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By I. M. R. Duarte, J. A. Rodrigues-Carvalho, F. R. S. Rosa, A. B. Pinho

"This paper aims to contribute to the knowledge of the mechanical properties of the shales and greywackes which constitute the flysch-type deposits of the Baixo Alentejo Flysch Group, in the south of Portugal. These formations are flysch-type deposits constituted by sequences of usually thick greywacke beds alternating with thin shale beds, which include sometimes intercalations of conglomerate beds. All the sedimentation of these flysch formations was controlled by tectonics. At the same time, should have occurred along with the first Hercynian deformation phase, a low-grade metamorphic event (chlorite zone), that affected these flysch deposits. This study highlights the influence of anisotropy and heterogeneity of these flysch rocks on their physical and mechanical characteristics. The anisotropy verified in some physical properties and on mechanical properties, due to the foliation makes difficult the sample preparation for the laboratory tests. Besides, it induces a scattering of the properties values measured, as for example, the strength and the deformability. The heterogeneity is related to the main features of these geological formations, which are constituted mostly by thinly stratified greywackes and shale beds, which sometimes may affect the results of the laboratory tests making them less representative. The study is made by using both shales and greywackes that constitute these flysch-type deposits in order to evaluate their geotechnical properties, mainly of the shales. Samples of these two rock materials, are tested accordingly a laboratory testing programme, which includes which included mineralogical analysis (X-ray diffraction), physical tests (bulk density, porosity, and void index) and mechanical tests (uniaxial compression, and deformability tests). INTRODUCTIONOne of the factors that most influence the geomechanical behavior of rocks, as well as rock masses is the anisotropy. The word anisotropy comes from two Greek words ""anisos"" (meaning uneven) and ""tropos"" (meaning direction). A body or material is considered to be anisotropic, where the same property has different values depending in which direction it is measured, therefore, an anisotropic material is one whose magnitude of the properties depends on the direction in which these are studied or measured. Otherwise, it is about an isotropic material. However, the fully isotropic materials are quite rare in nature."

Jan 1, 2015

By Fabio Terzi

In this investigation some preliminary results are reported about the electrochemical oxidation of CO using goldbased encapsulated nanoparticles grafted on conducting substrate. The investigation has been planned in four steps: 1. production of Au(111) substrate and modification with self assembled monolayers; 2. synthesis and embedding of nanoparticles; 3. grafting of encapsulated nanoparticles on electrode substrates; 4. investigation of CO electroxidation on the modified electrode. The systems were characterized by means of various techniques (spectroscopic, microscopic, and electrochemical methods), obtaining information about SAM's structure and morphology, size and composition of nanoparticles and electrochemical behavior of modified electrodes.

Oct 1, 2003

By Claudio Rocha Rosales

"Peñoles is a mining group with integrated operations for the smelting and refining of non-ferrous metals, and it is also a chemicals producer. Peñoles is the world’s foremost producer of refined silver, metallic bismuth and sodium sulphate. It is also the leading Latin American producer of refined gold, lead and zinc. The Met-Mex Peñoles Zinc Plant commenced operations in 1973 with an annual production capacity of 105,000 t/y zinc. Since then, production capacity has increased, and at present, it stands at 240,000 t/y zinc. In this paper, the leaching process and particularly the operation of the jarosite circuit is reviewed, specifying process improvements to treat high iron calcines.INTRODUCTIONTwenty years ago the Electrolytic Zinc Plant in Peñoles was treating high quality zinc concentrates with low concentrations of iron (~7.5 wt.%) and silica (1.8 wt.%). Nowadays the quality of zinc concentrates is poor with a typical iron content of around 11 wt.% and silica at 2.0 wt.%. This has created numerous processing problems in our roast-leach-purification- electrolysis sections. In order to meet customer requirements it is necessary to find processing solutions to assure the operational continuity of the plant. These processing solutions are the focal point of this paper.REVIEW OF THE LEACHING PROCESSThe purpose of the leaching process is to recover the metals, mainly zinc, through a series of extraction stages with sulphuric acid solutions, which progressively increases the zinc dissolution. After the series of acidification stages, the solution, which is rich in iron, is sent to the jarosite circuit to separate zinc from iron (Garcia & Valdez, 1996). The first step of the leaching process is the neutral leach circuit which produces a zinc sulphate solution that is sent to the purification section for the removal of impurities such as cadmium, cobalt and copper. Then this solution is sent to the tank house to feed the electrolytic cells."

