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By Ing. R. Geutskens

Zinc-bearing dust from blast furnace gas-scrubbing operation is a well known environmental health problem in the iron and steel industry. Hoogovens IJmuiden (The Netherlands) developed processes to solve this problem. 90% of the zinc is concentrated in 25% of the dust (the fine particle fraction) by means of slurry-hydrocyclonage. The resulting fine particle fraction is treated in a pressure leaching process. Hydrochloric waste pickle liquors have been used as a leaching liquor. By creating optimal leaching conditions more than 98% of the zinc is brought into an acid' solution, whereas nearly all the iron remains in the residue. The zinc can be separated selectively from the solution. The residue can be reused in the blast furnace (via the sintering plant). In the article information is given about the research work and -results of the pressure leaching process as well as the possibilities of the process for solving comparible problems.

Jan 1, 1990

By Akira Yazawa

The similarities and differences in copper, nickel and lead smelting processes are discussed based on the sulfur-oxygen chemical potential diagrams and the free energy minimization assessments using a thermodynamic software. The prominent features of copper smelting are ascribable to the fact that copper has a strong affinity for sulfur but weak for oxygen and the liquid phase immiscibility between Cu and Cu2S. During the oxidation of sulfides, nickel metal is not stable except at temperatures higher than 1500°C, well miscible with its sulfide, and is oxidized more easily than copper. Metallic lead looks as stable as copper during the oxidation of the concentrate but Pb and PbS. are much more miscible with each other and the vaporization loss is considerable. In the reductive smelting of oxides, the effects of oxygen potential and temperature on the copper contents in slag are not significant due to the monovalent character of copper and the reduction of copper content in slag is not easy in practice. The effect of the slag compositions on the oxidic metal contents of slag is much more significant for lead than either copper or nickel. Due to the immiscible nature between Pb and Fe, high grade lead bullion is easily obtained and lead is more tolerant to impurities.

Jan 1, 1998

By J. Fraser Forbes

"The meaning of the term ""process control"" has evolved significantly since its widespread use began in the manufacturing industries in the 1940s. Further, the scope of process control applications has drastically increased both in terms of the breadth of industries using process automation technologies and the vertical integration of these technologies within a single industry. This evolution and integration of process control technologies within the manufacturing industries has proceeded to such an extent that process automation is an integral part of modern business practices.This paper will examine the current status of process control technology from simple process regulation through process performance optimization to business planning. Each layer of the operations automation hierarchy will be discussed both in. terms of the current state-of-the-art and the directions in which these technologies are evolving. The key tools and tasks necessary for success at every level of the automation hierarchy will be introduced. Finally, the critical challenges that must be faced in accomplishing the goal of complete Computer Integrated Manufacturing (CIM) will be described.Finally, although this paper addresses issues of practical importance to any manufacturing company, the discussions will be framed in terms of the particular challenges facing and the opportunities available within the materials manufacturing industries."

Jan 1, 2000

By Lawrence L. Brown

As part of the Federal effort to help maintain an adequate supply of fertilizer materials, the Bureau of Mines conducted research to characterize complex low-grade Michigan phosphate materials and to devise methods for recovering fertilizer-grade phosphate concentrates. The rock is from middle Precambrian sedimentary formations in the Marquette Range located in the central part of the Upper Peninsula of Michigan. Occurrence of phosphate-bearing sediments in Precambrian rocks is rare. This deposit, containing 12 to 15 pct P2O5 is believed to be the richest Precambrian phosphate deposit in the United States. Petrographic examination showed that the conglomeritic rock contains crystalline apatite both in "black pebbles" and in quartz matrix. Attrition scrubbing and sizing tests showed that there is no tendency for phosphate to concentrate in any of the sized fractions. In beneficiation tests, which included grinding to minus 325 mesh followed by phosphate mineral flotation using a fatty acid-fuel oil collector, a phosphate concentrate was obtained that had a grade of 30 pet P2O5 and a P2O5 recovery of 72 pct. This concentrate should be suitable for fertilizer manufacture.

