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By Sylwia Zymankowska-Kumon, Rafal Danko, Józef Danko, Mariusz Holtzer

"Burning of ceramic materials is carried out at temperatures 900+ 1300°C, in dependence of the required functional properties. The Faculty of Foundry Engineering together with the Faculty of Material Engineering and Ceramics developed the technology of production of burned ceramic materials with using spent moulding and core sands. The mentioned above waste materials of the foundry industry fulfilled -in plastic masses intended for obtaining ceramic materials -the role of the addition weakening clay raw materials. The laboratory investigations were fully verified by the results of industrial tests. It should be pointed out that none negative effects were observed at the stage of mixing raw materials and preparation of plastic masses. The measurements of exhaust gases emissions performed during burning the products containing spent moulding sands as well as during the normal production did not exhibit any significant differences, which could have indicated the harmful impact on the natural environment.IntroductionSands are used by the foundry industry to make metal casting molds and are a mixture of silica sand, bentonite clay and carbonaceous additives or resins. During the casting process, the molten metal cause thermal decomposition of carbonaceous additives or resins, which results in the formation of potentially hazardous organics, that are emitted to the atmosphere and condense in the molding sand. Each year the U.S. foundry industry landfills about 10 million tones of sand because it is no longer suitable to make metal casting molds. A large high-silica sand content in spent foundry sands (SFSs) generates rational premises for their reuse in other than foundry practice fields. Efforts to divert the SFSs from landfills and encourage their beneficial use in manufactured soils, geotechnical applications, the construction industry (road construction, highway construction), the building materials industry (cement, bricks, limestone manufacture), in the filling of mining cavities or in landfill construction (roads on landfills, permanent covers) are make [1-7]."

Jan 1, 2013

By Ralph H. Nafziger

The Bureau of Mines, in cooperation with the Idaho National Engineering Laboratory, has electroslag melted a V-5Ti-5Cr alloy using a fused CaF2, flux. The alloy is a candidate for use in future fusion reactors. One objective of this research was to evaluate the feasibility of the electroslag melting process in separating simulated radioactive isotopes from the V alloy to demonstrate recyclability. Small amounts of Ca, Y, and Mn were added as surrogates for radioactive isotopes. Results showed that this vanadium alloy can be electroslag melted satisfactorily. The impurities added intentionally were removed or decreased successfully. Among the major alloying constituents, Cr was retained but there were some Ti losses. The latter may be controlled with process refinements. This research suggests that the electroslag melting process could be a suitable method for recycling V alloys after use in future fusion reactors, or for processing other reactive metal alloys with more immediate applications.

Jan 1, 1996

By Tao Zhang, Wen-tao YU, Hai-bin ZUO, Jian-Liang Zhang

Sintering-pot tests and metallurgical performances of sinter with 4 kind of different Al2O3 contents are experimented in this paper. Results show: when the Al2O3 contents increase from 2.0% to 3.5%, acicular calcium ferrites in mine phase will be gradually replaced by plate-like iron calcium. The increase of Al2O3 contents will lead to the addition of liquid viscosity and the reduction of permeability of sinter bed. Sintering time will be prolonged. The rate of yield is stable basically but production is low; besides, the increase of liquid viscosity will decrease of drum strength. The change of permeability of the material layer will make RDI +3.15 decrease first and then increase when Al2O3 contents changed from 2.0% to 3.5%. RI of sinter shows a contrary trend because many open voids are formed by deterioration of liquidity first and then pores closed.

Jan 1, 2015

By M. A. Halim, V. I. Lakshmanan, T. Sheikhzeinoddin, R. Roy

"Chloride metallurgy is emerging as an alternative process for the production of base metals. Process Research ORTECH Inc. (PRO) has been at the forefront of technological development of chloride metallurgy. PRO has developed an innovative technology for the production of high purity titanium dioxide, iron oxide and vanadium pentoxide from ilmenite ores and concentrates. PRO is also developing its proprietary mixed chloride technology for the extraction of vanadium from other sources such as oil shales. In this paper, results from the test work conducted at PRO for the extraction of Ti and V using a mixed chloride lixiviant are presented.IntroductionTitanium and vanadium alloys and compounds have numerous industrial applications. Titanium dioxide is used in paints, plastics, rubber, paper, inks, textiles and a number of other miscellaneous applications. Currently nanosize T1O2 is being investigated for application in the cosmetics industry. Inorganic sunscreens mainly use T1O2 or ZnO particles, which reflect and scatter ultra-violet light. T1O2 nanomaterial is also finding application in smart construction materials and coatings, as a photo-catalytic converter. Nano TiO2 can catalyze the dissociation of NOX gases and other automotive emissions, thereby reducing the smog in urban centers. After the construction material is exposed to sunlight or ultra-violet light, the T1O2 is photo-activated and degrades the pollutants.Titanium metal and titanium dioxide are produced from ilmenite (FeTiOs) or rutile (naturally occurring T1O2) ore. Only about 6% of the titanium resources are used to produce titanium metal and the rest is used to produce T1O2. Many of the titanium ore deposits currently have unacceptable levels of transition metals which limits their processing by conventional routes."

