Typical Iron Ore Research Articles

Effect of Slimes on Iron Ores Flotation

The presence of slimes is, in general, harmful to the flotation of iron ores, affecting the selectivity and the quality of the concentrates, besides causing an increase in reagents consumption. This work describes the behavior of different iron ore types from the Iron Quadrangle, Brazil, with respect to desliming in hydrocyclones and flotation, including a study on the dispersion degree as a function of pH. Flotation experiments were performed at different slimes contents (designated as by-pass) aiming at assessing the influence of this variable on the selectivity. The different ore types present differences in chemical and mineralogical composition and also in size distribution. The content of slimes not removed in the desliming stage (by-pass) affects differently the selectivity of each ore type. Some ores keep the selectivity constant for all levels of by-pass, but present a reduction in phosphorus grade in the concentrate for reduced by-pass levels. Other types respond to the reduction of by-pass with increased selectivity. As a general rule, by-pass levels lower than 4% lead to a stable behavior concerning selectivity, yielding low phosphorus content in the concentrate. The behavior of each ore type is related to the chemical and mineralogical composition and size distribution of the slimes and also to the dispersion degree of the ore. Preliminary tests indicated that the specific surface area of samples with different by pass levels can explain the flotation behavior.

Emission characterization of unintentionally produced persistent organic pollutants from iron ore sintering process in China

Emission of unintentionally produced persistent organic pollutants (Unintentional POPs), including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychorinated biphenyls (PCBs), hexachlorobenzene (HxCBz) and pentachlorobenzene (PeCBz), were investigated in four typical iron ore sintering plants in China. The emission factors and annual mass releases of the Unintentional POPs were calculated. The results indicated that PCDFs contributed more than 60% to the overall toxic equivalent quantity (TEQ) values, while the contribution of the dl-PCBs is relatively low, and only in the range of 8–9%. The dominant congeners of PCDD/Fs and dl-PCBs contributing most to the total TEQ were 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF and PCB-126. With regard to the TEQ contributions, the most abundant homologues were PeCDFs and HxCDD/Fs, followed by PeCDDs and non-ortho dl-PCB, whereas HpCDD/Fs, OCDD/Fs and mono-ortho dl-PCBs almost made no contributions. Due to the massive use of recycled waste in the feeding materials, the average emission factor of PCDD/Fs and dl-PCBs of the four plants was 3.95μgWHO–TEQton−1. Based on the results, the annual release of PCDD/Fs and dl-PCBs in 2007–2009 were estimated to be 2070g, 2212g, and 2307gWHO–TEQ, respectively.

Utilization of Iron Ore Slimes: A Future Prospective

In India, iron ores processing industries play a vital role in the Indian economy. During the washing and processing of iron ores, slimes less than 0.15 mm are generated and discarded into the tailing pond. These slimes need processing as they cannot be used directly in blast furnaces. In the present investigation, a typical iron ore slime sample containing 59.22% Fe, 4.76% SiO2, and 4.57% Al2O3 was taken. The desliming operation was carried out by using 2” Mozley hydrocyclone. The process variables used to attain the optimum condition of desliming include the spigot opening, the feed pressure, and the diameter of the vortex finder maintaining the pulp density at 10% solid. The deslimed sample was treated by different techniques including an enhanced gravity separator to achieve iron concentrate with 65% Fe so that it can be used for steel making through pelletization. The yield of the magnetic concentrate is about 46.8% with 65% Fe. To improve the yield, the overflow from 2” hydrocyclone and the rejects from magnetic separation were deslimed and processed to recover the iron values. The final concentrate is 74% yield with 64.8% Fe, 1.76% SiO2, and 1.8% Al2O3.