Jan 1, 2016

By I. Orford, V. Rozon

"The Sä Dena Hes Joint Venture Mill was designed to process 450,000 tonnes per year of ore grading 11.3% lead and 13.2% zinc.Run of mine ore is crushed in a jaw crusher and then ground in a closed circuit SAG mill and ball mill. A standard differential float in conventional flotation cells produces quality lead and zinc concentrates. Dewatering of concentrates is achieved using high rate thickeners, lamella clarifiers and pressure filters. Process water is 100% recycle.Plant design was based on metallurgical test work performed on drill core samples. The plant is operating at better than design specifications.INTRODUCTIONSä Dena Hes Joint Venture was formed in 1989 to develop the Sa Dena Hes lead/zinc sulphide mine, located approximately 45 km north of the Town of Watson Lake, Yukon. The mine is owned by a Joint Venture partnership between the operator, Curragh Inc. (87.5%) and Hillsborough Resources Limited (12.5%).The project was completed in a record ten months, working throughout the severe Yukon winter and through an abnormally wet spring and summer. The first truckloads of concentrate were shipped from the mine on August 1, 1991.The mill currently processes 550,000 tonnes of ore per year grading 6.9% lead and 11.5% zinc. Ore is crushed in a jaw crusher and ground to 60% passing 75 microns in a closed circuit operation of one SAG mill and ball mill. Using conventional flotation cells a 150,000 tonnes of concentrate is produced in a year with lead concentrate grading 78% lead and a zinc concentrate grading 60% zinc at overall recoveries of 89% and 90% respectively.Concentrates dewatering is accomplished using high rate thickeners, clarifiers and pressure filters. The lead concentrate and zinc concentrate contain 5.4% water and 7.8% water respectively. Concentrates are trucked to Skagway, Alaska for subsequent shipping to overseas smelters."

Jan 1, 1993

By Ken McClure, Alex Day

Located North of Williams Lake British Columbia, Gibraltar Mine is the fourth largest open pit Copper mine in North America. Gibraltar commenced Copper concentrate production in 1972 with a mill throughput rate of 30,000 tons per day. A series of expansion projects, including installation of a second SAG mill with variable speed drives in 2013, has increased mill throughput to 85,000 tons per day. Over the past 24 months, Gibraltar Mine in partnership with Spartan Controls has executed several advanced process control programming projects culminating in the implementation of a Continuous Speed Controller (CSC) for the most recently installed SAG mill. This paper covers development and results for the SAG mill speed controller. INTRODUCTION In January 2016, the price of Copper fell below $2.00 USD per pound, the lowest price in 7 years. Gibraltar Mine faced a significant challenge; how to maximize profit in an environment where capital spending was not an option. An opportunity was quickly identified to improve performance through increased automation and advanced control of the grinding processes. Beginning in March 2016, Gibraltar Mine partnered with Spartan Controls to introduce Advanced Process Control (APC) to the grinding circuits. The collaboration between metallurgical and process control engineering disciplines proved to be effective for achieving gains in throughput, reliability and productivity for the mill process. The Gibraltar milling facilities include 2 grinding-flotation plants for concentration of chalcopyrite ore with throughput rates of 58,000 tons per day (Concentrator 1) and 38,000 tons per day (Concentrator 2). Each of the two concentrators has a 34’ diameter SAG mill powered by 2 GE 4800 kW synchronous electric motors. For SAG 1 (in concentrator 1), power is transmitted through 2 Eaton Airflex clutches. For SAG 2 (in concentrator 2), the motors are driven by 2 TMEIC Variable Frequency Drives (VFDs). All programming is done using DeltaV, which Gibraltar uses as its Distributed Control System (DCS) and Human Machine Interface (HMI).

