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By A. Galibois, A. Dubé, H. Monette, J. L. Collins

"The start of mining operations often raises serious financial problems. In marginal cases promoters frequently demand financial aid from governments.In the past, the financial assistance has taken the form of gifts, procurement contracts, etc., but aid in such form has been severely criticized. A new formula has been developed to provide a more equitable distribution of the revenues accruing to the government and to private capital.The benefits to these two parties have been evaluated in an hypothetical case and compared in terms of internal rates of return on their investment, their shares of the undiscounted cash flows and their primary profits.The method based on the non-zero sum game theory provides a means for suggesting the lowest feasible annual production and the optimal sum contributed by the government in the form of outright gift, equity capital and convertible bonds. Other financial hypotheses can also be optimized by the computerized analysis."

Jan 1, 2014

By I. Ngo, L. Q. Ma, J. S. Guo

Deformation of gob-side entries has always been a critical concern for ensuring stability in longwall coal mines. This paper addresses the significant deformation and support challenges that arise in thick and hard roof longwall faces (THRLF) due to dynamic pressure. The study aims to elucidate the characteristics and mechanisms of deformation during the retreat of the longwall face. The research findings indicated that the primary cause of deformation was the combination of advanced abutment stress resulting from longwall face mining and the movement of the lateral roof over the chain pillar. To mitigate this issue, we propose a deformation control method known as cutting off the lateral roof (COLR) over the chain pillar. Simulation results demonstrate a significant reduction in roof stress and deformation of the gob-side entry after implementing the lateral roof-cutting technique. These findings provide valuable guidance for effectively managing deformation in gob-side entries, particularly when dealing with thick and hard roof strata.

Aug 3, 2023

By H. Askari-Nasab, S. Upadhyay, A. Moradi-Afrapoli

Material handling in surface mines accounts for around 50% of the operational cost. Optimum truck dispatching plays a critical role in the reduction of this operational cost in truck and shovel surface mines. Researchers in this field have presented several mathematical models to solve the truck dispatching problem optimally. However, a critical survey of the literature has shown that three significant drawbacks exist in the available truck dispatching models. The published models underestimate the importance of the interaction between truck fleet, shovel fleet, and the processing plants. They also disregard goals set by strategic-level plans. Moreover, none of the available models account for the uncertainty associated with the input parameters. In this paper we present a new truck dispatching model that covers all of these drawbacks, using a fuzzy linear programming method. The performance of the developed model was evaluated through implementatin in an active surface mining operation. The results show a significant improvement in production and fleet utilization.

Sep 1, 2021

By G. Akdogan, Q. G. Reynolds, S. J. Baumgartner

A computational model of a submerged arc furnace (SAF) used in the production of ferrochrome is presented. The model‘s intended use is to investigate the extent to which intrinsic and extrinsic properties of the raw materials affect burden distribution and electrical resistance within the furnace. The model is built on the discrete element method and calculates the mechanical interactions of particle distributions resulting from the flow motion of typical raw materials used in the smelting of chromium ore. This model excludes the effects of thermodynamics, furnace chemistry, and heat transfer. It illustrates how the consumption of materials (chromite pellets, flux, and reductant) is affected by changes in electrode length, reductant fractions, and reductant sizing and density during the formation of a reductant bed. The resistance calculation algorithm developed by Mintek was applied to construct networks developed from particle contacts, which can quantitatively generate estimates of the electrode-to-electrode and electrode-to-bath electrical conduction conditions.

Apr 16, 2024

By T. Fraszczak, U. A. Peuker, T. Mütze, O. Ortlepp

Dolomite is a calcium carbonate sedimentary rock that can be found all over the world. In its calcined form it is employed for water treatment or as an additive in iron production. Calcined dolomite is produced at the Wünschendorfer Dolomitwerk GmbH in shaft furnaces (kilns). Because of an expansion of the mined deposit, significantly higher extraction costs were expected. Therefore, the existing upgrading processes for the kiln stone fraction had to be adapted and improved. This paper presents a process optimisation which allows for an increase of the yield of calcined dolomite by 10 % due to a redesign of the crusher circuit and by an additional 5 % due to a comprehensive characterisation of the kiln stone fraction itself. Here the interdependency between the pressure drop in the furnace during calcination and the size distribution of furnace stones was used to increase the amount of fine size fractions in the furnace feed without deterioration of the calcination process. Keywords: Dolomite, crushing circuits, kiln stone production, flowability, calcination

