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By F. Dakubo

"Solvent extraction of copper pregnant solution (PLS) obtained from ammonium peroxodisulfate assisted leach was modeled using response surface methodology. Mixing speed, pH, reagent concentration and organic to aqueous (O/A) ratio were selected for testing. A pitched blade mixer was used in the experiment. Mixer speed contributed significantly to copper extraction significant, while pH had minimal effect on copper extraction. The response model developed has an R2 = 0.97 and Adeq precision of 28.3. A parallel kinetic comparing study using a straight blade Rushton turbine in a turbulent regime of mixing showed no difference (p-value =0.308) between peroxodisulfate assisted leach PLS and conventional ferric/sulfuric acid leach PLS- the power draw data support this conclusion. INTRODUCTION High arsenic chalcopyrite concentrates are a problem to the smelters all over the world due to high arsenic gas emissions during smelting. Therefore leaching is often the alternative for extracting the copper in these concentrates if dilution with low arsenic concentrate is not possible. High-pressure autoclave leaching is used. Alternatively, the use of stronger oxidants such as peroxodisulfate has been proposed [16, 18]. There is a concern brought up by the hydrometallurgy community about the faith of the organic extracting reagent coming into contact with stronger oxidant residue in the pregnant leach solution (PLS) and hence the efficiency of such extraction process. This work, therefore, looks to answer such concerns. PLS generated from leaching of chalcopyrite concentrate with the peroxodisulfate ion was used in this solvent extraction experiment. As a liquid-liquid extraction, solvent extraction involves contacting the aqueous PLS with organic extractant via mixing. Mixing is known to increase the interfacial area for mass transfer by decreasing the diffusion path length (Jussi et al.1997). EXPERIMENT Instruments and Reagents Reagent grade Acorga 5910 reagent was used in the experiment was supplied by Cytec (Current name Solvay), Ammonium peroxodisulfate and sulfuric acid were reagent grade obtained from Amazon. Apparatus The solvent extraction tests were carried in a 2000 ml plastic cylindrical reactor equipped with four 0.5” baffles. In the hypothesis test, the reactor was a 4000 ml cylindrical reactor with four 1” thick baffles arranged evening in the reactor. Comparison between peroxodisulfate and ferric leach PLS via hypothesis test"

Jan 1, 2018

By Nora M. Hutt, Kevin A. Morin

One technique for controlling ongoing acidic drainage is to relocate and submerge net-acid-generating waste rock in a lake or water-retaining impoundment. This can lead to the overall improvement of water quality and the reduction In short-term environmental liabilities. A case study of this technique is the Eskay Creek Mine in northern British Columbia. Some findings of the study are: (1) the addition of lime to each truckload of rock, based on its rinse pH, neutralized the accumulated acidity and suppressed the accumulated-metal release, (2) only 10-20% of the dump's neutralization potential had been consumed when acidic drainage appeared, (3) water chemistry in the watershed recovered roughly three years after relocation, and (4) environmental liability was reduced due to the cessation of on-land acidic drainage with no degradation of lake chemistry.

