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By Yuanbo Zhang, Zijian Su, Bingbing Liu, Guanghui Li, Manman Lu, Tao Jiang

Acid wastewater containing toxic metal ions has become increasingly important global environmental concern and lead (Pb) is one of the prime toxic heavy metal ions. Humic acid (HA), a kind of natural organic matter, has been proventohaveagreatadsorptioncapacityformetalcations(Pb2+,Cu2+,etc.).Our previous study has verified that HA has excellent adsorbing ability on vanadium titanium-bearing magnetite(VTM) particles. In this study, VTM-HA complex magneticparticles werepreparedfor removing Pb(II)fromacidwastewater,which could be easily recycled by magnetic separation. The effects of pH value, ionic strength and VTM-HA concentration on the removal ratio of Pb(II) were deter- mined by isothermal adsorption tests. The results indicated that Pb(II) adsorption was subject topHand ionic strength. When initial Pb(II) concentration is 100 mg/ L, the residual concentration and removal ratio of Pb(II) reach 0.17 mg/L and 99.83%, respectively, which are much lower than the discharge standard. (cid:1) (cid:1)

Mar 1, 2018

By Richard J. Abitz

Thennodynamic geochemical models have been applied to assess the relative effectiveness of a variety of reagents added to aqueous waste streams for the removal of radioactive elements. Two aqueous waste streams were examined: effluent derived from the processing of uranium ore and irradiated uranium fuel rods. Simulations of the treatment train were performed to estimate the mass of reagents needed per kilogram of solution, identify pH regions corresponding to solubility minimums, and predict the identity and quantity of precipitated solids. Results generated by the simulations include figures that chart the chemical evolution of the waste stream as reagents are added and summary tables that list mass balances for all reagents and radioactive elements of concern. Model results were used to set initial reagent levels for the treatment trains, minimizing the number of bench-scale tests required to bring the treatment train up to full-scale operation. Additionally, presentation of modeling results at public meetings helps to establish good faith between the federal government, industry, concerned citizens, and media groups.

Jan 1, 1996

By W. K. Collins

Engineered Scavenger Compounds (ESCs), developed by the U.S. Bureau of Mines, are a novel class of compounds that can selectively recover a desired element from a solid or molten alloy. Lithium titanate (Li2Ti3O7 or L'20-3T'02) is being used as an ESC to recover lithium (Li) from Aluminum-Lithium (Al-Li) alloys. X-ray diffraction measurements have shown that lithium titanate undergoes a phase change from an orthorhombic structure to a hexagonal structure. This change is due to the incorporation of Li in the matrix of the material and the effect of temperature. Although both are metastable, the hexagonal phase that forms during the scavenging of Li from Al-Li alloys appears to be the more stable phase. Recovering Li from the ESC by electrodeposition does not cause the structure to revert to the orthorhombic phase. Both the orthorhombic and the hexagonal structures of Li2Ti3O7 have similar scavenging capacities for Li. This paper proposes a new mechanism for the phase transformation.

Jan 1, 1993

By C. T. Philipp

Recycling of waste is much preferred over disposal. This paper discusses the Enviroscience, Inc. (ESI) process, now being commercialized by MetWool, Inc., to recycle hazardous wastes using an extractive metallurgical process which is followed by vitrification of non-reducible metal oxides. In this process, volatile and reducible metals are reclaimed as their respective oxides and elements.

Jan 1, 1995

By Wayne C. Stewart

Freezing of high pressure air lines and pneumatic equipment has been a recurring problem in the Thompson Smelter. The particular severity during the winter of 1989-90 resulted in costly process disruptions and repairs. A process improvement team with representatives from operations, engineering and both maintenance supervision and the shop floor was established to develop solutions. Their mandate included process evaluation, design, equipment and in-plant commissioning. In 1990, upon recommendation of the team, we installed three Refrigerant/Desiccant air dryers with a total capacity of 20,000 S.C.F.M. to service the Smelter. This paper discusses processes and process improvements associated with this installation.

Jan 1, 1993

By W. D. Riley

Engineered Scavenger Compounds (ESCs), developed by the U. S. Bureau of Mines I are a novel class of compounds that can selectively recover a desired element from 'a solid or molten alloy. Lithium titanate (Li2Tip7 or Li20' 3TiO.) is being used as an ESC to recover lithium (Li) from Aluminum-Lithium (AI-Li) alloys. X-ray diffraction measurements have shown that lithium titanate undergoes a phase change from an orthorhombic structure to a hexagonal structure. This change is due to the incorporation of Li in the matrix of the material and the effect of temperature. Although both of the structures are metastable, the hexagonal phase that forms during the scavenging of Li from AI-Li alloys appears to be the more stable phase. Recovering Li from the ESC by electtodeposition does not cause the structure to revert to the orthorhombic phase. Both the orthorhombic and the hexagonal structures of Li.Til07 have similar scavenging capacities for Li. This paper proposes a new mechanism for the phase transformation.

