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By Michael S. Moats, Daniel Kim, Shijie Wang

"The behavior and deportment of lead, arsenic, antimony and bismuth are critical in producing high quality cathode by copper electrorefining. A critical review of research related to these elements is presented along with a comparison to industrial data, where appropriate. These elements exist predominantly in the anode as complex oxides along die grain boundaries. Upon dissolution, Group 15 elements report both to the electrolyte and slimes while lead essentially enters the slimes. The deportment of the Group 15 elements appears to be influenced by several chemical interactions which are discussed. The effect of these elements on floating slimes and anode passivation is reviewed. Under normal electrorefining conditions, lead, antimony and bismuth are thought to enter the cathode through the encapsulation of slime particles. The literature indicates that arsenic enters the cathode predominately by electrolyte entrainment. Finally, areas for future research regarding these elements are presented.IntroductionControlling lead, arsenic, antimony and bismuth is critically important for the production of high quality cathode in copper electrorefining. The reasons for this are twofold. First, ASTM Grade 1 Cathode specifications [1] for these elements are low, as listed in Table 1. Second, they can affect the efficiency of the electrorefining process (e.g., through passivation, current efficiency, slime processing)."

Jan 1, 2012

By N Nosaka

Sinter plants currently have to use many types of ores with different properties due to the great demand for iron ores, which was driven by the massive growth in Chinese iron and steel industry. On the other hand, the development of iron ore mines is limited and the quality of iron ores is in a tendency of deterioration. Therefore, the quick evaluation of iron ores has become more important for a stable sintering operation. In addition to such a background, the CO2 gas emission should be decreased from sinter plants according to the Kyoto Protocol on reduction in greenhouse gases. The present paper first describes the methods for testing the metallurgical properties of iron ores, which use a small volume of sample mainly focusing on magnetite ore that is effective for reducing CO2 and NOx emissions from sinter plants. The sintering properties of ores are evaluated separately according to each stage in sintering process, that is: heating stage before melt formation, primary melt formation in adhering fines layer of pseudo-particles, and assimilation of nucleus ore particle with calcium-ferrite system melts.Next, the application of the tests to the blending ores is introduced showing examples of the studies on the effective usage of the magnetite ores with Marra Mamba type ores.

Jan 1, 2005

By C. H. Lee, F. Concha, L. G. Austin, P. T. Luckie

The Concha-Almendra batch-settling treatment for concentrated suspensions of single-diameter spheres has been modified. This modified version is used in the differential equations of simple batch settling of a particle size range of different density materials. The equations have been programmed for a finite difference solution, and a number of test cases have been analyzed. By cutting the settling column at a fixed fractional height, the material below this height can be treated as underflow and the material above as overflow. The predicted partition curves obtained from treating the settling in this way have Sharpness Indices in the range of 0.5 to 0.6, in the absence of dispersion effects. The Sharpness Indices decrease as dispersion increases. When the feed size distributions are of the Rosin-Rammler form, the partition curves (corrected for the bypass fraction) fit the Rosin-Rammler equation with reasonable accuracy. The predicted Sharpness Index of a component of a mixture of two materials of different densities was unchanged from that of the same materials settled alone. However, for the same, feed size distribution and volume fraction of solids in the feed, the heavier material settled faster, and the lighter settled slower, than when settled alone.

Jan 1, 1993

By H. E. Johnston

There are currently a number of options in terms of plant feed comminution tests: Bond work index tests, JK drop weight and SMC tests, SPI, low impact crusher work index tests, to name a few. However, information regarding specific energy requirements for regrind mills is often requested, which can be difficult or very expensive when only a small mass of concentrate is produced from bench-scale flotation tests. This research was aimed at developing a test methodology that would produce a similar result as an IsaMill Signature Plot but require less sample mass allowing for preliminary estimates of regrinding power at a lower cost. Initially, the laboratory test methodology was completed on a single sample in comparison to the IsaMill Signature Plot for that sample. Results indicated a very good correlation between the laboratory tests and the IsaMill Signature Plot for this sample, though some parameters did impact laboratory regrind mill efficiency. The developed methodology is subsequently being applied to a range of concentrates, investigating a range of material particle sizes and material types, in comparison to a full IsaMill Signature Plot on the same sample. This new test procedure has been called ‘The Eliason Test’.

