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By S. Simukanga, J. Masinja, P. A. Bepswa, A. N. Mwale

Screening is an important operation in dry and wet closed circuit mineral processing applications. Most of the operations have seen the benefits of using fine wet screens in primary grinding sections where the product is relatively coarse, and screens can handle the tonnage. Although many models are available, most of them are confined to dry and wet coarse screening applications. Most models do not give good predictions for wet fine screening. To facilitate model development, pilot plant tests were performed using a single deck Derrick Screen at aperture sizes of 45µm, 75µm, 106µm, and 150µm. Experimental data for a range of feed solids concentrations and flowrates was collected and used to calibrate the performance of the screen under the different operating conditions. The results showed that the performance of the screen deteriorated with an increase in feed solids concentration, and, similarly with an increasing feed flow rate. The percentage of fines carryover also increased with the reduction aperture size. The carryover was even more pronounced at higher feed rates and solids concentrations. A model was developed for predicting the performance of fine wet screening. Data from the test work was used to compare the actual and predicted results, and to calibrate the model. Additional independent data was used to validate the model and assess its limitations. This model will give an expected screen performance based on the initial feed conditions. It incorporates screen design parameters that allow for an estimation of a suitable screen size for a desired performance based on given feed conditions. This paper discusses; the results from the test work performed, the model development and its limitations.

Jan 1, 2016

By J. T. Birkholzer, M. Rutenberg, K. -H. Lux, R. Wolters, J. Rutqvist, L. Blanco Martin

In this paper, we present numerical results corresponding to the Thermal Simulation for Drift Emplacement (TSDE) test, conducted in the Asse salt mine (Germany) between 1990 and 1999 to simulate reference repository conditions for spent nuclear fuel in rock salt. This test is of significant relevance for nuclear waste disposal in salt because extensive research and measurement programs were set up for the experiment. In our numerical study, we use two sequential simulators, TOUGH-FLAC and FLAC-TOUGH, and we investigate two-way coupled processes, focusing on thermo-mechanical analyses due to the main effect of heating. The two simulators used have recently been updated and are able to deal with large strains and creep processes. Moreover, specific constitutive relationships and coupling functions for rock salt and crushed salt under repository conditions are available. Within the framework of a benchmark exercise between Lawrence Berkeley National Laboratory and Clausthal University of Technology, the same scenario has been modeled in three dimensions using the two simulators mentioned. The main objective of the current, first stage of the benchmark is to evaluate the capabilities of these two simulators to predict relevant processes under repository conditions for high-level nuclear waste in saliniferous media. The comparison of the numerical predictions between them is very satisfactory, leading to a successful code-to-code verification. The comparison between measurements and numerical results shows that the most important processes are captured by the codes and constitutive models used. However, some differences exist between measurements and numerical results. These differences will be addressed in the next stage of the benchmark exercise, in which a parameter fitting effort will be undertaken. Overall, from the results obtained it can be concluded that TOUGH-FLAC and FLAC-TOUGH have the necessary capabilities to reproduce relevant processes under repository conditions for high-level nuclear waste in saliniferous formations.

Jan 1, 2015

By G. Vibert Douglas

NICKEL minerals are known in New Brunswick but have never been reported from Nova Scotia. The attention of the writers was drawn to an occurrence of pyrrhotite, reported to carry nickel, at the Second Gold brook, Middle river, Cape Breton. The purpose of this paper is to record the occurrence and give an account of the general geological association. In a later paper it may be possible to give greater details? than are available at present. GEOLOGY The area lies at the edge of a plateau of Precambrian rocks which forms the panhandle of Cape Breton island. This plateau has a general elevation of 1,200 feet. Middle river, with its tributaries, the First, Second, and Third Gold brooks drains the area. The lower country to east and southeast of the plateau is underlain by lower Carboniferous sediments. The rocks of the plateau are presumably of Precambrian age but have never been definitely correlated with the Gold-Bearing Series of the mainland. ?There i:s; however, some resemblance, although they have apparently been more intensely mountain-built. They are essentially fine grained, sheared quartzites and slates . The general strike is east and west, with a north dip of 45° to 55°. There are smalllocal drag-folds in the area. The only igneous rock in the immediate vicinity is an intrusive pink porphyry. It has small phenocrysts of quartz and feldspar. It has intruded the sediments generally along the structural planes, but in places crosses the structure . Its intrusive character is further proved by the fact that it contains xenoliths of the quartzite.

