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By H. I. Kim

The leaching of a complex matte in chlorine and chloride media was studied. The matte was prepared from manganese nodules by the reduction smelting-sulfidation route. From XRD analysis, the major phases of the matte were identified as CuFeS2, CuS2, (FeNi)9S8, (FeNi)S2, Ni9S8, Ni3S2, (CoFeNi)9S8 and Co metal. Investigated were the chlorine, hydrochloric acid, hydrochloric acid-oxygen, ferric chloride, ferric chloride-oxygen, cupric chloride and cupric chloride-oxygen systems. The results are discussed in terms of reagent concentration, retention time, leach temperature and gas sparging rate. The chlorination process resulted >99% metal extraction efficiency within a short retention time and at atmospheric temperature. However, there were no preferential extractions of Cu, Ni and Co with respect to Fe. The cupric chloride-oxygen system produced leach liquors with the lowest Fe content and with a high base-metal extraction. Sulfide sulfur was converted to mixtures of elemental sulfur and sulfate in all the studied systems.

Jan 1, 2009

By Paul H. Johnson

The CH Leaching process is a new, more sophisticated, form of gold, silver, uranium and sulfide copper heap leaching wherein each layer of a multi-layered heap is divided into a number of independent cells, each of which are successively formed and leached in the top layer of the heap to their maximum economic recoveries, and then rinsed and sealed from further leaching. Triangular earth berms form the outside walls of the heap and a gridwork of rock-filled berms on top of the bottom pad form independent under- heap solution storage zones. The high degree of solution recirculation and staging that occurs in this process produces a relatively small volume of very rich pregnant solution. The cellular heap design and its mode of operation result in a uniform, intensive, long-term leach for all of the ore particles in the heap. Besides improved metal recoveries, the process appears to have several cost and operating advantages. In the CR2MR process, sulfuric acid and a soluble sulfide are added to a gold and/or silver pregnant leach liquor to precipitate most of the contained silver, mercury, copper, etc. as sulfides at a pH below 2.5. The other product of the reaction is solubilized HCN. Following a liquid-solid separation step, cyanide is regenerated in the supernatant solution by raising the pH to a level above 9.0. This process regenerates a portion of the cyanide used in the leaching step, removes contaminant ion species (silver, copper, mercury, etc.) from the leach solution and, in a subsequent step, recovers the gold in an enriched form. It is believed that substantial cost savings may be experienced by the use of this process in some gold and/or silver leach systems.

Jan 1, 1984

By W. Collingwood, K. V. Raj, S. Bandopadhyay

In the mining industry, computational fluid dynamics (CFD) modeling is used extensively to simulate air flow in underground mines. CFD modeling of pollutant transport in openpit mines is relatively new. Modeling the actual pit geometry of an openpit mine and the open domain is complex. The complexity is primarily due to the faceted geometry of an openpit mine with its numerous associated sharp features. Important issues that are not considered carefully at the geometry level are generally propagated to the subsequent processes. Several challenges and pitfalls are encountered in modeling pollutant transport in openpit mines. These challenges and pitfalls are related to the geometry, meshing, boundary conditions and turbulence modeling parameterization. An appropriate mesh selection is critical. A detailed discussion of the meshing of the domain of an openpit mine is presented in this paper. The selection of an appropriate turbulence model, such as kappa-epsilon (κ-ε), large eddy simulation (LES), Reynolds stress model (RSM), etc., to obtain the best possible solution is equally significant. This paper discusses the various challenges in modeling the pollutant transport process in an openpit and some of the approaches adopted to address these challenges.

