Search Documents

By David Butts

Solar ponding to crystdlize sodium chloride has been used for thousands of years.1 The systems used were inefficient and usually small compared to the large 25,000 acre pond areas seen today. It has only been in the last 25 years that any real effort has been applied to develop solar ponding technology. Many large solar pond systems have been constructed without much thought to efficient and optimum production rates. The recent high costs of labor, of equipment and of energy have forced producers to take a closer look at their solar pond systems in an attempt to squeeze out the highest possible yields. Other companies such as the Arab Potash Company, the Dead Sea Works, Texas Gulf (Moab, Utah) and San Francisco Salt Companies have no more land area in which to expand and therefore efficient ponds are essential. This paper is written to show how the subdivision of solar ponds can result in production increases of up to 20% and beyond.

Jan 1, 1984

By Li Zhang, Jing Zhao, Chuanwei Zang, Shuanlin Wang

The application of gob-side entry retaining (GER) in steeply pitching seam longwall mining with a hard roof has always been a difficult problem. Based on the simplified roof beam mechanical model, the traditional gob-side entry retaining by packing (GERP) roof structure evolution process and its problems with use in steeply pitching seams are analyzed. Therefore, based on the unique characteristics of the gangue rolling and accumulating in the steeply pitching seam, this contribution proposes an innovative method of gob-side entry retaining by roof cutting (GERRC) in steeply pitching seam and details its technical process. The roof structures of the GERRC and the GERP are compared. Taking the Chang Gouyu Coal Mine as a case study, field experiments were carried out. This research finds that the GERRC can both overcome the impact of rolling gangue on roadside support and make the rolling and stacking gangue become a roadside support. The roof structure of the GERRC is in a one-time statically indeterminate state, which is conducive to the stability of the roadway. In the field test, the total displacement of the roadway roof and floor is 97 mm, the supporting pressure of the serried single props is less than 28 MPa, and the props have no obvious bending phenomenon.

May 6, 2020

By T. J. Fenner

Surface and underground mining operations are often hindered by unknown tunnels and stopes and the precise locations of adjacent workings. Mine safety and planning are adversely affected especially in previously undermined areas where historical records are incomplete or non-existent. The results of several Ground Penetrating Radar (GPR) studies for the detection of known mine tunnels in underground coal; salt, and gold mines are presented. A case study to locate unknown, abandoned mine workings at a surface gold mine successfully located all workings to a depth of 11 meters.

Jan 1, 1992

By L. Rintala, P. Latostenmaa, T. Kalliomäki, O. Forsén, I. Lehtiniemi, M. Lundström, J. Aromaa

Conductivity is a typical physico-chemical property that has a substantial effect on electrical energy consumption in the electrorefining process. The objective of this study was to examine the validity of regression models predicting the conductivity of industrial copper electrorefining electrolytes. The models were based on data measured with synthetic solutions on a laboratory scale. The variables included in the models were temperature and the concentrations of copper, nickel, arsenic and sulfuric acid. Both first-order and combined effects of the variables were investigated. The measured data were analyzed using MODDE 8.0 modeling and design software. The validity of the models was investigated by comparing the predicted values with tankhouse conductivity measurements taken at the Boliden Harjavalta Copper Refinery in Pori in Finland. During the tankhouse tests, the conductivity and temperature of the industrial electrolyte were measured, and the composition of the electrolyte was analyzed. The measured conductivity values were compared with the predicted conductivities calculated using the developed models. The conductivity model developed in this paper was shown to be more accurate than previous models and suitable for industrial use.

By K. S. Whiting

Elevated concentrations of copper, cobalt, and arsenic within the Panther Creek Basin sediments in north central Idaho prompted an evaluation of the sources of the metals. Potential tailings and waste rock source samples collected at the head of Blackbird Creek were compared to sediment samples in the Panther Creek Basin using electron microprobe techniques. The mineral types, degree of alteration, and the morphology of the metal-bearing sediment grains within Blackbird and Panther Creeks were found to consist of copper-, cobalt-, and arsenic-bearing sulfide minerals.

