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By L Basnayaka, N Subasinghe, B Albijanic

"It has been recognised that the presence of clay minerals in ores adversely affect flotation performance. In this study, changes in rheological properties of the flotation pulps under normal operating conditions were studied with additions of bentonite and kaolinite clays at various concentrations. Zeta potential measurements were also carried out to determine the changes in surface charge due to adsorption of clay particles. The results showed that bentonite clay adversely affects floatability of pyrite while kaolinite clay had a lesser influence on flotation of pyrite. The addition of Ca2+ ions to the pulp containing bentonite modified the rheological characteristics and in turn improved the pyrite flotation. It was also observed Ca2+ ions suppressed the swelling properties of bentonite and altered surface charge properties of bentonite clay particles. It has been shown that the flow index affected the ultimate recovery and it may provide a means to monitor flotation performance in routine plant operations.Citation:Basnayaka, L, Subasinghe, N and Albijanic, B, 2016. Effect of Clay Rheology on Flotation of a Refractory Gold Ore, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 77–84 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By W. Crafts, J. L. Lamont

Electrolytic extraction of carbides from quenched and tempered steel and their examination under the electron microscope were found to be helpful in understanding the mechanism of secondary hardening in alloy steels1 and the same technique has been applied to isothermally transformed steels. A preliminary survey of the utility of the method has indicated that it has promising possibilities for investigating the characteristics of pearlite and bainite. The examination of a few carbon and chromium steels has suggested that pearlite is formed with carbides of two varieties representing the lamellar and nonlamellar forms and that bainite appears to form with a structure analogous to, but significantly different from, martensite. Procedure The method used for examining the carbides was similar to that described previously.1 The chromium steels used in the investigation were made from an Armco iron base in an induction furnace and were not treated with grain-refining deoxidizers. The composition of the steels is given in Table 1. Three-inch square ingots were forged and rolled to 1/8-in. thick sheet for use in the isothermal studies. After rolling, the sheets were sandblasted to remove the rolling scale. Specimens approximately 3/4-in. wide and l1/2-in. long were prepared from the 1/8-in. sheet. They were heated in a salt "bath at 2100°F (1150°C) for 1/2 hour, transferred to other salt baths at 1300°F (704°C), 1000°F (538°C), 800°F (426°C), or 600°F (315°C), held for various periods up to 100 hr and finally quenched in water. After quenching, the specimens were cut in half, one half being submitted to microscopic examination and the other half being used for the electrolytic extraction. The isothermally transformed specimens were submitted to examination under the light microscope to determine the degree of transformation and type of structure and were photographed at 2000 X. Carbide residues were obtained by electrolyzing in 10 pet hydrochloric acid and collecting the residue in glycerine to minimize attack by the acid. As pointed out in the earlier paper, the carbides are attacked to some degree during electrolysis. This attack is relatively minor on the coarser carbides but may be quite severe on the fine bainitic carbides. The residues were washed free of the glycerine with water and alcohol. The alcohol was removed by repeated washings of amyl acetate, and the amyl acetate suspensions were transferred to stoppered vials. Debye-Sherrer X ray diffraction patterns of the residues were prepared using a chromium target. A selection based on the microstructure and X ray data was then made of samples considered most illustrative of the progress of transformation. Electrolytically extracted residues from these samples were submitted to examination by W. D. Forgeng and A. C. Jenkins on the electron microscope at the Research Laboratories of The Linde Air Products Co. and electron micrographs were made at X 5000 and enlarged to 25,000 X. The micrographs obtained with both the light and the electron microscopes are mounted side by side in the accompanying figures. Although no effort was made to establish the T-T-T diagram for the chromium steels, the times for holding in the salt bath were adjusted with the intention of making the samples represent different stages in the transformation at temperatures of 600, 800, 1000, and 1300°F. The degrees of transformation and results of X ray examination are shown in Tables 2—4. The carbide designations refer to orthorhombic or trigonal carbide types and are not meant to imply that the compositions are exactly as indicated. X ray Diffraction Data The occurrence of Fe3C and Cr7C3 in these steels was found to be consistent with published data on comparable chromium steels. Steels A and B with relatively low ratios of carbon to chromium contained Cr7C3 in the pearlitic structures and FeuC in the

