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By Randolph C. Specht

A two year study was made of the waste disposal of the pebble rock phosphate industry. Solid slimes are impounded in large settling areas and the process water is re-used. Clear effluent was not found to be toxic to fish, or animal life in field tests or in controlled experiments.

Jan 1, 1950

By N. T. Rempe

The underground voids that result from mining provide opportunities for deep geologic waste disposal (DGWD). Such disposal could solve many environmental problems. DGWD takes careful planning, technology transfer and true partnership between waste generators and mine/repository operators. The US government is now planning on using specially mined excavations to dispose of radiotoxic and mixed waste. Using the experience gained from the domestic projects that are now in preparation and from foreign repositories that are now in operation, US mines can claim their rightful share of the growing market for DGWD.

Jan 1, 1998

By N. T. Rempe

The underground voids that result from mining provide opportunities for deep geologic waste disposal (DGWD). Such disposal could solve many environmental problems. DGWD takes careful planning, technology transfer and true partnership between waste generators and mine/repository operators. The US government is now planning on using specially mined excavations to dispose of radiotoxic and mixed waste. Using the experience gained from the domestic projects that are now in preparation and from foreign repositories that are now in operation, US mines can claim their rightful share of the growing market for DGWD.

Jan 1, 1997

By N. T. Rempe

Proper use of natural resources is multiple use. Underground space resulting from mineral extraction offers opportunities for deep geologic waste disposal (DGWD) which can solve many environmental problems. U.S. government projects plan to use specially mined excavations to dispose of radiotoxic and mixed waste. DGWD takes careful planning, technology transfer, and true partnership between waste generators and mine/repository operators. Using the experience, accumulated by domestic projects in preparation, and by foreign repositories in operation, U.S. mines can claim their rightful share of the growing market for DGWD.

Jan 1, 1996

By John M. Warde, Raymond M. Richardson

What to do with atomic wastes is one of the major problems of the atomic age. Unlike other waste materials, these cannot be burned, evaporated, or filtered, and the transfer of radioactive material from one physical or chemical state to another is not a complete answer, because only time diminishes radioactivity. Rate of decay of radioactive materials varies from a few seconds to several thousand years and cannot be altered by known economic methods. At present the Atomic Energy Commission and its contractors are coping with the situation adequately. Intensification of private development of atomic power could, however, pose problems in the nation's nuclear energy program.

Jan 5, 1955

By G. R. Denham

Innovative designs, mining, construction and reclamation practices are used at PT Newmont Nusa Tenggara's Batu Hijau mine on Sumbawa Indonesia to develop a cost-effective, environmentally sound, stockpile and dumping system. The mine production rate is over 200 million tonnes per year (50 million tonnes processed with 150 million tonnes being stockpiled for processing later or placed in waste dumps). Dump development for over 150 million tonnes per year in a mountainous, tropical environment, while meeting environmental and permitting requirements is not an easy task. The effective implementation requires innovative techniques and practices from every department of the mine.

Jan 1, 2002

By Paul Piercy

Bougainville Copper Limited operates a porphyry copper mine in Papua New Guinea. The waste dumps will contain 400 to 500 million tomes of rock at the end of nine life. The paper describes investigations carried out over a period of en years and highlights the problems associated with waste lump leaching in a tropical and seismic active region. Aspects discussed include mineralogy, chemical reaction, leaching rates, microbiological activity, dump stability, dump structures, effects of tropical conditions, seismic activity and topography.

Jan 1, 1981

By Knezicek Zeljko, Knezicek Tihomir

Lignite open cast mine "Dubrave" is the largest lignite mine in Bosnia and Herzegovina. The open cast mine was designed with two external waste dumps. Waste dump "West" is the major dump, while "Cajici" dump is used for dumping waste taken from leveling the terrain. The major waste dump contains 14.6 million cu.m. of waste, while the side waste dump contains 3 million cu.m. of waste. Existing situation with available sites for depositing the waste shows that additional space for dumping the waste must be provided. Three options can be taken into consideration. The fact is that none of the three options are suitable for the current production situation. This article deals with the optimization process for obtaining the optimal variant where a waste dump can be located and selection of the most valuable option.

