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By Huang Rui

The coal asphalt is combusted at different temperature in a heating cabinet with the temperature limit by 1200°C. By comparing the mass of the remainder of each experiment, the completely combusting temperature of asphalt smoke can be determined. Based on the experimental process of asphalt smoke, a discrete mathematical model of the asphalt smoke combustion is set by theoretic analysis. Through computer programming, the dynamic combustion process of asphalt smoke is calculated to simulate the experimental model. The result of experiment shows that coal asphalt can mostly react upon 500°C and the mass of remainder is 49.41% to initial mass of sample in the condition. The computing result shows that the temperature and the concentration of asphalt smoke influence its burning temperature approximating linearity. The consumed quantity of fuel to ignite the asphalt smoke needs be considered with the two factors.

Jan 1, 2006

By Sunil Jayasekera

This paper describes the results of a study carried out to examine the feasibility of electrolytic recovery of silver from cyanide leach liquor generated from a Western Australian silver mine tailings using a novel high mass transfer electrowinning cell. The proposed circuit involves heap leaching and electrowinning in a closed loop. The filter-press-like closed electrode arrangement of the cell allowed much improved mass transfer of metal ions to the cathode surface, making direct electrowinning of metals from dilute solutions feasible. The tests were conducted both in the laboratory and at large scale using a prototype with ~1.0 m2 cathode area. The results showed that the recovery of silver from as low as 250 mg L-1tenor was feasible. The silver deposit produced with the prototype cell was non-adherent and powdery and could be readily removed from the closed cell. A system was developed so that silver powder was discharged continuously during the run.

Jan 1, 2003

By I. Sofia Fernandez del Rio

This paper describes a process for the treatment of the dusts generated during the operation of blast and reverberatory furnaces in the lead smelter, to remove zinc, cadmium, arsenic and halides from the circuit. The process consists of a Pefloles' developed leaching/purification stage and a solvent extraction process developed by Lurgi. The plant capacity is 5,000 tonnes Zn/year. The feed to solvent extraction contains 8 g/1 Zn. Impurities such as copper, iron, arsenic and cadmium are removed by conventional cementation processes. The cadmium product is 99.99 % pure. The solvent extraction process consists of two extraction stages, one washing stage and two stripping stages. D2EHPA is used as the extraction agent and 25% ammonia as the neutralizer. The rich-zinc solution is sent to the electrolytic zinc plant for zinc recovery. The raffinate produced, which is a mixture of ammonium sulfate and chloride, is used for agricultural applications.

Jan 1, 2000

By E. Morrice

Solubility of yttrium oxide (Y203) in fluoride melts was experimentally measured in the temperature range of 998 to 1273 K and, YF3 composition in LiF.YF3 melts varying from 20 to 50 mole pct using a graphite crucible in an argon atmosphere. Solubility of oxide in the melt was found to increase with increasing temperature and YF3 composition in the melt. An expression for in XY2O3 as a function of temperature for several melts was deduced. The calculated activity coefficients of Y2O3 in the melts exhibited a negative deviation from Raoult's law.

Jan 1, 1989

By J. Tang

The major problem with the Nd-Fe-B magnet is its low operating temperature, i.e., the coercivity decreases so rapidly with increasing temperature that the practical maximum operating temperature-is only 100 °C. Meanwhile, it has been reported that nitrogen addition can drastically increase the Curie temperature of both R2Fe17 and RTiFe11 (R = rare earths). A reasonable question is, then, can one see a similar effect in Nd-Fe-B system? Experiments have been conducted to examine how magnetic properties of Nd-Fe-B magnet are affected by the nitrogen addition. Our results show that part of Nd2Fe14B maintains its original crystal structure and no substantial change in To, due to such N2 treatment is found. However, part of the sample decomposes into a-Fe and, possibly, Nd nitride as a result of nitrogen treatment.

Jan 1, 1992

By Mark W. Sajewycz

Creating technology, securing patent rights, and managing a patent portfolio are time-sensitive and dynamic activities. Agreements should be in place with technology partners (employees, contractors, joint venture partners), prior to embarking on research and development projects, so as to mitigate future disputes over patent rights. Technology partners should be educated on patent law basics so as to be mindful of patent bar triggering events. Accurate records must be maintained to capture information relevant for preparation and filing of patent application, including subject matter, names of inventors, and invention date. Developed inventions should be evaluated for whether to file for patent protection, delay patenting until technology is further developed, maintain trade secrecy, or effect deliberate public disclosure. Once decision is made to file for patent protection, time is of the essence, and application for patent protection should be filed as soon as possible, as many countries award patents on a "first-to file" basis. Decisions on where to file are made having regard to potential competitive advantages versus cost considerations, and can be delayed by taking advantage of priority rights recognized in patent legislation of most countries. Once patents are granted, competitors must be policed for potential patent infringement, and legal action may be necessary to prevent patent infringement.