Jan 1, 1950

By Frank Firmstone

(Ottawa Meeting, October, 1889. Substituted for the briefer note on the same subject. pre sented at the meeting and subsequently distributed in preliminary pamphlet edition.) Prof. H. Hoefer's theory of blasting was published in the Oesterr. Zeitschrift, xxviii., 1880, and xxix., 1881; and Part 111. in Nos. 15, 16 and 17, xxx., 1882, and subsequent numbers of that

Jan 1, 1890

By N. A. Tolch

[In this partner ?propulsive strength? or "strength" is defined as the relative propulsive effect of an explosive as determined by means of the United States Bureau of Mines ballistic pendulum. The data presented are derived from one particular strength testing device and do not necessarily represent the relative execution value of the different explosives in actual blasting. However, it is believed that the data obtained with the ballistic pendulum fire indicative of the relative propulsive or heaving force and are of value until propulsive strength can be expressed in more fundamental units.]

Jan 1, 1929

By Ernest J. Conway

This report presents engineering drawings for six material handling devices for underground coal mines. The devices were designed under a U.S. Bureau of Mines program to reduce injuries from material handling during mine and equipment maintenance. The six devices are (1) scoop-mounted 1411: boom, (2) swing-arm boom, (3) heavy-component lift-transport, (4) mine mud cart, (5) container-workstation vehicle, and (6) timber car. Each device is described briefly, and recommendations are made concerning the design of new devices.

Jan 1, 1989

By James A. Brown, Marius Botha, Christopher A. Fleming

"The technical and economic feasibility or re-processing hundreds of millions of tons of tailings in a number of historic gold tailings dams in the Witwatersrand area of South Africa is being investigated. The objective is to recover uranium and residual gold from the tailings, as well as to oxidize the sulphides to eliminate long term environmental liabilities associated with acid mine drainage. The tailings from the re-processing plant will be re-deposited in a new area far from urbanization, allowing for the rehabilitation of the real estate currently occupied by these historic tailings.The first step in the process involves a mild-regrind and mild acid leach of the tailings (pH 2.5 to 3.0) to dissolve up to 40% of the uranium. This uranium is recovered directly from the pulp by resin in pulp (RIP) with a strong base resin. The RIP tails are then treated by flotation to recover a rougher pyrite concentrate, and flotation tailings that are discarded. The rougher concentrate is cleaned to produce a final pyrite concentrate and cleaner scavenger tailings, and the pyrite concentrate is oxidized in an autoclave to leach uranium and generate acid. The autoclave discharge is combined with the cleaner scavenger tails, and the acid and ferric ions generated in the autoclave are used to leach more uranium and oxidize more sulphide in the cleaner tails. The product from the concentrate leach circuit is processed by resin in pulp for uranium recovery, followed by neutralization, cyanidation and carbon in pulp for gold recovery.The rougher float tails may be further treated to recover gold that was not recovered in flotation, but which had been liberated from the old dumps by natural oxidation of some of the pyrite over many decades. The float tails would be neutralized and treated by cyanidation and CIL to recover this liberated gold.All parts of the flowsheet have been extensively tested in the laboratory, and the critical elements of flotation, pressure oxidation and resin in pulp have been demonstrated in pilot plants. The results of the hydrometallurgical investigations are presented here."