Jan 1, 2014

By Ian William Wark, Keith Leonard Sutherland

Mercaptobenzthiazole and its sodium salt are marketed under the trade names Flotagen and Flotagen S respectively, for use as collectors for cerussite and other minerals. The structural formulas for sodium rnercaptobenzthiazole and for sodium ethyl xanthate are: Chemically there is a resemblance between the two compounds, though the free acid (mercaptobenzthiazole itself) is much more stable than xanthic acid. Both are readily oxidized, e.g., by iodine to disulphides, and can be estimated by iodometric titration. Qualitatively they are similar as collectors in flotation, although there are quantitative differences between them that may be important in practice. It is deduced that the influence of the nitrogen atom is subordinated to that of the sulphur atoms, and that the dominant group of these compounds is the mercapto group —SH or —5Na. The general method of investigation has been based on contact tests. Two temperatures, 10" and 35" C., have been chosen, and with a standard concentration of 20 mg. per liter of mercaptobenzthiazole (i.e., of the free acid) the influence of alkali, cyanide and copper sulphate on contact at sulphide mineral surfaces has been studied. This standard concentration corresponds to about 19 mg. per liter potassium ethyl xanthate; it brings out the differences between the minerals better than a higher concentra-

Jan 1, 1939

By K. Biswas, S. S. Peng

The stability of pillars in old mined-out districts is greatly dependent on the weathering action caused by moisture penetration into the pillar structure. Field observations in old mining districts indicated that this weathering action becomes critical in terms of the stability of the pillar if the coal seam contains parting or binder (layers of claystone or mudstone). The weathering action caused by moisture penetration over a long period of time degrades both parting and coal. However, it has been observed that the structural deterioration is more severe in parting. Moisture-penetration rates in parting and coal are different. The extent of the weathered zone in various layers of the pillar is primarily time dependent. This paper investigates, both in the laboratory and in the field, the effects of weathering action on coal and parting. In the laboratory, slake durability indices and uniaxial compressive strength tests for dry and saturated specimens are compared for coal. In the field, the in situ strength profiles for coal and parting layers are obtained, and the effect of time (in terms of the pillar age) on the strength profiles is studied An attempt was also made to establish formulae for time-dependent strengths of coal and parting.

Jan 1, 2000

By Z. T. Bieniawsk, C. A. F. F. Santos

The effects of artificial weathering on the mechanical properties of the Loyalhanna sandstone have been investigated. Weathering was simulated in the laboratory by subjecting cylin- drical specimens of rock to alternate cycles of wetting and drying (in distilled water at 2O0C 2 5OC and in an electric oven at 105OC t 1°C, respectively). The total number of cycles was 100 and the geomechanical characteristics of the altered material were determined through uniaxial compressive and indirect tensile ("Brazilian") tests, with the determination of axial and trans- verse strains and monitoring of acoustic emission activity (rate and total event count). Moisture content and weight loss data were collected after each cycle and the mechanical parameters (unconfined strength, indirect tensile strength, young's modulus, Poisson's ratio, permanent set and AE/MS activity) were determined for unweathered specimens and after 10, 20, 50 and 100 cycles of wetting and drying. Hypotheses for the effect of weathering on the geomechanical properties of the Loyalhanna sandstone are proposed as reinforced by petrographic analyses carried out for the different stages of artificial weathering. A methodology for assessing the degree of physical weathering of rocks is proposed based on the number of wetting and drying cycles.

Jan 1, 1986

By J. H. Swisher

Two recent papers in this journal1,2 contain experimental evidence for an anomaly in the concentration gradient for tracer diffusion. In both papers, the authors suggest that this anomaly is due to a Gibbs' absorption effect. Their hypothesis is that surface active tracer elements tend to remain in or near the surface adsorption layer, thereby altering the diffusion flux and concentration gradient. It is not clear how the anomaly can be explained in terms of an adsorption effect. Surface tension forces act parallel rather than perpendicular to a surface and therefore should affect only the rate of spreading of surface active agents tangentially across a surface. Frenkel3 has given a short treatment of surface tension as a driving force for surface diffusion. While the equilibrium concentration of a surface active agent at the surface of a solution is known to be higher than in the bulk, its chemical potential is necessarily the same. It is difficult to see how adsorption can result in an anomaly in the chemical potential gradient, which is the driving force for diffusion. A more detailed explanation by the authors of the adsorption mechanism is in order. A similar anomaly does not seem to arise where

