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By Walter Curlook

An atmospheric acid leaching process for leaching nickel and cobalt from highly-serpentinized saprolitic fractions of nickel laterite deposits has been developed and patented [I]. The process involves leaching the highly-serpentinized saprolitic portion of the nickel laterite ore profile in strong sulphuric acid solutions at atmospheric pressure and temperatures between 80°C and 100°C, essentially autogenously, to extract over 85% of its contained nickel content and a large proportion of its cobalt content after leaching times of about one hour. The amount of sulphuric acid used in the leaching process is between 80% and 100% by weight of the finely ground highly-serpentinized saprolite ore on a dry weight basis. The metal values are recovered as intermediate products. Key words: Atmospheric Leaching; Nickel Oxide Ores; Laterites

Jan 1, 2004

By Stober, Frank Allan

The paper describes the development of components in an lntegrated Furnace Control system for shielded-arc smelting focusing on operation and crucible integrity enhancement. The paper reviews the mechanisms of power, feed and energy input and losses into the shielded-arc smelting process and describes the furnace control system module development and integration to tailor the process. The ultimate success of a furnace control system application is transfer of knowledge, training, and operational support during furnace start-up and ramp-up phases and a model for how this has been achieved is discussed. The control modules of a shielded-arc laterite smelting furnace are described in detail including measured results and screen captures from application in a laterite smelting furnace. This paper focuses on developments in Integrated Furnace Controls tailored to shielded-arc laterite smelting but development of common furnace control modules for improved crucible and tapping operation integrity applied to other furnace processes, including immersed-arc smelting, is also covered. Keywords: IFC, Power, Feed, Supervisory, Control

Jan 1, 2004

By David T. Hobbs

Large quantities of highly alkaline, radioactive, liquid wastes are stored in underground tanks throughout the Department of Energy complex. These wastes will be pretreated to separate radionuclides and the remaining decontaminated liquid wastes incorporated into solid waste forms for permanent disposal. Significant savings in disposal costs could result by recovering .the sodium as sodium hydroxide for reuse or disposal as nonradioactive waste. Recent testing demonstrated an electrochemical separation process for the recovery of sodium hydroxide from alkaline waste solutions; The separation process uses ion-selective membranes to separate sodium from the bulk of the waste constituents under an applied electrical field. The sodium is recovered as a 10-15 wt % solution of sodium hydroxide. Results of bench-sc3Ie and pilot-scale tests with simulated and radioactive waste solutions are presented.

Jan 1, 1999

By Zvi Rivlin

Classical nucleation theory states that in first order phase transformations, such as liquid to solid transition, nucleation of the product phase starts with the formation of small, unstable clusters (embryos). When the thermodynamic barrier to nucleation is overcome, the embryos grow and attain a critical size, beyond which they are stable, i.e. they become nuclei. If nucle- ation does not occur, the parent, liquid phase remains in metastable equilibrium. At temperature lowers, undercooling increase and atomic mobility decreases. The viscosity change in the undercooled liquid may result in the formation of glassy state. As demonstrated in previous papers [I-21, in solidification involving surface nucleation of the product phase, as the case is in rapid quenching by melt-spinning, both nucleation temperature and nucleation time depend upon the number of atoms available at the isothermal surface in contact with the substrate. As a result of the thinness of the melt-spun ribbons, the embryo clusters that form at the freezing temperature may not be supplied by the amount of atoms necessary for their growth to critical nuclei sizes. In such extreme conditions, the liquid does not crystallize, it forms a metallic glass. A numerical simulation method is proposed for the reactions involved in embryo cluster formation and growth, at the atomic level. The simulation enables the caIcuIation of either the nucleation or the glass transition temperatures. Calculations made for the well-known glass forming CuZr and FeB systems afford prediction of the geometrical and thermodynamically conditions necessary for the formation of either crystalline or amorphous ribbons in melt-spun ribbons.

Jan 1, 1994

By Taner Kavas

In the present study the utilization of coal ashes that appear at the end of firing process of brick production in cement pastes was examined. Ashes with three different particle sizes of 75 µm, 106 µm and 150 µm were used to replace ordinary Portland cement (PC) as 5 % and 15 % by weight. Seven samples were prepared and physical, mechanical, chemical and microstructural analyses were carried out. The compressive and bending strength values of samples were determined at the ages of 2, 7 and 28 days. It was found that cementitious pastes with finer particle sizes possessed the highest compressive and bending strength values at all curing ages. Both values after 2 and 7 days cure increased with an increase in ash content, no matter what the particle sizes of ashes were. However, strength decreased after 28 days cure as a result of ash addition of 15 %, although it was still above that of the PC.

