Search Documents

By T. H. Eyde

Several hundred natural zeolite deposits occur in Tertiary and Cretaceous age formations of the western United States. Most of the large deposits are altered vitroclastic tuffs. Many of these deposits consist of a matrix of a high purity zeolite mineral or minerals in which fragments of unaltered rock are imbedded. These deposits represent an extensive resource of zeolite minerals which can be beneficiated to a consistently uniform, high quality product. The beneficiated natural zeolite products will possess many advantages over the selectively mined, unbeneficiated natural products currently being produced. These advantages will include: uniform particle size, high purity, consistent quality, high brightness, low iron content, high attrition resistence, uniform cation exchange and adsorption capacities, and low price.

Jan 1, 1981

By Jorge Alberto Soares Tenório

Electronic components have precious metals like Au and Ag. These metals have a high performance in electric conductance. The recycling of the scrap, however is too difficult because of the presence of other metals like Fe, Al, Zn, Sn, ceramics and plastics, all together in electronic components. The aim of the present work was to define one way for physical separation to have metallic non-ferrous concentrates. It was used three kinds of scrap. I was used conventional equipment for mineral processing like hammer mill; screens, electrostatic and magnetic separation.

Jan 1, 1997

By Melvin A. Jennings

Ion-exchange technology for precious metals recovery is at a turning point. Some very exciting technology has been developed in the past five years which should lead to commercialization of the process. Ion-exchange will allow not only for the recovery of gold and silver, but also will allow for the recovery of cyanide form plant tailings. This process may soon be competitive with Merrill-Crowe for silver and once this occurs, it will become the process of choice.

Jan 1, 1991

By Wan Pu

Chrysotile asbestos samples from different mines have been studied by SEM and TEM, including high resolution electron microscopy, to find reasons for differences in physical properties of different types of asbestos fibres. The results show that the inner diameters of fibre tubes and the lattice images of fibres are different for soft and hard asbestos fibres. These differences are related to temperatures and geochemical conditions during the growth of chrysotile asbestos.

Jan 1, 1989

By He Zhi-jun, Ning Zhe, Pang Qing-hai, Zhang Jun-hong, Zhan Wen-long

The effect of microwave irradiation on grinding property of coal was studied by using Hardgrove grindability index tester. Superior grindability of coal was obtained to varying extent after microwave irradiation treatment. The variation in microstructure of pulverized coal during microwave irradiation was observed by utilizing scanning electronic microscope (SEM). The results indicated that the different microwave absorbance of minerals and carbon matrix led to cracks on their interface, by which coal particles were further pulverized and therefore the granularity of coal powder was reduced. Due to the different formation process of various coals, bituminite and anthracite are very different in physical and chemical properties. According to the content of coal pulverization, it can found that microwave irradiation has a stronger pulverizing effect on bituminite in comparison to anthracite.

Jan 1, 2016

By Katsuyasu Sugawara, Takuo Sugawara, Shin-ji Abe, Tadakazu Kagami

"In order to clarify the mechanism and to obtain the fundamental data for heavy metal recovery from an incinerator ash by chlorination, pure chemical reagents, zinc oxide and lead oxide or the fly ash blended with calcium chloride and silicon dioxide were heated up to 1000°C in a nitrogen stream. Thermogravimetric curves of the samples with the chlorinating reagents indicated that solid-liquid reactions accelerated the chlorination and release of metals from the solid phase. The formation of liquid phase of calcium chloride played an important role on effective recovery of zinc and lead at lower temperatures below 800 °C. Although zinc and lead could be decreased in the incinerator ash without chlorinating reagents, addition of chlorinating· reagents enables the removal of metals in high extent· at lower temperature.IntroductionFly ash is discharged about 3,000 tons/day (about 110 million tons/year) from incinerators of municipal solid waste in Japan and mostly fly ash is disposed in landfills. Fly ash includes heavy metals e.g. zinc and lead. Since untreated fly ash caused hazardous leaching problems, Waste Disposal and Public Cleaning Law was revised in 1992, fly ash being designated 'specially controlled' general waste. Fly ash must be disposed by the following suitable, intermediate four methods: [I] Cement- Solidified Method, [2] Immobilized Chemicals Method, [3] Melting Solidified Method, [4] Acid Leaching Method, permitted by the Ministry of Health and Welfare, Japan."

