Search Documents

By R. Siwik, N. K. Davé

"The national reactive tailings (RATS) program is a co-operative industry-government effort to develop practical techniques for closure of reactive tailings areas. This paper summarizes the RATS program objectives and areas of research, and details the Noranda/CANMET project on the Waite Amulet tailings.Geophysical and biohydrogeochemical investigations were carried out at an inactive copper-zinc mine tailings site, Waite Amulet, in Noranda, Quebec. Geophysical investigations consisted of seismic, electromagnetic conductivity and electrical resistivity surveys to determine the thickness of the layers above bedrock and to map conductivity variations within the tailings and the immediate outlying area. Biohydrogeochemical investigations consisted of installing multilevel piezometer nests to determine groundwater flow patterns and porewater chemistry, obtaining solid core samples and characterizing for physical, chemical and mineralogical parameters, and iron oxidizing and sulphate reducing bacterial counts.The geophysical survey indicated a bedrock ridge extending under the tailings from the northeastern outcrop which may act as a porewater boundary layer. The survey also indicated a 2 to 20 m clay layer underlying the main tailings dam. Preliminary results of the saturated zone porewater chemistry have indicated three major zones of high electrical conductivity varying between 1,000 to 12,000 µs and pH between 3.4 to 8. Lower pH and high metal and sulphate concentrations were obtained in a shallow zone near the water table. With depth, the concentration of metal and sulphate ions decreased and pH increased below the water table. The underlying clay layer is relatively impervious -and most of the seepage from the tailings is probably exiting from the sides of the impoundment dam."

Jan 1, 1987

By L. I. Kiss, A. Larouche, V. Dassylva-Raymond

Control of the quenching capacity of the cooling water is of primary importance for maintaining the quality and recovery rate of ingots produced by direct chill casting. Industrially, this can be done using a cylindrical metallic probe undergoing rapid quenching by direct immersion in a reservoir filled with casting water. Such a test rig originally developed at Alcan Arvida Research and development Centre was modified and used to assess the role of key parameters affecting the boiling heat transfer. During the tests, the probe of the instrument undergoes the effects of different heat transfer mechanisms. An experimental study was performed in order to clarify the details of the probe-water heat transfer during rapid quenching. The heat flux along the surface was determined by mathematical modeling using the measured temperature signals, while the corresponding heat transfer regimes like stable and unstable film boiling, nucleate boiling and natural convection were identified by the analysis of high-speed video recordings. Aluminium

Jan 1, 2006

By W. J. Stickney

"Over-all recovery of cadmium has been increased at the plants of the Hudson Bay Mining and Smelting Co., Limited, since the construction of a slag fuming plant and baghouse where smelter flue dust is recovered. This pa-per outlines the distribution of the cadmium in plant products from the concentrator to the refining department.The leaching of cadmium-bearing precipitates from the zinc plant is also discussed. This consists of a two-stage leach; first with sulphuric acid and then with copper sulphate. Details of the leaches are outlined along with the safety measures practised in handling the hydrogen and arsine evolved.The paper describes the final preparation of electrolyte for the refining cells by purification for copper and thallium. Deposition of cadmium, using a polyacrylamide as an addition agent, is discussed.An outline is given of the melting procedures, under either sodium hydroxide or zinc chloride, and of the sub-sequent treatment of the dross to recover entrained cadmium and thallium."

Jan 1, 1966

By Sobczyk

The article will present a comparison of classifications of resources according to the JORC Code System with Polish classification, basing on system used in Eastern Europe. The differences between these classifications are significant. The information about mineral resources in Poland is not comparable to the main international system of reporting reserves like JORC, SAMREC, and PERC. Although comparisons between these systems are used, the transfer of particular categories of resources from the Polish system into a JORC category is not simple. Basing on the examples of privatization of Polish coal companies through initial public offering on the Warsaw Stock Exchange, the current practices providing guidelines how to convert resources from the Polish classification to the JORC system are described. Such independent assessment of resources is necessary for development of Mineral Expert?s Report (MER or CPR) which is an integral attachment to the prospectus.

