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By Ronald B. DeDiemar

This paper will present the intrinsic factors of a cone crusher that affect performance, develop and define an ideal feed gradation for a cone crusher and, finally, bring out an important new development in computer design of crushing chambers and show an ability to predict crusher performance without trial-and-error methods.

Jan 1, 1979

By R. A. Hemstock

"OIL EXPLORATION in Western Canada has produced outstanding results in the past few years. From such successes as Leduc and Redwater on the western plains, oilmen are now moving north in the ever-widening search for oil. They are reaching new frontiers and meeting new problems presented by this vast hinterland.One of the least known but most troublesome phenomena which will be encountered is permafrost. This term relates to a thickness of soil or other superficial deposit, or even of bed-rock at variable depths beneath the surface, in which a temperature below freezing has continually existed .for a long time. This permanently frozen ground affects, in many ways, oil exploration and exploitation. Seismic records are changed, pipe lines cannot easily be ditched into the ground, formation of wax is speeded-up in tubing and pipe lines, roads are difficult to build, and foundations of buildings and even of drilling 'rigs may require entirely new methods of construction.Permafrost underlies roughly one-fifth of the entire 'land surface of the world. It covers the northerly portions of Eurasia and North America. In the area that we are here concerned with, the southern boundary of permafrost extends south of east from about latitude 59°N. on the Pacific coast across the Rocky mountains, through Great Slave and Athabasca lakes, to cape Henrietta Maria, at the junction of Hudson bay and James bay (see Figure 1). Geologists generally agree that permafrost first appeared in the Pleistocene or Ice Age as the result of abnormal ground freezing."

Jan 1, 1952

By M Reza Afshar

In this work a mathematical model was developed to study the effect of electromagnetic force on the magnesium melt containing nonmetallic inclusion in an electrical isolated channel. The electromagnetic force exerted on the inclusion induced by DC current field was calculated. A three dimensional turbulent flow equations were solved numerically to compute the velocity field within the channel. On the basis of computed velocity and magnetic fields, the trajectories of inclusions were calculated using the equations of motion for inclusions. Parametric studies were carried out to evaluate the effect of various parameters such as current density, channel diameter and particle density on the removal efficiency of inclusions from magnesium melts.

Jan 1, 2004

By Y. Chengxian

Many factors about the HIC (hydrogen-induced cracking) resistance of pipelines are discussed in this paper. The main factors that influence the ability of HIC are environmental and material factors. The chemical compositions, non-metal inclusions and microstructure are discussed in detail, while a group of tests on HIC resistance are done according to varying C, S, Mn and P contents in pipeline steels, different experiment time and different strength to the coupon. It is concluded that decreasing the amount of C and S can obtain good HIC resistance; the test time has an effect on the different microstructure of X70; microstructure is the most sensitive factor for the initiation processes of HIC.

Jan 1, 2005

By A. Demers, M. Chapman, N. Reynier, R. Lastra, M. Courchesne, C. Laviolette

Historic medical isotope production at Canadian Nuclear Laboratories (CNL) in Chalk River involved the dissolution of irradiated isotope targets prior to extraction of Mo-99. This process generated liquid waste that was cemented in 5-gallon containers and transferred to an outdoor waste-management facility for intermediate storage. Research was undertaken to develop an innovative method for uranium, mercury and cesium recovery from the radioactive cemented waste (RCW). Regulations prohibit the removal of active radioactive waste from the Chalk River facility. Thus, CanmetMINING produced surrogate material following the same procedures and conditions to those used at CNL. The selective recovery of the uranium from the surrogate radioactive cemented waste (SRCW) could offer CNL more disposition options for the resulting wastes. Leaching tests were performed using four different SRCW at 1 kg scale. Different conditions, operating parameters, and the presence of plastic and corrosion products were evaluated on solubilization. The research investigated the use of potassium iodide with the sulphuric acid leach to increase metals recovery. Iodine improves the solubilisation of metals and the U dissolution reached 99%. The increase of leaching time reduces the U solubilization due to silica gel formation. Therefore, it will be important to control leaching time to avoid the loss of U during the pilot scale experiments. For Hg, the solubilization ranged from 60 to 80% due to the presence of metallic mercury and mercury sulphide found in SRCW cured at 60°C and/or aged for 30 months. Ion exchange (IX) was found the best method to separate the uranium from the impurities and produce a purified and concentrated uranium solution suitable for yielding a uranium product (yellow cake).