Jan 1, 1997

By T. W. Camm

"Search Amazon.com using the keyword “leadership,” and you are rewarded with a list of over 144,000 titles. There is no shortage of books and articles, many of them well written, with excellent ideas. So why is there still a constant cry for effective leadership in organizations? Often, the person in charge has personal blinders that prevent them from seeing or understanding how to implement the newest leadership idea or method. Either deliberately or subliminally, there is a disconnect from learning about leadership, and actually modelling and implementing what has been learned. Some current research in leadership theory can provide insight and tools to address this issue. INTRODUCTION Let’s start with a discussion of terms. Pseudo is defined by Webster (2015) as “Being apparently rather actually as stated.” Synonyms include affected, assumed, contrived, fake, false, phony, pretended, and artificial. Antonyms for pseudo provide additional clarity, especially when we consider terms normally associated with effective leadership: genuine, natural, unaffected, unforced. A similar type from my world of academia is a pseudointellectual, “A person exhibiting intellectual pretentions that have no basis in sound scholarship” (Dictionary.com, 2015). This is a person pretending to have an interest in intellectual activities for status; a fraudulent intellectuality. The thought of applying the term pseudo to leadership first occurred to me while reading Power and Innocence by Rollo May (1972). In discussing the dynamics of power, and how the innocent are often victims of the exercise of power, especially the more aggressive and destructive types of power, he saw two types of innocence. The first he called authentic innocence, which he described as a childlike clarity that carried into adulthood. The second type he called pseudoinnocence, a type of naïveté that makes a virtue of powerlessness, weakness, and helplessness; being more childish than childlike (p. 48-50). Just as there is the potential for pseudoinnocence and pseudointellectuals, it is also possible to experience pseudo leadership. (I hope the gentle reader is not troubled by my decision to use pseudo leadership as two separate words, in contrast to the use of compound words for pseudoinnocence and pseudointellectual cited above. Since there is no official definition of pseudo leadership, I have exercised my author’s prerogative to treat it as two words, both because I think in this particular application this makes the most sense, and also I think it is easier to read). As we will see, there are numerous theories applied to leadership. What is so troubling to many of us in organizations, there are a myriad of “leaders” in companies espousing pet theories, but very few instances where the actions of these individuals match their words. This is a particularly important problem when we look at the effect this has on the day to day operations of a mine, and where effective leadership (or its absence) can have a profound impact on both productivity and safety."

Jan 1, 2016

By W. Lin

When a large area of open gob collapses suddenly, a windblast is produced that can cause considerable damage throughout the infrastructure of a mine. In a few cases, the windblast has been accompanied by ignitions of methane and/or coal dust. This paper describes the conduct and results of laboratory tests involving the compression of mixtures of air, methane and coal dust under a falling weight and while allowing controlled escape of the mixture. The transient responses on pressure and temperature sensors were recorded. In addition to an analysis of those records, the paper highlights those conditions in which ignitions occurred.

Jan 1, 1997

By L. Xinguang

Shandong MinMetals Corporation, a state-owned import and export organization located in the city of Qingdao, Shandong Province, China, was opened in 1954, with the mission of marketing metal products and industrial raw material in oversea areas for hard currency to support the modernization project of the country as well as the province. The management officers are appointed by the provincial government, and report to the Foreign Trade Department of Shandong Province. Meanwhile, the company also receives guidance from MinMetals head office in Beijing, the capital city of China. The head office does not own and control any provincial MinMetals organizations, but merely coordinate business among provinces.

Jan 1, 1990

By K. Kim, T. M. Yegulalp

A new explanation of the scale dependency of rock strength is presented based on the theory of extremes. A brief review of past work on specimen size and strength relationship is followed by an introduction to the fundamentals of the underlying theory of extremes and its relationship to the scale effect. It is shown that the weakest link theory is directly related to extremal statistics and that parameters of strength distributions of rock can be derived as a function of the specimen size. Three sets of Brazilian test data are used to demonstrate the use of this approach.

Jan 1, 1994

By QUANWEN PU, Yonggang Wei, Bo Li

The spent catalyst is one of solid waste resources, which contains precious metals with considerable recovery value. However, due to the different compositions of catalyst, the recovery process is difficult. Most of the catalysts are supported by alumina which has good alkali-soluble properties, while platinum is insoluble in alkali. Platinum is enriched by pressurized alkaline solution which is a kind of hydrometallurgical process. The novelty of this study is the separation of alumina and platinum from the spent catalyst and the enrichment of platinum in the solid phase. In this study, a leaching process using NaOH as leaching agent under high temperature and pressure was employed. The effects of alkali concentration, leaching temperature, leaching time, and liquid–solid ratio on leaching efficiency were investigated. The optimum process conditions were determined as follows: alkali concentration of 240 g/L, temperature of 200℃, pressure of 1.20 MPa, time of 1 h, liquid–solid ratio of 5:1. It was concluded that the leaching rate of alumina can reach 99.69%. The content of platinum increased from 0.1749 to 21.12%, the loss of platinum was 3.39%, and the enrichment ratio of platinum increased by 120.82 times. The leaching kinetics of alumina was studied based on the shrinkage core model. The activation energy of alumina leaching is 19.53 kJ/mol, and the leaching process is controlled by chemical reaction. Pressurized alkali solution can not only efficiently leachate alumina from the spent catalyst and enrich platinum, but also reduce the reaction time and increase reaction rate.

