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By Y. Guan

The dissolution behavior of silver in ammoniacal solutions with cupric ammine as an oxidant has been investigated using a rotating disc electrode. The rates of dissolution of silver were determined by an electrochemical means as well as a direct measurement of silver ions reported in the bulk solution as a function of time. The variables investigated included stirring speed, temperature, concentration of lixiviants, and pH of the solutions. The rate of dissolution under the conditions studied' was found to be controlled by an electrochemical reaction at the liquid/ solid interface with an apparent activation energy of 48.07 kJ /mole. The rate was found to be a half order with respect to the, concentration of cupric tetra-ammine, Cu(NH3)l+.; The results were explained in terms of a mixed' potential theory.

Jan 1, 1994

By George E. Aiken

Agglomeration developments in the iron ore industry of North America are closely related to shifting patterns in commercially acceptable ore grades and even the definition of iron ores. These relationships have occurred mainly during the last 20 years. Many of these changes are an outgrowth of events which involved the history of the Mesabi Range. Although magnetic taconites had been discovered in the Lake Superior area about 1870, they remained unworked in part for lack of concentration methods and a generally unfavorable economic climate. Some 20 years later the rich Mesabi hematites were found beginning the era of direct shipping ores which continued through World War II. These Lake Superior iron ores included reserves of an estimated three billion tons. Following World War II, decreasing ore grades and rising costs began to force the closing of many underground iron mines. The early 501 s saw the beginning of the decline in direct shipping ores and a spurt in production of natural iron concentrate s. However, the market for unprocessed concentrates began to decline in the early 601 s as agglomerated products and foreign ores began to dominate the U. S. market.

Jan 1, 1972

By S. Tan

A computer-oriented systems simulator (CMHS) has been developed for analysis of continuous materials handling systems. Special emphasis has been placed in the model on several features which are unique to these systems. These features include periodic pattern of material arrival from several sources, several types of material to be transferred, material dispatch processes, intermediate storage capacities, and multiple material destinations. Both the deterministic factors of the continuous material handling system such as the physical decomposition of the system and the scheme and schedule of its operation and the stochastic factors such as variations of material arrival, material pattern on the conveyor, and avail-abilities of the system elements are considered in the simulator.

Jan 1, 1988

By W. A. Zingg

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

Jan 1, 1970

By Alexander Filimonov, Yury Bloshteyn

Ventilation of gas mines keeps necessary sanitation and hygienic conditions for labor in mines and increases the safety by dilution and removal of hazardous and dangerous gases in accordance with the safety rules. Several different concepts exist at the present time to design mine ventilation control systems. But technical ideas have been developed inadequately and technological solutions have not been investigated experimentally enough to build a serviceable system. This paper presents a new concept of high- efficiency mine ventilation process control system (MVPCS). The methods of modern system engineering (Kalman, 1969) are used to establish its functional and algorithmic structure. A three level hierarchical principle of system building is considered.

Jan 1, 1991

By Rubén Pavón] [H.

Mexico, that for various years held the second place among the elemental sulphur producers in the world, now occupies the fourth position. Nevertheless, taking advantage of the recent increase in the international prices of the metalloid, it is expected that Mexico recovers its traditional position producing, for the first time, over two million tons of sulphur during 1974. Drawing from material stockpiled during the last years sales are expected to reach 2.5 million tons, at excellent prices in the foreign markets, but not so in the domestic ones where prices have remained practically static since 1955, in spite of substantial escalation of production costs. Of the two sources of elemental sulphur in Mexico, the frasch process extraction from the salt domes of the Tehuantepec isthmus where the most important reserves are located - is the one that shall have an important increment. An increase of production of lesser magnitude is expected from sour gas, since sulphur recovery plants wilI go on stream toward the end of the year in the new oil fields recently located in the State of Chiapas. Two Mexican corporations are expanding and improving rational Frasch extraction operations. Together with Petroleos Mexicanos' sulphur recovery from sour gas it is estimated that production during 1975 shall reach 2.5 million tons and, consequently, supply the domestic market and generate an important sum of foreign currencies.