Jan 1, 2000

By I. Iwasaki

Flotation characteristics of pyrrhotite by itself and in complex sulfide ores are reviewed with respect to the effects of oxidation, grinding media and other electroactive minerals.

Jan 1, 1988

By Lifeng Zhang, Zineb Benouahmane, Yaqiong Li

Experimental oxidation tests at high temperature (1000-1200 °C) on SiC samples have been respectively performed under wet and dry air atmosphere for different holding times. The thickness of thermally grown oxide was experimentally measured by DEKTAK Stylus Profilometry. The results showed that the oxidation rate was increased with temperature and holding time, corresponding to a passive oxidation regime which led to the formation of SiO2 layer. The sessile drop method was employed in order to measure the contact angles between Si and SiC at high temperature. Contact angle can be varied from 39.6° to 75.6° by controlling the atmosphere. The deoxidation of the oxide layer and infiltration of liquid silicon caused a decrease in the contact angle.

Jan 1, 2016

By Kimura. E.

Continuous estimation of phosphorus content of molten copper is required to produce phosphorus deoxidized copper in a continuous casting operation. The phosphorus content of molten copper was related to its electric resistivity, which was measured by the four-probed technique with a specially-shaped cell. In a laboratory scale, the linear relationship between the above factors was confirmed in the temperature range of 1083OC through 1200°C. The phosphorus concentration range measured was from 40 to 500 ppm. The phosphorus content was monitored successfully by measuring the electric resistivity of the molten copper in the distributor of a continuous caster in an industrial scale.

Jan 1, 1992

By Juan B. Cabezas

"The favorable characteristics and workability of plastics as a replacement of wood, lead, stainless steel, asphalt and other materials are described. Various types of plastic have proven to be the most favorable choice for handling a variety of acidic, alkaline and organic solutions, as well as pulps, chemical wastes, slurries or tailings for impoundments. The material origin of various plastics, methods of manufacturing and specifications applied to leaching solutions are discussed, including availability and costs. Examples of select plastics are considered for use as alternatives of other materials under severe environmental requirements.IntroductionHydrometallurgical processes applied to gold recovery, as well as other metals, require the use of strong solutions of alkaline, acidic or organic nature, and may also include a variety of materials with extraneous characteristics and complications for handling in storage.The technology of leaching has been in use for more than 100 years, but the applications of leaching processes in metallurgy have become more commonly used in the last 15 years. Suitable materials for the construction of containers, launders, piping, and various accessories, to be used in the handling of leach solutions or slurries, have become a serious problem. Various metals such as brass, lead, stainless steel, etc., and non metallics including wood, clays, glass, rubber, ooncrete, tars or miscellaneous compounds have been tried in the past with serious limitations in workability and resistance to wear and corrosion. For example, the use of metallic, wooden or glass piping systems would require extraordinary shop maintenance to keep such systems in operation"

Jan 1, 1997

By Zuomei Jin

A laboratory study was conducted on the separation of Zn, Pb, Cu and Ag from a finely dissem-inated interlocked silver-rich multimetal sulphidc ore. These are often difficult to separate from each other by flotation. The thermodynamic calculations of Zn-S-O, Cu-S-O systems at different tem¬peratures were presented on predominance diagrams. Based on these diagrams the optimum temperature and gas composition were selected for roasting. The results of separating Zn, Cu from calcine by neutral leaching and acid leaching were found to be satisfactory. The distribution of silver in the roasting and leaching processes were tested. A flow sheet was proposed.

Jan 1, 1993

By T. Nakamura

TiO2 and Ti/TiO2 thin films were deposited on a quartz substrate by laser ablation of TiO2 and Ti targets using Nd:YAG pulsed laser. After sulfurization of the TiO2 film in H2S or CS2 gas at 1273 K for I hour, the surface atomic structure was changed. Furthermore, the Tirri02 film was successfully prepared by the subsequent ablation of Ti and Ti02 targets. The morphology and structure of the films were characterized by XRD, XPS and AFM analyses.

