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By R. Hogg, R. H. Weiland, P. Bunnaul

The dewatering of flocculated clay suspensions by compression in a centrifugal field was investigated. The results were analyzed with respect to the direct applicability of centrifugal dewatering (as in solid-bowl centrifuges) and indirect applications to gravity sedimentation systems. An important objective of the study was to evaluate the self-weight effect using centrifugal forces to simulate consolidation of deep sediments. Experiments were conducted in which the sediment mass and initial structure were maintained constant while the effective sediment weight was varied by centrifuging at different speeds. The relationship between the limiting sediment density and the applied consolidation stress was found to be the same for both gravity and centrifugal consolidation, indicating that small-scale laboratory tests can be used to predict consolidation in deep beds. The effects of the initial structure were also studied using controlled variations in flocculation conditions. The results imply that, for the flocculated suspensions studied, the longterm consolidation behavior is relatively insensitive to the actual extent of flocculation.

Jan 1, 1995

By V. L. Jr. Davis, F. L. Stanley, P. J. Bethell

Fwe 3 m (10 ft) diameter Microcel™ flotation columns were installed at Clinchfield Coal Company's Middle Fork preparation facility in order to reduce product ash and increase recovery and plant capacity. The Middle Fork facility is utilized for the recovery of fine coal from a feed stream that consists primarily of 1 .5 mm x 0 material. The columns replaced conventional flotation cells for the treatment of the minus 150 pm fraction while spirals are used to upgrade the plus 150 pm material in the plant feed. The addition of the column flotation circuit resulted in an increase in plant capacity in excess of 20 percent while reducing the flotation product ash content by approximately 7 percentage points. Flotation circuit combustible recovery was increased by 17 percentage points. This paper discusses circuit design, commissioning, and sparging system design. Circuit instrumentation, level control, reagent system control, performance comparisons with conventional flotation, and general operating procedures are also discussed.

Jan 1, 1995

By P. Bevilacqua, G. Ferrara

The paper discusses the problem of accuracy in the determination of the partition curve of gravity separation processes, which is strongly affected by both the sharpness of separation of the density analysis system used and the width of the density range selected. The problem is important when the density analysis of the separation products cannot be performed using heavy liquids, but has to be performed using heavy suspensions or using other systems such magnetogravimetric separation. The imperfect separation given by these systems and the use of large density ranges lead to the determination of apparent partition curves instead of actual partition curves for the process. In the paper the relation between apparent and actual partition curves is studied under different conditions through a simulation program. For different input data, special diagrams are given which, once the apparent partition curves and the sharpness of the density cuts are known, allow calculation of the actual partition curves and the related parameters.

Jan 1, 1995

By P. E. Snoek, R. L. Gandhi, C. S. Miller

Slurry operations are an integral part of mineral processing. There is therefore reason to consider using slurry pipelines for long distance mineral transportation. This paper reviews the current state-of-the art of such systems and, in particular, the design factors which must be addressed. It also discusses the selection of major components such as pipe, pumps, valves and storage facilities. Finally, the major steps required to determine the economic feasibility of a slurry system are listed and the major advantages and disadvantages of slurry pipelines compared with other forms of land transport are summarized. SLURRY PIPELINES: GENERAL OVERVIEW Minerals Transported Long distance slurry pipelines have been successfully used for transporting coal, iron concentrate, copper concentrate, limestone and phosphate. Additionally, several tailings disposal pipelines of considerable size and length have been built, but these generally are not categorized as long distance commercial mineral transportation systems. Table 1 lists selected examples of commercial slurry pipelines.

Jan 1, 1986

By George A. Desborough, Stephen J. Sutley, Reinhard W. Leinz, Paul H. Briggs

The mode of occurrence of metals in mine wastes is investigated using sequential extractions. Metals are extracted from some or all of seven operationally-defined phases: water-soluble, ion-exchangeable, carbonate, amorphous Fe-oxide, crystalline Fe-oxide, sulfide, and silicate. The quantity of metals extracted from each phase varies with particle size. The presence of jarosite (potassium end-member formula, KFe3[SO4]2[OH]6) influences the selection of the procedure for extracting the crystalline Fe-oxide phase. Anglesite (PbSO4) and cerussite (PbCO3) are extracted as several phases. Extraction results can be explained only in part by X-ray diffraction (XRD) mineralogy because of lack of specificity of the extraction procedures, relatively high XRD detection limits, and the presence of 40% XRD-amorphous matter in each waste. The increasing chemical strength of the sequentially applied methods provides a basis for judging metal availability, water-soluble metals being most available and silicate-bound metals being least available.

