Search Documents

By Doug Smith, Gary Taylor, Paul Ogryzlo

"Uranium mining and processing typically requires large quantities of high-grade reactive quicklime for the neutralization and clean-up of contaminated mine water and mill process waste streams. Currently the Saskatchewan uranium industry’s lime requirements are being supplied from deposits located in Manitoba and Alberta, resulting in transportation costs, which equal or exceed the market value of the product. During the summer of 2001, the northern village of Pinehouse located 220 kilometers south of the Key Lake uranium mill, staked two previously discovered limestone deposits. The relatively shallow deposits, known as Missi Island and Sleeping Giant are located in close proximity to one another, approximately 35 km south of Pinehouse adjacent to highway 914. This paper describes the results of a scoping study carried out by AMEC for the development of the two deposits based on a seasonal limestone mine and a continuous 40,000 to 60,000 tpy wood fired calcining plant designed to supply all of the quicklime needs of the Saskatchewan based uranium industry. Also described are the results of calcining and customer acceptance testwork on samples of lime prepared from recent Pinehouse limestone drill core. The potential benefits of the project include a significant new source of revenue for the community of Pinehouse, lower lime costs for the Saskatchewan uranium industry and employment for northerners in the mining, processing and wood harvesting operations.IntroductionInterest in the Pinehouse/Massinahigan River area for limestone was precipitated by the results of a 1977 industrial minerals drill hole program by the Saskatchewan Department of Mineral Resources. These results led to the acquisition of land in the area by Missi Island Mines Ltd who carried out extensive exploration during the period 1978-1982. They discovered a deposit on the southwest side of the Massinihigan River thought to contain approximately seven million tonnes of limestone with an average grade of 94.5% CaCO3. Missi Island carried out preliminary feasibility studies and prepared an Environmental Overview Statement. However, in spite of positive recommendations, the project was dropped in the mid 1980’s."

Jan 1, 2003

By Ertugrul Alp

Alp & Associates - Who We Are ?? Canadian consulting company (1999-?) ?? Principal Consultant: Dr. Ertugrul Alp, P.Eng. ?? Over twenty-five years experience serving the chemical, mining, pulp & paper, energy, steel, and transportation industries, and government clients. ?? Ph.D. in Mechanical Engineering, University of Waterloo ?? Experience: ?? Westinghouse Canada, Atomic Power Division, Manager, Analysis and Modelling ?? Concord Environmental (later Bovar Environmental), Principal, Manager, Air Quality and Risk Assessment ?? Arthur D. Little, Associate Director, Safety & Risk Practice Leader in Canada ?? Member: NATO CCMS Pilot Project on Disaster Preparedness (1991-1993) ?? Chair: MIACC Risk Assessment Expert Committee, 1995-1999 ?? Member: MIACC Committees on Land Use Planning and Pipelines (1993-1998) ?? Member: CSA/Q850 Risk Management Standard Technical Committee ?? Member: CSA/Z1002 OHS Risk Assessment Standard Technical Committee ?? Member: CCPA/CSChE Process Safety Management Committee (1999-?) ?? Member: ISO-31000 Risk Management Standard Canadian Advisory Committee ?? Chair: CSChE Process Safety Management Committee (2005-2006) ?? Chair: CSChE Expert Committee on Risk Assessment (1999-2005) ?? CSChE 2007 Process Safety Management Award

