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By Jian Li, Guo Chen, Bingguo Liu, Hongying Xia, Jinhui Peng, Libo Zhang

"Decomposition of ammonium tetramolybdate to prepare Mo03 using silicon carbide crucible in microwave fields was investigated. The results were analyzed Using TG-DTG and X-ray diffraction. Meanwhile, the effects of heating rat, material thickness, socking time, socking temperature on the structure of preparing Mo03 were studied. TG-DTG curves show that the decomposition process of ammonium tetramolybdate is only one stage, in the temperature range 300-350°C, whose begin to decompose when temperature increases beyond 300°C. The molybdenum trioxide was prepared by thermal decomposition. The quality ofMo03 was not affected under the heating rat is 12°C/min. It was beneficial for decomposition ratio with the lower material thickness, longer soaking time, and higher soaking temperature. XRD curves showed that it is viable method for preparation of Mo03 by decomposition from ammonium tetramolybdate in microwave fields.IntroductionMolybdenum is widely used in national defense, aviation, industrial and agricultural production as rare refractory metal. Molybdenum trioxide is vital raw materials for the process of preparation of molybdenum. The traditional production technology of molybdenum oxide is that ammonium tetramolybdate is calcined in rotary kiln or 4-tube furnace [J,2J. But the longer production time, the higher production cost, the lower furnace thermal efficiency, and bigger the energy consumption, especially the powder is easy to leak, the working environment is poor by using rotary kiln [ 3 l _ The particle of molybdenum oxide is non-uniform by using 4-tube furnace because of the uneven temperature of every tube and the poor exhaust of boat bottom [4l _ However microwave heating is quick and uniformity, it is a meaningful research that the microwave is used in the process of calcining ammonium tetramolybdate."

Jan 1, 2013

By E G. Prado

We have confirmed on bench scale the removal of chlorides and alkalies (+95%) and over 2/3 of the zinc, lead and cadmium from EAF dusts. This has been achieved with arrononium acetate solutions alone, or with combinations of water wash, amonia-ammonium carbonate and ammonium acetate solutions. Also confirmed are the process routes for the recovery of the aforementioned elements into marketable products. The technology involves the complete recycling of the reagents. The FAF residue is returned to the electric furnace without risk of impurities buildup. Commercial scale testing with the recycled dust was satisfactory, including quality of the slag and its behavior during the melting stage. A cursory feasibility evaluation is presented.

Jan 1, 1994

By R. H. Hanewald

The INMETCO process has been modified so as to recover nickel. chromium and Iron from a wide variety of metal containing waste-streams. This now includes the recovery of metals from spent acid solutions such as chromic acid etching I1quids. nJcke1 and chromium plating solutions; stainless and superalloy pickling solutions. etc. In addition. hazardous electric furnace stainless steel and. superalloy baghouse bags can be processed so as to recover the valuable metall1cs. A detailed review of the above new recovery techniques w1ll be discussed as well as the current operating methods used at INMETCO.

Jan 1, 1992

By Bo Jiang, Jiusan Xiao, Hongmin Zhu, Kai Huang, Shuqiang Jiao

Carbothermal selective reduction of simulative titanium slag and various titanium raw materials were presented and SiO2 was found to be partially reduced, forming a series of Fe-Si alloys during the process. Thermodynamic analysis of the selective reduction between TiO2 and SiO2 was performed using HSC 6.0 software, then a series of equilibrium experiments were designed and presented. The activity of Si reduced from SiO2 was affected by the presence of Fe reduced from FeOx and the generation of Fe-Si alloys, promoting the reduction of SiO2 in the whole process. The results of experiment are in great accordance with the calculated data obtained from thermodynamic analysis.

