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By Dave Bulled, Chris Bennett, Glenn Kosick, Glenn Dobby

"Mining companies around the world are embracing geometallurgical modeling at a rapid rate, as senior executives realize that inputs must be properly measured if the output is to be managed effectively. Geometallurgical modeling is used to scientifically manage risk in project evaluation, for plant design and production forecasting, and optimization of production planning and mineral processing/metallurgical unit operations. The technology also provides a solid foundation for implementing broad corporate strategies with respect to intelligent asset utilization and metal sales. Over the past five years, MinnovEX Technologies Inc. has been actively engaged in developing, promoting and applying geometallurgical modeling technology for major mining companies around the world. This paper describes the methodology for successfully applying the technology for the unit operations of comminution and flotation in the mining industry.INTRODUCTIONGeometallurgical modeling (referred hereon as geomet modeling), in theory, can be applied to its full potential on all unit operations in mineral processing; however, this paper will concentrate on two of the largest unit operations, namely comminution and flotation, where the technology is actually being practiced by many large mining companies. For concept studies and prefeasibility studies, aspects of geometallurgical technology are regularly applied but in a less rigorous manner than for final feasibility studies where justification for funds is sought. This paper will focus on the final feasibility stage of a project and on existing operations or planned expansions, where the full power of geometallurgical technology is brought to bear in a cost effective manner.One of the unique aspects of geomet modeling, when used to its potential, is the ability to design plants, and forecast and plan production with a quantifiable degree of precision, something that was unattainable in the past. This means that when new comminution and flotation plants are designed, the mining companies and financial institutions involved in the project can measure the precision of the design and therefore better understand and manage project risk. It means that for existing and new operations, metal sales personnel can carry out their sales strategies with a much better understanding of the degree of error associated with production forecasts of concentrate/metal and quality of concentrates. For mine and mill managers, geomet modeling allows the effect of the mine plan on the downstream processes to be quantified; thereby allowing the mine plan to be recast in a more optimized manner. Finally, existing concentrator personnel can optimize their unit operations based on a more definitive understanding"

Jan 1, 2004

By Robert A. Irvine

Traditionally, cost effective gains in the capacity of material handling systems were a result of increases in equipment size. In general, the use of maximum capacity components in a system optimizes the production "costs per ton." The trend-"Bigger is Better" will continue in material handling equipment. Since it is rare for plant operators to lament an over abundance of screening capacity, one can safely predict that vibrating screens will follow this trend. Large Vibrating Screens - The Challenge Large vibrating screens represent a unique challenge for Manufacturers, Plant Designers, and Plant Operators. The inherent mode of operation for vibrating screens is self-destructive. More often than Manufacturers admit, Designers plan for, or Operators staff for, a vibrating screen succeeds and self-destructs. This is a problem. It can magnify with larger vibrating screens.

Jan 1, 1983

An Environmental Impact Statement (EIS) for a major mining development typically has to address various aspects of surface water management, including some which generally tend to be the more contentious: the diversion of rivers and creeks from areas disturbed by mining, and their rehabilitation; the effective management of disturbed area run-off via the collection, containment and treatment of contaminated water on site in sedimentation dams; the collection, containment and treatment of mine pit water; the decommissioning of surface water storages; final void water quality; and water discharge criteria. Environmental Impact Assessment processes for proposed mining developments in Australia at the state and commonwealth level usually involve a form of Initial Advice Statement (or Notice of Intent), Terms of Reference, an EIS, and a Supplementary Report (or similar) which responds to agency and public comment on the EIS. The EIS is used by approval agencies to decide the acceptability of the Project, and to set the conditions of approval. The conditions are often in the form of a state-issued æOperational LicenceÆ or similar. With mining, the initial approval at the EIS stage is often just a pre-cursor to various other planning related approvals, including obtaining a mining lease. Afterwards, mine plans and plans of operations must be submitted to government at various stages of the mineÆs life, ostensibly to provide the detailed mine planning over periods of one û five years. Despite all this additional planning and documentation beyond the submission of the EIS, government approval agencies are increasingly not satisfied with conceptual water management designs and commitments to an outcome (such as meeting a specified water quality standard) in the EIS. Agencies are also requiring sufficient water management design information to be convinced that the outcomes are achievable. To assist proponents of major mining developments, the Queensland Government has published Technical Guidelines for water management, and Environment Australia has published a æBest Practice Environmental Management in MiningÆ booklet on water management. In addition, the Australian and New Zealand Environment and Conservation Council (ANZECC. 2000) has published Water Quality Guidelines which provide an approach to water management, and provide receiving water investigation trigger criteria. So, what are the water management issues that are likely to be the subject of comment, debate and negotiation prior to the EIS being approved? and what commitments may a mining proponent have to make in order to convince the approval agencies that sufficient investigation and design has been provided? This paper provides some answers to this question, by reference to recent major mining proposals which the author has managed through state and commonwealth Environmental Impact Assessment processes.

