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By Nathalie Neveux

For the first time, dehydrated ferrous sulfate was successfully used for the dry synthesis of potassium ferrate. In addition, ferrate ion is stabilized as a solid solution where hexavalent iron is partially substituted by S(V1) leading to a sulfato-ferrate having the following formula K2(Fe,S)04. This substance has an efficient life time of about six months. Ferrate ion is a powerful oxidant ( EO = 2.2V ), a bactericidal agent and possesses coagulant, flocculant properties. Its reduction generates nascent oxygen, hydroxyl groups and Fe(OH)3. Alkali metal ferrate is probably the future global agent for water treatment. Applications of this material in the field of urban and industrial effluents treatment have been investigated. Heavy metals cations such as Cu, Cd, Mn, Ni, Pb, Zn, ... were successfully removed. The results of sulfato-ferrate use for cyanide destruction, decrease in COD, soil, discoloration of pulp and paper effluents will be summarized.

Jan 1, 1999

By M. Vondersaar, B. Bulnes

Quemetco, Inc.,. as a subsidiary of RSR Corporation, operates one of RSR's three secondary lead smelters in the City of Industry, California, next to a residential area within Los Angeles County. The Reverberatory furnace serves as the main reactor for melting lead grid and paste recovered by the battery crushing system. Feed material is introduced via screw conveyor after drying in an upstream rotary kiln. Slag produced by the Reverb flows directly to an electric arc furnace. Products from this one-pass furnace system consist of soft lead bullion from the reverb, hard lead bullion from the arc furnace, and a non-hazardous slag from the arc furnace. Furnace bullion is processed into finished product in a six-kettle refinery. An overview ·of plant operations is presented. Where applicable, references will be made to changes that have taken place during the last decade.

Jan 1, 2000

By Amir Rehmat

The Institute of Gas Technology has developed a fluidized-bed process for recovering direct reduced iron from blast furnace flue dust a material currently considered to be a waste from the iron and steel industry. In the process, a portion of the carbon in the flue dust is combusted to supply energy for the endothermic reaction between carbon and steam. The reaction produces reducing gases comprised of carbon monoxide and hydrogen both of which react with iron oxides to produce reduced iron. Up to 95 percent of the iron oxides contained in the waste stream can be reduced to elemental iron. The vitiated reducing gases emanating from the process can be used as fuel in the plant. The yield of iron depends upon the quantity of iron oxide present in the flue dust and generally ranges from 20 to 30 percent of the waste stream. The investment cost estimated for a single processing train dedicated to one steel plant can be recovered in less than one year.

Jan 1, 1996

By W. G. Davenport

This chapter extends our mathematical description of flash smelting to -nitrogen in the flash furnace blast. As in chapters 4 and 5, the discussion is limited to auto thermal smelting (no hydrocarbon combustion). Hydrocarbon combustion is introduced in Chapter 9. Outokumpu flash furnace blast is a mixture of air and industrial oxygen. Most of its N2 originates in the air portion of the blast. A small portion originates as an impurity in the industrial oxygen. The nitrogen entering a flash furnace must always be heated from its input temperature, 298 K in this chapter, to its off gas temperature, -1500 K. Energy must be supplied for this purpose. With auto thermal smelting, the energy is-provided by oxidizing extra Fe-and S.

Jan 1, 2001

By G. C. Yao

Branch and needle-shaped intermetallic compounds of iron, silicon and aluminum normally exist in the molten aluminum. If a suitable amount of manganese metal is added into molten aluminum, the shape of the intermallic compound particles may become lumpish and spherical. According to the difference in electric and magnetic properties of these impurity particles and molten aluminum, these impurity intermetallic compound particles can be separated by applying an alternating magnetic field. In this experiment the alternating magnetic field was formed by a "c" type loop with AC (50Hz) current. The inner vacuum of the fireclay refractory separator is 25xl5xl30mm3 with a lateral baffle inside. The separator was put into the interspace of the "c" type loop. It was found that the longer the separation time, the larger the amount transferred of impurities. The amount of transferred impurities increases with the increase of separation time and intensity of magnetic field. The addition of manganese metal enhances significantly the efficiency of impurity separation

Jan 1, 2003

By Gerhard Bayer

X-ray and thermoanalytical studies were carried out on the formation and stability of Ca-, Mg-and Mn-tungstate, and of the corresponding minerals scheelite and wolframite. The tungstates were synthesized by different methods: precipitation from solution, solid state reactions, displacement reactions with solutions and in the solid state. The reactivity of natural scheelite and wolframite with different salt solutions and in mixtures with other minerals was investigated.

