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By P. M. Swash

The paper describes the use of mineralogical methods in the exploration and evaluation of primary diamond occurrences. The most common methods that are used include the systematic search for kimberlitic indicator minerals, surface textural study of the indicator minerals, (garnet, spinel, ilmenite and chrome diopside) and alluvial macrodiamond studies so as to understand their provenance and guide exploration towards diamondiferous targets. The mineral chemistry of the indicator is used to positively assess the origin of the mineral grains and is also pivotal in the determination of the diamond potential of a deposit. Petrography of the primary deposit is able to identify the body to be kimberlitic and is also a support to the mineral chemistry findings. Unambiguous proof of a prospects potential to contain macrodiamond is proven by the occurrence of microdiamonds in the residues from the rock. The presence of a sufficient number of microdiamonds in the rock is enough to determine a semiquantitative grade estimate and warrant further metallurgical evaluation so as to determine its actual macrodiamond content.

Jan 1, 1991

By Katsutoshi Inoue

Pectic acid gel crosslinked with epichlorohydrin was found to have very high selectivity to lead(II) and iron(III) ions over zinc(II) ion compared with commercial weakly cation exchange resins containing the same carboxylic functional groups, suitable for removing small amount of impurity metal ions from waste zinc plating solutions. In order to lower the cost, new adsorption gel was prepared from orange juice residue containing pectic acid by crosslinking with epichlorohydrin, which was also found to be suitable for removing these impurities. Further, very cheap adsorption gels was prepared not only from orange but also from apple juice residues by a simple method through just saponificating pectin substances contained in these residues into pectic acid by calcium hydroxide followed by water washing and drying. These adsorption gels exhibited excellent adsorption behaviors for removing the impurity metal ions away from zinc.

Jan 1, 2003

By Guoqiang Lv, Xi Yang, Wenhui Ma

Cast multicrystalline silicon ingots are widely used in photovoltaic manufacturing. A key issue to achieve high solar cell efficiencies is to attain an optimized temperature field during directional solidification (DS) process. This paper reports numerical investigation of multicrystalline silicon (mc-Si) ingot production using two major types of DS furnace. Specific examination is made on thermal distribution, interface shape and stress field. Evaluation is performed for the applicability of thermal system design to reduce thermal stress, improve crystal quality and enhance energy efficiency. The effects of procedure parameters and geometric configuration on temperature distribution are discussed as well to provide the viable solutions for systems optimization.

Jan 1, 2015

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 Richard A. Shulkosky

The American Iron and Steel Institute (AlSO, in conjunction with the U.S. Department of Energy (DOE) jointly funded the development of a mechanical properties model for Hot Strip Mills. INTEG process group, inc. validated an enhanced version of the model under a project funded by the AlSI/DOE Technology Roadmap Program (fRP). The Hot Strip Mill Model (HSMM) version 6.0 allows users to easily set-up their mill configuration, simulate a rolling mill schedule and calibrate the model for a variety of grades of steel. Starting from reheat furnace drop out, the model simulates roughing mill stands (reversing and continuous), heat retention equipment (coil box and covers), finishing mill stands (tandem and Steckel mills), the run out table and the mill exit area. The HSMM uses a series of physical models to calculate both the thermo-mechanical and the microstructure evolution of steel being processed in a hot mill to predict its final mechanical properties. The enhanced HSMM was validated using a multitude of samples from several steel companies. Excellent agreement was obtained for tensile strength. The supporting steel companies have utilized the model for a variety of practical applications. Keywords: Process Modeling, Microstructure Evolution, Mechanical Properties

Jan 1, 2003

By A. E. Isaacson

Bureau of Mines researchers developed and tested equipment to measure corrosion rates on a commercial-scale mill as an aid in predicting the effect of corrosion on minerals and how this effect relates to downstream processing. Bench-scale experiments were designed for duplicating ore grinding conditions closely enough that realistic rate determinations can be made in laboratory tests. Rates measured in a laboratory system compared favorably with those measured in the field. Cast steel was found to have corrosion rates in a copper mill and laboratory test cell of 22 and 21 mpy, respectively. Corrosion was found to account for less than 5% of the total grinding media wear in the operations studied.

