Search Documents

By Chulho C. Song, Liam Coleman

Alkaline pressure oxidation (POX) is an oxidative pre-treatment option that is commercially used for high-carbonate sulfidic gold ores. The high carbonate grades within the feed ore shifts the ideal operating pH to a basic regime. Compared with acidic POX, alkaline POX typically requires additional steam input due to a lower sulfur oxidation load and a high rate of in-situ carbon dioxide generation that needs to be vented along with steam. The cost of this steam addition is the largest differentiator between acid POX operation and alkaline POX from a cost comparison. However, alkaline POX can offset these costs through reduced acid usage for pre-acidulation and decreased alkali reagent consumption for subsequent neutralization. This paper reviews the specific operating cost impacts of acid/base consumption between alkaline and acidic POX with ores which require pre-acidulation, the overall economics of alkaline POX, and the regimes in which alkaline POX is economically favorable. The findings aim to guide industry professionals in making informed decisions for alkaline POX adoption by providing a summary view of its operational benefits and costs, contributing to the development of cost-effective and sustainable gold ore processing techniques.

Feb 1, 2025

By T. Uysal

The increasing demand for rare earth elements (REE) in highly strategic sectors such as hybrid electric vehicles, renewable energy, communication technologies, and the defense industry has made REE production methods important. In recent years, studies on REE have increased rapidly; however there are many studies on REE, there are not enough studies in the literature on the economics of the beneficiation process. RE ores are generally leached after beneficiation by gravity, magnetic and flotation methods. In this study, direct leaching, attrition scrubbing and leaching, and flotation and leaching methods are evaluated economically based on the data for the Mountain Pass (MP) facility. According to the sensitivity analysis performed as a function of capital cost (CAPEX), operating cost (OPEX), and rare earths oxides (REO) recovery, REO recovery has the biggest effect on the process economies. Although the flotation method entails additional investment and operating costs, transportation and operating costs are significantly reduced result of the higher grade and recovery. The flotation method is more profitable, with larger NPV and IRR values and a shorter payback period.

Jul 2, 2022

By M. Kumral, E. Dilhuydy, B. Ozdemir

"In-pit crushing and conveyor (IPCC) systems have become increasingly popular in the mining industry as an alternative to truck-and-shovel systems. Deciding whether to haul waste rock by truck or IPCC represents an important gap to be investigated in semi-mobile IPCC systems. A cost analysis is presented to evaluate the feasibility of crushing and conveying waste material in IPCC systems, along with sensitivity and risk assessments through Monte Carlo simulation. Although the capital expenditure is higher, results showed waste crushing will be feasible in deep pits and over long mine life and haul distances.RÉSUMÉ La popularité des systèmes de concassage et de transport dans la fosse minière (IPCC, de l’anglais In-pit crushing and conveyor) n’a cessé de croître dans l’industrie minière ; ils constituent en effet une option intéressante de remplacement des systèmes par camions et pelles mécaniques. Le choix entre le transport des stériles par camions ou par IPCC est encore difficile à faire et devra faire l’objet d’une étude approfondie au niveau des systèmes d’IPCC semi-mobiles. Une analyse des coûts est présentée pour évaluer la faisabilité du concassage et du transport des stériles par les systèmes d’IPCC, de même que des évaluations de la sensibilité et des risques par le biais de la simulation de Monte Carlo. Si les dépenses en immobilisations s’avèrent être plus élevées, les résultats ont cependant montré que le concassage des stériles sera envisageable dans des fosses profondes ainsi que sur une longue durée de vie et de longues distances de transport. INTRODUCTIONThe mining industry is currently facing many challenges such as low commodity prices, increasing environmental concerns and regulations, lower grades, deeper mines, and greater waste-rock quantities. As a result, the profitability of mining operations has decreased, with many mines stopping or suspending operations, and many new projects being postponed. Mining companies have therefore focused on improvements and innovations to increase the cost effectiveness of operations, for example, increasing production capacity to take advantage of the economies of scale (Crowson, 2003) and decreasing the unit operation cost. Changes in production capacity force mining companies to evaluate alternative material handling systems.During the past few decades and within material handling systems, significant improvements have been made to truck performance and capacity. Consequently, operating expenditures (OPEX) associated with fuel and maintenance have risen swiftly. In a mining operation, truck hauling systems now represent 40–50% of the capital cost and approximately 45% of the OPEX (Tutton & Streck, 2009). Additionally, material transportation costs are expected to increase due to longer haul distances arising from deeper and larger mines (Fleet et al., 2015). Finally, large fluctuations in fuel prices result in high risks associated with truck OPEX. According to the United States Energy Information Administration (2015), the cost of crude oil—the largest component of the retail price of diesel fuel—increased from US$24.31/barrel in 1986 to US$46.92/barrel in 2016, peaking at US$151.72/barrel in 2008 (Macrotrends, 2016)."

