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By Niels Verbaan

NioCorp is developing the niobium/scandium/titanium Elk Creek carbonatite deposit. The probable reserve announced by the company in 2017 indicated significant niobium (0.79% Nb2O5), titanium (2.81% TiO2), and scandium (71 g/t), and is composed predominantly of calcite, dolomite, and ankerite. Niobium is mostly (80%) contained in pyrochlore with the balance in various Fe-Nb-Ti oxides, which also host most of the titanium. Scandium is primarily deported in dolomite, with lesser quantities in pyrochlore and biotite. The process flowsheet recovers separate niobium, titanium, and scandium products. Scandium is extracted from whole ore hydrochloric acid leach solutions using solvent extraction and is further refined through a re-leach and precipitation process. Scandium leach residues are treated in a sulphuric acid sulphation process to recover separate niobium and titanium precipitates as well as to solubilize the remaining scandium. Both hydrochloric acid and sulphuric acid reagents are recycled within the flowsheet. This paper will discuss key bench and pilot test results of the niobium extraction and recovery circuits and will present a conceptual flowsheet developed by the project team for NioCorp at SGS Minerals.

By Robert R. Beebe

On the night of August 1'9-20, 1995, seepage was seen at the toe of the Omai tailings dam in Guyana. The mill was immediately shut down, and within two hours the flow, then mostly water, was diverted into an inactive mining pit nearby. At about the same time a second more serious break occurred at a point where water and solids could flow directly into the Omai River. By the time Ii coffer dam could be completed in the early morning of August 24, some 4.2 million cubic meters of tailings water and solids had escaped from the dam, of which nearly2.9 million cubic meters had reached the Omai River. This paper outlines some initial Process considerations and operational decisions which might have contributed to the dam's failure, describes how the Government of Guyana and the operator, Omai Gold Mines Limited, cooperated in dealing with immediate problems and shows how the Government set about investigating the accident. In particular, the paper details the work of a Process Review Committee comprising Guyanese and foreign experts convened to assess the gold processing and effluent management systems at Omai, and to recommend actions where appropriate.

Jan 1, 1998

By A. R. G. Azevedo, G. C. Xavier

"This work has for objective to identify the soil of the neighborhood Codin located in a lacking area of the urban nucleus of the district of Campos dos Goytacazes - RJ, after the identification the best line was determined for the production of soil-cement blocks. In this area it happens habitational deficit and precarious constructions are also verified. The use of soil cement blocks is considered a cheaper constructive method than the conventional (ceramic block or of concrete), because one of the components of the raw material is abundant (the soil) and the constructions can be erect with certain easiness for collective effort regime. Samples of soil of this area were collected for they be characterized with relationship to the physical and chemical characteristics, with I aid of GPS the community's location it was registered. Identified the soil type, the work began the study of lines they to make possible your use in an economical and safe way. For that were made drained blocks in the format 19,5x10x5 cm, with lines containing the addition of 5% and 10% of cement in volume, and as parameter of quality the absorption of water and the resistance to the compression were measured, following the Norms of ABNT.IntroductionWe know that the use of the soil by the humanity come from the antiquity. And ifs confirmed by the archaeology places of the old civilizations of the word. The most remote constructions date from 10.000 years old in Jericoh, in the Jordan River Valley. This work became more intensive at 3.000 B.C. (Before Christ), by people who lived in those valleys with mood areas, a lot of clay and washed by the rivers.Almost all the sectors of engineering of soils choose the stability to use the local soil. Although, artificially treated, offers more economical advantages.The stability of a soil consist of endow it of the condition to resist the deformations and ruptures during the period that it is being used, because these characteristics are necessary in any construction.The application of the natural soil only is possible in places that they are of good quality and attend to the requirements of engineering to the type of previewed application. The granulemeter correction and the chemical stability include cases of inappropriate soils areas, turning the soil able to be used as construction material. Among the stability agents, usually added to the soil for stability ends, the cement is indicated."

