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By Graham Cooke, Abhishek Lahiri, Animesh Jha, E. Jeya Kumari

"CO2 reduction by alternative energy devices such as wind-power, electric vehicles utilize rare-earth elements (REE) in several forms; such as in piezo-electric devices, batteries and magnetic materials. In 2010, the 95% of Rare Earth supply is controlled by China, compared to USA being dominant supplier in the 1980s. The dependence upon a single source of lanthanides has prompted the utilization of lower grades of titaniferous mineral concentrates, which often have rich seams of REE. We propose a new methodology, which utilizes the low-grade minerals for the extraction of synthetic rutile and also significant quantities of REE. We demonstrate the alkali roasting of lower grades of mineral concentrates and subsequent leaching in an aqueous medium for preferential flocculation of REE during the extraction of synthetic rutile. Changes in mineral structure during alkali roasting and leaching determine flocculation of REE and permit their separation at the front end of unit process.The physical chemistry and crystal structure of minerals in equilibrium with alkali and aqueous medium play an important role, which we explain by demonstrating the changes in the crystal structure. The quantification of separation of RE oxide via chemical analysis suggests that it may be possible to separate rare-earth oxides between 50 and 80% of the initial concentration in the non-magnetic fractions of ilmenite, for example. The microstructural and X-ray diffraction analysis points out that the presence of alumina and roasting with potassium based alkali enhances the separation and flocculation of rare-earth elements at the front end of the process after roasting. The process allows the recovery of CO2 generated by recycling into the process for the regeneration of alkali."

Jan 1, 2011

By Vladimir I. Skorohodov

The technology for copper utilization from circuit boards etching is proposed. The technology is based on combination of electrochemical and sorption methods. The conditions of copper electroextraction from ammonia-chloride solutions with obtaining of cathode copper are defined. The stage of electrolysis is destined for copper recuperation from etching process. Due to the electrochemical processes are unacceptable for cathode precipitation of the copper from diluted solutions such as rinse waters, the concentration on the strong-based cationites are used. After filtration throw the sorption columns solution is directed to the stage of circuit boards washing. It allows organizing close loop water recirculation. After saturation. resin is 'regenerated by chloride ammonium solutions. Obtained eluate directed to the etching stage, Generally. the technology provides copper recuperation and minimize wastes amount.

Jan 1, 2001

By Tseng. B. H.

Samples of unchlorinated and chlorinated carbonaceous concentrate from a carbonaceous gold ore were analyzed by transmission electron microscopy (TEM) for organically bonded sulfur and chlorine. The concentrate assayed 1.53 oz/t gold and 6.01% organic carbon. Much of the organic carbon occurred as sizable coarse particles up to several hundred microns in size, which showed no visible evidence of reaction with chlorine after chlorination treatment. Both the untreated and chlorinated fractions of the carbonaceous concentrate were analyzed by the TEM method, which detected organically bonded sulfur in all of the carbon particles examined in the untreated sample, ranging from about 1 to 5% organic sulfur, and averaging near 3.1%. TEM analysis of 40 carbon particles in the chlorinated sample indicated that organic sulfur was reduced significantly in the carbon and replaced in part by the chlorine, as the result of chlorination.

Jan 1, 1987

By A. R. Udupa

The reduction roasting behavior of chalcopyrite has been investigated using various combinations of a desulfurizing agent, i.e., CaO or Na2CO3, and a reductant, i.e., CO, H2 or C. Using these, combinations the sulfur is removed from the mineral as CaS or Na2S rather than SO2 as is the case with conventional copper smelting and converting. The laboratory reduction ex¬periments were conducted using thermogravimetric analysis (TGA) and boat tests of mixed combinations of fine particulate reactants subjected to a continuous gas stream. The degrees of metallization were determined by both weight loss and chemical analysis methods and the products examined using optical and scanning electron microscopy and electron probe microanalysis. The percent reduction after one hour at 900°C ranged from 60% to 94%. From these data It was possible to provide postulations as to the controlling reduction mechanisms.

