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Economic and environmental pressures are shifting the world balance of titanium dioxide production away from sulphate based. manufacture towards the more cost effective and cleaner chloride route. In the chloride process for titanium dioxide pigment manufacture, TiOz and other metal oxides in the feed ore are reacted at high temperature with chlorine in the presence of carbon. These gases are cooled after they leave the reaction zone, upon which solid contaminants precipitate and are substantially removed. The liquid titanium tetrachloride is purified by distillation before again being vaporised and interacting with hot oxygen to form pigmentary titanium dioxide and regenerate chlorine for recycle. The base pigment is wet milled, surface treated (by coating with hydrous oxides of silica, alumina and others) and redispersed before packaging. Optical properties of TiO2 pigments are reviewed and the role of refractive index and particle size explained in brief. Pigment related factors affecting the opacity, colour, undertone, gloss and durability of coatings are examined with respect to manufacturing requirements. The superior performance of chloride based pigments is briefly reviewed.

Jan 1, 1991

By Donovan F. Symonds

INTRODUCTION The selection of the optimum coal preparation plant flowsheet is a vital part of the development of a new plant or the expansion of an existing facility. Selection of an inappropriate flowsheet or individual equipment items can result in costly production losses, or needless expenditures or redundant or oversized equipment. The accuracy of the flowsheet selection process is, like most decisions, heavily dependent upon the amount, reliability, and quality of the database. A flowsheet which is based on simple borehole information from an area that has experienced little or no previous mining activity must necessarily include significant allowances for uncertainties. However, a plant which is to be built at an existing mine with good information on run-of-mine (ROM) coal quality, as well as bulk washability data and accurate projections of future quality, can be optimized. The following chapter will describe the processes which should be followed to select the most appropriate flowsheet for each unique operation. They include: 1. Examining and adjusting the washability database to reflect the ROM feed. 2. An evaluation of clean coal specifications. 3. Selection of the level of washing required. This includes no washing, if the coal is already at the desired specification, all the way through to complex total washing circuits for metallurgical grade coals. 4. Selection of the appropriate circuit such as dense medium bath vs. Baum jig. The most appropriate circuit is generally determined on the basis of economics. An approach for performing the evaluation will be desired. 5. The steps that need to be followed to develop a balanced plant flowsheet. ADJUSTING WASHABILITY DATA It is not unusual to have as many as 10 to 20 sets of washability information available for a particular mining property. These may be a combination of core and bulk samples or all bulk samples. In the latter case, they may also be face and/or ROM samples. It is necessary to reduce all of this information to a single set of washability data that is representative of the mean feed to the proposed preparation plant. This set is used to compare the clean coal yield and quality characteristics of the various flowsheet options. The term "representative" has some serious negative connotations. It is recognized that ROM coal quality will vary throughout a mine. However, over a period of 250 to 350 days per year, certain trends can be established. If possible, this "representative" sample should be close to the coal quality of the mean daily sample in terms of raw ash and sulfur contents, clean coal yield, and clean coal ash and sulfur content. If possible, this sample should be within the

Jan 1, 1991

By Dorothy B. Niell, O&apos

In its first three years of operations, the in-house programs of the continental Shelf Division of the Marine Minerals Technology Center (MMTC/CSD) have focused on the development of drill systems - technology and the improvement of techniques and applications of reconnaissance methods to marine mineral deposit characterization. Many of the technological advances made to date have been in direct response to specific requests from industry for drill systems needs, and from federal and state agencies seeking technical support for various research efforts. These cooperative programs have proven to be an extremely efficient and effective way for the MMTC to achieve some of the main program goals that were established for the organization at the outset: primarily, to encourage and assist U.S. industry in marine minerals research activities and to encourage cooperative work among research institutions, government agencies, and industry. The primary achievements of the MMTC/CSD to date include the development of the Remote Placer Drill System for rapid reconnaissance drilling of precious metal placer deposits (including both pneumatic prototype and hydraulic production