Jan 1, 2003

By P. M. Solozhenkin

On the territory Sakha (Yakutia) are located largest in Russian Federation reserves of antimony ores, Sarylakhsk and Sentochansk deposits, amaunt 10% of world stocks of antimony. A processing gold antimony ores Sarylakhsk deposit is carried out on gravitation-flotation circuit to receive gold gravitation concentrate and gold-antimony flotation concentrate with the contents of antimony over 60%. The gold-bearing concentrate is treated on place hydrometallurgicaly to a high-standard product, accepted by gold bank cash department. At the ore dressing plant reached the highest recovery in world in a concentrate of antimony 90%~91.6%, and gold 85.7%~86.0% as a result of scientific research works. Studied the mechanism of interaction cations of metals Pb2+, Cu2+, Cd2+, Hg2+, Ag+ with a surface antimonite presented on the basis of modern physical-chemical methods: nuclear quadrupol resonance, x-ray electron spectroscopy, electron spin resonance. The industrial tests of sodium dimethyldithiocarbate were carried out which confirmed high recovery of Sb and As. The leaching Sb2S3 by bacteria Desulfovibro desulfuricans and transformation antimonite in antimony trioxide by Tiobacillus Ferrooxidans improved following cyanidation . The extraction of antimony in a solution 96.0%~98.0% under optimal conditions. The common total extraction in the appropriate commodity products for gold reached 98%, for Sb 96.5%. At a combination of bioprocessing and cyanidation 85.5% of extraction Au was achieved. The new solvents for antimonite were found. Now by the Close Joint-Stock Co ?Sarylach-Antimony? industrial plant is constructed for processing Au-Sb concentrates to receive antimony trioxide and gold from various antimony deposits of Sakha (Yakutia).

Jan 1, 2014

By Bowra N

Working capital is best described as money that must be supplied from a company's treasury to buy inventories for raw materials and finished products and to provide credit to customers who have not yet paid for delivered products. Working Capital requirements for resource projects are to a large extent, dependent on specific characteristics of the projects concerned. Important variables are the nature of the project and speed with which sales can be realised. The project's location is also important as this will influence inventory levels. Working capital requirements have a time profile, the present value of which can represent a significant portion of a projects overall capital needs. A significant component of a project's working capital is not readily recoverable or able to be reassigned should the project fail or be deferred.