Jan 1, 2000

By H. L. Ehrlich

Marine manganese nodules harbor a mixed population of manganese-oxidizing and -reducing bacteria, as well as bacteria that do not act on manganese. They also host phagotrophic protozoa. Out of several laboratory studies, one line of investigation indicates that some kinds of bacteria found on nodules can catalyze the oxidation of Mn2+ bound to Mn(IV) oxide at the surface of nodules at in situ temperature and pressure. In the absence of appropriate bacteria, the rate of oxidation of the surface-bound Mn2+ is significantly slower. How Fe(III) is incorporated is still unclear. Base metals such as Cu, Ni and Co, which are usually found in marine nodules in various quantities, may be incorporated through scavenging by Mn(IV) oxide. Laboratory evidence shows that some other bacteria on nodules can reduce the Mn(IV) oxide to Mn2+ in the presence of an appropriate source of reducing power in the form of organic carbon. The reduction of Mn(IV) oxide mobilizes manganese and trace metals such as Cu, Ni, and Co in the nodules. These bacteria reduce Mn(IV) whether oxygen is present or not. They could be harnessed in the bioleaching of nodules. The manganese(IV)-reducing bacteria and the bacteria that neither oxidize nor reduce manganese are thought to keep the organic matter in the nodule environment sufficiently low to favor bacterial manganese-oxidation, which in laboratory tests is inhibited by excess organic carbon. The preying by the protozoa on the different kinds of bacteria is thought to control the bacterial population on nodules and ensure continued growth of the manganese-oxidizing bacteria and the nodules. To eliminate interference from seawater salts in the bioleaching of Mn, Cu, Ni and Co, it may be more advantageous to use terrestrial Mn(IV)-reducing bacteria than the Mn(IV)-reducing bacteria resident on nodules. The terrestrial bacteria would allow bioleaching in fresh water. Unlike the marine bacteria, most terrestrial bacteria studied to date reduce Mn(IV) oxide only anaerobically. A general outline for an anaerobic bioleach process of marine nodules with freshwater bacteria is discussed.

Jan 1, 2000

By Duane A. Smith

Horace Tabor. No 19th century Colorado mining man is better known but, unfortunately, probably less understood. He is little appreciated for his significant contributions to the industry and the state. A century ago, Tabor was headline news. The legend today, however, has become so all pervasive and so interwoven with fact that the two are hard to separate. For example, he never told Baby Doe on his death bed to hang on to the Matchless mine. Yet this has emerged as staple Tabor fare. So much attention has been focused on his matrimonial triangle that it overshadows the man. Symbol of mining's reward Tabor traveled west in the 1859 Pike's Peak gold rush. In the next generation, he came to symbolize the rewards mining might lavish on an individual. The Leadville Daily Herald (Sept. 10, 1882) could write, without exaggeration, that "the extent which the mining industry of Colorado is under obligation to Tabor cannot be easily estimated - what he has done for Leadville and Denver is patent to all." It had not come easily, nor had Tabor started out a success. His early placer mining at Payne's Bar, near present-day Idaho Springs, CO, had turned no fortune. So in 1860, he, his wife Augusta, and son went south to Colorado City, then over Ute Pass and up the Arkansas Valley to Oro City. Arriving soon after the initial discovery, Tabor staked a good claim. With a sharp eye, he and Augusta broadened their base by establishing a store. Both mining and business would pay dividends in the following years. By the season's end, though, Oro City was already declining. Always on the lookout for a richer district, Tabor and his family moved the next year across the mountains to promising Buckskin Joe. The familiar pattern followed, with the store and post office being the center of their attention. Mining investment and management now replaced the earlier physical panning and sluice operating. Seven years later, the Tabors abandoned Buckskin Joe and returned to Oro City. It had moved up California Gulch to be near the district's best mine, the Printer Boy. Middle class was not enough Middle class respectability, plus a steady income, was the Tabor's by the 1870s; fine as far as it went. But it proved far from the fortune Horace had always been seeking. Oro City languished in the backwash of Colorado mining and Tabor seemed like many men who had drifted around the Territory following the ebb and flow of mining. His faithful wife Augusta had been a steady factor in the success the family achieved. She helped year after year to operate the store and post office. Not simply the happy-go-lucky individual he has often been portrayed, Tabor was a hard working businessman/mine owner. An R. G. Dun and Company agent evaluated him in 1876 "Net worth $23,200. Is a very shrewd businessman and not liable to lose money, has a good chance to make money as he had no competition." Leadville: Tabor's silverlined-fortune After all those years on the Colorado mining frontier, in 1877, Lake County's wealthiest and most respected merchant made another move. It was short in distance, only 4 km (2.5 miles) down California Gulch, then a little north to a new mining camp. This new camp, soon named Leadville, gave birth to the Tabor fortune and legend. Middle-aged (Horace was 47), the Tabors once more set up their general store and found themselves in the midst of the open¬ing of a new district. This time silver beckoned and not the gold that had brought them West 18 years before.

