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By Edgar Vidal

Beryllium metal and alloys have been crucial in the advancement of technologies in space exploration, transportation, national defense, communications, energy, safety and medicine, to name a few. Beryllium is one-third lighter than aluminum and six times stiffer than steel, with unique thermal properties. Demand for this metal is expected to continue to increase as new technologies emerge, hence its efficient and safe extraction needs to be addressed. Current extraction technologies are very complex and energy intensive, but at the same time yield excellent quality metal. In order to develop new or improve current extraction methods, a detailed analysis of current and past extraction technologies must be made. This work intends to compile and interpret most of the research, development and industrial practices used in the production of beryllium, and open the field for innovative extraction methods.

Jan 1, 2006

By Bernard Bonnetot

The potentialities of hydrogen storage using borohydrides are presented and discussed especially in regard to the recoverable hydrogen amount and to the recovery conditions. A rapid analysis of storage possibilities is proposed taking in account the two main ways for hydrogen evolution: the dehydrogenation obtained using thermal decomposition of borohydrides or the hydrolysis of solid or dissolved borohydrides. The recoverable hydrogen is related to the dehydrogenation conditions and the real hydrogen useful percentage is determined for each case of use. The high temperatures required for dehydrogenation, even using catalyzed borohydrides, lead to poor outlooks for this storage technique. The hydrolysis conditions fix the yield of the recovered hydrogen and rule the storage capacity of the dissolved borohydride, the "fuel".

Jan 1, 2006

By Jonathan A. Paul

The most profitable companies in the world recognize that a huge competitive and financial power lies in their intangible assets. The competition to be in command of raw materials and markets is now waged more and more over the exclusive rights to new technology and ideas. The value gained from mining the innovation in your organization and protecting your intellectual property can be enormous. This paper will address the following topics: ? Understanding the connection between your competitive position and intellectual property ? Determining the value of your current portfolio and strengthening protection ? Converting knowledge into assets and adding value to the operation ? Litigation strategies to enforce your position and achieve your business objectives The presentation is designed for company executives and government managers who need to know how to identify and address core intellectual property issues that arise in the minerals, metals and materials extraction and processing industries.

Jan 1, 2006

By M. Dattilo

Research has been conducted over the past three years using the composite anodes versus the lead alloy anodes. The Merrlin composite anodes have shown the improved performance in copper electrowinning versus the lead-calcium-tin anodes. Using the composite anodes a 100-150 mV reduction in anode overpotential has been observed versus the lead alloy anodes in sulfuric acid electrolyte. The composite coating has excellent corrosion inhibiting properties, and reduces or eliminates the formation of manganese oxide scale. Laboratory evidences indicate that, the use of these composite anodes enhances the process of electrowinning by improving the lead alloy corrosion resistance, lowers the electrode potential, reduces the need for cobalt addition, eliminates the anode cleaning, and reduces the generation of acid mist. Field tests are underway.

Jan 1, 1999

By K. Eto, H. Akiyama, T. Iwamoto

The Hikoshima smelter carried out an expansion project in 1997 and increased its production from 59,200 t/y to 71,000 t/y. The leaching process and the casting process had production capacities of 84,000 t/y, but because of the electric power situation in Japan, the production capacity in the electrolysis process was limited to 59,200 t/y to justify the production cost. Electrolysis was the bottle neck of the plant. In order to eliminate a part of this bottle neck, and considering the electric power situation in Japan, a way to increase the production during the time when the electric power rate is low was sought. In practice, we increased the number of cells by 36, and further improved the operation procedures in the cellhouse. For example, we improved the working efficiency of the cells, improved the productivity during the night time, decreased the unit power consumption and improved labor productivity. Accordingly, this paper describes the recent operations at the Hikoshima plant.

Jan 1, 2000

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 Thomas Frost

In this time of market globalization, many industrial companies are including detailed arbitration clauses in their international contracts, in order to avoid the potential costs, delays, and uncertainties of litigation in foreign courts. Arbitration is less expensive and more flexible, procedurally, than court proceedings, and arbitral awards enjoy much greater international recognition than judgments of national courts. More than 134 countries have signed the 1958 United Nations Convention on the Recognition and Enforcement of Foreign Arbitral Awards, known as the "New York Convention", which facilitates the enforcement of arbitral awards internationally. There are several other similar arbitration conventions that provide for the enforcement of cross-border arbitral awards. Additionally, arbitral awards are not subject to appeal, whereas judgments of national courts are routinely subjected to a lengthy appeals process, and there are very few viable bases to challenge arbitral awards. This discussion will review key considerations in drafting arbitration clauses, including choice of law and choice of forum considerations; issues surrounding the selection of arbitrators; the discovery process; presentation of evidence; and enforcement of arbitral awards.