Jan 1, 1986

By Robert A. Rapp, Jan E. Verfurth

From the measurement of internal-oxidation band widths in Ag-In and Cu-A1 alloys, products for the solubility No and the diffusivity Do of oxygen in silver and apparent NODo products in copper have been obtained over a range of temperature. The NODO products for silver are in agreement with the product of the individually determined No and Do values of Eichenauer and Müller. Although interstitial diffusion of oxygen in silver is expected, the temperature-independent factor Do of the diffusion coefficient does not agree well with the theory of Wert and Zener. For Cu-A1 alloys internal oxidation does not follow the expression derived for ideal kinetics, since the apparent NODo product calculated from internal-oxidation measurements is a function of the alloy content in the specimen. Thus, unequivocal values for No or DO or even the product NODO in copper are not available from the literature. RELIABLE values for the saturation solubility NO and diffusivity DO of oxygen in fcc metals are lacking and difficult to determine, partially because internal-friction measurements are not applicable. Permeability experiments and Sieverts7-type adsorption -desorption methods3 have met with difficulty; however, Eichenauer and Müller4 have recently reported on the solubility and diffusivity of oxygen in silver as determined by the latter technique . Rhines, Johnson, and Anderson,5 and independently Meijering and Druyvesteyn,' introduced the possibility of deriving values for the product NODO in a metal from measurements of the widths of internal-oxidation zones (subscales) formed during the internal oxidation of alloys. In addition to these authors, several other investigators7-9 have made such measurements in various silver and copper alloys at various temperatures, mostly using me- chanically polished specimen surfaces. The purpose of this investigation was to determine over a range of temperature the calculated products NODO in silver and copper from systematic measurements of the widths of internally oxidized zones in Ag-In and Cu-A1 alloys, using specimens with electro-etched surfaces. Consider the internal oxidation of a dilute solid-solution alloy in which the base metal is not oxidized. If diffusion of oxygen is the rate-controlling step, then the depth 5 of the internal-oxidation zone is given by where y is a dimensionless parameter and t the oxidation time. Based on the solution of the diffusion equation, wagnerl0 has shown that under certain conditions several mathematical simplifications may be used in the evaluation of y, so that Eq. [I] may be expressed for the case that y « 1, and y(Do/DB) 1, where N(so)the is the equilibrium solubility (mole fraction) of oxygen in the solvent metal for the given oxidizing atmosphere, is the mole fraction of the solute metal in the bulk alloy, 4 is the diffusivity of the solute in the base metal, and v is the ratio of oxygen atoms to solute atoms in the precipitated oxide BO,. Rearranging Eq. [2] Maak' has derived an expression analogous to Eq. [3] for the case that an external-oxide scale, in addition to an internal-oxidation zone, is formed. For this combined external and internal oxidation for the case that 5/2 where 5 is the distance of the internal-oxidation front from the original external s.urface, and X is the distance of the external oxide/metal interface from the original external interface. The function F is defined by the expression

Jan 1, 1964

By N. C. Nissen, J. A. Thomas, A. Illis, K. N. Subramanian

Successful miniplant and laboratory testwork has indicated that high purity selenium can be produced from copper refinery slimes. The recovery technique fits into existing unit operations, and the selenium recovery in the new process was close to 99%. This recovery virtually eliminated any selenium being processed through the smelting stage. In addition, miniplant tests conducted at Inco Metals Co.'s J. Roy Gordon Research Laboratory in Mississauga, Ontario, have demonstrated the reliability of the process with respect to extractions, product quality, filtration characteristics, and effluent disposal. Inco's copper refinery at Copper Cliff, Ontario, produces about 500 t/d of copper with the anode slimes fall typically averaging 0.5% of the throughput. Investigations relating to the treatment of slimes within Inco's R&D have been conducted on several occasions since 1959, when the available alternatives such as acid or alkaline pressure leaching, aqueous or high temperature chlorination, roasting, smelting, etc., were considered. Interest in slimes processing was revived recently to meet increasingly stringent environmental standards and to replace equipment of a relatively old plant.

Jan 11, 1978

By M. J. Ackerman, C. R. Waine, W. M. Merritts, L. P. Mokwa

Tests were conducted in the Pocahontas No. 4 coalbed in southern West Virginia to determine if successful degasification techniques, developed during an earlier study in the Pittsburgh coalbed, would be effective in removing methane from those usually more gaseous coals. Specially designed long-hole drilling equipment and Bureau of Mines continuous recording devices were used to measure the quantity and methane content of the ventilating air during the investigation. Infusions were made with water at normal waterline pressures ranging from 200 to 220 psi or at pump pressures ranging from 400 to 650 psi. Results of the tests showed that methane emissions from free-flow bleeder holes were as much as 131 cfm. Infusions of some of the holes increased the methane emission from other holes and from the exposed coal surfaces near the working areas as much as 1,540 cfm. The methane content in the main return-air currents after infusion was reduced more than 86 percent of the amount recorded before tests were made.

