Search Documents

By C. L. Karr, D. E. Goldberg

This paper considers optimization of the design and operation of an air-injected hydrocyclone (AIHC) via a genetic algorithm (CAI. The AIHC is a mineral separating device, developed by the U.S. Bureau of Mines, that combines the selectivity of flotation with the capacity and simplicity of hydrocyclones. GA's are search procedures based on the mechanics of natural genetics. Computer results demonstrate the ability of a GA to rapidly locate design and operating parameters that improve AIHC performance. A computer model of the GA-designed AIHC predicts improved recovery over that currently being obtained with an AIHC in operation at the U.S. Bureau of Mines Tuscaloosa Research Center.

Jan 1, 1990

By J. B. Nanor, J. Lorengo, M. Misra, C. B. Bucknam

The dissolution of mercury during the gold cyanidation process is the cause of many environmental, health and processing problems. The removal of mercury-cyanide complexes from synthetic solutions and process water were investigated using sodium and potassium dimethyl dithiocarhamates and sodium sulfide as precipitating reagents. The results have shown that efficient mercury removal can he achieved by the formation of stable mercury compounds with the addition of potassium dimethyl dithioearhamate. The mercury dimethyl dithioearhamate precipitates are stable under plant operating conditions, and they do not have any deleterious effect on gold adsorption by activated carbon. Furthermore, it is possible to stabilize mercury in the heap during cyanidation by adding dimethyl dithioearhomate.

Jan 1, 1999

By O Gutsche, Fuerstenau D. W., R. Ravikumar

Six minerals and one ore, namely, barite, dolomite, galena, limestone, quartz, quartzite and taconite, were ground in single-particle comminution mode in a rigidly mounted roll mill with different levels of energy input. Grindabilities were determined from the median size of the self-preserving product size distributions, which was taken as a measure of the fineness of the ground material in an empirical energy-reduction ratio relationship. These values reflect the inherent resistance of the solids to mechanical size reduction that are least distorted by particle-particle interference effects, grinding characteristics, energy efficiency of the milling system employed and the extent of the fineness specified.

Jan 1, 1992

By D. Hong, K. N. Han

The leaching behavior of rhenium in ammonium iodide solutions with iodine as oxidant was studied. Experiments were carried out in an autoclave to investigate the effects of stirring speed, temperature, solution pH, and iodine and iodide concentrations on the dissolution of rhenium. It was found that a high temperature and a high solution pH were essential for the efficient leaching of rhenium. The dissolution rate was found to be dependent upon the concentration of iodine and iodide. It was concluded that the dissolution of rhenium under the conditions studied was controlled by the mass transfer of iodine with an apparent activation energy of 15.8 kJ/mole.

Jan 1, 1999

The problems of toxic, noxious, and explo¬sive atmospheres caused by gases and dusts are certain special environmental considerations in underground mining. Some other problems unique to underground mining are design of stable structures in the strata and their support, lighting the workings, and control of noise in confined spaces. These affect the health and safety of the workmen and deserve critical analyses. Some of the most important environmental parameters of underground mining are summarized in Table 1. The list is not exhaustive but illustrates the scope of environmental planning in underground mining. This chapter will discuss the use of computers and computer models in mine atmospheric environmental planning.

Jan 1, 1979

By K. V. S. Sastry

Pelletization, sintering, and pressure compaction are the most common methods used to agglomerate ore concentrates. Over the last 20 years agglomeration has grown enormously in popularity and has become a standard unit operation in the nonferrous, cement, fertilizer, and ceramic industries. However, it is in the processing of iron ores and the preparation of blast furnace feed that agglomeration is used most and its application has grown fastest (Ball, et al., 1973; and Sastry, 1977). This chapter deals with an account of the current practices and future trends in the application of computers relative to an overview of the process design and engineering considerations of the unit operation of agglomeration.

