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By Irwin R. Higgins, Richard S. Dennis

Acid recovery employs ion exchange resin as an adsorption media for the separation of inorganic acids from mixtures of acids and their metallic salts. This technology has been used to treat spent pickling and plating liquors to recover acid for reuse in the bath and to reduce waste acid neutralization costs. Acid recovery can also be used for electrolyte treatment to facilitate valuable metal recovery and to improve product quality. Conventional fixed bed ion exchange (I-X) systems are impractical for acid recovery because of complex control design and large resin inventories needed to process strong acid concentrations. TETRA'S CCIX™ continuous I-X contactor has been used successfully in a simple, continuous operating mode to separate acid from its salt. Efficient separation is enhanced by refluxing which allows acid to be produced as a salt-free product at nearly its original strength. Continuous treatment also recovers heat to the bath and improves metal quality due to consistent acid quality.

Jan 1, 1995

By E. Sehner, G. Van Weert

Metal chloride pyrohydrolysis is a fifty year old technology, operating satisfactory in many plants around the world, mainly on ferrous chloride, The capabilities and costs of its two equipment options (spray roaster and fluid bed pyrohydrolysis) are well known. Why is the technology not more widely used in mineral processing, beyond the production of MgO and upgraded TiO2slag? After briefly reviewing chloride vs. sulphate process characteristics and existing plant operations, this paper will discuss pyrohydrolysis options for the mine developer using the processing of ilmenite, siliceous zinc oxides and oxidic nickel / cobalt ores as examples.

Jan 1, 2003

By T. Weimer

Gasification of carbonaceous energy carriers with simultaneousCO2 removal is a new and interesting alternative e.g. ZECA [1],HyPr-Ring [2], AER [3]. In the ZECA process lime supported Hydrogen generation from Methane is a basic process unit and the Hypr-RING process investigates Hydrogen generation from hard coal with addition of lime. Here the main objective is a further development of the AER process. High energetic efficiencies for gasification in the range of 90 % can be achieved if the humidity of the energy carrier is already sufficient for steam reforming reaction. The aim of the overall process is upgrading coals and biomass yielding into three valuable products: • A fuel gas ready for power generation • A CO2gas stream containing >95%, ready for transportation to disposal or chemical fixation • A pre-calcined feed for cement clinkering consisting ofCaO and coal ash Thus power generation and gasification are independent. A promising industrial application is the combination of gasification and cement production. Then only one additional reactor is required and the precalcination mass flows have to be increased.

Jan 1, 2004

By Ben L. Seegmiller

The basic compression-yield concept of roof support for mine roadways requires that the mine roof be placed in a state of compressive stress. The compressive stress may be achieved using a support system such as an entry truss or other specialty truss device. Furthermore, the roof must be allowed to yield, but with great resistance when abutment loads are placed on the roadway. The resisted yielding may be provided using a new yieldable steel prop, known by the trade name, YIPP~. The yieldable steel prop can allow as much as 1.5 m[5 ft] of yield, or up to approximately 40% of the opening height, while providing a resistance in excess of 60 mt[66st]. More than fifteen mining operations including coal, trona and hard rock mines have field tested the YIPPI . Present results indicate that the yieldable prop provides a cost-effective alternative to wood cribs, concrete cribs, hydraulic props and other steel prop supports. The paper describes the YIPPI including its unique principle of operation, its applications and actual field performance.

Jan 1, 1992

By Don C. White

Santa Rosa is a mid-Tertiary, volcanic-hosted, gold-silver deposit. Current proven and probable reserves are 8.9 Mt (9.8 million st) grading 1.5 g/t (0.044 oz/ st) gold, minable by open pit and amenable to heap leaching. It is the product of hydrothermal mineralization along an arcuate segment of a caldera collapse ring fault in a probable maar volcanic setting. This segment was later broken by radial faults. Gold at Santa Rosa occurs principally as electrum, finely disseminated through intermediate tuffs, and associated with pyrite. The nearby Alto de la Mina deposit displays stockwork silica-pyrite-gold in a tectonically and hydrothermally shattered andesite flow. Miocene epithermal mineralization was accompanied by central silicification and pyritization and more distal argillization. An andesite flow cap rock at Santa Rosa played a pivotal role as an upward permeability barrier. Highest gold grades and most intense alteration occur closest to the ring faults and immediately beneath the andesite flow. Supergene alteration effects on the gold distribution are minimal.

