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By L. Filip

The roast-leach-electrowinning (RLE) process for zinc was modified to treat two typical complex concentrates containing zinc, lead, copper, gold and silver. Laboratory testwork results indicated that the optimum roasting temperature ranged from 700 to 800°C, in order to produce acceptable residual sulfur levels. The calcined concentrate was subjected to a three-stage leach sequence. The resulting leach solution was purified by hematitic precipitation and directed to the recovery of copper and zinc by solvent extraction and electrolysis. Alkaline smelting and subsequent electrolytic purification recovered the lead and precious metals from the leach residue. A flowsheet was developed based on the laboratory testwork results, and demonstrated in a large-scale pilot plant. The recoveries produced during the pilot plant operation ranged from 90 to 92% for zinc and copper, 85% for lead and 90% for gold and silver, respectively.

Jan 1, 1999

By Yousef Mohassab, Manoranjan Misra, Monalisa Panda, Eman Wahbah

This work studies the removal of arsenic (V), arsenate, and arsenic (III), arsenite, from aqueous solution using calcined Quintinite-3T. The two adsorbents Quintinite-3T was prepared, calcined at different temperatures, and characterized by XRD, BET, and SEM. The surface area of the calcined Quintinite-3T was 193.4 m2/g. The particles size ranged from 12 to 56 nm for the uncalcined Quintinite-3T and from 24 to 42 nm for the calcined Quintinite-3T. Kinetic analysis, adsorption isotherm, and factors affecting the adsorption were investigated. Calcined Quintinite- 3T retained As(v) and did not release it back to water even after an entire month.

Jan 1, 2016

By Marco Olper

After two years of extensive research a new and innovative modification to the CX-EW process has been exploited. This process, called CX-EWS, avoids completely all the critical aspects of the previous process which affected the cost of the energy, of the chemicals and of The maintenance of the insoluble anodes. All these benefits reflect a saving of about 30% of The operating costs compared to the present traditional production and allow for a total operating costs of less than 6.5 cts/lb. lead (net of raw material cost). With this new technology it is allowed for the first time the treatment in the same plant facilities of both primary lead sulphide concentrate and spent batteries. The paper describes the technical and economical aspect of the new process with a feasibility study for 150,000 t/y spent battery facility throughput.

Jan 1, 1995

By M. D. Stephens

A new, one-step process for extracting titanium from titaniferrous materials has been demonstrated. In the process, depleted uranium tetrafluoride (DUF 4), a solid, is mixed with ilmenite (FeTi03) and heated to 900°C. Titanium is extracted in the vapor phase as titanium tetrafluoride (TiF4) and the DUF4 is converted to uranium-iron oxide. The process has been found to selectively fluorinate the titanium in ilmenite and is capable of producing high purity TiF 4 with very low iron content. TiF 4 can be collected by condensation or through reaction with a fluoride salt such as NH4F, KF, or NaF. The TiF4 produced from the process can be used to make titanium metal, titanium oxide, or fluorotitanate compounds. Since the fluorination process is highly selective for titanium, it avoids many of the separations and waste issues common to other titanium extraction processes.

Jan 1, 2001

"Mixing phenomena in a bottom blown air-stirred one-seventh water model of CLU (Creusot-Loire Uddeholm) reactor was studie9-using three different configurations of straight circular nozzles fitted axially at the bottom of the vessel. The mixing time has been determined by pH measurements at various gas flow rates, bath heights and nozzle orientations in the presence and in the absence of a second phase.Experimental results reveal that the mixing time decreases with increasing gas flow rate. For a given gas flow rate the mixing time increases non-linearly with increasing bath height. Off-center configuration gives slightly lower mixing times as compared to center configuration. It is found that the contribution of buoyancy to the total stirring energy density is very small, but its contribution increases with increasing bath height. In the presence of an upper oil layer, the mixing time increases significantly for all configurations.IntroductionIn high temperature metallurgical melts mixing is carried out by injection of a gas either from top or bottom of the vessel in order to accelerate the rates of chemical reactions and to promote bath homogenization. When a gas is injected into a liquid through a submerged lance, porous plug or nozzle, the gas, rising as a two phase plume to the surface, imparts momentum to the surrounding liquid and causes gross circulation in the bath which promotes mixing."

