Fundamental Investigation for Processing of Pb-Cu-S-Bearing Materials

The processing of polymetallic materials provides some challenges to every flowsheet. Within Aurubis Cu-Pb-metallurgical flowsheet, a broad range of raw materials and intermediates are processed. Continuous improvements are required to adapt the flowsheet according to the changing material quantity and quality. Therefore, thermodynamic modeling is the desired and most efficient way to conduct scenario analysis. Hence, databases and software are becoming better and better as the acceptance of this method increased. Further understanding is promoted by conducting experimental test work to validate the calculated results. In this research work, the impact of various oxygen potential on the formation of the condensed phases’ slag, matte, speiss and crude lead were investigated. A frequent check of slag metallurgy, in particular, the iron and lead concentration, provide feedback if the metallurgical process is operating at the right oxygen potential. Following, the calculated distribution coefficients for Cu, Pb, As, Sb, Sn and Ni between matte/speiss and speiss/lead are discussed.

Application of technical nitrogen during gas nitriding austenitic steels

The possibility of using technical nitrogen including 0,2% O2 for activation austenitic steels surfaces during gas nitriding were investigated. By changing mole fraction of technical nitrogen i NH3 /N2t mixture one can regulate oxygen potential of gas atmosphere during heating the steel to nitriding temperature and sometimes during nitriding process. Four representative austenitic steels were nitrided with good results at 570°C and under 450°C. New method can be alternative to regulating oxygen potential by air and allows avoiding installing of firing mechanism and safety control.

Detection of Reserve Oxygen Potential in the Present of Fine Bubbles and its Ammonia Removal for Aquaculture Effluent

The availability of oxygen and the minimum amount of ammonia in the water media are crucial in catfish larvae hatchery performance. The condition with a balanced amount of required oxygen and the presence of ammonia resulting from the feces of striped catfish larvae is essential to maintain the health of the aquaculture media. This study aims to remove ammonia by introducing fine bubbles (FBs) into recirculating aquaculture media and investigating reserved dissolved oxygen inside the bubbles in the media. The water media for the striped catfish larvae hatchery was designed and set up with three containers in a recirculating system. Also, a separate container was utilized as bubble storage connected to FBs generator. The water treatment was conducted in three different scenarios using air and pure oxygen as the FBs generator sources. The generated FBs were investigated in terms of their size and zeta potential concerning the dissolved oxygen (DO). The media’s DO was measured using the titration method and digital DO meter. The difference in DO concentration received from titration and DO meter define as potential reserved oxygen. Furthermore, the removal of synthetic effluent (ammonia, NH4Cl) and effluent in the media with FBs resources were investigated and tested at a different duration of FBs applications. The results showed that bubbles size was 518.5 – 607.6 nm independent of gas resource, either pure oxygen or air. However, the gas resources affected the zeta potential value of suspended bubbles, air (-11.5 to -16.7 mV), and pure oxygen (-21.4 to -25.2 mV). When pure oxygen was used as a gas resource, the media reach the oxygen supersaturation DO condition (25.39 ppm) within 45 minutes with reserve oxygen potential (ROP) of 2.95 ppm. Thus, this condition allowed the synthetic effluent removal of 83.33% and effluent removal of 39.93%. It is emphasized that the ammonia removal due to the presence of reactive oxygen species when the FBs collapsed and the information of ROP due to FBs application is important to preserve the fitness of aquaculture media for catfish larvae hatchery.

Effect of the Fe2O3 Addition Amount on Dephosphorization of Hot Metal with Low Basicity Slag by High-Temperature Laboratorial Experiments

In this paper, the influence of the Fe2O3 addition amount on the dephosphorization of hot metal at 1623 K with the slag of the low basicity (CaO/SiO2) of about 1.5 was investigated by using high-temperature laboratorial experiments. With increasing the Fe2O3 addition amount from 5 to 30 g, the contents of [C], [Si], [Mn] and [P] in the hot metal at the end of dephosphorization are decreased and the corresponding removal ratios increase. In dephosphorization slags, the phosphorus mainly exists in the form of the nCa2SiO4–Ca3(PO4)2 solid solution in the phosphorus-rich phase and the value of coefficient n decreases from 20 to 1. Furthermore, the oxygen potential and activity at the interface between the slag and hot metal are increased. When the oxygen potential and the oxygen activity at the interface are greater than 0.72 × 10−12 and 7.1 × 10−3, respectively, the dephosphorization ratio begins to increase rapidly. When the Fe2O3 addition amount is increased to 30 g, the ratio of the Fe2O3 addition amount to theoretical calculation consumption is around 175%, and the dephosphorization ratio reaches the highest value of 83.3%.

Reactions at the molten flux-weld pool interface in submerged arc welding

In submerged arc welding (SAW) of chromium (Cr) containing steels, Cr is usually added to the weld metal from the weld wire, and not from the welding flux. Manufacturing of weld wires of specific compositions is expensive and time consuming and cannot closely match all the desired alloy compositions. Therefore, the weld wire chemistry is usually over matched to the base plate composition. Better matching between the weld metal and base plate is possible if the weld metal incorporates Cr from Cr containing metal powder, instead of sourcing Cr from weld wire of limited Cr content. Because Cr is easily oxidised, the oxygen partial pressure in SAW must be controlled. This work illustrates the control of the oxygen potential at the molten flux-weld pool interface by using aluminium (Al) powder addition. The controlled oxygen potential at the molten flux-weld pool interface ensures increased Cr powder transfer into the weld pool, without interfering with oxygen transfer from the plasma arc to the weld pool. The objective of this work is to use targeted powder additions to better control Cr reactions in SAW to improve Cr metal transfer to the weld metal and maintain an acceptable level of oxygen in the weld metal.

Prediction of Formation Probability of Rare earth uranates inside nuclear reactor fuel from the determined oxygen potential using solid oxide Galvanic cell

The Pr6UO12(s) and Er6UO12(s) were synthesized by citrate nitrate gel combustion method. The synthesis conditions were optimized from the study of precursors of these uranates in the temperature range 973...