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By Stuart D. Miller, Clayton L. Rumble

"A field net acid generation (NAG) test procedure has been utilized on-site to identify, classify and map potentially acid forming overburden at the PT Kaltim Prima Coal (K.PC) mining operation situated in the tropical equatorial region of East Kalimantan, Indonesia. The field procedure involves routine use of a calibrated, site specific NAG test (rapid oxidation test using hydrogen peroxide) which has a tum-around time of less than 24 hours and requires minimal sample preparation. It is used on geological drill-hole samples, for forward planning and overburden management; blast-hole samples, for day-to-day operational control and overburden scheduling; and final dump surface samples, for verification testing. This operational monitoring program has been in use at KPC for the past four years.Calibration and implementation of the field procedure has involved validating the NAG test using conventional acid-base accounting techniques, producing an overburden geochemical classification scheme, optimizing laboratory and sample preparation procedures, and ongoing quality management. This paper presents background theory and practical application in a case study format."

Jan 1, 1999

By Jennifer Murphy, Brad S. Schake, Karol Holmes, John R. FitzPatrick, Mike H. West

"The separation and purification of uranium from either nitric acid or hydrochloric acid media can be accomplished by using either solvent extraction or ion-exchange. Over the past two years at Los Alamos, emerging programs are focused on recapturing the expertise required to do limited, small-quantity processing of enriched uranium. During this period of time, we have been investigating ion-exchange as a method for extraction/purification of uranium from acidic media. In addition, waste stream polishing is associated with this effort in order to achieve more complete removal of the uranium prior to recycle of the acid. Extraction chromatography has been demonstrated to further polish the uranium from both nitric and hydrochloric acid media thus allowing for a more complete recovery of the actinide material and creation of less waste during the processing steps.We will discuss contact experiments for evaluation of eleven different resins for uranium removal from nitric acid, the evaluation (again by contact experiments) of uranium elution from the ion-exchange media by various chemicals, and small-scale experiments for the removal of 235U from nitric acid. Larger-scale (1 DO-gram) flow experiments, using depleted uranium, were done after the small-scale evaluation of the selected resin. A discussion is also included concerning the shortcomings of the contact experiments and how the flow experiments were modified in order to overcome these problems. We will also discuss the application of ion-exchange for some specific process needs at Los Alamos.Contact experiments were used to evaluate some commercially available solvent-impregnated resins in addition to evaluation of several resins of this type synthesized in our laboratory. These experiments involved both nitric and hydrochloric acid media. The data from these experiments will be used to determine the column size and amount of resin required to polish the waste stream produced by the ion-exchange process described above. Small-scale flow experiments will be described and data given on the mass balances achieved using this two step process.Future work for evaluation of new ion-exchange and solvent-impregnated resins as well as the search for new eluants will be discussed. Other future experiments for both processes, including large-scale experiments, will be discussed in detail."

Jan 1, 1996

By C. A. Pickles

At the present time, pyrometallurgical processes are employed for the recovery of lead from battery scrap. These processes have serious pollution problems, primarily due to the emfssion of sulphur dioxide and airborne lead in the form of dust and fume. In addition it is necessary to dispose of solid wastes and liquid effluents which contain lead and in some cases sodium sulfide-containing compounds. In this work an improved process was investigated for the recovery of lead from battery residue. This involved pelletization of the residue with sodium carbonate and moisture. Then, the pellets were melted without carbon and the .sodium sulphate salt was removed. Subsequently, the molten lead oxide was reduced with carbon. This process minimizes the sulphur dioxide emissions and leads to very low sulfide contents of the sodium sulfate salt

Jan 1, 1992

By Kee Jeung Lee

In this study the characteristic factors and formation mechanisms for the hydrothermal preparation of a -quartz crystal powders were investigated to find the optimum synthetic conditions. The degree of Q -quartz crystal face development depended on the relative growth rate of a particular form that varies considerably with the degree of supersaturation, the reaction temperature, the concentration of mineralizers, and the presence of seed crystals in the feedstock. Alkali hydroxides and alkali halides were found to be effective in the reactions as mineralizers, which added in order to increase the solubility of the feedstock. The fine Q -quartz crystal powders were obtained in the temperature range of 250-450% and pressure range of 100-300atm. As the concentration of mineralizers increased, the particle size of crystalline powders became smaller at lower reaction temperatures. The fractional size distribution of synthetic crystal powders was depended on the hydrothermal conditions. As the reaction time and the amount of seed crystals increased, the width of particle size distribution became narrower. The weight mean particle size was in the range of 1 to 10m. The characterization of the products were carried out using XRD. SEM. PSA, FT-IR, Raman spectrometer.

