Alkaline refining of crude lead: a method of arsenic removal and the behavior of arsenic in the process

In this work, the alkaline refining of arsenic in crude lead was studied with a mixture of sodium hydroxide and sodium carbonate as alkaline refining agents. Taking the arsenic removal rate as the research object, the effects of reaction temperature, holding time, Na2CO3:NaOH, the dosage of refining agent were investigated. The arsenic removal rate is 79.09% under the optimum experimental conditions as follows: reaction temperature 823 K, holding time 60 min, Na2CO3:NaOH 1:4, refining agent dosage 10%. The oxidation purification mechanism of arsenic was studied by XPS, SEM-EDS, XRD and FT-IR. The results show that arsenic in the crude lead is gradually oxidized by oxygen and lead oxide during arsenic removal process, and the arsenic trioxide is eventually converted into sodium arsenate (Na3AsO4) and lead arsenate (Pb2As2O7) in the slag.

THE EFFECT OF CeO2 NANOPARTICLE DOPING ON REFINEMENT OF Y-211 PARTICLES IN POIG PROCESSED YBCO COMPOSITES

Doping of non-interacting nanoparticles in YBCO superconductors in order to get fine microstructure defects has been studied. Y-211 inclusion, itself has large potential to create structural defects without affecting Y-123 matrix phase. Nanoparticles of grain refining agent like CeO2/Pt/PtO2 are interesting dopants, especially CeO2 for being cheaper than Pt. POIG process, as is one of the advance processing techniques to get uniform distribution of fine Y-211 particles of the order of 1-2 μm, throughout the YBCO composites. Finer Y-211 particles can drastically increase the pinning centers. Introduction of fine sized CeO2 as grain refining agent to reduce the size of Y-211 particles would create additional pinning centers. In the present work, the effect of CeO2 on Y-211size and distribution in POIG processed YBCO composite was studied. It was observed that with increase in CeO2 content Y-211 particle size decreases below 1μm and even less than 0.5μm for 10 weight percent CeO2 doping. The mechanism for refinement appears to be the formation of BaCeO3 on the surface of Y-211 during liquid phase infiltration that leads to splitting of Y-211 into smaller particles.

Research on the Effects of the Refining Treatment to the Properties of Dual-Phase Wear-Resistant Steel

Using refining agent to proceed refining treatment on dual-phase wear-resistant steel, the refining agent is made up of CaO, CaF2, Al2O3, Al, Na2CO3 and BaCO3. The experimental furnace is 25kg vacuum induction furnace, stalling 10 minutes after adding the refining agent, the heating temperature is between 1550 and 1600°C. By doing this, the content of harmful impurities including O, N and S in the steel is significantly reduced and the mainly existing form of the main non-metallic inclusions is changed, it also reduces the size and number of the microstructure of the inclusions in the steel and improves the impact toughness and elongation of dual-phase wear-resistant steel significantly.

Study on Purification and Removal of Iron from Alloy Anode

Residue of alloy anode generated in three-layer liquid electrolytic purifying method is refined, the state of iron in raw materials is analysed. The state (morphology) changes of iron refined by different refining agent are investigated. Results show: 40% of boron salts or phosphate as the main component of refining agent adding 15% NaCl、20% KCl、15% CaF2、5% NaF、5% cryolite, melting the residue of alloy anode at 1100°C and 1200°C respectively, the crystal could be incubated to grow up fully, it is benefit for collecting iron. When the soaking time is 150min, iron component in alloy is 4.8%,it reaches the standard taking back into the aluminum refining process.