Jan 1, 2012

By Junmo Ahn

This study investigated leaching kinetics by alternative lixiviants for copper leaching from chalcopyrite (CuFeS2), the most abundant copper resource in the world. As a refractory sulfide mineral, chalcopyrite shows low copper extraction due to passivation on chalcopyrite surface. Also, decrease of copper grade with high portion chalcopyrite requires the alternative leaching procedure to increase copper recovery. Therefore, alternative lixiviants such as sulfurous acid and methanesulfonic acid (MSA) were tested for both concentrate and low grade ore to enhance copper extraction. Also, an oxidant, hydrogen peroxide, was compared to ferric to find out the improvement of leaching kinetic. In concentrate leaching tests, 30 g/L MSA showed the highest copper extraction (47%), compared to other lixiviants at 75 °C. Periodical H2O2 addition enhanced copper extraction, and above 90% of copper extraction was observed within 96 h by periodical addition of 0.6% H2O2 at 75 °C. The activation energy of chalcopyrite leaching by MSA and H2O2 achieved 40 kJ/mol, which is chemical reaction control. The results of low grade ore leaching tests indicates that no significant difference among lixiviants (H2SO4, H2SO3 and MSA) with ferric was observed, all of which achieved around 37% within 24 h at room temperature. However, significant increase of copper extraction (>80%) was observed at both 20 g/L MSA and 10 g/L H2SO4 conditions by the addition of 10% H2O2.

By Filiz Sahin

This paper presents a synthesis of TiB2 via carbothermal reduction method using a mixture of TiO2, B4C and C prepared in molar ratio of 2:1:3. Reduction experiments were carried out in a high temperature graphite furnace in a graphite crucible under argon atmosphere at different time (0, 15, 30 and 60 min.) and temperatures (1400, 1500 and 1600 °C). The products obtained were investigated using XRD technique.

Jan 1, 2008

By Roger Altman

The solubility of copper in primary spinel crystals encountered in reverberatory slag samples has been determined by electron microprobe analysis. These spinels, which ranged in composition from 22% A12O3 to pure magnetite, contained small quantities of dissolved copper (0-0.4%). Based on literature data it was estimated that the solubility limit of copper in solid magnetite is no greater than about 1% at 1200°C and about 2% at 1250°C. However, it was found that practically every spinel crystal examined contained significant amounts of matte inclusions. Further examination of converter slag revealed large quantities of irregularly shaped precipitated magnetite crystals which contained a large proportion of copper inclusions. Additional experimentation showed that the total copper content in reverberatory slag samples was greater than the sum of the estimated en- trained plus dissolved matte in the slag. This difference is believed to be significant and is due to the presence of matte inclusions in the spinel crystals. In the present reverberatory slag samples these inclusions accounted for about 1/2 of the amount of sulfide directly entrained in the slag.

Jan 1, 1976

By Dietrich Gross

This paper describes an advanced oxy-fuel combustion technology for re-melting aluminum that significantly reduces energy consumption and emissions. This oxy-fuel combustion technology developed by Jupiter Oxygen is a patented process for combustion of fossil fuels with pure oxygen while excluding air, thereby creating an undiluted high flame temperature and increased efficiency for process heating in industrial furnaces. This unique process has led to improved heat transfer and longer residence time while maintaining the same process temperatures as with air combustion. The energy efficient combustion process allows aluminum companies to operate at a substantially lower cost due to a dramatic fuel savings of up to 70% for natural gas and waste oil (1). The results of more than 10 years of day-to-day experience utilizing the Jupiter Oxygen Corporation oxy-fuel combustion technology licensed to Jupiter Aluminum Corporation in the aluminum re-melting business are discussed.

