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By R. S. Shoemaker

Environmental and regulatory authorities are increasingly requiring that precious metals heap leach piles be contoured before they are abandoned so they may present a more "natural" look to the eye. Depending on the ore type, many of these contoured heaps will be subject to substantial erosion by precipitation events, native plants will have difficulty in establishing themselves and slimes be washed onto surrounding areas or into watercourses. This paper presents the argument that the results of contouring heaps are counter to good environmental practice. Calculations which have been made demonstrate that leveling and berming the heap tops as well as berming the edge of each lift or setback will effectively prevent water erosion and promote the growth of native plant species.

Jan 1, 1993

By D. Spitty

There are enormous complexities with mine planning and the problem itself presents a huge challenge to the existing mine planners performing this activity. Mine planning optimization supports planners to determine ?What are the best increment excavation sequence and the best material blending combination such that throughput, quality, cost, utilization and Net Present Value (NPV) targets are met?? It is achieved through using an advanced scientific approach that has been specifically adapted to address the mine planning dilemma.

Feb 23, 2014

By J. B. Lott

The authors' company has recently undertaken a development programme aimed at exploring the relationships between the variables of greatest importance in the design of mixer-settlers for metallurgical solvent extraction applications. Such applications vary from relatively small scale plants treating copper mine waters, nickel containing effluents, etc., where the total flowrates may be of the order of a few hundreds of gallons per minute, to very large scale plants treating several thousands of gallons per minute of leach liquors containing copper, uranium or other metals. This paper outlines the physical and mechanical factors which must be taken into account when designing mixer-settler systems for large scam. solvent extraction plants. The performance of the equipment will also be dependent upon the chemistry of the system, including the kinetics and thermodynamics of the ion exchange reaction itself, the effect of impurities flocculants, surfactants, temperature, etc., but these will not be dealt with here. Much of the laboratory work has been carried out using copper containing solutions and either LIX 64* or LIX 64N* as the solvent dissolved in various grades of kerosene. For simplicity, all the graphs and tables of results which are presented and discussed here will refer to the LIX-copper system, although the conclusions will in many cases be generally applicable to other systems also. The LIX-copper process is now sufficiently well known to obviate the need for a full description, however, an outline flowsheet of the process is shown in Figure 1. The ultimate objective of a laboratory programme for a particular extraction application is to provide data upon which a mixer-settler system can be designed to handle a given throughput of leach liquor and extract from this liquor the maximum quantity of metal for the minimum cost. In other words, the objective is to determine the design and operating parameters which achieve the optimum balance between capital and operating costs. * Trade-marks for General Mills solvents.

Jan 1, 1971

By R. G. Reddy

Spent potliner is generated in the electrolytic process of reducing alumina to make aluminum metal using molten fluoride electrolytes. Spent potliner (SPL), obtained at the end of the pots life contains a small amount of cyanide and fluoride which present environmental problems. SPL became a listed hazardous waste under RCRA (K088) in July, 1990. One of the possible uses of spent potliner is as a substitute for Calcium Fluoride (CaF2) as a fluidizer in iron-and steel making and in the glass industry. A low viscosity and a low melting point are prime requirements for accomplishing the above. In the present study, viscosity measurements were performed. Effect of various additives, such as sand, limestone, dicalcium silicate dust, and MgO baghouse dust on the viscosity of SPL was studied. The results showed that with the addition of sand and limestone, very high fluidity of SPL melt can be obtained at significantly low temperatures. The results suggest that spent potliner mixed with additives could potentially be used as a substitute fluidizer.

Jan 1, 1999

By Yves C. Lizotte

Although blasting remains the most inexpensive method of fragmentation in hardrock mining, the significance of the costs of blast-induced rockmass damage in terms of mining efficiency and safety is becoming increasingly recognized. There is no straightforward and systematic method of adequately measuring blast damage in on-going mining operations. This paper considers various techniques available to measure blast damage, making particular reference to recent underground hardrock mine studies. It concludes by proposing a damage audit procedure for integration into routine mine production control.

Jan 1, 1996

By Emily Sarver, Cigdem Keles, Jonathan Gonzalez

The study re-examines respirable coal mine dust samples using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). It finds that SEM tends to overpredict the abundance of dust from rock strata and underpredict coal content, possibly due to coal-mineral microagglomerates (MAGs). The findings suggest that MAGs could be valuable in improving dust controls in mines.