Jan 1, 1937

By R. Llewellyn

"Wear damage is responsible for very high maintenance costs and significant production losses in the oil sands industry of northern Alberta.It affects all areas of operations and involves a panoply of wear mechanisms from low stress sliding abrasion at extremely frigid temperatures during winter mining, to elevated temperature erosion/corrosion in processes where bitumen is converted to lighter hydrocarbon products.There is no universal panacea to defend against such diverse attack and a wide selection of resistant materials and systems is employed. These range from relatively soft rubbers which rely on their elastic properties for their protective capability, to some of the hardest ceramics and cermets which are currently available commercially.Details are presented of the characteristics and forms of the variety of wear materials being used and how they relate to the requirements of their areas of application. The review focuses on the practices followed at Syncrude Canada Ltd., which is the larger of the two commercial oil sands plants."

Jan 1, 1997

By M. Mirnezami, J. A. Finch, M. S. Hashemi A.

This study examined the effects of pH and sulphate concentration on the surface charge and stability of alumina and pyrite dispersions. The relationship between these properties was investigated using measurements of electrophoretic mobility and settling velocity. The maximum aggregation for both minerals was observed near the iso-electric point (iep) where the force of repulsion is at a minimum. Aggregation decreased at pH values away from the iep, where an increased surface charge causes electrostatic repulsion between particles. Zeta potential data revealed that sulphate ions were adsorbed only on positively charged surfaces for both minerals. Adsorption of sulphates on the alumina surface increased aggregation by reducing the surface charge from >+25 mV to close to zero. These results indicate an electrostatic bonding of sulphate ions to alumina surface. Preliminary results on the interaction of pyrite and sulphate ions indicate a similar response.

Jan 1, 2004

By X. J. Guo, H. X. Li

The biological heap leaching at Zijin copper mine is currently the largest industrial application of biohydrometallurgy and one of the earliest mines to develop biological metallurgy technology in China. Since 2001, through demonstration plant and different expansion stages, it has been developed to produce 20,000 tons cathode copper annually. However the ore grade of heap leaching gradually decline year by year with copper grade average at around 0.23% now. The copper mineral is mainly the secondary copper sulfide, and symbiosis with higher content pyrite, the sulfur and iron contents is about 15 times as copper in the ore (S/Cu>15), so the acid and iron treatment of leachate, extractant and acid mine waste water is a great challenge. Combined with located in the rainy area of southern China, huge amounts of over 10 million cubic meters acid drainage need to be treated every year, so the recovery of copper from waste water as well as low grade ore is one of the characteristics of this process. This paper in general introduced the operation of heap leaching, solvent extraction, stripping and electrowinning process in Zijin mine, summarized the experience of production and technical practice, and discussed the methods of heap construction, leaching rate enhancement, third phase formation and treatment, mine effluent treatment, resource recovery and heap slope reclamation. INTRODUCTION The Zijinshan gold and copper mine is located in southeast China, Fujian province, and the typical distribution characteristics of gold and copper deposit are "upper gold and lower copper", both are large porphyry deposits. By the end of 2017, the accumulated proven reserves of available gold resources were 318 tons, copper are 2.15 million tons, and the prospective reserves of copper are more than 5 million tons. The gold mining is open pit while the copper mining is open pit and underground. The cut-off grade of gold mining is 0.15 g/t, and that of copper mining is 0.15%. A large number of very low-grade gold ores (grade <0.30 g/t) adopt a combined ore-dressing process of “partial crushing/ore washing/reprocessing/heap leaching (overlying)/ carbon slurry" independently developed, while flotation and bio-heap leaching are adopted for copper mine. Among them, copper ore with more than 0.25% copper content enters the flotation system to produce copper concentrate, while that of less than 0.25% copper content is processed by bio-heap leaching, solvent extraction and electrowinning. Zijin biological heap leaching plant is the first mine in China to achieve the scale of annual output of ten thousand tons of cathode copper since 2006. In 2008, the solvent extraction and electrowinning system were expanded, now with a daily processing capacity of 20,000 tons of ores, an annual output of 20,000 tons of cathode copper, the expanded plant is the largest biohydrometallurgy plant in China.

