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By C. Heckman, M. S. Moats, A. Luyima, W. Cui

"Nucleation and growth of copper on 316L stainless steel from synthetic acidified copper sulfate was studied in the absence and presence of chloride ions and/or organic additives (HydroStar® 4208, DXG®-F7, Cyquest® N-900) using a potentiostatic technique. The current-time data obtained at 0.16V vs. SHE was analyzed using nucleation and growth models. Scanning electron microscope (SEM) images of deposits produced at 300 A m-2 show that the addition of 20 mg/L chloride ions increased the size and reduced the number of copper nuclei. Potentiostatic current-time data from the electrolyte without organic additives indicate progressive nucleation with two-dimensional (2-D) growth under diffusion control. SEM images obtained confirmed progressive nucleation with 2-D growth. 20 mg/L Cl- and 2.5 mg/L organic additives did not change the nucleation and growth mechanism, however the additives increased the number and reduced the size of copper nuclei leading to more uniform coverage of the stainless steel substrate.INTRODUCTION Electrowinning of copper is an important process in the manufacture of high purity copper metal. It is approximated that 20% of the world’s refined copper is produced from acidified copper sulfate solutions by electrowinning (Schlesinger, Sole, and Davenport, 2011). In many plants, copper is electrodeposited on AISI 316L stainless steel substrates for a period of 6-7 days, after which the copper is stripped from the blanks. Even though the deposition time for a commercial copper electrowinning circuit is around one week, it is critically important to control the nucleation, growth, and nature of the initial deposit (Sun and O'Keefe, 1992). Deposit morphology and structure are influenced by the real current density at the electrode surface. The real current density across the cathode surface is made uniform by proper design of the electrowinning cell and electrodes and careful operational practice. Even with good design and control, some current maldistribution occurs. The outcome of severe current maldistribution is poor deposits that affect product quality and/or increase energy consumption. To combat current maldistribution and create a larger operating window in terms of current density, temperature, and copper concentration, small amounts of organic smoothing agents (traditionally guar products) are added to copper electrowinning electrolytes. Moreover, these additives inhibit the growth of copper dendrites, which leads to improved deposit quality by producing bright, smooth, and dense cathodes."

Jan 1, 2015

By K. A. Lewandowski

Heap leaching efficiency is reduced by poor solution flow characteristics (channeling and ponding), which result from compaction and fines migration. Agglomeration of the ore can prevent compaction and immobilize fines, but copper leaching requires an acid-resistant binder to stabilize the agglomerates. Until now, there has not been a satisfactory way to evaluate whether a binder was effective, other than squeezing a handful to see if it ?feels right.? Procedures have been developed to quantitatively determine whether a binder produces agglomerates that can withstand compaction in an acidic solution, and have identified several binders that will provide sufficiently compaction-resistant agglomerates for copper heap leaching. Keywords: Copper heap leaching, Binder performance, Compaction

Jan 1, 2010

By Tracy Jarrett

IN making gold alloys possessing certain physical properties, such important factors as corrosion resistance, color, hardness and melting points must be considered. All of these requirements depend directly upon the composition. It is possible to obtain the same colored gold alloy by using different compositions, but in doing so one may bring in some undesirable property. Other investigations have been carried on in this field by F. E. Carter,1 E. M. Wise,2 and L. Sterner-Rainer.3 To make a complete study of the effect of composition upon these properties, a systematic investigation was carried on involving a range of copper content from 85 to 65 per cent. Elements such as zinc, silver and nickel were used to replace in part the copper content. The gold content in all the alloys remained constant. Only 10-karat gold alloys of those containing 41.6 per cent gold will be considered. All of the alloys were made in an induction furnace. Each alloy was cast in a 3 by ¼ by ¾ -in. ingot. The method of obtaining the melting points and making color determinations was described in a previous paper.4 The Rockwell B scale with the ball and 100-kg. weight was used for all hardness determinations. The submersion of test pieces in concentrated nitric acid is one of the standard corrosion tests used in the optical trade. A test piece in the 50 per cent cold-worked condition, ½ by 2 by 0.043 in., is blanked from a strip using a. die, and the weight, loss per square inch of surface is taken as a means of comparison. The time for this test is 2 ½ hr. of actual sub-mersion of the test piece in the acid. This standard test was applied to all of the 10-karat gold alloys discussed in this paper. The tensile tests were made upon strips of the dimensions shown in Fig. 1. The test pieces after blanking were annealed at 1300° F. for 20 min. and cooled in air. The "drop of the beam" method was used in determining the yield point, as there was a very marked "drop" when the yield point was reached.

