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By I. Pordea

The materials used for the construction of buildings contain natural radionuclides of the U238 and Th232 series and are ? 50% due to land radioactivity. Another component of natural radioactivity is K40, with ? 40%. The presence of these radiopollutants in the final products (i.e. bricks, concrete) due to body irradiation is by two pathways: external irradiation and internal irradiation. External irradiation is due to gamma radiations emitted by Pb214 (RaB) + Bi214 (RaC) from the U238 series, by Ra228 (Mezothoriu I) + Ac228 (Mezothoriu II) + Tl208 (ThC??) from the Th232 series and by the K40 radionuclide. Internal irradiation is due to inhalation of radon (Rn222) and Rn220 (Tn) plus short life descendents (Po, Pb, Bi), radionuclides which are present in concrete. A fraction from radon present in concrete enters into a house leading to internal irradiation by inhalation. In Romania, the maximum concentration of radon allowed for new buildings is 200 Bq/m3.

Jan 1, 2008

By Bernie W. Martin, Paul MacLeod

The new St. Clair River International Tunnel Project presented unique challenges in planning, permitting and approval. The project straddles the border between the Province of Ontario and the State of Michigan necessitating the review of U.S. approval legislation that has not been used in 60 years. The preparation of an environmental impact report to satisfy the legislative requirements for the Federal laws of the U.S. and Canada as well as the Province of Ontario and the State of Michigan presented a daunting task. In all, over 200 external contacts were made in carrying out the environmental approvals and permitting work. The definition of the alternatives including the NULL option were documented along with the impacts and mitigation measures. A "Modified Delphi" technique, along with other methodologies, was used for alternative evaluation and selection. A formal and informal public consultation process was undertaken which involved over forty major presentations and external meetings. A unique alternative to the traditional design, tender, build contracting practice was adopted; The Negotiated Compressed Process (NCP).

Jan 1, 1993

By Hassan Madani

Kushk lead-zinc mine is located in central part of IRAN. The mine is owned by Bafgh Mines Co., which is a nationalized company. Exploration results show that ore occurs in the area that extends for 800m length and 180m depth. The approved, probable and possible reserves of the mine is 900,000 tons, 1,120,000, tons and 1,450,000 tons respectively with average grade of 17.7% zinc and 4.3% lead. The total annual output of the mine all was by underground mining, is in the order of 100. 000 tons. The main entry to the mine is via an inclined shaft with a cross-sectional arp of 8 m2, length of 263m which dips at 20°. The ore is mined mostly by sublevel stopinq method. The major difficulty in ventilating the mine was that related to spontaneous combustion of pyrite, which was more serious in some parts of the mine than others. In order to reduce this risk, a new ventilation system for the mine was designed, using 4 exhusting fans.

Jan 1, 1991

By R. Ciccu

Permeable reactive barriers (PRB) are one of the most promising systems for groundwater remediation. PRB are constructed with the purpose to intercept the contaminated flow and to degrade it as a big reactive filter. The most common type of reactive barriers is realized by excavating a trench and by filling it with a substance able to treat the contaminants dissolved in the water. Another type of PRB is obtained by realizing a line of wells in which chemically active compounds are injected. A new method for barrier construction has been studied at DIGITA?s laboratories. It makes use of the waterjet technology to increase soil permeability and to inject active compounds. This technology is especially suitable in the case of deep contaminated aquifers where traditional construction methods are difficult to apply. The paper describes the experimental apparatus especially designed and constructed and the activities carried out to investigate the relationship between waterjet operative parameters and the penetration of the jet in the soil. In conclusion, on the basis of the experimental results, the economical feasibility of the technique is evaluated.

