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By D. Gu

Breakage of rock by machine is one of the major methods of excavation. With the development of modern engineering techniques, the advantages of using this method have become even greater. Improving efficiency and reducing the cost of rock breakage is the main goal of mechanizing the rock-breaking operation. For a given stratum, the efficiency of a machine excavation depends, to a large extent, on the design and method of application of the tools used. In a planetary cutter head, the subcutter heads move like planets around the main drive shaft. The general structure of the cutter head is shown in Fig. 1. As shown in this illustration, the main drive shaft (1-1) is connected to the tie bar (1) and, thereby, to a gear(5) that meshes with a fixed-gear ring(2). The subcutter head (4) is rigidly connected to the gear (5) by the subcutter-head axis (2-2). When the main drive shaft (1-1) rotates, the subcutter head (4) rotates around the axis (2-2), under the action of the tie bar and with the help of sleeve pipe (3).At the same time, axis (2-2) also rotates around the main shaft (1-1). As shown in Fig 1, is the angle between the main shaft and the subcutter-head axis.

Jan 1, 1995

By Walter Hoecker

The dissolution of gold in cyanide_ leaching has been we11 published with the genera1 acceptance that gold is oxidised by oxygen and stabilized by complexation with cyanide [1]. The dissolution of gold is essentially an electrochemical process. The rate of the anodic gold dissolution is controlled by the cyanide concentration. - (2) While the cathode reduction of oxygen is controlled by dissolved oxygen concentration - (3) There are a number of factors influencing the concentration of oxygen, and if 1owered substanth.lly will effect the efficiency of the leaching plant. These include: "' salinity "' temperature "'partial pressure "'oxygen consumption rate The use of pure oxygen for· cyanidation is only beneficial if oxygen is rate limiting, Conversely a slurry saturated with air (typically 5 - 8 ppm) may not be enough for maximum leach rate. The diagram below shows the maximum dissolved oxygen levels obtainable with pure oxygen and air. DISSOLVED OXYGEN (MAXIMUM) IN WATER At steady state, the rate of the cathodic reaction must equal the rate of the anodic reaction. Thus the rate of gold dissolution is dependent on both the· cyanide and oxygen concentrations. - (4) Using an average of Do/Den =· 1.5 [2] (where Do and Den are the oxygen and cyanide diffusion coefficients) the table below illustrates the maximum effective oxygen concentrations for given cyanide levels in clean water [3].

Jan 1, 1992

By Charles D. Litton

This report describes a smoke particle detector which utilizes a novel three electrode configuration and 5.0 [] source of Americium 241. The detector operates on the principle of diffusional charging by a region of unipolar molecular ions. The detector is sensitive to particle concentrations in the range of 10 to 5 20 ug/m3. The detector is intended for use primarily as an early warning fire detector but has the potential for other applications of particulate monitoring. In particular, this report adresses the potential use of the detector for monitoring diesel particulate matter (DPM). To assess the viability of this application, particle size data obtained from in-mine sampling of both DPM and dust were used to derive detector sensitivity functions for DPM and dust as a function of their mass concentrations only. These sensitivity functions are dependent upon the average diameters and size distributions of the DPM and dust. Using the derived sensitivity function for DPM, experiments were conducted in a ventilated tunnel where the true DPM mass concentrations, measured using a Tapered Element Oscillating Microbalance (TEOM) were compared to the mass concentrations calculated using the detector sensitivity function. The agreement between the two measurements was good, indicating that with additional experiments, coupled with in-mine evaluation of the detector, refinement of the device for use as a continuous monitor for DPM appears feasible.

Jan 1, 1989

By S. N. Groudev

Acid mine drainage waters generated in the uranium deposit Curilo, Bulgaria, were treated by means of a pilot-scale passive system consisting of an alkalizing limestone drain, a permeable multibarrier for microbial dissimilatory sulphate reduction, biosorption and chemical neutralization, and a natural wetland, connected in a series. The waters had pH in the range of about 2.5 ? 4.1 and contained radionuclides (uranium, radium), heavy metals (copper, zinc, cadmium, lead, nickel, cobalt, iron, manganese), arsenic and sulphates in concentrations usually much higher than the relevant permissible levels for waters intended for use in the agriculture and/or industry. The water flow rate through the passive system varied in the range of about 5 ? 15 m3/24 h, reflecting water residence times of about 60 to 20 hours. An efficient removal of pollutants was achieved by this system during the different climatic seasons, even during the cold winter days at external air and water temperatures close to 0°C. The removal was connected with different mechanisms but the microbial sulphate reduction played the main role during the warmer months of the year. However, during the cold winter days the removal of pollutants was due mainly to their sorption by the solid dead plant biomass (cow manure, plant compost, straw) present in the multibarrier as well as to their precipitation as a result of chemical neutralization caused by crushed limestone.