May 1, 2008

By P. Wells, P. Quinn

"A moveable flotation miniplant was designed and constructed at the research laboratory of Inco Technical Services Ltd. to address the need for flowsheet development with a limited amount of ore (such as drill cores). It consists of one rod mill, two regrind ball mills, one vibratory screen, 24 flotation cells of various sizes and two Venturi aerated flotation columns. The setup has continuous monitoring capability for pH, dissolved oxygen, oxidation-reduction potential, conductivity and temperature in conditioning tanks and flotation cells. Various options regarding flotation reagents, circuit configurations, and fineness of primary grind and regrind can be readily evaluated. The throughput of the miniplant is 20 – 30 kg/hour ore.Unit operations such as flash flotation, magnetic separation and gravity concentration can also be evaluated as an integral part of an entire flowsheet development.This communication describes the basic design features of the miniplant and some examples of applications are given.INTRODUCTIONInco operates numerous mines in Sudbury and Thompson and will shortly bring the Voisey’s Bay mine into production. It has long been recognized that the ores from different mines or from different depths of the same mine can give different responses in flotation. There is a growing need to properly evaluate the ores before feeding the mill to maximize the return of the mine/mill operation. Inco Technical Services Limited at Sheridan Park, Mississauga, Ontario has developed a batch laboratory procedure to address this issue. The results are considered in the overall economical assessment of new mine operations.For ores that cannot be processed by the existing mill operations or that will be processed by a new mill, it is necessary to develop a flowsheet that can maximize the economical return of the mine/mill operation. While recognizing the importance and contribution of the laboratory batch flotation procedure, it does not generate reliable data for flowsheet simulation and design. A full-scale pilot plant campaign is normally required to obtain the design data but often this is not possible due to a limited amount of ore obtainable from the drill core. A small-scale pilot plant (mini pilot plant or miniplant) capable of processing 20-30 kg/h ore can provide this data prior to a full-scale pilot plant campaign. A miniplant can also be used to optimize the circuit configurations, reagent additions and recycle options of process water before pilot plant work and can be used to test a different flowsheet configuration for an existing mill before re-piping a plant circuit."

Jan 1, 2003

By B. W. Williams

The crack propagation behaviour of Zr-2.5Nb pressure tube material was studied through comparison of the measured behaviour with the predicted response from finite element analysis. Three-dimensional finite element simulations of compact tension specimens were performed using the crack tip opening angle as a fracture criterion to allow for crack propagation. To obtain reasonable agreement with the measured behaviour, it was important to capture both the anisotropic plastic deformation behaviour of the Zr-2.5Nb material through use of the Hill-48 yield criterion and damage due to void growth, nucleation, and coalescence through the use of a Gurson-based constitutive model in the simulations.

Jan 1, 2010

By D G. Boxall

As an alternative to heavy water cooling, reactors cooled by organic liquids are being actively developed in Canada under the sponsorship of Atomic Energy of Canada Limited. One of the areas in which development has been required is that of core materials. The factors affecting the selection of fuel canning and coolant tube materials are discussed. It is shown that S.A.P. is a potentially attractive material for these applications. The fabrication of fuel sheathing is discussed. Difficulties met due to large inclusions and blistering due to high hydrogen contents have been overcome by magnetic separation and vacuum sintering of the powders. High-quality tubes can now be produced by extrusion to finished size. A study has been made of the mechanical properties of fuel-sheathing tubes and bar stock. The stress rupture properties of the tubes subjected to uniaxial and biaxial stress have been determined. The biaxial stress tests were performed by internal pressurization. For times in excess of about 200 hours, the curve of stress against time to rupture is extremely flat. The secondary creep rates of

