Employing semiconductor powders as photocatalysis for the degradation of organic pollutants in water has received a lot attention in the last decade. Titanium dioxide (TiO2) inhibits amazing photocatalyst properties including high activity, chemical stability, and low cost. Nevertheless, the photocatalytic activity of TiO2 (with band gap of 3.2 eV and excited by photons with wavelengths under 387 nm) is still limited to irradiation by UV wavelengths, so that photocatalytic process does not occur effectively during the irradiation with solar light as only about 4% of the total radiation of the solar spectrum is in ultraviolet region. 

Currently there are two types of minerals in China: wolframite and scheelite. Tungsten is a kind of rare metal and significant strategic material. It is called "heavy stone" from ancient China. In 1783 tungsten was named by the Spaniard DE Puria. The tungsten content in the crust is 0.001%. Generally the tungsten ores are formed for the activity of granitic magma. Tungsten is a silver-white shiny metal with high melting point and high hardness after smelting. There are more than 20 types of tungsten minerals and minerals containing tungsten which are discovered.

Pure tungsten bar is made of 99.95% tungsten power and its forging and annealing process is shown by test. The bar has physical properties e.g. density 19.3g/cm3, melting point (liquid) 3422℃, electricity conductivity 30% IACS min and hardness 69hra min. It owns special characters including low thermal expansion, good thermal conductivity, sufficient resistance and high elastic modulus. The bar is widely applied in various fields, e.g. support line, lead-in line, printer needle, various electrodes, quartz furnace, filament, high-speed tools, automatic products, sputtering target and heating devices with special properties etc. Powder metallurgy is a popular method in production process. 

China has the largest tungsten reserve and tungsten output whose reserve are four times of  other countries in the world, tungsten ore was found early 10th century and was called "heavy stones" at that time. Tungsten ore in China is mainly located in the Sanjiang tungsten tin metallogenic belt,West Qinling-Qilianshan metallogenic belt, Tianshan-Beishan metallogenic belt, south China metallogenic belt and north China metallogenic belt. Nanling metallogenic belt is the most richiest in south China metallogenic belt, and numerous large and super large tungsten ores are distributed in this metallogenic belt with more than 70% reserve of China. The tungsten ore in China was mainly formed in Yanshanian era accounting for 83%, Hercynian era 9%, Caledonian era 4%, Precambrian era 2% and Indosinian era 2%.