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By H. A. Pearse

NORMALLY, the Britannia ore mixture contains chalcopyrite and pyrite as the chief sulfide minerals, together with minor amounts of gold and silver and a low zinc content. Reduction is accomplished by jaw crushers underground, followed at the concentrating plant by Symons cone crushers, rolls, and ball mills. The standard flotation practice, evolved during several years of experimentation, provided for bulk flotation of the two sulfides, after primary grinding to only approximately 35 mesh, followed by regrinding of the bulk concentrate, with subsequent separation of the chalcopyrite and pyrite to make a marketable concentrate of each mineral. This so-called standard milling practice has previously been described in detail in U. S. Bureau of Mines Information Circular 6619. A modification will he discussed here. In the face of a constantly increasing world surplus of copper and a steadily falling price during 1930 and 1931, it was obviously undesirable to continue unprofitable production of large quantities of this metal. On the other hand, company officials were

Jan 1, 1934

By J. F. Lupo

There are numerous mines throughout the world that have open pit highwalls developed partially or wholly in soil or soil-like materials. Soil-like materials are considered to include soils (either transported or residual) and highly weathered rock, which may have soil-like behavior. These materials generally have characteristics or material properties that vary considerably from those of moderately weathered or fresh rock. Given these differences, it is important to consider the characteristics of soil-like materials to design safe open pit slopes. In the design of open pit slopes in soil-like materials, it is important to recognize the behavior of these materials is strongly dependent upon their mineralogy, degree of weathering, cementation, stress history, depositional history, and presence of water. As a result, soil-like materials may contain one or more of the following characteristics that can have a significant effect slope stability and design: - Relict structural features (joints, faults, etc), - Sensitivity to moisture (both wetting and drying), - Zones of alteration with variable strength and drainage characteristics, - Zones of low permeability creating perched ground water conditions, and - Undrained and drained strain softening or strain hardening behavior.

Jan 1, 2011

By Tuan V. Nguyen, Louis Mittoni, Murray Rudman, CSIRO Minerals, Jean D. Swift, John B. Farrow, Phillip D. Fawell

"Research projects towards developing a sound understanding of the factors controlling the performance of gravity thickeners have been conducted by the AJ Parker Cooperative Research Centre for Hydrometallurgy since 1988 through AMIRA International. The current phase of this work, the three year P266D “Improving Thickener Technology” project, has 27 sponsors comprising mineral processing companies, reagent suppliers and thickener manufacturers.These projects have resulted in the development of a range of tools and techniques to address flocculation, thickening and associated dewatering issues. A number of Computational Fluid Dynamics (CFD) models have been developed to predict likely full-scale thickener performance under various process conditions, based upon a knowledge of thickener design, plant flows and assessment of the flocculation behaviour of the feed slurry. At the same time, various laboratory and plant studies have been used to quantify important thickener processes, and to provide validation of the CFD models. These numerical and experimental capabilities have been applied to various thickener issues across a broad range of mineral processing operations, leading to significant process improvements and substantial financial benefits.This paper presents an overview of the work conducted during these projects, focussing on the research tools, the nature of the information that has been gained and the implications for thickener performance."

