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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 Shengli Wu, Mingyin Kou, Laixin Wang, Zhe Wang, Xinliang Liu

The sticking behavior of iron ores in the shaft furnace is one of the most important problems in the COREX melting progress, which directly influence the smooth operation and productivity of shaft furnace. Therefore, it is of great importance to study the sticking behavior of pellets in COREX shaft furnace. The results showed that porous metallic iron produced at the interface of pellets samples was the main reason for the sticking of pellets in the COREX shaft furnace. The SI (sticking index) and metallization rate increased with the reduction temperature and gas flow, and decreased with melting rate. However, the SI of pellets in the COREX shaft furnace could be decreased by the proper match of melting rate and reduction temperature, reduction temperature and gas flow, while the metallization rate of pellets were kept at a certain level. Furthermore, the matching of melting rate and reduction temperature was more effective than the matching of reduction temperature and gas flow.

Jan 1, 2016

By Antoine Allanore, Luis A. Ortiz, Donald R. Sadoway

"The steelmaking industry has drastically reduced its energy consumption in the last fifty years, and today’s technologies are considered to operate at their optimal efficiency with respect to energy needs. To cope with new constraints related to greenhouse gas (GHG) emissions, a change of paradigm is necessary. One of the promising technologies that could be deployed to help reach CO2 mitigation targets relies on the intensive use of electricity: molten oxide electrolysis (MOE). This paper presents the key process parameters that need to be tuned to address the practical needs for both high productivity in a steelmaking reactor and for an energy efficient process. Herein we show that contrary to common perception, the electrolysis process for ironmaking requires less energy than today’s chemical reduction route. Furthermore, we prove that most of the energy that must be provided to operate the electrolytic iron production cell is thermal energy which is readily generated by joule heating during electrolysis due to large currents being passed through the electrolyte. The energy consumption of the electrolysis cell is therefore shown to be highly dependent on the cell configuration and the chemistry of the electrolyte. As a consequence, the CO2-impact of the technology strongly depends on both the power production mode and the technological choices for design of the process, including cell configuration. Surprisingly enough, even when the electricity generation is not carbon-free, MOE still appears to be viable from the perspective of reducing GHG emissions providing sound reactor design considerations are made.IntroductionIn the context of greenhouse gas (GHG) emissions mitigation, the steelmaking industry is considering several techniques that could sustain the efforts and progress achieved by this sector in the last decades [1]. A recent report [2] on potential routes for low-CO2 steelmaking highlighted for all techniques both the strong dependency of CO2 emissions on electric power production mode and the need for a decrease in energy consumption per tonne of steel. Incited to innovate with respect to this last criterion, the steel industry considers electrolysis to be a promising technological solution, and in particular the molten oxide electrolysis (MOE) process. This process conducts electrolysis in a mixture of oxides that dissolve the iron oxide feed, which by the action of electric current is decomposed into liquid iron and oxygen gas. The opportunity for reduction in energy consumption during steelmaking by MOE is commonly attributed to the “direct” pathway from iron oxide to liquid metal offered by the use of a molten oxide melt and operation at a temperature above the melting point of iron, ideally 1600°C, to provide enough superheat for tapping the molten iron product:"

Jan 1, 2011

By D. M. Hausen

It has been demonstrated that microscopic techniques can be applied in a practical manner to the study of spodumene liberation in the processing of pegmatitic ores at the Kings Mountain spodumene plant, Kings Mountain, North Carolina. Spodumene and associated non-opaque gangue minerals are identified and quantified by microscopic point-counting of polished thin sections of heads, concentrates, middlings and tails fractions. Specially prepared polished thin sections? provide uniform thickness of particles for measurement of diagnostic optical properties and the alternate use of incident and transmitted light in distinguishing the various gangue and ore minerals. Spodumene is commonly associated and interlocked with quartz, albite, microcline and muscovite. Concentrate grade depends on the degree of spodumene liberation, which in turn depends on the crystal size and textural association of interlocked minerals. The liberation of spodumene can be measured as a function of screen size by means of microscopic point-count data. Microscopic data also provide useful metallurgical information about the nature of diluent minerals in spodumene concentrates, and the form of lithia losses in the tails. Lithium assays correlate closely with microscopic spodumene analyses in various flotation products from Foote Mineral's Kings Mountain plant, and confirm the applicability of quantitative optical microscopy to the study of liberation and recovery of spodumene from pegmatitic ores. A better understanding of recovery-grade relationships was developed as a result of quantitative microscopy studies.

