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By S. Brummelkamp, G. Van Weert

Separation of minerals by shape has received little attention, since minerals normally do not break into different shapes during crushing and grinding. However, comminution of consumer wastes generates opportunities for novel separations based on particle shape. For instance, ductile plastics are broken into longer curved shapes, whereas brittle plastics yield angular particles. Using spouting beds for particle separation in water requires controlling the spout's instability. The preferred geometry for such redesigned spouting beds is reported. Plastic cylinders, discs and spheres were separated as a function of rising water velocity and amount of particles in the system. By using 5 mm particles, differences in settling behavior could be video recorded.

Jan 1, 1999

Oil sands processing generates huge volumes of slurry, known as tailings, that is being stored in tailings ponds. The volume of produced tailings is a very important factor in oil sands surface mine planning, because the available area for dam construction is limited to the lease areas. On the other hand, oil sands operators cannot leave mine sites without reclaiming the tailings ponds. Since most of the reclamation material is generated in either oil sands mining or processing, it is reasonable to include reclamation material requirement as part of long-term mine planning. In this paper, an integrated optimization framework is proposed to maximize the net present value (NPV) of the produced oil sands, with respect to tailings capacity constraints and reclamation material requirements. A mixed integer linear programming (MILP) model is developed to find the optimal solution for long-term mine planning problem. A sample bitumen processing flow sheet is used to formulate the volume of produced tailings, based on Clark hot water extraction method. To verify the proposed model, it is coded in Matlab and run using CPLEX. Run results for real-case oil sands dataset show that the optimal production schedule meets material requirements for reclamation, tailings volume is within tailings capacity range in all periods and the production schedule follows the predetermined horizontal direction.

Feb 27, 2013

By B. Cousins

Copper, nickel, zinc and other ?penalty? metals are found with gold together in nature, and have a similar chemical affinity for cyanide used in leaching operations4. As a result, solutions that come from the heap leach pads contain a significant concentration of penalty metals along with the desired gold. In solution, gold and cyanide form the complex Au(CN)2- that is readily adsorbed onto activated carbon. Penalty metals as individual metal ions also load onto activated carbon and, depending on the concentration of cyanide and the pH of the solution, can form various cyanide complexes. Some of these complexes can also load onto carbon while some are significantly inhibited from loading. Copper, for example, can form the dicyanide complex Cu(CN)2-, the tricyanide complex Cu(CN)32-, and the tetracyanide complex Cu(CN)43-. At a low pH and a low concentration of cyanide, the dicyanide complex predominates. At a higher pH and a higher concentration of cyanide, the tetracyanide complex predominates. Without excess cyanide, however, individual copper ions can remain present. Activated carbon is used in gold extraction because it is highly selective for gold and less so for other metals, such as copper3. However, copper has the ability to adsorb (?load?) onto activated carbon and block the adsorption of gold when it is in the dicyanide form and in a high enough concentration. When copper is in the tetracyanide form, copper loading is significantly inhibited, allowing for the maximum gold recovery. In order to ensure the tetracyanide complex is formed, a combination of both available cyanide and elevated pH must be present. In the South Area of Newmont Mining Corporation?s Gold Quarry mine in Carlin, Nevada, copper and nickel loading becomes a problem when certain acid generating zones of the heap are leached. Copper, nickel, zinc and other penalty metals become leachable and the lower pH uses up more of the cyanide and creates carbon loading conditions for the metals. This decreases the carbon?s ability to extract the gold from solution, decreasing the recovery and increasing the concentration of gold in the barren solution that leaves the carbon columns. In this study, operational data from March through to May of 2007 is presented to show how Newmont developed a quick fix to lower pH and elevated metal concentrations that were causing low gold loadings on activated carbon at their South Area Leach (SAL) heap leach operations. Laboratory tested were also conducted to examine the chemical kinetics of metal loading and the individual effects of increased cyanide concentrations. THEORY Copper I ions form four different complexes with cyanide in solution: the monocyanide species CuCN, the dicyanide species Cu(CN)2-, the tricyanide species Cu(CN)32-, and the tetracyanide species Cu(CN)43-. The species are formed from the following reactions: [Cu)(?+-+ K1 (1) Cu ß2 (2) --+?+23)(3CNCuCNCu ß3 (3) --+?+34)(4CNCuCNCu ß4 (4) ] where K1 equals 1019.50, ß2 equals 1024.03, ß3 equals 1028.65, and ß4 equals 1030.35. Along with these complexing reactions, hydrogen cyanide and water also dissociate in solution, as per the following reactions: [H?+-+ KH (5) OHOHH2?+-+ KW (6)] where KH has a value of 109.24 and KW has a 1014 value2. These six chemical equations compete with each other, with domination of one over the others dependent on the CN- and H+ concentrations. Each complex also has different properties when it comes to its loading behavior on activated carbon. The dicyanide copper complex and the monocyanide copper complex have an affinity for adsorption onto activated carbon that is greater than the affinity of gold cyanide for adsorption. They also have a lower solubility in water, which enhances adsorption. The tricyanide copper complex and the tetracyanide copper complex are water soluble and have an affinity for loading adsorption on activated carbon that is less than the affinity of gold cyanide for loading adsorption1. There are three prime reasons for this phenomenon. First, the extra cyanides mask the metal ion more, which blocks the main adsorption characteristic of the complex. Second, the complexes are also larger, making it harder to physically fit into the active sites on the carbon. This helps make the latter two complexes kinetically inhibited from adsorption, freeing carbon active site to load with gold cyanide complexes. Third, it is also important to consider the expressions of the mass and charge balance. These balances describe all the overall concentration of copper and cyanide in solution, as well as marking overall charges of the ions in solution4. This is important because significantly changing the charge from positive/neutral to more negative is another reason for activated carbon to reject adsorbing the higher cyanide complexes. The speciation of copper and other penalty metal cyanide complexes in solution is dependent on the pH. At lower pH values, increased hydrogen ions (H+) can out-compete metals for cyanide ions. Lower free cyanide in the system leads to the lower cyanide species of copper cyanide predominating, with a noticeable concentration of the free metal, monocyanide and dicyanide species of copper cyanide. At higher pH values, hydrogen ions are significantly reduced, reducing the kinetics of HCN formation. More free cyanide remains in the system, allowing for more complexing. With this higher amount of cyanide in the system, the tetracyanide species of copper cyanide predominates, also with a noticeable concentration of the tricyanide species of copper cyanide. Higher copper concentrations, however, require more

