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By M R. Davidson, M P. Schwarz

A model for column bioleaching is investigated to identify and understand aspects of bacteria in bioleaching applications, which have implications in heap bioleaching operations. The model is used to simulate scenarios that would otherwise be time consuming to perform experimentally. This study uses a model of bacterial transport and attachment/detachment to ore particles, with a bioleaching model for the depletion of a copper-sulfide, also accounting for liquid and gas flow and gas/liquid oxygen mass transfer. The model includes aspects such as oxygen and ferrous ion consumption, coupled with leaching of a copper-sulfide via the shrinking core model. The model is used to investigate how the rate of leaching is affected by the bacterial concentration in the columns, by the bacterial regeneration of the leaching oxidant ferric ions. The model is also used to assess the impact of oxygen limitation and inoculation method on the copper leaching. Some comparison of the model with experimental data will be shown.

Jan 1, 2004

By M. G. F. Sohnlein

IN a Bolivian tin concentrator an appliance was needed to furnish a suitable product for fine jigging from a pulp of the following composition: Mesh Per Cent. +20 8.0 +40 36.5 +60 9.0 +80 10.5 +100 5.5 +150 4.51 -150 25.0 99.0 Loss 1.0 IN the jigging process, particles of cassiterite as small as 0.1 mm. can be recovered, provided they are not present in excess, that is if the material treated on the jigs contains sufficient coarser sands to keep the interstices between the grains open. Removing the fine material from the pulp by screening, to prepare the jig feed, is impractical, because that means the use of an 80-mesh screen or finer, and is not as effective as hydraulic classification. A screen would eliminate mineral grains from the feed which can be recovered by jigging, and in addition would throw more gangue and low-grade middling on to the jig. Formerly a one-spigot Richards vortex classifier had been used to accomplish this separation, but the tangential openings through which the hydraulic water enters became clogged by fine vegetal matter with which the water was contaminated, and which it was impossible to remove from the water. Consequently the work of the classifier was imperfect and a good deal of slime was sent to the jig. When designing the plant referred to in this paper it was decided to use a hydraulic classifier as shown in Fig. 1. The essential features had been copied from the Anaconda classifier.1 This remodeled classifier consists of a truncated pyramidal wooden hooper A with an attachment of cast iron

Jan 4, 1916

By W. Z. Choi

A combined size reduction- liberation model of grinding has been developed to predict the product size distribution for both free and locked particles. The model is an extension of the population balance model for size reduction. Locked (or composite) particles have been subdivided into discrete classes of different compositions to obtain more detailed information. The model has been tested on a sphalerite ore from Tennessee. Liberation data have been obtained using an areal scanning technique on microscope images of polished particle mounts.

Jan 1, 1985

A viable flow sheet of the sorption-flotation technology for gold recovery from low-grade ores and concentrates using powdered activated carbon modified by organic compounds as the sorbent-bearer has been developed. The powdered activated carbon, with high kinetic ability and sufficient specific area, was selected as the all-purpose gold cyanide complex-bearing sorbent which is active during flotation. To improve carbon adsorption capacity and to provide the required floatability its porous structure was filled with a quaternary ammonium compound which can extract gold cyanide complexes and render additional flotation properties to the carbon. To optimise the process and to simplify the layout, adsorption and flotation processes were carried out simultaneously in a mechanical flotation cell. The proposed technology was used for extended and pilot-plant tests of sorption-flotation gold recovery from 0.6 g/t Au final tailings and 2.0 g/t Au gravity tailings. The extended tests were carried out on Taseevskaya (Chita Region) flotation tailings, whereas pilot-plant tests were conducted on Kommunarovskaya (Krasnoyarsk Region) gravity tailings passing to cyanidation, followed by processing with filtration technology. Additional gold recovery from Taseevskaya final flotation tailings was 50.8 per cent. Gold recovery from Kommunarovskaya final gravity tailings was 92.5 per cent. Compared to the complete sludge process conventionally used at the plant, gold recovery was increased by 7.5 per cent due to lower gold losses in the liquid phase and conversion of the refractory non-cyanided metal into a carbon concentrate. This paper presents the experimental results of gold adsorption onto powdered activated carbon modified with quaternary ammonium compounds (sorbent-bearer) as well as sorbent-bearer flotation with various collectors from cyanide solutions and pulps.

