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The inherent weakness of the Zincor and similar iron removal processes is the relatively high undissolved zinc loss associated with the iron residue. High soluble zinc losses also occur due to poor filterability of the iron residue even though it may be limited to intermittent events. This work focussed on defining the optimum operating window for the Zincor iron removal process where iron is mainly removed in the form of amorphous, intermediate iron phases such as schwertmannite and ferrihydrite. In terms of the main operating conditions, optimum filterability was achieved under the following conditions: pH of 3.0, temperature as high as practically possible (70C), at least 25 kg/m3 seeding, and a retention time of at least 4 hours. When increasing the temperature from 60C to 70C, the required residence time decreased by almost 50%. Undissolved zinc loss was also reduced from 8% to between 2% and 3% by using a basic zinc sulphate/zinc oxide mixture as neutralising agent to effect iron removal.

Jan 1, 2003

By B. Oladipo, E. Govender-Opitz, T. V. Ojumu

Bioleaching, one of the several important processes of biohydrometallurgy is an accepted technique for the extraction of desired metals from sulphide ores. Although the mechanism is well understood, the slow metal extraction rate due to passivating layer and ferric ion precipitation, especially in a typical chalcopyrite leaching, impact negatively on the overall efficiency of the process. Iron precipitates are common in many biohydrometallurgical operations and these precipitates represent the exit route for undesired iron, alkali ions or sulphate ion from the processing circuit. While there have been reports on approaches to slow the formation of these precipitates by manipulation of various operating conditions such as pH, redox potential and temperature, the precipitates become highly significant over the long term in the continuous operation of bioleaching and may render heap impermeable. Although there is evidence supporting the nature of the passivation to be precipitates of iron, their scavenging mode of reducing extraction efficiency is still not well understood. This paper thus discusses iron precipitation in biohydrometallurgical processes, including its formation and significance on bioleach processes. The paper also details the associated passivating species identified with heap bioleaching of sulphide minerals and provides some insight into sorption mechanism that limits metal recovery in a typical bioleach operation. Keywords: Iron precipitation, bioleaching, chalcopyrite, passivation, jarosite, metal sorption

Jan 1, 2020

By Rhulani F. Maluleke, Francis W. Petersen, John H. Marsh, Johann de T. Steyl, Allan Nesbitt

"Pressure leaching of chalcopyrite and nickeliferrous pyrrotite at temperatures between 105 and 200 ºC has been proposed as a potentially viable route for the extraction of mineral elements from sulphide concentrates. In general, these concentrates contain iron, and the economic success of the processes is partially dependent on the choice of the environmentally acceptable iron-removal technique. One of the most widely used methods for the removal of iron from sulphate liquors is precipitation as hematite, goethite, or jarosite. The nature of the iron precipitate formed dictates downstream dewatering and residue treatment and disposal options. However, a better understanding of iron precipitation under the defined process conditions would consequently be of benefit in process design and optimisation.This study investigated the precipitation of iron in the autoclave at temperatures between 105 and 200 ºC. The effects of temperature, acid concentration, iron concentration, and the presence of other metal cations on the nature and composition of the precipitates were determined."

Jan 1, 2003

By Rhulani F. Maluleke, Francis W. Petersen, John H. Marsh, Johann de T. Steyl, Allan Nesbitt

"Pressure leaching of chalcopyrite and nickeliferrous pyrrotite at temperatures between 105 and 200 ºC has been proposed as a potentially viable route for the extraction of mineral elements from sulphide concentrates. In general, these concentrates contain iron, and the economic success of the processes is partially dependent on the choice of the environmentally acceptable iron-removal technique. One of the most widely used methods for the removal of iron from sulphate liquors is precipitation as hematite, goethite, or jarosite. The nature of the iron precipitate formed, dictates downstream dewatering and residue treatment and disposal options. However, a better understanding of iron precipitation under the defined process conditions would consequently be of benefit in process design and optimization.This study investigated the precipitation of iron in the autoclave at temperatures between 105 and 200 ºC. The effects of temperature, acid concentration, iron concentration, and the presence of other metal cations on the nature and composition of the precipitates were determined."

