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By A. Warczok

Smelting slags contain payable metals in a dissolved form and as mechanically entrained matte or metallic inclusions in the size range from 2 to 1000 µm. Slag cleaning requires reduction of magnetite and metal oxides and sedimentation of inclusions. Slag cleaning in an electric furnace is carried out in batch or semi-continuous mode. The strong trend for continuous slag cleaning generates the basic question about the optimal geometry of the electric furnace. Results of combined CFD, potential distribution and heat transfer modeling allowed for the determination of the fluid flow pattern and the temperature distribution in a classical, circular electric furnace as well as in a rectangular furnace. For the rectangular furnace, various length/width ratios and position of electrodes have been simulated. Analysis of key phenomena pointed out the advantages of the rectangular electric furnace over the circular furnace, particularly for continuous slag cleaning. Phenomena that have been analyzed were mass transfer, the rate of slag reduction, coalescence and settling of inclusions, all on the basis of the calculated slag flow pattern and the temperature distribution.

Jan 1, 2007

By M. M. C. Lima, L. C. S. Solimani, M. A. Quintela

Galvanized steel scrap is recycled to B OF converters where zinc escapes from the bath and is captured by the gas control system, appearing in BOF sludge. As BOF sludge contain high iron content, it could be recycled, but due to its zinc content, it is disposed in landfills. In this study techniques were evaluated for zinc layer removal from scrap by sulfuric acid leaching. The effects of coating weight, temperature, time and sulfuric acid concentration were evaluated for three different galvanized scrap. The results showed that the behavior of each galvanized scrap was different. Nevertheless zinc removal efficiency was more than 80% with low dissolved iron in the leached solution.

Jan 1, 2011

By William H. McCracken, William G. Holroyd

"The People's Republic of China could very well be considered the largest untapped mineral and metal resource in the world. The proven reserves of antimony, barite, bauxite, fluorspar, graphite, lithium, magnesite, mercury, molybdenum, phosphate, pyrite, rare earths, talc, tin, titanium, tungsten, vanadium and zinc are among the largest in the world.Any company involved in the purchase or supply of industrial raw materials has undoubtedly followed the phenomenal growth of some of the Chinese mineral commodities, where growths in production of more than 200010 have occurred during the past ten years, for commodities like barite, cement, gold, gympsum silver and talc. Others, like bauxite and phosphate, experienced production increases in one year alone of over 45%, from 1986 through 1987!A popular rationale in the United States during the past two years has been the acknowledgment by Professor David Calleo, of Johns Hopkins School of Advanced Studies, that ""America is not sinking-the rest of the world is rising"". While we recognized this rise to be that of economic power for Japan, Korea, Brazil, Taiwan and, more recently, the newly-combined Germanies, China has also successfully completed her own modern five year development binge. But with each boom there is also a bust, and the start of the 1990sfor China shows signs of economic distress. China posted a budget deficit equivalent of US$1.9 billion in 1989 coupled with official inflation at 18010. Projections for 1990 are for US$1.8 billion deficit and inflation as high as 24%. However, government spending in the first seven months of the year climbed 16.4%, outpacing an 11.6% rise in revenue. Spending increases have been related to the government policy to keep prices on domestic goods artificially low, through subsidies, and to bailout inefficient state companies."

Jan 1, 1991

By R. Loney, M. Militzer

There is a significant demand for new high strength steels with fine grain sizes for structural applications. One approach in this regard is to develop hot-rolled HSLA steels where refining the microstructure leads to increased strength levels, e.g. 700 MPa yield strength, that can be attained by suitable modifications of chemistry and processing. Here, an HSLA steel is investigated that contains 0.05wt%C-1.65wt%Mn-0.20wt%Mo¬0.07wt%Nb-0.02wt%Ti and approaches the above strength class. The ability to control and predict the mechanical properties of hot rolled steel depends strongly on the thermomechanical processes, which the steel undergoes. The final microstructure and, thus, the properties of the hot-rolled steel are a function of the austenite decomposition obtained during accelerated cooling on the run-out table and precipitation during coiling. The austenite-to-ferrite phase transformation under run-out table conditions has been investigated using a Gleeble 3500 thermomechanical simulator equipped with a dilatometer. The effects of cooling rate and initial austenite microstructure including the degree of work hardening on austenite decomposition kinetics and ferrite grain refinement have been quantified. Results show that grain refinement can be optimized by the presence of work hardened austenite and accelerated cooling. Based on the experimental results, a model is proposed to predict the transformation start temperature and the resulting ferrite grain size for run-out table cooling conditions.

