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By T. O. Kuhl

The Royal-Mountain King Project is 7.2 kilometers (4.5 miles) northwest of Copperopolis, California. Reserves of 8,250,000 t (9,100,000 st) at 2.32 g/t (0.068 oz/st) gold will be processed at 2500 t/d (2750 st/d) from three pits. Production is scheduled to begin the first quarter of 1989. District geology consists of northwest trending sequences of Jurassic meta-sedimentary and meta-volcanic rocks. Three ore bodies are located along the Hodson fault which trends northwest and dips 40 degrees northeast. The Gold Knoll and North Pit ore bodies are hosted in carbonate and silica altered meta-volcanic rocks whereas the Skyrocket ore body is hosted in quartz stockwork zones in meta-sedimentary rocks. Gold is present as inclusions and micro-veinlets in pyrite.

Jan 1, 1989

By Ivano Andreis, Georgios Kalamaras, Mario Liti, Sebastiano Pelizza, Filippo Avesani

"THE SS640 AGRIGENTO-CALTANISSETTA PROJECT The Caltanissetta tunnel is part of the works for the construction of the second 28km-long maxi section of the SS 640 motorway of Porto Empedocle, from km 44 to the junction of Imera in Sicilian hinterland. Amongst other major infrastructure works, the €740 million ANAS (Italian national roads and highway administration agency) project consists of four twin tube tunnels three of which are being excavated by conventional means. The longest tunnel, underpasses the Caltanissetta city and has a length of 3.9km under a maximum overburden of 120m. The JV consisting of CMC of Ravenna and TECNIS SpA won the design & built tender in 2010. Construction started in early spring 2012 following the approval of detailed design and later on the approval of design for construction. THE CALTANISSETTA TUNNEL The Design Phase Tender design and detailed design foresaw the construction of 13.4m excavation diameter tunnels that were to be enlarged in a second phase to create, every 600m, 50m-long tunnel sections for emergency parking. During the design for construction project phase the JV proposed to replace the 13.4m tunnel with a 15.08 excavation diameter that incorporated apart from the two 3.75m wide lanes a 3.25m wide continuous emergency lane. This significant tunnel section modification was associated with better road safety conditions, simpler and safer construction procedures, better statics for the tunnel section while in terms of overall cost the solutions were equivalent.Geologic context The tunnel is located in the middle of the geologically known Caltanissetta basin that is intersected by various tectonic structures. The geologic context for the tunnel scale, was defined in collaboration with the University of Catania in early project phases. For almost its entire length the tunnel is excavated in the Terravecchia formation that represents the lower part of the stratigraphic sequence that was formed in the Tortoniano period of Miocene. The quite complex geological model is also characterized by the presence of the so-called Trubi formation that consists of clay and marl clay. Almost 90% of the tunnel traverses formations that are quite similar in terms of excavation behavior. Exception to this are thrust zones and a calcareous stretch of the alignment. This last segment has a length of 200m and was identified since the very beginning as a tunneling challenge due to the combination of very poor geotechnical properties and an important water load."

Jan 1, 2016

By A. G. Naguib

In essence, any magnetic separator operates on the basis of imparting a preferential magnetic force on particles of higher magnetic susceptibility which are to be separated from particles of lower magnetic susceptibility. A certain amount of directional deviation to the particles takes place thus allowing for collecting each category of particles separately. The forces in action on particles in a wet magnetic separator of the established designs can be analyzed in a simple manner as shown in Figure 1.

Jan 1, 1972

By J. D. Vincent

The Henderson mine site is located at Red Mountain on the eastern slope of the Rocky Mountains, approximately 50 miles west of Denver, Colorado. The mill site is on the west slope of the Rockies and mine and mill will be connected by an underground railroad. All designs were for a 30,000 ton per day molybdenite processing plant with provisions for future expansion up to 50,000 ton per day if required. This plan did not just happen, but slowly evolved over the course of about three and one-half years. Many plants cannot afford such a delay, but the Henderson project will take about 10 years from the time it was first discovered until production starts, and these 3 !1 years were well spent in determining the best possible plant site and flowsheet. This paper describes some of the problems and the decisions made in arriving at the final location and flowsheet. The paper does not go into the specific details of how protection of the environment went hand-in-hand with all other project considerations. This particular aspect of the planning has been well-reported on other occasions and considerable information on it is readily available.