Jan 1, 2019

By K. Becerra, D. G. Almond, T. D. Maru

"Nkomati Nickel Mine in South Africa processes one of the world’s hardest ores in a 375k TPM autogenous grinding circuit. The plant employs an unconventional processing circuit, comprising a primary autogenous mill (AG or FAG) and pebble crushing circuit followed by a secondary hybrid pebble/ball mill and classification cyclone cluster.Advanced Process Control (APC) or Expert Control is now generally accepted as an advantage in most modern high capacity concentrator grinding circuits. This paper reviews the installation of model predictive control at Nkomati and examines the results and benefits of installation in an autogenous mill during plant ramp-up. The paper also demonstrates how predefining process control objectives together with good plant and supplier cooperation can achieve a robust and reliable APC implementation on a very short site program.The results conclusively demonstrate operational and economic benefits during circuit operation with the advanced process control system ON. Production performance and circuit stability were significantly better than during manual control."

Jan 1, 2012

By K. P. Wright

THREE OF the gold mines in the Red Lake Camp operates fluid bed roasters in their milling circuits. The mines are Campbell Red Lake, Cochenour Willans, and Dickenson. The roasters are used for the autogenous roasting of a flotation concentrate for subsequent gold recovery by cyanidation. Cochenour and Dickenson operate single stage reactors, whilst Campbell use a two-stage system. Ore treated by the mines is similar in that the major part of the gold is associated with arsenopyrite. Other sulphides present are pyrite, pyrrhotite, stibnite and sphalerite. Gangue minerals are mainly quartz, with carbonates and talc. Mineralization is, for the most part, extremely fine, and there is intimate association between sulphides and quartz, so much so, th at a picked specimen of apparently massive arsenopyrite will frequently contain as much as 80 per cent gangue. Gold recovery by straight cyanidation on this type of ore would not be higher than 80 per cent and

Jan 1, 1961

"Some of the tools developed for the processing of nickel laterite ore by resin-in-pulp (RIP) may be applicable to the remediation of metalliferous mine drainage (MMD). In both cases, recovery of metal value and production of a stable waste stream appropriate for long term storage is desired. MMD typically has the additional challenge of management of toxic low-value metals. Seen in this light, innovations in RIP reactor configuration, selective elution strategies and novel synthetic ion exchange resins become useful tools for taking on the MMD challenge in a way that maximizes both environmental and economic benefit. INTRODUCTIONAcid mine drainage (AMD) is a common problem in any country with significant past mining activity. When sulphide containing minerals, tailings or slag are exposed to water, oxygen and sulphur oxidizing bacteria, AMD will result. Abundant and reactive iron sulphide minerals leach first, providing acidity and the ferrous/ferric couple that can enhance the oxidation kinetics of other minerals. If this runoff contacts encounters acid consuming carbonates or silicates, the acidity may be neutralized, but certain heavy metals remain in solution and can continue to be an environmental hazard (Gray, 1997). For this reason, the remainder of this paper will refer to the broader term metalliferous mine drainage (MMD) rather than acid mine drainage. In either case, such drainage, containing high heavy metal concentrations and often significant acidity, is toxic to aquatic life and can lead to significant damage to ecosystems and to public watercourses. MMD is a problem most commonly associated with now defunct sulphide mineral mines, but similarly toxic streams can result from many types of waste, such as poorly stabilized leach tailings, slag heaps, and coal flotation tailings (Johnson and Hallberg, 2005; Lee et al., 2002; Sainz et al., 2002; Schüring et al., 1997). In any case, the management and remediation of MMD is an important ongoing problem for the resource industry, particularly for the many mines in Canada closed before the advent of more stringent environmental standards. MMD remediation represents a significant long term expense for the resource industry. Multi-disciplinary efforts to understand and mitigate this problem range from creation of artificial wetlands (Poulin and Lawrence, 1996; Sheoran and Sheoran, 2006) to sophisticated biochemical reactors and precipitation processes (Hatami, 2010). Certain remediation technologies such as ion exchange offer methods to make a saleable product by recovering valuable dissolved metals. This paper will show how these technologies can help defray the cost of remediation, and offer potential to turn a dangerous waste stream into a useful product."

