METHOD FOR SMELTING LOW-PHOSPHORUS HIGH-MANGANESE STEEL BASED ON REDUCTION DEPHOSPHORIZATION OF FERROMANGANESE

Abstract

A method for smelting low-phosphorus high-manganese steel based on reduction dephosphorization of ferromanganese is provided in the present application, relating to the technical field of high-manganese steel smelting, where the dephosphorization of ferromanganese is carried out under reducing atmosphere conditions through mediate-frequency induction furnace to obtain molten ferromanganese with lower phosphorus content, which is subsequently mixed with low phosphorus molten steel obtained by smelting in oxidative period of electric arc furnace in LF ladle refining furnace to make the Mn content of steel reach the requirement of high-manganese steel, and smelting is carried out under the condition of reducing atmosphere by adjusting the composition and temperature of the molten steel to meet the requirements of the target composition of the steel grade before tapping the steel.

Claims

1. A method for smelting low-phosphorus high-manganese steel based on reduction dephosphorization of ferromanganese, comprising following steps: S1, smelting high-manganese steel with scrap as a raw material by using an electric arc furnace, carrying out oxidative dephosphorization after the scrap is melted, removing oxidative dephosphorization slags after dephosphorization to obtain a low-phosphorus molten steel, crushing after cooling the oxidative dephosphorization slags obtained and putting into a slag ladle for later use, and transporting the low-phosphorus molten steel obtained via a ladle to an LF ladle refining furnace when a temperature is within a range of 1,460-1,580 degrees Celsius; taking medium-carbon ferromanganese as a raw material, and taking 20% of a mass of scrap for electric arc furnace smelting of high manganese steel as an additive amount, heating up the medium-carbon ferromanganese to a molten state by using a mediate-frequency induction furnace, and holding the medium-carbon ferromanganese in the molten state at a temperature of 1,300? C.-1,400 degrees Celsius; S2, adding a first slagging agent to the LF ladle refining furnace to prepare reducing slag after the low-phosphorus molten steel arrives at the LF ladle refining furnace, then adding a reducing agent into the LF ladle refining furnace for pre-deoxidation to obtain a low-phosphorus and low-oxygen molten steel, wherein an amount of the first slagging agent is 1.5%-2.0% of a mass of the low-phosphorus molten steel, an amount of the reducing agent is 0.1%-0.2% of the mass of the low-phosphorus molten steel; the first slagging agent is a mixture of CaO, CaF.sub.2, SiO.sub.2, and Al.sub.2O.sub.3, and a mass ratio of each substance in the mixture is: CaO accounts for 55%-65%, CaF.sub.2 accounts for 20%-30%, SiO.sub.2 accounts for 5%-15% and Al.sub.2O.sub.3 accounts for 2%-10%; adding a second slagging agent into the mediate-frequency induction furnace, wherein an amount of the second slagging agent is 1.5%-2.0% of a mass of the medium-carbon ferromanganese, the second slagging agent is a mixture of CaO, CaF.sub.2, SiO.sub.2 and CaC.sub.2, and a mass ratio of each substance in the mixture is: CaO accounts for 60%-70%, CaF.sub.2 accounts for 0%-15%, SiO.sub.2 accounts for 10%-20%, and CaC.sub.2 accounts for 5%-15%; S3, adding a SiCa alloy into the mediate-frequency induction furnace after forming covering slags in the mediate-frequency induction furnace, with an amount of the SiCa alloy being 0.5%-1.0% of the mass of medium-carbon ferromanganese, reacting for 10-20 minutes for reductive dephosphorization; S4, removing reductive dephosphorization slags in the mediate-frequency induction furnace to obtain a molten low-phosphorus ferromanganese after a reaction of the reductive dephosphorization in the S3 is completed, holding the reductive dephosphorization slags at a temperature of 1,350-1,450 degree Celsius and pouring into the slag ladle of the S1 stored with the oxidative dephosphorization slags; S5, adding the molten low-phosphorus ferromanganese obtained in the S4 into the low-phosphorus and low-oxygen molten steel obtained after S2 treatment, holding the molten steel at a temperature of 1,460-1,580 degree Celsius, and continuing a reduction refining in the LF ladle refining furnace for 10-15 minutes; S6, determining whether currently a Mn element content in the molten steel meets composition requirements of steel grades, if satisfied, then carrying out S7, or carrying out S8 if the Mn element content is lower than the composition requirements of steel grades; the composition requirements of steel grades are: C accounts for 1.00%-1.20%, Si accounts for 0.40%-0.60%, Mn accounts for 10%-15%, P accounts for less than 0.030% and S accounts for less than 0.010%; S7, holding the molten steel at the temperature of 1,460? C.-1,580? C., adding the reducing agent described in the S2 for final deoxidation and tapping, with an amount of the reducing agent being 0.018%-0.022% of a mass of the molten steel; and S8, adding medium-carbon ferromanganese into a current molten steel, smelting for 3-7 minutes, and returning to S6, wherein an addition amount of the medium-carbon ferromanganese is determined by a following formula: $\mathrm{addition}\mathrm{amount}\mathrm{of}\mathrm{the}\mathrm{medium}-\mathrm{carbon}\mathrm{ferromanganese}=\frac{\begin{array}{c}(\mathrm{Mn}\mathrm{element}\mathrm{proportion}\mathrm{of}a\mathrm{steel}\mathrm{grade}-\\ \mathrm{Mn}\mathrm{element}\mathrm{proportion}\mathrm{of}a\mathrm{sample})?\\ \mathrm{mass}\mathrm{of}\mathrm{smelted}\mathrm{high}\mathrm{manganese}\mathrm{steel}\end{array}}{\mathrm{Mn}\mathrm{element}\mathrm{proportion}\mathrm{of}\mathrm{medium}-\mathrm{carbon}\mathrm{ferromanganese}},$ with a unit of kg.