Jan 1, 1939

By Xiaoyan Xiang, Wenqiang Yang, Wentang Xia

Magnesium aluminate spinel is widely used in the metallurgical industry as refractory material, however, natural magnesium aluminate spinel is rare and most of the magnesium aluminate spinel is synthetic. The traditional synthesis of magnesium aluminate spinel often needs high temperature, which leads to more energyconsumption. In this article, solid phase sintering process was employed to synthesize magnesium aluminate spinel, in which, magnesium and aluminum oxide were used as raw materials and magnesium and aluminum powder were used as composite additives. The mass ratio of magnesium and aluminum on the effect of synthesis of magnesium aluminate spinel and the characteristic of the synthesis at different temperature and time was discussed. Experiment found that the synthesis temperature was observably lowered when the addition of magnesium and aluminum was 2.0% and 1.0% respectively.

Jan 1, 2016

By A M. Nyembwe, A M. Garbers-Craig, R Cromarty

With the depletion of high-grade lump iron ore, concentrates have been identified as an alternative material for sinter making. Adding concentrates to the sinter mixture reduces sinter bed porosity and gas flow through the sinter bed. This will result in lower sinter strand productivity. A potential solution to this problem is to add concentrate in the form of micropellets. This study investigates the effect of concentrate and micropellet additions on the permeability of the sinter mixture. Permeability was measured on sinter mixtures containing ten to 40 per cent concentrates and micropellets at various moisture contents. The effect of concentrate and micropellet addition on the permeability–moisture relationship was examined. The results confirmed that the addition of concentrates into the sinter mix decreases the maximum permeability of the sinter bed. The incorporation of micropellets into the sinter mix reduced the permeability less than concentrate addition. The study also showed that the maximum permeability of sinter mixes containing concentrate is reached at the same moisture content as the sinter mixture without concentrate addition. For sinter mixes containing micropellets, additional water must be added to obtain maximum permeability. Parameters including the granule size, void fraction and angle of repose were also investigated to evaluate their effects on the sinter bed permeability.CITATION:Nyembwe, A M, Cromarty, R and Garbers-Craig, A M, 2015. Effect of concentrate and micropellet addition on iron ore sinter bed permeability, in Proceedings Iron Ore 2015, pp 69–76 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By W. G. Davenport

Chapter 13 evaluated the %02 in blast, industrial oxygen and oil requirements for smelting FeSrCuFeS2 concentrates~ This chapter examines high eu grade CU2S-CuFeS2 concentrates the same way.

Jan 1, 2001

By W. G. Davenport

The Cu content of industrial flash furnace concentrates varies considerably. It is usually around 30% Cu (Tables 2.1, 3.1) but it may be as high as 55% Cu and as low as 20% Cu. The mineralogy of flash furnace concentrates also varies. The most common Cu mineral is chalcopyrite (CuFeSz), but many concentrates contain bornite (CuSFeS4), chalcocite (CU2S), covellite (CuS) and even native copper (CUO). Pyrite (FeSz) :is also present in many concentrates. This chapter examines how concentrate composition affects flash smelting -with specific reference to 'low-Cu-grade' FeS2-CuFeSz concentrates. Chapter 14 does the same with 'high-Cu-grade' CuzS-CuFeSz?concentrates.