Jan 1, 2013

By J. M. Floyd

Technology in use commercially and available for commercialisation for injection processing of base and precious metals in bath reactors is surveyed and compared. Differences between bath smelting and suspension smelting systems are highlighted in relation to important smelting criteria. The factors affecting the results achievable with various tuyere and lance injection bath smelting systems are discussed in relation to the various smelting, converting and refining operations involved in copper, nickel and precious metal processing steps. Process chemistry, process dynamics and heat and mass transfer rates are discussed for the different systems.

Jan 1, 1993

By Broggi Andrea

Condensates produced by SiO(g) and CO(g) have a crucial importance in silicon production. Condensation will follow the reactions 3 SiOðgÞ+COðgÞ→ 2 SiO2 + SiC and 2 SiO ðgÞ→Si+SiO2. Solid compounds generated during silicon production contain Si, SiO2 and SiC in different microstructures and amounts. In industrial systems, condensates limit the SiO(g) escape to the off-gas system. On the other hand, they can block the gas flowing from the high temperature zone, hence the necessity of studying an optimized condensation process. This review discusses SiO(g) condensation and its interaction with CO(g). The report gives an overview of the condensates found both at laboratory and at industrial scale. The two main compounds are the Si–SiO2 and the SiOx–SiC mixtures. The hypothesis on the mechanism of formation of SiC–SiOx condensates is presented through a wide selection of performed works. The advantages and disadvantages of the former experimental procedures are discussed.

By Norberto Benitez, Christian Ludwig, Simona Regenspurg, Fabian Mendez

"Navarro is the main garbage dump in the city of Cali (Colombia). Operated since the late 1960s it collects about 1.600 tons of waste daily. The environment surrounding Navarro is highly contaminated and the pollutants released by the dump threaten human health in the adjoining neighborhoods. The goal of our project is to identify major pollutants released from the dump and their distribution in the surrounding ecosystem. In a first phase of the sampling and analysis program landfill leachate was collected and screened for heavy metals and for the most common persistent organic pollutants. This allowed us to identify the most relevant compounds on which we focused in a more detailed second phase investigation. These compounds were quantified in the vicinity of the landfill (groundwater, surface water, drinking water and soil) to get information on their mobility and possible pathways into the human body.IntroductionThe usual technique of waste disposal in most developing countries is by landfilling on not -, or not well controlled sites, where people live close by or even on the waste itself. A typical example for this practice is Navarro, the main garbage dump in the city of Cali (Colombia). Operated since the late 1960s it now consists of about 23 million tons of household and industrial waste. The dump is located on a wetland in the riverbed of the Cauca River, the main drinking water source for Cali. Two ponds of unknown permeability located next to the landfill collect a fraction of the waste leachate. During the rainy season, the ponds frequently overflow and drain into the soil (alluvial, loamy sediments) of surrounding sugar cane fields. The environment of Navarro is assumed to be highly polluted and there is evidence that it affects the health of nearby inhabitants. Specifically, the incidence of respiratory diseases was higher among vulnerable individuals (<3 and >50 years old) living in a <3 km perimeter of Navarro as compared with a control group (Solano et al., 2006). Further, a clustering of extremely rare congenital malformations (sirenomelias and cyclops) was observed in a small area during a short time period (<6 months) (Filigrana et al., 2008)."

Jan 1, 2008

By T. K. Mukherjee, C. K. Gupta

"The importance of the processing of secondary resources such as solid industrial wastes and liquid effluents as well as byroducts for the recovery of the associated metal values hardly needs any elaboration. Such processing contributes in no small measure towards the augmentation of the availability and the supply position of resources. As an added benefit, it leads to a reduction in environmental pollution caused by the undesirable waste materials. As some typical examples of secondary resources in the Indian scenario, mention can be made of spent catalysts, metal/alloy scrap, ash, consumed batteries, flue dust, slag, sludge and slime, pickling solutions, spent acids, plating rinse solutions, spent etchants, waste water from synthetic fibre manufacture and from tanneries etc .. These wastes constitute a source of a variety of non ferrous metals. In the processing of secondary resources like these, the techniques of hydrometallurgy such as solvent extraction playa pivotal role.This paper outlines the efforts made to use solvent extraction to recover (1) base metals such as copper, zinc, nickel and cobalt from a number of secondary resources like cake, and sludge (2) refractory metals like molybdenum and vanadium from sulphidic byproducts and spent catalyst and (3) nuclear metal like uranium from phosphoric acid. In the case of base metals, process flowsheet involving the use of acidic extractants such as DEHPA and PC88A have been optimised. The problem of iron removal from the leach liquor, which influences the metal recovery process significantly, has drawn a special emphasis. In the case of refractory metals, basic extractants like Alarnine 336 has been pressed into service to produce kilogramme quantities of pure salts of molybdenum and vanadium. Finally, the paper gives a brief account of plant experience in recovering uranium from phosphoric acid, using a solvent system comosed of DEHPA and TOPO."