Jan 1, 1983

By Akira Kaneda, Nozomu Hasegawa

"In the Mitsubishi Continuous Copper Smelting and Converting Process, slag/matte mixture overflowed from the smelting furnace is separated continuously in an electric furnace (slag cleaning furnace, CL-furnace). In order to improve the separation efficiency of slag and matte and to minimize power consumption, the design and the operating conditions of the CL-fumace should be optimized. In the previous study, the authors developed a mathematical model for simulating phenomena in the CL-furnace. The model consisted of 3 modules, electric field analysis, heat and fluid flow analysis and the particle tracking method. In this study, the model was partially modified: k -E. model was adopted, and the effects of various conditions, such as furnace shape (including accretion) and scale, electrodes configuration, immersion depth of electrodes, and thickness of slag layer, were evaluated. And the optimum design and operating conditions were discussed.IntroductionUnder the recent environmental restriction, advantageous features of the Mitsubishi process have attracted much attention. The process uses 3 furnaces connected by launders. Mixture of matte and slag formed in a smelting furnace flows continuously to a slag cleaning furnace (CL-furnace), where the matte is separated from the slag. The matte is continuously siphoned out to a converting furnace and converted to blister copper. The slag overflowed from the CL-furnace is discarded. Because the slag contains about 0.6 % copper, improving slag/matte separation efficiency and decreasing copper loss make a great profit. Moreover the process requires a large amount of electric energy, so reduction of electric power consumption brings in enormous benefit.The objective of this study is to optimize the design and the operating conditions of the process, especially the CL-furnace. This will be achieved by developing the mathematical model and clarifying relations between the design or the operating conditions and various phenomena in the furnace. Fig. 1 shows an outline of the CL-furnace. The mixture entering through an inlet is separated to slag layer and matte layer . In order to maintain the temperature of the melt at a predetermined level, 6 electrodes are immersed into the lag and Joule's heat is generated by 3-phase alternating current flowing."

Jan 1, 2000

By R. C. Hubli

A panial equilibrium model? to simulate the dissolution of millerite (NiS) in aqueous solutions containing copper(II) chloride as the oxidizing species has been developed. The predominant copper(I) and copper(II) species are CuQ3 and CUO2 respectively. The model computes the initial concentrations of the species present in the aqueous phase under the specified input conditions, prior to the simulation of dissolution. During the dissolution of millerite, nickel enters the leach liquor as NiH and it has been found that the H+ decreases as a function of NiS dissolution. The simulation has been accomplished under conditions prevailing during actual dissolution, with only one mineral undergoing dissolution. The model can be applied for the simulation of co-dissolution of two or more sulfides. Under the given conditions, the precipitation of Cu1(OH»)O is negligible but loss of Cu(1l) could be significant if the initial H+ is lower than 0.03 M. The results of the simulation compare favorably with experimental observations.

Jan 1, 1996

By Junzo Hino

Most of the waste that contains a small portion of copper is landfilled. The recycling process of copper from the waste, such as shredder residue, should be developed in order to save mineral resources and prevent environmental pollution. Shredder residue, generated from disposed automobiles and electric appliances, consists of many types of plastics, glasses and metals. The combustion heat of plastics is efficiently used for smelting in the recycling process that consists of melting and reduction. Because the waste contains numerous components the knowledge of the distribution behaviors of the main components is necessary to develop the recycling process. The distribution behaviors in the recycling process are evaluated by using the thermodynamic calculation program, HSC Chemistry. The calculation results are compared with the practical operation data of the recycling process and discussed.

Jan 1, 2003

By Jing Zhan, Tian-zu Yang, Wei-feng Li, Li-Hua Jiang, Shi-yan Xu, Jian-yang Huang, Chuan-fu Zhang, Yan-qing Fan

The amount and activity of coal, reduction temperature and other parameters of the process of bottom-blown reduction of liquid high lead slag were investigated in laboratory. Methods to strengthen the bottom-blown reduction process were studied by industrial production. The results were in the follows: the reduction temperature was 1150℃; reduction time was 1.5h; the reductant was anthracite; lead content in slag was controlled to 2%; the rate of coal was 7% and gasification loss of coal in high temperature was severe; liquid lead slag reduction rate was faster with coal; prolonging the reaction size had little effect on reducing lead in slag; the size of the reactor can be further reduced.