Jan 1, 2002

By W. P. Tassie

"The location of Quintette Coal Limited's pit and geologic nature of the dedicated reserves combine to introduce a number of factors which can adversely affect waste dump stability. These factors include steep terrain, variable material type and particle size, and precipitation. This paper describes the solutions to related waste dump problems. A brief geotechnical review of the waste dumps is given and Quintette's operational strategies during periods of dump stability and instability are discussed. Despite best efforts, failures occasionally occur and discussion is included on Quintette's success at bringing failed dumps safely back into use. IntroductionQuintette Coal Limited (QCL) property is situated on the east slope of the Rocky Mountains near Tumbler Ridge, approximately 120 km southwest of Dawson Creek, British Columbia. This surface mine is located on mountainous terrain and is subject to climatic extremes of wind, precipitation and temperature.QCL has a current annual production of 4.75 million tonnes of metallurgical coal with a stripping ratio of 7: 1. This correctly implies the extraction of over 33 million bank cubic metres (BCM) of waste which is placed on numerous waste dumps at various locations adjacent to the pit.There are three active pits - Mesa, Wolverine, and Shikano (Fig. 1). Shikano is a newly developed pit located near the plant site. It is not subject to the unique dump management problems prevalent at the Mesa and Wolverine pits, therefore the Shikano waste dumps will not be discussed . The dumps for the Mesa and Wolverine pits, however, have been technically and operationally challenging since shortly after mining began in 1983. Their characteristics, associated site specifics and management, therefore, are the subject of this paper.Waste dump locations for the Mesa and Wolverine pits are shown in Figures 2 and 3 as is the relative waste distribution . Each sub-pit is connected to a principal waste dump in reasonable proximity and to an alternate dump should disposal of waste be necessary at that location. The waste dumps are constructed from the top elevations initially to coincide with subpit development. In the initial years (1-7) waste dump heights will be up to 250 m, then, as the mine matures (8-20 years), waste dump maximum heights will continuously decrease to coincide with lower bench elevations"

Jan 1, 1988

By A. Yazadni-Chamzini

Considering the nature of open pit mines, harvest volume, it usually is required to remove a lot of waste to access to mineral planned grade. So, one of the most important part of open pit mines design, is waste dump site selection. Many factors are effective in waste dump site selection. These factors are sometimes in conflict with each other. So selecting the desired location for waste dump is a process complex and multi-criteria decision making. There are a variety of methods for decision making under complicated condition, such as fuzzy, Delphi, multi-criteria decision making and Expert system methods can be hinted. VIKOR method, which is one of the decision making multi criteria methods, is useful tool for decision-making. On the other hand with regard to uncertainty in decision-making, fuzzy approach is a useful tool for this purpose. This article has tried to select the best waste dump site in Sari Gunay Gold Mine by Fuzzy VIKOR. The results show that C position has a higher priority than other positions.

Jan 1, 2012

By Robert S. Nichols

Fording Coal Limited's mine in the Rocky Mountains near Elkford, B.C. has produced 21.8 million clean tonnes of metallurgical coal from 1971 to 1980, inclusive. This production has come from several pit areas and required the removal of 149.1 million bank cubic meters of waste rock and overburden by truck-shovel and dragline operations. Waste dumps from 30m to 200m in height have been successfully constructed on natural slopes, generally between 10° and 26°. Design considerations for the dumps include foundation and soil conditions, natural slope angles and containment of weak overburden or rehandle materials. Dump control is maintained by monitoring the crest and the face of an active dump area. Crest movement is measured by extensometers locally termed "Spoil Monitors". When crest movement rates progressively increase above normal, dumping operations are temporarily relocated. Some unstable conditions and mass failures have occurred as the result of natural foundation slopes being in excess of 26°, failure of weak water saturated foundation soils or weak material being placed on the dump.

Jan 1, 1983

By Adam R. A

Techniques for the optimisation of open pit design and development are now accepted as standard practice in the mining industry. These techniques are used to analyse the impacts on project profitability of factors such as product price, slope design criteria and equipment selection. A fundamental assumption used in this type of analysis is that dump and stockpile designs and sequencing are predetermined. The cost of haulage for a typical truck shovel mining operation is in the range of 25 - 50 per cent of mine operating costs. Substantial cost savings can be achieved by optimisation of dump design and location of associated road and ramp systems.Factors which affect both the operation and total cost of dumping include; Ramp gradients and location, road design, dump placement and shape, dumping height, slope design (interim and final), slope stability, environmental requirements and equipment selection. This paper discusses these factors and their effects on the total mining operation and project value. Reference is made to case studies in which some of these factors have had a significant impact.

