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By K. Robinson

Following the longest Smelter campaign in BCL?s history it was planned to completely rebuild the flash smelting furnace in 1987. This was the fourth major overhaul and the most extensive so far attempted. Detailed planning took place over several year$ preceding the shutdown and implementation was completed in 54 days. The key to minimising shutdown time was the method designed for installation of the new uptake shaft and reaction shaft. Major repair work was also undertaken in the waste heat boiler and electric furnaces. Both of these activities had an impact on the critical path of the flash smelting furnace overhaul.

Jan 1, 1993

Pyrometallmurgical reactors constitute a key processing component in the total primary and secondary resource cycle, being involved both in primary smelting, converting and extraction, as well as the reprocessing of scrap, from aluminum cans to end-of-life automobiles. To effectively control the overall resource cycle, one needs to take a systems modeling approach of the whole cycle, seeking to also understand the dynamic process behavior of the individual components of the cycle, and then especially the part that contributes most to the chemical conversion, namely the pyrometallurgical reactor. This paper highlights the role of pyrometallurgical thermodynamics, in the whole resource cycle and specifically places equilibrium thermochemistry in the context of process dynamics where large variable inventories are recycled or maintained within the system. This paper will therefore review the semi-empirical dynamic modeling tools, which are used to model complex systems with the specific goal of developing dynamic predictive models, which also include slag-alloy chemistry, towards controlling the recycling in a feed forward manner. To illustrate the primary processing side, high carbon ferrochrome will be presented as a brief case study. It also will show how the distributed nature of the chemistry of melts in the case of primary extraction, and secondary materials such as recycled end-of-life vehicles, have a significant impact on the process outcomes and model predictions. It is therefore argued that the fundamental thermodynamics and kinetics in metallurgical reactors playa final crucial role in modeling the closed material cycle, but only when it is used in conjunction with process systems theory based on reconciled data for parameter estimation and model calibration.

Jan 1, 2003

By Kenneth McGowan

"The aluminum industry is the 5th largest consumer of energy and the largest consumer of energy on a per-weight basis. Process heating accounts for 25% of the energy consumed to manufacture aluminum. Consequently, the generation of this energy results in the production of a significant amount of CO2 (over 3.75 million metric tons in 2003)1. As a result, the Aluminum Industry Technology Roadmap of 2003 listed the development of improved refractory materials as a goal to reduce energy use and decrease greenhouse gas creation. The result of a R&D effort addressing this desire is the development of patented microporous refractory materials for metal contact applications in all furnace areas including the belly band. It has been demonstrated that this material can reduce energy consumption up to 38% in furnaces and significantly reduce heat loss in launder and trough systems. Furthermore the material developed is non-wetting and remains un-penetrated by metal throughout its lifetime. The material does not contribute to the formation of corundum. As a result, the energy efficiency of an older lining remains intact compared to standard refractory materials which may have an initial high insulating value (such as lightweights and board) or standard dense refractory (even with penetration inhibitors) both of which show a rapid increase in thermal conductivity as the refractory is penetrated with aluminum and formed corundumIntroductionThe aluminum industry is the second largest producer of metal in the United States, behind the iron and steel industry. It is the 5th largest consumer of energy and the largest consumer of energy on a per-weight basis. Process heating is required to melt, hold, purify, alloy, and heat treat the metal and accounts for 25% of the energy consumed to manufacture aluminum. As such, process heating is the second largest energy consuming operation. Smelting, which utilizes an electrolytic reduction process is the largest energy consuming operation1.Most process heating is accomplished through the use of fossil fuels, either directly or indirectly. The choice of fuel is dependent on a plant’s location and fossil fuel availability. Table I shows the processes impacted by refractories and the calculated BTU’s generated by usage of the respective fuels as well as the Metric Tons (MT) of metal passed through each process in 20001."