Jan 1, 1982

By S. K. Wu, Ray Y. Lin, Sunil Annaji

Infrared joining of TiAI using aluminum foils as the filler material was investigated at temperatures between 1050 °C and 1350 °C in a flowing argon environment for times varying between 15 and 60 seconds. Using aluminum foils, the attempt was to form the Al3Ti phase in the joint as a result of reaction between Al and TiAI at temperatures above the melting point of Al. It has been found based on X-ray diffraction and TEM analysis that, Al3Ti, indeed is the product of infrared joining of TiAI using Al as the joining alloy. Al3 Ti was detected even in the joint processed at 1050 °C for only 15 seconds. Since the aluminum foil used in this study contains 27 at% Si, the t 2 phase in the Ti-Al-Si ternary system is believed to have also formed at the joint/base TiAI interface. Cross sectional studies on the joined specimens have shown different degrees of reaction depending on the temperature and time of joining. Micro hardness evaluations across the joint show that the hardness near the center of the joint is typically smaller than that near the joint edge next to the base material. However, as the joining temperature and time increase, the increment of the hardness at the center of the joint is faster than that around the periphery of the joint.

Jan 1, 1996

By N. Voennann

Stillwater Mining Company operates an electric furnace at its smelter in Columbus, Montana to treat a Ni-Cu-platinum group metal concentrate along with secondary PGM bearing materials. Hatch Associates has designed several improvements to this furnace, which was originally built by others. Implementation of these relatively low cost improvements has resulted in substantial increases in furnace availability and capacity, along with reduced unit costs. ? The improvements included: ? Installation of water-cooled copper cooling elements to stabilize refractory wear and increase furnace life.- ? Improved furnace 'bindings, to enhance the furnace's structural integrity by improving the contact between the refractory and cooling elements, and by promoting tight brick joints resistant to matte or slag leaks. ? Adjustment of the electrode regulator to allow higher furnace power levels. ? Installation of an automated air-slide (aeration conveyor) feed system to evenly distribute the furnace feed in an insulating layer on the bath surface. This "black-top" practice reduces unit energy costs and makes available additional smelting capacity.- ? Electrode seals to reduce ingress of air that absorbs heat before exiting the furnace in the off-gas stream. The saved energy can be used to smelt additional concentrate. This paper describes the above furnace modifications, and the benefits derived from their implementation.

Jan 1, 1998

At its Copper Cliff Smelter, Inco Limited processes a bulk copper-nickel concentrate in two Inco oxygen flash furnaces, The furnace matte is converted to low iron matte for further processing, and the molten converter slag is recycled to the flash furnaces. The flash furnace slag is discarded. Natural gas or coke supplies a minor proportion of the process heat requirements, thus limiting the flash furnace matte grade to the target 45% CuNiCo. Coke addition to the furnace offers a potential means of establishing a reducing barrier on the surface of the molten bath. Such a practice would be conducive to producing sulfur deficient (partially metallized) matte. At the same iron content, the iron activity of sulfur deficient matte is higher than that of regular matte. A supernatant coke barrier could, therefore, be expected to lead to higher nickel and cobalt recoveries, reduction or even elimination of magnetite furnace bottom build-up and increased sulfur elimination as S02 in the flash furnace. Preliminary experiments were conducted in a miniplant flash furnace to investigate the effect on process metallurgy of the suggested modified scheme. This paper presents the experimental results and discusses key aspects of the possible operation of the Inco flash furnace with a coke barrier separating the freeboard from the molten bath.