Jan 1, 2009

By W. M. Hart

The remote face loading and entry convergence monitoring systems, employed at some of the Cyprus Amax's underground coal mines, have been able to continuously record changes in face shield resistance across and entry convergence ahead of the longwall face at any moment during longwall mining. The instrumental data obtained from these systems plus in-situ observations during the mining operation can help us better understand the mechanism of overburden strata movement above a longwall face and verify the effectiveness of the current face and entry supports. This paper describes the functions of both the face and entry monitoring systems, and discusses our findings and the issues related to successful ground control for longwall mining.

Jan 1, 1996

Tunnel damage from explosion and earthquake excitation is correlated with strain and particle motions. Critical strains and motions are then correlated with focal distance, which is so small that permanent strains are highly likely. The shaking process is then numerically modeled to investigate the effects of excitation frequency and joint orientation. The models confirm that near cavern blocks slide intermittently only at relatively high particle velocities during periods of low joint normal stress. Larger displacements occur with relatively small shear wave lengths or relatively high frequencies. Variation in joint orientation and rock mass dilation result in changes in displacement.

Jan 1, 1985

By Phil Pennington, D. Jack Adams

Mining and processing of minerals, metals, and fossil fuels can release selenium and arsenic into wastewaters. Both selenium and arsenic are difficult to remove to levels that meet current drinking water and discharge criteria. These metalloids can be used as electron acceptors by microorganisms transforming them back to reduced states, thus removing or stabilizing them. Bioremediation cost effectiveness will be discussed in terms of site information required, microbial populations, co-contaminants, pH, redox, and nutrients. Full-scale, economical ex situ and in situ biotreatments are possible and can produce 1,000’s of times less sludge than conventional precipitation technologies.