Jan 1, 1995

By John A. Herbst, Kuang Y. Lee

Coarse particle size measurement is essential for the automatic control of a size reduction process like crushing or SAG milling in order to achieve optimal process performance. However, the on-line size measurement of coarse material is not easily obtained due to the problems of material handling and sample statistics. A technique based on advanced image analysis and quantitative stereology has been successfully developed and tested in a pilot scale setting. The chord length distribution of coarse particles on a moving conveyor was measured with an image analyzer and then transformed to the mesh size distribution with a stereological model and a special numerical method. Some test results as well as the technique's industrial suitability and limitations of this method are also discussed.

Jan 1, 1992

Open pit optimization and mine design depend upon a realistic estimate of the grade-tonnage dis¬tribution. The estimate should reflect what can be reasonably recovered and processed. The McCoy/Cove operation in central Nevada is a gold and silver mine. Recoverable reserve estimations of gold and silver were made using indicator kriging and the indirect log normal variance correction to construct the grade- tonnage distribution. Optimal pits were generated using this distribution, and the results were compared to the pits generated by ordinary kriging and indicator kriging block mean methods. The results indicate that the proposed method for multimetal recoverable reserve estimation shows an improvement in terms of predicting the recoverable tons and grades. The optimal pits generated from the recoverable resource model are larger than those generated by the ordinary kriging and indicator kriging block mean methods. This model maximizes the overall recovery of the mineral resource.

Jan 1, 1999

By R. Kanniganti, M. Karmis, C. Haycocks

An extensive review of multi-seam under-mining literature was conducted and a data base of case studies was assembled . A critical review of the design principles outlined in this literature resulted in the compilation of specific design criteria for the design of lower seam mines. Analysis of this criteria demonstrated the necessity for a protocol for the design of unsymmetrically loaded pillars. Such a design criteria was developed using finite element methods for a wide range of possible loading conditions. This design criteria can be utilized for underlying pillar design when the loading conditions can be determined. To facilitate using all the under-mining research results by field/planning engineers a Windows TM based software package was developed. This software package contains a multi-seam tutorial, analytical tools and a case history database. The package is user friendly and fully interactive and supported with extensive on-line help. The package contains numerous case studies of multi-seam mines that can be reviewed to facilitate analyses.

Jan 1, 1996

By B. J. Arnold

With the passing of the 1990 Clean Air Act Amendments, many utilities are opting to switch to lower sulfur coal to meet new SO2 emissions requirements. This lower sulfur coal may be from new suppliers or it may be from current suppliers that modify existing cleaning plants or build new plants to produce this higher quality coal. New, sophisticated coal cleaning simulators are useful tools for optimizing cod cleaning circuit operating parameters to maximize the production of clean coal that meets more stringent specifications for SO2 emissions potential. The examples in this paper were developed using the Coal Cleaning Simulator (CCS), running under ASPEN PLUS™, that was developed under a Department of Energy project cosponsored by the Electric Power Research Institute. With advanced sensitivity analysis and optimization features, CCS allows a quick, efficient, cost-effective review of coal cleaning plant performance to meet current production goals and to plan future changes in plant operating parameters or circuitry configurations.

Jan 1, 1995

By B. K. Baird, P. C. Satchwell

The application of cutoffs during and after pit optimization is examined for a lower-grade multi-metallic copper deposit. Pit optimization requires calculation of the net revenue associated with each mining block, incorporating parameters such as metal prices, grades and expected recoveries, mining and processing costs, smelting and refining charges, and penalty element and royalty charges. Sensitivity analysis during pit optimization reveals which of these parameters have a significant effect on the total contained resource tonnage and total contained non-discounted revenue in the optimized pit. The cumulative effect of changing several of the more significant parameters is investigated. Application of a copper cutoff grade to a block inside the optimized pit could result in the less than optimal extraction of the resource. A block with copper grade below the applied cutoff could be economic due to the presence of other metals. Conversely, a higher copper grade block may be sub-economic. The relative merits of applying a copper grade cutoff, “equivalent grade” cutoff and dollar value per ton cutoff to blocks inside the optimum pit are discussed.

