Search Documents

By F. A. Rutledge, J. J. Mulligan, W. H. Kems, R. L. Thome

"As a part of the United States Department of the Interior program for the development and use of Alaska raw materials, the Bureau of Mines is conducting an investigation of deposits f nonmetallic minerals accessible to the Alaska Railroad for use in building materials in the Alaska Railroad-belt area. The results of the investigations, to date, indicate that raw materials for the production of brick products are in plentiful supply as clay in the Anchorage area, as fire clay at Sheep Mountain, and as shale in the Healy Creek coal formations near Healy, Alaska.Shale for the production of lightweight aggregate or Haydite occurs near mile 67 on the Glenn Highway, and preliminary tests give excellent results. Physical tests are new in progress on commercial-size concrete building units made with this aggregate. Another shale deposit in the same formation was located at mile 16 on the Matanuska Branch of the Alaska Railroad, and preliminary tests give comparable results.Natural lightweight aggregate in tree form of pumice and pumicite occurs in Katmai National Monument and has been used with excellent results in lightweight-building units in Anchorage and Fairbanks. These deposits will be investigated in more detail by the Bureau of Mines during 1952.One small perlite deposit near Healy, Alaska, showed excellent expanding properties, and the product compares favorably with commercial perlites being used in the States for plaster and concrete aggregates. Additional investigation by the Bureau of Mines to delimit the known occurrence and, if possible, discover others were planned for the 1951 field season.The pumice from Katmai National Monument also was considered for use as a pozzolan in pozzolan-portland concrete. Tests by the Bureau of Reclamation indicate that the pumice sample submitted by the Bureau of Mines would be satisfactory in strength development but is not outstanding. Natural activity is good and is greatly improved by calcination at 1,4000 F. Water requirements and shrinkage also are satisfactory. However, the material is ineffective in reducing expansion owing to alkali-aggregate reaction; and, if reactive aggregate is used to make concrete, it would not insure against excessive expansion. An attempt will, be made during the 1952 field season to delimit pumicite deposits along the Alaska Peninsula more amenable for use in pozzolan-portIand concrete.Because the Railroad belt has such a rigorous climate, insulation for new construction is of prime importance. Luring the Bureau of Mines, investigation of building materials all samples were submitted for chemical analyses as possible sources of raw materials for the production of rock wool, one of the best insulation mediums. Four areas having deposits of the required constitu¬ents were located as follows: Anchorage area, with Potter limestone and argillite; Cantwell-Windy area, with limestone and shale; West Fork of the Chulitna River area, with limestone and agrillite; and Homer-Seldoyla area, with Seldovia limestone and Homer clay. It was planned to take bulk samples of these formations and submit them for testing during the 1951 field season."

Mar 1, 1953

By David K. Hylbert

This study investigated stratigraphic and structural causes of roof falls in room-and-pillar drift coal mines in nine mines in eastern Kentucky. A contract modification provided for remote sensing studies in the Dunkard Basin of West Virginia and Pennsylvania. Results of stratigraphic and structural studies of an earlier contract (H0133018) were applied to several new mines. It was found that similar rock sequences contributed to unstable roof conditions. Structure contour and isopach maps were found useful In projecting these trends together with fence diagrams. Using Landsat imagery, a direct relationship was found between lineament direction and the trends of rock jointing, roof fall zones, "snap top" zones and sandstone channels in the examples cited. It was found that, by analyzing lineament intersections, from 50 percent to 65 percent coincided with roof falls.

Jan 1, 1980

By D James

Fletcher Challenge Limited through its subsidiary Grampian Mining Co Limited has carried out an ore evaluation of one of New Zealand's largest known deposits of ilmenite located at Barrytown on the West Coast of the South Island, New Zealand. The ilmenite is located in a beach sand environment which has previously been mined for gold. Two analytical techniques were developed to quantify the resource. Considerable difficulty was experienced in this phase of the evaluation due to the presence of major inclusions within the ilmenite grains. Wet and dry concentration circuits, utilising spiral, wet magnet, high tension and plate electrostatic separators have been designed to produce ilmenite from the ore. Studies to utilise the titanium content of the Barrytown ilmenite have been made. Recent work has been directed towards a titanium dioxide pigment process.

