Search Documents

Introduction Some people say it is almost impossible to get mining permits in California. Some say the day of the lone mining entrepreneur is past. And some say you cannot make money mining gold where old-timers have already mined it, especially in Tertiary gravels. But a young mining operator and SME member, Tim Callaway, is proving these ideas wrong. Callaway's company, Brush Creek Mining and Development Inc., has the necessary permits for its Gardner's Point gold mine in Sierra County, CA. And, Callaway has secured funds for the 7.7 km'/d (10,000 cypd) Tertiary gravel operation. The company's initial goal is to produce 373 to 466 kg/a (12,000 to 15,000 oz per year) of gold at Gardner's Point mine at a cost of less than $6.43/g ($200 per oz). Feasibility studies are currently being conducted to consider product levels up to the 1555 kg/a (50,000 oz per year) involving additional plants and infrastructure. While exploring for other hard-rock properties, the Brush Creek company already operates the Brush Creek lode gold mine. The mine sits high on a ridge south of Goodyear's Bar, which is located on the North Yuba river. It might be noted that the Brush Creek mine has been the subject of media stories recounting how a mine can operate with sensitivity to the environment. Gardner's Point project In 1983, Callaway negotiated with the Gardners Point Ltd. Partnership for control of the Gardner's Point property. The Partnership had been engaged for three years in securing permits, mapping and drilling, and test mining. The Partnership actually mined about 43.5 dam3 (57,000 cu yd) of gravel, which yielded 25.2 kg (810 oz) of free gold. Later, the Brush Creek company acquired ownership of the property. The company then began its own exploration and development program. As underground development proceeded at the Brush Creek mine, plans matured for a high-volume operation at Gardner's Point. Australian and English investors contacted Callaway. A joint venture was negotiated. The Australian owners became majority participants; the Brush Creek company, a minority participant and the operator. The Australian investors agreed to contribute $3.5 million (60%) to the Brush Creek Joint Ventures. The Brush Creek company will contribute its expertise as well as assets and liabilities valued at $2.3 million (40%). About $2 million has been allocated to the Gardner's Point project. Later, Brush Creek Mining and Development Inc. sold 50.4% of the company's common stock to English investors for $5.4 million. Callaway negotiated this private placement, which permits further exploration of projects being investigated. Geography and history The Gardner's Point mine is located in the northern Sierra Nevada of California, about 9.6 km (6 miles) east of the little town of La Porte in Plumas County. The mine lies high on a ridge above Slate Creek, which divides Plumas and Sierra Counties. La Porte is accessible from the Sacramento area by a winding, paved, two-lane highway. But the mine is reached only by two different unpaved county and Forest Service roads. Both roads include steep grades in and out of the Slate Creek canyon. Mine elevation is about 1.4 km (4600 ft) above sea level. The area is thus threatened by occasional heavy winter snows, though it

Jan 3, 1987

By William R. Yernberg

The Cripple Creek & Victor Gold Mining Co.(CC&V) celebrated completion of a two-year, $168.5-million expansion and capital improvement program. An open house celebration was held in the historic mining town of Victor, CO on Oct. 4, 2002. Hundreds of townspeople, the press and other invited guests from the mining industry joined the employees of CC&V in the celebration. The event included mine tours, company displays and a barbecue picnic, complete with a country and western band. The Cresson Mine is located about 40 km (25miles) west of Colorado Springs, CO between the towns of Cripple Creek and Victor. The mine is the only large-scale gold mining operation in Colorado and now employs about 300 (ME, October 2001, pp.21-28). The operation is a joint venture between Anglo-Gold (Colorado) (67%), based in Greenwood Village, CO, and Golden Cycle Gold (33%), based in Colorado Springs. CC&V is managed by AngloGold North America. AngloGold North America is the U.S. subsidiary of AngloGold, the world’s second largest gold mining producer. AngloGold is based in Johannesburg, South Africa.