Jan 1, 1996

By Zhengde Pang, Xue-wei Lv, Guibao Qiu, Chenguang Bai, Zhiming Yan

The viscous behavior of molten slags has played an essential role in determining the performance and productivity of the ironmaking process. In this paper, the viscosity and free running temperature in CaO-SiO2-Al2O3-9 mass% MgO-TiO2 slag has been measured at different content of Al2O3 and Al2O3/SiO2 ratio. In addition, the slags viscous activation energy has also been calculated. The results show that the TiO2 as a basic oxide content from 1 to 5 mass% can reduce the viscosity and free running temperature, and moderate content of TiO2 in high alumina blast furnace slag remains effective for reducing viscous activation energy and free running temperature.

Mar 1, 2018

By Suguru Kohno, Yoshihiro Momose, Masakazu Honma, Tokirou Kamosawa

Copper metal surfaces have been examined by an extremely sensitive surface analysis technique called temperature programmed photoelectron emission (TPPE). The surfaces were ultrasonically cleaned and subsequently abraded by a screw in organic solvents and water. The TPPE apparatus is composed of a Geiger counter with Q gas (He+ iso-C4H10). The curve of photoelectron emission (PE) intensity vs. wavelength from 300 to 170 nm, termed PE spectrum, was repeatedly measured at different temperatures in the temperature- increase process from 25 to 350°C. The number of emitted electrons in a PE spectrum (PE total count) increased, reached a maximum at-250°C, and decreased with increasing temperature. With the surfaces cleaned alone in the liquids the maximum PE total count decreased in the order C3H70H > (CH3) 2CHOH > C2HpH > CHPH > H2O. With the mechanically abraded surfaces in the liquids the maximum PE total count changed as a function of the abrasion period and the maximum tended to appear at higher temperature with increasing abrasion period; the maximum value at 10-min abrasion decreased in the order H2O > CHpH > C2HPH > (CH3) 2CHOH > n-C3HpH. It was suggested that the TPPE behavior can be related to the acid-base interaction between the alcohols and the abraded metal surfaces and the presence of a contaminant over layer on the surface. From the XPS analysis of the 01 s spectra it was suggested that the chemical change of the adsorbed oxygen to oxide oxygen with temperature plays a substantial role in the appearance of the maximum PE total count.

Jan 1, 2000

By Alicia E. Ares

316 L Stainless Steel samples were solidified directionally under conditions which produced the columnar to equiaxed transition. The position of the transition was located in each sample and the distance from the bottom of the ingot was measured. During solidification the distribution of temperatures were measured by means of thermocouples located strategically. From the measured temperatures the following parameters were derived; the local temperature gradient, the cooling rate and the velocities of the liquid and solidus fronts. Comparing the location of the transition and the values of these parameters it was found that the temperature gradient reaches negative values of as low as -13.44 "C/cm, and velocities of the fronts of around 0.1 cm/s. Also, a supercooling of 5.81°C were measured which was associated with the supercooling for the nucleation and growth of the equiaxed grains ahead of the columnar front. In addition the primary and secondary dendritic spacing was measured in both regions. The spacing was compared with the predictions from available models. The results are presented and discussed in the frame of the results obtained for other alloys