Jan 1, 2016

By Antti Roine

Sulfidic zinc concentrates are usually roasted in a fluidized bed furnace into sulfur-free oxide form. Metallic zinc is produced from this oxidic calcine using hydrometallurgical leaching, solution purification and electrowinning stages. The roasting step is necessary because zinc oxides are easier to dissolve using traditional leaching methods than zinc sulfides. The Kokkola Zinc smelter uses various types of zinc concentrates and secondary materials as feed mixture. This makes it difficult to find optimum process parameters for the roaster when the composition and particle size distribution of the feed mixture varies even on a daily basis. Certain conditions may even cause difficult accretion problems or increase the amount of calcine in the process off-gas line excessively. A thermochemical heat and material balance model was developed for process advisor, in order to estimate the effects of different process parameters (temperature, process air coefficient, concentrate feed, oxygen enrichment, water feed, etc.) on the heat balance, roasting temperature and calcine composition. This model was constructed using the heat balance module of HSC Chemistry 4.0 software. The prevailing chemical compounds in the concentrate and calcine were verified using mineralogical analyses and equilibrium calculations. The roasting process seems to operate near chemical equilibrium conditions, if the behavior of the main components is considered. This paper describes briefly the basic principles of the calculation model and outlines the results with several diagrams and discussion. The calculated results were in reasonable agreement with the recent process air oxygen enrichment and water feed test campaigns carried out at Kokkola in 1999.

Jan 1, 2000

By K. Sarveswara Rao

"Any innovative approach made in non-ferrous metallurgical industry centers upon developing new processes, saving materials, improving production quality, and bornagain materials. Aqueous processing is commonly used to treat lean grade or more complex ore bodies. Its sustenance largely depends on energy and environmental compliance including water and wastewater management. The present paper focuses the importance of using particle size distribution and surface area measurements during ammoniacal dissolution of a Cu-Pb-Zn sulphide bulk concentrate and with an overview of the effect of water salinity on the process chemistry and residue mineralogy. Accordingly, an effort is made here to discuss the emerging perspective and highlight the recent successes and trends in terms of energy savings in non-ferrous hydrometallurgy.IntroductionThe nature and structure of the global energy industry is likely to change significantly in the 21st Century. Rabago et al [1] have comprehensively discussed how the mining and minerals industries can adapt to the challenges and opportunities posed by trends and drivers in global energy use. According to the authors, the drivers of sustainability include water, efficient energy use, climate modification, transportation technologies and energy security. Sustainability and competitiveness for the minerals industry will depend on natural capitalism, resource efficiency, new processes, saving materials, improving production quality, born-again materials and the solutions economy. Based on this motivation, the theme of the present paper is centered upon applications as relevant to energy and sustainable development in non-ferrous hydrometallurgy."

Jan 1, 2009

By P. G. Mason

The Getchell property was mined for oxidized gold ore by underground and open pit methods from 1936 to 194.5, by which time known oxide ores were mined out. From 1945 until 1967 sulfide ores were mined and roasted to improve gold recovery with varying degrees of success. In J 983 FRM Minerals, Inc. purchased the property. Since then they have carried out extensive geological exploration to define the size and character of the orebody. The sulfide ore is refractory to direct cyanidation, thus considerable metallurgical testing has been necessary to develop a suitable, cost effective process for its treatment. Wright Engineercs Limited have designed and engineered a gold extraction plant, which incorporates pressure oxidation to liberate the gold and? is scheduled to be commissioned early in 1989.

Jan 1, 1989

By Jin-tao Gao

In order to recover Ti resource from titanium bearing blast furnace slag, a new technology to separate perovskite phase from CaO-TiO2-SiO2-Al2O3-MgO system by supergravity is researched. In the condition of gravity coefficient of 750g, treatment temperature of 1305°C and time of 20min, the significant layers appear in samples which are obtained by means of centrifugal treatment. Along the direction of the supergravity, the volume fraction of perovskite phase increases gradually, and the equivalent diameters of perovskite phase crystals increases with the area approaching to the bottom of the sample. It is indicated that TiO2 is enriched in the bottom of sample as concentrate with a recovery ratio of 74.05% by supergravity treatment.

