KR100293202B1 - REGENERATION METHOD OF WASTE NOx GAS GENERATED WHEN PICKLING STAINLESS STEEL WITH MIXED ACID OF SULFURIC ACID AND HYDROGEN PEROXIDE - Google Patents
REGENERATION METHOD OF WASTE NOx GAS GENERATED WHEN PICKLING STAINLESS STEEL WITH MIXED ACID OF SULFURIC ACID AND HYDROGEN PEROXIDE Download PDFInfo
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- KR100293202B1 KR100293202B1 KR1019960070086A KR19960070086A KR100293202B1 KR 100293202 B1 KR100293202 B1 KR 100293202B1 KR 1019960070086 A KR1019960070086 A KR 1019960070086A KR 19960070086 A KR19960070086 A KR 19960070086A KR 100293202 B1 KR100293202 B1 KR 100293202B1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/08—Iron or steel
- C23G1/085—Iron or steel solutions containing HNO3
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/36—Regeneration of waste pickling liquors
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Abstract
Description
본 발명은 스테인레스강의 혼산 산세 공정에서 발생하는 산세 배가스중 산화질소류를 효율적으로 제거하는 방법에 관한 것이며, 보다 상세하게는 황산을 이용하여 일차적으로 NOx가스를 제거한 다음 잔류하는 NOx가스를 과산화수소를 사용하여 효율적으로 제거하는 방법에 관한 것이다.The present invention relates to a method for efficiently removing nitrogen oxides from the pickling flue gas generated in the mixed acid pickling process of stainless steel, and more specifically, to remove the NOx gas first using sulfuric acid, and then to use the residual NOx gas as hydrogen peroxide. It relates to a method for efficient removal.
일반적으로 스테인레스강을 산세하는데는 적정비의 질산과 불산으로된 혼산(이하, "혼산"이라 한다)이 가장 산세성이 우수한 것으로 알려져 있고, 대부분 사용되고 있다.In general, pickling stainless steel is known to have the best pickling property, and a mixed acid composed of nitric acid and hydrofluoric acid (hereinafter referred to as "mixed acid") at an appropriate ratio is used most of the time.
그러나 상기 혼산은 산세시 NOx 가스를 발생하며 이는 완벽하게 처리하지 않은 채로 대기중에 방출되면 광화학 스모그의 전구 물질이 되기도 하고 대기중의 수분과 접촉하여 질산을 생성하여 산성비의 원인이 되기도 한다. 그외에도 호흡기 질환 및 하천과 해양을 부영양화하는 원인이 되므로 적조 현상을 초래하기도 한다.However, the mixed acid generates NOx gas during pickling, which when released into the atmosphere without being completely treated, may be a precursor of photochemical smog or may generate nitric acid in contact with moisture in the atmosphere, causing acid rain. In addition, respiratory diseases and eutrophication of rivers and oceans may cause red tide.
따라서 이같은 NOx를 제거하기 위한 여러 가지 방법이 개발되어 왔다. 최근 Nicholas J. Rossi의 논문 "How to control NOx", Pollution Engineering, April 1995, pp 50-52, 미국 특허 제4,938,838 및 유럽 특허 제0 267 166 A2 등의 공지기술에서 제시된 바와 같이 과산화수소를 이용한 NOx 제거 효과가 매우 우수한 것으로 평가받고 있다.Therefore, various methods for removing such NOx have been developed. Removal of NOx using hydrogen peroxide, as presented in recent work by Nicholas J. Rossi, "How to control NOx", Pollution Engineering, April 1995, pp 50-52, US Patent 4,938,838 and European Patent 0 267 166 A2. It is evaluated that the effect is very excellent.
그러나 과산화수소는 고가이므로 상기 기술은 경제적 측면에서 매우 열등하며, 이를 극복하기 위해서는 과산화수소의 사용량을 최소화하고 효율을 극대화할 수 있는 개선된 방법을 필요로 한다.However, because hydrogen peroxide is expensive, the technology is very inferior in terms of economics, and to overcome this, there is a need for an improved method of minimizing the amount of hydrogen peroxide used and maximizing efficiency.