Jan 1, 2008

By Robert D. Rogers

The demand for phosphate will continue into the future, because phosphate is currently irreplaceable as a plant nutrient and in many chemical applications. Phosphate is not recycled, so the supply must be replenished through a process of mining and purification. Numerous microbial isolates. obtained from the environment were screened find those which demonstrated the greatest promise of solubilizing PO4 from the ore of interest. Screening was accomplished in a step wise manner an agar plate bioassay, shake flask studies, and semi continuous growth conditions. It was found that with the proper conditions of nutrient supply and solution pH; the bacteria and. fungus used in the semicontinuous process were able to solubilize in excess of 80% of an Idaho rock phosphate ore (RP) within nine days. A significant amount of solubilization occurred within the first six days. There was a 'reasonable correlation between the occurrence of soluble Ca and PO.4 during the processing of the RP thus providing evidence that the RP was being disintegrated by the organisms. In all cases, HPLC analysis of the solutions in which PO4 had been. extracted from RP showed that organic acids, which have been implicated as the mechanism of solubilization, were present.

Jan 1, 1991

By Olga Slavkina

A new technology of bacterial leaching by means of the Thiobacillus ferrooxidance bacteria is proposed. The equations of reactions that describe of the first and the second stage of bacterial leaching of sulfide raw materials containing non-ferrous metals are given. The theory is analyzed and the technology of processing of some complicated substandard concentrate containing copper and zinc is proposed. The main technological operations including a two-stage bacterial leaching and stages of copper and zinc recovery in the form of marketable product are described. The results of the experimental validation of the main technological parameters of the first stage are given. The main possibilities of a more complete zinc and copper recovery at the second stage of bacterial leaching are discussed in comparison with single-stage leaching process.

Jan 1, 2003

By Edwin de Jesús Deveaux

After 32 years of operations beneficiating lateritic nickel ore in a fully integrated pyrometallurgical complex, Falconbridge Dominicana (FALCONDO), situated at Bonao and La Vega Provinces, Dominican Republic, has become profitable with one of the lowest nickel grade content processing plants in the world, and literally without any by-product (granulated slag, will be utilized in the future as a post-processing subproduct). To December 2002, mineral reserves were 64.1 million tonnes containing laterite grading as low as 1.15 % Ni when full dilution is applied. At a cut-off grade of 1.20% Ni, the reserves will provide 15-20 years of production. The mineralized thickness over the seven active deposits averages 6 m. Development of very selective and unique mining practices, together with improvements in the process plant, are key to achieving the production goal (30 kt Ni/yr) and to meet the quality standards for the ferronickel produced. Keywords: Laterites, grade control, mining methods, environment

Jan 1, 2004

By Harovel G. Wheat

It has been shown that the incorporation of fly ash into concrete as a replacement for part of the cement can be beneficial. In some cases, the strength of the concrete can be increased and the permeability can be decreased. This latter property can lead to a reduction in the migration and/or penetration of aggressive species into reinforced concrete. Some of these species, such as chlorides from deicing salts or marine environments, can subsequently result in accelerated corrosion of the steel reinforcement, a loss of the protection provided by the passive film on steel, and a loss of structural integrity of the concrete. Care has to be taken so that the appropriate compositions of the components of the fly ash are utilized in order to ensure maximum benefit to the concrete structures. This will be discussed as it relates to fly ash generation and treatment.

Jan 1, 2002

By Taegong Ryu

The thermal plasma process has been applied to the preparation of nanosized tungsten carbide (WC1-x). The reduction and carburization of the vaporized chloride by methane-hydrogen mixtures produced nanosized WC1-x powder, with a small amount of WC or W2C phase. The products were characterized using XRD, carbon analyzer, and TEM. The effects of plasma torch power, the flow rate of primary plasma gas (Ar) to generate plasma flame, and the addition of secondary plasma gas (H2) on the product composition were investigated. The tungsten carbide (WC1-x) powder had a particle size less than 30 nm. The powder was treated under hydrogen atmosphere to fully carburize the WC1-x, and W2C phases to WC as well as remove excess carbon in the product. Finally, WC powder with a grain size less than 40 nm was obtained.