2. The method for smelting low-phosphorus high-manganese steel based on reduction dephosphorization of ferromanganese according to claim 1, wherein the reducing agent in the S2 is ferrosilicon, or SiC, or silicomanganese alloy, or silicon calcium alloy, or aluminum alloy, with a Si content of 70%-80%.

3. The method for smelting low-phosphorus high-manganese steel based on reduction dephosphorization of ferromanganese according to claim 1, wherein a C content in the medium-carbon ferromanganese in the S2 is 1.0%-2.5% of a total mass of ferromanganese, and a Mn content is 75%-80% of the total mass of ferromanganese.

4. The method for smelting low-phosphorus high-manganese steel based on reduction dephosphorization of ferromanganese according to claim 1, wherein mass proportions of effective components in the SiCa alloy in the S3 are: 50%-65% of Si content, and 30%-35% of Ca content.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0027] The FIGURE shows a schematic process illustrating a method of the present application.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The present application is illustrated in further detail below.

[0029] The present application provides a method for smelting low-phosphorus high-manganese steel based on reduction dephosphorization of ferromanganese, whereby ferromanganese is smelted in a mediate-frequency induction furnace to reduce the P content in ferromanganese to obtain low-phosphorus ferromanganese in a molten state, then the low-phosphorus ferromanganese is added into an LF ladle refining furnace to be mixed with low-phosphorus molten steel obtained by a oxidative smelting method of electric arc furnace to finally obtain a molten steel with low P content. In the present application, the production mode in the prior art that solid high-phosphorus ferromanganese of normal-temperature is directly added in the reductive period of the electric arc furnace is replaced, so that the P content in the final molten steel is greatly reduced; also, the oxidizability of the dephosphated slags oxidized by the electric arc furnace is utilized to oxidize the negative-valence phosphorus in the dephosphated slags reduced by the intermediate-frequency furnace into high-valence phosphorus, and the obtained phosphorus-containing slag can be used as raw materials for the production of phosphate fertilizer and other products; by adopting the method, the P content in high-manganese steel is effectively reduced, with improved production efficiency, reduced production cost in addition to improved performance of the high-manganese steel.