Jan 1, 2015

By M. B. Mesina

Mechanical separation systems are widely used nowadays for scrap metal processing, but they have natural limitations in product quality. The quality of the final product is considerably improved when sensors are used in the separation process. This paper describes new methods using sensors for scrap metal sorting and quality control. An example is the electromagnetic sensor, which uses the electrical and magnetic properties of materials to distinguish between different non-ferrous metals. The measurement results of two prototypes are reported. The benefits and the possibility to integrate such systems into practical applications regarding the processing of secondary raw materials are also described.

Jan 1, 2003

By G. S. Gupta

To predict the iron oxide concentration a mass transfer model has been developed for an Induction Smelting Process (ISP) in which self-fluxed composite pellets (made of iron ore, brown coal and lime) are melted in a single phase induction furnace in conjunction with top blown oxygen. Transient mass balance equation with complex boundary conditions has been worked out by adopting a relatively new approach known as the cell model approach. These equations have been solved numerically using finite difference technique to obtain the iron oxide concentration profile in the ISP. Numerical and experimental results obtained for iron oxide concentration show a reasonable agreement with each other.

Jan 1, 1991

By Marcio Toshio Tanaka, Marcelo Breda Mourao, Cyro Takano, Cesar Yuji Narita

"The concerns in questions related to the environmental impact in the steelmaking industries caused mainly on the gas emissions such as the dioxide carbon are due to its raw material such as the coal, a fossil and non renewable resource. The purpose of this paper is to replace from 10% to 50% of the coal used in cokemaking by mixing it with a renewable source (wood charcoal). The powder (- 325 mesh) from both raw materials (coal and wood charcoal) were mixed in order to obtain a briquette that was then heat treated at 1100°C to obtain the biocoke. Results of usual analysis (coke reactivity index, coke strength after reaction and cold crushing strength test) were employed to compare to regular coke briquettes. It was found that biocoke with different amounts of wood charcoal present features enabling it to be used in some ore reductionprocesses.1. IntroductionThe iron and steelmaking industry is a heavy emitter of carbon dioxide; according to the World Steel Association, 6.5% of global emissions of this greenhouse gas is due to the production of ferrous materials [ 1]. This is due to the fact that the fuel and reductant employed in the blast furnace is metallurgical coke, obtained from fossil coal. There are some projects aiming to reduce or even eliminate the emission of fossil GHG in the iron and steelmaking process [2]. Most of them propose the capture and storage of the gas (CCS) [3], a technology not yet proven. Other studies point out that the coke consumption in the blast furnace could be reduced by using high reactivity coke; this could lead to lower temperatures in the thermal reserve zone of the blast furnace and consequently less fuel rate in the furnace.The use of biomass in the iron ore reduction process is known as an environmentally accepted solution, as biomass does not release already fossilized carbon."

Jan 1, 2013

By James T. Skoch

With the ongoing pressure on the secondary aluminum business to limit the amount of waste generated from processing aluminum dross, it becomes very advantageous to preprocess the dross to reduce waste. The advantage of preprocessing is that it significantly reduces the oxides and salt cake generated when melted. Various products can be produced from the oxides for the steel industry. The following paper will demonstrate that removal of oxide fines before melting will result in large volumes of material not being landfilled. We will show that the end result of this technology is to significantly reduce the amount of salt cake sent to a landfill while maximizing the recyclability of the aluminum dross.

Jan 1, 1995

By Shigeru Ueda, Shin-ya Kitamura, Dong Jun Shin, Xu Gao

Steelmaking slag contains useful elements such as P and Mn. Generally, in the carbothermic reduction of slag, not only P but also Mn are reduced and a Fe–P–Mn alloy is formed. In this study, the possibility of the separation of Mn and P was investigated. A mixture of synthesized slag and graphite was heated at 1773 K, and the compositions of the separated slag and metal were analyzed. The results showed that with a decrease in basicity, the reduction of P was enhanced but that of Mn was suppressed. Thus, under an optimum condition, steelmaking slag was separated into a Fe–P alloy and a high MnO-containing slag. Although further investigation is necessary, the formed alloy and slag could be used as raw materials for fertilizers and Fe–Mn alloys, respectively. This paper elucidates the concept of this process and the results of the fundamental experiments.