Jan 1, 1965

By Yum Xiaoquan, Turgut Yalcin

"A laboratory study was carried out to determine the potential role and effect of ultrasonic irradiation in the flotation of a Sudbury copper-nickel sulphide ore. The use of ultrasound was tested separately at the pulp preconditioning, collector conditioning and flotation stages. While no significant benefits were evident in the latter two cases, ultrasonic preconditioning of pulp improved the grade-recovery performance and had the prospect of reducing reagent consumption rates. Tests were conducted on both the normal and oxidized ore samples, and several variables were investigated, including ultrasound frequency (25 kHz and 45 kHz), ultrasonic power (up to 1.6 W/cm2), duration of ultrasonic treatment (up to 60 minutes), and the intensity of pulp agitation employed during the application of ultrasound. Ultrasound frequency of 25 kHz and duration of 15 minutes yielded satisfactory results. Changes were found to occur in the temperature, pH and Eh of the pulp during ultrasonic processing. The favorable effects of ultrasound observed in this study were attributed primarily to its surface cleaning capability.INTRODUCTIONThe use of ultrasound for the surface cleaning of objects is well known. Ore flotation is based essentially on the surface properties of minerals, and hence stands to benefit from ultrasonic treatment which may help restore mineral surface characteristics that might have been lost or modified through oxidation, etc. Expected outcomes of this method of treatment include improved flotation kinetics, higher recovery, better selectivity, and savings in reagent consumption, as has been demonstrated by various researchers (Aldrich and Feng 1999, Celik 1989, Ozkan 2002, Letmathe et al. 2002, Nicol et al. 1986)."

Jan 1, 2005

By Ludwig M. Strah

"Wear is a universal problem and is present in all cases wherein one weighted surface moves with or relative to another surface. A practical description of wear as applied to mineral processing plants is outlined.With the advent of higher material and maintenance costs, more attention is being focused on the field of wear resistant linings. The aforementioned is magnified today as the production facilities continue to be designed to handle larger daily capacities. These changes, higher costs and larger plant handling facilities have necessitated the introduction of different materials and designs to combat the never ending battle against wear.In order that wear be understood, it can be relegated to two specific types:1 - Mechanical Wear - due to movement of one loaded surface relative to another.2 - Chemical Wear - more easily defined as corrosionMechanical wearMechanical wear can be subdivided into two basic forms:A.,Material movementB.,Material impactMaterial movement Abrasion is the result of, as earlier stated, the straight move¬ment of one loaded material relative to another.Material impact Is the striking effect when a mass strikes another from various angles and at various speeds. Impact can be severe enough to permanently damage and distort the basic component installed to overcome impact."

Jan 1, 1983

By D. R. Spink

An historical background is presented to provide a basis for the lack of normally expected developmental effort over the first 20-25 years of viable zirconium production operations. This is followed by a description of developing technology, which is the result of years of research and piloting effort directed to the development of a more economical method to produce high-grade metallic zirconium. It is predicted that many of the process improvements described will have a significant impact on future zirconium production methods and consequently on future prices and markets.

Jan 1, 1977

By B. G. Cousins, B. O’Rourke, C. Spence

"Some non-flotation chemistries are added to flotation circuits directly and indirectly to control issues such as scaling and dust. Since the dosage levels are generally not very large, a standard laboratory float test may not be able to determine the effect a specific chemical has on the productivity of the flotation circuit. Hudbay and Ashland Water Technologies developed a laboratory testing protocol that uses kinetic float studies to test the effect of normal to extreme doses of antiscalant and dust chemistries (5 ppm to 500 ppm). Laboratory results indicate that this protocol helps to predict the potential interference that a particular chemistry will have on the flotation circuit.INTRODUCTIONFrom a chemical perspective, flotation is a very complex system involving more than the reagents used for flotation. Along with collectors, frothers, modifiers, suppressants and activators, there can be antiscalants for water treatment, dust suppressants used in the mining process, residual flocculants from recycled thickener overflows, grinding aids, and many other types of chemicals that are added upstream of a flotation circuit. Although these other chemicals are usually used at very low doses, it is important to know if they affect the flotation process detrimentally in the event of a spill or a build up from recycled water.Laboratory flotation testing of these chemicals characterizes their effects, but testing at expected doses in the float can mask the effects of the chemicals in the plant. Also, simple tests that do not measure the kinetics of flotation do not reveal the effects the other chemicals have on the flotation circuit. Thus, a new flotation protocol was needed to expose the full effects of chemical additives and to assist in choosing the chemical with the lowest potential for a negative effect.FLOTATION KINETICSMeasuring recovery kinetics in a laboratory flotation cell is a well-established procedure: analyzing concentrates taken in a timed sequence to determine the recovery rate of individual cells in a flotation circuit. The recovery from the early flotation cells are a true measurement of how well a flotation chemical is performing. The principles of kinetics can be mathematically determined by the following functions (Houston, 2006):"