Jan 1, 1997

By Junji Shibata

Zeolite synthesized from coal fly ash has many intelligent properties such as cation exchange, adsorption, catalyst and so on. The suitable use of the zeolite, however, is not established in an actual commercial scale yet. From the viewpoints of an effective usage of coal fly ash and the zeolite obtained from coal fly ash, we propose the new concept for environmentally friendly usage of zeolite, in which coal fly ash safely returns to the soil with growing plants and purifying wastewater. This method can make great contribution to recycle of coal fly ash, to purification of high nutritious water and to tree planting.

Jan 1, 2002

By Kazuhiro Asai

Nippon Mining and Metals Company has an annual indium production capacity of 30 tons at its Saganoseki smelter and refinery. Lately, indium content in the. zinc smelting dust, one of the main sources, has been on the decrease while the amount of impurity in it on the increase. The present process at Saganoseki does not permit efficient elimination of a large. amount of impurity. Therefore, studies were conducted to improve its recovery process. As a result, a new indium recovery process consisting of leaching, solvent extraction and electrowinning has been developed. The new process was tested at a pilot plant and satisfactory results were obtained. This new process is discussed in this paper.

Jan 1, 1995

By Kathryn Hindmarsh

The most common method for the concentration of cyanide in gold leach circuits is based on the titration of cyanide ions with silver ions. This can either be done manually as a titration with a visual end-point or by using one of several commercial cyanide analysers which are 'based on the same titration but use a potentiometric end point This method has 'its limitations in the case of some ores such as those containing high amounts of soluble copper and those that are treated at low (less than pH 9) pH values in that the titration results do not accurately reflect the concentration of cyanide which is available for the dissolution of gold. This paper will present the results of the development of a novel "active" cyanide analyser which is based on the rate, of the reaction between gold colloids and cyanide. Gold colloids have a deep red colour and can be very simply prepared and stored for extended periods of time when stabilized. t has been shown that colloidal gold behaves similarly to metallic gold, dissolving in aerated sodium cyanide solutions to give the colourless Au(CNh-ion, This allows the reaction between the colloids and cyanide to be monitored spectrophotometrically at 520 nm. An automated instrument has been developed around this concept which can analyse a filtered pulp stream every few minutes with periodic calibration using standard cyanide solutions, Results of test work on synthetic solutions and solutions derived from several Australian gold plants will be presented as will the results of a comparative evaluation with a commercial titration analyser on a local gold plant

Jan 1, 1998

By V. R. Voller

"The World Wide Web (the web) provides a very useful resource for the enhancement of teaching and research dissemination. This paper advocates that researchers take control of this resource and become actively involved in creating web content. Two examples of the use of the web in a materials setting is provided. The first illustrates how a concept quiz for teaching can be developed. The second shows how a materials processing model can be run in real time over the web. The paper closes with a summary of some resources that can be used to create web materials.IntroductionA recent copy of a newspaper advertisement read""Share what you know, learn what you don't""This neat phrase sums up a powerful teaching and research philosophy. In an educational setting a prime motivation for research is to uncover the unknown and venture in directions previously uncharted. The balance to this search for knowledge should be a desire to share that knowledge with others; whether it be with students in the classroom or research colleagues in a wider setting.The .World Wide Web and its associated multi-media software offer a perfect platform for researchers to share their knowledge with an extremely wide sector of the research community. To enable the use of this resource researchers must take the power that the web offers them into their own hands and create products that take maximum advantage of the medium. It is key that researches at the forefront become directly involved, otherwise a potential powerful medium will not realize it's true potential, and colorful products with no core content will proliferate. The object of this paper is to outline two ways in which the web can be used to enhance teaching and research objectives."

