Search Documents

By S. K. Kawatra, M. T. Rusesky, T. C. Eisele

An on-line monitoring system for apparent slurry viscosity has been developed at Michigan Technological University. It utilizes a vibrating sphere viscometer in conjunction with a special slurry presentation system to reduce particle settling and turbulence effects. It has proven to give accurate, reproducible results in an on-line hydrocyclone installation. Its performance shows that it can be an effective instrument on an industrial scale, particularly in grinding circuits. Development of the sensor and the importance of rheology in grinding are also discussed.

Jan 1, 1992

By B. Govindarajan, T. C. Rao, M. Vanangamudi

The results obtained from hatch, flotation experiments on two coals were used to develop relationships between the recoveries of water and solids into the concentrate. When the recovery of non-ash material (RN) for any size fraction is plotted against a parameter X, defined as [x _ Amount of (W) recovered x Collector dosage (C)in the concentrate (cc)(kg/t)] a single "non-ash recovery curve" is obtained. Non-ash recovery curves thus obtained from different size fractions are used to get a unique "modified non-ash recovery curve" for a given coal, using the reduced efficiency curve concept. Similar observations have been noted in the case of recovery of ash material (RA) also. The amount of water recovered into the concentrate is plotted against a parameter "Water Recovery Factor (WRF)," defined as [WRF = T.F.(1+C)] where T is time (in sec) and F is frother dosage (in kg/t). Plotted in this form a characteristic water recovery curve, for a given coal is obtained that may be defined by the following equation: [W4=W_(1 pWRF-e] The above relationships have been verified against the experimental results obtained from three more coals and are found to give satisfactory predicted values.

Jan 1, 1992

By G. R. Doubek

Dual Tube Reverse Circulation (DTRC) drilling has been extensively used for collecting groundwater information for the dewatering program at Amax Gold Inc. Sleeper Mine. This paper presents a discuss ion of the types of data which can be collected from DTRC drilling, as well as the effect submergence has on the data. A simple low-cost method of injection testing has been developed using DTRC equipment, allowing quantitative data to be obtained from exploration or test holes. Potential yields can be determined for each drill location, allowing siting and design of production wells to be optimized.

Jan 1, 1992

By Cynthia S. A. Wallace, Joseph E. Crawford

The Culberson ore body is a bioepigenetic sulfur deposit located in the Delaware basin. Sulfur occurs in the Upper Permian Castile, Salado and Rustler Formations. Most of the ore body forms a subhorizontal layer within the Salado Formation. Abundant cave fill deposits of Rustler and younger lithologies occur within the Salado Formation and predate mineralization. The cave fill deposits provided porosity zones within the otherwise impermeable sulfate host rock and controlled sites of mineralization. A northeast trending fracture zone near the west edge of the ore body localized some deep mineralization and may have allowed migration of hydrocarbons from depth.

Jan 1, 1992

By N. P. Reddy

This paper describes an experimental setup for multiple-fan ventilation systems at the ventilation laboratory of the WVU Department of Mining Engineering. Housed in a 30 ft by 70 ft room, the experimental setup consists of three 18 in. variable-speed axial-flow fans, the 18 in. diameter fiberglass tubing and fittings for arranging networks, and the pitot tube measuring and data acquisition system. The fiberglass tubing and fans can be organized into the non-planner network of two fans or three-fans. It is mainly designed for studying the characteristic curves, operating points, and fan stall for the multiple-fan ventilation system.

Jan 1, 1992

By Walter J. Johnson, Robert L. Chufo

A unique non-contracting coal thickness measurement technique has been developed to measure both the dielectric constant and thickness of a coal seam as part of a sensor array supporting an autonomous coal mining machine. The sensor measures the reflection of an electromagnetic signal from the coal/shale interface. Underground measurements of coal 6- in thick with a dielectric constant of 4 have been confirmed. Measurements were also made of a 31-in thick coal pillar for application of the sensor to highwall mining. The electromagnetic measurement technique, the data reduction process and field test experience will be presented.

Jan 1, 1992

By M. Poulton

Backpropagation, learning vector quantization, counterpropagation, functional link, probabilistic, and. self -organizing map are among the most popular neural network classification paradigms. Each paradigm finds a unique set of weights that will map the input pixels into their respective output classes. The usefulness of each network depends on its overall accuracy, ease of use, speed and scaling. The fastest and most accurate networks in this study were the functional link and counterpropagation. These networks, however, do not scale well to large input vectors or large training sets. A better choice is the LVQ network which achieves high accuracy, is fast, requires a minimum number of input parameters and presents fewer scaling problems.

Jan 1, 1992

By J. Dorsey

In 1910, Colonel Boyce Thompson, who owned Inspiration (now Cyprus Miami) and various other mining interests, formed the Magma Copper Company and leased the Silver Queen claims around Superior, Arizona. At the same time, he purchased other claims around the Silver Queen claims from what was then called the Magma Mine. The mine continued to operate until 1982 when Newmont Mining Company, who owned Magma Copper Company, shut down the operations due to high costs and low copper prices. When Magma was spun off by Newmont as an independent company in 1987, new studies of Superior were started. It was clear from these studies that the mine had been shutdown and over 1400 employees laid off for two basic reasons: first, as a resu1t of a mine plan that was technically flawed and second, be-cause of very high production costs mainly due to the low productivity from a very high cost work force. During 1989 a plan was formulated to re-open Superior with the determination to over-come the problems that resulted in closure. A new mine plan was developed and a management style developed that promotes team work and high productivity.

