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By D. H. Dvorak

Two pilot-scale biological reactor systems were installed to treat metal-contaminated water. The reactors consisted of barrels and tanks filled with spent mushroom compost, within which bacterial sulfate reduction became established. Concentrations of Fe, Zn, Mn, Ni, and Cd were lowered by over 95% as these metals were precipitated as insoluble sulfides by reaction with bacterially generated H2S. The chemistry of the reactor systems is examined, and opportunities for maximizing their metal-retaining and alkalinity-generating potentials are discussed.

Jan 1, 1991

By Satu Jyrkönen

A single-particle laminar-flow technique was used to study reactions of sulfidic nickel particles. The studied materials were three natural nickel concentrates and four synthesised nickel mattes. The variables of the experiments were the gas preheating temperature (500 - 1300°C), the composition of the reaction gas (N2 + 0 - 75 vol-% 02) and the ,particle size of the feed. Chemical analysis of the particles was used to determine the oxidation degree of the materials, and optical and scanning electron microscopy were used to detect alteration in their morphology, internal composition and structure. General reactivity of the materials was monitored by the extent of sulfur removal. The reaction mechanism of the studied materials was found to depend primarily on the materials composition as well as oxygen content of the reaction gas.

Jan 1, 1998

By Jack Parker

"The original design of mine openings and pillars at White Pine was based upon traditional assumptions; i.e., that the principal load is due to the weight of overburden, and that horizontal stresses are equal to one-. third of the vertical.Beginning January, 1964, borehole deformation measurements confirmed suspicions that the principal stress is horizontal and several times greater than the vertical.Vertical stress appears to be directly related to depth, but lateral stresses vary considerably in direction and magnitude. The direction of major principal stress lies parallel to the bedding and is apparently parallel to tension joints. Lateral stresses appear to originate from an igneous intrusive.Mining induces stresses which add to the primitive stresses, in some areas precipitating failure. In this paper, rock failures are illustrated, methods of measurement and typical results are given, and measures to counter or utilize the lateral stresses are described."

Jan 1, 1966

By Alessandro Navarra, Amir Arash Rafiei, Kristian Waters

Mathematical programming (MP) is fundamental to systems engineering and operations management, but has not been widely adopted by mineral processors. The current paper presents an interdisciplinary approach, using MP to incorporate basic notions of mass balancing into an optimization framework. The optimization is typically related to economic profitability. Two- and three-product formulas are extended to give formal descriptions of alternate modes of operation, and a global representation of the concentrator. At this global level, the framework may assist plant managers to make tactical decisions based on incoming feed data. The MP framework is demonstrated through sample calculations describing a lead-zinc concentrator.

Jan 1, 2015

By N. Ogbonna, D. G. Dixon

Although heap bioleaching has been recognized as an economic alternative for treating low grade mineral ores, the underlying physical, chemical and biological processes involved are complex. A detailed investigation into the dynamics of heap bioleaching processes has provided much insight into the underlying complexities, and has led to the development of a sophisticated modelling tool - HeapSim. This tool can be of great help in the design and operation of heap bioleaching processes. In this paper, the mathematical model implemented in HeapSim is examined. The model takes into account mineral kinetics, particle level effects, bacterial growth, oxidation and adsorption, gas absorption, pore diffusion, bulk advection, gas balance and heat conservation. Three case studies where the model has been applied are briefly discussed. Computational Analysis in Hydrometallurgy 35th Annual Hydrometallurgy Meeting held in conjunction with the 44th Annual Conference of Metallurgists of CIM Calgary, Alberta, Canada Edited by

Jan 1, 2005

Rest potential, cyclic voltammetry and chronoamperometry measurements were made to study the effects of cathodic polarization of chalcopyrite simulating the mineral contacted with grinding media under a nitrogen atmosphere. The reaction products on the chalcopyrite surface were identified by XPS and the mechanism of the cathodic reaction was proposed. Micro-flotation tests were performed to investigate the effects of surface changes on the floatability of chalcopyrite.

