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By John L. Halls

Modern business practice dictates that in order to ensure the economic optimization of investment, the size of any investment venture must be such that every increment of capital invested in such a venture yields at least a corporate minimum acceptable rate of return. This practice is based on the premise that alternative investment opportunities capable of yielding the minimum corporate return are immediately available. If a mining corporation is to make the maximum use of its investment funds, any capital investment in a mining property must comply with the above practice. The most important parameter in estimating ore reserves is the cut-off grade which is used to separate material into ore or waste. The cut-off grade is calculated on the basis that material of cut-off grade produces sufficient revenue to cover the estimated costs of mining and processing through to sales, including depreciation and produce a pre-determined profit. Ore reserves so estimated are adequate for determining the magnitude of an orebody but do not provide a sound basis for determining plant size and therefore capital investment in a new property or for expansion consideration on an existing property. From a financial analysis of this one ore reserve it is impossible to ascertain whether each increment of capital investment is providing the minimum acceptable rate of return, Other difficulties associated with the calculation of a cut-off grade including the determination of depreciation and the amount of pre-determined profit to be included in the cut-off grade calculation are outlined in the text. The proposed solution to determine optimum ore reserves and plant size for new properties avoids the complication of calculating a cut-off grade by computing a series of ore inventories using arbitrarily selected cut-off grades. A comparison of the cash flows generated by production from such ore inventories using incremental financial analysis clearly indicates the ore reserve and plant size which will best serve the corporation's investment and metal production goals. Incremental financial analysis of a corporation's operating mines and prospects assists management in assessing the comparative expansion and investment possibilities of each property for increasing or maintaining metal production on a long term basis.

Jan 1, 1969

By H. Suharyono

The results of an experimental study of polymer-induced flocculation of clay suspensions in continuous, stirred-tank reactors are presented. The effects of polymer dosage, mixing time and mixing intensity are shown to be generally similar to those observed for equivalent batch systems, but flocculation appears to be generally less effective in the continuous process. Settling rates are lower and supernatant turbidities are higher for the continuous system. It is postulated that non-equilibrium effects due to simultaneous polymer adsorption and floc growth can be exploited so as to enhance flocculation in batch systems. The nature of the continuous process, however, offers less opportunity for taking advantage of such effects. Conditions in a continuous flocculation system inherently lead to a closer approach to equilibrium.

Jan 1, 1994

By Parris A. Lyew-Ayee

The Government or Jamaica has just completed agreements with four of the five bauxite/alumina companies operating in Jamaica. These companies are Kaiser, Reynolds, Alcoa, and Alcan, and the Agreements came into effect on February 1, 1980. One of the results of these new Agreements is the Acquisition of all company-owned bauxite lands by the Government and the rationalization of bauxite reserves.

Jan 1, 1980

By J. Launay

In order to control and dispatch the sewage water coming from 3 tunnels toward 2 downstream sewage tunnels, a large cavern has been excavated in a suburb of PARIS. Located at a depth of 47,00 m, it has been excavated using the NATM procedure through swelling clay, weathered sandstone, and marl and chalk. It is 16,50 m high, 12,40 m wide and 60, 00 m long, with an elliptical cross-section and its two ends are egg-shapped. The final lining of the cavern is composed of 30 to 40 cm of shotcrete, steel ribs and passive anchor bars. The excavation stages and related movements were surveyed by extensometers, pressure cells and convergence devices. The design, method of construction of the cavern and the results of the measurements made are commented.

Jan 1, 1989

By H. Chu

Selective Agglomeration experiments carried out to clean ultra-fine coal are examined. Effect of feed size, pulp density, coalescing agent dosage, and mixing intensity and duration on the kinetics of agglomeration are principally evaluated. A computer coded population balance model governing agglomerate size distribution and composition utilizing coalescence and breakage mechanisms is developed. Model calibration, verification and extension are analyzed.

Jan 1, 1987

By S. K. Sharma

The Bureau of Mines' rapid method of dewatering fine-particulate slurries uses extremely high molecular weight polymers. These polymers form large, strong flocs which can be dewatered by sieving or sedimentation. However, sometimes these flocs deteriorate rapidly if water is not removed immediately. During field tests, clay slurries have been encountered that could have been dewatered economically if it were not for the rapid floc deterioration. A kinetics study was conducted to determine the rate of kaolin-PED floc degradation in which polymer addition, to bring the flocs back to their original condition, was used to determine the extent of floc decay. Results showed that the amount of polymer added, to replace polymer lost by spreading, was less for the lower PEO concentrations. For this clay-polymer system, floc breakage as judged by polymer additions followed first order kinetics. It was also found that the addition of fluoride ion stabilized the kaolin flocs.

