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By Qian (Ken) Liu, Remi Proulx

A large scale blast damage project was carried out over the past two years at INCO Ltd Manitoba Division co-funded by the Canada/Manitoba Mineral Development Agreement. The experiment was conducted at the T-3 Mine in two mining stopes with an experimental drift developed in the hanging-wall for the installation of monitoring instrumentation. The objective was to observe and subsequently to reduce ore dilution by monitoring the performance of blasts, the hanging wall movement, as well as the cavity of the open stopes.

Jan 1, 1995

The epizonal Ag-Pb-Zn vein deposit at San Bartolome is characterised by a base-metal sulphide assemblage containing the spectacular development of interpenetrating, bladed networks of pyrrhotite which have been replaced by marcasite and pyrite. A similar assemblage displaying the same crystal habits and textures are also a diagnostic feature of the Sn and SnAg deposits ofBolivia. On this basis, it is reasonable to conclude that both deposits were formed from fluids of similar nature and origin. Although no economic accumulation of Sn is known in San Bartolome, further comparison of the geologic setting, age, mineralogy, fluid inclusion data and magmatic association of this deposit with the Bolivian systems has highlighted additional similarities consistent with a hypothesis that more extensive Sn mineralisation might exist in the San Bartolome area.

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 C G. Ryan, T P. Mernagh, S R. Hunns, R A. Both, R R. Large, J B. Gemmell

 The Hellyer and Mt. Chalmers deposits are mound-style volcanic-hosted massive sulphide (VHMS) deposits in Australia. Textural, petrographic and microthennometric investigations of fluid inclusions in the Hellyer stringer system indicate that Type I, primary, liquid-vapour inclusions are 10 - 15 J.UIl in size, and yield homogenisation temperatures of 170 - 220¦C in early 2A veins, 165 - 322¦C in main-stage 2B veins and 190 - 256¦C in late-stage 2C veins. These data suggest a waxing and waning thermal history. However, the average salinity remained between 8 - 11 NaCl equiv. wt % in all Stage 2 veins. At Mt Chalmers, Type I inclusions up to 20 urn are found in quartz from the mineralised zone, and these inclusions yielded homogenisation temperatures of 160 - 268¦C and salinities of 5 - 8 NaCl equiv. wt %. Laser Raman spectroscopic (LRS) analysis indicates the presence of CO2 (<1 mole %) in the Hellyer and Mt. Chalmers VHMS systems. Semi-quantitative SEM/WDS microprobe analyses of fluid inclusion decrepitates indicate that the Hellyer and Mt Chalmers ore fluids were enriched in potassium and calcium but depleted in magnesium relative to seawater. PIXE microanalysis of fluid inclusions in quartz also indicates a significant base metal concentration in these fluids. Cation composition and higher salinities relative to seawater suggest that recycled seawater alone cannot be the sole source of the ore fluids. High base metal content and the presence of CO2 in the fluid inclusions imply that magmatic input of ore metals during seawater leaching of the footwall volcanic pile is a distinct possibility.

Jan 1, 1995

By M. T. Ityokumbul

Flotation columns and their variations are increasingly replacing conventional cells in mineral processing circuitry. While the operational characteristics of columns differ from those of conventional cells, the same scale-up methodologies are being employed in design. This practice may be attributed to poor understanding of the factors controlling throughput. The use of tall flotation columns is frequently justified on the requirement for increased particle residence time. It is shown that longer particle residence times in the column cell alone do not translate into increased recoveries. Throughput data from several industrial flotation column installations is presented. An attempt at using dimensional analysis to provide scale-up methodology for the factors controlling column throughput is made.

Jan 1, 1995

By G. F. Revey

Most commercial explosives contain 70 to 94% ammonium nitrate, by weight. When portions of these explosives end up in shot rock and ore, through spillage or incomplete detonation, ammonia and nitrates leach out of them and into ground water. In recent years, State and Federal regulators have been applying more stringent water quality standards, particularly at new mines and development projects. Bulk ANFO, a mixture of ammonium nitrate and fuel oil, is the explosive of choice at most mines, when mining conditions allow it. ANFO use is desired because it less costly than other explosives, but when spilled it dissolves readily in water. Several case histories in the United States and Canada show a clear connection between uncontrolled losses of bulk explosives and high nitrate levels in mine effluents. Mining companies have tried several approaches to reduce ammonia and nitrate levels in groundwater. They either control explosive losses, or they treat mine effluents at the end-of-pipe. This paper addresses the former solution --controlling explosive losses. For both packaged and bulk explosives, guidelines designed to limit losses during storage, handling and use, are described in detail.

