阅读说明：本技术 一种冷轧不锈钢退火酸洗工艺及酸洗设备 (Annealing and pickling process and pickling equipment for cold-rolled stainless steel ) 是由 王耀 廖砚林 周云根 贾鸿雷 李春明 吴迪青 于 2021-07-23 设计创作，主要内容包括：本发明涉及种冷轧不锈钢退火酸洗工艺及酸洗设备,酸洗工艺控制退火炉出口带钢的温度,使高温的带钢与低温的酸洗液直接接触,让其在表面发生强烈的物理化学反应,快速酸洗剥离表层粗大的氧化铁皮,并通过调控梯级溢流连续酸洗系统中酸洗液的氧化还原特性来提高酸洗效率,以高效去除奥氏体、铁素体和马氏体不锈钢上残留的氧化铁皮,该工艺充分利用了退火炉的余温,并且降低了酸液温度,节约了能耗,实现冷轧不锈钢带钢低耗高效酸洗的目的。(The invention relates to a cold-rolled stainless steel annealing and pickling process and pickling equipment, wherein the pickling process controls the temperature of strip steel at the outlet of an annealing furnace, so that the high-temperature strip steel is in direct contact with low-temperature pickling solution, strong physical and chemical reaction is generated on the surface of the strip steel, the rough iron scale on the surface layer is quickly pickled and stripped, the pickling efficiency is improved by regulating and controlling the redox characteristic of the pickling solution in a step overflow continuous pickling system, and the residual iron scale on austenitic, ferritic and martensitic stainless steel is efficiently removed.)

1. The annealing and pickling process of the cold-rolled stainless steel is characterized by comprising the following steps of:

step 1), after the cold-rolled stainless steel enters an annealing furnace to regulate and control components, controlling the temperature of the cold-rolled stainless steel strip steel at the outlet of a cooling section of the annealing furnace to be 60-200 ℃ by regulating the cooling capacity of the cooling section of the annealing furnace;

step 2), the cold-rolled stainless steel strip output from the outlet of the cooling section of the annealing furnace is subjected to heat preservation regulation and control, and then directly enters a pre-pickling tank for pickling at a temperature higher than that of a pickling solution, the pickling medium of the pre-pickling tank is HCl, the concentration of the HCl is 20-60 g/L, and meanwhile, the pickling medium contains Fe²⁺And Fe³⁺；

Step 3), the cold-rolled stainless steel strip which is pickled in the pre-pickling tank enters a neutral salt electrolytic tank for pickling after being squeezed by a squeezing roller; then enters a step overflow continuous pickling system with a plurality of sub-tanks connected in series for continuous pickling after passing through a drying roller; the neutral salt in the neutral salt electrolytic cell is Na₂SO₄The acid washing medium of the step overflow continuous acid washing system is HCl, the concentration of the HCl is 20-150 g/L, and meanwhile, the acid washing solution contains Fe²⁺And Fe³⁺；

And 4), allowing the cold-rolled stainless steel strip subjected to pickling by the step overflow continuous pickling system to enter a passivation tank for passivation, and finally allowing the cold-rolled stainless steel strip to enter a multi-stage rinsing system for rinsing, drying and rolling.

2. The cold rolled stainless steel annealing and pickling process according to claim 1, characterized in that: in the step 2), the temperature of the cold-rolled stainless steel strip entering the tank of the pre-pickling tank is higher than 100 ℃.

3. The cold rolled stainless steel annealer and pickle in accordance with claim 1The process is characterized by comprising the following steps: in the step 3), Fe is regulated and controlled by adding an oxidant²⁺And Fe³⁺The redox characteristics of the pickling solution are controlled by the proportion.

4. The cold rolled stainless steel annealing and pickling process according to claim 1, characterized in that: the step overflow continuous pickling system in the step 3) is formed by connecting a plurality of sub-tanks in series to form step overflow and form a multi-section low-temperature pickling tank, the acid liquor concentration of the multi-section low-temperature pickling tank is sequentially increased, and the total iron content is sequentially decreased.

5. The cold-rolled stainless steel annealing and pickling process according to claim 4, characterized in that: the step overflow continuous pickling system in the step 3) is at least provided with 2 sections of low-temperature pickling tanks, wherein the pickling medium in the 1 st section is a reducing system, and the pickling medium in the last section is a strong oxidizing system.

6. The cold rolled stainless steel annealing and pickling process according to claim 1, characterized in that: the passivation solution in the passivation tank in the step 4) is one or a combination of nitric acid, hydrogen peroxide and citric acid.

