| Abstract:Wet processing are mainly used in tungsten metallurgy. Almost all of basic leached residue from tungsten concentrate (hereinafter referred to as the'tungsten residue') contains a small amount of valuable metals such as tungsten, iron, manganese, tantalum, niobium, scandium, and so on. For the present, piled tungsten residues with a total capacity of nearly one million tons may have greater value of comprehen-sive recovery. The present treatments of tungsten residue mainly focuse on the recovery of tungsten and scandium, while tantalum and niobium are neglected.According to the characteristics of tungsten residue, hydrometallurgi-cal recovery of tungsten, concentration of tantalum and niobium and preparation of manganese-zinc ferrite powder were investigated by using tungsten residues with high calcium and silicon and lower tungsten as the raw material. A new clean process involving comprehensively covery of tungsten, tantalum, niobium, iron and manganese from tungsten residue was developed. And radioactive contamination and "three wastes" treatment of the technology were analyzed. The main conclusions derived from this study are:The recovery process of tungsten from the residue and the way to increase its recovery were systematically investigated. The characteristics of the technological mineralogy of tungsten residue was in detail inspected. And the impacts of several technical factors on the tungsten recovery were compared. Tungsten scattered in both solid and liquid during acid processing and the recovery of tungsten topped out at79.2%. However, it's difficult to obtain product due to the complex composition of acid leaching solution. Using the process of preroasting-water leaching, leach liquor contains low contents of impurities. It is found that recycling of tungsten bearing leach liquor benefit the increases of tungsten recovery. The amount of tungsten in the solution may reach16.6g·L-1and total recovery of tungsten may over88%after three cycles.The enrichemnt of tantalum and niobium from tungsten residue was systematically studied. Enriching behaviors and recoveries of tantalum and niobium were compared in the technologies such as hydrochloric acid treatment directly, leaching directly by sulfuric acid solution, concentrated sulfuric acid roasting and complexation leaching, the technology of soda sintering and water leaching, combining acid&alkaline process. According to the experimental results, the different solubilities of tantalum and niobium salts in the acid and alkaline solution led to differences of the enrichment effect and recoveries. Recoveries of tantalum and niobium ran up to80.1%and72.3%respectively as the tungsten residue was processed at low temperature and low acidity. Concentrate carried Ta2O5and Nb2O5with the total content as5.34%can be gained at high temperature and high acidity. And concentrate with the total content of Ta2O5and Nb2O5as13.03%was gained via process involving concentrated sulfuric acid roasting and complexing leaching, which could be used as the feed for tantalum and niobium metallurgy. The total content of Ta2O5and Nb2O5in concentrate from the combining technology was higher than acid treatment or alkaline treatment directly, while the overall recovery decreased. The application sequence of the acid and alkaline in the combining technology had some effects on the enriching behavior of tantalum and niobium. Few tantalum and niobium turned into solution when alkaline treated.Preparation of manganese-zinc ferrite powder from tungsten residue has been studied for the first time, which comprised high-value utilization of manganese and iron. Process of manganese-zinc ferrite powder prepara-tion involving leaching by sulfuric acid, purification of leaching liquor, coprecipitation and sintering has been investigated. The experimental results demonstrated that proportion of main metals in manganese-zinc ferrite powder near the theoretical value and the powder has low contents of impurities, for instance, silicon0.023%, calcium0.021%, magnesium0.027%, which can meet the quality requirements of manganese-zinc ferrite powder. Manganese-zinc ferrite powder with different ingredients may be obtained by compositional controlling of liquor before coprecipita-tion.Process of the preparation of manganic manganous oxide from tungsten residue has been investigated. Two-stage sulphating roasting was adopted to separate manganese from iron. The tungsten residue&50%sulfuric acid mixture was roasted at200?for60min and then the temperature is raised to700?and keep120min. Manganese beraing solution, in which mass ratio of manganese and iron could reach more than3000, was gained by water-leaching and the leaching efficiency of iron was only0.01%. The results show good separation of manganese and iron. Ultrafine manganic manganous oxide powder with particle size of less than0.1?m was prepared by means of purification of solution, neutralization and precipitation of manganese and oxidation of hydroxide by H2O2. The major product quality indexes basically can meet the enterprise standard (HG/T2835-1997).The clean process involving comprehensively recovery of valuable metals in tungsten residue was developed. Investigation shows that tungsten, tantalum, niobium, iron and manganese could be recovered effectively from tungsten residue via the technology composed of soda sintering, sulfuric acid leaching, liquor purification, coprecipitation and sintering procidure. And the total recoveries of tungsten, tantalum, niobium, iron and manganese weres reported to88.1%,78%,56%,95.2%,68.5%respectively. According to researches on the radioactivity and three-wastes treatment during comprehensive recovering procee, the radioactive elements were distributed in many kands of products, mainly in the leach sludge from sulfric acid processing with a specific radioactivity as18556Bq/Kg, which meets discharge standards and may be used in tantalum and niobium metallurgy. The technology has better achieved clean processing of tungsten residue due to less three wastes which are easily disposed. It not noly recycled industrial wastes but also opened new doors for manganese resource ferrite industry via its production from tungsten residue. There were73figures,67tables and136references. |
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