Jan 1, 1995

By Cathleen J. Webb, Arden D. Davis

Begun in 1992, an abandoned and inactive mine inventory in the Black Hills National Forest has resulted in a hazard ranking of the most severely affected sites. For purposes of the inventory, the Black Hills were divided into three main regions: the northern Black Hills, with primarily gold mines; the central Black Hills, with pegmatite mines and some gold mines; and the southern Black Hills, with primarily uranium mines. A computerized data base has been developed along with standard forms for field crews. The forms were designed to provide maximum compatibility with other abandoned mine inventories on various federal and state lands. Measures recommended for the most hazardous and heavily affected sites include regrading of unstable slopes, fencing of open shafts, and remediation of the most severe acidic mine drainage problems. Specific examples are illustrated where remediation and safety measures were recommended or have been implemented. The vast majority of the sites, however, needed little or no remedial action.

Jan 1, 1995

By Michael E. Stout

The recovery of the constituent components of spent lead acid batteries was pioneered in the early 1970's by M.A. Industries, Inc. MA's main reason for research and development in this area was to recover the polypropylene casings for use as feed stock in their injection molding plants. At that time spent and reject casings were either disposed of or being fed with the lead 'bearing materials into the ,smelting process. M.A. has since developed, built and operated plant for the conversion of scrap casing into reusable copolymer resins. The system is composed, of washing, .sizing, extrusion and pelletizing the polymer into a form which is ready to be injection molded into new products.

Jan 1, 1995

By Kal V. S. Sastry

Mathematical and expert system models are being used extensively for mineral process engineering; nevertheless, standardized methodologies for their computer implementation do not exist. In meeting this need, this paper introduces the concept of a process software model, or more specifically an object-oriented software model, and presents a detailed methodology for its development involving software model specification and development. These software models provide a formal basis for the subsequent design and construction of software objects corresponding to the real world process objects.

Jan 1, 1995

By John Campbell, William Trahant

"Total Quality Management (TQM) is becoming a reality in the mining industry. Widely adopted in the manufacturing and services industries, TQM has become the operating style of choice in numerous mining companies across the Americas and Australia. Iron Ore Company of Canada, Inco, MSA, Graniterock, Magma Copper, and CRA's Hamersly Iron - all are pioneers of TQM. These companies and others are confronting the challenges of implementing TQM and are managing the changes required of their people and cultures. What these companies are doing, why they are doing it, and how they are successfully managing the changes are the subjects of this paper.Driving the need for change in these organizations are a host of issues, some of which all mining companies are facing. Requirements from customers for ISO 9000 certification is becoming one of the initial motivators for Total Quality Management. These standards, commonly used in manufacturing throughout the European Community (EC), emphasize quality in the processes that create outputs, instead of just the outputs themselves. Iron Ore Company of Canada, for instance, responding to the requirement of one of its customers, British Steel, has become one of the first mining companies to meet the quality standard. Suppliers who meet the standards are highly desirable to customers who are themselves operating under the ISO or their national quality guidelines."

Jan 1, 1995

By G. F. Archer

Selenium and tellurium, trace metals found in copper smelting, report to blister copper during smelting. Winning these metals from anode slimes, the primary commercial source, is discussed. At Asarco's Amarillo Copper Refinery, slimes treatment segregates selenium and tellurium to a water-soluble soda slag. Aqueous precipitation of tellurium oxide and selenium by sulfur dioxide is valence dependent. Se+6 and Te+6, which constitute a portion of total selenium and tellurium, are not susceptible to this base case treatment. "Secondary Selenium" is formed from these hexavalent species. We describe a process whereby simultaneous oxidation of selenium and tellurium effects a separation. Process conditions for separating selenium dioxide, and efficiency of fume capture are examined.

Jan 1, 1995

By J. E. Urosek

The Mine safety and Health Administration (MSHA) formed the Mine Ventilation Bleeder and Gob Training Committee in 1993. This committee was charged with developing a training course designed to enhance the knowledge and understanding of practical bleeder ventilation systems. The course will probably include a discussion on the theory behind bleeder system design, an in-depth look at the strengths and weaknesses of the basic bleeder system types, case studies, and a review of the systems currently in use. A database on active underground bituminous coal mines, gob areas, and the bleeder systems presently used was developed from questionnaires distributed to nine Coal Mine Safety and Health (CMS&H) districts. Representative systems were selected for thorough investigation to develop case studies. This paper introduces some of the material to be included in the course, including a description of basic bleeder system designs, a review of a portion of the database, and facts about the gob areas and bleeder systems investigated for the development of case studies.

