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By Alex Del Castillo

The mineral processing industry has followed the development of database control systems, and various systems have been installed in existing and new plants. The goal is to improve product quality, raise productivity and lower production costs. Improvements in different units for mineral .processing .have been applied. This has led to increasing information for the operators. To support the operators and for an easy overview of the process, a complete concept for an integrated process-control system is required. This paper describes the plant-wide [process control system for the Collahuasi copper project located in northern Chile. The total investment for the project was $1,700,000,000 and included a port area and two copper processing plants, an oxide plant with a cathode production of 50 tons per year and a sulfide plant with a concentrate production of 330 kilotons per year. The main characteristics of the plant-wide process control system include a 200- kilometer long redundant control network and a 24-kilometer long redundant serial network providing coverage for the entire plant. The plants are located around 4,700 meters above sea level, serial communication lids allow the integration of over 2,700 SCADA data units, and the system handles over 7,500 physical signals plus the SCADA data integration. The main equipment consists of 39 different sized controllers, 16 operator stations, 5 engineering stations, 2 information management systems and 4 X- terminals. The project management, control configuration, factory acceptance test, system integration test, training, commissioning and start-up were carried out in close cooperation with the customer. The result was completely satisfactory for the customer.

Jan 1, 1999

By Andrey V. Tarasov

To carry out a physicochemical substantiation of a transition to ?soft? modes of reduction of calcine obtained by desulfurizing roasting of nickel concentrate produced as a result of copper-nickel converter matte separation in a nickel anode production circuit, an analysis has been conducted of the macrokinetic behavior of actual calcine samples in the presence of gaseous H2-CO mixtures and solid reductant additives. Within a temperature range of 900°C to 1100°C the main regularities typical of the calcine reduction process with individual gases (H2, CO) also take place when using a gaseous mixture. Under the conditions of low-temperature (900°C to 1000°C) nickel oxide reduction with products of fuel oil conversion in the presence of coke, the role of the latter is insignificant from the technological viewpoint. As a result of the present investigations, we have obtained analytical expressions of macrokinetic parameters of the reaction interaction within the [NiO] calcine-H2-CO-C-CO2-H2O-O2-N2 system.

Jan 1, 2005

By Bowang Xiao

Recently more and more attentions are paid to high pressure hydrogen quenching (HPHQ) for its advantages such as environmental friendliness, low distortion, etc, compared to oil and water quenching. In HPHQ process, heat transfer coefficient (HTC) usually varies from part surface to surface because of the intense variation of gas velocity around the part. This article studies the effect of HTC distribution on part distortion after HPHQ and shows that finite element simulations considering HTC distribution predict different distortion from these without considering HTC distribution. It is also pointed out in this article that HTC distribution can be optimized by adjusting part orientation and HPHQ condition so that part distortion is minimized.

Jan 1, 2010

By P. A. Mahanwar

Flyash were melt mixed with nylon 6 at a 30wt% concentration. TYZOR® TPT, a coupling agent, was used to facilitate the link between filler and matrix. The morphological characterization, using SEM, revealed sufficient matrix residue on the filler surfaces thus confirming the strong interfacial bonding between the filler and the matrix on treating. Tensile, impact and the flexural properties of the composites were also improved with the incorporation of coupling agent. As flyash particles tend to impart a grayish color to the plastic, TiO2 pigment was employed to make the formulations aesthetic. The pigment was added to the filled system in 0.1, 0.5, 1.0, 1.5, 2.0 wt/wt ratios. Scattering of incident light and spectral reflectance was higher for smaller particle size flyash. Moreover an increase in the scattering with increase in pigment concentration indicates better dispersion of the pigment, which again is due to the presence of coupling agent.

Jan 1, 2006

By Elisa Alonso

Recycling is generally a more sustainable alternative to landfilling. Its financial costs however, do not always justify its practice, especially in the short term. As a result, even for precious metals such as platinum, significant amounts can end up unrecovered. In considering risks of materials scarcity for firms that require platinum and platinum products, this paper examines how recycling provides additional benefits as a risk-mitigating strategy against scarcity. The experimental platform for this examination is a System Dynamics simulation model that strives to capture the dynamics of platinum market supply, demand and price. The detailed structures of supply and demand are key features of the model. Results show that since the secondary supply of platinum depends on a supply chain separate from primary extraction, recycling can diversify the risks of primary supply instabilities and reduce the impact of price fluctuations upon firms.