Jan 1, 2017

Since the early 1990s it has been evident that electricity demand has outstripped investment in generation and transmission. At the same time, concerns were being expressed about the risks associated with the run down of the Maui gas field. It is axiomatic that the necessary investments firstly require a stable and supportive regulatory and fiscal environment, and secondly that such investments have long lead times. A unwillingness by successive Governments to fund the necessary infrastructure, however, lead to the profound restructuring of the electricity with the ultimate objective of transferring the investment risk from Government to the private sector. Successive power crises since 1992 result from a failure to put in place a regulatory framework necessary to provide the environment to allow the private sector to make the needed investments within the necessary timeframe. The electricity sector has now stabilised to the extent that the regulatory risks associated with generation investment have been reduced. This does not mean that risk has been eliminated, however, and both economic and environmental issues will continue to constrain investment in some power proposals particularly those in the South Island and especially any South Island coal or gas thermal proposal. This is firstly because of several very simple economic issues:  1. while the South Island may have significant coal resources it lacks a significant electricity market; 2. except for a six to ten week period in a dry year, low cost hydro will price any large-scale South Island thermal out of the market which will restrict any large scale thermal station to a dry year and/or peaking load; 3. except for a six to ten week period in a dry year, export capacity on the HVDC link to the North Island is constrained to around 964 MWe (and 482 MWe from North to South in dry years); and 4. construction of any new thermal plant in the northern half of the North Island will price any South Island thermal station out of the market. There are also significant environmental issues associated with the establishment of a large scale thermally based power station in the South Island. Because the South Island lacks any large scale economically proven gas reserves, the environmental constraints considered are those associated with coal production. A coal mine dedicated to power generation will have significant on-site impacts associated, in particular those associated with disposal of opencast overburden and visual impacts. These will, however, be partially offset by the relative remoteness of such sites to population centres. What cannot be offset, however, is the off-site impacts, in particular, CO2, SOx and NOx emissions, water disposal and acid mine drainage.

Jan 1, 2003

By Guozhu Ye, Mikael Larsson, Eric Burström, Sten Ångström

"Increased use of scrap in steelmaking including scrap use in BOF has a high economic and environmental potential in terms of increased productivity, energy saving and reduced emission of CO2. Preheating and surface cleaning of steel scrap is a concept developed by MEFOS in a four year research program funded by MISTRA, Swedish Foundation of Strategic Environmental Research. The process concept consists of four major steps: 1) Combustion of ASR or other waste fuel and composing of the gas composition. 2) Scrap heating and cleaning in a shaft where the coated zinc is removed as ZnCl2 and scrap is heated to about 600 ºC. 3) Dust separation for recovery of metal zinc. 4) Gas cleaning. This paper will describe the process concept and highlight the major results from preliminary trials around the scrap heating and cleaning shaft.IntroductionSteel is often coated to increase the corrosion resistance. Share of coated and galvanized steel in the world marked is steadily increasing. This results in increased amounts of scrap with different types of coatings. Use of galvanized scrap in EAF plant results in an EAF dust with high content of zinc ferrite and many other impurities like Pb, Hg, Cd and halide. EAF dust is classified as hazardous waste in most of the developed countries and the steel plant has to pay for external treatment for zinc recovery. For use in BOF plant this will result in a BOF dust containing typically 1-5%Zn making it impossible for recycling to the blast furnace.Different approaches for surface cleaning have been investigated in past. Dapper et al. [1] examined the possibility to evaporate Zn, Ni, Cr, Sn from coated materials using chlorine. Chlorinated rinsing of non iron oxides and metals using HCl from combustion of PVC was discussed by Fray [2]. Further studies by Tee and Fray [3-5] have been concentrated on the possibility to vaporize coatings with an air and chlorine gas mixture. The O2:Cl2 ratio in the gas mixture was found to have great importance for control of the process. To avoid the chlorination of iron, this ratio should be kept at a level of 10:1.Scrap pre-heating up to about 600 ºC is a well known method and this alone could save up to 100 kWh per ton steel. The technology has been established since many years and efficient processes were developed in the 90’s. However, no process has fully gained the expected energy savings as the large quantity of the exhaust gas has to be reheated to over 1000 ºC again to destroy the hazardous components like dioxins."

