In recent years, with the rapid development of coatings industry and plastics industry, the demand of titanium dioxide industry has increased year by year, and the development of titanium dioxide industry in China has entered a critical period. Driven by both supply and demand, the price of titanium dioxide products has maintained an upward trend since the second half of 2015. Industry profits are considerable, it ushered in a new cycle of prosperity. According to statistics, the output of titanium dioxide in China reached 2.96 million tons in 2018.
In the process of rapid development of titanium dioxide industry, lack of protection of ecological environment and lack of government supervision make titanium dioxide industry restricted by our government as "restricted" and "double high" products. Therefore, environmental protection and comprehensive utilization of three wastes have gradually become the key issues of titanium dioxide industry in recent years.
Membranes, in a broad sense, are materials with selective separation functions.
Membrane technology appeared at the beginning of last century, and the application of membrane technology in China was relatively late. It was not until the 1980s that it formally entered the stage of application. However, with the rapid development of membrane technology in China, a variety of membrane products and membrane technology applications have been continuously developed and applied in various industries, including pharmaceutical and food, water treatment, petrochemical, environmental engineering and other fields. With the continuous improvement of people's quality of life and the enhancement of environmental awareness, membrane plays an important role in all walks of life and is an irreplaceable technology in the new century.
Membrane Technology and Titanium Dioxide
Titanium dioxide process is divided into sulfuric acid process and chlorination process. In China, sulfuric acid process is the main method, accounting for 95% of the total production capacity.
In the process of sulfuric acid production, there are three washing processes, which will produce multi-strand waste acid wastewater. In the traditional process of treating waste acid wastewater, Sean filter, plate-frame filter press, pipe filter or inclined plate sedimentation are often used. These processes have common characteristics: 1. The waste acid wastewater still contains a lot of titanium dioxide which can not be recovered, resulting in serious loss of titanium dioxide; 2. The waste acid contains a large number of heavy metal ions such as Fe2+, Ca2+, Mg2+. It prevents the waste acid from being reused directly so that it can only be neutralized. The wastewater after neutralization of waste acid has high salinity and large amount of water, accompanied by the production of a large number of waste gypsum, and the cost of solid waste treatment is too high. 3. Traditional equipment covers a large area and needs a lot of manual operation. During the production of chlorination process, chlorinated tailings will be produced, which contains a large amount of chloride and heavy metals, and it will cause serious environmental pollution by direct discharge.
Jiangsu Jiuwu Hi-tech Co., LTD successfully developed a variety of combined membrane processes to solve the problem of difficult treatment of waste acid wastewater and chlorinated tailings. Compared with traditional process, membrane process has many advantages:
1. Membrane equipment covers a small area and can be fully automated, and it is easy to operate and easy to maintain.
2. The effluent water quality is high, SS is less than 1 ppm, and all titanium dioxide is recovered. The annual recovery value of 100,000 tons of titanium dioxide plant is more than 4 million yuan.
3. Waste acid is completely purified. By-product sulfuric acid can be neutralized and high-quality gypsum can be produced, which has a certain market value. It can save 150 yuan by converting solid waste discharge into valuable products.
4. The chlorinated tailings are treated by membrane process as raw materials for cement production, and the salt in the tailings can be purified as caustic soda raw materials. It can not only recycle and utilize the tailings to avoid environmental pollution, but also turn waste into conservation, forming a recycling environmental protection and energy-saving industrial chain.
Titanium dioxide industry is a pillar industry of the country. It will continue to grow in the future. Production capacity and product quality will continue to be improved. But it is also accompanied by the continuous strengthening of environmental protection policies. Therefore, membrane technology will be more widely used in the industry and it will play an important role in the development of new technologies and products.