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By Stephen M. Testa

Several methodologies are available for the remediation of contaminated soils including bioremediation, vapor extraction, chemical fixation, incineration and direct disposal. A proven innovative and cost effective alternative for the fixation of contaminated soils is via cold-mix Environmentally Processed Asphaltm (EPA"'). EPAm methodology utilizes contaminated soil as an ingredient in an industrial process to produce a commercially viable product. Petroleum hydrocarbon and metal affected soil is incorporated with a water-based asphalt emulsion and varying amounts of aggregate to produce a range of cold-mix asphaltic products that fulfills the requirements of a variety of end uses. This viable and creative use which is within the intent and spirit of current regulations in producing, in lieu of a landfill waste, an end product for use as a berm, road base, liner, or other site specific application. Consideration of certain engineering and environmental factors including durability, stability, chemical resistance and ageing, biological resistance, permeability, leachability and geochemical aspects suggests that cold-mix asphalt incorporation of affected soil will perform more than adequately under normal conditions for a long period of time.

Jan 1, 1994

By Xiao-hui Fan, Xu-ling Chen, Zhi-yuan Yu1, Guanghui Li, Min Gan, Yun-song Huang, Tao Jiang

Compared with the traditional de-NOx processes by cleaning the waste gas, a new approach for reducing the formation of NOx during sintering process is proposed. Since more than 90vol% of NOx comes from the fuel combustion, the influence of sintering coke breeze pretreated by CO(NH2)2 additive on the NOx emission is researched. As adding CO(NH2)2, the reduction agents (NHi) are generated during the pyrolysis of CO(NH2)2, which reinforce the NOx reduction, And the appropriate content of CO(NH2)2 is 1.0 mass% of coke breeze.

Jan 1, 2015

By Guan-zhou Qiu, Shui-shi Liu, Yu-feng Guo, Tao Jiang

"The preparation of high-quality synthetic ruitle from electric furnace titanium slag was systematically investigated by activation roasting followed by acid leaching process. The results showed that impurities such as Ca and Mg in titanium slag can be effectively removed and TiO2 grade of the product was markedly improved by the process. High-quality synthetic rutile containing 88.54% TiO2, 0.42% (CaO+MgO) was obtained under the conditions that roasted with 7.5%(wt) H3PO4 at 1000 oC for 2h, followed by two-stage leaching in boiling dilute sulfuric acid for 2h. Mechanism studies showed that anosovite solid solution and silicate minerals were reacted with phosphoric acid in the roasting process. As a result, titanium components in titanium slag turned into rutile (TiO2) and impurities were transformed into acid-soluble phosphate and quartz.IntroductionWith the gradual depletion of natural rutile and the rapid development of titanium industry in China, the natural rutile reserves cannot satisfy the requirement for production of titanium pigment and titanium sponge. Ilmenite is, therefore, becoming main raw material for titanium industry. However, because of its low TiO2 grade, it generally requires preconcentration to titanium-rich material such as titanium slag or synthetic rutile [1-3].Ilmenite resources are extremely rich in Pan-xi area of China, which account for 90.54% of total ilmenite reserves in China [4]. The titanium slag produced by electric smelting of ilmenite concentrate has high contents of Ca and Mg, and is not suitable as a raw material for chloride process and titanium sponge production. Therefore, upgrading titanium slag to prepare raw material suitable for chloride process and titanium sponge production has important significance for the development of China's titanium industry."

Jan 1, 2011

By Dominik Hofer

A broad spectrum of tantalum containing input materials can be processed for the production of synthetic tantalum concentrate (“SynCon”). The use of these low grade substances offers a secure alternative to mining of coltan in Central Africa. SynCon is produced in a multi-stage pyrometallurgical process, wherefore the melting behaviour of slags presents an important factor especially regarding the energy consumption and its optimisation. The characteristics of a slag comprising mostly Al2O3, CaO, SiO2 and MgO are influenced by the amount of other oxidic constituents which enfolds the main focus of this study. A hot stage microscope serves for the investigation of the slag behaviour in a temperature range from 1000 to 1600 °C under reducing atmosphere (CO/CO2 gas). The experimental results are compared with thermodynamic calculations (FactSage) to get a better understanding of the process.