Jan 1, 2014

By N. Panagiotopoulos

A low-grade (1.06% Ni, 0.06% Co) hematitic type lateritic ore from Triada, Euboea Island, Greece, has been leached with sulfuric acid at atmospheric pressure for the extraction of the contained Ni and Co values. The effect of various parameters, including reaction time and leaching temperature, acid strength, pulp density, etc., on Ni, Co extraction and Fe dissolution was determined. By leaching at 95°C for 4h with a 3N sulfuric acid solution at 25% pulp density, Ni and Co extractions were 82 and 75% respectively, and Fe co-dissolution 28%, yielding a pregnant solution containing 2.7 g/l Ni, 0.16 g/l Co, and 33 g/l Fe. Overall acid consumption was 850 kg/t ore (or 100 kg/kg Nil. Preheating of the laterites at 600°C before leaching resulted in much faster leaching kinetics for Ni, but the final extraction and acid consumption remained unaffected; Fe extraction was not influenced. Three-stage counter-current leaching at 9S°C, using 2N acid strength at each stage and 35% pulp density, reduced acid consumption to 350 kg/t ore (41 kg/kg Nil, and yielded 81% Ni recovery. Percolation leaching of -10 mm laterite at ambient temperature with 3N acid for 7 days resulted in 58% Ni extraction.

Jan 1, 1988

By Kenneth L. Nash

The control of solubility of waste actinide ions, by conversion to highly insoluble mineral phases has been demonstrated in the laboratory. Actinide metal ions are removed from neutral pH solutions by a combined ion exchange-decomposition-mineralization process based on the application of the naturally-occurring hydrolytically unstable.polyphosphate organic compound phytic acid.

Jan 1, 1999

By P. Sergi

A method of characterizing gold ores with respect to processing is proposed. The method includes microscopical examinations to obtain qualitative and quantitative data that relate to processing. The main thrust, however, involves laboratory heavy liquid separation tests, laboratory amalgamation tests, and laboratory cyanidation tests to determine the proportions of gold that can be recovered in a conventional processing operation. Two different Brazilian gold ores: a quartz vein gold ore, and gold in metasediments were tested.

Jan 1, 1989

By S. B. Bortnikova

This paper presents the results of an investigation of the gold-silver oxidized ores at the Salair mine. West Siberia. High losses of precious metals during primary ore processing are the result of outdated technology that is not suited to treat the present ore compositions. The main mineralogical forms of gold and silver and their confinement to different grain size fractions have been determined. About 50% of gold in the slime fraction and 60% of the silver in the form of acanthite that are scattered from the secondary minerals are lost to the waste. The results of these investigations have provided the basis for the recommendation of a new technological process to upgrade the current practice of the gold extraction plant and for methods to reprocess the concentrates.

Jan 1, 1995

By Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa, Viviane Tavares Moraes

"The development of mobile phone technology has increased the replacement of outdated equipments for more modern models, transforming disposal of such devices into a serious environmental problem. Recycling appears as an attractive alternative to minimize the environmental impact of disposing such large quantities. Recycling can be accomplished by treating the printed circuit boards of used mobile phones by using the same techniques used in ore treatments with hammer mill; magnetic separation, electrostatic separation and grain size range. Before performing the recycling process a PCB characterization was performed to identify the fraction with the higher metals concentration/content. This study demonstrated that the electrostatic separation was not the best metals concentration of PCB aiming the recycling, while the non-magnetic residue had presented a more significant metal concentration. Furthermore, after the magnetic separation was possible to separate the following metals: iron and nickel.IntroductionPortable electronic devices have gained increasing acceptance over the last decades. Mobile phones sales in Brazil, for instance, have reached 104 million in 2007, and 128 million in 2008. It is estimated that, around the world, 100 million mobiles are thrown away every year, either because of loss of functionality or because newer models are launched in the market [1,2, 3]. Printed circuit boards in mobile phones are made of many materials, with approximately 83% in weight being metals and fiber-glass, and the balance being plastics pl. Several metals can be recovered from the electronics waste, such as copper, tin, iron, lead, nickel, titanium, aluminium as well as some precious metals such as gold, silver and palladium [4, 5, 6, 7, 8]. Concurrent with the increasing world demand for copper, there average metal content in ores has been decreasing. Economically interesting copper mines used to have 4% metal content, whereas presently, such content is around 1%, i.e., for every 1 ton of ore extracted, only 10 kg are copper [9, 10]. Approximately 33% of printed circuit boards (PCBs) composition is copper, that is, for every 1 ton of PCBs waste, 330 kg are copper [1]. Research in recycling PCB waste focuses on mechanical, electrometallurgy, pyrometallurgical and hydrometallurgical processes [3, 8]. Collecting and recycling obsoletes electro-electronic equipments is very important these days, in order to, not just preserve the non renewable natural resources but also to keep the environment and the population safe from the pollution caused by the toxic materials and heavy metals present in this kind of waste."