Jan 1, 2012

By W. D. Gould, A. Kapoor

Acid mine drainage (AMD) is characterized by low pH and high concentrations of sulfate and dissolved metals such as iron, manganese, aluminum, zinc, and copper. Chemical treatment of AMD achieves pH neutralization and toxic metal removal but also produces large quantities of bulky sludge that requires long-term storage facilities and monitoring. Chemical treatment of AMD achieves only partial removal of sulfate (SO4) and total dissolved solids. Sulfate reducing bacteria (SRB) have been used for the removal of sulfate from industrial process wastewaters. The biological sulfate reduction process generates sulfide and alkalinity. The sulfide produced in the biological sulfate reduction process is used to precipitate metals present in AMD as their respective sulfides and the alkalinity generated is used to neutralize the AMD. This review article will present an overview of biological sulfate reduction processes using SRB, bioreactor configurations, AMD treatment studies, and full-scale systems in operation for the treatment of acid mine drainage.

Jan 1, 2004

By P. L. Claessens, S. Belisle, C. Bowen

"Use of zinc shot feed is a well-established procedure among North American electro-galvanizers. This form of zinc is easy to handle and relatively inexpensive when compared with zinc oxide. This paper reports results on the kinetics of zinc shot dissolution in traditional pure zinc solutions and in electrolytes used for the plating of nickel/zinc alloys. Despite the cementation of minor amounts of nickel in the latter solution, acceptable dissolution rates of the zinc shot can be achieved through proper adjustment of the solution velocity. Under these conditions, the nickel shell produced by cementation is continuously abraded, exposing the underlying zinc.IntroductionThe use of insoluble, noble metal-containing anodes rather than soluble zinc anodes for the operation of high current density electro-galvanizing lines has gained almost universal acceptance. Two major reasons for this trend are:• improved control of the process by virtue of constant inter-electrode distance; and• increased productivity because the operation of the lines does not require the relatively frequent interruptions for replacement of consumed anodes .The results of the principal anode and cathode reactions are, respectively, depletion of the zinc content of the electrolyte and the increase on its acidity;"

Jan 1, 1991

By Mike Broczkowski, Laura Dewhirst, Kieran Large, Angelo R. Fernando, Heather Daigneault, Jim Johnson, Randy Wiens

The radioactive isotope radium 226 is a contaminant of potential concern in effluent waters from metal mining operations in Canada. Acceptable release levels of radium 226 are governed by Metal and Diamond Mining Effluent Regulations. Since radium is invariably present as a companion element in uranium ore, monitoring and controlling of radium 226 is a must for uranium mining operations. Measurement of radium 226 is traditionally carried out through a radiochemical technique involving selective co-precipitation of radium with barium sulphate followed by alpha spectroscopy for quantification. As of 2010, Cameco has also been using an ICP-MS based radium analysis method developed in collaboration with a research team at Trent University, Peterborough, Ontario. This method, which is highly automated and requires significantly less sample handling, with improved turn-around-times, is being used by Cameco site laboratories at the McArthur River and Cigar Lake mines as well as the Port Hope Conversion Facility. This paper compares the benefits and drawbacks of this new method, compared to the traditional alpha counting procedure drawing from almost ten years of field experience.

Jan 1, 2020

By L. Tang

A seismic monitoring system was installed in 2005 at Dongguashan Copper Mine, the deepest metal mine in China. Based on the seismic events monitored in situ, the possibility of rockburst prediction and prevention is investigated in this paper. The characteristics of space-timeintensity of mining-induced seismicity and the seismic response to mining are studied in detail using the seismic data in Dongguashan Mine. A conceptual model and a criterion of assessment of hazard seismic nucleation are proposed for Dongguashan Mine. In this model, the mine seismic stiffness method is adopted for rockburst prediction within the framework of the unstable failure theory. To analyze rock failure cases in Donggauashan Mine, the rate of the ratio of stiffness of rock in nucleation area to its surrounding area is proposed as a criterion for rockburst prediction.