Jan 1, 1989

By Emilia Visileanu, Eftalea Carpus

"Ecological economic policy shall be understood as the sum of political, economical and environmental measurements aimed at the entire economy dematerialization and the dematerialization shall be ""imposed"" since the designing stage of goods and services"". European textile and clothing industry with a long leading tradition in terms of innovation, fashion and creativity, continues to be one of Europe's major industrial sectors. Textile industry affects the environment by high consumption of water, energy and chemicals, as well as by the large amount of waste it generates as a result of using a large number of chemicals and technological processes.Textile waste prevention, reduction and ecological exploitation require the implementation of new management and education tools.Introduction“Europe must learn from the experience of global economic and financial crisis ""- this was the conclusion of the European Commission that has elaborated a ten-year strategy designed to reinvigorate the economy and make possible a growth which is ""intelligent, sustainable and favorable to inclusion"", by a better coordination of national and European policies.Adapting infrastructure and logistics that encourage the marketing of ""sustainable"", ""fair traded"" and ""green"" products as well as other special „green” products will facilitate the movement towards dematerialization and eco-efficiency among producers."

Jan 1, 2012

By Antti Roine

Sulfidic zinc concentrates are usually roasted in a fluidized bed furnace into sulfur-free oxide form. Metallic zinc is produced from this oxidic calcine using hydrometallurgical leaching, solution purification and electrowinning stages. The roasting step is necessary because zinc oxides are easier to dissolve using traditional leaching methods than zinc sulfides. The Kokkola Zinc smelter uses various types of zinc concentrates and secondary materials as feed mixture. This makes it difficult to find optimum process parameters for the roaster when the composition and particle size distribution of the feed mixture varies even on a daily basis. Certain conditions may even cause difficult accretion problems or increase the amount of calcine in the process off-gas line excessively. A thermochemical heat and material balance model was developed for process advisor, in order to estimate the effects of different process parameters (temperature, process air coefficient, concentrate feed, oxygen enrichment, water feed, etc.) on the heat balance, roasting temperature and calcine composition. This model was constructed using the heat balance module of HSC Chemistry 4.0 software. The prevailing chemical compounds in the concentrate and calcine were verified using mineralogical analyses and equilibrium calculations. The roasting process seems to operate near chemical equilibrium conditions, if the behavior of the main components is considered. This paper describes briefly the basic principles of the calculation model and outlines the results with several diagrams and discussion. The calculated results were in reasonable agreement with the recent process air oxygen enrichment and water feed test campaigns carried out at Kokkola in 1999.

Jan 1, 2000

Mineralogical and metallurgical scoping testwork were carried out to investigate the production of separate, marketable gold and platinum concentrates. The study utilized a flotation concentrate assaying approximately 5 wt% gold and 5 grams per tonne platinum. The gold-platinum mineralization was recovered from a placer deposit. Optical microscopy and scanning electron microscopy with energy dispersive x-ray analysis identified gold as zoned Au- Ag and Au-Ag-Cu alloys. Platinum primarily occurred as weakly zoned, variably magnetic Pt- Pd-Fe alloys. A combination of gravity and magnetic separations resulted in a gold concentrate grading 86.9 wt% Au (and 9.lwt% Ag) and a separate platinum concentrate grading 400 g/t Pt with recoveries of 94.5% and 96.7%, respectively. Magnetohydrostatic separation (MHS) using the Magstream 200 Separator indicated promising results.

Jan 1, 1994

By Pengcheng Li, Wei-Tong Du, Yu Wang, Gang Wen

Carbon dioxide could be utilized as a weak oxidant and a kind of coolant to oxidize elements, meanwhile, helping control the temperature during the converter vanadium extraction process. However, the optimum content of CO2 and the cooling effect of CO2 at low content have not been reported. In this study, experimental research based on the influence of different CO2 contents from 0% to 25% injected to the vanadium-containing hot metal was carried out, as well as contrast experiments of O2-N2 mixed blowing. The results indicated that the optimum content of CO2 was 15%. Under the optimum condition, the oxidation of [C] was the lowest and the oxidation rate of [V] was 96.9%, while the temperature was also lower than the O2-N2 mixed blowing. This paper provide a potential property for utilizing CO2 during the converter vanadium extraction process.

