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By Dickson T. J

Slag cleaning is an important part of the pyrometallurgical operations at the Kalgoorlie Nickel Smelter. It is a complex system with many streams of different phases and composition. Some of these streams are very difficult to control and/or monitor. Through the use of a statistical computer package, called Minitab, key relationships affecting the economical operation of the slag cleaning process have been found. Data for the statistical analysis was collected from all possible variables around the appendage.

Jan 1, 1991

By Peter J. Lean

The introduction oE computer control in the grinding circuit of the New Broken Hill Consolidated Limited concentrator in the early 1970's gave smoother operation at optimum performance. The ore feedrate and water additions to the grinding circuit were controlled to operate each of the ball mill/ rake classifier grinding units at the upper limit of the circulating load while classifier overflow density was maintained to give a product size and pulp density suitable for flotation. An incremental expansion of the concentrator in 1981-82 included the installation of hydrocyclones in closed circuit with three of the four ball mills. Without the rake classifiers in circuit the previous control strategy could not be used and the complex interaction of hydrocyclone performance characteristics when classifying coarse grained sulphide ore resulted in the over-grinding of the lead mineral galena. Testwork aimed at optimising grinding circuit performance recognised the enhanced tendency of higher specific gravity minerals to report to the cyclone underflow. The data has been evaluated on an individual mineral basis and then used to develop a model For grinding circuit control. The development of the model which uses inputs of ore feedrate, metal content of the Feed and slurry density of the cyclone overflow to predict the size of the minerals in the grinding circuit product is described and model predictions are compared with plant performance.

Jan 1, 1984

By Jennifer Pakula

Productivity improvements in underground mining are becoming harder to find. Most mines quickly identify deficiencies in their processes and then struggle to make productivity gains beyond that plateau. One way to increase productivity in this situation is to modify existing methods of operation. Vale?s Stobie Mine has been in operation since the late 1800?s employing a variety of mining methods. Many mining advances have been incorporated over time. With the advent of mechanized rubber tired equipment, sublevel cave mining was introduced to allow economic extraction of a large low grade area. Additional productivity gains were seen in the sublevel cave area with the introduction of preloading production drill holes. In preloading, the holes are loaded with bulk emulsion ahead of the production cycle and then primed for blasting as needed. The introduction of preloading, although giving the Stobie sublevel cave process an overall productivity gain, saw an increase in oversize due to the collar priming technique employed. Handling oversize material prohibited the operators from handling additional units of optimally sized material. Prepriming, adding detonators at the toe and midcolumn of the production holes during the preloading process, was identified as a change that could reduce the formation of oversize. This paper describes the introduction of prepriming to the sublevel cave mining method and focuses on the process Stobie employees followed to ensure a safe transition to this productivity improvement.

Nov 1, 2011

By Rubisov DH

This paper is related to the problems of the mathematical modelling of vibrating screening process and to predicting the screening operation results. The authors propose a model of screening based on the interpretation of granular material segregation on a screen surface as an instantaneous process. Results show an agreement with laboratory and pilot plant tests. Derived formulae can be used for screen sizing and screening result estimating.

Jan 1, 1993

By J. M. Manka

American mining companies operate many drum hoists, hoisting from varying depths with varying payloads. This paper reviews the procedure for selecting optimum wire rope constructions for existing hoisting installations. Selection for proposed installations, along with recommended hoisting parameters, is also discussed. To achieve optimum rope performance, preventive and corrective maintenance procedures are required and are reviewed here, along with examples of rope problems and their causes.

Jan 1, 1993

By Eugene Honeycutt, David Gallagher, R. E. Melley, Nick Madison

Drummond Co. Inc.'s Shoal Creek Mine slope conveyor is the highest lift, highest horsepower, highest tension conveyor system in North America. The system has a capacity of 4950 t/h (5500 tph), a vertical lift of 360 m (1180 ft) and a total connected power of 6000 kw (8000 hp). The mine will include 2 longwall machines and 5 to 7 development sections. Annual raw production will approach 9 million tly (10 million tpy). This paper describes the early investigation of system capacity, haulage system options, and the final selection of a single flight belt conveyor. It will review the basic system de- sign and equipment selected. Also included will be some highlights of the installation of the conveyor system.

Jan 1, 1996

By Amanda Azman, Richard Hi Danie/son

Ultimately, the most important product of a hearing conservation program is the prevention of hearing loss, not the amount of hearing protection that has been purchased or whether employees are attending their annual training sessions. Audiometric testing directly reveals whether hearing losses are actually occurring in a plant. With audiometric data, we can assess overall program effectiveness, alert workers of impending hearing loss, and reveal potential employer liabilities for compensable hearing loss. Without the ability to efficiently analyze audiometric data or produce effective reports, our programs become fruitless and unproductive. Consequently, ifaudiometric data are such vital end-products, then effective audiometric technologies serve as the prime architect and generator of these fundamental data. These technologies, consisting ofaudiometers, associated peripheral hardware, and database/reporting software, deserve our consideration.