Jan 1, 1991

By V. Ramachandran

In view of the increasing environmental regulations that have been promulgated in the last 30 years, non-ferrous smelters and refineries have learnt to handle effectively the process waste streams that need to be bled from the system for impurities' control The cations of concern are copper, lead, zinc, cadmium, mercury, thallium, nickel, silver, sodium and potassium. Anionic species of arsenic and selenium also need to be addressed, Sulfates and chlorides-not a major concern at present-have come under scrutiny in the recent past. The current paper reviews several treatment options with reference to a) types of waste streams processed b )process chemistry c)discharge options and recovery of treated water and d) sludge disposal The long term goal of any smelter and/lor refinery should be to achieve zero liquid discharge from the plant. Methods to obtain zero discharge are discussed.

Jan 1, 2003

By V. Ramachandran

In view of the increasing environmental regulations that have been promulgated in the last 30 years, non-ferrous smelters and refineries have learnt to handle effectively the process waste streams that need to be bled from the system for impurities' control. The cations of concern are copper, lead, zinc, cadmium, mercury, thallium, nickel, silver, sodium and potassium. Anionic species of arsenic and selenium also need to be addressed, Sulfates and chlorides-not a major concern at present-have come under scrutiny in the recent past. The current paper reviews several treatment options with reference to a) types of waste streams processed b)process chemistry c )discharge options and recovery of treated water and d) sludge disposal. The long term goal of any smelter and/or refinery should be to achieve zero liquid discharge from the plant. Methods to obtain zero discharge are discussed.

Jan 1, 2003

By Scott A. Howard

MgO is routinely used as the basis for refractory materials, however, its susceptibility to hydration may result in dimensional instability and subsequent failure. The addition of boron has been shown to reduce th,e hydration susceptibility of MgO yet its dissolution into certain grades of steel may degrade their performance. In order to predict the efficacy of reducing hydration susceptibility by the incorporation of mono-, di-and tri-and quadravalent cations, the lattices of various cation-substituted systems were modeled. To more accurately simulate the substituted lattices, either cation or anion vacancies were incorporated to maintain electrical neutrality and all possible arrangements of defects in a 2x2x2 MgO supercell were investigated. Correlations were then made between the lattice energies of these systems and their susceptibility to hydration as reported in the literature. The results indicate the presence of higher charged cations tended to increase lattice stability while the cations with lower valency tended to have lower lattice energies. The relatively small body of experimental results available in the literature are consistent' with this study's results.

Jan 1, 1989

By T. J. White

Xtaltite is the trade name for a generic technology which exploits the well known insolubility of some minerals, which naturally incorporate toxic waste elements, to consolidate and immobilise a range of inorganic waste products. It is a specific case of synthetic mineral immobilisation technology (SMITE) which is already used to immobilise high level nuclear wastes (HLW. Although HLW is highly toxic, it exists in relatively small volumes, occurs in central facilities and may be stabilised at low waste loading (< 10 wt%). In contrast, heavy metal wastes are of considerable volume, therefore Xtalitite waste forms must routinely accommodate high waste loadings (usually in excess of 30 wt% for a particular toxic oxide or combination of oxides) and be suitable for fabrication in remote locations using relatively simple technology. This paper details the methodology underlying Xtaltite, with particular emphasis given to the interplay between solid state chemistry, durability and economic considerations. Specific reference is made to the treatment of arsenious and mercurial wastes.

Jan 1, 1994

By Takeshita. Takuo

"In this work, the progress of the HDDR process is discussed mainly on the Nd-Fe-B magnet system. There are three technologies being used for the Nd-Fe-B permanent magnet production; the sintering technique, the rapid quenching annealing and the HDDR process. The HDDR process utilizes· the HDDR phenomenon, in which hydrogen absorbing intermetallic compounds go through as they are heated in hydrogen atmosphere, Hydrogenation - Decomposition Desorption - Recombination. In the HDDR process, these four steps in the HDDR phenomenon are processed by choosing suitable reaction conditions regarding to hydrogen gas pressure, temperature, rate ·of desorption and etc., and we can produce permanent magnet powders of good magnetic properties with microstructures consisting with sub-micron size crystalline grains. In the anisotropic magnet powders, the sub-micron size crystals are being mostly aligned in the crystallographic c-axis direction. Possible applications of the HDDR process to other systems are also discussed.Microstructures of the Nd-Fe-B Permanent MagnetsIt is well known that magnet properties of magnetic materials are very sensitive to their microstructures [l]. This is seen in almost all magnet materials from soft magnetic materials and hard magnetic materials to magnetic memory materials. In this regard, the production technology is very important for the control of microstructures of permanent magnets The Nd-Fe-B magnet is the most powerful permanent magnet as a practical permanent magnet, and its coercivity force is much dependant on the microstructure as is the case for other permanent magnets."