Jan 1, 1992

By W. A. Zingg

Impervious zones in copper waste heaps create a problem in contacting the rock with leaching solutions. These zones are normally associated with compacted layers .formed on the surface of each lift by dump truck traffic and by disintegration of the rock exposed to atmospheric conditions. These layers are usually only a few feet in depth--but, nevertheless, act as barriers to vertical flow causing the leach solution to perch in the heap, Consequently, much of the rock remains untouched and the leach solution breaks out the side of the heap instead of continuing downward to bedrock. One solution to this problem is breaking the hard pans with explosive charges. However, to use explosives means adopting new explosive materials and methods. To use this process successfully requires finding answers to operating conditions inherent to waste heaps. Foremost among these are: (1) type and size of casing that can be used because of limitations brought about by drilling problems, caving and, corrosive conditions; (2) perforating the casing at required levels; (3) an explosive capable of being pumped; (4) obtaining detonation of the, main charges through, the wail of the casing; (5) an explosive with the ability to propagate through the voids of the rubble and one which is not affected by water, acidic solutions, or back pressure conditions from hydrostatic heads; (6) to heave and rupture the compacted zones without chambering or recompressing the waste material.

Jan 1, 1970

By Cassandre Nowicki, Louis Gosselin, Carl Duchesne

"Quebec's primary aluminium production industry consumes roughly 39 TWh of electricity per year and is accountable for roughly 7 million tons of CO2 equivalent. By tapping only a small portion of waste heat and integrating it inside the production facility itself, we can significantly reduce GHG emissions and energy consumption. Although the amount of thermal waste can be adequately estimated by applying an energy balance to production processes, this provides very little information on the quality of waste heat and its potential for integration. A measure of exergy is required. Waste heat streams characterized by high exergy content may generally offer valuable incentives for recovery and integration. More generally, exergy values limit integration possibilities. An exergy analysis is provided for the aluminium electrolytic reduction process. This is meant to guide future heat recovery initiatives and energy efficiency measures.IntroductionCanada is one of the world leaders in primary aluminium production and 92% of its aluminium production capacities are located in the province of Quebec. In 2007, production capacity reached 2,786,000 tons in Quebec alone. Since it is estimated that 2.5 equivalent tons ofCO2 are released for each ton of aluminium produced in Canada, Quebec's aluminium production industry is accountable for roughly 7 million tons of CO2 yearly [1, 2]. Furthermore, with an average electricity consumption of 14 MWh per ton, primary aluminium accounts for 39 TWh of electricity per year in Quebec and this energy consumption represents 350 thousand tons ofCO2 equivalent [3, 4]. Natural gas consumption associated with primary aluminium production accounts for less than 1 TWh, but it represents an additional 350 thousand tons of CO2 equivalent [ 4].This work is meant to provide a tool to guide future efforts towards heat recovery and energy efficiency in the primary aluminium industry. Waste heat recovery and thermal integration can cut down both energy consumption costs and GHG emissions. In a primary aluminium production facility, waste heat represents roughly half of the energy input into the Hall-Heroult process. Tapping only a small portion of this energy could reduce natural gas and electricity consumption significantly. In order to evaluate how much of this energy is actually usable, we propose to apply an exergy analysis to individual transformation processes in an aluminium production facility, such that a potential to do work can be assigned to every waste heat flux. The approach will be described in the next section."