Jan 1, 1974

By Sii Smith-Gruner

Blasthole drilling by todays standards is not a mature operation. In most mining appli¬cations, the blasthole drill rig is the least understood piece of machinery. Draglines, mining shovels, and haulage trucks may have more charisma, but the entire mining process starts with the drilling of blastholes to facilitate removal of the overburden and/or the primary material being mined. There are two (2) principal drilling methods them being rotary and percussion. In certain situations, percussion drilling is the most practical method, but for most applications, rotary drilling using the rotary tricone bit is the common and accepted drilling technique. While the drilling rig is on the surface and quite visible to everyone, it is really the object at the end of the drill pipe, the tricone bit, that is doing the work and drilling the hole. The rig supplies power to the bit and air to clean the hole. In addition, it must be capable of providing certain other functions and should be properly outfitted to adequately support the rotary tricone bit.

Jan 1, 1988

By J. Moreno, P. Sinton, R. Vogwill

Groundwater models are often used to estimate and optimize dewatering volumes, locations, and rates, as well as water supply production for mines. Projections of future dewatering rates are highly dependent on the conceptual model used as a basis for the numerical model. This paper presents an audit of modeled dewatering rates versus actual data and an examination of the reasons for discrepancies. The setting is a gold mine, in a collapsed volcanic crater breached by the ocean. Mining will occur to about 200m below sea level within a remnant geothermal system. A detailed hydrogeologic investigation was conducted to support dewatering and geothermal depressurization design for future mining operations. These studies included development of a three-dimensional model to simulate heat and density-coupled groundwater flow, using software developed by URS/Dames & Moore. In this paper, the groundwater modeling results prepared 5 years previously by others was audited using operational dewatering data. This model was then extended using the new mine schedule and actual locations for dewatering wells to predict future dewatering requirements. In addition, a comparison between “hot” and “cold” model results was used to assess the need to use a heat-coupled versus a standard groundwater model for dewatering predictions.

Jan 1, 2003

By S. A. Moffatt

For several years iron ore processing plants, located in the northern U.S. experienced seasonal decreases in the grinding efficiency of their primary autogenous mills. Kawatra and Eisele (1992) studied this phenomenon in an operating plant and characterized it in terms of specific energy consumption (Fig. 1) and production of critical size material (Fig. 2). Critical size material is defined as ore that is too small to be effective grinding media and too large to be ground. This data showed that both specific energy consumption and critical size production increased during the winter months. The increased energy consumption was in part a result of an increase in the viscosity of the mill pulp at colder pulp temperatures. However, viscosity could not fully explain the changes in critical size production. These changes are most likely due to changes in the breakage characteristics of the ore. Other studies were also conducted to determine if thermal and physical properties of iron ore changed at colder temperatures. These are summarized below:

Jan 1, 1993

By Haydn H. Murray

Kaolins and bentonites of economic importance in Australia and New Zealand are described. Clays that are used for structural clay products are not discussed. Residual, hydrothermal, and sedimentary kaolins are utilized including clays associated with coal measures. Bentonites are sedimentary and residual. Very little kaolin and no bentonite is exported presently, but this will change in the near future as transportation costs continue to escalate. Many areas of Australia, in particular, where kaolins are known to occur have not been investigated to determine the quality and quantity of the deposit.

Jan 1, 1982

By M. F. Martin

Dewatering aids are chemicals which enhance the efficiency of mechanical dewatering equipment such as vacuum disc filters and centrifugal dryers. A new dewatering aid has been developed which significantly lowers the moisture content of the mineral concentrate and causes none of the undesirable side effects normally associated with dewatering aids. Highlights of product development from laboratory screening through field testing will be discussed.

Jan 1, 1985

By Ihsan Berk Tulu, Ted Klemetti, Deniz Tuncay

Accurately estimating load distributions and ground responses around underground openings plays a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the mining-induced loads, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses, both empirical and numerical. In this study, the numerical modeling approach recently developed at West Virginia University, which is based on the modeling approach developed by the National Institute for Occupational Safety and Health (NIOSH), is investigated using the finite difference software FLAC3D. The model includes the longwall panels, the adjacent chain pillar systems, and the different stratigraphic layers of the overburden. Using the 3D model, changes in loading conditions and deformations on the areas of interest, induced by an approaching longwall face, can be examined. This paper details the 3D modeling of a longwall panel utilizing this approach, and the verification of the results against field observations. The studied panel was 360 m wide with a 3-entry chain pillar system and about a 160-m average overburden depth around the studied area. The overburden strata consist of alternating layers of shale, sandstone, and limestone. The FLAC3D results were compared against field measurements from the mine site. The stress change values measured in the chain pillars were comparable with the modeling results. The model also replicated the surface subsidence profile obtained from field measurements fairly well. Overall, the 3D modeling approach was found to be successful for the case study longwall panel.

