Development of steel drum environmental protection technology

Development of steel drum environmental protection technology

Yang Wenliang

Since the 1990s, environment and development have become a focus of attention in today's society. With the development of the economy and the improvement of people's living standards, the call for environmental protection has spread throughout the world. Packaging, an industry related to human life, has also been increasingly affected, and the pollution caused by packaging has become more and more concerned. The world packaging industry has spent countless efforts to reduce environmental pollution. However, the packaging industry, like all other industrial sectors, has not completely solved the problem of environmental pollution. On the contrary, the packaging industry is also facing its own unique environment. pollution problem.

In recent years, the steel drum industry has made great progress as a major branch of the packaging industry, but at the same time there are serious environmental pollution problems. It exists not only in the steel drum itself, but also in the production process and use of the steel drum. Therefore, the development of steel drum environmental protection technology and reducing environmental pollution will be a major direction for the development of steel drum packaging in China.

First, the environmental protection of steel drum products is the main direction of technology development

1. Quality and environmental protection of steel drums

The most serious quality problem of steel drums is leakage, which has attracted the attention and research of many barrel experts, but it has not yet been completely solved. Steel drums contain a wide variety of contents, including food, petroleum products, chemical raw materials, medicines, etc., and some are highly toxic; some are easily reacted with the outside world to cause corrosion or pollution; some are flammable and easy Explosion... For many years, due to the leakage of steel drums, I did not know how many accidents occurred, causing more serious environmental pollution. Therefore, it is imperative to develop steel drum environmental protection technology and solve the problem of steel drum leakage.

The leakage of the steel drum is mainly caused by the quality of the barrel weld of the steel drum and the sealing of the top of the barrel. In order to solve this problem, China's steel drum structure has been improved from the original five-layer rectangular crimping to seven-layer circular curling, and some have also improved the welding machine from manual semi-automatic to fully automatic, thus improving the quality of the steel drum and reducing it. The leak, and the full pressure test of the product greatly eliminated the leakage of the steel barrel. However, due to the quality of raw materials and the backwardness and instability of the equipment, as well as the limitations of the process methods, it is still difficult to prevent the leakage of steel drums, especially in the case of collision or falling in use, the quality accidents occur more.

At present, in some European countries, in order to prevent the leakage of steel drums, all the joints of steel drums are produced by new technologies such as laser welding. The steel drums produced by the new technology have lower drop strength and leakage resistance than the original process. More than doubled, this will be the development direction of steel drum technology towards environmental protection.

2. Steel drum structure and environmental protection

As far as environmental protection is concerned, there are still many shortcomings in China's steel drum structure. Although the national standards have been revised again, there is no innovation in structure, and it still needs to be improved and improved.

The closed steel drum structure specified in GB 325-91 "Packaging Container Steel Barrel" generally has the problem of residual residue in the user's use. The contents of the steel drum are not clean, which not only causes a lot of waste, but also causes environmental pollution. Because some of the residue may be contaminated by the environment when the steel drum with the residue left behind is discarded. If the steel drum can be reused, cleaning the steel drum will result in greater pollution. Steel drums with residues left will also cause trouble for recycling. In recent years, there have been several steel drum structures in the world that do not leave any residue, such as arched bucket tops or grooved drainage structures. The steel drum structure without leaving any residue is the only way for the closed steel drum to go to environmental protection packaging.

3. Steel drum coating materials and environmental protection

For many years, the coatings of steel drums in China have not been much developed. They have only been improved from the coating process. Although they have also reduced the way of environmental pollution, the pollution caused by the coating process is still steel drums. A major drawback in production. In order to eliminate the pollution caused by coatings, many new environmentally friendly coatings have appeared in China and abroad in recent years. The use and popularization of these new coatings will make steel drum production technology a big step towards environmental protection.

Pre-coating is a major change in coatings. It shifts the steel drum from the final finished coating to the coating of raw materials, thus reducing the contamination of the coating process.

