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By J. W. Dini

Introduction The mission of the Materials Fabrication Division (MFD) is to provide fabrication services and technology in support of all programs at Lawrence Livermore National Laboratory (LLNL). MFD involvement is called for when fabrication activity requires levels of expertise, technology, equipment, process development, hazardous processes, security, or scheduling that is typically not commercially available. Customers are encouraged to utilize private industry for fabrication activity requiring routine processing or for production applications. MFD is .a large diversified service organization including approximately 400 full time employees. The group provides a wide variety of processes including all common machining and fabrications operations, laser and water jet cutting, electrical discharge machining, lapping, electron beam and laser welding, vacuum brazing, heat treating, forming, electroplating and metal finishing, optical polishing and grinding, vacuum coating, vacuum engineering and a variety of plastics operations. These operations occupy more than 1,250,000 square feet of floor space. For more detail on the many fabrication related services available from MFD, see Reference 1.

Jan 1, 1992

By P. A. Metz

The Fairbanks mining district has produced in excess of 7.5 million troy ounces of placer gold and 250,000 troy ounces of lode gold since gold was discovered in the area in 1902. The Fairbanks mining district is in the northwestern part of the Yukon-Tanana Upland Schist Terrane, an area of approximately 240,000 square km that has produced in excess of 21 million troy ounces of placer gold. All lode gold production from the terrane has been from the Fairbanks mining district, and all of this production has come from high-grade gold-quartz polymetallic sulfide veins. Gold grains in the vein systems range in size from several microns to several millimeters. The veins are localized in a complex metamorphic rock assemblage which includes greenstones and felsic metavolcanic and volcaniclastic rocks, meta-exhalatives and metasediments. Gold occurs in the metamorphic host rocks in association with arsenopyrite and arsenic-antimony sulfides which occur in lenses and disseminations within the host rock. Gold grains occurring in the metamorphic host rocks range. in size from sub-micron to a few microns in diameter.

Jan 1, 1987

By W. Mueller

The function of a process mineralogist in the operation of a copper mine and plant is to assist in the identification and classification of the operation's main throughput. These include ore, concentrates, slag and matte, and to a lesser extent, refined products. In addition, a number of other products not normally thought of in association with mineralogy are examined. These include scales from submersible pumps, failed boiler tubes, acid plant, and shaft furnace; characterization of inclusions in failed compressor gear teeth as well as in copper rod; and flue dusts from a smelter, air transported particulates and coatings on passive copper anodes in the refinery. Techniques and equipment required for these studies include simple hand magnets to the high intensity Isodynamic separator, visual examination to electron microscopes, x-ray equipment, DTA, IR, heavy liquid separation, and contracted services of custom laboratories. Several examined products from Magma Copper Company have been selected to illustrate the range of techniques and equipment required by a process mineralogist.

Jan 1, 1981

By E. Krystad, G. Tranell

"The kinetics of boron removal from liquid silicon during slag refining, as a process step in the production of solar grade silicon, has been investigated by means of small scale mass transfer experimental series at 1600°C, using a graphite crucible. The slags were SiO2-CaO based, with or without addition of approx. 19 wt% MgO. Experiments were carried out at slag-metal ratios of 1 or 2, where the silicon initially contained approx. 250 ppm boron. The metal-slag mass transfer coefficients for boron were found to be in the order of 1-3 · 10-6 m/s and were largely influenced by slag composition. The mass transfer rate was higher for the MgO-containing slag than the slags without MgO. The final equilibrium distribution of boron between metal and slag, LB, was determined to be in the order of 2.3-3.3.I. INTRODUCTIONRecent years have seen a race in industry and research aimed at obtaining a reliable metallurgical route for production of silicon for solar cells (SoG-Si) from metallurgical grade (MG) silicon. Metallurgical routes can successfully challenge the traditional chemical routes for production of SoG-Si if they generate metal of sufficient purity while being less expensive in terms of production cost and energy consumption. Efficient removal of boron is one of the greatest obstacles in the refining of silicon by a metallurgical route, because the segregation coefficient of boron in silicon makes directional solidification unfeasible; in addition, the vapour pressure of boron is not high enough for removal by vacuum refining. However, the thermodynamic properties of boron makes removal from silicon by oxidation possible, and thus the process of slag refining of silicon has been receiving increasing attention as a method for boron removal."