Jan 1, 2000

By M. E. Coleman, G. Money

"Clyde Materials Handling is an established customer-driven solutions provider, which utilizes its knowledge, expertise and technologies to transform the production processes of its customers, who operate in the ferrous and non-ferrous metals industries.With over 30 years experience in the process improvement industry, Clyde Materials Handling has helped their global customer base transform the way in which they operate their processes, which has enabled them to generate sustainable economic benefit and maintain their positions as leaders in their respective markets.Clyde Materials Handling has supported operators within the metals market by developing and deploying pneumatic conveying and pneumatic injection technologies. These environmentally supportive and sustainable solutions have been used to transport raw materials within operating facilities, from storage to silo, as well as injecting these materials directly into the heart of production processes.Clyde Materials Handling has worked closely with their customers, such as Codelco in Chile, where their pneumatic solutions have been used to inject a consistent, pulseless and accurate flow of copper concentrate into a bath smelter, which has helped to fuel the operational capacity, availability and productivity.This paper will discuss and highlight the ways in which pneumatic injection technologies, created by Clyde Materials Handling, and applied in partnership with their customers, have helped to improve the operational performance of the production processes of operators across the non-ferrous metals markets with specific reference to applications in the Peirce Smith Converter.Clyde Materials Handling has applications injecting Electronic Scraps, Dusts, Reverts, and other additives to the Peirce Smith Converter. They also have experience of modified PS Units used for Slag Cleaning. There experience with the Codelco Teniente Converter is also directly related to this area of operation."

Jan 1, 2009

By Theodore Ineich

The “BIOMOre” project aims to prove the technical feasibility of indirect in situ bioleaching of sulfide minerals contained in a deep underground deposit, by bringing together the disciplines required to make a success. The underground location in Poland was provided by project partner KGHM inside an operating copper mine. Key components of this project were the design and construction of a pilot plant, and its operation in an underground environment. This project also included a ∼250 t (100 m3) fragmented rock reactor hydraulically connected to the pilot plant. The pilot plant consisted of several tanks and pumps, a fluidised bed ferric iron generating bioreactor containing immobilised acidophilic iron oxidation biomass, and all the required instrumentation and utilities. Before the bioleaching phase could start, the rock reactor had to be flushed continuously firstly with water to remove chloride salts that are corrosive and also harmful for the bacteria used in the bioreactor, and secondly, with sulfuric acid solution to react with the carbonates present in the ore matrix. This paper summarizes the design, construction, commissioning, and operation of the pilot plant.

By T. DebRoy

In recent years rapid technological advances have been achieved in the application of high energy density heat sources such as lasers and electron beams in diverse metals processing operations such as metal refining, fabrication, coating, surface modification and alloying. However, our phenomenological understanding of these new and emerging processes has not kept pace with the technological achievements. Inadequate understanding of plasma-metal interactions, the complexity of the component physical processes, and the scarcity of thermophysical data at temperatures much higher than the melting points of metals are the main difficulties in the comprehensive analysis of these processes. Several unique contemporary issues related to metals processing with high energy density beams such as rapid evaporation of alloying elements during processing and the role of plasma in influencing vaporization rate interfacial tension and species solubility in metals are discussed in this paper.

Jan 1, 1993

By Husamuddin Ahmadzai

A survey of regulations and state of the art control technologies is presented relating to the smelting of primary aluminium, copper and recycling of residues. Some costs associated with the alternatives and trends for the coming decade in this. sector are identified.

Jan 1, 1992

By Maria Rashidi, Maryam Ghodrat, Bijan Samali

Treatment of sharp medical waste (waste disposable syringes) produced in hospitals or health care facilities in an environmentally sound ways have raised concerns relating to public health and occupational safety. Life cycle assessment (LCA) is a decision-supporting tool in waste management practice; but relatively little research has been done on the evaluation of sharp medical waste treatment from a life cycle perspective. Our study assesses the environmental performances of medical waste incineration as a type of dominant technology for specific medical waste of average composition. Inventory models were used for waste incineration and residues land fill. Background data were derived from modelling performed in HSC Chemistry thermochemical package linked with GaBi environmental assessment tool. Two scenarios have been considered and compared: Waste disposable syringes partially replacing coke in Electric Arc Furnace (EAF) steelmaking (WSI) and conventional incineration with pure metallurgical coke without adding waste syringes (CI). The results of this study could support the medical waste hierarchy and indicate that from a life cycle perspective, replacing part of metallurgical coke with waste syringes in electric arc furnace steelmaking leads to fairly significant reduce in most of environmental impact categories.

