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By D. R. Nagaraj, Napoleon Tercero, Raymond Farinato

"Several studies conducted recently have shown that molybdenite flotation from Cu-Mo ores is adversely impacted in sea water at pH >~ 10.0 irrespective of the pH modifier; under the same conditions Cu sulfide flotation is relatively unaffected. This has been attributed to the presence of Mg2+ ions and their hydrolysis products in the sea water which adsorb and precipitate on molybdenite surfaces as Mg(OH)2. However, why and how Mg(OH)2 impacts only molybdenite flotation in the complex flotation pulps containing a multitude of minerals is not understood. The work presented in this paper probes the interface and interphase regions near the edge and basal planes of natural molybdenite (MoS2) in aqueous solutions and flotation pulps, particularly in the presence of copper ore pulp and added Mg2+. Differences in interaction of metal ions and their hydrolysis products (Mg2+, Mg(OH)+) were measured on the two faces of this anisotropic mineral. How those differences relate to molybdenite floatability and the impact of aqueous solution chemistry are discussed.INTRODUCTIONWater resource management is an important sustainability challenge in mineral processing. In view of the shortage of fresh water in many parts of the world, mineral processing plants are evaluating alternative sources. Seawater flotation has received much attention recently and there have been several important studies reported in the literature, particularly for the processing of Cu-Mo ores (S. Castro, 2012; S. Castro, Rioseco & Laskowski, 2012; S. Castro et al., 2012; Laskowski & Castro, 2012; Ramos, Castro & Laskowski, 2013; S. Castro & Laskowski, 2013; Laskowski, Castro & Ramos, 2013; Nagaraj & Farinato, 2014; S. Castro, Uribe, & Laskowski, 2014; Veki, 2013). The main conclusions from these studies on Cu-Mo ores in seawater at elevated pH were: a) flotation recovery of Cu sulfides is either unaffected or only marginally reduced, b) molybdenite recovery is adversely affected in seawater at pH values necessary for rejecting pyrite (i.e. pH > 10 to 10.8 depending upon particular system), and c) the precipitation of Mg2+ in seawater as Mg(OH)2 is responsible for the adverse effect on Mo flotation. In order to further investigate the individual effects of Mg2+ and Ca2+ on molybdenite depression in Cu-Mo ore flotation, Nagaraj & Farinato (2014) conducted flotation tests wherein individual metal ions were spiked into tap water during grinding of Cu-Mo ores. They showed the strong adverse effect of Mg2+ addition on Mo recovery and, to a lesser extent, on Cu recovery when pH > 9.5. Under similar conditions, Ca2+ had virtually no effect on either Cu or Mo sulfide flotation. Figure 1 below shows the previous results for Cu- Mo ores in tap water and the effect of addition of Ca2+ and Mg2+ ions. Note that in seawater the adverse effect of Mg2+ on Cu recovery was much smaller than that in tap water (Nagaraj & Farinato, 2014; Figure 4a and 4b and Table 4 therein)."

Jan 1, 2016

By Michele L. Kimble

A fast-flow reactor mass spectrometer has been utilized to investigate the reactions of gas-phase gold cluster anions with CO and oxygen. Addition of CO to Aun - produces species of the form Au(CO)m -, where m = 2-5. However, CO does not bind to Au2 - or Au3 -. With oxygen addition in the cluster source, gold oxide species with both molecular and atomized oxygen are produced. The addition of carbon monoxide to these preoxidized gold cluster anions reveals that select species with 1, 2, and 3 gold atoms participate in the oxidation reaction to produce CO2. Bimolecular rate constants for the reactions between these species and CO are also discussed.

Oct 1, 2003

By Jerry Wallace

Two recent-release boulders posed serious threats to public transportation and utilities in Washington State. Both required challenging drilling and blasting solutions.