Jan 1, 2008

By LeEtta M. Shaffner, John R. Marks

The Homestake Gold Mine in Lead, South Dakota, commenced operations in 1876. As is the case with old, deep, continuously developing mines, a ventilation improvement is periodically required to maintain acceptable underground environmental conditions. Recent historical improvements at Homestake include a 5.2m diameter air shaft driven in the 1960's and a 2.1 MWR (580 ton) chilled water plant installed in 1978. By 1983, it became apparent that yet another ventilation upgrade would be needed to keep pace with accelerated development in the deepest mining sections. A study was therefore undertaken to project ventilation requirements for the next ten years and to select the method(s) most suitable to meet those requirements. The study called for a two-phase approach in which air flow and air conditioning were carefully balanced. Phase I, the installation of a new 2240 kW surface fan and several underground circuit changes, was completed in 1986. This paper describes Phase 11: the planning, design, installation and initial performance of the air-conditioning portion of the upgrade.

Jan 1, 1989

In the early days of minimal environmental protection awareness and unreasoning economy development pressures, little attention was paid to growing environmental concerns in Fuxin colliery, especially the air pollution problem due to the long term mining activities. In order to determine air quality concentration levels, a new technique for synthetic assessment of ambient air quality by using the extension of matter-element method is proposed in this paper. The air pollutants data such as Sulphur Dioxide (SO2), Carbon Monoxide (CO), Nitrogen Oxides (NOx), Total Suspended Particulates (TSP), Particulate Matter (PM10), and dustfall collected at four different air quality monitoring stations located in four districts of Fuxin colliery is used. The results obtained indicate that TSP, PM10, dustfall and SO2 are the predominant pollutants. Other pollutants such as CO and NOx are also detected in Fuxin colliery. The air pollution comes mainly from industrial emissions, mining activities and the abandoned gangue stockpiles. Compared to those applied to other mathematical assessment methods, it is demonstrated that the extension of matter-element model is quite appropriate for air quality assessment.

Jan 1, 2006

By R. W. Hutson

One of the fundamental precepts of experimentation is the isolation of a single variable to quantify its individual effect. Unfortunately, the variability of natural rock joints has frustrated such isolation. This variability and the high cost of securing a large member of natural joints has lead to increasing experimental dependence on stage shearing, artificial tension fractures and/or model materials. The new apparatus described herein allows for the first time replication of real joints with field scale asperities. It employs a diamond band-saw blade with computer controlled feed table to cut joints with high precision. The feed system is capable of placement to tolerances similar to those of a high quality computer plotter. The accompanying software allows the table to cut any desired joint shape (repeating or non-repeating) within certain, over-all size limitations. Resulting joint surface dimensions and roughness as well as shear resistance indicates that the joint surfaces are reproduced with a precision similar to that possible for the control of other experimental variables such as normal and shear forces.

Jan 1, 1986

By S. Svoronos, B. Moudgil, R. Stana, A. El-Midany

Due to their similar surface properties, it is not always easy to separate carbonate minerals from other salt type minerals by froth flotation. A particular example is the difficulty of separating dolomite impunities from phosphate minerals. Such challenging fundamental and practical problems have inspired several research efforts in various laboratories around the globe to find methods for economically removing the dolomite. However, a universal and cost effective process is not in commercial use. In this paper, a new process for separation of carbonate minerals (dolomite or calate) from other associated minerals is presented. Differential solubility of carbonates in slightly acidic solution is utilized to generate micro GO, bubbles at the carbonate mineral/ water interface. Particle (e.g., dolomite)/ bubble aggregates float to the surface leaving phosphate concentrate with low MgO content. Interestingly, up to 6.0 mm particles can be floated by such micro bubble/particle aggregates. Different sutface-active agents were tested to stabilize the bubbles. Results of these tests are presented and the mechanisms involved are discussed.