과산화수소에 의한 효과를 향상시키기 위해서는 하기 반응식에서 보듯이, 과산화수소가 식2의 반응을 일으키기 전에 식3의 반응에 사용되도록 하여야 한다.In order to improve the effect by hydrogen peroxide, hydrogen peroxide must be used in the reaction of Eq. 3 before the reaction of Eq.
즉, 식4의 반응이 일어나면 과산화수소가 비효율적으로 소비되며, 또한 식2의 반응이 식3의 반응보다 빨리 일어나면 아질산이 질산으로 산화되기 전에 NOx가스가 먼저 생성되며 일단 NOx가스가 생성되고 나면 제거하기가 어렵게 된다.That is, hydrogen peroxide is inefficiently consumed when the reaction of Equation 4 occurs, and when the reaction of Equation 2 occurs earlier than the reaction of Equation 3, NOx gas is first generated before nitrous acid is oxidized to nitric acid, and once NOx gas is generated, Becomes difficult.
그러므로 과산화수소를 사용하는 가장 효율적인 방법은 산세 시점에 적정량의 과산화수소가 존재하도록 하는 것이다. 즉, 식1 반응의 산세가 일어난 직후 또는 식2의 반응이 일어나기 전에 식3의 반응이 일어남으로써 NOx가 생성되기 전에 아질산을 질산으로 산화시켜 질산을 재생시키고, 또한 식4의 반응이 일어나기 전에 식3의 반응을 수행함으로써 과산화수소의 소비를 방지하도록 전체 반응을 유도하는 것이 가장 효율적이라는 점을 본 발명의 주안점으로 착안하게 된 것이다.Therefore, the most efficient way to use hydrogen peroxide is to ensure that an adequate amount of hydrogen peroxide is present at the time of pickling. That is, nitrous acid is oxidized to nitric acid to regenerate nitric acid before NOx is generated by immediately following the pickling of the reaction of Formula 1 or before the reaction of Formula 2 occurs, and then before the reaction of Formula 4 occurs, The main focus of the present invention is that it is most efficient to induce the entire reaction to prevent the consumption of hydrogen peroxide by carrying out the reaction of 3.
그러나 스테인레스 산세 공장은 코일을 연속적으로 산세하고 산세조의 길이가 수십m에 달하는 대형 공장이 대부분이기 때문에 적정량의 과산화수소를 산세 순간이나 혹은 코일의 상하면에 균일하고도 연속적으로 첨가하기가 매우 곤란하다. 또한 산세전에 과산화수소를 첨가하면 식3의 반응이 일어나기 전에 식4의 반응이 일어나게 되므로 과산화수소의 제거 효율이 감소한다.However, stainless steel pickling plants continually pick up the coils and most of the large plants have a length of several tens of meters, so it is very difficult to add an appropriate amount of hydrogen peroxide uniformly and continuously at the time of pickling or at the top and bottom of the coil. In addition, if hydrogen peroxide is added before pickling, the reaction of Eq. 4 occurs before the reaction of Eq. 3, thus reducing the hydrogen peroxide removal efficiency.
또한 잔류 NOx를 제거할 목적으로 과량의 과산화수소를 첨가한다면 비경제적일 뿐만 아니라 과산화수소의 휘발에 따른 발열이 과다하여 혼산 산세액의 온도가 상승되는 문제가 있는 것이다.In addition, if excess hydrogen peroxide is added for the purpose of removing residual NOx, it is not only uneconomical but there is a problem that the temperature of the mixed acid wash liquid is increased due to excessive heat generation due to volatilization of the hydrogen peroxide.
이에 본 발명의 목적은 황산을 첨가하여 초기에 생성된 NOx가스를 일정시간 제거한 다음 과산화수소를 연속 사용하여 황산의 효능이 감소한 다음 잔류 내지는 생성된 NOx 가스와 과산화수소의 반응에 의해 산화질소를 질산으로 재생하는 방법을 제공하려는데 있다.Accordingly, an object of the present invention is to remove the NOx gas initially produced by adding sulfuric acid for a predetermined time, and then to reduce the efficacy of sulfuric acid by using hydrogen peroxide continuously, and to regenerate nitric oxide to nitric acid by the reaction of residual or produced NOx gas and hydrogen peroxide. I'm trying to provide a way to do it.