Jan 1, 2006

By Neil Smith

Mineral processing plants typically procure a range of industrial services from contractors. Their satisfaction and value received is directly affected by how the services are procured, rationalized and delivered. Conventional purchasing strategies often focus on price rather than on optimizing the service relationship between supplier and customer. The nature of this relationship may have the greatest potential to reduce costs and enhance production. It has been documented that a service involves simultaneous production and consumption. A high degree of customer involvement is often necessary for a successful outcome and the expectations and attitudes of the customer can positively or negatively affect delivery of the service. This indicates that the customer can enhance or diminish their own satisfaction and value received and the supplier cannot act alone for best results. The Optimax? Program for industrial services is a service delivery framework whereby a customer and supplier work together to raise the efficiency of the service exchange. The Optimax? Program is intended to help the customer optimize costs and maximize production by connecting the customer and supplier through shared information and objectives. This paper will review the basic nature of services, provide a couple of examples of conventional procurement strategies for services and outline the features of the Optimax? Program. A Case Study showing recent results from implementing the Optimax? Program will be included.

Jan 1, 2006

By G. St-Amant, V. Cloutier, E. Ghali, S. Jin, G. Houlachi

During the casting of lead-silver anodes, variations in cooling rates result in the formation of an uneven microstructure. The slowly cooled areas (SCA) have a coarser microstructure than that of the remaining part (called "the general zone"). The effect of anode microstructure on the electrochemical behavior was investigated using galvanostatic, potentiodynamic and electrochemical impedance techniques. The results show that the resistances for the two steps of the oxygen evolution reaction on the slowly cooled areas of Pb- Ag anodes are higher than that on the general zone. The double layer capacitance for the first step of the oxygen evolution reaction (OER) and the pseudocapacitance of the second step of OER on SCA are smaller than those on the general zone. The potentiodynamic results show that the amount of lead dioxide formed on the SCA is greater than that of the general zone of the anode. The potential decay curves after 30 minutes of galvanostatic polarization at 45 mA/cm2 show that the corrosion potential of the SCA is 200 mV lower than that of the general zone. This can lead to perforation because of the formation of a galvanic cell with a small anode and a large cathode.

Jan 1, 2000

By Jin Liu

In the early 1990?s, Inco successfully installed two new flash furnaces as part of their SO2abatement project to reduce SO2 emissions from the Copper Cliff Smelter by 60%. The flash furnace off-gas is cooled and cleaned through two new Monsanto Dynawave gas cleaning systems that replaced the traditional venturi scrubbing system. It was discovered that the flash furnace production capacity is often limited by the capacity of the gas cleaning system. The key task is to eliminate pressure drop from the system. The froth column is responsible for by far the largest pressure drop in the gas cleaning system. Initially, the column was fitted with 22 plates. In 1994, both #1 and #2 froth columns were modified by reducing the number of plates in each column from 22 to 18 and increasing the interplate spacing on lower plates. With increasing demand for more throughput in the flash furnaces, further modifications on the froth columns were made in 2005. This paper describes these modifications and results together with some fundamental analysis of the froth column characteristics.

Jan 1, 2006

By Daojin Cao

The chemical components in the saturated aqueous solution of ammonium dimolybdate (ADM) were investigated at room temperature by comparative Raman spectroscopy. In order to explore the further detailed results, a new method of qualitative and half quantitative analyses, based on the main vibrant frequencies and the intensity ratio of the strongest peak to the second strongest peak recorded in Raman spectrum of saturated aqueous solution of ammonium heptamolybdate tetra hydrate (AHM), was put forward and attempted to analyze the chemical components of saturated aqueous solution of ADM. The results showed that there was obvious difference between Raman spectrum of saturated aqueous solution of ADM and that of ADM, but there were good relationships between Raman spectrum of saturated aqueous solution of ADM and Raman spectra of the three samples including AHM, the saturated aqueous solution of AHM and monomolybdate ion in aqueous solution. It was found that aggregated dimolybdate ion ({Mo2O72-}n)did not exist in the saturated aqueous solution, and was changed into heptamolybdate ion (Mo7O246-) and monomolybdate ion (MoO42-), which were in equilibrium each other, but the distribution ratio of heptamolybdate ion was larger than that of monomolybdate ion. In addition, Raman spectral pattern of saturated aqueous solution of ADM was reported.