ALL critical and strategic materials procurement functions have been transferred from the Defense Minerals Administration, General Service Administration, and the Economic Cooperation Administration and are now centered in a newly formed agency, the Defense Materials Procurement Agency. DWA will report directly to the Director of Defense Mobilization. Mr. Truman stated that he intended to appoint Jess Larson, administrator or General Services to head the new agency (see Trends P. 756). W. C. Schroeder has been named acting director of the Defense Minerals Administration replacing James Boyd. He has been named also to a newly created assistant director position of the Bureau of Mines serving under Mr. Boyd who is director. Schroeder was formerly head of' the Synthetic Liquid Fuels Division of the Bureau of Mines.

Jan 9, 1951

By J Szymanski, S Planeta

In pursuit of optimising the cemented rockfill system fragmentation of the aggregate, while travelling through the surface-to-underground aggregate transport raise, was investigated and a æfines estimationÆ equation was determined. When used with the rockfill strength estimation equation, the fines estimation equation enables an accurate estimation of the compressive strength to be derived theoretically. Optimum fill raise orientation was examined and recommendations are given depending on the varying stope dimensions. If the maximum dimension of the stope is less than 30.5 m (100 ft), a single, centrally located fill raise will suffice. However, as the stope dimensions increase, the number and orientation of the fill raises becomes more complicated and each stope must be examined on an individual basis.

Jan 1, 1998

By P. Coleman, J. C. Kerkering, S. Iverson

Fault tree analysis is a systematic safety analysis tool that proceeds deductively from the occurrence of an undesired event (accident) to the identification of the root causes of that event. One recurring mine safety problem-a dozer falling into a void over a drawpoint on a coal surge pile-was analyzed using available, inexpensive fault tree programs on a personal computer. The analysis identified basic and intermediate events that led to the burial of the dozer and graphically depicted the interrelationship between these various subordinate events as well as the various chain of events leading up to the primary event. A sensitivity analysis on these probabilities showed which events had the greatest influence on dozer burial in a coal surge pile.

Jan 1, 2001

By R. Reifsnyder, J. LaRosa Thompson

Slurry or slimes dispersion is a critical factor controlling the efficiency of sulfide mineral comminution and concentration operations. The PQ Corporation has conducted innovative sodium silicate-based studies to determine the effects of enhanced dispersion on whole ore grinding and flotation behaviors and on downstream separation and cleaning steps. The work has advanced the understanding of the role of pulp rheology on the optimization of commercial grinding, agitation leaching, and flotation operations. This paper reviews the role of sodium silicate as a selective wetting agent and surface charge modifier in sulfide mineral systems, and discusses the results of silicate experiments conducted on various ores of copper and molybdenum, gold, platinum-palladium, and copper zinc, all of which contain clay minerals or highly floatable gangue constituents.

Jan 1, 2002

By G A. Streltsova

In the paper the main concept of qualitative simulation is determined when computer-aided designing and forecasting of designs of robotised continuous-flow working face complexes for underground mining of hard ores. The parametric model æunderground ore mineÆ and its components û composite models are considered. Frame description of structure of working face complex and methods of organising of rule-oriented representation of knowledge when itÆs operating are given. The architecture of the developed prototype of expert system æworking face complexÆ and construction of a knowledge base for it are described when solving problems of multi-criteria optimisation of computational parameters of the working face complex under conditions of uncertainty. The guidelines for further development of knowledge base and expert system are given.

Jan 1, 2003

By Per-Martin Sandgren, Alrik Anttila

LKAB's ores have specific mineralogical properties that make them especially suitable for the production of supergrade concentrates. Conditions are particularly good for this purpose at Malmberget, where a concentrate for high-purity sponge iron production has been produced for many years. This product assays approximately 71.5% Fe and 0.20% SiO2. Potential exists for still further improvement. In recent years, the production of fractioned concentrates has been started. The material lies within the size range 74-125 µm and the approximate chemical analysis is 71.4% Fe and 0.30% SiO2. Other special products are under discussion. Malmberget ores are also suitable for the production of high- purity direct reduction pellets with a SiO2 content below 1%.

