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By F. Kapeller, G. Herget

"The need for monitoring the effect of changes in ground stresses due to mining in hard rock has existed for many years. The Mining Research Laboratories of CANMET, EMR have developed a new tool which monitors with high precision the radial deformation in boreholes. The result is the Mining Research Laboratories strain monitoring system (MSMS) which uses the highly stable and very sensitive vibrating wire principle to monitor deformations in relatively large boreholes, e.g. 76 mm to 153 mm diameter.The vibrating wire is strung across a relatively large proving ring and operates at a frequency between 600 to 1800 Hz. The read-out system is based on continuous vibration.The ring is installed with a hydraulic tool and brought into contact with the surrounding rock through precisely machined and guided wedges. The resolution of the system is in the neighbourhood of 4 x 10-4 min/ Hz. The data collection can be carried out with a portable read-out unit and provisions are available for automatic data collection. Stresses may be calculated from strain readings.The system was tested in cooperation with the Centre de recherches minérales at the Niobec Mine in Quebec for the purpose of monitoring the effects of drill drift development and slope mining on surrounding ground stresses.After access was available to the site, 153 mm diameter holes were drilled for the determination of in situ ground stresses. These holes were then used to install the strain monitoring system. The effect of drill drift development and production blasting in stopes C-203-13 and C-203-15 on ground stress distribution could be observed clearly.The horizontal relaxation in the core of a pillar which occurred during mining of adjacent rooms was between 0.082 mm to 0.111 mm. Calculations of stresses from these deformations indicate that the rock material is still in an elastic condition.Roctest of Montreal has obtained a license on the manufacturing and distribution rights. A patent has been registered and CANMET will assist in installation of the MRL strain monitoring system and the interpretation of records."

Jan 1, 1989

By R. W. Bartlett

A two step process for treating platinum group metal flotation concentrates Is described while experimental results. The process was designed to be simple and Inexpensive While yielding a high recovery and fast turnaround. Ii consists of electric furnace smelting of concentrate to remove gangue and produce a homogeneous sulfide matte containing all of the base metals and platinum group metals. Sulfide oxidation Is minimized during smelting to avoid Installing an acid plant In the second step, matte Is pressure-leached with oxygen In an acid sulfate system to dissolve Iron, nickel, ?and copper while leaving a residue highly concentrated In precious metals, and typically about 1% of the flotation concentrate mass, A batch process with oxygen titration against the base metal composition of the feed Is used to control the end point of the leach. Sulfides must be eliminated while minimizing the precipitation of hydrolysis products. The leach residue can be smelled to bullion to facilitate sampling accuracy.

Jan 1, 1989

By I. S. Parrish

Gold deposits in Hebei and Shanxi provinces in northeast China fall into three general classes: - Placer deposits - Mesothermal vein deposits - Disseminated and oxidized volcanogenic deposits Past production dating back thousands of years has all but exhausted the placers. The mesothermal vein deposits, incorrectly considered in the past as "greenstone" type, are small to moderate in both size and grade. Production from these granulite and amphibolite hosted veins, at present greater than from the newly discovered disseminated deposits, is expected to wane. Production from the disseminated deposits achieved only in the past few years is expected to equal or surpass that from the other classes of deposits. At least one "world-class" deposit is being developed.

Jan 1, 1989

By M. D. McInnis

The Jualin Gold Prospect is centered on Johnson Creek, approximately 40 air miles north-west of Juneau, Alaska. The property is on the southern end of the Kakuhan Range with Berners Bay immediately to the south and Lynn Canal to the west. The property is accessible directly by helicopter from Juneau or by float plane to the head of a 5.5 mile gravel road that begins on the north side of Berners Bay and terminates at the old workings of the Jualin Mine near the center of the property.

Jan 1, 1989

By J. Douglas Causey

In 1988, at the request of the Bureau of Land Management, the U.S. Bureau of Mines studied part of the 12,740-acre Blue Canyon Wilderness Study Area (OR-003-073) in order to evaluate its identified mineral resources. The study area is in Malheur County, OR, about 27 miles northwest of Jordan Valley. The study area is underlain by Tertiary welded tuff, tuff, perlite and tuffaceous sedimentary rocks capped by basalt. Jasper has been mined from several localities. Some mining has been done by hobbyists. However, the area has been covered by mining claims since 1964, with mining done by commercial operators. This region has been a source of "Owyhee picture" and other similar jaspers. More recent exploration has focused on the gold potential of nearby areas such as Quartz Mountain and Red Butte.