Jan 1, 2019

By Michael T. G. Brown

Syncrude Canada Ltd. has recently completed construction of its ambitious tar-sand mining and processing facilities at Mildred Lake, Alberta. The Syncrude site is approximately 48 km (30 miles) north of Fort McMurray near the west shore of the Athabasca River. The Syncrude operation involves the open-pit mining of approximately 270,000 tonnes (300,000 tons) of tar sand daily using draglines and a conveyor system. Bitumen is extracted from the tar sand, upgraded to oil-gas and transported to refineries in Edmonton and other locations for final processing . The Beaver Creek Dam forms part of the mining facilities for the Syncrude tar-sand mining operation. Water from Beaver Creek is diverted from the open-pit mine site south to the Athabasca River via Ruth Lake and the Poplar Creek Dam. General site layout is shown on Figure I . Design of the dam was completed by R. M. Hardy and Associates Ltd. of Edmonton, Alberta (now Hardy Associates (1978) Ltd) . Construction was undertaken during the summers of 1974 and 1975 under the direction of Canadian Bechtel Limited, managing contractors for Syncrude Canada Ltd. Total length of the dam is approximately 2.8 km (1.7 miles), with a maximum height in the order of 16 m (50 ft) The Beaver Creek Dam is located in a broad, flat, poorly drained valley. About 50 per cent of the site is covered with treeless peat deposits, which ranged in thickness from in excess of 5 m (15 ft) at the east end of the dam to less than 1 m (3 ft) at the central portion. The peat deposits overlie Pleistocene meltwater sediments on top of clay/clay shales of the Clearwater Formation and the tar sands of the McMurray Formation. The peat deposits and high groundwater levels at the site combine to make the excavation and construction of a conventional rolled clay cutoff impractical. For these reasons, the slurry cutoff trench technique was utilized to produce an efficient and effective seepage cutoff under various sections of the Beaver Creek Dam .

Jan 1, 1979

By Charles S. Ney

"ZINC-LEAD REPLACEMENT deposits straddle the steep-sided valley of Kicking Horse River at a point three miles east of Field, B.c., in Yoho National Park. The Monarch orebodies extend into Mt. Stephen on the south side of the valley, and outcrop at two points, 1,000 and 1,200 feet above the valley floor. The Kicking Horse deposits are in Mt. Field, on the north side of the valley, and they outcrop 200 feet lower.The East Monarch outcrop is said to have been discovered in 1884 during construction of the Canadian Pacific Railway. The larger West Monarch outcrop, 700 feet west of the original discovery, was not reached till 1917 because of its nearly inaccessible location on the cliff face.The Kicking Horse mine was staked in 1906. Little development was done for several decades, and mining was not commenced till 1935.At the East Monarch, mining was commenced soon after location, and several thousand tons of ore were shipped prior to 1912. At this time a gravity concentrator was installed. This was operated till 1924, and a total of 42,000 tons of ore were mined, including about 10,000 tons from the West Monarch. The period from 1928 to 1935 featured flotation milling and the mining of 265,000 tons of ore, mostly from the West Monarch orebody. Intensive exploratory development was carried out in both Monarch and Kicking Horse from 1935 to 1946. Production from both mines in this period totalled 380,000 tons. From 1947 to the time of closure in 1952, considerable new ore was found in both mines and 185,000 tons were milled. Immediate possibilities for finding ore in the Monarch were considered exhausted. Kicking Horse orebodies are known to persist with a low grade of zinc. Total production from the two mines amounts to 842,500 tons grading approximately 7 per cent lead, 10 per cent zinc, and 1.2 ounces per ton silver."

Jan 1, 1949

By L. Jones, S. R. Lawrence, A. R. Holloway

Whilst dense medium separation is best known for its ability to concentrate diamond and coal deposits, the process is now being employed in southern Africa as a pre-concentration step to improve the economics of platinum group metal and nickel ores. DMS plants built for these industries (such as the 1600tph unit at Tati Nickel, Botswana), are spearheading an expansion in this area by reducing mine and process operating costs yet maintaining economic metal recoveries. This paper provides an overview of DMS technology and examines the economic benefits available to North American operators and projects, with recent case studies as reference.