Jan 1, 2010

By J. Châteauneuf, R. Dupéré, D. Mrabet

"In gold processing plants, it is common to start gold cyanidation in the grinding circuit by simple cyanide addition or as a result of recycling residual cyanide. In such cases, advantages such as a decrease in gold lockup and reduced leach time have been noticed. The prevailing conditions in grinding circuits such as intense mixing, particle breakage and friction or high temperature are quite different from those found in tanks and so is the resulting cyanidation behaviour. To gain a better understanding of the cyanidation behaviour in mills and of the pertinence of cyanide addition in grinding circuits, lab tests were conducted using an industrial ore from Canadian Malartic mine. In this study, the effects of different parameters on cyanidation in grinding circuits were examined; parameters such as such as temperature, dissolved oxygen, cyanide concentration and pH. The results showed that the kinetic benefits of high temperature in the mill can overcome the low dissolved oxygen concentration thus leading to an overall gold dissolution kinetics improvement for temperatures up to 50°C. However, gold leach in the studied grinding circuit at lab scale caused an increase in cyanide consumption with a higher generation of iron cyanide and SCN-. These results were confirmed by tests in the Canadian Malartic plant where the cyanide addition was moved from the SAG mill to the leaching tanks resulting in a 20% savings in cyanide consumption.IntroductionCyanidation in grinding circuits can benefit gold processing by decreasing gold lockup and by reducing leach time. However, other aspects regarding gold and cyanicide dissolution come into play in the conditions prevailing in grinding circuits. Indeed, high turbulence, high temperature, recycling load, friction and particle breakage make cyanidation behaviour in grinding circuits different from in-tank cyanidation (Marsden and House, 2006). In several cases, cyanide in grinding is limited to a very low level or completely avoided such as in circuits with gravimetric separation, for ores requiring oxidative pretreatment or for preg-robbing ores. In other cases, water management imposes a certain recycling of residual cyanide. This problem is generally addressed by a case-by-case approach. However, the chemistry of cyanidation in mill circuits is worth investigating in order to assess the advantages and disadvantages."

Jan 1, 2016

Anglo Platinum commenced commercial underground borehole radar (BHR) surveys during 2006 following a series of trial surveys using both the ?slimline? Geomole and Aardwolf systems. Current borehole radar systems comprise radio frequency transmitter ? receiver antennae operating at 30 -100MHz that measure the time taken for a transmitted pulse to traverse a rock volume and be received (Fig 1). The time taken can be converted to distance if the transmission speed of the pulse through the rock volume is known. The transmitted pulse may be reflected off a suitably orientated geological reflector (in reflection mode) or may be recorded in receivers located in other boreholes (cross-hole tomographic mode). In the Bushveld Complex lithologies, these radar systems have ranges of 30-50 metres in reflection mode depending on the electrical properties of local stratigraphic units. Both the Merensky Reef (MR) and the underlying UG2 have been shown to act as reflectors, which offer the opportunity of using BHR as an imaging or mapping tool. Reflection of the radar signal occurs wherever a strong contrast in dielectric constants occurs such as between norite and harzburgite or where chromitite stringers are present. [ ] Fig 1 Main elements of a borehole radar system Much experience has been gained in the practical application of BHR surveys in platinum mining. The value of a BHR survey is that it provides a continuous line of information to ?connect the dots? rather than a few discrete pierce points. BHR surveys can be used to mitigate risk in three crucial areas: ? Mine planning at the strategic as well as tactical level ? geotechnical evaluation of proposed shaft sites, detailed profiling or mapping of reef and disruptions of the reef such as faults, rolls and potholes; ? Mineral resource classification ? identification of structural discontinuities in orebodies affecting resource classification e.g. potholes and reef facies; ? Safety ? identifying areas with poor ground conditions that are often associated with faults, dykes and potholes.

Jan 1, 2007

By E. L. Montgomery

Salar basins in the Andean Highlands of Northern Chile contain ground-water resources which could be used to satisfy requirements for the mineral industry in the region. Salars occur in arid zones; average precipitation is about 200 millimeters per year at altitudes of about 4,000 meters, and average annual evaporation is two meters or more. The salar basins are hydrogeologic sinks where water flows from recharge areas at the margins of the basins to discharge areas at the salt encrusted salar at the lowest point of the basin floor. Groundwater circulation occurs principally in the alluvial and fractured bedrock aquifers. Results of pumping tests for exploration and production water wells indicate a range in maximum sustained pumping yield of 62 to 126 liters per second, and where abundantly fractured, ignimbrite comprises the most prolific aquifer. Chemical quality of groundwater is good. Long-term pumping from properly located production wells in the salar basins would result in lowering of groundwater levels and salvage of water in areas where groundwater is lost via evaporation.