Jan 1, 2006

By Manuel Pérez-Tello

A mathematical model to represent the expansion and fragmentation of copper matte particles oxidized under flash converting conditions is presented. The model assumes the particles to be initially nonporous, have a constant mass prior to fragmentation, and travel at a constant velocity throughout the reaction chamber. The model requires the specification of five parameters: the particle expansion rate, a fragmentation diameter factor, a fragmentation size distribution parameter, and the fractions of the finest and the coarsest particles in the feed that undergo fragmentation. The model predictions show good agreement with experimental data collected in a laboratory flash converting furnace over a wide range of experimental conditions. The evolution of the size distribution of the particles along the reactor length was computed, and the model parameters were correlated with the experimental operating variables. Model predictions indicate that particle residence time is an important factor in the generation of dust. The presence of two maxima in the particle density function may be attributed to turbulent conditions prevailing in the furnace, which cause particles to follow very different trajectories within the furnace even if they are injected at the same location.

Jan 1, 2006

By Boris Arlyuk

The system of short term forecast of metal prices at LME is based on correlation between prices within the quarter forward and at the first place by economic parameters at the West, determining the consumption of metals. Such economic parameters are presented by data of indexes of Western World industrial production (WW IP), official data of IP and Dow Jones indexes at USA. For price forecast within the quarter forward (one day ahead, 3 day -65 days MA forward prices) are significant the changes of actual prices (official and close) at the past and the parameters of daily trade at LME at the past (futures turnover, open interest, LME stocks). It is developed subsystem of price forecast within the quarter forward based on analytical approach determining the relations between the participants of the market. It gives the opportunity to reduce the number of empirical coefficients at the model and receive good accuracy of forecast the MA prices and its direction at the future. Very important part of short term forecast is subsystem determining analytically the probability that the price forecasted for the next trading day will be the maximum or minimum daily price within the quarter forward. The thresholds probabilities are defined by identification the model at the past by maximal commercial efficiency. Such system was tested at the past at period since 2000 till 2005 and gives very high commercial results at operations on 1M forwards and hedging the sales of nonferrous metals traded at LME (primary aluminium, light alloys, nickel, copper, zinc, lead and tin).

Jan 1, 2006

By Bruno Lebon, Koulis Pericleous, Georgi Djambazov, Mayur Patel

"High speed compressible jets are used in a number of steel-making applications. In the case of the BOF, a compressible oxygen jet reacts with a carbon-rich iron bath to reduce carbon levels and produce steel. The intensity of the process is governed by the speed of the jet and by the size and shape of the depression created in the metal and slag by the force of the jet, i.e. by the corresponding free surface. This is a difficult CFD problem, since there are compressible and incompressible regions in the flow domain, which need to be handled differently in a finite-volume (FV) pressure-correction scheme. Also, standard turbulence models do not account for compressibility, or the large difference in density between the cold oxygen jet and the hot reacting surroundings. Corrections are introduced to the k-E model to remedy this deficiency and the results are validated against experimental data. The compressible/incompressible boundary is handled through a transition region, based on Mach number.IntroductionThe deformation of a free surface by a compressible high speed jet is of paramount engineering interest, particularly for understanding the physical processes within a Basic Oxygen Furnace (BOF). In a BOF, a supersonic oxygen jet impinges on a molten iron surface, thereby creating a cavity. Oxygen penetrates the bath and removes carbon, resulting in low carbon steel [1].The challenges in modelling such a process lie in coupling a solution domain with distinct compressible and incompressible regions and in dealing with large density differences between the modelled gas and liquid. The modelling of compressibility within the jet is crucial, since the correct velocity profile in the jet is required to determine the cavity depth with accuracy."