Jan 1, 2012

By Maria S. Gudjonsdottir, Miao Yu, Gudrun Saevarsdottir, Pall Valdimarsson

Around half of the energy consumed in aluminum production is lost as waste heat. Approximately 30–45% of the total waste heat is carried away by the exhaust gas from the smelter and is the most easily accessible waste heat stream. Alcoa Fjarðaál in east Iceland produces 350 000 tons annually, emitting the 110 °C exhaust gas with 88.1 MW of heat, which contains 13.39 MW exergy. In this study, three scenarios, including organic Rankine cycle (ORC) system, heat supply system and combined heat and power (CHP) system, were proposed to recover waste heat from the exhaust gas. The electric power generation potential is estimated by ORC models. The maximum power output was found to be 2.57 MW for an evaporation temperature of 61.22 °C and R-123 as working fluid. 42.34 MW can be produced by the heat supply system with the same temperature drop of the exhaust gas in the ORC system. The heat requirement for local district heating can be fulfilled by the heat supply system, and there is a potential opportunity for agriculture, snow melting and other industrial applications. The CHP system is more comprehensive. 1.156 MW power and 23.55 MW heating capacity can be produced by CHP system. The highest energy efficiency is achieved by the heat supply system and the maximum power output can be obtained with the ORC system. The efficiency of energy utilization in aluminum production can be effectively improved by waste heat recovery as studied in this paper.

Mar 1, 2018

By Geir Wedde, Anders Sorhuus

"Vast quantities of energy are released as heat to the environment from industrial operations. Many countries target waste heat recovery to mitigate CO2 emission. Exhaust gases from industries such as primary aluminium smelting, carry a substantial portion of the waste heat generated. For a cost efficient capture of more valuable heat (higher exergy), heat exchangers should operate on the exhaust gases upstream of the gas treatment plants. Heat exchange surface would be exposed to dust laden gases with risk of fouling. Heat exchangers of innovated design and operation have overcome the potential of excessive fouling rates. Heat exchangers of the ""shell and tube"" design have been demonstrated for exhaust gases from ferroalloy as well as primary aluminium smelters. In addition to the heat recovery, gas cooling results in smaller gas treatment plants with lower costs and reduced emission. The aluminium experience is exampled in the paper.IntroductionIndustrial usage of energy continues to grow as a result of increasing volumes of production, a trend that is likely to continue in the coming decades as living standards keep rising globally. World energy consumption (Figure la) is to grow 49 % by 2035 (ref. 2010) as reported by EIA [1]. The industrial sector consumes somewhat more than 50% of the total world energy consumption predominantly the energy increased demand comes from non-OECD countries in Asia. The industrial consumption by production of metals iron and steel accounts for 14 % and for non-ferrous metals 3 % mostly for aluminium production (Figure lb). Aluminium production will be discussed in this paper as an example of an industry with large quantities of waste heat to recover"

Jan 1, 2012

By John Norton

"This presentation will cover the physical properties of waste heat recovery. It is a two part presentation. The first deals with actually recovering the heat with new state of the art heat exchangers and applying that heat to the furnace combustion and the second part will cover what other processes you can enhance with this ""free"" heat. It will also talk about converting it to steam, hot air or electricity to be used or sold back to the utility company. The economics of various schemes will be reviewed. A brief discussion on State and Federal grants and subsidies will be presented.IntroductionThere are large quantities of wasted heat in the usual aluminum melting process. And, there are several techniques for reducing and/or using some of that wasted heat as you have seen. Any technique that can make use of wasted heat is a form of recovery. This can range from simply preheating aluminum billets prior to melting, to more complicated processes like air-to-air heat exchangers using the boiling and condensing characteristics of special fluids in “heat pipes.” The objective of this type energy recovery process is to move the wasted heat from the hot and dirty exhaust gas stream into some useful process.Waste Heat Recovery in the Aluminum Melting Furnace.There are considerations, of course:1) What might the value be of the recovered energy?2) Can the recovered energy be used within the process? Within the plant? Or by theneighbors?3) What is the capital cost?4) Is the recovery process complicated?5) Will it take additional staff?6) Will it cause additional downtime on the melting line?7) Will the operations staff need to be licensed?Ideally, the process will be simple and inexpensive, the recovered energy will be very valuable, and the whole effort will cause little distraction to the aluminum melting process itself. These would be ideal."