Jan 1, 1963

By William H. Lehr

In recent years, we have witnessed many innovations in the equipment used in handling bulk materials. Not too long ago, any sizeable stockpile of coal or iron ore was attended by one or more material handling bridges. More recently, large stockpiles have been built with mobile equipment of' the earth moving type with bulldozers and front end Loaders being utilized in reclaiming operations. The most recent stocking and reclaiming device is the rotary bucket wheel machine. The early bucket wheel machines built in the United States were developed for the strip mining of coal. We understand that the first American machine was built in the Midwest in 1944. This type of unit was developed in an effort to reduce the cost of removing overburden and to provide satisfactory spoil disposal. As the available coal reserves under shallow cover were exhausted, the cost of removing the deeper overburden with conventional equipment became too great for these operations to continue profitably. The first machine has now been followed by six or seven additional units, the largest of which can handle material at a rate of more than 7000 cubic yards per hour.

Jan 1, 1965

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 A. L. Hinde

The steady-state and dynamic behaviour of semi-autogenous grinding (SAG) mills are arguably best described using a population model that caters for the breakage kinetics and the material trans-port of rock and pulp inside the mill. Breakage kinetics are usually expressed in terms of a specific breakage rate function and a separate primary breakage distribution function. Material transport usually invokes the concept of a specific discharge rate function. Unfortunately, the breakage rate and breakage distribution functions for SAG mills are very difficult to estimate uniquely from plant data alone. Simplifying assumptions must be made to over-come this problem, which leads to many unresolved dilemmas with regard to whether or not the de-rived functions are accurate, precise, and reflect reality. For example, it is sometimes assumed that the breakage distribution function for a SAG mill treating run-of-mine ore can be derived from laboratory dropweight and tumbling tests on small rocks in narrow size ranges. Such tests hardly reflect the environmental conditions likely to be encountered in a pilot or production SAG mill where there is a wide spectrum of particle sizes. It is shown that the dilemmas associated with standard population balance models (models that utilise separate breakage rate and breakage distribution functions) can be overcome by expressing breakage behaviour inside a SAG mill in terms of a single function. This function is an energy-based cumulative breakage rate function defined as the fractional rate at which particles and rocks coarser than a given size break to below that size per unit specific energy input. A model for SAG milling is formulated, which invokes the concept of a cumulative breakage rate function. Comparisons are made between the mathematical structure of this ?simple model? and standard population balance models. Perhaps the most attractive feature of the ?simple model? is that the cumulative breakage rate function can be uniquely estimated from measurements of size distributions and mass flows of the feed and discharge streams together with the size distribution and holdup mass of the mill charge. Such measurement can easily be made at pilot scale. It is concluded that this simplified approach to SAG milling may turn out to be the quickest way to fully describe and quantify the performance of these very complex mills.

Jan 1, 2014

By E C. F Hamman

Sunrise Dam Gold Mine is a large open pit mine 730 km NE of Perth, Western Australia. Contract mining commenced in the open pit in September 1996 in lake clays and saprolites with the first fresh rock mined late 1999, and the underground starting the first decline in October 2003. By May 2007, over 150 million cubic metres of material had been mined and the pit was 360 m deep with 80 m remaining before reaching the planned final depth in early 2008. A final cut-back in the northwest will commence in late 2007 with open pit mining in the Mega Pit expected to conclude in late 2010. The challenges of developing the pit can be divided into three phases:Soft materials û mining was in multiple staged pits and cut-backs in lake clays, saprolites, weathered material. The varying characteristics had a significant impact on mining methods and slope stability. Structural û mining was gradually exposing more fresh rock and the drive was to understand how major structures and lithological contacts impact on local and large-scale stability. This had a significant influence on mine design and scheduling. Slope angles û achieving the final slope angle is critical. This is done through application of high standards of final wall establishment and proactive geotechnical hazard identification and management. This includes dealing with the rapid rate of descent, interaction with underground excavations and managing rock fall risk. The paper discusses each of these phases, highlighting the geotechnical controls implemented to date, looking at their success and impact on mining.