Jan 1, 2020

By D. Weijie, S. Kai, Y. Hu, X. Ning, M. Shiyi, W. Junpeng, Z. Guihong, L. Xianjie

Flotation is one of the most important processes in the copper production industry. The copper grade in the concentrate is a pivotal indicator of the flotation process performance. However, it is difficult to achieve real-time measurement through hardware sensors. Based on the production data provided by an industrial operation, a novel soft sensor based on multi-layer perceptron (MLP) is proposed for effective monitoring of this pivotal indicator. The proposed soft sensor uses the nonnegative garrote (NNG) to perform global variable selection for MLP, while a local search (LS) approach is incorporated to improve the model presented by NNG. Simulation results show that the proposed algorithm has higher prediction accuracy and better model simplicity than other algorithms. Furthermore, the variables selected are consistent with the field experience, and the developed model can provide reference of feedback control for the optimisation of the process. Keywords: Flotation process of copper ore, nonnegative garrote, local search, soft sensor, multi-layer perceptron

Jan 1, 2020

By H. C. Voges

The concentration of cassiterite at Iscor's Uis Mine is described, and information is given on aspects of the concentration of iron ore at Thabazimbi and Sishen Mines. At Uis, a very Iow-grade tin ore is concentrated by three-stage jigging, spiral concentration, and tabling to give a high-grade concentrate with a recovery of 80 per cent of the tin. A Iow-grade tantalite-columbite concentrate is also produced. The possibility of recovering mica, the use of sluice boxes instead of spirals, and the recovery of cassiterite from minus 45 µm material are being investigated. At the two iron-ore mines, heavy-medium separation is applied to size fractions larger than 0,5 mm. The types of ferrosilicon and the circuits used for the recovery of ferrosilicon from the various dilute-medium circuits are described. The spiral-concentration plant being installed at Thabazimbi for the treatment of the minus 0,5 mm portion of the ore is described.

Jan 1, 1982

By A. Melkumyan, M. Balamurali, J. Zigman

Understanding the contribution of geophysical variables is vital for identifying ore indicator regions. Both magnetometry and gamma-rays are used to identify the geophysical signatures of the rocks. Density is another key variable for tonnage estimation in mining, and needs to be re-estimated in areas of change when a boundary update has been conducted. Modelling these geophysical variables in 3D will enable investigation of the properties of the rocks and improve our understanding of the ore. The Gaussian Process (GP) was previously used to generate 3D spatial models for grade estimation using geochemical assays. This study investigates the influence of the following two factors on the GP-based autonomously generated 3D geophysical models: the resolution of the input data, and the number of nearest samples used in the training process. A case study conducted on a typical Hammersley Ranges iron ore deposit using geophysical logs, including density, collected from the exploration holes, is examined in this paper.

Sep 1, 2021

By E. E. Almási, G. Mucsi, G. Rákhely, Á. Rácz, B. Csőke, Zs. Pap, K. Bohács, N. Halyag

Wet stirred media milling is a widely applied grinding process in the field of mineral processing to produce <10 μm ground materials. In this paper, the results of wet stirred media milling of different Ti, Fe and Cu-oxide and phosphate minerals are presented. During the experimental work, grinding of ilmenite, vivianite, hematite and cuprite was carried out in a continuous operation wet stirred media mill. During the experiments, the particle size distribution and specific surface area of the ground materials were determined after a certain grinding time, as well as measuring the specific grinding energy, thereby determining the grinding kinetics of the different minerals. The measurement results showed the differences and similarities in the grindability of the individual minerals. Nano particulate vivianite, hematite and ilmenite was successfully manufactured in a stirred media mill; however cuprite was characterised as the coarsest final product for the same grinding circumstances. Keywords: Wet stirred media mill, cuprite, vivianite, ilmenite, hematite

Jan 1, 2020

By P. L. Moolman

An approach to the design of a tailings disposal system is presented using an example from a platinum project on the eastern limb of the Bushveld Complex as a base case. The design is driven by two inputs: namely, maximizing water recovery and minimizing power cost, expressed as cubic metres and kilowatts per ton of solids deposited on the tailings storage facility respectively. The approach considers low-, medium-, and high-density platinum tailings and uses material-specific aspects such as thickening and rheology to determine the most economical option. An analysis based on direct capital and operating cost (water and electricity) shows that the medium-density scenario results in the lowest total cost per ton of tailings deposited, even though this system results in the highest electricity consumption per ton of tailings deposited. As the cost of water and electricity is likely to increase in the future, the higher-density tailings disposal options become more economical, with the paste option the preferred option.