Jan 1, 2011

By G. Lissens

In this work the electrochemical combustion of dissolved organic species in a single compartment cell containing a titanium mesh cathode and a boron doped diamond anode has been studied, The organic molecules involved were complexing agents such as EDTA (ethylenediaminetetraacetic acid) or NTA (nitrilotriacetic acid) used in metal plating shops and bright nickel plating bath additives, From batch experiments, it is shown that complete decomplexing of EDTA and NIA is feasible. Complete TOC (Total Organic Carbon) removal from solutions containing 0.01 M EDTA, 0.02 M NTA and bright nickel plating bath additives could also be achieved. Recycling experiments show that decomplexing of EDTA and NTA solutions can be obtained at an average electrical energy input of ~20kWh.kg-1 of complexing agent. Decomplexing rates of respectively 3.l3 mmol.Ah-1 for EDTA and NTA have been obtained, The Instantaneous Current Efficiency (ICE) was 71% for EDTA and 95% by NTA, Simultaneous recovery of Cu from a 0.01 M Cu-EDTA solution has also been evaluated. A solution (1.8 dm3) containing 0.01 M EDTA and 528 ppm of Cu was treated in a single compartment cell at a current density of 2 A.dm-2. 73% of the TOC could be removed and a final copper concentration of 8 ppm was obtained.

Jan 1, 2003

By R. G. Robins

The effective removal of arsenic(V) from process streams and waste waters by precipitation with excess iron(II1) is sometimes attributed to the formation of basic ferric arsenates. The authors have investigated this system extensively using a variety of techniques and conclude that the solid phase produced is iron(II1) oxyhydroxide (ferrihydrite) with arsenic(V) adsorptively bound to the 2-3 nm particles.

Jan 1, 1992

By George Owusu

A study has been carried out on the use of solvent extraction, instead of the traditional zinc dust cementation process, to remove copper from concentrated zinc sulphate leach solutions. In a series of experiments using plant solution containing 1.9 g/L Cu, 2 g/L Fe, 173 g/L Zn, 7.9 g/L H,SO,, 0.25 g/L Cd, 15 mg/L Co etc. and LIX 622 in SX-1, up to about 97-98 % of copper present in the zinc sulphate leach solution was extracted with negligible co-extractions of zinc, iron, cadmium, cobalt, etc. pH modification was not required for this reagent. The copper loaded organic was almost completely stripped using 150 g/L sulphuric acid. Investigations into the effect of any possible organiclextractant contamination on zinc electrowinning showed (if any) little effect on current efficiency if the organic contamination is less than 45 ppm; current efficiencies of 95-97 % were obtained. At organic contaminations higher than 45 ppm, the current efficiency dropped to about 92- 94 %. Visually, the organic-contaminated cathode sheets had rough surface morphology, becoming more intense with increasing organic concentration, compared to the non-contaminated cathode sheets.