Jan 1, 2006

By Mônica Suede Santos Silva

This work describes characterization of the performance of the tundish of a six strand continuous casting unit of the Companhia Siderurgica Belgo Mineira, Joao Monlevade, Brazil using physical modeling. Permanent and transient conditions, due to ladle metal composition changes are considered. Pulse and step tracer addition techniques are employed to assess the control variables. For transient conditions the degree of inter-mixing and the minimum residence time are determined with a view to optimize the process especially during the grade changes of steel.

Jan 1, 2003

By John H. Schloen

Copper refineries are constantly looking for methods to upgrade their plants to reduce refining costs and to improve the purity of their electrolytic cathodes at the same time that the purity of the anodes they refine is being lowered by the rehabilitation of reverberatory furnace smelters to one of the direct smelting processes. The comments given below are based on the answers to the questionnaire returned bf the 36 copper refineries that represent 66% of the western world s refining capacity. Eleven refineries employ some form of uniform weight anade casting, e.g., Outokumpu, Contilanode, Mitsubishi, Lurgi, or Hazelett. This type of anode casting presents the best possibility for improving cathode purity. The cathode press of Phelps Dadge can improve current efficiencies and cathode quality. The press is used on first-run cathodes, after 48-60 hours, on half-cells at a time without interruption of the cell current. One refinery interrupts current for sever.al hours to allow the anode slime to settle before the, cathode pressing. The cathode press is now used at eight refineries. Apart from periodic reverse current (PRC), it is not expected that current densities will be increased. Thirty refineries, using direct current, average 231 amps/M, with a low of 178 and a high of 350. Five refineries use PRC at an average of 338 amps/M, with a low of 290 and a high of 380. Current efficiencies are good at an average of 94%, with a low of 88% and a high of 99% for the 34 refineries that reported. It must be remembered that the cycle efficiency with PRC is about 93%., so that the effective current efficiency with PRC would be only .94 X .93 or 87% However, PRC should be considered seriously for refinery expansions because it can save about 25% on capital costs.

Jan 1, 1987

By Supachai Surapunt

The distribution behavior of V A minor elements (As, Sb and Bi) in the smelting stage of the Mitsubishi process were evaluated thermodynamically based on thermodynamic data and operating data. The fractional distributions between the gas, slag and matte phases considered as the degree of vapor saturation of 1.0 are as follows: 53.8, 27.2 and 19% for As, 23.6, 56.6 and 19.8% for Sb, and 91.3, 1.1 and 7.6% for Bi, respectively. Arsenic is mostly distributed to the gas and slag phases. It is effectively eliminated by volatilizing and slagging. Antimony is mainly in the slag phase, which is suitably removed by slagging. Bismuth is easily vaporized to gas phase. The degree of vapor saturation has a large effeet on the distribution behaviors of the three elements between the three phases. The amount of a minor element in the charge has an effect on the distribution of As but no effect on the distributions of Sb and Bi. Increasing matte grade and temperature results in the change of distributions for As and Sb, significantly. The change in the distribution ratio between slag and matte phases also considerably affects the distributions of As and Sb. The distribution behavior of Bi is not significantly changed by the change in matte grade, temperature and distribution ratio.

Jan 1, 2003

By Bao Xiancheng

Jinlong's copper flash smelting process started up in April 1997. In the early days of production, lots of equipment and process problems were encountered. But, through continuous improvements in equipment and operation, the designed productivity was reached two years later and the smelting operation has been greatly upgraded since then. After more than 4 yew of production, we have made great achievements, such as increasing the flash furnace availability, significant improvements in operation control, optimization of concentrate burner's structure and operation, and smooth operation of the whole smelter. This paper outlines Jinlong's operational achievements made after commissioning, and discusses problems that were encountered and their countermeasures. Operational experience is also summarized

Jan 1, 2002

By Guangliang Wu, Dong-chang Huang, Xin-bin Liu

High temperature mechanical properties of 50Cr5MoV roll steel was investigated by Gleeble 1500 thermal simulator testing machine The morphology, composition and microstructure of fracture surface were observed and analyzed by OM, SEM and EDS The results are indicative of that, there are two brittle temperature zones of 50Cr5MoV roll steel at the temperature of 600°C~950°C and 1300°C~1450°C, respectively. The section shrinkage rate is less than 60% The fracture mode changes from mixed ones dominated by intergranular to toughness transgranular one with the increase of temperature at the range of 650°C~1300°C. The fracture is along the solid--liquid phase at the range of 1300°C~ melting point It is crucial to formulate the 50Cr5MoV casting technology, to prevent the cracks and improve the quality of 50Cr5MoV roll steel.