Jan 1, 2009

By Gurinder Kaur

Selenium (Se) based materials find wide applications in rectifiers, solar cells, photographic exposure meters, data storage devices, xerography and anticancer agents. They are also used in the glass industry to eliminate bubbles and remove undesirable tints produced by iron. In addition, Se is highly reactive towards a wealth of chemicals that can be potentially exploited to convert Se into other functional materials such as CdSe, ZnSe, Ag2Se. Here, we report a review of structural investigations of Se based materials in glassy and nanostructured forms. Glasses having varying amounts of Se and Tellurium (Te) were doped with group IV and V elements such as antimony and tin. Structural changes accompanying the composition variation were characterized with x-ray photoelectron spectroscopy, differential scanning calorimetry and x-ray absorption near edge spectroscopy. At the same time Se-Te nanoalloys were synthesized in aqueous micellar phase using Na2SeO3/Na2TeO3 as the Se/Te source. Morphology change from nanoparticles to nanoribbons was investigated using Scanning and Transmission Electron Microscopy (SEM/TEM) techniques. Structural investigations were also done for well defined morphologies of Se based nano-biomaterials obtained in the presence of water soluble protein bovine serum albumin (BSA).

Aug 1, 2013

By A. Consigny

New "clean technologies" to treat mining and metallurgical effluents containing dissolved metals have been successfully applied at mine sites in North America and Asia, treating water flows up to 24,000 m3/day. These clean technologies offer significant benefits compared to conventional alternatives and provide a sustainable solution that eliminates residual waste sludge, improves water conservation, generates revenues from wastewater, and delivers overall improvements to the environment. This paper will profile these technologies, and provide best practice case study examples of their application at mining operations, including data for water chemistry, flows, water quality, capital and operating costs, and life cycle costs of treatment.

Jan 1, 2011

By Akihiko Nishiyama

Unmanned construction technology used for remote control operation of construction machines has some problems to solve compared with manned operation of construction machines, such as fatigue due to long-term operation or decreases in operational efficiency. To solve these problems, we recorded the viewpoints of operators in both manned and remote control operation and analyzed the differences. This paper reports on our discussion of improving the operability of remote control operation based on the analysis results.

Aug 1, 2013

By Yoshimasa Funakawa, Kazuhiro Seto, Akio Kobayashi

A new hot rolled high strength steel consisting of ferrite matrix and nanometer¬sized precipitates was developed. The ultra fine precipitates were identified as TiMoC2, and the strengthening by the precipitates was evaluated more than 300MPa in case of TS/800MPa grade steel. Due to the strengthening effect of the ultra fine precipitates, alloy elements for solid solution hardening can be reduced. It is notable that the steel shows very high yield strength (730MPa in case of TS/800MPa) and very high local elongation leading to excellent stretch flange formability at the same time. The mechanical properties of the steel are attractive for chassis parts and structural parts of auto body. The steel has been produced commercially, and applied to the parts successfully.

Jan 1, 2004

By Jing Chai

The Cenozoic unconsolidated strata with the thickness of 100 to 240m in the east area of China are composed of clay, sandy clay and hardpan, etc. Numerous shafts of the coal mines in these areas have been damaged to various degrees since 1987, with the main reason for this being the subsidence of the super-thick unconsolidated strata. To prevent the continuing settlement deformation of unconsolidated strata caused by groundwater removal, long-term water injection through multiple boreholes controlled the settlement deformation of unconsolidated strata. A new type of fiber Bragg grating (FBG) sensing system was successfully used for real-time strain monitoring of the unconsolidated strata during water injection at a coal mine in China. A mathematical model for the compression settlement induced strain calculation is proposed which can assist understanding of the effect of water injection on the ground. With the increase in water injection, the unconsolidated strata compressed state was improved by the transition of the stress state from compressive to tensile stress. The wavelength change of fiber Bragg grating sensors corresponded with the trend of the water level in the same strata. Engineering practice indicates that these sensors can normally, safely and reliably survive conditions associated with hydrous unconsolidated strata. The FBG sensing can be used for continuous lifetime monitoring of the system, starting with real-time monitoring during low-pressure water injection process of multi-borehole. The results will give important guidance for water injection and mastering stratum subsidence.