Jan 1, 2008

By Emily Chen, Randolph Kirchain, Gabrielle Gaustad

"As prices and demand for aluminum metal have increased over the past few years, secondary production has begun to outpace primary aluminum production. However, while recycling of packaging and automotive scrap has continued to increase, aerospace secondary materials remain a largely untapped resource. Shredded or co-mingled aerospace scrap has a high degree of compositional uncertainty due to the prevalence of high copper and high zinc alloy series. Although it is clear that upgrading strategies enable increased usage of aerospace scrap, it is not clear that they would be economic or efficient. Previous studies by the authors have shown that modeling techniques, specifically chance-constrained optimization, provide the ability to evaluate upgrading options in terms of potential aerospace scrap utilization and production cost. Three specific cases are analyzed: a dismantled case, a sorted case, and a shredded or co-mingled case; sensitivity analysis of resulting compositional uncertainty is also presented.IntroductionAluminum recycling has a number of key environmental and economic benefits. Secondary recovery forestalls depletion of non-renewable resources and avoids the deleterious effects of extraction and winning (albeit by substituting some effects of its own). For most metals, the latter provides strong motivation for recycling; for light metals, like aluminum, the motivation is compelling[1]. Fortunately, as prices and demand for aluminum have increased greatly over recent years, secondary production has begun to outpace primary production (Figure 1). However, while the recycling rates of many aluminum products such as used beverage cans and cars have increased over this period, aerospace secondary materials remain a comparatively untapped resource.This untapped resource for scrap aluminum is a very large one; aluminum is the primary aircraft material comprising about 80% of a planes unladen weight[2]. It is used extensively for airframes, landing gear, engine components, propellers, and interior trim. A standard Boeing 747 jumbo jet, for example, contains approximately 75,000 kilograms of aluminum[2]. At an approximate rate of 300 per year, more than 6,000 civil aircraft are forecast to arrive at end-of-life in the next 20 years, potentially creating a large aerospace scrap market[3]. Many military aircraft are already available for possible scrap use, however, most are currently in storage at air force bases around the world[4]. The underutilization of these aerospace scrap materials indicates a lack of economic end-of-life options."

Jan 1, 2008

D. B. DOWLING,* Ottawa, Ont.-I do not propose to start any argument, but really there is a comeback to what Mr. Coste says.1 Geography is probably not geology, but geology is geography. You cannot regard structure as geography on the surface, but it is geology as soon as you get under the surface. In Canada, it is quite true that they went too close to the Rocky Mountains. When boring in the foothills, as Mr. Coste says, they were too close to the mountains where they got into a faulted area, and if there had been storage, it probably would have lost a good deal of the oil. The situation in the Calgary field is one that might be interpreted in many ways, but in front f the foothills there is a very deep syncline. The gas and oil that is recovered on the edge of the, foothills is of such a nature that we must assume that it is not the pure crude oil. It seems to be somewhat refined, or a condensation product. The solution, or at least the argument that appeals to me, is that as the deeper part of that basin is, say, 6000 ft. below sea level, there must have been some breaking up of the oil on account of pressure and of the heat, and we are getting gas, traveling up toward the surface in the foothills; and as it comes up, it probably condenses again, and is caught in folds on the edge of the syncline so that we have a natural condensing machine there. The oil is not found on the eastern side of the folds, it is found on the western side. On the eastern side and on the summit there is a little light oil, gasoline, we will say, blowing into the well once in a while; now that looks like a natural condensation of the gas and a storage behind the summit.