Aug 1, 2013

By T. I. Kunkel

The economic prosperity of many Canadian communities depends on resource extraction within the traditional territories of Indigenous people. The geographic sites where these resources are situated are also areas where these Indigenous people have sustained themselves for millennia through hunting, fishing, trapping, and gathering activities. These traditional activities provide not only sustenance, but also cultural and spiritual values, and the ability to transmit oral Indigenous cultures and customs from generation to generation. The multimillion dollar revenue mine project proposed within the Cariboo Chilcotin region of British Columbia is situated geographically in a location which has sustained the Tsilhqot?in people for millennia. However, this group of people have important social and cultural values nested within the traditional activities at this location. These values are typically not at the forefront of resource development. Using Indigenous research and grounded theory, this research paper briefly outlines Aboriginal values of the First Nations communities within the Cariboo Chilcotin region and some lessons learned from the Tsilhqot?in people during the environmental assessment of the mine proposal.

Aug 1, 2013

By Karim Ramji

The extractive sector today faces growing social, legal and political risks (SLPs) from so many different stakeholders including national and local governments, name and shame groups, civil society and environmental groups, and the ?Occupy? movement. Beyond these stakeholders, there are the indigenous peoples who have growing legal, social, political and economic influence which can often determine the outcome of the Project. The development curve in the extractive sector from initial exploration to mine start-up has become longer, steeper and more risky and expensive as these SLPs have grown in scope and complexity. Even if a project is permitted or starts commercial production, its ongoing development and operations are also facing these SLPs. The continuous assessment of these SLPs and the strategy to mitigate for them has now become critical for every project in the extractive sector. A project will only be successful if it is able to obtain the legal permits to operate, then withstand any judicial reviews, and then also to be able to gain and maintain the Social License to Operate (SLO). Stakeholder identification, management and engagement are key risk-mitigation tools. This paper focuses on the growing influence that indigenous peoples are now enjoying and the impacts on the extractive sector. Indigenous peoples are a unique stakeholder group because their legal rights and interests to lands and resources, their aboriginal title and rights, are gaining more recognition. When indigenous peoples form alliances with other stakeholders, this simply adds to their growing momentum and leverage, and this can become a daunting challenge for the extractive sector. More due diligence is required by companies to understand and assess the challenges posed by operating in areas claimed by indigenous peoples. There is a real need for mining companies to develop an effective indigenous engagement strategy to address these challenges in order to successfully convert risks into opportunities. Early identification and engagement with the indigenous peoples is required and the goal should be to conclude an Impact Benefits Agreement (IBA) with the affected indigenous peoples. The real objective must be to develop a real and transparent relationship between the company and the indigenous peoples so as to gain and maintain the SLO.

Aug 1, 2013

Introduction Gold Mining is an Important Economic Activity in Canada n Total value added during 1990-99 was $15.5 bn n The gold price is an important factor in the value added process n The gold price affects gold mining output, profits, exploration expenditures, employment, etc. Some Factors that Affect the Gold Price n The value of the US Dollar affects the US Dollar price of gold: a weaker US$ correlates with a higher gold price n Supply affects the gold price: the higher the supply on the market each year, the lower the average gold price that year Central Bank Gold Sales n Yearly central bank gold sales add to supply, and affect the price of gold negatively n The negative impact on the price of gold reverberates through the Canadian gold mining industry n Despite the modest amounts, even Bank of Canada gold sales affect the Canadian gold mining industry