Jan 1, 2016

By Tom Lewis

This report discusses the evaluation of the ENVIRO-CLEAN PROCESS, a technology developed by Lewis Environmental Services, Inc. for the recovery of metals such as chromium, mercury, copper, cadmium, lead, and zinc from surface and groundwater streams. This new heavy metal removal process (patent-pending) utilizes granular activated carbon with a proprietary conditioning pretreatment to enhance heavy metal adsorption combined with electrolytic metal recovery to produce a saleable metallic product. The process generates no sludge or hazardous waste and the effluent meets EPA limits. A 50 gpm system was installed for recovering hexavalent chromium from a ground water stream at a site located in Fresno, California. The effluent from the activated carbon system was reinjected into the ground water table with the hexavalent chromium concentration < 10 ppb. The system simultaniously removed trichloroethylene (TCE) to concentrations levels < 0.5 ppb. The activated carbon is regenerated off-site and the chromium electrolytically recovered. The full scale system has treated over 5 million gallons of ground water since installation.

Jan 1, 1996

By Chen Dong, Yuanling Gao, Jilai Xue, Jun Zhu, Luxing Feng

"Porous Ni-Ti alloy has many applications in a wide range of engineering areas. The porous NiTi alloys were prepared from Ti and Ni powders in sintering process under argon atmosphere. The major chemical compositions of the sintered Ni-Ti body were Ni Ti, Nh Ti4O and Nh Ti, respectively, the internal pore structures were characterized by image analysis technique, which were dependent on various processing parameters such as sintering temperature, amount of poreforming agent, forming pressure, etc. The results show that the porous alloy samples had the characteristics of uniform pore and high open porosity; pore-forming agent and sintering temperature are important factors in porous; pressure affected the sintered products' pore, by affecting the combination of alloy powder with pore-forming agent.IntroductionPorous Ni-Ti alloy materials exhibit not only excellent shape-memory and superelasticity, high yield strength and ductility, good corrosion resistance and biocompatibility, but also have low density, low stiffness, and high energy absorption rate due to their porous structures [1]. In recent years, these porous Ni-Ti alloys have found applications in a wide range of engineering areas, such as bone implants [2-4], impedance-matching connectors [5], energy-absorbing structures [6,7], separators [8] and actuators [9], etc.Pore characteristics can play very important role in determining of the performance of porous NiTi alloys. For example, when the alloys are used to repair or replace hard tissue implant material, the pore shape and size not only determine their mechanical properties, but also have great effect on the fluid transmission of human body. The pore characteristics can also influence the stressstrain behavior of the porous Ni-Ti alloy and, thus, strongly affect their mechanical properties, superelasticity, and fracture mechanisms [10].In this study, the Ni-Ti alloys with high porosity were prepared in a powder sintering process under argon gas. The pore characteristics were investigated using SEM, XRD and image analysis techniques, especially in association with the content of pore-forming agent, sintering temperature and compacting pressure."

Jan 1, 2011

By Chao Li, Qian Li, Yong-bin Yang, Kai Li, Qiang Xie, Yuan-yuan Zhu, Dong-ye Li, Qi-bing Tan