Jan 1, 2005

The word governing derives from gubernare meaningto pilot a ship. Being inclined to metaphors, one could be forgiven to think that politicians act this verb and captain the Nation's ship into some definite course. In the case of at least the mineral resources industry, it seems that there are not many James Cook followers in our parliaments: Australia's approach to mineral and energy policy is often chaotic - witness the 1935 to 1961 ban on iron ore export-ing which prevented the development of a significant steel industry at time when the World was hungry for this metal, just to mention one amongst many other examples.The follies of Australia's mineral policies are well il-lustrated in the case of uranium mining. Although Australia had the Western World's largest economic reserves of uranium, it is onlythefifth producing nation and its uranium potential is largely unrealised. At the root of this situation are the interventionist attitudes and policies of successive Federal Governments which for more than four decades distorted the Investment decision and, in more recent times. discouraaed investment.

Jan 1, 1990

By S. Rupprecht

"INTRODUCTION This paper addresses the prevalence of poor public reporting practices of Coal Exploration Results, Coal Resources and Coal Reserves in southern Africa. Currently, the reporting of coal tonnage without supporting coal qualities or “saleable” tonnes and quality is a poor reporting practice that occurs far too often. Not all coal is equal – therefore it is extremely important that investors or potential investors are provided with the full details of both run-of-mine (“ROM”) and Saleable coal tonnage, their associated qualities and other material and relevant information. Competent or Qualified Persons should note that publicly reported information should be sufficient to enable an informed reader to make a reasonable and balanced assessment of the significance of the information provide. “Companies are encouraged to provide information in their Public Reports, which is as comprehensive as possible” (CRIRSCO, 2013): too often this isn’t the case and material matters are either not reported or inadequately disclosed. According to the South African National Standard (SANS) 10320:2014 draft document - “tonnage and coal quality that will be available for sale, either in the raw ROM state (raw Saleable) at a specified moisture content, or after beneficiation of the ROM coal by processing operations to produce materials at specified qualities, size ranges and moisture contents. The assessments must demonstrate that at the time of reporting, the marketing of the products is reasonably justified. The basis of the predicted practical product yield to achieve the Saleable Coal Reserve must be stated. The moisture basis of reporting shall be stated.” As an example to why coal qualities are so important to the public, the requirements of South Africa’s electric public utility (Eskom) power stations are highlighted. The Kendal power station, commissioned in 1988, operates at a Calorific Value (“CV”) range of 19 to 20MJ/kg, an Ash content between 29 and 34% and Volatiles between 20 to 21%. Other power stations, such as Kriel or Hendrina, may require different qualities such as a CV range of 22 to 23MJ/kg, an Ash content between 20 and 28% and Volatiles between 22 to 23%. Thus, in terms of domestic saleable coal, it isn’t just about reporting the coal qualities but also informing the investor as to which power station the coal is intended to be sold as “boilers are designed to burn particular qualities of coal” and “it is not always possible to transfer coal between stations because of different quality requirements at each station” (Chetty, 2010). Sulphur content is also another important quality with the ideal coal content having a quality of less than 1% Sulphur."

Jan 1, 2018

By D. C. Fuller

CoaLiquid, Inc. (CLI) has been in the coal- oil-mixture (COM) business for over five (5) years. The initial pilot processing facility was replaced by a 2000 barrel per day commercial production facility in August of 1979. For over two (2) years CLI has been expanding its efforts and conducting large scale production and combustion demonstrations successfully in many locations across the United States. To facilitate the marketing effort, CLI has recently constructed a special trailer containing all equipment needed for a temporary COM retrofit. CoaLiquid has conducted commercial scale combustion demonstrations in the following types of combustion units: kilns, calciners, industrial boilers, blast furnaces and driers.

