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By Tianzu Yang, Weifeng Liu, Lin Chen, Qingkai Xiao, DUCHAO ZHANG

To solve the problem of low leaching ratio of direct gold cyanide leaching from arsenical refractory gold concentrate, this paper proposed a matte smelting process for gold enrichment in low grade copper matte. The effects of copper content in the mixed material, ratio change in slag type, smelting temperature and reaction time on recovery rate of gold and copper were investigated. The experimental results indicated that the recovery rate of gold increased with the increase of copper content in the mixed materials, temperature and reaction time. It was also noted that the recovery rate of gold and copper were respectively 98.16% and 96.39% when the addition of copper content in the mixed material was 3%, slag type of CaO/SiO2 and FeO/SiO2 were 0.6 and 0.9 in 1250°C and the time of reaction was 40min. Most of the arsenic was oxidized into As2O3 existed in the dust. The results showed that the matte smelting method can achieve efficient recovery of gold from arsenical refractory gold concentrate.

Jan 1, 2016

By P. J. Uggowitzer, H. Kaufmann

"New Rheocasting is a novel route of semi-solid casting, in which the globular semi-solid precursor material is produced by controlled cooling of only slightly superheated melts in conventional steel crucibles. The resulting semi-solid slugs are placed into the sleeve of a vertical Squeeze Casting Machine and then filled into steel dies. Solidification occurs under hydraulic pressures up to 100 MPa Due to the reduced cost of precursor material, reduced investment cost and easier recycling, the New Rheocasting process offers cost reductions of up to 25% over conventional semi-solid casting · routes. The New Rheocast products are pore free, pressure tight, weldable and heat treatable castings.In the present work the New Rheocasting Process is introduced and the influence of heat treatment on mechanical properties of the New Rheocast alloy A356 is discussed.The alloy A356 is cast under ideal New Rheocasting conditions into a step die on an UBE HVSC 350 Squeeze Casting machine. As-east, TS and T6 heat treatment conditions with variations in solutionizing and aging time/temperature parameters are applied and the samples are tested by tensile testing. Alternatively, the same heat treatment conditions are applied to conventional Squeeze Casting parts and compared with New Rheocasting.Questions of potential cost savings due to modified heat treatment conditions are also addressed in this paper."

Jan 1, 2000

By David R. Jessey

An ore microscopic and geochemical study of the nickel-cobalt occurrence in the Southeast Missouri Mining District has revealed several significant relationships. Siegenite [(Ni,Co)3S4] is the dominant nickel-cobalt sulfide in the ores, however, several other members of the thiospi¬nel group (AB2S4) occur: carrollite (CuCo2S4), nickelean carrollite [(Co,Ni,Cu)3S4], fletcherite [Cu(Ni,Co)2S4] and polydymite (Ni 3S4). In addition, bravoite [(Ni,Fe)S2], vaesite (NiS2), millerite (NiS) and gersdorffite (NiAsS) are present. Thiospinel composition varies dramatically within the district. Paragenetic studies have shown that the stratigraphically lowest thiospinels are the most cobalt-copper-rich. A detailed ore microscopic study of the AMAX Lead Company Buick mine has also shown significant changes in mineralogical association, texture and grain size of the siegenite along the north-south strike of the major ore bodies. Siegenite commonly replaces and veins chalcopyrite and is subsequently replaced by sphalerite. Less commonly, siegenite and chalcopyrite are observed to form linear replacements along sphalerite grain boundaries. The grain size of the siegenite varies markedly, but in a predictable north-south pattern that is consistent with a genetic model formulated from geo-chemical data. The compositional as well as textural trends displayed by the thiospinel mineralization could be exploited to optimize recovery of any or all thiospinels of economic interest.

Jan 1, 1981

By C. P. Broadbent

The process metallurgy of many nickel laterite smelting operations is controlled largely by the physical chemistry of the slag system. Consequently, accurate phase diagram information and physicochemical property data are essential to interpret and predict the behaviour and optimisation of the overall process. The system (SiO2 - MgO - FeO) first described by Bowen et al. between 1914 and 1935 and the system (SiO2 - MgO - FeO - Fe2O3) determined by Muan and Osborne in 1956 are of particular relevance to the study of nickel laterite smelting slags as these systems form a reasonable approximation of many industrial slags. This paper will review the literature for these (and other relevant) phase systems. In addition data available from the ternary and (quasi)ternary phase diagrams will be compared with data obtained from industrial slags. The physico-chemical properties under consideration will include; melting and crystallisation behaviour (solidus and liquidus temperatures), viscosity - temperature relationships, heat flux considerations, electrical conductivity, surface and interfacial tension.

