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By Pascale St-Germain, Michael Li, Lionel J. J. Catalan

The oxygen flux into water-covered reactive sulphidic tailings is required for evaluating the long-term performance and predicting the quality of engineered shallow water covers. This information can also serve as an input to the design of water covers for reactive tailings decommissioning. This paper describes some dissolved oxygen (DO) profiles recently measured in the field across the tailings/water interface and oxygen fluxes derived from these profiles. These fluxes are compared with previously reported flux values from similar field measurements. Techniques and pitfalls for measuring DO profiles and calculating oxygen fluxes are also discussed.

Jan 1, 2000

By S. Mathur, Pradip

Polyacrylic acid (PAA) was evaluated as a selective flocculant for the dolomite-apatite system. PAA with a molecular weight (MW) of 4 million was found to flocculate both dolomite and apatite. However, the flocculation behaviors of dolomite and apatite were significantly different with 450,000 MW PAA, which was found to be the lowest molecular weight fraction capable of flocculation. In single-mineral tests with a dosage of 2 kg/t PAA, 90% of the dolomite and 35% of the apatite flocculated. Selectivity was achieved in mixed mineral tests. From a feed consisting of an 80:20 mixture of apatite and dolomite, respectively, a concentrate containing 90% apatite was obtained with a 70% recovery. The dolomite rejection was about 75%, which corresponds to a 2% MgO content in the concentrate.

Jan 1, 1997

By P. Berendsen

The tectonic and sedimentary environment of the Central North American Rift System (CNARS) provides all excellent setting for major mineral deposits. Major north-northeast-trending high-angle normal or reverse faults and northwest-trending transcurrent fault systems may exercise control over ore forming processes. Gabbro and basalt are the dominant igneous rock types. Carbonatite and kimberlite occur in Nebraska and Kansas. Concentrations of Cu. Ni, Co, Ti, Au. Ag and PG-minerals are known to occur in this setting. Arkosic sandstone, siltstone, shale, and minor carbonate units occur on top of the rift basalts and in flunking basins where they may reach thicknesses of 10 km (6 miles). The potential, for stratiform or unconformity-related metalliferous deposits must be considered. The rift as a whole remains, however, largely unexplored.

Jan 1, 1990

By Y. Nakahiro, T. Wakamatsu, M. S. Elsalmawy

The flotation of quartz, feldspar and alumina was studied as a function of pH when using N-alkyldiamines as collectors. The lengths of alkyl chains of diamines were 8, 9, 10, and 12 carbon atoms. It was found that shorter hydrocarbon chain length of alkyldiamines has stronger tendency to float quartz while the feldspar responded poorly to flotation with these collectors at high pH values. The effect of addition of nonionic surfactant of Brij type, when using dodecadiamine as collector, was investigated. Flotation studies in the absence and in the presence of sodium dodecylsulfonate were carried out. These studies have indicated that sodium dodecylsulfonate, in the concentration studied, functions as strong depressant for feldspar.

Jan 1, 1995

By G. Pierson

Explanations for commodity price levels (or movements) commonly focus on the fundamentals of supply and demand, otherwise they are simply assigned to speculative activity. Comparisons of metal-price histories to monetary and other economic data support the argument that the supply of and demand for money are no less important in the determination of price than are the supply and demand of the commodity itself. That these relationships should exist is evident in the price identity and they are consistent with monetary theory. The patterns developed have limited usefulness as predictors, but their recognition is essential for the construction of price scenarios for planning purposes.

Jan 1, 1997

By Kal V. S. Sastry

Mineral processing simulation has come a long way since its beginning about thirty years ago. With our increased understanding of mineral process systems and the advent of new software and hardware technologies, we can visualize an ideal mineral processing simulator. This paper attempts to identify a number of desirable features of an ideal mineral process simulator and to describe the exciting trends in making such an ideal simulator a reality.

Jan 1, 1992

By Frank R. Cappuccitti

This paper will deal with current market trends for sulfide mineral collectors in three distinct parts; the global market for sulfide collectors, collectors as tools to solve mineral processing problems and new collector Research in the 1990's. The global market and manufacturing of sulfide collectors will be detailed as well as the trend towards using increasing amounts of specialty products. The use of Total Quality Concepts for laboratory and plant evaluations of new products will also be discussed. Research in the 1990's for sulfide collectors will need to focus not on the development of new chemical species but on the application of the new technologies that have already been developed.

