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By R. S. Sheeta, C. J. Bise

The search for a more effective means of coping with methane liberation has resulted in the expanded use of seam degasification. Its advantages are measured not only in reducing the hazards due to methane, but also in producing a marketable commodity, the gas itself. However, the success of a methane drainage system is the culmination of many complex factors, the most important being the coal seam permeability. The two most popular drainage techniques used in mining today are the vertically stimulated borehole method and the in-seam horizontal borehole method. The objective of this paper is to determine the permeability range in which the selection of the degasification technique is based primarily on equipment and economic analysis. A discussion of the equipment involved will be incorporated into examples evaluated by the Pennsylvania State University coal methane simulation model.

Jan 1, 1990

By Richard A. Williams

The design, modelling and simulation of solid-liquid mixers remains one of the least advanced aspects of minerals processing, due to difficulties in quantifying complex slurry hydrodynamics from first principles, and in acquiring reliable experimental data for model verification and development. This contribution describes the application of electrical resistance tomography (ERT) for three dimensional imaging of the concentration of mineral particulates in a slurry mixer as a function of key process variables (particle size, impeller type, agitation speed). It is demonstrated how ERT can provide a wealth of detailed data to allow model development, which ultimately will lead to much improved design capabilities and the generation of mixing models which could reside within Particle Process Simulators. This principle is illustrated using descriptions of mixer behaviour based on an empirical approach, although the measurement methodology described is equally suited to development of computational fluid dynamics models, cellular models or design approaches based on artificial intelligence. The experimental data can be built into a visualisation data bank, which acts as a "process toolkit" by allowing a library of process responses to be catalogued. Hence these data can be accessed for the purposes of model development, equipment selection, optimisation of operating conditions or testing on-line control strategies.

Jan 1, 1995

By P. C. Cochrane, I. S. Clelland, S. H. E. Phillips

Geological and hydrological conditions in the strata overlying the Salado Formation vary considerably in the Carlsbad, NM, area. The first four shafts sunk at International Minerals and Chemical Corp. (IMC) property have been located in competent and essentially dry conditions, while other shafts on adjacent properties have had such adverse conditions that ground freezing has been chosen as the water and ground control technique for shaft sinking. At the location of the IMC No. 5 shaft there has been extensive erosion and salt dissolution in the Rustler Formation, leading to collapse of some zones of the strata. Both ground freezing and pregrouting were considered as alternative methods of stabilizing the extremely poor ground conditions and controlling the potentially very heavy water inflows. It was decided that pregrouting the shaft was feasible and would offer substantial cost and time saving over a ground freezing technique. This paper describes the pregrouting techniques used and illustrates the requirement for flexibility in a grouting program so that it can be modified to reflect any new or additional information obtained during the progress of the grouting.

Jan 1, 1987

By J. L. Huiatt, D. G. Foot, J. D. McKay

The US Bureau of Mines compared column flotation using either fine or coarse bubbles with conventional flotation on a Montana chromite ore. On deslimed ore, fine-bubble column flotation produced a &.7% Cr2O3-grade rougher concentrate with 87% recovery, compared with 43.8% and 43.5% Cr2O3-grade rougher concentrates with 85% and 77% recovery for coarse-bubble column flotation and conventional flotation, respectively. On undeslimed ore, coarse- and fine-bubble column flotation produced rougher concentrates containing approximately 41.5% Cr2O3 with 95% recovery, exceeding conventional flotation, which produced 35.6% Cr2O3 -grade concentrates with 87% recovery.

Jan 1, 1987

By Juan Eduardo Barrera

SUNNARY AND CONCLUSIONS Argentina presents to the foreign and local investors a mineral wealth that is largely unexplored, untested, underdeveloped and therefore incompletely evaluated. In view of the above, the new administration of President Raul Alfonsin through its Department of nines has designed and implemented a strategy ( Plan de Expansión Ninera P.E.M.), whose main objective aims at improving the "investment climate" in the sector. It is the Government's basic intention to apply the Mining Promotion Law with responsibility but with generosity to encourage the attraction of investment (local and foreign) to the sector. The establishment of a Data Bank system to evaluate possible new potential ore mining developments will help to connect the owners of potential projects with investors outside the sector. Argentina has an interesting gold ore potential. Estimated reserves of individual projects already known amount to almost 300 tonnes of gold for potential production. The government strongly believes and present information indicates that more systematic exploration has to be undertaken in the Jurassic areas that almost cover the whole of Patagonia. Two recent gold discoveries (Angela in the Chubut province, and Cerro Vanguardia in Santa Cruz province) indicate the potential of this area.