Jan 1, 1992

By R. K. Will

An inactive mining operation in northern California is known to be a source of acid mine drainage and heavy metals which have impacted adjacent creeks. Elevated concentrations of copper and zinc are a concern to aquatic populations, particularly steelhead trout and salmon downstream in the Sacramento River. Previous regional geological surveys of mineralization by the U.S. Geological Survey located and mapped outcrops of massive sulfides and gossan. Recent investigations indicate that a substantial amount of the metals in the local creeks are due to natural causes. The investigations include locating and mapping surface and subsurface minerals, soil and water sampling, and chemical analysis. Groundwater, seeps, and surface water were also sampled and analyzed. A water balance was conducted on a sub-basin level following delineation of surface water drainage and groundwater divides. A chemical mass balance incorporated metal concentrations and water volumes and was then used with other data to determine the contribution of metals from natural versus mining-related causes.

Jan 1, 1998

By R. M. Cox

Pneumatic coal loading and conveying systems provide alternative methods for the safe and efficient mining of the thin high-grade coal seams found in the Southern Appalachians. Pneumatic systems eliminate most of the health and safety hazards associated with the operation of conventional mining and haulage equipment in small low-coal mines by removing powered mobile equipment from the mine. Ventilation is also improved by the coincidental removal of gas and respirable dust from the mine by the operation of the pneumatic loading and conveying system. Other significant advantages of pneumatic coal recovery systems are relative simplicity, operating flexibility, low capital cost, quiet operations, environmental benefits, and ease of automation. The design considerations and field evaluations of experimental prototype pneumatic coal loading and conveying systems, installed and operated in small thin-seam mines, are presented in this report. In addition, fundamental design criteria and recommendations for the installation and operation of a variety of pneumatic coal loading and conveying systems are proposed, which offer alternative coal recovery systems that alleviate the serious health and safety concerns of current small mine operations.

Jan 1, 1999

By Gill Montgomery

Although fluorspar is considered an industrial mineral by usage and value, its geological occurrence and the mining and milling methods employed make it more akin to the non-ferrous metal ores. Likewise methods of exploration for it are more like those used in the search for lead and zinc, with which fluorspar is often mixed. In fact, it often takes the mixture of fluorspar, lead, zinc, plus maybe barite to add up to enough recoverable values to make the mineral an ore by definition. This is so true where the fluorspar portion is low grade, perhaps less than 25 percent. Until the development of modern steel milling in World War I times, the invention of aluminum smelting, and development of the fluorine chemical industry and air conditioning, there were few uses for fluorspar aside from ceramic fluxes in the flint glass industry and for uses as glazes for pottery and china. Pure fluorite crystals have long been admired as semi-precious and ornamental minerals of many delicate colors.

Jan 1, 1983

By R. Bhaskar

The objective of the project was to optimize the ventilation parameters of a continuous miner underboom scrubber to further control. the amount of airborne dust discharged during mining, to further reduce the exposure of face personnel for an exhaust brattice ventilation system, and avoid recirculation of contaminants at the face. This research was performed in an underground coal mine in Utah. The tasks included preliminary face ventilation evaluation and optimization of the scrubber system to eliminate recirculation of the scrubber discharge air. Airflow tests were conducted on the currently used dust control system and the modified scrubber system. Tracer gas tests were performed to evaluate face ventilation effectiveness. Confirmatory tests of the scrubber system under actual operating conditions, modifications to the scrubber system, and a comparative evaluation of the scrubber system vs. the existing system were performed. This paper presents the results of the airflow pattern tests and the respirable dust levels in the modified scrubber system and the existing system. The optimized face ventilation parameters and the developed operating guidelines may provide the benefits of dust reduction, better face ventilation, and improved visibility.

Jan 1, 1994

By Christophe Bragard, Marte Gutierrez, Haotian Zheng, Michael Mooney

This paper proposes a framework for applying surrogate-based approaches to evaluate SEM construction, which can both benefit the uncertainty analysis in the design stage and real-time calibration during the construction process. The performances of four surrogate modeling approaches, namely back-propagation neural network (BPNN), support vector regression (SVR), random forest (RF), and polynomial chaos expansions combined with Kriging (PCK), were evaluated and compared. A variance-based global sensitivity analysis (GSA) was performed on the surrogate predictor to quantify the impacts of geotechnical parameters on the deformation responses induced by SEM tunneling. The Regional Connector Crossover Cavern project constructed in Downtown Los Angeles was set as the benchmark problem to demonstrate the efficiency and reliability of the proposed procedure.