"The permeability of sintering mix is a vital technological property in sintering process. However, it can only be measured by off-line method on samples picked from the production. In order to acquire the properties of sintering mix accurately, on-line measuring of permeability is urgently required. Based on the reflection characteristics of bed permeability on pipe flowing parameters, a new method is presented in this paper for on-line measuring of sintering mix permeability. The measurement can be performed by blowing gas flow in the bed with the measuring pipe. Measuring results are obtained by picking the data on flowing rate and pressure in the pipe. The function of flowing rate to pressure may be certain for samples with the same permeability. Thus, the permeability was determined by contrasting this function to the result of off-line measuring, and the relative coefficient or R2 value was more than 99%.IntroductionThe permeability of sintering mix is a vital technological property in sintering process, which directly determines production and quality of sinter, or even determines whether the sinter production is carried out smoothly [1,3].The permeability have more obvious influence on vertical sintering speed, which is mainly related to air quantity passing through material bed. Under certain inducing capacity and negative pressure, the vertical sintering speed mainly depends on the permeability of sintering mix. Low permeability may make burning through point of sintering move back, and the sinter mix cannot be burnt through. High permeability may make burning through point of sintering move forward, improving production efficiency by increasing the speed of sintering machine [4] Good permeability means a small resistance of fan ,reduction of negative pressure of sintering machine, and full contact between air and sulfide, which can strengthen physical-chemical reaction during sintering process and increase desulphurization rate. In gas well through material layer process, gas-solid desulfurization reaction and gas-solid-liquid heat exchange are completed and hot gas through the combustion zone supplies the sintering process with heat. Finally uniform sintering of the material layer in height and width direction is achieved [5] While high permeability index leads to weak sinter strength, fast sintering speed, short residence time of high temperature region and little liquid phase. Moreover, liquid phase in the fast cooling process is too late to fully crystallize but forming glass phase which is harmful to sinter strength as well. Bad permeability means a big fan resistance and increase of negative pressure of sintering machine, which make the air pass through material layer difficultly. When air and mix contact difficultly, removal of sulfide reduces so that desulfurization is incomplete. Meanwhile, low caking efficiency, slow sintering speed and easily burnt sinter , reduce sinter output. Therefore appropriate permeability of sintering mix is the premise of stable burning through point and satisfactory sinter output and quality."

Jan 1, 2013

By Ephraim Jeya Kumari

The demand for the titanium dioxide pigments and the shortage of higher-grade titaniferous ores with low radioactivity and zircon sands worldwide has encouraged the development of new techniques for the beneficiation of lesser grade titaniferous ores. The inferior quality ores are invariably richer in radio-active and lanthanide oxides, which severely interfere with the fluidized bed chlorination reaction (FBCR), in which ultra-high purity titanium tetrachloride is distilled off for pigment manufacture. However the present beneficiation techniques require high quality ilmenite ores and are not suitable for upgrading lower grade ilmenite ores which do posses trace metals in the form of lanthanides and actinides as Al-phosphates and zirconium silicates, respectively. The presence of mineral hosts, zircon sand and monazite in ilmenite and anatase also increase in chlorine gas consumption in the FBCR and contribute to a larger volume of hazardous waste production, which must be neutralised at a significant cost before being disposed off safely. In view of the problems described for lanthanide (Ce, Nd etc) and actinide (Th, U) trace impurities in titaniferous ores, an alternative route, which is flexible and more accommodating for processing difficult ores, is discussed. In the new process, which may be used for richer grades of ores too, the ore is roasted in air with sodium carbonate below 950°C to promote the formation of water-soluble sodium ferrite and insoluble sodium titanate phases. In this investigation, the high-temperature roasting process and the ensuing hydrometallurgical leaching steps have been analysed in the context of selective separation of lanthanide and actinide minerals from the main titaniferous mineral structures. Evidences for the selective separation are presented based on the chemical (XRD, XRF, AA) and microstructural analysis (SEM, EDX, EPMA) of roasted mass and the leached product. The efficiency of selective separation is also reported based on the chemicals analysis and the particle size of the materials derived after leaching. The paper highlights the various thermodynamic aspects of reaction equilibrium in the Fe-Ti-O-Na system, and the effect of Eh-pH diagram in the determination of pH required for the better control of the removal of iron and sodium. Two different types of Ti ores, namely ilmenite and anatase, their crystal structure and the phase transformation will also be explained on the basis of wet chemical analysis, XRF, XRD, EPMA and SEM-EDX studies. The method developed examines the technological feasibility of the selective separation process.

Jan 1, 2006

By Javier Antoñanzas, Susana Caballero, Eduardo Fernández, Jorge Aragón, Juan Carlos Múgica, Lourdes Yurramendi

Air Pollution Control (APC) residues treatment by plasma was studied as a technology for vitrification. During the project a protocol to verify the plasma technology was developed and afterwards applied to a specific case study: the APC residues from Municipal Solid Waste Incinerators (MSWI). Different operational conditions were tested and the vitrified products obtained were analyzed using standardized leaching tests in order to evaluate their new properties concerning safety storage. Two leaching tests were used for the evaluation, the European EN 12457-4 compliance test for leaching of granular waste materials and the French XP X 31-211 test for the determination of the leachability of a solid waste material initially massive or generated by a solidification process. Finally, conclusions about the environmental performances of the technology were obtained.