May 1, 2009

By Bruce C. Fielder

"The concentration of uranium in orebodies discovered in the Athabasca Basin of northern Saskatchewan over the last 20 years has increased by a factor of 100. These high grade uranium orebodies are associated with high concentrations of radionuclides, complex mineralogy and an elemental makeup that includes base metals, arsenic, and molybdenum. Exploiting these high grade ores has required metallurgical advances in milling, tailings disposal and effluent treatment as well as changes in the design of uranium mills.This paper describes the most significant advances, including advances in dealing with the environmental issues which have become more prevalent in recent years. The milling processes of the Cluff Lake Mill, Key Lake Mill, Rabbit Lake Mill, and McClean Lake Mill are compared to illustrate both similarities and differences necessary for milling different orebodies.BackgroundUranium mining in Saskatchewan started in 1953 when the Beaverlodge Mine, owned by Eldorado Nuclear Limited (Eldorado), came into operation at Uranium City. Development in the Athabasca basin started in 1975 when the Rabbit Lake mine came into operation. This was followed by the start-up of the Cluff Lake mine in 1980 and the Key Lake mine in 1983. The McClean Lake mine is forecast to start up in the near future. The McArthur River mine recently received construction approval and the Cigar Lake Project and the Midwest Project are currently in the environmental approval process.The Beaverlodge operation ceased production in June 1982 after nearly 30 years of operation. The Rabbit Lake mill processed Rabbit Lake ore from 1975 until 1985, Collins Bay R-Zone ore from 1985 until 1993, and is currently processing ore from the Eagle Point mine (Bharadwaj, Jarvi and Lam, 1996). The Cluff Lake mill processed ore from the D- Orebody from 1980 until 1984. Since then the Claude orebody has been processed and the OP and DS orebodies are presently being milled (SRK. Senes and Melis, 1987; and Cogema Resources Inc. 1994 ). The Key Lake mill processed ore from the Gaertner ore body from 1983 until 1989 and Deilmann ore has been processed since (Cameco Corporation, 1992b and I 994a). Processing of McArthur River ore in the Key Lake mill is scheduled for 1999. The McClean Lake mill will be processing ore from the JLR, Sue and McClcan orebodies associated with the McClean Lake mine. In future ore from the Cigar Lake and Midwest projects will be processed in the McClean Lake mill. (Minatco Limited. 1991a)."

Jan 1, 1998

By Jim Hazzard

A numerical investigation is presented to examine fluid flow in fractured rock slopes. In mining geomechanics, different numerical modelling approaches are used to estimate fluid pressures in open pit mines. The most common technique is the Equivalent Porous Medium (EPM) approach in which the fractured rock is assumed to behave as a porous continuum. Depending on the geometry and properties of the problem, this may not always be the best approach. The paper presents a parametric study to examine the effect of fracture spacing, fracture and matrix diffusivity and excavation rate on the fluid behaviour in rock slopes. Based on the model results, guidelines are provided as to when EPM models can be used and when different modelling approaches (e.g., discrete fracture flow) may be necessary.

Jun 1, 2012

By David Morley

This paper considers the ideal truck-excavator combination, defined as the combination resulting in the lowest direct unit cost, in consideration of multiple haul scenarios characterized by different haul distances, material and equipment availability. Through the application of Monte Carlo simulation, selected for its unique ability to handle the uncertainty of activity durations, the ?four to six passes? loading rule is shown to not correlate with the selection of the minimum cost fleet. Additionally, through the results of the simulation it is determined that the haul truck capacity has a greater effect on the overall efficiency of the system than does the excavator capacity. As a result, in order to arrive at efficient operations, the entire earthmoving system must be viewed as whole, namely, considering haulers together with excavators, as opposed to the popular method of first selecting a loading unit and then selecting a hauler obeying the ?four to six passes? loading rule. Furthermore, truck utilization and excavator utilization exhibit an inverse relationship and neither directly correlates with the overall efficiency of the earthmoving operation. The following conclusions are drawn: first, with limited financial resources, it is more valuable to increase hauling unit size before increasing loading unit size and second, predefined rules or generalizations, not based on evidence, potentially eliminate optimal truck excavator combinations from being considered.

Aug 1, 2013

By Y. Masuda, Y. Nakamura, K. Haraguchi, A. Taniguchi, K. Arita

Availability of the elements originating from steelmaking slag for various marine phytoplankters including purely cultured strains and natural populations was tested in land and shipboard laboratories. The results obtained demonstrate that, although their solubility was not uniform among different slags, dissolved iron, silicate and phosphate from the slag stimulate phytoplankton growth. No negative effect of the slag addition on their growth was observed at lower dose, e.g. less than 200 mg/l. Since most coastal waters are the hypernitrogenous environment due to anthropogenic load of ammonium, the slag can be an ideal source of silicate and phosphate, which restore the hyper-nitrogenous condition into truly eutrophic condition with balanced Redfield ratio. In so-called HNLC (high-nitrate low-chlorophyll) oceanic areas such as the Southern Ocean and the subarctic North Pacific, where iron is almost only limiting factor of the phytoplankton growth, the slag could also be a source of iron and enhance CO2 fixation by phytoplankton photosynthesis. (Key words: carbon deposition in deep-sea, marine environmental remediation, phytoplankton, slag as a source of iron, phosphate and silicate.)