Jan 1, 1991

By R. Cotton

"1. INTRODUCTIONTo say that the environment will be a dominant issue in the 1990' s is an understatement. A world-wide ""green revolution"" is taking place not only with the general public and politicians, but in the boardrooms and plant facilities of corporations around the world. There is probably not a plant manager who has not been requested by his corporation to assist in some way on environmental issues by providing advice and strategy, by dealing with customer or community concerns, by considering environmental matters in transactions, by developing new environmental compliance policies and requirements, and so on.There are, in the author's view, three main challenges for the mining industry in the environmental area in the 1990's. This paper will discuss each in turn. The first challenge is the concept of ""sustainable development"". Whatever the meaning of this much-debated phrase, we are rapidly moving beyond the buzzword, and into the specifics. It will clearly impact on the way we manage our companies, our communities and our personal lives.The second is the challenge of personal liability; particularly for officers, directors, supervisors and managers of the corporation. For example, in Ontario today, a good percentage of prosecutions for pollution offences are against individuals, usually managers and supervisors, in addition to the prosecutions against the corporation itself for the same offence. In all likelihood, prosecutions will increase in number and will increasingly be directed at individuals. A corporate president has already served a jail term for contempt of court related to his corporation's breach of a court order related to sewer by-law offences. Although the case is on appeal, another president has become the first officer in Canada to be sentenced to jail for violation of an environmental protection statute. Other corporate officers and directors have recently been charged with breach of their duty under Ontario's Environmental Protection Act."

Jan 1, 1991

By Vitaly T. Borisovich

Mining economics courses have been taught in Europe for more than two centuries and in the United States for most of this century. They are the mineral industry's version of engineering economics offered by industrial engineering departments. In the 1930s, mineral economics first appeared in American mining schools. This subject goes beyond the deposit and the mine. It examines the economic aspects of mineral resources in general and the individual mineral industries in particular. In 1947, the first degrees in mineral economics were granted in the United States. There are mining and geological engineers who specialize in mining economics. But it has rarely become a separate degree program. Rather, in this country and several others, a graduate student in a mining department or school will include economics in his course work. Then the person writes a thesis or dissertation on a mining economics topic. One exception is found in Moscow at the Department of Geoeconomics of the Moscow Geological and Prospecting Institute (MGPI). To place this program in perspective, some background is needed on education in the Soviet Union.

Jan 1, 1991

The theory of declining optimimum cut-off grades is more than 25 years old, but for a number of reasons it is still not widely used in industry. A lack of faith in the veracity of estimated grades is not in itself a reason to abandon any attempt to optimise cut-off grades. The use of declining cut-off grades has been thought to cause high-grading, but in fact this is only true if an artificially high discount rate is used in the calculations. Perfect application of an optimum cut-off grade should ensure that only ore generating more than a minimum net return is mined, and that as much as possible of the ore capable of generating that return is mined. Therefore differing mining costs in different parts of some underground mines necessitate local modifications to cut-off grade. Optimisation of cut-off grade is of necessity an iterative process. Integration of that process into a feasibility study need not be excessively time-consuming. A number of approximations can be made to speed the optimisation (any attempt to achieve a high level of accuracy is probably doomed to failure by a lack of precise cost and price projections). A procedure is outlined for optimising cut-off grade during planning of a typical underground mine.

Jan 1, 1991

By C. A. Young

Previous experimental results have shown that an increase in temperature and/or oxygen concentration leads to an increase in the hydrophobicity of fluorite (CaF2) with adsorbed oleate. Subsequently, ex-situ Fourier transform infrared (FT-IR) transmission studies suggested that this increase in hydrophobicity was the result of double-bond reactions between adjacent oleate species adsorbed at the fluorite surface. Now an in-situ FT-IR study on single crystals of fluorite has been used to monitor this phenomenon using internal reflection spectroscopy (IRS) with the crystals serving as reactive internal reflection elements. The double-bond reaction has been correlated with in-situ adsorption density measurements. These results demonstrate that only the first chemisorbed oleate layer undergoes the double-bond reaction at an appreciable rate. However, multilayers of precipitated calcium oleate in the case of fluorite appear to react minimally even for oxygen saturated solutions at elevated temperatures.