Jan 1, 1972

By Carl S. Vender

Knife River Coal Mining Co.'s Beulah Mine is a multiple-seam lignite operation located in western North Dakota. The mine began production in 1963 with annual production of 450 kt (496,000 st). It now produces 2.2 Mt/a (2.4 million stpy). As development progresses, operations advanced into more complex geologic areas. Various techniques have been analyzed to maximize coal recovery in a cost-effective manner. Additional studies are ongoing to determine what changes will be implemented as deep, wet sands are encountered in the reserve area. Knife River Coal began as an underground operation in 1924 at Beulah, 120 km (75 miles) northwest of Bismarck. In 1950, the operation converted to a combination underground and surface mine. The underground segment was closed in 1952. Development of the existing reserve area south of Beulah began in 1963. About one-fourth of the acreage under permit (Fig. 1) is sufficient for 10 years at current production rates.

Jan 1, 1991

By Jean Dupéré

Introduction Before examining the current position of the asbestos industry and its market outlook, it is important to describe the product itself. If we are to understand the problems besetting this basic mining and manufacturing industry, and, more importantly, if we are to appreciate solutions to these problems, we had better view asbestos from the proper perspective. Asbestos has a unique combination of properties - properties not found in any other natural substance or man-made material. As a result, asbestos has found its way - in fact, is welcomed - into hundreds of applications. Properties and Products World production capacity of asbestos fiber is about 6.5 Mt (7.2 million st). Major producers and their approximate percentage share of actual production are: USSR, 47%; Canada, 24%; South Africa, 5%; Zimbabwe, 5%; Brazil, 4%; Italy, 3%; and others (including the US, China, and Greece), 12%. Although Canada accounts for less than one-third of the world's

Jan 7, 1984

By P. N. H. Bhakta, X. P. V. Lei

The U.S. Bureau of Mines developed an alkaline oxidative pretreatment to increase the recovery of gold from refractory sulfide ores containing arsenopyrite (FeAsS) and/or pyrite (FeS2). Pretreatment of a low grade ore containing 0.4% FeAsS, 3.5% FeS2, and 2.74g/mt Au with 1.2m NaOH, 40 psig o2, 100° C, and 4 hr in a 2-L autoclave resulted in 94 to 96% sulfide oxidation. cyanidation of the pretreated residue resulted in 88% Au extraction compared to <20% Au extraction for untreated ore. Cyanide consumption was 0.25 kg NaCN per metric ton of ore. A flowsheet for treating sulfidic low-grade gold ore is proposed.

Jan 1, 1990

By W. G. Prast

The role of governments as a factor in the international non-metallic minerals industry can take several forms. Classically, the government acts as a taxing agent, collecting part of the economic rent on behalf of the country from private-sector mine operators. In addition to its taxation policies, the state can and does provide the practical commercial framework of regulatory and fiscal incentives and restraints that shape the activities of the mining firms. In addition to its functions as an agent of the public interest, the government can choose to take a more direct stake in the mining industry, and has done so in the instance of several industrial minerals that are actively traded on world markets. In this paper, the actions of three governments are reviewed and the consequences of their actions are examined.

Jan 1, 1981

By L. Alagha, F. Schott, M. B. Haya, Z. Xiao, K. C. Monyake

"Froth flotation is a process in which valuable minerals are separated from gangue minerals on the basis of surface wettabilities. It is a universally accepted process for the beneficiation of coal. The large amount of coal fines that have been generated from both mining and beneficiation processes has been reported as a chronic problem to both fine coal preparation and utilization as these fines contain a high amount of ash forming minerals. The current study investigated the potential application of Synthetic Bio-compatible Polymers as slime depressants in fine coal flotation for the possibility to enhance the combustible recovery and ash rejection. Raw coal samples containing 21% of ash-forming minerals were crushed, grinded and floated in the presence of Chitosan polymer. Flotation tests were carried out in D-12 Denver flotation cell with 1-Liter capacity. Flotation outcomes were studied as a function of polymer concentration. Box-Behnken factorial method was used for experimental design. Second order response functions were produced for ash% and combustible recovery. The results obtained from this study demonstrated positive influence of chitosan polymer on ash% and combustible recovery. Ash % was decreased by 3.32 % while an increase of 48.15 % in combustible recovery was observed when chitosan was introduced in the flotation process. INTRODUCTION Froth flotation is a widely used method of separating minerals by utilizing the difference between surface wettabilities [1], [2].Modern mechanized mining and ore handling operations produce large amounts of coal fines which in the past were not processed but discarded as waste[3]. Even though flotation is the best method of beneficiation for coal, it can be challenging in case of fine coals. In fine coals, slime coatings of colloidal mineral matter exist on the coal surface. These coatings render the coal hydrophilic, hence reducing flotation efficiency and recovery. Of late, different researches have been using biodegradable polymers to determine their feasibility in enhancing fine coal flotation efficiency[4].Naturally occurring and synthetic polymers, for example, polyacrylamide-based polymers, have been widely used in flotation as multifunctional reagents[5],[6],[7]. Hybrid polyacrylamide polymer has been successfully used as a depressant for ash forming minerals in fine coal flotation[3]. Recently, chitosan has been successfully used in flocculating quartz particles to produce faster settling rates of fine tailings [4]."