Jan 1, 1995

The mining industry is facing tremendous economic challenges. Fluctuating and depressed commodity prices, the ever-increasing pressure from environmental legislation and the competing global opportunities for capital investment are placing enormous strains on every aspect of the mining business. At the same time, mines are generally becoming older and deeper with all the logistical and rock mechanics difficulties that this entails. In the face of these new challenges the industry looks to technological advances to make operations more efficient and profitable. One approach is to develop and implement highly automated and computerised equipment as part of a trend towards major reductions in the underground workforce. This approach requires more capital investment rather than less and requires a more sophisticated and well-educated workforce with skills which are generally in high demand in society as a whole. It is difficult to see how the benefit that can be gained from such technology can justify the expenditures necessary to make it operate reliably underground on a daily basis. Nor is it easy to foresee how the mining industry, based as it is often in very remote areas, will be able to hire and retain sufficient numbers of people to maintain such fleets of equipment. Another approach, and the one which I favour, is the implementation of much greater control over the whole of the mining process. Mining is essentially a very simple process - we break rock and move it. The most cost-effective means of moving and processing the mining product depends entirely on the way it is broken - it depends on primary fragmentation by blasting. I propose that the way forward for the industry in the face of our present difficulties, is not new technology but is to utilise the level of technology which currently exists in ways which have traditionally been regarded as too difficult or too inflexible - improved fragmentation and the use of conveyors. The technical success of this approach depends on the complete re-design of the ore handling system from the face or stope drawpoint to surface. The fundamental issue which determines the success of this approach is designed fragmentation.

Jan 1, 1995

By I. K. Gilmore

Texasgulf Inc. currently operates an open pit phosphate mine in the central coastal plain of North Carolina. The area of phosphate deposition lies within the Aurora Phosphate district which consists of an embayment which is in the center of the Neogene phosphate deposition. A variety of solid and liquid fertilizer products are produced at the Texasgulf complex. One of these products is known as North Carolina Natural Phosphate (NCNP). New potential for use of unacidulated natural phosphate, now exists in regions with acid soils due to the discovery of the findings from recent research, cost advantages, and moves to reduce chemical inputs.

Jan 1, 1995

By Fulton B, Stewart R, Leach T

Gold mineralisation at Porgera is inferred to have been derived from a deep differentiated magmatic source which is capped by a series of (now tilted) inward dipping sills and stocks, which comprise the Porgera Intrusive Complex. An arc normal transfer structure provides a conduit, at the intersection with an arc parallel structure, into which basic magma derived from the deep melting of mantle material has been emplaced. Two phases of mineralisation display an association with late stage feldspar porphyry intrusives. Stage I carbonate-base metal-style gold mineralisation occurs as early quartz-sericite, then massive sulphide and late zoned Mn-Fe-Mg-Ca carbonate vein/breccias. Magmatic fluids derived from the deep magma source, are interpreted to have migrated along the margin of a feeder stock to the sills, and south to Waruwari. Stage II epithermal Au-Ag quartz-style gold mineralisation occurs as early fluidised breccias and carbonate veining, followed by zoned quartz-roscoelite-carbonate-gold vein/breccias, and late carbonate and/or sulphate open space infill. Magmatic fluids are interpreted to have utilised the same plumbing system as the late stage feldspar porphyry intrusive, and then migrated into the Roamane Fault which was dilated by; dextral rotation on elements of the transfer structure, normal faulting, and refraction around the competent footwall hornblende diorite. Bonanza gold is localised in a jog in the Roamane Fault, hangingwall splits and at intersections with cross structures. Bulk low grade Stage I gold has been deposited by the mixing of magmatic fluids with cool gas condensate waters, whereas high grade Stage II gold mineralisation resulted from the rapid quenching of mineralised magmatic fluids by oxygenated groundwaters.

Jan 1, 1995

By Wilfrid Comeau

While researching for a theme lecture (Comeau, 1993l) on: 'The Mechanics and Physics Explosives', the author of Energy Transfer in Rock Fragmentaion by was confronted with many conflicting concepts regarding: the current explosive rock fragmentation theories, the physical principles governing energy transfers, the mechanical properties of rocks, and observations and data from full scale rock blasting.