Jan 1, 2012

Thermodynamics and kinetics? of the removal of Va elements (As,Sb,Bi) from copper were investigated 1n the fire relining by alkaline carbonate fluxes such as Li 2co3 , Na 2CO3 and K2CO3. The distribution coefficients of As, Sb and Bl between alkaline carbonate fluxes and mo) ten copper were ?obtained at 1200°C under the different oxygen potentials. As and Sb were easily removed from copper to fluxes as pentavalent oxide form. On the other hand, Bi was hardly removed except by a Ll2CO3 flux. The removal rates of Va elements from copper were also measured In the temperature range of 1150°C.- 1250°C. The removal rates of As and Sb were much higher than that of Bi. The removal rates of Va elements showed the same order of the distribution coefficients. The removal rate could be expressed by following equation. (1).

Jan 1, 1987

By P. Myllykoski, J. Nylander, A. S. Korhonen, J. Larkiola

The coefficient of friction and the deformation resistance have been determined from the measured rolling parameters by applying the Bland-Ford-Ellis rolling force model and the artificial neural network model (ANN). The dependence of friction on the parameters such as reduction, rolling speed, front and back tensions, contact pressure and deformation resistance have been studied by the ANN model. Measured data of over 10 000 coils have been used in the training stage. Various dependencies have been examined and the results show that the friction coefficient does not depend much on the rolling speed. The reduction and deformation resistance seem to have the strongest effect on the friction coefficient. A friction model based on neural computing has been included into the existing rolling force model.

Jan 1, 1994

By Natasa Mitevska

The statistical analysis of the slag composition influence on copper losses to discard slag in the reverberatory furnaces No.1 and No.2 in the RTB BOR, Copper Smelter and Refinery (Yugoslavia) is presented in this paper. The model for the slag basicity calculation is determined, and connected to the copper distribution coefficients between the matte and slag phase. The influence of all components on the slag structure is also illustrated.

Jan 1, 2003

By Animesh Jha

"Fine ceramic powders (<500 nm) exhibit exceptional physical and mechanical properties in engineered structural ceramics. The production of fine powders, in particular the non-oxide ceramics, via a cheaper route than the organic solvent route has been rather elusive. This paper examines the physical chemistry of sub-oxide vapour-phase reduction reaction for the nucleation of non-oxide ceramic phase. Well known vapour species eg SiO and BO in the production of technical ceramic powders (SiC, BN) are particularly discussed for understanding the nucleation process of SiC and BN ceramic phases respectively. The regimes of partial pressures and temperatures are particularly 'identified. The calculated nucleation rate as a function of the temperature is compared with the experimental results on powder morphology. The production of amorphous and nanocrystalline h-BN powders is discussed in the context of substrate structure and thermodynamic parameters.IntroductionThe physical and mechanical properties of ceramic components are strongly dependent on the powder particle size and morphology used for their fabrication. For example the strength (Os) of the structural ceramic components increases with decreasing average grain-size (d) in accordance with the Hall-Petch relationship: Os = 0""0 + k/(d)1/2. Here k is an empirical constant which can be established from the graphical relationship. However as the particle size approaches submicrometer-size range, the dependence of strength on the particle size becomes more complex [1]. The design of ceramic components based on nanometer-size particles have recently become an important field which can offer ceramic materials with properties comparable to their metal counterparts. Several materials based on these concepts have been developed and reported by Niihara [2]. For example, the Al2O 3-SiC nanocomposite, having average B-SiC grain size 0.3-2um with intragranular SiC particulates of 5-10 nm has unusually high strengths (1100 MN/m2) at low and elevated temperatures combined with enhanced fracture toughness (> 4 MN-ml.5) which is an unusual combination in structural ceramics. Besides mechanical properties, as the particle size of ceramic powders approaches the nanometer-size range, the charge transport properties also improve by many times. The effect of particle size on the electrical conductivity of Si3N4-TiN composites has been well documented [3.4]. The size of ceramic particulates without doubt plays a pivotal role in determining the properties of ceramic components."