Jan 1, 2012

By Biserka Lucheva, Tzonio Tzonev

"A unique DC electric arc rotary furnace with capacity 150 kg has been designed and constructed for the recycling of low-quality scrap and aluminum dross. The main constructive feature of this furnace is that the axially positioned graphite electrodes (cathode and anode) are placed 100 mm away from the rotation axis of the furnace. A specific characteristic of the construction is the possibility one of the electrodes (the anode) apart from moving axially (parallel to the furnace axis) to move at 90° outside the working space. High recovery rate of metal aluminum from aluminum dross (92%) was realized in this furnace. This is the reason for construction of industrial DC electric arc furnace.IntroductionThe consumption of aluminum waste has been rising continuously on a world scale, which is a great stimulus for the development of the technology for aluminum recycling.To recover the aluminum in dross, the conventional recycling process uses salt rotary furnaces heated with a fuel or a gas burner. This treatment process produces a secondary dross containing alumina, salts, impurities and a small amount of aluminum. Molten aluminum is tapped from the furnace and the residue is then dumped from the furnace. It has been the practice to dispose the residue in a landfill. Improvement of this technology, known as the oxy-fuel process, uses a gas burner enriched with oxygen to increase the thermal efficiency [1]. Recent studies show that the most efficient aggregate for recycling of aluminum scrap has turned out to be the rotary tilting furnaces, heated by plasma or electric arc, for which the use of flux is not necessary [2,3].Accordingly, there is a substantial need in the industry for an improved process for recovering free aluminium. It is particularly desirable that such process be cost effective and ecologically safe."

Jan 1, 2008

By Georgeta Rata, Cornelia Petroman, Ioan Petroman

"Proper training and education in the field of recycling and waste treatment are inconceivable without the proper teaching of the terminology specific to both recycling (aerospace products recycling, automotive recycling, general recycling, recycling behaviour, recycling schemes, recycling systems, and waste recycling) and waste (characterization of waste, electronic waste, heavy-metal containing waste, monitoring of waste, radioactive waste, solid waste, waste collection, waste conversion, waste recycling, waste reutilization, waste stabilization, waste storage, and waste treatment) in both the students’ mother tongue and in English for Special Purposes (ESP) as a second language (with focus on the structuring of the specific terminology). Including linguistic approaches among the possible approaches of environmental protection and material sustainability means including linguistics among the various disciplines addressing energy supply, cement and building materials, metallurgy, chemistry, glassware, pulp and paper industry, machinery, automobile and electronic industries, collection, and sorting, further treatment and final disposal of post-consumer material.IntroductionCultural and technical changes have produced more novel artefacts than novel activities or novel properties, generating new vocabulary needs that are readily answered by new words (nouns).The purpose of this research is to show that ‘waste words’ – phrasal words (items that have the internal structure of phrases but function syntactically as words, e.g., cattle waste) and particularly compound nouns (words formed by combining roots, that tend to have a meaning that is more or less idiosyncratic or unpredictable, e.g., wastepaper ‘discarded paper’) – used in the study of the English of recycling, waste treatment, and clean technologies can be misleading for both native and non-native students and/or users of English because their structure alone does not allow instant, proper understanding of their meaning.Our hypothesis is that this inconvenient can be overcome by getting to reach the proper meaning of these new words. Or, arriving at the precise meanings of the ‘waste words’ depends on our knowledge of the world (for example, wastepaper indicates that some used paper is discarded and not wasted) rather than on purely linguistic knowledge."

Jan 1, 2008

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Yang Tian-zu

Sodium pyroantimonate which is widely used as the clarifier in the glass industry and as the synergist in anti-flaming industry respectively has a production history of about 30 years in China. At present there is the production capacity of about 20,000 tons per year in China and China is chief producer of sodium pyroantimonate. In this work the production processes adopted by the producers of China, the operation conditions and the product qualities of sodium pyroantimonate prepared by different preparation methods have been summarized, and on the basis of comparing the advantages and disadvantages for each process the most advanced method - the air-oxidation method was introduced in detail. The production processes of sodium pyroantimonate mainly include the method of oxidation by sodium nitrate, the oxidation method of hydrogen peroxide, the potash salt method, the chlorination method and the air-oxidation method etc. The method of oxidation by sodium nitrate in which the crude antimony oxide, sodium carbonate and sodium nitrate are separately used as the raw material, the flux agent and the oxidant, has the advantage of short and simple technological process, but low grade quality of sodium pyroantimonate and bringing about serious environmental pollution are the disadvantages and this method has been substituted by other methods. Sodium pyroantimonate can be directly prepared by the hydrogen peroxide oxidation method with the advantages of simple technological process, high grade quality of the product and little environmental pollution. High grade quality of sodium pyroantimonate can be also synthesized by the potash salt method, in which industrial antimony white, the hydrogen peroxide, potassium hydroxide and sodium hydroxide are applied as the starting material. The disadvantages of these two preparation methods are high production cost and high requirements on the raw materials. The chlorination method with the crude antimony oxide, hydrochloric acid and chlorine as the raw material has the advantages of low production cost and high grade quality of the product. However complex process, high requirement of anti-corrosion for the equipments and producing plenty of waste water limit its application. The air-oxidation method with stibnite/jamesonite concentrate, sodium sulfide, and sodium hydroxide as the raw material and atmosphere as the oxidant is a newly developed method and its advantages are low production cost and the complex raw material can be treated by this method and its disadvantage is that the quality of sodium pyroantimonate is lower than that prepared by the oxidation method of hydrogen peroxide and the potash salt method.