Identification of minerals and organic materials in Middle Eocene ironstones from the Bahariya Depression in the Western Desert of Egypt by means of micro‐Raman spectroscopy

The Middle Eocene ironstones of the Bahariya Depression consist of four iron ore types: manganiferous mud‐ironstone, fossiliferous ironstone, stromatolitic ironstone and nummulitic–ooidal–oncoidal ironstone. The upper surfaces of these sequences were subjected to subaerial weathering and a lateritic iron ore type was formed. The chemical composition of these ironstone types was investigated by means of micro‐Raman spectroscopy. Various closely related iron‐containing and manganese‐containing minerals were detected by means of the above‐mentioned approach. The high spatial resolution and sensitivity of this method allowed us to identify minerals that could not be detected by other techniques. Well‐preserved organic materials were observed in one type of ironstones. Therefore, using Raman spectroscopy, we were able to provide evidence that the formation of some of the investigated rocks was biologically mediated. The application of Raman spectroscopy is considered a powerful technique for the identification of both organic and inorganic substances in the studied iron ore deposits. Copyright © 2011 John Wiley & Sons, Ltd.

Ability for Self-Pelletization of Iron Ores and Magnetite Concentrates

A procedure for evaluating the susceptibility of raw materials for the process of sintering of iron-ore mixes is presented. The procedure relies on the evaluation of the amount and quality of the finest grain fraction. The method is based on determination of particular grain fractions. For the grain less than 0. 15 mm, the determination of the amount is performed using an IPS (Infrared Particles Sizer) grain size analyzer and for the grain larger than 0. 15 mm, the fraction is determined using the (wet and dry) screening methods. This allows for quantity assessment of the quality of material in terms of its susceptibility to self-pelletizing by calculating Total Ability for Self-Pelletizing (TASP) index f τ. The presented method, in combination with the grain size and chemical analyses, can serve for evaluation of suitability of raw material and mixes for the sintering process. Furthermore, the TASP index for 10 types of iron ores and concentrates was determined. The usability of the TASP index was verified by determination of its impact on yield of sintering process both in laboratory and in industry scale.

Structural deterioration of iron ore particles during thermal processing

Degradation of iron ore particles during ironmaking produces airborne particulate matter and reduces process efficiency. The work presented here investigates thermal deterioration of iron ore particles during thermal processing of two types of iron ores, goethite and hematite. While the hematite iron ore showed close to an inert thermal behaviour, the goethite sample exhibited significant structural and thermochemical changes during heating at approximately 300 °C due to the breakdown of the hydroxyl bonds and release of water vapour. The associated strain in the particle caused by structural deterioration and crack propagation through the iron ore particle during heating was further modelled in this work. The model showed that cracks are initiated on the surface of the goethitic particle with crack propagation from the surface down to 20% of the particle diameter. Heating of iron ore particles in a fixed bed reactor did not produce particle fragmentation, however the structural changes during heating of the goethitic iron ore sample were so significant that the heating is expected to destabilise the particle structure and generate conditions favourable for particle degradation through mechanical or reduction induced particle deterioration.

Research on High-Temperature Properties of Typical Iron Ores Used in China and its Blending Optimization

High-temperature properties of 10 samples of iron ore from Brazil, Australia and China were measured. Several conclusions were made based on these experimental results. Assimilability of Brazilian ore, Australian ore and Chinese ore concentrate were low, high and medium, respectively. Optimal fluidity of liquid phase was observed in 2 types of Brazilian ores (BR-B, BR-C), 1 type of Australian ore (AU-C) and 1 type of Chinese ore (CH-D). For self-strength of the bonding phase, Australian ore presented low levels, while Brazilian and Chinese ore presented high levels. According to the experimental results of high-temperature properties of iron ore, schemes of ore blending optimization were designed and sinter pot test using these blends were performed. The results indicated that ore blends composed of 30~45% Brazilian ores + 25~50% Australian ores + 20~30% Chinese concentrates presented excellent sintering results, considering both the performance of the processing and quality of the sinter. Therefore this experiment has proved that ore blending optimization combining high temperature properties can lead to more efficient sintering mixes.