Jan 1, 1989

By S. M. I Kytö, J .. K. Mäkinen, K. Saarhelo

"At the Outokumpu Oy Harjavalta Copper Smelter the control philosophy of the flash smelting process has been changed from the slow feed-back control to feed-forward control. This is important as the fluctuations in the flash smelting furnace matte grade and slag temperature are desired to be minimized.The system is based on a specially designed automatic sampling device and the Outokumpu Courier 20 on-stream X-ray fluorescence analyzer. A microcomputer-based Analyzer Operator Station (AOP) controls the system and calculates the process parameters for the furnace from the analyzed chemical composition and other existing data.A considerable reduction in the deviation of the matte grade and slag temperature has been gained. This has resulted in conservation of energy and refractories, lower copper losses and higher through-put in the flash smelting furnace and converters.1.0 IntroductionThe flash smelting technology for copper concentrates was developed at the Outokumpu Oy Harjavalta Smelter soon after the World War II. The incentive for this development was shortness and high price of any form of energy. The fact that smelting can be carried out autogenously, without external energy by utilizing the latent heat of sulfide combustion was known decades before, but Outokumpu Oy was the first company to take the advantage of this knowledge in practical operation. A further advantage of this technology was that the SO2 containing gases suited well for sulfuric acid production, thus minimizing the detrimental effects on the environment (1).The very heart of the flash smelting process is the reaction shaft of the flash smelting furnace (see Appendix I). Heating up of the dried feed mixture, dissociation of several compounds, ignition and oxidation of the feed take place very intensively in the reaction shaft during 2 - 3 seconds, which the fine grained particles reside in the reaction shaft. A very accurate control of the amounts of the feed materials as well as of oxidizing gases, fuel, etc. is of primary importance."

Jan 1, 1989

By Randal J. Barnes

The January 1988 issue of Engineering and Mining Journal includes two short articles on blasting practices in surface gold mines (Anon., 1988 ; Carr , 1988). A reader of these articles learns, among other things, that a "12 x 13 ft" blasting pattern is used at the Carson Hill Mine, and a "17-ft burden and 18-ft spacing" is used at Echo Bay Mineral's Borealis operation, while at Mascot's Nickel Plate Gold Mine "ore shots are on a 10 x 10 ft" pattern. Like a new edition of the World Book Almanac, these articles are overflowing with useful tidbits of technical data; but, they never mention why the particular blasting patterns were selected. A survey carried out during the Winter of 1988 at six surface gold mines in the western United States also failed to produce a satisfactory answer. The responses from mine planning engineers to the question "why is your blasting pattern X by Y", reduced to "we use X by Y here because we used X by Y at our last operation, and it worked ok." Certainly, with the available decades of experience and professional practice in blast holes design, rock fragmentation in surface mines has been thoroughly investigated. However, and this is the central issue, fragmentation of the rock is not the primary purpose of most rotary drill holes in surface gold mines. Quoting senior mine engineers from companies operating, three of the richest surface gold mines in the world (AMAX Gold, Homestake Mining, and Gold Fields Mining)

Jan 1, 1989

By Lee W. Abramson, William H. Hansmire

The H-3 Project is planning, design, and construction of a 10-mile (16 km)-long final segment of new highway that traverses the Koolau mountain range in Oahu. Interstate H-3 traverses North Halawa Valley on one side of the Koolau Mountains and Haiku Valley on the other side. The project includes a tunnel through the mountain range. The one-mile (1.6 km)-long twin-bore Trans-Koolau Tunnel will have two lanes in each direction. The total roadway width including shoulders in each bore will be 38 ft (11.6 m). The geologic and geohydrologic conditions along the alignment present a variety of tunneling problems. Geologic conditions consist of volcanic materials deposited generally in fairly thin basaltic layers. These volcanic materials generally weather down to "MH" soils which are compressible but relatively strong. Perched ground water that is recharged by heavy rainfall is present in the mountains. The paper presents results of initial geologic surveys and exploratory boring, and plans for exploratory tunneling and testing programs. A site specific classification method developed to characterize the weathered profile is presented.