Jan 1, 1986

By Miguel Rutti

El presente trabajo señala la geología, litología y mineralización del yacimiento minero El Tapado del distrito Yanacocha, situado al norte de Cajamarca. Este se encuentra conformado por diferentes depósitos auríferos epitermales de alta sulfuración, los cuales se desarrollan dentro de un vulcanismo calco-alcalino de composición andesítica a dacítica de edad Mioceno y son correlacionables con la Formación Porculla del Grupo Calipuy. La geología del depósito está conformada por rocas porfiríticas (intrusiones) y flujos piroclásticos tales como tufos de cristales, tufos líticos y brechas piroclásticas afectados por eventos eruptivos de brechas freáticas - freatomagmáticas. Todas estas rocas han sufrido posterior alteración hidrotermal con ensambles típicos de sistemas tipo ácido-sulfato. La mineralización económica está controlada por procesos hidrotermales y se encuentra asociada a sílice masiva y sílice vuggy ( 1-10 g/t Au y estructuras de hasta 136 g/t Au ) y en menor grado sílice alunita y sílice granular (moderada a baja ley).

Apr 22, 2003

By T. Weatherwax

As part of a strategic research initiative at UBC to design and evaluate integrated underground mining and mineral processing systems, work has been done to determine how to utilize the coarse rejects of pre-concentration in the underground environment. An amenability study for nine orebodies from four of Xstrata Nickel?s Ontario operations evaluated both processing and waste disposal methods. The utilization of the rejects as a high quality backfill with minimal binder requirements has been identified as the preferred disposal method. Fill mixes utilizing the rejects in combination with classified tailings, full tailings, and cement were developed based on the geotechnical properties of the rejects. The mix designs were examined for both strength and rheological properties. The paper will present the results of the pre-concentration testwork, the design and strength testing of various mix designs for rejects from the nine ores and presents a conceptual design for an underground pre-concentration system based on this test work.

Jan 1, 2008

By M. C. Pietrobon

"A common problem in assessing the applicability of laboratory flotation data is determining how closely conditions during laboratory testing of the ore matches those that occur in a plant. Typical laboratory based investigations do not consider factors such as water quality, pulp temperature and the pulp chemical environment during both grinding and conditioning on laboratory flotation performance. Disregarding these important factors may seriously compromise the validity of conclusions based solely on laboratory experimental results. Furthermore, considering these factors during the flowsheet design stage in the development of new ore resources may reduce financial risk associated with building a new plant. A methodology is described here which embraces these factors in an attempt to bridge the gap between laboratory and plant. The methodology should be considered a vital first step in all laboratory based experimental programs and has implications for fundamental studies on the flotation behaviour of single minerals. This methodology increases the confidence with which findings of laboratory based studies can be transferred to the plant and highlights the effect of variables which may be accessible to manipulation in the plant.Pulp chemical parameters, such as pulp dissolved oxygen demand, pH, Eh, mineral oxidation and solution composition were manipulated in the laboratory by adjusting the duration of gas purging after grinding, the process water input and pulp temperature. A key finding was that matching of the laboratory pulp chemistry to the plant pulp chemistry was dependent upon oxidation after grinding. In turn, mineral oxidation was dependent upon the pH in grinding, water composition and the duration of oxygen purging after grinding. The methodology closely matched the dissolved oxygen demand and surface chemistry of laboratory and plant pulps."

Jan 1, 2002

By Berny Rivera

The paper point out the Galvanox process developed at the University of British to leach concentrates containing copper sulfide mixtures, mainly chalcopyrite. This patented process is based primarily on the galvanic interaction between chalcopyrite and pyrite, which allows chalcopyrite to be leached preferentially over pyrite. Under the correct process conditions, near-complete extraction of copper can be reached typically within twelve hours. This study will also show that this process is suitable to treat low grade copper concentrates (bulk concentrates) taking advantage of the selectively of chalcopyrite over pyrite, and the use of pyrite as a catalyst.

Sep 9, 2007

By M. Tangstad

Keywords: Pyrometallurgy, ROMA, Norway, furnace, fines The ROMA project is a competence project on optimizing the usage of raw materials and energy in the ferromanganese, silicon, and aluminium industries. One of the items investigated in this project is the effect of fines on the furnace, and the usage of agglomerates versus lumpy ore. From lab-scale experiments it is shown, that for the charge to agglomerate in the furnace, the charge has to be exposed to a temperature higher than about 1200°C, independent of fines content. The fines less than 1 mm also showed higher agglomeration properties, compared to 2?4 mm, which showed no agglomeration property at all. The properties of agglomerates are very dependent on the pre-treatment of the agglomerate. Sinter and pellets, which have been heated to high temperatures, show a better strength, but also a lower CO reactivity. Sinter also shows a lower melting temperature compared to the ore.