Jun 13, 2021

By Zygmunt Sadowski

Problems encountered in barite flotation from various waste materials such as spent drilling muds are likely to be closely connected with the effect of chemical additives and metal ions present either added or present as contaminants, on the flotation. Fuerstenau and Palmer (1976) have studied in detail the adsorption of multivalent cations onto oxide and silicate minerals. It was observed that the adsorption of a multivalent metal species exhibits a sharp pH dependence which is related to the formation of hydroxy complexes of the metal ions in solution. Investigations on the recovery of barite from tailings ponds and mining wastes (Sullivan and Lamot, 1981) have shown that such barite materials can contain large quantities of carbonate and silicate minerals (including clay minerals). Also iron oxide slimes can be present. From these substances cations such as Ca2+, Mg2+, Fe2+ and A13+ can potentially dissolve and be present in the aqueous phase accompanying the various minerals. These ions and their hydrolysis products can have a substantial effect on any subsequent flotation scheme. The present study investigates the effect of the noted ions on both the stability and electrokinetic behavior of barite suspensions.

Jan 1, 1986

By D. C. Seidel

The role of surface charge in soluble salt flotation, which was developed in Part 1, is extended to relate the theory to the specific phenomena of KCI- NaCl separations. Temperature-collector solubility relationships, metal ion activation, and particle size effects are discussed.

Jan 1, 1967

By Thomas E. Ban

The continuous sintering process was invented more than 60 years ago by two metallurgists, Arthur S. Dwight and Richard L. Lloyd, who saw a need for automation in mineral processing. Their specific objective was to beneficiate copper ore by desulfurizing and agglomerating it for copper blast furnace smelting at the Cananea plant in Mexico1. Since their early development the process expanded widely in scope, size, and application. The current worldwide sintering applications exceed 250 million tons per year for agglomerating ores of lead, manganese, zinc, and iron. Sintering is also widely used for production of sintered lightweight aggregate from clays, shales, and fly ash. The continuous sintering process took on wide expansion during the 1960's in foreign countries. Plants for production of approximately 135 million tons per year were built in these countries for sintering iron ore fines as shipped from new iron ore projects of Canada, Liberia, India, Brazil, and Australia. This expansion represented construction of approximately 80 new sintering plants, some as large as 15 thousand tons per day production on a single large sintering machine. Sized self-fluxing or highly fluxed sinter has become recognized as a premium blast furnace charge and has enabled blast furnaces of Japan and Europe to produce upwards of 10,000 tons of metal per day with coke rates less than 1,000 pounds per ton of metal. This coke requirement is practically 50 percent of the ordinary rates achieved during the early 1950's when the peak blast furnace production was less than 113 of the current records.

Jan 1, 1975

By A. S. Atkins

The interest in the use of micro- organisms in the leaching of sulphide minerals has been traditionally exploited as a scavenger process for the recovery of valuable metal by- products from waste ore dumps. Environmental concern on sulphur emission from conventional pyrometallurgical plants together with the cost of stack cleaning systems to comply with legislative control also indicate baccerial leaching to offer a low cost treatment for the processing of sulphide minerals. The paper describes the effect and limits of relatively coarse particles on the complete leaching of pyrite and its importance to the practical application in dump leaching operations of sulphide minerals. It has also been demonstrated that static leaching techniques have encouraging economic potential for process plant operations compared with agitated leaching systems.

Jan 1, 1984

By R. W. Salmi

The authors discuss the cooperative efforts by Minnesota Ore. Operations and Research; from the earlier development, testing and installation of fine shear screens in the Minntac Step III concentrator to the most recent testing and operating data that has resulted in the installation of Derrick Multifeed sandwich deck screens in Minntac Steps I and II. Pilot-plant test results that were obtained at the Coleraine, Minnesota Research Laboratory are also reported and demonstrate the effects of feed rate and feed percent solids on sandwich screen performance with two sizes of Minntac fine screen feed.

Jan 1, 1984

By K. C. Li

The scope of this subject is a broad one. The demand for a metal with high refractory properties, great strength at elevated temperatures and high nuclear cross section, has put tungsten in the foreground as: the most promising metal to fill some of these requirements. Recently developed techniques have made it possible to roll large tungsten sheet and-the availability of fabricated tungsten is already upon us. More and more, the demand is for purer and still purer metals. Tungsten is no exception. As technology improves, we are learning more about the effect of foreign elements in minor amounts upon the chemical and physical properties of metals. As equipment and technology improve, specifications become more rigid, and reasonably so. Pure metals have revealed properties hitherto unknown in metals produced by former technology.