Jan 1, 2004

By Pierre O'Dowd

"The southern Abitibi Belt is the major source of gold in Quebec. Although the northern part of the belt is quickly being developed, the area under study will not be downgraded in the near future because it still contains more than 75% of the known reserves in the belt.Gold is found in a variety of geological environments which are part of a small number of distinct structural patterns. For the exploration geologist, outlining such patterns might be easier and more productive than defining, when it is possible, the exact genetic nature of the gold mineralization.Exploring in the right place has always been one of the main concerns of explorationists. This paper briefly describes the various favourable geological settings, and outlines areas, types of structure and lithologies of high potential for gold exploration in the southern Abitibi Belt.IntroductionThe southern part of the Abitibi Belt is a profilic mining area for precious and base metals (Lulin 1990). Although mineralizing processes and controls of polymetallic deposits are well known and understood (Lydon 1984), almost every gold occurrence is a unique case and numerous models have been proposed (Roberts 1987; Hodgson and McGeehan 1982; Hodgson 1990).This study does not define new genetic models for the formation of gold deposits, neither is it meant to elaborate on the existing ones. A genetic approach, is by definition, theoretical and, to some extent, universal. It helps geologists define types of targets and exploration tools but does not outline or quantify target areas. To tentatively summarize the complexity of a genetic approach, a brief discussion on the various genetic models in vogue in Abitibi and the problems related to their use in exploration can be found at the end of this paper."

Jan 1, 1991

By J. H. Pateson, D. C. Comrie, D. J. Ritcey

"Geopolymers are inorganic semi-amorphous three dimensional silico-aluminates of the poly(sialate) type (-Si-O-Al-0-) or of the poly(sialate-siloxo) type (-Si-O-Al-O-Si-0-). Polycondensation occurs at low temperatures with geopolymers being stable up to 12oo0 c. Research, development and application technology pertaining to geopolymers is being undertaken jointly with Dr. Joseph Davidovits of The Institute for Applied Archaeological Sciences of Florida, U.S.A. This joint focused upon the chemical Barry University in Miami Shores, research and development program has stabilization and solidification of various waste products through geopolymerization. Of particular interest is the geopolymerization of mine wastes including tailings and waste rock derived from the processing of base metals, precious metals, potash, coal and uranium deposits.INTRODUCTIOND. Comrie Consulting Ltd., in cooperation and technical liaison with CANMET, Ottawa has been testing the application of geopolymers to mining wastes. Corporate efforts to date have concentrated upon reactive acid tailings, principally from the abandoned Kam-Kotia Mine site, and dewatered paint waste sludges. Test work conducted to date has successfully yielded geopolymer treated materials and wastes with increased chemical and structural stability. Wastes containing heavy metals, cyanides, arsenic and sulphur dioxide have been successfully geopolymerized."

Jan 1, 1988

By E. Norton

"Even though the subject of this panel discussion is dust control, rather than dwell on the design aspects of dust collection systems which are well documented in numerous publications, :it was considered more pertinent to the present economics of mining to examine the energy costs involved.At the present time, the facts of shrinking fossil fuel reserves and spiralling fuel costs are being constantly brought to our attention. Industry is being motivated to consider the possibilities of incorporating heat recovery systems in areas where they prove to be economical. Unfortunately, it is not a simple exercise to determine if the installation and operation of heat recovery equipment is feasible and economical. Each process involving heat recovery potential must be thoroughly studied in all aspects.In a paper presented at the 1975 Annual General Meeting of the Canadian Institute of Mining and Metallurgy in Toronto, Ontario, entitled ""The Influence of Energy Conservation on Concentrator Design"", it was stated that the largest single energy consumer in winter is space heating with the largest portion of this supplied to crushing and screening plants. (1) Within the scope of this panel discussion we will study, as one example, a crushing and screening plant using natural gas heat in the province of British Columbia and we will explore the feasibility and economics of installing air-to-air heat recovery equipment."

Jan 1, 1976