Study On The Process For Producing High-Purity Ruthenium Used For Sputtering Target

The preparation of high-purity metal used for sputtering target is an important research goal in metal materials engineering. This dissertation concerned in studies on the process for producing high-purity ruthenium and the refinement technology, which was improved by combination methods of physics and chemistry, and wet metallurgy and fire metallurgy methods. The purity of ruthenium achieved at least 99.999%, which could be applied to sputtering target directly. The dissertation is consistent of eight parts:1. The background and current situation of this work is concisely introduced. The goal and significance of the topic is expatiated.2. The theoretical principle of preparation of high-purity ruthenium from ruthenium hydrochloric solution was disscused. Two process stages of oxidation and distillation technology with standard oxidation-reduction potential E0 as the creterion of oxidation reaction was analyzed. In the first stage, osmium was first efficiently distilled and oxidated with H2O2 as oxygenant from ruthenium hydrochloric solution. Then, ruthenium was efficiently distilled after oxidation with NaC103+H2S04 as oxygenant in the second stage. At the same time, residual osmium were further efficiently removed and oxidated again from ruthenium hydrochloric solution.3. The process for producing the purity ruthenium hydrochloric solution by conventional method of oxidation and decompression distillation from original ruthenium solution was studied. The effects on the distillation efficiency and the refinement efficiency of the product were investigated, and the optimum process parameters were given by orthogonal test. The results showed that there were a lot of shortcomings in the conventional processes, such as few treatment raw material amount, the longer distillation time, the lower distillation efficiency, numerous reagents consumption. Furthermore, the processes must be in high distillation temperature and high vacuum, which lead to not only more expensive operating cost, but also higher impurity content of the third ruthenium hydrochloric solution.4. The process for producing the purity ruthenium hydrochloric solution by high-gravity way of oxidation and vacuum degassing from ruthenium hydrochloric solution was studied in Rotating Packed Bed Reactor (RPBR). The feasibility of the process of oxidation and decompression distillation in RPBR was analyzed. The effects on the distillation efficiency of osmium and ruthenium, and the purity of the refined ruthenium hydrochloric solution were investigated, and the optimum process parameters were given by orthogonal test. The experimental results showed that the RPBR possesses the advantage of the short reaction time, higher vacuum degassing efficiency of osmium and ruthenium, especially lower distillation temperature and lower vacuum degree, less dosage of reagents, and lower energy consumption. The high-purity ruthenium hydrochloric solution was preparated easily by this method.5. The process for producing the pure ammonium ruthenate chloride by the precipitation method of ammonium chloride from the purity ruthenium hydrochloric solution was studied. The effects on the deposit rate and the refinement effect of the ruthenium hydrochloric solution were investigated, and the optimum process parameters were given by orthogonal test. The precipitation rate of ruthenium reached about 99% and impurity elements content decrease to a great degree. Therefore, the high-purity ruthenium salt can be prepared to produce high-purity ruthenium powder by this method conveniently.6. The process for producing the purity sulfide ruthenate by the precipitation method of sulfide sodium from the purity ruthenium hydrochloric solution was studied. Under the optimum operation condition, deposit rate of ruthenium reached about 99%. The high-purity ruthenium salt can be prepared to produce high-purity ruthenium powder by this method conveniently, and the theory of reaction mechanism of the process was discussed.7. The sinter and reduction process of the high-purity ruthenium salt, and acid boiling process of the sponge ruthenium powder were studied. The sponge ruthenium powder was prepared under the optimum operation condition of the sinter and reduction in a hydrogent atmosphere. The sponge ruthenium powder product was washed first by a mixed solution of aqua regia and hydrofluoric acid, and further washed by water before drying. The high-purity ruthenium could be obtained, purity of ruthenium of at least 99.999% excluding the gaseous ingredient elements by GDMS analyzed, and could be used for preparing high-purity ruthenium sputtering target.8. The waste liquor recovery, metal balance, cost accounting, economic benefit and social benefit in the refining process of ruthenium were studied and analysised.