Jan 1, 2006

By George Hufford

An investigation is made into the applicability of queueing theory to simulating the operation of a large open pit copper mine in the southwestern United States. Actual data from a working mine was used to construct curves for truck loading time, haulage and return time, and dumping times. Known results of investigations of queueing models (Koenigsberg - 1958, Gordon and Newell - 1967, Cabera and Maher - 1973) were used to simulate the actual operation. These did not give acceptable results so commonly used probability distributions were fitted to the actual data. A large computer program known as Q-GERT was used with the various parameters obtained from fitting the curves. Kolmogorov- Smirnov tests were run that showed that this was not satisfactory either. Finally, Q-GERT was used with the actual data from the mine. An appropriate correction factor is then found to apply to the exponential probability distributions tested previously and satisfactory results are obtained.

Jan 1, 1981

By T. E. Scartaccini

A drill recorder is a permanent data collecting instrument. In open pit blast hole drilling the application of a drill recorder is that of data collection, drilling control, and drilling education. The various drilling parameters (weight, RPM, penetration, torque, and air) have a drilling correlation which can be demonstrated and documented by a recorder graph. When the correlation is physically put to use during the process of drilling, then the recorder has become a drilling tool and is no longer just a data collecting instrument, per se. By being able to maintain accurate records and drilling control, comprehensive studies of changes both operational and technological can be made. These are based on in-progress facts and not after-the-fact logs. To determine total drilling efficiency, drilling conditions must be documented and controlled. Field operations at American Smelting and Refining Company's Mission Mine have proved that by increasing drilling control, demonstration of parameter relationships, and drill monitoring, more economic efficiency can be obtained. In comparing results obtained with recorder control and conventional control a decrease of 14 percent to 36 percent of drill footage costs were obtained. The percentage of variance is dependent upon whether drilling is milled-tooth or carbide-insert bit drilling.

Jan 1, 1970

By Hasan Sevim

This paper summarizes recent developments in modeling of underground coal slurry haulage networks for determination of optimum design and operating parameters. The model presented here is based on a stochastic dynamic programming formulation, applicable in any typical room-and-pillar and/or longwall mining configuration commonly practiced in the United States. The formulation and the structure of the model is general enough to handle design problems involving more than one face and mining method. Given the stochastic operating characteristics and a system layout, the model can be used to determine the equipment configuration and operating regimes that minimize the overall unit cost of coal haulage.

Jan 1, 1983

By Charles H. Rice

Coal liquefaction processes can be divided into two broad classifications - direct and indirect. Direct liquefaction processes, in general, slurry coal with a solvent and react it with hydrogen under elevated temperature and pressure. Indirect liquefaction is the term applied to processes in which coal is first gasified to generate a synthesis gas of carbon monoxide and hydrogen. The synthesis gas is then converted to various types of liquid fuels by the proper selection of catalyst and conditions. The first experiments on direct coal liquefaction were undertaken in 1933 by Bergius. Development and commercialization of the Bergius concept was accomplished mainly through the effort of I.G. Farben at the Ludwigshafen plant of its subsidiary, Badische Anilin und Soda Fabrik A.G, under the leadership of M. Pier (1). A demonstration plat having an annual capacity of 100,000 tons of coal was built in Leuna, Saxony in 1927. Six years later, Imperial Chemicals Industries, Ltd., commissioned a plant in Billingham, England (2).