Jan 1, 2009

By Tianzu Yang, Weifeng Liu, Lin Chen, Deyu Wang

"Due to the gradual exhaustion of easily extractive gold ores, it is vital to make efficient use of refractory gold ores which hold 30% gold storage of the world. However, the disadvantage of current processing technologies for refractory gold ores consists of severe pollution, low gold extraction ratio, high investment, etc, thus great research interests were attracted during recent years. This article provides an overview of the distribution and categories of the refractory gold ores in the world. The state of art in processing refractory gold ores by pyrometallurgy, hydrometallurgy and biometallurgy techniques and their industrial applications are highlighted. Potential environmental conservative techniques for efficient gold extraction are also reviewed.IntroductionResources of Refractory Gold OresAs easily extractive gold ores are going to be exhausted with the large scale mining nowadays, refractory gold ores are becoming more and more important. Gold in the refractory gold ore cannot be fully extracted using conventional method (cyanidation) even with fine grinding. The amount of gold in the refractory gold ores is about 1500~2000t in China, which occupies 30~40% of the total gold storage [1]. Therefore, it is vital to make efficient use of refractory gold ores."

Jan 1, 2013

By John R. Howell

"SUMMARYThe process of producing a new cast component requires significant design and development by both the design engineer and the foundry engineer. This effort strives to produce a high quality component at minimum cost. To assist in this development, an analysis system, consisting of several computer programs, has been developed to simulate the metal casting process. This system incorporates analytical geometric solid modeling, finite element analysis, results display, and an innovative technique to model the casting mold with surface boundary conditions.The simulation has produced excellent thermal results and work is in progress to develop techniques to enable use of this data in additional analyses to predict porosity and residual stress. Research is required to produce working parametric formulations of material properties. Software development is required to develop good fluid flow analyses for large. 3D models to simulate filling of and convection in molds.Integrating this system of programs is difficult due to proprietary database structures used by software developers. However, an acceptable means has been accomplished' to move data from one program to another. Further software development is required to facilitate this task. INTRODUCTIONThe process of producing a new cast component requires significant design and development by both the design and foundry engineer. This effort strives to produce a high quality, reliable component at minimum cost in a timely manner. The design engineer needs to know the physical and mechanical properites which can be expected in the actual part at critical areas. This will enable him to design a part with minimum material while fulfilling the performance required. The foundry engineer needs to produce a sound, quality casting with a minimal amount of material In risers, the feeding system and machining stock. This must be done with a minimum· investment in tooling and development time and maximum productivity of labor and capital employed. This task Is continually being made more difficult because of increased competition in the marketplace and the use of castings in more severe service. This has strongly influenced the need for high quality castings.The task of developing a new casting is difficult for both the design and foundry engineer. To assist in this development, Deere & Company has been engaged in the development of an analysis system to simulate material processes. A major portion of this program involves simulation of the metal casting process. This analysis system has evolved into a package of computer programs which simulates casting solidification and subsequent cooling through the finite element method"

Jan 1, 1986

By Cynthia K. Belt

Improved energy efficiency has grown in importance within industry as energy costs have escalated. The analysis of trends and changes to a process is critical in making the best business decision in energy management. Frequently, energy use per day (Kilowatt-Hour or British Thermal Units) is used to track energy efficiency. Sometimes, the somewhat more complex method of energy per processed weight (Kilowatt-Hour per Metric Ton or BTU per Pound) is used to make this evaluation. Yet both methods ignore the effects due to throughput and weather. In this paper, different thermal processes and systems will be evaluated using statistical methods to highlight alternative methods to evaluate energy efficiency. Examples and potential problems will be discussed for both a single process and a collection of processes within a plant or corporation.

Jan 1, 2008

By John L. Sundstrom

Complete systems were designed -and are in operation to recycle the effluent streams and to remove impurities from tankhouse. electrolyte, Heavy em¬phasis was placed on making usable products from as many streams as poss¬ible at minimum capital and operating costs. Almost complete recycling: and reuse of water and sulfuric acid were paramount. Techniques used in-clude solvent extraction - electrowinning, evaporation - crystallization and filtration.