Jan 1, 1993

By V. M. Paretsky

Oxygen-flame converting of a solid ground matte containing heavy non-ferrous metals in a wide range of concentrations is one of the perspective trends meeting the demands of modern non-ferrous metallurgy. As. a result, of semicommercial tests on oxygen-flame smelting of nickel matte containing 13,5-17,5% Ni; 0,45-0,65% Co under continuous autogenous conditions a converter matte containing 68 8-75,0% Ni and 0,48-1-,0% Co and ferrite -calcium slag containing 1,4-8,4 Ni and 0,16-0,56 Co were pro¬duced. Nickel recovery in a converter-matte was 76,2%, copper - 58,'2% and cobalt recovery in. a slag was 90%. Slag cleaning in an electric furnace allowed to after-recover nickel and cobalt in an alloy to produce a dumpy slag containing 0,03% Ni and 0,02% Co. The development of modern' ecologically pure energy-saving autogenous technologies of the treatment of sulphide raw materials containing heavy non-ferrous metals makes certain demands of the perfection of a process of converting rich sulphide-metallic intermediate products obtained at autogenous smelting. These-demands were connected first of all with the fact that converting process stages because of process periodicity are more unfavourable from the point of ecology, power intensity and unit stability. Besides, during rich matte treatment the problems connected with heat shortage when using air blast and heat excess-when using top oxygen blast to treat luquid matte a-rise and when enriching air blast by oxygen up to 26% fast erosion of the brickwork of a tuyere zone takes place. The technology of Outokumpu and Kennecott companies-on solid- copper matte converting in a flash smelting furnace using air blast is not universal as its possibilities are limited by certain composition of mattes. Besides, flash smelting to produce highly basic or combined slags requires larger enrichment-of blast by oxygen or extra fuel feed. Naturally a flowsheet with continuous converting of matte of various composition up to white matte production is simple,

Jan 1, 1993

By Wang Zhi

High-Mg-content concentrates are usually treated in Jinchuan flash smelting Furnace. Because the viscosities of high-Mg-content slag is very high, the operation of flash smelting becomes very difficult. To solve this problem, the viscosities of the semi-synthesized FeO-MgO-Si02 slag of different compositions were measured. The results showed that when in the slag the weight percentage of MgO [m(Mgo)] is 6-10%, the ratio of the weight percentage of iron to that of Si02, m(Fe)/m(SiO2) is 1.1-1.4 and the temperatures are within 1473?1773K, the slag viscosities increased with the increase of m(Mgo) and m(Fe)/m(sio,). When m(Mgo)<6%, the smelting temperature should be controlled at I 300°C in order to to keep the smooth operation. When m(Mgo» 10%, the temperature should be kept above 1633K. When the content of MgO is higher, a lower viscosity slag ean be produced by decreasing the ratio of m(Fe)/m(sio,). The appropriate ratio of m(Fe)/m(sio,) for Jinchuan flash smelting furnace is about 1.2.

Jan 1, 2003

By Jiangtao Li, Zhongwei Zhao, Xingyu Chen, Xuheng Liu

In tungsten ion-exchange process, excessive sodium impurity enters into ammonium tungstate solution. However, the Na content of the final ammonium paratungstate (APT) product must be strictly controlled. Consequently, it is necessary to remove Na from the ammonium tungstate solution during processing in order to obtain the required purity of APT. In this study, porous Na specific absorbent, Na1+xAlxTi2−x(PO4)3, is used to remove Na from the ammonium tungstate solution. Through experiments, the effect of reagent concentration of Na1+xAlxTi2−x(PO4)3, reaction time, reaction temperature and Na concentration on the Na removal were investigated. The results showed that under optimal reaction conditions of reagent amount of NATP 1.0 times of theoretical amount, reaction temperature 25 °C and reaction time 15 min, the Na removal from commercial (NH4)2WO4 solution can reach 98%. Na1+xAlxTi2−x(PO4)3 has a good applicability to different Na+ concentrations. The obtained APT product reaches the national standard purity of zero level.