Jan 1, 2003

By Tao Zeng, Jianchao Li, Chang Jie, Jieyu Zhang, Jifang Xu, Kuochih Chou

"The densities of the selected quaternary Ca0-5%Mg0-Alz03-Si02 slag with low silica were measured by the Archimedean method in a wide temperature range from l 723K to 1823K. Slag compositions were chosen based on five different levels of Si02 content between 0.00 pct and 11.40 pct. The MgO content was equaled to 5.00 pct. The mass ratio of CaO/Alz03 was varied from 0.67 to 2.14. The effects of temperature, Ca0/Alz03 ratio and optical basicity were studied. It is shown that density decrease approximately linearly with an increase in temperature. With the same Si02 content, the density decreases with increasing of CaO/Alz03 ratio and optical basicity. Based on the experimental data as the boundary of the homogenous phase region predicated by F ACTSAGE software, the mass triangle model is used to calculate the density of selected limited homogenous phase region. The results showed that the mass triangle model is working well.IntroductionIt is of great importance to measure density of slag melt not only to the theory research for melt, which that is directly amenable to the structure correlations of molten slags, but also to the industrial application. Many metallurgy phenomena such as inclusion formation in molten melt and its removing, slag foaming, slag-metal reaction are closely related to the density of slag. Density is also required to estimate other fundamental properties, like surface tension, viscosity, and thermal conductivity from thermal diffusivity so that a relatively complete picture in regard to the behavior of high-temperature molten oxides could be made."

Jan 1, 2013

By Mikiya Tanaka

This paper outlines our attempt to establish a recycle process of nickel in the spent baths and waste rinse water of electroless nickel plating plants using solvent extraction and solvent-impregnated support, Solvent extraction studies of nickel from actual spent baths revealed that (i) nickel is efficiently extracted by a hydroxyoxime extractant such as LIX84I at a pH greater than 6 and is readily stripped with sulfuric acid, and (ii) the mixtures of LIX63 and acidic organophosphorus extractants (D2ERP A, PC88A, and Cyanex 272) enhanee the nickel extraction efficiency to a sufficient degree without pH adjustment, but at the same time, reduce the stripping efficiency. The application of acidic organophosphorus extractants to selectively remove impurity metal ions (iron and zinc) from a real spent bath before extracting nickel lead to the finding that PC88A and Cyanex 272 effectively remove iron and zinc without pH adjustment leaving nickel in the raffinate. The removal of nickel from the waste rinse water was also studied. Solvent-impregnated supports with a macroporous resin and oil sorbents made of natural kapok fiber and synthetic fiber as supports were applied using D2EHPA and LIX860 as the extractants. During the batch operation, nickel is removed with a high efficiency without pH adjustment. During the column operation, however, the effective removal is hindered by (i) the dissolution of the nickel-D2EHPA complex into the aqueous phase in the high loading region, and (ii) the slow removal rate of the LIX860-impregnated support.

Jan 1, 2003

By Derek J. Fray

Electric arc furnace dusts, especially those containing zinc ferrite, are notoriously difficult to process to give valuable products and non-toxic residues. The ideal process would remove and recover the toxic non-ferrous metals as pure metals, of commercial value, and non-toxic residue which can be used as a raw material in the steel industry. From an examination of the thermodynamics of the oxides and chlorides of the various elements in the dust, it is apparent that the chlorides of the toxic non-ferrous elements are more stable than the oxides while the reverse applies to the ferrous elements. This offers the opportunity for a complete separation of the zinc, lead and cadmium from the iron oxide. Results are presented for the chlorination of electric arc furnace dusts under oxidising conditions and the subsequent treatment of the chlorides to recover the pure metals and chlorine which can be recycled back to the reactor.

Jan 1, 1994

By Rolf R. von Oppenfeld

Onsite hazardous waste processors often find obtaining a Treatment Storage and Disposal (TSD) permit one of their first major challenges. Some processors may spend the time and money required by the permitting process, only to find out later that a permit was not necessary. This paper will present and analyze four strategies that processors may use to avoid obtaining a TSD permit. Some facilities will be able to remove their waste streams from RCRA's oversight by ensuring the material is not "hazardous" waste. Parties that treat waste while it is in process may be able to avoid generating "waste" altogether. Certain treatment facilities have been specifically exempted by EPA. Finally, treatment of waste while it is in generator storage tanks may be allowed without a RCRA TSD permit. Hazardous waste point of generation, an important determination relating to these strategies, will also be discussed. Generators and processors will find this paper useful when evaluating their permit exemption potential

Jan 1, 1996

By Mojtaba Ahmadiantehrani

A previous study showed that up to 80% gold extraction could be obtained with 160 lbs/ton hypochlorite consumption at ambient temperature from a low grade Carlin-type carbonaceous ore. Crushing the ore to a finer size and agglomerating with cement decreases hypochlorite consumption by 60%; while, agglomeration and curing the cement-ore mixture with hypochlorite solution has no significant effect on total gold extraction. The high hypochlorite consumption is due to oxygen depletion as the solution percolates through the column, i.e., oxidation of gangue materials. These side reactions are reduced at sub-ambient temperatures resulting in a substantial further decrease in hypochlorite consumption. The optimum temperature range and additional reduction of hypochlorite consumption by introducing the reagent into the column at different elevations will be discussed.