Jan 1, 1992

By H. Lyn Bourne

This is the 10th annual tabulation of US mineral royalties published in MINING ENGINEERING. The first year, 1982, the author solicited information about royalties and the cost of reserves. That column contained only a few royalties - not enough to tabulate. Since then, the response has been sporadic but the entries have grown to more than 300. Some have been deleted. Some of the older information has been deleted to make room for new entries. All indications suggest that the readers enjoy and use the information. But more information is needed. Russian practice In 1989, this column gave a brief history of mineral leasing and royalty payments as the concept applies to mining in the United States. This year's narrative deals with information about the mineral ownership in Russia. That country is in political and economic turmoil, including administrative systems and methods. And many laws are likely to change. What follows describes the Russian system of mineral ownership as of early 1992, according to Kirill Kavun. He begins "All the subsurface space of the Russian Federation with minerals contained belongs exclusively to the state. This forms the Common State Mineral Fund. Land parcels may be state, municipal, public or private property. They may be let to be owned and used by individuals, juridical persons, national/territorial or administrative/ territorial formations." This seems to apply to surface rights, as known in the US.

Jan 1, 1992

By Wei Wu

A computer-aided method for optimization of bench blast design in surface mines is presented. The design procedures basically consist of two steps. Firstly, a series of normalized, full- scale bench crater tests must be carried out in the field to find the optimum burden that produces the largest amount of acceptable fragments and other parameters that defines the effective fracture zone. Next, the locations and initiation sequence of blast-holes will be determined in such a way that each hole, at its time of firing, will be responsible for same amount of burden rock and will be in a position favorable to effective fracture of burden rock. A computer software "B.B." which can assist the second step of the design is fully introduced and its application is illustrated by an example.

Jan 1, 1992

By E. M. Frizzell

Decisions affecting ground control design require detailed knowledge of roof rock geology. This is especially true when weak roof materials and anomalies create hazardous conditions and. if not properly supported, result in roof falls. The U.S. Bureau of Mines has developed a system to evaluate geological conditions by using a roof drill that will provide an estimate of the compressive strength of the roof rock in real time. Through the use of sensors and a microcomputer on the roof drill critical drilling parameters can be interpreted and analyzed almost instantaneously, making it possible to inform an operator of hazardous roof conditions such as voids and changes in strata during the drilling process. Geotechnical data can be downloaded to a portable semiconductor memory device, which is brought to the surface so that data can be directly accessed with a personal computer for further analysis. Results from field tests are presented.

Jan 1, 1992

By John Hanna

Recently. researchers at The University of Alabama have developed a two-step method for the treatment of phosphorus sludge that includes bulk removal of phosphorus by physical separation techniques followed by remediation of the residual P4 in the sludge using a novel wet air oxidation technique known as "HSAD", Tests made on samples of the electric furnace phosphorus sludge have demonstrated that essentially complete and fast removal of the P4 in the sludge can be achieved by the HSAD wet oxidation treatment, Further studies were made to determine the applicability of the two-step process on sludges of various origins. P4 contents different pre-treatment and storage conditions, The present work discusses the mechanisms and factors controlling the HSAD wet air oxidation remediation approach.

Jan 1, 1992

By G. M. L. Robinson

The Clean Water Act, as administered by the Environmental Protection Agency, has mandated industry, government and the public to comply with potentially conflicting and vague water quality statutes, regulations and guidelines. Universal regulatory strategies have been developed which have introduced and have created regulatory, compliance and institutional conflicts. Conflicts have been created because National water quality performance goals and design standards are vague, and, in many cases, cannot be scientifically justified. Because of regulatory technical requirements to define background and environmentally impacted water quality characteristics, the ability to achieve regulatory compliance is difficult. Difficult issues requiring resolutions includes but are not limited to site specific surface and ground water quality classification systems, water quality standards and guidelines, point and non point pollution sources etc. Because of these statutory and regulatory complexities, a confrontational regulatory system has been created as it relates to: - defining performance criteria in relation to design criteria; - resolving water quality statistical compliance conflicts; - defining laboratory precision requirements; - determining background groundwater characteristics; and - locating a representative point of compliance. Because of these complex regulatory issues, the ability to balance goals, needs and economics has not been achieved or in many cases has not been attempted, without legal intervention. A few examples illustrating where water and waste management compliance conflicts have been experienced.