Jan 1, 2001

By Lei Zhang, Xianjun Lu1, Minjie Lian, Liyang Zheng

In order to investigate rheological behaviour of fine tailings backfill pastes, the fine iron ore tailings (size fraction of -0.074mm accounts for 70%) from Fuquan Mining Co., Ltd. of Sinosteel Corporation (Shandong, China) was investigated. The rheological parameters such as slump, viscosity and yield stress of the tailings pastes under different densities were measured in detail, and the effect of paste density on the rheological property and the relationships of different rheological parameters of the pastes were also discussed. According to the results, the rheological behaviour is in accordance with the pseudoplastic fluid in a wide range of paste densities (solid content, w/w) of 65% to 80% and the pastes turn to be Bingham fluids at higher shearing rates. Along with the increase of paste density, the slump drops gradually and the viscosity and shear stress increase gradually. However, the variation extent of the rheological parameters varies at different density ranges. According to the variation pattern of the rheological parameters at different paste densities, the flow ability of the pastes can be classified into three zones. The high fluidity zone was observed at the density range of 65%-69% where the rheological parameters vary slightly along with the paste density, the moderate fluidity zone was observed at the density range of 70%-76% where the rheological parameters vary significantly along with the paste density, and the low fluidity zone was observed at the density range of more than 76% where the rheological parameters vary sharply along with the paste density and the critical density for this sudden variation is about 76%. Furthermore, linear correlations of slump/viscosity and slump/yield stress were observed. It is possible to predict the viscosity and yield stress of the pastes based on the slump measurements.

Jan 1, 2014

By L. E. Veki, S. M. Luukkanen, J. P. Karvonen, J. O. Leppinen

Today there is a consensus that xanthate adsorption on sulfide minerals is primarily controlled by redox reactions occurring at specific potentials on these semi-conductive minerals. Consequently, it is possible to control xanthate adsorption by controlling electrochemical conditions in the system by using oxidizing and reducing agents. The scope of this study was to investigate the possibilities to increase the selectivity of Cu-Fe-Zn ore flotation by applying electrochemical control in the conditioning of the flotation feed. In this work, mild steel grinding in a nitrogen atmosphere was used as the basis to provide a negative starting potential and minimize the amount of oxidation products on sulfide mineral surfaces. To study how different potential levels affect flotation results, a controlled conditioning procedure was utilized maintaining potential at a desired level by titrating the pulp with air. Xanthate adsorption kinetics during conditioning was examined by taking pulp samples for spectrophotometric analysis and laboratory flotation tests were conducted for samples that underwent the controlled conditioning procedure in the potential range of -200mV to +200mV vs. SHE. A clear correlation was detected between chalcopyrite recovery and the potential during controlled conditioning indicating that there was a constant increase in chalcopyrite recovery when the potential was shifted to more anodic values. It is possible that utilizing potential control in the conditioning stage, a smelter grade copper concentrate can be achieved directly in rougher flotation without cleaning stages. Conditioning in favorable conditions had significant positive effects on flotation selectivity of chalcopyrite. The improvement in copper concentrate grade being predominantly caused by the depression of pyrite. By applying the controlled conditioning procedure pyrite recovery in rougher flotation was reduced even low as under 1%, while in the tests without controlled conditioning, pyrite recovery varied between 7.5 – 65.7%. The result of this work indicate that affecting collector adsorption by electrochemical control in the conditioning stage can provide significant improvement in sulfide mineral flotation and industrial applications could lead to decreased chemical consumption, reduced equipment and maintenance costs.