Jan 1, 1991

By S. Castro, L. Gutierrez

"Mining operations are often located in remote arid environments with limited access to fresh water. Shortage of fresh water in such cases makes it necessary to use seawater in mineral processing plants. Such plants treating Cu- Mo sulfide ores in seawater have been fully operational in Chile (e.g. Las Luces, Centinela). In many cases process waters used in commercial flotation plants (e.g. Mt Keith in Western Australia) are even more concentrated electrolyte solutions than seawater. This paper is an attempt at classification of the flotation operations carried out in process waters that are concentrated electrolyte solutions.INTRODUCTIONAccording to Gleick (1966), of the total Earth’ water resources 97.5% is in the oceans and ice caps, and thus only about 2.5% is fresh water. Shortage of fresh water in many parts of the world makes it necessary to use seawater in mineral processing operations. The existing commercial operations using seawater as well as recent research projects that deal not only with sulfide ores but also with apatite ores provide a lot of information that can now be generalized. The progress that has been made in this area is reviewed and based on this information an attempt is being made at classifying the flotation operations carried out in highly concentrated electrolyte process waters.SALT FLOTATIONFlotation in highly concentrated electrolyte solutions was studied by Klassen (Klassen, 1963). He reported that hydrophobic, bituminous coals, could float in salt solutions without addition of any other flotation agents. The process is referred to as salt flotation. Other inherently hyhrophobic minerals (e.g. talc, graphite, sulfur, etc.) were shown to behave similarly (Klassen and Mokrousov, 1963)As Figure 1 shows, some coals float quite well in solutions of Na2SO4, NaCl and NaNO3 (Klassen, 1963). While there are differences between the tested salts (explained by different foamabilities of these solutions) all the tests indicate that only bituminous coals float well in concentrated electrolyte solutions. 0.3 M solutions are quite sufficient to initiate a good and very fast flotation. If wettability of various coals is compared it becomes obvious that these well floating coals are very hydrophobic bituminous coals (Figure 2)."

Jan 1, 2018

By Toru H. Okabe

As part of a systematic study on the thermodynamic properties of complex nitrides, phase equilibria of the system Li-M-N (M Mg, AI, Ga) at 900 K were investigated. An attempt to determine the thermodynamic properties of complex nitrides was made by using the galvanic cell method, which utilizes LiMgN as an electrolyte under nitrogen atmosphere. The electromotive force (Emf) of ilie cell at temperatures between 800 and 1100 K was measured. Whilc the Emf of the cell at 900 K was measured to be 0.137 V, data discrepancies of ±0.03V were found. It was difficult to determine temperature dependence of ilie Emf. The Gibbs energy change for the reaction, 113 LbN (s) + 1/3 Mg3N2 (s) = LiMgN (s), at 900 K was determined to be tJ.Gor (LiMgN) -13.2 (±2.9) kJ/mol. Using thermodynamic information on ilie binary nitride from literature, the standard Gibbs energy of LiMgN was derived to be AGO f (LiMgN)= - 121 kJ at 900 K. The thermodynamic stability range of nitride was discussed by constructing isothermal chemical potential diagrams that provide a better understanding of ilie stability region of the LiMgN phase. The diagram was found to be in good agreement with the isoiliermal phase diagram determined by ilie alloy equilibration meiliod. Although the obtained data includes large uncertainties, the results provide a better understanding of the iliermodynamic stability of nitrides. The potential application of this complex nitride to nitrogen chemical sensors or a medium for controlling nitrogen potential is also shown.

Jan 1, 2003

By R. B. Hopler

Explosives R&D has historically been motivated by coal mining. Whether to solve safety problems or to improve productivity and cost, the result has been the same: better explosives products and initiation systems. This process continues at an accelerated pace today due to the tools presently available to the explosives and mining industries.

Jan 1, 1993

By G Clarke

Commissioning of the Cannington processing plant began in October 1997. The nameplate capacity (of 1.55 million tonnes of ore per annum) was achieved relatively quickly. Since then (like many mines) the operation has strived to increase throughput and improve valuable metal recoveries, to offset declining head grades and lift the value of the operation. The processing plant now has the capability of treating over 3.2 million tonnes of ore per annum and in financial year 2005/06 the combined concentrate production exceeded 600 000 wet tonnes, approximately 80 per cent above concentrate output in the first full year of operation (at the design feed rate). This improved performance was achieved by making changes and additions to each of the major unit processes û primary grinding, flotation, leaching, filtering and paste fill preparation. The changes have included: adding a fines flotation circuit, expanding the grinding circuit, adding a pebble crusher, switching from continuous to batch leaching, building paste conveyors and decommissioning the column flotation cleaning circuits. This paper reviews these changes, outlines the current operating practices and discusses the challenges or opportunities that remain.