Jan 1, 2013

By Erwin Riyanto, Roy William, Karl Llewellyn

The Deep Mill Level Zone (DMLZ) mine is currently one of the deepest block cave mines in the world. The rock mass is heavily veined with little to no joints and faults are usually healed cohesive structures leading to difficult cave mining conditions. The caving process is improved if the rock mass contains fractures with sufficient density that it will cave by gravity as undercutting progresses. Hydraulic fracturing (HF) has been used to create fractures around the cave to improve mining. A seismic monitoring system has been used in DMLZ since the start of mining. Therefore, the seismic activities before, during and after HF can be monitored. Shear wave splitting is a process used to study the impacts of HF on the rock mass. This process involves the measurement of travel times from splitting shear waves after seismic events and using this to define the anisotropy within the rock mass and subsequently fracture density. This paper sets out the methodology for carrying out the interpretation of the shear wave splitting process using seismic data from the fracked cave crown and abutments along with an overview of the benefits to cave mining as result.

Apr 26, 2022

By J. A. Burger

Research in the eastern U.S. has shown that productive mine soils and forests can be restored using the following guidelines: (1) cooperation among the mine operator, landowner, and regulatory authority in developing the mining permit; (2) replacing topsoil or creating a desirable medium in which trees are planted; (3) loosely grading non-compacted topsoil; (4) using native and non-competitive domestic ground covers that quickly protect the site; and (5) planting a proper silvicultural mix of crop trees for their commercial value along with nurse trees for wildlife and soil improvement.

Jan 1, 2002

By D. R. Taylor, R. G. Goss

The use of clay granules as carriers for pesticides dates from the early 1940's and by the present day represents a business conservatively estimated at between 200 - 300 thousand tons / year in the U.S. alone. Aside from economic and specific target pest efficacy advantages, the use of clay granules as pesticide carriers also delivers a number of environmental benefits which will be reviewed. Topics to be discussed will include: 1) drift control (versus liquid sprays), 2) mobility (in the environment), 3) worker safety, and 4) transportation (spill) safety.

Jan 1, 1999

By H. Maleki

This paper recognizes the 100th year of research accomplishments by the mining industry resulting from close cooperation among mining companies, geotechnical consultants and researchers from the former United States Bureau of Mines in stability assessments and development of improved and productive mine designs. The paper provides an overview of dramatic developments in geotechnical instrumentation, and its applications in the U.S. and around the world for enhancing the understanding of ground response to mining-induced changes in stress, resulting in improvements in ground control technologies.

Jan 1, 2010

By Jerry C. Tien

Mining in China dates back at least 4,000 years. Today, with no less than 103,000 metal/nonmetal mines and between 40,000 to 80,000 coal mines, China’s mining industry is undoubtedly the largest in the world. Despite improvements in recent decades, seemingly endless mining accidents continue to make the news. Official coal mining deaths were 6,702 in 2003, and 6,027 miners died in 2004; actual figures may be much higher. Added to these were the 2,699 deaths in the metal and nonmetal industries. Most of these accidents were due to CH4 (methane gas) explosions and fires as a result of inadequate mine ventilation de-sign or practices. A good portion of these accidents occur in small, privately run and often technically illegal mines. During the past 10 years, the Chinese government has attempted to crack down on small and often technically illegal mines without much success. The number of accidents and associated fatalities has not significantly reduced. However, there appears to be a new urgency in China’s efforts to step up mine safety in the country. After its worst reported mine disaster in more than a half century, the government quickly paid reparations to families, suspended high-level officials in charge and announced additonal reforms. One of those was the elevation of the central government’s work safety office to cabinet-level status. There has been increased transparency in reporting and investigation of mine accidents and disasters in recent years. There has also been an increase in public criticism by labor leaders concerning the neglect of mine workersafety.1 This article examines the causes of China’s many mining accidents, current legal and enforcement structures, respective mining health and safety related laws and regulations, recent mining industry developments and the latest effort to curtail small mining operations.