Feb 11, 2022

By B. Pesic

Manganese is about twelfth in the list of the most abundant elements in the earth's crust (Reidies, 1981). More than 150 known minerals contain manganese as an essential constituent (Mellor, 1932). In general, ores containing at least 35%Mn are classified as manganese ores, ores with 10-35%Mn are called ferroginous manganese ores, and ores containing 5-10%Mn are known as manganiferrous ores. One very important class of manganiferrous ores are manganiferrous-silver ores. They occur in the oxidized portions of the silver deposits of the Western United States. Silver is very often associated with manganese oxides which in some ore deposits are dispersed through calcite, causing the black color of the host rock, which is known as black calcite. Black calcites can occur in carbonate rocks (10-1500oz Ag/ton) and in volcanic rocks (less than 1.0oz Ag/ton).

Jan 1, 1986

By James R. Garvey

The impact of conversion on the coal industry can be summarized very briefly: We are going to have to mine an awful lot of coal. Fortunately, the United States has the coal reserves available, and given the right conditions, we can mine it. The coal reserves of the United States are enormous. If we consider them on the basis of proved reserves, using the standards of the petroleum industry--that is, resources mapped and explored and recoverable with present techniques at close to present costs--and compare that with the reserves of other fuels, coal constitutes 88 per cent of the proved recoverable energy resources of the nation. That includes oil, natural gas, oil shale and uranium, so long as the uranium is used in burner reactors. If we consider resources on the basis of "ultimate recoverable" reserves, that is, those resources which can be extracted with improved technology and at somewhat higher costs--and if we include those resources of all fuels not yet found but believed to be waiting discovery--coal still accounts for 74 per cent of the national total. We have built a hydrocarbon economy in which about 76 per cent of our total energy needs are supplied by petroleum and natural gas, and about 20 per cent by coal. Domestic resources of oil and gas are running dangerously low and, assuming a continued hydrocarbon economy, the 20 per cent supplied by coal may increase dramatically. We already import nearly a quarter of the petroleum we consume, and the chief source of additional imports seems to lie in the politically unstable Middle East. Natural gas is in even shorter supply, and the problems of importing it seem at least as difficult as those of oil. The fact is, the United States is already relying to an increasing extent on foreign fuel sources. There is an obvious national risk in making an important part of energy supply hostage to foreign governments of uncertain tenure and friendliness. There is also an economic risk--one of the chief reasons for last year's economic freeze was to try to correct the deficit in our balance of payments; it is obvious

Jan 1, 1972

By J. Noll, C. DeGennaro, C. Zhou, J. Srednicki

"The personal dust monitor (PDM) (model PDM3700), as well as other electronic devices, can cause electromagnetic interference (EMI) which can disrupt the operation of some proximity detection systems (PDSs). A 15 cm (6 inch) minimum separation distance between the miner-wearable component (MWC) of the PDS and the electronic device usually avoids these disruptions, but due to the amount of equipment on a miner’s belt and the method of wearing the PDM in some situations, this distance can be difficult to always reliably maintain. Another method of reducing EMI effects is utilizing magnetic field shielding. The shielding capability of several different materials was investigated by surrounding the PDM with the material and quantifying the EMI. A copper mesh pouch reduced the EMI from a PDM3700, allowing a minimum separation distance of 10 cm (4 inches) instead of 15 cm (6 inches) as shown in a previous study for an unshielded PDM. A MU-metal box had a better shielding effectiveness, as it further reduced the minimum separation distance to less than 7 cm (2.8 inches). Shielding reduced the EMI of the PDM with MU-metal providing better results than the copper mesh. These materials may be beneficial for shielding individual components of the PDM or for constructing a shielded pouch. However, before the advantages of a shielded pouch can be determined, the effects of just the shielding material (metal) on the PDS needs to be quantified. INTRODUCTION According to statistics from the Mine Safety and Health Administration (MSHA), 43 miners have been fatally struck or pinned by a continuous mining machine (CMM) since 1984. In an effort to prevent future striking and pinning fatalities from occurring, proximity detection systems (PDSs) have been developed and are required on all operating CMMs in underground coal mines, with the exception of full-face CMMs, by 2018 (MSHA, 2015)."