Jan 1, 1989

By D. Yadon, P. Lee, W. Kelly, C. Stilwell

Rico is a small town in an old zinc mining district in a mountain valley of southeastern Colorado. Mine waste rock and mill “tailings” remained after over 100 years of mining in the area, leaving associated surface water and groundwater impacts. Atlantic Richfield Company is proposing an innovative approach, which uses lime precipitation and wetland ponds (semi-natural system, also called treatment lagoon in a wetland setting) to treat adit water in the Rico area. Besides using a non-conventional treatment approach, a non-conventional (non-Superfund) regulatory/administrative approach is being proposed. This paper will focus on the water treatment issues and solutions, as well as describing the innovative “watershed” regulatory process.

Jan 1, 2004

By W. Petruk, D. B. Sikka

Lithium-bearing lepidolites from three deposits in the province of Goias, Brazil, were investigated to determine whether there is a correlution between the lithium content of the mineral and the color of lepidolite and associated tourmaline. Such a correlation can be a useful guide to field geologists for outlining high-grade lithium ore zones. It was found that mauve-pink lepidolite associated with pink tour-maline, and brownish lepidolite associated with black tourmaline have high lithium contents, but that the color of lepidolite is not due to lithium. The pink color of lepidolite and tourmaline is likely due to Mn3+, and the brownish tint of lepidolite and black color of tourmaline to Fe3+. Lepidolites appear to be lithium- rich when the lepidolite and associated tourmaline contain relatively high amounts of Mn3+ and/or Fe3+.

Jan 1, 1988

By Tetsuo Yamazaki

Natural cold seepages are characterized as rapid upward transports of methane from deeper parts of geological structures to the seafloor. Thermogenic and/or biogenic methane generated in deep sediments moves up to seafloor, and major part of methane is consumed in anaerobic oxidation of methane (AOM) and hydrogen sulfide is created in anaerobic sulfate reduction by consortium of microorganisms. Then the hydrogen sulfide is utilized by chemosynthetic communities near the seafloor, such as Acharax, Calyptogena, Bathymodiolus, and the mat-forming bacteria Beggiatoa (Fig. 1). When the supply of methane is large or rapid, remaining methane escapes from seafloor, and it is aerobically oxidized in seawater. A mass balance ecosystem model of chemosynthetic community around natural cold seepages in sediment layer and on seafloor has been created and improved by the authors (Yamazaki et al., 2005; Takeuchi et al., 2007). The model is constructed from 3 main processes as schematically shown in Fig. 2: (1) Methane supply process; (2) Ecosystem process; (3) Water column process. The part of chemosynthetic communities is in the ecosystem process. A numerical model CANDI (Carbon And Nutrient Diagenesis) was developed by Boudreau (1996) to simulate the biogeochemical processes such as organic matter, oxidant, nutrient, bi-product, and pH diagenesis in aquatic surface sediments. Then, the improved version named C. CANDI was developed (Luff and Wallmann, 2003; Luff et al., 2004). The authors created the same type carbon and nutrient diagenesis process model with calcium carbonate formation like C. CANDI (Yamazaki et al., 2005), and have added the sulfur oxidizing and immobilization processes (Takeuchi et al., 2007). The sulfur oxidizing and immobilization processes are connected with the carbon and nutrient diagenesis process model.

Jan 1, 2008

By Yoginder P. Chugh, K. V. K. Prasad, R. Missavage

This paper presents results of field monitoring and finite element studies to analyze and improve a room-and-pillar retreat mining system. Fie1 d instrumentation was utilized to monitor pi11ar load changes, roof to floor convergence and differential roof strata movement as retreat mining progressed and to determine in-situ horizontal stresses. A two-dimensional finite element model depicting strata behavior at this mine was developed and used to analyze existing and alternate improved mining geometries. The results showed excellent correlation between fie1 d observed and model predicted behavior. Some of the recommended changes in mining geometry based on the study were incorporated in the mining system.

