Anti-corrosion application of ethylene epoxy ethylene resin in copper smelting flue gas acid

China Paint Online News News
Zhang Nan 1, Sun Fan 1, Liu Hua 1, Dai Hua 1, Chen Hanchun 2 (1. Huachang Polymers Co., Ltd., East China University of Technology, Shanghai 200237; Zijin Copper Co., Ltd., Longyan 364204)
Summary: Epoxy vinyl ester resin has excellent corrosion resistance, widely used in the copper smelting industry. This paper introduces the process of flue gas acid production in the copper smelting industry, and analyzes the characteristics of ethylene epoxy ethylene ester resin and the application case of anti-corrosion engineering in view of the corrosive medium environment in the flue gas acid process, and aims to provide a practical reference for corrosion and protection in the copper smelting industry.key words: epoxy vinyl resin, copper smelting, corrosion prevention, acid production, application
classification number: TG172; TE98
Document Code: B
Article No.: 1005-748X (2013) 05-04490-03
China is the world's largest producer and consumer of refined copper
With the improvement of copper smelting technology in China and the increasing attention to environmental protection, the anti-corrosion requirements in copper smelting industry are becoming more and more strict. According to the process and characteristics of copper smelting, the main corrosion phenomenon occurs in flue gas acid, electrolytic refining, water treatment and other sections, according to the different corrosion environment, the main selection of stainless steel, lead, acid-resistant brick / granite, water glass, resin and other materials, including ethylene epoxy resin as a new in recent decades, excellent corrosion-resistant materials, in the copper metallurgical corrosion industry plays an important role. Especially in the purification of flue gas acid, static de-fog, exhaust desulfurization and other sections. Equipment such as flue gas pipes and acid pipes are heavily made of epoxy vinyl resin fiberglass. This paper focuses on the anti-corrosion application of ethylene epoxy ethylene resin in the flue gas acid section in the copper smelting industry.1 Ethylene Oxide Resin
Ethylene Oxide Resin is an excellent corrosion-resistant high temperature resin material developed by Shell Chemical Company in the late 1970s by East China University of Technology was the first successful research in China, and soon launched a product called MFE-2 epoxy vinyl ester resin. The main chain of ethylene epoxy ethylene resin is obtained by the open-loop esterification reaction of unsaturated carboxylic acid and epoxy resin, and the curing process is copolyzed with styrene by the double bonds at both ends of the main chain, forming a stable three-dimensional mesh structure. Molecular structure and curing process make it the following advantages: (1) molecular main chain is epoxy skeleton, with the inherent good performance of epoxy resin and glass fiber immersion and other advantages
; Curing process adjustability,
(3) adjacent cross-link double-bond to ester-based space shielding effect makes the resin has a high hydrolytic stability, with good acid resistance, alkali corrosion resistance and other properties,
(4) stable three-dimensional network structure makes the resin has a high temperature resistance.
epoxy vinyl ester resin has good formability, regenerative properties and chemical corrosion resistance, and is resistant to most acid, alkali and salt solutions at 100 degrees C. Depending on the introduction of the base group in the main chain, there are BPA, phenolic and various modified epoxy vinyl resins to achieve different performance requirements and cost control. Such as: (1) Bisphenol A type ethylene epoxy resin comprehensive performance is excellent, suitable for the production of corrosion-resistant lining, tanks, sports equipment, wind power equipment, glass and steel hull and other corrosion-resistant glass and steel products, glass scale coatings or glue, rubber clothing base body, etc.; (2) phenolic ethylene oxide resin pouring body can withstand high temperatures above 150 degrees C, widely used in power plants, smelters and other flue gas desulfurization high temperature and humidity environment; (3) by brominated flame retardant modified ring Oxygen vinyl resin oxygen index of more than 30, can be used in transportation, construction and other industries equipment components, work parts, etc. ; Mold production and overall composite bridge and other fields; (5) elastomer modified vinyl epoxy resin break elongation rate of more than 10%, high flexibility, good bonding, and it is suitable for the production of high-speed railway elastic gaskets, or as a seam material, sealing material.Epoxy vinyl ester resin processing process is widely applicable, can directly produce a variety of high-transmission resin pouring body, or with glass fiber / felt, polyester cloth and other reinforcing materials hand paste, molding, extrusion, winding, etc. to make a variety of fiberglass products or high-performance composite materials . Can also be mixed with a variety of added materials such as graphite, titanium white powder, Sb2O3, such as conductive resin, flame retardant resin and other special materials or coatings, rubber clothing, or directly mixed with quartz sand / powder, glass scales, etc. into mortar, glue and other brickwork or paving granite. Ethylene epoxy resin, as a good performance, reasonable price, a wide range of applications of excellent corrosion-resistant resin, has gradually replaced conventional resins and metal materials, has become the main anti-corrosion design material.2 Anti-corrosion applications for various sections of flue gas acid
