Sulfur Resources Should Be Fully Utilized      

By Sun Qixiang    

Sulfur is an indispensable chemical raw material extensively used in various chemical processes. The output of sulfuric acid is usually regarded as an indicator of the development level of industries in a country. With the growth of the chemical fertilizer industry worldwide, the phosphate fertilizer sector in particular, the demand for sulfur, an important raw material for sulfuric acid, has grown greatly. Although sulfur resources are very plentiful around the world and the output of sulfur is also slightly higher than the actual demand, most sulfur resources in trade are not mined but are byproducts of processing other chemicals, making the supply conditions more uncertain. Chemical fertilizer production is the biggest consumer of sulfur resources, accounting for around 70% of the world total for many years.
   Reportedly, the world's reserves of sulfur resources are around 3.5 billion tons (counting on 100% sulfur). Canada, Poland, Saudi Arabia, China and the United States have the five biggest reserves in the world. China has 1.4 billion tons (physical goods, the same below), including 812 million tons of pyrite, 301 million tons of associated sulfur and 317 million tons of native sulfur.

Sulfur, pyrite and smelting flue gas each hold a 1/3 share

Raw materials for sulfuric acid production include sulfur, pyrite (including associated pyrite and coal-containing pyrite) and the flue gas of smelting sulfur-containing nonferrous metals (copper, nickel, lead and zinc). In appearance, among these three sulfur resources, only pyrite is a natural mineral. In reality, however, sulfur and flue gas of smelting sulfur-containing nonferrous metals are also closely related to natural minerals. The former is from the processing of natural gas and crude oil. The latter is from the smelting of various nonferrous metal minerals.
    (1) As pyrite is a natural mineral, it is a sulfur resource produced "from scratch" by mining. At the same time, however, it has a narrow scope of end applications (mainly sulfuric acid production) and unfavorable properties for storage and transportation.
    (2) Sulfur and smelting flue gas are both sulfur resources that are opportunities arising from other endeavors. Their production is determined by the demand in end applications other than sulfuric acid and will not terminate because of a surplus of sulfur or sulfur-containing compounds. These two resources are of course not exactly the same. Sulfur has good properties for storage and transportation. It has considerable freedom of handling and can be transported over long distances or stored nearby. Sulfur contained in smelting flue gas is in the form of sulfur dioxide and must be treated promptly at the smelting site.
    These three sulfur resources, as raw materials for sulfuric acid production, have evident quality differences. In terms of production process, the process using sulfur is the simplest and no waste water or waste residues are generated. From this point of view, sulfur is undoubtedly the ideal raw material for the sulfuric production. Moreover, the process using flue gas has some unfavorable factors. For example, dust, arsenic and fluorine are contained in flue gas and the process flow is rather complicated. Due to the overwhelming importance of environmental protection, however, smelting flue gas has to become a raw material for sulfuric acid production because it is the key alternative for mitigating the exhaust's environmental impact. Comparatively speaking, pyrite has the most passive position. It has unfavorable factors similar to smelting flue gas and is also a sulfur resource that is produced deliberately. When the price of sulfur goes down or the output of nonferrous metals increases drastically, sulfuric acid plants using pyrite as raw material are inevitably the first to bear the burden. When there is a sulfur supply deficit, however, pyrite producers can fully employ their advantage in geographical location and develop vigorously. So pyrite is extremely important in regulating the supply of sulfur resources in China.
   Pyrite is the major sulfur resource in China. But in terms of per-capita occupancy, the reserves of pyrite in China are comparatively far from being rich. Furthermore, there are few large mines and high-grade ores but many small mines and low-grade ores. As a result, the raw materials for sulfuric acid production in China must be imported. As a matter of fact, it is the only choice for China's sulfuric acid industry. The oversupply in the international sulfur market from the last years of the past century into the early years of the present one promoted the development of domestic sulfuric acid production with sulfur as the raw material. The proportion of sulfuric acid using sulfur as raw material in the total output increased from 5.4% in 1997 to 46.6% in 2009. With the import of great quantities of sulfur and the rapid development of the nonferrous metal smelting sector, the layout of raw materials for sulfuric acid production has been constantly optimized and adjusted in China. The proportion of sulfuric acid output using pyrite as raw material has been reduced constantly, the proportion using sulfur has increased rapidly and the proportion using smelting flue gas has increased steadily. A raw material layout formed with sulfur, pyrite and smelting flue gas each holding a 1/3 share.

Fully utilize overseas and domestic resources

1. Guide the sound competition between imported sulfuric acid and domestic sulfuric acid

As sulfuric acid is in serious surplus in Japan and Korea and the storage cost of sulfuric acid there is very high, these two countries need to export great quantities of sulfuric acid each year. Major targets are China and India. Smelting enterprises in Japan and Korea can successfully export only by offering subsidies to traders. As the shipping cost is very high, the FOB price of sulfuric acid is often a negative price (lower than its selling price in Japan or Korea).
   The sales of sulfuric acid in Japan and Korea in such special trade form have posed great threats to the sulfuric acid industry in China. In 2009 quite a few smelting enterprises in China filed a petition to conduct an antidumping investigation into imported sulfuric acid from Japan and Korea. To sum up, overseas low-price sulfuric acid and domestic sulfuric acid should both be used in balance. In the future, new sulfuric acid plants should be constructed in China's inland areas. Coastal areas can use imported sulfuric acid.   

2. Strengthen the utilization of various domestic resources

First of all, high-sulfur pyrite should be used as raw material to increase benefits in sulfuric acid production using pyrite as raw material. Mining enterprises should be encouraged to use their mines as the basis and construct large sulfuric acid units. Advanced processes should be used to achieve clean production. The comprehensive utilization of waste heat and cinder should be strengthened to enhance competitiveness. The recovery of sulfur resources in the utilization of coal, oil and natural gas should also be strengthened. The total emission of sulfur dioxide in waste gases in China today is basically equal to the consumption of various domestic and overseas sulfur resources in the sulfuric acid production. Although the recovery of sulfur in coal has a disadvantage in cost for the time being, with technical progress the utilization of these sulfur resources will surely make breakthroughs.