Mar 1, 2018

By M. G. Silva-Valenzuela, H. Wiebeck, F. R. Valenzuela-Diaz, J. C. Arjona, S. H. Wang

Urea is the most used nitrogen fertilizer around the world being responsible for many environmental problems. Preparation of microcapsules from biodegradable polymer has been reported as a main system to sustain active substances, finding application in different areas. The objective of this work was to sustain urea in nanocomposite microcapsules of poly(3-hidroxybutyrate) (PHB) reinforced with a smectite Brazilian clay in its natural (MMT) and modified (OMMT) form. PHB/MMT and PHB/OMMT microcapsules were obtained by w/o/w emulsion. Characterization were performed by XRD and optical microscopy. Structural and morphological differences observed by XRD and optical microscopy shown that PHB/OMMT microcapsules are smaller than PHB/MMT microcapsules, with average size diameter ranging * 49 μm. Results indicate that PHB/OMMT microcapsules present more defects and fractures than PHB/MMT microcapsules.

Mar 1, 2018

By Luciano E. Ramírez, Jesús L. Valenzuela, José R. Parga

"An innovative process for removing copper cyanide complexes including silver and zinc from cyanidation circuits has been developed. The technology was based on the inducing the nucleated precipitation of copper and silver in a tube serpentine reactor, using sodium sulfide as the precipitate and sulfuric acid as pH control. The results showed that pH had a great effect on copper cyanide removal efficiency and the optimum pH was about 3 to 3.5. At this pH value copper cyanide removal efficiency could be achieved above 97 and 99 % ,when influent copper concentration ions were 650 and 900 ppm respectively. In this process (sulphidizaton-acidification-recycle-thickening), the cyanide associated with the copper cyanide complexes is released as HCN gas under weakly acidic conditions, allowing it to be recycled back to the cyanidation process as free cyanide. This system was successfully commercial applied at Minera William in Mexico.IntroductionThe recovery of gold and silver from minerals and concentrates with cyanide is an important hydrometallurgical process, which has been studied for more than 124 years. Patented by MacArthur in 1888 [1], the process relies on the fact that gold dissolves in aerated cyanide solutions to produce the gold cyanide complex. The stoichiometry by wich this reaction occurs is known as the Elsner equation as shown here. Silver is accomplished in the same fashion."

Jan 1, 2012

By Sheng-li Wu, Guo-liang Zhang, Bo Su

The mineralogical characteristics of iron ores can influence their high temperature sintering performance. In this study, eight iron ore samples from Brazil, Australia, and South Africa were characterized by their chemical composition, mineral types, particle morphology, and gangue dispersity. Meanwhile the influence rules between the mineralogical characteristics and the high temperature characteristics were evaluated and analyzed. The results showed that the effect of SiO2 on assimilation characteristic of iron ores was relatively complex, Al2O3 and LOI of iron ores had negative correlation with assimilation temperature of iron ores, the dense slab-flaky mineral granule restrained to the assimilation characteristics of iron ores; liquid phase of iron ores with high SiO2 content and low Al2O3 content had high fluidity, and the higher dispersity of gangue minerals in iron ores was good to the fluidity of liquid phase.

Jan 1, 2015

By Chao Li, Shi Sun, Hongxu Li, Jiaqi Fan, Qi Liu

With the great demand of consumer electronics (CE) and electric vehicles (EV), cobalt has become one of the more scarce energy metals.The recovery of cobalt from a copper converter slag, which contained over 2.4% Co and was accumulated as industrial waste, by reduction-sulfurization smelting was explored. Quantitative analysis of treated slag showed that activated carbon and ferrous sulfide can be used to settle cobalt into matte as Co–Fe alloy. The experiment was carried out at 1673 K with a reducing atmosphere of burning electrode graphite crucible. It was found that the recovery of Co would increase within creased added activated carbon, was unaffected at higher carbon additions, and for low additions of carbon increased at higher FeS additions. Over 95% Co, 99% Cu and 62% Fe could be settled into matte. Preliminary separation of Co from converter slag by pyrometallurgical smelting is proposed.