Jan 1, 2005

By Douglas B. Silver

"Editor’s note: Douglas B. Silver, Portfolio Manager, Orion Resource Partners, was the keynote speaker at the 2017 SME Annual Conference & Expo in Denver, CO on Feb. 19, 2017. He also gave the keynote address to the SME Annual Conference in 2008. The following is his 2017 keynote address with a few of the slides that were presented. The full speech is available on YouTube https://www.youtube. com/watch?v=uF0qwGJIX3UIn 2008, I had the privilege of giving SME’s keynote address. At that time the financial markets were on the verge of collapse and my presentation described the issues. Unfortunately I was correct, and global markets went into a steep nosedive, creating the largest economic downturn since the Great Depression.In hindsight, there were plenty of signs that this was coming. The Supercycle had created massive new wealth. This wealth was largely invested in the United States due to the country’s political stability and credit worthiness. In 2004, the large investment banks convinced the U.S. Securities Exchange Commission (SEC) to allow them to triple their borrowing leverage ratios. This made the banks more vulnerable to market volatility. The banks then lent money to NINJAS - people with no income, no job and no assets. Even worse was the fact that these unqualified home owners used adjusted-rate mortgages (ARMs) which they, of course, intended to refinance prior to interest rates rising. These mortgages were then bundled up by the banks and sold to investors as “safe” investment products. The money flowed into these products because the rating agencies gave these instruments high marks. These same agencies earned their fees from the very same banks seeking high ratings. (No conflict there). Private debt exploded and peaked out in 2008.These mortgage products were sold in an unregulated shadow banking system and the ARMs came due. Toxic mortgage default rates skyrocketed and the mortgage-backed securities collapsed in value. This house of cards had a negative feedback loop that accelerated the market crash and resulted in more than $1.5 trillion being lost in the securitization sector, a 47 percent decline in the Dow Jones Industrial Average, foreclosure rates skyrocketing and housing prices collapsing. The financial markets were in a nosedive."

Jan 8, 2017

By J. P. Rider, T. W. Beck, J. A. Organiscak

"The National Institute for Occupational Safety and Health (NIOSH), Office of Mine Safety and Health Research (OMSHR) has recently developed a series of models utilizing Computational Fluid Dynamics (CFD) to study gas distribution around a continuous mining machine with various fan-powered flooded bed scrubber discharge configurations. CFD models utilizing Species Transport Model without reactions in FLUENT were constructed to evaluate the redirection of scrubber discharge toward the mining face rather than behind the return curtain. The following scenarios are considered in this study: 100% of the discharge redirected back towards the face on the off-curtain side of the continuous miner; 100% of the discharge redirected back towards the face, but divided equally to both sides of the machine; and 15% of the discharge redirected toward the face on the off-curtain side of the machine, with 85% directed into the return. These models were compared to a model with a conventional scrubber discharge where air is directed away from the face into the return. The CFD models were calibrated and validated based on experimental data and accurately predicted sulfur hexafluoride (SF6) gas levels at four gas monitoring locations. One additional prediction model was simulated to consider a different scrubber discharge angle for the 100% redirected, equally divided case. These models identified relatively high gassy areas around the continuous miner which may not warrant their use in coal mines with medium to high methane liberation rates. This paper describes the methodology used to develop the CFD models, and the validation of the models based on experimental data.INTRODUCTION Methane gas and respirable dust are two hazards frequently encountered at continuous miner (CM) operations. An accumulation of both methane gas and coal dust may lead to massive explosions underground [1], and overexposure to respirable coal dust can result in pneumoconiosis (commonly referred to as “Black Lung Disease”) in coal workers [2]. Current U.S. federal coal mine regulations limit concentrations of methane gas to below 1% at the face area and require exposures to respirable coal dust to be at or less than 2.0 mg/m3 for an 8 h shift average. Begin on August 1, 2016; the overall respirable dust standard in coal mines is reduced from 2.0 to 1.5 mg/m3 for full shift sampling. If the quartz content of the dust exceeds 5% by weight, the dust standard becomes more stringent, reducing the allowable concentration to the value of 10 divided by the % quartz."

