Specific Ore Research Articles

Characterizing and recovering the platinum group minerals––a review

Methods of characterizing and recovering the platinum group minerals are reviewed in this paper. First, a classification of platinum group minerals (PGMs) ore types is briefly introduced, followed by the introduction of some representative platinum group minerals. Second, the sample preparation techniques for mineralogy studies are presented, followed by a brief introduction of instruments used for characterizing PGMs. Third, the mineralogy of specific ores amenable to gravity, flotation and the flowsheet for recovering platinum group minerals in several mills of interest are discussed in details. Finally, new research trends of recovering PGMs and conclusions are briefly presented.

Application of neural networks to predict locked cycle flotation test results

The performance of a continuous flotation circuit is influenced by the flotation variables and the number of stages of a flotation circuit is dependent on flotation conditions, such that the interrelation between the flotation conditions and the number of stages must be carefully determined to obtain acceptable metallurgical performance from the circuit. The locked cycle test is a useful tool for simulation of continuous flotation circuits. However, it is a time-consuming and tedious procedure. A simulation method used to predict locked cycle test results from data from individual batch tests is available in the literature. In order to develop an optimum circuit configuration for a specific ore, several batch flotation tests for the first cycle of the locked cycle test have to be conducted to predict the metallurgical performance of various circuit types. Therefore, an integrated simulation method, which uses experimental data and the results of this simulation method has been developed to structure a neural network model for prediction of locked cycle tests results without additional experiment and calculation. In training and testing of the neural network model, results of the simulation method were used as the output data set and the flotation conditions of the batch tests were used as the input data set. Apart from the training and testing data, results of the LCT for several circuit types were predicted in order to validate the neural network model and to determine its performance on both: interpolation and extrapolation. Because the neural network model was trained using results of the simulation method, the use of the neural network model did not lead to any improvement in predictions of actual LCT results. However, the results of this study indicate that the neural network model can be used to simulate various circuit types with an error of less than 4%, instead of the simulation method. Consequently, the neural network model, as an alternative to the simulation method, can be used to determine the effects of changes in certain flotation variables on the number of cleaner and scavenger stages in a flotation circuit.

Helium and Argon in Ore Fluids: So What?

The isotopic composition of He and Ar trapped in crustal fluids and fluid inclusions carries a signature of the source of the fluids and the processes which have affected them. There are three distinct sources of the noble gases; atmosphere, crust and mantle. Atmospheric gases carried in groundwaters are characterised by the presence of 36Ar and 4~ and minor amounts of helium (3He/4He = 1.39 x 10 _6 = Ra). The crust is a source of radiogenic 4~ and 4He, very low levels of3He (-0.01-0.05 Ra) and no 36Ar. The prime signature of the mantle is helium with a high 3He content (e.g. 3He/4HeMoRB ~ 8 Ra), together with 4~ and, in most situations, negligible 36Ar (4~ ~ 40,000). Fluids trapped in ore minerals frequently carry all three components (Stuart et al., 1995). We have investigated He and Ar isotopes, sometimes in combination with halogens, trapped in ore fluids from a variety of areas and types of mineralisation. Our aims have been to see what qualitative aspects of the mineralisation processes are reflected in noble gas patterns and to what extent these can be used to resolve conflicting interpretations, what aspects can be understood in a quantitative way, and whether these can be used, for example, to model the large scale features of specific ore deposits. In this report we contrast the He and Ar isotope observations from two widely separated porphyry-Cu deposits (PCD) with those from an MVT deposit. The Machangqing PCD deposit in West Yunnan province, China, is part of the Ailaoshan-Jinshajiang alkali-porphyry intrusive zone of Eocene age formed in an extensional setting. The mantle derived magmas intrude lower Ordovician microelastic rocks and Devonian limestone and appear to have assimilated some crustal material. The Sungun PCD is located in NW Iran and is associated with a series of calc-alkaline hypabyssal igneous intrusions of Oligo-Miocene age. The magma was emplaced in a continental margin tectonic setting related to the subduction and assimilation of the Persian plate during the major Alpine orogenic phase. The Sungun porphyries occur as stocks and dykes intruding a series of Oligocene dacitic breccias, tufts and trachyandesitic lavas, Eocene arenaceous-argiUaceous rocks, and UpperCretaceous limestones. The He and Ar compositions of gases released by crushing sulphides from the two deposits are shown in Figs. 1 and 2. 4~ is the only isotope present in high abundance in all components and consequently this is the only method of representing all the data, end members and processes in a single figure. Mixtures of three end members define a mixing plane, while elemental fractionation of He and Ar drive compositions radially from, and perpendicular to, the ASW axis. In both figures the data lie on 3component mixing planes. The three end members are fluids enriched respectively in atmosphere (ASW), mantle helium and argon ( label led EARLY) and crustal helium (labelled LATE). The 3He/4He ratios, 1.2 Ra (Machangqing) and 2.25 Ra