Jan 1, 1970

The objective of this study is to classify ore and waste in a selected mine. The support vector machine, was used for the classification purpose, is applied to a zinc ore body in a skarn deposit located in the central region of the Peruvian Andes. The input parameters used for the model are spatial coordinates and the lithological information of the ore body. The input data was divided into training and testing data sets and the performance of the model was tested using the testing data set. The results show that more than 76% of the data could be properly classified by this method. The ore waste maps of the deposit was then developed using SVM model. From the result it was observed that a comparatively very few number of cells classified as ore. The ore is concentrated in small lodes at the middle of the volume of study, and not uniformly distributed throughout the study area. The lithological map of the deposit was also constructed as it was used as an input parameter for the SVM model. The indicator kriging was used for generation of lithological map of the ore body. Key word: Ore waste classification, Support vector machine, Indicator kriging, Confusion matrix.

Jan 1, 2008

The Industrial Minerals div. has been forging ahead in formulating a program for the February Annual Meeting in Los Angeles. Several papers have been listed and more are being worked into the program. For the cement, lime and gypsum part of the sessions, papers on Gypsum in the Aircraft Industry, Geology of San Marcos Island Gypsum Deposit, and Status of New Dry Rotary Blast Hole Drills, are expected. The Chemical Raw Materials sessions will feature a symposium on potash, with 13 papers as the anticipated number to be presented. Airborne and Ground Magnetometer Work has been suggested. Eight papers have been set for Mining Geology, Four papers, Mining Phosphate Rock, Idaho Phosphorous, and Geology of Carlsbad Potash and Geology of Pearlite will be on the program. Sessions on Dimension stone and slate have been tentatively worked out with papers on Geologic Factors Affecting the Dimension Stone Industry of California, A Quarter Century of Granite Quarrying in Massachusetts, Rock Bursting and Other Geologic Problems in the Granite Quarries of Barre, Vt., Quarry Practices in the Indiana Building Stone Industry, Stratigraphy and Composition of the Salem Limestone, and Dimension Stone in the U. S. in 1952. The Rare Minerals Committee is aiming for six papers with two papers now definitely on the program.

Jan 1, 1952

By S P. Suthers, J M. F Clout, J J. Campbe

An advanced technique for modelling hydrocyclone separation performance has been developed. This technique is based on the combined modelling of hydrocycloning parameters and ævirtualÆ iron ore feed. The virtual feed modelling was performed using a novel (in-house) software package called æRecognitionÆ, which uses data from optical image analysis to classify the particles in certain size fractions according to total iron content and calculates data for every grade class. These data include the average mineral composition and density of every liberation class in every size fraction. This information about every size fraction, representing the ævirtual feedÆ, was input to the mineral processing modelling package USIM PAC. The hydrocycloning process was then modelled for this virtual feed using the Plitt hydrocyclone model. Empirical calibration coefficients for the hydrocyclone model were calculated using an optimisation procedure in Excel. Pilot-scale hydrocyclone beneficiation experiments were performed on an iron ore blend, using different hydrocyclone pressures and per cent solids in the feed pulp. These experiments were modelled and the modelling results were compared with the experimental results. The new modelling approach enables prediction of the recovery of each mineral in the products, calculation of the total iron grade and recovery, and optimisation of iron ore beneficiation using hydrocyclones.

Jan 1, 2005

By N. N. Clark

Pachuca tanks are used widely as reactors for treating gold slimes, and for alumina digestion and uranium leaching. In some designs, slurry mixing in the tank is achieved by introducing air at the base of a draft tube, which is the full height of the tank. A buoyant air-slurry mixture rises in the draft tube and is discharged at the top. The slurry flows back through the bulk of the tank volume. Little information is available to predict the relationship between slurry flow rate in the draft tube, and the volume of air added at the base of the tube. Most current designs are based on the energy balance proposed by Lamont 25 years ago. Recent two-phase flow theory is used to develop a momentum balance for the flow in the draft tube, and a new, accurate design equation is derived. Bubble slip, frictional (wall) losses, entrance losses, and acceleration effects all contribute to the pressure gradient in the draft tube. None of these factors may be neglected under typical operating conditions. The new design equation accounts for all of these factors, and finds good agreement with Lamont's experimental example. Also, the new equation demonstrates that it is uneconomical to operate the draft tube with high airflow rates.