Feb 10, 2022

By Drummond Earley III

The hydrology of in situ leach mining operations is being studied by the U.S. Bureau of Mines using a variety of techniques, and the Bureau has made significant advances in tracking and modeling the flow of leach solutions in rock formations. However, the influence that leach solution composition has on the hydrology of these systems is poorly understood, and geochemically-controlled changes in the hydrologic characteristic of ore deposits during in situ leach mining of porphyry-hosted, copper oxide ores have not been previously studied. The Cyprus Casa Grande in situ leach mining operation mines fracture-hosted and disseminated copper oxides (predominantly chrysocolla) hosted by granodiorite porphyry using a pattern of underground wells. The injection solution consists of sulfuric acid raffinate from a solvent extraction-electrowinning plant. Chemical analysis of representative injection and recovery solutions reveals that gangue cation concentrations in these solutions are high, and geochemical modeling shows that the solutions are saturated or nearly saturated with respect to gypsum, jarosite, and various amorphous oxides. Precipitation of these solids is evoked by calcium-exchange reactions, rising pH, and perhaps locally rising redox potential, as the leach solution reacts with the ore minerals, host rocks, and the atmosphere. Mass and volume balance calculations show that approximately 25 cm of precipitates are formed per gram of copper recovered at Cyprus Casa Grande. The results of geochemical modeling agree with petrologic examination of pre-and post-leach core samples from the leached horizon. Moreover, hydrochemical modeling and hydrologic field data suggests that chemical precipitation causes significant decreases in porosity and permeability during in situ leach mining of porphyry-hosted, copper oxide ore.

Jan 1, 1992

By J. A. Herbst

It is widely recognized that Semiautogenous Grinding (SAG) circuits require the use of effective process control techniques to achieve their full processing potential and to protect them from the harmful effects of overloads and grind-outs. This requirement is even more essential as the variability of the ore being processed increases. The new Chino Mines Company concentrator located near Santa Rita, New Mexico started operation in June of 1982. At least eight major rock types are mined and milled. Ore hardness, feed size, and specific gravity are quite variable. Typical feed rates per grinding line are 850-900 tph but extremes of 260-1200 tph have been encountered. Normal feed rate variations of between 400 and 1100 tph are encountered on a weekly and sometimes daily basis. Feed size varies with rock type from a maximum of eight inches for the harder ores to two inches for the softer ores. One somewhat unique characteristic of the Santa Rita ore body among major copper mines is the wide variation in ore specific gravity. Specific gravities of the major rock types range between 2.7 and 3.6. The specific gravity variations are due to large changes in magnetite concentration throughout the pit. The result of this is large variations in SAG mill throughput which can have a harmful effect on downstream ball milling and flotation performance. Due to these wide fluctuations in ore characteristics, it was recognized soon after startup that successful operation of the grinding circuit and the plant at large was dependent upon the development of an effective automatic grinding control strategy. Research at the University of Utah has suggested that control based upon critical but difficult or costly to measure variables would improve automatic control performance. A project team made up of the Chino process control staff, Kennecott's Process Control department and the University of Utah Metallurgy Department was established to assess these concepts at Chino. This paper describes the development and on-line plant implementation of an Extended Kalman Filter that uses simple models of the SAG milling process, to predict the volumetric loading, the rock mass, the water mass, and the ball mass within the SAG mills at Chino. The on-line estimation of these parameters is the first step in the development of an integrated SAG mill/ball mill control strategy which is hoped to L eventually maintain the grinding circuit at its maximum capacity, while balancing the grinding load between the SAG and ball mills. Examples of long term estimation with the models and filter are shown for typical operating conditions as well as a SAG mill overload and grind-out.

Jan 1, 1983

By E. S. Forbus

A process for producing reductive bleach in-situ in kaolin slurries has been developed. The bleach is formed by mixing an iron sponge powder (-325M) with slurry treated with SO2. The process has been successfully demonstrated in production, and applied to several grades. The color, brightness, and viscosity of the bleached product is equivalent to or better than that of product bleached with commercial sodium hydrosulfite . The tested products can be bleached at a cost, which is 38-54% of those associated with the use of commercial bleach.

