rate; It is gravitational acceleration; At any moment The density ratio of molten iron to slag; It is to prevent Regularization parameters that cause numerical divergence; It is the viscosity ratio weighting coefficient; It is the velocity difference weighting coefficient; It is the viscosity ratio term; It is the flow rate difference time correction term; It is the baseline flow velocity difference.

[0008] S2. The shear force is quantified by introducing a formula for calculating the layered shear disturbance intensity, and the shear disturbance intensity is obtained. Based on the shear disturbance intensity and the layered interface height, the opening ratio of the molten iron and slag outlet is adjusted, and separation optimization is performed based on the opening ratio of the molten iron and slag outlet.

[0009] Preferably, S1 specifically includes:

[0010] Based on the molten iron temperature, a molten iron temperature decay term is constructed, and the instantaneous density value of the molten iron is obtained; based on the slag temperature, combined with logarithmic calculation, the instantaneous density value of the slag is obtained.

[0011] Preferably, S1 specifically includes:

[0012] Based on the density ratio of molten iron to slag and the density ratio threshold, the density separation potential between molten iron and slag is judged: when the density ratio of molten iron to slag is greater than or equal to the density ratio threshold, it indicates that the physical conditions for stable stratification are currently available; when the density ratio of molten iron to slag is less than the density ratio threshold, it indicates that stratification is difficult to form.

[0013] Preferably, S2 specifically includes:

[0014] The formula for calculating the layered shear disturbance intensity calculates the layered shear force by calculating the vertical velocity gradient between molten iron and slag at the layered interface and combining it with the dynamic viscosity of slag and molten iron, thus obtaining the shear disturbance intensity.

[0015] Preferably, S2 specifically includes:

[0016] Based on the layered interface height, a layered sensitivity index is introduced to generate a layered ratio term.

[0017] Preferably, S2 specifically includes:

[0018] Based on the shear perturbation intensity, a perturbation exponent weight is introduced to generate an exponential perturbation decay term.

[0019] Preferably, S2 specifically includes:

[0020] Using the stratification ratio term and the exponential disturbance attenuation term as nonlinear modulation factors, the iron-slag outlet opening ratio is calculated to regulate iron and slag tapping. The specific calculation formula is as follows:

[0021] ,

[0022] in, At any moment The ratio of the opening degree of the molten iron slag outlet; It is a numerical stability correction term; It is a stratification sensitivity index; It is the weight of the disturbance index; At any moment The shear disturbance intensity; It is the critical value of shear disturbance intensity; This is a reference temperature; Indicates the height of the slag layer; It is a hierarchical proportion item; It is the exponential disturbance decay term.

[0023] The beneficial effects of the technical solution of the present invention are:

[0024] 1. Traditional slag-iron separation mainly relies on operator experience and fixed structure adjustments, which cannot achieve dynamic response control of the stratification interface height. This invention, through a density ratio function constructed based on temperature data, can perceive the evolution trend of the density difference between molten iron and slag on a millisecond time scale, and use this as a preliminary judgment basis for stratification feasibility, ensuring that the prerequisite physical conditions for stratification behavior are met. Once the density ratio reaches the density ratio threshold, subsequent height positioning processing is initiated, effectively avoiding the mixing problem caused by blindly tapping iron under unfavorable conditions, and improving the stability of stratification control.

[0025] 2. Traditional slag-iron separation processes are easily affected by factors such as interface disturbances and temperature gradients, leading to stratification failure. This invention introduces a shear disturbance strength calculation formula to achieve a quantitative judgment of the mechanical stability of the stratified interface. The shear disturbance strength is calculated by coupling the vertical velocity gradient with temperature and viscosity, which can dynamically reflect the relative slip state of the molten fluid in the furnace. As an important intervention variable for adjusting the system response opening, especially under high temperature or high flow rate difference conditions, it can detect potential interface instability risks in advance and take adjustment actions in advance, thereby effectively preventing interface collapse or mixing accidents.

[0026] 3. This invention designs a formula for calculating the opening ratio of molten iron and slag outlet with dual nonlinear modulation factors. It controls the sensitivity of the layered interface position through a power function and suppresses the disturbance risk through an exponential function, realizing real-time coordinated control between the iron outlet and the slag outlet. It no longer relies on fixed baffle positions or manual adjustments, but adjusts the fluid channel opening based on real-time calculated physical state variables such as the layered interface height and shear disturbance intensity, thus achieving closed-loop operation, adaptive adjustment, and disturbance suppression functions. Attached Figure Description

[0027] Figure 1 This is a flowchart of an optimized method for separating slag and iron in a high-carbon chromite ore hot furnace, as described in this invention. Detailed Implementation

[0028] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] The following description, in conjunction with the accompanying drawings, details the specific scheme of the optimized method for separating iron from slag in a high-carbon chromite ore hot furnace provided by this invention.