Jan 1, 1997

By Liow Jong-Leng

A survey of the interactions of large gas bubbles formed from top and bottom injection of gases into melts was carried out. Spherical cap bubbles were found not to produce much splash when they break through the bath free surface except for that formed by plunging of the-spout at its edges. In contrast, the bursting of balloons produces cavities which give rise to liquid jets being ejected from the bath free surface. The position of the balloons relative to the bath free surface is an important parameter in the formation of the liquid jet. It is found that the interactions of multiple bubbles close to the free surface is important in determining the splash behaviour of gas injected systems.

Jan 1, 1996

By Daniel K. Kim

The charge for the copper refinery is a mixture of anodes produced at San Manuel from BHP source concentrate and copper purchased from external sources. Control of unwanted impurities in the tankhouse - is very important and beneficial. Currently available removal/recovery technologies were reviewed for the control of bismuth and antimony levels in the electrolyte. Recent studies have focused on solvent extraction (SX) technology and generated successful results for the removal and subsequent recovery of bismuth and antimony. The SX system employs the reagent, ACORGA SBX-50, in conjunction with a patented high chloride stripping system. The latter enables recycle of the eluant, avoiding the high costs associated with conventional systems, such as regeneration of resin. Concerns over potential transfer of organics and chloride ion to the electrolyte were readily addressed, solved and demonstrated using conventional, established technology. This paper describes the benefits of electrolyte purification, the flexibility afforded by the SX system, the operational practices necessary for maintaining adequate control of bismuth and antimony impurities in the electrorefining environment and possibilities for future development /exploitation of the Zeneca SX system at the San Manuel refinery.

Jan 1, 1998

By S. J. Buckler

Many chemical and metallurgical processes use submerged gas injection to increase contact area between gas and liquid phases in order to promote faster overall reaction or refining rates. The total interfacial area produced by gas injection through lances, nozzles or tuyeres is both an important design parameter for new vessels and a measurement for estimating the maximum processing capacity of existing equipment. Estimating total interfacial area from submerged injection into industrial pyrometallurgical vessels from existing knowledge is a problem with two aspects. The first difficulty is the difference in behaviour of cold (aqueous) and hot (molten metal) systems, implying that existing models and correlations of gas-liquid behaviour developed in low temperature systems are not necessarily appropriate for estimation of high temperature behaviour. The second difficulty is the issue of scale-up of correlations from laboratory to industrial sized vessels. The work presented in this paper is part of an ongoing experimental investigation, at the GK Williams CRC for Extractive Metallurgy, to quantify the total gas-liquid interfacial area available in pyrometallurgical vessels using chemical measurement methods. The effects of three operating variables, injected gas flow rate, nozzle diameter and nozzle submergence, on total interfacial area are quantified in a IOOL aqueous system - the first stage of a three stage process in examining the implications for scale-up of high temperature, medium-scale results are discussed. The results of work at high, injected gas flow rates (up to 500/min) show that the submerged Froude number is not sufficient for use as the sole variable in a predictive model of total interfacial area. Further work is being undertaken to identify other dimensionless variables that will better represent the gas-liquid characteristics in submerged injection that influence the formation of total interfacial area. The second and third stages of the experimental investigation involve measuring the total interfacial area in a large-scale (1000L) aqueous sodium sulphite and small-medium scale molten metal baths.

Jan 1, 2002

By Takaaki Shibata

The Tamano Refinery has developed two new processes for removing the impurities, arsenic, antimony, and bismuth from an electrolyte. The first process involves bleeding the surface electrolyte in the electro-refining cells. The copper concentration level in the outermost layer is lower than that in any of the other layers, while the impurity levels are almost the same in all layers. Bleeding the surface electrolyte increases the amount of impurities removed in the liberator by approximately 20%. The second process involves adsorbing antimony and bismuth from the electrolyte by means of chelating resin. As the electrolyte passes through the packed column of chelating resin, antimony and bismuth are selectively adsorbed. They are then desorbed by means of hydrochloric acid, and then recovered in the form of a highly concentrated antimony chloride solution by means of evaporation. This process almost doubles the capacity for removing antimony from an electrolyte.

Jan 1, 1987

By Kirsi M. Riihilahti

The oxidation characteristics of solid copper matte particles under simulated Kennecott-Outokumpu Flash Converting conditions are presented. This project is concerned with the determination of the effects of operating variables on the reaction of the particles. Experiments were carried out in a large laboratory-scale flash furnace with 72 wt-% Cu matte by varying initial particle size, temperature, oxygen partial pressure, oxygen-to-matte mass ratio and residence time. Chemical analysis was used to study the oxidation extent and copper volatilization. Particle fragmentation was examined. Fractional conversion and sulfur removal slightly decreased with initial particle size, while a higher oxygen-to-matte mass ratio mainly resulted in higher fractional conversion and more efficient sulfur removal. The fractional conversion values represented the overall extent of oxidation more closely than degree of sulfur removal.