About 80% of the earth's copper mineral composition is a Cu-Fe-S mine, which is usually extracted by fire metallurgy. Most of the released sulphides are in the form of SO2, such as so2 volume percentage of smoke emitted from OttoKunpu flash furnaces, which accounts for about 25% to 50%, and SO2, which is about 8% to 15% of the smoke from Peirce-Smith furnaces. In addition, the flue gas contains a small amount of SO3, Cl2, F2 and other gases and dust. In the past, SO2 flue gas is generally discharged directly into the atmosphere, now with the state's attention to environmental protection, this practice has been strictly prohibited, fire and copper must catch sulphides, recovered sulphides are generally made into sulfuric acid. Figure 1 is the process of using SO2 acids in the exhaust gas. Among them, purification, static de-fog, exhaust desulfurization and other sections of a large number of epoxy vinyl resin to make fiberglass equipment.
1 Process for the production of sulphuric acid from flue gas from a smelting furnace or refining furnace
2. 1 Purification work section
smelting of flue gas after static dust removal, mainly SO2 and a small amount of Cl2, F2, SO3 and other gases and dust, the temperature is about 300 degrees C, the first to enter the washing tower (flow tower or Wenshi tube) is cooled by water to 55 to 60 degrees C.early washing tower design mostly using alloy steel or lead structure, but high cost, high quality, not easy to produce, corrosion resistance is not ideal, short service life. Now the washing tower, cooling tower and supporting slant sink, upper liquid storage tank, accident high groove, etc. have all been made of fiberglass, the main body of the tower is positive round, more use of medium-base fiberglass yarn immersion epoxy vinyl resin winding preparation, sometimes resin will add glass microbeads or other fillers to increase the rigidity of products or other special properties. At present, glass and steel manufacturers use winding machine to produce round towers or cans and other fiberglass products, high production efficiency, product quality and stability, accurate size. Compared to the same quality requirements of metal products, can reduce the quality of 40% to 60%, and for larger equipment, cutting and on-site bonding assembly can be used to simplify transport requirements, with better technical and economic results. Shown in Figure 2 are a first-stage washing tower, a cooling tower and a secondary washing tower for a 200kt.a-1 copper project.
2 A first-stage washing tower cooling tower and a second-stage washing tower for a 200kt.a-1 copper project２． 2 Electrostitive de-fog
the cooled and washed gas needs to pass through the electrostitive de-fog remover to remove the mist droplets that remain in the gas after being cooled by water. After the gas enters the parallel hundreds of anode tubes in the de-fog remover, the acid mist particles in the gas absorb the charge and make directional motion under the force of the electric field, reaching the anode plate where the acid mist is collected. After that, the charged particles release electrons on the polar plate, the acid mist is gathered, and under the action of gravity flows into the acid reservoir of the acid de-acid mist, which achieves the goal of purifying the acid mist.the main composition of the gas into the de-fogr is about 8% to 12% SO2, 8% to 10% H2S, and 5% to 10% acid fog, the temperature remains at about 40 degrees C. Because the electric de mist remover has been in an acidic atmosphere for a long time, it must be made from materials with good corrosion resistance. Cathode wire are made of metal, anode plate commonly used materials are lead, hard PVC (PVC) and conductive glass and steel three types. However, PVC products easy to age cracking, short service life, lead products have a large weight, variability, maintenance difficulties, pollution environment and high cost shortcomings, and by vinyl epoxy resin and graphite made of conductive glass and steel products completely overcome the above shortcomings. Such as the Guixi smelter's 1307-5 square tube vertical electric de mist remover, the use of MFE-3 epoxy vinyl ester resin to make conductive glass steel, when the voltage rises to 72kV, the current can reach the rated current 400mA, de-fog efficiency of more than 99%, running 16a glass steel components still maintain a good appearance. As shown in Figure 3, the internal structure of an electro-mist remover for a 200kt.a-1 copper project, the anode plate is made of MFE-7 flame retardant vinyl epoxy vinyl resin to conductive glass steel, and the oxygen index (OI value) is greater than 30.