Mineral Resources, Environmental Issues, and Land Use

Contrary to predictions from the 1950s through the mid-1980s, persistent shortages of nonfuel minerals have not occurred, despite prodigious consumption, and world reserves have increased. Global availability of raw materials is relevant to policy decisions regarding mineral development and land use. Justification for environmental protection may exceed that for mining a specific ore body. Demand for environmental accountability is rising worldwide, and new technologies are enabling internalization of costs. Mineral-rich developing nations plagued by inefficient state-owned mining enterprises, high population growth rates, and environmental degradation could realize substantial benefit by reforming government policies to encourage foreign investment in resources and by appropriate allocation of mineral rents.

Flotation modelling: A wide range of solutions for solving industrial problems

Steady state simulation is now widely used for the design and optimisation of mineral processing plants. One of the most difficult unit operations to simulate in mineral processing is flotation. There are two main reasons for this. Firstly, the flotation circuits are made up of a number of streams of widely differing flowrates and compositions, which can make the collection of reliable experimental data time-consuming and expensive. The data generally available are thus limited in number and often subject to experimental error. Secondly, the flotation process is highly complex and controlled by many different hydrodynamic and physicochemical parameters. Many mathematical models exist which represent flotation, reflecting the variety of approaches with emphasis on different principal parameters, however, few of these models are effectively operational for industrial purposes, their usability depending on the data available. This paper presents the solutions to such problems provided by the USIM PAC 2 simulator. Several methods are possible, depending on the objectives of the simulation study and the data available, that require the use of data reconciliation algorithms, simple flotation models (flowsheeting) or much more complex models (liberation modelling). A detailed description is given of the flotation models embedded in the software enabling different parameters for specific ores and specific plants to be taken into account. The more detailed the model is, the greater the amount of data required for its use. Industrial examples are given to illustrate some of the uses and relative advantages of the different models.

The interrelationship between mineral liberation and leaching behaviour

The liberation characteristics of any ore are intimately related to the mineralogical texture. In this paper, leaching experimental results were used with the liberation model of King to predict the liberation of gold from complex ores. Diagnostic leaching results were used with the liberation model, as the results from a diagnostic leaching procedure explain the deportment of gold in the various minerals in a complex ore. The free or leachable gold in an ore obtained from such an experiment would be similar to the gold liberated by crushing and/or milling. The leachable gold in each size fraction of an ore can be determined by diagnostic leaching, before and after milling. Thus, it would be very useful if the leachable (liberated) gold in a specific unmilled ore can be used to predict leachable (liberated) gold in the milled ore of that specific ore. If this can be achieved, then the leachable gold in each size fraction of the unmilled and milled ore can be predicted by the model. An explicit solution to King's liberation model was modified in order to predict the leachable gold in different size fractions on the basis of data gathered for the unmilled ore. In this model, μ m is the mean linear intercept length for gold in the ore, and the term A· exp( 1 D ) indicates the fraction of leachable gold which cannot be attributed directly to liberation: L g(D)=2μ m/D 2[μ m−(μ m+D)exp(−D/μ m]+[A ·exp(1/D] It was found that this model gives reasonable predictions of the leachable gold for milled ore when the leachable gold in the unmilled ore is known.