May 1, 2003

By Gerhard Melcher, Hermann Hilbrans, Michael Gamroth

"IntroductionSeveral new smelting processes have been proposed and developed during the last 20 years. This has been true, in particular, for copper smelting technology. The important impulses for the advances in this field have been the recent demands regarding the environmental protection, energy saving and improved utilization of the metals contents of deposits, in particular that of complex raw materials.The methods developed more recently for pursuing these objectives have been outlined in several papers. In some of them the advantages and drawbacks of certain developments have been stressed. These documents are of great importance for assessing the different processes. The following paper tries to explain some details of the cyclone smelting process taking into consideration a few of these well-known presentations. The effectiveness of operation of the cyclone smelting process indicates that this process presents a significant achievement when compared with other conventional methods.The application of the CONTOP smelting cyclone range s beyond the field of copper metallurgy or the smelting of sulphide concentrates with the aid of oxygen. The research work carried out in the pilot plant of KHD Humboldt Wedag AG in Cologne-Porz also includes the recovery of the metal contents of intermediate products and processing of smelter residues which have to be converted in a disposable stat e, free of environmental pollution. This paper explains a few examples in this regard."

Jan 1, 1987

By B. M. Das, D. B. Cross

"In June 1983, the Computer Applications and Process Control Committee (CAPC) of the Canadian Institute of Mining and Metallurgy (CIM) circulated a questionnaire to coal mining, exploration and consulting companies in Canada to determine the industry's level of interest in holding a workshop-style meeting to introduce company personnel to ""state-of-the-art "" computer systems designed to carry out specific technical and management junctions. It was necessary to conduct the survey to determine the specific fields of application and the nature of training which are of most interest.Almost universally, the companies expressed interest in computer workshops and training for applications in the Canadian coal industry. The survey showed that all categories of personnel felt the need for some sort of training. Areas of specific interest identified were: exploration and geology, mine design, reserve calculations, coal mining technology, coal preparation, rock mechanics, ventilation, financial planning, and process simulation. The details of this survey together with an assessment of the significance of computer applications in the Canadian coal industry are presented in this paper."

Jan 1, 1986

By K. A. Hughes

Under the oxidizing conditions of the McClean Lake Tailings Management Facility (TMF) hydrocarbons entrained on the surface of tailings material from mill processes are gradually converted to soluble bicarbonate ion. This has been observed to be a process occurring over approximately three years likely encouraged by the presence of a microbiological community within the tailings mass and in the water column. A recent tailings sampling campaign has provided evidence that bicarbonate ion is participating in the conversion of gypsum to calcite. In older tailings, equilibrium with calcite appears to be controlling the terminal bicarbonate ion concentration.

Aug 1, 2010

By Susan W. Campbell, Bruce Regensburg

"The CIM Careers Task Force has addressed industry's concern of a perceived shortage of skilled personnel over the coming decade. The industry is faced with a fundamental shift by young Canadians away from scientific and engineering careers, coupled with the fact that today 's students know little about the minerals industry and have a poor image of it.The responses to two questionnaires which were distributed to CIM members, government, professional associations, and educational institutions, formed the backbone of the Task Force position paper, which presents a shopping list of ideas and initiatives for consideration and to facilitation by the various organizations concerned.Tackling the image of the minerals industry is part of the answer to the careers crisis. On the positive side, the minerals industry provides the allure of a treasure hunt for young people and is seen as a significant contributor to the economy. It is understood to be well paying, provide good opportunities for advancement, individualism, and travel, and to be rich in esprit de corps. Enhancement of these positive aspects of the image can take place at all student age levels.Numerous initiatives tackle the negative aspects of the image. Young people perceive the industry to be environmentally damaging, which is the most crucial aspect that needs to be addressed. The industry is seen as still in the pick-and-shovel days and as a sunset industry that is running out of ore. Work in the minerals industry is perceived as dangerous and lacking glamour. And finally, the perceived remoteness of operations and exploration is seen as a drawback to a largely urbanized student group.Tackling young peoples' curiosity and interest in the minerals industry throughout grade school and encouraging postsecondary science and engineering students to enter the minerals industry by ensuring summer employment is the second part of the equation.The CIM Careers Task Force position paper develops strategy to attract and maintain interest of students in grade school, junior high, senior high school, and in post-secondary levels. The strategy outlines initiatives targetted at each of the educational levels and action plans to accomplish the objectives."