Jan 1, 1988

By J. Y. Kim, S. L. Chryssoulis

Lead ions that originate from galena during the processing of complex sulfide ores migrate onto the surfaces of sphalerite and iron sulfide minerals. This results in poor selectivity during differential flotation. Generally, in sulfide ore processing, the lead-activated minerals float in the Cu/Pb rougher circuit. The surface lead complicates the zinc flotation circuit by lowering the concentrate grade. The effect of lead in the differential flotation of sphalerite from Cu-Pb-Zu and Pb-Zu ores is discussed. Plant and laboratory-test data are interpreted by determining the surface compositions of individual grains of sphalerite and iron sulfide particles. For the first time, surface compositions were determined by using laser-ionization mass spectrometry (LIMS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Cationic and cationic species on the surface were analyzed to elucidate the phenomena. It was proven that these new techniques are very useful in understanding the basic mechanisms of a sulfide mineral-flotation system.

Jan 1, 1997

By T. A. P. Sankar, S. Gundiah, Pradip, R. A. Kulkarni

Two modified polyacrylamide flocculants, namely polyacrylamide with glycolic acid functionality (PAMG), and a copolymer of acrylamide with N-acryloyl-[T]- aminobutyric acid (HPVP), were synthesized, characterised and evaluated for selective separation in apatite/quartz and apatite/dolomite/calcite systems, respectively. PAMG flocculant was found selective in the separation of tricalcium phosphate (TCP) from its mixtures with quartz at acidic to neutral pH range. The selectivity deteriorated at alkaline pH. In contrast, polyacrylic acid (PAA) flocculant was found most effective only in the alkaline pH range. HPVP flocculant (even though flocculating all three minerals namely apatite, dolomite and calcite) was observed to be quite selective for the separation of calcite from apatite-dolomite minerals in single mineral tests in the presence of sodium hexametaphosphate dispersant at neutral pH. There was, however, no selectivity observed during tests on synthetic mixtures. This loss in selectivity is attributed to the phenomenon of hetero-flocculation, as reported earlier, for separation in an apatite-dolomite system with polyethylene oxide.

Jan 1, 1993

By Chien D. Ngo, Andre Bachmann, Rainer Bunge

The remediation of contaminated sites has gained great importance in many industrialized countries. One method for cleaning the polluted soils from such sites is "soil washing," the scope of which is the separation of the contaminants from the soil. Soil washing is an outstanding example for a successful transfer of technology from Mineral Processing to Environmental Engineering. This presentation intends to introduce the Mineral Processing Engineer to soil washing through a short review of the fundamentals, and the discussion of an example for a successful soil cleaning operation in Switzerland.

Jan 1, 1995

By W. Addy Majewski, Kenneth L. Bickel

The U.S. Bureau of Mines (USBM) and Diesel Controls Limited evaluated a new diesel emission control system on an underground mine vehicle. The system was a catalyzed ceramic wall-flow diesel particulate filter (CDPF) combined with an catalytic converter, or diesel oxidation catalyst (DOC). This paper describes the design and installation of the system on a load-haul-dump (LHD). The results of screening tests conducted by the USBM are also given. The screening tests were conducted to determine if the device's particulate collection efficiency, regeneration temperature, and effect on gaseous hydrocarbon (HC) and carbon monoxide (CO) emissions changed over the period it was being used. The system was removed from the LHD and evaluated in the laboratory after operating for 308 and 1200 hours. After 308 hours of operation, laboratory testing revealed its particulate collection efficiency varied from 41.0 to 93.5 percent, depending on engine operating conditions. Its regeneration temperature was about 415° C. It reduced HC emissions by up to 97.6 percent, and CO by up to 95.0 percent. When tested in the laboratory after operating for 1200 hours on the vehicle, no significant change in performance was observed.