Jan 1, 2007

By Luiz Bruno de Oliveira Araujo, Luciano Morais Teixeira, Luiz Gustavo Pedrosa de Melo, Altair Lúcio de Souza

The off-line simulation of the metallurgical process in an industrial line brings several benefits such as: evaluation of the influence of the main parameters that affect the results of the process, comparison between different set ups, greater assertiveness in operational adjustments, process optimization and reduction tests for development of new products. With this objective, a software for offline simulation of the hot strip mill process of Gerdau Ouro Branco was developed based on the logic of calculations implemented in the online model. The software results in important process variables such as mill pass scale, load, torque, and power at each pass, temperature and the hot mean flow stress of the simulated material. During rolling mill process the strip presents different temperatures and time between passes for different points along the length, which directly influences the hot strength of the product and consequently in the calculated variables, thus the calculations executed by the software were divided to three points of the strip, head, body and tail bringing the individual results to each of these positions.

Oct 1, 2019

By K. A. Eriksson

Over 25 years ago, SKEGA pioneered the use of rubber linings in grinding mills and rubber is today widely accepted and almost standard material chosen for Regrind -and Secondary Mills. There are, however, only a few Primary Mills in operation with "solid" rubber linings because available materials and designs are often not cost efficient in comparison with steel alloys on a cost per ton basis and/or downtime for liner replacement would be too high.

Jan 1, 1988

By F. Kitzinger

The possibility of increasing the efficiency of mineral processing plants by means of computer control has prompted metallurgists to examine their flowsheets more critically in order to develop practical control strategies. Control schemes in use to date generally rely on the automation of traditional and previously manually regulated control loops, for instance the addition of reagents to maintain a constant assay or a constant pH. This approach is predicated on the availability of well-established primary sensors such as pH electrodes or on-stream analyzers. Noranda Research Centre, in cooperation with Noranda Group concentrators, has developed a froth level monitor and a pulp density meter susceptible of application in this type of control. Although some of the basic principles on which they are based have been known for some time, their incorporation into the design of reliable, direct-reading instruments which can be interfaced with a computer, is be-lieved to be novel*.

Jan 1, 1977

By Qiang Guo, Zongliang Zuo, Mengqi Wei, Qingbo Yu, Qin Qin

Activated carbons, derived from waste ion-exchange resin by CO2 physical activation, were applied to separate CO2 from flue gas against global warming. The BET specific surface areas of activated carbons at different activation temperatures and times were investigated. The CO2 adsorption capacity was tested under non-isothermal and isothermal conditions. The experimental results show that when keeping the activation temperature constant, the specific surface area increases firstly and then decreases with increasing activation time. For the given activation time, the specific surface area rises firstly and then declines with increasing activation temperature. The adsorption capacity decreases with increasing temperature. The maximum adsorption capacity is 51.46 mg/g under the condition of 298 K and pure CO2. Fractional order kinetic model is the best one to describe the kinetics of CO2 adsorption. The activated carbons show the potential to be an effective adsorbent for the removal of CO2 from flue gas.

Mar 1, 2018

By Anna Wasilkowska

The study concentrates on the effects exerted by microstructure, deformation history and uniaxial stress conditions (temperature, stress state, strain rate) on the mechanical properties offerritic TRIP-aided steels for automotive applications. In low-alloyed TRIP-steels it is quite difficult to separate the effect of the austenite to martensite phase transformation from the influence of the ferritic matrix contributing to the yield stress and uniform elongation. Investigation of transformation kinetics of retained austenite as a function of the deformation temperature show that using the parameter k to characterize the retained austenite stability allows to identify regious of different temperature sensitivity separated by a transition temperature of 10±5°C. The observed low strain-rate sensitivity of the flow stress is an intrinsic property of the ferritix matrix and points to defomtation governed by slip. The ultimate tensile strength is much stronger affected by temperature than the yield stress. The influence of the temperature on the elongation is complex, because of the heating of the specimens by 60-l20°C at moderate and high strain rates. The increase of the total strain can be understood in terms of thermal softening of the ferrite. On the other hand, the steep increase of the stress during dynamic testing is an effect of accommodated elastic and plastic strains in the matrix. The strain- hardening exponent is dependent on the conditions imposed during testing. The martensite transfomtation rate is lower and the critical stress for martensite nucleation is much higher under compression compared to tensile loading. In secondary tensile tests, the yield stress increases steeply, and the ultimate tensile strength and the total elongation depend linearly on the amount of pre-straining. The results confirm that in the range of 8=10-4 s-l the TRIP-effect governs room temperature plasticity. Keywords: TRIP-steels, mechanical properties, strain rate sensitivity, temperature sensitivity, austenite stability