Jan 1, 1992

By C. Dupuis

Thiourea is a promising reagent for gold extraction especially from refractory ores that cannot be treated by traditional cyanidation route. In this study recovery of gold from thiourea leaching solutions was investigated by direct electrowinning. The electrolysis cell consisted of a carbon flow-through cathode and a lead anode. The anodic and cathodic compartments were separated by a membrane. Galvanostatic mode was chosen for operation of the cell. Factors affecting recovery efficiency such as cathode thickness, linear flowrate, current intensity, thiourea and gold concentrations were investigated. The influence of some species in solution on efficiency and selectivity of recovery was investigated. Gold recovery reached 99% but current efficiency was lower than 10%. The complex formed with ferric ion and formamidine disulfide are reduced before gold-thiourea complex. Thiourea consumption occurred during leaching mainly by oxidation and reaction with dissolved copper.

Jan 1, 1989

By C. M. Antony

The galvanizing process involves the use of accessory equipment in a series of aggressive environments including zinc ammonium chloride flux, molten zinc at 45S°C (850°F), and acid for stripping of adherent zinc. An Fe-Ni-Cr-Co alloy has been identified which combines excellent strength and resistance to molten zinc and acid attack making it suitable for accessory equipment. The alloy was field tested by a commercial galvanizer as basket material and was found to provide improved life compared to original low-alloy steel baskets while cross-section thickness was reduced 44%. Additionally, other associated processing cost savings were realized.

Jan 1, 1992

By Norihiko Fukatsu, Takashi Iwamoto, Noriaki Kurita, Koji Katahira, Kunihiro Koide, Teruo Ohashi

"The galvanic cell-type hydrogen sensor employing CaZro.9Ino.t03-a. as the solid electrolyte was designed for the measurement of hydrogen activities in molten copper under industrial .conditions. The sensor probe consists of the cap-shaped solid electrolyte with porous platinum electrode on the inside and alumina refractory tube. The gas mixture of the composition 4%H2-0.5%02-Ar was made to flow on the inside electrode. The hydrogen sensor probe was inserted directly into molten copper and the melt was used as the outer electrode. The effect of oxygen activity gradient to EMF was eliminated theoretically by measuring the oxygen activity in the melt simultaneously with an oxygen sensor. The high stability of output and excellent response to the change of hydrogen activity were obtained over the wide range of industrial copper melting conditions.IntroductionIn the metal casting process, hydrogen easily dissolves in molten metals from water vapor in the surrounding atmosphere. Owing to the large difference in hydrogen solubility between liquid and solid metal, dissolved hydrogen becomes a cause of the defects of blowholes in castings or ingots. It is necessary to control the hydrogen content in the molten metals [l]. Using proton-conducting ceramics as a solid electrolyte, high temperature-type hydrogen sensor can be constructed [2]. SrCe03- and BaCe03-based perovskite-type oxides exhibit appreciable proton conduction under hydrogen containing atmosphere at high temperature [3-5]. A hydrogen sensor for molten aluminum using CaZro.91no.103-a. has been developed and widely used in the ·process control in the aluminum melting industry [6,7]. The same type of hydrogen sensor has also been expected in the copper melting industry. .. However, CaZro.91no.103-a shows ·not only proton but also oxide ion conduction in the high temperature and at low oxygen activies like the copper melting· conditions. Then we studied the oxide ion conduction in CaZro.91no.103-a. iit · detail [8]. From the consideration on the EMF of the galvanic cell employing this material as electrolyte, it was shown that the unknown hydrogen activity may be precisely determined from cell potential which is corrected for the effect of oxygen potential gradient And the hydrogen sensor based in this principle was constructed and tested in laboratory-scale [9,10]. We repeated the similar tests in factory-scale and developed the sensor system for practical uses [11, 12]. In this report, the structure and system of the hydrogen sensor for molten copper will be introduced first. The reliability of the sensor will then be demonstrated from the results of experiments for sensor probes carried out in TYK's laboratory."