Jan 1, 2012

By N. B. Strydom

The data on heat stroke cases reported during the past five years were examined to determine the influence of age on the incidence of heat stroke. Relating the age distribution of these cases to that of the total number of Bantu mine workers showed clearly that the older men run a significantly higher risk of developing heat stroke than the younger men. Although the number of Bantu over 40 years of age in the industry is less than 10 per cent of the total they nevertheless accounted for 50 per cent of the fatal heat stroke and 25 per cent of the nonfatal heat stroke cases during the period under review. Age must, therefore, be recognised as a causal factor in heat stroke and the worker over 40 years of age should be allocated to work on surface, or in cool areas or to non-strenuous and supervisory tasks in hot areas.

By D. G. Krige

The scope and salient features of a general risk-analysis model for the main types of new mining ventures are covered in brief outline. The following special features and their effects on the investment criteria are discussed: - various criteria for viability, - the maximum shortfall of funds, - correlations between the grades of up to five ore constituents and between the corresponding product prices. differential inflation and escalation rates for costs and prices, - the estimation, if relevant, of a pay limit based either on the major product only, or on the two major products jointly, - the likely recovery grades of all the products to be obtained when the ore-body is mined to any such pay limit. - an option to take account of the effect on the pay limit of any negative taxation on marginal ore, - investment analyses in current and real terms for individual groups of investors subscribing for equity and any loan capital on differential terms.

Jan 1, 1979

The 89th Annual General Meeting of The South African Institute of Mining and Metallurgy was held at Kelvin House, Johannesburg, on 20th August, 1986. Mr. H. E. James (President) was in the chair and declared the meeting open at 16hoo. Obituaries President: It is my sad duty to announce the deaths of the following members of this Institute: Life Fellow D.L. Carson; Retired Fellows T.K. Adams, G.E. Carlyon, N.M. Holford, D.E. Maclver, C.J. Morgan; Fellows S.K. de Kock, R.R. Porter, Dr G.J. Rees; and Associate Sir Lindesay Clark. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, please rise and observe a moment of silence. Minutes President: The 88th Annual General Meeting of the Institute was held on Wednesday, 14th August, 1985, and the minutes were published in the September 1985 issue of the Journal. The minutes were confirmed.

Jan 1, 1986

By J. -M. Chautru

A geostatistical simulation of a typical mining site for polymetallic nodules in the North Pacific Ocean is presented. This is the first stage in the design of an industrial mining system. Two variables which have a major effect on the orebody&apos;s economic potential are considered, namely: the maximum slope of the ground inside a mining block of 50 x 100 m; and the average quantity of nodules on the same support. Two geostatistical problems have emerged in this study. The first is due to the lack of a change of support model for the maximum of a variable. A provisional solution, considering an experimentally accessible &apos;equivalent&apos; support, is proposed. The second is due to a non-linear link between the two variables. To be able to take this into account in the simulation, we propose a new method based on the decomposition: X = E(X/Y) + Residue (X). Satisfactory results were obtained with this approach.

Jan 1, 1987

By A. E. Voigt

Iron ore samples representing the input and output of several jigging experiments were analysed to determine the effect of particle size, shape, and density on jigging performance. Traditionally, the manual measurement of the size and shape of individual particles is very tedious and prone to inaccuracies and inconsistencies. Using a novel multi-view imaging technique the 3-dimensional representations of each particle in the sample was determined. From this representation several size and shape measurements were extracted, and these were correlated with the individual particle density measurements. A rigorous investigation into the confidence associated with density and the size and shape features as a function of sample size was conducted, thus allowing the significance of correlations in the data to be determined. The jig?s performance was seen to be clearly sensitive to density and markedly so to particle size, while the results for shape indicated the need for continued work in the definition of particle shape.

Jan 1, 2012

By A. Mabentsela

A furnace freeze lining is necessary for safety and economic reasons in several smelting operations. The integrity of the freeze lining is put at risk by furnace power imbalances. Although numerous models have been derived to model the growth and depletion of the freeze lining due to power imbalances, no model exists for thermomechanical damage to the freeze lining. This study provides an initial pathway for modelling thermomechanical damage to the freeze lining in an ilmenite smelting furnace using information from the literature and experimental work. A methodology under the framework of continuum damage mechanics is proposed to model mechanical damage to the freeze lining due to phase changes, thermophysical changes, and constrained thermal expansion. Drill cores of solidified slag ingots were used to represent the freeze lining. The modified power law proved to be the best predictor of the softening response of the drill cores. Damage driving parameters were extracted from the raw data, and governing equations of the parameters with respect to temperature were derived for use in a finite element method (FEM) code.