Jan 1, 1979

The primary goal of a maintenance information system should be to aid the maintenance department in providing the required equipment or plant availability at the lowest possible cost. To achieve this goal, the system must provide information in support of the following objectives: (1) establishing the best fleet, equipment, and component configuration; (2) establishing the best maintenance program; (3) executing the defined maintenance program efficiently; and (4) monitoring equipment availability. These objectives can be satisfied with five groups of reports. Each of these groups should provide regular, periodic reports to aid in planning and monitoring trends, exception reports to identify problems, and on-request reports to provide analytical capabilities.

Jan 1, 1979

By Pradip

The selection, testing, and commercial utilization of flotation reagents is best carried out in stages through microflotation tests on pure minerals and their synthetic mixtures followed by bench-scale batch flotation tests on the ore. A systematic approach to quantitatively evaluate different reagents, in particular, through the analysis of batch flotation data, has been presented in this paper. It is recommended that the reagents are compared both in terms of their performance with respect to the recovery-time as well as the recovery-grade plots. While the former describes the kinetic aspects of reagent interaction, the latter is a measure of its selectivity for a particular separation problem.

Jan 1, 1987

By D. E. Ranta, Leigh A. Readdy

Defining classes of ore using geostatistical methods that match historical classifications has presented problems in the past. A simplistic and practical approach to this problem is presented. An example of the approach is presented using a porphyry-type system as a case study. The technique described uses area of drill-hole influence and known conditions from similar deposits, or the production history of the deposit being studied. It provides a practical bridging mechanism for defining the class of ore on a block-by-block basis using the error of estimation value developed during kriging. The approach provides a filtering method that refocuses attention on the adequacy of drill-hole spacing.

Jan 1, 1992

By Marian Radetzki

The economic developments and industrial behavior patterns that led to a lasting excess capacity in the world non-ferrous metals industries from the aid-1970s are explored. Detailed attention is devoted to analyzing and defining crucial concepts like "capacity", "excess capacity", "capacity maintenance" and "investments". Empirical evidence of capacity utilization and capacity growth in the industries under study is provided. The coincidence of excess capacity and low prices on the one hand, and investments in capacity maintenance and capacity expansion, on the other, is seen as a consequence of substantial declines in the metal industries' investment and production costs during the period studied.

Jan 1, 1989

By N. D. Cristescu

An analysis of the interaction between a creeping rock and a yieldable lining is presented. The following cases are considered: an elastic lining, a lining made of circular shaft rings that may slide at their joints, a lining made of circular reinforced concrete panels with wooden compressible strips inserted between the longitudinal joints and a yieldable support that has a compressible broken-rock stratum between the support and plane rock. By formulating a mathematical model for the rock-lining interaction, one can optimize the sequence of excavation-lining application. To keep costs to a minimum, one can also choose the most appropriate lining for the corresponding rheological properties of the rock.

Jan 1, 1997

By L. Darkwah

The use of explosives in coal mining inevitably results in oversize, midsize and undersize (fines) products due to fragmentation. The oversize can be broken into smaller sizes by further processing. However, the undersize have a negative affect on the efficiency of a mining operation. Therefore, limiting the amount of fines can be economically crucial. This paper concerns investigations aimed at reducing fines generation in coal mining. Inherent fractures were identified as one of sources of fines generation. This paper is centered on establishing a relationship between the fracture occurrence, the explosive properties and the blast outputs, which are evaluated in terms of the fines generated.

Jan 1, 1998

By J. W. Wilson, Y. P. Wang, M. H. Erten

The use of water is still the most effective and economical means for dust control in underground coal mines today along with dilution by the ventilation current. Studies have shown that the dust capturing capacity of water is a result of a balance of many intermolecular forces. Surfactants are known to reduce such forces by affecting both the surface tension of the liquid and its interfacial tension against a solid. Surfactants can be added to the water sprays to facilitate the dust capturing capacity. A laboratory scale model has been developed in which surfactants were added to the spraying water and preliminary data indicates positive results.