Jan 1, 1995

By P. O. Lindahl

The U.S. Bureau of Mines initiated research to improve the safety and efficiency of transporting coal from deep underground mines using a balanced air-lift hydrohoist. A 50-m-high pilot-scale model was constructed and tested to evaluate the feasibility of hydraulically hoisting a coal-water slurry in a U-tube pipeline from the mine level to the surface with the assistance of compressed air. A prototype screw feeder is used to continuously compact and inject 5-cm or less run-of-mine coal into a pressurized 20-cm-diam pipeline. Production rates up to 40 metric tph at an airflow of 1.5 m3/min were achieved with the model, and coal size degradation was relatively minor. Modifications are in progress to achieve 100 tph at an airflow of 2.8 standard m3/min injected into the riser pipe. Pilot-scale results indicate that an air-lift hydrohoist system is a feasible, cost-effective alternative to conventional skip hoisting that can be installed in existing shafts or surface-drilled holes closer to the face area. Air-lift hydrohoisting offers advantages of infinitely adjustable slurry flow rates, reduced pressure at the point of coal injection, and flexible design that can be combined with hydraulic pumping. Proposed design changes are discussed for coal transport, mine layouts, ventilation, fire control, and escapeways using this system.

Jan 1, 1995

The Hishikari gold deposit, discovered by the Metal Mining Agency of Japan, has become a giant class epithermal gold deposit with the highest grade of gold yet recorded in the world through detailed exploration and development by the Sumitomo Metal Mining Co Ltd. The exploration strategy involved a regional approach combining geological and gravity surveys over a 900 km2 area which had historically produced over 120 t of gold. These surveys were carried out to grasp the common geologic features of epithermal gold deposits in the survey area. A genetic model for epithermal gold deposits in the area under regional survey was also considered based on detailed research of the Kushikino epithermal gold deposit which was in operation at that time. This model was applied to the targeted areas, and important relationships between mineralisation, host lithology, intensive propylitic alteration and gravity highs became apparent. The Hishikari block was selected in this way and bonanza gold was discovered during drilling. Since the development of the Hishikari mine, information useful for further exploration for the same type of deposit has been accumulated.

Jan 1, 1995

By Milawarma E, Cusack C

The Sapan Dalam coal deposit of Indonesia consists of ten steeply dipping seams with thicknesses varying between 0.1 and 3.5 m and split by shale, clay, silt and sandstone. The area contains four faults dipping about 75¦ with four to 85 m vertical displacements. The complex nature of the deposit coupled with limited 27 exploration drillholes at an average spacing of 200 m made it difficult to create a realistic geological model. A three-dimensional gridded seam model gave a fair representation of the deposit. Attempt to create an optimum pit using the WHITTLE 3D pit optimiser proved unsuccessful since the pit optimiser is restricted to standard regular or fixed blocks. The gridded seam model was converted to a fixed block model prior to the optimum pit design. Smoothing and pit base controlling were also introduced to obtain a smoother pit. A mining scenario produced 3.6 million tonnes of coal, 28.4 million bcm of waste and US$18.1 million revenue.

Jan 1, 1995

By K Palmer, G J. Artmont

Alluvial gold is an ideal exploration tracer to bedrock source and indicator of bedrock mineralisation style because: (i) gold occurs in a wide range of deposit types, (ii) primary composition is sensitive to style of mineralisation, and (iii) it is a heavy resistate mineral that is readily preserved and easily sampled. In regional exploration of the Central Ranges of Irian Jaya, alluvial gold mineralogy has been applied to maximise the information return from panned concentrate sampling and to focus exploration effort. Primary gold is a solid solution of Au+Ag¦Cu¦Hg, ¦ trace Pd, Te, and Sb. In general Ag¦Hg increase and Cu decreases with inferred decreasing temperature of formation, and gold from particular mineralisation styles has signature compositions that can be used as indicators of bedrock mineralisation type. Furthermore, the abundance of alluvial gold is an indicator of the economic potential of a catchment. The convergent continental-oceanic plate geology of the Central Ranges is conducive to a wide range of mineralisation styles. Mineralogy of gold in ophiolite, skarn, porphyry, mesothermal vein and possible VHMS environments is characterised from alluvial and bedrock samples, and the use of gold mineralogy in prospecting at regional scale through prospect definition to drilling is demonstrated.

Jan 1, 1995