Jan 1, 2015

By Immo H. Redeker, O. E. Pothier, E. W. Gieseke

Phosphate rock is the primary source of phosphorus, an element necessary to all forms of life--plant, animal, and human. While phosphorus finds many uses in everyday life, it is an irreplaceable ingredient in all complete plant foods. With the present need for intensive farming, the fertility of the soil can be maintained only by external additions supplied by mines or other sources. A major consideration in any mining operation is to establish the economic and ecological impact of the development on the local population as well as the national interest. The Commodity Data Summaries, as published by the U.S. Bureau of Mines (USBM), is a ready reference concerning the importance of phosphate to the national and local interest. The summary of domestic and world pro¬duction is given in Table 1. During 19722 the demand for marketable phosphate rock exceeded the supply in the United States and the rest of the world. Domestic and world reserves are more than adequate to meet furture demands. Phosphate rock prices firmed and export prices increased, reflecting the change from oversupply to a shortage of phosphatic fertilizers. Demand is expected to exceed supply through 1973. New fertilizer plant capacity planned for 1973-74 will increase the production of phosphate rock by more than 5 million tons in the United States. Morocco and Spanish Sahara are scheduled to increase their production to 18 and 3 million tpy, respectively, within 2 to 3 years. The domestic phosphate rock production for 1972 was 40.8 million tons and 1973 was 42.1 million tons.' Industry, with government-supported programs, will emphasize restoration of mined land and solution of the colloidal slime disposal problem in Florida. The foregoing information comes by courtesy of The Division of Nonmetallic Minerals of the U.S. Bureau of Mines, January 1973. The summary gives a great deal of information but does not give a complete picture. There are many supporting industries which contrib¬ute to the area in which the mines are located. The figures shown in Table 1 deal with concentrates. To produce such concentrates many more tons of waste overburden and ore must be moved. Because of the competitive nature of the phosphate rock industry, data on concentration ratios not only are difficult to obtain but also are not for publication by companies. The concentration ratios vary from one mine to the next in Florida as well as in Tennessee and the western United States. To produce 42.4 million tons of phos¬phate rock in the United States required moving about 350 to 400 million tons of material. Domestic Industry. In 1972 some 26 firms and the Tennessee Valley Authority produced phosphate rock, with several firms produc¬ing from more than one mine. The distribution of marketable phos¬phate rock production was: Florida and North Carolina 82%; Idaho, Montana, Utah, and Wyoming 13%; and Missouri and Tennessee 5%. The value of this production was $223 million. The principal consuming classifications were: agriculture 75%, soaps and detergents 5%, plating and polishing 3%, animal feed supplements 4%, and miscellaneous applications 13%. Over 5,000 firms processed end-prod¬ucts for agricultural purposes. Uses of Phosphate Rock. The tendency in the United States has been to produce more phosphoric acid by the wet process, while the production of electric furnace phosphorus, triple superphosphate, and ordinary superphosphate has been on the decline. Exports of phosphate rock have been on the increase for several years and in 1971 reached 33% of total production. However, export sales of phos¬phate rock are expected to decline in the years ahead, both in total tons of sales and in percentage of production as domestic sales increase (see Table 2). The description and chemistry involved in the production of phos¬phate fertilizers is too complicated to be presented here. The Waggaman13 book is a very thorough reference on the subject involv¬ing production, utilization, and chemistry. The various operations generally have chemical plants near the dry plants or ship to associated chemical plants for further processing. Wet rock, dry rock, and ground dry rock of various grades are sold. In addition various grades of calcined phosphate rock, including defluorinated phosphate rock for animal food supplements, are pro¬duced. Various grades of phosphoric acid, superphosphate, triple suerphosphate, as well as diammonium phosphate, are produced. These products are available from the various producing compa¬nies listed in the text. For prices and specifications the producing companies should be contacted.

