Search Documents

By Denise Crocce Romano Espinosa

The recycling of waste of electric and electronic equipment (WEEE) is one of the main modern challenges. Among the variety of WEEE, batteries can be set apart due to their composition and their growing demand along with portable devices. The objective of this work is to characterize the thermal behavior of a sample of mixed types of batteries using a thermobalance (TGA). The results of tests showed that Cd evaporated up to 800ºC, Zn evaporation occurred mainly above 900ºC and manganese oxides were pre-reduced to MnO at temperatures above 900ºC.

Jan 1, 2009

By He De-wen

The influence of wastewater containing benzene from chemical industry by technology combined blow-off with Fenton reagent oxidation was experimentally studied. The present results suggest that the technology combined blow-off with Fenton reagent oxidation can effectively remove benzene pollutant in wastewater. The main factors that influence the removal benzene such as temperature and blowing time and volume, pH and reagent dosage of H2O2 and Fe2+ are studied and the optimal experimental conditions are as follows: time 20min, temperature 40i, air-blowing volume 0.4L/min, pH value 5, and H2O2 and Fe2+ dosage 2mL/L and 200mg/L respectively. Under the above conditions, benzene pollutant can be removed up to 97%. Compared to other removal ways of wastewater containing benzene, the technology combined blow-off with Fenton reagent oxidation is more effective and has the advantage of high speed.

Jan 1, 2009

By A. Broussaud

An original methodology has been developed for steady state simulation of selective grinding and mineral liberation in rod and ball mills. Three fundamental aspects of the methodology are presented successively : modeling ore texture, modeling grinding and its selectivity, and modeling mineral liberation. The methodology for modeling ore texture includes the conversion of 2D data into 3D reconstructed information and the use of the BILCO coherent material balance software. The models for grinding Simulation are classified into three levels, corresponding to three levels of available experimental data. All models account for grinding selectivity and for variations of engineering para-meters and operating conditions. An algorithm has been introduced to forecast mineral liberation, compatible with accurate simulation of selective grinding, which generates reasonable results.

Jan 1, 1987

By Vinay Kumar

The disposal of large quantities of electronic scraps generated world wide is causing not only environmental problem but also loss of resources. Therefore, R & D efforts have been made to develop a suitable process for extraction and separation of metals viz. copper, zinc, cadmium and nickel expected from the leaching of e-scraps using solvent extraction process. Different process parameters viz. pH, aqueous to organic ratio, kinetics of extraction, extraction isotherm to establish stage requirement for extraction in continuous mode etc have been studied to optimise the condition for the separation of metals. The studies showed the selective extraction of copper after iron precipitation from the sulfuric acid leach solution of e- wastes containing ~1.0 g/L Cu and minor impurities with 2-hydroxy-5- nonylacetophenoneoxime (LIX 84) above pH 2.0 in single stage. A scheme for separation of cadmium, zinc and nickel has been proposed using di(2-ethylhexyl) phosphoric acid (D2EHPA) under controlled pH of the aqueous solution. The order of extraction was found to be Zn> Cd> Ni.

Jan 1, 2009

By Zhihong Liu

Monodisperse micron size nickel oxalate particles with rhombohedron morphology were prepared from condensed Ni(OH)2 suspension by a novel gel-sol process proposed by one of the authors. Firstly, condensed nickel hydroxide gel was formed by fast adding 1 mol dm-3 NaOH solution into 0.2 mol dm-3 nickel chloride solution, and then oxalic acid solution with a concentration of 0.25 mol dm-3 was dropped into the gel drop wise through a pump equiped with a pH controller under preset pH value, and in this process, Ni(OH)2 gel was converted gradually into monodisperse nickel oxalate sol. The formation of the nickel oxalate particles was found to proceed through a dissolution-recrystallization mechanism from the nickel hydroxide gel. The product particles exhibited rhombohedron like shape with micron size long axis and sub-micron size short axis. The effects of such factors, as temperature, surfactants, et al, were evaluated experimentally on the particles sizes and morphologies.

Jan 1, 2006

By Pratheesh George

Solid state galvanic cell with CaF2 as the electrolyte was employed for determining the thermodynamic properties of Nb-Al binary alloys in the temperature range of 973-1073 K. The activities and activity coefficients of Al in NbAl3 were determined. The experimental procedure and the design and construction of the experimental setup have been also explained in detail. Aluminum activity in NbAl3 increased with increase in temperature and shows a strong negative deviation from ideality. The activities of aluminum in NbAl3 were determined to be 0.0165 and 0.0289 at 973 and 1073 K respectively. The stability of NbAl3 has been compared with other available intermetallic systems.