Jan 1, 2004

By F. P. Hassani, Jacque Ouellet, M. Hossein

A laboratory investigation was undertaken to evaluate the effectiveness of different binding agents in a paste backfilling operation suitable to be used in a sulphide-rich environment. Different combinations of Portland cement and fly ash type C as well as ferrous slag were used as the binding agents. The unconfined compressive strength of the samples was measured for extended curing periods. The results indicate that the addition of 3% slag in the binding agent mix could produce strengths up to 0.5 MPa in the samples under investigation. For higher binding contents, the addition of Portland cement will lead to higher availability of calcium hydroxide and calcium aluminate, which are susceptible to deterioration from the phenomenon known as sulphate attack. Using slag, on the other hand, will reduce the permeability, availability of calcium hydroxide, and dilute the calcium aluminate ions reducing the susceptibility of the samples to sulphate attack. However, gypsum will form which could have the same detrimental effect on the strength of the treated matrix. Therefore, special attention must be given to the content and properties of agents used to activate the pozzolanic properties of the slag.

Jan 1, 2001

By L. Xia, B. Hart, J. Nigim, Z. Chen

"Grinding ore is an important step in the flotation process. Not only does grinding reduce particle size and liberate minerals, it also creates conditions for reactions to occur on particle surfaces that can aide or inhibit flotation. There have been numerous studies examining various grinding regiments and the effect on flotation pulp chemistry, including autogenous grinding and using media of variable composition. There have been however, few studies looking at the effect of variability in grinding media size on pulp chemistry and subsequent flotation. This study attempts to link changes in pulp chemistry in response to variations in grinding media size to flotation recovery. It uses probes mounted in the grinding chamber (pH, Eh, DO, and conductivity) to monitor pulp chemistry changes during grinding of a Cu-Zn ore. Surface chemistry analysis by ToF-SIMS was performed on sphalerite from the mill discharge. Activator and depressant species were monitored on the mineral surfaces and their presence was evaluated in the context of variability in pulp chemistry linked to differences in grinding media and its ball size.INTRODUCTIONIt has been widely recognised that not only does grinding reduce particle size and liberate minerals but the grinding environment has a large effect on the flotation of sulphide minerals. This effect is attributed to Eh change, iron hydroxide coating on surfaces, oxygen reduction, precipitation from solution and galvanic coupling (Grano, 2009). As early as 1960, it was reported that after grinding the ores in an iron mill the natural floatability of sphalerite was reduced significantly (Rey and Formanek, 1960). Kocabag and Smith (1985) studied on the industrial circuits showing that the depression of sulphides flotation in a steel mill is possibly due to the coating of iron oxidation products. Peng, Grano, Fornasiero, and Ralston (2003a, 2003b) found that iron contamination from grinding media plays a dominant role in depressing galena and chalcopyrite flotation. Huang, Grano, and Skinner (2006) reported the same observation in the flotation of arsenopyrite."

Jan 1, 2016

By James W. Cameron

DESPITE the fact that, after oxygen and silicon, aluminum is the most abundant and widely distributed element in the earth's crust, it is, commercially, a modern metal. Attempts were made by Sir Humphrey Davy and other chemists to decompose alumina, the oxide, into its elements, but with unsatisfactory results, and it was not until 1827 that Wohler succeeded for the first time in isolating the metal in pure form. Some thirty years later, commercial production of aluminum was started in a plant near Alais, France, using a process developed by Deville which was a modification of that of Wohler. It was not, however, until around 1886 that possibilities of low-cost production were realized. Hall and Heroult discovered, independently, the now famous process for extraction of aluminum by the electrolysis of alumina (Al,O,) dissolved in fused cryolite. This discovery, with its subsequent effect in reducing the price of the metal, was perhaps the greatest single factor contributing to the remarkable growth of the aluminum industry. But only in the years following the Great War did aluminum begin to attain equal importance in many fields with other non-ferrous metals. Numerous factors, political and economic, in the past decade have had a profound effect on the industrial history of the metal. At present, systematic substitution of aluminum for other base-metals is proceeding at a rapid rate in such countries as Germany and Italy with a view towards 'economic self-sufficiency'. Quite naturally, ?the economic depression started extensive research and experiment in various industries in an attempt to improve efficiencies and lower costs. Partial answers have been found in the extended use of aluminum and its alloys. Even against the background of tremendous technological advance that has marked the past fifty years, the rise of the aluminum industry must necessarily stand out conspicuously.