Jan 1, 2011

By R. O. Burt

"Gravity Concentration, the oldest form of Mineral Processing, remains of major importance to the Industry. Current applications of Gravity Concentration are briefly examined.The Paper details one approach to the development of a Gravity Concentration Plant, from laboratory and mineralogical techniques, through Pilot Plant testing, where applicable, to the actual design of the plant.INTRODUCTIONGravity Concentration, once the major method of concentrating minerals has, for much of the twentieth century been regarded, like the dodo bird, as obsolete. However, in more recent years it is enjoying something of a renaissance, and is once again being treated as a useful, economic alternative in the Mineral Processing Engineers' arsenal.An indication of the broad application of gravity concentration is the variety of minerals presently recovered. A list is given in Table 1; this list is not exhaustive."

Jan 1, 1984

By Laxman S. Sundae

A Bureau of Mines investigation was conducted to determine the effect of specimen volume on the apparent tensile strength of disks of St. Cloud Gray Granodiorite, Lithonia granite, and Rockville granite. The investigation used a technique developed by the Bureau to determine apparent tensile strength. Because the test specimens were selected without macroscopic defects, that is, cracks, joints, and planes of weakness, the strength variations are solely due to microscopic features. Several replications of each test were performed. Data for each set of specimens were fitted to a power law of the form y = axb, where y = apparent tensile strength, x = specimen volume, and a and b are constants. This power law is essentially a form of Weibull's theory. The average coefficients of correlation for St. Cloud Gray Granodiorite, Lithonia granite, and Rockville granite were 0.85, 0.53, and 0.78, respecitvely. In all cases a decrease in strength with increasing volume was noted; in the extreme case, a decrease of 40 pct was noted with an elevenfold increase in volume. The decrease in strength with increasing specimen volume is explained in terms of Weibull's theory.

Jan 1, 1974

By G Metzner, R Rodriguez, C Savage

OK Tedi Mining Ltd. (OTML) is in the process of optimising the concentrator performance. One aspect that has been recently implemented is an upgrade of the existing expert control philosophy on the grinding circuit and this will be the topic of this paper. Ore grinding in SAG mills is a multi-input multi-output (MIMO) process subject to several disturbances, most typical being quick acting disturbances such as changes in ore characteristics like hardness and particle size and slow acting disturbances such as ball charge variations and liner wear. The OTML SAG mills treat ore from diverse ore bodies and receive fresh feed subject to large changes in particle size. These circumstances make these mills particularly challenging to control. In this paper, a comparative analysis is presented between the performance of the OTML SAG mill #2 before and after the commissioning of a hybrid control strategy. The strategy uses Expert Knowledge combined with advanced disturbance rejection to reduce the variability of the main process variables, especially pressure and power. It further optimises the overall operation by driving the SAG mill #2 against process constraints (e.g. high power, high motor temperature and high scats recycle rate) and maintaining the operation at or near this point. This strategy is implemented by a combination of the manipulated variables (i.e. fresh feed tonnage and % solids) at any given time.The paper will present trends and a statistical analysis of the comparative results of the mill operation over a period of months, showing a 30% reduction in mill power / pressure variability and a 12% improvement in average power drawn. An increase in throughput was also observed, but cannot be conclusively attributed to the change in mill control due to other changes that were made to the SAG mill #2 during the period of comparison. An additional benefit includes better acceptance from the operators with improved consistency of the SAG mill #2 operation across shifts.The paper will also discuss further improvements envisaged in the continued optimisation of the grinding control circuit.CITATION:Savage, C, Rodriguez, R and Metzner, G, 2013. Hybrid process control strategy for the Ok Tedi Mining Ltd semi-autogenous grinding mill #2 - A comparative analysis, in Proceedings MetPlant 2013 , pp 202-214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By Ivo Dreiseitl, Kondratenko. Anatoly

