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By W. S. Kirk

World cobalt production in 1987 was estimated to be about 26,600 metric tons (MT) of which Market Economy Country (MEC) production was estimated to be about 22,000 MT. Zaire and Zambia produce about 80 percent of the primary cobalt produced among Market Economy Countries (MEC). Production cutbacks. lowering cobalt grades and mining curtailments in Finland and Zambia in 1987, resulted in lower production than that of 1986. The trend is expected to continue through 1988. Cobalt production from Canadian ores and from Botswana is expected to increase significantly in 1988 as a result of increased nickel production. MEC production in 1988 is estimated to be 22,100 MT, only slightly higher than that of 1987. There are currently no primary cobalt mines. Virtually all cobalt is recovered as a byproduct of copper and/or nickel mining. Zaire, which produces cobalt as a byproduct of copper, is the worlds largest cobalt producer, with over 50 percent of total estimated world cobalt production and nearly 65 percent of MEC production. Zambia follows with about 14 percent and 17 percent, respectively. Zambia's cobalt production also results from copper production.

Jan 1, 1988

By José L. Carvalho

"Time-dependent swelling deformation of several shaley rock formations in Ontario is a wellknown phenomenon. In shales and mudstones with a higher salt concentration in the pore fluid than the ambient fluid, the outward gradient generates an osmotic pressure which acts as the driving force for swelling. The swelling phenomenon appears to be related to ion exchange between the rock porewater and the surrounding water.The swelling potential is expressed as the percent swelling strain that occurs per log cycle of time, in either the vertical (perpendicular to bedding) or horizontal (parallel to bedding) directions. In addition, the swelling potential is also noted to be stress dependent. In practice, therefore, the conditions required for swelling are (i) the accessibility to water, and (ii) an outward salt concentration gradient from pore fluid of the rock to the ambient fluid. The relief of in-situ rock stress during excavation serves an initiating mechanism (Lo and Micic, 2010).INTRODUCTIONTime-dependent swelling deformation of several shaley rock formations in Ontario is a well-known phenomenon. In shales and mudstones with a higher salt concentration in the pore fluid than the ambient fluid, the outward gradient generates an osmotic pressure which acts as the driving force for swelling. Swelling is also controlled by the inter-particle bonding; if the bond strength exceeds the osmotic pressure, swelling will not occur, and vice-versa. The bond strength can be reflected by the calcite content which forms cementation bond between rock particles."

Jan 1, 2015

By Volker Vogt, Wolfgang Sand, Eberhard Gock

"It was discovered that the selective activity of bacteria during the extraction of raw material concentrates by means of flotation could also be achieved with extracellular polymeric substances (EPS) excreted by bacteria. EPS, which is extracted by means of centrifuging bacterial cultures, can help to significantly reduce the use of cyanides, approximately 200,000 t/a of which are used for ore dressing today.The bacterium used was Acidithiobacillus ferrooxidans. In order to identify the bandwidth of the oxidation activity, 20 bacterial strains of the strain collection of the University of Hamburg were attracted to iron(II) sulfate and pyrite under defined conditions. All strains oxidized iron(II) sulfate ten times faster than pyrite.EPS has so far been derived from four strains. In general, EPS extracts are divided into a hydrophilic and a hydrophobic fraction. The hydrophilic fraction is composed of e.g. fucose, rhamnose and glucose; fatty acids such as dodecanoic acid, hexadecanoic acid, octadecanoic acid and nonadecanoic acid were found in the hydrophobic fraction.Pure mineral phases and mineral mixtures were used for the flotation tests. As opposed to current knowledge, the results were reproducible with technical flotation machines."

Jan 1, 2003

By Nikhil Dhawan, Shrey Agrawal, SHAILA MIR

The current study investigates the effect of microwave processing on low-grade banded iron ore using charcoal, coking coal, and non-coking coal. Charcoal showed better microwave heating response at low temperatures, and the coals exhibit better heating response at higher temperatures. Low carbon dosage ~ 12% is sufficient to generate concentrate with 61.8% iron grade and ~6% for 94.8% iron recovery comprising of magnetite phase suitable for iron-making applications. The process separation efficiency of ~ 95% is achieved at 6% carbon dosage and decreases with an increase in carbon due to formation of the fayalite phase. The metallization degree showed a strong dependency on reductant dosage and achieved amaximumvalue of 22.7%at 18%charcoal. The comparison of ore with pure iron oxide and the synthetic mixture of iron oxide indicated that the underlying bonding due to banded structure enhances the Joule heating during microwave irradiation and thereby aids in attaining higher temperature and better separation.

