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By Martin E. Nelson

Several heavy metal separation techniques are currently being developed for soil remediation at various Department of Defense and Department of Energy (DOE) Facilities. The majority of these techniques involve a wet process using water, PH modifiers or other compounds. The United States Naval Academy (USNA) has developed a dry process for heavy metal separation. The process uses air classification technology to concentrate the metal contaminant into a fraction of the soil. The advantages of this dry process are that it creates no contaminated by product and uses commercially available technology. The USNA process is based on using a Gayco-Reliance air classifier. Tests have been conducted with the system at the Naval Academy and the University of Nevada-Reno (UNR). The USNA tests used soil from the Nevada Test Site mixed with bismuth at a concentration of 500-1000 ppm. The UNR tests used soil from four DOE sites mixed with uranium oxides and plutonium at an activity level of 100-700 pCi per gram. Concentration of activities and volume reduction percentages are presented for the various soils and contaminants tested.

Jan 1, 1995

By Patrick R. Taylor

Sub-micron sized boron carbide powders have been synthesized in a non-transferred arc thermal plasma reactor. Precursors for this synthesis are boric acid or boron oxide powders and methane. The powders produced were characterized in terms of size, shape and purity. Methods to increase the purity of the product were evaluated and included hot water leaching to remove unreacted oxides and controlled temperature, air roasting to remove excess carbon. Theoretical results are also presented on the thermodynamics and mechanisms of the synthesis reactions.

Jan 1, 1994

By Kimio Itagaki, Makoto Ohtsuka, Kouki Chiba, Minoru Matsumoto

"The properties of Ni-Mn-Ga films such as chemical composition, crystal structure, microstructure and transformation temperature were investigated with respect to sputtering conditions in the present study. The Ni-Mn-Ga films were deposited on a polyvinyl alcohol substrate with a radio-frequency magnetron sputtering apparatus using the NisoMn2sGa2s and Nis2Mn:«1Ga24 targets. After separating from the substrates, the films were annealed at the temperature between 873 and 1273 K for 3.6 ks. The chemical composition of the films depended on the radiofrequency generating power, however, there was no dependence on the heat treatment temperature. Each deposited film had a columnar grain structure. After heat treatment, the width of columnar grains widened and then became indistinct with increasing heat treatment temperature. The Heusler type cubic crystal structure of the fi4n with heat treatment at 1073 K changed to the tetragonal one through the martensitic structural transformation during cooling. The martensitic structural transformation temperature increased with increasing nickel content of films, while the Curie temperature decreased. The film obtained at 200 W using the Nis2Mn24Ga24 target after heat treatment at 1073 K showed one-way shape memory effect through the reverse martensitic structural transformation during heating.IntroductionThe ternary intermetallic compound NiiMnGa has a Heusler-type crystal structure and is an intelligent material, which has a shape memory effect and a ferromagnetic property. The martensitic structural transformation occurs within the ferromagnetic temperature region. The cubic crystal structure of L21 at high temperature changes to a tetragonal one through the martehsitic structural transformation during cooling. The films of this compound can be applied for an actuator of micro-machines."

Jan 1, 2000

By Hiroshi Nakajima, Kotobu Nagai, Toshihiro Hanamura

"Low carbon ferritic steel bars with ultra-fine grain structure was developed through a warm rolling for the first time by the present authors. They show better low temperature toughness than conventionally hot-rolled plates. Hence, the brittle fracture surfaces in Charpy tests were examined in terms of the effective grain size of fracture, compared with those of conventional QT steels. The ductile-to-brittle transition temperatures were in good accordance with those for the QT steels if referred to the effective grain size of fracture: · However, the size was a few times that of the ferrite grain. This means the grain refining is not yet fully utilized from the viewpoint of low temperature toughness. The anisotropy of· the impact properties and the annealing effect of highly dislocated structure on the toughness are also discussed in the present paper.IntroductionFor structural materials, both high strength and good toughness are required. Well-known approaches for obtaining better toughness for steels are as follows:1) Grain refining2) Addition of Ni3) Thin plate effect by cracking parallel to the rolling direction prior to crack propagation4) Contribution of metastable austenite.Among them, only the grain refining can raise the strength and improve the toughness. And it is well known that the finer the ferrite grain size, the lower the ductile-to-brittle transition temperature. For example, in the case of 0.11 carbon steel, the transition temperature decreases linearly to in d 1/2 [1 ]. However, these have been told in the regime of coarse grain size that is larger than 10 µm in diameter. There ~as .been no study dealing with the low temperature toughness in the regime of ultra-fine grain size with a diameter in the order of 1 µm."