Jan 1, 1995

By A. Mehmet, W. A. M. te Riele

A pilot-plant investigation in a NIMCIX contactor has shown that activated carbon can extract more than 93% of the gold in return-dam solutions. The average gold concentration in the barren solution was less than 0.003 mg/L from a feed averaging 0.048 mg/L. The carbon was eluted by the Zadra procedure. The operating conditions of the elution-electrowinning circuit are reported, and the elution of the gold and other metals is discussed. The reactivation of the carbon by use of the Rintoul kiln is described, together with the results of reactivation. The consumption of reagents in the process cycle is presented in sufficient detail to allow the economic viability of this technique to he evaluated for the recovery of gold from low-grade solutions.

Jan 1, 1990

By Richard Hogg, Erol Kaya, Jan M. Mutmansky

Characterization of the size, shape, chemical composition, and mineralogical content of mine airborne dusts generally requires a larger mass of dust particles than is typically collected using traditional sampling devices. In this paper, the general design of a passive dust collector is described and the field results are presented. The collector was constructed of galvanized sheet metal duct with a resin-coated honeycomb to provide an elutriation-type system for particle collection. Several versions of the collector were used in the field portions of the research. The dust samples collected from underground coal mines were found to possess angular particle shapes, relatively consistent size distributions, and elemental compositions that showed relatively little variation, at least for the more prevalent elements. In addition, the distributions of particles sizes obtained from the passive dust collector appear to be similar to those of samples collected at the same time in a conventional personal sampler except that the passive device seems to collect a larger quantity of coarse, non- respirable particles. Conclusions on the suitability of this dust collector for collecting characterization samples are presented. In addition, the potential for using such a dust collection system for supplying dusts for biomedical research is discussed.

Jan 1, 1993

By H. Barry Holt, Charles A. Bischoff

On November 15, 1990, President Bush signed the Clean Air Act Amendments of 1990. The new legislation is sweeping in its demands for cuts in smog, acid deposition, toxic air pollutants and ozone-depleting chemicals. The Amendments will siqnificantly alter air quality permitting and compliance and are estimted to cost billions of dollars to implement. This article provides an overview and summary of each of the eleven titles of the Amendments. It also addresses how the Amendments will be implemented.

Jan 1, 1991

By Parris A. Lyew-Ayee

This paper is the first preliminary report on the bauxites and terra rossas of the Caribbean. It concentrates on the islands of the Greater Antilles, and for reference purposes the Yucatan Penin- sula is included. At this point, observations made in Jamaica, Haiti, and the Dominican Republic are compared with reported information on Puerto Rico, the Bahamas, Cuba, the Cayman Islands, and the Yucatan Peninsula with regard to occurrence, as well as physical, chemical, and mineralogical composition. From this, an attempt is made at classifying the types of bauxites in the Caribbean, indicating the best reserves estimates, and the process ability of these bauxites. Some suggestions are also provided to fuel the controversy over the likely source material(s) or origin of the Caribbean bauxites.

Jan 1, 1984

By G. J. Melvin

Mines the world over tend to face a common range of problems. They begin life by trying to determine if there is sufficient product, usually under tons of earth, of sufficient quality to justify the operation. Once such a determination is made the mine must then be planned and brought into operation. Once operating most mines find that they are far away from suppliers, using very expensive equipment. Hence the three most common mining problems are, what does my ore body look like and how can it best be mined, how can I get sup- plies to my mine in the most cost effective way, and how do I control the vast dollars required to keep it all operating. Mincom started life by providing technical mining software to address the first of these problems and was very successful, particularly in the coal mining industry. However the company soon realized that if it was to become a significant provider of mining industry software it must also address the other major problem areas. Hence started what is now Mincom's largest business which is the provision of fully integrated mine management software with strong emphasis on materials and maintenance management to control costs. Mincom not only supplies the software but also provides a comprehensive implementation package using its own staff of experienced mining industry specialists. This papaer highlights some of Mincom's international implementation experiences.