Sep 21, 2020

By Pengfu Tan

A thermodynamic model and computer program, CuModel, has been developed to model the distribution behaviors of Cu, Fe, S, O, Ni, Co, Sn, Pb, Zn, As, Sb, Bi, Au and Ag, copper loss in the slag, and heat balance in copper smelting process, matte converting process and copper con-tinuous smelting process. It can be predicted for any set of controllable process parameters such as feed composition, smelting temperature, degree of oxygen enrichment and volume of oxy-gen-enriched air. This model accounts for physical entrainment between matte and slag phases. It can be used in Isasmelt process, copper flash smelting process, Mitsubishi process, P-S con-verting process and Noranda process. The predictions by the present computer model are com-pared with the known commercial data from Guixi Smelter in China, PASAR Corporation in Philippines, Horne Smelter in Canada, MIM Limited in Australia and Naoshima Smelter in Ja-pan. The agreements between the computer predictions and the commercial data are excellent. In this paper, the applications of CuModel in the copper metallurgical industries have been pre-sented. CuModel has been used by Daye Smelter and Guixi Smelter in China, and by PASAR in Philippines as well.

Jan 1, 2004

By M Carr, C Wheeler, M Lurie, B Chen

The demand for steel products in modern society is prompting the iron ore industry to optimise their operations to ensure sustainability of fines and lump products. One of the key components in the iron ore transportation chain are belt conveyors. The energy consumption of modern belt conveyor systems has reduced considerably over the past few decades, however, there is still significant scope for further reductions, especially when heavily loaded long overland belt conveyors are considered. A new rail based continuous bulk material transportation system has been developed by researchers at the University of Newcastle to reduce the energy consumption of heavily loaded and long overland conveyors. The Rail-Running Belt Conveyor technology is a state-of-the-art continuous belt conveying technology which provides an innovative and novel departure from conventional continuous bulk material transportation systems with significant energy and economic benefits. This paper presents an overview of a Rail-Running Belt Conveyor variant which considers an enclosed belt. Enclosed belt conveying has the benefits of encapsulating the bulk material, and thereby reducing dust emissions and moisture ingress, in addition to being able to negotiate smaller radius horizontal and vertical curves leading to greater flexibility. To quantify the primary differences between conventional conveying technologies, the Denver office of thyssenkrupp Industrial Solutions (USA) developed a case study for an 11 km long conveyor. The conveyor design throughput was 2750 t/h and included a small net elevation loss of 10 m. When considering CAPEX the Rail-Running Pipe Conveyor equipment supply cost is approximately 45 per cent of the cost of a conventional pipe conveyor, while savings upwards of US$50M emerge for CAPEX combined with five years of OPEX. The savings vary with the topography and density of the bulk commodity, with iron ore generally showing increased savings because the high bulk density increases rubber losses in conventional conveyors.

Nov 8, 2021

By G P. S Resende, D E. G Oliveira, E A. S Baeta, T F. Bravin

There is currently in the mining industry, as well as in other industries, a movement seeking to increase investments in decarbonisation processes to help combat global warming. Among some initiatives taken is replacing diesel-powered mobile equipment in the mines with electricity-powered equipment, such as electric off-highway trucks or even belt conveyors in the mining operation. Samarco is a Brazilian mining company that since its conception has used a conveyor belt mining system in its mining operation, using only a small number of trucks to complement the mining process. This mining process that combines conveyor belts and trucks has brought environmental gains for the company since the environmental impact of conventional truck-only mining is greater than that of the combined system. To measure these gains, a medium-term mining plan was developed in which two fleet scenarios were detailed. One scenario contemplated a high level of detail of belt mining seeking its maximisation, while the other considered the operation performed 100 per cent by trucks, eliminating the use of conveyor belts. Through the comparison of these two scenarios, it was possible to make an inventory of atmospheric emissions and greenhouse gases for each one of them considering data such as types of equipment, diesel consumption, total distance travelled and energy consumption. The results showed that the fleet scenario with conveyor belts results in periods with up to 15 per cent less greenhouse gas emissions and 37 per cent less total particulates compared with the truck-only scenario. Therefore, the results confirm the environmental benefits of the method and the need to look for ways to even expand it in future operations through a study to identify the potential areas in the long-term mining plan.