Jan 1, 1993

By G. A. Gruber

A flotation process has been developed to successfully treat ore from the Santo Domingo phosphate deposit in Baja California Sur. The ore contained less than four percent P205 with quartz, silicates, and carbonates as gangue minerals. Flotation of the low grade feed In sea water required that the conventioinal Crago Process, comprising direct anionic flotation, deolling, and inverse cationic flotation be augmented by an anionic cleaner flotation step, phosphate depression, and a calcite flotation step.

Jan 1, 1986

By Ralph C. Kirby

The U.S. produces about 34 percent of the world's aluminum yet must import 90 percent of the raw materials needed. There are abundant resources of aluminum-bearing minerals such as clay, anorthosite, alunite, shale, and dawsonite, but none of the numerous processes proposed for recovering alumina from them has yet proved economically competitive with the Bayer process using imported bauxite. To help develop an economically viable process for utilizing these resources, the Bureau of Mines is testing on a common basis several proudsing processing techniques. New improvements and approaches developed by industry and the Government are being evaluated on a mall scale to obtain enough information on which to form a judgment regarding the best processes for commercial adoption. A continuous miniplant having a feed rate of about 70 pounds per hour is being operated now to investigate the nitric acid process for recovering alumina from clay. Parts of this plant will be used subsequently for work on other processes for recovering alumina from clay, anorthosite, alunite, and dawsonite. Initial results of the operation and plans for the overall project will be discussed.

Jan 1, 1974

By S. K. Ghosh

This paper discusses how the information on ash composition, ash-fusion temperatures, and ash-slag viscosity can be utilized to predict slagging and fouling potentials of a particular coal. A review of several empirical parameters which are commonly in use for determining such potentials is given. Also, some guideline values for interpreting the relative propensity of slagging and fouling of various types of coal are provided.

Jan 1, 1983

By H. Maleki

This paper recognizes the 100th year of research accomplishments by the mining industry resulting from close cooperation among mining companies, geotechnical consultants and researchers from the former United States Bureau of Mines in stability assessments and development of improved and productive mine designs. The paper provides an overview of dramatic developments in geotechnical instrumentation, and its applications in the U.S. and around the world for enhancing the understanding of ground response to mining-induced changes in stress, resulting in improvements in ground control technologies.

Jan 1, 2010

By Y. Q. Zhang, Y. Luo, S. S. Peng

Burrier pillars in underground coal mines could eventually be subjected to a water head due to the build-up of mine water in the old workings. The water head could not only act ns a force to destabilize the pillar, but it could also cause seepage flow through the pillar and its surrounding strata. Excessive seepage flow could induce piping failure that, ill turn, could accelerate the mechanical failure process of the barrier pillars. In this paper, a finite element simulation approach was employed in the evaluation of the barrier pillars. Both the stress distribution and the seepage flow pattern in and around a barrier pillar have been simulated numerically. The effects of ground stress on rock permeability to water seepage has been taken into consideration in these simulations,