Jan 1, 1987

By J. T. I. Poijärvi

The smelter off-gas cleaning and the weak acid treatment at Outokumpu Harjavalta Metals Oy are presented and described in this paper. The smelter consists of the copper and nickel smelters and the acid plant of three separate acid plants two of which are double contact and one single plant and of one liquid sulphur dioxide plant. The preliminary cooling and flue dust separation of the smelter off....,gases from the copper ?and nickel flash smelting furnaces and converters? in the waste heat boilers and in the hot electrostatic precipitators are described. The final cooling and cleaning of the gases in the scrubbers at the sulphuric acid plant and the treatment of the weak acid in the vacuum and in the submerged combustion evaporators for the removal of impurities are presented as well as the treatment of the condensates from the evaporators. The attention is paid to the generation of sulphur trioxide in the smelter off-gas.and to the treatment of that in the weak acid bleed-off and to the utilization of the treated acid.

Jan 1, 1992

By A. E. M. Warner

Inco Limited has long and extensive experience in converting nickel-copper primary smelting mattes over a broad range of nickel/copper weight ratios and combined nickel-copper-cobalt contents. At the Copper Cliff Smelter, the composition of the converter product matte has to meet the requirements of the matte separation process; at the Thompson Smelter, converter matte of a different composition is cast into anodes for nickel electrorefining; and in Soroako, Indonesia, a very low copper product matte is granulated for the Japanese market. Recently, Inco has conducted pilot plant testing of three possible nickel-copper matte continuous converting routes, namely flash converting, oxygen top blowing-nitrogen bottom stirring, and tuyere blowing. This test work has generated substantial new information on nickel-copper matte converting chemistry. This overview paper reviews the metallurgy of nickel-copper matte converting, in particular the behaviour of cobalt and the operating conditions required to meet the iron and sulfur specifications of the product matte. The relevant thermodynamic information is used to discuss the industrial data.

Jan 1, 2003

By Musa Karakus

In an attempt to explain the phenomena of lead entrainment during Cu drossing of lead bullion, two different synthetic lead bullions were heated to 1050°C, cooled slowly to various temperatures, and then quenched. The morphology and composition of dross particles that form when Mn is used to desulphurize bullion also were examined. Polished sections of these pyrometallurgical products were examined by process mineralogical techniques to identify the impurity phases, determine their chemical compositions, examine the morphology of the impurity phases and evaluate the potential for lead entrainment in such crystals, and characterize pre-quench and quench-generated phases. The phases crystallized were metallic lead, metallic copper, galena, chalcocite, albandite, Cu14.4Pb2S9. and 5.5Pb2S3.5. Metallic copper formed isometric skeletal crystals, chalcocite formed platy and skeletal crystals, and 1formed crystals and eutectic intergrowth with chalcocite and Cu14.4Pb2S9 or Cu5.5Ph2S3.5. The pre-quench crystals are larger and usually exhibit skeletal forms; the quench-generated phases are only a few micrometers across and disseminated throughout the lead matrix. Skeletal crystals of metallic copper and chalcocite form three dimensional networks that entrain large amounts of metallic lead.

Jan 1, 1989

By Minge Zhao, Yuandong Pei, Zhixing Zhao, Zejun Ma, Lili Ban

"Confocal scanning laser microscope (CSLM) has been applied to carry out the in-situ observation of melting and solidifying characteristics during iron ore sintering process, accompanied with TG-DSC test. It can be found that apparent Liquid phase forming temperature(LFT) and ending solidifying temperature(EST) is about 1190? and 1160?, respectively. Forming liquid phase during sintering process goes through four courses, these are shrinking, expanding, shrinking and expanding coexisting and expanding totally. For Yandi fine, the corresponding temperature of these four courses is about 1120-1160?, 1190-1196?, 1218-1220? and 1233-1270?, respectively. Although CAJ fine has more difficulty in forming initial liquid phase, but when liquid phase expands, it may have better fluidity and easier for liquid phase formation. Adding enough CaO, CAJ fine takes on high fluidity like Yandi fine, because liquid phase during sintering process is formed mainly by reaction between CaO and Fe2O3.IntroductionConfocal scanning laser microscope (CSLM for short) has been applied to carry out the in-situ observation of metallurgical phenomena, especially in steelmaking process. Recently, many researches on ironmaking process were conducted with CLSM. While for high temperature properties during sintering process, there are limited reports on in situ observation1-2). In this paper, melting and solidifying characteristics of iron ore were observed with CLSM under simulated sintering temperature, and high temperature properties of iron ore during sintering process was clarified based on the in situ observation results and TG-DSC research."