Jan 1, 2016

By Guanghui Li

Nickel pig iron (NPI), used as a substitute for electrolytic nickel, is able to reduce the production cost of stainless steel greatly. Aiming for preparing NPI from nickeliferous laterite ore, a pilot-plant scale test of coal-based rotary kiln direct reduction of laterite ore was performed and reported in this study. In this process, the ground laterite sample (18.85% TFe and 1.52% Ni) mixed with additives, pulverized coal and binder was briquetted into briquettes with the size of 40mm×40mm×31mm, laterite ore briquettes and reducing coal were charged into a rotary kiln with the diameter of 1.6 m and the length of 16 m, for a retention period of 6~7 hours, in which reduction section temperature was ranging from 950~1050 oC. The reduced briquettes were water quenched, ball mill ground and beneficated via low intensity magnetic separation. A magnetic concentrate, Ferronickel powder, with 86.9% TFe and 8.0% Ni was obtained, and the corresponding magnetic recovery of iron and nickel are 75% and 96.3%, respectively.

Jan 1, 2014

By Zhuo Sheng

We have designed a high-temperature Raman micro-furnace and cell that is suited for the electrochemical process study of the NO3 − in molten NaNO3– KNO3 (fraction of NaNO3 50 wt%) salt. During the cycle voltammetry and constant potential electrolysis process, the Raman laser beam was focused near the electrode; subsequently, the Raman spectra are obtained and the reduction process of NO3 − is analyzed. In the CV cathodic scan process, the new peak attributed to the ν1 mode of NO2 − emerges, and the peaks assigned to superoxide ions (O2 −) and peroxide ions (O2 2−) are not found. In the constant electrolysis process, the peaks at 1130 and 800 cm−1 appear when the potentials are between −2.0 V and −3.2 V (vs. Pt). The results show that when the NO3 − is reduced in molten the NaNO3–KNO3 mixtures, the reduction product O2− cannot stably exist, and O2− will react with NO3 − to form of superoxide ions (O2 −) and peroxide ions (O2 2−).

By P. Hanniala

In the day-to-day life the copper business of today is influenced directly by the ever-increasing general concern about the environment. In addition to that the inherent shortcomings of the copper smelting business, have since many years been the falling real price level of the metals and the relatively high initial capital investments required for the production units. These shortcomings have been compensated for by high productivity, low specific operating costs, low metal inventory and unbeatable technological superiority. Thus today more than 50 % of the world primary copper is today produced by utilizing Outokumpu Flash Smelting Technology. This figure is expected to grow at an increasing speed in the near future. Characteristic for the Outokumpu Flash Smelting technology is high flexibility for a wide grade of concentrates and the highest sulfur capture owing to at the same time competitive investment and operational costs. The Flash Converting technology offers new options for copper production and optimization of the mine- concentrator-smelter production chain. In the following years it is expected that the trend in copper making is that higher grade concentrates are produced at the mines. Thus increasing amount of high grade concentrate will be available for direct-to- blister Flash Smelting causing an overall cost reduction in copper smelting i.e. both in capital and operational costs. In the '90s new technologies based on Outokumpu Flash Smelting technology have been taken into operation, thus eliminating the non-continuous Peirce-Smith converting process step. New innovative solutions have been used in the latest projects, as in Kennecott Utah Copper, where the new Kennecott-Outokumpu Flash Converting process was started up in 1995. Also, in 1995 the new DON process was started at Outokumpu Harjavalta nickel smelter followed by the Fortaleza nickel smelter in Brazil in 1997. The aim of the continuous development work at Outokumpu has been the expansion of the direct-to-blister process towards lower grade concentrates. The most recent example of this is the start-up at the Olympic Dam smelter in Australia, where the existing direct-to-blister Flash Smelting furnace was replaced with a new one having a capacity of 200 000 t blister copper per annum in just one smelting step.