Jan 1, 1985

By J Rostami, D Tadic

While hard rock tunnel boring machines (TBMs) have an established track record in the tunnelling industry, accurate estimation of TBM performance for each specific project remains critical. Machine performance prediction is required to assist planning activities, including costing and schedule preparation, machine specification and effective planning of maintenance and repairs. In addition, monitoring machine performance during the construction period is required to assess and manage excavation progress, and to achieve optimal advance rates based on specific geotechnical conditions exposed during excavation. TBM performance analysis can also contribute to the development of more accurate performance prediction models for future applications. Rock mass characteristics play a dominant role in machine performance. This paper offers a review of the impact of rock mass characteristics on TBM penetration rates for two specific tunnelling projects. A discussion is provided on the results of statistical analysis of available field data, including geological back mapping, rock properties and measured rates of penetration (ROP). The analysis offers a comparison of the achieved and predicted ROPs to provide a better understanding of the influence of rock mass properties on the performance of hard rock TBMs. A new rock mass adjustment factor is introduced to enhance the accuracy of an existing prognosis model for use in jointed rock masses.

Jan 1, 2008

By C. John Dunnicliff, Birger Schmidt

INTRODUCTION To be effective and useful, monitoring of tunnel construction must be carefully planned throughout all steps. A vital and frequently overlooked step is a clear definition of the specific purposes of the instrumentation. Most tunnel construction monitoring has in the past been of benefit to research, the advancement of tunneling practice, wittingly or not. The development of monitoring instrumentation for the benefit of the project from which the data are recovered has very significant potential for risk and cost reduction of soft ground tunneling. A systematic approach to tunnel construction monitoring, from conception to full implementation, includes at least the following nine tasks or steps: Definition of benefits and purposes; design and project specification to draw full benefits; selection of monitoring parameters; selection of instruments and writing of specifications for procurement and installation; procurement and installation; reading and maintenance; data storage and retrieval; interpretation; implementation. Some of these steps are fairly easy and resolved through the use of established theories and technologies. The difficult ones are those that require the bending of minds, those that involve changes in the ways engineers design soft ground tunnels, the way owners pay for tunnels, and the construction is managed, inspected and controlled. Performance monitoring can be of benefit to the owner, design

Jan 1, 1974

By M. E. Wadsworth, P. H. Yu, C. K. Hansen

A study of the rate of dissc5lution of chalcopyrite (CuFeS2) in acidic solutions under oxygen overpressures was carried out by measuring the rate of formation of cupric ions in solution. Effects of temperature, oxygen partial pressure, surface area, and concentration of sulfuric acid were evaluated. A sized batch of chalcopyrite was leached in the temperature range of 125° to 175°C and in the pressure range of 75 to 400 psi of oxygen. In 0.5 N H2SO4 all products of reaction went into solution except for trace amounts of elemental sulfur. The dissolution of chalcopyrite followed linear kinetics and was essentially independent of hydrogen ion concentration for H2S04 concentrations between 0.2 and 0.5 N. The oxygen dependence indicated adsorption approaching limiting values with increasing oxygen pressure. The linear mechanism was explained in terms of steady-state adsorption of oxygen at the chalcopyrite surface followed by a surface reaction. The enthalpy of activation for adsorption of oxygen was found to be approximately 33 kcal per mole. An activation enthalpy of approximately 9 kcal per mole was observed for the surface reaction. Charge transfer reactions are not rate controlling in the process.

Jan 1, 1973

The reported values of the standard reduction potentials of the Au(NH3)2+/Au(0) and Au(S2O3)23-/Au(0) couples are reviewed to emphasise the experimental difficulties associated with the measurement of reliable values for these quantities. The standard reduction potential for Ag(I)/Ag(0) in ammonia and thiosulphate solutions measured at ionic strength 0.1 and 25oCis used to predict the following relevant stability constants () for gold complexes based on the linear free energy correlations: Au(NH3)2+2 = 1013, Au(S2O3)23-2 = 1024 and Au(NH3)43+4 = 1033. The equilibrium constant ( 10-11) for the reaction Au(S2O3)23- + 2NH3 = Au(NH3)2+ + 2S2O32- based on these stability constants is in reasonable agreement with the measured value (10-9) based on potentiometric and spectroscopic data when excess ammonia was added to a solution of Na3Au(S2O3)2. This also indicates that the stability constant of Au(NH3)2+ is 9 to11 orders of magnitude less than that of Au(S2O3)23-. Relevant species distribution and Eh-pH diagrams based on the revised data are presented.