Jan 1, 2020

By R. Wirth, B. Orberger, C. Wagner, A. Tudryn, B. Baptiste, S. Miska, Université Paris-Sud

Banded iron formations (BIFs) comprise complex textures and mineralogy, which result from fluid-rock interactions related to high and low temperature alteration. The initial iron oxy hydroxide mineralogy and associated phases such as carbonates, quartz, apatite and phyllosilicates were transformed leading to an upgrading of these BIFs into the world’s largest source of iron ore. In low-grade BIFs, a large part of the iron is related to micro- and nano- metric iron-bearing inclusions within micrometric quartz and/or carbonates (mainly dolomite). We studied laminated jaspilitic BIF samples from a drill core containing 26.71 wt.% total iron, 0.2 wt.% SiO2, 0.32 wt.% MnO, 15.46 wt.% MgO, 22.32 wt.% CaO, 0.09 wt.% P2O5, < 0.05 wt.% Al2O3, 0.15 wt.% H2O and 34.08 wt.% CO2 (Aguas Claras Mine, Quadrilatero Ferrifero, Brazil). Bright rose coloured dolomite and quartz bands alternate with massive specular hematite bands. Raman spectroscopy, X-ray diffraction and FIB-TEM analyses reveal that the micro- and nanometric inclusions in dolomite are mainly hematite and minor goethite, partly occurring as clusters in voids. Curie Balance analyses were carried out at different heating steps and temperatures on whole rock samples and a synthetic mix of decarbonated sample and pure dolomite. X-ray diffraction on the products of the heating experiments shows that that hematite is stable and new phases: magnesioferrite (MgFe2O4), lime (CaO), periclase (MgO), portlandite (Ca(OH)2) and srebrodoskite (Ca2Fe2O5) were formed between 680°C and 920°C. These finding gives hints to optimizing the beneficiation process, as the presence of hydroxyl ions bearing goethite micro- and nanoinclusions lowers the sintering temperature. Prior separation of coarse hematite and barren dolomite and quartz, followed by lower temperature sintering of the inclusionbearing dolomite/quartz leads to transformations into phases with higher magnetic susceptibilities (such as hematite and magnesioferrite). The entire Fe and Fe/Mg oxide feed (the priorly separated fraction added to the sintered fraction) can then pass through wet-high intensity magnetic separation after crushing.

Jan 1, 2016

By Dale Verran, Jared Orynik, Chad Sorba, David Bronkhorst

Denison Mines Corp. (“Denison”) has a 90% interest in the Wheeler River Uranium Project (“Wheeler River”) located along the eastern edge of the Athabasca Basin in northern Saskatchewan between the Key Lake mill and the McArthur River uranium mine. The project is host to the high-grade Phoenix and Gryphon uranium deposits, discovered by Denison in 2008 and 2014 respectively, which include combined Indicated Mineral Resources of 132.1 million pounds U3O8 (1,809,000 tonnes at an average grade of 3.3% U3O8). The Pre-Feasibility Study (“PFS”), completed in accordance with NI 43-101 in September 2018, is highlighted by the selection of the In-Situ Recovery (“ISR”) mining method for the development of the Phoenix deposit, with an estimated average operating cost of $4.33 (US$3.33) per pound U3O8. Phoenix is the highest-grade undeveloped uranium deposit known globally, including Indicated Mineral Resources of 166,000 tonnes at 19.1% U3O8 for 70.2 million pounds U3O8. The paper aims to provide a summary of Wheeler River and an overview of the proposed development of the Phoenix and Gryphon deposits according to the PFS completed for the Project. Further details regarding the PFS, including additional scientific and technical information are described in greater detail in the NI 43-101 Technical Report titled "Pre-Feasibility Study for the Wheeler River Uranium Project, Saskatchewan, Canada" dated October 30, 2018 with an effective date of September 24, 2018. A copy of this report is available on Denison's website and under its profile on SEDAR at www.sedar.com and on EDGAR at www.sec.gov/edgar.shtml.