Jan 1, 2000

By K. A. Natarajan, J. M. Modak, P. Anand

A microbial survey of Jamnagar bauxite mines in Gujarat, India, revealed the indigenous presence of a variety of autotrophic and heterotrophic bacteria and fungi associated with the ore body and water ponds in the vicinity. Among these, bacteria belonging to the genera Thiobacillus, Bacillus and Pseudomonas are implicated in the weathering of aluminosilicates; the precipitation of iron oxyhydroxides; the dissolution and conversion of alkaline metal species; and the formation of alumina, silica and calcite minerals. Fungi belonging to the genus Cladosporium can reduce ferric iron and dissolve alumina silicates. Biogenesis thus plays a significant role in bauxite mineralization. Various types of bacteria and fungi, such as Bacillus polymyxa, Bacillus coagulans and Aspergillus niger, were found to be efficient in significant calcium solubilization and partial iron removal from bauxite ore. Probable mechanisms in the biobeneficiation process are analyzed. Biobeneficiation is shown to be an effective technique for the removal of iron and calcium from bauxite ores for use in refractories and ceramics.

Jan 1, 1998

By M. J. Shulman

The exploration geologist is frequently confronted with the problem of allocating his resources, i.e., exploration effort, among various areas. Although geologic, financial, and logistic considerations influence the allocations, no objective criterion is usually given that determines the optimal allocation. Maximizing the expected gain in information, subject to the constraint of a limited exploration budget, is used as the objective criterion to allocate airborne reconnaissance effort. The information function, I(x), quantifies the expected gain in information, where x is the scale of exploration. To calculate the information function, the following probabilities are required: the probability that an area contains a deposit; the probability that an anomaly is produced by the target; and the probability that an anomaly is produced by a barren area (false signal). Alternatively, the barren areas can be replaced by other targets. To illustrate the allocation method, the optimal number of line kilometers, i.e., the optimal line spacing per area, is determined for an aeromagnetic survey for iron in Egypt.

Jan 1, 1987

By B. J. Arnold, C. D. Harrison, R. A. Lohnes

More than 544 Mt (600 million st) of coal are handled annually for use by this country's coal fired power plants. Coal is transported in various ways: overland conveyors, railcars, trucks and barges. It can travel short distances or thousands of miles, picking up moisture, freezing or drying. When the coal is received at the power plant, environmental problems with fugitive dust and further handling problems can arise. To ensure that power plant availability is not jeopardized by coal handling problems, the Electric Power Research Institute's (EPRI) Coal Quality Development Center (CQDC) developed a research program aimed at addressing utility coal handling problems. The program has identified key areas, and is investigating the cost and cause of coal handling problems as well as the solutions to these problems. The ultimate goal of the program is to develop a "handleability index" that utilities can use in their coal specifications or hardware for a utility's sampling system to predict handleability and determine if a coal shipment should be accepted.

Jan 1, 1993

By G. Baudet, M. Save

Ethoxylated phosphoric ester surfactants were evaluated as collectors for flotation of carbonates from sedimentary phosphate ores, at slightly acidic pulp pH, using sulfuric acid or sodium fluorosilicate as a phosphate depressant. With 12 to 15 carbon atoms in the hydrophobic chain, maximum collecting power was observed for 9 to 10 ethylene oxide units. Only fine carbonates, ranging in size from about 20 to 160 µm or 40 to 200 µm, were effectively removed with phosphoric ester collectors. Utilization of seawater, or water of extremely high hardness, did not detrimentally affect selectivity. Silica, silicates, and residual fine carbonates can be separated in a second flotation stage, with primary amine as a collector. Coarse carbonates are separated by direct flotation of phosphate with fluoride ion as a phosphate activator and primary amine as a collector. In a seawater pulp, fluoride ion was not required. Typical examples of laboratory and pilot- scale test results are given to illustrate capabilities of the various flotation flowsheets.

Jan 1, 1999

By R. E. J. Putman

The past ten years have witnessed substantial development of electronic equipment for execution of process control functions. The methodology of giving instructions to the data-handling system and the organization of the system, both the equipment and instruction coding taken together, have developed simultaneously. Examples of the technology specific to the mineral processing industry can be cited. Approaches to system design developed for the Pinto Valley concentrator incorporating slave and master data processing have been described by Arney, and his associates (1974). Madge (1970) has described the hierarchical systems employed at the operations of Cominco Ltd. The Kennecott Garfield smelter is controlled by a system of microprocessors linked to a general purpose data processor (Marchant, et al., 1977). These systems provide innovative approaches to couple advancing technical capability in electronic data processing to the objectives of process management. The current state of the art described in this chapter is certain to require updating in the 1980's with the advances in technology anticipated.

