Geometallurgy

A geometallurgical model is currently built in two different ways. The first and the most common way relies on geometallurgical testing, where a large number of samples are analysed for metallurgical response using small-scale laboratory tests, eg Davis tube testing. The second, mineralogical approach focuses on collecting mineralogical information over the orebody and building the metallurgical model based on mineralogy. At Luleå University of Technology,
Sweden, the latter method has been adopted and taken further in four ongoing PhD studies. The geological model gives modal composition by the help of element-to-mineral conversion and Rietveld X-ray diffraction. Texturally, the orebody is divided into different archetypes, and liberation measurements for each of them are carried out in processing fineness using IncaMineral, a SEM-based technique. The grindability and liberation spectrum of any given geological unit (sample, ore block, domain) are extrapolated from the archetypes. The process model is taken into a liberation level by mass balancing selected metallurgical tests using the particle tracking technique. The approach is general and can be applied to any type of ores. Examples of ongoing studies on iron and massive sulfide ores are given.

The access to real geometallurgical data is very limited in practice, making it difficult for practitioners , researchers and students to test methods, models and reproduce results in the field of geomet-allurgy. The aim of this work is to propose a methodology to simulate geometallurgical data with geostatistical tools preserving the coherent relationship among primary attributes, such as grades and geological attributes, with mineralogy and some response attributes, for example, grindability, throughput, kinetic flotation performance and recovery. The methodology is based in three main components: (i) definition of spatial relationship between geo metallurgical units, (ii) co-simulation of regionalized variables with geometallurgical coherence, and (iii) simulation of georeferenced drill-holes based on geometrical and operational constraints. The simulated geometallurgical drillholes generated look very realistic, and they are consistent with the input statistics, coherent in terms of geology and mineralogy, and produce realistic processing metallurgical performance responses. These simulations can be used for several purposes, for example, benchmarking geometallurgical modelling methods and mine planning optimization solvers, or performing risk assessment under different blending schemes. Generated datasets are available in a public repository.

Increasing competition in the minerais industry and fluctuating coramodity prices require new ways of saving energy, lime, and general operational costs. A good understanding of physical processing or pre-processing streams that can potentially cut these costs requires detailed analyses of chemical and physical behaviours and processing responses during rainera]. processing. It is very useful to perform a detailed mineralogical and micro-textural characterization of materials (ore, tailings, and waste) that addresses, among other parameters, particle and grain sizes, as well as particle densifies. The choice and/or corabination of the 'best' processing approaches is crucial for processing efficiencies, and can be established and verified by using automated mineralogy with the associated software. A sample of low-grade iron ore from El Volcan, Mexico, serves as an example to demonstrate in a step-by-step approach how QEMSCAN® analyses provide processing information. Elements under consideration include iron, phosphorus, and sulphur.

The emerging discipline of geometallurgy is becoming increasingly recognised as a discrete and high-value activity that reflects an ongoing trend towards more effective mine site integration and optimisation. Constrained sampling that reflects and defines inherent ore body variability is a key geometallurgical requirement. This requires use of larger numbers of low-cost physical testing which can be applied to small sample volumes suitable for defining natural variability. The AMIRA P843 GeMIII project (Geometallurgical Mapping and Mine Modelling) is a major industry-supported research initiative designed to develop new tools, methods and protocols to support geometallurgical integration. As part of this integrated research a new more rapid low-cost comminution test (GeM Comminution index) has been developed which can be employed as a front line tool for geometallurgical mapping purposes and predictive throughput modelling. The test has been designed to be inserted into routine assa...

Historical tailings are secondary sources due to the presence of some amount of valuables minerals and metals. Metal content that has not been recovered earlier is now coming into the focus due to the improvements in technology; decreasing grades in primary deposits, increase of metal prices, and rising of environmental issues. In this thesis, historical tailings from the Yxsjöberg mine have been characterized by a number of methods including elemental analysis, XRD measurements, optical microscopy observations, quantitative liberation analysis and SEM-based analysis. Elemental analyses have been done in bulk and size fraction samples. XRD measurements were conducted on four main samples, optical microscopy on all samples and SEM-based measurements on two main samples.
The results from characterization along with the information found in literature on the state of the tailings provided information about the society of minerals present in the tailings, grades of elements of concern and their corresponding distribution versus vertical profile and size fractions. Liberation condition of the scheelite phase and the accurate mineral chemistry of some important minerals were acquired. At the end of the characterization study, element-to-mineral conversion was used to quantify the presence of different minerals and their behavior in bulk and size fractions.
By considering the current state of the tailings (based on characterization test works, literature study on the last improvements of the mineral processing technologies), feasible and promising reprocessing methods were selected for further investigation. This involved magnetic separation, enhanced gravity separation and flotation.
Several separation tests using magnetic separators and the Knelson enhanced gravity separator were conducted in order to investigate the performance of the mentioned methods. The results showed that these methods are applicable to fulfill the corresponding separation tasks. Moreover, flotation method, which is nowadays used in processing of such mineral assemblages, has been recommended to test in future works.
As a conclusion, a process flowsheet is proposed. As mentioned before, the main components of this process plant includes magnetic separation (low intensity) to reject iron contaminants, magnetite and pyrrhotite. The Knelson enhanced gravity method allows to recover scheelite particles within the size range between 150 to 300 μm. Conventional froth flotation method is suggested to be utilized for recovering fluorite, chalcopyrite, helvite, bismutite and scheelite within the size range between 75 and 150 μm in processing route and 10 to 75 μm in another. For particles below 10 μm, containing considerable amounts of liberated scheelite particles, newly developed flotation methods including column flotation and flocculation flotation are recommended, although tests and optimization remain to be done for final approval.