Jan 5, 1919

By Richard J. Leary

At the 1976 Annual Meeting of AIDE, Alan Merson reminded his audience that economic' success comes to those who understand things as they are, rather than as they have been or what ideology says they should be (1). He went on to say that, measured by this standard, the mining industry is in trouble. The mining firms had recognized long ago the importance of effective lobbying in Washington and the state capitals. But, he pointed out, those methods are nearly worthless anymore in coping with many land use problems because the critical decisions are likely to be made at the local level. There the tactics are far different as are the relations of the decisionmakers to the parties before then. Furthermore, in his estimation the trend is to leave land use regulation largely to the local level of government. All who are concerned for access to land for mineral development will be benefited by reading Professor Merson's paper lie is speaking effectively about the context of decisionmaking for specific cases, the shape of things in the here and now. There is, however, a longer-tern set of considerations that if pursued will be likely to foster the creation of public support for mining developments. At that sane meeting I spoke on two foundations of the long-term relationships: namely, the growth in requirements for minerals implied by projections of increasing consumption; and a rationale for fostering mineral exploration and development. I mentioned in passing the social decisionmaking process for public uses of land (2). This paper is intended as a complement. The growth of requirements for Minerals and the rationale for development based on the Entropy Law will be only mentioned. The main concern will be on the process of social decisionmaking in the context of access to land for mineral development.

Jan 1, 1976

By J. A. Drozdiak, W. Tse, P. P. Rosario

"In a recent publication (SAG 2015), we presented a non-conventional high pressure grinding roll (HPGR)-ball mill circuit as a lower capital cost alternative to the “standard” HPGR circuit. The circuit was designed for the treatment of a hard ore and relatively high tonnage (50,000 t/d). That paper provided details such as flowsheets, layouts, and equipment lists for the two options and compared their calculated capital costs demonstrating significant savings for the proposed circuit. This paper extends the analysis to a third option, a traditional semi-autogenous ball crushing circuit, giving the same level of details and now including the operating cost estimates for all three options for a more comprehensive analysis. Moreover, this work also provides information about the strengths and weaknesses of the non-conventional HPGR circuit when compared to the “standard” HPGR option.This study demonstrates that the proposed non-conventional HPGR-based circuit not only provides a lower overall capital costs for the project if compared to a “standard” HPGR circuit but also brings the capital cost to the level of the traditional semi-autogenous grinding (SAG)-ball mill circuits. In addition, the innovative HPGR circuit provides similar operational cost savings of the “standard” HPGR and thus a significant advantage when compared to the SAG option. With the current capital cost sensitivity for most greenfield projects, the proposed alternative circuit should help make HPGR-based circuits more competitive and thus promote the utilization of a technology that enables higher energy efficiency and reduced greenhouse gas emissions. INTRODUCTIONThe application of high pressure grinding roll (HPGR) technology in comminution circuits is well established for the processing of cement, diamonds and iron ore (Broeckmann & Gardula, 2005), and over the past 10–15 years, this technology has slowly been applied to hard ores in high-tonnage precious and base metal operations. Unfortunately, under the current economic climate, the ability to finance large capital projects has become very difficult and companies tend to have an easier time securing funding if the capital expenditures (CAPEX) are low with a proven process method. The traditional semi-autogenous grinding (SAG) mill / ball mill circuits easily fit into this mould, having been installed in countless plants around the world over the past 30 years with relatively low capital requirements. In contrast, it has been well-documented that HPGR-based circuits are capital intensive with complex material handling systems (Seidel, Logan, LeVier, & Veillette, 2006). Although these circuits benefit from reduced operating costs with the increase in energy efficiency and the elimination of steel grinding media (Rosario, Boyd, & Grundy, 2009), if the company is unable to secure financing to build the plant, these advantages remain out of reach. With the current trend to retrofit existing SAG circuits with a secondary crushing circuit to achieve design throughput, the opportunity to circumvent this gross inefficiency by making HPGR-based circuits more capital friendly would greatly benefit the industry."

Jan 1, 2016

By John O. Galloway

"The year 1947 was a momentous one in the history of the petroleum industry in Canada. It was in that year that Imperial Oil Limited made its discovery at Leduc, the forerunner of other discoveries, large and small, and the spark wl1ich started a most intensive exploration and development programme there.If, to use boxing parlance, Leduc was the first blow of a one-two combination which left doubting Thomases groggy, then Redwater was the number two blow which achieved the knockout. The oil industry's exploration leaders did about-face without delay and the rush of oil operators of all classifications to western Canada began. It is still continuing, and the influx of capital which the operators have brought in and are bringing in has a bouyant effect upon the over-all economy. The boom is on, but it is a sound one, and it is difficult to conceive that it will have anything but the most beneficial effect on Canada, and particularly western Canada.The petroleum industry is an important segment of the general economy. Its activities call for tremendous amounts of capital; its employees are well paid; it is a large customer for a wide range of products of other industries; its commodities are essential to the citizens and the nation.The industry is carried on by highly aggressive and independent groups and individuals, of which a small minority are integrated while the majority are relatively small operators engaged in only one or two phases of the business. Competition is the rule and, since the nature of the business is mass production, the industry is faced from time to time with serious problems, many of which are peculiar to it."