Aug 1, 2013

By P. Ramirez

"To achieve an optimal metallurgical performance in the flotation process the bubble diameter should be between 0.5 and 2.5 mm. To control bubble size, frothers are added, reducing bubble size and conferring bubble stability against coalescence. However, the bubble generation mechanism determines predominantly the bubble size distribution produced. In mechanical flotation cells, bubbles are produced by the shear stress generated by a rotating blade on a gas stream. This mechanism produces a log normal bubble size distribution. In contrast, in column flotation, jetting gas injectors are commonly used in Chile and the bubble size distribution is bimodal with small and large bubbles. Bubbles larger than 2.5 mm mean a loss in surface area, while bubbles smaller than 0.5 mm move with the pulp stream and therefore collide less frequently with particles. In this paper, a new device based on a jetting sparger and a deflector disc (impinging jetting) is evaluated as an alternative sparger for column flotation.The new device was tested in a rectangular acrylic cell 1 m × 0.5 m × 3 m. High-speed cinematography was used to compare bubble generation with jetting and impinging jetting at different gas velocity in the nozzle (5–50 m/s). From the image analysis, it was observed that the deflector induces a shear stress, in analogy to a rotating blade but in this case the shear results from a high velocity gas hitting a static surface. The device was evaluated in a 0.5 m diameter 3 m high column. The McGill bubble viewer technique was used to compare the bubble size generated by jetting and impinging jetting. It was found that the Sauter mean bubble diameter reduced from 7.4 mm to 2.8 mm, when the jetting sparger was modified with the deflector. In the case of the impinging jetting sparger, 70% of the bubbles were in the effective range for flotation, while for the jetting sparger, only 10% were in the effective range."

Jan 1, 2016

By M. N. Pons, E. Benizri, B. Laubie, A. Bani, Université de Lorraine LRGP, P. Kidd, A. J. M. Baker

"Serpentine (i.e. ultramafic) outcrops in Europe cover more than 10,000 km2 and have a low-fertility and low-productivity, making them unattractive for traditional agriculture. In general, these areas are slowly abandoned by local farmers, affected by strong rural exodus and landscapes undergo a process of closure. However, ultramafic landscapes have the potential to provide multiple ecosystem services that can contribute to Europe’s goals towards insuring food security, production of renewable raw materials and renewable energy. Phytomining (agromining) aims at cultivating metal hyperaccumulator plants that are able to accumulate Ni and other strategic elements from metal-rich soils and transport them to the shoots (>1%), which can then be harvested as a bio-ore. Such metal-rich biomass can be used to recover highly valuable metals, e.g. nickel (Ni) and also to produce energy (heat, electricity). Nickel agromining can thus offer an eco-efficient alternative to classical pyro- or hydrometallurgical processes without disturbing the soil cover and the geology from soils and rocks that would be considered as low grade ores or sterile material for conventional mining methods.Phytomining agroecosystems can lead to better soil resource efficiency and can offer a fully integrated, new agromining agriculture that could cover thousands of km2 in Europe, benefit local communities with a sustainable rural development and provide a wide array of ecosystem services which will need to be optimised under a life cycle assessment methodology:1. Production of bio-sourced metal products2. Production of energy biomass3. Restoration of soil fertility for conventional agriculture (Ni stress)4. Limiting Ni intake by local populations and farmers5. Use and conservation of local biodiversity (plant and soil fauna and microflora) as cultivated ecosystems6. Store carbon in cultivated soils7. Enhance pollination activity at landscape level.Nickel agromining could therefore change the economical balance in historically-disadvantaged ultramaficregions of Europe"