By Li Ma, Shaoguo Chen, Gele Qing, Qihang Liu, Keng Wu

Olivine contains higher MgO element, which can be added into blast furnace burden to improve slag stability and fluidity. Effect of calcined olivine and untreated olivine on low silicon pellet production process and quality was studied in this paper. The results shows, calcined olivine has no effect on bursting temperature of green pellet, however the bursting temperature of green pellet will decrease with increase of untreated olivine ratio. Untreated olivine has slight effect on green pellet strength than calcined olivine while the ratio is higher than 2%. The compressive strength of low silicon pellet will increase first and decrease afterwards with increases of calcined olivine ratio under firing temperature of 1250°C, whereas, the changing sequence is reverse fired under 1280°C. The result of untreated olivine pellet compressive strength is same as calcined olivine pellet. However, the compressive strength and metallurgical property of calcined olivine pellet is slightly higher than that of untreated olivine pellet under same condition.

Jan 1, 2015

By Denise Crocce Romano Espinosa, Andrea Moura Bemardes, Jorge Alberto Soares Tenorio, Daniella Cardoso Buzzi, Tatiana Scarazzato

"In copper plating processes, a fraction of raw materials are incorporated to the final products, while other portions are discarded as effluents. In this study, the application of electrodialysis (a membrane treatment process) was studied for treatment of wastewaters from cyanide-free strike baths, in order to reuse the components of this bath: copper and HEDP. The synthetic solutions studied consider 1 % of ion concentration of the bath used in this process, simulating the rinsing waters to be discarded. The electrodialysis allowed a percentage extraction up to 73% of copper ions and 72% of HEDP from the effluent. Complexes formation between the acid and copper indicates the possibility of recovery of components in the same compartment, obtaining a concentrated solution of these substances that can be reinserted in the process, for compensating drag-out losses. A diluted solution is also obtained, that can be reused as water in rinsing tanks.IntroductionIn metal finishing industries, contaminants in wastewater and the type of treatment required are determined according to the type of operation [l]. Generally, electroplating industries employ conventional wastewater treatments, e.g. oxidation of cyanide and chemical precipitation. This stage promotes reactions with soluble compounds to produce an insoluble precipitate, removed by physical separation. The sludge is dried by press-type filters [2].In this manufacturing sector, part of the raw materials are discarded as hazardous waste. The cost of discarded compounds and the treatment and disposal of waste may compromise profit margins. In addition, water consumption per unit of production stimulates the development of methods able to recover and reuse the largest possible amount of water [3].In some plating processes, cyanide-based substances are used as complexing agents and as raw materials in form of metal salts [4]. However, the toxicity associated with cyanide has been promoting research for the development of new raw materials in plating processes.A study conducted in Brazil [4] evaluated the modification of a commercial cyanide-free bath for processes of copper coating on Zamak. In the performed study, a new alkaline copper bath was formulated using l,hydroxyethane-1,1-diphosphonic acid (HEDP), an organic compound known for forming stable complexes with metal ions.As results of the study, the operational conditions and the formulation of a bath to obtain adherent, uniform and bright layers were established (Table I) [4]."