Jan 1, 2020

By G. C. Lipsyy

ALL mineral production? of Can11.da is transported in a mine car at some stage during its extraction. There are as many types and varieties of mine cars as there are of mines. Many of the cars in use were developed in the blacksmith shop. Others were designed by engineers and improved by the mine foremen and the mechanics. Every mine car has the ideas of miner, blacksmith, mechanic, and engineer incorporated in it. Many of these ideas are not generally known. This paper was written to make at least some of this information available to the mining industry. In drawings, tables, and notes, it gives all the important details pertaining to the cars. It .does not recommend any particular type of car for any particular piece of work, nor does it present drawings from which a car can be built. It gives the engineer or master mechanic information on many cars which he can apply to his own particular problems. It is hoped that this information will be of use to mine operators. If a few new ideas are conceived as a result of the paper, the author will feel that the effort of compiling it has been worth while. In order to obtain the data for the preparation of the paper, a questionnaire, copy of which is here reproduced, was sent to all the operating mining companies in Canada. An accompanying letter briefly explained the purpose of the paper and asked for co-operation in furnishing as complete information as possible.

Jan 1, 1945

By R. E. MacAfee

THERE have been great changes in the design, capacity, and pressure of steam generating units over the past fifty years. If we go back as far as 1890, the plants then existing were largely horizontal return tubular boilers, hand-fired, with the boilers supported on the brick sitting which was com-posed of red brick with, probably, a refractory lining one brick thick in the combustion chamber. About this time, the water tube boiler began to supplant the H.R.T. boiler and, where new plants were being constructed of any size, water tube boilers were largely installed. In those days, say from 1890 to 1905, a 250 h. p. water tube boiler was considered a large unit. These boilers were largely the straight tube type and were set with the first row of boiler tubes three to six feet above the grates. The brick setting was a combination of red brick and fire-brick. The fire-brick lining in the furnace proper was usually 9 in. thick and in the first pass 4 1/2 in., while the rest of the setting was entirely red brick. These units were largely hand-fired and were expected to produce about 100 per cent rating as a maximum. It may be well at this point to define rating, which is the evaporation of one boiler horse power per hour by each ten square feet of heating surface in the boiler. A boiler horse power is the evaporation of 34.5 pounds of steam from and at 212°F. Consequently, a boiler containing 2,000 square feet of heating surface is rated at 200 h. p. and the evaporation at 100 per cent rating is 200 X 34.5, which equals 6,900 pounds of steam per hour from and at 212°F.

Jan 1, 1939

By Sherwin F. Kelly

With the progressive exhaustion of ore deposits easily discovered by surface prospecting, the attention of scientists is being turned more and more to the employment of mechanical means for the location of ore bodies whose outcrops are not visible. The dip needle, the Eotvos Torsion balance, and various methods of electrical prospecting are illustrative of the modem tendency. Interest in the possibility of applying electricity to the solution of many of the prospector&apos;s problems dates much farther back than is usually realized. The first person to notice an abnormal intensity of electrical activity in the region of certain ore bodies was an Englishman, R. W. Fox, who experimented on the Cornwall copper and tin veins about 1830. Dr. Barus, in the United States, carried the early experiments a step further in his work on the deposits of Eureka, Nevada, about 1880. He made the very definite suggestion that the phenomena noticed would be of material aid to the prospector. Not until Professor Schlumberger, of the Ecole des Mines, Paris, took up the matter, shortly before the war, was any definite effort made to put electrical prospecting on a commercial basis. His work resulted in the establishment of sound principles and practicable field technique, for two distinct methods of prospecting.