Mar 1, 2017

By Francis C. Furman

Microscopic evidence indicates that the high sinterability of certain commercial dolomites is tied to specific dolomite textural characteristics. This study encompasses detailed characterization of the unprocessed dolomite and sintering doloma results. The chemical and mineralogical compositions, insoluble residue, chemistry homogeneity, crystal size, primary carbonate texture, secondary dolomite texture, deformation structure, porosity type, porosity, and density of the raw dolomite were observed. These characteristics are compared with sintering trials of <74um powder-compacts samples in which holding times were varied. The evolution of the dolomite characteristics are reviewed and related to the final sintered doloma characteristics. The critical characteristics of a single-stage sintering brick dolomite are the following: 1) primary oolitic texture, 2) dolomite purity, 3) dolomite stoichiometry 4) minimal impurities, less than 1 weight {%} Fe2O3 Al2O3 and SiO2, 5) chemical homogeneity, 6) high density, 7) very low porosity, S) very coarse homogeneous crystallinity, 9) nonplanar dolomite texture, 10) abundant strain related slip microdeformation structures, 11) minimal subsequent alteration. Even with grinding to <74um the nonplanar dolomite texture and slip deformation still have a major effect on doloma sintered density. The three newly identified characteristics of single-stage sintered refractory brick dolomite are their primary oolitic texture, secondary nonplanar texture and abundance of stress related microdeformation structures. The primary oolitic texture reflects a homogeneous pure carbonate with respect to chemistry and crystal size secondary nonplanar texture produces crystals with large surface area to volume ratio. Stress related slip deformation moves CO, groups in to the same site of another CO, group but different orientation which is very unstable. All of these characteristics may facilitate the formation of higher density dolorna sinters.

Jan 1, 1995

By Jian Li, P. Liu, R. Zhang and J. Lo

In the past decades, focused ion beam (FIB) has evolved into a powerful microscope that provides capabilities that no other microscopes can offer. The combination of high-resolution imaging and stress-free ion beam cross sectioning provides valuable microstructure information both at the specimen surface and beneath. FIB techniques are also the preferred method to prepare site-specific transmission electron microscope (TEM) specimens. CanmetMATERIALS owns a world-class microscopy facility, where advanced microscopy work provides strong supports to research programs that cover a wide range of subject areas. This paper is aimed to provide a few practical examples of FIB applications in microstructure characterizations that include cross-sectioning and imaging, serial sectioning, and advanced TEM specimen preparation in materials research at CanmetMATERIALS.

Jan 1, 2015

By A. René Silva

The separation of Fe(III) from simulated Ni(II) solutions using different ion exchange resins was studied. The resins tested included cation exchangers with sulfonic and carboxylic groups and chelating resins with iminodiacetic, aminophosphonic, and mixed sulfonic and phosphonic groups. The dosage of resins was varied from 0.1 to 0.5 g/mL to study the impact of resin type and dosage on iron separation from simulated nickel leach solution containing 25 g/L Ni(II) and 25 g/L Fe(III) at pH 1.5. Also, the effects of different metal ion concentrations, Fe (III):Ni(II) ratios in solution, pH, and adsorption times were investigated. Experimental results demonstrate that all the chelating resins selected favored the adsorption of Fe(III) over Ni(II) with high Fe(III) loading. Soft cation exchange resins also favored the adsorption of Fe(III) over Ni(II), but no significant Fe(III) loading was observed. In contrast, strong cation exchange resins did not show adsorption preferences. The most efficient separation was observed using resin with aminophosphonic groups at resin dosage of 0.2 g/mL, having a Fe(III) adsorption over 94% and Ni(II) adsorption below 5%.

By J. L. Watson

The composite nature of titanomagnetites found on the west coast of the north island of New Zealand is an important parameter in the beneficiation of the black beach sands for export to Japan. To investigate this composite nature, borehole and plant samples from the Waipipi Ironsands Ltd property were subjected to a series of separations in heated Clerici solutions at densities varying from 3.2 to 4.6 g/cc. The resulting density fractons were analyzed magnetically and a set of distribution curves for composite grains proposed. In addition the experi¬mental data was plotted to produce titanomagnetite sand &apos;washability curves" which illustrate the possible problem areas in beneficiation that may arise due to composite titanomagnetite grains. From this data a set of guidelines are suggested for interpreting the curves in terms of ease of gravity concentration. The composite nature or liberation of titanomagnetite grains is shown to favor high and low grade composites with few intermediate compositions being isolated. The relationships between grain size, borehole depth and liberation are examined and related to beneficiation procedures for the black sand deposit.

Jan 1, 1982