Jan 1, 2005

By M. S. Janssen

The development of a design equation for, and the testing of, a constant- flow airlift pump IS described. The predictions of the new airlift model agree with the results of experiments carried out using riser diameters between 0.025 and 0.300 m, submergence depths between 5 and 10 m, suspension densities between 1000 and 1650 kg/m3, and a solids dg of 70 to 100µm. The predictions o the model also agree with data from the literature for submergence depths that reached 130 m. This airlift model was employed to simulate the pulp flow through a series of tanks, each of which was fitted with an airlift pump to transfer the suspension to the next tank. Particular attention was paid to the riser diameter, submergence of the airlift pump, and control of the air supply to the airlift pump during the simulated operation of a series of tanks. The results of the simulation highlight some design parameters that could affect the efficiency and operation of a plant that employs airlift pumps to transfer suspensions.

Jan 1, 1989

By O. A. Bascur

In recent years, metal-producing companies have increased their investment in automation and technological innovation, embracing new opportunities to enable transformational change. Transformation to a digital plant can fundamentally revolutionize how industrial complexes operate. The abundant and growing quantity of real-time data and events collected in the grinding and flotation circuits in a mineral processing plant can be used to solve operational issues and optimize plant performance. A grade recovery model is used to identify the best operating conditions in real time. A strategy for increasing the value of instrumentation in current plants is reviewed. An optimal Gaudin size distribution model provides augmented information from traditional sensors to find the optimal grind cut size to reduce metal losses in the flotation circuits. Sensors in flotation circuits enable an estimate of the recovery and determination of the optimal froth depth and aeration using an air hold up flotation model. A strategy of classifying data for online generation of insights to using operational intelligence tools is described. The implementation of a recovery/grind strategy with industrial examples in nonferrous mineral processing is presented.

By W. S. Urbanski, A. L. Devernoe, M. S. Walker

Theory and practice are described for a new processing method capable of precise mineral separations based primarily on differences in particle specific gravities at specific gravity split points from 1.5 to 21.0 and beyond. Separations are analogous to those achieved using rotating heavy media, except that the effective specific gravity of the fluid is created magnetically using a relatively dilute, low-viscosity, water-based magnetic fluid. Results reported here for a large, laboratory flow-through separator include: 1) 99% grade with 97% recovery in single pass separation of a suite of heavy minerals from quartz at I0 kg/h, 14 tph/rm2 of duct cross section, 2) 90% grade and recovery in single-pass separation of mixtures of sand-size, non-magnetic rutile (4.23 specific gravity) and zircon (4.72 specific gravity) at throughputs of 35 kg/h, 47 tph/rm2 of duct cross section, 3) partition curves having Ep90-10 transition widths 5% or less of mineral specific gravities, and 4) essential confirmation of the theory.

Jan 1, 1991

By R. Mohan Srivastava

In any operating mine, especially in precious metals operations, immediate improvements in profitability m readily achievable through more effective grade control. Just as the oil industry has come to recognize that enhanced oil recovery (EOR) in existing oil fields yields a higher return on investment than exploring for new oil, so too must the mining industry recognize the benefits of enhanced metal recovery (EMR). Current grade control practices are generally dismal. The very word "control" suggests a willingness to make the best of a bad situation -- as in "damage control" or "disease control" -- and a failure to perceive the opportunities for improved profit. While damage and disease can merely be controlled, success and improved profit can be engineered. This paper presents one approach to enhanced metal recovery. It shows how existing methods can be used to address the issue of ore/waste discrimination. The following sections outline the problem, describe the current state of the practice of grade control, propose an alternative approach and. illustrate the application of the proposed alternative to actual blasthole data from an operating gold mine.

Jan 1, 1992

By Gary L. Simmons

Over the past several years, Newmont Gold Company (previously Santa Fe Pacific Gold Corporation) developed a new technology for the flotation of refractory auriferous sulfide minerals which is referred to as the N2TEC flotation process. Starting in April 1997, the first commercial flotation plant utilizing N2TEC technology was successfully commissioned at the Lone Tree Mine near Valmy, Nevada. The Lone Tree flotation plant was designed to process 4,085 mt/d of ore producing 494 mt/d of sulfide concentrate. A flotation tails leach CIP circuit was added to recover cyanide-soluble gold from the flotation tails. A portion of the flotation concentrate is blended with whole ore feed to the Lone Tree autoclave, up to the limit imposed by the current oxygen plant capacity. The remainder of the concentrate is shipped to either the Twin Creeks autoclaves or the Carlin roaster for subsequent oxidation and gold extraction. This paper discusses the results achieved in the commercial flotation plant compared to pilot plant testing and engineering design flotation modeling. Capital and operating cost information are also presented.