Jan 1, 1950

By Seffen Leppla, Rolf Katzenbach, Matthias Seip

"Abstract The economic and safe design of deep foundation systems in difficult soil conditions is based on a reduction of construction material used, construction time spent, energy consumed and a high-level modelling of the soil-structure-interaction. The special foundation system Combined Pile- Raft Foundation (CPRF), in-situ load tests on the construction site and a sufficient soil investigation allow cost optimised constructions. In any case at challenging projects the observational method has to be applied for verification and quality control of the design. Regarding the 4-Eye-Principle as basis of the quality control management an independent peer review of the planning, design and construction phases is the guarantee for safety, serviceability and optimisation of all projects. Main execution standards for the construction of deep foundations based on the Eurocode 7 are summarised and discussed. The paper presents the basics of the safe and qualified design and construction of foundation systems including quality assurance. The application in engineering practice is shown on achallenging project of high-rise buildings with difficult boundary conditions.IntroductionThe construction of deep foundation elements in inner cities are special challenges due to the limited space for the construction works and the effects on existing buildings (Figure 1).An economic and safe design of deep foundation systems in difficult soil conditions is based on the following main aspects:•,qualified experts for planning, design and construction•,interaction between architects, structural engineers and geotechnical engineers•,adequate soil investigation•,design of deep foundation systems using the Finite-Element-Method (FEM) in combination with•,enhanced in-situ load tests for calibrating the soil parameters used in the numerical simulations•,quality assurance by an independent peer review process (4-eye-principle) combined with theobservational method if necessary"

Jan 1, 2014

By AIME AIME

LIFE in few countries is dominated by geographic conditions to the degree that it is in Peru. The broad plateau of the Andes, bordered by lofty ice-clad ranges with deeply eroded flanks, imposes a pattern on the region to which most human activities must conform. On the Pacific side, desert conditions prevail, interrupted only by irrigated valleys along rivers that descend from the highlands. Above seven or eight thousand feet the rocky ridges become grass covered, and the central zone is one of high pastures with cultivation in the valleys or on terraced slopes except at altitudes over 15,000 ft. where glaciated landscapes prevail. Each of the three belts has its own distinctive resources and climate, and each its own special ways in which its inhabitant, must make a living. The Pacific region is one of the most arid regions in the world. Except for the irrigation, the country is an unmiti¬gated desert. The climate, in spite of the tropical latitudes, is mild with the heat relieved by air from the adjoining cold ocean. Fogs are prevalent throughout the winter months but precipitation is scarcely measurable. Ideal conditions exist for cultivation of sugar and cotton which are the dominant crops. Lima, the capital. situated in one of the most productive valleys, is an impressive city which in its modern development is well maintaining the high position it held when it was the

Jan 1, 1945

By D. V. Bush

The economic application of real time computer control can be broken down into 2 broad areas of concern. The first would be in gaining the most efficient utilization of energy. The second would be in improved product quality. This paper will be primarly concerned with the first area of efficient energy utilization as that area has the greatest effect on costs and thus net profits. Most process control strategy attempt to achieve the greatest comminution with the least amount of energy thus maximizing efficiency. A more direct approach to energy control involves a total mine and mill energy management system. In most cases these systems have an ability to achieve a very short payback period with the greatest return on investment.

Jan 1, 1986

By Alvin Kaufman

The industrial revolution of the early 1800's and the subsequent remarkable progress in raising American living standards are based not only on a constantly improving technology but on an ever increasing use of energy from mineral fuels and waterpower. Industrial nations require inexpensive energy sources in order to grow. The more complex the economy, that is, the more intensive the processing of raw materials, the greater the energy needs of that economy. As a result of the current international economic expansion, the worldwide search for sources of low-cost energy has accelerated. As a part of this search there is considerable interest in the potential for commercial development of geothermal power, particularly abroad and in the western United States. This interest is indicated by the fact that 40 exploratory wells have been drilled in the California thermal areas alone during the 1955-62 period. Of these, 24 were drilled in The Geysers, Casa Diablo, and Salton Sea areas.