Jan 1, 2011

By James C. Sever

"With the advent of high energy costs and increasing concern for the environment leading to the incorporation the C02 life cycle as a criteria for the material used in a finished product, it is beneficial to analyze the plant and the process used in producing a raw material in order to identify practical, economic energy recovery opportunities. To this end a study was made of the proposed Nevada Clean Magnesium, Inc. Tami-Mosi reduction facility. Each source of waste heat is listed together with the assessment for potential co generation or direct recovery. The overall impact on energy requirement and C02 generation is provided.IntroductionHistorically metal reduction plants, large consumers of energy, do not recover waste heat. This occurred for many reasons:• Energy costs were low and the capital for a co-generation system could not be justified;• Waste heat sources contained entrained solids or liquids which would inhibit efficient energy recovery;• The exit temperature for the heat source was too low for efficient use by aaqueous Rankine cycle system.The business environment has now changed adding impetus to the recovery of energy previously discarded. Power costs have greatly increased. Global warming and the impact of carbon dioxide on the environment has become an issue which could impact the permitting of a plant. Technology improvements especially the development of a scaling environment waste heat boiler [l] and the development of the organic cycle Rankine cycle recovery system enable up to 70% energy recovery from ""low grade"" heat sources [2].With the inception of Nevada Clean Magnesium, Inc. 's (formerly Molycor Gold Corporation, Inc.)Northern Nevada Tami-Mosi project [3], an opportunity was presented to incorporate energy optimization from the initial design phase."

Jan 1, 2013

By T. S. Reddy

Research and Development Centre for Iron and Steel (RDCIS) a unit of Steel Authority of India Limited (SAIL) is continuously engaged in reduction of energy consumption at SAIL plants by implementing innovative and new concepts. In this regard, continuous efforts are being made to recover waste heat in Sinter Plants. This paper discusses existing waste heat recovery measures taken and proposed measures planned in Sinter Plants. One such effort is on waste heat recovery from sinter coolers. Hot sinter is discharged to the crusher at the end of the sinter machine at a temperature of 500 to 800°C. Temperature of hot sinter is brought down to nearly 100°C in the sinter cooler with air-cooling. The air after cooling the sinter is generally discharged to the atmosphere at about 225 to 300°C. It is planned to recover heat from the hot air that is being released to atmosphere and heat the process water, which is being added at ambient temperature in mixing drum at Bhilai Steel Plant. The temperature of raw sinter mix will be raised by addition of this hot water, which will help in improving the productivity of sinter machine. It is estimated that Waste heat recovery to the tune of 1.5 to 2.0 Gcal/h is possible with reduction in CO2 emissions in the range of 4000 to 5000 ton/year. The novel approach that is being adopted is addition of hot water in mixing drum for higher sinter productivity for the first time in India. Keywords: waste heat recovery, sinter plant, hot water generation, emission reduction, CDM

Sep 1, 2012

By Reza Kamali, Mohsen Bashiri, Hadi Fanisalek

"Half of the input energy to aluminum reduction cell will be lost as waste heat which could be studied for possible recovery. Since price of energy is increasing and the main production cost in primary aluminum industry is energy, so waste heat recovery consideration will be interesting. One of the possible choices for recovering is from aluminum exhaust gases that needs minimum modifications for reduction cell and has no influence on cell heat balance which is vital for the operation. By using heat exchangers with in-line and staggered tube arrangements which placed before fume treatment plant (FTP) we will be able to recover enough amount of heat. The main challenging problem which is necessary to overcome will be the heat exchanger material and its design because of corrosive and dusty exhaust gases from potroom. In this paper, a desalination system with six effects of evaporator is proposed for producing distilled water by using recovered heat from hot exhaust gases. The calculated amount of produced distilled water is around 27,000 / in this specific suggested desalination plant. The suggested desalination plant is based on Hormozgan Aluminum Company data (Hormozal) in Bandar Abbas, Iran which is constructed by the Persian Gulf.IntroductionWaste heat losses arise both from equipment inefficiencies and from thermodynamic limitations on processes. The exact quantity of industrial waste heat is poorly quantified, but various studies have estimated that as much as 20 to 50% of industrial energy consumption is ultimately discharged as waste heat [1]. In order to achieve a final decision for establishing the waste heat recovery plant in any type of industry, a strong feasibility study is mandatory. Also, we need to remember that the possible amounts of energy and suggested process plant for recovery have to be investigated before starting any feasibility study. This kind of study which is important to be finished before moving to feasibility step is mainly a theoretical study, and was done for the Hormozgan Aluminum Company (Hormozal). In addition to the exhaust gases from the potroom, the exhaust gases from anode baking plant appear to have a better potential for waste heat recovery compared to potroom exhaust gases. The average temperature of exhaust gases from anode baking kiln is 120°C higher than the exhaust gases temperature in the potroom. This needs further investigation in a different study, because this study is just focusing on potroom exhaust gases."

Jan 1, 2011