Jan 1, 2018

By E. H. Kurt

INTRODUCTION The simplest way to drill a hole into rock is to strike a steel chisel or drill bit with a hammer. Early miners used this elementary hand technique so successfully in "single jacking" and "double jacking" that the first mechanical rock-drill designers sought to duplicate it. However, in the early developments, the designers were forced to retreat to a construction known as the "piston drill," wherein the entire drilling element is tied to the piston and reciprocates with it. It took nearly 50 years to devise a method of divorcing the two elements and to achieve the original hammer principle used in hand drilling. The Mont Cenis tunnel, drilled through the French Alps in 1861, usually is considered the birthplace of the mechanical rock drill. The Hoosac tunnel in Massa¬chusetts was drilled at about the same time, and the success of these two ventures paved the way for innova¬tions that produced the Burleigh, Ingersoll, Sergeant, and Waugh piston drills between 1870 and the turn of the century. In 1897, George Leyner of Colorado introduced what has been considered the most significant development in rock-drill history. He devised the hollow drill steel for water flushing; when combined with his free-piston hammer drill, this became the first lightweight and dust¬free underground machine. In addition, Leyner's drills introduced improvements such as automatic rifle-bar rotation of the drill steel and chuck, automatic lubrica¬tion, and an enclosed throttle control. During the 1920s and 1930s, automatic feeds, centralizers, sliding cones, and the automatic water back head were developed, laying the groundwork for all pneumatic underground drills currently in use. Since these pioneering efforts, rock-drill development has been concerned primarily with refining the designs and improving the metallurgy to make faster, lighter, and more dependable machines. Fig. 1 illustrates the progress in drilling speed during the first 125 years of rock-drill development; that progress is a credit to the persistence and inventiveness of the designers in the rock-drilling industry. ROCK-DRILL CLASSIFICATIONS To meet the variety of conditions encountered in rock drilling, several distinct types of drills have been de¬veloped. In general, rock drills may be classified as either hand-held or mounted, with the hand-held ma¬chines including the jackhammer or sinker, the jackdrill or jackleg, and the stoper. The mounted drills are com¬monly known as "drifters." Table 1 shows that each type of drill is available in several sizes from different manufacturers. Fig. 2 illustrates a typical rock drill, showing the principal components. The jackhammer or sinker, shown in Fig. 3, is used primarily for general mine utility work such as drilling anchor holes (short vertical holes to bolt or anchor machinery), pin holes (short, usually horizontal holes to fasten sheaves, etc. to side walls), popholes (for blasting large boulders), and similar applications. They also are used for shaft sinking. Jackhammers are classified ac¬cording to weight, and they range from 7 to 30 kg (15 to 65 lb). The rock drill originally known as a jackleg was made by clamping a pneumatic cylinder or leg to a jack¬hammer, both to support the weight of the machine and to feed the tool forward in horizontal or uphole work. The more modern jackdrill refined this concept to make the hinged pivot for the leg integral with the drill cylinder and to group all drill and leg controls in the drill back head for convenience. Fig. 4 illustrates a typical jackdrill. Jackdrills are classified according to cylinder bore size, ranging from 60 to 83 mm (2.375 to 3.25 in.). Because of their light weight and versatility, jack drills are very effective in small drifts, small tunnel head¬ings, and stoping. The larger machines are applied to hardrock formations and in applications where drilling speed is a primary consideration. In soft formations or

Jan 1, 1982

By R. G. Sinclair, E. Sangine, S. M. Fortier, J. Brainard, K. Stone

"The U.S. Geological Survey and Natural Resources Canada conducted a study on the net import reliance of each North American country, and the impact of North American trade on the net import reliance of 12 nonfuel mineral commodities that are associated with advanced technology products: cadmium, cobalt, gallium, germanium, graphite, indium, lithium, nickel, rare earth elements, selenium, silver and tellurium. The combined results for North America, using 2014 data, showed greatly reduced net import reliance for nearly all of the commodities evaluated, which is largely the result of pooling the resources of production and recovery in Canada and Mexico of materials that are consumed in the United States. This study highlights the mitigation of potential supply risk for critical materials that results from trade within the North American trade bloc. IntroductionMultiple metrics and definitions exist for what constitutes a critical material, but there is broad acknowledgment that a mineral commodity may be considered critical if, among other factors, its production is geographically concentrated, if it has few or no substitutes, or if the country of origin is politically unstable. Numerous governmental and independent researchers have proposed methods of investigating criticality, with differing priorities such as economic resilience or strategic military supplies (European Commission, 2014; Graedel et al., 2015; U.S. National Science and Technology Council Subcommittee on Critical and Strategic Mineral Supply Chains, 2016). While criticality really depends on who is asking the question, and despite the differing priorities, there are several commodities that are commonly found to be of concern. In particular, some critical or potentially critical materials are used increasingly in advanced technologies, or they have complicated supply chains because they are coproduced or are produced in controlled markets.Commodities for which imports are required to satisfy domestic demand are those for which the importing country is net import reliant. Net import reliance (NIR) in this study is calculated as the amount of imported material, including changes in stockpiles, minus exports and is expressed as a percentage of domestic consumption:"