Jan 1, 2013

By G. Griffiths

"P. WitteWitteck DevelopmentThe implications of using a tower mill for fine grainding in the ore processing of tailings are significant. What can those of us who are in a research and development situation do when we recommend this equipment to a client? When this prototype is placed on stream next to a conventional grinding mill as you suggest how do we estimate the power requirements and the grind which will be achieved?ReplyLet me explain the Macassa circuit. The tower mill here was running in parallel with one of the ball mills. The feed entering the tertiary system is scalped in a primary cyclone. The finial cut is made in a secondary cyclone. The actual feed to the tower mill is the underflow from the two cyclones and was split to the ball mill and tower mill. During the testing we were unable to isolate the tower mill to determine its contribution to the overall system. We then started to look at the amount of material produced across the mill. We entered the mill at between 17% and 20% finished material and exiting at between 36% and 40% finished material. We were able to project, with a high efficiency classification system, and arrived at 6 Kwh/ton or better."

Jan 1, 1984

By Changping Hu, Keqin Tan

In 1937, the Metallurgical Department of the National Resources Committee established a copper refinery plant (predecessor of the Chongqing Smelter) in Changsha, Hunan Province, China. The blister copper produced by a local copper smelter was casted as anode for electrorefining. The plant, with a capacity of one ton of electrolytic copper per day, was designed and tested in 1937. At the trial production stage, a total of 9 tons of cathode copper was produced. The plant was formally put into operation in July 1938. In the same month, more than 20 tons of electrolytic copper with purity over 99.9%Cu was produced. This was the first batch of electrolytic copper produced in China. In 1939, China’s largest non-ferrous metal smelting plant, Fengtian Gold Mine Refining (predecessor of the Shenyang smelter) was completed and put into operation in Shenyang, mainly producing nonferrous metals such as gold and silver, as well as copper and lead. In 1939, the Kunming copper smelter (predecessor of Yunnan Smelter) was completed and put into operation. The plant equipment, imported from the United Kingdom, was designed to produce 1,200 tons of electrolytic copper annually. In 1943, Jiatong smelter (predecessor of the Shanghai Smelter) became the 4th domestic cathode copper producer. Since 1949, China has gradually established a large copper industry. These developments are discussed in this paper. Today, China operates nine out of the twenty largest copper refineries in the world. With a total capacity approaching 9 million tons of copper per year, China has the world’s largest copper refining capacity. INTRODUCTION China is a country with a long history of copper mining. The earliest smelter in China in recent times was the Shanghai Smelter, which was built in 1912. From then until 1949, China successively built Chongqing Smelter, Kunming Smelter and Shenyang Smelter. The world's first copper electrorefinery was the Pembrey refinery built in the UK in 1869 (Lu, 1999). However, it was not until 69 years later that the technology was spread to Changsha, China.