Jan 1, 2006

By Eun-young Kim

Electrogenerated chlorine leaching of waste printed circuit boards was investigated in hydrochloric acid solutions. The pulverized printed circuit board contained about 37.6% of metal component, in which copper was about 83.6%. The leaching rate of copper was greatly affected by current density and agitation speed. The leaching of copper up to 98% was achieved at 20 mA/cm2, 50?, 180 minutes, and 600 rpm in 1M HCl solution. Increasing agitation and lowering current density enhanced utilization efficiency of electrogenerated chlorine. Leaching of copper was suppressed at initial stage, while the minor metal elements, such as aluminum, lead, and tin, were dominantly leached out.

Jan 1, 2006

By Orlando C. Gaspar

The textures of the ores, the fine mineral intergrowths, the complex distribution of the deleterious minor elements, and the low base metal contents in some ore types, pose many technological problems to the beneficiation of the volcanogenic massive sulphides occurring in the Iberian Pyrite Belt. In particular fine intergrowths of the base metal sulphides with pyrite impose extremely fine liberation sizes (Kao=15 to 25um). The mineralogical, textural and metallogenic studies have provided an understanding of the distribution of vertical and lateral metal zoning in the ore bodies. Mapping of the ore types, carried out by mine geologists, and the metal zoning patterns computed from data base have shown that ore types are distributed as ore lenses, and that vertical and lateral base metal zoning exists in several orebodies. Since ore processing efficiency is affected by ore textures, and because the same mineral often shows different textural features, a relationship between the textures of the feed ores and those of the middlings must be established for all ore types defined at the deposit scale. For supplying, on time, the information needed for the optimization of the concentration processes, empirical methods of determining the mineralogical and textural characteristics of the several ore types have been developed.

Jan 1, 1995

By Minting Li, Hailong Yang, ChangWei, Cunxiong Li, Gang Fan, Xingbin Li, ZhiganDeng

The filtration problems on acid leaching sludge of high silicon zinc ore have been paid extensive attention in zinc hydrometallurgy. It was found that soluble silica can be effectively converted into silica precipitate with good settling, filtration and washing properties, and the filtration rate can be in excess of 800 L/m2 · h under certain leaching conditions. According to investigating on the filtration rate, viscosity and concentration of silica of leaching sludge or liquor, the filtering temperature can tremendously improve the filtration property of pulp. At the same time, the experimental data indicated that the viscosity of leaching liquor was the key factor influencing filtration property of leaching sludge.

Jan 1, 2016

By Roberto Parra

The classic criteria of the preparation of the charge for the smelting of copper concentrates in at flash furnace considers the mass and energy balance from the chemical and mineralogy composition of the concentrates. The operation parameters fixed with this method don't assure the stability of the operation and the critical problems of the slag quality and dust formation occurs very often. This paper presents the results of a laboratory test that allows the prediction of the behavior of concentrates blends in the view of the minimization of the dust formation and the magnetite control in the slag. The combustion of different copper concentrates and blends were done in a drop tube furnace The results show that the magnetite and dust formation don't have a linear behavior with the weight proportion of the blend and some optimal blends of 2 or 3 types of concentrates can be identified. From the reasonable hypothesis that the qualitative behavior of blends in the drop tube represents the real behavior in the burner, the preparation of the charge with this approach could help to solve those operational problems.

Jan 1, 2003

By George P. Demopoulos

In this paper the production and stability of crystalline scorodite (FeAsO4·2H2O) is discussed both on the basis of previously published work as well as recent work performed in our laboratory. The production of scorodite, especially from arsenic-rich and iron-deficient sulphate solutions offers a number of operational advantages such as high arsenic content, stoichiometriciron demand, and excellent dewatering characteristics. In addition to hydrothermal production of scorodite the work done over the last 10 years in our laboratory has determined that it is feasible to produce scorodite by step-wise lime neutralization at 90°C. The atmospheric scorodite possesses the same structural and solubility characteristics with the hydrothermally produced scorodite. Long term equilibration tests (up to 66 weeks) in the pH range 5 to 9 and temperatures from 22 °C to 75 °C revealed scorodite to undergo slow incongruent dissolutionyielding a highly metastable nano-sized 2-line ferrihydrite phase. The equilibrium arsenic concentration with this phase was 0.35, 0.96 and 5.87 mg/L at pH 5, 6, and 7 respectively at 22°C. In the presence of gypsum slightly lower concentrations were measured, this being more pronounced at pH>7. It was tentatively deduced that a Fe-Ca-AsO4 association (in the form of a phase resembling the mineral yukonite) contributes to the lowering of As concentration. Finally thermodynamic calculations determined that scorodite is stable in the presence of ferrihydriteunder oxic conditions up to pH 6.75 at 22 °C or higher pH at lower temperature and gypsum-saturated solutions. Keywords: Scorodite, Crystallization, Arsenic, Solubility, Stability, Precipitation, Disposal, Extraction, Processing, Metals, and Environment.