Jan 1, 2003

By R. C. Hopper, A. A. Mathews, T. A. Lang

DESCRIPTION OF PROJECT The Straight Creek Tunnel site is located approximately sixty (60) miles west of Denver, Colorado, on Interstate Route 70 in the vicinity of Loveland Pass, in the Rocky Mountains. The ultimate project will consist of dual two-lane vehicular tunnels with a building at each portal to house mechanical ventilation equipment and other installations. The tunnels run virtually east-west on an ascending 1.64 percent grade for a distance of approximately 8,900 feet, and will pass beneath the Continental Divide at an elevation of about 11,000 feet above sea level. The maximum cover is 1,450 feet and each tunnel is approximately 48 feet wide by 50 feet high as excavated. The work now under construction consists of the North Tunnel, which initially will have two-way traffic. Ultimately it will be the west bound lanes for Interstate 70. The completion of the North Tunnel will be the fulfillment of a long felt need for better communication through the high Rocky Mountains of central Colorado and is a vital link in Interstate Route 70. The early planning for a vehicular tunnel through the Continental Divide began in the late 1930's and between November, 1941 and May, 1943 an exploratory pioneer tunnel

Jan 1, 1997

By A. Scheltema Beduin, M. Kalisch, E. Floch, R. J. Dijkhuis, H. J. Oterdoom

In metallurgical copper production, the traditional aim is to increase recovery of copper to the maximum. SMS Siemag (SMS) has supplied numerous furnaces for this application. New targets are to make sure end of line products are as safe as possible with respect to health and environment, and to maximize raw material utilization. This means a for example a minimization of leachable metals in slag, so it can be safely used as a construction material, and either a targeted concentration or fixation of volatile compounds, such as arsenic. Currently, 2 process routes are generally applied for slag cleaning. The first is grinding followed by flotation, and the second is slag cleaning in an (electrical) furnace. Popularity of both options has fluctuated over the years, and currently the milling-flotation seems to be the more popular option. In this article some of the advantages and disadvantages of both methods are described, and especially how long term environmental policies could have an impact on the decision which process route to choose. Finally, this article will describe some of the developments SMS is working on in pyrometallurgical slag cleaning that could influence the direction for the design of the copper plant of the future.

Jan 1, 2014

By Split Engineering Chile Fernando Fernandez

Mathematical modeling in conjunction with mineral characterization is widely used as a method for design and optimization of comminution circuits, to simulate the processes of crushing, grinding and classification. An important input parameter to the simulation models is the Run-of-Mine Particle Size Distribution (ROM PSD). The run-of-mine size distributions due to blasting have a great influence on the performance of a semi-autogenous grinding (SAG) mill. In this paper, a mine case study was conducted where there are four primary geologic units and the material properties between the four units vary considerably. Also, the mixture of the four unit that will be mined at any given time also vary considerably. This presents a challenge in terms of optimizing the blasting for mill production throughout the mine life. As part of the case study, field rock mass characterization, laboratory rock mechanics tests, and laboratory breakage tests were conducted. The field characterization and rock mechanics tests provide material properties used to simulate the effect of different blast designs on run of mine particle size distributions (ROM PSD). The JKSimBlast software was used for these simulations. The rock breakage tests provide material properties used to simulate crushing and grinding performance. The JKSimMet software was used for these simulations.

Jan 1, 2015

By B. W. Madsen

Bureau of Mines research to recover arsenic from mining industry waste material and process streams is reported. Batch and column approaches were investigated for adsorbing arsenic from acid leach solutions and ion-exchange eluate solutions with hydrated titanium dioxide granules. A method for producing hydrated titanium dioxide granules was devised to provide material suitable for use in a packed adsorption tower. Selective adsorption of arsenic from acidic leach solutions was achieved. The loading capacity of arsenic on the granules was 14 wt-pct when synthetic solutions were used, but lower when actual leach solutions were used. Other elements in the leach solution were Zn, Cd, and In. The granules were used in an attempt to lower the arsenic content in a solution containing 0.95 g/l W and 0.027 g/l As from a process devised by the Bureau of Mines to treat Searles Lake brine. The arsenic content was lowered to less than 0.001 g/l, but unacceptable amounts of tungsten also were adsorbed by the granules. Adsorbed tungsten was partially stripped with pH 11.5 NaOH, and both tungsten and arsenic were completely stripped with 5M NaOH solution. Repeated loading and stripping of the granules had no effect on the loading capacity for arsenic.

Jan 1, 1983