Jan 1, 1981

By Chikabumi Yamauchi, Mitsuru Tanahashi, Jutaro Miura, Takaharu Iwadachi, Toshiharu Fujisawa

"Tue oxidation behavior of molten Cu-Be alloys was investigated by exposing· the molten Cu-Be alloys to various Ar-O2 atmospheres to control the oxygen partial pressure, PO2 = 10 ~105 Pa at 1423 K. The following results were obtained:• The oxygen · partial pressure in gas phase affects the morphology of the oxide formed on the surface of the alloy and · the oxidation rate of beryllium.• At lower oxygen partial pressure, a molten Cu-Be alloy is covered with a homogeneous and compact internal layer of BeO. Thus, the beryllium oxidation rate can be minimized.• By adding a small amount of calcium or zirconium into the molten Cu-0.5 mass% Be alloy, a protective BeO layer is formed even at higher oxygen partial pressure. Thus, the beryllium oxidation rate can be reduced.IntroductionCopper-beryllium (Cu-Be) alloys are well recognized for their unique properties, such as high electrical conductivity, high strength, high fatigue strength, excellent properties at elevated temperatures, good formability and good corrosion resistance. .This extraordinary collection of properties are the reasons why Cu-Be alloys are expected to be ""Key-materials"", which are necessary to further advance science and technology and to be applied in.various fields such as electronic devices, machine parts, repeater housings of undersea optical fiber communication cables, etc.However, a large amount of beryllium is oxidized to BeO in melting stage of the current Cu-Be alloy production process, because beryllium is a highly reactive element. This is one of the ·main factors that negatively affect the production yield and th_e product quality."

Jan 1, 2000

By Giuseppe Bonifazi

Minerographic and petrochemical research was carried out on crude ore samples from the complex polymetallic Zn-Cu-Pb sulfide ores of , Sotiel in Huelva province west of Seville, Spain. A computerized image analysis system was used to define the structural and textural characteristics of the ore to obtain information on the degree of liberation of the different minerals (i.e. pyrite, sphalerite, galena, chalcopyrite). Techniques of digital multispectral image processing of reflected light microscopy images were used. Particular structures were identified by means of mineral associations and numerically quantified to obtain useful information for designing beneficiation processes.

Jan 1, 1991

By Zhenjun Tan, Lei Zhang, Jigang Li, Yifang Zheng, Jilai Xue

"Water electrolysis in 0.4 mol/L NaOH solution for hydrogen generation was carried out with ultrasound introduced through the anode. It was found that the cell voltage reduced by 150-300 mV in the current range of 20 mA to 40 mA with ultrasound frequency at 25.3 kHz. The cell operation became unstable when the cell current was larger than 75 mA with ultrasound. This reduction in cell voltage was due to removal of the gas bubbles on the electrode surface, which can be directly observed in the see-through cell of water electrolysis. Ultrasound with frequency of 33.3 Hz was also tried, but no better effect was obtained. The results suggest that ultrasound assisted water electrolysis can have potential in energy savings for hydrogen production.IntroductionIn electrolytic process, the electrode that the bubbles generated on its surface usually covered a thin gas film, which can be caused an additional voltage about 0.15-0.25V[l,2], especially in aluminum electrolysis. To solve the problem, loading the ultrasound removes the gas bubbles from the electrodes, this subject had been researched in recent years. From 1995 Jilai Xue et al[3,4,5]. applied the ultrasound in aluminum electrolysis in lab. The results from Sheng-De Li et al.[6] reveals that can decrease the cell voltage and have influences about the hydrogen and oxygen's output ratio. Although there are many paper about the applying of ultrasound such as in electrolysis[5,6], deposition[7,8], plating[9,10], oxidation of salts substance on the surface of electrodes[l 1] and so on, the effect of different frequencies ultrasound hadn't been investigated deeply.We focus on the anode voltage by different frequencies ultrasound and the bubble behaviors in this paper. The environment of this experiment is in alkaline solution. Through this exploration it can offer a basis for the applying of ultrasound in electrolysis."

Jan 1, 2011

By Bin Xu, Qian Li, Yong-bin Yang, Tao Jiang, Jian-jun Hu

It could significantly increase the leaching rate of refractory gold concentrate containing sulfur and arsenic by roasting pretreatment with adding certain amount of sodium sulfate, and the mechanism of that was systematically researched with DSC, XRD and SEM in this paper. Results indicated that the mechanism of Na2SO4 on double refractory gold concentrate at roasting pretreatment can be summed up in the following three aspects：Firstly, Na2SO4 can react with SO2 and SO3 which is produced by the oxidation of sulfides and generate Na2S2O7(l), which plays buffer effect on sulfides exothermic oxidation, avoiding the secondary-encapsulated of gold. Secondly, the liquid phase of Na2S2O7 can cover mineral particles' surface that possesses a sintering effect, it leads to internal cracks of the particles. Finally, mineral particles will gather with sodium sulfate particles as the center that can improve the permeability of the layer.