ABSTRACT
The present study investigates the impact of the quality of lumps in iron ore mining systems and its implications for mineral reserve recovery rates. Improving the quality of lump ore, through simple yet innovative mineral processing, can maximize recovery of reserves, decrease waste generation, and increase the productivity and sustainability of mines by allowing transition to lower quality iron ores. Here, a case study is described in which both siliceous and dolomitic banded iron formation rocks (BIFs) were subjected to chemical, physical, and mineralogical characterization before undergoing beneficiation processes in pneumatic jigs and logwasher equipment. These processes were found to increase product quality and reduce the levels of contaminants, including SiO2, Al2O3, and fines. The gain in quality led to a reduction in the cut-off grade, from 60% to 58% Fe, while maintaining products specifications. Consequently, a 20% increase in the lump ore reserves was achieved, contributing to the sustainability of the mining system.

Mineral quantifications are challenging on Ni-laterites: XRD analyses provide useful information on mineral species present in samples but with limitations in the precise quantification of complex mineral assemblages containing different particle and grain sizes. The quantification of clay mineral rich samples presents particular challenges as described by Pevear (1989) and Reynolds (1989). Automated-SEM systems including MLA, Qemscan, and TIMA show also limitations with respect to the distinction of Mg-silicates with close chemical compositions (olivine, serpentine, talc, nontronite, saponite, pyroxene,…). MLA and Qemscan, and the associated software, provide analytical results as count proportions acquired by their respective detectors. These results are presented as element wt%. It should be noted, though, that these results are far from precise and need to be laboriously calibrated and converted in order to ascertain precise element wt% information that are necessary to calculate a structural formula of a mineral. The Mineralogic system allows very fast EDS analyses that provide element and oxide analyses that are acquired from Zeiss SEM analyses and are presented as precise element and oxide wt%. This Mineralogic methodology is a step change to methods employed by QMESCAN, MLA and TIMA. Mineralogic allows for each acquired EDS spectrum to have a matrix correction and peak deconvolution applied before a spectrum quantification. This methodology thus allows for accurate and precise elements quantification, which is subsequently classified using the designed mineral library. In contrast to MLA and Qemscan systems, Mineralogic data can be directly used to establish precise phase compositions, structural formulae, and to even distinguish mineral phases of very similar chemical compositions. The Mineralogic system enables the user to group mineral populations of minor chemical variation. The distinction and quantification of clay minerals and minerals that are grouped within the smectite group is only one field of application. An extensive database is currently under construction that allows a high-precision identification and distinction of minerals including those that were hitherto regarded as problematic with respect to their identification and, even more, quantifications.

Repositories of historical tungsten mining tailings pose environmental risks, but are also potential resources for valuable metals. They still contain large tonnages of useful minerals and metals, reflecting the inefficient extraction methods and/or low metal prices at the time they were mined. The focus of this study is to evaluate the technical viability of reprocessing the tailings to recover some of the contained valuable minerals and metals, as well as reducing the negative environmental impact associated with the tailings. Geometallurgical studies were conducted on drill core samples taken from the Smaltjärnen tailings repository of the closed Yxsjöberg tungsten mine, Sweden. The collected samples were characterized physically, chemically, and mineralogically. Knelson concentrator dry low-and high-intensity magnetic separation methods were tested as potential beneficiation methods. The tailings are dominated by the −600 to +149 µm particles. The highest concentration of tungsten (W) was 0.22% WO 3. Using a Knelson concentrator, scheelite (main W mineral) recovery was enhanced, with 75 wt.% tungsten recovered in the 34 wt.% heavy concentrate. Only 1.0 wt.% sulphur (S) reported to the non-magnetic fraction. Based on the findings, a methodology and a preliminary process flowsheet for reprocessing the tailings is proposed.