Jan 1, 2014

By Grégory Miette

The paper deals with a process that allows the recycling in a cupola of EAF dusts with 18 % Zn. It produces dusts with zinc grade higher than 50 - 55 % and commercial cast iron with less than 200 ppm Zn, 50 ppm Pb, 0.15 % S. The paper focuses mainly on lab tests made with the aim to develop an effective formulation of self reducing - melting pellets. With such a formulation, agglomerates develop a breaking load higher than 125 - 150 kg without any thermal treatment. Zinc and lead are volatilized in the cupola with yields higher than 95 % at 1200 OC, before any melting. Sulphur is transfemed into gas and slag. All these conditions allow to lower zinc, lead and sulphur grades below the cast iron specifications. Results of first bench scale tests performed at Fonderie Piret to validate the process will be presented.

Jan 1, 2002

By Ph. Cauwe

This paper presents the experience that NESA and MECHIM have gained about recovery of non ferrous and precious metals from complex sulfide materials. Processed materials are from natural deposits or metallurgical by-products or residues. Roasting of these materials is closely related to the pyro or hydrometallurgical processes used downstream of the roasting. Conditions of a first step of roasting the SELECTIVE ROASTING, are analyzed and explained. The roasted products so obtained are characterised by an extended elimination of volatile sulfides (AS, Bi, Sb, Sn, Pb, Hg, ?? ) and are readily available for the pyrometallurgical recovery of non ferrous and precious metals. After the SELECTIVE ROASTING, thanks to. the high porosity obtained in the "selective calcine", the SULFATE ROASTING is per-formed in excellent conditions. Hydrometallurgical tests performed for the final calcine show a high recovery of non ferrous and precious? metals and require only simple and well known processes. Many experimental and commercial data are given.

Jan 1, 1983

By Alberto Oalvez, Lucya Yunus, Pengfii Tan

"Laboratory flotation tests of slow cooled converter slag have showed that 92.5% copper recovery at the copper cut-off grade of 24 - 25 % can be achieved by using a 50:50 ratio of DSP330 and SIBX (sodium isobutyl xanthate) at the natural pH of 7 and with a grinding time of 18.5 minutes. 70ìéç is the P80 achieved at this grinding time. MIBC is the frother and the solid content of the flotation feed was 46%. In the plant trials, two types of collectors at two different feed particle sizes for both the normal and slow cooled slag were operated. The particle size was controlled by the feed rate. The P80 of 75 ìçé at a feed rate between 32 - 36 t/h were tested. The plant trials have demonstrated that the copper recovery in the milling and flotation process of the slow cooled slags was improved by 3%. IntroductionIt is proposed to float the slow cooled converter slag, in the auxiliary circuit of the copper concentrator at Mount Isa, by using the processing conditions identified from several laboratory flotation tests. Among these laboratory tests, one produced a copper recovery of 4 % higher than those achieved from a normal cooled slag with the same slag feed grade and the same copper content (24 - 26 %) in the concentrate. These test conditions were selected for further studies.Laboratory Test Work and Plant TrialsThere has been a lot of work conducted under laboratory and plant conditions [1]. However, the achieved results did not justify their total implementation in the Mount Isa Copper Concentrator. Initially, the lab trials were carried out with slag cooled 100% in air; then it was changed to combined cooling for 12 h with air and 2.5 days with water sprays. The reason for this change was the shortage of space when the slag was cooled 100% in air, as it takes several days to achieve safe temperatures for its removal. The San Manuel Copper Smelter has reported that their slag was left for air cooling in pits for 8 h and then was followed by water cooling for 2-3 days [2]"

Jan 1, 2012

By Yan Zeng

Lithium metal silicates (Li2MSiO4, M = Fe or Mn) composed of abundant and non-toxic elements are important cathode materials for Li-ion batteries (LIB). In contrast to solid-state or sol-gel methods, hydrothermal synthesis conducted in pressure reactors is a favorable processing route as it provides the potential for scalable production and is environmentally benign. However, the key is to control the precipitation reaction to obtain powders with desired properties to meet battery specifications. Through a systematic study, we have found that Li2MSiO4 with tunable size from 300 nm to 1.5 μm can be produced by adjusting precursor concentrations, temperature, and reaction time. Under optimum conditions, high purity Li2MSiO4 with minimum defects were successfully produced and examined as an LIB cathode. The use of complexing agents promoted the formation of unique hollow particles via the self-assembling of elongated crystals. A four-step formation mechanism is proposed based on extensive characterizations with XRD, HR-TEM, SEM, and Mössbauer spectroscopy.