Jan 1, 1999

By E. A. Rychkun

Introduction Minicomputers have been gaining acceptance in mining. Low cost interactive processing and plotting can now be controlled by geologists or engineers needing rapid solutions and specialized mining software in formats that allow noncomputer personnel to readily interact with computer processes. User-oriented programs maximize the use of interactive display features and graphics, as shown by the HP9845 minicomputer, a unit with portability, processing power, graphics capabilities, capacity, and peripherals such as plotters, digitizers, disk drives, and printers. Application Coal exploration projects require that much effort be spent determining coal volumes within trial pit limits. This determines a prospect's viability and potential. Adapting volume calculations to a computer has been limited, since it was difficult to create reasonable representations of complex coal seam geometry with a digital process. So many of the simple mechanical procedures needed to produce pit reserves are still performed manually by geologists and engineers. But with new minicomputers and their interactive graphics, it is now practical to accurately model complex structures without tedious calculations. GEOSEM (Geomin Seam Oriented Exploration System) is a computer system designed to analyze coal prospects. The system shows how a coal prospect, with complex geology, can be quickly analyzed, modeled, displayed, and evaluated for mineable reserves. Its interactive graphics allow rapid visual presentation of data, high-speed tabular reports, and precision plotting. The system is most effective when used by a geologist or engineer who selects the required operations and specifies relevant parameters via screen and keyboard interaction. Rolling Hills The Rolling Hills prospect represents a typical Rocky Mountain coal deposit. Enough geological interpretation has been done to show a complex system of block faulting with coal seams following synclines of stratified lithologies. With the completion of initial drill hole exploration, questions arose concerning coal volumes and strip ratios involved with various pit limits. Quality information had been gathered on the coal intercepts. It was decided that coal vol¬umes and pit designs were of prime importance. The objective was to enter and display data, create a computer model based on interpretation, develop pit designs, compute seam/ waste volumes, and report various contents. The project, begun by entering data in the GEOSEM system, was completed in several days. Data Entry For modeling, the prime information was seam identity and drill hole intercept. Other information-rock type, Btu rating, and percent of ash, sulfur, and moisture-was also available. It, too, was entered into the data base through the computer keyboard and then reported, verified, and corrected. Various reports can be produced, according to user specified sort parameters. For example, from an analysis of available data, only 14 intercepts could be found with Btu value greater than 8000 and sulfur content less than 0.4%. The sort option can also be used prior to entry into the analysis routines. Data Analysis Though the objective was to create a seam model and compute reserves, it became necessary to project quality information into unsampled areas. Statistical analysis was then war-ranted. A typical analysis correlated the lack of relationship between percentage of ash and Btu. Although histograms were also produced, these typified a lack of samples and "ragged" distributions. A geostatistical analysis was also applied, showing the results of computing a 2-D variogram on the largest coal seam. Results showed an average range of 18 m, with a poorly defined variogram. Data Display and Drafting Scaled plans and sections were required so seam locations could be compared to hand drawn interpretations and drill coordinates verified. At the same time, topography could be interpolated from collar elevations to determine whether surface control points were needed for better definition. In addition, a new set of 50 final-scale drawings were required, showing new drilling information. By using the computer screen as a "scratch pad" device, various sections were displayed and then plotted on a drum plotter at the desired scale for overlay on original sections. Both lithology and seam name were plotted for the five main sections. Since the coal seams were striking north-south, sec-

Jan 11, 1981

By J. M. Mutmansky

The usual method employed to determine the direction of flow in a connecting airway in advance is to conduct a survey between the two existing nodes being connected by means of the new airway. It is then assumed that airflow will take place from the node with higher pressure to the node with lower pressure. The purpose of this paper is to examine this direction-of-flow problem --using properties of the system characteristic curve for a two-terminal network --and specify some conditions that ensure that flow will take from the higher-pressure node to the lower-pressure node. It is concluded that the only requirement is that all characteristic curves of fans in the network should be strictly decreasing. Five numerical examples illustrate some important properties of the direction-of-flow problem.