Jan 1, 2014

By Ahmet Haxhiaj, Jaroslaw Drelich

"Both composition and porosity of pellets are the main parameters influencing the reductive melting process in water-jacket furnace during the roasting of sulfide lead concentrate. Roasting in a smelter located in Trepçë is done at about 9000C, for pellets which are composed of PbS, CaCO3, Fe2O3, and SiO2. In order to faciltiate the formation of slag in the reductive melting, the pellets must have the proper content of CaO, SiO2, and FeO, and porosity. The plant’s practice indicates that pellets with porosity of 18% do not melt adequately in the water-jacket furnace. The optimum porosity for the proper melting of pellets needs to be 32-40% and can be achieved when pellets are loaded with more than 10 wt.% CaO. Pellets with less than 10% CaO have a limited network of pores, such that reactive gases cannot reach the entire ore structure. Also, the composition of the pellets must satisfy the ratio of CaO : SiO2 : FeO = 1 : 1.2 : 1.8 to facilitate the formation of slag in the reductive melting process.IntroductionAgglomeration roasting of sulfide lead concentrate is an important phase in the production of lead by reductive melting [1-6]. The reductive melting process is a complex process with contradictory effects of several technological indexes which many times are hard to measure and determine. In this process, loading the water-jacket furnace with pellets of optimized composition and structure can reduce the consumption of coke, and achieve high level of lead recovery. Pellets (agglomerates) should be porous, but at the same time they should have necessary mechanical strength. ‘Self-melting’ ability of pellets is controlled by the types and quantities of fluxes blended into the pellet composition. Three major additives and their role are:"

Jan 1, 2011

By Edward P. Hagarty

The Hazardous and Solid Waste Amendments (HSWA) of 1984 added Subtitle I to the Resource Conservation and Recovery Act (RCRA), authorizing the Environmental Protection Agency (EPA) to develop and implement a new regulatory program for Underground Storage Tanks (USTs) containing petroleum and other regulated substances. Technical standards required for release detection, prevention, and correction as necessary to protect human health and the environment were promulgated as described in 53 Federal Register 37082 (September 23, 1988). Virginia State Regulations (VR 680- 13-02) and U.S. Army Regulations require that a Corrective Action Plan and a Site Clearance Report be prepared to explain the details of remediation of any contaminated media. Construction of new buildings is proposed in two different areas at Fort Myer in Arlington, Virginia, where USTs containing gasoline, diesel and heating oil were located. Tightness testing performed on these USTs in September 1991 indicated that some of the tanks were leaking. Many of the tanks were removed for permanent closure. Initial Abatement (excavation of contaminated soil) was &ed out immediately. A detailed Site Characterization Study which included Hydropunch", field screening using immunoassay, and pilot test - dual phase (water and soil gas) extraction was conducted. Environmental media were analyzed for volatiles, semi-volatiles and metals. A detailed risk analysis (RA) was performed to determine risk-based clean up levels for benzene, toluene, ethylbenzene, xylenes (BTEX); polycyclic aromatic hydrocarbons (PAHs); and methyl-tertiary butyl ether (MTBE). The RA also discussed the presence of lead in the soil. Before constructing any buildings in these contaminated areas, remediation must be conducted in accordance with the State, Federal and other applicable regulations. The remedial alternatives evaluated included Vapor Enhanced Groundwater Extraction, Soil Vacuum Extraction, Soil Washing, Soil Steaming, Active and Passive Ventilation SolidificationlStabilization, Vapor Barrier Construction, and Excavation with Off-site Disposal. This paper discusses: (a) delineation of soil contamination @) risk analysis (c) evaluation of remedial alternatives and selection of the most appropriate technology and (d) consideration of various regulatory issues.

Jan 1, 1994

By Wilhelm Wendt

About five years ago we showed that it is possible to use the spectral in- formation in the light emitted by the off-gas flame of a PS converter for on-line production control. Very recently measurements have been performed using improved optical equipment and data evaluation software, resulting in both improved accuracy and the establishment of new optical process parameters. Using the optical signals the slag heats could be stopped at a predetermined Cu content of the white metal with an accuracy of +0.2% Cu m the range 74-78% Cu. A good correlation was found between the slag composition and optical data, providing a possibility for on-line monitoring of the SiO2 content of the slag. The measurements indicate the possibility of predicting the optimum end-point of the copper-making stage and having real time information on the impurity removal. Factors influencing the optical parameters, such as blowrate, Pb content, temperature etc. will be discussed.