Jan 1, 2015

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

In order to produce good quality ammonium paratungstate, Sn needs be removed efficiently from the tungstate processing solution. The nascent hydrous ferric oxide has excellent adsorption ability and is often used as an adsorbent to remove metal ions from aqueous solution. In this paper, nascent hydrous ferric oxide is used to remove Sn from tungstate solution. Through experimental, the effects of pH value, reagent amount of adsorbent, reaction temperature and reaction time on the Sn removal are investigated. The study shows that 98% of Sn can be removed effectively from sodium tungstate solution and only 2% of W is lost during process under the conditions of pH 9~12, reagent amount of Fe addition 40 times Sn amount, reaction time 30min and room temperature. As the Fe addition reaches 90 times of Sn concentration in the ammonium tungstate solution, 99% of Sn is removed and APT with zero level purity national standard is obtained.

Jan 1, 2014

By Bemd. E. Langner

At Norddeutsche AfFmerie the CollaMat is an important instrument for controlling the activity of glue in copper electrolyte. Thanks to on-line measuring of the glue activity appropriate action can to taken in the event of sudden changes, such as an intemption in the glue supply, as well as long-term trends, such as continuously decreasing glue activity over days or weeks. Laboratory tests on the dependence of glue degradation on temperature have shown that relatively small increases in temperature of only 3OC cause the half change value of the glue degradation to reduce by 25 %. It is a similar picture with the sulphuric acid concentration in electrolyte. An increase in the acid concentration from 160 g/l to 200 g/l can - depending on the temperature - likewise result in a decrease in the half change value of up to 25 %.

Jan 1, 1995

By Emil B. Milosavljevic, Ljiljana Solujic

Cyanide is exceptionally reactive, and in typical gold/silver processing liquors, cyanide may be transformed into various species and forms depending on the mineralogy of the ore and chemical make-up of the process water. The exact speciation and relative concentrations depend on the Eh and pH values, as well as the free CN concentration in the system. Very good cyanide balances can be achieved by the judicious selection of the analytical techniques used. The choices an analyst has to make (which analytical methods to use and which ones to avoid) in order to gain better understanding of cyanide speciation and balances in a particular system under investigation will be discussed. Examples of cyanide balances obtained for the laboratory scale tests (agitated leach and column tests) will be presented and discussed.

Jan 1, 1999

By T. Mutoh

Tellurium in raw slime has recently been recovered as copper telluride in Onahama Smelter & Refinery. The slime is decopperized with sulfuric acid solution in conventional leaching tanks. The pregnant leach solution containing 45 g/l of copper and 1 g/l of tellurium is introduced to a copper telluride recovering reactor. The tail solution from the reactor containing less than 20 mg/l of tellurium is recycled directly to circulation tanks of copper electrolysis. The impurities of the product copper telluride is kept below 1% without any purification.

Jan 1, 1990

By Jr. Foot

The Bureau of Mines, U.S. Department of the Interior, investigated flotation methods for recovering fluorite and byproduct beryllium from the Fish Creek deposit of Nevada. The preferred method includes (l) fluorite rougher and cleaner flotation, (2) de sliming at 20 micrometers, (3) muscovite flotation, (4) silicate flotation, (5) hypochlorite wash of silicate concentrate, and (6) beryllium rougher and cleaner flotation from the silicate concentrate, Laboratory results showed that over 94 pct of. the fluorite was recovered in a concentrate containing 96 pct CaFz. Beryllium flotation produced .concentrates .containing in excess of 5 pct BeO with recoveries over 70 pct. A 1.00-lb/h continuous flotation unit was constructed to demonstrate this procedure,

Jan 1, 1985

By Sutham Niyomwas

Biomorphic Cellular TiCIC ceramics were produced by vacuum-infiltrating carbon preforms with Ti02 sol and subsequent synthesis by the carbothermal reduction process. The carbon preforms used in the study were obtained by pyrolysis of parawood and neem wood. The effect of infiltration time on the composition and microstructure of the biomorphic TiCIC ceramic was analyzed by X-ray diffractometry and scanning electron microscopy. The biomorphic structure of the TiCIC ceramic is consistent with that of the biotemplate natural parawood and neem wood.