Jan 1, 1982

By W. H. Blauvelt

THE subject of fuel-briquetting has attracted much attention on the part of engineers and investors for the past 15 or 20 years, and especially in recent years, during which a number of plants have been built, with more or less commercial and technical success. Our technical literature contains numerous descriptions of certain processes, and discussions of the industry in general. For a history of the development of the art in the United States, and for descriptions of many of the processes which have been tried, reference may be made to the files of our Transactions, and, for more recent information, to a paper by C. T. Malcolmson, read before the First Annual Convention of the International Railway Fuel Association in June, 1909. The purpose of the present paper is to describe the briquette-plant of the Solvay Process Co. and the Semet-Solvay Co. at Detroit, Mich., which, after a period of long and costly evolution, is now operating satisfactorily on a commercial basis. I believe that it will be of interest to some of our members to have the details of operation, lower-consumption, labor, etc., as worked out on a practical and commercial scale in a going operation. The briquette industry has had a somewhat checkered career in the United States, and much the larger portion of the failures has been due entirely to commercial causes. It seems axiomatic to say that before undertaking the installation of a plant for manufacturing briquettes it is necessary that the local situation should be carefully examined : First, to determine the kind of briquettes, if any, the local market will consume; that is-to say, whether the available fuel-supply is such that briquettes would be a welcome addition, and whether the most promising field is the industrial or the domestic market. Second, if there is an available supply of raw material, as coal,

Mar 1, 1910

By Robert E. Murray

The title of my paper, "A Company's Response to Federal Coal Leasing," brings to mind a picture of a dog chasing its tail. This is what the coal industry, has been doing since the Federal coal leasing moratorium went into effect in 1971. We've gone around in many circles, but we are only very slowly, if at all, getting closer to catching our tails, i.e., efficient, economical, and rational Federal coal leasing. My companies, The North American Coal Corporation and its four Subsidiaries, The Falkirk and Western Plains Mining Companies and The Coteau and Missouri Valley Properties Companies, together hold in excess of 4.5 billion tons of lignite reserves in North Dakota. Some of our North Dakota properties are substantially interspersed with Federal coal, with the government holding title to the minerals in every other section. This checkerboard pattern of Federal ownership has made it difficult to develop and market some of our reserves, and, as a result, it has become imperative that we be familiar with and active in the Federal Coal Leasing Program.

Jan 1, 1982

By H. EI-shall

In this paper, the results of bench scale testing of five different flotation processes to separate dolomite from phosphate are discussed. The effectiveness of each process interms of phosphate recovery and MgO content in the concentrate is used together with the reagent consumption as the basis of comparison. The water quality is found to play a major role in the performance of these processes. Effect of water hardness as well as other parameters are discussed.

Jan 1, 1995

By J. H. van Laar, C. S. L. Schutte, M. Le Roux

Highly energy-intensive systems prone to wastage are significant causes of unnecessary energy losses in industry. Deep-level mine chilled water reticulation systems fall within this category of inefficient energy-intensive systems. Some techniques (measured baselining, zero-waste baselining, leak detection, and control valves) exist to identify and reduce wastage in mine water reticulation systems. However, these techniques have not been compared, which begs the question of which is more accurate. A need, therefore, exists to compare these methods to determine the effectiveness of each. This study investigates each method and applies them to a case study mine, providing a platform for comparison. These methods identified wastage ranging between 2 and 20 l/s (3–30% of water consumption). The comparative effectiveness of the methods from best to worst was found to be zero-waste baselining, leak detection, control valves, then measure baselining. This study proposes an application procedure combining the considered methods to identify and eliminate wastage on deep-level mine systems more efficiently.

Jan 31, 2024

By Elham Najafi, Sina Ghassa, Ata Akcil, Hadi Abdollahi, Sandeep Panda, Zohreh Boroumand

Bioleaching is an environmental friendly process that has gained much interest for the production of metals from metal-bearing wastes or materials. The process decreases carbon footprint by reducing consumption of fossil fuels. Iron is a key factor in acidophilic iron-oxidizing bacteria’s activity, which is used extensively in the bioleaching of sulfide minerals. In the present study, the effect of different iron sources is investigated on sphalerite (ZnS) bioleaching. For this purpose, the effects of FeSO4  .7H2O, Fe2(SO4  )3 and FeS2 (pyrite) were studied on bacterial activity, and zinc (Zn), lead (Pb), cadmium (Cd) and arsenic (As) dissolutions were monitored from a ZnS concentrate. Under optimum conditions, the dissolutions of Zn, Pb, Cd and As were found to be 39.8, 0.1. 0.03 and 10 percent, respectively, in 25 days.