Jan 1, 2005

By T. Plikas, L. H. Gunnewiek, L. Oshinowo

"Electric furnace smelting is one of the principal unit operations for ferroalloy production, and increased process intensity, improved availability, minimal maintenance and a longer campaign life are common objectives for electric furnace operation in order to obtain favourable economics of production. Furnace designers have continued to develop innovative solutions, e.g., furnace cooling systems, that have allowed these objectives to be realised and CFD modelling plays a key role in the design process. Enhanced understanding of the energy transfer process in the furnace and the ability to develop, evaluate and optimize components of the crucible design to match process requirements are the key motivators for modelling.This paper provides an overview of recent applications of CFD to the design of electric furnaces. The aim is to illustrate what can be done, and identify areas where further work is needed in this field. Examples include furnace bath simulation, crucible cooling system design, taphole design, baking of Soderberg electrodes, off-gas systems, and fume control and building ventilation. It is argued that the trend is for numerical models to become more encompassing while at the same time more accessible, and therefore further improvements in furnace design will be realised with continued and well validated modelling efforts.IntroductionOne of the main processing steps in ferroalloy production is the smelting of ore in electric furnaces. The three-electrode, AC submerged arc furnace is most prevalent method for smelting in the industry, with shielded-arc and DC plasma arc furnaces achieving limited application (1,2). Commercial furnaces range in size from a few megawatts to more than eighty megawatts of supplied power, and operate with the objective of maximising the return on capital invested. Maximising productivity and energy efficiency are two pathways to achieving this objective, through process intensification, increased availability, minimal maintenance, and increased campaign life for the furnace and associated equipment. Concurrently, the need to reduce the environmental impact of metal production by controlling the emission of particulate emissions, greenhouse gases, and other harmful by-products must also be met."

Jan 1, 2004

By Slobodan Radosavljevic

The polymetallic W-Pb-Bi-Ag ore from the ?Nova jama? ore zone of the Rudnik ore field have been investigated. Contact-pneumatolytic (skarn), pneumatolytic-hydrothermal, and hydrothermal mineralization phases are defined in this ore zone. The most significant mineralization phase that gave compact ore bodies is pneumatolytic-hydrothermal phase. A relatively pure Mo-free scheelite is the only tungsten-bearing mineral. Lead minerals are mostly presented by Pb-Bi sulphosalts and much less with galena. The image analysis coupled with Energy Dispersive Spectrometry (EDS) analysis on a Scanning Electron Microscope (SEM) was applied to the characterization of a W-Pb-Bi-Ag ore as an efficient tool for mineral quantification. Results of EDS (Energy Dispersive Spectrometry) analyses gave the empirical formulae: Pb1.91Ag0.05Cu0.08Bi1.93S5 for cosalite, Pb0.98Ag0.03Cu0.05Bi1.99S4 for galenobismutite and galena Pb0.99Ag0.03S.

Jan 1, 2006

By Yasuo Ojima

A new copper continuous converting process was investigated to evaluate the possibility of its application in the commercial operation. The tests were performed both in the laboratory and in pilot plant scale. Bath smelting process with the use of the top submerged lance technology was applied in these tests. Furnace shape was modified to a lengthwise eylindrical one with a settling area. The furnace monitor was put in the settling area to check the furnace from inside, FeOx-Si02, FeOx-CaO and FeOx-CaO-Si02 based slag systems were used to check their efficiency, The optimum slag chemistry to have good metallurgical results was discussed and FeOx-CaO system with some Si02 content turned out to be preferable although it has not been practically used, In this pilot plant test feeding rate of I tIH of solid grain matte was charged consecutively for two weeks and continuous converting could be done successively. This process is expected to overcome the problems of existing processes and be easily applied in existing plants.