Jan 1, 2019

By Colin Hardie, Erik Bartsch, Guy Comeau

"The Xstrata Nickel Raglan Concentrator, located at the northern limit of Quebec’s Nunavik region has been in operation since 1997. Originally designed to process 800,000 tonnes per year of high grade nickel ore, plant capacity is currently approaching 1,200,000 tonnes per year due to an Optimization Project (FAG to SAG conversion) in 2005 and many recent processimprovements.In 2006, the Raglan Metallurgical Group with assistance from the Xstrata Process Support group decided to make SAG control one of its priorities in order to further increase throughput and improve stability. The original primary mill control logic delivered by the Optimisation Project in 2005 consisted of a simple PID loop controlling the mill charge (bearing pressure) through feed rate changes. Due to the multivariable, non-linear and disturbance dominated nature of the SAG circuit it was quickly found that this traditional PID control strategy was not able to adequately control the mill; resulting in poor stability, frequent operator interventions and less than optimum performance.This paper describes the successful integration of advanced field systems such as mill feed image analysis (Wipfrag) and crusher gap controller (ASRi), into a multi-variable fuzzy logic SAG mill controller. The process of how a strategy for control was developed and implemented directly in the existing control system (exploiting standard system capabilities) is discussed. It is also shown how this approach has provided mill automation which is simple, robust (despite erratic feed characteristics), and delivers both an increase in throughput and a reduction of variability.INTRODUCTIONOriginally commissioned as a Fully Autogenous Grinding (FAG) circuit in 1997, preparations to convert the Katinniq Concentrator Mill to SAG had in fact commenced as early as 1999, but were halted owing to alternative process improvements which achieved up to 1Mtpa as early as 2000. Up until this time, plant process controls had remained more or less static; modifications having been limited to those required by new equipment. Primary mill process controls and related measurements were at this stage limited to:"

Jan 1, 2008

By J. S. Stewart

THE Mackenzie River Valley proper extends from Great Slave lake to the Arctic ocean (see map, Figure 1). From Fort Providence, near Great Slave lake, to Aklavik, near the Arctic coast, the distance by river is 1,000 miles. This will give some idea of the extent of the region. Throughout the length of the river valley, the Precambrian complex rocks are overlain by unaltered sedimentary rocks several thousand feet in thickness. These sediments are dominantly marine and Palaeozoic in age. In places, the Palaeozoic strata are overlain unconformable by Cretaceous an Tertiary sediments. The strata have been folded and, in general, the inclination of the beds to the horizontal is comparatively gentle. Here, then, we have the essentials for potential oil fields covering an area over 1,000 miles in length. This is probably the largest comparatively unexplored potential petroleum region in North America, and surface evidences of oil in the form of seepages occur in several places. Many of these seeps were known to the early explorers, and the first Geological Survey report on the Mackenzie River region, containing the results of field work carried out by R. G. McConnell in 1887-88, noted the petroliferous character of the Devonian strata and the indications of petroleum(l). This region is, however, handicapped by distance from markets and sources of supply of materials; by lack of modern transport facilities; by short season for river transport, and mountainous country separating the valley from the Pacific seaboard; and by the long winter season with weather that makes outdoor work difficult. These factors have tended to discourage the enthusiasm of would-be promoters, and so development in this region has been slow In 1920, a test well drilled about fifty miles northwest of Fort Norman discovered oil in commercial quantity, and three additional wells proved a small area to be productive.

Jan 1, 1944

By F. A. McLean

At the Annual Western Meeting held at Blairmore, Alta., October 1924, the writer presented a paper drawing attention -to the advantages of portable gas-driven equipment for developing isolated mining properties. This type of equipment was at that time practically in its infancy and the details of results actually accomplished were somewhat meagre. During the last year or so a number of these plants have been installed so that it is now possible to offer more definite information regarding the actual mining progress accomplished with such plants and their cost of operation in various parts of the country. This paper has been written with the idea of reviewing the work done during the past year, and to supply data which may be of interest to those wh9 are confronted with the problem of selecting equipment for development or assessment work. Because drilling operations play such an important part in mining, one of the first problems that usually confront the prospective? mine owner is the selection of the proper com-pressed-air plant. The size and type of equipment and the method of driving it require careful consideration. The size and type of equipment is determined largely by the funds available, transportation facilities, and the speed with which the programme of development is to be carried out. The selection of the proper method of drive usually depends on local conditions, such as the relative cost of various fuels, and has an important bearing on operating costs.