Jan 1, 2012

By F. J. J. van Loo, J. K. Kivilahti, M. Paulasto

"Activation mechanism and interfacial reactions in brazing of ShN4 with different AgCuTi filler alloys has been investigated thermodynamically and experimentally. During brazing the AgCuTi filler alloy is divided into two liquids Ll and L2, where the (Cu,Ti)-rich liquid L2 gathers at the ShN4 interface and reacts with it. The concentration of Ti in L2 is high, but due to the strong attractive interaction between Cu and Ti, the activity of Ti in L2 is considerably low. In reaction between ShN4 and Cu-containing brazes a Ti-Cu-Si-N compound is typically formed at the interface. In absence of Cu, in joints brazed with AgTi based filler alloys, extremely Ti-rich solution reacts with ShN4 and as reaction products TiN and TisSh[N] are formed. IntroductionAdvanced ceramics like silicon nitride are increasingly used as structural components in demanding applications as well as in electronics industry. Complex, multicomponent structures for engineering applications generally require interconnections and therefore joinability of ceramics largely determines the possibilities of metal-ceramic structures to enable demanding functions. Brazing with active filler metals, most of which are based on the Ag-Cu-Ti system, has been commonly employed for joining of ShN4 to other ceramics and metals. The interfacial microstructures formed when ShN4 is brazed with Ag-Cu-Ti braze alloys have been discussed in several recent studies [1-7]. However, some inconsistencies exist in the reported results. The formation of layers of TiN and titanium silicides, possibly TisSh, next to the ShN4 has been reported in several studies [1-5], while in another investigation, a layer of an orthorhombic TiSi- Cu-N phase was found beyond the TiN layer [6]. In few investigations the thermodynamics of the ShN4-Ti system has been considered, but no detailed thermodynamic analysis of the chemical interactions between the braze and ShN4 has been provided. In order to resolve which chemical reactions are possible under various joining conditions and thereby to be able to control the brazing of ShN4 the reactions in brazing has to be studied using both microstructural and thermodynamic analysis."

Jan 1, 1996

By C. J. Beyke

In recent years recycling of household batteries has received increasing attention, primarily for environmental reasons. This article reviews the major battery types and some of the technologies available to recycle them. It also discusses issues such as collection and sorting which are related to battery recycling in the United States. Finally, results from research being conducted by the U.S. Bureau of Mines on the reclamation of nickel-metal hydride, alkaline, and zinc-carbon batteries are presented.

Jan 1, 1995

By Kazutaka Kunii

It is invariably certain that after punching for IC Leadframes, scrap metal were generated. These seraps were re-dissolved and in order to use as raw material for leadframes, it is necessary to remove the Ni plating. In this study a simple method was developed for the removal of Ni plating by surface oxidation of Ni plating. For this purpose a fundamental study was carried out on the oxidation behavior of Ni plating. Results showed that by controlling the oxidation condition, a considerably high rate of Ni could be removed.

Jan 1, 1996

By Xie Hao

According to its raw materials orthogonal test scheme is designed and a large number of systemic experiments were carried out in order to study the sintering characteristics of three types of fine ores in Kunming Iron&Steel Co.Ltd(KISC). The effects of carbon mixture ratio and basicity on sintering time, agglomeration ratio, physical properties and utilize coefficient were researched via single factor analysis and range analysis. The experimental results show the best mixture ratio of each fine ore. Analysis found that the influence of the carbon mixture ratio is more significant than which of the basicity on the sintering process except agglomeration ratio of foreign ore.