Jan 1, 2006

By C. P. Broadbent

Due to growing .public awareness of environmental issues and greater sensitivity towards waste management, many countries around the world are implementing more stringent legislation governing the storage and disposal of hazardous wastes containing heavy metals such as As, Sb, Pb, Cd or Hg. These wastes can no longer be dumped without providing clear guarantees that the material concerned is environmentally safe and will not leach toxic elements to the surroundings. In the Netherlands the current dumping charge for chemical waste (i.e. worst category) is $280/t, and for industrial waste this cost reduces to $75/t. If the material can be reused there may be a small positive credit for selling it, for example discard slag as an aggregate to the construction industry. A number of (pyre)-metallurgical operations, mostly associated with the extraction of metals from sulphidic ores, produce arsenic residues in the form of As2O3 containing flue dusts and speises. If the flue dust is of high purity it can be sold, though many traditional uses are being substituted by other materials. In many cases upgrading the quality of the arsenical dusts is not possible for either technical or economic reasons. Traditional practice is to dissolve these dusts in acid prior to precipitation as ferric arsenate, which is at present classified by many countries as industrial waste and can be dumped. Recent work, however, has cast doubt on the stability of arsenates for disposal and alternative disposal routes have been investigated. Tests have shown that up to 10% (dm) As can be incorporated into "glassy" silicate slags with very low levels of arsenic leaching in the cooled product. Calcium arsenate was added to a range of synthetic and industrial slags from the system SiO2-FexOy-CaO-A12O3-AsmOn, under mildly oxidising conditions and quenched subsequently in water. It would appear that this represents an environmentally acceptable method for the disposal of many arsenical residues and there is some optimism that this method will be equally applicable to the disposal of other toxic metal residues.

Jan 1, 1994

By M. E. Reed

Clyde Materials Handling (CMH) and WorleyParsons have developed a concept for a flash furnace feed system using the specialist pneumatic conveying equipment expertise of CMH and the flash furnace process experience of WorleyParsons. CMH has developed a proprietary volumetric feeder (called a Rotofeed) which is extremely accurate and overcomes many of the problems inherent with loss-in-weight screw feeders and drag chain conveyors, previously regarded as state-of-the-art. Initial indications are that the Clyde-WorleyParsons Feed System could deliver the following benefits to Flash Furnace operation: ? Accurate pulse-less delivery of feed material to the head of the burner leading to improved combustion performance and process stability; ? Highly accurate split to the individual quadrants of a conventional burner tube, or provision of a smooth hollow curtain to a burner without guide vanes; ? Decreased pressure pulsation in the furnace due to improved combustion control and performance; ? Decreased temperature fluctuations in the furnace due to improved combustion characteristics and hence reductions in refractory thermal stress and wear; Plant measurements have indicated a correlation between the discharge of concentrate from the drag chain conveyor and high speed pressure fluctuations in the flash furnace settler. Pilot scale test have been conducted to illustrate that the system delivers pulse-less feed to the burner with even feed distribution axially.

Jan 1, 2006

By Andreas Nolte

In 1999 HÜTTENWERKE KAYSER AG (HK) in Germany will produce more than 180,000 t/y of electrolytic refined copper. To achieve this production from materials with copper grades from two to seventy percent and diverse copper alloys, HK operates three blast furnaces, one holding furnace two Peirce Smith converters and two anode furnaces. Technical, metallurgical and economic factors for the ongoing process optimization are outlined. The fluctuating quality and quantity of raw materials renders complex this optimization. The principal variables are the quality and quantity of process consumables: coke, copper-iron, limestone, oxygen, as well as the blending of feedstock and a new organization of the operating crews. The search for new metallurgical process parameters is ongoing. HK started with an intensive research programm in November 1997. As a result it will be possible to cut processing costs by about ten per cent, to increase the blast furnace capacity by ten per cent and to lower the metallurgical losses of copper and tin in the slag by more than ten percent. The presentation concludes with information on future steps to continue the optimization process.

Jan 1, 1999