Jan 1, 2018

By Joshua Farmer, Mike Gianforte, Tao Jiang, William Gettings

The Two Rivers Water Reclamation Authority (TRWRA) in Monmouth County, New Jersey, is replacing its aging Pleasure Bay Interceptor (PBI) with a new 54-in interceptor in a 3,250-foot long 8 to 10-foot diameter tunnel and a new 50-mgd main pump station (MPS). A comprehensive phased geotechnical investigation was performed, including SPTs, CPTs and geophysics. A channel filled with soft marine sediments was identified. The tunnel is set in stiff to hard marine soil to enable using a less expensive open-face TBM. The thickness of tunnel cover under the channel is optimized through numerical analyses to avoid a deeper pump station yet maintaining tunnel stability with controlling seepage.

Jun 13, 2021

By William J. Shampine

The Floridan aquifer, which underlies all of Florida, yields water with a hardness of less than 180 pmts per million (ppm) in the northwestern part and throughout much of the center of the Slate. In most of the rest of the Stale, the aquifer yields water having a hardness greater than 180 ppm and as much is 1,900 ppm. Hardness of ground water is caused by dissolved salts from the geologic formations through which the water passes or by direct pollution. Sometimes pollution may indirectly increase the hardness of ground water by increasing the acid content and thus increasing the solution of calcium and magnesium salts. Water from deep zones of the aquifer lend to he harder than water from more shallow zones. Only the hardness of water from the upper part of the aquifer is shown.

Jan 1, 1966

By M. Soderstrom

In a solvent extraction (SX) plant, stage efficiency calculations are used to determine mixer efficiency. With modern extractants and mixing equipment, it is generally taken for granted that stage efficiencies will be above 95%, but this is not always the case. Dependant on mixer/solution conditions, stage efficiencies can occasionally be low, therefore leading to higher reagent usage. Proper methods to identify when stage efficiency performance is below expectations, and ways to identify if it is an equipment or chemical issue are valuable tools for a plant metallurgist. With these tools and skills an on-site metallurgist can more quickly return their SX plant to proper operation. This paper will discuss methods for analyzing stage efficiency, evaluating factors that may affect stage efficiency, and evaluating the impact of stage efficiency on the overall operation.

Jan 1, 2010

By Mark Gershon

This paper describes an application of a new approach to mine planning and production scheduling in a gold mine. The technique, limited to use in open pit mines (but not limited to gold), has been described previously (Gershon, 1987). The-computer program used is the HOPS software, which has been described previously as well (Gershon, 1988). The mine is scheduled for the production of 8,000 blocks out of a mine having 25,000 blocks (50 x 50 x 10). The technique is based on the concept of inverted cones (Gershon, 1987). While it does not provide a true optimization of results, it does approximate the optimal situation. As opposed to most scheduling software that only serves as a computerized notepad for the scheduler, the use of this approach allows for a scheduling intelligence to be built into the software.

Jan 1, 1989

By Robert B. Scott

The Dents Run Demonstration Project near Morgantown, West Virginia, was a cooperative venture involving the U.S. Environmental Protection Agency (EPA), the Water Resources Division (WRD)(1) of the West Virginia Department of Natural Resources (DNR), and the Christopher Division of the Consolidation Coal Company (CONSOL). The object of this project was to demonstrate pollution control methods and to clean up a 37.8 sq km (14.6 sq mi) watershed severely polluted by coal mine drainage. A study entitled, "Water Infiltration Control to Achieve Mine Water Pollution Control" (EPA-R-2-73-142),(2) was conducted by the Cyrus Wm. Rico Division of NUS Corporation for the grantee to determine the feasibility of utilizing remedial techniques to improve the Dents Run water¬shed. This study showed that the Dents Run watershed was discharging as much as 6,870 kg/day (15,100 lb/day) of acid; 1620 kg/day (3,560 lb/day) of iron 17,250 kg/day (38,000 lb/day) of sulfates; and 29,500 kg/day (64,900 lb/day) of total dissolved solids into the Monongahela River near Morgantown, West Virginia. This pollution was caused by the combination of borehole pump discharges from active underground mines, runoff from abandoned strip mines, and runoff from refuse dumps.