By Katsunori Yamaguchi

Secondary materials, that contain relatively high concentrations of platinum group metals, (PGMs) are treated in copper smelting process. The PGMs lost in the slag is increasing with increasing quantities of scrap treated amount. To determine the portion of the PGMs chemically dissolved and that associated with the mechanically trapped matte in the slag will be a key factor to improve the recovery of those metals. An experimental study was carried out to determine the distribution of palladium between the FeOx–SiO2 slag and the liquid Cu2S–FeS matte at 1573 K and a fixed partial pressure of SO2 of 0.1 atm. It was found that the distribution ratios are around 10−3 for platinum and palladium. The distribution ratios show a tendency to increase when the grade of matte is increased above 60 mass% Cu. In addition, the solubility of platinum in FeOx–SiO2 slag equilibrated with a pure palladium and the Pd-Cu alloy was determined at 1573 K and the range of oxygen partial pressure from 10−9 to 10−7 atm. The solubility of palladium in the slag tends to increase with increasing oxygen partial pressure and activity of CuO0.5 in the slag.

By Seksak Asavavisithchai, Natthida Jareankieathbovorn, Areeya Srichaiyaperk

"Recycling of ADC12 alloy scraps for fabrication of open-cell aluminium foams has been conducted via pressure infiltration method of replication process. The scrap, up to 50 wt.%, was melted with pure aluminium billet, followed by infiltration in a replicated mold of polyethylene foam structure. Compared with the pure aluminium foam, the compressive strength and hardness are higher for the foams with recycled scraps. The increase in foam mechanical properties is due to the presence of Si hard phase in Al matrix. The strength and hardness of the foams also increase with increasing contents of the scraps.IntroductionRecently, open-cell metallic foams have been brought to considerable attention of many industries due to their superior properties; such as large surface area, high specific strength, thermal conductivity, high service temperature and excellent anti-microbial activity, that cannot be found in conventional materials [1, 2]. Typically, open-cell foams are used in functional applications for which a requirement of high strength materials is not demanded. Good examples of such applications include heat exchangers, bone-replacement implants, interconnects, catalyst supports, and sound insulators.Among all types of open-cell metallic foams, aluminium (Al) is the most widely used base metal, due to low material cost, low density, low melting temperature and good corrosion resistance. To improve mechanical properties of Al foam, modification of foam microstructure with addition of alloy elements or ceramic particles is commonly carried out [3, 4]. ADC12 alloy is a typical die-casting Al alloy with high content of silicon (Si) close to the eutectic point in Al-Si binary phase diagram. The alloy is extensively used in the casting industry, due to high wear and corrosion resistance, low coefficient of thermal expansion and excellent castability [5]. The mechanical properties of Al-Si alloy are strongly dependent of Si content."

Jan 1, 2012

By Fuqiang Zheng, Feng Chen, Wenting Duan, Yufeng Guo, Tao Jiang

High-quality titanium-rich material is of significance in the development of titanium industry as it is the main raw material to produce sponge titanium and titanium white using chloride process. Activation roasting of titanium slag with high Ca and Mg contents as adding H3PO4 followed by acid leaching was investigated to prepare titanium-rich material. The effects of H3PO4 dosage, roasting temperature and time, hydrochloric acid quantity, acid leaching temperature and time on TiO2 grade and removal of impurities were studied. The results show that after the finely ground titanium slag roasted with 8% H3PO4 at 1000 for 2h, most Mg impurities in anosovite solid solution structure were converted into simple acid–soluble compounds. The impurities such as Ca and Mg obviously decreased when the hydrochloric acid concentration was 20%, leaching at 100 °C for 2h, from which a titanium-rich material containing 82.56% TiO2 and 1.15% (CaO+MgO) was obtained.