Jan 1, 1926

By J. C. Gathje

Newmont&apos;s Phoenix Project is located near Battle Mountain, Nevada and is scheduled to produce copper concentrates containing high precious metal values. High temperature pressure oxidation (PDX) of the concentrates was considered as a treatment option during process development. The metals content in Phoenix concentrates range from: 15-25% for Cu, 1-10% for Zn, 0-2% for Pb and ?27% Fe. The precious metals content of the Phoenix concentrates can range up to ?300 g/t Au and >3,000 g/t Ag. As a consequence it was necessary that any process for consideration should have the capability of recovering both the copper and precious metal values. Typically, gold can easily be leached from the autoclave discharge solids, but silver is chemically bound with the jarosite formed and cannot be directly leached. Laboratory investigations led to the development of a patented PDX process that minimizes the formation of jarosite so that the silver can be leached easily along with the gold. The process was confirmed with extensive pilot plant testing. Excellent solution extraction of copper and zinc was achieved, and both iron and lead were precipitated in the PDX residue. The process produces clean PDX discharge liquors with very low iron concentrations. As an example, conventional PDX techniques resulted in pregnant liquors containing ?5 g/L Fe. However, the Newmont process, which controls the iron and sulfate species, achieved high iron precipitation in the PDX solids and pregnant liquors containing <0.5 g/L Fe. High gold and silver recoveries were achieved by direct cyanidation of the PDX solids. This process has the added benefit of producing PDX solids that demonstrate superior settling and filtration characteristics.

Jan 1, 2006

By Weng Fu, James Vaughan, Stefan Lakemond

Uranium bearing copper sulphide flotation concentrates produced from iron oxide copper gold uranium (IOCG–U) ore contains radionuclides such as 238U, 230Th, 210Pb, 226Ra, 210Po, which have the potential to reduce their marketability, thus posing a challenge to the industry. Thus, a two–stage leach process has been proposed in this study. In first stage, a sulphuric acid leach process effectively dissolve most of the 238U and 230Th into solution, but other radionulclides (mainly 210Pb, 226Ra and 210Po) remain associated with copper sulphide minerals owing to their low solubilities in sulphuric acid solution. In the second leaching stage, the use of methanesulfonic acid (MSA, CH3SO3H) is investigated to selectively dissolve the 210Pb, 226Ra and 210Po from the residue of the first stage. The results indicate that 96% of 238U, 87% of 230Th, 90% of 210Pb, 86% of 226Ra and 17% of 210Po are dissolved using 3 mol/L MSA solution at 90°C for 3 hours, which represents a dramatic decrease in the radioactivity of the copper concentrate. INTRODUCTION Australia is host to one of the largest iron oxide copper–gold–uranium (IOCG–U) deposits in the world. Most of the value in these deposits is associated with copper. In mineral processing, the gangue minerals are separated from copper sulphide minerals that report to a copper flotation concentrate. However, due to the strong association of uranium with copper minerals and hematite, even clean copper concentrates can contain significant amounts of uranium (238U) and its radioactive decay elements, of which thorium (230Th), radium (226Ra), lead (210Pb), and polonium (210Po) are the long life radionuclides. These hazardous radionuclides negatively affect the marketability of the copper concentrates. Customer copper smelters in China, Japan and Europe may consider the radionuclides penalty elements or may not be able to process the feed. Therefore, there is a strong motivation to remove radionuclides from copper concentrates at the mine site before shipping to custom smelters in global market. Hydrometallurgical leaching has been widely employed to remove radionuclides from different kinds of minerals such as copper concentrates (Ragozzini & Sparrow, 1987), zircon concentrates (Aral, Sparrow, McDonald, & Norgate, 2007), and coal ash (Lei, Qi, Sun, Xu, & Wang, 2014). Leaching using sulphuric acid (H2SO4) solutions is the most widely used process for the extraction of uranium from uranium ores due to the relatively low cost and wide availability of the acid (Bhargava et al., 2015; Gilligan & Nikoloski, 2015). The leach process involves treating ground ore slurry with sulphuric acid at elevated temperatures (typically 60–90 °C) under oxidising conditions in order to convert the uranium in the minerals 2+ from the relatively insoluble tetravalent form (UO2) into water–soluble hexavalent state (UO2), which then complexes with SO42- and forms UO2(SO4)22- in solution. The uranium oxidation is generally carried out in the presence of ferric ion (Fe3+), regardless of the reagent and oxidant used. The most commonly used oxidants for uranium include sodium chlorate, pyrolusite and oxygen (Ring, 1980). These oxidants act indirectly by converting ferrous sulphate, formed by the oxidation reaction of UO2 in slurries, into ferric sulphate. The presence of Fe–containing gangue minerals such as hematite in the ore usually provides sufficient Fe required for the oxidation of UO2. After sulphuric acid leaching, the locked thorium (230Th), radium (226Ra), lead (210Pb), and polonium (210Po) elements are chemically liberated from hematite and uranium mineral grains (Ciobanu, Wade, Cook, Schmidt Mumm, & Giles, 2013). However, the extraction rate of radium (226Ra), lead (210Pb), and polonium (210Po) in sulphate solution is very low due to the limited solubilities of (Ra, Pb, Po)SO4 (Bagnall & Freeman, 1956; Liu & Papangelakis, 2006; Nikitin & Tolmachev, 1933).