[0030] As shown in the FIGURE, the method for smelting low-phosphorus high-manganese steel based on reduction dephosphorization of ferromanganese includes the following steps: [0031] S1, smelting high-manganese steel with scrap as raw material using an electric arc furnace, carrying out oxidative dephosphorization after the scrap is melted, removing oxidative dephosphorization slags after the oxidative dephosphorization to obtain a low-phosphorus molten steel, crushing after cooling the oxidative dephosphorization slags obtained and putting into a slag ladle for later use, and transporting the low-phosphorus molten steel obtained via a ladle to an LF ladle refining furnace when a temperature is within a range of 1,460-1,580 degrees Celsius (? C.), where a P content is 0.005% when tapping at an oxidative period of electric arc furnace smelting; [0032] meanwhile, taking medium-carbon ferromanganese as a raw material, and taking 20% of a quality of scrap for electric arc furnace smelting of high manganese steel as an additive amount, heating up the medium-carbon ferromanganese to a molten state by using a mediate-frequency induction furnace, and holding the medium-carbon ferromanganese in the molten state at a temperature of 1,300? C.-1,400? C.; [0033] S2, adding a first slagging agent to the LF ladle refining furnace to prepare reducing slag after the low-phosphorus molten steel arrives at the LF ladle refining furnace, then adding a reducing agent into the LF ladle refining furnace for pre-deoxidation to obtain a low-phosphorus and low-oxygen molten steel, where an amount of the first slagging agent is 1.5%-2.0% of a mass of the low-phosphorus molten steel, an amount of the reducing agent is 0.1%-0.2% of the mass of the low-phosphorus molten steel; the first slagging agent is a mixture of CaO, CaF.sub.2, SiO.sub.2, and Al.sub.2O.sub.3, and a mass ratio of each substance in the mixture is: CaO accounts for 55%-65%, CaF.sub.2 accounts for 20%-30%, SiO.sub.2 accounts for 5%-15% and Al.sub.2O.sub.3 accounts for 2%-10%; [0034] adding a second slagging agent into the mediate-frequency induction furnace, where an amount of the second slagging agent is 1.5%-2.0% of a mass of the medium-carbon ferromanganese, the second slagging agent is a mixture of CaO, CaF.sub.2, SiO.sub.2 and CaC.sub.2, and a mass ratio of each substance in the mixture is: CaO accounts for 60%-70%, CaF.sub.2 accounts for 0%-15%, SiO.sub.2 accounts for 10%-20%, and CaC.sub.2 accounts for 5%-15%; [0035] S3, adding a SiCa alloy into the mediate-frequency induction furnace after forming covering slags in the mediate-frequency induction furnace, with an amount of the SiCa alloy being 0.5%-1.0% of the mass of medium-carbon ferromanganese, allowing a strong reducing environment to form in the mediate-frequency induction furnace, reacting for 10-20 minutes (min) for reductive dephosphorization; under such conditions, a dephosphorization rate of the medium-carbon ferromanganese can reach 40%-60%; [0036] S4, removing reductive dephosphorization slags in the mediate-frequency induction furnace to obtain a molten low-phosphorus ferromanganese after a reaction of the reductive dephosphorization in S3 is completed, holding the reductive dephosphorization slags at a temperature of 1,350? C.-1,450? C. and pouring into the slag ladle of S1 stored with the oxidative dephosphorization slags; oxidizing unstable phosphide with negative valence such as Ca.sub.3P.sub.2 in the oxidative dephosphorization slags using FeO, MnO and other oxides to produce P, P.sub.2O.sub.3, and P.sub.2O.sub.5, and so on, with the avoidance of phosphine gas generated by phosphide upon encountering water in a humid environment and environmental pollution, and the phosphorus-containing slag can be reused as phosphorus fertilizer resources after treatment; [0037] S5, adding the molten low-phosphorus ferromanganese obtained in S4 into the molten steel obtained after S2 treatment, holding the molten steel at a temperature of 1,460? C.-1,580? C., and continuing a reduction refining in the LF ladle refining furnace for 10-15 min; [0038] S6, determining whether currently a manganese (Mn) element content in the molten steel meets composition requirements of steel grades, if satisfied, then carrying out S7, or carrying out S8 if the Mn element content is lower than the composition requirements of steel grades; [0039] the composition requirements of steel grades include: C accounts for 1.00%-1.20%, Si accounts for 0.40%-0.60%, Mn accounts for 10%-15%, P accounts for less than 0.030% and S accounts for less than 0.010%; [0040] S7, holding the molten steel at the temperature of 1,460? C.-1,580? C., adding the reducing agent described in S2 for a final deoxidation and then tapping, where an amount of the reducing agent is 0.018%-0.022% of a mass of the molten steel; the final deoxidation refers to: stripping the oxygen elements within the molten steel to a low level using strong reducing agents such as calcium silicate alloys and aluminum rods, preventing problems such as tissue defects from occurring to degrade the properties of the steel after solidification; [0041] S8, adding medium-carbon ferromanganese into a current molten steel, smelting for 5 min, and returning to S6, where an addition amount of the medium-carbon ferromanganese is determined by a following formula:

[00002]$\mathrm{addition}\mathrm{amount}\mathrm{of}\mathrm{the}\mathrm{medium}-\mathrm{carbon}\mathrm{ferromanganese}=\frac{\begin{array}{c}(\mathrm{Mn}\mathrm{element}\mathrm{proportion}\mathrm{of}a\mathrm{steel}\mathrm{grade}-\\ \mathrm{Mn}\mathrm{element}\mathrm{proportion}\mathrm{of}a\mathrm{sample})?\\ \mathrm{mass}\mathrm{of}\mathrm{smelted}\mathrm{high}\mathrm{manganese}\mathrm{steel}\end{array}}{\mathrm{Mn}\mathrm{element}\mathrm{proportion}\mathrm{of}\mathrm{medium}-\mathrm{carbon}\mathrm{ferromanganese}},$

with a unit of kilogram (kg);

Embodiment 1

[0042] A method for smelting low-phosphorus high-manganese steel based on reduction dephosphorization of ferromanganese includes the following steps: [0043] S1, smelting high-manganese steel with scrap as raw material using an electric arc furnace, carrying out oxidative dephosphorization after the scrap is melted, removing oxidative dephosphorization slags after the oxidative dephosphorization to obtain a low-phosphorus molten steel, crushing after cooling the oxidative dephosphorization slags obtained and putting into a slag ladle for later use, and transporting the low-phosphorus molten steel obtained via a ladle to an LF ladle refining furnace when a temperature is within a range of 1,460? C., where a P content is 0.005% when tapping at an oxidative period of electric arc furnace smelting; [0044] meanwhile, taking medium-carbon ferromanganese as a raw material, and taking 20% of a quality of scrap for electric arc furnace smelting of high manganese steel as an additive amount, heating up the medium-carbon ferromanganese to a molten state by using a mediate-frequency induction furnace, and holding the medium-carbon ferromanganese in the molten state at a temperature of 1,300? C.; [0045] S2, adding a first slagging agent to the LF ladle refining furnace to prepare reducing slag after the low-phosphorus molten steel arrives at the LF ladle refining furnace, then adding ferrosilicon into the LF ladle refining furnace for pre-deoxidation to obtain a low-phosphorus and low-oxygen molten steel, where the first slagging agent is dosed at 1.5% of a mass of the low-phosphorus molten steel, and the reducing agent is dosed at 0.1% of the mass of the low-phosphorus molten steel; [0046] the first slagging agent is a mixture of CaO, CaF.sub.2, SiO.sub.2 and Al.sub.2O.sub.3 with proportions of 55%, 20%, 15% and 10%, respectively; [0047] adding a second slagging agent into the mediate-frequency induction furnace, where the second slagging agent is dosed at 1.5% of a mass of the medium-carbon ferromanganese, the second slagging agent is a mixture of CaO, CaF.sub.2, SiO.sub.2 and CaC.sub.2 with proportions of 70%, 15%, 10% and 5%, respectively; [0048] S3, adding a SiCa alloy into the mediate-frequency induction furnace after forming covering slags in the mediate-frequency induction furnace, with an amount of the SiCa alloy being 0.50% of the mass of medium-carbon ferromanganese, allowing a strong reducing environment to form in the mediate-frequency induction furnace, reacting for 10 min for reductive dephosphorization; under such conditions, the dephosphorization rate of the medium-carbon ferromanganese can reach 40%-60%; [0049] S4, removing reductive dephosphorization slags in the mediate-frequency induction furnace to obtain a molten low-phosphorus ferromanganese after a reaction of the reductive dephosphorization in S3 is completed, holding the reductive dephosphorization slags at a temperature of 1,350? C. and pouring into the slag ladle of S1 stored with the oxidative dephosphorization slags; oxidizing unstable phosphide with negative valence such as Ca.sub.3P.sub.2 in the oxidative dephosphorization slags using FeO, MnO and other oxides to produce P, P.sub.2O.sub.3, and P.sub.2O.sub.5, and so on, with the avoidance of phosphine gas generated by phosphide upon encountering water in a humid environment and environmental pollution, and the phosphorus-containing slag can be reused as phosphorus fertilizer resources after treatment; [0050] S5, adding the molten low-phosphorus ferromanganese obtained in S4 into the molten steel obtained after S2 treatment, mixing thoroughly for refining and compositional fine-tuning, mixing thoroughly for refining and compositional fine-tuning to meet the composition requirements of steel grades, holding the molten steel at a temperature of 1,460? C., and continuing a reduction refining in the LF ladle refining furnace for 10 min; [0051] S6, determining whether currently a Mn element content in the molten steel meets composition requirements of steel grades, if satisfied, then carrying out S7, or carrying out S8 if the Mn element content is lower than the composition requirements of steel grades; [0052] S7, holding the molten steel at the temperature of 1,460? C., adding the SiCa alloy for a final deoxidation and then tapping, where the reducing agent is dosed in 0.018% of a mass of the molten steel; [0053] S8, adding medium-carbon ferromanganese into a current molten steel, smelting for 3 min, and returning to S6, where an addition amount of the medium-carbon ferromanganese is determined by a following formula:

[00003]$\mathrm{addition}\mathrm{amount}\mathrm{of}\mathrm{the}\mathrm{medium}-\mathrm{carbon}\mathrm{ferromanganese}=\frac{\begin{array}{c}(\mathrm{Mn}\mathrm{element}\mathrm{proportion}\mathrm{of}a\mathrm{steel}\mathrm{grade}-\\ \mathrm{Mn}\mathrm{element}\mathrm{proportion}\mathrm{of}a\mathrm{sample})?\\ \mathrm{mass}\mathrm{of}\mathrm{smelted}\mathrm{high}\mathrm{manganese}\mathrm{steel}\end{array}}{\mathrm{Mn}\mathrm{element}\mathrm{proportion}\mathrm{of}\mathrm{medium}-\mathrm{carbon}\mathrm{ferromanganese}},$

with a unit of kg.

[0054] Embodiments 2-10 adopt the same preparation method as that of Embodiment 1, the difference lies in the quantity ratio of the ingredients and the selection of process parameters, see Table 1 for details.

TABLE-US-00001 TABLE 1 Ingredient ratios and process parameters of Embodiments 2-10 S1 S2 Temperature Amount of low- Temperature Amount Types Amount of phosphorus of medium- of first of of second S3 molten carbon reducing reducing reducing reducing SiCa Reacting steel ferromanganese agent agent agent agent alloy duration Embodiment 2 1,490? C. 1,325? C. 1.63% SiC 0.13% 1.63% 0.60% 10.5 min Embodiment 3 1,520? C. 1,350? C. 1.75% Silico- 0.15% 1.75% 0.70% 12.0 manganese min alloy Embodiment 4 1,550? C. 1,375? C. 1.88% Calcium- 0.18% 1.88% 0.80% 13.5 silicon min alloy Embodiment 5 1,580? C. 1,400? C. 2.00% Aluminium 0.20% 2.00% 0.90% 15.0 alloy min Embodiment 6 1,460? C. 1,300? C. 1.50% SiC 0.10% 1.50% 1.00% 16.0 min Embodiment 7 1,490? C. 1,325? C. 1.63% Silico- 0.13% 1.63% 0.50% 16.5 manganese min alloy Embodiment 8 1,520? C. 1,350? C. 1.75% Calcium- 0.15% 1.75% 0.60% 18.0 silicon min alloy Embodiment 9 1,550? C. 1,375? C. 1.88% Aluminum 0.18% 1.88% 0.70% 19.5 alloy min Embodiment 10 1,580? C. 1,400? C. 2.00% Silico- 0.20% 2.00% 0.80% 20.0 manganese min alloy S4 S5 S7 Temperature Temperature Temperature of reductive of of Amount S8 dephosphorization molten Reacting molten Types of of Reacting slag steel duration steel deoxidizer deoxidizer duration Embodiment 2 1,375? C. 1,580? C. 11.25 1,580? C. Aluminium 0.02% 4 min alloy min Embodiment 3 1,400? C. 1,550? C. 12.50 1,550? C. Calcium- 0.02% 5 min silicon min alloy Embodiment 4 1,425? C. 1,520? C. 13.75 1,520? C. Aluminium 0.02% 6 min alloy min Embodiment 5 1,450? C. 1,490? C. 15.00 1,490? C. Aluminium 0.02% 7 min alloy min Embodiment 6 1,300? C. 1,460? C. 10.00 1460? C. Calcium- 0.02% 3 min silicon min alloy Embodiment 7 1,375? C. 1,580? C. 11.25 1,580? C. Aluminium 0.02% 4 min alloy min Embodiment 8 1,400? C. 1,550? C. 12.50 1,550? C. Aluminium 0.02% 5 min alloy mir Embodiment 9 1,425? C. 1,520? C. 13.75 1,520? C. Calcium- 0.02% 6 min silicon min alloy Embodiment 10 1,450? C. 1,490? C. 15.00 1,490? C. Aluminium 0.02% 7 min alloy min