Jan 1, 1991

By C. A. Wheeler

This paper presents the initial findings of a research program to reduce the annual equivalent costs of belt conveying systems. The work utilizes models to predict the motion resistance of belt conveyors that take into consideration the influence of key conveyor variables, such as idler roll diameter, spacing, troughing configuration and belt width. Given a specified conveyor configuration, the capital and ongoing costs of the system can then be approximated based on the required belt, idler rolls, structure, drives, etc. The research provides a computational means to rapidly analyze a large number of potential conveyor configurations and to compare each on an annual equivalent cost basis.

Jan 1, 2008

By S. Eugene Sankey, Geoffrey L. Payne

Modern metallurgical processing often depends heavily on the use of flocculants to achieve the high levels of efficiency required. Selection of the optimum polymer can be complicated by the effects of process streams on the chemical and physical stability of the chosen polymer. Similarly, the presence of the polymer can have positive or negative side effects on process streams, such as phase disengagement in solvent extraction, foaming at filters and thickeners, crystal growth modification or flotation performance. Guidelines are given to highlight areas where problems may occur and suggestions made as to how these can be overcome. Practical advice on the preparation and application of polymers in process liquors is provided.

Jan 1, 1986

By Pierre Ollivier, Dominique Morin, Pr. Ivo Toromanoff

Refractory gold ores have been processed by bio-hydrometallurgical process at B.R.G.M. (Bureau de Recherches Géologiques et Minières), Research Centre ,Orleans,France. The liberation of gold has been studied and the following steps for gold recovery improved. The overall process flowsheet has been established comprising different ways of treatment before the final discharge of the effluent. Iron and arsenic are successfully precipitated under well controlled Eh-pH conditions. Long term stability tests have been conducted and the research programme is to be continued with the crystallo graphic studies of the precipitates. Economical studies have been performed on the base of data obtained on parameters studies.

Jan 1, 1990

MULSIM/NL and La Model are displacement-discontinuity programs which have been used quite successfully in the past to provide detailed structural models of various single and multiple-seam mining situations. However, both of these programs required fairly complex details of the mine plan and topography to be manually input into the program, often taking several days of work. Recently, automatic mine and topographic grid generation capabilities have been added to the MULSIM/NL and La Model programs, reducing the input time requirements from days to hours. This paper discusses the algorithms used for the automatic grid generation and demonstrates the utility of the new capabilities with a case study.

Jan 1, 2003

By R. H. Grau

The National Institute for Occupational Safety and Health (NIOSH) has conducted research to improve the ventilation of large-opening mines. The research has demonstrated that the ventilation of large-opening mines improves significantly by including ventilation requirements in the mine planning process and implementing some practical techniques during mining. Planning the location of long pillars to reduce the number of crosscuts between intake airways and return airways, positioning auxiliary fans in their proper locations, and establishing ventilation stoppings with minimal leakage all significantly improve the ventilation of large-opening mines. Mine operators that adopt these techniques in the mine ventilation plan will reduce mineworkers? exposure to airborne contaminants.

Jan 1, 2008

By D. A. Norrgran, J. N. Orlich

Described is the application of high- intensity magnetic separation throughout the spectrum of industrial minerals. Performed either wet or dry, the separation has application in both the recovery and concentration of value minerals and in removing deleterious mineral constituents. The various types of magnetic separators along with the design and operating parameters relative to separation response are characterized. The characteristics of specific minerals to magnetic collection and the production of high-grade concentrates are described. Laboratory, pilot-scale, and plant studies carried out on a variety of industrial minerals have demonstrated the effectiveness of magnetic separation as either a primary or a secondary unit operation to achieve product quality.

Jan 1, 1987

By W. M. Ma, W. L. Zhong, Syd S. Peng

In a longwall section that consisted of 7 longwall panels, there were two high pressure gas transmission pipelines across the panels burying from 3 to 10 ft. below the surface. One pipeline was 20 in. in diameter while the other was 24 in. in diameter. In order to investigate the stress conditions sustained by the pipelines during underground longwall mining, strain gages were mounted on the pipelines above panel #3, #4, and #5. Survey monuments were also installed along but near the pipelines. This paper presents a subsidence prediction method and the preliminary results of the pipelines' stress conditions as affected by underground longwall mining.

Jan 1, 1986