Jan 1, 2019

By N. H. Grace

"IntroductionDURING the past half century, the economy of Western Canada was largely centred on agriculture. However, the impact of World War II has led to an acceleration in the development of a variety of natural resources so that, today, Western Canada is experiencing great industrial development. Consequently, the availability •of low-cost energy assumes prime importance. In the final analysis, industrial growth and expansion are intimately linked to the energy resources.Coal ReservesHas Western Canada adequate coal reserves to meet the present accelerating demand for power in the days that lie ahead? This question must be answered before detailed consideration can be given to the probable patterns •by which various energy sources in Western Canada may be expected to meet the expanding demand. Figure 1 indicates the extent and distribution of the Canadian coal reserves, the data having been prepared by Dr. B. R. MacKay for the Royal Commission on Coal in 1946 (1). The amount of readily recoverable coal is listed as one-half the quantities shown on the chart. It is interesting-to note that upwards of 90 per cent •of the Canadian coal reserves .are located in the three most westerly Canadian provinces. It has been estimated that the coal reserves, at the present rate of mining, would be adequate for about 3,000 years. Consequently, it may be concluded that the coal •reserves in Western Canada •are indeed adequate to meet tremendous energy demands for many centuries. When the oil and natural gas have been exhausted, the great coal reserves will still be available."

Jan 1, 1953

By C. J. R. Braithwaite, Giancarlo Rizzi

"The Navan zinc-lead ore deposit (70 million tonnes) is hosted principally (97%) by the Meath Formation (Lower Carboniferous, Courceyan, Navan Group), comprising a lower, mainly carbonate mudstone unit, the Stackallan Member, and an upper grainstone-dominated unit. TheStackallan Member, about 60 m thick, comprises about 35 peritidal cycles including an oolitic grain-stone interval. Grainstones forming the upper part of the formation, about 150 m thick, comprise at least six shallowing-upward ramp cycles. Emergence horizons are indicated by subaerial dissolution surfaces, in situ breccias, and a single palaeosol.Most dolomitization at Navan is con?ned to the Meath Formation. The linear dolomite body,trending NE-SW, has a ?attened, laterally limited, tabular geometry in cross-section, suggesting that dolomitizing ?uids initially rose vertically, cross-cutting stratigraphic and sedimentological bound-aries, although ?uid ?ow was subsequently controlled by these features.Three stages of dolomitization are indicated by textural relationships, cathodoluminescence (CL),oxygen isotopes, and ?uid inclusion data. Stage 1 crystals, with generally dully luminescing cores and up to six overlying subsidiary zones, are the main replacive phase. Crystal surfaces are commonly corroded and overlain by bright stage 2 rhombs (which also form new nuclei lining molds and fractures). Three subsets of zones are present in stage 2 crystals: bright, non-luminescent, and dull; these are locally separated by additional corrosion surfaces. Stage 3 comprises relatively large baroque crystals, generally dully luminescent but with up to seven sub-zones. Isotopic and ?uid inclusion data suggest growth of successive stages from waters which became progressively hotter(60°–160°C).The distribution of the ores follows the dolomite trend. Ores were precipitated between Stages1 and 2 of dolomite growth, following Stage 2, and also during the nucleation and growth of Stage3 crystals. Dolomitization and mineralization appear to have been temporally and genetically related. The cyclic sedimentation of the host rocks, which accentuates lithological and petrographical contrasts between depositional units, controlled dolomitization. The relationship between dolomitization and mineralization, which is closely associated with faults, provides powerful exploration criteria. The recognition of these features in limestones elsewhere in the Irish ore ?eld may point toward unrecognized zinc-lead prospects."