Jan 1, 2009

By Lenny Winkel

With the aim to develop a solar-driven process for the extraction of copper from sulfide concentrates research on the decomposition of copper sulfides under inert atmospheres has been initiated. Thermogravimetric measurements on chalcocite,(Cu2S) revealed that copper is formed already at 1823 K. Chalcopyrite (CuFeS2) also disintegrates at this temperature, although at a lower rate. Copper and iron have been identified in the solid residue. The results confirm the feasibility of copper extraction by direct decomposition of sulfides under atmospheric pressure. The decomposition under inert atmosphere prevents generation of SO2, it also alters the behavior of volatile impurities during decomposition of copper sulfide concentrates. Chemical equilibrium calculations for chalcopyrite contaminated with enargite (Cu3AsS4) have shown that the absence of an oxidic slag allows for a complete evaporation of arsenic and subsequent separation from intermediate sulfides. The need to better assess the potential of direct sulfide decomposition has prompted the development of an experimental setup for studying the decomposition reactions. The experiment has been devised such that data on the decomposition kinetics and on impurity removal can be obtained at temperatures up to 2500 K.

Jan 1, 2003

By P. N. Anyalebechi

The effects of Si (0.19-0.52 wI. %), Fe (0.20 wI. %-0.44 wI. %), and Cr (0-0.10 wI.%) on the response of ingots of aluminum alloy 3004 solidified at different rates (O.IO°C/s to 30°C/s), to homogenization heat treatment have been investigated. Response to homogenization was determined by quantifying the following microstructural parameters: (i) amount of Mn retained in solid solution; (ii) types, relative amounts, sizes, size distributions, shapes, and chemical compositions of second phases; (iii) extent of the alpha-transformation (i.e., AI6(Fe,Mn) --7 (XAI12( Fe,MnhSi) reaction; (iv) dispersoid formation; and (v) alleviation of dendritic microsegregation. Of the three alloying elements investigated, Si had the greatest effect on the response of aluminum alloy 3004 to heat treatment. Increase in Si content, fineness of cast microstructure, and homogenization temperature facilitated alpha-transformation reaction, dissolution of Mg2Si, loss of Mn supersaturation, and formation of AldFe,Mn)3Si and Mg2Si dispersoids.

Jan 1, 2008

By Qingguo Xue, Jingsong Wang, Siyang Long, Jun Zhao, Haibin Zuo

In order to effectively use of low rank coal, the thermally dissolve coal (TDC) was extracted from four kinds of low-rank coals by N-2-methyl-2-purrolidinone (NMP) at high temperature and high pressure. The structures of thermally dissolve coal and residues were characterized by element analysis, FT-IR spectra. The effects of temperatures, coal rank, solid-liquid ratio and extraction time on the extraction yields of TDC were studied, respectively. Moreover, the extraction mechanism of TDC at mild conditions is proposed. The results show that the ash contents of TDCs from four raw coals are significantly lower than that of raw coals, and the volatile contents and H/C are significantly improved. For KL coal, with the increase of temperature, the extraction yield of KL-TDC is improved evidently from 33.75% to 56.25% and the ash content is decreased from 0.57% to 0.49% at 350 °C.

Mar 1, 2018

By Thomas Prietl

The use of gas stirring systems through the furnace bottom is common for anode and holding furnaces in the copper industry The first implementation of a gas stirring COP KIN® system in a Peirce-Smith converter was performed at the New Boliden smelter, Rönnskar, Sweden. In addition to other benefits, a decrease in process time and a decrease of the oxygen content in the blister copper were observed. To determine the effects of the gas stirring system and the process endpoint, an optical production control ?Semtech OPC system? was used. The light emission of the converter flame as an optical process parameter provides qualitative on-line process information, and is also used for endpoint determination of the slag making process, on-line control of iron content in white metal, quality control of slag etc. The results, benefits and risks of using the COP KIN® and OPC system for a Peirce-Smith converter are reported.

Jan 1, 2005

By Tiebao Yang

In high pressure die casting processes, a die plays a critical role in removing heat from the molten metal during the cavity filling and solidification stages. Proper control of die temperature is essential for producing superior quality components and yielding high production rates. This paper proposes a local temperature control scheme for die thermal management based on a computerized intelligent real-time monitoring and control system (IRMCS). In this scheme, cooling water lines are controlled by a pump and solenoid valves. A controller is designed according to the law of die temperature fluctuations. The results obtained from the experiments carried out on a laboratory die casting process simulator indicate that the controller can limit the local die insert temperatures in a given band. Hence, the desired thermal pattern of the die insert becomes achievable.