Mar 1, 2017

By Y. A. Chang, J. Woodford, C. R. Kao

Reactive diffusion studies between NbC and Si were carried out at 1300 °C under a vacuum of 10-5 torr and a uniaxial pressure of 1 MPa. The annealing time ranged from 8 to 100 hours. The Si used was single crystal silicon; the NbC was hot-pressed powder compact. A NbSi2+SiC two-phase reaction layer formed with NbSi2 as the matrix and SiC as discontinuous particles. The microstructure of the reaction product is homogeneous, dense, and fine. The NbSi2 grain size and SiC particle size are in the micron range. The growth of the reaction products follows parabolic kinetics. Extrapolation of the data to zero thickness suggests an apparent incubation time of 3.5 hours. However, for short annealing time «60 hours), the thickness data can be approximated by linear kinetics with an initial growth rate of about 2 11m/hr. Based on these experimental observations, a growth mechanism for the reactive diffusion between Si single crystal and NbC powder compact is proposed. We propose that the nucleation sites for the SiC particles are at the voids of the NbC powder compact. This proposed nucleation mechanism offers a potential way of controlling the SiC particle size by changing the void size and void density of the NbC powder compact. This hypothesis, if proven to be true, will allow us to control mechanical properties of the composites by tailoring the SiC particles formed. It is also pointed out that the microstructure requires Si to be the dominant diffusing species and to diffuse through the reaction layer, while Nb and Conly have to undergo local rearrangement.

Jan 1, 1996

By R Bartlett

Process engineering-science originally developed for percolation leaching of ore in heaps is extended to the decontamination of unsaturated soil, either in situ or after excavation and emplacement as a soil heap on an impervious pad. Phenomena considered include: soil matrix porosity and permeability; percolating solution retention, capillarity and flow; washing sweep efficiency; optimum solution application rates during leaching; soil agglomeration to improve soil permeability and soluble contaminant transport by diffusion in soil agglomerates. Practical aspects briefly discussed include leach pad construction, solution distribution and recovery from the soil, and solution containment.

Jan 1, 1994

By Nagy El-Kaddah

"One of the emerging technologies for the production of ultra-clean metals is electromagnetic filtration. The theory and the mechanism of electromagnetic separation of inclusions from molten metal are briefly reviewed along with basic electromagnetic separation systems. This paper focuses on inclusion removal in the induced current separators, with specific reference to a new separator developed at the University of Alabama. A simple analytical model is presented for the analysis of particle separation in such a system. The role of the applied magnetic field on inclusion removal will be discussed. It is shown that particle velocity increases exponentially with increasing magnetic field strength. At moderate field strengths, the velocity of 50 to 100 u. inclusions· are an order of magnitude larger than those achieved by buoyancy. The separator developed at the University of Alabama is described together with experimental results of laboratory and large scale experiments on purification of molten aluminum. These results demonstrate the capability of the system for producing super-clean metals.IntroductionThe nature of extraction, refining and processing of metals is such that oxides and other non-metallic particles will always be present. This is due to the highly reactive nature of metals with oxygen and other non-metallic elements. The presence of these type inclusions in metals, even in minute amounts, can seriously flaw the reliability and performance of the final product. They not only reduce the strength and the stiffness of the metal/1/, they are the reason behind many of manufacturing defects such as porosity in castings, surface and internal cracks in continuously cast ingots and rolled products, etc., which act to cause premature failure of manufactured parts. In fact, for critical applications such as turbine blades, there is virtually no tolerance for inclusions above ten microns in size /2/. Therefore, removal of inclusions from the liquid metal is an essential processing step.The demand for cleaner metals has brought major changes in the technology and practice of metal refining and casting. Inclusion removal from the melt is currently achieved by passing the melt through a series of melt treatment systems, including induction stirring furnaces, argon-stirred ladle, and ceramic foam and deep-bed filters /3,4/. These systems are generally capable of removing all inclusion particles above 50 microns in diameter, which meets current cleanliness requirements for most applications. However, they may not be able to meet the projected cleanliness levels for critical applications due to kinetic and operational limitations of these systems in removing smaller particles /5/."

Jan 1, 1996