Jan 1, 2003

By T. Inami

The chlorine leach of the anode slime was studied in order to improve the treatment process at the Niihama Nickel Refinery. The anode slime originates from the nickel matte electrorefining and, contains 3-5% of nickel as sulfides. A comparative study has been conducted on the filter cake resulting from the sulfur filtration of the molten anode slime. The kinetic factors of the chlorine leach such as temperature, grain size were defined. Under the optimized condition, 70-80% of the nickel is recovered from the slime or filter cake. On the basis of these results, the chlorine leach process for the treatment of anode slime has been established. The leaching plant has been installed and successfully operated since 1986.

Jan 1, 1988

By D. J. Wang

Based on the thermodynamic arid kinectic aspects, the vaccum distillation processes for the separation and recovery of metals from wastes are analyzed. As to the separation criteria, The separation coefficient and equilibrium composition relation between vapor phase and liquid phase are the bases of recovery of metals by vacuum distillation, The vaporization rates and condensation mechanisms are also discussed. Some experimental results which deal with metals-containing wastes are described and the performances of a new kind of horizontal vacuum furnace are introduced, which demonstrate that , vacuum distillation may be a prospective technique for circulation and regeneration of some non-ferrous metals from industrial wastes.

Jan 1, 1996

By Seong-Jong Kim

The formation behavior and corrosion characteristics of anodic oxide films on pure Mg and Mg-AI alloys were investigated focusing on the effects of anodizing potential, Al content, temperature and NaOH concentration. Pure Mg and Mg-AI alloys were anodized for 10 min at 3, 10, 40, and 80 V in NaOH solutions. Mg(OH)2 was generated by an active dissolution reaction at the surface of the specimen and the product was affected by temperature while MgO generation increased with NaOH concentration. Moreover, the current density after anodizing for 10 min at a constant potential decreased with increasing AI content in Mg-AI alloys,

Jan 1, 2003

By Cleusa Cristina Bueno Martha de Souza

Hydrometallurgical techniques for processing metals are becoming an efficient method for recovering metals. Although batteries' manufacturers have got rid of mercury content, some efforts have been made for recovering other metals enclosed in the battery formula. This paper discusses the bench scale experiments in the purification process of leached solutions from alkaline spent batteries. After leaching process using sulfuric acid as leachant, the solutions containing Fe, Cd, Pb, MIl, Zn and K were neutralized to precipitate iron hydroxide. In a second step, the purification experiments were carried out with excess of zinc dust to try to remove Cd while Mn and Zn still remain in the solution to be recovered in an electrolysis stage. The purification experiments procedures were conducted at different temperatures and times to find out properly conditions from the viewpoint of metals removal After filtration the solutions were submitted to chemical analysis to certify the metals content extracted.

Jan 1, 2001

By Thomas Niehoff, Dave Stoffel

"Energy in the form of natural gas, oil and electricity is expensive and will continue to be a rare resource in the future. Recycling of metals, instead of primary production, is a logical and crucial step towards energy conservation. Energy consumption can be impacted by using advanced combustion systems for metals recycling. Air-fuel combustion has been the conventional method to melt and recycle metals. Global competitive pressures, “greenhouse” gas emissions, and high energy prices force melt shop operations to optimize energy usage and reduce overall operating costs. Oxy-fuel combustion and process technology can be applied to metal recycling operations to meet these objectives. Linde has converted several hundred furnaces from air-fuel to oxy-fuel technology and has extensive experience in optimizing the use of oxygen in furnaces. Additionally, Linde has the process knowledge necessary to avoid costly start-up issues that can accompany the transition to oxy-fuel technology. This paper will describe the benefits and potential issues for conversion to oxy-fuel.IntroductionThe furnace combustion system is the heart of a fossil fuel fired melting process and must be properly matched to the furnace to work as one cohesive unit. Furnaces vary widely in size, shape and features. Rotary furnaces are barrel-shaped and can be designed for tilting or nontilting operation. In a rotary furnace, the products of combustion create a single or double pass through the furnace prior to exiting. Reverberatory furnaces are box-shaped and can also be designed for tilting or non-tilting operation. Reverberatory furnaces are constructed of single or multiple chambers, with or without metal bath movement, and designed for continuous or batch processing. Different furnaces are used for different feedstock materials and products.Furnace combustion systems also vary in many ways. Combustion systems can be of air-fuel or oxy-fuel based technologies, or a combination of the two, resulting in an air-oxy-fuel system. Each of these types of systems has different combustion characteristics which can produce very different results. Here we will describe specific differences in melting processes and their associated energy requirements."