Jan 1, 2018

By M. Shriwas, F. Calizaya

"Controlled recirculation may be considered as a beneficial means in mines of cold climate, where heating of air is required, and in deep or extensive mines, where cooling of air is required. Controlled recirculation can be designed by proper sizing of the booster fans with respect to main fan. Intuitively, it seems that the buildup of methane at the face will cease when a steady state condition is attained, and also that, at that same time, the maximum concentration at the face will remain same as in the return air. This supposition is proved by mathematical analysis that considers uniform mixing of methane in air in successive cycles of recirculation. This study includes two scenarios to show the effect of controlled recirculation on methane concentration in a sample network. Firstly, when recirculation crosscut exists near the working face; secondly, when recirculation crosscut exists away from the working face. The later scenario shows lesser buildup of methane concentration than the former one. INTRODUCTION The controlled recirculation is designed purposefully to allow a partial fraction of used air that increases the air velocity due to increased quantity of air and consequently allows effective dilution of contaminants to improve local ventilation condition at the working face. It can be designed by proper sizing of booster fan with respect to main fan in a ventilation network. Controlled recirculation may be categorized as crosscut, in-line or combined system based upon the configuration of the booster fan locations in a district ventilation network. Research on controlled recirculation has shown numerous benefits of controlled recirculation especially in deep or extensive underground mines, where further heating or cooling is required (Calizaya 1990; McPherson 1993 and Jones, 1987). However, fear of buildup of concentration has misled the mining communities to view the controlled recirculation as a hazard and deprived the mining industry to derive benefits from recirculation. Intuitively, it seems that the buildup of methane at the face will cease when a steady state condition is attained, and also that, at that same time, the maximum concentration at the face will remain same as in the return air. This supposition is proved by mathematical analysis that considers uniform mixing of methane in air in successive cycles of recirculation. This study includes two scenarios to show the effect of controlled recirculation on methane concentration in a sample network. Firstly, when recirculation crosscut exists near the working face; secondly, when recirculation crosscut exists away from the working face. The later scenario result shows the less buildup of methane concentration than former scenario result."

Jan 1, 2016

By Andrzej Warczok

Intensive smelting of copper concentrate in Teniente Converter (CT) leads to the production of high grade matte and highly oxidized slag. Smelting slag is processed in Teniente vascular slag cleaning furnace. The slag composition and forms of copper affect the slag cleaning process and final copper content. Converting of high grade matte in Pierce-Smith converter faces some difficulties in proper slagging of iron oxides. Overblowing in copper making stage allows for slag liquidation but leads to high content of copper oxide in converter slag. Converter slag recycling into CT results in the increase of the participation of oxidic copper. Separate treatment of converter slag and its impact on the forms of copper in CT slag has been analyzed. Thermodynamic properties of a system and kinetic limitations pointed out the negative effect of converter slag recycling on the forms of copper and copper recovery in slag cleaning stage. Experimental results of slag cleaning tests in a crucible scale as well as microscopic examination of laboratory and industrial slag samples supported the above analysis and permitted to formulate recommendations of separate processing of converter slag. Keywords: copper, losses, slag, recycling

Jan 1, 2001

By Dagoberto Brandão Santos, Kairo de Barros Guimarães, Túlio Magno Füzessy de Melo

The effect of the cooling conditions on the microstructure and hardness of a Dual Phase hot-rolled steel 800 MPa strength was investigated. Simulations of the cooling conditions using a dilatometer were carried out from samples of a hot rolled coil with variations of the intermediary temperature from 620 to 740°C, isothermal holding time between 1 and 10 s and coiling temperature between 50 and 400°C. In addition, two CCT (Continuous Cooling Transformation) diagrams were developed to evaluate the effect of the isothermal holding time on the phase transformations of the remaining austenite. It was observed that the intermediary temperature has a strong influence on the kinetics of the phase transformation, as well as the isothermal holding time influences the amount of ferrite formed and, consequently, the final microstructure and hardness of the material. The coiling temperature did not cause significant changes in the amount and morphology of the ferrite, but a gradual replacement of martensite with bainite was observed, which, in addition to the self-tempering effect, contributed to the hardness reduction.