Jan 1, 1924

By L. H. Shang

The 319 Al-Si alloy is one of the most prominently used aluminium-based alloys in motor vehicle and engine applications, Microporosity present in 319 alloy castings reduces the load bearing capacity of the castings, The quantitative prediction of microporosity levels in Al-Si castings has been a subject of much interest for several years. In this research a new criteria function, tf 1,98 R13° (tf: local solidification time, R: cooling rate) was developed by multiple regression analyses, correlating thermal data from simulation studies to experimentally obtained microporosity values. This new criteria function gives a general prediction of microporosity in 319 Al-Si castings.

Jan 1, 2005

By J. Lui

Inco Copper Cliff Smelter commissioned two new Inco flash furnaces in 1991/1993 as part of its S02 abatement program. Each flash furnace is equipped with a fluid bed dryer. The ~ 12 wt% water content in the concentrate filter cake, flux, reverts and sludge is removed in the fluid bed dryer. The dry solids are discharged from the dryer together with exhaust gases into the baghouses where they are separated. The dry solids are transferred to four storage bins. In September 2003, for the first time since startup in 1991/1993, a large amount of elemental sulfur accumulation was discovered on the walls, roofs and floors of the outlet side of the baghouse chambers. Several baghouse fires were experienced during cleaning and conducting maintenance work in the elemental sulfur contaminated baghouses. Laboratory scale test work at the Inco research lab was conducted to understand the mechanism. A plant solution to minimize elemental sulfur formation was implemented with success. This paper summarizes the efforts to understand and minimize elemental sulfur formation in the baghouse chambers.

Jan 1, 2007

By Arthur Dubé

An account is given of the developments brought about in the last fifteen years by metallurgical research in the field of heat treatment of steels. The practical aspects of these developments are especially emphasized. Methods of representation of the phase-change during austenitizing and sub-critical transformation of austenite are described and the importance of time-temperature-transformation charts for the planning of heat treatment cycles is shown. Special copies such as retained austenite and internal stresses developed on quenching are also discussed in some detail. Due to the interest shown currently in these problems, it has been thought advisable to describe briefly the underlying principles and present some of the results already available.

Jan 1, 1945

By T. Guan, G. Fu, X. Zhou, L. Deng

"Currently, tailings water is required to be recycled in minerals processing plants. When the flotation tailings water of complex copper-sulfur-tungsten polymetallic ore is reused to the flotation of copper-sulfur ore, a portion of tungsten would be lost in copper concentrate or sulfur concentrate due to the addition of the collectors used for oxidized ore which are also effective for the sulfide minerals in the process of tungsten flotation. At the same time, the technical index of copper concentrate and sulfur concentrate would be seriously affected by tailings water. Our experimental researches of many years show that the copper concentrate with a grade of 18.36% Cu at a recovery of 76.67% is obtained for the raw ore containing 0.60% Cu, 18.99% S, 0.16% WO3 in small locked cycle test using recycled water, through simple pretreatment of the tailings water from tungsten flotation and adding special regulator CW and new tungsten collector TM. The result is close to the performance without using tailings water. And, in the continuous pilot experiment which was continuously conducted for 4 days with the same technology, the following results was obtained: the copper concentrate with a grade of 21.74% Cu, the recovery was 71.55%; the sulfur concentrate with a grade of 45.16% S, the recovery was 80.10%; the tungsten concentrate with a grade of 42.63% WO3, the recovery was 54.62% relative to raw ore (the recovery relative to scheelite was 76.47%). The throughput of the continuous pilot experiment is 1.0~1.2 t/d, and the raw ore contains 0.56% Cu, 18.80% S, 0.14% WO3 on average.INTRODUCTIONMining industry is one of the most important developing fields, it supplies raw materials for industrial production as well as discharges much waste water. Tailings water is the main source of beneficiation waste water, it would result in severe environmental pollution if discharged directly. Generally, the tailings water would bring undesirable effect on flotation index after simple pretreatment by lime (Kalin, Fyson, & Wheeler, 2006). On the other hand, the treatment of tailings water through ion-exchange (Cui & Liu, 2015) before recycling is of high cost. Generally, in the flotation of Cu-S-W polymetallic ore, when the tailings water from tungsten flotation is treated simply by lime and recycled to the flotation of sulfide minerals, the flotation index of sulfide minerals decreases, and a portion of oxide mineral would be lost in the sulfide concentrate. As a result, the recycle rate of this kind of tailings water is relatively low, some of the tailings water is discharged after simple treatment and then environmental pollution is caused subsequently. One of the effective ways to improve beneficiation performance and increase the recycle rate of tailings water is to conduct research on developing recycle technology for flotation tailings water of complex copper-sulfur-tungsten polymetallic ore."