Waterborne coatings are a new type of self-priming coating developed after anodic and anodic electrophoretic coatings. It is characterized by water as a dispersion system, does not contain any organic solvents, complies with international management regulations, and is conducive to environmental protection.

Adhesive coating is a kind of polymer film coated with color coating and binder. Due to its good durability and weather resistance, it can be easily attached to the outer surface of the barrel. Because it replaces solvent-based liquid coatings, it is a revolutionary new coating for environmental protection.

For the first time, powder coatings have achieved solvent-free dry coating production, which fundamentally eliminates the scattering of harmful solvents, and the overspray powder can be recycled. Not only the coating quality is good, the efficiency is high, but more importantly, it reduces and eliminates environmental pollution, improves working conditions and saves energy. It is a new trend in the development of steel drum coating.

Second, the process of steel barrel production is not conducive to environmental protection is gradually reduced

Due to the limitations of equipment and technology, there are still a large number of processes that are not conducive to environmental protection in the production process of most barrel factories in China. Some are still not recognized by people; some are also promoted as advanced technology; others have set up corresponding environmental protection facilities, but they have long been lost. This situation is gradually improving with the improvement of national environmental awareness and technological progress.

1. Development of processing technology for barrel weld edge

The welding process of the barrel body is to pre-treat the seam of the barrel body before the seam welding, and the purpose is mainly to eliminate oxides and oil stains on the edge to facilitate seam welding. At present, the main domestic process is edging, that is, the grinding edge is ground by 4~8 sets of grinders, and the barrel industry is called edging process.

People who see the edging production with their own eyes will be shocked because the working environment here is too bad, there are deafening noises, there are dusty dust, smog and smog... The noise comes from the friction between the grinding wheel and the steel plate; the dust It is the particle under the grinding of the grinding wheel and the steel plate; part of the flue gas is the product of the high temperature of the binder in the grinding wheel, and part of the result is the vaporization of the oil stain on the surface of the steel plate at high temperature. In such a working environment, environmental protection departments often ask for rectification as soon as possible.

In recent years, a variety of new welding edge treatment processes have emerged in China, which proves that people still recognize the impact of edging on the environment. These processes include milling edge technology, cleaning process, flexible wheel grinding process, and fully automatic high frequency welding process. Both the milling process and the cleaning process eliminate noise and dust, but the cleaning process uses corrosion of oxides and oil on the weld edge, such as hydrochloric acid, often accompanied by toxic and harmful gases, and there is cleaning waste, or Environmental protection is unfavorable, so it cannot be promoted. Only the automatic high-frequency welding process is characterized by the advanced nature of the welding machine. The welding edge can be welded without strict treatment, and the treatment process is removed, thereby reducing the labor intensity, reducing the production cost and improving the environmental pollution.

2. Development of steel drum coating production technology

Steel drum coating production is one of the most harmful to the environment in the production process of steel drums. The large amount of waste gas, waste water and waste residue produced by steel drum coating are mainly from the three wastes produced by chemical treatment methods such as degreasing, descaling, phosphating and passivation before painting; organic solvents and paint mist during the coating process. Three wastes generated by scattering, solvent evaporation during drying of the paint.

If the three wastes in the painting process are not effectively and properly managed, the harm to the environmental pollution and the operator is serious, and it is not allowed by the National Environmental Protection Law. Various effective measures are taken to comply with the relevant national environmental protection. The provisions of the law, comprehensive management, the environmental pollution of the three wastes and the harm to human health, to a minimum or to eliminate. However, in the past, the treatment of the three wastes in China was a remedial type, which made the environmental protection work fall into the vicious circle of pollution after the first pollution. Therefore, the use of pollution-free or low-pollution production technology is the real way out.