Jan 1, 1979

By Nikhil Dhawan, Veeranjaneyulu Rayapudi, Singh Rahulkumar Sunil

The ever-increasing demand for steel and the subsequent depletion of high-grade ores requires the massive utilization of low-grade iron ores. In the present study, an iron ore slime sample containing 56.1% Fe was investigated using physical beneficiation, carbothermal reduction, and a microwave-assisted process; however, physical beneficiation and microwave exposure were found to be inefficient as they yielded lower iron recovery. Using coconut shell as an alternative reductant was found to be promising and does not lead to the formation of higher iron oxides, such as fayalite and wustite phases. The microwave-assisted carbothermal reduction was found at par with conventional reduction, saving time and heating. The optimum magnetic concentrate obtained in both carbothermal reduction routes (microwave and muffle furnace: Fe grade, Fe recovery, and yield of 64.3, 97, and 84%, and 67, 99, and 83%, respectively) are suitable for alternative iron-making or blast furnace units.

By J. Engesser

A research project was undertaken to determine if coal addition tofluxed-magnetite pre-fired pellets would reduce nitrogen oxide (NOx)emissions during pellet induration. Iron oxidation rate tests, coal oxidation rate tests and calcination rate tests were conducted in a laboratory furnace to determine the amount of coal necessary to provide adequate heat for limestone calcination without producing detrimental effects to magnetite oxidation. Pilot scale pot-grate tests were then performed with and without coal in the pre-fired pellets to verify pellet quality parameters and nitrogen oxide emissions. The off-gas during each pot-grate test was analyzed for NOx, CO2, CO, SOx, and O2. There was approximately a ten percent reduction in NOx emissions with coal addition during the normal pot-grate firing cycle. There was a 75% reduction in NOx emissions during firing cycles that used 25% to 75% excess air during firing rather than the normal 300% excess air.

Jan 1, 2003

By Qing-Wang Hao

In this paper, the authors attempt to develop engineering based approaches for estimating safety factors against pillar and floor failures and predicting likelihood of subsidence events over abandoned coal mines in Illinois. There are two critical problems involved in the analysis: determination of geotechnical properties, and consideration of time effect. The authors attempt to solve the problems by generating hypotheses, which are used to modify existing engineering models for estimating pillar and floor safety factors. The modified models are validated using data from two well established databases of subsidence events over active and abandoned mines in Illinois. The data analysis suggests that most of the trough type subsidence events in Illinois were caused by floor failures rather than pillar failures. The subsidence incubation period seems to be directly related to initial floor safety factors at the time of mining. This correlation can be used to predict the likelihood of subsidence and to assess subsidence risks within both spatial and temporal contexts where detailed mine maps are available.

Jan 1, 1986

By Roger L. Baer

Introduction Brief Review -SEC mission & history -Development of SEC mining disclosure guidelines -Principles of good public company ‘disclosure’ SEC staff views of alternative approaches to mining company disclosure -SME Resource & Reserve Committee – April 2003 Food for thought

Jan 1, 2003

By Karen M. Kessen

The isotopic variations of lead from Mississippi Valley galenas have long been used to place constraints on the sources of the lead, and on the residence the of the lead in crustal reservoirs prior to its emplacement in the Mississippi Valley province. Similar studies based on strontium isotope variations in gangue minerals associated with the lead-zinc sulphides have been neglected until Haden's (1) study of such minerals from several localities in northwestern Ohio. His work revealed two things about the mineralization. Firstly, it shoved that the average isotope composition of lead from galenas from northwestern Ohio lies on the anamalous lead line characterizing Mississippi Valley-type leads, albeit at the least radiogenic end of the entire data array. This confirm earlier assignments of the Ohio mineralization as Mississippi Valley-type (Hey1 and others (2)). Secondly, Haden (I) showed that the strontium in the calcite, strontianite and fluorite is broadly similar in isotopic composition to the strontium in the host Silurian to Devonian marine carbonates within which these minerals arc emplaced. He concluded that the mineral strontium my have been very locally derived, from the carbonate hosts.

Jan 1, 1979

By Anthony G. Fonseca

The acid leach-solvent extraction processing of oxide copper ores can be improved when selected cation additives are utilized. Bench scale testing showed improvements in both sulfuric acid leaching and solvent extraction processing. Treatment with the method to be described shows improvement in copper recovery in the acid leaching section as well as reduced acid consumption and reduced iron and aluminum dissolution. Processing the copper bearing leach solution with LIX-64N shows increased loading of the LIX reagent which relates to reduced aqueous and organic flow rates, reduced organic loss and inventory as well as a reduction in the size of mixer-settlers. The use of selected monovalent cations controls fluctuations within the pro- cessing system to accomplish the above named improvements. Additionally, these cations are totally compatible throughout the processing system and are quite inexpensive. Bench scale recycle data will be presented both for the leaching section and the continuous solvent extraction processing section up to (but not including) processing the loaded electrolyte. Material balances as well as major solution component monitoring will also be presented.