Jan 1, 1961

By Alper Kirmaci, Taghi Sherizadeh, Dogukan Guner, Cameron Mitchel

Brow hazards are a significant concern in coal mine ribs and form when weak coal sloughs out of a rib face and exposes an overhanging block of more competent rock or coal. Of 36 rib failure fatalities in the last two decades, 36% resulted from rib brow failures. This highlights the need to better understand the mechanisms driving brow formations and failures to mitigate this hazard and eliminate potential fatalities. The research team at Missouri S&T worked to enhance the current CPRR system and include the potential for these brow hazards. We employed physical modeling methods to build a scaled model from critical brow cases observed in the field. The dimensions and properties of the models were scaled down by 14.4 times from the field cases. The results of the physical modeling efforts were used to assist in calibrating distinct element numerical models vital to understanding brow formation and failure mechanisms. Subsequently, three physical models were created and tested to provide data on an otherwise impossible-to-capture event at the field scale. The results of these tests provided formed brow dimensions that agree well with those observed at the field scale. The brow dimensions were 1.25 inches deep into the rib, equivalent to 1.5 feet when scaled up. Similarly, the numerical modeling efforts provided good agreement by capturing a brow forming 1.55 inches deep into the rib. The physical model results further validate the applicability of physical modeling efforts for capturing otherwise difficult and dangerous phenomena in a controlled lab setting.

Feb 22, 2026

By R. P. King

Knowledge of the behaviour of flotation machines had developed and increased considerably over the last few years. Although much work remains to be done on the study of the fundamental processes that influence the collection of hydrophobic particles at an air-water interface, there is enough information to permit the building of realistic models of the gross flotation behaviour of various ores. These models serve as an ideal base for the development of simulation techniques for the steady-state behaviour of entire flotation plants that consist of a large number of individual flotation machines. Simulation techniques have a very real role to play in assisting with the design of new plants and in improving the operation of exisiting plants. Recently, highly efficient data-logging systems have been introduced on flotation plants. These systems are based on the on-line measurement of volumetric flowrate, pulp densities, and metal contents, and they generate enormous quantities of information regarding the operation of the plant. Unfortunately, this information is largely wasted at the present time because efficient data-reduction techniques, although available10 are not in common use. Simulation techniques play a central role in such data reduction because they form the essential link between the fundamental kinetic flotation processes on the one hand and the plant data on the other.

Jan 1, 1974

By F. Dakubo

"Solvent extraction of copper pregnant solution (PLS) obtained from ammonium peroxodisulfate assisted leach was modeled using response surface methodology. Mixing speed, pH, reagent concentration and organic to aqueous (O/A) ratio were selected for testing. A pitched blade mixer was used in the experiment. Mixer speed contributed significantly to copper extraction significant, while pH had minimal effect on copper extraction. The response model developed has an R2 = 0.97 and Adeq precision of 28.3. A parallel kinetic comparing study using a straight blade Rushton turbine in a turbulent regime of mixing showed no difference (p-value =0.308) between peroxodisulfate assisted leach PLS and conventional ferric/sulfuric acid leach PLS- the power draw data support this conclusion. INTRODUCTION High arsenic chalcopyrite concentrates are a problem to the smelters all over the world due to high arsenic gas emissions during smelting. Therefore leaching is often the alternative for extracting the copper in these concentrates if dilution with low arsenic concentrate is not possible. High-pressure autoclave leaching is used. Alternatively, the use of stronger oxidants such as peroxodisulfate has been proposed [16, 18]. There is a concern brought up by the hydrometallurgy community about the faith of the organic extracting reagent coming into contact with stronger oxidant residue in the pregnant leach solution (PLS) and hence the efficiency of such extraction process. This work, therefore, looks to answer such concerns. PLS generated from leaching of chalcopyrite concentrate with the peroxodisulfate ion was used in this solvent extraction experiment. As a liquid-liquid extraction, solvent extraction involves contacting the aqueous PLS with organic extractant via mixing. Mixing is known to increase the interfacial area for mass transfer by decreasing the diffusion path length (Jussi et al.1997). EXPERIMENT Instruments and Reagents Reagent grade Acorga 5910 reagent was used in the experiment was supplied by Cytec (Current name Solvay), Ammonium peroxodisulfate and sulfuric acid were reagent grade obtained from Amazon. Apparatus The solvent extraction tests were carried in a 2000 ml plastic cylindrical reactor equipped with four 0.5” baffles. In the hypothesis test, the reactor was a 4000 ml cylindrical reactor with four 1” thick baffles arranged evening in the reactor. Comparison between peroxodisulfate and ferric leach PLS via hypothesis test"

Jan 1, 2018