Jan 1, 2003

By Carolyn Kenney, Jianjun Liu, Zhenghe Xu

"The flotation of fine particles has been a challenge to scientists and engineers in mineral processing. A novel concept of reactive oily-bubbles as carrier to float fine particles is described in this paper. The reactive oily bubble flotation is considered attractive for fine particle flotation. In addition to the role of fine particle agglomeration by oily films, the surface properties of air bubbles coated with a thin oil film can be better controlled for the desired selectivity by adding certain types and concentrations of water insoluble collectors into the oil phase. This approach can eliminate the addition of collector to the aqueous phase, avoid undesired synergetic interactions among collectors, activators, depressants and dispersants present in slurry, minimize undesired activation of gangue particles and significantly reduce the amount of collectors needed.The concept of using reactive oily-bubble to achieve selective flotation was demonstrated in contact angle measurement and by microflotation tests with fine sulphide minerals: sphalerite and galena in this paper. The flotation behavior of sulfide minerals can be radically modified with adjustment of solution pH, addition of depressant and activator as in conventional flotation. The successful separation between PbS/SiO2, ZnS/SiO2 and PbS/ZnS was demonstrated using mixed mineral systems. Compared with conventional flotation, the reactive oily-bubble flotation showed a stronger collecting power.INTRODUCTIONThe challenge for fine particle flotation has long been recognized and well documented (Fuerstenau, 1980). Because of drastic changes in surface properties of fine particles and associated physicochemical and hydrodynamic conditions of flotation systems, fine particles responded poorly to the conventional flotation processes. For instance, the small mass and hence low inertia of fine particles would result in a low efficiency of collision and attachment of fine particles with flotation bubbles. Large specific surface area of fine particles, on the other hand, would cause an increased reagent consumption. Dominating colloidal forces of fines may cause slime-coating, accompanying a low selectivity (Somasundaran & Arbiter, 1979; Fuerstenau, 1980; Sivamohan, 1990)."

Jan 1, 2003

By Phillip N. Yasnowsky

The thrust of this Bureau of Mines report is to relate the size of automobiles to the price of gasoline, and the use of minerals in automobile manufacture to the size of automobiles. Only one of the many plausible scenarios of public reaction to higher gasoline prices, a switch to economy size automobiles, is developed. No account is taken of other potential impacts such as improvements in public transportation or increased occupancy per vehicle. Furthermore, a gasoline price increase is the only incentive to the greater utilization of economy cars that is considered. A gasoline price increase to $0.60 per gallon would reduce the amount of minerals required to produce the automobiles sold in the United States by an estimated 15 percent. Gasoline prices of $0.80 and $1 per gallon would cause declines in mineral requirements for U.S. automobile sales estimated at 26 percent and 35 percent, respectively.

Jan 1, 1974

By E. H. Cho, B. Conner

Three sulfide minerals, chalcopyrite, sphalerite, and pyrite, were leached using a bioleaching mode and an electrobioleaching mode. The former mode was used to leach the minerals with the bacterium A. ferrooxidans in a bioreactor. In the latter mode, the leaching of the minerals was performed in a combination of a bioreactor and an electrochemical cell. In this set-up, the solution was circulated between the bioreactor and the cathode compartment, the two reactors were in series, and the cell was operated intermittently. The mechanism is such that an increase in Fe(II) concentration, which is a nutrient of the bacteria, by electrochemical reduction of Fe(III) would increase the bacterial population and in turn would accelerate the leaching of the mineral. It has been found that the electrobioleaching of chalcopyrite is an improvement over the bioleaching with respect to the fact that leaching conversion is higher and a high level of Fe(II) concentration can be maintained. However, the electrobioleaching of sphalerite does not show any improvement over bioleaching. The electrobioleaching of pyrite is similar to that of chalcopyrite, and this has potential to be used in applications such as coal desulfurization and pretreatment of refractory gold ore in heap leaching where fine gold particles are entrapped inside pyrite particles.

Jan 1, 2006

By A. C. Veatch

Jan 1, 1921

By J. Weinstein

New erosion, corrosion resistant metal, ceramic, and polymer composite technologies are being developed and marketed by Alanx Products L.P. for use in hydrocyclones, pumps, valves, and other applications in mining and minerals processing. This paper will present an overview of the ceramic/metal composite material system and properties developed, which include excellent erosion/ corrosion resistance. Wear data will be shown from a variety of laboratory tests in dry and wet conditions, in aqueous neutral and corrosive environments. Comparisons will be made with a variety of competitive materials currently used in the industries sited. Data will also be presented on field tests with pumps and hydrocyclones in hard rock mining and other abrasive/corrosive environments. Field data from North and South America, as well as Australian mining applications will be highlighted.