7. The cold rolled stainless steel annealing and pickling process according to claim 1, characterized in that: the multi-stage rinsing system in the step 4) is composed of 3-6 stages of step overflow rinsing systems, wherein the pressure of the rinsing water of the last stage is 5-10 kg, and the pressure of the rinsing water of the rest stages is 2-6 kg.

8. The cold rolled stainless steel annealing and pickling process according to claim 1, characterized in that: in the step 2), Fe is regulated and controlled by adopting a mode of online adding of polybasic weak acid and circulating filtration and separation²+ and Fe³⁺Total iron content.

9. The annealing and pickling equipment for the cold-rolled stainless steel is characterized by comprising the following steps: comprises a strip steel transmission device, an uncoiler, a welding machine, a loop, an annealing furnace, a heat preservation cavity, a temperature control device, a pre-cleaning tank, an electrolytic tank, a step overflow continuous pickling tank, a passivation tank, a rinsing tank and a dryer, wherein the uncoiler, the welding machine, the loop, the annealing furnace, the heat preservation cavity, the temperature control device, the pre-cleaning tank, the electrolytic tank, the step overflow continuous pickling tank, the passivation tank, the rinsing tank and the dryer are sequentially arranged along the advancing direction of strip steel.

10. The annealing and pickling equipment for cold-rolled stainless steel according to claim 9, characterized in that: the device is characterized by further comprising a regulation and control system and an oxidation potential detection, wherein the regulation and control system is connected with each acid tank of the step overflow continuous pickling tank and is arranged in a linkage manner, the oxidation-reduction characteristic of the pickling medium in the step overflow continuous pickling tank and an automatic valve for adding the oxidant are arranged in the linkage manner, the oxidation potential detection judges the oxidation-reduction characteristic of the pickling medium by detecting the oxidation-reduction potential of the acid liquid in the step overflow continuous pickling tank, and the control and control system is used for adding the oxidant into the corresponding pickling tank of the step overflow continuous pickling tank.

Technical Field

The invention relates to the technical field of strip steel surface cleaning, in particular to a cold-rolled stainless steel annealing and pickling process and pickling equipment.

Background

The surface quality of stainless steel is one of the key factors influencing the improvement of product performance. A layer of compact metal oxide film is formed on the surface of the cold-rolled stainless steel strip in the rolling process, and the oxide film can seriously reduce the surface quality of the cold-rolled stainless steel strip and aggravate the abrasion of the roller.

After the cold-rolled stainless steel strip steel is annealed and mechanically descaled, the acid pickling process of the austenitic stainless steel is Na₂SO₄(Electrolysis) acid washing → scrubbing → Mixed acid (HNO)₃+ HF) pickling, pickling process of ferrite and martensite being Na₂SO₄(Electrolysis) Pickling → brushing → HNO₃And (electrolytic) acid washing, and then multi-stage rinsing and drying. The current pickling process has the defects of high acid consumption, high brush roll replacement frequency, high power consumption and the like.

In addition, the pickling conditions of the cold-rolled stainless steel strip are severe, and the pickling time is long, so that the development of high-efficiency pickling equipment and process is urgently needed, the pollution of high-temperature and high-concentration chemical reagents to the environment is reduced, the cleaning speed is accelerated, and meanwhile, the strip steel with high surface quality is obtained.

Disclosure of Invention

The invention aims to provide a low-consumption and high-efficiency annealing and pickling process for cold-rolled stainless steel.

The specific scheme is as follows:

a cold-rolled stainless steel annealing and pickling process comprises the following steps:

step 1), after the cold-rolled stainless steel enters an annealing furnace to regulate and control components, controlling the temperature of the cold-rolled stainless steel strip steel at the outlet of a cooling section of the annealing furnace to be 60-200 ℃ by regulating the cooling capacity of the cooling section of the annealing furnace;

step 2), quitThe cold-rolled stainless steel strip steel output from the outlet of the cooling section of the furnace is subjected to heat preservation regulation and control, then directly enters a pre-pickling tank for pickling at a temperature higher than that of pickling solution, the pickling medium of the pre-pickling tank is HCl, the concentration of the HCl is 20-60 g/L, and meanwhile, the pickling medium contains Fe²⁺And Fe³⁺；

Step 3), the cold-rolled stainless steel strip which is pickled in the pre-pickling tank enters a neutral salt electrolytic tank for pickling after being squeezed by a squeezing roller; then enters a step overflow continuous pickling system with a plurality of sub-tanks connected in series for continuous pickling after passing through a drying roller; the neutral salt in the neutral salt electrolytic cell is Na₂SO₄The acid washing medium of the step overflow continuous acid washing system is HCl, the concentration of the HCl is 20-150 g/L, and meanwhile, the acid washing solution contains Fe²⁺And Fe³⁺；

And 4), allowing the cold-rolled stainless steel strip subjected to pickling by the step overflow continuous pickling system to enter a passivation tank for passivation, and finally allowing the cold-rolled stainless steel strip to enter a multi-stage rinsing system for rinsing, drying and rolling.