Jan 1, 2016

By S Grönstrand, C. Perez, A. B. Yañez, F. Coddou, P. Morales, H. Elgueta

"The TankCell® 300 forced air flotation cell designed and built by Outotec, with active volume of over 300 m3, was installed at Codelco’s Chuquicamata concentrator in September 2008. After that, a program was conducted, where the new cell was tested against the plant’s existing flotation cells of type TankCell® 160, with an active volume of over 160 cubic meters.Testing program was exhaustive and detailed. Grade-recovery curves for each setup were reported, along with recoveries by particle size. Secondly, operational characteristics like air feed and froth height setpoints, and power consumption are compared side-by-side. As the third topic, gas dispersion characterization included velocity mapping, holdup, bubble size and bubble surface area flux operating range. The fourth area of interest was the retention time distribution (RTD) of the 300 and 160 m3 cells in comparison. A detailed campaign using radioactive tracer tests was conducted to clarify this.All of the investigations mentioned above are reported in separate papers for more detail. The aim of this paper is to collect the key findings, and present them in real terms, always referring to operability and metallurgy of the cells. It is destined for people designing new plants and to those improving and expanding existing ones. The most frequently heard question is: will the new large cells operate at same efficiency as the smaller ones. In short, the answer is: NO. They operate at improved efficiency!INTRODUCTIONIn the last two decades of minerals processing, there have been three dominant trends of development in the flotation technology: equipment scale-up, cell characterization and circuit modeling. Equipment scale-up has been rapid in the past two decades. In the year 1990, the largest flotation cell in use was 50 cubic meters of size. This year, 300 cubic meters is the largest installed cell. Characterization of flotation equipment and circuits is a very popular subject nowadays and has helped many operations to improve their recoveries through better control strategies, for example by using optimized air feed and level control profiles (Gorain, 2005), (Doucet, Gomez, Finch, 2006), or through better maintenance (Coleman, Urtubia, Alexander, 2006). Characterization work is closely linked to circuit modeling. The aim is to produce sufficient amount of data to allow reliable model building. These models are then used to design new circuits and to improve existing ones. So in summary, these three lines of development have slightly different aims – from capital and operational cost to performance optimization. Ultimately, they converge in the same end result – maximizing the profitability of the operation. Following chapters will summarize the extensive test work and scientific studies at Codelco Chuquicamata. The aim was to compare a TankCell® 300 cell, with nominal volume of 300 m3, against two TankCell® 160 machines, with 160 m3 volume in each. The work should yield answers to questions: does the larger cell produce similar results – is the scale-up successful?"