Jan 1, 1999

By Helfried Nafe

"For about a century thermodynamically absurd facts have been propagated in conjunction with the iron-carbon phase diagram. These facts concern fundamental relationships of chemical thermodynamics. Attention is turned here to the discussion of only one of the relevant aspects of the subject, i.e. the definition of the thermodynamic activity of the solute and its implications for the iron-carbon solution.IntroductionThe view on the iron-carbon solution is characterized by the assumption that the solute may appear in two different forms, i.e. graphite and cementite. Accordingly, two carbon solubilities are differentiated, on the one hand for graphite and, on the other hand, for cementite. As a consequence, two versions of the phase diagram exist simultaneously, the application of which depends on the prevailing conditions, (i) the so-called stable phase diagram with graphite as solute and (ii) the metastable one that is based on the cementite-in-iron solution. These diagrams are joined together in the double phase diagram that originates from Heyn [l ], with the first ideas mainly going back to Stansfield [2] and Charpy [3].Thermodynamically, the most inadequate implication of the Fe-C double phase diagram is that the carbon activity may take values larger than unity. With the standard state of the activity being that of the pure substance, i.e. the Raoultian one, such a value implies the nonsensical existence ofa state purer than pure. The explanation of this physical state, ifthere is any, vaguely refers to supersaturation and, in the wider sense, to the physico-chemical phenomenon of metastability. Other aspects of chemical thermodynamics are likewise involved. Therefore, the comprehensive investigation into the present subject requires more topics to be considered than only one separate issue. Not only should the criticism of the present view be in the focus but also the discussion of new ideas capable of reconciling the experimental facts, known about the F e-C system, with the fundaments of chemical thermodynamics. All this, however, cannot be provided here because of the limited space available. As a consequence, in what follows only a part of the whole problem is under scrutiny, i.e. the definition of the thermodynamic activity and its role for the interpretation ofrelevant experimental facts."

Jan 1, 2014

By W. G. Davenport

Chapter 1 showed that flash smelting is a key step in extracting copper from sulfide ores. It also showed that there , are two versions of flash smelting: (a) Outokumpu flash smelting, which uses oxygen-enriched air blast and injects dry feed downwards into a hot furnace (b) lncoflash? smelting, which uses industrial oxygen blast and injects dry feed horizontally into a hot furnace. This chapter describes Outokumpu flash smelting.

Jan 1, 2001

By Akira Yazawa

In the field of pyrometallurgy, the equilibrium evaluation has recently become easy by use of thermodynamic software, but it is strongly desired to estimate the amounts of non-equilibrium minor components to simulate practical processes. However, simple physico-chemical technique can not be applied to evaluate practical non-equilibrium components for many reasons. As an engineering solution for postulated equilibrium system, the activity coefficient is modified and introduced as the simulation parameter referred to as the "adjustment coefficient." This modified thermodynamic calculations were adopted to various sulfide roasting processes where many solid phases are participating and the system is not necessarily in equilibrium. Successful simulation was realized by assigning suitable adjustment coefficients for minor components which form a pseudo solid solution in the calcine. Some examples from sulfation roasting and dearsenizing roasting were discussed. In the smelting system, the loss of copper in slag is caused by equilibrium and non- equilibrium reasons, that is, chemical dissolution and entrainment of copper in slag. The total copper content of slag was simulated by use of the adjustment coefficient for entrained copper.

Jan 1, 1998

By Kotaro Ogura

"Ethylene has been produced in aqueous solution from CO2 by the electrochemical reduction driven by a natural energy. This process is useful for storing a large amount of the natural energy. In the closed system, the conversion efficiency of CO2 is almost 100%, and the maximum selectivity for the formation of ethylene is more than 70%. On the other hand, the current efficiency for the competitive reduction of water is less than 10%. The electrolysis is practicable under such special conditions as three-phase interface consisting of gas, solution and metal, concentrated solution of potassium halide, low pH and copper or copper halide-confined metal electrode. These requirements are thoroughly examined, and the grounds to reply upon are revealed. A series of chemical apparatuses including an electrolytic cell in a large scale are designed for the ethylene production, which allow us continuously to supply raw CO2 and to extract the product.IntroductionIn connection with the depletion of the petroleum reserve, much attention has been paid to the utilization of natural energies such as sunlight, wind force and waves. However, these energies are always changeable, and some means of storing them are necessary for the common use. In general, natural energies are transformed to the electric energy at the time of utilization, but the electricity is not very storable. This is one of the reasons why the application of natural energy is not so expanded. On the other hand, the storing of natural energy by plants is very skilful. In the photosynthesis, solar energy is transformed to chemical energy by fixing carbon dioxide."