Jan 1, 1997

By C. J. R. Braithwaite, Giancarlo Rizzi

"Abstract-The Navan zinc-lead ore deposit (70 million tonnes) is hosted principally (97%) by the Meath Formation (Lower Carboniferous, Courceyan, Navan Group), comprising a lower, mainly carbonate mudstone unit, the Stackallan Member, and an upper grainstone-dominated unit. The Stackallan Member, about 60 m thick, comprises about 35 peritidal cycles including an oolitic grainstone interval. Grainstones forming the upper part of the formation, about 150 m thick, comprise at least six shallowing-upward ramp cycles. Emergence horizons are indicated by subaerial dissolution surfaces, in situ breccias, and a single palaeosol.Most dolomitization at Navan is confined to the Meath Formation. The linear dolomite body, trending NE-SW, has a flattened, laterally limited, tabular geometry in cross-section, suggesting that dolomitizing fluids initially rose vertically, cross-cutting stratigraphic and sedimentological boundaries, although fluid flow was subsequently controlled by these features. Three stages of dolomitization are indicated by textural relationships, cathodoluminescence (CL), oxygen isotopes, and fluid inclusion data. Stage 1 crystals, with generally dully luminescing cores and up to six overlying subsidiary zones, are the main replacive phase. Crystal surfaces are commonly corroded and overlain by bright stage 2 rhombs (which also form new nuclei lining molds and fractures). Three subsets of zones are present in stage 2 crystals: bright, non-luminescent, and dull; these are locally separated by additional corrosion surfaces. Stage 3 comprises relatively large baroque crystals, generally dully luminescent but with up to seven sub-zones. Isotopic and fluid inclusion data suggest growth of successive stages from waters which became progressively hotter (60°-160°C).The distribution of the ores follows the dolomite trend. Ores were precipitated between Stages 1 and 2 of dolomite growth, following Stage 2, and also during the nucleation and growth of Stage 3 crystals. Dolomitization and mineralization appear to have been temporally and genetically related. The cyclic sedimentation of the host rocks, which accentuates lithological and petrographical contrasts between depositional units, controlled dolomitization. The relationship between dolomitization and mineralization, which is closely associated with faults, provides powerful exploration criteria. The recognition of these features in limestones elsewhere in the Irish ore field may point toward unrecognized zinc-lead prospects."

Jan 1, 1997

By Peter Silveston, Earl Shannon

Process-oriented experiments on the use of coal as an adsorbent for certain soluble components of sewage are described. The capacity of Canadian coals for these components was less than 0.1 per cent by weight for the highest concentration at which these components could be expected to be found in domestic sewage. This is much less than values reported in the past. A pronounced selectivity between components was observed. Experiments on bacteria removal in beds of coal, regeneration of spent coal to restore adsorption capacity and COD contributions of coal are reported in the paper. The simple application of coal as an adsorbent does not seem promising.

Jan 1, 1970