Further, in the step 2), the temperature of the cold-rolled stainless steel strip entering the tank of the pre-pickling tank is higher than 100 ℃.

Further, in the step 3), Fe is regulated and controlled by adding an oxidant²⁺And Fe³⁺The redox characteristics of the pickling solution are controlled by the proportion.

Further, in the step overflow continuous pickling system in the step 3), a plurality of sub-tanks are connected in series to form step overflow, and a multi-section low-temperature pickling tank is formed, the acid liquor concentration of the multi-section low-temperature pickling tank is sequentially increased, and the total iron content is sequentially decreased.

Further, the step overflow continuous pickling system in the step 3) at least comprises 3 sections of low-temperature pickling tanks, wherein the pickling medium in the 2 nd section is a reducing system, and the pickling medium in the last section is a strong oxidizing system.

Further, the passivation solution in the passivation tank in the step 4) is one or a combination of nitric acid, hydrogen peroxide and citric acid.

Further, the multi-stage rinsing system in the step 4) is composed of 3-6 stages of step overflow rinsing systems, wherein the pressure of the rinsing water in the last stage is 5-10 kg, and the pressure of the rinsing water in the rest stages is 2-6 kg.

Further, the Fe is regulated and controlled by adopting a mode of online adding of polybasic weak acid and circulating filtration and separation in the step 2)²+ and Fe³⁺Total iron content.

The invention also provides cold-rolled stainless steel annealing and pickling equipment which comprises a strip steel transmission device, and an uncoiler, a welding machine, a loop, an annealing furnace, a heat preservation cavity, a temperature control device, a pre-cleaning tank, an electrolytic tank, a step overflow continuous pickling tank, a passivation tank, a rinsing tank and a dryer which are sequentially arranged along the advancing direction of the strip steel.

The device is characterized by further comprising a regulation and control system and oxidation potential detection, wherein the regulation and control system is connected with each acid tank of the step overflow continuous pickling tank, the oxidation-reduction characteristic of the pickling medium in the step overflow continuous pickling tank is in linkage with an automatic valve for adding the oxidant, the oxidation potential detection judges the oxidation-reduction characteristic of the pickling medium by detecting the oxidation-reduction potential of the acid liquid in the step overflow continuous pickling tank, and the regulation and control system is controlled to add the oxidant into the corresponding pickling tank of the step overflow continuous pickling tank.

Compared with the prior art, the annealing and pickling process for the cold-rolled stainless steel has the following advantages: the annealing and pickling process of the cold-rolled stainless steel provided by the invention cancels an annealing furnace outlet drying device, a mechanical descaling process and a pickling section mechanical brushing device, and a step overflow continuous pickling process system without nitric acid and hydrofluoric acid is adopted to realize the rapid cleaning of the strip steel, meanwhile, the temperature of the strip steel at the outlet of the annealing furnace is controlled, so that the high-temperature strip steel is directly contacted with the low-temperature pickling solution, the strong physical and chemical reaction is generated on the surface of the strip steel, the rough and large iron scales on the surface layer are quickly pickled and stripped, and the pickling efficiency is improved by regulating and controlling the oxidation-reduction characteristic of the pickling solution in the step overflow continuous pickling system so as to efficiently remove residual iron oxide scales on austenitic stainless steel, ferritic stainless steel and martensitic stainless steel, the process fully utilizes the residual temperature of the annealing furnace, reduces the temperature of the acid liquor, saves energy and realizes the purpose of low-consumption and high-efficiency acid pickling of the cold-rolled stainless steel strip.

Drawings

FIG. 1 shows a schematic diagram of a cold rolled stainless steel annealing and pickling plant.

Detailed Description

To further illustrate the various embodiments, the invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. Those skilled in the art will appreciate still other possible embodiments and advantages of the present invention with reference to these figures. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.

The invention will now be further described with reference to the accompanying drawings and detailed description.