[0055] Table 2 shows the mass ratio of each component of the first slagging agent and the second slagging agent in Embodiments 2-10.

TABLE-US-00002 TABLE 2 Components of the first slagging Components of the second slagging agent agent Embodiment 2 57.5% CaO, 22.5% CaF.sub.2, 12.5% SiO.sub.2, 60% CaO, 5% CaF.sub.2, 20% SiO.sub.2, 7.5% Al.sub.2O.sub.3 15% CaC.sub.2 Embodiment 3 60.0% CaO, 25.0% CaF.sub.2, 10.5% SiO.sub.2, 62% CaO, 5% CaF.sub.2, 18% SiO.sub.2, 7.5% Al.sub.2O.sub.3 15% CaC.sub.2 Embodiment 4 62.5% CaO, 27.5% CaF.sub.2, 7.5% SiO.sub.2, 64% CaO, 5% CaF.sub.2, 16% SiO.sub.2, 4.5% Al.sub.2O.sub.3 15% CaC.sub.2 Embodiment 5 65% CaO, 28.0% CaF.sub.2, 5% SiO.sub.2, 2% 66% CaO, 0% CaF.sub.2, 19% SiO.sub.2, Al.sub.2O.sub.3 15% CaC.sub.2 Embodiment 6 55% CaO, 20.0% CaF.sub.2, 15% SiO.sub.2, 65% CaO, 10% CaF.sub.2, 10% SiO.sub.2, 10.0% Al.sub.2O.sub.3 15% CaC.sub.2 Embodiment 7 57.5% CaO, 22.5% CaF.sub.2, 12.5% SiO.sub.2, 68% CaO, 10% CaF.sub.2, 12% SiO.sub.2, 7.5% Al.sub.2O.sub.3 10% CaC.sub.2 Embodiment 8 60.0% CaO, 25% CaF.sub.2, 10.0% SiO.sub.2, 70% CaO, 10% CaF.sub.2, 15% SiO.sub.2, 4.5% Al.sub.2O.sub.3 5% CaC.sub.2 Embodiment 9 62.5% CaO, 27.5% CaF.sub.2, 7.5% SiO.sub.2, 65% CaO, 0% CaF.sub.2, 20% SiO.sub.2, 2.5% Al.sub.2O.sub.3 15% CaC.sub.2 Embodiment 10 65% CaO, 28.0% CaF.sub.2, 5% SiO.sub.2, 2% 65% CaO, 0% CaF.sub.2, 20% SiO.sub.2, Al.sub.2O.sub.3 15% CaC.sub.2

[0056] Table 3 shows the phosphorus content of the low-phosphorus high-manganese steel smelted based on reduction dephosphorization of ferromanganese prepared in Embodiments 1-10.

TABLE-US-00003 TABLE 3 P content of finished steel Embodiment 1 0.028% Embodiment 2 0.026% Embodiment 3 0.022% Embodiment 4 0.027% Embodiment 5 0.025% Embodiment 6 0.020% Embodiment 7 0.026% Embodiment 8 0.022% Embodiment 9 0.019% Embodiment 10 0.021%

[0057] As can be seen from Table 3: the data in Table 3 is the phosphorus content in the finished steel obtained by each embodiment, and the lower the phosphorus content in the finished steel, the more ferromanganese dephosphorization is required.

[0058] Finally, the above embodiments serve only to illustrate the technical schemes of the present application and are not intended to be limiting, and although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that modifications or equivalent replacements can be made to the technical schemes of the present application without departing from the purpose and scope of the technical schemes of the present application, which should be covered by the scope of the claims of the present application.