Jan 1, 1986

Jan 1, 1879

THE treatment by chlorination of the Mount Morgan Gold Mining Company's ores was first accomplished, early in 1886, by a works having a capacity of 25,000 tons per annum. Shortly afterwards another works was established, capable of dealing with 50,000 tons per annum. The extraction of gold was originally successful and satisfactory, but running expenses were high, averaging £2 19s. 6d. per ton of ore treated. These works were believed to be the largest chlorination pJants in the world at that time. As might have been expected, the mechanical details and chemical process had not been perfected, and, moreover, both works were hurriedly built, and operating expenses were not then considered of such prime importance, as the ore at that time was of very high grade the large quantities of low grade ore since dealt with not being then considered, since the bulk of it was not even known to be in existence.These two works consisted of lock-breakers, high speed rolls, screens, elevators, &c., for crushing; a large number of small handrabbled reverberatory furnaces for roasting; one-ton chlorination barrels and three-ton leaching vats for chlorination.

Jan 1, 1910

By Jury C. G

A decade of expansion and high production targets have led to changes in the number and structure of the Mount Isa Mines Limited work- force. Falls in labour turnover and absenteeism are correlated with two demographic variables, improved selection and placement procedures and home purchase facilities. Some results of recent population surveys are presented and discussed in terms of future housing needs and potential employment problems encountered by school leavers.

Jan 1, 1974

By Mamookho Elizabeth Makhatha, Mbal Henock‑Michel Mwanat, Kubangala Brest Kasongo, Ntumba Edward Malenga

This study investigated the operating parameters that affect the kinetic dissolution of copper and cobalt from sulfidic ores. The sulfuric acid concentration, temperature, sodium chloride concentration, particle size range, and leaching time were selected to deduce the kinetic mechanism of the leaching reaction. Other parameters, such as a stirring speed of 250 rpm and the percentage solid 10% w/v, remained constant. The results reveal that an increase in acid concentration enhances the leaching rate of copper and cobalt. Copper and cobalt dissolution was positively affected by the addition of sodium chloride. The highest leaching rates of copper and cobalt were 24.71% and 15.65%, respectively. The chemical control and diffusion control by shrinking core models are well fitted as the kinetic models representing the dissolution of the minerals. The respective activation energies for copper and cobalt dissolution of 10.92 and 31.023 kJ mol− 1 for the chemical control and 18.83 and 37.28 kJ mol− 1 for diffusion reaction control were established from temperature-based experiments.

Aug 26, 2022

By Rodolfo Arnaldo Montecinos de Almeida

As escórias de forno elétrico a arco (FEA) têm diversas funções, entre elas a melhoria da eficiência energética através do fenômeno da espumação. Por isso o estudo das escórias é de suma importância nos FEA’s. Um dos fatores que determina a qualidade da espumação e a sua eficácia é presença de partículas sólidas na escória. A saturação de MgO é extremamente importante, pois além de garantir partículas sólidas garante também a compatibilidade química para minimizar o consumo do refratário. Neste trabalho, foi feito o estudo da saturação de MgO para escórias no sistema CaO-SiO2-FeO-MgO-Al2O3, onde avaliou-se a influência que a basicidade binária, os teores de FeO e do Al2O3 tem sobre o mesmo. Foram feitos diagramas ternários, onde viu-se as diferenças que os teores de Al2O3 tem sobre os campos líquidos e as demais fases presentes. Foram feitos os diagramas de saturação isotérmicos (ISD’s) encontrando os mesmos pontos de dupla saturação quando comparados com os diagramas ternários. Fez-se uma validação dos ISD comparando a posição de diferentes corridas com a energia elétrica consumida. Quanto mais próxima a corrida está da linha de saturação menor será seu consumo energético.