Jan 1, 1997

By I. Gaballah

About forty percent of the SOx emissions are generated during the processing of metal sulfides of Cu, Pb, Zn, Ni, etc. Although new technologies for metal sulfide's smelting allow the production of H2S04 with a reasonable cost and decrease the emissions of sulfur oxides, the generated quantity of SOx is considered as a serious threat to environment. This paper suggests alternatives for low temperature processing of complex sulfide ores or concentrates 'CSO or CSC' under neutral, reducing and chlorinating atmospheres or their combination. At T > 400 "C, The neutral and reducing treatments allow the decomposition of pyrite and the partial recovery of sulfur as So and H2S. At 300 "C, the chlorinating treatment of CSC is fast, exothermic and allows the separation of FeC13 from the valuable elements' chlorides. It also generates SyCIx that can be either reduced by H2 or hydrolyzed in presence of sodium sulfide. The recovery rate of elemental sulfur with respect to the sulfur input exceeds 90 %.

Jan 1, 1999

By J. F. White

An experimental study was undertaken to evaluate the feasibility of a selective chloridizing roasting pre?treatment process for the elimination of impurities from zinc feed?stocks prior to recovering zinc by conventional unit operations. In this investigation, a number of chemistries that might serve as a basis for such a pre? treatment process were examined. A variety of chloridizing agents were admixed with EAF dust to promote the selective removal of lead and cadmium by the formation of volatile metal chlorides, he results of the experimentation firmly establish that selective chloridizing roasting is a technically feasible means of eliminating lead and cadmium from EAF dust. Excellent extraction efficiencies were accomplished with a number of chloride additives; as high as 98 percent lead extraction and 88 percent cadmium extraction were attained with minimal zinc losses, Continuous pilot?scale tests reinforced the trends established by laboratory?scale experimentation, Attempts of chlorine elimination using pyrohydrolysis were less successful. The extent of chlorine elimination was found to be highly dependent upon EAF dust sample type and treatment temperature.

Jan 1, 1996

By W. G. Davenport

This chapter demonstrates how our matrices can be used for controlling a flash furnace. Specifically, it shows how we can determine the adjustments in industrial oxygen, air, oil and flux input rates that will; (a) correctly alter product temperatures and compositions to newly targeted values (b), maintain set-point product temperatures and compositions with varying feed compositions and feed rates. It also discusses corrective actions that might be taken when furnace temperature and matte grade unexpectedly change.

Jan 1, 2001

By Timothy W. Ellis

This paper presents the basic theory of operation, physical chemistry and phase equilibria which allow the development of liquid-liquid extraction circuits based on metallic solvents. The incorporation of reduction and reduction/diffusion processes into the process 'scheme is discussed and a detailed description of ,several liquid-liquid extraction schemes are developed. A synopsis of experimental results obtained using this: method to separate rare earth and other metal based materials will be given.

Jan 1, 1996

By Brajendra Mishra

Molten Salt electrolytic processes offer unique opportunities to extract and refine metals where gaseous or metallothermic reduction, hydro metallurgical extraction and aqueous electrolytic methods are thermodynamically constrained. Production of aluminum and magnesium by molten salt electrolysis are well known commercial processes. Several other reactive metals, such as lanthanides and actinides, as well as beryllium and calcium, make use of molten salt processing for extraction and refining. This presentation describes the science of molten salt chemistry and electrochemistry for winning and refining of several metals. In addition, recovery of metals from waste process salts by molten salt reduction as well as oxidation have been discussed. Material issues in design of molten salt reactors have been included. Various applications have been presented through case studies. Experimental data have been included to justify the suitability as well as limitations of these specific processes.

Jan 1, 2003

By Z. Yang

The flotation behavior of the. green algae Chlorella vulgaris and a wild Chlamydomonas spp. was studied in the presence of Zn(II) using dodecylammonium chloride as collector. At about pH 6. both organisms readily float as amine concentration approaches lx10-3 kmol/m3. In addition, electrokinetic measurements were made on the organisms as a function of pH in both the presence and absence of Zn(II). It was found that the Zn(II) has a considerably greater effect on the zeta potential of C. vulgaris than on Chlamydomonas. Zn(II) adsorption studies also indicated that C. vulgaris is able to accumulate more Zn from solution than the Chlamydomonas.