Jan 1, 1992

By J. Humphries

With today?s turbulent markets and unprecedented global opportunities, the need to optimize net present value and internal rates of return from capital investments has never been greater. To help address the need, this paper presents an overview of the key processes and strategies for achieving maximum return from capital projects. Best practices discussed address stage gate management for project evaluation, selection, and oversight, project execution efficiency, value improving practices, operational readiness, and operational excellence. The paper also includes a model of key metrics and benchmarking with tips for application. [ ]

Jan 1, 2011

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigation beginning with No. 4251, of which this is the eleventh. The-data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each halt township is followed by a description of each deposit developed in that halt township. The 14 halt-township maps and 77 detail maps of the bauxite deposits in this series at reports give the locations and numbers of all the holes drilled on the project, except the deep holes drilled to test the geophysical anomalies. The locations of those holes show on figure 13 in volume 1. The descriptions of the deposits developed are followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained tram the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each halt township is given with the discussion of that area.

Jan 1, 1948

By N. R. Shoko, J. Chirasha

Zimbabwe Alloys has been producing Low Carbon Ferrochrome since 1953. A number of operational and technical advances have been made since then. Some of these advances improved production significantly. Process control, however, remained a challenge not only in the production process itself but also in the handling of finished product. In addition the handling of the slag created an environmental problem. Process control issues were addressed by Zimbabwe Alloys Limited and Japan Metal & Chemicals (JMC) entering into a Technical Transfer Agreement. The aim of the technical transfer was to improve production, alloy quality and, thereby, the financial performance of Zimbabwe Alloys. In addition, the Low Carbon Ferrochrome production process was made environmentally friendlier by modifying the final slag handling methodology. The aspects that are covered and discussed in this paper are, ladle refractory lining changes, improved control of the process, changes in the alloy casting methodology and granulation of the final slag. The improved control of the process was enhanced by the conversion from ladle duplexing to argon purging, introduction of on-line sampling and introduction of second stage process. The combined effect of the above was a significant improvement on on-grade material production, production efficiencies, unit cost of production and a cleaner working environment.

Jan 1, 2004

This is an abstract from Environmental Service and Technology (Vol 32 No 20 1998) which will be o finterest to South African Mining and Metallurgical Scientists, involved in chromium mining and Metallurgical processing. Maybe the scourge of our dams and reservoirs?the water hyacinth can be put to good use! The novel technology of phytoremediation embraces plant accumulation processes for the cleanup of toxic heavy metals and organic chemicals. Several plant species have been identified that are excellent hyperaccumulators of a number of heavy metals, e.g., Brassica juncea (Indian mustard) and Thlaspe caerulescens (Alpine pennycress). Other speciesincluding Myriophyllum brasiliense(Parrot?s feather), Salixsp. (willow), and Popullussp. (poplar) have also demonstrated phytoremediating abilities.

Jan 1, 1999

By B. J. Vorster

AngloGold South Africa region currently consists of twelve gold plants. These plants use a combined total of $20 million of cyanide per annum. Of this, the major portion (60%) is consumed at two Ergo dump retreatment plants. Historically the primary motivation for cyanide control at Ergo has been one of leach/cost optimization. However, more recently, with the increased public awareness of cyanide in the environment, a secondary but increasingly important motivation for control has been to ensure that only the minimum amount of cyanide is added to the process whilst not compromising leach performance. Following a brief overview of the Ergo process, the methodology in determining the amount of cyanide to be added is described. The paper then traces the developments in cyanide control from very basic manual systems to the current automated control system. In line with the increasingly sophisticated control systems, developments also took place in regards to the method of cyanide analysis. The development of these analysers is also discussed. Whilst cyanide is one of the major drivers, if not the major driver of gold dissolution, it cannot be viewed in isolation particularly with respect to the relationship between cyanide and oxygen as ascertained from the Elsner?s well-known equation. Consequently, in order to control cyanide addition, knowledge of the relative cyanide/oxygen profiles is necessary. Various means investigated at Ergo for pulp oxygenation have therefore been included for the sake of completeness. Finally a comparison is made of the control achieved from the current system compared to the original manual system. The knowledge and experience gained at Ergo is now being used to draw up guidelines for the installation and optimization work at the other AngloGold plants. The net effect of this will be reduced cyanide consumption for the region, which also, apart from the obvious economic benefit, translates into a reduced environ-mental risk.