Jan 1, 1977

By J. G. Dunn, A. S. Ibrado, D. J. Hollbach

Gold production is one the most important mineral process­ing industries in Western Australia. The gold is usually found in either weathered oxidised zones, or associated with sulfides. In the latter case, oxidation is achieved by some form of chemical processing, such as roasting or more recently bacterial leaching. In all cases, gold is dissolved out of the oxidised matrix by cyanide solution. Pyrrhotite is an iron sulfide generally represented by the formula Fe1_,S where O x 0.125. Three different structural forms ofpyrrhotite are known to occur naturally, stoichiometric FeS (troilite), hexagonal pyrrhotite Fe1_xS and monoclinic pyrrhotite Fe7S8 [I]. Substitution of iron atoms within the pyrrhotite structure by other ions of similar atomic radius such as nickel, copper, cobalt and manganese is also possible [2], and often observed in natural pyrrhotite samples. Pyrrhotite is abundant in Western Australian sulfide mineral deposits which are commonly associated with gold bearing ores. It is generally believed that pyrrhotite has a detrimental effect on gold recovery from such ores, as it is commonly claimed to decompose in alkaline, aerated cyanide solutions to form iron cyanide complexes, thus consuming free cyanide, and to form sulfur/oxygen containing species such as sulfate, through oxidation of sulfur in pyrrhotite, which thus consumes oxygen. From information gleaned from the literature, claims about the high reactivity of pyrrhotite in cyanide appear to be based on early cyanidation studies performed on gold ore samples which have been poorly characterised, and contained impurities such as pyrite, arsenopyrite and chalcopyrite, which may have also contributed to the levels of species observed in solution [3-5]. In addition, the investigations do not take into account that iron atoms in the pyrrhotite structure may have been partially substituted by other atoms that influence the solubility of pyrrhotite in cyanide solution.

Jan 1, 1995

By Mehmet Guney

During the last decade various modifications of room and pillar and sub-level methods have been tried in an effort to eliminate gob-fires, dangers from roof falls, surface subsidence and to increase efficiency of extraction in the Armutcuk Mine, Turkey. It was eventually decided that the most likely system to give maximum benefits in view of existing geological conditions and coal seam characteristics was a system of cut-and-fill stoping employing hydraulic stowing. This paper has attempted to examine the trends of working techniques of hydraulic stowing. In addition, the results achieved and technical problems involved are discussed.

Jan 1, 1968

By C. N. Bensley, S. K. Nicol, R. Lamb, G. W. Kidd

Flotation circuits in the metalliferous industry recover high value concentrates from very fine (minus 0.lmm), low grade, slow-floating feeds. Flotation columns acting as final cleaners within these circuits offer the benefits of higher grade concentrates, reduced circuit complexity, improved control and reduced power consumption. By contrast, in the coal industry, these benefits have not been realised, principally because columns are not well suited to the treatment of conventional coal flotation feeds (minus 0.5m). However, this does not imply that columns do not have a place within the coal industry, rather that they must be applied in a role where all the unique advantages of column flotation can be of benefit. The development of a commercial scale column to recover discarded ultrafines from the Riverside preparation plant of BHP-Utah Coal Limited is discussed. Particular emphasis is placed on the column design features pertinent to the recovery of ultrafine coal. Pilot and commercial scale column performances are compared. The results of the commercial scale testwork indicate that a full installation at the 5.5 MTPA Riverside plant would annually recover additional coal worth $US 6.6M.

Jan 1, 1988

By Paul H. Muller

The configuration of remote seal DP cells for specific gravity measurement is described and the calculations for calibration are presented. The error induced by ambient temperature change is investigated as it relates to capillary dynamics and electronic considerations. Instrument specifications are discussed in the light of accuracy requirements and the calculation of error vs. ambient temperature is described.

Jan 1, 1984

By H. Zhu

Qualitative and interpretative information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system pro-vides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data.

Jan 1, 1989

By James J. Scott

Friction Rock Stabilizers, trade name II Sp 1 it Sets&apos;" have been under research and development by the author and the Ingersoll-Rand Company since February of 1973. The United States Bureau of Mines and the Mines Enforcement and Safety Administration as well as many mining companies have cooperated in field testing the device. Split Set rock anchors are distinctively different from the widely used mechanical rock anchors or fully grouted rock anchors. They control ground movement internally in a manner that allows controlled deformation during the early phase of the ground reaction curve but then, as secondary creep develops, anchorage per unit length increases and they serve to strengthen and stabilize the opening for long periods of time. The history of research and development of the Scott Split Set rock anchor system with accompanying laboratory and field test data is presented in this paper.

Jan 1, 1977