Jan 1, 1975

By E. Sabah

A series of adsorption tests are carried out to understand the ability of cationic surfactants and metal ions to adsorb onto sepiolite. Adsorption tests conducted as a function of heat treatment reveal that sepiolite is rather conducive to the uptake of both organic and inorganic ions. An ion exchange mechanism between surfactant or metal cation and magnesium ion followed by chain-chain association is proposed to explain the incorporation of cationic surfactants into the structure of sepiolite.

Jan 1, 1998

By Ruckmick J. C.

Elemental sulphur occurrences are widely distributed in two geological environments: -1-Basins containing hydrocarbons and zones of Cenozoic vulcanism. However, very few of these constitute deposits large enough to be of commercial importance. Almost all of the elemental sulphur mined in the world comes from bioepigenetic deposits in petroliferous basins. These deposits occur in two general structural styles: diapiric (salt domes) and stratiform. Examples of diapiric deposits occur in the Gulf Coast basins of Texas, Louisiana, and southern Mexico. Examples of stratiform deposits occur in the Fergana and Amudarya depressions of Central Asia, the Mesopotamian Depression in Iraq, the Cis-Carpathian Trough in Poland and Russia, and the Permian Basin in Texas. Economic bioepigenetic sulphur deposits range in size from approximately 1 million tons of sulphur in the smaller salt dome deposits to more than ZOO million tons of sulphur at the Mishraq stratiform deposit in Iraq. Total world production from bioepigenetic deposits amounts to approximately 16 million tons of sulphur per year, one-half of the world's present annual consumption of elemental sulphur. Most of the balance of the annual consumption is recovered from sour gas and petroleum. All bioepigenetic sulphur deposits share remarkably similar origins and characteristics. They are formed by anaerobic bacterial replacement of gypsum or anhydrite in tilted basins where evaporite beds are underlain by petroleum. Figure 1 illustrates a generalized cross-section of a salt dome sulphur deposit. Figures Z, 3, and 4 are cross-sections of three types of stratiform sulphur deposits. In terms of sulphur genesis, the only significant difference between the salt dome and stratiform deposits is that the positioning of the anhydrites above the petroleum in the salt domes is caused by diapiric rather than sedimentary processes. In the salt domes, the residual anhydrites of the cap-rocks are accumulated by solution and removal of halite by artesian ground waters.

Jan 1, 1978

By G. E. Wasson

Consolidation Coal Co. tested the agglomeration of fine coal using a laboratory pellet mill. The principal operating variables examined were feed coal moisture, coal size distribution, and additives to the feed coal. The moisture of the feed coal was found to be critical to both the pellet mill operability and the product strength. Coals, with feed moistures too high to pelletize, could be pelletized if mixed with lime or a water absorbent material. The addition of dry starch binder improved the product strength.

Jan 1, 1991

By H. Wen, X. Zhai

"The Jurassic coal fields which lay in west China are the major energy base and contain half of coal resources in China. Due to the gather and degeneration rules, the spontaneous combustion characteristic of Jurassic coal is distinguished with permo-carboniferous coal, which needs to be studied deeply. Programmed heating experiments of five Jurassic coal samples and three permo-carboniferous coal samples from different primal coal fields in West China were conducted to identify the characteristic parameters in the low temperature stage of oxidation and spontaneous combustion. The experiments were carried out under non-isothermal heating conditions up to 180? at the heating rate of 0.33?/min in an air atmosphere. The result showed that oxygen consumption rate, CO gas production rate and heating intensity of all coal samples increased with the rising of the temperature, which of the Jurassic coal was higher than that of Permian-carboniferous coal. The C2H4 gas of Jurassic coal generated earlier, more than that of Permian-carboniferous coal in the process of oxidation and spontaneous combustion. It indicated that the Jurassic coal was easier to be oxidized and spontaneous combustion and the index parameters of spontaneous combustion were different between the Jurassic coal and permo-carboniferous coal.INTRODUCTION Coal was the foundation of industry development, and occupied 70% of primary energy production and consumption structure in China. According to the data of the 3rd coalfield prediction, 39.6% of the total coal resources were located in northwest Jurassic coal field in China [1], where the quality of coal was excellent. The study of northwest Jurassic coal already dated from the 80s of the 20th century, about coal rock composition, coal metamorphism [2], coal-derived hydrocarbons, coal structure [3], etc. The results of these studies showed that the composition and properties of Jurassic coal was obviously different from Permian-carboniferous coal, as well as the characteristic of spontaneous combustion [4]. As a result, the spontaneous combustion characteristic of Jurassic coal particularly needed to be studied. Now more and more methods could be conducted to test the characteristics of coal spontaneous combustion, for example, thermal analysis technology [5-7], programmed heating experiment [8-10] and coal spontaneous combustion experiment [11,12]. In these methods, programmed heating experiment could be conducted to determine the oxygen consumption rate, CO gas production rate and heating intensity quickly."

Jan 1, 2015