Jan 1, 2003

By W. A. Jankola

Teck Cominco Metals Ltd. operates an integrated zinc-lead smelter at Trail, British Columbia, Canada. The zinc circuit comprises three parallel operations: conventional fluid-bed roasting, direct zinc pressure leaching of concentrates and atmospheric leaching of zinc oxide fume recycled from the lead smelter. The products from these three areas are combined in the main leaching plant where they undergo iron purification. Unlike most leaching circuits, the leach process in Trail begins with an acid leach and is followed by a neutral leach. An evaluation was undertaken to determine if the process at Trail could be improved by converting to the conventional neutral leaching process with a subsequent acid leach of the residues. This paper explores the results of these tests and the implications for Trail Operations.

Jan 1, 2006

By P. E. Hopkins

Introduction and History IN speaking of the economic geology of southeastern Ontario, W. G. Miller and C. W. Knight' say that "there occurs in southeastern Ontario a variety of minerals and rocks of economic value, probably as great as in any district of like size on the North American continent. Some of these deposits, including marble and trap, are inexhaustible. Others, including talc and iron pyrites, have proved to be of considerable economic importance. From time to time, during the last 50 years, the following minerals and rocks have been mined or quarried with varying success: gold, iron pyrites, zinc blende, copper pyrites, galena, mispickel, magnetite, hematite, talc, actinolite, mica, marble, ophicalcite, feldspar; fluorite, apatite, corundum, graphite and sodalite. All of the economic materials, with the exception of fluorite, appear to be of pre-Cambrian age. The fluorite veins penetrate the Ordovician, Black River, limestone." Accompanying that report was an article by the writer on the Queensboro Pyrite Area which includes one of the two working pyrite properties in southeastern Ontario. In the present paper will be given a brief description' of all the known pyrite deposits in the area which may at some time possess an economic value, with fuller descriptions of the two working mines-The Canadian Sulphur Ore Co.'s mine near Queensboro, and the Nichols Chemical Co.'s property at Sulphide. The earliest mining of iron pyrites in Ontario was done in 1868 on the Billings property near Brockville. The mines were closed down in 1879 under the assumption that they were exhausted. Many other

Jan 8, 1916

By Y. Qin, X. Fu, T. Qi, H. Tang

"The FASTMELT ® process was developed as an alternative to blast furnace ironmaking; in this process, high-quality molten iron is produced using direct reduction followed by high-temperature slag/metal separation. In this study, iron recovery and phosphorus removal from oolitic highphosphorus haematite using the FASTMELT® process was investigated. The performance of two reducing agents, coal and wood char, was compared. Direct reduction experiments indicated that with optimized reductant addition, the ore-char and ore-coal briquettes attained metallization values of 82% and 78%, respectively, and residual carbon contents of 0.24 and 2.35%, respectively. The slag/metal separation experiments revealed that molten iron containing 0.41% phosphorus and 0.021% silicon (by mass) was produced from optimally reduced ore-char briquettes, and molten iron containing 0.78% phosphorus and 0.91% silicon from optimally reduced ore–coal briquettes. The study indicates that carbonaceous materials with high CO2 reactivity are suitable for use in the FASTMELT ® process for phosphorus removal and iron recovery from oolitic high-phosphorus haematite. IntroductionIn China, the general depletion of iron-rich mineral reserves has led to many efforts to exploit low-grade and refractory ironcontaining resources for ironmaking (Liu et al., 2014). The efficient utilization of the highphosphorus oolitic haematite resources in central China has received considerable attention. The available resources of this material total approximately 3.0 billion tons. The oolitic units in the ore exhibit an onionlike structure with phosphorus-containing gangue layers of 2–10 µm thickness. The best concentrate produced from these resources contains approximately 50% iron (Fe) and 0.8–1.2% phosphorus (P) (by mass) (Ai, Yu, and Wei, 2009; Song et al., 2013; Wu, Wen, and Cen, 2011). Further removal of phosphorus from these ores using conventional beneficiation methods is not possible."