Jan 1, 2008

By Adolfo Pillihuaman Zambrano

Fe-Cr-C production is a very high electrical energy consuming process. Decrease up to 10% of this electrical energy is expected when self-reducing agglomerates are used. This research aims to understand how the synergetic effects are when stronger reductant, like Fe-Si, is substituted for coke in self reducing pellets. Brazilian chromites containing 41.2%Cr2O3 were mixed with petroleum coke and agglomerated with cement as the binder. Small amounts of 1%, 2% and 4% of Fe-75%Si were substituted for the equivalent petroleum coke, and pure silica plus hydrated lime were added for adjusting the slag composition. The mixture was pelletized, dried and submitted at 1773K up to complete the reactions. The results showed that the reduction reactions were 1.4 and 2 times faster with 1% and 2%Fe-Si addition, respectively, than with no addition. The microscopic analysis showed that it was formed a liquid phase, but the pellet did not collapse what indicates that the coalescence of the metallic phase depends on the dissolution of the pre-reduced particles of the chromites into slag.

Jan 1, 2008

By David G. Dixon

A mathematical model is derived in dimensionless form which simulates the effluent concentration response of reagents from spent heaps under both fresh and recycled water rinsing. The model is based on dispersion from isochoric pathways distributed in length and cross-section, oriented normal to convection channels in ideal plug flow. The effects of heap height, rinsate flow, and initial reagent concentration are examined. It is shown that the rinsing cycle undergoes a distinct shift between fast and slow rinsing at a certain time depending on the amount of stagnant solution in the heap, and the distribution of dispersion pathways. Results of preliminary column rinsing tests on both agglomerated and unagglomerated ores are presented which partially validate the model.

Jan 1, 1994

By M. I. Novgorodova

An overview of the systems Au-Ag and Au-Cu is given. The nature and levels of concentration of various elements occurring with native gold is reviewed. The examples cited are mainly from the USSR. The lack of homogeneity within naturally occurring Au-Ag solid solutions is examined.

Jan 1, 1991

By H. J. Garcia

Biodegradation of cyanide by microorganisms isolated from solids previously exposed to cyanide has been investigated. Initial sodium cyanide concentration was 300 ppm at pH 10.5. The kinetics of biodegradation were found to be first order with respect to cyanide concentration, and the overall reaction rate constant is k = 0.102 day-1. The activation energy and the frequency factor were determined to be { A }Ea = 5.45 Kcal/mol and A = 1.28 x 10-2 sec-1, respectively. Based on these values, thermodynamic properties of an intermediate activated complex were assessed. All tests resulted in cyanide concentrations less than 0.1 ppm in about 35 days at 250C, whereas at 350C the time of biodegradation to reach this cyanide level was 30 days. Kinetic data were also established to relate biodegradation to amount of inoculum. The maximum theoretically-attainable rate, Vm , and the optimum amount of inoculum, K , were determined to be 4.8 x 10-4 M NaCN/day and 7.5 % of amount of inoculum. With respect to the mechanism of biodegradation, cyanide was shown to decompose to carbonate, bicarbonate and ammonia. Titrimetric analyses revealed concentrations of 5.6 x 10-3, 4.8 x 10-3 M, and 70.2 ppm for carbonate, bicarbonate and ammonia, respectively. The average cell population was determined to be 3.75 x 108 cells/mL.

Jan 1, 1994

By Joseph Hamuyuni, Pekka Taskinen

We present experimental results for the liquidus in the system Cu2O - CaO -Al2O3 at 1250 oC. In this study, we quantified the liquidus by the equilibration/quench/analysis technique, with Cu2O, Al2O3, and CaO as primary materials exclusively. Experiments were conducted in air at an at oxygen pressure (p) = 21.3 kPa). Equilibrated specimens were quenched in brine solution of 10 wt% NaCl. We then quantified the liquid chemical compositions by means of Energy-Dispersive X-Ray Spectroscopy (EDS) and Electron probe micro-analyzer (EPMA). This study reveals inconsistences in liquidus surface of the present ternary diagram of the system here in mentioned. Differences of up to 10 wt % compositions of the species have been observed.

Jan 1, 2015

By Warren J. Bruckard, Mark I. Pownceby, Sazzad Ahmad, M. Akbar Rhamdhani

Rutile is the preferred feedstock for producing high-grade TiO2 pigment but due to decreasing resources, alternative materials such as ilmenite is now used to produce a synthetic rutile (SR) feedstock. This requires removal of impurities (e.g. Fe, Mg, Mn) which, for a primary ilmenite is straightforward process. Processing of weathered ilmenite however, is complex, especially when chrome-bearing impurities are present since minor chromium downgrades the SR market value as it imparts color to the final TiO2 pigment, Chrome-bearing spinels are a problem in weathered ilmenites from the Murray Basin, Australia as their physical and chemical properties overlap with ilmenite making separation difficult. In this paper, different sulfidation process routes for weathered ilmenites are analyzed for their applicability to Murray Basin deposits as a mean of remove chrome spinel impurities. Thermodynamic and experimental studies indicated that selective sulfidation of chrome-bearing spinel can be achieved under controlled pO2 and pS2 processing conditions thereby making them amenable to separation.

Jan 1, 2015