Jan 1, 2005

By Roshan B. Bhappu

Integrating a research and development department into an engineering company's corporate structure can be rewarding to the engineering division, the R&D group, and, most of all, the company's clients. Actually, the R&D department is a logical extension of the conventional processing group within an engineering organization-but the R&D group provides services as needed to the engineering department while it is carrying out regular testing, pilot plant, and preliminary feasibility studies. Backup Services Provided With an R&D group, the engineering division does not need a process engineering group as such. The R&D group provides project backup services for feasibility studies, preliminary and detailed engineering, construction, and startup. The R&D group, in turn, benefits from its close association with project engineers, draftsmen, estimators, and computer capabilities in the engineering division. The client also benefits from the arrangement because R&D and engineering skills are available to both departments on an as-needed basis without standby eost. To handle the integrated responsibility of R&D projects, as well as conceptual design and preliminary feasibility studies, the R&D staff must be carefully selected. These research engineers should: • have a good background in plant practice as a mill superintendent or chief metallurgist; • be capable of organizing and supervising a testing program or a pilot plant campaign; •be innovative and willing to accept new ideas and concepts; • be able to translate lab test results into a workable flowsheet through sound conceptual design and feasibility studies; and •be able to communicate with clients. In short, the R&D engineer must be a jack of all process-engineering trades to successfully take a project from concept to operating reality. Engineers in a metallurgical R&D organization should have experience in mining and processing all types of

Jan 10, 1980

By C. A. Young, R. G. Robins, E. J. Dahlgren

The formation of copper thio-complexes in sulfide solutions has been recognized for many years and the measured solubilities of certain copper sulfide minerals attributed to these complexes. Attempts to model this system have proposed either copper(I) or copper(II) thio-complexes, and these have been incorporated into computer programs for generating stability diagrams for the copper-sulfur-water system in order to delineate the region where the reductive dissolution of copper sulfide minerals is likely. In this paper it is proposed that the dissolution of copper from both ore bodies and sulfide tailings can be explained by the formation of the cupro-thio-complexes under anaerobic conditions. Stability diagrams are presented to depict the region and extent of the solubility.

Jan 1, 2001

Environmental conflict management approaches and procedures have been used to successfully address and resolve a variety of issues, problems, and conflicts related to the extraction of natural resources. Companies in the mining industry have been involved in a range of controversies over planning, siting, permitting, environmental, and enforcement issues. Through the use of conflict resolution case studies, this paper will present approaches and procedures that can help companies and other involved parties to successfully manage and resolve differences in a mutually acceptable manner.

Jan 1, 2000

By G. Krogman, C. Walla, B. Wood

The Gebo Mining District (District) is located in the Bighorn Basin of Wyoming. Commercial underground coal mining began in 1906 with the arrival of the railroad in Thermopolis, which is located approximately 11 miles to the south. Mining in the District ceased by the early 1970’s. In Fall of 1999, Lidstone and Associates, Inc. (LA) and their subcontractors were retained by the Wyoming Abandoned Mine Land Division (WyAML) to perform an inventory of over 500 abandoned mine sites across Wyoming. During the summer of 2000 field inventory, a 30-foot deep headcut (Figure 1) and sink-hole were noted in the West Fork of Sand Draw (WFSD), immediately west of the Town of Gebo. The headcut and sink-hole were located at the culvert outfall associated with a stream crossing of a relatively well traveled county road. Upon further investigation, it appeared that underground mine workings had been exposed at this location. This resulted in a condition whereby water would be conveyed directly into the mine workings during a runoff event. The exposed mine workings as well as stream capture created a very hazardous condition. The WyAML implemented mitigation measures in the summer of 2000 by constructing a temporary stream crossing upstream of the existing failed crossing. To address this hazardous situation as well as a number of other hazards identified in the District during the field inventory, the WyAML retained PHC Reclamation, Inc. (PHC). PHC was directed to perform a field investigation and develop a Reclamation Plan to address all existing abandoned mine hazards in the District. Federal, state, and private parties own lands within the District. Hazards identified during the investigation included an underground mine fire, open adits, open shafts, subsidence, drainage problems, and coal slack. A Report of Investigation (ROI) was submitted to various regulatory agencies that documented the existing conditions and conceptual reclamation plans to remediate the hazardous conditions. After review of the ROI by the US Department of Interior - Bureau of Land Management (BLM) an on-site meeting was conducted. BLM Cultural Resource personnel declined to approve a District reclamation project until a historical overview of the entire District was prepared. Due to the hazardous situation associated with the WFSD stream crossing, Hot Springs County Road and Bridge Department convinced various state and federal regulatory agencies to allow reclamation of the stream crossing to occur. A decision was made to allow reclamation on privately owned lands within the WFSD drainage. This decision limited the amount of channel that could be subjected to reclamation upstream of the crossing to privately owned lands. PHC contracted LA to perform a geologic, geomorphic, hydrologic, and hydraulic investigation of the drainage to assist in the development of a WFSD reclamation plan. LA’s investigation consisted of four parts: Delineate the extent of mine workings in the area; Identify all drainage structures that required mitigation; Survey a series of channel cross-sections and a longitudinal profile of the impacted channel; and, Develop basin hydrology to assist in the design of a stable reclaimed stream channel.