Jan 1, 1994

By Barada K. Mishra

The potential merit of the discrete element method (DEM) as a numerical tool for analyzing process engineering problems involving particulate material is discussed. In this method, the dynamic equilibrium equations for each distinct and deformable body are solved. Therefore, it readily lends itself to modeling large numbers of discrete, interacting bodies as in mineral processing operations where a charge of particulate material is processed. Here some applications of DEM are reported: motion of particles in the ball mill, mixer, and jig. Although DEM has made very little headway in mineral processing research, it is shown here that a host of other areas of industrial interest in the context of flow of particulate materials can also be made amenable to analysis by this method.

Jan 1, 1993

By George L. Baloo, Dave Kwiatkowski, Jose G. Cañlzales

Capital project funding for a medium to large materials handling project often includes a budget for procurement of supplier-recommended spare parts, and it is the Project Team's responsibility to select these parts. With today's economic climate, limited budget, and other factors, the spare parts selection process is a difficult and arduous effort. This decision carries with it a risk to plant operations and in some cases the commodities producers. Too often the decision-making process is not documented, and the reasons for eliminating and reducing quantities are based on "best guess " Recently on the Solids Handling Phase 2 Project in Jose, Venezuela, the Project Team took a unique approach to this problem. This paper discusses the analytical approach taken by the Project Team, the database system that was developed to manage this problem, lessons learned, and their applicability to pre- project planning and preliminary design.

Jan 1, 2004

By Daniel K. Dysinger

Capital resource budgeting is the way managers of publicly held companies fulfill their fiduciary responsibility to maximize the wealth of stockholders. Managers maximize shareholder wealth by allocating investment capital to the most productive of competing alternative projects. Managers do this in a manner that maximizes the net present value of the firm's future cash flow. The techniques of cash flow analysis are the primary tools available for selecting a corporate portfolio of projects that meets or exceeds the rate of return expected by shareholders. The reliability of cash flow analysis hinges on the ability of managers to forecast the future values of individual components of cash flow. The accuracy and reliabil¬ity of forecasting determine the soundness of capital investment decisions and, ultimately, determine the value of the firm.

Jan 1, 1997

By A. Marabini, G. Belardi, N. Sheau, F. Veglio

The present paper deals with the modelling of a Multi-gravity separator in the treatment of chromite fines. A first screening study was carried out by 2" full-factorial experiments in order to check the main effects and interactions among the investigated factors: shake frequency, shake amplitude, tilt angle and washwater flowrate were taken in consideration in the study. Two size fractions were employed in the experimental tests. Successively, considering the factor with larger influence on the Cr203 and SiO2 grade and Cr203 recovery in the concentrate, a further improvement of the experimental design was performed to determine empirical models to describe the behaviour of the MGS in the mineral treatment. The results show how intrinsic interaction among the factors take place, highlighting that an optimization study must be carried out considering all the MGS setting parameters.

Jan 1, 1995

By G. G. O. O. Uwadiale

A number of Nigerian iron ore deposits have been upgraded to the specifications of concentrates for the blast furnace and the direct reduction iron- and steel-making plants. Depending on the mineralogy of the ore deposits, the techniques of oil agglomeration, magnetizing reduction, washing and scrubbing, gravity concentration, and reverse froth flotation have been utilized. A mode of distributive management of the deposits, in the direction of their technoeconomic utilization in the country's developing iron and steel plants, is presented.

Jan 1, 1990

By Paul M. Godlewski, Gerry Millar, Harvey W. Parker

Recently, over 70 railroad tunnels in the western USA have been enlarged and rehabilitated "live track," utilizing modern excavation and lining methods, in most cases to clear the larger double-stack container cars. This paper presents the general conditions of the tunnels and the technical aspects and costs of the rehabilitation of approximately 40 kilometers of tunnels, which range in length from a few hundred meters to 13 kilometers. Concrete-lined tunnels were rehabilitated by grouting and rock bolting, while unlined or timber-supported tunnels were relined with shotcrete and rock bolts. High output lining methods were required because of limited track time. Enlargement has been accomplished primarily by carving notches out of the concrete linings with a roadheader, or occasionally with saws. Unlined tunnels were enlarged by drill-and-blast or roadheader excavation.