Jan 1, 1939

By W. van der Merwe

With the gold industry looking to process more complex ores, the online measurement and control of cyanide addition to the gold leaching circuit has become more crucial. This paper compares the two commonly employed "free" cyanide online analysis methods (amperometric and potentiometric end-point silver nitrate titration) with the common site laboratory rhodanine endpoint silver nitrate titration and ion selective electrode methods. Measurement differences between these methods are presented and discussed for cyanide solutions containing copper and zinc with varying cyanide to metal ion ratios. The resulting cyanide available to leach gold is also compared with these measurements.

Jan 1, 2011

By W. Blum

Progress made in improving the creep resistance of Mg alloys is reviewed with the emphasis on microstructural interpretation. Experimental results on the increase of creep strain with time at constant stress a measured for limited times and strains are displayed in a transparent form as creep rate-strain diagrams from which the minimum creep rate stress is safely derived. In addition, data on the thermal stress component a derived from high-precision a-reduction tests are reported. Within a simple statistical dislocation model these data allow one to quantify the relation between dislocation velocity v and a . In combination with structure evolution laws this relation serves as a basis for modeling the creep rate. New alloys have distinctly higher creep resistance than AZ91 where precipitation hardening plays a minor role. This is due to hardening by intermetallic phases which may form a continuous skeleton along the grain boundaries (e.g. Ca-alloyed AZ91) and/or submicron-sized precipitates within the grains (MRI230D, Mg-Zn-Ca alloys).

Jan 1, 2006

By G. M. Hughes

"400 cubic foot Agitair Flotation Cells are in use at Sherritt Gordon's Fox and Ruttan Mine Cu-Zn concentrators. The 4 impeller model No. 120, used at the Fox Mine Operation, appears to offer superior agitation and aeration qualities compared to the single impeller model 120A, in use at Ruttan. The advantages of the model 120 are most significant with ores of high specific gravity and coarse grind.IntroductionSherritt is using 400 cubic foot Agitair flotation machines at both the Fox and Ruttan Mine Concentrators.At the 3000 tpd, Cu-Zn Fox concentrator, 18 model 120 machines have been in operation since May, 1969.The 10000 tpd, Cu-Zn operation at Ruttan utilizes 49 model 120A machines. The plant started operation in May, 1973.The 4-impeller model 120 flotation cell has been marketed by Galigher since the early 1960's but the single impeller model 120A is relatively new.Model 120 Agitair -Cell DataThe Model 120 (Dwg. 1) has floor dimensions of 101 x 10' and a lip height of 2~ to 4 feet to provide up to 400 cubic feet of volume. This machine is shown with a froth crowder and stabilizer plates which are optional.Each motor drives two agitators. 20 HP is recommended by Galigher but 25 HP is more realistic with massive sulphides. The SG of ?ox ore is about 3. 6.The Model 120 can handle up to 600 cubic feet of air per cell at 2 psig which requires 5-6 HP at the blowers. Air volume to each impeller is controlled by a valve from a main header.During the first 3 years of operation at Fox there were few mechanical problems with the 120's."