Jan 1, 1985

By Madan M. Singh

This section is unique to the Handbook in that it is the only section that deals with underground excavations for nonmining purposes. The editors were of the opinion that the section should be incorporated because the subject matter covered by the chapters is closely related to mining, and many mining engineers are currently involved in these activities. As we enter the decade of the 1990s activities in this category will increase, enhancing the relevance and utility of the material discussed. As the population increases, especially in metropolitan areas, the necessity to go underground will be greater. At the present time, not only are subsurface shopping malls and pedways connecting buildings becoming commonplace, but structures as diverse as the Civil and Mining Engineering Building on the University of Minnesota campus, a road-and-fleet maintenance facility in Multnomah County, OR, and even an ice cream parlor (Dairy Queen) in northern Wisconsin have been constructed underground. Placing utilities below the surface has numerous advantages and is now customary. Rapid transit and highways through tunnels in urban areas have been the norm for many years, but subterranean stormwater reservoirs, power plants, industrial warehouses, and food storage silos are relatively new innovations. The philosophy of underground defense installations is ancient, but their requirements and designs have trans-formed radically as technology advances. The use of under-ground space for disposition of wastes is modern, since it is recently that environmental concerns and waste disposal costs have assumed increased significance.

Jan 1, 2008

By Lee Ann Arrington-Webb

Thiele Kaolin Co. has invested much time and money in achieving and maintaining its IS0 9002 certification. Through a regimen of process control and documentation, routine audits and a commitment to quality management, this kaolin producer is a competitive pigment supplier in a worldwide market. Background In 1987, the International Organization for Standards developed the ISO 9000 quality management system. This series of standards is used as a means to ensure customers that a quality management system is in place. Certification of a company does not mean that an individual product is of high quality. Rather, it demonstrates a supplier's ability to meet its customers' product and service needs. It also shows that a company has documented records to assure product consistency. The ISO 9000 system was begun in England during the early 1980s. During the mid-1970s, the British manufacturing industry was experiencing low quality. In an attempt to boost quality standards, the British government established the BS 5750 standards system. In 1987, BS 5750 was incorporated into ISO 9000. The ISO 9000 series consists of three levels of certification. ISO 9001 is the model for quality assurance in "design/development, production, installation and servicing." This standard applies to companies that rely on research and development to bring products that frequently change to market. ISO 9002 involves "production and installation" only. This standard is relevant to industries that produce a specific product according to specifications - either their own or their customer's. ISO 9003 is the model in "final inspection and test." This standard is the least detailed of the 9000 series. It is also the most applicable to companies that purchase, inspect or sort and resell. The quality system requirements for certification are outlined in the 18 elements of ISO 9002. These include: 4.1 - Management responsibility. 4.2 - Quality systems. 4.3 - Contract review. 4.4 - Design control. 4.5 - Document and data control. 4.6 - Purchasing. 4.7 - Control of customer-supplied product. 4.8 - Product identification and traceability. 4.9 - Process control. 4.10 - Inspection and testing. 4.11- Control of inspection, measuring and test equipment. 4.12 - Inspection and test status. 4.13 - Control of nonconforming product. 4.14 - Corrective and preventive action. 4.15 - Handling, storage, packaging, preservation and delivery. 4.16 - Control of quality records. 4.17 - Internal quality audits. 4.18 -Training. Continuous improvement, though implied in maintaining these requirements, could potentially be included in the quality system requirements in the next revision. The ISO 9000 requirements and documentation system is shown in the hierarchy pyramid (Fig. 1). A company's quality policy serves as the top of the pyra-