Jan 1, 1993

By Guohua Bai, Lin Zhang, Shan He, Xuling Chen, Min Gan, Xiaohui Fan, Yanbin Tang

"For reducing the dust content in flue gas during copper smelting in the Ausmelt, technologies and mechanism of strengthening the pelletizing of copper concentrate were studied. The results show that adding bentonite, organic binder or composite binder can effectively enhance the strength of green pellet and reduce the rate of shedding powder in drying process, and composite binder works best. When adding 1 % of composite binder, the drop strength of green pellet increased from 1.9 times/P to 4.5 times/P, the rate of damage dropping from 2 m reduced from 50.12% to 13.08% and the rate of shedding powder reduced from 60.28% to 25.13% at drying temperature of 400111. In addition, the mechanism of binder absorbed in the surface of mineral was investigated by infrared spectroscopy. The results showed that composite binder absorbed in the surface of copper concentrate was in the form of chemisorptions, which made hydrophilic enhanced, while bentonite absorbed in the surface of copper concentrate was physisorption.IntroductionWith the technologies of copper smelting developing, the equipment of copper smelting steps into a large-scale and efficient level in recent years. As Ausmelt smelting is characterized by being efficient, environmentally-friendly and energy-saving, it is generally recognized by the enterprises of copper smelting [l]. The process of Ausmelt smelting starts with materials mixing, and then pelletizing. From this point onwards, pelletized balls are charged to the top of the furnace, undergoing drying and smelting reaction[2]. Since copper concentrate is fine-grained, directly adding into smelting furnace can make it blown out of the furnace together with the airflow upwards, rendering flue gas high in flue dust, which can cause the loss of concentrate greatly, and make smelting environment poor as well. The concentrate transported into the furnace and smelted after disc balling is conducive to improve the capacity of melting furnace during copper concentrate smelting, reduce the powder shedding rate and improve enterprise benefits."

Jan 1, 2013

By H. Forrest

Lead smelting at Cookson Industrial Materials was formerly carried out using a combination of Blast and Reverberatory Furnaces. In the late 70' s these furnaces were replaced by two 20 tonne capacity Rotary Furnaces. This furnace type has proved to be more flexible in the range of feedstock that can be processed, including lead drosses, battery plate and even whole batteries. High rates of production have been achieved whilst attaining a good level of environmental control. The majority of the sulphur in the feedstock can be fixed by use of appropriate fluxes.

Jan 1, 1990

By F. Kongoli

Viscosity is an important parameter of copper smelting and converting processes. It affects the settling of matte or metal droplets in the slag, distribution of elements etc. Despite this importance, confusion exists on the viscosity of copper smelting slags as a result of disagreements found among the measured viscosity data of several authors especially in the slags of high ferric iron content and close to magnetite precipitation. In this work a critical review of the existing data on the viscosity of copper smelting slags has been first carried out and the effect of oxygen potential on the viscosity of copper smelting slags has been clarified through a coupled quantification of viscosity and liquidus temperature. The confusion in the literature has been clarified and the importance of the relation between the viscosity and the liquidus temperature is discussed.

Jan 1, 2003

By G. Barbery

The models for particle composition prediction that have been put forward are limited to simple textures and lead to an independance of grade with respect to particle size in broken ore. A presentation is made of a modification in texture description; binary textures, in which each subeonstituent has its own breakage characteristics are introduced. The calibration of the textural model can be made using heavy liquid separation results. The application to the case of coal is presented. Coal washability data present spe¬cial difficulty due to the distribution in the specific gravity of coal, which must be taken into account. Coal s.g. distribution is taken as a generalized exponential distribution. Model calibration is then possible and is shown to be in good agreement with experimental data.