Jan 1, 2003

By Larry Southwick

This Peirce-Smith Converting Centennial symposium is celebrating the contributions of two men, William Peirce and E.A.C. Smith, in advancing technology allowing the copper industry to realize its full potential. However, theirs is representative of a larger story: New, simpler technology releasing the stranglehold of older, more complicated technology, new developments in vessel configuration and design finding alternate routes around dead ends in operability, advances in technique and concepts removing roadblocks of cycle time and capacity, and overall innovation opening up vast new reserves around the world to those companies willing to embrace those improvements. Our story is also one of personalities, stubborn smeltermen versus the innovators, those inside the industry versus those from outside. It is a story of an initial borrowing from the steel industry, but also Peirce and Smith, from the refining end of the copper business, taking the ideas of Baggaley from Pittsburgh’s steel and airbrake industry, who built on what Hollway, Manhès and David, Douglas, and others had done in smelter tests, further to compete with the previous primacy and closely held expertise of the copper smeltermen in Wales. These advances have been well recorded in photographs taken over the last 150 years. A number were submitted especially for this symposium. Many others were published in the mining and metallurgy press of the times. Several mining schools also retained copies of photos either taken during field trips, or donated to the school by alumni and operating companies. This presentation will provide a selection and discussion from these sources of “converters in action”, describing the various designs, operations and developments depicted. The focus here will be on the first roughly 60 years of copper converter development, from Bessemer’s days at the dawn of this new idea, up to and slightly past the time of initial adoption of Peirce and Smith’s designs.

Jan 1, 2009

By Esher Hsu

In Taiwan, around 8,000 tons of batteries are consumed per year but only 17% of which were collected and transported to oversea for recovery. The dumping used batteries have become a potential environment problem. How to increase the collection efficiency of used batteries is an important issue for EPA in Taiwan. Besides, some treatment plants are on process to get permission for recovering used batteries. The objective of this study is to estimate the recycling cost of spent consumer battery and explore the feasibility of recovering used consumer batteries in Taiwan based upon the principle of cost-efficiency. The recycling cost including collection cost and recovery is estimated based on a survey. Results would provide some suggestions to Taiwan EPA regarding feasibility of recovering used batteries in Taiwan.

Jan 1, 2006

By F. F. Aplan

Though over 100 minerals are known to contain the rare earth (RE) or lanthanide elements, only a few provide the bulk of the world's source of these elements. The principal RE-containing mineral, monazite [(Ce,La,Th,Y)PO4], is recovered by gravity, magnetic, electrostatic and flotation concentration methods, while the other important source mineral, bastnasite [CeFC03], is concentrated by flotation. The processing of the lesser important source minerals is discussed, as is the recovery of the lanthanides from apatite [Ca5(P04)3(F,OH)] where the rare earth elements are present from trace amounts to over 10% as the mixed oxides.

Jan 1, 1989

By H. H. Kellogg

The Process Fuel Equivalent (PFE) for nine different flowsheets for production of anode copper from sulfide concentrates has been evaluated and compared for a set of uniform conditions and a "standard" concentrate analysis. The processes considered are: reverberatory smelting, (wet-charge and hot-calcine charge), electric furnace smelting, Outokumpu flash smelting (2 versions), mom flash smelting, Noranda Continuous Process (2 versions), and the Mitsubishi Continuous Process. The energy required for the numerous processes auxiliary to the principal smelting processes-¬roasting, drying, air compression, gas handling, dust collection, slag cleaning, acid manufacture, etc.--are separately evaluated and incor¬porated into the process comparisons. The factors in process design that lead to important energy savings are: use of fuel rather than electric energy; use of oil or coal rather than natural gas; maximum use of oxygen enrichment of the process air; drying of charge before smelting, or, even better, drying and preheating of charge by partial roasting in a fluid-bed; recovery of waste heat from all major hot process gases.

Jan 1, 1976

By Georgios Kolliopoulos

Water is a critical commodity of our generation and a key compound for the chemical and mining industries. Sustainable industrial development is directly associated with the ability to recover clean water from contaminated sources. Forward Osmosis (FO) is a low-energy footprint membrane process allowing the recovery of clean water from high salinity effluent streams. In FO, water is recovered spontaneously into a concentrated draw solution (CDS). Energy is required to separate the recovered water from the resulting dilute draw solution (DDS). In the current work, the fundamentals of the FO process and the most important aspects affecting its performance are discussed. An energy comparison of FO and conventional water recovery technologies is presented. Finally, the opportunities FO presents in the field of hydrometallurgy are analyzed.

By Xiao Hong, Zhang Wenqiang, Gao Bing

The characteristics of top charging coke (coke 1) and stamp charging coke (coke2) were investigated. The weight loss ratios of two kinds of cokes with and without alkalis were measured after reacting with CO under the temperature of 2 900, 1000, 1100 and 1200 °C respectively. The microstructures of original cokes were observed by SEM. The experiment results show that, with no addition of alkali, the weight loss ratios of coke 1 and coke 2 were nearly the same under the temperature of 900 and 1000 °C. While the weight loss ratio of coke 2 was much larger than coke 1 under the temperature of 1200 °C. With alkali-rich, the weight loss ratio of the two cokes was almost the same at 1100–1200 °C.

Mar 1, 2017