Jan 7, 2018

By C. V. Deutsch, T. Acorn

Understanding and managing risk is of increasing concern for the mining industry. Although methods exist to model geologic uncertainty based on stochastic modeling techniques and multiple realizations, there are few approaches to manage this geologic uncertainty in pit optimization. Block values can be penalized if the block uncertainty is high, but the goal here is to consider the reserve risk within the pit. This paper presents an approach for pit optimization that considers all realizations simultaneously with a heuristic pit optimizer. The heuristic algorithm maximizes value and also penalizes reserve risk. The inclusion of multiple realizations provides access to the risk or uncertainty in the total pit value. Considering this information permits an active risk management approach that can manage the uncertainty in the reserves within the entire pit.

Jan 1, 2018

By W. N. Hamilton

British Columbia is geologically favourable for a rich variety of industrial mineral occurrences. Some have been produced for years, others overlooked until recently. Major production occurs for asbestos, gypsum, limestone, magnesite, silica and sulfur; lesser production for a dozen others. For several of the minerals, potential is much greater than existing production. New production opportunities exist also for diamonds, niobium and REE minerals, fluorspar, kyanite, nepheline syenite, talc, and several others. Alberta, though geologically less diverse, also has many industrial minerals. Limestone, salt and sulfur have the major production; clay and shale, silica, sodium sulfate and a few others lesser production. Opportunities exist for expanded production, and for new production in heavy (Ti -Zr) minerals, formation brines (Ca-Mg-I-Li), and gypsum.

Jan 1, 1987

By Wilfred Walker

Much is known of the geography of the Alpine orogeny because it has now ended and all geosynclines are in their terminal, cordilleran form. The principle of sea floor spreading, continental drift, and mantle cells has gained general acceptance, but the number and position of the cells, even during the Alpine orogeny, is controversial. The oceanographers have demonstrated the uprises and in this paper it is suggested that downflows are marked by island arcs in the oceans and geosynclines (now cordillera) in the continents, for a total of about a dozen cells. Major mineral deposits associated-with the Alpine downflows are porphyry copper, molybdenum, nickel, chrome, lead-zinc-silver, gold, mercury, tungsten, and tin. Amore precise environment is known for some of these metals, for example, nickel, chrome, and mercury in flysch (which flanks mantle downturns), Ten major orogenies have taken place from 3500 m.y. to the present, Their re¬construction and metallogenesis is the subject of a continuing study.

Jan 1, 1971

By M. T. Ityokumbul

Flotation columns and their variations are increasingly replacing conventional cells in mineral processing circuitry. While the operational characteristics of columns differ from those of conventional cells, the same scale-up methodologies are being employed in design. This practice may be attributed to poor understanding of the factors controlling throughput. The use of tall flotation columns is frequently justified on the requirement for increased particle residence time. It is shown that longer particle residence times in the column cell alone do not translate into increased recoveries. Throughput data from several industrial flotation column installations is presented. An attempt at using dimensional analysis to provide scale-up methodology for the factors controlling column throughput is made.

Jan 1, 1995

By Timothy D. Gardner, Christopher Mark

Coal mines in the Illinois Basin have not engaged in pillar recovery for many decades. In large part, this is due to the exceptionally weak nature of much of the roof in the region. But, as room-and-pillar mining is conducted at greater depths, and larger pillars become necessary, recovering them becomes more attractive. Recently a western Kentucky coal mine became the first in recent times to successfully employ full pillar recovery. This paper describes the many challenges that were overcome during the process. From the beginning, the focus was on protecting the miners from roof instability, using cable bolts, mesh, mobile roof supports (MRS), and engineered final stumps. Two short test panels were extracted first, and the results were used to adjust the support pattern and mining sequence. Further adjustments were made based on subsequent experience. To date, seven panels have been recovered without a ground fall injury.

Jul 1, 2023