Jan 1, 1974

By C. R. Stelck

"AbstractThe Cardium formation of northeastern British •Columbia •contains an erosional unconformity that becomes progressively more severe northward until, •at Liard river, the stratigraphic hiatus eliminates the underlying Lower •Cardium sandstone, the Kaskapau formation, and the upper Dunvegan sandstones. The area of unconformity roughly coincides with the distribution of the continental facies of the earlier Dunvegan formation. Along Wapiti river, the zone fossil Scaphites ventricosus Meek and Hayden is found in the Bad-heart member of the overlying Wapiabi shale; Scaphites :preventricosus. Cobban marks the base of the Wapiabi shale; Scaphites cf. corvensis •Cobban is found in the middle shale member of the •Cardium formation. The log of the Red-Willow No. 1 well shows close similarity to the outcrop sections south of Wapiti river. The Cardium formation is mainly late Turonian in age. Two other pre-Cardium Turonian sands of north-eastern British Columbia are named the Wartenbe and Tuskoola sands.IntroductionTHE Upper Cretaceous Cardium (Bighorn) sandstone formation of the Foothills of northeastern British Columbia carries within its formational limits an erosional unconformity. The unconformity decreases to the southeast, becoming in immediate shoreline regions, now under the plains, a minor diastem. Such diastems, or stratigraphic intervals of non-deposition, occurring in the shallow unda-zone are paralleled in the deeper portions of the unda-zone by the phenomena of sub-aqueous winnowing. '.This winnowing and re-working •at critical depths creates sand areas with porosity."

Jan 1, 1955

By H. H. Bird

Kilembe is situated in the foothills of the Ruwenzori Mountains in Uganda. Precambrian stratiform copper de-posits are currently being mined at a rate of 90,000 tons per month. Complex ore structures and variable ground conditions have led to diverse mining methods in the past. New mining areas contain more shallow-dipping, highly contorted orebodies, in heavy ground. Cut-and-fill mining will be practised in the future. The geology, mining and milling are described.

Jan 1, 1968

By Yvon T. Maurice

Under the auspices of the Federal-Provincial Uranium Reconnaissance Program, a geochemical orientation survey was undertaken in an area of uraniferous Lower Proterozoic (Aphebian) rocks near Cape Dorset in southwest Baffin Island. The main objective of this study was to establish a methodology for a future reconnaissance geochemical program using lake samples over a 300-mile Lower Proterozoic rock belt that occurs along the southern coast of Baffin Island. Mineralogical and chemical studies of known radioactive occurrences, combined with detailed sampling of secondary environment media in the vicinity of the showings. indicate that uranium is the most significant pathfinder, despite considerable enrichment of other metals in the uraniferous rocks, Significant geochemical patterns produced by uranium in lake waters and uranium in lake sediments have been obtained, but their relative usefulness depends on the distribution of carbonate bedrock, which in turn affect the bicarbonate content of lake waters. In southern Baffin Island, because of erratic variation in lake-water alkalinity, it is recommended that both water s and sediments be sampled on a routine basis. The need for lake-water acidification to prevent depletion of soluble metal ions in samples resulting from adsorption on the walls of the containers and/or suspended solid matter is discussed briefly. The base metal potential of the area was examined in some detail and found to be significant, particularly for a Lower Proterozoic gossanous formation that occurs throughout southern Baffin Island.

Jan 1, 1977

By C. R. Julian

MECHANIZATION During the last fifteen years, numerous attempts have been made to mechanize the operations of loading ore and placing till. It is to be regretted that, to date, little progress has been made in this direction. The comparative efficiency of manual labour in Spain is the factor largely responsible for the failure to cheapen costs by mechanization. The necessity for careful classification of the ore and the need for keeping all openings small also makes the problem one of difficulty. It may be of interest to describe the various attempts at mechanization that have so far been made. CONVEYORS: (1) When stoping by layout III in San Dionisio, a trial was made of transporting the filling by jigging conveyors. This method proved un-economical, as the wall building and spreading of the till could not keep pace with the delivery, with the result that the machinery was idle a great part of the shift. (2) The transport of ore from the working places to the ore-passes by jigging conveyors and belts was also tried. Although more successful than in the case of the fill, the method could not compete with that of hand tramming, principally due to the high cost of (a) maintenance caused by the abrasiveness of pyrites, and (b) labour constantly employed on re-aligning the conveyors owing to the constant settlement of the floor. In a few cases, where a sill floor was being blocked out in virgin ground, the method showed a saving. SCRAPERS: Frequent attempts at loading by scrapers have been made, but again the only success obtained has been in the blocking-out of sill floors. The principal obstacle to the successful application of scraping, other than on the sill floor, has been that the openings, which have to be small, call for a light scraper outfit, whereas, in practice, a heavy scraper and at least a 25 h.p. winch are necessary for handling satisfactorily the ore, which is heavy and which breaks somewhat blockily.