Jan 1, 2017

By J. C. Gathje

Newmont&apos;s Phoenix Project is located near Battle Mountain, Nevada and is scheduled to produce copper concentrates containing high precious metal values. High temperature pressure oxidation (PDX) of the concentrates was considered as a treatment option during process development. The metals content in Phoenix concentrates range from: 15-25% for Cu, 1-10% for Zn, 0-2% for Pb and ?27% Fe. The precious metals content of the Phoenix concentrates can range up to ?300 g/t Au and >3,000 g/t Ag. As a consequence it was necessary that any process for consideration should have the capability of recovering both the copper and precious metal values. Typically, gold can easily be leached from the autoclave discharge solids, but silver is chemically bound with the jarosite formed and cannot be directly leached. Laboratory investigations led to the development of a patented PDX process that minimizes the formation of jarosite so that the silver can be leached easily along with the gold. The process was confirmed with extensive pilot plant testing. Excellent solution extraction of copper and zinc was achieved, and both iron and lead were precipitated in the PDX residue. The process produces clean PDX discharge liquors with very low iron concentrations. As an example, conventional PDX techniques resulted in pregnant liquors containing ?5 g/L Fe. However, the Newmont process, which controls the iron and sulfate species, achieved high iron precipitation in the PDX solids and pregnant liquors containing <0.5 g/L Fe. High gold and silver recoveries were achieved by direct cyanidation of the PDX solids. This process has the added benefit of producing PDX solids that demonstrate superior settling and filtration characteristics.

Jan 1, 2006

By M. J. Latva-Kokko

This paper describes the behaviour of iron and the methods used for iron control in the nickel matte leaching process. OMG Harjavalta Nickel Oy processes approximately 10 000 t/y of iron, which enters the process with the nickel matte raw material. Iron dissolves and precipitates in several different stages of the leaching process. Compounds like ferric hydroxide, parabutlerite, goethite, hematite and jarosite are found. Iron removal is done within the leaching process, and this means that the dissolution of nickel sets the limiting conditions for iron precipitation. A leach residue consisting mainly of the iron precipitates is neutralized and stacked in the waste pond. When iron is precipitated from concentrated nickel sulphate solution, some nickel is lost by co-precipitation. Recent studies have shown that Ni-Fe ratios less than 1%, attributed to co-precipitation, can be obtained with jarosite precipitates, compared to 2-3% ratios typically found with hematite precipitates. Iron can be precipitated as jarosite under the optimal nickel leaching conditions by adding ammonium sulphate to the feed slurry of the autoclave.

Jan 1, 2006

By M. E. Ramírez

In this research bioleaching or extraction of iron present in a kaolin from La Virgen mine, Anti-oquia/Colombia, was carried out. Organic acids produced in SF with Aspergillus niger were used in the process. The fermentation process was carried out in 3 L aerobic stirred bioreactors, at a temperature of 30 °C, a stirrerd speed of 700 rpm, an initial pH of 4 and a fermentation time variable between one to 8 days, obtaining broth fermentation samples daily per bioreactor. For iron extraction, fermented broth from second to sixth day of fermentation was evaluated and it was found that the fermentation broth of the third day showed a larger potential for iron removal, 786 ppm, by using kaolin with an initial iron content of 1401 ppm. A set of tests using commercial organics acids such as citric acid and oxalic were carried out because those were found in the fermentation broth and it was found that oxalic acid presented three times more iron removal than citric acid.