Jan 1, 2000

By Carla Lupi, Alessandro Pescetelli

"Spent lead battery recycling still shows few weak points in the achievement of a 100% recycling of different waste matters and by- products arising from the recycling process. Some of said problems are dealing with aqueous streams outgoing the recycling plant, and more particularly, a) the waste waters discarded from the breaking and separation unit, b) purification of the spent electrolyte drained from waste batteries and upgrade to a quality compatible with full re-use by the batteries’ manufacturers, c) purification of the mother liquors discarded in the sodium sulfate crystallization process so to produce a salt of commercial grade. All of the above listed problems have been satisfactorily overcome applying an electrochemical process that, through different process conditions and parameters, is able to remove the harmful impurities that hinder the successful commercialization of such by products, or, at least, that can avoid heavy and expensive treatment plant and operation.IntroductionAlmost 100% of commercial lead and lead alloys produced by secondary lead plants is recycled to the new lead accumulators manufacture. The other by-products and residues produced through the lead recycling process may be classified into two groups:a) matters reusable in the new accumulators production processb) matters produced as a result of various reagents and additives used in the recycling process, to be sold to different market sectorsQuality and saleability of by-products are significant points for the economics of the secondary lead plant operation, because, if said by-products are not saleable, they are just wastes, so offsetting potential revenues, and, at the same time, adding a heavy burden to operating cost, like disposal cost [1]. When looking at a typical, modern lead scrap batteries recovery cycle, it is quite evident that we are still rather far from dealing with a waste-less technology (fig.1).The group a) includes 3 by-products produced through the breaking process: among those matters the polypropylene only usually reaches a standard quality suitable for sale to lead manufacturing sector or to other sectors as well. The other two by-products, electrolyte and separators, do not still reach, through a viable and effective regeneration process, a quality standard sufficient for their re-use in the lead batteries sector ."

Jan 1, 2008

By John C. Taylor

With growing emphasis on energy conservation and increased concern over the presence of heavy metals in the environment, it is fortunate that most metals are readily recycled. In this respect, metals have a significant advantage over plastics and similar materials used as metal substitutes. For many years a secondary industry has processed scrap copper, nickel, lead and zinc to produce refined metal which has, to varying degrees, influenced the price and displaced the production of primary metal. This paper reviews some of the challenges the industry will face and the changes in process technology which will be required as pressure mounts to increase the amount of metal recycled. In the case of most base metals, this will have an impact on primary metal production; as the tonnage of metal recycled increases, the requirement for primary production, or new metal, will depend more and more on the growth in consumption.

Jan 1, 1993

By Wenbo Luo, Jilai Xue, Tiepeng Li, Jun Zhu

Sodium silicate solutions for producing silica have been ultrasound treated to enhance the precipitation process in laboratory scale. Higher precipitation rate was found with ultrasound treated solutions than those without ultrasound. The obtained SiO2 powder products were characterized using XRD, SEM, BET and laser particle size analyzer. The particle size distribution and the specific surface area of the powder products varied with the power input level and the processing time of the ultrasonic treatment. The results indicate that the efficiency of the precipitation process can be improved optimally when the ultrasound is conducted into the solutions before the nucleation stage.

Jan 1, 2015

The kinetics of the oxidation of cyanide by manganese dioxide was studied using a rotation disc electrode system. The rate? of the half-cell reaction of cyanide oxidation is increased at higher hydroxide concentrations. An addition of copper up to 0.001 mole/l was found to enhance the diffusion current, especially at a high hydroxide concentration (0. 1M). A similar enhancement of the reaction rate is also achieved with nickel added at levels up to 0.01 mole/l. Manganese dioxide however requires a i:ow pH to achieve reasonable reduction rates. Leaching studies indicated that the initial reaction rate is strongly dependent on pH, initial concentration of cyanide. Using manganese dioxide cyanide could be oxidized at neutral pH's and ambient temperatures.