Jan 1, 2010

By C. DeLong

"The Mt. Milligan porphyry copper-gold deposits are in central British Columbia, 155 km northwest of Prince George. Mineralized outcrops and float were discovered in the Mount Milligan area by prospecting. The most recent discoveries, which utilized lithogeochemistry, were in 1983. Areas containing the outcrops and float then were investigated by geological mapping, soil and lithogeochemical sampling, ground and airborne geophysical surveys, trenching and diamond drilling. This work led to the discovery of the Mt. Milligan Main deposit in 1987 and the Southern Star deposit in 1989. Extensive diamond drilling continued until 1991 and delineated a measured and indicated resource of 299 million tonnes grading 0.45 g/t Au and 0.22 % Cu from the combined deposits.The Mt. Milligan deposits lie within the Early Mesozoic Quesnel Terrane and are hosted by porphyritic monzonite stocks and adjacent volcanic rocks of the Takla Group. The Mt. Milligan Main deposit is centred around the MBX stock and Rainbow dike, and the Southern Star deposit around the Southern Star stock.Potassic alteration is extensive within the stocks and in volcanic rocks adjacent to the MBX stock and Rainbow dike. Propylitic alteration surrounds the potassic alteration and decreases in intensuy away from the stocks. Mineralization consists mostly of pyrite, chalcopyrite, lesser magnetite, and minor bornite, molybdenite and gold.Mineralogical zoning is well-developed within the deposits. A biotite-rich subzone forms the core of the potassic alteration zone and hosts most of the copper and gold. Numerous polymetallic veins lie within the propylitic alteration zone just beyond the limit of porphyry-style copper-gold mineralization."

Jan 1, 1995

By R. W. Coburn

The results of field experiments on wells which required stimulation indicated that engineered well-completions will cause an increase in ultimate recovery at reduced costs. Techniques and tools have been developed which can be used to establish well conditions most conducive to successful stimulation. Cementing, perforating and treating are bound together so completely that the success of one phase is completely dependent on the .effectiveness of the preceding phase. A method of determining the efficiency or effectiveness of any given well-stimulation treatment has been derived. Pressure behaviour during a treatment can be analyzed to yield the total percentage of the formation which has been treated.

Jan 1, 1960

By A. Hayatdavoudi, K. G. Sawant, F. Boukadi

"In this work, we found that contact between shale and water results in development of micro fractures. Based on results of experiments on Pierre shale, we conclude that appearance of micro fractures begin with saturation of capillaries, ionic and diffusive transport of water into the shale clays and once capillaries are saturated, the cause of micro fracture propagation is the conversion of ionic activity/exchange to excess pressure that did not exist before fracking. Based on these findings, the spread of micro fractures appear to be a time-dependent phenomenon which has not been addressed in the existing macro/micro fracture models.INTRODUCTIONShale has often been involved as a hazard in drilling operations. This hazard can be defined as “destabilization” of shale. When contacted with water-based drilling fluids, some shales readily swell and sometimes, cause the wellbore to cave-in, slough, wash-out, close, and pack-off, impeding the drilling by sticking the drill-pipe. However, once drilling reaches the desired depth or length, the casing is set, cemented, and perforated, and then actually we wish to initiate fractures and destabilize the shale formation, using hydraulic fracturing.Clays constitute a major portion of minerals in shale. These clays contain a large amount of free energy which is the main factor for “slick” water adsorption/absorption. In fact, the reason for using “surfactants” in hydraulic fracturing fluids is to make the penetration of the fluid into the capillaries much easier, thus water meets with less resistance to enter the small capillaries. Also, the result of high capillary suction pressure is due to small Angstrom size capillaries, smaller pores and presence of ions and hydrateable metal atoms. The free energy is thus, related to all the above mentioned and other affects. Capillary pressure, osmotic pressure and other pressures are responsible for creating the micro-fractures in shale, thus, increasing the network of micro-fractures which leads to more gas production. The objective of this study is to evaluate the pressures of the individual ions which are released by the diffusing “slick” water into shale. These pressures would be added to the above mentioned capillary pressure, osmotic pressure, bacterially-induced pressures, chemically-induced reaction pressure, pressure due to exchangeable ion-transport, pressure due to release of free energy of solvation and eventually to the pore pressure as suggested by Terzaghi’s equation."