Jan 1, 1987

By Feng Liu

A thermal upgrading process by which nickel value can be concentrated in a ferronickel alloy is a possible alternative to treat Sudbury pyrrhotite (Po) tailings with nickel content of 0.5–1.5 wt%. The basis of this process is precipitation of Ni from Po at high temperature once Fe/S ratio in the iron-deficient Po is shifted towards stoichiometric or near stoichiometric FeS (troilite) either by the addition of iron and/or the removal of sulfur. For the iron addition route, the reaction between elemental iron and nickeliferous pyrrhotite to produce ferronickel alloy and Ni-depleted iron sulfide phase plays a critical rule. In this paper, the formation mechanism of ferronickel alloy was investigated using the diffusion couple technique to better understand the nickel diffusion behavior in the iron and sulfide phases.

By Bin Xu, Qian Li, Yong-bin Yang, Xiao-liang Liu, Tao Jiang, Yan Zhang

Some high sulfur and arsenic-bearing gold concentrate has a gold leaching rate less than 80% by oxidation roasting-pickling-cyanidation process. The characteristics and intensification of gold leaching were studied systemically. By combining chemical composition and phase analysis, the low gold leaching rate was found to lie in the capsulation of gold by iron-containing phases including iron oxides, arsenopyrite and pyrite. 96.66% of gold in the industrial leaching residue was capsulated and 95.88% of the capsulated turned out to be in the iron-containing phases. The results of laboratory pickling-cyanidation experiments on the calcine and industrial leaching residue presented further demonstration for the fact that gold capsulated in the iron-containing phases was hard to be leached. However, the gold cyanide leaching rate of calcine could be raised over 95% by a reduction roasting-pickling pretreatment which played such a significant role in exposing the capsulated gold that gold leaching was intensified remarkably.

Jan 1, 2015

By Kunwar Pal, S. K. Tyagi, A. K. Pandey

"This study deals with the performance evaluation, technical and environmental aspects of different cookstove models (NIRE-02, NIRE-03 & NIRE-04). These cookstove models were designed, fabricated and evaluated following Bureau of Indian Standards (BIS) and their performance was compared from technical and environmental points of views. The theoretical efficiencies of all the cookstove models are found to be in good agreement with the experimental one. Also, the overall performance of these models is found to be in the order of (NIRE-04 > NIRE-03 > NIRE-02) which is also observed to be much better than that of the traditional cookstoves being used by the people in most of the developing countries around the world. The CO2 emission reduction from these models is found to be between 2.0-3.0 tons per household annually which is ultimately in good agreement with the experimental values.IntroductionMore than 2.5 billion people around the world depends on the biomass based resources for cooking and heating applications which includes wood, cattle dung, charcoal and agriculture residue [1,2]. Generally, people of rural area cook their food on unvented open fire, which burn biomass fuel inefficiently besides it creates many thermal and environment pollution hazardous causing health problems in the women and girl children due to more exposure of emissions. Also the consumption of biomass is very high as compared to the fossil fuels due to the fact that the large population of the developing countries lives in the rural area than that of in the urban area. It is estimated that about 3% of the diseases are caused due to incomplete combustion of biomass, which results in the around 1.8 million premature death every year including around 0.9 million death under five year of their age [3,4].Ramanathan and Carmichael [5] recently found that the black carbon of unburned smoke is playing a major role in global warming. The emission factors for different combinations of fuel and stove tested in China for direct and indirect GHGs as well as other airborne pollutants such as, CO2, CO, CH4, TNMHC, N2O, SOx, NOx, TSP etc. for a typical set of operating parameters [6]. The improved biomass cookstove technology came into assistance which is technically feasible, socially reliable and economically viable [7, 8]. The improved biomass cookstove not only reduces pressure on the biomass resource, but also reduces the environmental pollution and also minimize the time required for collection of fuel wood [9, 10]. Sharma et al. [11] emphasized on the adoption and large-scale propagation of efficient stoves to improve the health of rural women and to reduce the consumption of firewood and environmental pollution."