By Elham Najafi, Sina Ghassa, Ata Akcil, Hadi Abdollahi, Sandeep Panda, Zohreh Boroumand

The present study investigates the influence of ferrous iron (as FeSO4) and ferric iron (as Fe2 (SO4)3), and pyrite (FeS2) on the ability of bacterial leaching of a high-grade sulfide Zn–Pb ore. In this regard, shake flask experiments were carried out at 5% (w/v) pulp density of the ore sample (having 40.7% Zn and 12.4% Pb initial metal content) using a consortium of mesophilic iron and sulfur-oxidizing acidophiles. A concentration of 0.04 mol/L of ferric iron in the leaching media was found to be optimum for zinc extraction without affecting growth of the microorganisms. Under this concentration, the dissolution of Zn, Pb, Cd, and As was found to be 57%, 0.2%, 0.03%, and 9.9% in 25 days. Using ferrous iron in the media, 0.16 mol/L of Fe2+ was found to be the optimum concentration for efficient bacterial growth and metal dissolution (54.6% Zn, 0.08% Pb, 0.03% Cd, and 10.2% As) from the sample in 25 days. On the other hand, using pyrite as the source of energy for bacterial growth, an initial 12-day lag period was observed when compared to the effect of ferrous iron in the media. Under the optimum concentration (test with 0.24 mol/L iron in the form of pyrite), the dissolution of Zn, Pb, Cd, and As was found to be 39.8%, 0.1%, 0.03%, and 10% in 25 days. The surface chemistry analysis indicated formation of a sulfur layer over the particle surface that hindered reagent diffusion and affected metal recovery through bioleaching.

By Richard C. Corson

The objective of blending materials in a bedding pile is to reduce the variation in successive samples taken from the materials to be blended. In designing a bedding and reclaiming operation, several mechanisms are available to effect the reduction of variability, or increase in homogeneity, of the materials. These mechanisms can act before stacking, in the stacking process, in reclaiming and after reclaiming. In evaluating alternative methods of stacking and reclaiming, the potential user must judge each method on the basis of certain criteria; the capital cost of the equipment, the allowable absolute variability of the reclaimed product and the effectiveness of blending. Several stacking and reclaiming methods have been tested using a computer simulation. Based on the results of this program, factors were developed to describe the effectiveness of blending for chevron stacking of discrete materials and preblended materials, bucket wheel reclaiming and drum reclaiming. From these factors, the total effectiveness of a combined stacking and reclaiming system can be determined.

Jan 1, 1985

By A. Mazhary

"Although sensor-based ore sorting has gained significant attention recently, sorting gold deposits still face a high level of skepticism by gold mining companies. In order to shed some light on the matter, this article looks at two different gold deposits that were examined using X-ray Fluorescence, Electromagnetic and X-ray Transmission sensors. The heterogeneity of each sample is measured based on the assay results of each particle and is related to its sortability. Multivariate linear regression analysis was also performed on the XRF results to find potential proxy elements for detecting gold. The results from these deposits were varied and each sample showed different levels of sortability. While both X-ray sensors proved efficient for different deposits, the electromagnetic sensor failed to produce any promising results. Despite unsatisfactory result for one sample, this technology can have significant advantages in terms of lowering the operational costs and improving head grades and recoveries providing that the deposit is amenable to such separation methods. Therefore, it is important to mention that sensor-based ore sorting is ore and sensor dependent, and as a result, it cannot be applied and be beneficial to all deposits. Therefore, amenability tests are required in order to examine the potential for sensor-based ore sorting before one can reject the idea.INTRODUCTION Although sensor-based ore sorting has gained significant attention recently, sorting gold deposits still face a high level of skepticism by gold mining companies. Except for a few cases presented previously, no new case studies have been published. Previously, mines such as Kloof Gold Mine in South Africa used an optical sorter to sort their waste stockpile in 2003–2004 (Von Ketelhodt, 2009) and then again in 2009 (Von Ketelhodt, Falcon, & Falcon, 2011). More recently, Coeur Operations utilized an XRT sorter for their Kensington Mine in Alaska (Lasley, 2014) and also Anglo-American Platinum used an XRF sorter to pre-concentrate Platinum Group Metals through an algorithm that used chrome, copper and nickel as proxies (Rule, Fouchee, & Swart, 2015)."