Jan 1, 2001

By David P. Reddick

"Suncor Inc. Oilsands Group mining operation in Northern Alberta, Canada, has been blasting to loosen the oilsands to increase production and decrease maintenance of the bucketwheel excavators for over twenty years. In 1991 an area of the mine was encountered which had a working face of 130 feet rather than the usual 20 to 57. In order to maintain production objectives, the planning and blasting departments of the mine took on the task of blasting as much of the working face as possible. McGinnis Rathole Drilling Company provided the drilling for the project and Mining Services International (MSI) delivered the bulk explosives to the boreholes. It is believed the resultingblasts exceeded several known records in production blasting."

Jan 1, 1992

By Dianne M. Lapierre

Mining firms in Canada are increasingly incorporating the social and environmental interests of their stakeholders into their projects in an effort to become more sustainable. Such initiatives have included negotiating Impact and Benefit Agreements (IBAs) directly with would-be impacted, often aboriginal, communities near resource developments in the Canadian north. Why does a mining firm take on this extra time-and cost-intensive initiative when governments and regulatory measures are in place to address social and environmental issues? Past research has paid little attention to the corporate rationales for IBAs. Based on document review and interviews with mining executives, this study investigates the rationales of mining firms that ?over-comply? with legislative requirements by negotiating IBAs or similar types of agreements with communities. The results indicate that mining firms increasingly recognize IBAs as an intrinsic part of the permitting process. When queried, executives regularly identified the negotiation of agreements as ?the right thing to do?. While this response could be read in ethical terms, a commercial rationale is also clearly present. By building strong relationships with nearby communities, addressing community concerns, and directing benefits to local people, all of which are explicitly achieved with an IBA, mining firms are maintaining their long-term financial viability, thus their sustainability, within an evolving industry.