Jan 1, 2002

By Krzyszof Borowiec

With the aim of determining the thermodynamic conditions for sulfation of impurity elements, in particular magnesium, in titaniferous slags the equilibrium gas composition for the sulfation reaction: MO + so2 + 1/2 02 = MS04 has been studied by an EMF technique with a solid zro2 + Cao electrolyte. Here M denotes the impurity elements: Mg, Ca and Mn, and the following _oxide systems have been studied: Ti02-MgO-Fe2 o 3 , Ti02-MnO-Mn2 o 3 , and Ti02 -CaO-Si02 , all in the . temperature range 700-1000ºc. Reproducible EMF values were obtained by adding small amounts of -Na2so4 to the oxide-sulfate mixture. From the observed results the Gibbs energy of formation of the phases Mg 2Ti04 , MgTi03 , MgTi 2o 5 , MnTi03 , CaTi03 , and CaTiSio5 , as well as the activity of MgTi05 in the solid solution with Fe2Ti05 have been calculated. The results show that, from a thermodynamic viewpoint, sulfation of these impurities in titaniferous stags i:s favorable- at around and below 800ºC.

Jan 1, 1985

By Zhiyun Li

Room temperature infrared reflection spectra of 2 n-type homo-epitaxial epifilms have been measured in the work. The effect of the refractive index on the determination of layer thickness using traditional calculation measurement is studied and some improvements have been added to the measurement to improve the accuracy and stability of the measured results. Results of the improved method have great agreement with the results from SEM and both variance and mean relative error decrease an order of magnitude.

Jan 1, 2010

By Florian Kongoli

"Lime ferrite" slag with limited silica content has proven to be a valuable choice in the modem processes of copper smelting and converting due to several advantages that this slag offers compared to classical silicate slags. Nevertheless the liquidus surface of this slag has been experimentally measured only at low oxygen potentials such as in equilibrium with iron or near it and in air. Although most of the smelting and converting processes that use this slag occur at intermediate oxygen potentials, the liquidus surface of this slag is not known at these conditions and the effect of oxygen potential and silica has not been correctly understood. This has brought some confusion in literature as well as in the industrial practice. In this work the liquidus surface of the calcium ferrite slags has been quantified by the means of a new thermophysicochemical model and a new type of liquidus surface diagrams which are very convenient for any industrial process that uses calcium ferrite slags. These diagrams can be easily used to select the lowest liquidus temperature of calcium ferrite slags at a minimum cost and can help design several fluxing strategies in copper smelting and converting processes. The effect of the oxygen potential and silica is also quantified and important industrially related conclusions are drawn.

Jan 1, 2003

By Grant E. Casley

Since 1970 Mount Isa fines Limited has made a significant increase in blister copper production from approximately 100,000 to 155,000 mt per annum and in fact 161,040 mt were produced in the calendar year 1974. Flowsheet developments including fluidised bed roasting and converter slag flotation are discussed, particularly their contributions to minimising major equipment changes in smelting and converting. The use of model- ling and simulation techniques for such an exercise is mentioned. The paper reports the alterations made to both equipment and operating techniques in the reverberatory furnace and converter sections to achieve the regular production of 250 mt of blister per converter day from a 41% Cu matte grade. The effects of flux composition on converting performance are highlighted. The air quality control programme is discussed in relation to its restriction of blister copper production.

Jan 1, 1976

By Igor Zh. Bunin

A model for developing electric discharges between sulfide mineral (pyrite) particles under high-voltage nanosecond pulses in a liquid medium (water) is considered. A possibility of electrical breakdowns of liquid gaps between particles under nanosecond pulses is shown. This probability and the energy released in discharge channels depend strongly on the sulfide conductivity.

Jan 1, 2010

By Thomas P. Battle

Titanium is the ninth most common element in the Earth&apos;s crust, yet only in this century has titanium come into use as an engineering material, particularly in aircraft structures, as the metal, and in pigments, as the dioxide. In this presentation, the metallurgical aspects of processing titanium-containing raw materials will be reviewed. Particular emphasis will be given to the ores and beneficiation techniques which lead to the production of titanium dioxide pigment, which accounts for over 90% of world titanium production.