Jan 1, 2002

By M. A. Hammer

In this study by the Federal Bureau of Mines Pennsylvania anthracite from the Eastern Middle field was oxidized by concentrated nitric acid at steam-bath temperature for 24 to 1,000 hours. The quantitative data obtained include yields of nitric-acid soluble and insoluble products and the distribution of carbon and ash in each. The acid-insoluble residues were examined for solubility in aqueous sodium hydroxide. With a sodium hydroxide concentration of at least 1 normal, a portion of the residue could be extracted in the form of a true solution. With lower alkali concentrations, peptization occurred. Alkali solubility of the residue increased with length of oxidation. However, when expressed in percentages of original coal weight, the alkali solubility remained essentially constant after 192 hours of oxidation. This suggests that the alkali-soluble products are converted to acid-soluble products at the same rate as the original coal substance is converted to alkali-soluble material. Microscopic observations of the peptization of the acid-insoluble residues revealed a gross micellar physical structure. The action of nitric acid is apparently not restricted to the surface of a coal particle. The acid penetrates the particle through the pore structure, dissolving some of the ash and altering the bonds between the coal micelles. The bond alteration, as indicated by ultimate analyses, involves the physical and chemical adsorption of the components of nitric acid. Some of the altered bonds are not thermally stable; this instability is shown by the complete loss of peptizing ability when the acid-insoluble products are heated above 200° C. This loss is accompanied by the evolution of water, oxides of nitrogen, and hydrocyanic acid.

Jan 1, 1961

By Andre Zingano

The objective of this paper is to study the effect of annulus thickness on the quality of resin mixture for fully grouted resin bolt. Pullout and mixture tests were made in underground coal mines for the following arrangements: (a) borehole diameter 1.14 in. (29 mm), and roof bolt diameter 0.75 in. (19 mm) with steel wire around the roof bolt; (b) borehole diameter 1.14 in. (29 mm), and roof bolt diameter 0.75 in. (19 mm) with no wire around the roof bolt; and (c) borehole diameter 0.95 in. (24 mm) and a roof bolt diameter 0.75 in. (19 mm) with no wire around the roof bolt. The mixture test in steel pipe showed that the best resin mixture is for borehole with 0.95 in. (24 mm). The arrangement (b) produced big voids around the bolt. But for the 0.95 in. (24 mm) hole, arrangement c, the mixture was the best. It was corroborated with the pullout tests results where there is a difference in grout stiffness: the 0.95 in. (24 mm) borehole is about 10 times higher than a borehole with diameter 1.14 in. (29 mm). On the other hand, for the cohesive strength the difference is not significant. Numerical models were built to simulate the pullout tests, and also to simulate the roof support at an intersection. Convergence at two underground intersections, consisting of an immediate roof with laminated sandstone, was monitored to evaluate the performance of the roof supports, using the 1.14 and 0.95 in. (29 and 24 mm) diameter boreholes (i.e. arrangements ?a? and ?b?). The convergence readings showed that the 0.95 in. (24 mm) borehole diameter resulted in a smaller, although it was not significantly different.

Jan 1, 2008

By M. M. D. S. Vemba

Paper written on project work carried out in partial fulfilment of B.Sc. Eng (Mining Engineering) degree Engineering refers to the application of mathematics and other sciences to logically develop solutions to problems. However, in opencast mining, due to the randomness of operations, the use of mathematics is often neglected. Instead, practices that have proven successful elsewhere tend to apply. At the other end of the scale, mathematical models have been developed to identify and quantify all the operational parameters involved in the loading and haulage of ore. These are then used to optimize the operation. Optimization in this context, refers to the reduction of cost through effective utilization of the available time and resources. Considering these mathematical models, the loading and transport system at SMC (Catoca Mining Society) will be assessed with a view to its optimization. The discussion will be introduced by considering the mine background and other general information, which will highlight the main operational variables.

