Use of local fuel-produced syngas for iron ore pelletizing

Iron ore pellets are important sources of iron for steel manufacturing. A high temperature process of induration finalizes pelletizing and typically consumes vast amounts of heat. While local resources can include iron ore, there can be a lack of local natural gas normally used for ore processing. A solution is use of abundant local fuel-produced syngas. We have performed this research based on mathematical modeling. A possibility of use of local coal-produced syngas for iron ore pelletizing has been proven what means creating a novel way for active and cost-efficient local ore pellet manufacturing. Gasification of induration machines does not require major equipment renovation. We have also analyzed major benefits and risks of this new technology.

Effect of the combustion system on reduction of thermal specific energy consumption in an industrial high temperature process

This paper presents an experimental study carried out in an industrial furnace for frits production using different configurations of burners based on different combustion techniques such as enriched air combustion, flat-flame oxy-combustion and preheater air combustion. The residence time of combustion gases inside the furnace also was modified. Several combustion configurations were tested and its effects on productivity and thermal energy specific consumption and efficiency were determined. The results show that higher residence time of the combustion gases can decrease significantly the specific consumption of fuel, while the change of the burners and combustion techniques did not show significant effects on decreasing the energy consumption. However, it is highlighted that the oxy-combustion flat-flame burners produced the lowest specific consumption of fuel. Even though the experiments were conducted in a furnace for frit production, the corresponding results can also be applied to guide or improve other industrial high temperature processes.

Fabrication of All-GaN Integrated MIS-HEMTs with High Threshold Voltage Stability Using Supercritical Technology

In this paper, a novel method to achieve all-GaN integrated MIS-HEMTs in a Si-CMOS platform by self-terminated and self-alignment process is reported. Furthermore, a process of repairing interface defects by supercritical technology is proposed to suppress the threshold voltage shift of all GaN integrated MIS-HEMTs. The threshold voltage characteristics of all-GaN integrated MIS-HEMTs are simulated and analyzed. We found that supercritical NH3 fluid has the characteristics of both liquid NH3 and gaseous NH3 simultaneously, i.e., high penetration and high solubility, which penetrate the packaging of MIS-HEMTs. In addition, NH2− produced via the auto coupling ionization of NH3 has strong nucleophilic ability, and is able to fill nitrogen vacancies near the GaN surface created by high temperature process. The fabricated device delivers a threshold voltage of 2.67 V. After supercritical fluid treatment, the threshold voltage shift is reduced from 0.67 V to 0.13 V. Our demonstration of the supercritical technology to repair defects of wide-bandgap family of semiconductors may bring about great changes in the field of device fabrication.

Facile and rapid fabrication of porous CuBr films by a solution oxidation and their application for the exclusive detection of NH3 at room temperature

Porous CuBr films are the most promising platform for the exclusive detection of NH3 but their simple and cost-effective fabrication without employing high-temperature process remains elusive. Herein, we report the...

Plasma Processing of Iron Ore

The depletion of high-grade ore minerals and the scarcity of fossil fuel reserves are challenging factors for metallurgical industries in the future. Also, extensive mining for increased steel demand results in the generation of fines often found unsuitable for use as direct feedstock for the production of metals and alloys. Apart from mines waste, the other major sources of fine minerals are leftover in charge burdens, sludges, and dust generated in the high-temperature process. Sludge and fines generated during beneficiation of ore add to this woe, as the outcomes of beneficiation plants for lean ores show better yield for fine particles. The utilization of lean ore and wastes in iron making requires wide research and adopting new advanced technologies for quality production with time-saving operations. The application of thermal plasma in mineral processing has several advantages that can overcome the current industrial metal extraction barriers. The present study demonstrates the thermal plasma for the processing of different iron-bearing minerals and its feasibility for metal extraction.

Desiliconization of leucoxene concentrate through the vacuum silicothermic reduction

A new approach to the processing of leucoxene concentrate through the vacuum silicothermic reduction of titanium and silicon oxides using technical silicon as a reducing agent is presented. It has been shown that the reactions occurring during the high-temperature process are accompanied by the formation of SiO gas resulting in desiliconization of the leucoxene concentrate. The highest desiliconization degree of 82 % was achieved when the content of silicon in the reactant mixture was 29 wt. %.

Formation of Ga double grading in submicron Cu(In,Ga)Se2 solar cells by pre-depositing a CuGaSe2 layer

By introducing a pre-deposited CuGaSe2 layer, a steep Ga back grading has been formed in a submicron CIGS layer with a high-temperature process for the first time.

PREPARATION AND CHARACTERIZATION OF CaZrO3COATING ON GRAPHITE FOR TiNi ALLOY MELTING

Graphite is a favorable melting material of TiNi alloy. In order to reduce the carbon increment during high temperature process, the protective CaZrO3 coating has been prepared using different methods. First, CaZrO3 powder was synthesized via solid-state reaction using calcium metal as raw material. The coating on graphite was prepared by flame spraying, plasma spraying and dipping sintering, then it was observed and characterized. The results show that the apparent quality of the obtained coating is intactness. Here, the spraying coating is composition uniform and structure compact; the dipping coating exhibits an obvious color change and presents the typical porous structure.