Jan 1, 2017

By S. Aguayo-Salinas, J. L. Valenzuela-García, A. L. Leal-Cruz, M. I. Pech-Canul, M. T. Certucha-Barragán

"The aim of this research was to carry out a comparative and systematic study of the degradation of cyanide by hybrid natural/biodegradation and biodegradation methods using a mixture of Pseudomonas sp and Bacillus megaterium native bacteria. Bioreactors consist of filled columns with contaminated ore containing 100 ppm of total cyanide. In the biodegradation tests a mixture of bacteria was inoculated into the biodegrading solution. Results of cyanide degradation show a similar asymptotic behavior in both the hybrid (opened system) and biodegradation (closed system) methods; however, for the same period of time (72 h) the permissible maximum levels (1-2 ppm of cyanide) are only attained in the closed system. While in the closed system the cyanide levels are reduced from 100 to 1.5 ppm, in the open system, cyanide decreases from 100 to 2.4 ppm.IntroductionOne of the most important tasks of mining industry is the treatment of the wastes generated in mining operations. Accordingly, industrial waste waters and ores represent a complex problem and a great challenge. In addition to ethic and communitarian considerations, there are laws that prohibit or regulate the contamination of water and air. Moreover, they establish that the restoration of wastes must be considered as a necessary operation cost [1]. Currently this important problem is being addressed by the mining and metallurgical industries using different approaches; mainly they are focusing on the treatment of waste waters and ores generated by the leaching process in which cyanide is used as a leaching agent for the recovery of precious metals as gold and silver. Cyanides have toxic characteristics and thus negatively impact the environment when they are discharged to the ground without previous treatment. While there are some processes in current use there are others that have only been proposed and that allow cyanide degradation, transformation to less toxic compounds and/or the complete elimination of cyanide. The second group includes a variety of techniques that use natural, chemical and biological treatments. Natural treatments consist of the passive abandoning of the heap and of its washing with water. Since these processes are slow and generate great volumes of water partially contaminated, then other alternatives should be considered."

Jan 1, 2008

By W. H. Holtzhausen

The purpose of this project was to compare two underground, batch coal haulers ? battery haulers and shuttle cars ? in order to determine the more viable machine to implement. The specific standards for battery haulers were investigated and compared to the requirements of shuttle cars in order to identify the unnecessary expenses related to the legal requirements that are attached to the machines. Costs such as running costs, capital costs, and maintenance costs were researched and compared over a typical life of machine. Average production rates and breakdown times were obtained and used to determine which machine would be more reliable in achieving the required annual production.

Jan 1, 2014

By Chu Bo-Yi

"This paper contains a comparison of creep-feed and shallow-cut grinding on ceramics with both neat oil and water-based grinding fluids. When a water-based grinding fluid was used in creep-feed grinding on ceramics the vertical forces and specific energies increased markedly fast with result that the wheel surface was damaged seriously. Creep-feed grinding on ceramics with neat oil not only produced much lower grinding forces and specific energies but also resulted in the wheel remaining in good condition and minimizing damage to the ground surface. This finding may lead to a deeper understanding of the behaviors of grinding fluids in grinding processes both on ceramics and metal as well.1. IntroductionAs advanced ceramics are obtaining more and more applications in the technical area, some machining processes are needed after the sintering to reach the accuracy and finish required by components. Because of higher hardness and brittle behaviors of modem ceramic many researches have been done in order to improve grinding efficiency and surface quality.In the grinding metals the concept of creep-feed grinding has been developed in industry as a real alternative to the normal method of shallow-cut grinding. In addition to the general economic advantages, dimensional accuracy and surface integrity are invariable improved using the creep-feed grinding technique.In grinding ceramics former studies have done many works on both creep-feed and shallow-cut grinding on ceramics with water-based grinding fluids since the water-based were thought to be better coolants than neat oil in most tests of grinding metals[l]. It was suggested that the specific grinding energies of ceramics are markedly higher in creep-feed grinding. The grinding force increases vary rapidly with time in the creep-feed case. In other words, so-called speed stroke grinding with high workpiece speed is considered more suitable for improving the grinding efficiency [2][3]."