Jan 1, 2016

By Gulshan Kumar Pradhan, Yogendra Pratap Singh, Dhawanm Nikhil

"Potassium (K) is one of the essential elements for the growth of plants and thereby for humans. In fertilizers, potash demand has been steadily increasing at ~3.5% annually. Water soluble potash deposits are rare and highly localized. India is neither present on the world potash production map nor it has adequate potash rich rocks. The K-bearing minerals are recovered either by using conventional underground mining methods or though solution mining methods. India possesses a vast resource of silicate rocks such as glauconitic sandstone and Feldspar. These rocks are basically a group of alumino silicate of potassium, sodium and calcium (K2O%: 5-12, Na2O%: 3-10%, SiO2%: 52-65, Al2O3%: 15-20, Fe2O3%:, 5-7 and MgO%: 2-3.5).The K extraction from silicate rocks has received little attention probably due to the slow release, the locked structure of alumina-silicate minerals, and the unavailability of appropriate economic processes & their know-how. In fact due to this India imports all of its potash demand (about 3.5 million tons per annum) from different countries.In the present work, an attempt has been made to identify the structural and chemical alteration of desired K mineral phase in silicate rock (~K2O%: 10.5, Na2O%: 2%, SiO2%: 55, Al2O3%: 19, Fe2O3%, 5-6, MgO%: 2.5) under different conditions such as acid leaching, thermal treatment and chemical processing. Different treatments are aimed to increase K availability which is related to the modifications in mineralogical composition. The modifications in the feed sample and treated samples are studied through SEM-EDAX, XRD, EPMA and optical microscope. With the combination of treatments, it is possible to extract more than 90% K and the formation of sylvite phase (water soluble) confirms the dissolution of potash values."

Jan 1, 2016

By A. Fyson, M. P. Smith, Margarete Kalin

"Drums containing 0.07 m3 of pyritic waste rock from a zinc/copper mine, with and without Natural Phosphate Rock (NPR) additions (40 kg/t waste rock) were set up outdoors. The effluent chemistry has been monitored over a period of 709 days. In the presence of NPR, the cumulative acidity discharged from 7 out of 8 drums was 80 % less than that discharged from drums without NPR. Mixing NPR throughout the drums was more effective in reducing acidity than placement of the NPR in a layer in the drum. NPR treatment was more effective for 'fresh' waste rock than for material which had weathered for more than 4 years. It is concluded that application of NPR to pyritic waste rock could greatly reduce acidity generated.IntroductionWaste rock dumps are significant sources of acid, generated by the oxidation of sulphides. Oxygen and water supply are oxidation rate-controlling factors, and oxygen supply is the reaction-limiting component. If secondary minerals can be formed on the surface of the rocks, pyrite oxidation and therefore acid generation may be reduced or inhibited. Neutralizing agents such as limestone do not prevent the oxidation of pyrite but treat the resultant acid mine drainage (AMD) or acid rock drainage (ARD).Meek et al. (1991) determined in pilot scale experiments that apatite mixed with tailings was more cost effective than liming or use of PVC liners to reduce oxygen and water penetration into the tailings. Phosphate is not acting as a neutralising agent but it creates a chemical condition on pyritic surfaces which prevents reactions of the oxidising agents. Precipitation of principally iron phosphates physically isolates the pyrite surfaces from further oxidation (Ziemkiewicz 1990; Evangelou 1994). The chemistry of the phosphate effects has been described by Spotts and Dollhopf (1990). Secondary mineral formation was evident in the leach pile at Gibraltar when leaching was impaired (Scott, 1991) indicating a link between oxidation and the mineral-formation process. This paper reports on effluent characteristics when waste rock is generating acid in the presence of NPR."

Jan 1, 1995

By A. J. Basu

Air quality in underground mining operations can fluctuate significantly during the working day, but until recently the only way to ensure a mine had sufficient air quality was to over-ventilate and, with significant delay in adjusting the volume or direction of the airflow, working conditions were tolerable but rarely ideal. Underground ventilation management systems have been considered to achieve improved energy efficiency since at least 1995 in Canada. However, Mine Ventilation Optimization, (MVO) and integrating it with Ventilation on Demand (VOD) is only becoming more of a reality in the last seven (7) years. A systems approach to MVO takes into account all the elements from the point the power is distributed into the ventilation fans through to the actual quality and quantity of fresh air to the working face. Opportunities exist throughout the system for energy savings but not all of them are cost-effective. Depending on the application, these opportunities can be easily realized by properly sizing, streamlining, maintaining and operating the ventilation system using premium mine proven energy efficient components throughout. Implementation of VOD is a key step in achieving the MVO objective. However, VOD is a concept, and it requires various tools, procedures, and strategies for cost-effective and operationally viable implementations. This paper provides a historical background in the development of VOD and provides a framework for proper and cost effective implementation. In addition, an optimized ventilation system will also allow increased airflow by reducing resistances and shock losses. This turn in would allow production target improvement, which could be an attractive objective compared to energy savings. Mine ventilation is the life support system of an underground mine, and contributes to sustainable development and corporate social responsibility goals assuring health and safety aspects of strategic planning. The proposed framework addresses implementing mine ventilation optimization integrating ventilation on demand as a vehicle for energy, health and safety improvement and overall productivity gains in the mining cycle efficiency while significantly reducing carbon footprint of a mine.