Jan 1, 2006

By D. Sohn

Work accidents have an essential impact on the economy of a country and in final consequence on each company. The main purpose of industrial OHS is to maintain and promote the health of all employees. Healthy working conditions increase efficiency and motivation and safeguard the success of the business against the background of the extremely dynamic processes of change. Maintaining and promoting the health of all employees, weather in operation, administration or on the mining site, has become therefore not only an ethical requirement but also an economic must. Creating a suitable working environment for people today entails much more than just preventing accidents and work-related illnesses. It is important to be proactive in establishing an even better culture of prevention and to convince everyone, workers and managers alike, of its importance. Especially in the age of rapid changes and above all in view of global competition we are more dependent than ever on healthy, enthusiastic, competent and creative employees. OHS provides you with the necessary competitive edge.

Jan 1, 2007

By Colin Connors

Cemented rockfill is a key component in the success of underground mining at the Jerritt Canyon Joint Venture. The Murray and SSX mines are characterized by relatively poor rock mass quality, and the goal of complete mining recovery makes maintaining a high quality backfill product vital to the safety and efficiency of the mining operations. A large portion of the ore production from the Murray mine originates from drifting under backfill. Modelling studies performed to investigate induced loading of the backfill were used to develop engineering specifications for the backfill material. Operations history has shown an almost 100 percent stability of the backfill when mining is carried out beneath it. The volume of backfill required each year (approximately 300,000 tons) and the required cement content have a significant impact on the total mining costs. The potential for cost savings associated with higher replacement of cement with Type "C" fly ash and the implementation of a backfill strength management strategy were therefore evaluated.

Jan 1, 2001

By S. Möllerherm, E. Drüppel

"The development of indicators to assess the sustainability of mineral raw materials operations is amajor task with respect to its actuality and difficulty. This holds true even more when dealing withenvironmental indicators.The use of existing environmental indicators in the mineral raw materials industry leads to false orat least distorted results. Therefore the Institute of Mining Engineering I from the RWTH AachenUniversity developed indicators and an assessment system for the mineral raw materials industryon operation, company and sector level on behalf of the Federal Ministry of Economics and Labour(Bundesministerium für Wirtschaft und Arbeit, BMWA) and the Federal Institute for Geosciencesand Natural Resources (Bundesanstalt für Geowissenschaften und Rohstoffe, BGR).In total 30 indicators were defined and designed to assess the performance of the mineral rawmaterials industry in terms of sustainable development, 10 indicators for each pillar (economical,ecological and social pillar).The following paper describes some of the results focussing on the development of environmentalindicators. These had to be adapted or completely new designed in order to match the specificcharacteristics of the mineral raw materials industry."

Jan 1, 2005

By A. B. Cecala

Enclosed cabs have been used on surface mining equipment for many years to protect equipment operators from health and safety hazards. The surface mining and quarrying process is a highly mechanized process that generates large quantities of respirable dust. Due to economic factors, more older mining equipment is being used today than in years past. With this older equipment, it is common to observe deterioration of many components on the enclosed cabs which greatly reduce their protection effectiveness. NIOSH has performed a number of different field studies, as well as a comprehensive laboratory study evaluating various factors and parameters regarding enclosed cabs. NIOSH has recently completed a cooperative research effort with Sy-Klone International and Vulcan Materials Company to evaluate the effectiveness of a newly designed uni-directional filtration and pressurization system that brings all the clean filtered air in at the roof of the cab and extracts all recirculated air near the floor. This design provides the highest air quality to the equipment operator. Testing on this new system showed an almost 10-fold reduction in respirable dust inside the enclosed cab. The uni-directional design is easy to incorporate and should be considered for all new and retrofit systems in surface mining equipment.

Jan 1, 2009

By K. Oraee

Proven and probable coal reserves in Iran are estimated to be in excess of 5 Billion tons while the annual coal production is a mere 2 Million tons. Underdevelopment of the industry has proved higher production levels to be impossible, despite growing demand for energy supplies. The existences of numerous legislation are thought to have a detrimental effect on coal mining activities to the extent that some business entities have become uneconomical in many areas. This paper provides an analysis of the prevailing mining laws, policy making, legal frameworks and obstacles. It also outlines some other obstacles enshrined in the law and also highlights areas where foreign direct investment should be encouraged. The costs of lost opportunities are then estimated. The paper concludes by demonstrating that deregulations, amendments and in some cases complete abolishment of the incumbent legislations governing the coal mining industry will greatly enhance development of the industry. The analysis provided in this paper together with the results obtained, can prove useful to macro-economic policy makers both at local and national levels.