Jan 1, 1997

By B. Roy

The Somita plant processes low sulphide gold ore in Burkina Faso with a CIL process. After experiencing recurrent low gold recoveries, Somita undertook an investigation on the source of the problem. COREM conducted a mineralogical study on different pit samples. A series of tests was also conducted on a composite sample from the plant which shows a content of 3.4 g/t in gold and 0.48 % in graphite. A reference test in laboratory resulted in a recovery of gold of 75%, similar to plant recoveries for the evaluated ore. In these tests, even if cyanide is not deficient, it was diverted mainly into iron cyanide complex, copper cyanide complexes and by graphite adsorption. Causes of low recovery were also identified and quantified. Solutions to increase gold recovery were suggested such as increasing gold dissolution kinetics by O2 or by lead nitrate addition, change in activated carbon addition point location to the 1st cyanidation tank and finer grinding to increase liberation. Increase in the pH could also contribute to reduce cyanidation consumption. Following these recommendations, Somita changed carbon addition from tank 2 to tank 1 in the CIL circuit. This change led to an increase of more than 5% in gold recovery. A system for the addition of lead nitrate is also under implementation at the plant and benefit will be evaluated in 2013. Finally, pit management for cyanidation will be done based on mineralogy instead of gold content in the future.

Jan 1, 2014

By Zdzislaw Specht

THIS paper discusses elementary laws pertaining to seismic reflection methods and presents a general and simple criterion for determining the direction of dipping of a reflection horizon from observational data of distance and time. The important development of practical geophysics and the successful results obtained in America, Germany, and other countries, caused introduction of geophysical methods of prospecting in Poland. Of all methods, seismic prospecting has proved most successful in the area of the Carpathian foreland, where new oil reserves are to be expected. Because of the great depth of the sedimentary column in that area, rang-ing sometimes over 2000 meters, it was obvious that only the seismic reflection method could give reliable information regarding the structural features of these strata at such a depth. During the experimental surveys it appeared that the complicated geological conditions of that area do not always allow prediction of the depth and the angle of dipping of reflecting horizons, and for that reason information about the inclination of a given horizon has great importance in the determination of subsurface structure. Therefore the problem arises of obtaining from seismic reflection data reliable information as to the direction of dipping of reflecting strata, without any previous knowledge of the average velocity and depth of geologic horizons under consideration.

Jan 1, 1940

By Jaracz K

At the operation of mine winders in deep shafts considerable oscillations of winding ropes may occur due to elasticity of both wind-ing and balance ropes. The amplitudes of longitudinal oscillations may reach + lm at relatively low frequencies, ranging from 0.5 to 2 c/s. These oscillations may be dangereus for the rope and produce several hazards to the winding installation as a whole. They may cause conside-rable instant accelerations on the pulley and dangerous tensions in ro-pe wires. The excessive acceleration may cause the uncontrolled rope slip on the pulley. Several methods of limitation of these accelera-tions were developed, some of them have been already in control system: of electric drive of the winder. The most simple ones are: a/ limita-tion of the rate of change of acceleration and retardation of the win-der /so called "jerk"/ and b/ the proper selection of regulators of the winder control system to get the optimal control. The trouble in solv-ing the problem of rope oscillations is that the dynamic system of the winder is a nonstationaryone owing to changing distance of conveyance from the pulley. Besides, the system is described by the equations with distributed parameters. The brief discussion of the theory and its practical aspects are enclosed as well.

Jan 1, 1985

By B. Samanta

A quality characteristic analysed through construction of the Shewhart control chart is required to be normally distributed. In mining applications, this assumption is often violated as many quality characteristics follow skewed or lognormal distribution. In this paper, two methods were investigated using a heuristic approach for setting up the control limits for a skewed population. Based on these approaches a Mode chart, and a Weighted Variance (WV) control charts were constructed. The performance of the proposed methods was compared with the normal based Shewhart method through a case study conducted in a surface mine supplying iron ore to a steel plant. A simulation study was also conducted to evaluate the effectiveness of the proposed methods over the Shewhart method. The study revealed that the Shewhart control charts generated more out of control alarms compared with the Mode and Weighted Variance control charts for a skewed population of Fe%. The simulation results also revealed that for extremely high skewed population, the WV control chart and Mode control chart provided higher probability of coverage than the Shewhart method; although the detection rate (probability of detection) of out of control condition for these methods was slightly reduced compared with Shewhart method.