Jan 1, 1989

By Antoine Allanore, Luis A. Ortiz, Donald R. Sadoway

"The steelmaking industry has drastically reduced its energy consumption in the last fifty years, and today’s technologies are considered to operate at their optimal efficiency with respect to energy needs. To cope with new constraints related to greenhouse gas (GHG) emissions, a change of paradigm is necessary. One of the promising technologies that could be deployed to help reach CO2 mitigation targets relies on the intensive use of electricity: molten oxide electrolysis (MOE). This paper presents the key process parameters that need to be tuned to address the practical needs for both high productivity in a steelmaking reactor and for an energy efficient process. Herein we show that contrary to common perception, the electrolysis process for ironmaking requires less energy than today’s chemical reduction route. Furthermore, we prove that most of the energy that must be provided to operate the electrolytic iron production cell is thermal energy which is readily generated by joule heating during electrolysis due to large currents being passed through the electrolyte. The energy consumption of the electrolysis cell is therefore shown to be highly dependent on the cell configuration and the chemistry of the electrolyte. As a consequence, the CO2-impact of the technology strongly depends on both the power production mode and the technological choices for design of the process, including cell configuration. Surprisingly enough, even when the electricity generation is not carbon-free, MOE still appears to be viable from the perspective of reducing GHG emissions providing sound reactor design considerations are made.IntroductionIn the context of greenhouse gas (GHG) emissions mitigation, the steelmaking industry is considering several techniques that could sustain the efforts and progress achieved by this sector in the last decades [1]. A recent report [2] on potential routes for low-CO2 steelmaking highlighted for all techniques both the strong dependency of CO2 emissions on electric power production mode and the need for a decrease in energy consumption per tonne of steel. Incited to innovate with respect to this last criterion, the steel industry considers electrolysis to be a promising technological solution, and in particular the molten oxide electrolysis (MOE) process. This process conducts electrolysis in a mixture of oxides that dissolve the iron oxide feed, which by the action of electric current is decomposed into liquid iron and oxygen gas. The opportunity for reduction in energy consumption during steelmaking by MOE is commonly attributed to the “direct” pathway from iron oxide to liquid metal offered by the use of a molten oxide melt and operation at a temperature above the melting point of iron, ideally 1600°C, to provide enough superheat for tapping the molten iron product:"

Jan 1, 2011

By C. Peter Hayes

The world continues to change and with it the supply of minerals and metals, the location of centres of production of primary metal and the increasing levels of metals and materials recycling. New technologies are being developed to meet the ongoing search by industry for lower costs, cleaner production and new markets. To keep abreast with these changes, and to utilise fully, the potential benefits of these technical advances, the industry will need a professional workforce having different knowledge, skills and professional attributes than in the previous millennium. What are these skills and attributes? How to best attract and develop the metallurgists of the future, and provide for the ongoing educational and research needs of the industry?

By Bingliang Gao, Junli Xu, Michal Korenko, Jinzhao Guan, Liangxing Li, Zhongning Shi, Zhaowen Wang, Aimin Liu

Al-Si alloy, a precursor of solar grade silicon, was prepared by direct electrolysis in cryolite molten salt at 950 oC using high purity silica as material, liquid aluminum as the cathode and high purity graphite as the anode. The electrochemical behavior of Si(IV) ion was investigated using cyclic voltammetry method. The electrolysis products were characterized by XRD, SEM/EDS and ICP. The results indicate that the reduction process of Si(IV) on tungsten electrode is a two-step process and there is about 0.6 V gap between the two steps. The contents of boron and phosphorus in the aluminum-silicon alloy are 3 ppmw and 8 ppmw, which will make the directional solidification purification effectively and reduce the cost of preparation solar grade silicon from metallurgical grade silicon.

Jan 1, 2015

By Christopher R. Casias

A basic methodology is presented (employing both standard and theoretical assessment, analysis. and data interpretation techniques) for classifying waste containing trace levels of radionuclldes. Despite increased regulatory requirements for handling. transporting. and disposing of such waste: (I) no formal characterization methodology has yet been Implemented. and (2) no limits have been set to define the point at which a waste material is considered to be low-level and below which it Is "below regulatory concern" (BRC) or can be considered to contain no more than a diminimus level of radioactivity (i.e . is nonradioactive). 'I1le concept of diminimus limits specific to waste streams and waste forms is introduced. and a mechanism fur evaluating waste In relation to BRC and diminimus limits is outlined. This methodology can be used to perform a complete and adequate characterization of waste for classification according to its level of radioactivity.