At present, the environmental protection coating technology at home and abroad has developed rapidly. Nowadays, various coating methods for mechanized and automated assembly lines with advanced coating technology such as high pressure airless spraying, electrophoretic spraying, electrostatic spraying and powder coating have been widely used. Production of new patterns. In these modern advanced coating methods, the latest coating technology for automatic coating and robotic operation of microcomputer program control and closed circuit television control has been introduced. The new high-protection, high-decoration, low-toxic, low-pollution coatings and thinners are matched with dip coating, spray coating, roll coating, and photocuring, radiation curing coating, etc. for semi-mechanized, mechanized and automated assembly lines. It constitutes the development of modern coating production towards new coating systems with high efficiency, high quality, low consumption, energy saving, environmental pollution reduction and improved working conditions. The extensive use of environmental protection facilities has caused the pollution caused by ordinary spraying methods to be decreasing. The new coating process is rapidly expanding its application and continuously improving its development. The coating environmental protection equipment is continuously developed and put into production. At present, China's steel drum coating technology is trying to catch up with the world's advanced level, people's environmental awareness is constantly strengthening, and the prospect of environmental protection is beautiful.

Third, the environmental protection problems in the use of steel drums are receiving increasing attention

Steel drums often cause environmental pollution due to improper use. Most of the common causes of pollution are caused by improper selection of steel drums and unreasonable storage and transportation methods.

1. Compatibility of steel drum materials

There may be compatibility issues when loading certain materials in steel drums. Common coating problems, sealant problems and seal problems are commonly seen.

The inner coating, sealant and seal should be compatible with the contents and should not react. When incompatibility problems occur, the contents are contaminated and the sealing performance of the steel drum is lost, resulting in unpredictable results. Cases in which a large amount of chemical substances that have occurred in a sea cargo ship cause serious seawater pollution are caused by compatibility problems. Therefore, both parties should clarify this issue when producing and ordering steel drum packaging products, so as not to cause irreparable consequences.

2. Environmental protection issues during storage and transportation

Leakage of steel drums in use is mostly related to uncivilized loading and unloading. Due to improper loading and unloading, the steel drum collides, falls and deforms, leaks, and causes pollution. At present, some domestic enterprises have adopted automated assembly line operations for filling, loading and unloading of steel drums, thereby reducing leakage pollution caused by artificial uncivilized loading and unloading.

The correct storage and transportation of steel drums is not allowed to place the steel drums in the open space. In particular, it is not allowed to stand the steel drums in the open space, that is, the barrel mouth is upward. The steel drum is placed in the open space. In addition to the damage to the steel drum caused by the wind, the sun and the rain, it is important that the thermal expansion and contraction affect the sealing performance of the steel drum. Also, when standing in the open air, it is easy to accumulate water in the top of the barrel and infiltrate into the barrel through the poorly sealed barrel mouth, causing the contents to be contaminated. When the content contamination cannot be used, new waste is caused.

Fourth, the recycling of used steel drums

There are generally three methods for recycling used steel drums. One is to clean the old steel drums, paint stripping, shaping, repainting and continue to use them. Second, the old barrels are used to make other products.

1. Renovation of old barrels and environmental protection

At present, the number of enterprises engaged in the renovation of old barrels is gradually increasing, and technology and equipment are also being developed. However, there are still a large amount of three wastes in the cleaning, stripping and recoating processes. Regarding the three-waste treatment technology, the domestic market is quite mature. As long as it pays attention to governance, environmental pollution can be well controlled.

The environmental protection effect of the mechanical paint stripping method is obviously superior to the chemical method; the environmental protection effect of the cleaning process after the residual waste liquid is reused is also significantly better than the direct discharge. Therefore, the advanced methods of technology and technology for the three wastes are directly related to the effect of environmental protection. This will always require us to seriously explore and study.

2. Manufacture of other products from old barrel sheets

Some enterprises have built old barrels and made other products by stamping and other methods, and some have made the sheets into smaller barrels. In this recycling process, if the waste sheet still needs to be cleaned and pulled off the knee, it should also pay attention to the treatment of the three wastes to reduce environmental pollution.