"The second prime area within the Interoceanmetal Joint Organization exploration area named H22 was delineated in 2013 with the goal to ensure sufficient nodule reserves for profitable mining operations and processing.The knowledge base for area H22 has been obtained from archive materials. The geological situation can be characterized as follows: the sea bottom is represented by tectonic blocks oriented in a sub-meridional direction. According to swath mapping, the depressions (troughs) are contoured at depths of 4500-4600 m while the tops of horsts occur at 4300-4350 m. Volcanic relief occupies 6% of the H22 area; in the eastern part a multicone volcano was detected. Its area at the base is 153 km2. The maximum height of a cone above the base is 850 m. The crystalline basement composed by tholeiitic basalts of late Oligocene age is covered by about 100 m of sediments. Semi-consolidated to consolidated calcareous nanofossil sediments of the Marquesas formation are deposited on the basement. Higher up in the profile sediments of the Clipperton formation occur. They are represented by unconsolidated siliceous (Radiolaria, Diatom) ooze. Sediments containing calcium carbonate have not been detected. Where opaline silica (or CaCO3 if any) content is below 5%, the sediments belong to zeolitic clays or red pelagic clays. Grain size composition of the seabed and the near-seabed sediments in H22 classifies them into clayey silts."

Sep 1, 2014

By A Reid

The Late Archaean of South AustraliaÆs Gawler Craton contains significant potential for gold resources. The main targets of interest are migmatised gold style systems of which the Challenger deposit is the best known example. This deposit is one of the lower cost gold producers in Australia due to the high-grade, low-tonnage nature of the mineralisation. Structurally controlled, metamorphosed deposit styles are also possible throughout the Archaean of the Gawler Craton, including occurrences within reactivated shear zones. More typical, lower metamorphic grade orogenic gold styles are also possible within greenstone host sequences identified in the central and southern parts of the Gawler Craton.

Jan 1, 2007

Myths and misconceptions regarding cyanide in the mining industry are common. This is not surprising, given the other uses to which cyanide is, and has been put. Unfortunately, the economic benefits, largely due to the introduction of cyanide in towns such as Waihi are often unrecognized. In the current "green" environment, the New Zealand mining industry faces constant scrutiny and challenge. The use of cyanide in hard rock mining is one area which can stir the emotions of the public.   Cyanide can be transported, stored, used and disposed of in a safe manner. The modem mining industry has an excellent record regarding the safety and environmental issues relating to cyanide. Many of the fears relating to cyanide in the mining industry have proven to be unfounded. It is important that this reputation is maintained. This is possible given proactive and ongoing management of cyanide issues.

Jan 1, 1997

By A. G. Pasamehmetoglu, N. Celebi, K. Erarslan

A deposit evaluation system has been developed for a proposed new mine in the basin around Collolar in Turkey. It includes compositing, gridding and reserve estimation facilities and takes account of the economic value of the pit and the pit bottom elevation

Sep 1, 1991

By William R. Wessels

This report describes a field survey and laboratory investigation into the causes of failure of resiliently clad screen decks applied to coal preparation plants. Blinding of screen deck perforations and delamination of the resilient cladding are studied and mechanisms responsible for these failure modes are hypothesized. A laboratory test program to simulate the mechanisms was begun and abandoned when it became apparent that meaningful test results would require a substantially redirected effort. No meaningful test data was obtained from the laboratory simulation.

Jan 1, 1982

The 8 ft by 91/2 ft drive which joined No. 7 Shaft with Browne Shaft on the 1,480 ft level was extended from both ends and met at a point approximately 12,000 ft from No. 7 (2,000 ft from Browne).The surveying required for this 2 1/2 mile haulage drive called for greater accuracy than was obtainable from South Mine standard methods. Procedures and devices from published information were tried and modified as required to suit local conditions. Several new methods were applied and improved as the drive advanced. The control of angular, linear and level measurements was perhaps considerably in excess of the requirements, but this was offset by abnormally large discrepancies resulting from shaft plumbing. The accuracy of the final breakthrough, although not to the standard desired, was sufficient to complete the connection without inconvenience and added cost.INTRODUCTIONThe acquisition of the Browne Shaft leases in January 1962 presented the management of Broken Hill South Limited with the problem of transporting ore from these leases to its mill. It was eventually decided that diesel locomotivehaulage through a 2t mile drive on the 1,480 ft level between the two mines was the best solution. The drive was advanced from both ends after Browne Shaft was deepened by 80 ft to reach the 1,480 ft level horizon. Each end advancedabout 15 ft/day with the miners working three 7 hr shifts. Blasting was restricted to the end of the shift.The survey work involved five shaft plumbings and 78 theodolite stations in a traverse, underground and surface,of more than 5 miles. Because of the exceptional length of the drive, an unusually high degree of reliability was required.The aim was for a maximum error at breakthrough of 1 ft 1 in 30,000, and to secure this, precise methods of linear measurement were necessary. Shaft plumbing in particular posed special difficulties.