Behavior of Vanadium and Niobium during Hot Metal Dephosphorization by CaO–SiO<sub>2</sub>–Fe<sub>t</sub>O Slag

V and Nb are key elements for the production of high-grade steel. These elements are produced by few countries, and V has been nominated as a national stockpile element in Japan. Despite the importance of these elements, there are no strategies to obtain stable resources for them. Some types of iron ore that contain V and Nb can be used as sources of these elements. This study clarified the possibility of extracting V and Nb by means of a conventional hot metal dephosphorization process without using CaF2 as a flux. First, the influences of V and Nb oxides on the distribution ratio of P2O5 between the solid solution and liquid phases in slag were measured. Then, the behaviors of V and Nb in hot metal dephosphorization by CaO–SiO2–FetO slag were investigated. Finally, a previously described hot metal simulation model was modified and the behaviors of various elements, including V and Nb, during hot metal dephosphorization were simulated, and the results were compared with experimental ones. The results are summarized as follows: (1) The addition of V and Nb oxides slightly increases the distribution ratio of P2O5 between the solid solution and liquid phases in slag. (2) The decreasing rate of the elements by the flux addition can be expressed as Nb > Mn > P > V, and these decreasing rates increase as the basicity increases. (3) The simulation results for the behavior of P and V or Nb are in good agreement with the experimental results; that is, the decreasing rate for Nb is greater than that for P, and the separation of Nb leaving P in the hot metal is easier than the separation of V.

Mineralogy, geochemistry, and origin of hydrothermal manganese veins at Wadi Maliek, Southern Eastern Desert, Egypt

The present work deals with the geology, mineralogy, geochemistry, and origin of the metagabbroic-hosted manganese deposits at Wadi Maliek in the southern Eastern Desert of Egypt. The manganese veins are found in the shear zones and channel ways of the fault planes within the metagabbroic rocks pointing to those hydrothermal solutions carrying manganese and iron load penetrating along these fractures. These faults are striking N 80° E–S 80° W with dipping 65°. These veins vary in thickness from 15 cm up to 125 cm wide; each vein may show difference in thickness from bottom to top. Microscopic examinations, X-ray diffraction, infrared spectral, differential thermal (DTA), thermogravimetric (TGA), and ESEM-EDAX analyses revealed that the manganese minerals consist mainly of pyrolusite, psilomelane, and ramsdellite. Goethite and hematite are the common iron minerals. Petrographically, the manganese deposits can be classified into three ore types based on the predominance of manganese and iron minerals: manganese, manganese–iron, and iron ore types. The geochemistry of Maliek deposits indicated that the total averages of some major oxides in manganese, manganese–iron, and iron ore types are respectively as follows: SiO2 (15.64%, 11.52%, and 20.58%), MnO (39.9%, 17.81%, and 0.77%), FeO* (7.13%, 33.31%, and 37.08%), CaO (5.89%, 5.82%, and 5.32%), and Na2O (1.04%, 1.61%, and 1.53%). With regard to trace elements, the Maliek manganese deposits are rich in Zn, Ba, Pb, Sr, and V. Based on the geological, mineralogical, and geochemical results, the studied manganese deposits are considered to be precipitated from hydrothermal solution.

Isolation and identification of iron ore- solubilising fungus

Potential mineral-solubilising fungi were successfully isolated from the surfaces of iron ore minerals. Four isolates were obtained and identified by molecular and phylogenetic methods as close relatives of three different genera, namely Penicillium (for isolate FO), Alternaria (for isolates SFC2 and KFC1) and Epicoccum (for isolate SFC2B). The use of tricalcium phosphate (Ca3(PO4)2) in phosphatesolubilising experiments confirmed isolate FO as the only phosphate solubiliser among the isolated fungi. The bioleaching capabilities of both the fungus and its spent liquid medium were tested and compared using two types of iron ore materials, conglomerate and shale, from the Sishen Iron Ore Mine as sources of potassium (K) and phosphorus (P). The spent liquid medium removed more K (a maximum of 32.94% removal, from conglomerate), than the fungus (a maximum of 21.36% removal, from shale). However, the fungus removed more P (a maximum of 58.33% removal, from conglomerate) than the spent liquid medium (a maximum of 29.25% removal, from conglomerate). The results also indicated a potential relationship between the removal of K or P and the production of organic acids by the fungus. A high production of gluconic acid could be related to the ability of the fungus to reduce K and P. Acetic, citric and maleic acids were also produced by the fungus, but in lower quantities. In addition, particle size and iron ore type were also shown to have significant effects on the removal of potassium and phosphorus from the iron ore minerals. We therefore conclude that the spent liquid medium from the fungal isolate FO can potentially be used for biobeneficiation of iron ore minerals.