Jan 1, 2002

By R. Thorpe, M. Dosbaba, A. Kopriva, A. Niiranen, J. Ruokanen

"Automated Mineralogy (AM) is an important diagnostic tool in flotation plants as it adds ore and particle mineralogical properties to traditional mass and chemical data. AM is used in project development, for future ore studies and for diagnosing concentrator operations. With the exception of operations who own central laboratory or on-site systems, the use of AM is often limited to the analysis of a comparatively small set of samples. Metrix Plant Technologies has partnered with TESCAN to integrate TIMA AM technology into the implementation of Performance Assessment Campaigns (PAC). Routine daily composite samples from the mill are analysed mineralogically on a size-by-size basis over several weeks. All the relevant metallurgical, process control and mineralogical data is combined into a single large database for mass balancing and interactive examination. This paper describes the implementation and results of a PAC at the Agnico Eagle Kittilä gold mine in Finland. Although challenging, the addition of mineralogical data as dependent variables in multivariate analysis leads to a much deeper understanding of the root cause effect of events driving the flotation performance. INTRODUCTION TO STUDY The Kittilä mine, owned by Agnico Eagle, is Europe’s largest primary gold mine, with annual production of approximately 180,000 Oz. The operation is located in Lapland in northern Finland, and is currently expected to operate until 2035. The location of the operation is shown in Figure 1. Historically, the mine was an open pit, although in recent years ore is sourced solely from underground operations. The processing plant features crushing and grinding, followed by carbon flotation and sulphide flotation. Carbon concentrate is a waste stream, and sulphide concentrate reports to pressure oxidation (autoclave) and CIL circuits for gold extraction. The final flowsheet is shown in Figure 2. Following commissioning in late 2008, the operation achieved commercial production on May 1st 2009. Gold recovery in flotation gradually increased to a 92-96% range at a throughput of ~3500-4000 tonnes per day. In late 2014, the operation commissioned a plant expansion to ~5000 tonnes per day. Following a commissioning period, the operation stabilised with recoveries in a 90-94% range, which over any given period was determined to be ~2% lower with statistical significance. The trends from start-up of gold recovery in flotation and throughput are shown as follows in Figure 3. In early 2016, Agnico Eagle Kittilä mine, along with Agnico Eagle Technical Services (AETS) partnered with Metrix Plant Technologies and TESCAN, to perform a Performance Assessment Campaign (PAC) at Kittilä, involving automated mineralogy on five key streams at Kittilä on 40 days selected from a 50 day period between February 15th and April 4th 2016, when plant operations were stable. In addition to the mineralogical data, metallurgical and operational data were pooled into a single, powerful database to explore opportunities for the operation to improve recovery in a sustained manner, ideally to the levels pre-expansion."

Jan 1, 2017

By Irina Melekestseva, Beltenev. Victor, Victor Ivanov

"One of the major problems discussed over the last years is a possibility of mining of seafloor massive sulfide deposits. In spite of the pessimistic points of view on their commercial development, they are still of great interest and continue to be studied (Hannington et al., 2011). Recently, Barriga (2012) paid special attention to the underestimated amount of massive sulfide hydrothermal fields and pointed to the importance of the buried fields and subseafloor mineralization.This study examines the geochemistry of seafloor and subseafloor precipitates collected at the Peterburgskoe (19°52´ N) and Irinovskoe (13°20´ N) hydrothermal fields (MAR) during the 34th cruise of the R/V Professor Logatchev in 2011. These fields were discovered by the Polar Marine Geosurvey Expedition in 2010 and 2011, respectively (Shilov et al., 2011; Beltenev et al., 2012). The Peterburgskoe field, associated with basalts, is located 16 km west of the main rift valley at the depth of 2800-3100 m at the junction of a large non-transform discontinuity with the second rift ridge parallel to the rift valley. The Irinovskoe field occurs at depths of 2700-2850 m and has a northwestern satellite sulfide site, both confined to an oceanic core complex (MacLeod et al., 2009), which includes mafic and ultramafic rocks. The details of geological structure of the fields may be found in the relevant papers.Diverse samples were collected from the hydrothermal fields: seafloor massive sulfides, Fe-hydroxide crusts, SiO2-rich sulfide-bearing precipitates, and subseafloor mineralized rocks (Melekestseva et al., 2014a). Massive sulfides may be subdivided on the Fe-rich and Cu-rich types. The marcasite-pyrite, pyrite, hydroxide-marcasite, and chalcopyrite-pyrite (Fe-rich) mineral types are dominant in the Peterburgskoe field at lesser amounts of sphalerite-hydroxide-chalcopyrite and pyrite-covellite-chalcopyrite (Cu-rich) massive sulfides. The mineralized sulfide-talc-carbonate-chlorite, chlorite-sulfide-quartz, and hematite-sulfide-quartz rocks host stringer-disseminated sulfides including chalcopyrite, covellite, and pyrite."

Sep 1, 2014

By T. Panhorst

Evaluation of through-deck blasthole sample reliability at the Lone Tree gold mine revealed a non-systematic bias in the sampling system. Ore is primarily hosted within the Powerline fault zone. Clay gouge, present in the fault zone and typically enriched in gold content, forms agglomerates during blasthole drilling leading to a segregation error during sampling. Replicated samples split from blasthole cuttings piles show through-deck samples to be either significantly enriched or depleted by 1.5 standard deviations or more from the mean gold content of their respective cuttings pile quality of through-deck samples correlates strongly with quantity of clay present.