Jan 1, 1993

By R. A. S Villegas

The Brazilian government announced in 2007 its plans to reactivate the nuclear program. As a result of this decision, a new nuclear power plant is already being built and there are studies dealing with, among other activities, the building of 4 to 8 new ones until the end of 2030. Such increase on the country?s uranium demand affects INB, the Brazilian state company that?s in charge of uranium supply. This paper describes scenarios predicted to the Brazilian nuclear industry for the next years and the INB plans to meet the country?s needs in terms of uranium exploration and production.

Aug 1, 2010

By Robert A. Creaser, Iain Mitchell, Robert L. Linnen

Abstract - The Bermuda Zn-Pb showing is hosted by dolomitized Blue Fiord Formation of Devonian age, located east of the Ensorcellement dome on the Grinnell Peninsula of Devon Island. Fluid inclusions in hydrothermal calcite indicate that the mineralization precipitated from low-temperature, highly saline brines. The ?34S compositions of sphalerite, galena, and marcasite range from 16.1‰ to 35.2‰. Consequently, the Bermuda showing is interpreted to be Mississippi Valley-type (MVT) mineralization. The apparent age of mineralization has been determined by the Rb-Sr method from sphalerite separates, and a Late Devonian age of 357 ± 50 Ma (MSWD=65), with an initial 87Sr/86Sr ratio of 0.7083 ± 0.0020 is indicated. This date, within error, is the same as the Polaris deposit. This suggests that the mineralization formed during the Ellesmerian Orogen, although it is also possible that mineralization is associated with extension, related to the opening of the Sverdrup basin. The strontium and sulfur isotopes and fluid inclusion analyses indicate the involvement of a brine that acquired its salinity from interaction with evaporites, lower in the stratigraphic succession. The Polaris mine is the type deposit in the Cornwallis Zn-Pb district and is hosted by the Thumb Mountain Formation. The results of this study are significant because they demonstrate that regional brine movement is more widespread than previously recognized, and that MVT mineralization in the Cornwallis Zn-Pb district is not restricted to the Thumb Mountain Formation.

Jan 1, 2004

By D. A. Barr

"Most of the lode and placer gold production in the Canadian Cordillera has been derived from mines and placers in the Intermontane and Omineca belts. Gold has been produced from rocks of Precambrian to Eocene age, but the preferred host environment contains Upper Paleozoic to Upper Jurassic eugeosynclinal or arc-type sedimentary and volcanic rocks adjacent to plutonic complexes which have a wide variety in both size and composition. Auriferous quartz lodes occur in fissures and shear zones which are commonly subsidiary to strong fault zones. In common with most vein-type deposits, structural complexities are an essential part of the mine environment.Gold production from the Canadian Cordillera to the end of 1978 totals 35.0 million ounces, of which 47 per cent has been produced from placer mining, principally in the Klondike and Cariboo districts. The balance has been derived from lode gold (80 per cent) and base metal (20 per cent) mines.Gold reserves in producing mines and deposits committed for production as of January 1, 1978 were 87.4 tons, or 21.6 per cent of total Canadian gold reserves contained in all types of deposits. Although more than 100 lode mines have operated in the Canadian Cordillera since the turn of the last century, over 75 per cent of the lode gold produced by 1978 was recovered from five mining camps, namely the Rossland, Hedley, Bridge River, Premier and Barkerville.The average grade of the principal producers in these camps was about 0.45 ounce of gold per ton. Individual camps yielded from 3 to 8 million tons during their operating lives, which varied from 28 to 43 years. The last of these mines ceased operating in 1971.Most of the total lode gold production has been derived from quartz veins, frequently with associated carbonate and ankerite, occupying fractured and faulted zones in Mesozoic volcanic and sedimentary rocks closely associated with a variety of intrusions. A review of the literature suggests that several deposits may have evolved by remobilization of ore constituents from earlier concordant gold-bearing formations. The principal metallic minerals in the deposits are native gold, electrum, tellurides, pyrite, arsenopyrite, pyrrhotite, sphalerite, galena and chalcopyrite.As the mineralogy suggests, many of the Cordilleran lode gold deposits have yielded important co-products or byproducts, including silver, copper, lead, zinc, cadmium and tungsten. Significant by-product gold production has also been derived from porphyry copper, volcanogenic, replacement and pyrometasomatic deposits, particularly in recent years.No major lode gold discovery has been made in the past 67 years, although little exploration activity for gold has taken place during the last 30 years. Several relatively small lode gold and gold replacement deposits have been discovered in recent years, either serendipitously (Chappelle) or on very low initial budgets (Northair and Carolin). Based on well-established precedents, one or more of these may eventually be developed into a large mine.A detailed study of the Canadian Cordillera gold deposits based on recent genetic models could prove rewarding, not only in up-dating information on their origin and depositional characteristics, but in stimulating the search for undiscovered gold deposits, in the Cordillera and other parts of Canada."