[0031] See attached document Figure 1 The diagram illustrates a flowchart of an optimized method for separating slag and iron in a high-carbon ferrochrome submerged arc furnace, according to an embodiment of the present invention. The method includes the following steps:

[0032] S1. Obtain the temperature of molten iron and the temperature of slag, and estimate the instantaneous density values ​​of molten iron and slag respectively to obtain the density ratio of molten iron to slag; based on the density ratio of molten iron to slag, construct a dynamic positioning model of interface height to obtain the layered interface height.

[0033] Before the entire separation process begins, temperature data of molten iron and slag at the grate inlet are collected using on-site temperature sensors. Since temperature directly affects the density and viscosity of the molten fluid, a density ratio function is constructed based on the temperature data and laboratory thermal expansion experiments. This function serves as the fundamental input for subsequent layering interface determination. The specific formula for the density ratio function is as follows:

[0034] ,

[0035] in, At any moment The density ratio of molten iron to slag reflects the density difference between the two at that moment. A larger density ratio indicates a higher density. A higher value usually means that the molten iron and slag have a better stratification effect and the stratification interface is more obvious. It is the initial density of molten iron, a standard value obtained by consulting standard literature; It is the initial density of the slag, obtained through standard data provided in standard literature; It is a moment The temperature of the molten iron is measured in real time by a temperature sensor, where the temperature unit of the temperature sensor is set to Calvin. It is a moment The slag temperature is measured in real time by a temperature sensor; It is a standard temperature value. You can choose the melting point temperature or a common smelting temperature, such as 298K, where K represents the temperature unit Calvin. This is the decay coefficient of molten iron density as temperature increases, reflecting the degree of influence of molten iron temperature on its density. The reference range is... ; It is the logarithmic response coefficient of slag density as a function of temperature, describing the logarithmic change in slag density with increasing temperature. The reference range is [range missing]. ; , It was obtained by fitting experimental data on the density of molten iron and slag at different temperatures using the existing nonlinear least squares method. This is the iron temperature decay term, used to describe the effect of iron temperature changes on iron density. As the temperature increases, the density of molten iron gradually decreases. It is the logarithmic response of slag temperature to slag density, used to describe how slag density changes with temperature, that is, slag density decreases as temperature increases, but the rate of decrease is slow. It describes the process of density reduction of molten iron due to thermal expansion under high-temperature smelting conditions, and is used to dynamically estimate the instantaneous density value of molten iron. It is the instantaneous density value of the slag;

[0036] The density ratio output by the above formula These are the main control parameters of the interface height dynamic positioning model, and their purpose is to determine the density separation potential between molten iron and slag. Specifically, based on historical smelting condition data obtained from existing databases, a density ratio threshold is set using an empirical regression method. and density ratio Compared with density ratio threshold Comparison: When When, it indicates that the physical conditions for stable stratification are currently met; when If the temperature is too high, it indicates that stratification is difficult to form, and the process enters the preparation stage for temperature or flow regulation, such as reducing the tapping speed and appropriately increasing the temperature difference, in order to wait for the ideal stratification conditions to form.

[0037] when Based on the density ratio of molten iron to slag, a dynamic positioning model for the interface height is constructed. This model dynamically adjusts the height of the stratified interface according to factors such as temperature, flow rate, and density differences. Specifically, because the molten fluid exhibits a stratified flow state driven by gravity, the denser molten iron lies in the lower layer, while the less dense slag floats in the upper layer. The height of the stratified interface fluctuates over time and is limited by the viscosity ratio and flow rate differences of the molten fluid. Therefore, the specific formula for constructing the dynamic positioning model for the interface height is as follows:

[0038] ,

[0039] in, At any moment The instantaneous height of the slag-iron stratification interface relative to the bottom in the slag grate is the stratification interface height, which is also the height of the molten iron layer. It is the working depth of the grate (total liquid column height), which is a design parameter of the equipment; At any moment The weighted fusion temperature of molten iron temperature and slag temperature is calculated by an attention mechanism. The methods used in the calculation of the weighted fusion temperature are all well known to those skilled in the art and will not be described in detail here. It is molten iron at all times Weighted fusion temperature The dynamic viscosity was measured under controlled temperature conditions using a high-temperature rotational viscometer or crucible rheometer, and obtained by fitting multi-point data using a nonlinear model such as the Arrhenius equation. The reference range is as follows: ; It is the slag at all times Weighted fusion temperature The dynamic viscosity was measured under controlled temperature conditions using a high-temperature rotational viscometer or crucible rheometer, and obtained by fitting multi-point data using a nonlinear model such as the Arrhenius equation. The reference range is as follows: ; It is a moment The molten iron flow rate can reflect the sinking and discharge capacity of molten iron, and is obtained through a flow rate sensor in front of the furnace; It is a moment The slag flow velocity is an important source of the velocity difference at the stratification interface, which is obtained through the furnace front flow velocity sensor. It is gravitational acceleration; It is to prevent The regularization parameter that causes numerical divergence can make the formula stable at the initial time, and can be taken as 0.06; This is the viscosity ratio weighting coefficient, used to control the contribution of viscosity ratio to the stratification process. It reflects the nonlinear influence of viscosity differences on interface stability. Based on historical smelting condition data (such as stratification interface height) obtained from existing databases, it is determined using existing multivariate nonlinear least squares regression methods. The reference value range is... ; This is the velocity difference weighting coefficient, used to control the intensity of the excitation effect of the velocity difference during the stratification process. It can affect the sensitivity of the stratification interface to rise. Based on historical smelting condition data (such as molten iron velocity and slag velocity) obtained from existing databases, it is determined using the existing multivariate nonlinear least squares regression method. The reference value range is [insert range here]. ; It is a viscosity ratio term, which represents the dynamic viscosity ratio between molten slag and molten iron, and is used to measure the difference in flow properties between the two melts; It is the velocity difference time correction term, used to measure the dynamic contribution of the molten physical state (velocity + density + time) to the change in the height of the stratified interface; This represents the coupled effects of fluid viscosity differences, flow velocity differences, density comparisons, and time evolution at a given temperature; It is the reference velocity difference, a small constant greater than 0, and can take values ​​of... This ensures that even when the macroscopic velocity difference is zero, It will not disappear completely, thus preserving a fundamental contribution for the dynamic calculation of interface height.

[0040] S2. The shear force is quantified by introducing a formula for calculating the layered shear disturbance intensity, and the shear disturbance intensity is obtained. Based on the shear disturbance intensity and the layered interface height, the opening ratio of the molten iron and slag outlet is adjusted, and separation optimization is performed based on the opening ratio of the molten iron and slag outlet.

[0041] After the instantaneous height of the interface is determined, the strong shear force difference between the molten iron and slag in the molten flow state leads to instability of the layered interface. Therefore, based on the interlayer shear stress theory and the calculation model of the two-layer immiscible fluid interface based on the Navier-Stokes equation, a formula for calculating the layered shear disturbance intensity is constructed to quantify the shear disturbance intensity. The specific formula is as follows:

[0042] ,

[0043] in, At any moment The layered shear force, i.e., the shear disturbance intensity; , Let represent the vertical velocity gradients of slag and molten iron at the interface, i.e., the rate of change of velocity per unit height. These are velocity gradients of the upper and lower layers of the interface calculated using a multi-point laser velocimetry (LDA) probe and a numerical differential algorithm. The velocity gradient of the lower layer of the interface is [the velocity gradient of the lower layer is...]. The velocity gradient of the upper layer of the layered interface is... ; This represents the shear stress in the region near the interface within the molten iron layer; This represents the shear stress in the slag layer near the interface.

[0044] Furthermore, based on the layered interface height and shear disturbance intensity, the angle ratio of the taphole and slag outlet is calculated, i.e., the taphole-slag outlet opening ratio, to achieve precise control of tapping and slag tapping. The specific calculation formula is as follows:

[0045] ,

[0046] in, At any moment The ratio of the opening degree of the molten iron slag outlet; It is a numerical stability correction term used to avoid the denominator or numerator being zero in the limiting state and to prevent numerical singularities. Its value can be 0.01. It is the stratification sensitivity index, used to control the degree of nonlinearity in the response of the outlet opening to the stratification ratio. The larger the size, the more sensitive it is to adjusting the amount of molten iron. It is the perturbation index weight, used to control the perturbation factor. The degree of influence on the exponentially decaying term determines the strength of the feedback. It is the critical value of shear disturbance intensity, which is obtained by simulation using numerical simulation tools such as ANSYS Fluent, OpenFOAM, and COMSOL. When the shear disturbance intensity exceeds the critical value, the outlet opening should be controlled in time to prevent slag and iron mixing. It is the reference temperature, that is, the full-power furnace temperature measured by an infrared thermometer, which is used as the benchmark for temperature weighting normalization. Indicates the height of the slag layer; This is the layering ratio term, which, as a nonlinear modulation factor in power function form, represents the relative relationship between the thickness of the molten iron layer and the slag layer. If... This indicates a high proportion of molten iron, and the opening of the molten iron outlet should be increased. It is an exponential disturbance attenuation term. As an exponentially decaying nonlinear modulation factor, it can quickly respond to and suppress high-disturbance and high-risk states. When the shear disturbance intensity is high or the temperature is high, the exponential term approaches zero and automatically reduces the opening of the molten iron outlet.