Jan 1, 2014

By Marion Dattilo

The search for an improved anode for the electrowinning of lead from fluosi1icic acid medium has led the U.S. Bureau of Mines to investigate composites. Polymer bonded metal oxide powders which may contain catalyst additions were prepared by pressing. These composites display an improved activity toward the oxygen evolution reaction over electrodeposited lead dioxide on titanium, carbon, and nickel substrates. These composite electrodes contain 5 to 10 wt. " binding polymer, with the balance being metal oxides. Lowered anodic potentials achieved using the compnsite anodes resulted in lower levels of lead dioxide deposition during electrowinning.

Jan 1, 1995

By D. E. Karvelas

Argonne National Laboratory is conducting research to develop a cost-effective and environmentally acceptable process for the separation of high-value plastics from discarded household appliances. The process under development has separated individual high purity (greater than 99.5%) acrylonitrile-butadiene-styrene (ABS) and high-impact polystyrene (HIPS) from corruningled plastics generated by appliance-shredding and metal-recovery operations. The process consists of size-reduction steps for the commingled plastics, followed by a series of gravity- separation techniques to separate plastic materials of different densities. Individual plastics of similar densities, such as ABS and HIPS, are further separated by using a chemical solution. By controlling the surface tension, the density, and the temperature of the chemical solution, we are able to selectively float/separate plastics that have different surface energies. This separation technique has proven to be highly effective in recovering high-purity plastics materials from discarded household appliances. A conceptual design of a continuous process to recover high-value plastics from discarded appliances is also discussed. In addition to plastics separation research, Argonne National Laboratory is conducting research to develop cost-effective techniques for improving the mechanical properties of plastics recovered from appliances.

Jan 1, 1996

By Hector Henao

To provide thermodynamic data for converting the nickel matte to liquid nickel, an experimental study was conducted in the phase equilibrium between the Ni-S alloy and the CaO-Al2O3 based slag melted in a MgO crucible at 1873 K under controlled Pso2 of 10.1 kPa and Po2 in a range between 2.5x 10-and 10.1 Pa by using CO-CO2-SO2 gas mixtures. The content of nickel in the slag at Po, of 10.1 Pa, above which solid NiO is expected to precipitate in the equilibrium state, was found to be 4, I mass% and the contents of sulfur and oxygen in the nickel melt were 0.4 and 02 mass%, respectively. ft was clarified that increase in the temperature reduces the solubility of nickel in the slag and the contents of sulfur and oxygen in the alloy, The distribution of minor elements such as gold, silver, copper, cobalt, iron, arsenic and antimony between the Ni-S alloy and the CaO-Al2O3 based slag was also studied. The distribution ratios of iron and cobalt, defined by (%X in slag)/[%X in alloy] where X is the minor element, are larger values than that of nickel, while those of copper, silver and antimony are similar to that of nickel. The distribution ratios of arsenic and gold are lower than that of nickel in the higher range of oxygen partial pressure.

Jan 1, 2003

By John W. Ahlrichs

Microscope, electron microprobe and x-ray diffraction have been used to provide quantitative evaluation of products from the mill, smelter, refinery and other metallurgical processes. Phase compositions and their quantities are necessary for an adequate understanding of the various products obtained throughout an operation and in laboratory testing. By careful evaluation, important information can be gained in improving recoveries and increasing grades at various stages of processing. Four case histories are discussed in this paper. Quantitative microscopic counting techniques are applied to mill products to determine degrees of locking and liberation of the economic minerals. Rapid, but accurate evaluation aids the metallurgist to develop or improve the grinding and flotation circuits. In the smelter, the identification and quantification of the phases are important for predicting reaction mechanisms and kinetic trends. Mineralogic techniques have been applied to conventional smelter products, and to those obtained in laboratory tests for newly developed innovations to smelting. Small, but important, values of gold occurrences in ore are difficult to determine. Evaluation of gold usually requires special separations into various mineral concentrates, followed by assays and mineralogic determinations of the products. Numerous occurrences of solid solution constituents can be treated as by-products, but often they are deleterious to metallurgical treatment. Most solid solution problems can be unraveled by the mineralogist's tools.

Jan 1, 1981