Jan 1, 2008

By Glenn C. Miller

Cyanide is the most common lixiviant for extraction of precious metals, and its efficient use in open pit mines has contributed to the increase in world production of gold during the previous two decades. With this expansion of precious metals mining using cyanide, public concerns have developed in response to the inherent public perception of cyanide as a tox-in as well as a series of environmental problems that are directly or indirectly related to cyanide use in open pit mining. Some of these have technical or regulatory solutions, while others will require additional investigation before they can be resolved. The following discussion will summarize some of the public concerns regarding the use of cyanide in precious metals mining. The issue of cyanide use in large scale precious mining is controversial, and recent banning of cyanide use in open pit mines in Montana, or complete banning of cyanide in Hungary has reflected those international concerns. The underlying basis for some of the bans (e.g. Montana) reflect a general concern of the environmental impacts of mining, rather than specific issues related to risk of cyanide use. The human safety record for cyanide use, particularly in the developed countries is good, and cyanide is clearly the most efficient lixiviant for precious metals. Indeed, the relatively short lifetime for cyanide in the environment renders it one of the less problematic chemicals used for extraction of gold from ore. Mercury amalgamation or use of bromide as a lixiviant are certainly much more problematic. What, then, is the basis f~r the international concern about precious metals mines that use cyanide. Ifuse of cyanide for gold recovery is to continue, what additional infom1ation needs to be developed that will allow a better management of the risks of cyanide? Which of the concerns are directly related to cyanide, and which are indirect concerns that more related to effects of open pit mining. Under what conditions should use of cyanide be discouraged? DUl::ing June of 2000 the United Nations Environmental Program conducted a two-day workshop on cyanide use in mining that was attended by persons from the mining industry, regulators and environmental community. Support and attendance at this workshop reflected concerns by all three groups on further restrictions for cyanide use and the emerging potential for guidelines for better management of the catastrophic release of cyanide-containing mining waste. The following discussion is meant to focus-on those risks and explore the basis for an often negative reaction to precious metals mining using cyanide. It is presented in the format of a statement, followed by a discussion. While admittedly provocative, the statements are meant to express the concerns? of the public regarding cyanide and the mining industry.

Jan 1, 1998

By Huimin Lu, Liyuan Zhao, Zhijiang Gao

The aluminum matrix composite reinforced by graphene was successfully fabricated using high pressure torsion (HPT). With only 0.5wt% graphene, the grain size was reduced to 100nm while that of pure Al was about 500nm. The hardness of the composite increased from the center (64HV) to the edge (120HV) of the sample. Moreover, the tensile strength of this composite reached 197MPa, while that of pure Al was 157MPa. The enhancement in mechanical properties was induced by grain refinement, load transfer from the matrix to the reinforcement and dislocations piled up at the grain boundaries.

Jan 1, 2015

By Charles H. Rawlins

Reported is work done on processing of steel mill effluents in the areas of dewatering and separation. Much of the waste from these operations is in the form of sludges from scrubbers, in which the primary constituent is iron oxide. Recycling of the sludge&apos;s magnetic fraction has become economically attractive in order to reduce the overall volume placed in landfills. The objective of this research is to determine the effectiveness of combining magnetic and cyclonic forces, to recover iron oxide particles from waste water stream, while decreasing the volume to be disposed. Three different size hydrocyclones, operating within the field of a quadripole magnet, were tested using varying feed pulp densities of magnetite, magnetite/dolomite, blast furnace (BF), and basic oxygen furnace (BOF) slurries. In the first three cases, the percentage of magnetics recovered increased to greater than 95%. The limiting operational factors are; high pulp density for small cyclones, which can cause flow blockage within the magnet field, and extremely fine particle sizes (<2 microns), which cannot be recovered. The results indicate this technique can remove virtually all the magnetic particles from some steel effluents to a 40-50% weight percent solids pulp, on an in line continuous basis.

Jan 1, 1994

By P. A. Metz

The Fairbanks mining district has produced in excess of 7.5 million troy ounces of placer gold and 250,000 troy ounces of lode gold since gold was discovered in the area in 1902. The Fairbanks mining district is in the northwestern part of the Yukon-Tanana Upland Schist Terrane, an area of approximately 240,000 square km that has produced in excess of 21 million troy ounces of placer gold. All lode gold production from the terrane has been from the Fairbanks mining district, and all of this production has come from high-grade gold-quartz polymetallic sulfide veins. Gold grains in the vein systems range in size from several microns to several millimeters. The veins are localized in a complex metamorphic rock assemblage which includes greenstones and felsic metavolcanic and volcaniclastic rocks, meta-exhalatives and metasediments. Gold occurs in the metamorphic host rocks in association with arsenopyrite and arsenic-antimony sulfides which occur in lenses and disseminations within the host rock. Gold grains occurring in the metamorphic host rocks range. in size from sub-micron to a few microns in diameter.