Jan 1, 2004

By Michael E. Meadows

The results of tests to determine the .regional applicability of four synthetic unit hydrograph models are presented. The SCS curvilinear (Haan), SCS single triangle, Williams and TVA double triangle unit hydrograph models were tested on 271 events from 38 USDA experimental watersheds in 14 physiographic provinces. Though inconclusive due to the limited number of events analyzed, the results indicated a regional tendency for each model, with the SCS curvilinear unit hydrograph method generally performing best overall. It outperformed the SCS single triangle by predicting better shape; they differed less than 2 percent in time of peak and peak rate predictions. The Williams model performed well at Oxford, Mississippi and Coshocton, Ohio, which suggests it may be applicable to surface mined lands within the Northern and Central Appalachian Plateau and Texas coal producing regions. The TVA model is applicable to the Appalachian Plateau, specifically the Cumberland Plateau. A second test using only the SCS curvilinear unit hydrograph on 11 small watersheds and 50 events was conducted to investigate the effect of the excesss rainfall pattern on simulation results. A Green and Ampt infiltration model was coupled with the SCS unit hydrograph model to determine if peak rate and timing errors noted in the regional test could be minimized with an alternate to the SCS curve number model for determining infiltration losses. The results confirm the curve number model is the better approach to determining the excess rainfall pattern for unit hydrograph simulation.

Jan 1, 1983

By Poul Hansen

"In mid-I986, a world-class mining enterprise was created in British Columbia, bringing together the copper mining operations of Lornex Mining Corporation and Cominco into a new entity, Highland Valley Copper. This paper will focus on the background and rationalef or the formation of this partnership, the resulting operating changes and the productivity and cost benefits expected.IntroductionSince the deterioration of the world copper industry in 1981, the future of the Lomex and Cominco mines in the Highland Valley of British Columbia looked increasingly precarious. Despite the expansion of the Lomex mill complex in 1981 to one of the world's most cost-efficient copper and molybdenum concentrators, persistent low metal prices had made the remainder of the ore in the Lomex orebody marginally economic and had significantly foreshortened the expected life of the operation.Cominco had acquired the Bethlehem Copper assets in order to consolidate its ownership of the Valley orebody, and was feeding the Bethlehem concentrator with ore from the Valley orebody. In spite of the high grade and free-milling character of the Valley ore, profitability of the Cominco operation was severely restricted because of the limited capacity of the Bethlehem concentrator and its location high on the hillside above the orebody."

Jan 1, 1987

By Prosper Lamothe

El presente texto describe la metodología ad-hoc para evaluar proyectos de Inversión estratégicos a través de la flexibilidad y la teoría de opciones reales. La clave de dicho enfoque metodológico radica en realizar la mejor proyección del precio de los metales aplicando las mejores prácticas mundiales al respecto. Para ello, se analizan una gran variedad de modelos concluyendo que el mejor modelo a aplicar, debe ser la simulación del precio del metal con reversión a la media con saltos de tipo aleatorio.

Sep 9, 2007

Poorly designed sampling protocols generally result in high project risk by artificially increasing grade variability (ie the nugget effect). Sample collection, preparation and assay protocols that suit the ore type, together with QA/QC systems, will reduce this risk. All reporting codes (eg JORC, 2004) require the Competent Person to consider the quality and implication of sampling and assaying programs. High sampling errors beget higher project uncertainty; despite this fact, sampling does not receive the attention it deserves. The case studies presented show that many sampling issues frequently go unrecognised or unaddressed, resulting in poor project decisions during exploration through to feasibility and production. The overall conclusion is that correct sampling is critical to mining project success and that there is often a need for its optimisation.

