湿法冶金加压氢还原制取微细镍粉

阐述了用湿法冶金加压氢还原技术制取微细镍粉(0.2-1.0μm)的方法。该法以工业碱式碳酸镍为原料,水为制浆介质,直接进行浆料氢还原。在配制浆料时加入一定量的硫酸,以保证溶液中有足够的初始镍离子浓度,并消除原料组成及原料pH值的波动带来的不稳定因素。同时加入催化剂,以增加固体表面的活性,以此作为缩短或消除反应诱导期的主要手段。并提出,在确定的镍离子还原初始浓度下,可通过控制固体表面的活性来达到控制产品粒度的目的。此外,还从镍颗粒的形貌试论了该还原反应的机理。

FINE NICKEL POWDER MADE BY HYDRO-METALLURGYPRESSED HYDROGEN REDUCTION

The present paper has discussed a hydrometallurgical pressurized hydrogen reducing technolgy. Fine nickel powder(0.2-1.0μm) was obtAlNed by direct reduction from slurry, using alkali lithium carbonate as raw materials and water as the medium of slurry.Reducing conditions are as follows:P_H2-25kg/cm2, temperature-175℃ and quantity of alkali lithiun carbonate750g/L. A required quantity of sulphuric-acid was added into slurry allowing sufficient concentration of initiative nickel ion and eliminating the unstable factors arisen from the fluctuation of raw material composition and pH value.At the sametime, anthraquinone and other catalyst were added into shurry for increasing surface activity of solid, completely eliminating introductive period or shortening it from about 50 to 3-5 minutes with a result of great improvement of productivity. It was also shown that after the ascertainment of the concentration of initiative nickel ion the surface activity of solid can be controlled by odding different kinds and quantities of catalysts with the aim of controlling particle sizes of products. Besides,reaction mechanism has been discussed from the ellipsoidal shape of nickel powder.It is considered that the direct reduction of alkali nickel carbonate may be conducted by the reduction of nickel ion solved in liquid phase. Finally, nickel powder and aluminium powder (or other metal or ceramic powders) were compounded by spray drying process to obtain nickel-based composite powder suitable for hot spray coating.