May 1, 2008

By B. Cousins

Copper, nickel, zinc and other ?penalty? metals are found with gold together in nature, and have a similar chemical affinity for cyanide used in leaching operations4. As a result, solutions that come from the heap leach pads contain a significant concentration of penalty metals along with the desired gold. In solution, gold and cyanide form the complex Au(CN)2- that is readily adsorbed onto activated carbon. Penalty metals as individual metal ions also load onto activated carbon and, depending on the concentration of cyanide and the pH of the solution, can form various cyanide complexes. Some of these complexes can also load onto carbon while some are significantly inhibited from loading. Copper, for example, can form the dicyanide complex Cu(CN)2-, the tricyanide complex Cu(CN)32-, and the tetracyanide complex Cu(CN)43-. At a low pH and a low concentration of cyanide, the dicyanide complex predominates. At a higher pH and a higher concentration of cyanide, the tetracyanide complex predominates. Without excess cyanide, however, individual copper ions can remain present. Activated carbon is used in gold extraction because it is highly selective for gold and less so for other metals, such as copper3. However, copper has the ability to adsorb (?load?) onto activated carbon and block the adsorption of gold when it is in the dicyanide form and in a high enough concentration. When copper is in the tetracyanide form, copper loading is significantly inhibited, allowing for the maximum gold recovery. In order to ensure the tetracyanide complex is formed, a combination of both available cyanide and elevated pH must be present. In the South Area of Newmont Mining Corporation?s Gold Quarry mine in Carlin, Nevada, copper and nickel loading becomes a problem when certain acid generating zones of the heap are leached. Copper, nickel, zinc and other penalty metals become leachable and the lower pH uses up more of the cyanide and creates carbon loading conditions for the metals. This decreases the carbon?s ability to extract the gold from solution, decreasing the recovery and increasing the concentration of gold in the barren solution that leaves the carbon columns. In this study, operational data from March through to May of 2007 is presented to show how Newmont developed a quick fix to lower pH and elevated metal concentrations that were causing low gold loadings on activated carbon at their South Area Leach (SAL) heap leach operations. Laboratory tested were also conducted to examine the chemical kinetics of metal loading and the individual effects of increased cyanide concentrations. THEORY Copper I ions form four different complexes with cyanide in solution: the monocyanide species CuCN, the dicyanide species Cu(CN)2-, the tricyanide species Cu(CN)32-, and the tetracyanide species Cu(CN)43-. The species are formed from the following reactions: [Cu)(?+-+ K1 (1) Cu ß2 (2) --+?+23)(3CNCuCNCu ß3 (3) --+?+34)(4CNCuCNCu ß4 (4) ] where K1 equals 1019.50, ß2 equals 1024.03, ß3 equals 1028.65, and ß4 equals 1030.35. Along with these complexing reactions, hydrogen cyanide and water also dissociate in solution, as per the following reactions: [H?+-+ KH (5) OHOHH2?+-+ KW (6)] where KH has a value of 109.24 and KW has a 1014 value2. These six chemical equations compete with each other, with domination of one over the others dependent on the CN- and H+ concentrations. Each complex also has different properties when it comes to its loading behavior on activated carbon. The dicyanide copper complex and the monocyanide copper complex have an affinity for adsorption onto activated carbon that is greater than the affinity of gold cyanide for adsorption. They also have a lower solubility in water, which enhances adsorption. The tricyanide copper complex and the tetracyanide copper complex are water soluble and have an affinity for loading adsorption on activated carbon that is less than the affinity of gold cyanide for loading adsorption1. There are three prime reasons for this phenomenon. First, the extra cyanides mask the metal ion more, which blocks the main adsorption characteristic of the complex. Second, the complexes are also larger, making it harder to physically fit into the active sites on the carbon. This helps make the latter two complexes kinetically inhibited from adsorption, freeing carbon active site to load with gold cyanide complexes. Third, it is also important to consider the expressions of the mass and charge balance. These balances describe all the overall concentration of copper and cyanide in solution, as well as marking overall charges of the ions in solution4. This is important because significantly changing the charge from positive/neutral to more negative is another reason for activated carbon to reject adsorbing the higher cyanide complexes. The speciation of copper and other penalty metal cyanide complexes in solution is dependent on the pH. At lower pH values, increased hydrogen ions (H+) can out-compete metals for cyanide ions. Lower free cyanide in the system leads to the lower cyanide species of copper cyanide predominating, with a noticeable concentration of the free metal, monocyanide and dicyanide species of copper cyanide. At higher pH values, hydrogen ions are significantly reduced, reducing the kinetics of HCN formation. More free cyanide remains in the system, allowing for more complexing. With this higher amount of cyanide in the system, the tetracyanide species of copper cyanide predominates, also with a noticeable concentration of the tricyanide species of copper cyanide. Higher copper concentrations, however, require more

Jan 1, 2009

By T Hicks

Designers of mining facilities play a significant role in defining the overall mine greenhouse gas emissions performance. This demands an appreciation of all the greenhouse gas emissions sources, including Scope 3 emissions, which will form an increasing fraction of the emissions as we transition our generation sources to renewable energy. Traditionally overland conveyors are designed to operate as fast as practical, and through this approach, achieve relative minimisation of: conveyor belt tensions; belt width; mechanical equipment masses; structural steel quantities; and concrete quantities. It is well understood that higher belt speeds reduce capital cost and improve project economics. Operating at higher speeds introduces operating costs through system energy losses and increased wear rates. This paper assesses the life cycle greenhouse gas emissions for a typical iron ore overland conveyor to demonstrate how the design criteria and engineering decisions impact greenhouse gas emissions and project economics. An analysis of the decarbonisation potential and project economics using a range of operational parameters has been completed, developing a marginal abatement cost for each system configuration, creating a basis for integration of low emission overland conveyor designs as part of the broader facility decarbonisation strategy.