Jan 1, 2007

By Lyda W. Hersloff

An environmental monitoring program was established to assess the baseline of parameters which may be impacted by a research and development hydraulic borehole mining operation. During the baseline program, two aquifers were identified at the borehole site with the overlying sand aquifer being distinct from the ore sand aquifer on the basis of radiological parameters. The direction of flow of groundwater was determined to be north 19° west at a rate of 1.82 feet per year. Tests to determine the effect of backfilling the boreholes indicated that using overburden from the open pit mining operation would not significantly increase the radiological consti¬tuents of the ore sand aquifer. Mining measurements of the- radon flux from the borehole indicated that the actual release rate of 0.035 pCi/sec was several orders of magnitude less than the calculated estimate by the Environmental Protection Agency. Finally, a gamma survey conducted at the site indicated that the terrestrial component of background radiation was consistent with that in areas near uranium deposits. The methodology used as well as the supporting data are given in this report.

Jan 1, 1981

By Wu Jie Mei, Li Yao Liang, Franz-Werner Gerressen, Arthur Bi

Diaphragm walls (D-walls) are known as underground structural elements commonly used for retention systems and permanent foundation elements. In addition, they are also quite often used as deep groundwater barriers, called Cut-Off-Walls (COW). Shanghai ranks third among the most densely populated metropolises in the world. In 1990, only eight million people lived there. Today, Shanghai has about25 million inhabitants. The increasing demand to accommodate the infrastructure of growing megacities like Shanghai pushes the required depth for subway, sewage and foundation projects to the limit. Future projects will demand excavation depths of more than 100 m (328 ft) on a regular basis. Already carried out reference projects will be described and a general outlook for upcoming projects will be given. The paper also explains the installation process in general focusing on the use of trench cutter technology. INTRODUCTION D- walls are known as underground structural elements, commonly used as retention systems for excavation pits and shafts as well as permanent foundation walls or elements. It is anticipated that, with the increasing trend of utilizing more and more underground space to accommodate environmental considerations and urban/suburban development, there will be an increasing requirement for diaphragm wall usage in even more difficult conditions and with increasing depth. The trench cutter is the most important tool for performing this work. The hydraulic grab, a well-known and valuable excavation tool for d-walls reaches its limits in terms of depth and when cutting rock. Therefore the trench cutter technology will be in the focus of this paper. The trench cutter itself is a reverse circulation excavation tool. It consists of a heavy steel frame with two drive gears attached to its bottom end, which rotates in opposite direction around the horizontal axis. Cutter wheels are mounted onto the drive gears. As they rotate, the soil beneath the cutter wheels is continuously broken up, removed, mixed with the bentonite slurry in the trench and moved towards the opening of the suction box of the pump? A centrifugal pump located right above the cutter wheels conveys the slurry via a hose system up to a desanding plant. There the slurry loaded with soil and rock particles is cleaned and returned into the trench.

Jan 1, 2018

By Michael Horn

[An economic trading region made up of 22 eastern Washington, northern Idaho, and western Montana counties, with Spokane, Washington as the central place, was defined for this study. modeling system with the, 1985 county database was to create an Input/Output based model of the regional economy. The leading ice, with respect to income, employment, value of exports, and total industry output are shown for each county and the region. The value of total industry output from natural resource based industries is also shown for each county and the region. Interindustry transactions, final demand, and value added components for the region are shown in the Regional Gross Flows Table. The total gross output for the region is valued at $36.7 billion. Total industry output for the region is $18.1 billion. The region provides $5.4 billion in income to a work force of 286,000. Spokane County, Washington accounts for about 50 percent of the regional total industry output, income, and employment. Both Spokane County and then as a whole produce about 80 percent of the total industry output for final demand with remaining 20 percent going to intermediate inputs for further production. Spokane County exports about 43 percent of its total output while 35 of the regional output is exported. Exports account for more 50 percent of the total in 18 of the 22 counties within the region. About 9 percent of the total industry output from Spokane County and 19 of the total output from resource f: .t *III For counties Spokane a industry ? N from nafural resource based represents 18 percent ?.{1 to 71 s. ?-{ and averages 39 r. ?-11 of total county +' ' 7:. FS.-f.?) If t. Natural resource it us -t for more than 50 coutny 1 s ? sass in seven counties within region.]