Jan 1, 1965

By Carlos León

El presente trabajo señala el proceso de optimización en la recuperación del cobre y molibdeno en la concentradora de Toquepala. La implementación y desarrollo de la remolienda del flujo de concentrado desarrollan un mayor grado de liberación, y por ende, una mayor recuperación del cobre y molibdeno en el circuito. Asimismo, el descarte de relave OK-50 ha permitido normalizar las recuperaciones de cobre y molibdeno en ciertas secciones de la flotación rougher de la planta, incrementando en la recuperación del cobre de 0.8% y 1.8% en molibdeno. Por ello, es factible mejorar las condiciones de operación de la planta a través del desarrollo de pruebas metalúrgicas llevadas adelante como un esfuerzo conjunto entre todos los integrantes del equipo Concentradora Toquepala.

Sep 13, 2001

By Glenn S. Dobby, Glenn A. Kosick

"Column flotation circuit engineering has matured to a good level of understanding regarding testing, scale-up and design. Some of the factors important to the process of implementing columns are addressed in this paper, highlighting the following issues• operating bias and the maximum achievable solids carrying rate for a column application.• internal circulating loads of full scale and pilot plant flotation columns• short-circuiting oflarge scale columns and the impact on separation selectivity• the number of stages in a column circuit and the impact on selectivity.The paper uses several case studies, from pilot plant to full scale implementation, to illustrate these design issues.1. IntroductionTen years ago, in 1984, there were very few column flotation installations world wide and the largest columns were about I . 5 to 2 m diameter or square. During the following decade there have been in the heighbourhood of 80 column installations that have been successful and profitable, as both retrofits and green-fields plants. Now, columns as large as 3 to 4 m are not uncommon. Examples of installations with many large columns include Escondida, with ten columns each at 4 m square, and P T Freeport Indonesia, with 21 columns: nine 3 m diameter columns, four 2.4 m diameter columns and, starting up in April I 995, eight 3.6 m diameter columns.During this growth period there have also been column installations that can be considered as failures. In the majority of these cases, the reason for their failure has been an insufficient installed capacity for applications where there is a high weight recovery of solids to the froth product These include zinc cleaning, copper cleaning and iron ore flotation (silica flotation from a feed that is 15 to 30 %Si02) An application with high weight recovery to the froth product makes column scale-up and circuit design more complicated. This is particularly so if a high degree of selectivity is also required while attaining a high weight recovery, which can happen with iron ore flotation in columns."

Jan 1, 1995

By Donald W. Baggs

This report describes economic mining feasibility studies conducted by the Bureau of Mines to estimate mining costs in the Porcupine mining area of the Juneau Mining District, southeastern Alaska. Investigations were conducted on the economics of three mineral deposit types: 1) massive sulfide deposits containing zinc, copper, and silver, 2) vein gold, and 3)disseminated gold. Cost estimates were developed using the Bureau of mines Cost Estimating S,-stem. Discounted cash flow rates of return were calculated using the Bureau of Mines MINSIM (mining simulation) computer program. Three sets of metal prices were used in the study based on recent historical price information. Underground longhole stope mining of a massive sulfide deposit containing 25 pct zinc. 1 pct copper, and 63.6 g/mt silver was found to be economic at high metal prices at a quantity of 13,200,000 mt ore. Cut-and-fill mining of a 26,400,000 mt massive sulfide deposit was found to be economic at medium metal prices. Open pit mining of a similar deposit was found to he economic at medium metal prices and 26,400,000 mt ore, or at high metal prices and 6,600,000 mt ore. Underground mining of a vein gold deposit was found to be economic at a grade of 17.1 g/mt medium metal prices and 1,320,000 mt ore. Open pit mining of a disseminated gold deposit was found to be economic at a grade of 1.71 g/mt medium metal prices and a quantity of 39,600,000 mt ore.

Jan 1, 1986