Jan 1, 1986

By Peter Sullivan, Johan van Heerden

Increased use of continuous miners and roadheaders in the underground coal mining industry in South Africa has led to improved productivity and efficiency of operations. Of major concern, however, is the increased amount of airborne dust generated during mining. Dust is a health hazard in terms of respiratory diseases, can impede productivity and is the major contributor to the potential of underground explosions. The concern of the South African coal mining industry with regard to the underground dust problem has led to the establishment of a Dust Control Section in the Coal Mining Division of COMRO. In the field of dust suppression system evaluation and design, collaborative work has been undertaken by COMRO and FLOSEP. This paper gives a review of the application of Computational Fluid Dynamics (CFD) in evaluating and improving environmental conditions in continuous miner and roadheader sections. A brief history of the development of the CFD model as well as a discussion of a typical application is included.

Jan 1, 1993

By Georgy Cherkashov

The geological setting, morphology and physical properties of massive sulfide deposits must be taken into account when designing the underwater systems being currently constructed for mining of this type of marine minerals. Based on more than 20 years experience of hydrothermal mineralization studies in the northern equatorial part of the Mid Atlantic Ridge (MAR) we have provided the following conclusions:

Jan 1, 2008

By Donald P. Richards, Patrick Ramond, Martin Herrenknecht

Phase 1 of the second line of the Cairo Metro includes approximately 5.83km, of double track tunnels excavated in water bearing sand of the Nile flood plain. Closed face bentonite slurry shield tunnel boring machines 9.43m in diameter were used. State-of-the-art technology was used in TBM operations and guidance, with surface settlements averaging less than 14mm, and alignment deviations averaging less than 25mm. Production rates up to 580m/month were achieved, with average production of 4.8m/shift, 13.4m/day and78m/week. The completed tunnels, lined with precast concrete segments, are completely watertight under 20m of water pressure.

Jan 1, 1997

By John Drew Ridge

Recent work by Haas has made available information on densities and vapor pressures of solutions of differing salinities at temperatures up to 330°C. From these data it is possible to predict the behavior of volcanic exhalations of various degrees of salinity as they approach the sea floor. Particular attention is devoted to solutions of 5.0 weight per cent NaCl and 20 weight per cent NaCl, two fluids that approximate quite closely the salinities of what Roedder termed: (1) normal hydrothermal fluids and (2) fluids typical of stratiform deposits of low-temperature conditions of origin. It is apparent that solutions above 220-230°C. cannot reach a sea floor on which the depth of water is 600 feet or less in the liquid state but will boil at some appreciable depth beneath the sea floor. Such boiling would result in the precipitation of all constituents of the ore fluids of significantly lower vapor pressure than water. The principal such constituent would be salt, and no sulfide deposits, the major constituent of which is salt are known. It follows, therefore, that ore fluids probably never get close to the sea floor of shallow seas at temperatures high enough to permit boiling. Ore fluids significantly above 230°C. can reach the sea floor in the fluid state only if the depth of the sea in the area. in question is well above 600 feet, for example, solutions at temperatures of ±300°C. reach the sea floor in the liquid state only if the depth of sea water is slightly over 3000 feet. Ore fluids reaching the sea floor at such depths may be the parents of such fluids as the Red and Salton Sea brines. On the basis of these data, the Cyprus and Kuroko deposits are discussed.

