Research On The Preparation Of High Purity W-Mo Powders From Crude W-Mo Blend Concentrates

W-Mo ore is a complicated multi-metal mineral resources in China.However,due to the complicated geological conditions and special ore structure,the ore dressing is extremely difficult,it causes higher costs of present metallurgical processes.At present,there are few prerequisites for the dressing and extraction of tungsten molybdenum oxide ore in industry.In the field of mineral processing,Zhengzhou Institute of Multipurpose Utilization of Mineral Resources,Chinese Academy of Geological Sciences has been successfully achieved tungsten and molybdenum polymetallic ore flotation enrichment,access to Mo and WO3 more than 30%crude tungsten and molybdenum blend concentrates.In this study,using the crude tungsten and molybdenum blend concentrates as a raw material,a novel hydrometallurical process was developed to prepare high purity W-Mo powders.The research mainly focused on roasting-acid leaching combined pretreatment process,extraction of tungsten and molybdenum from pretreatment material by roasting with soda and leaching with water,aluminum salt-magnesium salt coprecipitation purification,obtain high purity tungsten and molybdenum mixed compounds by co-precipitation and co-crystallization process,preparation of high purity W-Mo powders from tungsten and molybdenum compounds by co-calcination and co-reduction process.Main experimental results are as follows:Firstly,we need to analyze chemical composition and phase of crude tungsten and molybdenum blend concentrates in order to make a experimental plan.After roasting-acid leaching combined pretreatment process.Under the optimum experimental conditions that are oxidation roasting at 600 ℃,leached with 3%hydrochloric acid at room temperature to remove the raw material impurities and gangue minerals,the recovery of tungsten and molybdenum was up to 98.17%and 96.24%,respectively.The tungsten and molybdenum grades in the ore increased from 16.51%and 14.92%to 19.90%and 17.63%,seperately.The leaching test was carried out based on the pretreatment material.Under the optimum experimental conditions that are soda-silicon roasting for 2 h at 850 ℃with 3 times stoichiometric ratio of Na₂CO₃ and ω（SiO₂）/ω₍Conc₌12%and subsequently water leaching for 1 h at 70 ℃ with a liquid-to-solid ratio of 3:1,98.89%W and 99.41%Mo were extracted.Study on the technology of removal impurity-coprecipitation-cocrystallization process.Under the optimum conditions,the coprecipitation process of tungsten and molybdenum recovery rate were 99.50%and 99.68%,respectively.The high temperature acid precipitation of tungsten and molybdenum precipitation rate were 84.02%and 99.03%,respectively.The low temperature acid precipitation of tungsten and molybdenum recovery rate were 98.88%and 93.51%,respectively.The acid pickling process of tungsten and molybdenum recovery rate were 91.67%and 97.89%,respectively.The tungsten and molybdenum compounds obtained from evaporation crystallization experiments show purity levels of>99.95 wt%.Under the optimum conditions,the thermal decomposition temperature at 500℃,first step reduction with hydrogen at 520 ℃,second step reduction with hydrogen at 920 ℃,the W-Mo powders obtained from co-calcination and co-reduction experiments show purity of>99.9 wt%with oxygen as the major impurity of 500 parts per million（ppm）.The study overcomes some problems that are the long technological processing and the great difficulty of separation of tungsten and molybdenum with the traditional method,which provides a new possibility of comprehensive and efficient utilization of resources of tungsten and molybdenum.The research utilizing the low-grade tungsten molybdenum oxide ore as the raw material for the production of high added value W-Mo powders by removing impurity-leaching-coprecipitation-coreduction process.It provides technical support for the development and utilization of complex low-grade nonferrous metal resources in china.