제1도는 과산화수소와 황산의 함량, 및 주입 방법이 NOx 지연에 미치는 영향을 보이는 그래프이며,1 is a graph showing the effects of hydrogen peroxide and sulfuric acid content and the injection method on the NOx delay,
제2도는 혼산에 첨가하는 황산의 함량 변화가 NOx 지연에 미치는 영향을 보이는 그래프이다.2 is a graph showing the effect of the sulfuric acid content added to the mixed acid on the NOx delay.
본 발명에 의하면, 스테인레스강 혼산 산세액에 과산화수소를 첨가하여 질산을 재생함을 포함하는 스테인레스강 혼산 산세시 발생하는 산화질소류 배가스 제거 방법에 있어서, 과산화수소를 첨가하기에 앞서 혼산 산세조에 황산을 1%미만으로 첨가하고 상기 황산이 첨가된 산세액으로 스테인레스강을 산세함으로써 산세에 의해 생성된 NOx가스를 제거하는 단계; 및 이어서 산세조에 연결된 혼산순환탱크내에서 측정한 NOx 생성량 혹은 산세량과 비례하여 H2O2를 혼산순환탱크내에 연속 첨가하여 황산이 소모된 다음에 잔류 혹은 생성된 NOx와 과산화수소를 반응시켜 질산으로 재생하는 단계;로 이루어짐을 특징으로 하는 황산 및 과산화수소를 이용한 스테인레스강 혼산 산세시 발생하는 산화질소류 배가스 제거방법이 제공된다.According to the present invention, in the method for removing nitric oxide exhaust gas generated during stainless steel mixed acid pickling, which comprises adding hydrogen peroxide to the stainless steel mixed acid pickling solution to regenerate nitric acid, sulfuric acid is added to the mixed acid pickling tank before adding hydrogen peroxide. Removing NOx gas generated by pickling by adding less than% and pickling stainless steel with the pickling solution containing sulfuric acid; Then, H 2 O 2 is continuously added to the mixed acid circulation tank in proportion to the amount of NOx produced or pickled in the mixed acid circulation tank connected to the pickling tank, and sulfuric acid is consumed, and then the remaining or generated NOx reacts with hydrogen peroxide. There is provided a method for removing nitrogen oxide exhaust gas generated during stainless steel mixed acid pickling using sulfuric acid and hydrogen peroxide.
이하, 본 발명에 대하여 상세히 설명한다.EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.
본 발명에서는 황산을 산세성과 표면 품질에 영향을 주지 않는 범위내에서 소량 첨가함으로써 산세 초기에 생성된 NOx가스를 제거하고, 혼산 순환 탱크에서 과산화수소를 첨가함으로써 황산의 효능이 감소한 다음 잔류하거나 혹은 새로 생성된 NOx가 과산화수소와 반응하여 질산으로 완전히 재생되도록 하는 것이다.In the present invention, by adding a small amount of sulfuric acid within a range that does not affect pickling properties and surface quality, the NOx gas generated at the beginning of the pickling is removed, and hydrogen peroxide is added to the mixed acid circulation tank to reduce the efficacy of sulfuric acid and then remain or generate new NOx reacts with hydrogen peroxide to completely regenerate with nitric acid.
스테인레스강 산세시 발생된 NOx는 황산이 존재하는 경우 황산 및 스테인레스강내의 철 이온과 황산이온과의 반응으로 생성된 황산철과 1차적으로 반응하여 H2SO4ㆍNO, NOHSO4, Fe(NO)SO4를 생성함으로써 산세 직후 급격히 생성된 NOx를 처리하게 된다. 이를 도식화하면 다음과 같다.NOx generated during stainless steel pickling reacts with iron sulfate produced by the reaction between sulfuric acid and iron ions in sulfuric acid and stainless steel when sulfuric acid is present. H 2 SO 4 ㆍ NO, NOHSO 4 , Fe (NO By generating SO 4 , the NOx produced is treated immediately after pickling. Schematic of this is as follows.