Jan 1, 2006

By Rumen Markov, Lubomir Kuzev

"The treatment technologies for municipal solid waste (MSW) are effective mainly for components sized over 40 – 50 mm. This fraction is separated by screening in the beginning of the process. Usually the undersized product is deposited without additional treatment. Its quantity is variable from several up to 30 – 40 % of the total MSW. Both oversized and undersized fractions are formed by all types of primary matter. Adapted technologies from mineral processing will provide a suitable technology for treatment of MSW under 40 – 50 mm. The MSW content depends on the geographical location, the degree of urbanization and other factors. The methods can be applied for separations of different components suitable for recycling or other utilization are: • Separation by density; • Separation in thin liquid layer; • Selective grinding and screening; • Flotation, etc. Introduction Municipal solid waste (MSW) represents an integral part of public urbanization. However, there are some drawbacks stemming from MSW, in regard to its collection, transport and elimination. Different approaches exits worldwide for tackling the problems arising from MSW. For a short period of time, the attitude towards MSW has evolved in several levels, each further level being characterized by higher percentage of utilization of MSW components. Thus, the bottom line has been shifted from safety storage towards processing that includes recycling and maximal utilization of MSW components. Technologic processes applied for treatment of MSW have a common feature – that the fine components, having sizes under 20 mm, 30 mm, 40 mm, or 50 mm are excluded from treatment process trough screening, and in most cases diverted without any additional treatment to preliminary prepared storage sites. MSW in Sofia – current situation The amount of MSW collected daily in Sofia as around 1000 t/24 h. It is stored or baled. Baling is a spare alternative of storage, since baling insures only temporal keeping of MSW, till the building of suitable storage site where the bales will be transported and buried. The morphologic composition of MSW in Sofia has been determined several times at different time intervals, from some Bulgarian organizations as well as from the Japanese organization JICA. So far, however, there is still a lack of enough systematical and comprehensive study. Generalized results from the studies on the MSW components, as well as some important parameters are given in Table 1."

Jan 1, 2008

By Maurizio Marezio Bertini

Ammonia - ammonium sulfate solutions were sparged in a glass reactor with a SO2/O2 gas mixture (2% SO2 and 98% O2) to leach copper from pure chalcopyrite and chalcopyrite concentrate. The SO2/O2 mixture produces higher and faster extractions than O2 by itself. The effect of temperature, particle size and free ammonia concentration was investigated. The fastest and highest recoveries were obtained at 80 oC from a chalcopyrite concentrate with a d80equal to 13 m, with about 83 gpl free ammonia, an average pH equal to 8.75 and a stirring speed of 500 rpm. The extraction process was controlled by diffusion through a product layer, according to the shrinking core model, with an activation energy of 41 kJ/mole.

Jan 1, 2003

By William Ewing

Copper is rapidly being adopted by the semiconductor industry as the interconnect material of choice. The aqueous processing techniques used generate wastes such as spent electrolyte from electroplating, electroplating rinse water, copper solutions from removing copper from the back of the wafer and CMP waste streams. We are examining the use of chelating resins as a means of recovering copper from these streams within the processing plant, thereby allowing recycling of process water and minimizing hazardous waste disposal costs. We have examined the effect of model plating additives (and other organic complexing agents) on the efficacy of Dowex M4195. Although these might have had a significant effect, commonly used electroplating additives polyethylene glycol (PEG), benzotriazole (BTA), thiourea, glycine, and 3-mercapto-1-propanesulfonate (MPSA) each had little or no effect on the ability of the resin to chelate copper and remove it from solution. This suggests that Dowex M4195 could be useful for treating waste solutions of rather variable compositions.

Jan 1, 2003

By Michael J. Nicol

One of the preferred methods for the recovery of gold from refractory gold ores and concentrates involves pressure oxidation in acidic solutions. The main refractory gold-containing minerals are pyrite and arsenopyrite and there is evidence that the presence of even small amounts of chloride can inhibit the oxidation of these minerals and also substantially reduce the recovery of gold. In this paper, the results of a study of the anodic (oxidation) and cathodic (reduction) behaviour of pyrite electrodes in acidic sulfate solutions containing ferric ions at different chloride concentrations and temperatures up to 200oC and pressures of 2000KPa are presented. The electrochemical studies have been complemented by pressure oxidation experiments on a refractory gold concentrate. Results have shown that, as the chloride concentration increases, the anodic reactivity of pyrite is largely unaffected but the rate of the cathodic reduction of iron(III) decreases. The rate of oxidation of a sulfide concentrate and the recovery of gold by cyanidation of the residues decreases at high concentrations of chloride.

Jan 1, 2003

Environmental and public concerns and the banned use of cyanide for the recovery of gold in some parts of the world have heightened the search for an alternative lixiviant to cyanide. Thiosulfate appears to be the most promising alternative to cyanide due to thiosulfate being non-toxic, relatively cheap compared to cyanide and generally gold recoveries are similar to those of cyanide. The most widely researched thiosulfate process is one where copper ions and ammonia are added to the solution. This paper reviews the leaching of gold in thiosulfate solutions and the contributions of the research at Monash University to the understanding of the gold oxidation reaction in thiosulfate solutions, the solution chemistry when copper ions, ammonia and oxygen are present, the influence of the changing solution chemistry on the gold leach kinetics, and the application of thiosulfate in the leaching of gold from ores. It is clearly shown that the gold oxidation rate is hindered in thiosulfate solutions. In the presence of copper ions the gold oxidation rate though is significantly enhanced and thus is why copper(II) is more effective than other oxidants in the thiosulfate leach system. The copper-ammonia-thiosulfate leach solution chemistry is shown to be very complex, especially in the presence of oxygen as the rate of thiosulfate oxidation increases and the majority of the copper ions are not maintained in the copper(II) oxidation state. The thiosulfate oxidation rate must also be maintained low as an intermediate thiosulfate oxidation product hinders gold leaching. In optimising the recovery of gold from ores with copper-ammonia-thiosulfate leach solutions it is important to evaluate and minimise any negative effect an ore may have on the leach solution chemistry and hence gold leaching.