Jan 1, 1940

By J. W. Matousek

"Computer modeling of smelting processes requires internally consistent equations for calculating the compositions of mattes and slags. That is, the sum of the calculated assays must total 100%. One set of equations that satisfies this requirement for copper produced under oxidizing conditions (pSO2>one atmosphere pressure) is given by the following:%[Fe] = 62.0 – 0.775%[Cu]%[S] = 28.0 – 0.00125%[Cu]2%[O] = 10.0 – 0.225%[Cu] + 0.00125 %[Cu]2Mattes containing nickel in appreciable quantities do not have the defined “white metal” end point of approximately 80 percent copper and 20 percent sulphur that is found in the copper system during the converting process. The above equations, however, are readily extended to nickel and nickel/copper mattes for any desired end product composition."

Jan 1, 1996

By Alain Simard, Sylvain Lacroix, Louis-Martin Dubé, Pierre Pilote

"The Harricana-Turgeon belt (HTB) is a poorly known volcano sedimentary belt in the NW part of the Abitibi Sub-province; it includes the Matagami, Joutel, Brouillan and Casa-Berardi mining districts. The HTB is dominated by volcanic rocks, which covers 65% of its surface area, followed by sedimentary (18%) and plutonic (17%) rocks. It is also transected by numerous deformation zones located either at the contacts of volcano-sedimentary units and granitoid bodies or cross-cutting them. A preliminary geological synthesis shows that mineral deposits are associated with certain regional geologic elements.The volcano-sedimentary units are grouped here into twelve band-shaped lithotectonic domains, most of which extend for more than 150 km E-Win the HTB. Each domain is defined by lithologies and facies associations, and gradiometric and electromagnetic signatures.Eight domains are composed of basaltic or basaltic to komatiitic associations, interlayered with thin pelagic sediments, representing sub-marine lava plains. Two domains are composed of basaltic to rhyolitic associations that are interpreted as volcanic arcs formed by one or several central volcanic complexes.The sedimentary rocks are grouped into two lithotectonic domains. Each is composed of rhythmic sequences of turbiditic sandstone- siltstone-shale, Algoma-type banded iron formations and conglomerates bearing plutonic and volcanic pebbles. These three facies come partly from mass flow at the bottom of a slope in a moderately deep marine environment. In each domain, a conglomerate sandstone- siltstone sequence, containing poly genetic pebbles of local provenance, is similar to Timiskaming-type alluvial deposits.The nineteen granitoids, found within the HTB and at its border, belong to numerous petrographic suites, and have been grouped into four structural families: pre-tectonic, pre- to early-tectonic, syn- to late-tectonic, and late- to post- tectonic. The pre- to early-tectonic plutons are presumed to be sub-volcanic and are generaly associated with the volcanism of central complexes.The HTB mineral resources consist essentially of polymetallic (Cu-Zn-Ag-Au) and gold (Au-Ag) deposits. The polymetallic deposits are located exclusively in the two lithotectonic domains composed of basaltic to rhyolitic associations (Matagami-Brouillan and Joutel Raymond). All gold deposits are associated with deformation zones superimposed on lithotectonic domain contacts and highlighted by graphitic units. Most of the deposits are hosted in the Casa-Berardi and Douay deformationzones, located at the contact of the Cartwright basaltic to komatiitic domain and the Taibi sedimentary domain"