Jan 1, 2007

By Juan Estrada, Mirtha Frómeta, Rubén Alcalá, Emilio Montejo, José Castellanos, Juan Berto, María Rivas

"The oxidized nickel ores from San Felipe deposit are composed mainly Smectites which gives to the pulps very unfavorable rheological .properties (cinematic viscosity and high shearing strength) for transportation processes (pumping), very low settling velocities and very low thickened pulps. These properties do not allow the preparation of high % solids, which affects the economic efficiency if a high pressure acid leach (HPAL) process is used. Pulps of close to 30% solids have very high BYS making pumping impossible. CIPIMM developed three technologies to solve these problems and to substantially increase the % solids in the pulps to be leached without a thickening step. These technologies are: • CIPIMM 2. At Preparation of pulps using additives. This method is based on the effect of some additives (inorganic salts) to improve the pulp’s properties. The use of this method allows increasing the % solids in the pulp up to 40% with good rheological properties • CIPIMM 2B. Preparation of pulps by thermal treatment of the ore previous to the preparation of the pulps. This method is based on the thermal destruction of the clays structure. Its use allows to obtain pulps with 50 - 60 % solids with excellent rheological characteristics. As a collateral effect, the Ni and Co grades increases by 10 - 15%. • CIPIMM 2C. Pulp preparation by chemical treatment. This method is based on the chemical transformation of clays, to obtain without thickening, pulps with 43- 45% solids and excellent rheological properties. The use of one of the three technologies depends on the chemical and mineralogical composition of the ores and the results of technical-economical evaluations to determine which one is the best alternative before running higher scale tests."

Jan 1, 2014

By Patrick Rennkamp, Wolf-Dieter Trodel, Andy Fearn

"The Jansen shafts are completed using purely mechanical excavation. This paper summarises the geology, a description of the shafts, the method used for excavation and the results achieved along with the challenges encountered and the solutions developed during the project. This experience is now being applied in the next generation machines and shaft sinking processes. This pioneering approach is changing shaft sinking in soft and medium to hard rock. INTRODUCTION The Jansen Mining project located approximately 150 km east of the city Saskatoon is the location of the BHP owned potash mine with an expected mining output of eight million tonnes annually upon completion. Mining contractors DMC Mining Services have used two Herrenknecht Shaft Boring Roadheaders (SBRs) to excavate the two blind shafts with an approximate excavation diameter of ten metres (inner diameter approximately 8.3 m) to depths of -975 and -1005 metres, respectively. The SBRs excavate the rock by a partial-face cutting method, using a transverse cutting drum mounted on a telescopic boom. The excavated rock is then conveyed away from the bench by an innovative pneumatic system and transferred into muck buckets to be hoisted to the surface. No drilling and blasting was done to keep to the BHP philosophy of using only mechanical excavation for this reference project. BHP VISION – MECHANICAL EXCAVATION BHP focused on mechanical excavation at Jansen due to the following perceived benefits: 1.No workers in the excavation chamber (shaft bottom), minimizing the exposure to traditional shaftsinking hazards associated with working in the shaft bottom. 2. Minimal damage to the rock fabric reducing the need for ground support and avoiding potential impact damage to freeze tubes located around the shaft. 3. Accurate excavation diameters with no overbreak, reducing volumes of rock to be removed and replaced with concrete lining."

Jan 1, 2019

By Young-Geun Park

A new decarburization model for the RH system was constructed for calculating the decarburization reaction using a three-dimensional fluid dynamics program. The entire fluid flow in the RH process was calculated by evaluating the shape and volume of the plume zone, formed by Ar gas blown through multiple nozzles on the wall of the snorkel. On the basis of this fluid flow, the decarburizaiton reaction was calculated through establishing the decarburization reaction model, which considers the thermodynamics, reaction kinetics, and the decarburization sites (Ar bubble surface, bath surface, and the CO bubble fomtation at inner sites). The results from this model were compared with a real RH operation results with good agreement. Because it is possible to predict the carbon concentration at various conditions using this model, it may be useful in increasing the decarburizaiton rate. Key words : RH process, plume zone, decarburization, Ar bubble surface, bath surface, inner site, circulation flow rate.