Jan 1, 1973

By O. Guyot, T. Mulpeter

Sadiola Hill mine is located in the sub-Saharan part of Mali. In its first two years of operations, Sadiola Hill mine had already exceeded expectations with respect to profitability, plant capacity, metallurgical recovery, cash costs and social integration into the area. The advanced control system installed by the authors has been a major contributor in the substantial throughput of the mill over the design tonnage with no loss of recovery. The run-of-mine ore at Sadiola consists of soft clays with a varying percentage of grit, producing a high viscosity slurry. The percentage of grit fed to the plant varies on an hourly basis. This combination was expected to have a large impact on the milling circuit and determined that the early installation of an expert mill control system would be advantageous. Svedala Cisa OCS©, was selected as the most suitable support software. The operational rules and control philosophy are housed in the OCS© graphic-oriented fuzzy expert system while a model­based Soft Sensor has the remarkable ability to detect the variations in grit in the feed. Designed during the second half of 1996, commissioning of the system began in March 1997, the OCS was fully on-line by September. With the implementation of the optimising control strategy a throughput of 5.0 million tons relative to the target of 4.4 million tons was achieved for the 1998-operating year. The Sadiola project confirms that advanced process control techniques are among the most cost-and time-effective methods of improving metallurgical plant performance. The recipe that worked at Sadiola is a mix of metallurgical expertise, proper software selection, adequate design of control philosophy, and excellent plant support and follow­up. The early decision, design and installation of the mill control system has resulted in an enhanced Return on Investment.

Jan 1, 2000

By Wolfgang Sand, Alex Schippers, Tilman Gehrke, Thore Rohwerder, Peter-Georg Jozsa

Metal sulfides are degraded via thiosulfate (pyrite) or via polysulfides and sulfur (sphalerite, galena, chalcopyrite) by leaching bacteria The attack on the crystal lattice is either effected by only iron(III) ions or by iron(III) ions and protons, respectively. Consequently, different endproducts are formed. For a control of ARD-processes, these reactions need to be hown to regulate them. Experiments in percolators up to 65 m3 with inorganic compounds like fluoride, concrete, or SDS resulted in differently lasting inhibition. Microcalorimetric measurements of microbial leach activity allow monitoring of these effects with respect to active bacterial cells, and, in addition, the amount or rate of dissolved metal sulfide allowing prediction of possible endangerment by ARD.

Jan 1, 2000

By D. A. Dahlstrom

Energy costs have had a serious impact on all basic industries today. This is due to the significant amount of energy that is used to convert natural resources into usable products. Other factors such as transportation with its major energy requirement and materials employed in processing that have already required significant energy input for their manufacture accordingly influence delivered cost to the user. The farmer is a good example of this. While his large capital investment for land, machines, and buildings is highly impacted by today's interest rates, his chemical fertilizer, herbicides, and pesticides as well as those same machines and transportation costs for his products have also been seriously affected by energy costs. With the many unit operations involved in mining and mineral processing, several of which require significant inputs of energy, one can only conclude that this industry has experienced a great increase in percentage of total cost for energy alone. Fuerstenau (1975) indicated that the minerals industry used about 12.5% of the total energy produced in the US. McNulty (1983) listed the total energy requirements for the production of 0.9 t (1 st) of various metals including the energy consumed in the manufacture of supplies employed, such as tires, explosives, chemicals, grinding media, etc. (Table 1).

Jan 1, 1987

By Munson R. McKinney, Bryan A. Slim

To date some 1,000 exploration targets (by way of adits, mine dumps, shafts, outcrops and unstoped mine areas) have so far been identified using an interactive data base system to query a digital data base comprising topographic, cadastral geological and mine components developed as a compilation of old plans, records, surveys and recently flown aerial photography. The exploration targets are intended for early follow-up as part of a 1987 exploration programme to investigate the reserve potential of the former producing property located in southern Utah. Of further interest is the unscrambling of old mine plans to provide drill targets for investigation of unstoped reserves with one target being a possible 800,000 tons in part of the lower workings. The project site encompasses about 3,200 acres of mainly patented lode claims covering most of the claims and mines of the Gold Mountain mining district formed in 1889. Turn of the century mining saw several mines operating whose total production was at least 143,000 oz. gold and 460,000 oz. silver from steeply dipping veins up to 20 ft. or more in thickness.