Jan 1, 2003

By Katsunori Okaya, Gjergj Dodbiba, Hiroyuki Ono, Toyohisa Fujita, Seiji Matsuo

"In an attempt to raise the copper grade of Printed Circuit board (PCB) by removing other components, carbonization treatment was investigated. The crushed PCB without surface-mounted parts was carbonized under nitrogen atmosphere. After screening, the char was classified by size into oversized pieces, undersized pieces and powder. The copper foil and glass fiber pieces were liberated and collected in undersized fraction. The liberation of copper foil from the oversized pieces was also investigated. The copper foil was liberated easily from glass fiber by stamping treatment. Liberation rate of copper foil was high at high carbonized temperature. The experimental results indicated that 90% of oversized char was liberated and the copper foil recovery from PCB carbonized at 1073K was 110kg/t. The copper recovery from char powder by flotation was also investigated. 15% of the copper grade and 80 % of the copper recovery were obtained, whereas the removal rate of silicon was 55%.IntroductionWaste Electrical and Electronic Equipments (WEEEs) should be recycled because they have many kinds of valuable materials and most WEEEs include Printed Circuit Boards (PCBs). In Japan, about 30 km2 per year of Printed Circuit board (PCB) has been produced [1], PCBs are normally separated from WEEEs and picked up by hand and sold to non-ferrous metal market because PCBs include high grade of copper and other precious metal such as gold, silver and palladium [2]. However, PCB also has impurities such as silicon, aluminum and calcium which are slag materials in non-ferrous smelting process, and other harmful elements such as lead, bromine and antimony. Low grade PCBs are sold after removal of invaluable parts or sometimes land filled without any treatment"

Jan 1, 2011

By Mark E. Schlesinger

A substantial database exists for the thermodynamic properties of many antimonide compounds, but these have rarely been compiled or critically discussed. An abbreviated version of a full?scale review of the thermodynamic properties of binary antimonide compounds is presented, focusing on the choice of experimental techniques.

Jan 1, 2006

By Linping Yu

A simplified ED process was developed for organic acids recovery from cyclohexanone waste in this paper. In this regard, the one-stage ED was investigated directly without pretreatment, such as ion-exchange or nanofiltration to removal of foulants. The current efficiency and the energy consumption in the ED process for the recovery of carboxylic acids from cyclohexanone waste is theoretically analyzed and experimentally tested. The concentration of recovered carboxylic acid is related to many parameters and still needs more work to be determined.

Jan 1, 2009

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By J. Brent Hiskey

Carefully prepared gold-bearing arsenopyrite samples from different geographical locations were leached in alkaline cyanide solutions using an electro-dissolution technique. Special precautions were taken to utilize monosized and thoroughly characterized samples. The rates of iron, arsenic, gold and silver dissolution were measured as a function of temperature under controlled conditions in sodium cyanide media.

Jan 1, 1989

By Reinhold G. Schulze

Thiourea is being applied as an industrial leaching agent for gold and silver only in a few cases. A GIP technique was developed which eliminates most of the obstacles against its use. Omission of an acid treatment and mild conditions for precious metals stripping from the loaded carbon simplifies process conditions in comparison to cyanide CIP technique. Examples are given.

Jan 1, 1989

By Mikael Ersson

A fundamental mathematical model of lance blowing on a bath surface has been developed with a purpose to increase the understanding of various phenomena in top blown oxygen converters. The model is based on the Navier-Stokes equations and turbulence is predicted using the k-model. In the present model the deformation of the liquid surface, caused by the impinging gas jet, is described using a VOF formulation. The mathematical model results have been verified by comparing predicted penetration-depth data with experimental results from physical model trials. The fluid dynamic modeling has also been coupled with the thermodynamic modeling to predict the reaction rate/distribution occurring in the vessel. The focus has been on carbon and a qualitative comparison of the predicted carbon content in the hot spot area and in droplets with experimental data from laboratory trials has been done.

Jan 1, 2006

By Julian Szekely

A review is given of the current metals processing operations, where electromagnetic forces play an important part in affecting the performance of the system. These include arc furnaces, plasmas, the Hall Cell, electromagnetic stirring and others. These considerations will be extended to discuss what new frontiers may be breached by the intelligent application of electromagnetic phenomena. The topics discussed will include magnetic flow control, levitation melting and cold crucible melting and refining.

Jan 1, 1988