Oct 1, 2019

By F. Khomamizadeh

In this study the effect of solidification rate, T6 and T7 heat treatments on thermal fatigue resistance of A319 aluminum was investigated. Increasing of the solidification rate improved the thermal fatigue resistance of the alloy by refinement of the microstructure. The most sensible areas for thermal fatigue crack growth were the eutectic zones, T6 and T7 heat treatments improved the thermal fatigue resistance of the alloy by enhancing of the matrix resistance against the crack propagation. The slight reduction of the thermal fatigue resistance after T7 heat treatment is attributed to coarsening of the precipitates which reduces the matrix resistance.

Jan 1, 2005

By Ari Jokilaakso, Junjie Shi, Zhuo Chen, Pekka Taskinen, Xiang Gao

The amount of copper flash smelting slag has increased during the recent years along with an increasing slag-to-metal ratio. During slag tapping, some copper sulfide is mechanically entrained. As a result, it is necessary to recover copper matte from the slag by suitable methods. At present, the most common way is slow, controlled cooling in a transfer ladle. However, research on the detailed effects of slow cooling and the function of slag modification is rare. This paper described experiments that were performed at different cooling rates (0.5, 1.5, 3, and 7 °C/min), with and without additive. A detailed characterization of the copper-rich phase and its particle size was subsequentlymade using SEM-EDSmicrographs and image analysis software.With a decrease in cooling rate, the particle size of the copper-rich matte phase became larger. The addition of gypsum and carbon as a slag modifier affected the size of the copper-rich phase slightly, and its chemical composition was modified compared with the experiments without additive.

Jul 31, 2020

By Jinsheng Wang, Zhixiong You, Xuewei Lv, Yu Zhang, Jie Dang

Electro-titania slag is generally used as the raw material for titanium dioxide production by sulfate process. The phase composition of titanium as well as their disseminated grain size have significant effect on the acidolysis of titanium. Anosovite is considered as the most favorable Ti-bearing phase due to its high acidolysis ef ficiency, while silicates and rutile are not soluble in concentrated sulfuric acid. Different cooling rates will play a significant effect on the phase structure and particle size, which directly affects the acidolysis ratio of titania slag. In this paper, the influence on acidolysis ratio of titania slag at different cooling rates was studied. The results revealed that slower cooling rate resulted in the formation of larger particle size and a comparatively higher acidolysis ratio was obtained. On the contrast, rapid cooling was disadvantageous to the leaching of titanium as the smaller particle size anosovite was wrapped by glass phases.

Mar 1, 2018

By Ho-Jung Shin

The influence of cooling rate from 1873 to 1473 K on the size and morphology of austenite grains was studied using a Fe-O.I5 % C-I.5 % Mn alloy. The experiments were carried out at three different cooling rates of O.33KJsec, O.67KJsec and air-cooling. The austenite grain showed an isotropy at 0.33KJsec but maximized anisotropy at O.67KJsec and become much less. anisotropic. In order to account for these phenomena, a model was developed for estimating the size and morphology of austenite grains as a function of cooling rate. The driving force for the )( phase formation from 0 phase is caused by undercooling degree due to cooling rate and energy barrier is restricted to the misfit strain energy which is caused by mismatch between )( phase and 0 phase. The )( phase from 0 phase could be formed on not random orientation index systems but specific orientation systems depending on cooling rate.