상기 반응생성물들은 산세액내에 침전물로 존재하게 되며 후처리공정을 거쳐 슬러지로 배출된다.The reaction products are present as precipitates in the pickling solution and discharged to the sludge after the work-up process.
여기서 스테인레스강 혼산 산세액의 조성은 이에 한정하는 것은 아니나, 질산 22중량% 및 불산 4중량%가 혼합된 혼산이 사용된다. 본 발명에서는 상기 일반적으로 사용되는 산세액에 황산을 1% 미만으로 첨가하게 된다. 상기 황산이 1% 이상 첨가되면 과량의 첨가제로 인해 혼산에서의 산세성 및 표면조도, 광택도 등의 표면물성이 열화하게 되므로 바람직하지 않다.The composition of the stainless steel mixed acid pickling solution is not limited thereto, but a mixed acid of 22% by weight of nitric acid and 4% by weight of hydrofluoric acid is used. In the present invention, sulfuric acid is added to less than 1% to the generally used pickling solution. When 1% or more of sulfuric acid is added, it is not preferable because excessive physical additives deteriorate surface properties such as pickling properties, surface roughness, glossiness, and the like in mixed acids.
처리하고자 하는 스테인레스 강판이 장착될 수 있고 혼산 순환 탱크로 부터 시편 표면에 황산 1% 미만이 첨가된 혼산 산세액이 일정 유량으로 흘러갈 수 있도록 설치한 산세 반응조를 이용하여 50-70℃의 혼산 산세 반응온도에서 산세한다.Mixed acid pickling at 50-70 ° C using a pickling reactor equipped with a stainless steel plate to be treated and installed to allow a mixed acid pickling solution containing less than 1% sulfuric acid to flow at a constant flow rate from the mixed acid circulation tank. Pickling at the reaction temperature.
상기한 바와 같이, 산세시 혼산에 첨가된 황산에 의하여 초기 생성된 NOx가스를 제거하는 동안 산세조를 통과한 산세액에 과산화수소를 산세량(단위시간당 산세표면적) 혹은 NOx 생성량에 비례하여 연속 첨가함으로써 황산의 효능이 감소한 다음 잔류하거나 혹은 새로 생성된 NOx를 질산으로서 재생한다.As described above, by removing hydrogen peroxide continuously in proportion to the pickling amount (pickling surface area per unit time) or the NOx production amount, the pickling liquid passed through the pickling tank while removing the NOx gas initially generated by the sulfuric acid added to the mixed acid during pickling. The effectiveness of sulfuric acid is reduced and the remaining or newly generated NOx is regenerated as nitric acid.
본 발명의 방법에 의하면, 황산을 이용하여 초기 급격히 생성된 NOx가스를 제거한 다음 황산 소모후 잔류하거나 혹은 생성된 NOx는 과산화수소와 반응시킴으로써 질산을 최대 효율로 재생할 수 있다.According to the method of the present invention, nitric acid can be regenerated at maximum efficiency by removing the NO x gas which is rapidly generated using sulfuric acid and then remaining after sulfuric acid consumption by reacting with hydrogen peroxide.
이하, 실시예를 통하여 본 발명을 상세히 설명한다.Hereinafter, the present invention will be described in detail through examples.