Jan 1, 2006

By Xiao Caimei

The method of Substance Flow Analysis (SFA) provides a helpful tool for the study of the industrial metabolism of a certain metal within a regional level, such as copper, lead etc. In this paper the flows and inventory of cobalt in China, 2008, were traced with the STAF model, and the situations of production, fabrication and manufacturing, use and waste management in China were introduced. The result revealed that the resource of cobalt in China was so poor that a large amount of cobalt material or cobalt products needed to be imported, and there was lack of recycling of cobalt resources.0

Jan 1, 2010

By Junli Xu, Xianwei Hu, Kaiyu Xie, Liangxing Li, Zhongning Shi, Zhaowen Wang, Bingliang Gao, Aimin Liu

Al-Ti master alloys were prepared by aluminothermic reduction between the dissolved titanium dioxide and aluminum in cryolite melts at 960oC. The kinetic analysis by differential scanning calorimetry indicated that the apparent activation energy of the reaction of reducing titanium dioxide by aluminium is 22.3 kJ/mol, and the reaction order is 0.5. The products were analyzed by means of X-ray diffraction, X-ray fluorescence, scanning electron microscopy and energy dispersive spectrometer. Results from X-ray diffraction showed that the phase compositions of produced alloys are Al and Al3Ti. In addition, Al-Ti master alloys containing 2-6 mass% Ti were formed at different reduction time of 2-5h in aluminothermic reduction experiment.

Jan 1, 2015

By Lloyd Robert Nelson

The historical progression in installed electric furnace smelting capacity of some 1650 calcium, chromium, manganese, nickel and silicon ferro-alloys furnaces is reviewed. Key increases in the inherent installed electrical capacity, often achieved through uprating furnaces, are identified. Possible factors facilitating such advances are explored, including: specific process engineering and pyrometallurgical enhancements (e.g., improved control over the consistency, size and chemical form of raw materials, extents of preheating and pre-reduction delivered into the furnace; and patterns of feed distribution); furnace electrical configuration (AC or DC; immersed, submerged-, shielded- or open-arc); form of electrode (graphite, self-baking or composite); furnace configuration (circular or rectangular; closed or open and 1-, 3- or 6- electrodes); better engineering and equipment designs (e.g., high-intensity cooling) and state of furnace electrical and metallurgical control systems. A view is presented on the prevailing state of evolution of the Mega-scale in ferro-alloy smelting and opportunities for still further improvements.

Jan 1, 2014

By Zhengjie Chen, Wenhui Ma, Jijun Wu, Kuixian Wei

The gasification reactivity of PC (petroleum coke), strengthened by addition of different potassium carbonate proportions using different grinding medium, was investigated by using thermogravimetric analysis (TGA). Results showed that the gasification reactivity of PC not only increased with the increase of catalyst-loaded, but also showed the effective improvement by anhydrous alcohol. The PC was mixed with potassium carbonate [K2CO3] catalyst at 0.5%, 0.8%, 1.0% and 1.5%, and then ground wet with distilled water. The CO2-gasification rate of PC was only 77.35%, 80.55%, 84.07% and 85.88% under the gasification temperature 1100 °C and holding time 120 min, at different K2CO3 respectively. However, when the PC was ground in anhydrous alcohol at the same condition of catalyst-loading, the gasification rate of PC reached 95.43%, 96.63%, 95.50% and 95.61% at the holding time of 108 min, 101 min, 74 min and 35 min, respectively. It was shown by FTIR, SEM and EDX determinations that the anhydrous alcohol used as the grinding medium can further improve the gasification reactivity of PC when compared with the distilled water.

Jan 1, 2016

By Qing Bo

In this study, the cobalt oxide precursor was prepared in open-style reactor in the condition of high reactant concentration, and then the precursor was decomposed to obtain the cobalt oxides (Co3O4). The effects of some factors on the cobalt precipitation, the particle size and size distribution, and the micro-morphology were addressed. The factors studied include cobalt concentration, initial pH of solution, temperature and time for the reaction, the charge amount of urea, and the temperature for decomposition. It is determined that the precursor particle is in the chemical composition of Co2(OH)3Cl with fine crystalline. By calcinations under proper conditions, the mono-dispersed cobalt oxide particles were prepared with fine crystalline, about 2 µ m in particle size and regular shape in morphology.