Sep 18, 2023

By F. Shi , D. Lay, C. Antonio

High Voltage Pulse (HVP) technology has the potential to transform traditional mineral processing practice in the mining industry. HVP pre-treatment has been shown to enable ore preconcentration, achieve ore pre-weakening and improve mineral liberation. In order to improve the efficiencies of these novel HVP applications, it is essential to understand how HVP operational factors affect ore breakage in HVP pre-treatment. A two-level fractional factorial experiment using two rock samples, a gold-copper ore and a basalt sample, was performed to determine which factors have statistically significant influences on breakage probability, size reduction, and energy efficiency, and which factors have insignificant influences. Operational factors investigated include applied voltage, electrode gap, number of pulse discharges, the number of rocks being processed per batch, and rock size. In total, 1920 batch tests were conducted. For ore breakage characterised in terms of breakage probability and the degree of size reduction during HVP pre-treatment, the dominant factors were identified to be the number of pulse discharges, voltage, and the number of particles present in the processing zone. As all these three factors are related to the specific energy, it is concluded that the specific energy is the most important factor controlling ore breakage in HVP treatment. In terms of the efficiency by which spark energy is transferred from the generator energy, the factors found to have the most dominating influence were the particle size, the number of rock particles present in the processing zone and the voltage. Increasing the values of these factors reduced the loss of HVP energy during the energy transfer process. The factorial experiment using the two ore samples with vastly different mineralisation produced similar results. This proves that the dominant factors affecting HVP breakage are generally applicable to different ores types. Keywords: High voltage pulse, ore breakage, factorial experiment, specific energy

Jan 1, 2020

By Yinan Zhang, Y. Luo

Most of the reported coal spontaneous combustion events occur in surface and underground mines where low rank coals (i.e., subbituminous and lower for this particular studies) are extracted indicating their high propensities for spontaneous combustion. Low rank coals have high moisture content (15 to 45%) and are capable of absorbing more moisture in dried condition. However, it is hard to induce the initial stage of self-heating process for the low rank coal using the current laboratory R70 testing method — a method widely used in the coal industry. Like a sponge, dry low rank coals can absorb water vapor in the air while the heat contained in the moist air is transferred to coal and served as the required activation energy to initiate the coal self-heating process. In order to prove this theorem and quantify the effects, the R70 adiabatic oxidation testing method has been improved to introduce a controlled moist flow into the coal reaction vessel. Tests using the new method and its setup on low rank coals showed that the initial self-heating process of coal sample can be greatly accelerated by the added water vapor — impossible with the regular R70 method. Once the self-heating is sustained, the removal of air moisture can further accelerate the process.

Sep 17, 2021

By M. -B. Kime

This study applies attainable region analysis to optimise cobalt recovery from oxidised ores via reductive leaching with sulphur dioxide and sulphuric acid. The attainable region framework enables systematic visualisation of trade-offs between cobalt yield and sulphur dioxide loss, guiding reactor network design beyond conventional mass balance modelling. Experimental column leaching trials, supported by validation runs, were conducted under controlled flow and reagent conditions. Kinetic parameters for cobalt dissolution and sulphur dioxide consumption were used to simulate reactor trajectories and construct attainable region envelopes. To ensure hydrodynamic realism, residence time distribution tests confirmed partial plug flow behaviour with dispersion effects, justifying the use of hybrid reactor models in the attainable region simulations. The results revealed that increasing recirculation ratios improves cobalt yield while reducing sulphur dioxide losses, with attainable efficiencies exceeding 90% cobalt recovery and < 20% sulphur dioxide loss. Importantly, the study proposes practical reactor network configurations for future implementation, including staged percolation columns with intermediate mixing zones, oscillatory flow reactors, and modular fluidised bed systems. These designs offer scalable pathways to translate attainable region-based optimisations into industrial practice. Compared to traditional modelling, attainable region analysis provides a geometric decision support tool that captures multi-objective trade-offs and reactor interactions, offering novel insights for continuous leaching system design. This work advances the application of attainable region methodology in minerals engineering by bridging theoretical optimisation with practical reactor design, supporting sustainable cobalt recovery from both primary ores and recycled feedstocks.