Jan 1, 2000

By Luben Xie, Lin Hu, Qiang Wang, Min Gan, Tao Jiang, Wenqi Li, Yi Wang, Xiaohui Fan

"The mineralization behaviors of typical fluxes are studied by investigating the microstructures with optical microscope. The results show that the reactions begin with between iron ore and lime, limestone with small particle to form primary liquid. Then coarse limestone, dolomite and serpentine take part in reaction under the action of primary liquid. Limestone is the easiest to mineralization, next dolomite, and the last is serpentine. The higher basicity and smaller fluxes size favor the mineralization process of dolomite and serpentine.IntroductionThe purposes of adding fluxes into sintering are that:(1) to increase the basicity of sinter, so as to reduce even eliminate addition fluxes into BF(blast furnace) and decrease the coke ratio of BF[1,2]. (2) to decrease the melting point of sintering mixture to ensure sintering can be carried out at a lower temperature and reduce the energy consumption. (3) to improve the qualities of sinter by forming binding phase with iron ore fines [3].Flux is another significant component for sinter besides iron ore, especially for high basicity sinter[4]. The proportion of flux is usually higher than 10% in sinter mixture(excluding return mine).There were many reports about the influence of the flux types on sintering, such as limestone, dolomite, lime and so on[5-7]. It is very important to choose suitable fluxes for iron ore sintering. Although the effect of flux size on sintering also has been researched, the mineralization behaviors of the fluxes in the sintering process has not been illuminated. The paper will study the mineralization behavior of fluxes in sintering."

Jan 1, 2011

By Wei Gao, Qing-cai Liu, Cun-fang Lu, Jian Yang, Hinmi Zheng

"The mode of occurrence of sulfur and mercury in 57 Chinese bituminous coals have been examined using X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), and Zeeman atomic absorption mercury spectrometer. Mercury levels in coal are related to the geographic location of the coals and types of the coals. A synthesis of result indicated that most likely occurrence modes of mercury in high-sulfur and high-mercury coals are in solid solution in pyrite. Our study from 57 coal samples showed that most values of mercury concentration in coal varied from 100 to 1000 ng/g with an average of approximately 500ng/g, and mathematical model about correlation between mercury and sulfur was gained by mathematical statistics. This is apparent that mercury and sulfur vary concomitantly from coal data (table 3) , the high correlation between them in all coals at confidence of 95% ( a=0.05 ) .1. INTRODUCTIONThere contained about one trillion ton abundant coal resources in China. As a leading level of proven coal reserves in the world, the coals mainly distributed in north China and northwest China, especially in Shanxi, Guizhou, Shanxi provinces and Inner-Mongolia autonomous region. At the same time, China has the largest production and consumption of coal, and has the output of coal nearly accounted for 37 percent of the world's production. Coal-fired power plants are the major source of energy generation in China, and the proportion of coal combustion is up to 75 percent in the total energy configuration. Therefore, the mercury pollution caused by coal-fired has become a topic of wide-spread discussions since 1990. The contamination of mercury of human activities accounted for 10 to 30 percent [1], and the mercury emissions of coal-fired flue gas has made the greatest contribution to the pollution of atmosphere[2] In the past 30 years, the global increasing concentration of mercury pollutant in atmosphere maybe result from coal combustion[2]. The mercury emissions caused by coal-burning has become the main reason of China's mercury pollution, and the characteristics of mercury pollution is closely related to China's energy configuration, additionally, the features of mercury pollution have changed from the point pollution in 1970's to diffused pollution today[3]. Mercury can be found in various types of coals, and it is evaporated into gas phase during the combustion process."