Jan 1, 1991

By Herbert Pöllmann

Waste disposals are needed for safe deposition of different kinds of materials which can not be used as secondary raw materials. Often high contents of heavy metals must be bonded tightly to cristalline compounds to protect the environment from contamination. Therefore it is important. to find minerals which are capable to incorporate different heavy metals and protect the ground water. The power of resistance against leaching out effects of highly water-soluble salts can be increased. Mineral groups of metal hydroxy salts, ettringites, apatites, sodalites and calciumchlorosilicates and their hydrates are recommended for their formation in mineral reservoirs. Different wastes as red mud, gasification ash, garbage combustion ash and fluidized bed ashes were included in this study. The formation of different new compounds and their properties were determined.

Jan 1, 1991

By Yoshio Masuda

Cobalt-rich crust in rich Co, Ni, Mm and Pt will be a potential resources for island country such as Republic. Marshall Islands. This study was conducted for Marshall Islands by the President Kabua?s request. It covers crust resources, CLB mining, processing, and economic estimation, and study concluded feasible veiw.

Jan 1, 1991

By Quilliam B, Richmond G

Aberfoyle Ltd. has utilised a variety of flotation technologies in the Hellyer concentrator in North-Western Tasmania. Hellyer ore, with its slow flotation rates and low rate differentials between values and gangue, requires the use of long residence times and low air consumption rates in the flotation circuit. The operation of the flotation circuit, with a nominal residence time of 7 hours, has necessitated the development of a control system to provide continuity through operator shift changes. Cell selections at Hellyer varied from the 54 m3 hybrid Dorf Oliver / Maxwell (DO/MX) cells, to smaller 32 m3 Maxwell cells, conventional Don-Oliver 300 (8.5 m3) and 600 (17 m3) trough cells, and a column cell. The advantages of the large cells included low specific power consumptions and a low capital cost. However, problems with mixing and the maintenance of consistent froth depth have been identified in the hybrid DO/MX cells. Short circuiting in the trough cells was apparent, causing a considerable reduction in metallurgical performance. The column cell performs to expectation, although the application is not ideal.

Jan 1, 1991

By R. K. Mehta

An electrochemical coal oxidation model involving heterogeneous kinetics is presented. This model was tested by collecting current transient data on three coals assaying different ash content under varying operating conditions such as particle size, temperature, and % solids. In all cases, the model fitted the data very satisfactorily. Three intrinsic rate constants, namely mass transfer coefficient of Fe(II) Ions diffusing from solution to the anode (kma), mass transfer coefficient of Fe(II) Ions diffusing from solution to the coal surface (kmc), and chemical rate constant for coal oxidation with respect to Fe(III) at coal surface (k), were calculated. It was interesting to note that in this system, the mass transfer at anode was as important as the chemical reaction at the coal surface. The validity of this model was further demonstrated through a comparison of the activation energy of coal oxidation: firstly, by utilizing calculated chemical rate constant and assuming Arrhenius' type of relationship: secondly, by utilizing conventional approach using limiting current values. The comparison revealed that agreement was quite close. This kinetic analysis is useful because such a model can be used in predicting the intrinsic rate constants so that the relative importance of mass transport can be rationally analyzed.

Jan 1, 1991

By R. D. Hamilton, W. J. Miles

In 1987, the International Agency for Research on Cancer designated crystalline silica as a 2A probable carcinogen. As a result, crystalline silica is regulated under the Hazard Communication Standard as a probable carcinogen at a concentration of 0.1% or greater in the workplace. Crystalline silica will be listed as "reasonably anticipated to be a carcinogen" by the National Toxicological Program. This designation of crystalline silica as a probable carcinogen has created major issues for the mineral and chemical producer, including labeling, hazard communications, marketing a material with potential hazard exposure, and potential liability. The State of California also regulates crystalline silica under Proposition 65 in products as a carcinogen, based upon the IARC determination that it is a probable carcinogen. More federal and state regulations are anticipated as a result of the IARC classification of crystalline silica and its subsequent federal regulation. Respirable crystalline silica has been regulated as a hazardous dust for many years by OSHA. This regulation was initiated to prevent silicosis, another occupational disease. OSHA has established monitoring devices for determining the concentration of airborne respirable silica in order to measure exposure to this substance. The accurate determination of the crystalline silica content is critical to dealing with these health risks and regulations. In the past, crystalline silica was considered to be safe and, because of its ubiquitous nature, little effort was made to determine or quantify its presence in most materials. The Hazard Communication Standard requires that a1l products containing 0.1% or greater crystalline silica must be properly labeled for this material and its hazard. Unfortunately, the 0.1% threshold was not chosen on the basis of established analytical capabilities for crystalline silica, but results from general limits for potentially carcinogenic chemicals and substances. Numerous methods have been developed for the determination of crystalline silica in a variety of products. However, these methods are not generally applicable since they must be specific for silica in any of its crystalline states and not just for total silica content. Chemical tests for silica are not difficult and quite accurate at the 0.1% level; however, in addition to its crystalline phases, it occurs in amorphous phases and in a wide variety of crystalline and amorphous silicates. In general, there is little correlation between total silica content and crystalline silica.

