DEVELOPMENT OF METHOD FOR REMOVAL THE NITRIC OXIDES FROM PROCESS OF PRECIOUS METALS RECOVERY FROM ANODE SLIME
Nitric compounds, especially nitric oxides, are extremely toxic with many unfavorable local effects, especially in the surrounding of great pollution sources. This work contains the results of laboratory research for involving of the best absorption parameters (temperature, type and concentration of absorption liquid), as well as a selection of absorption system for completely removal the nitric oxides from process of hydrometallurgical recovery of precious metals from anode slime in Plant for Anode Slime Treatment. The basic aim is decreasing of nitric oxides emission to the law approved concentration, both in working conditions and at gas emission point of the plant.
NOx suppression with hydrogen peroxide in the metals industry
Metal dissolution processes involving nitric acid are major sources of NOx. Technologies using hydrogen peroxide have been developed and proven on an industrial scale to suppress the emission of NOx from these processes. No changes are made to the dissolution process. Case histories are presented to illustrate the effectiveness of hydrogen peroxide with particular reference to the pickling of stainless steels.
Failure analysis for poor solderability of Au surface of PCB
Nonwetting is one of the common problems and is always rejected in electronic assemblies. ENIG pads of a PCBA exhibited nonwetting after lead-free reflow soldering. With the aid of stereomicroscope, SEM&EDS and XRF, a series of analysis was performed. And after visual inspection, surface and cross section analysis, thickness measurement and solderability test, it can be inferred that oxidation of plating surface was the main reason for nonwetting, and corrosion in Ni plating caused an adverse impact on solderalibity.