Jan 1, 2011

By Carlos Maurício Fontes Vieira, Sergio Neves Monteiro, Diogo Neves Henriques

"This work evaluates the effect of incorporation of an ornamental rock waste into an industrial clayey body used for roofing tiles fabrication. Formulations with 0, 10, 20 and 30 wt.% of waste were prepared by replacing the sand in the industrial clayey body. The plasticity of the formulations was determined by the Atterberg limits. Specimens were fabricated by 18 MPa press-molding and then fired from 850 to 1100oC. The specimens were tested to determine the water absorption, linear shrinkage and three points bending flexural strength. The results indicated that the waste improves the extrusion performance of the clayey body by decreasing its plasticity. The use of the waste was beneficial to the water absorption and mechanical strength of the fired clayey ceramic at temperatures above 1000 ° C.IntroductionOrnamental rock is a natural resource available in the municipal area of Santo Antônio de Pádua and located 150 km from the city of Campos dos Goytacazes, northe of state of Rio de Janeiro, Brazil. Intense industrial activity related to ornamental stones, especially gneisses, is traditionally occurring in the region. After mining, the flagstone is submitted to sawing to obtain blocks and then, after a manual operation, the final products are small flagstones [1,2]. During the sawing operation, a sludge composed of water and fine particles of rock is generated. A monthly production of 1000 tons of ornamental rock waste is estimated to be produced at Santo Antônio de Pádua. The final disposal of this waste has brought serious environmental problems. Since most industries do not have an adequate sludge treatment, the waste is contaminating the soil and underground waters as well as obstructing rivers and lakes.Ceramic bodies industrially fabricated in the municipal area of Campos dos Goytacazes, 280 km from the city of Rio de Janeiro, are still empirically elaborated using a mixture of local clays. These clays are predominantly kaolinitic mineral, associated with high plasticity. Due to the excessive plasticity of the ceramic bodies, it is common to have dimensional defects in the final products after the drying and firing processes. Moreover, the kaolinitic structure and the presence of aluminum hydroxide confer a refractory behavior to the local clays. This impairs sintering during the firing operation. In the case of clay ceramics for civil construction, this results in greater porosity associated with elevated values of water absorption and low mechanical strength [3,4]. To avoid these problems, it is necessary to reformulate the ceramic body composition. The addition of both non-plastic materials to reduce plasticity and fluxes to condition the refractoriness is a possible alternative."

Jan 1, 2008

By V. Vergara

Four copper composites were obtained by mechanical alloying, using as dispersed phases of four carbide powders; they were: boron carbide, chromium carbide, silicon carbide and zirconium carbide. The purpose of this work was to study some characteristics of these compounds and their feasibility for use as materials for electrical equipment. Raw materials used were copper powder finer than 150 mesh, and 2-4 vol % of powder carbides finer than 325 mesh. The alloying process was carried out using both a Spex 800-D mill with tungsten jars and balls and a hardened stainless steel jar and balls, the purpose of which was to measure the degree of contamination induced by the milling media. The changes in particle size, morphology and microstructure of copper alloys were studied with SEM and TEM for each alloyed powder. The degree of saturation of copper by the carbides was measured by X-ray diffraction. Sound samples were obtained by hot isostatic pressing at 1073°K. The best characteristics were obtained for the compound copper-chromium carbide, based on their hardness, tensile strength and electrical conductivity values. The other alloys failed due to their excessive brittleness after hot pressing.

Jan 1, 1999

By Mohamed Ahmed, A. Kawy

"Smelting of scrap copper and residual anodes and cathodes carried out in a reverberatory type furnace. In this, deoxidation process is carried out by wood, which acts as a resource of reduction gases such carbon monoxide, hydrogen and methane. Use of wood causes the formation of soot pollutants and efficiency of oxygen removal from copper is low leading to added costs in removing contaminants. This expensive problem was solved by using of reformed natural gas as a source of reduction gases (CO+ H2).IntroductionThree reverberatory furnaces were used for smelting of scrap copper and residual anodes and cathodes. Each furnace had a 7tpd capacity and was operated at 1183 °C.In this furnace, Step1-compressed air supplied by tubes from the side of the furnace to remove sulfur from copper matte by oxidation .The copper is also oxidized to copper oxide .[1]Step 2- copper from matte is deoxidized by a reductant. Typically deoxidation process is carried out using wood as a resource of carbon monoxide, hydrogen and methane which are the reduction gases. Use of wood causes the following:1- Forms soot pollutants2- Oxygen removal efficiency from copper is low; more contamination in copper matte increased energy in deoxidation3-the process is highly expensive.In the recent trends, this problem has been solved by using reformed natural gas as a source of reduction gases (CO+ H) .This results in 1-Reduced pollution during smelting.2- High efficiency in the removal of oxygen from copper to produce oxygen free copper. The surface of copper produced from this method is smooth which helps in forming and machining.3- Low cost and natural gas is more readily available in Egypt than wood."