Mar 30, 2026

By L. G. Austin

The model originally proposed by Austin, et al., has been modified in the light of further investigation of the breakage laws in SAG milling. The model uses a fully-mixed reactor for short L/D mills and calculates the breakage of small particles by the nipping action of balls and pebbles. The autogenous self-breakage of larger lumps is treated as an effective means of fast breaking rock and much slower breaking rock. Experiments show that fast autogenous breakage can be treated as a first-order breakage with an overall specific breakage rate which incorporates fracture and chipping. Similarly, slow breakage incorporates fracture and abrasion. Autogenous breakage is cushioned by the accumulation of fine material. Simulation results are compared to results from tests in a 2 m diameter continuous pilot-scale SAG mill. Future work is discussed.

Jan 1, 1985

By Y. Nishida, Y. Nara, T. Ishida

Understanding time-dependent deformation and fracturing in rock is essential, because the information of the long-term stability of rock is required for many sub-surface structures excavated in a rock mass. Time-dependent fracture propagation has been invoked as a potential key mechanism responsible for the increase in seismicity preceding earthquake ruptures. In engineering projects and in preventing natural hazards, the study of time-dependent fracturing is necessary. Subcritical crack growth is one of the main causes of time-dependent fracturing in rock. For silicate rocks, subcritical crack growth has been investigated by various researchers. It has been clarified that surrounding environmental conditions (temperature, humidity, and existence of water) have strong influence on subcritical crack growth in silicate rocks. Therefore, the information of subcritical crack growth in silicate rocks has already been enough. On the other hand, information of subcritical crack growth in carbonate rocks is not enough. Especially, the influence of surrounding environment on subcritical crack growth in carbonate rock has not been clarified yet. In this study, we investigate subcritical crack growth in carbonate rock experimentally using a fracture mechanics testing method. Marble obtained in Skopje in Macedonia is used as a carbonate rock sample. The Double Torsion method is used to measure the crack velocity and stress intensity factor. Especially, influence of water on subcritical crack growth in Macedonian marble is investigated. It was shown that the crack velocity in water is much higher than that in air at the same temperature. Based on the results of subcritical crack growth measurements, the long-term strength is evaluated for marble. It was clarified that the long-term strength in water is lower than that in air in marble. It is concluded that water has a remarkable influence on subcritical crack growth in marble. It is also considered that the long-term stability of carbonate rock masses should be ensured in a dry environment.

Jan 1, 2015

By Houquan Zhang, Ming Li, Guimin Zhang, Bei Zhang

"The support quality of bolts in deep roadways is one of the important factors for efficient and safe coal production. A new kind of non-destructive testing technique and equipment was used to monitor the axial bolt load in real time in deep roadways. Based on the test results, the working status of bolt support in deep roadways was evaluated. The research results show that the variation characteristics of axial bolt load is consistent with the distribution characteristics of rock pressure no matter whether it is in the initial support stage or mining disturbance stage. The axial load of bolts located 20m outby the development face has an overall rising trend within 3-5 days after installation. Within a certain distance in the front abutment pressure zone in front of the face, the axial bolt load increases with the advance of coal extraction. When coal and rock in the abutment pressure zone yield, the axial bolt load is dropped correspondingly. This kind of non-destructive testing technique provides an advanced means of detection and evaluation on bolt support quality.INTRODUCTIONMany coal seams more than 800m deep are being mined in eastern China. Roadways of large cross-section are being developed in coal seams more than 600m deep in western China (Kang et al. 2014). Moreover, these roadways are commonly supported by roof bolts and have encountered many support problems, including soft rock strata, intense mining disturbance, and abnormal tectonic stress. The stability of its surrounding rocks is difficult to maintain, the roof bolt even fails before mining (Shen 2014; Jiang et al. 2015). Therefore, it is very important to develop an effective method to detect the bolt quality in real time and evaluate the bolt's safety status.During installation of roof bolt, the installation quality is heavily affected by installation equipment and tools, field conditions, and operators' skills (Li et al. 2005; Shan 2009). The anchorage length will be shorter than the designed one if the resin cartridges are pushed to the bottom of excessively long drill hole and stay there without being shredded and mixed. The support function of the bolt would be weakened by the shorter anchorage length."