Example 1

The embodiment provides a cold-rolled stainless steel annealing and pickling process, which is characterized in that the temperature of strip steel at the outlet of an annealing furnace is controlled, high-temperature strip steel directly enters a pickling tank to be pickled, an outlet drying device of the annealing furnace, a mechanical descaling process and a mechanical brushing device of a pickling section are eliminated, the strip steel is quickly cleaned through a step overflow continuous pickling process system without nitric acid and hydrofluoric acid, and the energy consumption and the acid consumption are reduced simultaneously to obtain the strip steel with high surface quality, and the process specifically comprises the following steps:

and step 1), after the cold-rolled stainless steel enters an annealing furnace to regulate and control components, controlling the temperature of the cold-rolled stainless steel strip at an outlet of an air cooling section of the annealing furnace to be 60-200 ℃ by regulating the cooling capacity of the cooling section of the annealing furnace. In this embodiment, the cold-rolled stainless steel strip from the cooling section of the annealing furnace is subjected to air cooling, high-pressure mist cooling and temperature control in the heat preservation chamber to control the temperature of the cold-rolled stainless steel strip entering the tank, so that the cold-rolled stainless steel strip enters the pre-pickling tank at a high temperature for pickling.

And 2) directly feeding the cold-rolled stainless steel strip into a pre-pickling tank for pickling at a high temperature after passing through a heat preservation cavity. In the embodiment, the pre-pickling tank has a large conical bottom structure, the pickling medium of the pre-pickling tank is HCl, the concentration of the HCl is 20-60 g/L, and the pickling medium contains Fe²⁺And Fe³⁺Is high and highWhen the warm cold-rolled stainless steel strip is contacted with the low-temperature pickling solution, the surface can generate strong physical and chemical reactions to rapidly pickle and strip the rough and large iron scales on the surface layer. Preferably, the temperature of the cold-rolled stainless steel strip in the groove is higher than 100 ℃, so that when the cold-rolled stainless steel strip is contacted with the pickling solution, the surface can generate strong physical and chemical reactions to rapidly pickle and strip the rough and large iron scales on the surface layer.

In this embodiment, in step 2), Fe is regulated and controlled by on-line feeding of weak polybasic acid and cyclic filtration and separation²⁺And Fe³⁺Total iron content.

Step 3), the cold-rolled stainless steel strip which is pickled in the pre-pickling tank enters a neutral salt electrolytic tank for pickling after being squeezed by a squeezing roller; then enters a step overflow continuous pickling system with a plurality of sub-tanks connected in series for continuous pickling after passing through a drying roller.

In this example, the neutral salt in the neutral salt electrolytic cell was Na₂SO₄The step overflow continuous pickling system comprises 2-4 sections of low-temperature pickling tanks, wherein the pickling medium of each low-temperature pickling tank is HCl, the concentration of the HCl is 20-150 g/L, and the pickling solution contains Fe²⁺And Fe³⁺It can regulate and control Fe by adding oxidant²⁺And Fe³⁺The proportion controls the oxidation-reduction characteristic of the pickling solution to ensure the pickling effect.

In the pickling operation in the embodiment, the neutral salt and the multistage hydrochloric acid pickling solution are electrolyzed, and the oxidation-reduction characteristics of the pickling solution are controlled to realize the effect of efficiently removing the iron scales on the cold-rolled stainless steel strip with low consumption.

Preferably, the sub-tanks of the step overflow continuous pickling system realize step overflow through communicating pipes, the acid liquor concentration is sequentially increased progressively, and the total iron content is sequentially decreased progressively.

Preferably, the oxidizability of the pickling medium of the 2-4-stage low-temperature pickling tank is gradually improved, more preferably, the pickling medium of the 2 nd stage is a reducing system, and the pickling medium of the last stage is a strong oxidizing system.

And 4) allowing the cold-rolled stainless steel strip subjected to the acid washing by the step overflow continuous acid washing system to enter a passivation tank for passivation, and finally allowing the cold-rolled stainless steel strip to enter a multi-stage rinsing system for rinsing, drying and rolling.

In this embodiment, the passivation solution in the passivation tank is one or a combination of nitric acid, hydrogen peroxide and citric acid.

The multi-stage rinsing system is composed of a 3-6 stage step overflow rinsing system, a pH meter and a conductivity meter are arranged to monitor rinsing liquid, wherein the pressure of the rinsing water in the first stages is 2-6 kg, and the pressure of the rinsing water in the last stage is 5-10 kg, so that a better rinsing effect is realized.