Sep 23, 2020

By Robert J. Hite, James P. Searls, Sherilyn C. Williams-Stroud

Potash is a generic term that includes potassium chloride, potassium magnesium sulfate, potassium sulfate, potassium nitrate, and sodium-potassium nitrate mixtures. In the ceramics industry, potash is also used to refer to potassium oxide. Potash, primarily in the form of potassium carbonate, was the first industrial mineral produced in the United States, and the first US patent issued was for an apparatus and process developed in 1790 for its production (Paynter, 1990). Prior to the 1860s, potash was primarily sold as an impure form of potassium carbonate produced by burning hard- wood trees and leaching the potassium salts from the ashes. The major early uses of potash include soap and glass making, dyeing fabrics, baking, and saltpeter for gunpowder. In 1859, the development of a purification process to remove the sodium and magnesium chlorides was developed for the carnallite found at Stassfurt, Germany, and mined potash became available. With the appearance of mined potash and the earlier (1840) discovery in Germany by Justus von Liebig that potash was a nutrient for crops, potash started to be used for high valued crops such as cotton and vegetables. The German potash companies quickly developed a manufacturing process for producing potassium sulfate for tobacco fertilization. German potash supplied nearly all American needs until the embargo of the First World War when imports from Germany were interrupted (Bateman, 1918). With the discovery of potash deposits in New Mexico in 1931, the United States became self-sufficient in potash. In 1962, the United States began importing potash from Canada, and two years later domestic apparent consumption began to exceed domestic production. Along with nitrogen and phosphorus, potassium is one of the three essential plant nutrients, the "K" of NPK terminology. As a result, 95% of potash production is used as plant fertilizer. In all plants, inadequate potassium diminishes growth, causes increased disease, stalk and stem breakage, and susceptibility to other stress conditions. Plants take up large quantities of potassium from the soil, and potash fertilization replaces this loss so that each new crop can be grown with the same vigor and productivity as the previous year's crop. The potassium depletion of the soil from growing repeated cotton and tobacco crops is well known in the history of southern agriculture in America. George Washington was known to have studied alternative crops that could be grown on soil that had been depleted by repeated tobacco crops. Most of the remaining 5% of potash consumption is by the chemical industry, as potassium hydroxide to produce soaps and detergents, glass and ceramic products, dyes, explosives, alkaline batteries, and medicines. Potash as chemical is used in oil field drilling mud, the aluminum recycling industry, and the electroplating industry. Additional minor uses for potassium chloride include water softener regeneration, sidewalk deicing, and salt substitution for human consumption. Potash is used in the food industry as potassium phosphate, and in production of glass products as potassium carbonate or nitrate. GEOLOGY Potassium is the seventh most abundant element in the earth's crust and the sixth most abundant element in seawater. It is found in silicate minerals of igneous, metamorphic, and sedimentary rocks and is also a major constituent of many surface and subsurface brines. The majority of world potash resources are found in subsurface bedded salt deposits which yield high grade, large tonnage ore bodies and are amenable to low cost mining and beneficiation. Because of the relatively high solubility of potassium minerals, potash from salt deposits is ideal for use as fertilizers. Some potash production is from evaporation of naturally occurring brines, but the vast majority of current domestic and international production is from bedded salt deposits. Sylvite, carnallite, kainite, and langbeinite are some of the more important potassium minerals (Table 1). Sylvinite, a mixture of KC1 and NaCl is the highest grade potash ore. Carnallite can be considered a potash ore when removal of magnesium chloride is included in the beneficiation, but it can also be considered a contaminant when mining for sylvite. Potassium sulfate and potassium nitrate are typically manufactured products. Potassium sulfate is produced from mined minerals through conversion processes in Italy, Germany, and Carlsbad, NM, and from brines in southern California and at the Great Salt Lake in Utah. Natural deposits of potassium nitrate occur only in small amounts in Chile. The majority of potash-bearing bedded salt deposits are believed to have originated from the evaporation of seawater or mixtures of seawater and other brines in restricted marine basins (Schmalz, 1969). The reflux depositional model for evaporite deposition was first described in the literature in 1888 by Ochsenius. A shallow bar, or sill, across the mouth of a basin lets in a restricted flow of seawater which evaporates into a salt-precipitating brine (Fig. 1). The density of the brine at the distal end increases with increased salinity, sinks to the bottom, and sets up a reflux current of higher density brine back toward the ocean. The sill, which restricts the inflow of seawater, allows inhibited flow of evaporation-concentrated brines back to the ocean. The least soluble salts are precipitated nearer the sill, and the most soluble components come out of solution in the deeper parts of the basin. The result is a lateral facies change in a tabular-shaped deposit that is due to the salinity gradients in the brine (Fig. 2A). The asymmetrical facies distribution of the Paradox Formation (Middle Pennsylvanian) Utah (Hite, 1970), the Prairie Formation (Middle Devonian) in Saskatchewan (Holter, 1972), and the Salado Formation (Upper Permian) in New Mexico (Lowenstein, 1988), might prompt explanation by such a model. Other deposits, such as the Salina Formation (Upper Silurian) in Michigan (Matthews and Egleson, 1974), show a facies distribution that could be described as a bull's eye pattern. Although some small subbasins of high grade sylvite are found near the margins, the potash is generally located in a central part of the basin surrounded by successively less soluble facies (Fig. 2B). The sparse