Characterization of ores from mine to concentration plants is a long-standing aim of many studies. However, only limited number of investigations have focused on comparing characterization techniques to track material’s properties from rock-size to downstream processes (i.e. ground-size). Such studies are necessary to assess the uncertainty of those techniques exploring their advantages and complementarity. Additionally, individual uncertainty of most common characterization methods i.e. 3D X-ray computed micro-tomography (CT) and mineral liberation analyzer (MLA) and their quantification cannot be directly measured. Thus, validation of results requires a constructive comparison amongst these approaches.
This work aims to constructively compare 3D CT and 2D MLA to measure the grade and particle size distribution (PSD) of a parisite-bearing sample and its processed ones in crushing and milling stages. With this purpose, the amount and grain size distribution of parisite (Ca(Ce,La)2(CO3)3F2) in a carbonate sample was measured in three forms: uncrushed (rock), crushed, and milled, using CT. After milling, the sample was sieved into five size fractions and each fraction was analyzed by MLA and CT. The amount of each fraction was used to back calculate the initial mass of parisite in the initial uncrushed sample. It is found that the mass of parisite estimated from grain mounts and the mass directly measured in the entire sample as measured using CT are in good agreement. CT yields more consistent results for coarser grain sizes, e.g. >56 µm, but significantly underestimates the mass % and PSD of finer size fractions. Above 56 µm, MLA shows inconsistencies, possibly due to sampling representability of grain mounts. For particles bellow 56 µm, MLA values are more representative although seemingly overestimate the content of parisite. We conclude that CT is the prime choice to measure an ore grade when the grain size is sufficiently large relative to the voxel size.

Mikheevskoye project is a porphyry Cu-Mo open pit mine located in Chelyabinsk region, Russia. Ore extraction started in 2011 and mineral processing started in late 2013. Mikheevskoye project is owned by the Russian Copper Company.


This study examines the effect of hydrothermal alteration zonality and geometallurgical ore body zonality on the mine planning and plant feed quality forecast. The study was conducted at Russian business unit of Outotec, which operates part of the processing plant in Mikheevskoye project.


The empirical part of the study was conducted in October 2013 - January 2014. Geological data for the study was obtained from Outotec office and Russian Copper Company geologists. Some geological data was collected through sampling campaign in the Mikheevskoye open pit. Additional data was gathered through the questionnaire which investigated how processing engineers working on site view the ore body. A questionnaire was distributed among Outotec and Russian Copper Company process engineers.


The results revealed that mine scheduling based on the geometallurgical zoning is potentially possible and feasible in case of porphyry ore deposits. In this case, twelve geometallurgical zones were determined theoretically. Application of hydrothermal alteration zonality helped improve forecast feed grade quality. Based on the results of this study, it was recommended to conduct additional exploration drilling, evaluate the process performance of the samples retrieved in the drilling and to update the model developed in this study accordingly. One of the key findings of the study was estimation of the new payback time for the project on the basis of current market situation.Mikheevskoye projekti on Venäjällä, Chelyabinskin alueella sijaitseva porphyry Cu-Mo malmin avolouhos. Malmilouhinta alueella alkoi vuonna 2011 ja rikastamon toiminta vuoden 2013 lopussa. Mikheevskoye malmiesiintymä ja rikastuslaitos ovat Russian Copper Companyn (RCC, Venäjän kupariteollisuus) omaisuutta.


Tässä tutkimuksessa tarkastellaan vesiliukenemisesta ja lämpötilagradientista syntyneiden muuttumisvyöhykkeiden sekä mineraalivyöhykkeiden (geometallurgiset) vaikutusta louhintasuunnitelmaan ja ennustettavaan rikastamon syötön laatuun. Tutkimusta toteutettiin Outotecin Venäjän alueyksikössä; sama Outotecin yksikkö vastaa vaahdotus- ja vedenpoistopiirin operoinnista Mikheevskoye projektissa.


Tutkimuksen kokeellinen osuus toteutettiin lokakuussa 2013 – tammikuussa 2014. Geologinen tieto tuli Outotecin ja RCC:n geologeilta. Osa geologisesta tiedosta oli kerätty paikan päällä avolouhoksesta näytteenottokampanjan merkeissä. Lisätiedot kerättiin kyselyllä, joka tutkii prosessi-insinöörien ymmärrystä malmiesiintymän piirteistä. Kysely toteutettiin Outotecin ja RCC:n prosessi-insinöörien keskuudessa.


Tutkimuksen tulokset osoittivat, että louhinnan suunnittelu perustuen mineraali- tai geometallurgisiin vyöhykkeisiin on mahdollista käytännössä ja on myös taloudellisesti kannattavaa porhyrymalmiesiintymissä. Tässä tapauksessa 12 teoreettista mineraalivyöhykettä oli otettu käyttöön. Vesiliukenemisesta ja lämpötilagradientista syntyneiden muuttumisvyöhykkeiden huomioon ottaminen auttoi tarkentamaan rikastamon syötteen laadun ennustetta. Tutkimuksen tulosten pohjalta suositellaan tuotantokairausten toteuttamista, niistä kerättyjen näytteiden analysointia prosessikäyttäytymisen osalta sekä tässä tutkimuksessa kehitetyn mallin päivittämistä ko. tulosten pohjalta. Tämän tutkimuksen yksi keskeisiä tuloksia oli uusi arvio projektin takaisinmaksuajasta nykyisten metallihintojen pohjalta.