Jan 1, 2014

By Mohammad Noaparast, Hamed Haghi

"In this research work, it was attempted to reduce the iron contents (Fe2O3) in relatively low grade silica sample which was obtained from Shenin silica mine, using magnetic separation. The prepared sample contained 93.75%SiO2, 0.44%Fe2O3, 2.78%Al2O3, and 0.08%TiO2 and the Fe2O3 had to be reduced to less than 0.08%. Mineralogical studies and XRD analysis indicated the presence of Hematite, Pyrite, and Goethite as the major iron impurity phases. Mineralogical studies of polished and thin sections demonstrated that the degree of freedom of silica is more than 80% in -300+212 ?m size fraction. After primary stages including crushing, milling, scrubbing and de-sliming, various methods such as low intensity magnetic separation (LIMS), high gradient magnetic separation (WHGMS) and dry high intensity magnetic separation (DHIMS) were applied to find out that which process would be appropriate for the elimination of iron impurities from this sample. Different experiments were carried out on the product of wet rod mill and scrubber. However the magnetic field intensity of WHGMS was increased down to 2Tesla, and there was not any acceptable result in reduction of Fe2O3 content lower than 0.08%. Thereafter the product of wet rod mill and scrubber were dried and reported to DHIMS. In these experiments, maximum magnetic field intensity was 1.4Tesla. In this case very significant results were achieved, and Fe2O3 content of final product were reduced to less than 0.05% which meets glass manufacturing standards."

Jan 1, 2014

By V. Arslan

The primary advantage of using oxalic acid is in the formation during leaching of soluble complexes that are both photo-chemically and microbiologically degradable. In this study, chemical leaching and bioleaching methods were used for quartz sand. Using the ANOVA-Yates test technique, the effects of solids rate, temperature and oxalic acid rate were investigated using chemical leaching experiments. Solids rate and temperature were effective parameters on the chemical leaching. After the tests, the removal of Fe2O3 increased to 97.02%. Finally, the iron content decreased from 0.315% Fe2O3 to 0.0094% Fe2O3 in the leached quartz sand. The effect of pulp density was investigated on the bioleaching experiments. The bioleaching of iron oxides by Aspergillus niger resulted in removal of 47.70% of the total iron in the quartz sand, and suggested that this strain has not a good ability to remove iron impurities from quartz sand in comparison with chemical leaching. The iron content decreased from 0.315% Fe2O3 to 0.164% Fe2O3 in the bioleached quartz sand.

Jan 1, 2009

By E. A. Roux

As the first mine-to-metal zinc operation utilising atmospheric leaching, solvent extraction and electrowinning, Skorpion Zinc faces unique challenges and opportunities. One of these challenges is found in the solvent extraction circuit, in which di-ethylhexyl phosphoric acid (D2EHPA) is used as the organic extractant. Although D2EHPA is an excellent extractant for zinc, it suffers from the co-extraction of ferric iron, which is produced during leaching and by the corrosion of the grinding media. This situation is partially mitigated by iron precipitation in the neutralisation step prior to solvent extraction. Unfortunately, some ferric iron still reports to the solvent extraction process. This leads to a slow build up of iron in the organic phase. Chemical stripping is used to maintain the Fe concentration at an acceptable level. In this paper, the efficiency of the iron removal process is discussed.

Jan 1, 2006

By P J. Marsh, P J. Bartsch, N J. Semler

Iron Road Limited is currently studying the feasibility of producing 20 Mt/a of high-grade (67 per cent Fe) magnetite concentrate from a 2.6 Bt resource (JORC) located at Warramboo on the central Eyre Peninsula in South Australia. Bulk concentrate has been tested at a relatively coarse grind size of -106 ¦m. The preliminary flow sheet has been confirmed based on initial mine plans and comprehensive metallurgical testing across the range of mineralisation. Extensive Davis tube testing to predict magnetite recoveries has been conducted over the resource, however this was completed at settings different to the optimised settings developed in the metallurgical test work program.This paper outlines the development of an ore treatment simulation in SysCAD which utilises the mine production plan, the Davis tube test data from the resource, data from metallurgical test work and process design criteria to predict magnetite concentrate deliveries. Mineralogical data, including QEMScan results and metallurgical assessments, were a fundamental basis of the process models which enable predictions of concentrate yield and quality. Power and water requirements are also calculated within the model. SysCAD dynamic simulation has been used to assist with the design of the process plant and downstream infrastructure. The simulation has been set-up to allow iterative integration and optimisation of the mine plan when it becomes available.CITATION:Semler, N J, Marsh, P J and Bartsch, P J, 2013. Iron RoadÆs prediction of magnetite concentrate production from the Central Eyre Iron Project, in Proceedings Iron Ore 2013 , pp 539-546 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By P. Kerr