Jan 1, 2009

By Zhihe Dou, Yan Li, Qiuyue Zhao, Guozhi Lv, Yan Liu, Hongliang Zhao

"Abstract: How to reduce carbon dioxide emissions has become a vexing problem, meanwhile, there exist high energy consumption and low efficiency problems in the existing CO2 capture and storage technologies. For CO2 comprehensive Utilization, this paper researches a new technology of absorbing the CO2 emission with high alkaline calcium or high alkaline wastewater sludge mineralization of calcium and invent a core device for multi-level jet carbonation. The industrial test has been carried out in China Xinyu slag Engineering Co., Ltd. The wastewater flow is 150m3/h in the pilot scale. The prepared calcium carbonate has a whiteness greater than 90%, particle size less than 150nm. The mineralization of aluminum exhaust with waste carbide indicates that the CO2 absorption rate is greater than 99.0%, CO2 concentration in the exhaust gas is lower than 0.08%, the purity of mineralized calcium carbonate is greater than 99.0% and particle size is less than 100 nm.InstructionAccording to the statistic data from IEA (2009), the carbon dioxide discharge from fossil fuel consumption in China has exceeded it in the US by the year of 2007, China, has become the largest emitter of carbon dioxide all over the world. Meanwhile, the economic scale is still on an increasing trend in the next 50-100 years, leading to a continuous increment in carbon dioxide discharge. According to the international energy agency forecasts, the energy-relative CO2 discharge in China will rise to 11,615 million tons, 91.3% higher than it in 2007. In the year of 2012, the CO2 gross discharge has reached 10,000 million tons, obviously higher than the predicted value. It is a tremendous task to reduce the emission. Non-ferrous metals industry is one of the largest emitters of carbon dioxide among the industrial circle, the whole industry might discharge a huge amount of carbon dioxide (over 600 million tons), in which the electrolytic aluminum industry is the largest energy consuming industry and CO2 emitter. At present, the CO2 discharge has focused by the whole world due to the environmental problems it causes; meanwhile, supplement of new carbon source is needed due to the exhausting oil and coal resources, so that various countries in the world are attaching importance of the recycle and purification of CO2. Many countries are studying on the cyclic utilization of carbon dioxide. Gas CO2 is mainly applied in chemical, pharmaceutical raw materials, beverage filling agent, refrigerant, inert medium, solvents, pressure source, the welding protective gas, antioxidant and fire extinguishing agent, etc. Solid CO2 is mainly applied in penicillin production, fish, cream, ice cream and other food storage and transportation at low temperature, etc. nowadays, such methods as absorption method, membrane separation, adsorption, etc. are widely used to recycle CO2, with such problems as high investment cost and technical constraints etc."

Jan 1, 2014

By Sheng-hai Yang

The ultrafine, monodispersed, spherical cobalt powder has been fabricated by reducing cobalt hydroxide with glycol. It were investigated that the effect of NaOH concentration on the reaction rate and the effects of the concentration of cobalt hydroxide and surfactant on the morphology and particle size. The particles were characterized by the X-ray diffraction(XRD), scanning electron microscope(SEM), laser diffraction particle size analyzer and BET specific surface analyzer respectively. The XRD shows that the cobalt powders exist mostly in face centered cubic (fcc) structure, a little in simple hexagonal. The cobalt powders prepared at Co(OH)2150g/L, NaOH 40 g/L and surfactant 30g/L, its average particle size, specific surface area and cobalt content, were 0.88µm, 2.705m2/g. and more than 99.5% respectively.

Jan 1, 2006

By Kazuhiro Asai

Hitachi Refinery of Nippon Mining & Metals Co., Ltd. installed a reverberatory type recycling fumace in 1978 in order to treat the industrial wastes which contain metal elements such as copper, gold and silver. Pyrite and industrial waste materials such as galvanizing sludge, hydroxide slime and dust are smelted. Sulfidized copper, iron and precious metals are transformed into matte and other metallic elements are oxidized into slag This copper matte is transported to Saganoseki smelter and copper and precious metals in the matte are recovered. Recently it is difficult to obtain pyrite economically because of the decrease of pyrite production. Therefore, a new treating process of the liquid waste has been investigated at Hitachi Refinery. In this process, the sulfide or sulfate from the liquid waste are smelted as a source of sulfur.

Jan 1, 1997