Jan 1, 1994

By David A. Zegeer

It's a pleasure to be here, and an honor to be invited to address this distinguished group of professionals. Today, I'd like to begin with an overview of progress in coal mine safety and health. I'll discuss some current areas of concern. And I'll make some suggestions as to where we may be headed in the future. This year marks the coal industry's 15th anniversary under the Coal Mine Safety and Health Act, which took effect in 1970. We have come a long way in those 15 years. As a coal mining man from way back, I remember the era when the Coal Mine Safety and Health Act first was passed. Some of you may remember it, too. At that time, the safety and health of coal miners was in the public eye even more than it is at present. One reason was a mine explosion that killed 78 miners when it occurred in a large underground coal mine in November 1968. That disaster raised tremendous public concern about protecting the safety of miners.

Jan 1, 1985

By Kyle L. Brennan, Scott Maybrier, Gang Chen, Scott Huang

Data from about 3200 drill holes in the offshore area at Nome, Alaska was digitized and processed. Most drill hole files have associated lithology, gold value, and blow count descriptions for each drill hole. The gold intensity was used to present the potential gold resource in the study area on the world wide web. A web page was created that gives background information on the project, descriptions about the Nome area, maps of the claim blocks that include all the normalized slices of gold deposits, and links to other relevant sites on the web. The site is located at http://mineral.uafsme.alaska.edu/nomeproject/nomehome.htm.

Jan 1, 2002

By David S. Bolin, Bruce Kennedy, Leigh A. Readdy, Graham Mathieson

INTRODUCTION The estimation of ore reserves is a process that begins with the earliest exploration stages on a property and continues throughout any subsequent evaluation and exploitation of the deposit. During exploration and preliminary evaluation, the results of these reserve estimates constitute the basic data for prefeasibility studies and economic analysis. The decision to continue exploration and development or to abandon a prospect is often based upon these studies. During the active life of a mine, reserve computations are continuously revised to assist in development planning, cost and efficiency analyses, quality control, and improvement of extraction and processing methods. Accurate reserve estimates are also required when financing a project, purchasing or selling a property, and for accounting purposes such as depletion and tax calculation. It is important to remember that the reliability of ore reserve estimates varies progressively through time as more and more information becomes available. The lowest order of reliability of estimation of reserves exists at the time of discovery. The maximum level of certainty concerning the ore reserves within a deposit is reached when the deposit is completely mined out. Between these two extremes are variable levels of certainty as to the tonnage and grade of the resource. This is particularly true of that portion of the mineral resource that constitutes the "minable reserve," as this portion is dependent upon economic as well as geological and technological factors. In the following discussion, several of the factors affecting ore reserve computation and some of the commonly used methods of calculation are presented. The first part of the discussion is confined to classical methods of hand calculation utilizing level maps and sections. The second part of the discussion presents an overview of somewhat more sophisticated methods of geostatistics which have been developed within recent Years. Geostatistical methods frequently provide the best ore re- serve estimates for many deposits. However, a digital computer is required for such geostatistically derived estimates due to the number and complexity of the cornputations involved. For many properties the classical nongeostatistical methods are adequate, particularly in the early exploration stages. In fact, it is the author's contention that even at those properties where the geostatistical approach is employed for reserve estimation, the geological and engineering staffs should prepare an estimate by traditional means. This provides an internal audit for the reserves and at the same time requires a continuing close appraisal of geologic problems that influence the presently known geostatistically estimated reserves and production at the mine.