Jan 1, 1983

An intensely sheared and mineralisedIzone occurs in the Quartz Dolerite Greenstone (or Younger Greenstone) mass on, the western limb of the Kalgoorlie Syncline. This zone comprises the western part of the Golden Mile and has produced the greater part of the 33,000,000 ounces of gold produced to date from the main mining belts. A study of.th e general geological and structural features gives rise to the expectation that the lode shear system,will continue southward on a pitch similar to that of the maln syncline whose axial plane may be referred to as the "Boulder Dyke". Although payable ore has recently been found further south than previously, the expectation of large quantities extending southward from the present mining areas is Problematical.'

Jan 1, 1964

By William C. Peters

The experiences of exploration crews with mineral land acquisition could be graphed to show a correlation with the natural law that everything tends to become more so. A single step, such as that of taking a series of deep soil samples, is sometimes delayed until some sense can be made from floating unpatented claims which are obscure in orientation as well as position-placer claims, overlapping lode claims, location posts with empty Prince Albert cans and claims with no apparent assessment work for ten years. Add to this some patented claims without monuments, a state or federal withdrawal area which may or may not invalidate preexisting claims, a loosely defined tunnel site, and some ranchers who understandably resent the separation of surface rights from mineral rights.

Jan 1, 1970

By P. Coleman, J. C. Kerkering, S. Iverson

Fault tree analysis is a systematic safety analysis tool that proceeds deductively from the occurrence of an undesired event (accident) to the identification of the root causes of that event. One recurring mine safety problem—a dozer falling into a void over a drawpoint on a coal surge pile—was analyzed using available, inexpensive fault tree programs on a personal computer. The analysis identified basic and intermediate events that led to the burial of the dozer and graphically depicted the interrelationship between these various subordinate events as well as the various chain of events leading up to the primary event. A sensitivity analysis on these probabilities showed which events had the greatest influence on dozer burial in a coal surge pile.

By A. S. Ibrado, D. W. Fuerstenau

The adsorption of the cyano complexes of Ag(I). Cu(l), Hg(II), Cd(II), and Zn(II) on activated carbon was investigated as a function of pH and correlated with the speciation diagram for each metal. The results show marked changes in uptake with pH, closely resembling the predominance profiles of their neutral and singly charged cyano complexes. Multicharged negative complexes are repelledby the negatively charged carbon surface. The sensitivity of activated carbon to the charge of the adsorbing species indicates that silver adsorbs as an anion, not chemically bound to the coadsorbing counterions. For the same reason, activated carbon is selective to metals that preferentially form neutral and singly charged cyano complexes, namely gold and silver.

Jan 1, 1990

The Lower Palaeozoic Woolomin Association is composed of chert and jasper (often radiolarian), siliceous argillite, the mafic volcanics with associated hyaloclastites, and occasional greywacke and limestone lenses. Several "Cyprus-type", conformable pyritic copper (+/- zinc and cobalt} sulphide lenses are spatially related to individual mafic volcanic units and manganiferous chert and/or jasper. The Association has been interpreted to represent an oceanic crustal remnant generated either in an island arc environment (Herbert, 1981) or at a divergent plate boundary (Scheibner and Glen, 1972; Leitch, 1974a, 1975) later to be obducted, or tectonically emplaced, into continental crust; the adjacent Peel Fault was considered to be the palaeo-obduction zone (Scheibner and Glen, 1972) and the associated alpine-type mafic/ultramafic complex, an ophiolite (Crook and Felton,1975).

Jan 1, 1990

By A D. Ferreira, A E. C, A D. Padovezi

The increasing market requirements regarding the quality of products, the enhanced predictability from detailed mine planning, the need for process consolidation and upgrading require continuous investigation on the characteristics of different ore types to be concentrated. This paper addresses the mineralogical and technological characterisation of several itabirite iron ore types and the influence of the composition and mineralogical associations on desliming and flotation. Pellet feed quality and the influence on the major performance indicators, such as weight recovery of slimes, selectivity index, metallurgical recovery, flotation kinetics of iron minerals and gangue is also emphasised. The investigation resulted in a classification of iron ores according to their mineralogical composition, morphology of the crystals, and/or texture and microstructure of mineral particles with respect to desliming and flotation performances.

Jan 1, 2005

By Owen S. Roberts

During the design phases of a conveyor system, the question arises regarding the type of drive required for each application. The paper shows that the correct drive for any particular application is the one that satisfies the criteria established for that application in the most economical manner consistent with such considerations as site location, availability of spare parts, area environmental conditions, power supplies available, etc. Following discussions of various mechanical arrangements for the drives, motor types and their characteristics are considered along with the control means of modifying these characteristics to satisfy individual requirements. These characteristics are all illustrated graphically. After selecting the motor and its starter, control accessories and interlocking arrangements as applied to material handling systems are discussed.

Jan 1, 1973