Jan 1, 1991

By A. J. Basu

An overview of the evolution of computerized mine planning and design has been given, emphasizing the need for a knowledge-based system for planning and design of underground coal mines. An outline for the development methodology and procedure has been provided. Problem structuring guidelines have been used to incorporate intelligence and integration to the design modules. A skeletal model for a mine planning and design expert system has been prescribed, and the development process has been documented in detail. A feasibility prototype has been developed to test the structure of the skeletal model and to ensure completeness of the design process. The feasibility prototype development and its contribution toward proto typing has been addressed in this paper. At present, prototype development is underway. The prototype is expected to be avail-able for testing and implementation in early 1991.

Jan 1, 1991

By E. H. R. Schümann, H. Wagner

SYNOPSIS The paper gives a detailed overview of the history of subsidence engineering on South African collieries. Surface displacements resulting from total-seam extraction are discussed, and the important role of local geology is highlighted. It is shown that the differences in subsidence behaviour between South African and European collieries can be attributed to the presence of competent strata in the overburden of South African coal seams. Criteria are given for the prediction of the most important subsidence parameters, and a new model for the simulation of surface subsidence above total-extraction panels is introduced. The final section of the paper deals with the damage to surface structures caused by total-seam extraction. A brief summary of the most important undermining experiments on South African collieries is given, and it is concluded that local experiences of damage compare with those in Europe.

Jan 1, 1991

By Veneta Groudeva

A pyritic ore containing zinc, lead and copper as? the relevant primary sulfide minerals, .as well as gold and silver finely disseminated in the sulfide matrix, was? leached in percolation columns. Each column contained 30 kg of ore crushed to minus 10 mm. Firstly, zinc and copper were efficiently leached by means of chemolithothrophic bacteria? in acidic sulfate bearing medium. Zinc was leached more rapidly than copper but the final extractions of these metals were similar (about 75% in 300 days). A part of the galena was oxidized to the. insoluble lead sulfate during the leaching. The pyr:ite was, however, relatively slightly attacked. The ore was then leached by means of FeC11 - HCl solutions both in the presence and in the absence of bacteria to solubilize the lead. The chemolithotrophic bacteria grew in media containing both chloride and sulfat~ ions and maintained a high ferric to ferrous ion ratio in the percoiating solutions. The chemical leaching was, however, more efficient since ft was possible to carry it out at higher chloride ion concentrations. About 10% of the lead was leached in this way in 90 days. Finally, the ore was leached by thiourea in the presence of a gold-oxidant (oxone) to extract the gold and silver. Over 60% of the gold and over 55% of the silver were extracted from the ore in 150 days, while. the extractions of these precious metals from an untreated ore sample were lower than 25%.

Jan 1, 1991

By Roger E. Burleigh

In June, 1989, the U.S. Bureau of Mines, undertook a 9-day evaluation of the tin resource potential of the Sleitat Mountain tin deposit. Significant tin-tungsten mineralization is associated with quartz-topaz-white mica-tourmaline greisen alteration of a multi-unit, 57 Ma, peraluminous, granite stock which intrudes Cretaceous Kuskokwim Group flysch deposits. The granite comprises marginal biotite-, intermediate biotite-muscovite-, and central zinnwaldite-granite units, interpreted as a zoned alteration system. Major vein mineralization is confined to two east-west-trending zones of steeply oriented tabular lenses of greisen interleaved with mildly altered granite. Cassiterite is the dominant ore mineral while arsenopyrite, loellingite, wolframite, pyrite, sphalerite, chalcopyrite, and bismuth-oxides are present in minor to trace amounts. The north and south greisen zones are estimated to contain an inferred resource of 128 to 212 million lbs Sn in 28.6 million st of mineralized rock. An 1,800-lb representative bulk sample contained 0.37% Sn, 0.04% W and 17 ppm Ag and is considered an average grade estimate for the deposit. Drill testing by Cominco Alaska Exploration indicates that substantial widths of high-grade tin mineralization are included within the lower grade disseminated mineralization. Depth of deposit erosion is substantial and there exists a high probability for placer tin deposits.