Jan 1, 2015

"Real time analysis of conveyed bulk materials can be used to improve process performance by reducing variability and upgrading ore quality through selective removal of increments of flow that do not meet appropriate selection criteria. This paper focusses on proven Prompt Gamma Neutron Activation Analysis (PGNAA) and microwave transmission technologies used to representatively measure conveyed ore quality in real time so that meaningful decisions can be made between the mine and mill. This enables the effective removal by bulk diversion of small increments of conveyed flow such as waste, highly deleterious material or sub-economic material from the mill feed. Improved ore quality in plant feed optimises process performance, reduces processing costs and minimises tailings generation. Analysis is unaffected by particle size, dust, layering or segregation, mineralogy and belt speed. Technologies are explained and performance examples given from installations in copper and iron ore. The technology has been used successfully in bulk sorting for over twenty years typically using measured increments of a few minutes. Improvements in technology and calibration performance have resulted in accurate measurements over increments of thirty seconds and below.INTRODUCTION Ore quality variability exists on a number of scales. Block model grades represent a few hundred to many thousands of tonnes. Grade control at the mine occurs on a scale typically down to the size of a haul truck, which may be a few hundred tonnes. Highly variable ore quality is detrimental to process efficiency and effectiveness. Processing waste or low grade ore when higher quality feed is available represents a lost opportunity to generate higher revenues earlier in the operational life. Measuring ore quality accurately over short time increments during conveying enables small increments to be measured and diverted according to their quality. The paper explains the technology and benefits. Neutron irradiation techniques were considered potentially suitable for conveyed bauxite measurement by Beurton et al, 1995. Tran & Evans (2001) concluded there was no equivalent technology to Prompt Gamma Neutron Activation Analysis (PGNAA) in terms of material penetration power. PGNAA was evaluated by Nelson & Riddle (2003) for possible use in the phosphate industry and recommended its use for further characterisation of the mine’s various ore types to improve stockpile allocation and grade control. Cottle (2007) discussed test work for an iron sinter application and Delwig et al (2011) described the successful installation in 2009 and performance of PGNAA for base-to-acid ratio control in sinter feed with the analyser output used to control lime addition. Geoscan (PGNAA) works very well on iron ore and can “improve control over what is happening in the plant” and that comfort can be provided in knowing that the product is on-spec according to Minnett (2010). PGNAA is not yet used in the minerals sector for tariff purposes as has occurred since 2000 with Coalscan (PGNAA) in coal (Minnett, 2010)."

Jan 1, 2017

By M. Lahtinen

Traditionally, there have been three main methods for iron removal in the hydrometallurgical production of zinc. These methods are atmospheric precipitation of jarosite or goethite and pressurised precipitation of hematite. Jarosite precipitation is without doubt the leading and the most commonly used technology for iron removal. However, jarosite precipitation has some drawbacks, such as a low iron content (and, thus, high residue volume), high moisture content after filtration and often a high zinc content. These features make any environmentally acceptable way of using or disposing of jarosite more expensive, as compared to hematite and goethite. The importance of environmental regulations has grown in the zinc industry during the last decade, which will have an increasing effect on new investments. Hematite has several advantages over jarosite, such as a high iron content, low moisture and low zinc content. An important advantage of hematite is that it is suited for further use in the cement industry. However, until now the need for autoclave equipment has limited the spread and implementation of hematite precipitation in the zinc industry. Outokumpu Technology Oy has recently developed an alternative method for iron removal, which is the atmospheric precipitation of hematite. A patented method for precipitating hematite at atmospheric pressure is presented and compared with conventional methods for iron removal. The process conditions, the quality of the hematite precipitate and the environmental aspects are also discussed.

Jan 1, 2006