Jan 1, 2001

By H. Yoshida, H. Hatta, T. Suzuki

"The effect of the copper and magnesium contents and quenching rate during quenching on the age hardening behavior of 2000 series aluminum alloys was investigated. For the higher copper-containing specimens as conventional alloys, like AA2024, precipitation of the stable phases increased as the quenching rate decreased under the as-quenched conditions. The maximum hardness after the artificial aging of air cooled(AC) specimens was much lower than that of the water quenched(WQ)specimens. On the other hand, for the lower copper-containing specimens, coarse precipitation did not increase even in the case of the AC. The age hardening behaviors of the WQ and AC were very similar such that the maximum hardness and aging rate were almost the same. Many parts of the fine precipitates that increased the hardness were thought to be the GPB zone or fine S’ phase for the WQ and relatively coarse S’ phase for the AC. From the calculated CCT(continuous cooling transformation)diagrams, the lower copper-containing specimens could maintain the copper and magnesium in the solid solution state during the AC, so they could be quenched at a rather slower quenching rate like the AC.INTRODUCTIONThe 2000 series aluminum alloys, containing copper and magnesium as the major chemical components, are some of the well-known heat treatable aluminum alloys. These alloys have a high quenching sensitivity, thus the age hardening ability of these alloys decreases with as low quenching rate. To prevent the decrease of the age hardening ability, quenching is done by a method such as water quenching, which is not very efficient in an industrial situation, because the method requires such large equipment. For these alloys, reducing the quenching sensitivity helps them to be produced in a rather convenient way. For example, 6000 series alloys such as A6063 have low quenching sensitivity, thus they could be quenched by only air cooling just after extrusion and they do not need water quenching. Based on these reasons, investigations of these alloys with high copper and magnesium contents have been conducted in the past to find a way to lower the quenching sensitivity by adding transition elements such as manganese, chromium and zirconium (Kanno, Suzuki, & Itoh, 1986; Suzuki & Itoh, 1986; Kanno, Sakuma, Muromachi, & Watanabe, 1988). However, very few studies have focused on the quenching sensitivity of the lower copper and magnesium containing alloys because of their usage for structural components with high strength, and most of the past studies have used only the fast quenching method like water quenching. On the other hand, from our recent results, there is a possibility to lower the quenching sensitivity of 2000 series alloys with lower alloying elements. In this paper, the effect of the copper and magnesium contents with lower alloying elements and quenching rate, especially in case of slower quenching rate than conventional quenching method, on the age hardening behavior of the 2000 series alloys is investigated by the hardness measurement, structure observation and thermal analysis."

Jan 1, 2018

By A. G. Doll

The Bond low energy impact (crushing) work index test is specified to be performed on rock specimens between 50 mm and 75 mm in effective diameter. NQ-diameter drill core, frequently used in mineral exploration programs does not meet that specification, it being 45 mm diameter or less. This paper reports the effect of performing the impact test on contiguous sections of HQ diameter and NQ diameter core, exploring the hypothesis that the contiguous intervals give equivalent results in spite of the core diameter difference.

Jan 1, 2012

By Ayman A. El‑Midany, Hassan E. El‑Shall, Kerri‑Ann A. Hue

Modification of clays is necessary for the zearalenone (ZEN), as long-chain mycotoxins, removal. The organic-cations were usually used to modify the clay hydrophobicity to accommodate the large mycotoxin molecules. In this study, tri capryl methylammonium (TCMA) chloride and common corn oil were used in clay modification. Several characterization techniques such as XRD, FTIR, and TGA were used to identify the d-spacing changes after modification either by TCMA or corn oil. The results of applying the TCMA-corn oil-modified clays in ZEN removal indicated a noticeable improvement where more than 90% of ZEN could be removed in vitro at acidic and neutral pH values. The success of eliminating a high percentage of ZEN molecules is due to the expansion of intergallery spacing as a result of TCMA surfactant intercalation within the clayforming layers. The removal percentage does not depend only on pH but also on the amount of clay used. In addition, the ZEN removal in the presence of corn oil is better at acidic pH and small clay amount where the ZEN can be fully removed.

Sep 27, 2021

By Satyajeet Ghosh, Edward F. Glynn

Many of the proposed techniques for calculating the reliability of rock slopes utilize Monte Carlo simulation. Monte Carlo approaches are attractive because they provide means of solving probabilistic problems with deterministic algorithms. One disadvantage shared by all simulation-based stability analyses is that they assume all the random variables are independently distributed. The paper focuses on the independence assumption and examines the effect of correlation on the probability of failure. In particular it considers the influence of possible (albeit hypothetical) correlation between joint attitudes [(8)] and joint friction angles [($)]. The study indicates that neglecting correlation can introduce significant errors into the reliability computations. With a modest positive correlation between [8] and [$] the error can lead to a 100% overestimate of the probability of failure.

Jan 1, 1982