Jan 1, 1999

By W. Linwood Haden

Fullers earth has been mined since about 1920 in southwest Georgia and the adjoining area of Florida. In 1935, the mineral was named "attapulgite" after the source of a sample near the town of Attapulgus, Decatur County, Georgia. Mining and processing of the clay was described in a 1930 publication1 at a time when petroleum refiners were the major users. In the years since then, the uses and users of attapulgite have multiplied, and both mining methods and processing methods have been changed to optimize the clay for the new uses. A comprehensive review of the properties and applications of attapulgite 2 has been published. Only a brief review will be given here to explain the properties being sought and to show how these properties are optimized by mining and processing practices.

Jan 1, 1972

By R. Torbin

The degree to Which automation/remote control/robotics has been utilized in the mining industry is far less compared to general industry because of several factors. These factors include the adverse working environment, the difficult work operations, and the generally lower incentive for capital investments in new mining equipment. Foster-Killer has been actively involved in the development of advanced mining and underground construction equipment. This equipment is designed to be remotely operated to improve both productivity and worker safety. Many of these machines employ advanced electronics and robotic features. Other types of Foster-Miller developed robots will also be described Which could be applied to special mining problems. The types of machines that will be discussed include the following: remote shaft lining/placement. remote excavation/mining operations, automated conveyor system, and robotic surveillance.

Jan 1, 1989

By T. M. Gurr

It is estimated that in excess of one-half million chemicals are used throughout the American workplace. Hundreds of new chemicals are also being introduced into the workplace annually. Exposure to some of these chemicals can be harmful to workers and to the environment. The Occupational Safety and Health Administration (OSHA) estimates that approximately 25% of the U. S. labor force or approximately 25 million workers are exposed to one or more chemical hazards each year. OSHA has determined that this poses a serious problem for workers exposed to such chemicals. Chemical exposure may cause safety and health problems. Health problems can include a cause or contribution to heart ailments, kidney and lung damage, sterility, cancer, burns, and rashes. Safety hazards can include the potential to cause fires and explosions and other serious accidents.

Jan 1, 1989

By Feng Dingwu, Chen Jin, Sun Zhongyuan, Peng Shiying

The recent development of rare-earth permanent magnets has impacted the field of magnetic separation. The permanent magnets technology led to the advent of various magnetic separators particularly designed for application in mineral processing. In this paper, a new type of rare-earth PHGMS possessing a higher magnetic field strength in the working zone was developed using finite element analysis techniques. The NdFeB permanent magnets used had properties of 38 MGOe stored energy, and magnetic material flux levels exceed 1.2 T, The combination of scientific and engineering design and suitable matrices can offer an effective separation of industrial minerals, such as kaolin, feldspar, etc. Compared with conventional high intensity electromagnetic separators, the equipment can reduce electrical energy over 80% with lower operation and maintenance costs, and less installation space.