Jan 1, 2009

By A. Cullaj

Several industrial sites suffer from the contamination of soils from heavy metals, which are emitted among others by anthropogenic mining and metallurgical activities. Effective and economic physicochemical technologies for remediation of these sites remain complicated and costly. A new alternative remediation technique is the so-called phytoremediation. This is based on the ability of some plants to accumulate very high concentrations of metals from soils and thus providing the basis for a remediation of the contaminated sites. This technique as an emerging branch of natural biotechnology, has several advantages compared to the sophisticated physicochemical techniques of soil remediation. It is not only environmentally friendly but also its costs are quite low since it is solar driven. Furthermore plants can accumulate metals to such levels that the mineral recovery maybe feasible even in conventional Ni refinery or smelting operations. In this work, thc potential of many plants to accumulate nickel has been investigated in order to identify the species which offer the best phytoremedial potential for nickel contaminated soils in Albania. Field surveys have been made in five nickel-containing sites in order to identify the nickel tolerant species that have spontaneously grown in contaminated soils. Atomic Absorption Spectrometry measurements were carried out on 145 different plants collected. 16 of them were identified as having an hyper ability to accumulate nickel since they contained more than 10 000 mg Ni per kg (DW). Seven taxa are of Alyssum genus and one of Bornmuellera genus of Cruciferae. The highest accumulation of nickel was present in aerial parts of Alyssum murale var. chlorocarpum Hausskn (25 500 mglkg or 2.5%) and Alyssum markgrafli O.E. Schulz (23 700 mg/kg or 2.37%). The seeds germinated are more evidenced at A.m.var. chlorocarpum, about 63%. These plants are suggested as the most promising species to be used for phytoremediation purposes in nickel contaminated soils and phytoextraction of nickel.

Jan 1, 2003

By A. Cullaj

Several industrial sites suffer from the contamination of soils from heavy metals, which are emitted among others by anthropogenic mining and metallurgical activities. Effective and economic physicochemical technologies for remediation of these sites remain complicated and costly. A new alternative remediation technique is the so-called phytoremediation. This is based on the ability of some plants to accumulate very high concentrations of metals from soils and thus providing the basis for a remediation of the contaminated sites. This technique as an emerging branch of natural biotechnology, has several advantages compared to the sophisticated physicochemical techniques of soil remediation. It is not only environmentally friendly but also its costs are quite low since it is solar driven. Furthermore plants can accumulate metals to such levels that the mineral recovery maybe feasible even in conventional Ni refinery or smelting operations. n this work, the potential of many plants to accumulate nickel has been investigated in order to identify the species which offer the best phytoremedial potential for nickel contaminated soils in Albania. Field surveys have been made in five nickel-containing sites in order to identify the nickel tolerant species that have spontaneously grown in contaminated soils. Atomic Absorption Spectrometry measurements were carried out on 145 different plants collected. 16 of them were identified as having an hyper ability to accumulate nickel since they contained more than 10 000 mg Ni per kg (OW). Seven taxa are of Alyssum genus and one of BornmueIIera genus of Cruciferae. The highest accumulation of nickel was present in aerial parts of Alyssum murale var. chlorocarpum Hausskn (25 500 mg/kg or 2.5%) and Alyssum markgrafii O.E. Schulz (23 700 mg/kg or 2.37%). The seeds germinated are more evidenced at A.m.var. chlorocarpum, about 63%. These plants are suggested as the most promising species to be used for phytoremediation purposes in nickel contaminated soils and phytoextraction of nickel.

Jan 1, 2003

By A. Vahed

The Goro Nickel Project is situated in the Southern Province of New Caledonia. Inco Limited and Goro Nickel S.A. have developed a process that features the use of pyrohydrolysis to produce nickel oxide. The process treats a blend of laterites by Pressure Acid Leaching followed by solvent extraction of nickel and cobalt using Cyanex 301®. Purified nickel chloride solution is converted to high purity NiO product and 6M hydrochloric acid, which is recycled back to the SX circuit. In co-operation with Andritz AG, spray roaster and fluid-bed pyrohydrolysis technologies were examined for this purpose. Tests were conducted at the Andritz AG pilot plant in Vienna, Austria, and at Goro in larger scale installations. The latter served to establish process engineering design parameters for scale-up. Several process variables were investigated in both technologies and the off-gas characteristics were established. Fluid-bed pyrohydrolysis was selected for the Goro commercial plant, primarily because it produced a granular nickel oxide. The main focus of this paper is to outline the results obtained in pilot plant studies of liquid fueled fluid bed pyrohydrolysis for the Goro Project. Keywords: lnco Goro Nickel, Fluid Bed Pyrohydrolysis, Pilot Plant Tests

