Research on Sponge Titanium Smelting Technology
China's sponge titanium production, relying on domestic strength to gradually achieve technological progress, from fixed bed chlorination to boiling chlorination, from packed column rectification to flotation tower rectification, from reductive distillation separation to reduction distillation combined, magnesium electrolysis from partition The large-scale non-separator and the closed circuit of magnesium and chlorine are realized. The scale of production ranges from 100 tons to 1,000 tons until it reaches the economic scale of 5,000 tons.
However, compared with the advanced level in foreign countries, there is still a big gap. Mainly in the technical and economic indicators, "three wastes" governance, equipment support level and automatic control.
To expand the scale of the factory to 10,000 tons and realize the modern production of "clean, civilized and pollution-free", it is necessary to improve the existing technology and equipment for the existing problems. The main research directions and topics can be summarized as follows .
1. Manufacturing technology of high-grade titanium-rich materials Western countries use high-grade natural rutile and synthetic rutile as raw materials to produce titanium sponge. China lacks high-grade natural rutile resources and does not produce high-grade synthetic rutile. The production of titanium sponge is based on high-titanium slag containing about 92% of TiO2. The high-titanium slag is produced by a small open electric furnace. The scale of the factory is small, and the technology and equipment are also very backward. Because asphalt is used as a binder, the environmental pollution is serious. Strictly speaking, these high-titanium slag small factories are small electric furnaces with high energy consumption and high pollution that belong to the national policy.
The technical improvement of producing high-titanium slag containing TiO292% is quite difficult, and there is no related technology abroad. Foreign large-scale closed electric furnace can only produce titanium slag containing about 205% of TiO. The semi-closed electric furnace in the CIS countries can only produce about 90% of titanium slag, and must use high-quality ilmenite as raw material. If China's ilmenite is used as raw material, it can only produce 85-87% of titanium slag.
Compared with 96% natural rutile (impurities 4%) and 92-94% synthetic rutile (6 to 8% impurities), 92% of high titanium slag (11% impurity) is already a "coarse grain". Therefore, the factory does not want to use raw materials with a lower grade than 92% high titanium slag.
Large sponge titanium smelters hope to use high-grade titanium-rich materials to solve the problem of high-grade raw materials.
1) Construction of a large-scale high-grade titanium-rich material factory:
Since China's titanium resources are mainly characterized by low-grade ilmenite, it is decided to use a titanium-rich material process with high impurity-removing ability to obtain high-grade titanium-rich materials. Among them, hydrochloric acid leaching method to manufacture artificial rutile process route, in addition to strong impurity ability, can process high-calcium-containing low-grade titanium concentrate into high-grade synthetic rutile containing TiO292~94%, related technology research is close to maturity, hydrochloric acid It can be recycled, and the supplemental hydrochloric acid can be supplied by hydrochloric acid by-product.
2) Imported high-grade synthetic rutile: Australia has a very rich high-quality ilmenite. The content of artificial rutile TiO2 produced by reducing rust method is 92-94%, and the completed plant has an annual production capacity of more than 800,000 tons.
Therefore, it is possible to consider importing this artificial rutile from Australia, its particle size is very consistent with the requirements of boiling chlorination, and also contains a certain amount of low-cost titanium.
2. Further study on the large-scale technology of boiling chlorination furnace
In the process of large-scale production of sponge titanium in China, the biggest difficulty encountered is the manufacturing technology of titanium tetrachloride, including two processes of chlorination and refining; the largest gap with foreign advanced level is also the manufacturing technology of titanium tetrachloride; In the future, the size of the boiling chlorination furnace and the level of chlorination technology should be improved (including increasing the chlorination rate of titanium, the utilization rate of chlorine, the capacity of chlorination furnace, reducing the chlorine content of tail gas, and improving the recovery rate of titanium tetrachloride. ) is one of the focuses of future research work.
3. New process for removing vanadium from titanium tetrachloride In the current industrial production, there are three methods for removing vanadium from copper wire, mineral oil and aluminum powder. Among them, the copper wire has good vanadium removal effect, and high quality titanium tetrachloride can be obtained, but the intermittent operation, the washing and regenerating operation after the copper wire failure is labor-intensive, the operating environment is poor, the copper consumption is high, and the cost of removing vanadium is high, only suitable Application in small-scale production.
The cost of removing vanadium from minerals is low, but special heating method is needed to produce a bulky residue liquid. The residue is easy to crustle on the heating wall. The titanium tetrachloride after vanadium contains a small amount of organic matter, which is difficult to separate and remove. It is more suitable for chlorine. Production of titanium dioxide.
The aluminum powder has less residue of vanadium and is less prone to crusting. It is easy to recover vanadium from the residue. The low cost of vanadium removal is a vanadium removal method suitable for the production of titanium sponge.
Aluminum powder in addition to vanadium has been successfully used in the production of titanium sponge in the CIS countries for many years. Beijing Research Institute and other units have successfully completed small-scale experimental research, indicating that the removal of vanadium from aluminum powder is a feasible process technology. However, such ultra-fine active aluminum powders used in the CIS countries are expensive and explosive, requiring research and improvement.
4. Large-scale magnesium reduction distillation combined method to improve product sponge rate
The large-scale reduction distillation combined method produces sponge titanium. Due to the expansion of the reactor capacity, the heat generated by the reduction reaction cannot be effectively output, resulting in local high temperature, which leads to densification of some products. At the same time, it also hinders the increase of the feed rate and increases the production cycle. Equipment capacity is reduced.
Therefore, it is necessary to further study the process and equipment for improving the large joint method to increase the equipment capacity and increase the sponge rate of the product.
5. Large non-separator slot magnesium electrolysis reduces power consumption
In the past, in the production of titanium sponge, magnesium electrolysis technology has been relatively backward. Since the use of 110KA non-separation tank magnesium electrolysis process, the technical level and technical and economic indicators have improved significantly.
However, in the process of introduction and digestion, some of the techniques in this technology are still insufficiently mastered. Therefore, the current efficiency is low and the power consumption is high, which requires further research and improvement.
6. The automatic control of the production process and the automatic control technology for the management of the sponge titanium production process have a certain foundation. In the future, further research should be carried out to prepare, chlorination, refining, reduction distillation, crushing, sorting, packaging, magnesium from titanium-rich materials. Computer control and management of the entire process of electrolysis.
The research content includes the sensing elements of the measured parameters, measuring instruments, actuators and computer control, etc., and finally realizes the control of each process and the computer networking of the main control room, so that the sponge titanium production management can fully realize the automatic control.
7. The research on the new method of making titanium has become the hot spot of the international titanium industry. The new technology of making titanium has always been a hot research topic in the world. In recent years, research on this worldwide problem has made some progress. The University of Cambridge and Australia CSIRO have studied several different new titanium dioxide processes for TiO2 electrolysis. It is said that the cost of titanium can be reduced by about 50%. The United States and the United Kingdom are expanding their experiments and plan to push the FFC process to industrialization.
If a new titanium alloy can be produced by TiO2 electrolysis, for example, a titanium alloy containing a small amount of iron, natural rutile or synthetic rutile can be used as a raw material, and other alloying elements are added in the form of an oxide, so that the cost of the titanium alloy produced is large. reduce.
Through the completion of the above research, the technical level of sponge titanium production in China will be greatly improved, and conditions can be created for the production of 10,000 tons of sponge titanium.
After several years of research and technical research, China's sponge titanium production technology will enter the world's advanced level, and then achieve 10,000-ton production scale.