Jan 1, 1989

By Adam J. Szladow

"INTRODUCTIONThe low calorific value and the high moisture and ash contents of run-of-mine (r.o.rn.) lignite limits the utilization of Saskatchewan lignites to thermal power plants in Saskatchewan, Manitoba and western Ontario. On the other hand, the low sulphur content and the low mining cost make lignites potentially attractive for new coal markets, if suitable processes can be found for upgrading. Economic upgrading to a higher quality fuel would make lignites more acceptable for industrial and utility boilers.This paper presents a summary of the process engineering evaluation of coal upgrading technologies conducted in support of a study of selected lignite upgrading processes. The summary presents the relative advantages and offers specific comments on the application of coal upgrading technologies for lignites. ResourcesLignite comprises the largest fossil fuel energy deposits in Saskatchewan. The total resources of immediate and future interest exceed 27 billion tonnes. The measured and indicated lignite resources of immediate interest are large enough to last for over 200 years at the current production rate of about 10 million tonnes per year (Table 1).Saskatchewan lignitedeposits are present in three different geologic formations: (I) the Ravenscrag Formation of Paleocene Age in southern Saskatchewan; (2) the Swan River Formation of Lower Cretaceous Age in central north Saskatchewan; and (3) the Judith River Formation of Upper Cretaceous Age in central west Saskatchewan. The deposits in the Swan River and Judith River Formation are not currently of economic interest.The Ravenscrag deposits are confmed to four lignite basins, namely: the Estevan, the Willow Bunch, the Wood Mountain and the Cypress basin (Fig. 1). The estimated resources of immediate interest in the four basins are over 7 billion tonnes (Table I). These resources include lignite seams at least 1.5 m thick, at depths of less than 45 m.The average quality of lignite varies relatively little between the four basins considering the distance between deposits (Table 2). There is, however, a progressive increase in moisture and ash content, and a decrease in calorific value and carbon content as one moves westward from the Estevan to Wood Mountain and Cypress basins. The Estevan area deposits are of higher rank despite the fact that they are stratigraphically younger than the Willow Bunch deposits (Cameron and Marconi, 1979).In upgrading lignite to a higher quality fuel, it is important to know not only the average proximate and ultimate analysis (Table 2) but also other lignite characteristics influencing the product quality . For example, Figure 2 shows the effect of lignite HIC ratio on the product equilibrium moisture for hydrothermal treatment of lignite. It is apparent that lignites with a higher HIC ratio, or high liptinite content yield much better quality product for the same hydrotreatment conditions. Other examples of lignite characteristics which are important in upgrading include distribution of sulphur forms and mineral matter, maceral composition and degree of surface oxidation."

Jan 1, 1989

By W. F. Riggs

INTRODUCTION Flotation equipment is becoming more definitive in design as well as greater in dimension. The last ten years have witnessed the implementation of large flotation cells ranging in size from 28 to 85 cubic meters. However, small plants still operate with cells as small as 3 cubic meters. These changes have increased the operational sensitivity of the flotation system to the chemical reagents used. No scientific study has been undertaken to develop the relationship between the size of equipment and the response of reagents in the flotation system. Hence, this article is an attempt to present several observations from past experience for the purpose of stimulating future research in an area previously ignored and perhaps subsequently not used to advantage. CONVENTIONAL FLOTATION Recent advances in conventional flotation cell design have been made in two areas: a. Flotation cells are becoming larger, and b. Basic design of flotation cells has changed. They can be classified into two types: deep cell and shallow draft cell. Size and design changes of flotation cells have a greater effect on frother performance than on the performance of other chemical reagents. Hence, the discussion in the following sections is restricted to the impact of frothers in the flotation system. Flotation Cell Size The advent of increasing flotation cell size has resulted in the increase of frother consumption. There appears to be a correlation between reduced horsepower (kilowatt) consumption and increased frother consumption per ton of ore processed in the circuit. This is more prevalent when the frother chemistry remains unchanged. Another reason for increased frother consumption is the increased distance between the rotating central shaft and the lip of the cell for larger flotation machines. Increasing this distance results in increased surface area corresponding to the larger cell size. Reduced power input per ton combined with the need for longer, stronger load support of the froth bubble as a result of increasing cell size has resulted in the development of a new series of stronger and more persistent frothers. By the same token, these newer, stronger frothers are difficult to control when applied to the smaller cells. This is true even at lower dosages because the break point between too much frother and not enough frother for optimum metallurgy is normally very narrow. This problem is often exaggerated when operators have established an optimum setting for pulp level and air for the particular frother in use. Generally, the tendency is to operate the flotation cells simply by adjusting frother dosage. The increase in frother strength to accommodate the large cells often results in the realization, after a retrofit, that the existing pump box or sump which is still handling the same volume of concentrate is no longer adequate in size. Flotation Cell Design The two most common flotation cell designs installed during the past ten years are the deep cell and the shallow draft cell. The deep cell provides for complete mixing of air and pulp at the bottom of the cell. The shallow draft cell does all the mixing/pumping in the bottom haft of the cell whereas the mixing of the air is performed further up the shaft and is brought into contact with the pulp midway up the vortex. There are many preferences for one or the other. It is the author's contention that both designs have very valid concepts and must simply be suited to the particular situation as required by the operator. The following comments are subjective observations which should be explored in greater detail. The deep cell mixes both air and pulp together at the bottom of the cell requiring a full depth ascending of the homogenized air to the surface to form the froth layer. This design, in combination with charged air, provides for good concentrate grade control under adverse conditions of selectivity, especially when faced with a fine grind and a slime-laden gangue. A selective frother can be applied without a competitive loss in recovery. One of the conditions for good selectivity in this environment is operating at medium pulp solids concentration in the range of twenty-six to thirty-four per cent (26-34%). When a higher solids concentration is used in combination with a coarse grind, it becomes difficult to maintain the same recovery with a selective frother due to higher pulp viscosity. This condition sometimes results in an unacceptable coalescence of the air bubbles as they ascend the full height of the deep cell. The increased pulp viscosity at higher solids concentration can also retard the flotation kinetics. The combination of decreased surface area of dispersed air and slower kinetics can result in reduced recovery causing coarse particles to continue to drop