Mobilisation of potassium and phosphorus from iron ore by ectomycorrhizal fungi

Mutualistic roles of ectomycorrhizal (ECM) fungi have been linked to their ability to produce organic acids that aid in the dissolution of insoluble minerals in the rhizosphere. This ability of ECM fungi was utilised to investigate their potential participation in the mobilisation of nutrients such as phosphorus (P) and potassium (K) from a typical insoluble ore—iron ore. In vitro pure cultures of four different ECM fungi; Pisolithus tinctorius, Paxillus involutus, Phialocephala fortini, and Suillus tomentosus were screened for their ability to mobilise P and K from two types of non-exportable Sishen iron ore. When present in iron ore, these elements are deleterious and reduce the commercial values of the ore. Experiment was set up with different treatments that included two ore types (KGT and SK) and five particle sizes of each ore type. Results indicated the potential of the four fungi to mobilise P and K from the two iron ore types though at different levels. Ore type, particle size, organic acid production and attachment of the fungi to the iron ore were all found to play important roles in the mobilisation of nutrients from these ores.

A synopsis of the channel iron deposits of the Hamersley Province, Western Australia

The channel iron deposit type or CID is one of the two major iron ore types mined in the Hamersley Province. Channel iron deposits provided around 40% of the total of 394 Mt of iron ore mined from the Hamersley Province in 2009, and the current CID resource is around 7 billion tonnes. Channel iron deposits occupy numerous meandering palaeochannels in a mature surface that includes Precambrian rocks and ferruginous Palaeogene valley fill. These palaeochannels are generally less than a kilometre but can range to several kilometres in width and from one metre to more than 100 m thick. There are two currently mined CID areas: the first in the western Hamersley Province in the Robe palaeochannel, and the second in the eastern Yandi palaeochannel. These two major CID channels extend over 100 to 150 km, with the Robe system up to 5 km wide. The granular ore facies typically contains ooids and lesser pisoids with hematite nuclei and goethite cortices, with abundant goethitised wood/charcoal fragments and goethitic peloids, minor clay, and generally minimal porous goethitic matrix. Post deposition weathering is common and produced secondary facies. Ooids and pisoids were mostly derived from the stripping of a well-vegetated, deep ferruginous surface. The peloids were derived intra-formationally from both fragmentation and reworking of desiccated goethite-rich mud. Minute wood/charcoal fragments in the soil were initially replaced by goethite and then dehydrated to hematite, forming nuclei for many ooids and pisoids. In addition, abundant, generally small (<10 mm) fragments of wood/charcoal were replaced in situ by goethite within the consolidating CID. This profusion of fossil wood, both as ooids and pisoids nuclei and as discrete fragments, as well as the local presence of kenomagnetite suggests major episodic wild fires in heavily vegetated catchments. The goethitic matrix was the result of chemically precipitated iron hydroxyoxides, resulting from leaching of iron-rich soils in an organic environment.

Mineralogy and geochemistry of banded iron formation and iron ores from eastern India with implications on their genesis

The geological complexities of banded iron formation (BIF) and associated iron ores of Jilling-Langalata iron ore deposits, Singhbhum-North Orissa Craton, belonging to Iron Ore Group (IOG) eastern India have been studied in detail along with the geochemical evaluation of different iron ores. The geochemical and mineralogical characterization suggests that the massive, hard laminated, soft laminated ore and blue dust had a genetic lineage from BIFs aided with certain input from hydrothermal activity. The PAAS normalized REE pattern of Jilling BIF striking positive Eu anomaly, resembling those of modern hydrothermal solutions from mid-oceanic ridge (MOR). Major part of the iron could have been added to the bottom sea water by hydrothermal solutions derived from hydrothermally active anoxic marine environments. The ubiquitous presence of intercalated tuffaceous shales indicates the volcanic signature in BIF. Mineralogical studies reveal that magnetite was the principal iron oxide mineral, whose depositional history is preserved in BHJ, where it remains in the form of martite and the platy hematite is mainly the product of martite. The different types of iron ores are intricately related with the BHJ. Removal of silica from BIF and successive precipitation of iron by hydrothermal fluids of possible meteoric origin resulted in the formation of martite-goethite ore. The hard laminated ore has been formed in the second phase of supergene processes, where the deep burial upgrades the hydrous iron oxides to hematite. The massive ore is syngenetic in origin with BHJ. Soft laminated ores and biscuity ores were formed where further precipitation of iron was partial or absent.