Jan 1, 1990

By F. Rivard, M. G. Drouet, W. S. Ruff, P. Carabin

"In both the hot rotary-salt-furnace (RSF) treatment of aluminum dross and the cold ball-millsieving (BMS) treatment of zinc dross, enormous amounts of energy and recoverable metal are wasted and large amounts of greenhouse gas are produced. Such wastes and the environment pollution could be avoided by using the DROSRITE PLUS™ technology. Economic and GHG production comparisons between the presently used industrial treatment processes and DROSRITE PLUS™, supported by over one hundred tests conducted in Canada, the US and Europe, are presented. The savings, with DROSRITE PLUS™, would be about $191 and $418 per MT of aluminum and zinc dross, respectively.INTRODUCTIONDross is a material, which forms on the surface of molten non-ferrous metal, such as aluminum or zinc, during melting, metal holding and handling operations when the molten metal is in contact with a reactive atmosphere. Dross normally consists of metal oxides entraining a considerable quantity of molten free (unreacted) metal, and for economic reasons it is desirable to extract the free metal before discarding the residue. In the case of aluminum dross, recovery of the metal is usually carried out by treating the dross in a furnace at a high temperature (Peterson et al., 2002). By contrast, cold zinc dross is crushed in a ball mill followed by sieving to separate the coarse metal portion from the fine oxide residue.The conventional aluminum dross treatment process, using gas or oil-heated rotary salt furnaces (RSF), is thermally inefficient and environmentally unacceptable because of the salt slag and CO2 produced from the combustion of fossil fuels. In the past several years, a number of salt-free processes have been developed and some of these have found limited commercial use (Gripenberg et al., 1994; Lavoie et al., 1990). In all these dross treatment processes, heating of the cold dross in a rotary furnace requires an external energy input that varies between 375 and 2,500 kWh per (metric) tonne of dross. Molten metal separated during processing of the heated dross is tapped, and the remaining solid residue is discharged from the furnace."

Jan 1, 2012

By W. A. Gow, H. H. McGreedy

It is believed that many of the problems encountered in the operation of gold cyanidation plants are difficult to resolve due to the lack of sufficient and reliable in-formation regarding the variations and actual values of operating variables at any given time. The application of instruments to monitor the more important variables in the cyanidation process should result in more efficient plant operation and a better understanding of the process. The use of pH and conductivity sensing devices for alkalinity measurements, a monitor to determine the dissolved oxygen content of plant solutions, a continuous cyanide titrator and sonic control of grinding circuits are discussed. Although the discussion is oriented toward the cyanide process, much of the paper is applicable to other ore treatment operations.

Jan 1, 1966

By K. Hasselwander, K. Knabel

"A significant area of Outotec’s business involves fluidized bed roasting. With several decades of experience, more than 300 reference plants and strong R&D capabilities, the company provides several industries with optimum processing solutions. Applications include oxidation and sulfation of sulfides found in copper, pyrite and zinc concentrates. Gold production and de-arsenifying roasting are also within this scope. This paper describes the latest furnace developments and includes novel trends. Moreover, hot and wet gas cleaning systems are examined focusing on unit operations related to the removal of components such as dust, SO2 for sulfuric acid production, fumes, halides, Hg, hydrocarbons, nitrous oxides and metals.INTRODUCTIONGenerally, when defining roasting processes, it can be stated that the respective primary pyrometallurgical reaction is exothermic, of gas-solid nature and relates to a value solid product. These processes are a key focus within Outotec’s scope and include: (i) dead roasting (ii) sulfating roasting (iii) partial de-arsenifying roasting and (iv) two-stage, de-arsenifying roasting.Dead roasting involves the oxidation of a given sulfide, thus allowing for a subsequent leaching process, and has been applied to producing ZnO. Dead roasting of pyrite has also been extensively utilized with a primary goal of producing sulfuric acid. In contrast, sulfating roasting involves converting a sulfide to its sulfate, enabling a selective sulfation of components, such as Cu or Co, and their separation from ferrous components during leaching (produced sulfates are soluble). Partial roasting involves partially oxidating the metal sulfide to its oxide with the simultaneous production of gaseous As4O6, which is handled during gas cleaning. The solid product, containing hardly any As, is rich in S and can be fed to a respective smelter (e.g. in the case of Cu). Alternatively, if the production of oxide is required, a dead roasting step is added after the partial roasting step, with the overall process considered as two-stage roasting."

Jan 1, 2012

By G. E. Veins

A three-phase, continuously-operated, 250 kv.a. electric smelting furnace has been installed at the Mines Branch, Department of Mines and Technical Surveys, Ottawa, for the experimental treatment of ores and by-products of interest to the Canadian mining, metallurgical, and chemical industries. In the operation of this furnace particular emphasis is placed on the accumulation of quantitative data which will be useful in determining the most suitable smelting technique and the nature of the products, and in arriving at preliminary conclusions regarding the cast of power and electrodes. The results obtained in the experimental smelting of iron, manganese-iron, titanium- iron, nickel, and chromiumiron ores, and of a number of industrial by-products, clearly show the value of such treatment for materials of this type.

Jan 1, 1957