Jan 1, 1992

By Charles L. Richman

The effect of the addition of Silver Sulfide on the rate of Chalcopyrite (CP) of Sulfuric acid (H2SD4 leaching is discussed, Although Ag2S in an expensive addition, a theoretical explanation of it's use will aid in the development of a economic substitution. We have used cyclic voltammography to show the presence reaction species at different potentials. Cyclic Voltammography maps the surface reaction current peaks on CP, to regions on the CP Phorbaix diagram. AC Electro-lmpedance spectroscopy (EIS) models the surface impedance properties, which control the rate of electron and ion transfer, and the surface kinetic reactions, with and with out light. EIS and other measurements show that AgCuS u Photo-reactive material- The EIS results are compared with the SEM and EDXA results to show the presence of diffusion pores, and diffusion controlled reactions during CP leaching without the addition of silver sulfate. We hypothesize that AgCuS is an ionic conductor like Ag2S. EIS shows an imposed negative leaching rate greatly. Our theory shows how the formation of Silver Copper (1) sulfide layer at open circuit potential gives an effect similar to negative potential, that is enhanced with illumination. We verify that AgCuAS is an N-type semiconductor that forms a diode type junction with the electrolyte with the Mott-Schoottly relation.

Jan 1, 2001

By Y. Yang, S. Peelman, J. Sietsma, Z. H. I. Sun

The rare earth elements (REEs) present in the Kiruna iron ore mine tailings are being considered as a new REE resource for the EU. These tailings, after beneficiation, contain approximately 5000 ppm of rare earths, concentrated in apatite and monazite minerals. To economically extract the REEs from these tailings the phosphorous contained within the apatite must also be extracted and the waste production of the process should be minimal. To achieve the extraction of REEs and phosphorous HCl and HNO3 were investigated as possible leaching agents. Based on the results a leaching process using HNO3 is proposed. This process produces H3PO4 from the apatite while simultaneously dissolving the REEs. The resulting leach liquor is then cooled to remove the unwanted Ca as Ca(NO3)2. Analysis of the leach liquor reveals extraction ratios of between 75% and 100% for the heavy REE (e.g. Y, Eu, Dy, …) and below 40% from the light REEs (i.e. Ce, La). Full phosphorous extraction was also achieved.

Jan 1, 2016

By T. Ueno

Naoshima Smelter & Refinery of Mitsubishi Materials Crop. commissioned a new Mitsubishi continuous copper smelter in May 1991. Process offgas volume of the conventional reverberatory furnace line, one of the previous smelters having been shut down, was very large and thus two acid plants had been operated. It was expected that the offgas volume would be reduced at the new smelter to about a half of the sum of those from previous two 1 smelters and the sulfur dioxide strength would be increased. So various alternatives were studied to minimize the operation cost. And it was decided to utilize both of the plants with minor modifications by diluting the gas either with air or with dilute gases. The acid plants now receive offgases from the new copper smelter, a sintering machine of a lead smelter and a decomposer of waste acid. The paper discusses plant design, operation, improvements and modifications realized in relation with the retrofitting of the copper smelter.

Jan 1, 1992

By W. G. Davenport

This chapter demonstrates how our matrices can be used for controlling a flash furnace. Specifically, it shows how we can determine the adjustments in industrial oxygen, air, oil and flux input rates that will; (a) correctly alter product temperatures and compositions to newly targeted values (b), maintain set-point product temperatures and compositions with varying feed compositions and feed rates. It also discusses corrective actions that might be taken when furnace temperature and matte grade unexpectedly change.