Jan 1, 2009

By Z. Sadowski

The influence of organic acids simple salts and A. niger saccharose and molasses worts on sodium oleate adsorption on the salt-type mineral surfaces has been studied. It was found that salts of organic acids had an effect on the sodium oleate adsorption on barite calcite and magnesite. The collector adsorption on the barite and calcite surfaces decreased under the influence of investigated worts. Experimental data suggest that the biomodification of salt-type mineral surfaces can be used for the selective separation of these minerals.

Jan 1, 1991

By Qin Hua, Xiangru Chen, Qijie Zhai, Yongsheng Yan, Liang Chang

"In this paper, pure bainite ductile iron and their alloying form of 0.2wt% niobium were prepared by a controlled cooling heat-treatment. The effect of niobium alloying on the microstructure, hardness and impact toughness of bainite ductile iron was studied. The results show that adding niobium effectively improves the hardness and toughness of bainite ductile iron. The hardness and the impact toughness of niobium-alloyed bainite ductile iron were investigated by varying the temperature at which samples were fed to the incubator.IntroductionThere are two essential methods to prepare the bainite ductile iron: isothermal quenching [I-31, and alloying [4• 51• Isothermal quenching process is very time and energy consumable, concerned as a high cost technique for mass production. Besides, there are certain limitations on the size and shape of castings in this process. In addition, it potentially harms the environment. As for the alloying, Ni, Mo, and Cu have to be utilized to obtain bainite. However, the large demand and high cost of Ni makes it not feasible in practice.It is well known that niobium can promote the formation of carbon compound, and improves the stability ofundercooled austenite, which is preferred to the increase of the hardenability. Previous studies showed that niobium could refine the grain and improve the mechanical properties of gray cast iron [6-81 • Therefore, in the present work, the effects of niobium and the temperature at which samples were fed to the incubator on the microstructures and properties of niobium alloyed bainite ductile iron were investigated."

Jan 1, 2014

By Francis Vanbellen

Umicore Precious Metals Refining operates an integrated precious metals smelting and refining plant in Hoboken, Belgium. Once a smelter and refiner of complex concentrates, the plant today?s feed consists exclusively of industrial and consumer recycled products, making it the world?s largest recycling facility for precious metals. Unlike the fairy tale of the Frog Prince, it took much more than a princess? kiss to successfully realize this makeover. A completely renewed plant has been built over the past decade. The most visible technological innovation was the commissioning of the Pb-Cu smelter. Its flexibility towards very different types of feed makes it perfectly suited as main entry to the Hoboken flow sheet. A new Cu-leaching & electro winning plant and precious metals refinery make up the Precious Metals Operations (PMO) whose targets are fast throughput and maximized yields for gold, silver and the platinum group metals. The Base Metals Operations (BMO), flexibly process the by-products from the PMO, valorizing ?impurities? like indium, tellurium, selenium and others. Off gas and waste water treatments ensure compliance with strict environmental standards. Precious metals recycling is an art that goes beyond mastering a unique flow sheet. Umicore Precious Metals Refining offers a complete recycling service, taking care of sampling and assaying, metals management and logistics. The quality of this integral service is recognized through the attribution of ISO certifications for our operational activities, sampling and the environmental care. And it?s an art that follows Michelangelo?s experience: ?Art is 5% of inspiration and 95% of transpiration.?

Jan 1, 2006