Jan 1, 1997

By R. L. Bullock

The New Lead Belt of Missouri, situated in the heart of the Clark National Forest, stands as a dynamic example of how mining activities can successfully coexist in a restricted wilderness area. After 16 years of intensive drilling activity, mine development and surface plant construction, many would agree that the mine-plant design philosophy of St. Joe has minimized the imbalancing effects to the ecology and the wilderness appearance of the Ozark area. In a recent dedication speech of St. Joe's newest operation, it was stated: 1 "this Brushy Creek Mine, as well as nearly all of the mines in this district, lies within the boundaries of the Clark National Forest. Here the Forest Service has an outstanding and realistic program for multi-use of Federal lands. Mining, lumbering, recreation and conservation coexist in, what I consider, a delightful wilderness environment. I believe that this same type of usage could be permitted on all government land without seriously detracting from its natural beauty." Each and every activity in the process of discovery, exploration, development and finally operating a mine and process mill could have drastically degraded some phase of nature's environment were it not for the well developed and executed plans of the mining people involved. This is not to say that everything has been kept in perfect balance; but most certainly the industrial impact on what was once a wilderness area has been held to a minimum. What follows is the story of how each phase of this gigantic development was handed by industry people. Through their interaction and cooperation with government agencies, educators and researchers, allowed not only the ecology of the area to be protected, but the aesthetic beauty of the Ozarks to remain intact.

Jan 1, 1973

By John L. Shafer

Often an in situ leach is the only practical economic method for copper recovery from small low grade oxide deposits. The decision to develop a copper property by an in-situ blast and leach is strongly dependent on ore grade, tonnage, hydrology, and the copper extraction and acid consumption rates. The inherent "leachability" of the ore will in part determine the desired amount of fracturing of the ore deposit by the blast in order to obtain a copper extraction rate that is economical. For the last several years Occidental Research Corporation (ORC), the corporate R&D for Occidental Petroleum has under-taken a modest effort to address the question of "how to best identify and determine the information necessary to predict and control the operation of an in-situ leach for the economic recovery of copper."

Jan 1, 1977

By H. Fayed

Two-phase (water and air) flow in a self aerated WEMCO flotation machine has been investigated using computational fluid dynamics (CFD). A 0.8 m3 model is considered. The flow is modeled by Euler-Euler approach, and transport equations are solved using a commercial software ANSYS-CFX5 [1]. Because of the lack of circumferential periodicity in this machine, the entire machine is modeled and unsteady simulations are conducted in the whole volume of the bulb. Uniform bubble diameter is specified, and the effects of bubble diameter are determined by conducting simulations for three diameters of 0.5, 0.7, and 1.0 mm. The unsteady air flow rate through the machine is predicted as an outcome of the simulations. Air volume fraction contours and velocity field in different parts of the machine are presented and discussed.

Jan 1, 2012

By W. R. Reed, J. P. Rider

"The National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) has recently developed a series of models utilizing computational fluid dynamics (CFD) to study airflows and respirable dust distribution associated with a medium-sized surface blasthole drill shroud with a dry dust collector system. CFD models were constructed in ANSYS FLUENT Version 15. Previously run experiments conducted in the NIOSH full-scale drill shroud laboratory were utilized to validate the models. The setup values in CFD models were calculated using experimental data obtained from the drill shroud laboratory and measurements of test material particle size. Subsequent simulation results were compared with the experimental data for test scenarios, including 0.14 m3/s (300 cfm) bailing airflow with 2:1, 3:1, and 4:1 dust collector-to-bailing airflow ratios and 0.24 m3/s (500 cfm) bailing airflow cases with 2:1, 3:1 and 4:1 dust collector-to-bailing airflow ratios. For the 2:1 and 3:1 ratios, results showed the calculated dust concentrations from the CFD models were within the 95% confidence intervals of the lab experimental dust concentrations. This paper describes the methodology used to develop the CFD models, to calculate the model dust input, and to validate the models based on experimental data. Problem regions were identified and revealed by the simulation of a dry dust collector system. The simulation results could be used for future development of dust control methods for a surface mine blasthole drill shroud. INTRODUCTION In surface mines, production drilling is an essential process in blasting which fractures the hard rock overburden for removal. Holes with a predetermined pattern, diameter, and depth are drilled into the overburden to introduce explosives. During the drilling process, considerable amounts of respirable dust are produced. Past research conducting area sampling at blasthole drills has documented time-weighted average respirable dust concentrations ranging from 8.68 to 95.15 mg/m3 [1] and 1.04 to 52.30 mg/m3 [2]. These high dust concentrations, which may contain silica, can lead to respirable dust over-exposures for the drill operator, drill helper, and other personnel in the vicinity. These over-exposures can lead to silicosis, an occupational lung disease that has no cure and is ultimately fatal. In order to prevent the development of silicosis to mine workers, the Mine Safety and Health Administration (MSHA) regulates the exposure to respirable dust. For metal/nonmetal (M/NM) mines, MSHA has adopted the threshold limit values recommended in 1973 by the American Conference of Governmental Industrial Hygienists (ACGIH) [3]. The total airborne dust standard is 10 mg/m3. However, if the sample contains greater than 1 percent quartz (the most common form of crystalline silica), a respirable dust standard is calculated with the following equation: Respirable dust standard = (10 mg/m3) / (% respirable quartz + 2)"