Aug 16, 2017

By S. W. Beckman, L. Williams, A. E. Seep, R. Fischer, J. Hubbard

Introduction The Summitville Mine located in southwestern Colorado was added to the National Priorities List in June of 1994. Summitville was the site of mining operations that began in 1873 with the discovery and development of gold placer and lode deposits in the late 1800's. The mine site is located about 25 miles south of Del Norte, Colorado in the San Juan Mountains adjacent to the Rio Grande National Forest at an approximate altitude of 11,600 feet. The site was mined for gold, silver and copper between 1873 and 1947. The Summitville Consolidated Mining Corporation, Inc. (SCMCI), a wholly-owned subsidiary of Galactic Resources, Ltd of Vancouver, Canada ran a large tonnage open-pit mine and cyanide heap leach operation from 1986 to 1992 (Pendleton and Posey, 1992) During the mine operation by SCMCI, approximately 10 million tons of gold ore was mined, crushed and stacked on a lined leach pad. Heap leach operations experienced water balance and unplanned solution discharges from the start of the mine life. Despite the production of 249,000 troy ounces of gold during the mine operation, SCMCI was unable to meet remedial requirements and notified the state of Colorado of its intention to file a Chapter VII bankruptcy in December 1992. The EPA Region VIII Emergency Response Branch took over site operations on December 16, 1992 to prevent a catastrophic release of hazardous substances to the environment. The multiple contamination sources at the mine site are due to both historic and SCMCI mining operations. Emergency response operations at the site have prevented releases of severely contaminated solution and a permanent treatment for all waste units at the site is under investigation. A Request for Proposal (RFP) was issued in October 1993 by Environmental Chemical Corporation (ECC) at the Request of EPA Region VIII, Department of the Interior and Bureau of Reclamation. The RFP requested that interested companies provide information on their ability to implement innovative treatment technologies to improve treatment efficiency and reduce treatment costs for remediation of the heap leach pad (HLP) spent ore and ore leachate solutions. Dames & Moore and Pintail Systems, Inc. (PSI) jointly submitted a proposal suggesting application of biotreatment processes for detoxification of cyanide in spent ore and HLP leachate solutions. The proposal was accepted for pilot and field demonstration under the SPA Superfund Innovative Technology Demonstration Program (SITE) with additional funding from EPA Region VIII. This report discusses the test program and results of a Focused Feasibility Study which demonstrated biotreatment processes for spent ore cyanide detoxification.

Jan 1, 1995

THE Institute met on Wednesday evening, May 22d, in the parlor of the Stanton House, Dr. T. Sterry Hunt, President, in the chair. The President delivered an introductory address on the Brown Hematite Deposits of the Great Valley, after which the following papers were read and discussed : Note on the Result of an Experiment with the Wheeler Process of Combining Iron and Steel in the Head of a Rail, by W. E. C. Coxe, of Reading, Pa. On the Jenks Corundum Mine, Macon County, N. C., by Dr. R. W. Raymond, of New York City. On Wednesday afternoon, previous to the opening session, the members who had already arrived in Chattanooga, were taken by the Local Committee to the works of the Roane Iron Company, and Chattanooga Iron Company, and then to the top of Lookout Mountain, where, at the request of the members present, Dr. Hunt described the geological and geographical features of the Chattanooga region, with the magnificent panorama spread out before them as a map. On Thursday morning an excursion was made by steamboat down the Tennessee River as far as Shellmound. Here cars were taken to the coal mines of the Dade Coal Company, where the members were courteously received by Mr. E. B. Wells, the Superintendent. After a trip through the mines the party partook of a collation provided by the company. South Pittsburgh, on the Tennessee River, was next visited, where the Southern States Coal, Iron and Land Company have a large blast-furnace plant in the course of erection. After conducting the party through the works, shops, etc., Mr. James Bowron, the manager, entertained the members with graceful hospitality at dinner. The second session was held on Thursday evening for the transaction of business. The President, Dr. T. Sterry Hunt, appointed Messrs. W. E. C. Coxe, R. H. Richards, and F. J. Slade, scrutineers, to examine the ballots for officers for the ensuing year.