Sep 1, 2024

By Chao Li, Shuai Wang, Hongxu Li, Lifeng Zhang, Xie Yang

The method of chloride-hypochlorite leaching has the advantages of short process, low pollution and higher in reaction rate compared with the traditional leaching method. In this research, NaCl - NaClO solution is used to leaching gold from a refractory gold concentrate, and the influence of NaCl and NaClO concentration, reaction time to the leaching rate were investigated in this experiment. The raw materials and the leaching residue were characterized by a series of analysis methods such as XRD, XRF, SEM and EDS. Results indicate that the leaching rate and the desulfurization rate can be achieved at 96.26% and 98% with most optimum conditions as follows: NaCl concentration 50g/L, NaClO concentration 200g/L, Liquid-solid ratio 10:1, the best reaction time was 150 mins. And these conditions should be guaranteed pH<8.0, ORP>900mV.

Jan 1, 2015

By M. J. Beus

The U.S. Bureau of Mines is conducting investigations to improve design methods for mining volcano-genic massive-sulfide (VMS) type deposits in environmentally sensitive regions. This study was conducted at the Greens Creek Mine, which is typical of many VMS-type deposits throughout southeast Alaska, and served as a case history for computer modeling and structural analysis. Results indicated that the finite-element design method provided reasonable comparisons with both the anticipated regional stress regime and the measured deformational response of the underground accessways. Investigators concluded that reasonable accuracy can be expected for stability analyses of proposed mine design scenarios at this mine using the results of this preliminary study.

Jan 1, 2010

By Gary A. Kingston

This examination of Pacific Northwest (Idaho, Montana, Oregon, and Washington) ferrous scrap-industry operations, principally those in Oregon and Washington, points out factors influencing the supply and consumption of scrap materials, such as the complete dependence of steel ingot producers in these States on scrap as a metal raw material and the sizable quantity of scrap exported from Seattle and Portland to Japan. The pattern of the industry is presented as a movement of materials from their diverse sources to the consuming market. The geographic locations of the consuming industries in relation to the areas generating scrap materials and the movement pattern of the supply from source to destination strongly influences the cost of the commodity. The best measure of the scrap supply available in an area is experience in terms of how much scrap was withdrawn at a given price. Scrap availability is not finite, because the return of materials as scrap is secular and influenced by constantly varying market conditions. Steel ingot producers use 75 percent of the approximate 500,000 tons of scrap consumed in Oregon and Washington; steel foundries take 15 percent of the total; and iron foundries, ferroalloy plants, and other miscellaneous consumers utilize the remainder. Also, from 1955 to 1960 an average of about 200,000 tons has been exported annually from Oregon and Washington. The foreign exports are supplemented by lesser shipments to other steel producing States, principally in the western United States. From 1955 to 1960 the preferred and higher value heavy melting scrap grades accounted for about 60 percent of total withdrawals which varied between 600,000 and 950,000 tons annually. Total crap withdrawals from Oregon and Washington are projected to 1.8 million tons by 1985, 60 percent (1.1 million tons) of which will be heavy melting grades. No. 1 heavy melting scrap is most attractive to scrap consumers at $35 per ton or less. Price-supply relationships compared with projected scrap requirements indicate future prices possibly over $35 per ton. High prices over a long period could motivate the Pacific Northwest scrap consumers to produce steel from iron ore. However, technologic changes taking place at integrated steel plants could reduce scrap withdrawals from the Pacific Northwest, which might keep the scrap price sufficiently attractive to obviate production of competitive iron products by the Pacific Northwest scrap consumers.

Jan 1, 1964