Jan 1, 1980

By L. V. Volkov

The equilibrium of the CuO-Cu20-Cu+-Cu2+ system with various chloride ion concentrations in solution in the presence or absence of an oxidant was investigated. It is shown, that, regardless of the presence or absence of chloride ions or oxidant (oxygen) in the system, the process can be divided into three stages, which are characterized by differing rates and mechanisms of metallic copper cementation and cuprite precipitation and, hence, lead to differing rates of the dissolution of nickel into solution. The effect of the concentrations of chloride ion and oxidant on the phases in the process residues is also discussed. The addition of an oxidant increases the amount of cuprite (Cu20) in the leach residue. With increasing chloride ion concentrations, the rate of copper cementation increases, even without an oxidant in solution. The results of these laboratory experiments and the mechanisms developed are consistent with analysis of samples of industrial cement copper obtained from the Severonickel Combine.

Jan 1, 2007

By J. M. Ortiz, J. Haas, W. Kracht, G. Pamparana

This work explores the effect of ore hardness variability on the design of a solar photovoltaic system with battery storage and grid backup, to operate a semi-autogenous grinding mill (SAG). First, a case of two synthetic ore populations was studied, without any consideration of spatial distribution. The mean and variance of the ore hardness (measured in specific energy consumption) of both populations were subjected to a sensitivity analysis. The operation was evaluated with one and two stockpiles. The latter allows classifying according to ore hardness to adapt the SAG energy consumption to the solar cycle. The results show that using two stockpiles allows achieving a larger autonomy (i.e., fewer energy imports) at lower total costs, especially when the difference of mean hardness between the two populations is large. The difference in variance (between the two populations) has a smaller impact on the design recommendations. Second, a case study was performed considering the spatial distribution of geometallurgical units. Two cases were considered: (a) brownfield, when there is historical information of the actual variability of the ore hardness; and (b) greenfield, when the system design relies mainly on geometallurgical modeling. Brownfield and greenfield planning result in similar sizing recommendations of the solar power plant if precise drill cores are available. In this case, geometallurgical modeling is an effective tool for forecasting the energy demand necessary for designing the power plant. INTRODUCTION Solar energy can help make mining more sustainable (Moreno-Leiva et al., 2017). With falling battery costs, an autonomous solar supply is soon to become an economical alternative in many parts of the world, even in the presence of a larger power grid (Child et al., 2017). Although this, places with high solar radiation such as the Atacama Desert in Chile, nowadays show a large potential of incorporating solar energy as a supply of energy. Many of the Chilean copper mines are in this zone making it interesting to study their compatibility and potential of integrating this renewable source to their operation. The power demand in a copper mineral processing plant is determined by the main power loads in grinding and flotation, with grinding typically the largest power consumer, especially the semi-autogenous grinding (SAG) mills (Wei and Craig, 2009). In Chile, it corresponds on average the 50% of the electrical energy consumption (COCHILCO, 2013). Solar energy production is determined by the irradiance perceived into the solar photovoltaic (PV) panels (which varies through the geographic location) and several other climatic parameters such as the current season, humidity, temperature, altitude, and others (Molina et al., 2017). Also, solar energy is only generated during the sun hours, getting to a maximum generation at a certain peak hour during midday, and finally dropping to zero during the night. This shows a cyclic parabolic profile as shown in Figure 1. Due to the SAG mill operated continuously, the power supply always must be available. During the night, to continue supplying the energy, it is necessary to complement the solar power generation with a battery energy storage system (BESS), which will act as a power backup and a buffer. For the optimal sizing of this PV- BESS system, information of the demand profile is needed (Pamparana et al., 2017). In the case of the SAG mill operation, the resulting demand relates to the ore-hardness for a specific throughput and grind size (Morrell, 2004). Therefore, for a given throughput and target grind size, a harder ore would require more power, and variable hardness results in more variable demand and a subsequent need for larger energy storage (Bueno et al., 2015). Due to the ore-hardness variability and the operation of the mill, the power demand profile in inherently variable.