Jan 1, 2003

By C. K. Kocsis

A study was undertaken to evaluate the thermal environment and determine the contributing heat sources within the existing 153 Orebody of Coleman/McCreedy East Mine which would then enable the prediction of the climatic conditions in the mine?s future 170 Orebody. The study entailed continuously monitoring, for a 2-week period, the dry-bulb temperature, humidity and barometric pressure along the existing intake airways from surface down to the 4810 Level and throughout an active mining area on that level. Furthermore, the mining activities and associated equipment that could be responsible for any changes in the temperature and humidity conditions within this mining area were also monitored. These data were then used to develop and validate a climatic simulation of the mine?s mechanized cut and fill mining method. This climatic model was then transposed to the future 5700 Level in the deeper 170 Orebody, to determine the environmental conditions within its production workings and along the main haulage route ascending from that area. Based upon the simulations performed it was shown that the level of ventilation planned for the new orebody should be able to maintain adequate environmental conditions. However, this study did emphasize the importance of the appropriate distribution of airflow in workplaces that used auxiliary ventilation in order to sustain a suitable thermal environment.

Jan 1, 2009

By Oliver Bowles

The United States Bureau of Mines has within its ranks a group of engi- neers who are engaged in working out quarry problems, the solution of which will be of general benefit to the industries involved. The problems undertaken are approached in a systematic and thorough manner, all the evidence for and against any proposed change or new development being collected as carefully as an attor- ney would prepare his data on an important case. Unlike the attorney, however, the Bureau engineer does not take sides; his judgment is based entirely and in- partially on the array of facts presented. In order to gain the desired infor- mation he visits many plants, consults with the leaders in the industry, works out experiments in his laboratory, and supplements this information with a stu- dy of all available literature already published on the subject in any part of the world. As an engineer who has for eight years conducted such inquiries in the stone industry, I propose to discuss the Bureau of Mines viewpoint; and it may be of interest to consider with me in a brief and general way the engineer's method of looking at quarry problems, and some of the results attained through past and present labors. While the Bureau has conducted no investigation directly for the crushed- st one industries, two years of investigative work at cement-plant quarries, and work now being conducted at lire-plant quarries, has a very direct bearing on the problems of the crushed-stone industry, since stripping, drilling, blasting, loading, and transportation are similar in many respects in all stone quarries. The results of cement-plant quarry investigations are to be found in Bureau of Mines Bulletin #160. (b) Two short papers on lime-plant quarry problems have been issued in mimeographed form as Serial #01 (c) and Serial 3 (d).

Jan 1, 1923

It is well known that the electrochemical precipitation of metals from aqueous solutions is conducted by the electrochemical standard potential scale. This scale indicates the order of nobility of different metals. Consequently, the standard potential scale shows the nocivity of metals when they are present as impurities in aqueous solutions containing metals. In the hydrometallurgy of cobalt, nickel and zinc are co-deposited during cobalt electrodeposition. Nickel has almost the same chemical, physical and electro-chemical properties as cobalt. Furthermore, the electrochemical potential of nickel is relatively higher than that of cobalt. For this reason nickel is preferentially reduced at the cathode in the presence of cobalt. The presence of small amounts of zinc in solution leads to contamination of cobalt electrowon. In spite of its lower electrochemical potential in comparison to cobalt, zinc is reduced on the cathode because of its higher hydrogen-overvoltage. But, in the hydrometallurgy of zinc, small amounts of cobalt present solution will contaminate the zinc reduced at the cathode. This is easily explained by the fact that cobalt is more electropositive than zinc. The co-deposition mechanism of sulphur at the cathode is not yet well understood. Great attention has to be paid to the mechanism of co-deposition of sulphur during cobalt electrolysis. This work aimed to investigate the influence of some parameters on the co-deposition of nickel, zinc and sulphur during cobalt electrowinning. The following parameters have been investigated: Co2+concentration in the electrolyte, current density and ammonium sulphate (NH4)2SO4additions. It has been established that important nickel, zinc and sulphur co-deposition takes place at relatively low Co2+ concentration in solution. The behaviour of these elements with regard to the cathodic phenomena has been established.

Jan 1, 2005