Jan 1, 2004

By I. V. Makarskii, D. N. Nikitin, L. G. Tarasova

"The extent and nature of the damage to diamonds at processing plant is largely determined by the design features of the equipment, the characteristics of the feed ore and the parameters of the ore disintegration process (change in the rotational speed of the autogenous mills, variations of the water supply to comminution process, choice of the optimum charge, etc.). To monitor the intactness of diamonds, an instrumental method using the X-ray tomography system and colored synthetic indicator diamonds was developed for identifying the process-related damage. The X-ray tomography system consists of a CT-Portable X-ray tomographic scanner, a crystal positioning device and customized software (developed by the Fraunhofer Institute and Aliud GmbH, Germany). The developed method enables improvement of the accuracy of the results, exclusion of the subjectivity of the mineralogical assessment, acceleration of data processing and promptly planning of the activities aimed at reducing the process-related damage to diamonds. KEYWORDS Diamonds, colored indicator diamonds, process-related damage, loss of mass, instrumental method, X-ray tomography system. INTRODUCTION Industrial tests of ore processing technology at the enterprises of ALROSA PJSC are accompanied by assessment of the process-related damage to diamonds. The assessment of the process-related damage to crystals is carried out for prompt elimination of factors contributing to the increase of impact forces in the process flow sheet of ore treatment plant. For this purpose a specially selected parcel of -4.0 + 2.0 mm sized natural indicator diamonds is used. The diamonds are exposed to ionizing radiation in order to turn them green and thus to create a distinctive feature. Colored natural indicator diamonds are described, photographed in several views and introduced into the process flow sheet of the processing plant, then extracted from the process flow, described and photographed again. The comparison of diamonds before and after their passing through the process flow sheet of the plant allows to find evidence of process-related impact on the crystal and to calculate the factor of process-related damage (the number of crystals damaged during liberation and recovery), the loss of crystal weight and the degree of damage to the crystals. The method of colored indicator diamonds is used to select processing methods, equipment or regime which would be the safest for diamonds based on the analysis of the factors of process-related damage. There are limitations of the method, such as:"

Jan 1, 2018

By M. D. Khattar

Problems discussed concern encountering of high temperatures [up to 66°C] and heavy flow of water [150 L.P.S] during the construction of the 10.15 MØH.R.T. for the 2500 MW Nathpa Jhakri Hydro Power Project in the Himalayas(India). Over a length of 2500 M progress of work got seriously affected resulting in excessive time for completion - two years [max. monthly progress achieved was 178 M [Heading]. Many innovative and simple steps were taken to complete the work in these inhospitable environs affecting working of both men and machines. Also it meant a review of the design of concrete lining. Other geological conditions affecting the progress are also described.

Jan 1, 1999

By D Bruce, D Cox

The main access decline at Carrapateena mine was excavated through two different underground aquifers. In these areas of decline, pressurised water finds the path of least resistance through the rock and into the excavation. In some locations the ground water would upwell underneath the roadway resulting in rapid deterioration of the running surface. The deterioration of the road was so rapid that the two areas of decline required significant roadworks every single shift or it would become impassable by mine traffic. With a full fleet of underground trucks hauling to the surface, managing these sections of roadway was impractical and unproductive. The site team resolved this issue by installing Roller Compacted Concrete (RCC) to the affected sections of decline. RCC is a specialist concrete product that is delivered to the site near dry and is installed using a grader and roller similar to road base. This product can be installed quickly and be trafficked within hours of installation, making it ideal for mines with single access declines and unfavourable road conditions. RCC roadways were successfully installed at Carrapateena mine in conjunction with under-road drainage. These roadways have proved to be a very effective solution which requires minimal maintenance and are resistant to water ingress from the aquifer. This paper discusses the technical aspects of the RCC, as well as the practical implementation of the solution as a whole.