Jan 1, 1992

By G. A. Kosick, G. S. Dobby

"This paper presents the principles and application of a recently developed control system for flotation columns and column circuits. The control system uses triple pressure sensors to directly sense zone densities and level, and to help in characterizing the operating behaviour of individual columns. A complete expert system development tool is incorporated within the system to provide the facility for full operator training, an on-line help facility, and a means for incorporating the column behavioural patterns into decision making rules. The system is configurable to any number of columns and can be run in either supervisory mode or direct control through Minnovex PIO software. Additional process signals can be interfaced with the system if desired. Operating experience with the control system on the Minnovex column flotation pilot plant is described.I: INTRODUCTIONColumn flotation cells have been more difficult to control and are more sensitive to circuit changes than conventional mechanical flotation cells. This susceptibility encouraged investigation into various types of control strategies ranging from inexpensive single pressure measurements for level control, to highly instrumented and expensive systems using a variety of control methods.Flotation operators, in many cases, do not understand the column control philosophy or have not been trained to deal with this new type of cell. Some operators have subsequently absolved themselves of the column operating responsibility. Some column cells, for example, have run for hours with slurry pouring over the top or no froth coming off at all.ColumnEX is a column flotation control system which was developed from the viewpoint of an operating shift foreman who wishes to:1. control the column or column circuit through a genuine understanding of what is happening inside the columns, and2. to share this knowledge with his flotation operators and be available to guide them through times of circuit upsets."

Jan 1, 1990

By T. K. Dichmann, J. A. Finch

"Microflotation, laboratory batch, and in-plant minicell continuous tests were conducted to determine if copper ions not only activate sphalerite but also depress pyrite when the minerals are together. Microflotation tests showed that pyrite recovery increased with addition of copper ions in the pH range of 5-10 when alone, but decreased when sphalerite was also present. Batch flotation tests (Red Dog ore) showed that upon addition of copper, pyrite recovery decreased significantly. The continuous tests (Louvicourt Mine) confirmed this and indicated that with excess copper pyrite recovery can increase. The results suggest there is competition for copper and xanthate in favour of sphalerite. To take advantage of this competition it may be necessary to control the sequence and rate of copper, collector, and lime addition. INTRODUCTIONFlotation, in common with all physical separations, is an imperfect process that results in misplacement of minerals. One source of this imperfection is accidental activation by contaminating metal ions. An important practical example is the misplacement of pyrite to zinc concentrates. Flotation of sphalerite generally requires activation by copper ions, added as copper sulphate. Copper ions are also used to activate pyrite [l] hence there is the suspicion that accidental activation contributes to the recovery of pyrite (Py) with the sphalerite (Sp). However, recent literature has shown that copper ions may make Py less floatable if Sp is also present. Xu et al. [2] conducted continuous minicell tests in-plant at Kidd Creek Operations (division of Falconbridge Ltd.) and showed that while the addition of copper sulphate improved zinc/iron selectivity, it did so as much by reducing the recovery of pyrite as increasing zinc recovery (Figure 1)."

Jan 1, 2000

Jan 1, 1969

By V. B. Dale

This is one of a series of reports covering the mineral resources of the Nation. It describes briefly most of the known tungsten deposits in Yuma, Maricopa, Pinal, and Graham Counties, Ariz. Most of those described were examined by the author. An effort was made to determine the position of the various deposits by section, township, and range and to give accurate road direction to each property from a prominent landmark. All available maps have been used in making these determinations, but in unsurveyed areas it was necessary to make approximate projections of subdivisions. The township and range numbers refer to the Gila and Salt River base and meridian.