Jan 1, 1989

By J. Michael Howard

Holes cored through the Prairie Creek lamproite volcanic complex at the Crater of Diamonds State Park by companies interested in the site's commercial diamond potential give an opportunity to redefine the size and shape of the Prairie Creek pipe. Relationships of cored rock sequences and the discovery of a previously unrecognized major rock type allow a reinterpretation of the sequence and type of intrusive activity. Trench sampling of diamondiferous rock units yielded a diamond content far below what was anticipated based on an estimate from historical records. Inadequacies of shallow bulk-testing methods for a diamondiferous pipe are examined.

Jan 1, 1999

By J. E. Gebhardt, S. Chander

Significant advances have occurred in the use of electrochemical techniques for sulfide mineral flotation research. The techniques have been used singly or jointly with other characterization methods. When used in combination with other methods, the electrochemical methods provide a means to control the state of oxidation of the surface. Various analytical methods are employed for characterization. The methods that have been used include wetting, x-ray photoelectron and fourier transform infrared spectroscopies. The electrochemical methods include voltammetry and transient electrochemical techniques of galvanostatic polarization and AC impedance spectroscopy. The challenge for the future lies in the utilization of this knowledge in plant operations so as to increase the overall efficiency of flotation separations.

Jan 1, 1989

By Anthony D. Hammond, Charles A. Kliche

A slope stability study for the Annie Creek and Foley Ridge Mines was undertaken to provide Wharf Resources, Inc. with a technical assessment of the stability of the slope for an overall pit slope angle of 60°. A rock analysis of the most critical and persistent combination of discontinuities was carried out using probabilistic methods. A detailed discontinuity mapping and assessment of the rock mass provided the orientation data used in this study. The orientation data were reduced and analyzed to identify the discontinuity sets. A statistical analysis provided information about the distribution of the data. A deterministic wedge stability analysis identified the critical combination of discontinuities; those with a low factor of safety were further studied using probabilistic kinematic and kinetic stability analyses. The results from this approach were used to obtain the reliability or probability of failure of the slopes.

Jan 1, 1988

By Mulong Yu, Yosry A. Attia

Beneficiation of high magnesium Florida phosphates requires ultrafine grinding to liberate the dolomite (the main source of magnesium), and a separation process capable of dealing with ultrafine sizes such as selective flocculation. The objective of this study was to investigate the feasibility of separating dolomite from apatite ultrafines by selective flocculation. To achieve this objective, selective polymeric reagents to either dolomite or apatite must be first designed and synthesized. This challenging task was accomplished by carefully selecting complexing/chelating agents which are selective to either the Ca or Mg ionic sites on the minerals, and incorporating these reagents into the structure of long chain water soluble polymers to obtain either selective flocculants (with high molecular weight, MW, polymers), or selective dispersants (with low MW polymers) to either the dolomite or the apatite particles. Synthesis and testing of these polymers on individual and mixed mineral slurries, and on a sample of natural high magnesium phosphate ore, have been attempted and the results are described in the paper. The preliminary results showed encouraging signs for the feasibility of selective flocculation separation of dolomite from apatite.

Jan 1, 1993

By Jose M. Milian, Raphael F. Matson

An intensive study was started in 1968 to determine the most economical process for winning nickel and cobalt from an extensive de- posit of complex, low grade nickel-cobalt ore (1.6% Ni, 0.10% CO) designated "the Greenvale ore." In 1974 the commercial plant at Yabulu, in Queensland, Australia, began processing the ore. In the interim, a great deal of laboratory and pilot-plant effort was applied to develop technical, process and commercial design data to demonstrate to potential financial backers and customers that a full-scale plant was feasible. The laboratory test work, pilot plant facilities and pro- gram are briefly reviewed in this paper.

Jan 1, 1979

By B. J. Arnold, F. F. Aplan

A model incorporating rate and residence time to describe the froth flotation process was used to provide data for the evaluation of various kinetic flotation models and to provide scale-up information from laboratory to industrial scale coal froth flotation. Rate constants were determined in laboratory and plant froth flotation tests and the residence time distribution was measured for a bank of four 21 ft 3 (0.6 m3 ) WEMCO cells treating Upper Freeport seam coal and a bank of four 300 ft 3 (8.5 m3 ) cells treating Lower Kittanning seam coal. It was found that a lag time for continuous flotation should be incorporated into scale up models and that a kinetic froth factor ratio of between about 2.0 and 2.8 should also be used to scale up data from laboratory to plant scale.

Jan 1, 1989