Jan 1, 1998

By G. G. Richards

"The slag fuming process has operated for close to 70 years to recover zinc from lead blast furnace slag. The process is normally carried out through the batch treatment of slag by submerged injection of coal and air. Within the bath the coal acts as both a reductant, to reduce Zno to zinc vapour, and a fuel, to maintain bath temperature during the endothermic reduction process. The partition of coal between the slag, combustion and bypass is dependent on factors such as bath depth and injection pressure. The option of continuous fuming has been pursued at the D. Blagoev smelter in Bulgaria using heavy fuel oil as reductant/fuel. There has, however, been little attempt at commercial continuous fuming with coal. This paper presents an analysis of a coal-based continuous slag fuming furnace. The data on the Plovdiv fumer is used as a reference point. Critical design criteria for continuous fuming include the slag feed rate, degree of coal combustion and furnace size. Mathematical modelling analysis suggests that continuous fuming with coal can achieve respectable zinc/coal ratios.IntroductionThe slag fuming process was developed in the early part of this century to recover zinc from non-ferrous smelting slags [1-3]. The majority of installed furnaces were put in place to fume zinc from lead blast furnace slag on a batch basis. In most cases coal is used to effect reduction of zinc oxide, but one furnace uses natural gas [4] and, in a curious twist, a continuous fumer was developed based on fuel oil [5].Given the general nature of blast furnace lead smelting, it is not surprising that slag fuming has remained a batch process, in spite of the advantages that could be gained by moving to continuous fuming. Blast furnaces are usually operated as relatively independent units, and tapping has traditionally been done into ladles. The presence of a crane aisle makes direct coupling of the blast furnace to a slag fumer difficult, especially in a retrofit situation. Furthermore, steady-state blast furnace operation is not easy to achieve. The size of these furnaces and the nature of their feed make it difficult to guarantee constant operation."

Jan 1, 1996

By B. Garcia-Egocheaga, J. Rutten, N. Goicoechea, U. Meurer, Mager K., W. Saage, Simonettim F.

Because of the increasing use of zinc as an active and passive anticorrosion agent for steel, leading to constantly growing return rates of galvanized steel components, especially through the automotive industry, major Electric Arc Furnace (EAF) flue dust amounts with higher zinc contents will accumulate in future. Landfilling of steel plant flue dusts is no longer allowable for ecological reasons. These dusts are classified as hazardous by law. Waelz technology is safe and reliable. The range .of treatable feed materials has been extended by process modifications and state-of-the-art offgas technology. Waelz oxide, the product, is delivered to metal smelters for zinc production and the byproduct, Waelz slag, can be used in road construction. Despite the fact that Waelz technology is among the best available techniques (BAT), it is continuously being optimized further with respect to energy input, product and offgas quality in order to comply with the ever more stringent environmental regulations. However, if these flue-dusts are treated, the loops between the steel and the zinc industry can be closed by reusing recovered zinc which in tum leads to savings in natural resources and a more reasonable use of landfills.

Jan 1, 2000

By L. Sh. Tsemekhman

The results of laboratory, large-scale laboratory and commercial scale investigations regarding the process of slag melts cleaning by oxidizing-reduction gas mixtures with a wide range of Po2 and the use of matte of various compositions as an extracting phase are presented. The copper, nickel and cobalt behavior during the cleaning process has been studied based on SEM and x-ray Microprobe of the quenched slag melts. The general cleaning mechanisms have been found. On the basis of the obtained data the most efficient cleaning methods have been proposed.

Jan 1, 2003

By T. H. Jeffers

The U.S. Bureau of Mines' Salt Lake City Research Center. has developed porous polymeric beads containing immobilized non-living biological materials for extracting metal contaminants? from wastewater&. Immobilized biological materials include peat moss, algae, biological polymers, and other materials that demonstrate high .affinities for heavy metals. The beads, designated as BIO-FIX beads, have distinct advantages over traditional methods of utilizing biological materials in that they have excellent handling characteristics . and can be used in conventional processing equipment or low-maintenance systems.. Toxic metals such as copper, cadmium, zinc, lead, and mercury are several of the many heavy metals effectively removed from mine wastewater& using B'IO"FIX beads. Continuous cyclic testing indicated that the beads continued to produce treated effluents which met National Drinking Water Standards (NDIJS) after 175 loading-elution cycles, Adsorbed metals were removed from the beads using dilute ?mineral .acids. In many cases" the extracted metals were further concentrated to enable processors to reclaim the metals, thus minimizing the generation of a hazardous sludge. Tests indicated that use of the beads in a low-maintenance system was particularly effective for treating remote acid mine drainage waters? and small toxic seeps from hardrock mining districts ..

Jan 1, 1991