Jan 1, 2010

By Esperidiana A. B. Moura, Célio H. Wataya, Roberta A. Lima, Rene R. Oliveira

The purpose of this study was to investigate the mechanical, morphological and thermal properties of biodegradable composites based on aliphatic-aromatic copolyester/polylatic acid blends (PBAT/PLA blends) reinforced by açaí seed fibers, an abundant byproduct of the açaí fruit agro industry. The biodegradable polymeric composites were prepared by melting extrusion process using a twin-screw extruder machine. The fibers removed from the açaí seed were used as the reinforcement and PBAT/PLA blends as the matrix. The influence of the açaí seed fibers addition on properties of composites was investigated by tensile and impact tests, SEM, DSC, and XRD analysis. Correlation between properties was discussed. In addition, açaí seed fibers characterization by SEM, XRD and WDXRF have also been carried out. The addition of açaí seed fibers on biodegradable PBAT/PLA blends showed that it is possible to get interesting property gains in biodegradable polymer by using waste from renewable sources.

Jan 1, 2015

By Maria K. Kojo

The interaction between various slags and a nickel concentrate containing pyrite, pentlandite, and violarite were investigated by submerging concentrate pellets in molten slags. The slags were contained in MgO-A12O3 spinel crucibles. The slag oxidizes the iron sulfides in the concentrate, resulting in a nickel matte. The amount of S02 gas formed during reaction was measured to determine the oxidation reactivity of the slags. The experimental variables included temperature, the ferric/ferrous ratio of slag, and other slag properties such as the FeO/SiO2 ratio and the MgO and NiO contents. The reactivity of the slag depended in a complex manner on its oxidizing power, viscosity, and interfacial tension. The slag composition for the greatest reactivity was determined to be Fe3+/Fe2+ = 0.3, Fe/SiO2 = 1.3, and % MgO = 2. This slag, however, caused substantial foaming. Increasing the MgO content to 10% or replacing it by 5% MgO + 8% NiO eliminated at a slight decrease in reactivity. The implications of the findings from this work in the bath smelting of nickel sulfide concentrates are discussed.

Jan 1, 1995

By Pekka Hanniala

The Outokumpu Flash Smelting process today is the most feasible method for copper matte smelting. The economic feasibility of the process has always been one of the main decision making criteria in smelter projects. Thus, today about 50 % of the world primary copper production utilizes Outokumpu Flash Smelting Technology. However, in the future, environmental criteria will have stronger and stronger impact on decision making. Flash Smelting technology offers the best pollution control features of any process. today. It is foreseen that, in the near future, the global trend will be that all the smelters must decrease their emissions at an accelerating rate, compelling the smelters to make increasingly larger investments on environmental protection. In most of smelters ?today, Peirce-Smith converting and transfer of the molten material in ladles are the number one pollution source. The key today for copper converting and minimizing emissions is the Kennecott-Outokumpu Flash Converting process, which has proven to be the most effective converting method in terms of pollution control and, production efficiency including capital and operational costs. Outokumpu Flash Smelting technology is applicable also for small to medium scale smelters but the most interesting area is the upper capacity limit for smelting in one line, which has not yet been reached. We predict that by the year 2000 to 2005, there will be at least one smelter which produces 500,000 tonnes of Cu per year based on one Flash Smelting and Flash. Converting unit. The current state-of-the-art of the Outokumpu Flash Smelting - Flash Converting process is presented in this paper as well as some new options for copper production to be utilized in the near future but which are available already today.

Jan 1, 1998

By D. R. Flynn

The recovery of nickel and cobalt from electromachining sludges in the form of relatively high-purity marketable products has been investigated. The investigation has shown that a series of metallurgical unit operations can be performed to recover nickel and cobalt from electromachining sludges in the form of al kal i nickel ic hydroxide and cobalt sulfate/cobal t metal, respectively. The recovery unit operations for nickel include high pH cyanide complexation, followed by oxidation and precipitation of alkali nickel hydroxide. The resultant filtrate can be treated for cobalt recovery by neutralization and acid baking to produce cobalt sulfate. The cobalt sulfate can then be treated for cobalt recovery by electrowinning. Results from laboratory bench scale test work are discussed in terms of appropriate operating conditions.