Jan 1, 2016

By H. Z. Kuyumcu

Coking of coal blends using high volatile coals with poor coking abilities to produce a high quality coke for blast furnace application can be achieved by compacting the coal blend prior to the carbonization process. Here densification up to a relative material density of 80 %, i.e. a compact density around 1100 kg/m3, has proven to be advantageous. Coal is compacted by stamping, if the so-called stamp charging process applied. Compacting of the coal by pressing is practised in case of the cokemaking with so-called heat-recovery ovens. Stamped and pressed coal cakes require over the cake volume uniform high density and mechanical stability. Besides the aspects of the coal selection, the efficiency of the process is mainly determined by the operating parameters compacting time and compacting energy for coal cake making. At the Department for Mechanical Process Engineering & Solids Processing of the Technical University Berlin the two sub-processes of densification and strengthening during stamping and during pressing are theoretically and experimentally investigated using specially developed lab-scale compacting test units and a strength test device. Describing cake density in terms of coal properties for a given coal and measured compacting energy input then leads to a compacting equation with the so-called Stampability as the integral model parameter for the stamping process. For the pressing process the cake density can be calculated with the measured compacting pressure and the Compressibility factor, respectively. Investigations were carried out to provide evidence of a significant influence of coal type, coal surface moisture, coal granulometric and mechanical properties on the densification process. The overall objective of the work is to establish a comprehensive mathematical model on the compacting behavior of large coal bulk quantities and the optimization of the compacting processes by stamping and by pressing. Keywords: coal compacting, agglomeration, stamping, pressing, cokemaking

Sep 1, 2012

By Krishna Parameswaran

This paper illustrates sustainability considerations in copper hydrometallurgy using examples of practices at ASARCO LLC, an integrated U.S. primary copper producer. Using the classic Brundtland Commission development of sustainable development, i.e., “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper discusses how copper hydrometallurgical processes can be sustainable. The examples used to illustrate sustainable development and related concepts include: water conservation opportunities in milling and leaching operations; implementing green chemistry and promoting product stewardship in the electrorefining of copper.

Coal-derived flue gases contain CO2/SO2 and these contaminants preferably have to be captured by cheap sorbents. This remediation approach is from the standpoint of addressing issues such as global warming, acid rain and development of Advanced Power Generation Systems and to realize the economic gain as well. Conventional and existing dry scrubbing technologies use regenerable sorbents which are pollutant specific and require expensive stabilizers in order to attain versatility. This paper discusses the use a novel class of sorbents prepared from the heavy metal contaminated Berkeley Pit water (Butte, Montana) by a proprietary process developed at The University of Nevada, Reno. These sorbents are activated mixed spinel ferrite (MxFe,_X04)&apos; Preliminary experimental results show that the sorbents have good desulfurization and CO2 decomposition capacities. The decomposition effectiveness of these mixed spinel ferrites was studied at 300°C and compared against the synthetic magnetite obtained from ferrous sulfate solution in our laboratory. The results indicated that the mixed spinel ferrite had good affinity for the adsorption and decomposition. The CO2 decomposition data of both sorbents fitted the first order reaction kinetics. Even though the surface area of the magnetite was higher than that of mixed spinel ferrite, the CO2 decomposition rate of the mixed spinel ferrite was estimated to be 2.5 times higher than that of magnetite under identical conditions. The carbon analysis deposited on the sample indicated that the CO2 was 100% decomposed into carbon and other carbon! hydrogen compounds by the mixed spinel ferrite whereas the conversion was 43% by the magnetite. In terms of specific adsorption of carbon, ferrite was 3-5 times more efficient than magnetite.