Alternativas para classificação de recursos minerais: métodos geoestatísticos tradicionais

A dificuldade na quantificação do grau de incerteza associado com a estimativa de recursos minerais tem levado ao desenvolvimento de uma gama de metodologias, termos e definições. Isso gerou uma situação em que praticamente cada companhia de mineração possui sua metodologia particular de classificação. Intuitivamente, sabe-se que os métodos tradicionais utilizados na avaliação de recursos não levam em consideração a continuidade espacial dos teores e, mesmo que algumas metodologias baseadas em métodos geoestatísticos são incapazes de fornecer uma medida do erro associado às estimativas. Nesse sentido, esse artigo se propõe a desenvolver uma metodologia que permita uma análise quantitativa e qualitativa dos recursos minerais estimados por meio da incorporação da incerteza e da adequada definição do risco ou erro associado às estimativas. Um estudo de caso com um banco de dados de minério de ferro típico foi efetuado, permitindo uma comparação, tanto entre os diferentes sistemas de classificação, como entre os parâmetros-chave de cada sistema, sendo que os resultados obtidos permitiram ressaltar as limitações específicas de cada metodologia, além de demonstra a natureza empírica dos métodos tradicionais, devido ao seu caráter predominantemente subjetivo.

Assessment of evolution of loss on ignition matter during heating of iron ores

Ironmaking involves reduction of iron ores to metallic iron using coke, coal or gas as reductants. Although different iron ore reduction processes exist, prior to each reduction type, commonly, the hydroxyl and clay materials present in the iron ores undergo decomposition as a first stage. The mass loss during decomposition of these materials is termed as Loss on Ignition (LOI). The aim of this work is to apply a computer aided thermoanalytical technique to evaluate five different iron ore types during decomposition of the LOI matter and determine associated decomposition temperature ranges and heats of reactions. Fourier Transform Infrared (FTIR) spectroscopy and thermogravimetric analysis (TG) were also incorporated to support the analysis interpretation. Three distinctive temperature ranges of decomposition of iron ore LOI matter were detected. The first region was associated with dehydration of the hygroscopic moisture at a temperature range between 100 and 150 °C. The second region occurred at a temperature range between 260 and 425 °C during which strongly bonded water was released and the OH groups associated with primarily iron oxyhydroxides were fractured. The third range, which occurred at a temperature range of 530 and 605 °C, was related to decomposition of the aluminosilicate clay materials.

Utilizing a Value of Information Framework to Improve Ore Collection and Classification Procedures

This case study utilizes a value of information decision framework to provide mine managers guidance regarding the purchase of ore grade scanners. LKAB's Kiruna mine produces three types of iron ore to meet long-term contractual agreements on a monthly basis. There is a priori uncertainty regarding the ore type in any given mineable section of the orebody. In addition, there is extracted ore type uncertainty that is introduced by the mining process. These uncertainties are better understood by obtaining more precise (real-time) information. In addition, a better understanding of the uncertainties can improve the quality of operational decisions and increase the overall profitability of the mine. This case study provides a framework for measuring the economic impact of information purchases in a mining context and discusses the implications of those findings.