Jan 1, 1991

By Ole Rud Bendixen

Topsoe has developed a Wet gas Sulphuric Acid (WSA) process which effectively recovers SO2 in off-gases from non-ferrous smelters and roosters. The product is concentrated sulphuric acid of typically more than 96 wt% irrespective of SO, concentration in off-gas. The process does not generate any waste products or waste water and does not use any absorbents or other chemicals. In the process, up to 99.3% of the SO2 is converted catalytically into SO3, which reacts with water in the gas, hereby forming gaseous sulphuric acid. The acid is condensed in a WSA condenser of proprietary design. Excellent heat economy and practically no sensitivity to the water balance mean that no extra sulphur burning is required at any S02 concentration, The process is especially well suited for treating off-gases where the SO2 content is lower than approx. 5-6%, and it is a good alternative to a complete renovation of a smelter. However, also off-gas from flash smelter may be treated. The process has found good use in both molybdenum and lead roosters. An example from a molybdenum roaster in Chile shows that 97-98wt% acid is produced from a 2.3 % S02 gas. This plant is situated in the outskirts of Santiago and represented a major local source of SO2. The plan was started in May 1993.

Jan 1, 1996

By B. Q. Li, Y. Shu, K Lynn

"This paper discusses the effects of magnetic field and internal radiation on the melt flow and solidification morphology during solidification processing of oxide crystals for optoelectronic and remote sensing applications. The numerical solution of the integral differential equation characterizing the internal radiation and the magnetohydrodynamic equations describing the magnetic and transport phenomena is obtained by applying the combined discontinuous and continuous finite element method. The results show that both internal radiation and an externally applied magnetic field can have important effects on the melt flow and solidification behavior during the melt processing of oxide materials.IntroductionOptical single crystals are widely used in optical and electronic devices. These crystals are often grown from high temperature oxide melts under strictly controlled conditions. As in the well-known single crystal growth processes for semiconductor wafers, thermal gradient in the melt is a major contributing fuctor to the oxide melt pool. Unlike the semiconductor single crystal growth processes, however, the oxide melt is semitransparent and internal thermal radiation plays an important role in redistributing the thermal energy in the melt pool. Our recent experience with pilot-scale plant measurements also shows that the oxide melt is electrically conducting, although its electrical conductivity is considered much lower than the liquid metal or semiconductor melt.The fact that the oxide melt is absorbing and emitting in the thermal radiation frequency range makes it difficult to study the thermal energy transport in the melt pool. This is because thermal radiation is governed by a hyperbolic differential equation, which is different from those describing the transport processes in liquids. Also, our understanding of how thermal radiation interacts with other transport mechanisms such as convection and conduction is rather limited at point in time, in particular in high temperature oxide melts for optical single crystal processing."

Jan 1, 2004

By den Bulck A. Van

In Europe, 50% of the copper originates from recycling. High-Cu containing scraps are regularly rich in impurities like Fe, Ni, Sn and Pb. Many high-Cu containing scraps are fed directly into anode-furnace casting installations or furnaces with limited refining capability. The impurities levels of the anodes produced in these processes should however remain acceptable for further electro-refining. The distribution of Sn between copper and slag has been investigated for conditions relevant to copper converting. Unlike previous studies, this work focuses on the behavior of Sn relevant to fire refining conditions, which are essential for anode refineries.In this study, liquid Cu–1Sn and CuOx–FeOy–SiO2 slag, with CaO additions, were equilibrated at 1300 °C in vacuum sealed SiO2 ampoules. After metal–slag equilibration, the samples were quenched in water. The composition of the slag and Cu metal was investigated with Electron Probe X-ray Microanalysis. The distribution coefficients of Sn between slag and Cu metal were determined as a function of slag composition.