Jan 1, 1996

By Gudrun A. Saevarsdotti

For decades tile aluminium industry has been practicing gas treatment of aluminium melts. This treatment is of great importance because of its influence on &apos;impurity" and inclusion removal from the melt. The gas-melt interaction is greatly influenced by the gas composition, melt temperature etc. This paper gives an overview of the interaction between argon-chlorine gas mixtures and the aluminium melt. It covers the thermodynamics of the reaction between the chlorine and a number of different elements commonly found in liquid aluminium, and discusses the behaviour of reaction products in the melt. The paper reports an experimental study of the behaviour of the chlorine-molten aluminium interface, using sodium contaminated aluminium melt with and without the addition of grain refiner.

Jan 1, 1996

By Yan Zeng

Lithium metal silicates (Li2MSiO4, M = Fe or Mn) composed of abundant and non-toxic elements are important cathode materials for Li-ion batteries (LIB). In contrast to solid-state or sol-gel methods, hydrothermal synthesis conducted in pressure reactors is a favorable processing route as it provides the potential for scalable production and is environmentally benign. However, the key is to control the precipitation reaction to obtain powders with desired properties to meet battery specifications. Through a systematic study, we have found that Li2MSiO4 with tunable size from 300 nm to 1.5 μm can be produced by adjusting precursor concentrations, temperature, and reaction time. Under optimum conditions, high purity Li2MSiO4 with minimum defects were successfully produced and examined as an LIB cathode. The use of complexing agents promoted the formation of unique hollow particles via the self-assembling of elongated crystals. A four-step formation mechanism is proposed based on extensive characterizations with XRD, HR-TEM, SEM, and Mössbauer spectroscopy.

By KNona C. Liddell

"Many metal recovery processes involve heterogeneous reactions in porous media accompanied by fluid flow and mass transfer. Modeling such systems is difficult because of the number of rate processes involved and is complicated even further by effects due to the structure of the porous medium. Data on even bulk properties of the medium are often severely limited or unavailable. For many such systems, a cell model may provide an attractive alternative to models based on transport mechanisms in a differential volume. A cell model requires less input data and is computationally efficient. Identical residence time distributions can be obtained with models of both types, and both allow conversion and concentration profiles and histories to be calculated. The formulation and properties of cell models for metals recovery are described in detail.INTRODUCTIONSubsurface mineral leaching, metal ion recovery and environmental remediation are significant modeling challenges. They involve one-, two-, or three-dimensional reactive flow in multi reaction open systems. Dissolution, adsorption, and ion exchange occur at reactive mineral surfaces, and these heterogeneous reactions are accompanied by acid-base, complexation, and redox reactions in the solution phase.Two approaches have been taken to reactive flow problems in geologic media: mixing cell and transport models. Mixing cell models, the subject of this review, are based on a network of connected cells, each with a specified number of input and output streams. Mixing cells are assumed to have no internal solute concentration gradients, that is, each cell behaves like a well-stirred tank. Gradients are represented by step changes between connected cells; this results in a model that is spatially discretized at the outset. Different methods of discretizing the model equations are considered more fully below. Although this is not strictly necessary, it has usually been assumed in subsurface flow applications that all cells in the network have the same volume and identical initial properties."

Jan 1, 1996

By D. B. Apel

As depths to the ore bodies keep increasing around the globe, the problem how to deal with the increasing temperature of undisturbed rock mass becomes very important. In extreme cases the rock temperature at the bottom of the mine could raise up to 80 °C. In deep mines, geothermal heat is considered as the primary heat load contributor, which accounts for 50?90% of the total heat load depending on different geological conditions. Thus the geothermal heat control in underground mines is the most important and demanding issue to ensure a suitable working environment. In this study, expanded perlite aggregate (EPA) was incorporated as a lightweight substitute for sand. Five mixtures were prepared using 0, 25, 50, 75 and 100% replacement ratios of sand by EPA. These, mixtures were tested in the laboratory for both the insulating and strength properties of the developed shotcrete. The goal of this research was not only to develop shotcrete which would exhibit good insulating properties but also which would exhibit strength properties similar to the regular shotcrete. This paper not only reports the results of the laboratory tests but also discusses the output of numerical model which was performed to evaluate the benefits of using the insulating shotcrete in reducing the cooling costs at hot underground mines.

Aug 1, 2013