Jan 1, 1981

By Theodore M. Gurr, James J. Bartels

Phosphate produced fertilizers provide the phosphorous nutrients required by plant life to sustain significant growth, thus improving the production of food for the world's population. Phosphorous replenishment of soil currently can be obtained efficiently by no other means than by direct application of phosphate fertilizer to the soil. Phosphate products are also utilized in animal feeds, detergent, and various industrial processes. Thirty-three countries are presently mining phosphate rock for the production of fertilizers, and its process byproducts. The major phosphate rock producers are the United States, the former Soviet Union, Morocco, and China [(Table 1)]. Phosphate rock is generally defined as a rock material that contains phosphate minerals which are sufficient for commercial usage. Phosphate minerals are found in sedimentary igneous and metamorphic rocks. Economic resources of phosphates are primarily developed from sedimentary rock sources. The apatite mineral family comprises the majority of phosphate constituents from both sedimentary and igneous rocks. Igneous phosphate rocks are generally composed of fluroapatite whereas sedimentary rocks are generally composed of carbonate fluroapatite, or chlorapatite. Phosphate rock is mined by a multitude of processes, including surface and underground mining. The mined rock requires mechanical and chemical processing to liberate the phosphate for utilization as fertilizer. Approximately 85% of the world's phosphate production uses sulfuric acid, with the remaining processes utilizing nitric and phosphoric acids. Ammonia is also introduced in the manufacture of liquid fertilizer, ammonium phosphate and ammonium polyphosphate. GEOLOGY Mineralogy and Chemical Properties Phosphate most commonly is derived from the mineral apatite, which is chemically described as CA5(F,Cl,OH)(PO4)3. Apatite is also broken up into the composite apatite minerals which are fluroapatite Ca5F(PO4)3, chlorapatite Ca5Cl (PO4)3 and hydroxyl-apatite Ca5(OH)(PO4)3. Carbonate CO3 can substitute for PO, forming carbonate apatite, called francolite. The guano phosphate (bird excrement) mineralogy commonly occurs as brushite CaHP04.2H20, monetite CaHPO4, whitlockite Ca3(PO4), and dahlite Ca10(PO4)6(OH)2. Apatite minerals form from igneous sources where they are developed deep in the earth's crust; and the cooling processes are slow, producing long, hexagonal prismatic to tabular crystals. The termination of the crystal can be basal plans or pyramids. In some instances, the crystals are bipyramids. Faster cooling, or sedimentary derived apatites are more commonly cryptocrystalline. Collophane is a name given to cryptocrystalline apatite found in phosphate rock in fossil form. Apatite minerals are relatively soft and are used to describe the 5 hardness on the Mohs scale. Cleavage is poor and develops along the C(0001). The color of apatite minerals varies from colorless, to violet, and blue, but are predominantly green or brown; luster is vitreous to subresinous. Collophane's physical appearance is often opaline, dense, with colloform structure and sometimes concretionary, nodular or pulverulent. Phosphate Bearing Materials Origins Phosphate deposits of igneous and metamorphic origins have been well defined. Sedimentary origins have been defined, but with a greater degree of uncertainty. Research in the 1980s proved out some of these processes through studies of real time deposition in Chile, Peru, and Australia. Igneous intrusive alkali rock and associated contact metamorphic rocks, provide approximately 20% of the world's phosphate. Fluorine containing apatite minerals are the most common materials containing phosphorous. Fluorapatite occurs in most igneous rocks. Fluorapatite and fluorine hydroxylapatite, together with carbonate varieties of these, are important members of the group. Where an essentially pure chlorapatite, carbonate apatite, and hydroxylapatite are rare and restricted in occurrence, the fluorine containing types occur in most all igneous rocks as early formed accessory mineral, usually in microscopic crystals, and may occur as extremely large bodies as magmatic segregations from alkalic igneous rocks. Apatite is also found crystallized in pegmatitic faces of both acidic and basic types of igneous rocks. More specifically, apatite is associated with magnetite deposits, in hydrothermal veins, especially those formed at relatively high temperatures, and in veins of the Alpine type. Apatite is common in both regionally and contact metamorphosed rocks, especially in the crystalline limestones where it is associated with sphene, zircon, pyroxine amphibole, spinel vesuvianite, phlogopite, talc, chloride schists, and as a contact metamorphic mineral.

Jan 1, 1994

By Gary P. Thomason

We have all heard a great deal about how various projects were financed or certain companies were successful in obtaining a bank loan. There are many more projects and companies who fail to get the money they need. At least a portion of these failures, and a large percentage of the frustrations connected with even the successful financings, are a result of not understanding the process of obtaining money. Recent years have seen a proliferation of sources available to finance minerals operations, but let me assure you that these represent only a minor portion of the minerals financing market. The fundamental source of borrowed money to almost all minerals related companies remains the banks. Therefore, understanding the "Loan Approval Process" can easily mean the difference between getting the money or not. In the following pages I hope to provide some insight into what I define as the loan approval process. Having pre-offered my definition, I intend to delineate the various stages of the process and the planning and information I believe should be contained in each. My ultimate goal is to help you think like a banker and, in so doing, stay on top of the process so that you can successfully obtain the funding necessary for your projects.

Jan 1, 1983

By Sandip K. Mukherjee

In underground mining operations, ventilation and water sprays are the common methods of controlling dust. In recent years there has been a proliferation of technical literature dealing with water sprays for dust control. However, guidelines for the design of an effective water spray system have not been presented to the mining industry. This paper reviews developments in water spray dust control technology and recommends guidelines for water spray systems to control dust in under- ground coal and non-coal mining operations. These guidelines suggest type, number, location and orientation of nozzles, desirable operating water pressure, and associated filtration system.