Jan 1, 1992

By S. Chander

A mineral or metallurgical process uses various inputs, such as ores, energy and other raw materials, to make different products that fulfill societal needs. The processing of raw materials has changed in recent years due to the increased complexity of processing low-grade ores, intensifying competitiveness and greater constraints. For process improvement, various plant optimization and process modifications must be conducted under environmental, social, political and economic constraints. Processing research and education's success in meeting the process industry's future needs depends on an adequate balance between micro- and macro-engineering approaches. In its simplest form, macro-engineering is concerned with the "big picture," while micro-engineering requires looking at a subset of the process. So macro-engineering may be defined as an investigation of the larger or "whole" system to achieve the desired goals. And micro-engineering may be viewed as a quantitative investigation of a subset of the process, to determine cause-and-effect relationships within the subset. Two different approaches might be used in macro-engineering analysis. In one, the big picture may be viewed without a detailed knowledge of the subunits. With this approach, statistical tools are used to relate input and output parameters. Also, actual plant data or analog models might be used to obtain the desired information. The usefulness of such an approach increases with problem complexity. To attain the desired goals using the second, "model-based," approach, a detailed knowledge of the subunits is often useful and their interactions may be considered. In complex process analysis, the first of these approaches is more useful since less information is needed. However, it is also less exact and more likely to fail if there are significant changes in conditions and interactions. The second approach, on the other hand, is more exact, with greater predictive ability within the narrow subset being considered. Consequently, it is difficult and costly to conduct.

Jan 1, 1992

By George F. Klernrnick

The Pokorny sulfur deposit is located in the northwest comer of the Delaware basin in the Rustler Springs sulfur district of west Texas. To date, 57 sulfur test wells have been drilled by Addwest Minerals delineating a resource of greater than one million long tons (It) of native sulfur. The deposit, hosted by the Permian Ochoan Castile Formation evaporite sequence, is a sulfur-bearing bioepigenetic limestone replacement of banded bituminous anhydrite. Three distinct mineralized horizons are present that correlate with zones of halite dissolution in the Castile. Sulfur mineralization occurs as hydrocarbon-poor disseminated grains, and as crystalline linings of discontinuous planar voids and large vugs.

Jan 1, 1992

By V. G. Medina

The 15 000 t/d La Coipa mine initiated operation in July of 1991. The complex consists of a conventional, open-pit mining operation and a mill employing cyanide leaching with Merrill-Crowe gold and silver recovery. The process plant includes a primary crushing circuit, a 15,000 t (live) covered stockpile, a semi-autogenous mill/ball mill/crusher or SABC grinding circuit, a leach circuit, a belt filtration/washing circuit, a zinc precipitation circuit and a "dry" tailing disposal system. The process plant is described in detail with major design considerations used in the selection of the processes and equipment. The unique methodology employed in the disposal of the filtered tailings is also described.

Jan 1, 1992

By B. K. Mishra, R. K. Rajamani

A numerical method known as the discrete element method (DEM) is used to track the motion of individual balls in large-diameter ball mills. As a result, the en masse motion of the charge, force distribution, fall-height distribution, and energy distribution emerges from the simulation. Hence, it is possible to investigate the effect of mill diameter, liner profile and ball size distribution on the force regime created within the mill. Simulation results for 14-, 16- and 18-ft diameter mills are shown. The proportion of energy lost in high-intensity impacts and sliding ball motion is discussed. The DEM simulation technique opens the way for a closer examination of liner profiles on ball-charge motion.

Jan 1, 1992

By M. J. Zdunczyk

Located approximately 50 miles northeast of Knoxville, Tennessee, Short Mountain Silica mines the Clinch Formation, an orthoquarzite, for silica sand. In 1980, a Knoxville resident and area contractor visualized mining Short Mountain for silica sand. Because APG Industries, the main market for the glass sand product, was only 48 kilometers from the site, many silica sand companies became interested in the property. In 1986, J.D. Nicewonder began to develop the site, and in May of 1988, APG Industries received the first sand shipment.

Jan 1, 1992

By G. Raspa

This article describes a procedure for calculating the recoverable reserves of stratified orebodies characterised by a thin and irregular layers. An application on the phosphate deposits in the N'Zeto region of the Popular Republic of Angola is also described. The procedure consists in building a block model of the deposit through the conditioned multivarial geostatistical simulation of small areal units. The recoverable reserves are then calculated and defined by applying to the model a selection processes based on measured geological/economic parameters taken from the drillholes: thickness of overburden and mineralised layers, economic grain-size fraction, grade. The procedure also takes account both of the geometrical constraints of the mining method and dilution. For reasons of confidentiality, a multiplier has been applied to the values adopted for the sampling data.

Jan 1, 1992

By S. P. Fleming

An acid mine drainage sludge containing 0.26% nickel, 0.21 % cobalt and 4.5% manganese was leached in a one-liter reactor with sulfuric acid in the absence and presence of sodium sulfite. The effects of temperature (25°C and 52°C) and sodium sulfite concentration (up to 0.03 molar) on the leaching rate were particularly investigated. The leaching rates of nickel and cobalt with sulfuric acid have been determined to be controlled by diffusion through product layer. It has been found that effective leaching conditions to give more than 90% extraction of nickel, cobalt and manganese while keeping the iron extraction below 10% come with an elevated temperature and a low sodium sulfite concentration at pH 3; for example, 52°C and 0.01 molar sodium sulfite.

Jan 1, 1992