Jan 1, 2000

By Lloyd R. Nelson

Experimental results of three-phase mixing in a physical model of a CCRL for metals refining are presented. The system was operated above a critical lower liquid height-to- width ratio (H,/W) of unity, with adequate bottom gas injection through a line of central, single tuyeres (Q,/A = 7.5 cm/min, or c = 17 W/m3) to sustain levels of interphase transport considered appropriate to an industrial pyrometallurgical refining operation. The application of a thermal tracer technique to elucidate both longitudinal mixing and interphase heat transfer is discussed. The results indicate that even under conditions of significant bottom gas injection, it should be possible to maintain acceptably low longitudinal mixing 1 (D, < 20 cm /s and D,/uL < 0.1) in the CCRL. Interphase mass transfer coefficients of the order of 0.004 cm/s are predicted from the measured interphase heat transfer coefficients (h = 1.3 to 2.0 kW/m2K), using the heat and mass transfer analogy. Adequate rates of rehning are predicted for an industrial CCRL operated under such conditions.

Jan 1, 1995

By Shengli Wu, Yuandong Pei, Zhixing Zhao, Shuhai Ou, Jiangshan Shi, Huaiying Ma, Jun Xiong

Spraying technology on sintering surface bed after ignition has become a hot research topic, with the purpose of achieving energy-saving, emission reduction and improvement of sintering indexes. In this paper spraying steam technology was researched from theory, experiment and practice. First of all, from the thermody- namic and kinetic analysis, the mechanism of sintering surface spraying steam was analyzed and its advantageous effect was con firmed. Based on this, sintering pot test and commercial trial were carried out respectively. The results shown that spraying steam is bene ficial for increasing coke combustion ef ficiency with improving CO 2/(CO+CO2) in the exhaust gas from 80% to about 85% level, through decreasing CO content of flue gas by more than 1000 –2000 ppm. There was a suitable spraying amount to improve the quality of the sinter, and the spraying position of the steam cannot be excessively front and rear. Due to the low steam pressure (1 kg) and temperature (about 100 °C) compared with industrial steam (3 kg and 130 °C, respectively), the sinter quality such as yield index was affected by spraying steam in sintering pot test to a certain extent, and proper spraying amount (0.008 m 3, 50 kg sinter) in sinter pot test is far smaller than application amount in commercial trial (2t/h). It is thought that suitable spraying steam parameters has a comprehensive effect of energy saving and quality improvement.

Mar 1, 2018

By F. D. S. Marquis

An investigation of the mechanisms of formation of two types of porosity-primary and secondary-their characterization, evolution during processing, and effects on the mechanical behavior (fracture, fatigue, and failure) of 7X50 and 2X24 alloys has been conducted. The mechanisms of formation of three forms of primary or cast porosity were investigated, and each form was characterized: (a) macroscopic shrinkage porosity-MSP); (b) microscopic interdendritic porosity (MIP); and (c) hydrogen gas porosity (HGP) or primary hydrogen porosity (PHP). The mechanisms of formation of four forms of secondary or thermal/thermomechanical porosity were investigated, and each form of porosity was characterized: (a) high temperature oxidation (HTO). internal hydrogen precipitation (IHP), or secondary hydrogen precipitation (SHP); (b) preheating blistering porosity (PBP); (c) eutectic melting porosity (EMP);and, (d) dissolution micro void formation (DMF). The evolution and interactions of the primary and secondary types of porosity (w.ith special emphasis on PHP and SHP) during industrial and laboratory processing and their effects on the fracture and failure behavior of both types of alloys (with special focus on fatigue crack initiation and propagation) were investigated.

Jan 1, 1996

By John W. Graydon

Incineration is an attractive alternative to the disposal of MSW in landfill sites. However, the process of incineration generates fly ash which contains significant levels of leachable heavy metals - particularly cadmium, lead, and zinc - and it is essential to manage this fly ash in an environmentally sound manner. The compositions, phases, textures, morphologies and size of fly ash particles have been studied by light microscopy, scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. The detailed spatial relationships and speciation of the environmentally significant constituents have received particular emphasis. The information obtained is useful in understanding how fly ash is formed during incineration, in understanding the leaching behavior of untreated fly ash if it is disposed of in a landfill and, most importantly, in guiding the development of the best treatment strategies for fly asti to mitigate its environmental impact.