Jan 1, 2016

By D. Dodgen, L. Larrimore

Electric utilities depend heavily on coal as a major fuel source for power generation, annually producing more than 85 million tom of ash, boiler slag and FGD (flue gas desulfurization - "scrubber") materials as by-products. Utilities and others who bum coal have traditionally disposed of these by-products in ponds or landfills. However, in the last 10-15 years there has been a greatly increased emphasis on beneficial utilization of these materials by the producers themselves as well as by customers who purchase the by-products. Regulatory, cost and technical performance issues currently impact the use of coal ash and other coal combustion by-products (CCB).

Feb 24, 1997

By Eric Forssberg, Ming-wei Gao

Four parameters of the Drais stirred ball mitt, i.e., bead load, bead size, flow rate and top feed size have been studied regarding their influence on the specific surface area. A factorially designed scheme was employed for conducting 27 mitting tests. The results show that the bead toad is the most important parameter in terms of increasing the specific surface area with less energy consumption. The bead size is also important. The optimum ratio of bead size to top feed size is found to be 14 to 80, which is much wider than in bat2 milling. The variations in flow rate and top feed size appear to influence the process insignificantly.

Jan 1, 1992

By W. M. Middleton

The exploiting of geothermal steam is a new endeavor in this country and is for that matter a very new science in the world. With the majority of steam wells in the world having been drilled during the last twelve years relatively little experience and knowledge has been gained that can guide us as compared to the techniques the oil and gas producers have developed for their use. We few technical personnel associated with the field find it a continuous challenge to understand and explain what effects or causes the various unusual phenomenon experienced. We have had unending discussions attempting to formulate pet theories which we can use as guides. We know, so the geologists tell us, that the source of the heat is from the hot magmatic core of the earth. Theory has it that the magma is cooling off and that hot gases are given off as this magma cools and shrinks. In volcanic' areas along fault lines where the magma reaches closer to the surface than in other areas, there is a higher concentration of gas evolution; consequently, geyser or geothermal areas are developed. As these hot gases rise toward the surface they encounter various minerals, including overlying bodies of water. It is into these underground lakes that our wells are penetrating. As the heat enters these lakes it spreads out by conduction, convection and water migration. We can strike this hot water over quite large areas in many of the geothermal fields. At present there is one anomaly to this in the United States as there is in Italy where our wells do not penetrate a hot water lake. This is at The Big Geysers in California. Here superheated steam is produced with a heat content, so high that it could not have been boiled off of a fresh water pool. This puzzled us until last year when a well was completed into a large body of brine in the Imperial Valley. This brine exists at close to 500°F and at a hydrostatic pressure sufficient to preclude any boiling. It is now believed by some of us that a similar pool of brine must exist below The Big Geysers area, from which the steam is emanating. If there is such a brine pool, it offers a plausible explanation of the high-heat content, for brine boils at a higher temperature than fresh water. I am now beginning to think that a similar brine pool may exist under all the geothermal basins for if it is under two of them, it is highly probable that it is under the others. The partial understanding of what we are drilling toward, and formulating a theory to explain its behavior helps guide us in our steam well drilling.

Jan 1, 1963