Jan 1, 1992

By Pan Cao

The process of reduction roasting of nickel laterite with rotary hearth furnace combined with magnetic separation becomes a very potential way to prepare ferronickel alloy, especially for the low grade nickel laterite ore. In order to realize this new process, the effect of roasting temperature, time and additive on the reduction degree were investigated in the laboratory experimental. The results indicated that the recovery rate of Ni increased with the roasting temperature increasing to 1500°. Most of nickel and a spot of iron are selectively reduced with adding 25.19% SiO2, 6.42% coal, and roasting for 60min at 1500℃. Then conventional magnetic separation was carried out. The content of Ni and Fe are 7.50% and 59.08% in ferro-nickel nugget prepared by this method. And the recovery rate of Ni is 90.91%, which indicates that a high recovery of ferro-nickel from nickel laterite ore is achieved indeed.

Jan 1, 2014

By Jewel Gomes

Green rust is an important intermediate in oxidative transformation of Fe(II) phase. This unstable compound contains a mixture of ferrous and ferric hydroxides that belong to a family of minerals known as layered double hydroxides (LDH). Its general formula is [FeII(6-x) FeIIIx (OH)12]x+[Ax/n-*yH2O] x-, where A is an n-valent anion mainly Cl-, CO3-2 and SO4-2, and in which either the bivalent or the trivalent iron can be replaced for other trivalent or bivalent metal ions. It was first identified as corrosion product, later in soils as a product of interactions between microbes and metals in soils. Due to its high reactivity, it is used in the reduction of organic and inorganic compounds, As removal, and the treatment of acid mine drainage. In this paper, we described the method of electrochemical generation of green rust, its characterization by XRD, SEM and FT-IR, and its implications to electrocoagulation.

Jan 1, 2009

By Yongfeng Jia

Lime neutralization and co-precipitation of As(V) with iron(III) is the most widely used and most economical method for the removal of arsenic from mineral processing solutions and effluents. However, the arsenate fixation mechanism in the coprecipitated solids is not fully understood. It was suggested by various researchers to be a ferrihydrite precipitation process during which arsenate is removed by adsorption on ferrihydrite. In this study, XRD, EXAFS and microprobe were employed for the speciation of arsenic and the effect of various factors on arsenic solubility was also investigated. The results indicate that coprecipitation is a more complicated process than simple adsorption resulting in lower arsenic solubilities. Poorly crystalline ferric arsenate was observed for the first time to be present in the coprecipitated solids. In case of lime as base, there exists some type of Ca-Fe-arsenate association. A general term ?coprecipitate? is suggested to describe the precipitated arsenic-bearing solids instead of those widely used specific terms ?arsenical ferrihydrite? or ?arsenic-bearing ferrihydrite?.

Jan 1, 2005

By Qian Li, Haiyan Leng, Kuo-Chih Chou, Haoyuan Xiao, Zhigang Yu

Magnesium borohydride and Magnesium alanate were synthesized by mechanochemical metathesis reaction. The thermal decomposition behaviors of Mg(BH4)2-nMg(AlH4)2(n=0.5,1) systems were investigated as potential hydrogen storage materials. The results showed that the systems started to desorb H2 at 120 ℃ and desorbed 3.9 wt. and 4.9 wt.% H2 below 300 ℃ when n equals 0.5 and 1, respectively, while individual Mg(BH4)2 started to desorb H2 at 250 ℃ and desorbed only 0.82 wt.% H2. Because of the exist of the Mg(AlH4)2, the isothermal desorption kinetics of Mg(BH4)2 in the Mg(BH4)2-0.5Mg(AlH4)2 systems was 50% faster than that of pristine Mg(BH4)2. In addition, the re-hydrogenation rates also increased 49.4% and 37.9%.

Jan 1, 2015