Jan 1, 2008

By Hideki Yamamoto

A new technology to convert fluoride gas (C2H2F4 ; R-134a) contained in the exhaust gases from semiconductor manufacturing plants and refrigerators directly into a harmless substance have been established, thus, presenting a new concept for the disposal of fluoride gases such as CFCs that are associated with the global warming. Experimental results verify that chemical reactions with metal compounds can take place at substantially lower temperatures of 700- 800K as compared with combustion. treatment temperatures of 1200-1500K. The reaction product is mainly metal fluoride, which chemically is a harmless material. Furthermore, this process is compact, easily controlled, safe and has low running costs. This paper deals with a new chemical reaction method for the harmless disposal of gases effecting the global warming.

Jan 1, 2003

By A. V. Tarasov

Investigations of thermodynamic properties of Cu-Ni and Cu-Ni-S systems and mattes have been conducted with the aid of a MC-1301 mass-spectrometer designed for studies-of processes of vapor formation of hardly volatile substances. The instrument comprised a combination of an evaporator of Knudsen chamber type with a mass-spectrometer for analysis of the vapor phase, In the process of studies of molten Cu-Ni-S systems and commercial-grade mattes within a temperature interval of 1400-1800 K the partial pressure of sulfur was measured by means of complete isothermal evaporation and the partial pressure of copper and nickel by comparison of ionic currents. The partial pressure values of the components above the molten Cu-Ni-S were used for calculation of activities of the respective components in the melt. The copper and nickel activity data obtained was used for assessing the amount of dissolved losses of these metals in autogenous smelting slags.

Jan 1, 2003

A new technology for the treatment of copper nickel-containing concentrate after high-grade matte flotation to blister copper with the production of liquid silicate slags in a vertical autogenous unit with upper oxygen blow has been considered. The copper and nickel behavior in the process of sulphide copper concentrate interaction with silicate melt containing oxide copper has been studied. The general mechanisms of such interaction are found.

Jan 1, 2003

By Fuqiang Zheng, Yufeng Guo, Pengfei Li, Guanzhou Qiu, Tao Jiang, Andrew Yakovlevich Travyanov

Low content of TiO2 and high impurities content of Ca and Mg are the shortcomings of domestic ilmenite. To meet the requirements of the material in the titania produced by chlorination process and titanium sponge industry, enrichment of ilmenite is necessary. In the process of enriching ilmenite, high temperature and reductive condition were beneficial to the formation of anosovite, but the high content of magnesium oxide which was solid soluble in anosovite baffled the following separation. So the effects of pre-oxidation and reductive conditions including reduction temperature, reduction time and hydrogen concentration on the phase composition and metallization rate were studied. The characteristics of reduction samples were analyzed by X-ray diffraction and optical microscope. Results have shown that the reduction product is mainly composed of Fe, Fe(Mg)TiO3 and TiO2 at 1123K, its metallization rate is about 65%,magnesium exists in Fe(Mg)TiO3.

Jan 1, 2015

By John Dasher

One of our War Plants processed Bolivian concentrates as low as 17% Sn by the Arnhem process (pressure leach with HCL) and sent the waste acid down a ditch to Galveston Bay where the chlorides, mostly iron, hydrolyzed. Oyster men, and Texas, demandedimpoundment until a disposal process could be developed. A recycle process found by lab work was recommended, piloted and a plant built. This involved cementation of As Sb, Cu, Bi and Ag on light moving scrap iron and of Sn & Pb on Al turnings (then not recyclable), evaporation and crystallization of hydrous FeCl2, roasting crystals in a muffle furnace and absorbing HCI for reuse. The residue from leaching the low grade concentrates was floated to remove undissolved sulfides, classified and passed over sand and slimes tables to get a smeltable concentrate, a discardable sand tail and a slimes tail worth treating After desliming at 2 micro meters cassiterite, oxide flotation gave good, lab results; but commercial equipment wasn&apos;t adequate then. Chloride volatilization, with or without smelting gave high recoveries of Sn as SnCl2, whose marketing was questionable. I have heard this was finally fluxed and smelted.

Jan 1, 1992