[실시예 1]Example 1
과산화수소 및 황산의 함량, 및 주입 방법에 따른 NOx 제거효과NOx removal effect by hydrogen peroxide and sulfuric acid content and injection method
본 실시예는 과산화수소 및 황산의 주입 방법에 따른 NOx 제거 효과를 보기 위한 것으로, 본 발명의 방법에 의하여 황산을 첨가한 다음 과산화수소를 혼산 순환탱크에 연속첨가한 실시예 (가), 변형된 종래 방법으로 황산없이 과산화수소만을 산세 후 연속첨가한 비교예 (나) 및 종래의 방법에 따라 과산화수소를 일시에 산세조에 투입한 종래예 (다)의 3가지 경우에 대하여 NOx 제거율을 측정하고 그 결과를 도 1에 나타내었다.This embodiment is to see the NOx removal effect according to the injection method of hydrogen peroxide and sulfuric acid, the embodiment of adding sulfuric acid by the method of the present invention and then continuously added hydrogen peroxide to the mixed acid circulation tank (A), modified conventional method The NOx removal rate was measured for three cases of Comparative Example (b) in which only hydrogen peroxide without sulfuric acid was added and then continuously added, and conventional Example (c) in which hydrogen peroxide was added to the pickling bath at a time according to the conventional method. Shown in
우선, 산세하기 위하여 105mm×170mm의 스테인레스 시편을 산세 반응조에 장착하고 40ℓ의 혼산 순환탱크로부터 산세액이 시편 표면에 일정 유량으로 흘러가도록 하였다. 산세도중 발생하는 NOx는 NOx 측정기를 통해 1분 간격으로 210분간 측정하고 그 값을 컴퓨터에 자동입력되도록 하였다. 여기서 상기 NOx측정기는 오존을 이용하여 NO2를 산화한 다음 NO2센서를 이용하는 것으로, 측정되는 NOx 제거율은 ppm단위로 표기하였다.First, in order to pickle, a 105 mm x 170 mm stainless steel specimen was mounted in a pickling reactor and the pickling liquid flowed from the 40 liter mixed acid circulation tank at a constant flow rate on the surface of the specimen. NOx generated during pickling was measured for 210 minutes at intervals of 1 minute using a NOx meter and the value was automatically entered into the computer. Here, the NOx meter oxidizes NO 2 using ozone and then uses a NO 2 sensor, and the measured NOx removal rate is expressed in ppm.
실시예 (가)의 방법에 따르면, 질산 22%와 불산 4%를 혼합한 스테인레스강 혼산 산세액에 산세전에 0.5% 황산을 첨가하고 NOx가스를 제거한 다음 황산에 의한 NOx가스 제거 효능이 남아 있는 동안에 혼산 순환 탱크에 과산화수소를 1.6㎖/min으로 77분간 연속하여 첨가하고 NOx를 제거하였다.According to the method of Example (A), 0.5% sulfuric acid was added to the stainless steel mixed acid pickling solution mixed with 22% nitric acid and 4% hydrofluoric acid before the pickling, and the NOx gas was removed and the NOx gas removal effect by the sulfuric acid remained. Hydrogen peroxide was continuously added to the mixed acid circulation tank at 1.6 ml / min for 77 minutes and NOx was removed.
그 결과, 과산화수소를 중단한 다음에는 약 17,000㎎/㎥의 NOx가 측정되었으나, 과산화수소를 첨가하는 동안은 거의 완벽하게 NOx 가스를 제거함을 확인할 수 있었다(도 1 참조).As a result, after stopping hydrogen peroxide, NOx of about 17,000 mg / m 3 was measured, but it was confirmed that NOx gas was almost completely removed during the addition of hydrogen peroxide (see FIG. 1).
실시예 (나)는 산세전에 황산을 첨가하지 않은 비교예이다. 도 1에서 알 수 있듯이 여기서도 또한 과산화수소를 중단한 다음 발생한 NOx는 약 17,000㎎/㎥이었으나 산세 초반에 약 3,500㎎/㎥의 NOx가 발생하게 됨으로, 실시예 (가)에 비하여 초기 급격하게 생성된 NOx가스를 처리하지 못하였다.Example (B) is a comparative example in which sulfuric acid was not added before pickling. As can be seen in FIG. 1, the NOx generated after stopping hydrogen peroxide was about 17,000 mg / m 3, but about 3,500 mg / m 3 of NO x was generated in the early stage of pickling, thus rapidly producing NO x as compared with Example (a). The gas could not be processed.
실시예 (다)는 종래 방법에 의한 비교예로서, 과산화수소(1.6㎖/분×77분=123㎖)를 산세전에 일시에 첨가하고 황산은 전혀 첨가하지 않았다.Example (C) is a comparative example according to the conventional method, in which hydrogen peroxide (1.6 ml / min x 77 minutes = 123 ml) was added at a time before pickling and no sulfuric acid was added.
그 결과, 도 1에서 알 수 있듯이 과산화수소 첨가를 중단한 다음 발생된 NOx량은 약 17,000㎎/㎥이었으며, 초기 약30분 정도는 NOx 생성을 완벽하게 지연하는 듯하였으나 그이후에 NOx가 급격하게 발생됨을 확인할 수 있었다.As a result, as shown in FIG. 1, the amount of NOx generated after stopping the addition of hydrogen peroxide was about 17,000 mg / m3, and initially about 30 minutes seemed to completely delay the generation of NOx, but NOx was rapidly generated thereafter. Could confirm.