Jan 1, 2004

By Harry Littleton, Jr. Scarber, Wanliang Sun

"The Lost Foam Casting (LFC) process is relatively immature when compared to other casting processes. To make the process more robust, computer modeling is needed to reduce lead times and casting defects. In this study, metal filling of lost foam aluminum castings was visualized using state-of-art real time X-Ray technology. Metal filling of the lost foam casting was simulated using a commercial software package. The result of the computer simulation was compared with the results of the real time X-Ray visualization. Some of the computer simulation results agreed with the real time X-Ray visualization, but some did not. Based on other studies using real time X-Ray technology, new input variables, such as foam density variations, were developed for the computer modeling. With the new variables, modeling of the lost foam casting process becomes more realistic. IntroductionMold filling of the Lost Foam Casting (LFC) process is an important step toward making a quality part. In the LFC process, molten metal is poured against a refractory coated foam pattern surrounded by dry sand. At the pouring temperature of aluminum, the foam pattern is decomposed into 30% (wt) gaseous and 70% (wt) liquid foam pyrolysis products. Existence of the gaseous foam decomposition products significantly increases the back pressure on the metal stream compared with the conventional open cavity sand mold. Entrapment of the liquid pyrolysis products during the metal filling generates many casting defects, such as internal pores, fold and blisters. Existence of these casting defects sometimes seriously degrades the quality of the components manufactured by the LFC process. Understanding and controlling the metal filling of the LFC process will certainly make this process more robust."

Jan 1, 2004

By Olga K. Karakasi, Angeliki Moutsatsou, Ioanna Kavallari

"The present study focuses on the amelioration of the behaviour of high calcium fly ash (HCFA), investigating its application in a new environmental field: oil spill clean up. High calcium fly ash is a by-product of electric power plants, produced annually in large quantities, whose greater amount is landfilled. Some of its properties, such as its chemical and mineralogical composition, its fine particle size, its porosity, floating ability and hydrophobic character make it an attractive material for this purpose. Researches showed that when added to an oil spill, it forms a semi-solid phase, which allows the quite total removal of the oil, but it is not stably retained on the surface. In order to ameliorate its floating ability, the decrease in its specific gravity by mixing with a lighter material is investigated. In the present study the mixing with two materials, already used in oil spill clean up, sawdust and a polymer, has been examined. Addition of 15-25% w/w sawdust to HCFA results in a material with better performance than HCFA or sawdust alone: it has a satisfactory floating ability and allows total removal of oil. Addition of the polymer, however, has resulted in no significant amelioration of the oil sorption behaviour of HCFA, probably because no affinity between HCFA and polymer has been achieved.IntroductionCoal fly ash is a by-product of coal combustion in electric power plants, produced worldwide in huge quantities, approximately 500 million tones annually. High calcium fly ash (HCFA) is classified to class C presenting a (Al2O3 + SiO2 + Fe2O3) > 50%. The production of lignite fly ash in Greece comes up to 13 million tones annually, of which only 12% is used in construction applications, the other being landfilled [5, 6].Besides its limited application worldwide as a construction material, research is focusing on the development of new environmental applications, such as waste stabilisation and solidification, soil and water environmental improvement [9, 12]. For the application of fly ash in further environmental fields several chemical modifications have been applied, in order to improve its properties. Extensive research has been focused on the conversion of both coal and lignite fly ash to zeolite and its further application in environmental field, such as the uptake of inorganic (heavy metals and ammonium [8, 11]) or even organic compounds (methylene blue [15]) from waste water streams, or the use as molecular sieves, to adsorb water molecules, SO2 and NH3 from gas streams, due to the high cation exchange capacity and porosity of the produced zeolithic material. Furthermore, lignite fly ash has been combined with sodium silicate solution, prepared by treatment of rice husk ash, and tetrapropylammonium bromide, to synthesise hydrophobic zeolite ZSM-5 [4]."

Jan 1, 2008

By B. C. Blakey

Unlike most hydrometallurgical slurries, those containing significant concentrations of goethite are typically highly viscous and shear-thinning, even at solid volume fractions below 5%. The viscosity may also depend upon time. These characteristics must be taken into consideration in slurry transport and heating. The technical literature is replete with apparent contradictions regarding the viscous behavior of these slurries, which may be due, in part, to variations in viscosity-measuring techniques. We present techniques that yield consistent results suitable for use in process design. A striking degree of time-dependent behavior is demonstrated for a laterite slurry. Reliable methods to design and analyze tubular transport and heating systems for time-independent slurries are summarized. Rules of thumb are then offered to account for the effects of time-dependency.

Jan 1, 2000