3 The internal structure of an electric desolator for a 200kt.a-1 copper project２． 3 Exhaust desulfurization
After electro-fogging, the flue gas is dehydrated with 93% H2SO4 plus 7% H2O (sometimes 96% to 98% of the thick sulphuric acid) in the drying tower, heated to 410 degrees C and O 2 Catalytic oxidation into SO3 in the conversion tower, cooling to 200 degrees C after SO3 in the absorption tower by 98% H2SO4 plus 2% H2O absorption and production of sulfuric acid, the trans-chemical segment mainly uses water glass building acid-resistant brick for protection treatment. Residual exhaust gas according to sulfur content to choose to discharge into the atmosphere or further desulfurization, flue gas desulfurization process is mainly: limestone -gypsum wet desulfurization, seawater desulfurization, etc. , of which limestone-gypsum wet desulfurization method is widely used, active coke desulfurization technology in environmental protection and resource reuse representative.(1) Limestone-Gypsum Desulfurization
Limestone-Gypsum Desulfurization technology is mature and reliable, widely applicable, high desulfurization efficiency, is currently the most widely used in the copper refining industry desulfurization method. Its main process is: flue gas after cooling by the heat exchanger, into the absorption tower and limestone emulsion full contact, smoke SO2 in O2 and H2O participation in the reaction to produce CasSO4.2H2O, the remaining gas after the defog heating into the chimney.the main body of the absorption tower is a carbon steel structure, lined with a certain thickness of epoxy vinyl ester resin glass scale film, which is quite beneficial to corrosion prevention. At present, ethylene epoxy ethylene resin glass scale film has gradually replaced other materials, a large number of applications in desulfurization and corrosion prevention.(2) Active coking flue gas desulfurization technology This technology is a resource-based dry flue gas desulfurization technology, coal-based active coke as an adsorbent, adsorption of SO2 in the removal of flue gas. The active coke after adsorption so2 can be heated and dissoated to obtain a high concentration of SO2 mixture gas. The active coking flue gas desulfurization process has the following advantages compared with the limestone-gypsum wet flue gas desulfurization process: (1) desulfurization can be accompanied by desulfurization and removal of harmful heavy metals;so the active coke desulfurization technology is in line with the direction of industrial development.
flue gas first into the humidification tower, humidification tower for the fiberglass tank structure, containing Bauer ring filler, flue gas in the filler after the filling by high temperature water vapor humidification heating into the adsorption tower, adsorption tower for carbon steel structure, lower air inlet phenolic phenolic ethylene resin glass scale film. Central for the active coking layer, active coking is coal as raw material, molding, coking, activated production of porous black particles, flue gas in the active coking layer to complete SO2, HF, HCl and dioxin and other large molecular oxides, as well as mercury, arsenic and other heavy metals adsorption, and then from the side flue discharge to the chimney. Saturated active coke is transported to the analytical tower for heating de-attachment, resulting in a SO2 mixture with a volume concentration greater than 20% and sent to the acid production.２． 4 Chimney exhaust and pipe corrosion prevention
after purification of the flue gas will still have residual sulphides, when the flue gas contains moisture, or air humidity is high, sulphides will still combine water into acid. The flue gas temperature is between 40 and 80 degrees C, the acid is very corrosive to the structural material, and the chimney lining ethylene epoxy resin glass scale film is the final corrosion protection.the whole process of acid production, most of the flue gas in the pipeline is flowing at less than 80 degrees C, the pipe is also made of fiberglass. Some acid pipes use PVC-lined fiberglass-reinforced composite pipes.
3 concluding
the performance and quality of domestic excellent vinyl epoxy resin has reached or even surpassed similar products abroad. Flue gas acid has been a large number of ethylene epoxy resin as an anti-corrosion material with the product in-depth research and development and improvement, continuous improvement of the production process, more epoxy vinyl resin products have been introduced, ethylene epoxy ethylene in the copper smelting industry will have a broader application market.:
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