Jan 1, 1959

By K. E. Tame

The Bureau of Mines is studying possible modifications in conventional uranium ore-processing steps to confine and permit controlled disposal of radioactive wastes. A potential method of minimizing pollution from radio-active nuclides, principally radium 226, in uranium mill waste streams is to reuse the waste solutions within the mill. Such reuse of waste solution in the Kerr-McGee Shiprock-type process was investigated in the laboratory. The Shiprock mill employs a two-stage acid-leaching process for dissolution of the uranium, countercurrent decantation for liquid-solid separation and washing, and organophosphorus solvent extraction for recovery of the uranium and vanadium from solution. The simulated use of barren raffinate instead of fresh water in the mill circuit was carried through a laboratory campaign of 28 interlocked leaching, washing, and solvent extraction cycles. About 99 percent of the uranium and 91 percent of the vanadium were dissolved from the are, Washing efficiency in the thickener circuit averaged about 99.5 percent when the pulp was washed with enough barren raffinate and makeup water to recover 2.5 tons of pregnant solution per ton of ore. The only solution discarded was that contained in the washed and thickened leach residue. A buildup of salts due to recycling of solutions did not adversely affect operation of the washing circuit.

Jan 1, 1962

By M. F. Handley

Sequential grid mining has been employed as the primary mining strategy at the AngloGold West Wits Elandsrand Mine since the inception of stoping operations from the sub-vertical shaft system in 1988. Little has been published on sequential grid mining as a mining strategy since, and the purpose of this paper is to describe sequential grid mining, its history, its implementation at Elandsrand, and the outcome to date. The results obtained using sequential grid mining have been evaluated from seismic data, productivity statistics, and rock related accident statistics. Comparisons with neighbouring mines namely Western Deep Levels and Deelkraal, have been made to substantiate the improved conditions observed at Elandsrand, and to compare sequential grid mining directly with longwall mining in similar conditions and at similar depths. Sequential grid mMining is shown to be cost-effective, more flexible, and safer than long wall mining in similar conditions, at least on the Ventersdorp Contact Reef in the western part of the Carletonville Goldfield. More work is necessary to establish it as the favoured mining strategy at depths exceeding 3000 metres, and for reefs other than the Ventersdorp Contact Reef.

Jan 1, 2000

By E Portes, G Noble, J Roberto, A Stabile

Iron ore beneficiation plants are facing economic pressures to treat more challenging ore types, improve efficiency and improve product quality. Better control and stability of the plant process in the face of increasing feed ore variability has been a goal for many of the operations facing these challenges.Prompt gamma neutron activation analysis (PGNAA) technology has proven to be a successful measurement technique within an iron ore beneficiation plant. PGNAA was first developed in the early 1980s for the measurement of the elemental composition of bulk materials. Today, PGNAA technology is applied for elemental analysis within the iron ore industry on both bulk materials and slurries.Traditional composite sampling throughout the wet iron ore beneficiation process provides a delayed measurement of average properties but does not capture the true variability of the process in real-time. As such this is a limiting factor towards stabilisation and optimisation of the process. A PGNAA analyser provides real-time slurry elemental analysis of feed, concentrate and tails streams within the processing plant. The analytical data from the analyser can be exploited with a control strategy to correct and stabilise the plant on a much shorter time scale, delivering significant economic benefits and greater operational flexibility. The economic benefits include more stable product quality and a reduction in composite sampling and laboratory costs.Some example results will be presented from the Vale Vargem Grande iron ore beneficiation plants, which are utilising a six stream multiplexed Thermo Scientific PGNAA Slurry Analyser.CITATION:Noble, G, Stabile, A, Portes, E and Roberto, J, 2017. Real-time slurry elemental analyser for iron ore beneficiation plant control, in Proceedings Iron Ore 2017, pp 481–486 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Samuel M. Bryant

The purpose of this study was to develop procedures to measure Bingham flow properties for mine tailings and to use these to predict the possible consequences of a hypothetical tailings flow failure at the Tenmile Tailings Pond at Climax, Colorado. The consequences of such a failure were found to be minimal, and the failure itself highly; unlikely. Values of Ty (Bingham yield shear strength) and np (plastic viscosity) were measured for 10 materials using results obtained from vaned coaxial viscometer tests and triaxial tests.

Jan 1, 1983