Jan 1, 2016

By Guo Chen, Yifeng Shi, Xiaobiao Shang, Nanshang Shen, Bangqi Zhang, Jinhui Peng, Junruo Chen

"The energy is introduced directly into the volume of the honeycomb ceramic regenerator due to the complex interaction of microwaves with minerals in microwave gas heating system. A three-dimensional numerical model is developed to simulate the electromagnetic field by solving Maxwell's equations using finite-difference time-domain method. Computational result is presented for the microwave power absorption of the regenerator. Effects of the dielectric constant and the effective loss factor on the microwave power absorption in the regenerator are studied as well. Numerical results show that the heating pattern strongly depends on the dielectric property of the regenerator. The demonstration of the model of electromagnetic field distribution can be applied effectively and efficiently to optimize the fundamental parameters in the microwave heating processing.IntroductionIn recent years, microwave energy has been utilized in many fields, such as food processing, chemical engineering and mineral processing [l]. In contrast to conventional heating, where heat is transferred from a surface to the interior, microwave energy is introduced directly into the volume of minerals due to the complex interaction of the microwave with the mineral. Based on volumetric heating effects, microwave heating has several advantages such as pollution free, rapid heating technique, internal heating, high efficiency over conventional heating [ 1-4]."

Jan 1, 2013

By Geoffrey S. Plumlee

The Summitville gold mine, located in southwestern Colorado, received tremendous publicity in the 1980&apos;s and 1990&apos;s for leaks of cyanide solutions from its heap leach facility. As is typical with cyanide spills, real time, geochemically rigorous assessments of the environmental effects were not performed. Past United States Geological Survey (USGS) research used simple mixing experiments to model the influx of alkaline cyanide heap leach solutions from Summitville into a nearby stream, whose waters were highly acidic due to severe acid-rock drainage (ARD) from the mine. These experiments indicated WAD cyanide rapidly degraded due to formation of Fe-Cu-CN solids and lesser HCN volatilization. The alkaline heap leach solutions also precipitated hydrous iron-and aluminum, oxides and hydroxysulfates (iron and aluminum &apos;supplied by the acid. rock drainage (ARD]), which then sorbed copper and other heavy metals from the ARD. These results indicate that mixing of cyanide heap leach solutions with ARD may be a cost-effective remedial method at mine sites where treatment of both is required. New experiments are currently in progress to further refine a potential remedial process.

Jan 1, 1998

By Shilai Yuan, Huimin Lu, Liyuan Zhao, Zhijiang Gao

"A purification process was developed to removal impurity element boron from metallurgical grade silicon by electromagnetic induction slag melting. Vacuum melting furnace was used to purify boron in both Al2O3-MgO-CaO-SiO2 slag system and Al2O3-CaO-SiO2 slag system. The relationship between different slag chemistry and the removal of boron in silicon were studied using Back Propagation (BP) Neural Network model. The best slag chemistry for the removal of boron was predicted by Genetic Algorithm (GA) contributed by the use of Matlab. The results show that the mass fraction of Boron in silicon is reduced from 11.7496×10-6 to 2.3259×10-6 after slag melting in 28.96%Al2O3-3.43%MgO-36.24%CaO-31.37%SiO2 slag system. The relative error obtained with GA-BP Neural Network model was below 0.35%.IntroductionSolar energy, due to its low green house gas emissions, has been paid great attention. Accordingly, the demand for solar grade silicon (SoG-Si) has been growing rapidly. The quest for developing a low-cost method of producing SoG-Si has been moving forward in the last decade. Refining of metallurgical-grade silicon (MG-Si) attracts research interest due to its low material and energy costs, and more environmentally friendly technology in comparison to the traditional Simens process. As such, impurity elements in MG-Si must be removed to low levels for the photovoltaics (PV) cell to operate at optimum efficiency. Most impurities in metallurgical-grade silicon (MG-Si), especially metal elements, can be separated by directional solidification and the zone refining plasma-arc method [1, 2]. The main focus in refining MG-Si to SoG-Si is on the impurities which are the most difficult to remove. Boron has relatively high segregation coefficients (KB=0.8, concentration of Boron in solid silicon divided by its concentration in liquid silicon) [3] and higher vapor tension (the saturated vapor pressure of boron and silicon are 6.78×10-7 Pa and 0.4 Pa, respectively). The vacuum melting and directional solidification methods hence have no effects on boron removal.Slag refining involves melting MG-Si in the presence of a flux to produce a slag phase that can take up the impurity elements. The mechanism of slag refining is considered to include two main steps: the oxidation of boron and the absorption of boron oxide by slag materials. The oxidation of boron, described by the oxygen potential (PO2), resulting from the equilibrium Si and SiO2. The absorption of boron oxide, described as the slag basicity, is interpreted as expected to facilitate their extraction to alkali and alkali-earth oxides in the slag phase. Thus, effective removal may be obtained for a certain slag composition. Researchers [4-5] examined the effect of boron removal in CaO-SiO2 based ternary systems and showed that the addition of excess CaO can decrease the activity of SiO2. Researchers [6-8] studied the boron behaviors in CaO-SiO2-Al2O3, CaO-SiO2-Na2O, Al2O3-BaO-SiO2, CaO-SiO2-Li2O and Al2O3-CaO-MgO-SiO2 slag systems by adding boron in the silicon to a degree. Li2O, Na2O, MgO and BaO are thought to be associated with B2O3."