Jan 1, 2001

By G. Chancellor

"INTRODUCTION The paste plant is located at the Barrick Goldstrike mine in Northern Nevada on the Carlin Trend. The Goldstrike property consists of an open pit and an underground mine; along with two processing facilities: a roaster and an autoclave. The underground portion of the mine produces approximately 1,800,000 ore tons per year and approximately 400,000 ounces. The mine is broken up into four distinct zones: Banshee, Meikle, Rodeo and Northpost. The current paste plant services both the Rodeo and Northpost zones. Development of the conceptual designs and permit approval for this plant was an extensive process that took over a decade to complete. A testing program was developed in conjunction with this process and implemented throughout to ensure the following metrics were achieved: ensure no environmental impact, material available onsite would be able to flow through the pipe to all required locations, and that this material could achieve the appropriate final strength. PLANT AND UNDERGROUND CONSTRUCTION This is the first paste plant to be built in Nevada. The paste plant at Goldstrike began construction in January 2012 and was completed in March of 2013. This plant was constructed to service the Rodeo side of the underground mine which previously utilized a cemented rock fill (CFR) plant to meet their backfill needs. However, in March of 2013, the same month the plant was commissioned, the raise that fed this CRF plant was mined out in a planned phase of the adjacent open pit. This made the switch to paste all the more difficult as it was being relied on for as the sole source of backfill production even though the system yet to be fully tested and optimized. The plant was designed to be fed with onsite Roaster tailing which would be thickened and then mixed with cement and fly ash. The plant was designed to pump 177 tons of paste per hour with a utilization of 65%. The original design specifications for the paste were 77% solids with varying binder contents depending on where the paste was being placed"

Jan 1, 2015

By K. Barbetti, J. Avraamides

"The processing of gold ores with high silver contents can provide operational challenges, such as high cyanide consumption, retardation of gold leaching and competition during adsorption stages of carbon-in-pulp/leach/column (CIP/CIL/CIC) circuits. In particular, the silver, which is about 1.5% of the value of gold, competes with gold during carbon adsorption due to its higher concentration in many Ag-Au ores, potentially leading to gold solution losses. Fresh and partially fouled (barren and regenerated) activated carbons were evaluated at various Ag:Au ratios and total metal concentrations with regard to the adsorption kinetics and equilibrium loadings. Conventional Freundlich isotherms were found to be highly inaccurate for predicting equilibrium loadings in the competitive adsorption environment. An integrated model, which incorporates competitive adsorption kinetics with a modified competitive adsorption isotherm model has been developed and validated using plant and laboratory data. The model performance and some of its salient features will be discussed.INTRODUCTIONThe processing of gold ores with high silver contents can present a range of operational challenges, such as high cyanide consumption, retardation of gold leaching and competition in carbon adsorption circuits. Silver is often present at significantly higher concentrations than gold in many gold-silver ores and competes with gold in carbon adsorption circuits, limiting the gold loading rate and capacity, resulting in gold solution losses and reduced gold recovery.Curtin University’s Gold Technology Group has evaluated fresh and partially fouled (barren and regenerated) activated carbons at various Ag:Au ratios and total metal concentrations to determine the adsorption kinetics and equilibrium loadings for gold and silver. Conventional Freundlich isotherms were found to be highly inaccurate for predicting equilibrium loadings in the presence of both gold and silver.An integrated model, which incorporates competitive adsorption kinetics with a modified competitive adsorption isotherm model has been developed and validated using plant and laboratory data. This paper describes the model performance and some of its salient features."

Jan 1, 2016

By David N. Montgomery

The characteristics of a closed cavity acoustic coupler were measured. Various configurations were investigated to determine their feasibility for use in a portable audio dosimeter calibrator.