Jan 1, 1999

By Arthur B. Cummins

It is appropriate to discuss diatomite at an AIME meeting in San Francisco. California has led the nation, and the world, in the production of diatomite products for more than 40 years. It appears that our State will maintain this position for a long time to come. Diatomite today ranks high in the list of California mineral commodities, with a total value since 1889 well in excess of $100 million. California's production has more than doubled since 1942. In 1959, the value of diatomite production in California is exceeded only by the following industrial mineral materials-borates, stone, sand and gravel and cement20,28. Also, not unimportant is the production of diatomite in each of our other Pacific Coast States, including Nevada. First, let us define diatomite. It is a sedimentary siliceous rock of organic origin, which consists mainly of the fossilized remains of diatoms. Diatoms are microscopic aquatic plants which have the capacity of precipitating silica bio-chemically so as to form a part of their organized structure. In the economic sense, we are not concerned with the numerous types of sedimentary materials which contain minor amounts of diatom residues, or with impure or highly indurated siliceous materials, which may have been formed from diatomite2. Diatomite (synonyms--diatomaceous earth, kieselgurO is a term generally restricted to material of such qualities as to be suitable for commercial uses. Diatomaceous silica is a designation which is best used to distinguish the basic component of diatomite, that is, the substance of the silica shell itself, and which is the major' constituent of beneficiated diatomite or processed diatomaceous products.

Jan 1, 1959

By K. M. Mohamed, I. B. Tulu

"Failures of coal ribs are major hazards in underground coal mines. For the period of 2010 to 2014, rib falls were the leading cause of groundfall fatalities and accounted for 35% of all groundfall-related fatalities. Currently, the National Institute for Occupational Safety and Health (NIOSH) is conducting a research project to develop an engineering-based design methodology for rib control in coal mines to reduce rib fall accidents and fatalities in underground coal mines. Numerical models can be used as part of the design methodology provided the models are appropriately calibrated and verified. The paper presents a coal rib model to simulate the mechanism of the coal deformation and fracturing that can lead to stress-driven rib falls. The proposed coal rib model was calibrated against published data from an instrumented rib site at the West Cliff mine in Australia. Fracturing of the coal rib was defined by critical values of shear strain of the coal material and rib displacement. A critical plastic shear strain of 2.8% and a sudden increase of rib displacement of 30 to 45 mm were sufficient to develop a fracture plane in the rib model. Accordingly, a discontinuous rib deformation was achieved and it compared favorably against field monitoring data. INTRODUCTION Coal ribs are the vertical walls of coal formed when entries are developed in a coal bed. Failures of coal ribs are a major hazard in underground coal mines. Furthermore, failing ribs can contribute indirectly to roof and floor instability by increasing opening widths across intersections and entryways. Over the last 18 years, there has been a continual occurrence of injuries and fatalities in underground coal mines due to rib falls. For the period of 2010 to 2014, rib falls (excluding longwall face and bursts) were the leading cause of ground fall fatalities and accounted for 35% of all groundfall-related fatalities [1]. Despite the threat of rib falls, the amount of rib falls and rib support research conducted in the U.S. is limited compared with what has been done in pillar and roof support design. Currently, the National Institute for Occupational Safety and Health (NIOSH) is conducting a research project to develop an engineering-based design methodology for rib control in coal mines to minimize the number of rib fall accidents and fatalities in underground coal mines."

Jan 1, 2016

By Charles J. Johnson

The United States is totally dependent on imports for all primary chromite and most ferrochrome supplies. Although the United States imports chromite and ferrochrome from a number of countries, the long-term future of chromite supplies appears to lie in southern Africa (Republic of South Africa and Zimbabwe) where 88 percent of known world reserves exist. Floreover, low mining costs and the availability of low-cost electricity for ferrochrome production gives South Africa a comparative advantage over most other chromite and ferrochrome-producing nations. A well-known problem faced by the United States is that when viewed from a longer-term perspective, the major sources of supply of metallurgical grade chromite and ferrochrome may be subject to disruption. The three countries that have caused the greatest concern have been the Republic of South Africa, the Soviet Union, and Zimbabwe. South Africa presents a particularly difficult problem because it may be subject to internal political unrest and/or U. N, economic sanctions. South Africa has increased its share of world chromium production from about 30 percent in 1968 to 62 percent in 1978.1

Jan 1, 1982