Jan 1, 1991

By Yotamu Hara, Animesh Jha

"High Curie temperature and large magnetic anisotropy make cobalt an important magnetic material for power engineering applications of magnets operating above ambient. It is also an essential constituent of modem lithium - cobalt oxide batteries, without which modem electronic gadgets will be functionless. Both these applications of cobalt save energy and reduce C02 emission. Ironically, however the production of cobalt from copper and nickel smelting in the world remains one of the least energy efficient process. The paper analyzes the energy balance, material and process chemistry of overall cobalt recovery and the waste generated, which entail the process limitations. We discuss a novel approach for the reduction of sulphide minerals with CaS04, permitting better separation of metals from slag and generating higher concentrations of S02. Such an approach may seem to be an alternative energy efficient option for processing and further purification of cobalt in metallic form. The results are discussed in the context of process thermodynamics and reaction kinetics for Coalloy production.IntroductionCopper sulphides bearing minerals are predominantly associated with iron and cobalt sulphides minerals. Carrollite (CuC02S4) is a mineral that has both copper and cobalt sulphides [1,2], which may also contain FeS, by substituting either Cu2+ or Co2+ ions in mineral lattice. On smelting copper - cobalt - iron sulphide concentrates, some parts of the cobalt often partition to matte at preferentially low oxygen potential by forming eventually an alloy phase with copper, however a significant fraction is often lost into an oxide slag rich in iron and silica. The slag heaps accumulated in the Copperbelt region in Zambia from last 60 years of mineral processing and metal extraction is reported to be 0.3 to 2.6 wt% of cobalt element, which is high [3]. Cobalt is also available in smaller concentrations in the copper smelting and converter slag, as reported in the investigations on the recycling of such slag materials using leaching with ammonium salt [4], iron chloride [5], and sulphuric acid [6], and solvent extraction [7].The recovery of cobalt from slag, irrespective of the techniques researched so far, does not seem energy efficient because the molten slag at 1300°C is quenched by losing thermal and chemical energy. The quenched slag is again reheated to above room temperature for leaching and above liquidus for carbothermic reduction of residual cobalt oxide. For example, in Mintek DC arc smelting [3], 80% of cobalt and 95% nickel are recovered by expending 600 kW per tonne. Assuming that the mineral carrollite is the starting phase, the univariant calculations for the Co-Ca-Si-S-0, Fe-Ca-Si-S-0, and Co-C-Si-S-0 systems are shown in Figure la, lb, and le, respectively at 1573 K."

Jan 1, 2012

By Yosry Attia

Recent emphasis on environmental effects and costs of conventional mining processing, plus success in accelerating bacterial action, suggest that biotechnology be explored for gold ore processing. In our paper, the past experience with organisms in processing gold is reviewed. The use of microorganisms for liberation of gold from sulfide ores as a substitute for fine grinding is discussed. The possibility of accumulation of gold from solutions, such as cyanide solutions, is explored as a potential replacement for such processes, such as carbon-in-pulp or ion exchange. The improvement in engineering technology and kinetics needed to scale-up from laboratory experiments to production scale are outlined.

Jan 1, 1985

By Tailoka F.

Various metallurgical residues from iron and steel making processes have been treated by chlorination in excess air with hydrogen chloride gas generated from the combustion of scrap polyvinyl chloride (PVC). The residues include dust from both the electric arc and blast &maces, hydrocyclone overflow, zinc - lead blast furnace slags and dust rich in zinc and copper from copper refining. Chlorination is achieved either directly by mixing the residues with scrap PVC or indirectly in a two furnace system. In the latter, scrap PVC is combusted between 523 and 573 K in a horizontal furnace and the resulting gases are then reacted with metallurgical residues in a vertical furnace at 1166 to 1329 K. Gas chromatography, thermogravimetric measurements, XRD and AAS have been utilised to study the reactions. The recovery of non ferrous metals is as high as 80 to 90 % and only a negligible amount of iron is carried over. The optimum temperature for combustion is between 518 and 573 K. Above 600 K, the evolution of HCI is so fast that sufficient chlorination is not achieved. Analysis showed that no dioxins were present in the gases, the residues or the chlorides.

Jan 1, 1997

By Bruce H. Baker

Studies of used or unused refractory materials are excellent examples of applied mineralogy in industry. Refractory materials are mineral substances containing ceramic or chemical bonding systems. Knowledge of the mineral composition, bonding, and textural relationships often explains the resulting physical property values of a refractory and contributes to the interpretation of refractory wear mechanisms occurring in steel plant service.

Jan 1, 1982