Jan 1, 1992

By J. Tang, B. Q. Li, R. Akarapu

"An integrated model is developed to represent the three-dimensional electromagnetic wave propagation and thermal phenomena during microwave heating of ceramics and dielectric/biological materials. The model development is based on the edge finite element formulation for electromagnetic fields and the node fmite element formulation for thermal phenomena. Results are presented and compared well with available analytical solutions and experimental measurements. With the model, the effect of sample positions on the electromagnetic and thermal field distributions is studied.IntroductionMicrowave, as an electro-heating source, has been widely used in the processing industries for packaged foods and other materials. The commonly used household microwave oven is a typical example of microwave heating processes. Other industrial microwave processing systems include large-scale microwave guides and cavities, which are used for the sintering operations as required for making ceramic components or for sterilizing the packaged foods."

Jan 1, 2004

By W. G. Davenport

This chapter shows how flash furnace industrial oxygen and oil requirements are affected by different: (a) product temperatures (b) conductive, convective and radiative heat losses (c) electrical energy inputs (d) hydrocarbon fuels. The calculations of the chapter are all for production of 65% Cu matte from pure CuFeS2 concentrate. Blast temperature is? 298 K throughout.

Jan 1, 2001

Gas flow and heat transfer phenomena in two industrial-scale waste-heat boilers of the Outokumpu copper flash smelting process were analyzed with a commercial computational fluid-dynamics (CFD) package Phoenics. Various operating conditions were simulated for the first boiler and particularly for the second boiler. The gas flow pattern was compared qualitatively with the physical laboratory models, and the general flow pattern was consistent with the laboratory visualization. The heat transfer simulation was validated with, temperature measurements for both boilers, and good agreement was reached between the computed temperature profiles and the measured data. The computational results indicate that gas flow in both boilers is of three-dimensional and recirculating nature. The numerical tracer experiments indicate that some dead volume is present in both boilers, and the boiler modification reduced the dead volume from 38% to 15% under basic operating conditions. Radiative heat transfer accounts for 65-90% of the total &apos;heat transported in the radiation sections of both boilers under different operating conditions. The modified boiler is very efficient for cooling the off-gases at almost doubled volume flow rate. The CFD modeling proved to be a useful tool for numerical experiments and analysis of boiler performance for process: optimization.

Jan 1, 1998

By George Nekoksa

The biofilm activity monitoring probes measure applied current during intermittent short-term polarization of the probe electrodes and current or potential between the electrodes after removal of the polarization. The probe polarization mimics conditions at crevices, welds and inclusions where the biofilm activity and microbially influenced corrosion usually concentrate. Monitoring of AC resistance between the probe electrodes can provide infornation about the thickness of deposits.

Jan 1, 1994

By H. Eccles

BNFL, an internationally acclaimed company noted for its nuclear fuel cycle services and waste management technologies, collaborated with Viridian BioProcessing Ltd, a small company acknowledged for developing environmental biological processes, and an internationally recognised professor of biological sciences, to develop an unique bioremediation process for treating toxic, heavy metal contaminated land. This paper describes the process, with particular reference to the problem and scope of land contamination with toxic, heavy metals and the current available technologies. The process technologies are based on using indigenous, soil micro-organisms which can be stimulated to produce acid or sulphide ions to mobilise or precipitate the heavy metals respectively. Laboratory studies have indicated metal removal efficiencies of greater than 90 % can be achieved, whilst recovery efficiencies from the metal loaded leachate are even higher at approximately 95%.

Jan 1, 1996

By Run-sheng xu, Hai-yang WANG, Di ZHAO, Teng-fei SONG, Jian-Liang Zhang

This paper was mainly focused on the different semi-cokes and charcoal which could be new fuels for blast furnace injection. Through the comparative study with bituminous coal and anthracite coal, the properties of semi-cokes and charcoal were presented in this research. 10 indexes of different fuels were obtained by different standard experiment, including proximate analysis, ultimate analysis, igniting point, explosivity, transportation characteristic, ash properties, grindability, calorific value, combustibility and reactivity with CO2. According to the data analysis, it provided a theoretical basis for rational utilization of various blast furnace fuels, and helped to broaden the scope of the blast furnace injection fuels. This research could contribute to energy conservation, emissions reduction, and sustainable development of iron and steel enterprises.

Jan 1, 2015