Biotar Ironmaking Using Wooden Biomass and Nanoporous Iron Ore

This paper describes fundamental experiments of a new biomass ironmaking that employs low-grade iron ore and woody biomass for promoting the direct reduction, FeO + C = Fe + CO, in which dehydrated, porous limonite iron ore was filled with carbon deposited from the biomass tar, biotar. In our experiments, three types of iron ores containing different amounts of combined water (CW; 1.6, 3.8, and 9.0 mass %) were first dehydrated at 450 °C to make them porous and then heated with pine tree biomass at 500−600 °C for the gasification and the tar vapor generated was decomposed to deposit carbon within/on the porous ores. The dehydration treatment made the iron ores porous by removing CW and significantly increased their Brunauer−Emmett−Teller (BET) specific surface areas and porosities. In the second treatment of biomass gasification and decomposition of tar vapor, the biomass was changed into char, tar vapor, and reducing gas; the biotar was decomposed and carbonized within the porous ores. Interestingly, the...

Granulometric optimisation of raw materials for ISF continuous segregation system in Usiminas' sintering plants

This paper describes the improvement in the operational results obtained in the sintering unit of Usiminas' Steel Works, located at Ipatinga, one of the integrated steel plants in Brazil, after incorporation of intensified sifting feeder in the sintering circuit. Beneficial results came about after extensive investigations involving alterations to particle sizes of the feed material comprising of different types of iron ore, limestone, solid fuels and other additives such as serpentinite. The present work describes the methodology developed for sampling, including variations in the particle sizes of the feed mix, and their effect on the operational results of the sinter plant in respect of productivity and quality of sinter produced. The beneficial effect of serpentinite additions has been confirmed.

Goethite Morphology and Composition in Banded Iron Formation, Orissa, India

AbstractIron ore deposits are generally described in terms of size, grade and chemical composition rather than the mineralogical and microstructural characteristic of different ore types. It is essential, however, to know the morphology, microstructure and chemical composition of individual minerals for optimum mineral processing. Goethite is reported to occur as a ubiquitous phase in many iron ore types and is particularly abundant in the Precambrian banded iron ore formation of north Orissa, India. Goethite from the Bonai–Keonjhar Belt in Orissa has been examined in terms of its morphology and microstructure in relation to chemical composition. Electron microscopy indicated several goethite morphotypes including botryoidal, nodular, spheroidal, platy, stalactitic and flaky. These different morphotypes display intergranular, intragranular, wedge, reniform, comb, prismatic, cavity‐line and bead microstructures. In situ analysis using electron probe microanalyzer indicated a wide compositional variation among the different morphotypes and microstructures. Goethite replacing hematite is generally devoid of deleterious elements while re‐precipitated goethite generally contains adsorbed alumina, silica and/or phosphorus. Nodular goethite commonly has a high phosphorus level while botryoidal, spheroidal and platy goethite often contains increased combined alumina and silica. Goethite having a reniform, wedge, intergranular or intragranular microstructure is highly water bearing and cryptocrystalline in nature. During dehydration, bead, comb, cavity‐lined or prismatic goethite develop, which are more crystalline and which have a higher iron concentration. Goethite with a wedge, prismatic or bead‐type microstructure has a higher adsorption of silica (2–4%), while goethite having an intergranular, bead or prismatic microstructure invariably contains appreciable phosphorus, generally at levels deleterious to processing.

Predicting Granulating Behaviour of Iron Ores Based on Size Distribution and Composition

Increased demand and diminishing high grade resources have resulted in a large diversity of iron ore sources used in the modern steel mill. Using research on the effect of ore type and size on granulation for single ore blends containing coke, flux and returns, this paper presents a study to model the optimum granulating moisture and related green bed permeability of an iron ore from the size distribution and composition of the ore when added in a simplified sinter blend.The models developed from the granulation test work are applied to a broad range of iron ore types and blends. The effect of particle size on granulation is also quantified across a range of iron ore types.It was found that the optimum moisture could be described accurately by knowing the ore's SiO2, LOIT and Al2O3 (−1 mm) content, as well as the −0.15 mm and percentage of Intermediate (0.1 to 1 mm) size fractions. It was also found that for most iron ores, an increase in particle size close to the 0.1 mm size range has the greatest effect of reducing permeability and increasing granulating moisture.