Jan 1, 1989

By M Stewart

Alluvial gold deposits in the area studied are preserved on the valley floor and elevated terraces due to a sequence of glacial/interglacial events during Pleistocene and Recent times. Continued regional uplift has overprinted these events. Prospecting by drilling and bulk sampling has demonstrated a complex alluvial gold resource which is now being mined.

Jan 1, 1989

By J. A. Dos Santos

High angle conveyor (HAC®) systems in open pit mining offer many advantages over the traditional, truck only, haulage systems, including: (1) superior energy efficiency, (2) less dependency on petroleum products, (3) less sensitivity to inflation, (4) less labor, (5) less excavation for the amount of ore recovered, and (6) less ramp construction and maintenance costs. Previous studies had revealed the technical and economic feasibility of high angle conveyors. This paper presents the Sandwich Belt HAC® as the vital link to optimization of in-pit conveying systems. HAC development to date is discussed, beginning with studies in 1979, to the first large scale prototype in 1983, to the first commercial unit in 1984, into "the latest commercial installations. Discussion continues with the HAC systems to suit the various open pit mining operations and the corresponding characteristics of the system components, particularly the high angle conveyor. The range of HAC systems from the low capacity (up to 1,814 t/h), low lift (10.7 to 36.6M), highly mobile to the moderate capacity (1,814 to 3,629 t/h), moderate lift (36.6 to 76.2M), intermittently mobile to the high capacity (greater than 3,629 t/h), high lift (greater than 76.2M), semi-mobile, are discussed along with some possible combinations of these.

Jan 1, 1989

By B. R. T. Simoneit

The formation of petroleum is normally thought of as a geologically lengthy process, involving the accumulation of organic matter, its gradual burial, diagenetic breakdown via geochemical reactions, maturation, heating within a 75-150'C "oil window" induced by normal geothermal gradients in the subsiding basin, and slow product migration into structural traps (Tissot and Welte, 1984, Hunt, 1979). The entire process can take millions of years and, indeed, most oil reservoirs probably formed in this manner. How-ever, today in sedimented, submarine rift basins (Fig. 1), Cl to >C40 hydrocarbons with the chemical and physical properties of crude oil are forming in demonstrably much shorter time by rapid thermal maturation of immature organic matter in hydrothermal regimes that are unusually high for sedimentary basins (Brault and Simoneit, 1988a, b; Didyk and Simoneit, 1988; Kawka and Simoneit, 1987; Peter et al., 1988; Simoneit, 1983; 1984; 1985a,b; 1988; Simoneit et al., 1984; 1987; 1988).

Jan 1, 1989

Interest in industrial minerals in recent years has increased to such an extent that it has taken them into the mainstream of the Australian mineral industry. Notwithstanding that time series data on the values of production, exports, and imports show that industrial minerals are overshadowed by metals and energy minerals, their contribution to the national economy is important and more significant than would seem to be indicated by the statistics. Whereas the ex mine value of metals generally includes some processing (at least to a concentrate stage), most industrial minerals are valued at little more than their extraction cost, in addition to which such costs are generally low because most industrial minerals are exploited in low-cost surface operations. Consequently, values of mine production of metals and industrial minerals are not strictly comparable in that values of mine production of metals tend to be overstated Short term growth of the industrial minerals sector is assured because of several new projects already commissioned but not yet reflected in the statistics. Longer term growth is also assured, based on various other major projects that are likely to come on stream in the early to mid 1990s.

