The Paper describes the analysis and demonstration of NaOH substitution for some soda;soda solution initial concentratoon and min.temperature during dissolution,etc in soda autoclaving of tungsten ore.Some helpful conclusions are drawn.

In this paper,ultra-fine Ce-Zr-O powders were prepared by the means of coprecipitation under the room temperature.The powders were analyzed with Laser particle sizer,XRD,TG,specific measuring and testing instruments.The factors influencing product particle size:such as the composition of mixed liquid,the ways of feeding material,the type of additives,the calcining temperature etc.were studied.The results show that uniform particle size and super suspending ultrafine Ce-Zr-O powders were obtained by the following process:First zirconium nitrate and cerium nitrate were fed into ammonia water to get precipitate under the room temperature;then drying and calcining the precipitate to get product.

Analysis is made of the structural features of the steel-bonded cemented carbide pre-alloyed powder.Study is made of the influence of different carbon content on the pre-alloyed powder structure.Powder preparation process is developed on the basis of the features of steel-bonded cemented carbide pre-alloyed powder.The O_2 content is reduced by reduction annealing,resulting in improved powder structure.

The formation of η-phase of dual phase gradient cemented carbide matrix and the characteristic of cobalt-phase gradient distribution are studied.The formation mechanism of cobalt-phase gradient cemented carbide has been analysed.

Study is made on the preparation method,particle morphology and crystal structure of spherical cobalt oxalate and spherical Co(OH)_2,which are used as precursor for reduction of Co metal powder.Discussion is made on the relationship between the morphology of Co powder particle and precursor.

High-purity Ta_2O_5 is obtained by low-acid partial extraction from commercial Ta stripping solution of HF-H_2SO_4-Paraoct and Ta/Nb extraction system,using N503+Kerosene+modifier A as extractant so that part of Ta is extracted into the organic phase followed by further separation from Nb and impurity,stripping under alkali condition to obtain high-quality Ta solution,followed by neutrallization;washing;drying and calcination to result in high-purity Ta_2O_5.

Description is made of the process for trace Si removal from ultra-pure YCl_3 solution by molybdate commercial alcohol extraction.Discussions are made about the main technological factors affecting Si removal efficiency by extraction process.

In view of quality problems occured in Ge extraction,study is made on removal of S, As from high S/As/Si low-quality raw material.Results showed that high-temperature S removal,As removal by oxidization and two-step Si removal has resulted in distinct efficiency and qualified Ge concentrates are ensured.

Based on the traditional technology,large improvement is made on the key operations of small-diameter Ta wire,focusing on the elimination of the problems in Ta wire produced by original technology,such as high O_2 content;low tensile strength,poor surface quality,large tolerance,low resistance against partial O_2 brittleness.The new technology has resulted in better integral properties of Ta wire and increase of recovery by 5%.The product is qualified enough for export purpose.

In this paper,description is made of the development of the cemented carbide with rare-earth additions in the last 10 years.Brief description is made of the influence of rare-earth elements on the texture and performance of the cemented carbide.