Jan 1, 1996

By L. Sh. Tsemekhman

A new technology for the treatment of copper nickel-containing concentrate after high-grade matte flotation to blister copper with the production of liquid silicate slags in a vertical autogenous unit with upper oxygen blow has been considered. The copper and nickel behavior in the process of sulphide copper concentrate interaction with silicate melt containing oxide copper has been studied. The general mechanisms of such interaction are found.

Jan 1, 2003

By Run Huang, Xuewei Lv, Lei Lei, Guibao Qiu, Chenguang Bai

"The TiO2-rich slag and pig iron can be produced from ilmenite concentrate by the electric furnace process. In this study, ilmenite concentrate was reduced in a vertical furnace equipped with a weighting data acquisition system. The effects of reducing agent (carbon) amount on the iron reduction were studied. The phase transformation, morphology and chemical compositions of reduced samples were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. It was found that the reductive degree of ilmenite concentrate increased with the increase of reducing time. The phases of reduced samples were mostly iron, rutile, Ti3O5 and Fe2TiO5. The mass loss percentage increased with increasing the carbon amount from 8% to 12%. When the carbon amount exceeded 12%, the mass loss percentage decreased with the increasing of carbon amount.IntroductionIlmenite and rutile are the main raw materials for producing titania pigment and titanium metal. With the development of the titanium industry, huge amounts of titanium resources are needed. As sources of high-grade titania mineral decrease worldwide, more attention should be paid to the processes involving low grade mineral such as ilmenite ore. In ilmenite, MgO and CaO are the gangue parts. Therefore, the ilmenite refining becomes more and more popular. In the previous studies, the methods of ilmenite refining are electric furnace smelting, direct acid leaching, selective chlorination and thermal reduction [1]. Electric furnace smelting method is widely used in the titanium industry, however, which consumes a great deal of energies and has a high CO2 emission. Its essence is to remove iron oxides and obtain a high titania slag. So the thermal reduction of ilmenite concentrate is an important step in titanium industry, which can decrease carbon reagent consumption and save energy.Over the past several decades, many studies have been carried out on the mechanism and kinetics of the reduction of different ilmenite ores, which are as follows: The carbothermal reduction of Panzhihua ilmenite initiated at about 860 oC. In the temperatures ranging from 900 oC to 1400 oC, the reaction rate was changed like a shape of “M”. That was to say that the reaction rate increased with the growth of temperature at first, then decreased, afterward increased again and at last the reaction was arrested [2]. The Mohammad A.R group [3, 4] showed that the carbothermal reduction of primary ilmenite concentrate was faster in hydrogen and initiated at a lower reduced temperature than in argon and helium. The reduction in argon and helium had about the same rate and extent. Titanium oxycarbide started at 1000°C in hydrogen. The conversion of primary ilmenite concentrate to metallic iron and titanium oxycarbide at 1200 °C was completed in 300 minutes. Monoxide as the reductant to reduce ilmenite had been studied intensively by a few research groups [5, 6]. The rate and the degree of reduction depended on the formation of a metallic shell of iron which inhibited the transfer of CO to the reaction zones; titanium had a strong effect on the mechanism and rate of reduction of iron oxides. Wang and Yuan [7] studied the reductive kinetics of the reaction between a natural ilmenite and carbon. At temperature below 1100°C, chemical reaction was the rate controlling step, at 1100 to 1250°C mixed controlling was rate controlling step, above 1250°C diffusion through the product layer controlled the reaction. Zhang [8] investigated the reduction of natural, sintered and preoxidized ilmenite concentrates in hydrogen methane mixtures. Preoxidation and sintering of ilmenite concentrates changed their phase composition and caused a sharp decrease in specific surface area of raw materials and an increase in carburization temperature. Sintering also increased the metallization temperature of iron."