Jan 1, 2014

By Yang Xianwan, Zhu Xiaoyun, Guo Zhongcheng, Zheng Yanping, Zhai Dacheng

"Corrosion resistance of RE-Ni-W-P-SiC composite coating and 3 l6L stainless steel in corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions at different concentrations by means of immersion methods and anodic polarization curves obtained by DHZ-1 electrochemical synthetic tester and HDV-7 transistor constant potentiometer. Immersion experiment results show that corrosion rate of RE-Ni-W-P-SiC composite coating as-deposited in HCl solutions increases with the rise of HCl concentrations, on the contrary, the corrosion rate of the composite coating after heat treatment decreases with increasing the HCl concentrations the corrosion rates of the coatings as-deposited and after heat treatment in H2SO4 and H3PO4 solutions respectively decrease with the rise.of H2SO4 and H3PO4 concentrations the corrosion rate of the deposit as-deposited in FeC13 solutions decreases with increasing FeC13 concentrations, while the rate of the composite coating after heat treatment increases .with the rise of FeC13 concentrations.In addition, the corrosion rate of 3 l 6L stainless steel in the corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions at different concentrations increases with rising of concentrations. Furthermore, the corrosion rate of 316L stainless steel in the corrosion media of H2SO4, HCl, H3PO4 and FeC13 solutions respectively is much greater than that of the RE-Ni-W-P-SiC composite coating as-deposited and after heat treatment in the same corrosion media.1. IntroductionAll the materials and their products, when processed, stored and used, it is inevitable that the corrosion, wear, fatigue and crack occur owing to the actions of surroundings. Those early failure and abrasion, through all kinds of departments and profession that corrosion consumes one percent of tens of the steel products of the whole world; and two or four percent of the GDP is lost because of the corrosion."

Jan 1, 2000

By SM Rao

Nuclear Fuel Complex (NFC ) , Hyderabad (IN DIA ) , is engaged in the manufacture of nuclear fuel assemblies and zircaloy structural components required for the Indian nuclear power reactors. The production of zirconium oxide, sponge and zircaloy materials through chemical and hydro - metallurgical processes generates many effluents containing valuable zirconium and hafnium . This paper deals with the various processes such as multiple crystalization, phosphate precipitation, ion-exchanges amine solvent extraction etc, for the treatment of these effluents and subsequent recovery of valuable zirconium and hafnium .

Jan 1, 1992

By F. F. Lins

There is a large use of mercury in Brazil by the gold miners in the so called "garimpos" (non registered mining operations), where it is usual to recover the gold contained in the gravity concentrates by amalgamation, which is highly deleterious to environment if not conducted properly. Unfortunately, this is a common practice there. After presenting in brief the modus operandi generally practiced in the garimpos and the environmental problems, this work reviews some of the research conducted in CETEM according to two approaches: (i) replace amalgamation by other processes and (ii) develop technology to treat mercury-contaminated soils and effluents. Conventional processes like froth flotation, to recover gold from gravity concentrates, and centrifuges were considered. Also as alternatives to amalgamation, innovative process like the recovery of gold by coal-oil agglomerates and a technology that is currently under development in our laboratory, called gold-paraffin process, are described in brief, some results presented and their potential use assessed. To reclaim sites already polluted a technology was developed to float mercury selectively from contaminated soils. The potential use of centrifuges to pre-concentrate the mercury is also discussed. The scope for applying the last techniques is to concentrate the pollutants in a small volume of mass which would be suitable for recycling or isolation from the environment. A prospective technology to treat contaminated soils, or mercury concentrates, is the immobilization of mercury by adding inorganics. Concerning the ionic mercury which may be present in effluents, precipitation of the ions and flotation of the precipitates are being studied.

Jan 1, 1994