Mar 15, 2021

By Vitor Tomaz de Aquino, Moysés Dutra da Silva, Weslley Luiz da Silva Assis, Rafael Masulck Santos, Tiago Araújo Neves

Neste trabalho é abordado o problema das múltiplas mochilas para modelar a necessidade industrial metalúrgica de alocação de bobinas de aço em um forno de recozimento em caixa. Condições especiais de processo, exigem priorização das bobinas mais antigas do estoque para garantir requisitos de qualidade. Além do mais, algumas limitações físicas e exigências de qualidade devem ser respeitadas, tais como, a obrigatoriedade de agrupamento de bobinas de mesma qualidade e limites físicos de altura e peso. Assim, uma formulação matemática é proposta para resolver este problema, cuja função objetivo visa maximizar o peso total da carga ocupada pelas bobinas de mesmas características e priorizar as bobinas mais antigas em estoque. Os resultados computacionais mostram que a aplicação da técnica do modelo de programação linear otimiza a formação de cargas gerando resultados reais de processo.

Oct 1, 2019

By Gheorghe Dobra

Ante el agotamiento de reservas minerales, Rumanía decidió asegurar las materias primas minerales necesarias a través de la explotación de los yacimientos propios. Sin embargo, los problemas que esto genera se deriva en movilizar las capacidades de concepción y tecnología en proyectos como la explotación de yacimientos pobres. En ese sentido, el presente texto refiere las posibles soluciones de los problemas técnico-económicos de la valorización de los yacimientos pobres de Rumanía para las inversiones en proyectos de gran escala. Estas soluciones conllevan que la política del Estado debe revalorizar las riquezas nacionales y satisfacer para el consumo en la producción propia y que el valor del yacimiento se da mediante la evaluación de los productos que pueden ser extraídos y consumidos.

Sep 1, 1981

By Luis Hochschild

"El presente texto señala las posibilidades y problemas de la minería en el Perú. Para ello, primero se revisa los factores que afectan la pequeña y gran minería tales como: los impuestos, agua, agilización de la mina, desarrollo zonal, carreteras, denuncios, permisos para reinversiones adecuadas. Asímismo, se debe analizar este poder de inversión y actualizarlo cuando se le utilice para fines específicos como: construcción de campamentos, colegios, hospitales, etc y esto debe regir para la pequeña, mediana y gran minería, ya que la inversión que haga cualquiera de ellas será en beneficio del trabajador peruano. "

Jul 1, 1969

By North R. A

The Queensland Mining Act 1968-1972 has now been in force for almost two years. The Act was completely re-written and has made for easier working, e.g., there is no distinction now between Gold Mining Leases and other Mining Leases. For the first time in the history of Queensland, provision has been made for caveats, so that options etc. can be protected. The chief problem which has arisen so far has been the question of the Government issuing mining leases to the holder of an Authority to Prospect over areas which are included iri its Authority. Litigation has taken place and an Appeal, it is understood, will shortly be heard by the Privy Council. The provisions dealing with labour conditions have been brought up-to-date and generally speaking, they are quite clear as to the responsibility of the Lessee. The Mining on Private Land Act has been repealed and the provisions relating to mining on private land are now a part of the Mining Act itself. Previously, the holder of a- mining freehold did not have to pay royalty on

Jan 1, 1974

By Norman Weiss

The purpose of this paper is to relate progress in the engineering field called Minerals Beneficiation to undergraduate and graduate education in our colleges and universities. So mach has been written recently about the education of scientists and engineers that I've had to struggle against the temptation to repeat what has been often said before, particularly because man like Robert Mehl of Carnegie Tech, Antoine Gaudin of MIT, H. M. Davis of Penn State, and John Vanderwilt of Colorado School of Mines have recently written many quotable paragraphs on the subject. In the matter of progress, the rapidity of proliferation in the area of physical and chemical beneficiation is convincing proof that this is indeed a lively art, and having been a millman for 35 uninterrupted years I prefer to lean on personal observations to some extent, rather than on statistics and charts v culled from the journals. I propose in this paper to talk first about the progress we've made in our branch of the mining industry in the last 3 decades--particularly in the last few years--and try to show that future progress will depend upon the quality of education and capacity for research possessed by our colleges. The second part will deal with some of the problems the colleges encounter in trying to fulfill these responsibilities.