Jan 1, 2011

By Guolin Zheng, Jian Pan, Deqing Zhu, Xianlin Zhou

"In ferronickel production, nickel oxide and part of the iron oxide are reduced to metal by agglomeration and smelting in blast furnace. Due to the physical and chemical properties of the laterite ores, a large fraction of fines is generated during the pre-treatment stages and the strength of agglomeration is weakened, which results in low productivity and bad quality. In this paper, the process of pelletization of nickel laterite was developed, and some parameters to strengthen the pelletization of nickel laterite have been optimized. The results show that the compressive strength of fired nickel laterite pellet can reach over 2000 Newton per pellet while firing at the temperature of 1220 °C~1250 °C in 12 min. The product pellet can be used as high-quality burden for blast furnace to manufacture ferronickel.IntroductionIn recent years, the global stainless steel market was developed exuberantly, which greatly promoted the needs of the basic raw material of stainless steel smelting - metal nickel. Currently nickel sulfide ores are only 40% of global nickel reserves, but offer 60% of all the nickel production. However, with the deficit of resources, the nickel sulfide ore (high grade ore) is depleting, so there is an increasing focus on the utilization of low-grade nickel laterite. Recent research has focused on the wet treatment process to utilize nickel laterite, and less on the use of other technologies [1-8]. The economical and efficient technology relies on the reduction of nickel oxide and part of the iron oxide metal by agglomeration and smelting in blast furnace in China. Some domestic steel companies have adopted this process [9, 10]. Unfortunately a large fraction of fines is generated during the pre-treatment stages and the strength of agglomeration is weakened, which results in low productivity and bad quality of fired pellets. In this study, the process of pelletization of nickel laterite was developed firstly, and some parameters to strengthen the pelletization of nickel laterite have been optimized, and the product pellet can be used to produce stainless steel and ferronickel alloy by blast furnace."

Jan 1, 2011

By Donghai Li, Cheng Pan, Pan Chen, Xuewei Lv, Mei Liu

"Chromite concentrate after beneficiation can not be directly used in the electric furnace. Therefore sintering is one of the effective way to agglomeration, by which the chromite concentrate can be utilized and the power cost of ferrochrome smelting can be reduced. The properties of raw materials and the sintering process of chromite concentrate were studied in this work. The results showed that chromite concentrate used can hardly granulated alone, while chlorite addition can improve the effect of granulation. Moisture plays an important role in sintering process. The granulation effect is optimal when the amount of water addition is 12%. Strength and abrasion index are the evaluation indexes of sinter quality. It was found that the strength of sinter increased with coke dosage increasing to 12%, and then decreased when it continuously increased. Opposite regularities were found for the abrasion index of the sinter.1 IntroductionChromium is a very important metal element which is mostly used in the production of stainless steel. In the earth, it is always formed compound with iron as ferrochromium spinel (FeO.Cr203), and its mineralogical name is chromite.[1] Currently, the global production of chrome ore is about 20 million tonnage every year , in which fine ore (less than 8 mm) accounted for about 80% [2] Although the price of the fine ore is cheaper than the lump one, too much fines will lead to the poor permeability and causes increased electricity consumption while producing ferrochrome. Therefore, the agglomeration process of chrome ore is one of the effective measures to increase the usage ratio of fine ore."

Jan 1, 2013

By G. G. Krishna Murthy

Several experiments were conducted to determine the rates of heat transfer coefficients of CaO-SiO2-A1203-FeO slags at temperatures in the range 1623-1823 K The experimental technique involved measuring heating rates of a solid specimen, sub¬merged in slag phase, using a temperature probe made of Pt\ 10%Rh-Pt. Effect of %FeO (3-10%), %FeS (0.1-0.68%), %P205 (0.2-3.0%), %MgO(5-6%), and %MnO (0.96-3.84%) present in the slag on overall heat transfer coefficient, U, of slags was investigated. Simple first order heat balance equation in combination with experimental plots rising temperature of solid specimen versus time were employed to determine the values of U. The values of U determined in the present investigation were present in the range of 70-260 cal/Ks.m2. The value of U increased with increasing the slag temperature. The values of U were not effected by increased amounts of sulfur in the slag phase. The increased concentrations of MgO, FeO, MnO, and P205 in the slag phase decreased the values of U. On the other hand, the increased amounts of Fe2O3 in the slag phase increased the value of U. Comparison of the results, obtained using the slag bath stirred by argon injection, with those determined without any stirring indicated that both radiative and conductive heat transfer mechanisms are important even at high temperatures.