Jan 1, 1999

By V. Srajer

Several optimization approaches used by the Canadian mining industry were used to investigate surface coal mining operations in Canada. A computer program was applied to optimize truck/shovel systems and for various analyses. The analyses of eight western Canadian coal mines included investigation of fleet imbalance, under- and over trucking, development of the criteria for automated truck control, comparison study of various haulers and loaders, haulage layout, driving conditions, machine performance, servicing and maintenance policies, etc. Each property investigated supplied background information for the study and cooperated in optimization studies. The truck/shovel system optimization study is demonstrated as a test case to outline procedures and step-by-step instruction for similar applications.

Jan 1, 1989

By F. F. Peng, D. C. Yang, G. Yanief, E. H. Cho

This study deals with carrier flotation of cerium dioxide, a surrogate of plutonium oxide, which is the major contaminant at the Nevada Test Site (NTS). The objective of this study was to determine the feasibility of using carrier flotation for remediation of the site. In this study, a - 200-mesh fraction of pure cerium dioxide was used. Oleic acid was used as the collector, while calcium carbonate was used as the carrier. Mechanical-cell tests were conducted to float the surrogate from a mixture containing uncontaminated NTS soil, both in the absence and presence of the carrier. It was found that the addition of the carrier drastically enhanced the flotation recovery of cerium dioxide. The flotation recovery of the surrogate increased from 34% to 65% by adding only 0.5% calcium carbonate (-150 mesh). The recovery further increased to 95% by adding 10% calcium carbonate. The flotation method utilizing a carrier of calcium carbonate seems to have a high potential for the remediation of the soil contaminated with radionuclides at the NTS.

Jan 1, 1998

By Donald E. Scheck, Syed F. Abbas

Public domain ventilation simulation programs have been well accepted by the mining engineers, but preparing the input and interpreting the results are labor intensive tasks. High performance personal computers and versatile CAD packages provide the means to quickly create the network and display the results. The enhanced simulators work from computerized as-mined map, the projected mine layout and timing maps. Using on screen displays of these maps and the snap-on feature of AutoCAD, the planner designates nodes in the ventilation network, connects them into branches and selects the branch characteristics from a side bar menu. The color coded ventilation network appears with the parameters shown along each branch. The software then calculates the length of airways and computes the branch resistances where needed and converts the input into the required format and passes the data to the Pennsylvania State University or U.S. Bureau of Mines ventilation programs. Output is available in graphical as well as report format. The color coded graphs include pressures at the nodes and flow quantities on the branches. Since the networks come from the mine maps, the ventilation displays are to scale and can be plotted separately or superimposed on the mine maps.

Jan 1, 1991

By M. Balakrishnan, K. A. Natarajan, J. M. Modak, J. S. Gururaj Naik

The ability of various fungal species isolated from gold mines to uptake gold and base metals such as zinc, copper, iron and lead from gold-process cyanide effluents was investigated. Under identical treatment conditions, different strains showed wide variations in their ability to take up gold and other base metals. Aspergillus terreus exhibited as high as a 60% gold uptake. Almost complete removal of zinc was possible with various fungi and with the yeast Saccharomyces cerevisiae. Studies at various metal concentrations showed a higher gold uptake from dilute solutions, and studies with Aspergillus niger showed that gold uptake by living cells increased gradually as the contact time increased. Metal uptake capacities between living and nonliving cells were also compared. A waste biomass (ABM- I), obtained from a fermentation industry, wasalso identified as having a high gold uptake capacity. At 5% (W/v) solids, ABM-I could efficiently remove up to 83% of the gold contained in an effluent solution within 24 hrs.

Jan 1, 1995

By Robert Dimock

The successful management of large dispersed mineral operations is dependent upon accurate and timely decision making. The plant locations providing the data to support the decision making process are generally separated by distances which elongate the time required to accumulate the data at a central focus. The need exists to examine operational data in context with total mining operations, and in relation to target projections and historical trends. The use of microcomputers for local information tasks is an established capability. Grouping microcomputers into local-area networks is rapidly becoming established. Interconnecting multiple local-area networks to provide a free flowing stream of information between all operational locations of a mining enterprise is possible with use of some emerging technologies. The benefit of the potential interconnections and rapid transfer of information can readily be seen from a production reporting perspective. Numerous other advantages exist' by providing routing to enable a workgroup to be established between separated work functions.