[0047] The theoretical basis of the above formula stems from the approximate functional relationship between the opening flow rate and the outlet angle in fluid dynamics. By introducing a nonlinear modulation factor, the slag-iron separation process is made robust to disturbances. The control logic is as follows: the higher the stratification interface, i.e., the more molten iron, the larger the taphole opening. The stronger the shear disturbance, the smaller the molten iron outlet opening, further reducing the overall opening and preventing the stratification interface from collapsing. Through this adjustment, the separation effect between molten iron and slag can be maximized, reducing the mixing of slag and iron.

[0048] In summary, an optimized method for separating slag and iron in a high-carbon ferrochrome submerged arc furnace has been developed.

[0049] The order of the embodiments is for illustrative purposes only and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0050] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A high carbon chromite hot furnace slag iron separation optimization method, characterized by, The method comprises the following steps: S1. Obtain the temperature of molten iron and slag, and respectively estimate the instantaneous density values of the molten iron and slag to obtain the density ratio of the molten iron and slag; ， in, At any moment The density ratio of molten iron to slag; It is the initial density of molten iron; It is the initial density of the slag; It is a moment The temperature of the molten iron; It is a moment The temperature of the slag; It is the standard temperature value; It is the decay coefficient of molten iron density as temperature increases; It is the logarithmic response coefficient of slag density as a function of temperature; It is the term for the temperature decay of molten iron; Used for dynamically estimating the instantaneous density of molten iron; It is the instantaneous density value of the slag; Based on the density ratio of the molten iron and slag, in combination with a density ratio threshold, the density separation potential between the molten iron and slag is judged; when the physical conditions for stable stratification are met, based on the density ratio of the molten iron and slag, in combination with dynamic viscosity and flow velocity, an interface height dynamic positioning model is constructed to obtain the stratification interface height, and the specific formula is as follows: ， wherein, is the instantaneous height of the slag-iron interface relative to the bottom of the slag extractor at time is the instantaneous height of the slag-iron interface relative to the bottom of the slag extractor at time is the working depth of the slag extractor; is the instantaneous height of the slag-iron interface relative to the bottom of the slag extractor at time is the weighted fusion temperature of the molten iron and the slag; is the dynamic viscosity of the molten iron at time , the weighted fusion temperature ; is the dynamic viscosity of the slag at time , the weighted fusion temperature ; is the flow rate of the molten iron at time ; is the flow rate of the slag at time ; is the acceleration due to gravity; is the regularization parameter to prevent numerical divergence; is the viscosity ratio weight coefficient; is the flow rate difference weight coefficient; is the viscosity ratio term; is the flow rate difference time correction term; is the reference flow rate difference; S2. Introduce a stratification shear disturbance intensity calculation formula to quantify the shear force, and obtain the shear disturbance intensity, and the specific formula is as follows: ， wherein, is the laminar shear force, i.e. the shear disturbance intensity, at time , denote the vertical velocity gradients of the slag and the hot metal, respectively, at the laminar interface.​ Based on the shear disturbance intensity, in combination with the stratification interface height, the molten iron and slag outlet opening ratio is adjusted, and separation optimization is carried out based on the molten iron and slag outlet opening ratio, and the specific calculation formula is as follows: ， wherein, is the molten iron slag outlet opening ratio at the time ; is the numerical stability correction term; is the stratification sensitivity index; is the disturbance index weight; is the shear disturbance intensity threshold value; is the reference temperature; denotes the height of the slag layer; is the stratification proportionality term; is the exponential disturbance decay term.

2. A high carbon chromitite hot furnace slag iron separation optimization method according to claim 1, characterized by, The S1 specifically comprises: Based on the density ratio of the molten iron and slag and the density ratio threshold, the density separation potential between the molten iron and slag is judged: when the density ratio of the molten iron and slag is greater than or equal to the density ratio threshold, it indicates that the current physical conditions for stable stratification are met; when the density ratio of the molten iron and slag is less than the density ratio threshold, it indicates that the stratification is difficult to form.

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