Jan 1, 1998

By K M. P Singh, K M. K Sinha, G S. Jha, T Gouricharan, K K. Sharma

The majority of the powerplants in India are fed with non-coking coals, with the coals dispatched from their respective mines via wagons loaded by a rapid loading system or pay loader. The usual top size of coal is 200 mm and sampling is carried out manually from wagons. The manual method of wagon top sampling of large size raw coal is not only difficult, but also violates some of the fundamental principles of sampling. As per sampling requirements, samples are to be drawn from the full depth of the wagons, which is impossible to be done manually. Since the ash distribution in the different size fractions is not homogeneous, the results from the samples, which do not reflect the true size distribution of the lot, are likely to be biased. More importantly, sample collection by shovel from the top is a function of human discretion and not governed by the equiprobability rule. In another case, the sample has been collected by a cross belt-type auto mechanical sampler for 200 mm size coal at one of the super thermal power stations. Test analysis shows that coal collected using a cross belt-type mechanical sampler also has significant deviations from stopped belt coal samples of 200 mm size due to size segregation. Studies carried out on wagon top sampling through specially designed experiments reveal some interesting features. The presence of bias in wagon top sampling is apparent when compared with the ‘stopped belt’ sample. In this paper, a comparative study between manual wagon top sampling/auto mechanical sampling with respect to stopped belt sampling has been conducted for coal of size 200 mm. In addition, precision studies have been performed for wagon top sampling/mechanical sampling for Indian thermal powerplants.CITATION:Sinha, K M K, Sharma, K K, Jha, G S, Singh, K M P and Gouricharan, T, 2014. A comparative study of manual wagon top sampling and auto mechanical sampling of 200 mm size coal with respect to stopped belt sampling of thermal coal at Indian super thermal powerplants, in Proceedings Sampling 2014 , pp 43–48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By J. C. Huyhua

The effect or various oxidants on gold and silver dissolution in thiourea solutions (0.05 M in H2SO4) was studied using the rotating disc technique, a.t 2s c and 600 rpm. These studies were carried out at constant (4:1) initial molar ratio or thiourea to oxidant concentrations, to produce 50 % thiourea. oxidation. The initial dissolution rate of gold was approximately four times higher in the presence. of ferric sulfate (5.37 x 10-3mg cm-2 s-1) than in the presence of hydrogen peroxide (H2O2), potassium persultate (K2S2O3), or monopersulfa.te (KHS06). The dissolution rates for silver were considerably lower than gold for the same oxidants. Oxidation of thiourea in the presence of peroxygen and persulta.te compounds is a. fast reaction and it is completed in less than ten minutes. On the other hand, the oxidation or thiourea with? ferric.sulfate is slow, yielding a second-order reaction rate constant k = 6.09 I mol-1 h-1. Sulfur formation in the ferric thiourea system begins when ferric ion reduction approaches to completion. With hydrogen peroxide, sulfur is observed at lower thiourea concentration than ferric. Suifate. The presence of a large excess or free thiourea i.e., s to 20 % thiourea oxidation) retards sulfur formation and maintains favorable dissolution rates. Finally, carbon-in-leach experiments indicate that thiourea solutions a.re stable for several days, with ferric sulfate or hydrogen peroxide. The dissolution rates of gold and silver doubles in the presence or activated carbon when hydrogen peroxide is used as oxidant.

Jan 1, 1989