The annealing and pickling process for the cold-rolled stainless steel provided by the embodiment cancels an annealing furnace outlet drying device, a mechanical descaling process and a pickling section mechanical brushing device, and a step overflow continuous pickling process system without nitric acid and hydrofluoric acid is adopted to realize the rapid cleaning of the strip steel, meanwhile, the temperature of the strip steel at the outlet of the annealing furnace is controlled, so that the high-temperature strip steel is directly contacted with the low-temperature pickling solution, the strong physical and chemical reaction is generated on the surface of the strip steel, the rough and large iron scales on the surface layer are quickly pickled and stripped, and the pickling efficiency is improved by regulating and controlling the oxidation-reduction characteristic of the pickling solution in the step overflow continuous pickling system so as to efficiently remove residual iron oxide scales on austenitic stainless steel, ferritic stainless steel and martensitic stainless steel, the process fully utilizes the residual temperature of the annealing furnace, reduces the temperature of the acid liquor, saves energy consumption and realizes the purpose of low-consumption and high-efficiency acid pickling of the cold-rolled stainless steel strip.

Example 2

Referring to fig. 1, a pickling apparatus for implementing the annealing and pickling process of the cold-rolled stainless steel according to embodiment 1 includes a strip steel conveying device (not shown in the figure), and an uncoiler 1, a welding machine 2, a loop 3, an annealing furnace 4, a heat preservation chamber 5, a temperature control device, a pre-cleaning tank 9, an electrolysis tank 10, a # 1 acid tank 12, a # 2 acid tank 16, a passivation tank 18, a rinsing tank 20, and a drying machine 22, which are sequentially disposed along the traveling direction of a strip steel 23.

Wherein, the temperature control device is provided with a fan 6 and a heater 7, the temperature of the strip steel can be controlled by controlling the power of the fan and the heater 7, and the temperature control device is also provided with a plate temperature instrument 8 for detecting and controlling the plate temperature of the strip steel; the electrolyte circulating tank 11 is connected with the electrolytic cell 10 through a circulating pump; the 1# acid tank 13 is connected with the 1# acid tank 12 and the 2# acid tank 17 through a circulating pump 14 and a 2# acid tank 16, the passivation tank 19 is connected with the passivation tank 18 through a circulating pump, and the rinse tank 21 is connected with the rinse tank 20 through a circulating pump. Although fig. 1 shows only two acid tanks, that is, the 1# acid tank 12 and the 2# acid tank 16, the number of acid tanks is not limited to this, and the number of acid tanks may be increased or decreased depending on the number of stages of actual pickling. A heat exchanger 15 is arranged between each acid tank and the acid tank to ensure that the temperature of the pickling solution in the acid tank can be kept low after pickling.

Strip steel 23 is opened a book the operation via decoiler 1, and carry by transmission device toward back end process direction after the operation of welding machine 2 and loop 3, it carries out the heat treatment through annealing stove 4 earlier, the cooling zone output from annealing stove 4 after the heat treatment is accomplished, the strip steel that the annealing stove cooling zone came out is through the regulation water jacket circulation volume and the temperature control of heat preservation chamber 5 of annealing stove, with the waste heat of at utmost utilization annealing stove, let the strip steel that comes out maintain certain high temperature, and after regulating and control through temperature regulating device, let high temperature strip steel and microthermal pickle contact surface can take place strong physical chemistry reaction and peel off the thick iron scale in top layer fast acid cleaning.

The hot high-temperature strip steel sequentially passes through the pre-cleaning tank 9, the electrolytic tank 10, the No. 1 acid tank 12 and the No. 2 acid tank 16 for acid cleaning, enters the passivation tank 18 for passivation, improves the whiteness and the corrosion resistance of the strip steel, and finally enters the rinsing tank 20 and the dryer 22 for rinsing and air drying to obtain the strip steel with high surface quality.

In this embodiment, the strip steel strip pickling system further comprises a regulation and control system 24 and an oxidation potential detection 25, the regulation and control system is connected with each pickling tank of the multiple sections of pickling tanks, the oxidation-reduction characteristics of the pickling medium in each pickling tank and the automatic valve for adding the oxidant are arranged in a linkage manner, the oxidation potential detection determines the oxidation-reduction characteristics of the pickling medium by detecting the oxidation-reduction potential of the acid liquor in each pickling tank, and the regulation and control system is controlled to add the oxidant into the corresponding pickling tank of the multiple sections of pickling tanks, so that the oxidation-reduction characteristics of the pickling medium in each pickling tank of the multiple sections of pickling tanks are automatically controlled, and the strip steel cleaning effect and consistency are further ensured.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.