Jan 1, 1993

By Tetsuya Uda

Our recent achievements of rare earth separation technique[1,2] and new process idea for rare earth magnet recycling[3] are reviewed, (1) Binary chloride mixtures of rare earths were separated by a new selective reduction-vacuum distillation process. According to our experimental results, apparent separation factors were 8.1 for the Pr-Nd chloride mixture and 570 for the Nd-Sm chloride mixture. These values are much higher than conventional solvent extraction methods. (2) A study of recycling process of magnet sludge was carried out. The rare earths in the neodymium magnet sludge were extracted by chlorination with FeCI2, An activated carbon was used as a de-oxidation reagent Metallic iron in the sludge was not chlorinated because the iron monochloride is not stable, The extracted rare earth chlorides were easily separated from Fe-alloy and the excess of FeCh by vacuum distillation, 96 % of neodymium and 94 % of dysprosium in the sludge were extraeted into chloride phase, By the vacuum distillation, a mixture of neodymium and dysprosium trichlorides of 99.2 % purity was recovered, On the other hand, the rare earth chlorides can be converted to the corresponding oxides by a pyrohydrolysis reaction accompanied by a formation of HCl gas, The HCI gas can chlorinate metallic iron to FeCh, Therefore, a new recycling process for rare earth magnet waste can be realized as a chlorine circulation type process. During the process, only carbon and water are consumed and there are no toxic pollutants, Moreover, the obtained rare earth oxide can be directly used as raw material in the conventional oxide electrolysis process,

Jan 1, 2003

By Aline Maria dos Santos Teixeira

Serpentinite is an ultra basic and metamorphic rock consisting mainly of magnesium, calcium and silicon oxides. The rock under study is a host rock of chromite mine located in Andorinha, BA. The objective of this paper is to evaluate the rock&apos;s physical and chemical characteristics to be used as an additional fertilizer of acid soils. After comminution, rock samples were submitted to chemical analysis, XRD, SEM-EDS and TGA. Afterwards, particle size distribution was determined. Result analysis confirms that our rock consists mainly of dolomite, calcite and diopside. According to the result obtained, it can be said that the serpentinite rock has promising applications in agriculture for the correction and additional fertilization of acid soils. However, it is necessary to study the characteristics of the rock such as its dangers and toxicity as well as evaluate them according to the legislation for corrective acidity.

Jan 1, 2010

By Satu Strömberg

Four different nickel concentrates were oxidized in a laboratory scale laminar flow furnace in simulated flash smelting conditions. The major nickel- and iron-bearing minerals in the con- centrates were pentlandite, violarite, gersdorffite, and pyrite and pyrrhotite, respectively. Thermal decomposition, ignition and oxidation behavior of nickel and iron sulfides were examined by using optical and scanning electron microscopy. General reactivity of the concentrates was monitored with sulfur removal which was most effective in violarite-based concentrate. Pentlandite-concentrates needed higher experimental temperatures for complete desulfurization and gersdorffite-based concentrate contained 5 - 10 % of the original sulfur even in the most oxidizing conditions studied (1 100°C, 50 vol-% 02). The reactivity of the iron minerals was found to depend on the other minerals present in the concentrate. In this paper, the observed re- action products and mineralogical changes are presented and preliminary conclusions of possible reaction mechanisms of nickel-bearing minerals are discussed.

Jan 1, 1997

This paper describes developments in ferro-nickel furnace technology, specifically improvements to cooling methods, furnace controls, and high voltage furnace operating regime. The evolution of these technologies is briefly presented, as context for describing the current state of the art that has enabled ferro-nickel furnace operation at over 75 MW and specific energy consumption of less than 400 kWh/t dry ore. Examples from existing operations are used to illustrate present best practices, and potential future trends are discussed: The paper begins with an overview of the fundamental aspects of pyrometallurgical treatment of lateritic ores that drive ferro-nickel furnace design. Furnace wall cooling methods are related to the requirements resulting from specific furnace process conditions, including slag and metal compositions, as well as arc and bath power. The benefits of high productivity and low specific energy consumption resulting from high voltage (shielded-arc) operating practice are discussed, along with the furnace controls and electrical power train that enable such operation even with captive power generation. This paper is an update of that which the authors prepared for the Infacon X ferro-alloys conference.

Jan 1, 2004