Jan 1, 1991

By Gary A. Halvorson

Plots were established on regraded abandoned mine spoil to determine if nearby good quality spoil could be used in place of topsoil for the reclamation of these sites. Gypsum, calcium chloride, and power plant ash were also tested to determine the effectiveness of these materials in reclaiming these sites. Two sites were selected on which very little vegetation was growing on highly sodic spoil material. Gypsum, calcium chloride, and ash were added to the spoil at a rate designed to reduce the (sodium adsorption ratio) SAR in the surface 15 cm to 10 or less. The good quality spoil (replacement soil) was then laid on the swface at rates of 0, 5 or 15 cm of material. The plots were seeded to a mixture of smooth bromegrass (Bromus enennis Leyss.), crested wheatgrass (Agropyron desertorum (Fisch. Ex Link) Schult.) and alfalfa (Medicago sativa L.). The addition of 5 or 15 cm of replacement spoil significantly improved vegetative growth on these sites. Chemical treatments had no effect on vegetative growth. Weathered ash showed no adverse effects on plant growth or soil properties.

Jan 1, 1991

A field trial of the prompt neutron-gamma SIROLOG technique was undertaken by the CSIRO - Division of Geomechanics at Callide Coalfields during July 1989. The trial investigated whether the sonde could reliably be used for the determination of Ash and Iron Oxide (Fe2O3) in coal seams, which had a highly variable iron content. Ten boreholes were logged, being water filled of a nominal diameter of 120 mm. The logging probe employed a 1.6 ¦g 252Cf neutron source and a 51 x 51 mm BGO detector. The source to detector distance was 15 cm. The results from one exploration borehole at the Dunn Creek Mine are discussed in the paper. The rms deviations for ash and iron determination between the neutron-capture predictions of the geophysical logs and the laboratory - chemical assays were 1.9 per cent Ash and 0.88 per cent Fe respectively. Using existing empirical equations which relate iron oxide concentration in coal ash to Initial Deformation Temperature (reducing conditions) at Callide, it may be possible to indirectly determine ash fusion properties as least as accurately, on a more detailed ply-by-ply basis, and more cost competitively than current laboratory techniques allow.

Jan 1, 1991

By F. D. Wang

This paper presents an innovative mining method with the application of the water jet. The basic principle of this mining method is to mine a thin panel slice with a water jet system and to allow the roof to deflect elastically and subsequently to be supported by the coal floor without artificial roof support. Through the sequential mining of layers from top to bottom, the entire seam is extracted and the roof rests upon the mine floor. The advantages of this method are that the safety of underground operation can be greatly increased and the surface overburden disturbance will be markedly reduced. . An economic evaluation of such a system is presented for the total cost estimated per ton of coal mined at the face. This evaluation is then compared to that of a continuous mining section utilizing a room and pillar mining method.

Jan 1, 1991

The patented "Epytensic" pump of Minnovation Ltd, a multiple piston pump, is used widely on shearer loaders and by partial high pressure watcr jet cutting strategically in relation to cutter picks not only improves cutting rates, but saves power and increases the life of gearboxes and picks, as well as improving dust suppression. The "Face Side Pump", also a piston pump, located on the ranging arm gearhead has advantages over gateroad pumps and shearer body pumps. The "Extraction Drum", hydraulic air mover system, linked with the above innovations and high pressure water, have further advantages in methane and dust removal. Some modifications providing these systems need workshop applications but most are possible underground with minimal changes to shearer profiles and advantages of minimising hosing, along with the other advantages stated.

Jan 1, 1991