Jan 1, 1989

By A. G. Fabbri

This paper aims at the application of quantitative criteria for evaluating the mineral potential of square cells representing areas in terrains being explored at a reconnaissance level. The assumption is made here that the evaluation methods used by an expert economic geologist can be organized into geological models for establishing associations within imaged areas, that correspond to pixels with similar characteristics. UTM-registered multiple data sets have been constructed which include seasonal LANDSAT 2 and 4 images, SEASAT scenes, selected airborne radar images, digitized aeromagnetic, gravity, bedrock geology and topographic elevation maps. The area of interest is located in the Bathurst Inlet, District of MacKenzie, N.W.T., where a preliminary mineral potential evaluation was performed by the Geological Survey of Canada to assess its suitability for a national park. The multiple data sets described in this paper can be used for many studies at different resolutions, for comparing processing methods in remote sensing and, most importantly, for evaluating the physical and spatial relationships between the different images in registered data sets.

Jan 1, 1989

By Sukumar Bandopadhyay

A present dominant problem is that of high downtime of the longwall shearer used in the coal production process. The means by which this problem can be overcome are many, but one of, the most important ones is that the-use of an expert system can reduce diagnostic and repair time. In this paper, a fault-diagnostic expert system model is presented. Specifically, the diagnostic architecture of the longwall shearer expert system and its use for diagnostic reasoning are discussed.

Jan 1, 1989

By Douglas Owen

Two case studies describe the introduction of technology new to an organisation. The lessons learnt from these Case studies contribute to Our general understanding of the management of technological change.

Jan 1, 1989

The GDR has extensive lignite deposits at its disposal, which formed the basis for the development of an independent energy source after 1945 and which will retain their significance well beyond the year 2000 (see fig. 1). In 1946 lignite output was about 110 x 106 t. In 1985 312x 106 t was produced and in 1988 the planned output will be ca. 315 x 106 t. Thus, the domestic produc- tion of lignite covers ca. 75% of the GDR's primary energy requirements. More than 80% of the electrical energy is gener- ated by the use of lignite and about 12% by nuclear energy. In addition to this, about 18 x 106 t/a mineral oil and about 6 x 109, m3/a natural gas are imported, predominantly from the Soviet Union. The lignite deposits of the GDR are of Tertiary origin and are recovered exclusively by opencast mining. There are two large regions (fig. 2): - in the region east of the river Elbe (Cottbus/Senftenberg- "Niederlausitz") and - in the region west of the river Elbe (Halle/Leip- zig/Magdeburg). These deposits differ in geological age and conditions of depo- sition, consequently there are differences in their chemical and physical composition and, thus, in their uses. The younger Mio- cene coals of the main region in the East of the river Elbe belong to the epirogenetic type and have a low content of ash and sul- phur. Among other things, they are suitable for the production of brown coal high-temperature coke (Lauchhammer and Schwarze Pumpe). The older Oligocene coals of the Halle/Leip- zig region are bitumenous in certain areas. Therefore, they form the basis for production in low-temperature carbonizing and chemical plants. In the Halle-Magdeburg region, where the lig- nite is in contact with the underlying Zechstein subdivision, so- called "salt coals" are found.

Jan 1, 1989

By J. S. Stachulak

Installation of a computerized mine monitoring and control system in two planned construction phases began in 1983. Phase one consisted of providing a central monitoring station located on surface for monitoring underground CO detection in Frood Mine's heated area. The implementation of this project annualized labour savings of $200,000. The cost of installation of an early fire warning system was $100,000. There are several CO sensor monitoring carbon monoxide trends through mine heated areas. To obtain an early warning, it is not good enough to know that a fire has started, but it is also necessary to know where the fire is located.

Jan 1, 1989

There has been much debate in the past as to whether the Australasian Institute of Mining and Meteorology ("AusIMM") should issue valuation guidelines in addition to the ASX and NCSC requirements. My experience in preparing independent expert reports has been that "best practice" sets higher standards than any laws or requirements set out by the ASX and NCSC. This is where I see the AusIMM coming in.

Jan 1, 1989