The chlorination process titanium dioxide process is not developed in China. It is only a technical problem.
Titanium dioxide is currently the best white pigment and is widely used in coatings, rubber, plastics, paper, printing inks and other fields. It is produced in two processes, sulfuric acid and chlorination. The chlorination method titanium dioxide production process is an internationally recognized new generation of advanced technology to replace the sulfuric acid method because of its environmental protection and high product quality in the production process.
Two preparation methods
At present, the global production ratio of chlorinated titanium dioxide to sulfuric acid titanium dioxide is about 6:4. In developed countries in Europe and America, the proportion of chlorination is higher. However, at present, only a few titanium dioxide enterprises in China use the chlorination method. Why is the domestic titanium dioxide industry not developing?
Internationally recognized excellent craftsmanship, national memory dispute
It is understood that although there is a conclusion in the international arena, in the Chinese industry, whether the sulfuric acid method is good or the chlorination method is good, but there has been a lot of controversy.
One viewpoint is to advocate the development of the chlorination method to eliminate the sulfuric acid method. Relevant professionals pointed out that China's titanium dioxide industry must take the road of chlorination, and then have the strength to cope with the severe challenges of the international market. The reason is very simple. The main raw materials of the sulfuric acid process are sulfuric acid and titanium concentrate, etc. The products produced are of low quality, single species and serious environmental pollution. On the contrary, the main raw materials of the chlorination method are high-titanium slag and chlorine gas, which are called cleaning processes, and have many advantages such as high production automation, high product quality, large scale, and low emissions of “three wastes”.
The other side believes that the chlorination process is not completely substitutable for the sulfuric acid process. At present, European and American countries still maintain strong demand for the anatase titanium dioxide produced by the sulfuric acid process in the papermaking, chemical fiber, ceramics, cosmetics and other industries. The sulfuric acid method titanium dioxide still has a wide range of application methods and market demand in the future, and will be titanium chloride. White powder coexists for a long time.
At the same time, the domestic sulfuric acid law will not fall behind. Because domestic companies have worked hard to create an improved sulfuric acid process. This technology has been greatly improved than the original sulfuric acid method. For example, acid-soluble titanium slag is used instead of titanium concentrate as raw material, waste acid concentration and recycling, sulfur acid waste heat utilization, etc., and the production level has been greatly improved.
Some insiders also said that in terms of environmental protection, it is a misunderstanding to simply say that sulfuric acid pollution is serious. The main pollution of sulfuric acid titanium dioxide is waste sulfuric acid, but with the promotion of waste acid recovery technology, the amount of waste sulfur can be greatly reduced. For example, Sichuan Longjing Company, its waste acid is used for the production of phosphate. However, the chlorination slag produced by the chlorination method is difficult to handle. At present, many foreign enterprises transport chlorinated waste slag to the deep sea in the high seas, or are buried in the sparsely populated abandoned mines, which is more harmful to the environment; in terms of raw materials, the current domestic titanium Although there are many resource rocks, there are few high-quality sand mines.
To adapt to the chlorination process, it is also necessary to refine the titanium concentrate into high titanium slag. In this way, the production process of the chlorination process is not short and the cost is not necessarily low. In a joint EU study, the sulfuric acid law has different hidden dangers to the environment, and it is not who is more environmentally friendly. Chlorination can save energy and reduce wastewater discharge, but its waste is more toxic than waste from sulfuric acid.
In fact, in the type of titanium dioxide products, the modified sulfuric acid method also has advantages. The modified sulfuric acid process can produce both high-end rutile titanium dioxide and low-end titanium dioxide, while chlorination can only produce rutile titanium dioxide. Although it can also be converted to anatase type, an additional process is required during the conversion process, which adds additional cost.
Although it is a development trend, key technologies are difficult to master
After years of technical exploration and research, the production process has been solved one by one. Jinzhou Titanium finally succeeded in developing China's first set of 10,000-ton chlorinated titanium dioxide core device - oxidation sensor in 2001, solving the key technical problems. After 20 years of hard work, the installation, production and continuous operation of the device were gradually realized.
At present, the domestic chlorination method is still insufficient compared with the advanced level in foreign countries. First, the domestic oxidation reactor operating cycle is only more than 3 weeks, but compared with the foreign oxidation reactor for up to six or seven cycles, there is still a certain gap. Second, the product quality has a certain gap with foreign countries, mainly reflected in the particle size and crystal form control of titanium dioxide. It exhibits whiteness, achromatic power, and hiding power. There are gaps in indicators such as weather resistance. Third, in the manufacture of key equipment, the quality of domestic manufacturing is still not comparable to imported equipment. Fourth, there is still a gap between the production capacity of single equipment and foreign countries.
In addition, there is a big difference between the chlorination method and the sulfuric acid process. The former has very high requirements on production technology and equipment materials, and most domestic enterprises do not reach this level of technology. At the same time, we do not have our own core. Technology, key technologies are difficult to introduce. This is also an important reason why the chlorination method has not been promoted in China.