Jan 1, 2019

By B. Krysa, A. Mitsui, T. L. Koehler

The presence of arsenic, even at trace levels, in copper processing leads to the risk of arsine gas where reducing conditions exist that can reduce any soluble arsenic present to its minus 3 valance state and generate hydrogen gas from the solutions. This risk is understood to be significant within the industry, particularly in the case of liberator cells where copper concentrations in solution are drawn down to remove the copper and impurities from the bleed stream. However, there are numerous other potential areas where the arsine gas risk exists including contact between active metal such as iron, zinc or aluminum and arsenic bearing solutions in pyrometallurgical dust treatment, refining and acid plant operations. In turn this breaks down to different mitigating strategies dependent on the risk scenarios considered; for example, how this risk interacts with Change Management, Confined Space Entry or Contractor Training. The ISO 45001 is an emerging standard meant to improve employee safety, reduce workplace risks and create safer working conditions all over the world. The paper shows a case study of how a framework consistent with the tenets of ISO 45001 has been used to provide a consistent assessment of this risk for a wide variety of copper operations and the expectations of how this may be used to effectively improve the effectiveness of barriers against future incidents. INTRODUCTION Arsine gas (AsH3), first identified in 1775, is a highly poisonous, colorless, non-irritating gas with a mild garlic odor that is heavier than air. Arsine gas is generated when reducing conditions are generated in the presence of hydrogen ions and arsenic compounds. Present permissible occupational exposure limit as defined by Occupational Safety and Health Administration (OSHA) as an 8-hour time-weighted average is ppm (0.2 mg/m3). Further increasing the risk, conventional respiratory protection utilizing half or full masks with gas filtering cartridges provide minimal protection against arsine. In copper processing plants, the risk of arsine generation is well understood in liberator cells, which are part of the electrolysis process. In this process, solutions containing copper are reduced in copper concentration removing not only the copper, but also arsenic, antimony and bismuth. The residual solution can be bled to control impurity build-up in the refinery. In this process, if the copper concentration is reduced to the point where As3- can form, arsine gas is generated via reaction with hydrogen ions generated during the plating process. The copper concentration at which arsine gas is generated depends on copper concentration at the cathode surface, the temperature and the acidity. As a result, there is always a risk of arsine gas generation in the liberator cell. Process measures to minimize or mitigate arsine evolution are tight control on final copper concentration, warm temperatures, fresh feed distribution and internal acid recirculation rates. Operator exposure protection measures are hooding, ventilation, arsine detection systems, restricted personnel access, automated shutdown controls and pre-defined evacuation plans.