Jan 1, 1879

By L. A. Stinnett

An investigation of hazardous surface openings of abandoned and inactive underground mines in the Black Hills area of South Dakota has revealed: (1) tracing legal ownership of mineral claims via county courthouses is confusing, complex, and oftentimes misleading, (2) in general, the selected mine openings in this investigation are to be considered relatively high in risks and hazard potential which poses a threat to the general public, (3) mine closure procedures and designs can generally be categorically implemented depending on the overall situation of the particular mine opening with subsequent unit costs estimates, (4) few preventive state or federal legal measures exist to date concerning mine closures, and (5) liability damages relating to mine opening accidents usually involve expensive and complex common law cases.

Jan 1, 1979

By A. S. Richardson

THE design of mine airways receives, in general, very little engineering treatment. To a large extent this is, of course, due to the fact that information upon which to base calculations is seldom available in definite form. In many mines the extent of the workable deposits may not be known at the time an air course is planned, and the length of service is indeterminable. Volume of air required for ventilation may also increase with extension of the life of a property, and natural obstacles, such as heavy ground, often place limitations upon the size of opening that can be maintained. Perhaps a majority of the shafts used in ventilation of metal mines were originally intended as hoisting shafts, and many of the tunnels and cross-cuts similarly used, were also designed as haulage ways or for other operating purposes. Even when a shaft is sunk solely for ventilation, custom usually dictates a size and shape consistent with the type commonly used for ordinary operations, because experience has demonstrated it can be excavated and maintained. In fact it may not be very far wrong to say most ventilation openings were never made with any consideration as to economic design for such use. When an air course is required to pass air between different parts of mine workings under a fixed pressure, the size of opening required for a given volume of flow, is, of course, determined by the resistance factor of the air course. It is then impossible to proportion the opening with reference to economics of power consumption, and this paper is limited to the design of openings where ventilation pressure or power consumption may be varied for economic advantage.

Jan 2, 1926

A rotating disc geometry was used to provide a uniformly accessible surface for a kinetic study of copper cementation with zinc in sulphate solution. For copper concentrations of the order of 10 p.p.m., a porous, adherent deposit is formed on the zinc surface and this has a significant influence on the reaction rate. When the specific mass of deposit is less than about O· 35 mg/cm2 the surface may be considered as smooth and the rate is described by simple convective counter diffusion of zinc and copper ions through a laminar diffusion boundary layer to the deposit-solution interface. In the presence of additional deposit, the diffusional mass transfer rate is increased by increased surface roughness.The rate under these conditions is first order, with the degree of enhancement independent of further increases in the specific deposit mass. The enhancement in rateis, however, directly related to the initial mass flux and the species involved in the reaction.Preliminary work showed the same mechanism to apply to cementation from chloride solution, solutions of high zinc concentration, and cementation of copper with iron..

Jan 1, 1970

The Ore Reserve System implemented at Mount Isa for Mount Isa Mines Limited is a comprehensive' computer system designed to process assay, geological, structural and survey data for Isa and Hilton Mines. This paper outlines the achievements of this system to date and by example, discusses the various reports and plotted output available. __ The impact of the ore reserve system particularly within the-Geology and Mine Plan ning Departments is reviewed in terms of new approaches to ore reserve calculations, evaluating the economics of various mining methods and reviewing preliminary stope designs. The compilation of metal distributions for both copper and lead orebodies at varying cut offs and reducing the involvement of skilled personnel in preparing non-standard plots of borehole paths are discussed. Options available through the system and their applications are outlined together with the planned future development of the system.

Jan 1, 1974