Jan 1, 1991

By Robert Irvine

Exploration activity for diamonds in Canada has recently experienced a dramatic increase. Disclosure of a diamond discovery exhibiting features of a potentially economic deposit contained in a kimberlite pipe in the Lac de Gras area of Canada's Northwest Territories has sparked substantial interest in-Canada and abroad and has triggered the largest staking rush in terms of area in the history of Canadian exploration. In this paper, we report on the nature and extent of current exploration activity in Canada for diamonds (with special attention to Arctic regions), the results of this activity to date, and the context in terms of current world markets for diamonds.

Jan 1, 1995

By A. J. Friedrich

Conveyor belts are designed to go unnoticed. When they work well, they attract little attention. When they are not doing the job right, it is noticeable, and they need to be fixed immediately. Vulcanising contractors compete for the maintenance of belts in mining/quarrying and general materials handling worldwide. Damage repair is approached in similar fashion. The damaged section of belting is normally cut out and discarded, and the belt re-spliced using hot vulcanising, Cold splicing, or mechanical fasteners/clip joints. However, there is a cost-effective alternative, alleviating the need to remove damaged sections which are often perfectly recoverable. This is the use of cold-curing repair resins and adhesives.

Jan 1, 2000

By J. C. Franklin

The U.S. Department of the Interior, Bureau of Mines, has developed a data acquisition system to continuously monitor radon, working level, absolute pressure, temperature, relative humidity, and air velocity. Data have been taken in intake and exhaust drifts, working stopes, and sealed-off areas of positive and negative ventilated uranium mines. Radon emanation rates, ranging from 1.7- to 12.2 x 2 10-l4 Ci/cm /sec were determined in four mines. The ratios of short duration, primary fan shutdown time to radon normalization time were 1 to 2 and 1 to 4, respectively, for-negatively and positively ventilated mines. Blasting and slushing caused radon increases of 160 and 67 percent, respectively.

Jan 1, 1980

By Donald P. Spitzer, Peter V. Avotins

The flow properties of thickener underflow slurries can be characterized by their rheological parameters. Most of these slurries exhibit Bingham plastic behavior, characterized by a yield stress, to, and a Bingham viscosity, nB. Red mud is generated as a leach residue in the Bayer process. The use of new Bayer process flocculants which contain hydroxamate functional groups leads to muds which are qua1itatively considerably more fluid than muds generated with conventional polyacrylates or acrylatefamide copolymers. A variety of rheological tests confirm lower yield stresses and less extended floc structures with the new flocculants, at the same solids levels. Conversely, under given viscosity restraints, the new polymers make it possible to operate at higher solids levels, which offers major benefits in processing red muds.

Jan 1, 1992

By L. B. Rothfeld

Two new coal use technologies are on the verge of commercial acceptance by the utility industry: atmospheric fluidized bed combustion (AFBC) and gasification combined cycle (GCC). Generating plants under construction or in planning will replace older pulverized coal (PC) boilers or substitute for new PC boiler capacity. This paper reports recent developments in the commercialization of AFBC and GCC, emphasizing the potential impact on the coal mining industry. The influence of coal quality characteristics on fuel selection is explored by means of preliminary economic calculations for different coals and competing fuels.

Jan 1, 1987

By Craig J. Nelsen, David A. Smith

In 1987, LAC Minerals (USA), Inc. conducted a high resolution helicopter electromagnetic (EM) and magnetic geophysical survey on the Ortiz Mine Grant, New Mexico. The primary purpose of this survey was to assist in geologic mapping of a major structural zone, the Tijeras-Canoncito Fault System (TCFS). This structure is a very important ore- controlling feature in the area. Geophysical signatures over known deposits was a secondary goal of the survey, but direct detection of mineralization was not anticipated. The TCFS was revealed to be a complex, branching and anastomosing system of faults which locally form the bounding structures of a graben. The geophysical survey guided subsequent geologic mapping by redirecting field investigations, and geophysically redefining some features which previously had been only partly defined.

Jan 1, 1989

By Arpad E. Torma

The electrochemical behavior of a zinc sulfide concentrate during the microbiological leaching was investigated using ZnS-carbon paste electrodes and a cyclic voltametric technique. The effects of Zn2 [ ] , Fe2+, Fe3+ and Cu2+ on the cathodic and anodic currents associated with zinc sulfide leaching in presence and absence of microorganisms, were assessed. The semiconductor nature of zinc sulfide was discussed in terms of ability of microorganisms to obtain their metabolic energy (through removal of electrons) from this high energy gap substrate. The intermediate electrochemical reactions involved in the ZnS leaching were described.

Jan 1, 1989