Jan 1, 1983

By P. A. Korpi

In March of 1978 the first set of Angular Spiral Liners utilized in grate discharge ball mills for wet grinding was put into service in the San Flanuel Concentrator of Flagma Copper Company. The use of these liners has decreased grinding media consumption by 19.2% and grinding energy consumption by 15.8%. In addition a 1.1% increase in grinding throughput is being realized through the use of the system. This paper describes the Angular Spiral Lining System and reviews the test program at the San Manuel Arizona Concentrator. Operating parameters are discussed in addition to the current testing program to futher optimize the system.

Jan 1, 1982

By R. M. Smailer

Detailed description of the development of the FIOR process1 and, subsequently, other technical papers relating to the operation and start up of the FIOR plant2,3 are available in the technical literature. The Fluidized Iron Ore Reduction (FIOR) process plant constructed in the Matanzas region of Venezuela represents the first commercial application of this technology. The FIOR process was developed by Exxon Company during the 1950's and 1960's; and the facility in Venezuela was designed and constructed by Davy McKee with the plant start up in 1976. While there is a minority government ownership in the company, FIOR de Venezuela operates as a private sector company with the majority of the ownership being private capital.

Jan 1, 1981

By G. G. O. O. Uwadiale

Starting from a crude ore assaying 45.6% Fe, a fine-grained oolitic iron ore was concentrated by the oil agglomeration technique to 90% Fe recovery and 65% Fe assay. The ore required grinding to minus 5 µm to effect adequate liberation, and the technique yielded optimum results at pH 9. The roles of pH, collector, and bridging liquid concentrations on selectivity and yield of iron minerals in the concentrates are discussed.

Jan 1, 1991

By Michael L. Nave

An existing coal mine's raw coal 60 inch conveyor system had become productivity bound by a capacity of 3,500 tph. The existing conveyor drives were fixed speed wound rotor induction motor drives installed in 1983. The fast track upgrade installed variable speed medium voltage variable frequency drives to speed up the conveyor to a capacity of 5, 000 tph. The installation took place over a one week system shutdown during Christmas 2000.

Jan 1, 2002

By G. Chi, M. C. Fuerstenau, R. C. Bradt, A. Ghosh

With increased emphasis on controlled blasting, which is the first and least-costly stage of comminution, ore grindability and plant throughput can be increased by 5% to 10%, and energy savings of up to 10% appear possible. Crushing and grinding efficiencies are presented for ore blasted under regular and adjusted field conditions. An economic analysis of drilling and blasting through crushing and grinding is presented, suggesting that cost savings approaching 10% may be achieved.

Jan 1, 1998

By K. N. Han, J. J. Kellar, Y. Guan

The adsorption of zinc species onto silica in ammoniacal solutions was studied. The adsorption isotherms indicated that the adsorption of zinc increased with increasing pH. The adsorption density increased as the zinc equilibrium concentration increased up to =3.5x10-4 M. Above this concentration, the adsorption density was independent of the equilibrium concentration, and a maxima adsorption density was reached. Temperature had no significant effect on the adsorption density.

Jan 1, 1995

By H. Schultheis

The European Commission has launched in April 2002 the Thematic Network NESMI with-in the FP5 under Growth. NESMI stands for ?Network on European Sustainable Mining and Processing Industries? and will run until 2005. Within NESMI there are different ways to set up indicators and evaluate them throughout the NESMI Members. First analyses concerning the Demand and Competence within NESMI are developed. New focus points for analyses can be implemented into NESMI.

Jan 1, 2003

By D. V. Ramani, M. M. Kissel, M. T. Ityokumbul

Experiments were carried out to determine the efficacy of bubble column flocculation. An acid-base neutralization method was used to determine the mixing time in a 0.064- by 1.5-m bubble column equipped with a Mottporous sparger. The mixing times decreased as the tracer injection point approached the gas sparger. Preliminary flocculation experiments on two clay samples were carried out. The effects of frother addition and airflow rate are presented and discussed.

Jan 1, 2000

By M. C. Fuerstenau

With increased emphasis on controlled blasting, which is the first and least-costly stage of comminution, ore grindability and plant throughput can be increased by 5% to 10%, and energy savings of up to 10% appear possible. Crushing and grinding efficiencies are presented for ore blasted under regular and adjusted field conditions. An economic analysis of drilling and blasting through crushing and grinding is presented, suggesting that cost savings approaching 10% may be achieved

Jan 1, 1997