Jan 1, 1989

By C. M. Chang, H Gu, J. A. Barrera-Godínez, T. J. O’Keefe

The inability to economically separate Fe3+(aq) from a variety of liquid effluents is a major Concern for the primary metals industry. A unique solvent extraction process, galvanic stripping, has been developed to address this problem. The galvanic stripping of iron from D2EHPA using only a 5~10 g/L H2SO4 solution is achieved after Fe3+ is directly reduced to Fee, in the organic phase using zinc metal additions. To date, the primary focus of the laboratory research has been on optimizing the parameters that control iron removal. The results from these studies have now been, used to make a preliminary design for a continuous flow process that is envisioned for zinc industrial applications. Specific quantitative data are shown for the use of a Zn-Ph cellos° in the iron-reams al process. Some introductory results on electrochemical potential measurements and impurity distribution with solution cycling are also giiven.

Jan 1, 2000

By B. J. Arnold, C. D. Harrison, R. A. Lohnes

More than 544 Mt (600 million st) of coal are handled annually for use by this country's coal fired power plants. Coal is transported in various ways: overland conveyors, railcars, trucks and barges. It can travel short distances or thousands of miles, picking up moisture, freezing or drying. When the coal is received at the power plant, environmental problems with fugitive dust and further handling problems can arise. To ensure that power plant availability is not jeopardized by coal handling problems, the Electric Power Research Institute's (EPRI) Coal Quality Development Center (CQDC) developed a research program aimed at addressing utility coal handling problems. The program has identified key areas, and is investigating the cost and cause of coal handling problems as well as the solutions to these problems. The ultimate goal of the program is to develop a "handleability index" that utilities can use in their coal specifications or hardware for a utility's sampling system to predict handleability and determine if a coal shipment should be accepted.

Jan 1, 1993

By R. A. Jankowski

Laboratory tests were conducted to evaluate the silica collection efficiency of flooded-bed scrubbers using six different filter panel designs at two operating velocities. Test results indicated that reductions in filter density negatively impacted respirable dust collection. Silica collection efficiency for the least-dense filter was as much as 33 % lower than the collection efficiency of the most-dense filter. At the low operating velocity, the least-dense filter allowed more than 40% of the respirable silica dust in the scrubber intake air to pass through the unit and back into the mine environment. Operation of the scrubber at the higher test air velocity increased silica collection efficiency regardless of the filter panel tested The density of the filter panels also impacted the quantity of air moved through the scrubber, with higher-density filters reducing scrubber airflow. For each filter, the relationship between dust-collection efficiency and air-moving capacity must be considered to determine the overall effectiveness for each mine application.

Jan 1, 2000

By Kenneth N. Han, Yuhong Chen

The removal of carbonaceous material from Carlin gold ore has been investigated via froth flotation. The effect of type and concentration of various oils as flotation collectors and of sodium silicate as the dispersion agent on the overall recovery of carbonaceous material has been studied. Other variables affecting froth flotation efficiency were also examined closely. These included particle size, pH of the solution, and temperature. The effect of reduction and oxidation of carbonaceous material on froth flotation efficiency has also been investigated. This investigation showed that aromatic type oil was the most effective collector. Also found in this investigation was that oxidized carbonaceous material was difficult to float unless the oxidized portion was subject to reduction before flotation. More than fifty percent of the carbonaceous material was able to be removed via froth flotation. It can be concluded from this study that the effect of pH and temperature during the rougher flotation state is of little significance to the overall recovery of carbonaceous material. Since pyrite is responsible for the high consumption of chlorine, removal of pyrite is very important in order to reduce the overall consumption of chlorine.

Jan 1, 1990

By M. G. Rylatt

BHP Diamonds is developing Canada's first diamond mine, Ekati, located in the Northwest Territories (NWT). The mine is a joint venture between manager and operator BHP (51%), Dia Met Minerals (29%), Charles Fipke (10%) and Stuart Blusson (10%). BHP Diamonds is part of BHP Minerals: Production at Ekati began Oct. 14,1998. The mine is situated on a 3,450-km2 (853,000-acre) claim block located in the Lac de Gras region of the NWT (Fig. 1). It is about 300 km (185 miles) northeast of Yellowknife and 100 km (60 miles) south of the Arctic Circle. The seasonal winter ice road to Echo Bay's Lupin Mine passes along the eastern margin of the project area. This allows road access each year from mid-January to mid-April. For the remainder of the year, the project is accessible only by air.

Jan 1, 1999