Jan 1, 1993

By Hongbo Zhu, Jinhui Peng, Linqing Dai

"To optimize the process variables for making direct reduced iron (DRI) by microwave heating, the reduction temperature, reduction time and the ratio of coal to material were studied with the central composite design (CCD) and their interactions on the Metallization rate were also investigated. The predictive polynomial quadratic equations model was analyzed by ANOVA. Optimal conditions of making DRI can be concluded as follows: 28 min at 1139?, the ratio of coal to material is 20.95%. Under these conditions, the metallization rate is up to 97.06%.1. IntroductionThere are some technical problems in making direct reduced iron (DRI) or sponge iron using iron ore concentrates containing coal and lime. In reduction of the iron ore concentrates containing coal with microwave heating, the strength of pellets needn’t to be considered. It reduces the costs and improve quality of materials, but also eliminates the need for pellet preparation process, simplifying the process and achieving a cleaner production.Microwave energy is a clean energy, and has characteristic of selective heating. The speed of heating is also fast. It researched by Chen Jin that when the mole mass of C: O is 0.627 and the microwave power is 15KW, it only spends 15min from 15? to 1021.6? with 1 kg iron ore containing coal with microwave heating [1]. There are many factors affecting metallization rate. In order to find a suitable condition for reduction process, it is necessary to design a series of suitable experiments.Response surface methodology (RSM) is one of the relevant multivariate techniques which can deal with multivariant experimental design strategy, statistical modeling and process optimization [2–5]. It is used to examine the relationship between one or more response variables and a set of quantitative experimental variables or factors. This method is often employed after the identification of the vital controllable factors to find the factor settings that optimize the response. Designs of this type are usually chosen when a curvature in the response surface is suspected. The process optimization of the microwave reduced iron ore was seldom reported in literature. Hence the present work intends to assess the effects of variables such as reduction time, reduction temperature and the ratio of coal to identify the optimum conditions using a central composite design (CCD). The characteristic of product was assessed using scanning electron microscope (SEM)."

Jan 1, 2011

By John A. Herbst, William T. Pate

"Plantwide control of mineral processing operations has long been sought for its potential benefits. These benefits include minute-to-minute optimization, reacting to disturbances in ore characteristics and equipment status as they happen, and the coordination of all unit operations in pursuit of the highest performance level. However, several difficult challenges have kept us from fully realizing those benefits. One of these challenges has been to provide fairly complete quantitative descriptions of unit operations to account for critical interactions within and between unit operations. In some cases we understand the physics and chemistry very well and can incorporate that knowledge into phenomenological models. In other cases our knowledge is incomplete, so we must rely on other forms of knowledge such as fuzzy logic or neural nets. Another challenge to be met has been to simultaneously compute a large number of manipulated variables. In the past this challenge was met by optimizing only unit-by-unit, rather than on a global basis to significaritly reduce the number of variables. In this paper, a procedure that globally optimizes one or two important variables is outlined. This procedure comes much closer to true plantwide optimizing control while remaining computationally feasible. Finally, another major challenge is to choose a meaningful global objective that can be calculated with the models and can be effectively optimized. Financial goals seems to be the objectives of choice.This paper discusses recent progress in overcoming the challenges and illustrates a promising approach which is being pursued at Mexicana de Cobre's La Caridad copper ore concentrator. At M de C, advanced control strategies have been installed one at a time in the crushing, grinding and flotation sections. During this period, the throughput of La Caridad, Mexico's largest copper concentrator, increased from 76,000 tpd to 90,000 tpd. Plantwide integration is expected to gain an additional 3% improvement in profitability."

Jan 1, 1996

By José Luiz Rodrigues Bravo

The production of electrolytic copper with assured quality corresponding to international standards, in a conventional electrorefkery of a custom smelter, is a hard and cautious task, if no advanced technologies for selective control of electrolyte impurities are available. The improper control of the amount of As , Sb and Bi in the anode that enter the tankhouse , attributable either to a bad schedule of concentrate input or to the unavailability of clean concentrates in the international market , as well as the lack of means to maintain the suitable level of these elements in the electrolyte together with other operational circumstances, can result in off-grade copper, as well as affect the starting sheet chemically and physically. This paper presents in a practical way the relationship between the operational conditions and the cathode and starting sheet quality produced at CMSA, covering the period of the last five years of operation, discusses the technologies available in the market for antimony and bismuth removal and compare the results of testwork, achieved in the laboratories of CMSA, using two resins not associated with patented technologies.