Jan 1, 1982

By H. Wen, X. Zhai

"The Jurassic coal fields which lay in west China are the major energy base and contain half of coal resources in China. Due to the gather and degeneration rules, the spontaneous combustion characteristic of Jurassic coal is distinguished with permo-carboniferous coal, which needs to be studied deeply. Programmed heating experiments of five Jurassic coal samples and three permo-carboniferous coal samples from different primal coal fields in West China were conducted to identify the characteristic parameters in the low temperature stage of oxidation and spontaneous combustion. The experiments were carried out under non-isothermal heating conditions up to 180? at the heating rate of 0.33?/min in an air atmosphere. The result showed that oxygen consumption rate, CO gas production rate and heating intensity of all coal samples increased with the rising of the temperature, which of the Jurassic coal was higher than that of Permian-carboniferous coal. The C2H4 gas of Jurassic coal generated earlier, more than that of Permian-carboniferous coal in the process of oxidation and spontaneous combustion. It indicated that the Jurassic coal was easier to be oxidized and spontaneous combustion and the index parameters of spontaneous combustion were different between the Jurassic coal and permo-carboniferous coal.INTRODUCTION Coal was the foundation of industry development, and occupied 70% of primary energy production and consumption structure in China. According to the data of the 3rd coalfield prediction, 39.6% of the total coal resources were located in northwest Jurassic coal field in China [1], where the quality of coal was excellent. The study of northwest Jurassic coal already dated from the 80s of the 20th century, about coal rock composition, coal metamorphism [2], coal-derived hydrocarbons, coal structure [3], etc. The results of these studies showed that the composition and properties of Jurassic coal was obviously different from Permian-carboniferous coal, as well as the characteristic of spontaneous combustion [4]. As a result, the spontaneous combustion characteristic of Jurassic coal particularly needed to be studied. Now more and more methods could be conducted to test the characteristics of coal spontaneous combustion, for example, thermal analysis technology [5-7], programmed heating experiment [8-10] and coal spontaneous combustion experiment [11,12]. In these methods, programmed heating experiment could be conducted to determine the oxygen consumption rate, CO gas production rate and heating intensity quickly."

Jan 1, 2015

By R. F. Al-Fariss

The phosphoric acid industry is expected to develop in Saudi Arabia in the near future. There are three main reasons for expecting this: the discovery of phosphate deposits in the Sirhan-Turayf region, the construction of phosphate fertilizer facilities of the TSP, DAP and NPK plants on the east coast of the country, and the availability of an ample amount of sulfur As a by-product from the petrochemical industries. This study is a part of the research work performed in the chemical engineering department At King Saud University to evaluate the Saudi phosphate rocks for the wet process phosphoric Acid production and to test different flotation methods for the carbonate rich phosphate rock In a laboratory scale flotation cell. Experimental results for the above tests, as well as Beneficiation by calcination, are presented.

Jan 1, 1993

By Donald M. Ulbrich

Any of you who served in the military remember the admoniton to "get the lead out," In the military environment, where cost wasn't always a factor, "get the lead out" was more often a call for activity of any sort than activity of a particularly productive nature. As a result, when the top sergeant yelled "get the lead out," lots of people started moving.. . usually to get out of his way. Now there's a new cry, ..one that comes not only from the military but from an entire nation threatened with dependence on foreign sources for its energy needs. That cry ...get the coal out, Like the earlier order, it's a call to activity. A signal that the coal reserves of the United States must be tapped so that Project Independence can succeed by 1985, But it's more than a mere call to activity; it's also a call to achieve productivity. ,a call to produce coal both efficiently and acceptably. And that leads us to the key questions of where the coal is going to come from to meet that 1985 goal, and how can it best be mined. Where will the coal come from? There's no doubt much of it must come from surface mining in the West. How can this coal be mined? There are several options available but there is an excellent case to be made for using mining shovels and haul trucks due to their versatility in stripping, loading and reclamation, We'll explore this approach in this talk today.

Jan 1, 1976

By R. E. Ray

As coal reserves at shallow depths continue to be exhausted, a number of US coal companies are developing seams previously considered too deep to mine economically. Because of increased cover load, mines operating in deeper seams face unique ground control problems. In addition, the volume of methane gas in coal beds increases with depth, and ventilation requirements are much more stringent for deep mines than for shallower mines. When the longwall mining method is wed at great depths, ventilation, ground control, and operational considerations all influence the design of longwall panels. This paper examines these influences, particularly ventilation and operational considerations, on the feasibility of two-, three-, and four-entry longwall development panels in Jim Walter Resources' four deep mines.

Jan 1, 1988