Jan 1, 1987

By Allen J. Sobczak, Peter J. Peters

The five tunnel contracts of Milwaukee Northeast Side Relief Sewer System are about 80 percent complete. The tunnels are all excavated for 1.9 meter (6'-0") finish diameter sewers in a variable rock, mixed face, and glacial soil environment. Different contracts were let under two primary types of specifications, performance and prescriptive, which treated aspects of construction, such as primary ground support and groundwater control, differently. Interfacing of design and construction through field personnel allowed the needs of all parties to be met and resulted in savings in time and money to the Milwaukee Metropolitan Sewerage District (MMSD). Interfacing, cooperation and risk sharing allowed resolution of problems such as line and grade variations and potential differing site conditions. It also allowed the parties to pursue constructive changes to construction activities. Thus on one contract prescribed use of compressed air was eliminated, but migration of fines into the tunnels was stopped with filter fabric. Use of an expensive primary support system was dropped, but concern about deterioration of lagging was alleviated by use of special materials.

Jan 1, 1983

By Rudrajit Mitra, Wesley B. Johnson, Erik C. Westman

The ability to understand stress redistribution within a mine allows greater extraction efficiency with reduced safety concerns. Stress redistribution has been examined at the laboratory scale using ultrasonic tomography and numerical modeling using PFC3D. A data acquisition system was built to obtain tomograms as samples are loaded in uniaxial compression. Limestone samples were loaded to failure. Three-dimensional tomograms of the samples correlate to various stress distributions. The tomograms are compared to analytical and PFC3D results.

Jan 1, 2005

By David Wilburn

Recycled materials are increasingly being used in road construction to supplement natural aggregate derived from crushed stone, sand, and gravel. An understanding of the amount of substitution that is taking place, its economics, and factors affecting the level of substitution is useful in estimating the potential for recycling and in assessing the total supply of aggregate. While U.S. consumption of recycled aggregates from crushed concrete is estimated to have increased 160 percent between 1994 and 1996; it comprised less than 5 percent of total aggregates consumed in 1995. Construction waste supply is regional, and is determined by infrastructure decay and replacement rates. Aggregate recycling rates are greater in urban areas where infrastructure is being replaced, natural aggregate resources are limited, disposal costs are high, or strict environmental regulations prevent disposal. Recycling is expected to increase as construction contractors attempt to save on transportation, disposal, and new material costs. Aggregate producers include recycled material as an option to consumers in order to prolong the life of their reserves and improve their range of products. Recycled aggregates can be a supplement for natural aggregates in selected applications, but their use should be evaluated locally based upon relative cost, quality, and market factors Because aggregate recycling is often affected by local and regional transportation systems, disposal and tipping fees, resource supply, the market for specific products, and municipal support, costs for three representative fixed site operations of different sizes were modeled. Under study conditions, all were found to be profitable, but highly dependent upon local tipping fees and market prices, which can differ significantly by location. Smaller operations were found to have different operational dynamics, often requiring creative marketing or incentives to maintain profitability.

Jan 1, 2001

By William J. Dimond

Computor analysis has opened a new world of information for the mining of resources. This paper is directed at the mining of coal. The same procedures apply to most mining projects. The available facts when evaluated against the variables produce the answers. The project must be carefully analyzed, so that the facts can be organized in a data file. The file can be expanded as additional information is obtained during the entire life of the mine. If the mine is pre-planned, the file will be expanded in an orderly fashion and updated information will be available at all times. The development of a property goes through several phases; Exploration, Economic Analysis, Development, Production, and Reclamation. Each phase is an expansion of the data file. The validity of the answers is directly related to the accuracy and quantity of available data. The basis for a data file is horizontal position, and elevation of each piece of information. A coordinate system and datum are reference for a digital (X, Y and Z) position in a spatial system, a three dimensional digital model of the mine. The current practice is to use the State Plane Coordinate system and elevations as established by the U. S. Coast and Geodetic Survey. Each state has adopted this system by law. In the event there is litigation, it is an advantage to have the data on the legally recognized system. The control must be expanded so that all data can be assigned a digital position, and planned to fulfill the requirements for all phases of the mining operation. The project must be analyzed to insure that the objectives can be achieved without duplication or loss of time. sufficient data must be available to reach each required level of information. The coal data can be defined in two categories, spatial

Jan 1, 1977