Jan 1, 2001

By J. S. Pitsillos

A new furnace tapping technique involving the simulation of a control valve at the exit to a furnace is being investigated. The purpose of this new tapping technique is to regulate the flowrate of liquid furnace products( slags, metals and mattes). Numerical modelling and experimental work has been carried out on tapping of slags leaving a SIROSMELT reactor and the results found to be in good agreement. Numerical modelling has also enabled prediction of the important industrial conditions for the onset of blockage from the shape of the pressure versus flowrate curves. Slag launder experiments have been carried out and a one-dimensional heat transfer model was used to evaluate the effectiveness of launder covers and different coolants. From the experimental results and mathematical model some launder design guidelines such as inclination angle, covers and coolants have been developed.

Jan 1, 1991

By N. Tsuchida

Sumitomo Metal Mining Co. Ltd. (SMMC) is currently developing the flowsheet to treat stockpiled limonite, a type of laterite ore, at Rio Tuba on southern Palawan Island, Philippines. The new plant will be commissioned at the end of 2004. Rio Tuba Nickel Mining Corporation (RTNMC) has been mining saprolite since 1977, and the limonite ore located above the saprolite ore body has been stockpiled separately according to nickel and magnesium content. Ore from these stockpiles will be blended and used for the operation. The annual production of nickel will be 10,000 metric tons for the next twenty years. The proposed process consists of ore preparation, high pressure acid leach (HPAL), counter- current decantation wash, impurity removal and sulfide precipitation. Precipitated mixed sulfide will be processed to electrolytic nickel by the Matte Chlorine Leach Electrowinning (MCLE) process at Niihama, Japan. SMMC has established new technologies during the process development, such as zinc removal and sulfide precipitation. Applying this technology, preferential removal of zinc can be achieved by hydrogen sulfide gas with negligible loss of nickel. Precipitation of nickel by hydrogen sulfide gas is carried out at low temperature. Slow kinetics is selected for control of the particle size of the precipitated mixed sulfide. Keywords: HPAL, Zinc Removal, MS Production

Jan 1, 2004

By N. S. Raghavendran

Based on the weld pool length and width calculations due to an empirical model (1) for submerged arc weld metal, an elegant quantitative definition of tandem submerged arc welding is established. On the basis of this theoretical consideration optimum welding parameters for joining 25 mm thick low carbon steel plate in two passes by tandem wire submerged arc welding have been experimentally found out. An assessment of the metallurgical quality of weld metal and the dependence of mechanical propenies on pool overlap has been made. Also the solution of Rosenthal (2) etc. for a moving point source of welding, which was used as a guide line in formulating the empirical model for the calculations of weld pool dimensions, is compared with the solution of empirical model for submerged arc weld pool dimensions.

Jan 1, 1990

By A. V. Reddy, C. Beckermann

"The DC continuous casting of a grain refined AI-4.5%Cu round ingot with realistic boundary conditions is numerically simulated. Of particular interest are the effects of the transport of free solid in the form of equiaxed grains on the macro segregation patterns and the final grain size distribution. The study uses a previously developed two-phase model that incorporates descriptions of heat transfer, solute redistribution, melt convection, and solid transport on the system scale with microscopic models of solutal undercooling, microsegregation and grain impingement. The numerical results indicate that grain transport inhibits the formation of inverse segregation in the ingot shell and promotes negative centerline segregation. This is explained by the reduction in the solid coherency next to the mold and the advection of solute-lean grains towards the centerline. Comparisons with the experiments of Finn et al. [5] illustrate the need for considerable improvements in the model. IntroductionMacrosegregation continues to be one of the concerns in DC continuous casting of aluminum ingots. The variation in composition over the ingot cross section results in the need to adjust alloy composition in order to meet mechanical property specifications in finished products. The extent of macrosegregation is greatly affected by the casting conditions, such as casting speed, superheat, cooling rate, mold size, alloy composition, and grain refining practices. Thus, it is of great interest to develop a comprehensive mathematical model to simulate the casting process, enabling the selection of conditions that minimize macrosegregation while maintaining a high productivity."

Jan 1, 1994