Feb 27, 2013

By F. Turatti

Rio Tinto is one of the world's largest mining companies, involved in every stage of metal and mineral production, producing aluminium, copper, diamonds, coal, iron ore, uranium, gold and industrial minerals. Operations are in more than 50 countries in multiple continents and vary in location between large urban centres, regional industrial complexes and remote regions. A risk-based strategy was developed by Rio Tinto to manage its air quality impacts on a global scale. The strategy consists of three objectives ? improving air quality performance, developing industry leading practices and engaging and influencing in air issues. This paper discusses three major successes achieved this approach. Firstly, how air shed resources are managed in constrained air sheds. Secondly, how financial modelling is used to value air quality constraints, and thirdly, how a rigorous and comprehensive e-learning course is used to improve the overall level of air management knowledge of Rio Tinto?s environment managers.

Feb 27, 2013

By J. P. Baur

The sensitivity of radiochemical techniques makes possible the study of the initial stage sulfuric acid leaching kinetics of chalcopyrite and other copper sulfide minerals. High-grade Transvaal chalcopyrite was neutron irradiated in a TRIGA reactor to produce radioisotopes copper-64, iron-59, and sulfur-35. Dissolution rates were measured in the time interval zero to 60 minutes during which time significant anomalies were observed. First, an initial period of rapid dissolution lasting a few minutes; second, an arrest or "plateau" region usually lasting from 6 to 10 minutes; third, a second period of dissolution of lesser rate than the first. The effect of solution variables such as pH, oxygen partial pressure, and ferric ion concentration at different temperatures were measured. The initial rate data were correlated by considering the rapid reaction to be due to the dissolution of surface oxidation products or the formation of an iron depleted surface layer. The data for the second slower reaction have been explained to be due

Jan 1, 1972

By H. -J. Langhoff

"The paper describes not a result, but a starting point to implement sustainable development to a region characterized by a typical down river landscape, agriculture, and extractive industry. The NaturFreizeitNiederrhein GmbH (NFN) is a private company with associates from administrative bodies, the local mining companies and multiple representatives of environmental protection groups (local and national), tourism organizations, cultural societies and also aquatic sport and fishing clubs. Center of the concept is the "NFN Lake District." The development concept aims to provide the agricultural industry with alternative means of income, while protecting wildlife and the ecological balance as well as preserving the social und cultural system and enhance the safety against flooding from the river Rhine. The mining industry contributes their coordination of obligation concerning reclamation and recultivation of the already existing individual projects. While designing the landscape components and establishing the infrastructure for the different tasks, the production of gravel and sand is yield as a by product. The result is a long term perspective for region and industry."

Jan 1, 2005

Modern coal cleaning technologies have allowed coal preparation facilities to become quite efficient at removing sulfur compounds, waste rock and low grade coals from run of mine coal. Up to 50% of the raw mined coal stream may end up as refuse, particularly when the coal originates from longwall mining operations, or is high in partings, rock and impurities. The refuse materials vary from coarse materials removed by physical screening to very fine materials removed by floatation and density separation processes. Coal refuse piles are also known by a variety of other names including "waste dumps", "gob piles" and "slate dumps". The potential hazards of improperly reclaimed refuse include contamination of surface and groundwaters by acidic leachates and runoff, erosion and sedimentation into nearby watersheds, spontaneous combustion, disturbance of topsoil borrow areas, and damage from landslides should large slope failures occur. Many of these problems have been particularly acute for abandoned refuse piles, and modern regulations attempt to minimize the environmental impact of coal refuse disposal operations.

Jan 1, 1993

By Samuel W. Woods

The Tacoma, Washington plant is one of six plants in the United States Gypsum Company's Acoustical and Mineral Fiber Division. The Tacoma facility was acquired in 1959 along with six other mineral wool plants from the American Rock Wool Company. Originally, the Tacoma plant was built as a carbide plant during the Second World War and after that was converted and operated as a mineral wool plant by several insulation companies. Through these early years, the use of raw materials at Tacoma consisted primarily of slags along with small percentages and various combinations of silica (in various forms such as gravel), limestone and basalt. These raw materials were melted in cupolas using coke as the heat source. Raw material usage and types as well as mineral wool production methods and equipment remained without major changes for many years.

Jan 1, 1983