Jan 1, 2019

By R. J. Twigg, S. D. Chang

"The production of heavy water, the moderator in a CANDU reactor, is examined following a flow sheet of a typical Canadian plant. The process involves the extraction and concentration of deuterium from natural water through a chemical exchange mechanism with hydrogen sulphide. Consequently, corrosion problems associated with sour environments – the use of hydrogen sulphide - are an everyday problem and have led to the development of a highly refined materials selection and testing program to prevent equipment from failing prematurely.IntroductionHeavy water is a naturally occurring compound in ordinary water and is formed from the combination of two deuterium atoms and one atom of oxygen. Deuterium is a heavy hydrogen atom which has a nucleus of on e proton and one neutron. Hence, heavy water is a combination of heavy hydrogen and oxygen and is chemically known as deuterium oxide. It looks and tastes like ordinary water but it freezes at 3.8°C and boils at 101.4°C. The molecular weight of heavy water is 20 as compared to 18 for ordinary water; the density of heavy water is ten per cent greater than that of ordinary water.Although heavy water and ordinary water exhibit only small differences in their chemical and physical properties, there are large differences in their nuclear properties, the most important of which is the neutron moderating ratio, used to measure the ratio o f the slowing down power to the neutron capture characteristics. For heavy water the ratio is 21000 and for ordinary water it is 50. This high moderating ratio is essential for achieving a high neutron economy. Heavy water is, therefore, chosen as the moderating and heat transport fluid in the CANDU reactor."

Jan 1, 1983

By E. L. Martheleur

A general expression for the electric power generated or consumed in a direct-current circuit is obtained by multiplying the reading of a suitable voltmeter connected across the terminals by the reading of an ammeter connected in the circuit. by the reading of an ammeter connected in the circuit. When alternating currents are considered, the product of the volts and amperes as obtained for direct currents does not generally represent the true energy involved; it is greater than this true energy and should be multiplied by a certain factor which may have any value between zero and unity, according to the conditions of the circuit. This factor is called the power-factor of the system, and expresses the ratio of the true energy over the apparent energy. For a three-phase system the expression of the apparent energy is [\/ 3 x E x I; ] while the expression of the true energy, that is, energy suitable for mechanical work, is [v? 3 x E x I x cos A.] The total current of a circuit corresponds to the reading of an ammeter connected in the circuit; it is the resultant of two currents. The first of these is in phase with the voltage, and is that portion which really produces mechanical work; the second is always in quadrature with the voltage, that is it may lead or lag the voltage by 90° according to the condition of the circuit. This second current does not produce any sensible work, and for this reason is sometimes called wattless current or reactive current.

Jan 1, 1924

By John H. Fowler

"Barytes is one of the major components of drilling fluids used in oil and gas well-drilling. This mineral's close association with the petroleum industry bestows it with a commodity status not enjoyed by many other industrial minerals. Approximately 85% of world barytes production is used as a weighting agent in oil and gas well drilling while the remaining 15% is consumed mainly in the manufacture of barium chemicals, glass and as a pigment, filler or extender.Barytes mining began in Nova Scotia around 1865 and has continued until the present. Currently there are three barytes producers in the province one exporting pharmaceutical-grade barium sulphate and the other two supplying drilling mud-grade barytes to the offshore. Several barytes exploration and development programs are underway with excellent possibilities that Nova Scotia deposits will supply a significantly larger share of the drilling mud-grade barytes used in east coast drilling programs.Currently there is renewed interest in barytes activities in Nova Scotia because of its use as a weighting agent in drilling flu ids used in offshore oil and gas drilling programs.This paper reviews the use of barytes by the well drilling industry; outlines the history of barytes mining in the province, progressing to present-day exploration, development and production activities underway in Nova Scotia; and concludes with the market potential for Nova Scotia barytes."

Jan 1, 1986