Jan 9, 1964

By R. R. Sacrison

The Barrick Mercur Gold Mine lies in the Oquirrh Mountains of northern Utah. Limestone, sandstone, shale, and chert are the predominant rock types being mined. Recent expansion has encountered rhyolite. Lithology and structural attitudes control most mechanical behavior. Slope steepening, mine planning, and site selection are presented as means by which geological engineering has contributed to the economics of the operation. Geomechanics investments of approximately $700,000 have resulted in cost savings or additional production worth over $16,000,000.

Jan 1, 1990

By R. B. Elver

The level of steel consumption per capita is one of the principal indicators of a country's standard of living. It is no coincidence that the materially advanced nations possess viable iron and steel industries to provide a reliable and economic source of steal for the manufacturing industries. No other metal is as dominantly important in manufacturing as steel. The blast furnace - steel furnace complex based on coking coal, ferrous scrap and iron ore - continues to be the principal steel-producing method. Less important is the electric furnace method based on scrap, In recent years, there has been considerable interest in the many direct reduction processes that are not dependent on coking coal but usually produce a product for further refining in steel furnaces. No matter which series of processes are used, iron ore is essentially the only source of virgin iron units. Thus, to such a vital and capital-intense industry as steel, access to a relatively inexpensive, long- term supply of iron ore is essential.

Jan 1, 1964

By Bradley Stoughton

It is very easy to reduce iron ore at a temperature well below its melting point and produce a more-or-less-pure metal which can be used directly for implements, tools, or machines. This simplicity has been the cause of much money loss by persons who were so satisfied with the successful operation of a process that they paid all too little attention to the commercial aspects of it. How easy a direct process is may be gleaned from the fact that it was practised with some -success by primitive man, and has been in almost continuous operation in one form or another for a period of probably 4,000 years. The production of steel in ton lots, beginning about 1860, brought a new phase into the economic situation, which, however, had been already greatly modified in 1784 by Henry Cort's invention of purifying pig iron. Direct processes survived both of these revolutions, under special geographical conditions, even up to the last few years of the nineteenth century, but ceased to have any general use as the basis of supply for structural, machine, or tool industries even in countries which could have manufactured iron by a direct process, but, instead, imported the product of established iron and steel processes. And this is still the situation today, notwithstanding the invention of an incredible number of 'new' processes since 1900, most of which are abandoned, and only survived as along as their financial backers were willing and able to Jose money. Probably none of these processes failed to work pretty well, and all seemed to show a handsome profit on paper.

Jan 1, 1930

By Joseph E. Pogue

THERE are two methods employed in the development of oil pools. The older and dominant method is one in which the primary object is the protection of the underground deposit from drainage through competing wells, and considerations of efficiency of extraction and cost of production are subordinated thereto. The newer and less prevalent method is one in which maximum efficiency and minimum cost are the first objectives and developments to these ends may proceed undisturbed by the exigencies of competitive drainage. The second method has developed mainly in pools under single ownership and the term "unit operation" has come to be applied to this procedure. A single ownership, however, is not essential to the method, for unity of operation may be achieved by agreement under split ownership, or even by a concert of enlightened purpose. There are examples of unit operation where neither the ownership nor the management is a unit, but merely where unity of procedure has been attained, as is the case of the Yates pool. .Throughout this paper unit operation is used in its broad sense without implying sole ownership or single management, although unit operation is more conveniently attained where these conditions are present.

Jan 1, 1930

By Gunnar Almgren

Hole deviation has great consequences on mining economy, especially for long hole drilling technique. First of all the bore hole datas are concerned but also such factors as development, loss of ore and waste rock dilution are influenced. Hole deviation for sublevel open stoping is illustrated with examples from some mines. The deviations are indicated as mean values but also as standard deviation values, owing to their statistical distribution. The economic influence of the hole deviation is especially studied for steep, small lowgrade orebodies, mined with big hole blasting. Hole deviation can thus influence costs up to US$ 3-4 per ton for operating, development, losses of ore and rock waste dilution. This cost is of the same magnitude as the total operating costs for many sublevel stoping mines. The economic savings in accurate drilling are therefore substantial and are worth all attention.

Jan 1, 1981

By Chester O. Ensign

Many publications to date have advocated under- seas mining operations, optimistically overlooking the paucity of information on mineral distribution and the ocean environments in which minerals occur. Such articles (smattered with opinion, as is this article) are herein tempered by my more conservative views on the economics of mining under the seas. For purposes of this paper, underseas mining refers only to the deeper surficial deposits of the continental shelf and the deep sea floor, i.e., the deposits of phosphorite and manganese nodules.

Jan 9, 1966