Iron segregation is pre-dated by copper and nickel segregation processes for which the experimental methodology and reaction chemistry were established. The accepted reaction sequence for segregation involves the generation of hydrogen chloride, the chloridization and volatilization of the metal chloride, and precipitation of the metal from the metal chloride in the vicinity of carbon. Iron segregation roasting offers a potential extraction solution for processing oxide deposits with complex mineralogy or waste streams such as Minette-type iron deposits, nickel laterites, ilmenite, red mud, electric arc furnace (EAF) dust, mill scale and slag. After subsequent magnetic separation, one is left with a high grade metallic iron powder which can be marketed for powder metallurgy or briquetted to serve as a direct reduced iron (DRI) product. The non-magnetic product is typically concentrated oxides including rutile, alumina, or oxides of V, P, and rare earths, etc. that may be economically recoverable with subsequent processing. While operating conditions vary for different metals, they share the requirements of an elevated operating temperature and a mixture of oxide ore, carbonaceous additive and a chloride additive in varying amounts all in a closed reactor to allow for reducing conditions and contain the volatile chlorides. This process is then followed by some form of physical separation. Testwork performed by the authors shows promising results that may aid in future development of the process. Segregation roasting of iron will likely never displace traditional beneficiation and ironmaking technologies; however, it has great potential in niche markets where traditional technologies have failed or current technologies generate substantial waste.

By H. Weissenbaeck, B. Nowak, M. Oesterreicher, R. Stastny

The producers of certain metals like nickel and cobalt increasingly face a shortage of easy-to-mine and easy-to-process ore bodies. Their focus is shifting towards alternative raw materials which in turn demand new, different extraction techniques. One potential route for processing a ferrous ore with a non-ferrous target metal is atmospheric leaching with hydrochloric acid followed by purification of the pregnant leach solution (PLS). For the separation of iron from the PLS, and, in turn, the extraction of the non-ferrous compounds, the following flow sheet is proposed. Pre-concentration of the PLS, oxidation of ferrous (if present) to ferric chloride, hydrolysis of ferric chloride leading to the precipitation of hematite and the evaporation of hydrochloric acid, followed by crystallization of non-hydrolysable metal chlorides by means of sparging hydrogen chloride into the solution. Hydrogen chloride required in the latter step is produced internally by super-azeotropic distillation of regenerated hydrochloric acid. The liquid filtrate from the crystallization step is recycled to hydrolysis. Depending on the specific composition of the PLS, the hematite produced contains only traces of other impurities, whereas the crystallized mix of non-hydrolysable metal chlorides – containing also the target metal in enriched form – contains ferric chloride only in an amount referring to the filter cake moisture. These crystals can then undergo further hydrometallurgical separation and extraction processes. As an example, this flow sheet is proposed for treating nickel laterite ores. Experiments related to the demonstration of crucial assumptions in the flow sheet are presented. Based on those experiments a mass and energy balance of the flow sheet was calculated and is presented here together with a table of the major consumables in order to provide a basis for an operating cost estimate and other process economics.

Jan 1, 2016

By U König, N Norberg

Traditionally, quality control of iron sinter has relied on time-consuming wet chemistry. However, the mineralogical composition that defines the physical properties, such as strength or reducibility, is not monitored.X-ray diffraction (XRD) analysis in combination with Rietveld quantification and statistical data evaluation using partial least squares regression (PLSR) has been successfully trialled to determine the mineralogical composition and process parameters such as the FeO (Fe2+) content and basicity of iron sinter within an analysis time of less than eight minutes per sample. The results were compared with wet chemistry data.PLSR does not require pure phases, crystal structures or complex modelling of peak shapes. The analysis is therefore easy to set up and ideal if only one property needs to be analysed. PLSR results show an accuracy for the FeO content of &#177;0.3 per cent for the samples analysed in this case study.Both the PLSR and Rietveld methods take the full XRD pattern into account and can be simultaneously applied on the same measurement. PLSR was found to be the more robust method if only FeO and basicity results are required. The Rietveld method helps to predict other parameters, such as the compression strength of the sinter, by monitoring all existing phases (eg larnite C2S or silico-ferrite of calcium and aluminium phases).CITATION:K&#246;nig, U and Norberg, N, 2015. Iron sinter process control using x-ray diffraction, in Proceedings Iron Ore 2015, pp 53–60 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By U König, N Norberg

