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By K. Wood, L. Duval

"The paper discusses the approach used to add a new, separate 5000 t/d copper-zinc treatment circuit to an existing, 1650 t/d copper circuit, essentially within the existing mill building. Temporary installation of new equipment allowed renovation and expansion within existing operating areas. Production in the original circuit was maintained at rated capacity throuqh0ut the construction period through close co-ordination between operating and construction groups. Downtime for circuit and service tie-ins was minimal. Both circuits are described briefly.For presentation at Canadian Mineral Processors Conference Ottawa, January, 1987.INTRODUCTIONLes Mines Selbaie is located in the Abitibi region of northwestern Quebec, in what has recently become better known as the Casa-Berardi-Joutel area. Les Mines Selbaie is operated as a joint venture project managed by Selca Division of BP Canada Inc. and owned 55% by BP Canada, 35% by Esso Minerals Canada and 10% by Trans Canada Pipelines."

Jan 1, 1987

By Hosking IA, Mirkov P

Among the solutions currently being considered for improving traffic flow in Sydney are the construction of major road tunnels, principally the Eastern Distributor Tunnels, leading from the end of the Cahill Expressway to Drivers Triangle and South of Taylor Square and the Sydney Harbour Tunnel, which incorporates sections of driven tunnel at the northern and southern sides of the harbour. The Eastern Distributor Tunnels, known as Stages 2 and 3 of the Eastern Distributor Scheme comprise: Stage 2 - A south bound two lane tunnel from north of William Street to Driver's Triangle. The southern end includes two Y junctions (locally 3 to 4 lane widths) with exits into South Dowling Street, Anzac Parade and Moore Park Road. Stage 3 - A north bound, two lane tunnel from Taylor Square to Palmer Street just north of William Street. Further details of the Eastern Distributor Tunnels are given in the paper by Baxter, Chappel and Fishburn (1986) which is included in this conference.

Jan 1, 1987

The Karangahake gold-silver deposit is located 11 km west of Waihi in the southern part of the Hauraki Goldfield. Historically it was the second largest bullion producer in the goldfield with a past production (1882 - 1944) of 126.712 tonnes of gold-silver bullion (Au:Ag ratio of 1:3.3) from 1 142 315 tonnes of ore grading 27.4 g/tonne gold equivalents.

Jan 1, 1987

Previous models describing the aggregation of polymer coated particles fail to take into account the fact that there are a limited number of sites onto which a polymer segment can adsorb, called ?active? sites. Thus, the collision efficiency is a factor not only of the fractional surface coverage, but also of the number of active sites. In this study, a physical model of the flocculation system was devised in which the number of these sites could be varied, in order to study the effect on particle aggregation.

Jan 1, 1987

By Binns MJ

Gold/silver orebodies of the Golden Plateau deposit, Cracow, Central Queensland, are currently being exploited by the Cracow Mining Venture. A geostatistical block model has been prepared to assist with long term mine planning. The Golden Plateau orebody, of inferred epithermal origin, is a multiply brecciated, silicified fault complex containing irregular, tabular and pipe- like oreshoots. Historically the lode has been stoped and open cut over a strike length of 750 metres at widths of up to 15 metres and to a depth of 250 metres. The Golden Plateau mine produced 1.55 million tonnes of ore at an average grade of 12 g/t Au and 13.5 g/t Ag over a 42 year period. In the preparation of the reserve model much reliance has been placed on recent diamond and reverse circulation drilling (71 holes in total). However a significant volume of data has been derived from historical level assays and underground diamond drilling. Over 3,000 level assays and 50 underground drill holes contributed to the database. Similar lognormal populations were observed for 1 metre composite grades from each major drilling campaign once corrections were made for core loss. Cumulative frequency plots revealed only one outlier which was cut to the population line. The population statistics from the historical level assays showed a significant difference from those derived from the drill hole composites. Level assay populations were cut to local drill hole populations before incorporation into the ore reserve model. The resulting data has yielded interpretable variograms, the parameters of which have been applied to the preparation of a kriged block model of the deposit.

Jan 1, 1987

By Yokozawa K, Yamamoto T, Kameoka Y

Japan Construction Method and Machinery Research Institute has been conducting various field surveys of tunnel works and other excavation works, and the cost and efficiency of these two excavation methods have been studied. Based on these data, the costs of blasting excavation and mechanical excavation represented by roadheaders were calculated. The costs were calculated and compared for rocks of various hardness. When the total construction cost is considered, the degree of overbreak becomes one of the most influencial factors, because the overbreak area must be filled up with expensive shotcrete in NATM. So, in the next step, the relation between the excavation costs considering overbreak and the rock hardness was studied using the data on overbreak obtained by the field survey.