Jan 1, 2006

By Xingjian Gao

The mechanical properties of a low carbon low alloy steel in the austenite and _-ferrite regions have been examined by thermal-tensile tests using a Gleeble-1500D system at temperatures in the range 600oC to 1300oC and at a strain rate of 10-3/s; these being the conditions that apply to the unbending operation during the continuous casting of steel. The yield strength and tensile strength of steel decreased with increasing test temperature and the embrittlement zone occurred in the temperature range 800oC to 970oC. In the embrittlement zone, the fracture surfaces and microstructures of the tensile specimens were examined by scanning electron microscope. The results showed that the cause of the embrittlement at 950oC in which the minimum %R of A was around 36% is the second phase particles precipitated along the _ grain boundary during deformation leading to inter-granular brittle fracture.

Jan 1, 2010

Based on experimental and computer simulation results from our group, we report a systematic, atomic level analysis of carbon dissolution from carbonaceous materials in molten iron. Experimental results on graphite/Fe-C-S system were obtained using carbon dissolution studies, XRD and FESEM investigations and were supplemented with Monte Carlo simulations. Three basic mechanisms, namely carbon atom dissociation rate, interfacial phenomena and mass transfer in the melt were found to be responsible for the overall dissolution process. While mass transfer in the melt is governed by the concentration gradients, melt composition and temperature; impurities present in ash play a significant role in the interfacial phenomena. For less ordered forms of carbonaceous materials, carbon atom dissociation rate depends strongly on the degree of long-range order and is an important rate controlling mechanism in the overall dissolution process. A systematic comparison of dissolution rates for a variety of coal-chars, natural and synthetic graphites has been carried out in an attempt to identify rate-controlling mechanisms. The structure of the carbonaceous material appears to be an important underlying factor in the carbon dissolution process.

Jan 1, 2003

By Nikhil Dhawan

Electronic waste (e-waste) is a collective name given to discarded electronic devices such as Television, Cellular Phones and Personal Computers. Among the heterogeneous metals present in the e-waste are the base metals: copper, aluminium, nickel, tin, zinc, iron and precious metals: gold, silver, palladium, platinum apart from several hazardous and halogens metals. Hence there is a need to recover these metals from electronic scrap by recycling and then re-use, which can meet large amount of metals demand. Hydrometallurgical processing was employed for the recovery of metals from television printed circuit board (TV PCB). Different lixiviants such as hydrochloric acid, Sulphuric acid, and nitric acid were used to understand the dissolution behavior of copper, iron and lead present in the TV PCB. Effect of increasing concentration of nitric acid was also studied. Selective recovery of tin over 95% in the form of tin oxide was precipitated. The precipitated tin oxide was identified by X-ray diffraction technique. Tin oxide of purity more than 99.9% was obtained.

Jan 1, 2009

By Pengfu Tan

A thermodynamic model has been developed to model the desilverising process of lead by the addition of zinc during lead refining, whereby silver-zinc solid solutions are formed, and floats out of the dissolved zinc/silver in the lead bath. The solubility of silver-zinc solid solutions in lead decreases with falling temperature. A number of variations and modifications of the desilverising process are modeled, and applied to a wide range of silver contents in lead bullions in the industry.

Jan 1, 2005

By Yunyan Wang

Diagrams of pc-pH for the complex ions concentration and pH value and -g- for activity coefficient and ionic strength ln±MnSOI4had been drew based on the thermodynamic principle of coordination chemistry and combined with Pitzer theory at 298.15K. The diagram of -g- indicated that -gincreased sharply from 0.0000 up to 1.2147 when I changed from 0.00 ln±MnSOIln4±MnSO4to 0.09; The increase of -gbecame slowly when I was more than 1.00 and less than 1.69; kept still when I ln±MnSOln4-g±MnSO4was more than 2.25 and less than 4.00. Diagrams of pc-pH illustrated that the minimum solubility of Mn(OH)2(s) increased with the increase of I, the pc increased from 6.5 to 5.5 when I increased from 0.00 to 4.00; The pH of the minimum solubility of Mn(OH)2(s) increased with the increase of I, the pH increased from 11.80 to 12.76 when I increased from 0.00 to 2.89, the pH kept still when I (I was less than 4.0) increased. There is single function relationship between the minimum solubility of Mn(OH)2(s) and relevant pH in different I.

Jan 1, 2010