Jan 1, 1995

The 1996 Arizona Conference was held in Tucson on Dec. 8 and 9. Attendance was 648, a 12% increase from the 1995 conference. The annual conference is organized by the Arizona Conference Board of Directors, representing SME sections from throughout Arizona and adjacent areas. In addition to those representing mining and processing operations in the Arizona region, the meeting was well attended by interested parties from throughout North America. These included vendors, consultants, academia, research organizations and corporate management. The technical program highlighted the meeting. It consisted of a keynote address and morning and afternoon technical sessions. In the technical sessions, 23 papers were presented by the mining, hydrometallurgical, smelting, geology and mineral-processing divisions. The conference was then capped by a banquet that included a talk by a noted economist. Keynote address The program was kicked off by a keynote address titled "Forecasting for the 105th Congress," by Rep. John Shadegg (R-AZ). He was elected to Arizona's Fourth Congressional District in 1994. Shadegg serves on the House Budget Committee, the Resources Committee and the watchdog Government Reform Committee. He stressed the familiar conservative positions of reducing government spending, balancing the budget and states rights. As a member of the House Resources Committee, Shadegg stated his support for the mining industry. Technical sessions Mining division. Two of the five presentations described developments at two Arizona mining operations. T.J. Swendseid of Phelps Dodge presented a paper titled "New developments at Morenci" and P. Garretson of BHP presented a paper titled "Startup of the Robinson Project." Morenci continues to expand its operation and recently broke records for production. Other developments at Morenci included the completion of a 600-m (2,000-ft) drainage tunnel and stockpile rehandling. In addition, Phelps Dodge moved Morenci's crusher plant. It was completely disassembled and reassembled in just eight days. Another interesting presentation was "Predictive maintenance techniques for large electric shovels at Cyprus Sierrita," presented by T. Ritzel of Cyprus Amax. The presentation described high-technology methods for predicting maintenance problems. These methods included vibration analysis, ultrasonic detection, infrared thermography, electrical measurements and tribology (the science of lubricant evaluation). The benefits of these techniques are reduced downtime of the equipment, as was demonstrated in case studies at the mine. The other presentations were "Introduction to NOSA 5-star safety program," by R. McKinnon, BHP Copper North America, and "A new design guideline for mine sealing," by K. Fuenkajorn, Rock Engineering International. Hydrometallurgical division. The hydrometallurgical session consisted of five papers. These included a presentation titled "Recovery of gold and silver using guanidine-based extractants," by M. Vining of Henkel Corp., Tucson, AZ. In this presentation, guanidine-based extractants LIX-79 and AURIX resin were introduced. LIX-79 was shown to have applications in copper-gold and high silver ores. In ammonia-cyanide leaching, AURIX was shown to be more selective in CIL vs. RIL comparisons. Other papers in the hydrometallurgical division included "Application of cobalt in the copper industry," by J. Hawke, OMG Apex Inc.; "Series parallel conversions and production gains at Cyprus Miami Mining's dump leach and solvent extraction operation," by E. Bilson of Cyprus Amax; "Lead alloy anode corrosion at the San Manuel SXEW tankhouse," by W .M. Gort of BHP Copper and "Hydrometallurgical treatment of copper refinery slimes," by B.C. Wesstrom of Phelps Dodge. Smelting division. Three papers were presented in the smelting division session. These included updates and reports on improvements at the Hayden, Hidalgo and BHP San Manuel smelters. For example, W.A. Dutton of Phelps Dodge presented "Recent improvements at the Hidalgo Smelter." These changes were aimed at reducing environmental emissions and increasing production. They included modifications to the fugitive-gas collection system to reduce particulate emissions, rubber lining the acid plant scrubbers to reduce corrosion and the installation of a cold lime softening system for water treatment. Equally interesting papers were presented by D. Norton of Asarco, Hayden, AZ, in a paper titled "Update of the Hayden smelter process," and by D. Jones of BHP Copper, San Manuel, AZ, in a paper titled "Update on first campaign of the BHP San Manuel Copper." Geology division. The session began with a paper that outlined the progress of an exploration project in South America. "The Pierina exploration project, Ancash Province, Peru" was presented by J.D. Lowell, Lowell Mineral Exploration, Rio Rico, AZ. Another paper was then presented on a copper deposit in Grant County, New Mexico. "Zonation of supergene copper minerals at Hanover Mountain, Grant

Jan 1, 1997