To cope with varying raw material qualities and increasing prices for energy, a more frequent and accurate monitoring of the processing of iron ore became the focus in sinter plant operations. Traditionally, quality control in iron producing industries has relied on time-consuming wet chemistry or the analysis of the elemental composition. The mineralogy of a sinter that defines the properties and behaviour in the blast furnace is often not frequently monitored. One fast method to analyse the mineralogical composition of iron sinter, raw mixtures and iron ores is X-ray diffraction (XRD). Recently statistical methods such as similarity analysis or partial least square regression (PLSR) in combination with XRD raw data has become more and more popular in handling large amounts of data and correlating process-relevant parameters directly with an XRD measurement. PLSR can be used to correlate process parameters directly from the XRD pattern without investigating the mineral content. Hidden information that is present in the measurement but not determined with traditional methods can be used to improve the characterisation of the analysed materials.CITATION:K&#246;nig, U and Norberg, N, 2017. Iron sinter process control using X-ray diffraction – part : monitoring of low temperature degradation, in Proceedings Iron Ore 2017, pp 75–78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By A. C. Moorgas, J. Divall

This study investigates the feasibility of using waste iron slag, the by-product from a mineral sands processing works, in road construction. The study includes the different options investigated for the treatment of a leachate that is produced during the cooling of the iron slag, prior to processing. It also reviews the reasons for choosing the current treatment option that is being trialed. Cooling the iron slag with water results in the formation of a leachate with a high pH and high sulphide concentration. This leachate can seep into the ground and, over time, it will contaminate the ground water. A system was designed to collect and treat the leachate to prevent contamination of surrounding natural water sources. Numerous leachate treatment options were investigated to find cost effective method of treatment After cooling, the iron slag is passed through an iron recovery plant and the unsaleable product is placed on a dumpsite. Rain percolates through the dumpsite, which can result in the formation of a leachate that can contribute to a contaminated plume. After extensive testwork, it was found that the dumpsite, which was leached of contaminants, could be screened and used as a G5material (specifications in Table II) in road construction. The initial challenge was to establish that this material was environmentally safe for use in this particular application. Approval from the Department of Water Affairs (DWAF) was required for the testwork and then for the long-term use of this material in the construction industry. The following challenge involved establishing a market for the material. Construction companies in the area were reluctant to change to a new product that was not naturally occurring. The economics of this project are extremely sensitive to transport costs and hence only projects within a specified radius can be supplied with the Black Top Gravel (BTG). This project is not are venue generator, but it does save the money that would be required to manage the dump, and it reduces the closure costs.

Jan 1, 2003

The negative effects of pyrite and pyrrhotite on thiosulfate gold leaching have been investigated. Possible remedies to reduce some problems are discussed. In a gold bearing pure silicate ore, 92% of gold could be extracted within 3 hours using a solution containing 0.2 mol/L ammonium thiosulfate, 0.9 mol/L ammonia, 30 - 300 ppm copper sulfate and 8.6 ppm dissolved oxygen at pH 10.26. The thiosulfate consumption was 7.1 kg/t under these conditions and could be further reduced to 3.5 kg/t by decreasing the dissolved oxygen to 0.3 ppm. Addition of 16% pyrrhotite or pyrite into the silicate slurry led to a decrease in gold extraction by 2% or 9% respectively and an increase of thiosulfate consumption by 11 kg/t or12.8 kg/t respectively in three hours. Several adjustments, such as increasing copper ion and ammonia concentration and reducing the dissolved oxygen level to 0.3 ppm resulted in increased gold extraction and lower thiosulfate consumption despite the presence of these sulfides.

Jan 1, 2005