Jan 26, 2023

By B. Genc, C. Gous

Spontaneous combustion during coal mining operations is a major problem that affects the health and safety of workers and causes environmental problems. The phenomenon is associated with the presence of coal, coal shale, and pyrite. In 2020, a premature detonation incident occurred at an iron ore mine where the waste material contains black carbonaceous shale units known to be associated with pyrite. The spontaneous combustion propensity and properties of samples of the black carbonaceous shales from the mine were examined and compared with samples from the Witbank Coalfield. The spontaneous combustion liability indexes of these samples were correlated with X-ray fluorescence (XRF) and proximate and ultimate analyses using linear regression. The Wits-Ehac Index classification results show that the samples were between medium and high risk. The linear regression analysis showed very poor correlations between the Wits-Ehac Index results and the XRF and proximate and ultimate results. The most valuable relationship found is between the presence of relatively high sulphur (greater than 3%) and ground reactivity with nitrate-bearing explosive emulsion.

Jun 5, 2023

By F. Smit

Mining and plant disciplines can benefit from pre-concentration of UG2 platinum ores in a dense medium separation (DMS) plant. The main benefit of DMS is the selective discard of waste from the feed stream, thus improving project economics while reducing the power and water requirements for processing. On the mining side, with the correct combination of variables, implementing DMS as a pre-concentration step can reduce cut-off grades and, as a result, increase ore reserves. In addition, the use of DMS technology gives the mine team the opportunity to consider alternative mining methods for an operation. The challenges of balancing the mining tonnage, methods, and resulting grades with the process plant size, recoveries, and DMS discard volumes have resulted in the development of a model to optimize value on new projects or existing operations. This paper will focus on these benefits from a mining and plant perspective, quantifying the water and power savings, and look at the economic benefits of pre-concentration and the effect of metal prices, plant feed grade, and DMS efficiency in different mining environments.

Jan 1, 2012

By Y. Qin, L. Han, P. Gao, Y. Han, Y. Lia

In the present study, an innovative comminution technology of high-voltage pulse discharge was proposed for galena to weaken the mechanical property. The results of pre-treatment experiments indicated that the optimal operating conditions of spherical gap spacing 25 mm, pulse numbers 120, and loading voltage 25 kV were obtained, where the relative grindability of pretreated products was improved significantly, although with the prolonging of grinding time, the superiority of high-voltage electric pulses was gradually weakened. The galena ores were subjected to a high-voltage pulse discharge, and then the crack generating along the boundary between galena and gangue was observed under an optical microscope, and the surface burning which appeared in the ores. The scanning electron microscope (SEM) results indicated that the pretreated products were in a state of melting and then condensation, accompanied by some pore formation. Pulsed discharge pre-treatment not only produced more micro-cracks and cracks in the sample but also extended the original crack. Keywords: High-voltage pulse discharge; galena; relative grindability; micro-crack

Jan 1, 2020

By M. Hao, S. Hu, X. Lyu, M. Lian, C. Anning, G. Yao, Z. Wang

The results revealed that the pozzolanic activity of the gold mine tailings and their main mineral phases improved by mechanical activation. Under the same activation conditions, the activated mica powders possessed the highest pozzolanic activity index, followed by the activated feldspar, and the activated quartz exhibited the lowest pozzolanic activity index. The addition of calcium oxide promoted the formation of amorphous C–(A)–S–H gel for all paste samples, and stratlingite and hydrotalcite were observed in calcium oxide activated mica paste. The addition of natural anhydrite promoted the formation of ettringite for the pastes of calcium oxide activated aluminosilicates materials (gold mine tailings, mica, and feldspar). Furthermore, the pozzolanic activity indexes of the mechanically activated gold mine tailings and their main mineral phases were tested to be qualified for use as supplementary cementitious material in cement. This paper provided an innovative approach for recycling gold mine tailings as supplementary cementitious materials in cement, which would be environmentally friendly and cost-effective. Keywords: Mechanical activation, gold mine tailings, supplementary cementitious material, hydration properties, pozzolanic activity

Jan 1, 2020