Jan 1, 1987

By S. N. Monteiro, C. M. F. Vieira, M. M. Ribeiro

"This work has as its objective to evaluate the effect of incorporation of the powder waste retained in the eletrostatic precipitator of the sintering stage from an integrated steel making plant on the physical and mechanical properties of a red ceramic. Formulations were prepared with incorporation of the waste in amounts up to 20 wt.% into a kaolinitic clay. Rectangular specimens were prepared by uniaxial mold-press at 20 MPa and then fired at 750, 900 and 1050°C. The evaluated physical and mechanical properties were: linear shrinkage, water absorption and flexural rupture strength. The results showed that the waste has a potential to be used into red ceramics. The incorporation of the waste enhanced the properties of the ceramic, decreasing the water absorption and increasing the mechanical strength at all investigated temperatures.IntroductionThe sintering stage of an integrated steel-making plant is dedicated to the agglomeration of a mixture of iron ore, coke or coal, fluxes and water [1]. It is a common practice in this stage to use of solid wastes with great amounts of iron in the form of sludge and powder. One of the atmospheric pollutants generated during the sintering process is the particulate material, which is normally retained in an equipment denote as electrostatic precipitator. This equipment retains very small particulates, present in the gaseous emissions by application of an electrical potential difference in between the plates that the fluid is forced to go through. [2]."

Jan 1, 2011

By D. Lui, B. G. Thomas, B. Ho

"Results from mathematical models and plant experiments are combined to quantify the effect of transverse depressions and oscillation marks on heat transfer in the continuous casting mold. A heat transfer model has been developed to calculate transient heat conduction within the solidifying steel, coupled with the steady-state heat conduction with the continuous casting mold wall. The model features a detailed treatment of the interfacial gap between the shell and mold, including mass and momentum balances on the solid and liquid powder layers. The model predicts the solidified shell thickness down the mold, temperature in the mold and shell, thickness of the resolidified and liquid powder layers, heat flux distribution down the mold, mold water temperature rise, ideal taper of the mold walls, and other related phenomena. The important effect of non-uniform distribution of superheat is incorporated using the results from previous 3-D turbulent fluid flow calculations within the liquid cavity. Results from plant experiments confirm that transverse surface depressions and oscillation marks form at the meniscus and move down the mold. Measurements of mold thermocouple temperatures and breakout shell thickness were used to calibrate the models. The results indicate that the surface depressions and oscillation marks are filled with mold flux, but still have a significant effect on decreasing heat transfer. The predicted mold temperature fluctuations are consistent with measurements. If the depressions become filled with air, their effect is greatly increased. These results should be useful in the difficult task of interpreting transient mold thermocouple signals for on-line quality monitoring.IntroductionMany different types of intermittent surface defects on steel slabs arise during initial solidification in the mold of the. continuous casting machine. These defects include deep oscillation marks, surface depressions, and cracks. They may lead to quality problems, such as slivers, in the final rolled product. In severe cases, breakouts may occur, where liquid steel bursts through a thin section of the shell and drains over the casting machine below the mold."

Jan 1, 1997

By Edgar Peek

Lixiviant regeneration is by definition a precondition for any hydrometallurgical process. In chloride hydrometallurgy either HCl or Cl2 has to be regenerated in order to establish an economically viable metallurgical process. One such regeneration process is widely used with steel pickling where HC1 is regenerated through the thermal decomposition of ferrous chloride in either spray roasters or fluid bed pyrohydrolyzers. This standard HC1 regeneration process deserves to be considered as a potential separation process, since thermodynamic calculations show that a fluid bed pyrohydrolyzer can function as a ferrous-nonferrous separator. Several nonferrous,metals such as zinc, lead and cadmium can be volatilized as a chloride under ferrous chloride pyrohydrolysis conditions. If such a nonferrous metal volatilization could be achieved in the case of slurry feeding of "contaminated" iron oxides, then this would increase the Fe/H2O ratio of the (process) feed and thus save on fuel per ton of iron, while yielding a marketable iron oxide product. Previous test work on synthetic materials revealed that the near-complete separation of zinc, lead and cadmium from iron oxide was possible in a pyrohydrolytic atmosphere, even if zinc was present as zinc ferrite (more than 99.5%). This investigation, which was carried out in a tube furnace at 1100 K has now been extended to treat synthetic zinc minerals and also franklinite ore. For the latter, it was found that 85% zinc volatilization could be achieved in 4 hours at 1300 K. It is postulated that complete zinc volatilization could not be attained due to the formation and/or presence of gahnite and hardystonite, which might be stable in HCl/H2O atmospheres at 1100 K. The effect of adding small amounts of calcium chloride to react with gahnite and hardystonite to give zinc chloride and both calcium aluminates and silicates is being discussed. Test work on slurry feeding of this complex ore in a recently constructed 4-inch diameter fluid bed pilot unit has been planned for the near future.

Jan 1, 1995