Aug 1, 2013

By Z. D. Hora

Brick shales and refractory clays are mined at Sumas Mountain near Abbotsford. Sholes and stoneware clays elsewhere in the province have not been developed. THE SUMAS MOUNTAIN deposit near Abbotsford, 80 km east of Vancouver, has been in continuous production since 1905. The deposit is exposed in a small outlier and comprises a sequence of alternating beds of clay and sand. Beds are of Eocene age. Within the 400 m thick ness of sediments are seven distinctive conglomerate members, some up to 20 m thick, interbedded with fine grained sediments including claystones and siltstone , or "shales". Shale is quarried to produce a variety of bricks, sewer pipes and similar products; it is also used for cement. Several different shale beds have been mined over the years and exhibit a variety of fired colours ranging from buff-pink grey to deep red; pyrometric cone equivalents (PCE) range from 3 to 20. A layer of fireclay 3 to 4 m thick that occurs at the base of the sequence has pinkish white to light buff fired colour and PCE of 30 to 33. It is used as a 266 primary component to produce refractory bricks. The shale is quarried and processed by Clayburn Industries Limited of Abbotsford. Another similar but smaller outlier of the same geological formation is known from Blue Mountain, about 20 km northwest of Mission. Other ceramic clays in British Columbia are reported from Quesnel (7 m bed of white stoneware clay, PCE 17 to 19), Giscome Rapids (25 km north of Prince George, 10 m bed of stoneware clay to PCE 31) and anaimo-Comox area (buff to red firing "shales", PCE 8 to 10-1 12) . From 1959 to 1974 Cretaceous shale from Saturna Island in the Strait of Georgia was used to produce lightweight aggregate. Similar deposits of expanding shale are known from the vicinity of Duncan on Vancouver Island.

Jan 1, 1984

By A. L. MacAllister

"Keymet Mine lies on the Elmtree River 4 miles west of Petit Rocher and about 18 miles northwest of Bathurst, Gloucester County, New Brunswick. A good gravel road runs through the property.The deposit was discovered in 1880 when a vein 7 to 8 feet wide was re-ported. In 1883 the first shaft was sunk as part of an exploration program which was carried out sporadically until 1897, when the company dissolved. Activity on the property was intermittent until 1946 when the property was again staked and during the next year diamond drilling intersected the vein in several places. In December 1949 Coulee Lead and Zinc Mining Company optioned the property and held it until its sale to Keymet Mines Limited in June 1952. By July of the same year work had begun on a three-compartment shaft.Early development work was concentrated on the 150, 300 and 450 foot levels but the shaft has since been sunk to I,228 feet to allow for eight levels at intervals of 150 feet. Little lateral work has been done to date below the 600-foot level.The first mill constructed to treat the ore was to go into production in the spring of 1954, but was destroyed by fire. A second mill, having a capacity of 200 to 300 tons a day, was officially opened October 25th, 1954. Present shipments are zinc and copper-lead-silver concentrates.The rocks of the area are shale, conglomerate, limestone, and quartzite with minor interbedded volcanic rocks, all probably of Silurian age. Small plugs of Devonian acidic intrusions occur 3 miles east and about 5 miles northwest of the mine. Minor dykes of both acidic and basic rocks occur on the mine property. In many of the fine-grained sedimentary rocks the more brittle laminre have been brecciated and give the rock the appearance of an argillaceous conglomerate."

Jan 1, 1949