On the ore producing potential of granitoids: experiences in the U.S.S.R.

A wide variety of structural, petrochemical, geochemical and mineralogical indicators have been suggested as indicators for the identification of ore-producing granitoids. This paper is concerned only with those indicators which have been found to be of practical use in the U.S.S.R. These may be classed as: (1) geological and structural indicators; (2) petrological and geochemical indicators; and (3) mineralogical indicators. Useful quantitative characteristics include such features as: the average content of accessory minerals in the granite; the average content of the specific ore element in minerals bearing this element; the average accumulation ratio between the ore element in early and late differentiates; and the average value of the difference between ore-element concentrations in the granite and in its rock-forming and accessory minerals. Use of these quantitative characteristics can distinguish between productive and non-productive granitoids, as well as indicate some of the processes which may have controlled the formation of ore deposits.

A model for the formation of the iron, manganese and sulphide ores of central Sweden

The non-apatitic iron ores, manganese ores and sulphide ores of central Sweden, which occur in a volcano-sedimentary complex of Early Proterozoic age, have a common volcanogenic origin. The close association between specific ore types and metavolcanics suggests a stratigraphic control of the ores on a regional scale. Deposited in basins, the ores formed with increasing water depth (increasing pH and decreasing Eh) in the following order: quartz-banded iron ores mostly lacking sulphides; non-man-ganiferous skarn iron ores with Cu-Fe sulphides; manganiferous skarn iron ores with Zn-Pb sulphides, and Fe2+-Mn2+ silicates (eulysites). The latter two ore types occur adjacent to argillites/greywackes indicating a reducing environment. The manganese oxide ores of the Langban type represent a formation intermediate between the quartzbanded iron ores and the manganiferous skarn iron ores.

A METALLOGENIC MAP OF THE WORLD

This describes a metallogenic map of the world, compiled at 1:22, 000, 000, which relates geologic structural elements with principal mineralization processes and recognizable regularities in the distribution of metallic ores. The structural elements delineated include two types of shield areas and five types of mobile folded zones, the latter distinguished on the basis of age of folding. The types of mineral deposits recognized are: 1) magmatic, 2) pegmatitic, 3) skarn, 4) hydrothermal, 5) sedimentary, 6) deposits resulting from metamorphism, 7) weathering, and 8) diamond deposits of all kinds. The specific ore deposits are classified as either 1) very large deposits of world importance, or 2) other industrial deposits. Shield areas are typically associated with such ore formations as metamorphic deposits of Fe, Mn, Au, U, sulfide deposits of Cu-Ni, and rare-metal pegmatites. Within mobile folded zones, mineralization usually manifests four successive stages, each characterized by a specific metallogeny ...

Ore and granitization

The process of granitization may be regarded as an approximate reestablishment of the geochemical equilibrium attained when the earth first cooled, but which was later upset by the large quantities of predominantly basic volcanic rocks brought into the sial by physical, as distinct from chemical, forces.On the basis of the granitization hypothesis, an attempt is made to explain the variation in composition of granitic rocks and of associated ore deposits during geological time by relating them to preceding volcanic activity. This leads to a possible explanation of the origin of some metalliferous provinces--e.g., the Western Australian gold province.Evidence is offered in support of the hypothesis that, in the process of the formation of a granitic rock, the valuable elements of ore deposits are concentrated in inverse ratio to the extent to which they are incorporated by isomorphous substitution in the common rock-forming minerals. This is held to explain, to a large extent, the association of specific ores with specific types of granitic rocks.Attention is drawn to the economic importance of distinguishing between synchronous and subsequent batholiths and suggestions are made for prospecting in areas in which synchronous batholiths occur.It is considered important to distinguish between ore deposits formed during a period of granitization and those of volcanic--or abyssal--origin: e.g., in the former case, given favorable conditions, some sort of zonal arrangement of the mineralization is to be expected; in the latter case, fluctuations in the depth of geoisotherms might easily cause ores, theoretically belonging to various depth-zones, to occur at the same vertical horizon.