따라서 본 발명의 방법에 의하면 황산을 산세액에 첨가함으로써 과산화수소가 NOx와 반응을 개시하기 전까지 생성된 NOx가스를 일차적으로 충분히 처리할 수 있음을 확인할 수 있으며, 나아가 과산화수소는 NOx 생성량과 비례하여 연속적으로 첨가하는 것이 효율적임을 또한 확인할 수 있었다.Therefore, according to the method of the present invention, it can be confirmed that by adding sulfuric acid to the pickling solution, it is possible to sufficiently process the generated NOx gas until the hydrogen peroxide starts to react with the NOx, and furthermore, the hydrogen peroxide is continuously in proportion to the NOx production amount. It was also confirmed that the addition was efficient.
[실시예 2]Example 2
혼산에 첨가하는 황산의 함량 변화에 따른 NOx 제거효과NOx according to the content of sulfuric acid added to mixed acid Removal effect
본 실시예는 혼산 산세액에 첨가할 황산의 적정량을 결정하기 위한 시험으로, 혼산 산세액에 황산을 0%, 0.5% 및 1.0%를 각각 첨가한 것을 제외하고는 실시예 1의 (가)와 동일한 방법을 반복하였다. 실시예 1과 마찬가지로 NOx 제거량을 측정하였으며 그 결과를 도 2에 나타내었다.This example is a test for determining the appropriate amount of sulfuric acid to be added to the mixed acid pickling solution, except that 0%, 0.5% and 1.0% of sulfuric acid is added to the mixed acid pickling solution, respectively. The same method was repeated. As in Example 1, the amount of NOx removal was measured and the results are shown in FIG. 2.
그 결과, 황산을 첨가하지 않은 실시예 (가)의 경우 NOx 생성량을 2,000㎎/㎥까지 지연하는데 걸리는 시간은 30초였으며, 황산을 0.5% 첨가한 실시예 (나)의 경우 지연 시간은 2-3분이었고, 황산을 1.0% 첨가한 실시예 (다)의 경우 지연 시간은 5분 정도인 것을 관찰하였다.As a result, in Example (a) without adding sulfuric acid, the time taken to delay NOx production amount to 2,000 mg / m 3 was 30 seconds, and in Example (b) with 0.5% sulfuric acid, the delay time was 2- It was 3 minutes, and in Example (C) to which 1.0% of sulfuric acid was added, the delay time was observed to be about 5 minutes.
상기 시험 결과로부터 황산 첨가량이 많을수록 초기 NOx 생성이 지연되는 효과는 비례함을 알 수 있다. 그러나 황산 첨가제가 너무 과량이면 산세성 및 표면물성이 열화되는 점을 감안하여, 황산 첨가량은 1%를 기준으로 하는 것이 가장 바람직한 것으로 여겨진다.From the test results, it can be seen that as the amount of sulfuric acid is added, the effect of delaying the initial NOx production is proportional. However, in view of the fact that too much sulfuric acid additives deteriorate pickling properties and surface properties, it is considered that the amount of sulfuric acid added is most preferably based on 1%.
본 발명의 방법에 의하면, 황산으로 하여금 산세 초기에 생성된 NOx가스를 제거하게 하고 그런다음 과산화수소를 연속 첨가함으로써 황산에 의한 NOx가스 제거 효능이 감소한 다음 잔류 내지는 생성된 NOx와 과산화수소를 반응시켜 혼산 산세시 발생하는 NOx 가스를 질산으로 최대 효율로 재생시킬 수 있다.According to the method of the present invention, sulfuric acid is removed to remove NOx gas generated at the beginning of pickling, and then hydrogen peroxide is continuously added to reduce NOx gas removal efficiency by sulfuric acid, followed by reacting residual or generated NOx with hydrogen peroxide to cause acid pickling. NOx gas generated at the time can be regenerated with nitrate at maximum efficiency.
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