Jan 1, 1997

By Bo Jiang, Lianyun Liu, Hongmin Zhu, Kai Huang

"Watermelon peel is selected as a novel adsorbent to remove Pb(II) from aqueous solution. A simple saponification process is proposed to modify the peel and the adsorbent is characterized by SEM and FTIR. The effects of pH, contact time, initial concentration of Pb(ll), biosorbent dosage and temperature on adsorption of Pb(II) are investigated. Different models are used to fit experimental data. These models indicate that the adsorption process follows the Langmuir model and pseudo-second-order model. The maximum adsorption capacity obtained from Langmuir model is 1.05mol kg-1 for the prepared sorbent. Equilibrium time is attained in 5-10 min for the studied concentrations. The watermelon peel can be used as an effective and low-cost biosorbent for removal of Pb(ll) from aqueous solution.IntroductionRecently, removal of heavy metal ions from industrial effluents by biosorption has become a very attractive topic, since the more serious pollution issues caused by heavy metals emerge frequently, and more strict requirements for its control are called upon by society [1,2]. In this case, most conventional purification technologies are not suitable due to poor cost-effectiveness [3]. For example, chemical precipitation by alkaline reagents usually can not decrease the metal ion concentration below the permissive levels, and also it will produce a large amount of sludge containing toxic metals. Membrane separation techniques can realize deep purification of wastewater easily, although its operating cost is usually high. Thus, considering the high effectiveness, low cost and free-sludge operation, bisorption has become a promising technique in water treatment [4]. The most important thing for this technology is the synthesis of a suitable biosorbent, whose adsorption properties will determine the removal efficiency and economic cost for the whole process. Watermelon is one of the most popular fruits for mankind for its delicious flavor. Usually, the watermelon is consumed mainly for its edible pulp, and its peel is discarded or only used as feed for livestock. Considering the pectin contained in the watermelon peel, just like that in orange wastes in the reported literatures [3], the idea of using it as the raw material to prepare the biosorbents for heavy metal ions removal from the aqueous solution was evaluated in this study."

Jan 1, 2012

By Virgil Optasanu, Yvon Lacroute, Eric Lesniewska, Tony Montessin, Pauline Vitry, Eric Bourillot, Cédric Plassard

A general challenge in metallic components is the need for materials research to improve the service lifetime of the structural tanks or tubes subjected to harsh environments or the storage medium for the products. One major problem is the formation of lightest chemical elements bubbles or different chemical association, which can have a significant impact on the mechanical properties and structural stability of materials. The high migration mobility of these light chemical elements in solids presents a challenge for experimental characterization. Here, we present work relating to an original non-destructive, with high spatial resolution, tomographic technique based on Scanning Microwave Microscopy (SMM), which is used to visualize in-depth chemical composition of solid solution of a light chemical element in a metal. The experiments showed the capacity of SMM to detect volume. Measurements realized at different frequencies give access to a tomographic study of the sample.

Jan 1, 2015

By Patrick R. Taylor

Glass is used for immobilization of radioactive and hazardous wastes due to its durability and ability to accept a variety of waste constituents into its network structure. Alternative high temperature vitrification techniques have the advantage of increased throughput, increased waste loading and being applicable to variable and heterogeneous waste streams. However, the increased processing temperature places further concerns on the increased volatilization of contaminants, and increased corrosion and erosion of me Iter components. A database of melt properties at higher temperatures, such as partitioning, viscosity, density and electrical conductivity, in the temperature range of 1400-20000 K are being developed.

Jan 1, 2000

By Leonard J. Friedman

The recovery of sulfur dioxide from metallurgical gases for the production of sulfuric acid has been an effective means of reducing sulfur dioxide emissions from non-ferrous smelters. Sulfuric acid has been produced from gas originating from fluid bed roasters, electric furnaces, reverberatory furnaces, flash smelting furnaces, Pierce Smith and flash converters, sinter machines, etc. The gas from each of these sources has a unique set of variables that affect the design and operation of the sulfuric acid plant. In addition, the sulfuric acid plant itself has been evolving, with new equipment designs and materials. This paper will review each of the unit operations in the gas cleaning and contact sections of the metallurgical sulfuric acid plant, discussing various equipment designs, materials and the handling of gas stream variables and impurities. The paper updates to 2006 previous works on metallurgical sulfuric acid plants by the authors.

Jan 1, 2006