Jan 1, 1959

By J. M. Livingstone

"This paper covers some of the problems confronted by Canada's railways in moving bulk materials from their source to the dock-site. The ""cost center"" concept is presented, and hypothetical examples of its use given. Also discussed are systems design, the unit train and pipelines.INTRODUCTIONCANADA LIVES BY RER EXPORTS and the Port of Vancouver by the exports of the Mountain and Prairie Empire at her back. The most recent estimates of off-shore shipments of bulk from the Port of Vancouver rise to 35.8 million shipping tons in 1985 and deep-sea general cargo estimates, in and out, are estimated at 7.6 million shipping tons for the same year. This compares to 7.67 and 2.87 million shipping tons, respectively, in 1965."

Jan 1, 1968

Regions with extensive reserves of brown coal but with inadequate deposits of hard coal provide a particularly suitable field for the application of brown coal petrology.In fact, this discipline is indispensable where brown coal is to form the basis for high-quality products of upgrading. Both chemical and physical analyses are required in addition to the techniques employed in coal petrology, but it is the macropetrographic and the microscopic investigations that are of decisive and specific importance.Foremost among the methods of upgrading brown coal is briquetting. From the raw materials aspect the biochemical rank of coal (i.e. the type of deposit) and the coal variety (i.e. the lithotype) exert a marked influence on briquette strength. These are also the significant factors in the suitability of a brown coal for high temperature carbonization; here the demands on coal quality are even more exacting if adequately sintered and therefore high-strength lump chars are to be obtained. The principle applies also to the char from low temperature carbonization. There are close relationships between the tar yield and the remission of the coal.The reflectivity measurement therefore provides a rapid method for evaluating the suitability of a brown coal for low temperature carbonization. Similar correlations have been established between the content of extraction bitumen (raw montan wax) and the remission. Petrological investigations show that the quality of the coal bitumen is a function of the type of deposit and of the lithotype.

Jan 1, 1968

By Dennis K. Mortensen

Improvements in flotation technology are continually being made in the attempt to achieve the mineral processor's goal of maximum mineral concentrate grade and recovery at zero cost. Technology that cannot be totally proven in the laboratory must be tested under plant conditions either in a pilot plant or in the existing circuit. Problems associated with new technology can be solved effectively by the mineral processor who approaches each of the problems objectively.

Jan 1, 1989

By J. Loredo

Asturias, in Northwestern Spain, has an extensive mining history. As a result of these historical mine activities where operations have been usually developed with little control on effluents or emissions (environmental regulation of mining activity has only been introduced recently), pollution has been severe in some areas, specially in Hg abandoned mine sites, which constitute one of the major environmental problems related to mining. In many of these sites, materials stocked in spoil heaps can be considered as hazardous wastes because of their chemistry, content on ecotoxic elements and potentiality to spread these to the environment. In the humid climatological conditions of the region, water and wind eroded spoils are dispersed through the environment by different pathways and occasionally surrounding soils and waters are intensively affected by pollution. According to the environmental risks that these unreclaimed mine sites suppose for human beings and ecosystems, remedial options must be considered.

Jan 1, 2003

By Charles Will Wright

ALTHOUGH the United States has long led all other countries in both the production and consumption of mineral products, the trend seems definitely toward an increasing dependence upon foreign sources of supply. This is not to take the position that we are either a have or a have-not nation. For years we shall continue to secure a large proportion of our needed minerals: from our own mines, but we must face the fact that this century has seen "a more thorough and intense development of the mineral resources of the United States and a greater depletion of its irreplaceable mineral reserves than has occurred in most other countries. An audit of our mineral production given in the attached charts discloses the extent of our deficiencies. Because of these facts, low-cost foreign sources offer a promising field for the investment of a portion of our mining capital and an opportunity to obtain for the United States a greater supply of strategic metals and minerals. How. ever, to reach this end, the industrialist investing in the foreign field must have the full co-operation and strong backing of the Federal Government and the involved Federal agencies.

Jan 1, 1947