By Mingchun Lu, Zhe Wang, Mingming Cao, Xiangdong Xing, Shan Ren, Jianliang Zhang, Zhengjian Liu

"The effect of reduction temperature on the vanadium titano-magnetite carbon composite pellets was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the discussion has put emphasis upon the enhanced reduction mechanism of additives containing CaF2 and NaF in this paper. The results showed that the reduction temperature of 1350°C was needed for the generation, mergence and growing up of metallic iron as well as monomer dissociation between metallic iron particles and slag phase in the vanadium titano-magnetite metallization pellets. The iron compound was completely reduced into metal iron, and Fe2Ti04 was mainly transformed into metal iron, (Fe,Mg)Ti205 and FeTi03 at 1350°C. The maximum metallization ratio was only 88.5% at 13500 for 30 min without any additive. However, with the addition of 3.0% CaF2 or NaF, the metallization degree of pellets could reach up to 94.8% and 92.5%, respectively.IntroductionVanadium titano-magnetite which is mainly distributed in the area of Panxi, Chengde and Maanshan in China is a kind of complex iron ore which contains various valuable metal elements such as iron, vanadium, titanium, etc. Among the above areas, Panzhihua (Sichuan Province in China) area possesses the largest deposits of vanadium titano-magnetite and the future reserves are more than 100x108t, and the reserves of Ti existing as Ti02 reach to 8.7x108t which occupy over 91% of the whole nation and ranked No.1 in the world[1]. Lots of researches on the comprehensive utilization of vanadium titano-magnetite have been conducted in the world. And many technological processes have been applied successfully in industrial production. Among these processes, the process of rotary kiln-electric furnace is employed to recover iron and vanadium in South-Africa, while the process of blast furnace-rotary furnace is widely used in Russia and China. Besides, many researchers have made efforts on employing new direct reduction process to realize the effective comprehensive utilization of vanadium titano-magnetite[2-4]. However, the direct reduction process is only researched in laboratory and it has not been used in industry."

Jan 1, 2013

By E. J. Peterson

Oil shale retorting induces mineral and chemical reactions to occur on the macroscopic and microscopic levels in the kerogen-bearing marlstone. The nature and extent of the reactions is dependent upon process variables such as maximum temperature, time at temperature, atmosphere, and raw shale composition. This report describes the investigation of the mineral, chemical, and trace element release properties of spent shales retrieved from an experimental in situ retort at Occidental Oil Shale, Inc. 's Logan Wash site in Garfield County, Colorado. Correlation between mineralogy of the spent materials and the mobility of major, minor, and trace elements are indicated, and relationships with important process parameters are discussed. The progress .of carbonate decomposition reactions and silicat ion reactions is indicative of the processing conditions experienced by the shale materials and influences the mobility of major, minor, and trace elements when the solids are contacted by water. Shale minerals that are exposed to the extreme conditions reached in underground retorting form high temperature product phases including akermanite-gehlenite and diopside-augite solid solutions, kalsilite, monticellite, and forsterite. The persistence of relatively thermally stable phases, such as quartz, orthoclase, and albite provide insight into the extremes of processing conditions experienced by the spent shales. Leachate compositions suggest that several trace elements, including vanadium, boron, fluoride, and arsenic are not rendered immobile by the formation of the high-temperature silicate produce phase akermanite-gehlenite.

Jan 1, 1981

By Richard D. Hagni

Process mineralogy has not been given adequate attention in years past, because geologists have not been sufficiently interested in applying mineralogical techniques to industrial processes, and most process engineers are not adequately trained to use them. Although some individuals and institutions have made efforts to improve the situation, it is only in the last few years that the significance of applying the methods of mineralogy to a wide variety of industrial processes has been fully appreciated. Presently, the formation and organization of several groups devoted to applied mineralogy have created a more amenable climate for the development of process mineralogy. As a result, the presentation, discussion, and publication of the results and case histories of process mineralogy have become fairly common. Short courses affording hands-on experience with applied techniques are now available to the many geologists and process engineers engaged in industrial mineralogical processes. The future role of the process mineralogist is viewed as an expanded one, which will increase in value.

Jan 1, 1982

By T. T. Chen

The manganese oxide scales, consisting mainly of MnO2, characteristically occur in banded colloform structures which adhere to porous layers of PbSO4 and PbO2 that oxidized from the rolled Pb-0.7% Ag anodes. Hydrous Mn oxides, Mn3O4 and amorphous Mn oxides are believed to be also present. Tiny particles of gypsum, PbSO4, SrSO4 and AgCl are entrapped in the colloform masses. The gypsum originated from the Zn electrolyte; strontium carbonate was added to the ZnSO4 solution to control Pb, and silver originated from the anodes. Some of the colloform bands contain minor amounts of Pb, implying a limited degree of dissolution of the Pb during electrolysis. Other colloform bands incorporate trace amounts of Zn. Colloform structures permeated with silica gel are presumably caused by the high silica content of the electrolyte.

Jan 1, 2009