Jan 1, 1976

By Douglas K. Modrow

In the fall of 1993, construction was completed on a state of the art industrial waste water treatment plant at Asarco's East Helena Lead Smelter. Purpose of the plant was to remove arsenic and metals using hydroxide precipitation. Completing of the plant culminated a lengthy process of laboratory bench-scale test work, engineering, construction, and Environmental Protection Agency (EPA) oversight. Unfortunately, the effiuent requirements for the plant were made significantly more stringent as construction was rearing completion. As a result, optimization activities were initiated to determine and implement measures to substantially improve effiuent quality so the new discharge limits could be met. These activities consisted of acquiring a thorough understanding of process chemistry and plant operations, and developing simple, practical methods of automating unit operations associated with the treatment plant. Implementation of these modifications in the second half of 1996 will not only significantly improve the constancy and reliability of treatment plant operations, but also result in operating cost savings and reduced need for increased operator attention at capacity flows, plus allow the treatment plant to meet the new discharge limits.

Jan 1, 1996

By Oliver C. Ralston

The growing popularity of perlite (sometimes spelled pearlite) as a raw material for thermal expansion into pumicelike products in the Western States has prompted a preliminary investigation of the properties of such material and the problems that want solution to put a perlite industry on a firm foundation. The Bureau of Mines is undertaking the gathering of data and the solution of these problems, and the following paper records some of the available information. and the promise of the material, with some comparisons of advantages of the various competing lightweight aggregates that can be made from siliceous volcanic glasses and rocks containing entrapped or dissolved water that causes their expansion on' quick heating to their softening points. This new industrial rock has caught the fancy of the mineral industry in the western States because it has Fume advantages over natural pumice. Chemically, it is typified as rhyolitic in composition, and one may find obsidian, rhyolite, pumice, pumicite, and perlite from the same vant and contemporaneous in origin. The material need not be rhyolite but should be a siliceous or acid lava and contain 2 to 5 percent water still in "solution" in the rock. On quick heating to the softening temperature the material puffs, due to conversion of the contained eater into bubbles of steam. Slow heating causes gradual release of the imprisoned water by decrepitation and. cracking and-results in, very little puffing. Perlite is often in the form of ovoid volcanic bombs formed by explosive eruption of large masses of lava into the air, where they, quickly cool, with escape of little of the contained water, exceptt perhaps for a hollow interior. Since they cool in layers they have an onion-type structure and a pearly luster from interference of light between the. layers, which is' the origin of the name "perlite." Perlite may occur in intruded flows that have been quickly cooled and partly expanded but retained most of their magmatic water content. Obsidian may be the same lava cooled quickly under conditions that prevented crystallization of feldspars and other minerals, leaving the volcanic glass that may or may not retain all of the original contained water.

Jan 1, 1946

By J. F. Messerly

The purity of three specially prepared samples of benzene was determined with an adiabatic, low-temperature calorimeter with automatic control of shield temperature. Extensive measurements were made on each sample to determine how variations in operating procedures affect melting-point and freezing-point as well as purity data obtained by the calorimetric method. Detailed results of the investigations are presented, and effects of different operating procedures are discussed, together with problems encountered in interpretating experimental results.

Jan 1, 1963

By J. A. Organiscak

Longwall mining technological improvements have provided significant increases in productivity over the last 15 years. Longwall productivity is anticipated to continue to escalate with expanded application of automated equipment. Automation technology that will likely be adopted over the next 5 years is memory cut with shearer initiation of shield movement supervised by a couple of face workers. Operations using this technology will most likely relocate many production workers from the face to the outby gate entries and position several face workers outby the shearer, exposing workers to different health and safety risks. These changing risks are primarily related to worker relocation and expected increased production levels. Workers outby the face will most likely have less dust and noise exposure, but will be exposed to other safety hazards associated with outby equipment movement, materials handling, and gate entry ground movements. The face workers will most likely be exposed to higher respirable dust and noise levels generated by the equipment at elevated production rates. Methane gas emission is also expected to increase with faster mining rates. These operational changes and the control technologies needed to reduce redefined longwall worker hazards at semiautonomous longwall operations require examination to maintain the health and safety of mine workers.

Jan 1, 1996