Jan 1, 1987

By James A. Procarione, Sandip K. Mukherjee

The Department of Mining Engineering, University of Utah, has developed a thermodynamic-based mine ventilation simulator capable of predicting or analyzing the climatic conditions in hot underground environments. This compressible flow model, besides analyzing an operationally and legally-constrained network for mass and pressure balance, also takes into account various existing and anticipated sources of heat. Presently, three major sources of heat have been incorporated in the model. These include autocompression, wall-rock heat, and heat from equipment. A unique feature of this simulator which makes it distinctly different from its existing predecessors is the mathematical technique utilized to solve the network problem. Advantage has been taken of newer, more sophisticated mathematical and programming techniques to accomplish accelerated convergence and network solution generation. This paper describes in detail the development of the simulator including the mathematical relationships and the techniques used to predict the initial and final thermodynamic states of the mine air after its interaction with heat sources. The algorithm for solution to the network, computer model description, and the input data and program execution requirements are presented. A simple hypothetical network is used as a case study to illustrate the application of this simulator.

Jan 1, 1987

By W. J. Cieslewicz

Geologically, northeastern Siberia is a region occupied by a folded belt of Triassic and Jurassic sediments and volcanics. Gold mineralization is of Upper Jurassic age. Most of the stream placers formed during the Quaternary. Placer gold was first discovered in 1916. Between 1930 and 1957, mining was carried out by the "Dal 'stroi," a Russian concentration camp organization. Since 1966, the mines have been worked mechanically. About 10 mining districts are now active, producing, altogether, 110 to 135 t (120 to 150 st) of gold annually.

Jan 1, 1987

By P. Venkatsubramanian, D. R. Maneval

An insufficient hydrologic data base exists for most large and small coal basins in Alaska owing to the lack of need in the past to collect data. The runoff process is insufficiently understood which is complicated by specifically northern phenomenon, and the lack of understanding of hydrologic relationships in permafrost environment. This paper presents an understanding of the hydrologic effects of frozen ground and presents methods by which the influence of surface mining upon the hydrologic balance can be analyzed.

Jan 1, 1987

By K. A. Brunk

Newmont's research, operations, history and experience with pre-treatment of preg-robbing carbonaceous ores are described, with emphasis on the chemistry, physics and kinetics of chlorine treatment. Present operations, control strategy and projected changes are also described, including a summary of the adsorption of chlorine into pulps and off-gas scrubbing. Conditions of chlorination have been optimized by the use of Eh-pH diagrams of the gold-chlorine-water system, and have resulted in significant increases in gold recoveries and decreases in chlorine consumptions.

Jan 1, 1987

By T. T. Chen

Kidd Creek continuously-cast copper anodes are characterized by high levels of Se, Pb and Ag; the anode slimes constituents and their morphologies are controlled by both the anode composition and the casting process. Hollow Cu2Se spheroids and tube-like structures, enveloping Cu-Pb-As oxide and/or Cu2O, are present in the as-cast copper. During electrolysis, the selenides are liberated from the copper and accumulate in the slimes layer; the Cu2O and Cu-Pb-As oxide react rapidly with the electrolyte to form soluble species and PbSO4. Silver, which is present mostly as a solid solution in the anode copper, is also liberated during electrolysis and reacts with the Cu2Se to form (Cu,Ag)2Se. The ultimate composition of the selenides in the slimes layer depends mostly on the Ag and Se contents, but various other elements, including Au and Te, are also structurally incorporated. Although the selenides are the major Ag carrier, metallic silver also is present. A thin layer of Cu2O crystals sometimes forms at the copper surface, and may affect anode passivation. Copper sulphate is a common constituent and serves to agglomerate the slimes. Copper sulphate is present on both passivated and non-passivated anodes, but that observed on the passivated metal is present as a thick compact layer. Copper powder is associated with CuSO4.5H2O only on passivated surfaces.

Jan 1, 1987

By B Scheiner, D. A. Stanley

Introduction Treatment of ores to recover metal and mineral values results in waste materials usually in the form of dilute slurries. The US Bureau of Mines (USBM) investigated a technique for dewatering phosphatic clay waste by flocculating with polyethylene oxide (PEO) and dewatering the resulting floes on a static screen and/or trommel screen (Schemer et al., 1985). In the investigation, it was determined that PEO was far superior to polyacrylamide polymers for this type of dewatering. This paper discusses reasons for this superior performance. Comparison of PEO with polyacrylamides Dewatering experiments were conducted by adding PEO solution from a burette to a stirred clay slurry. The dewatering endpoint was characterized by rotation of the floc mass as a unit, a clear supernate, a maximum floc size, and a minimum floc volume. Additional water was removed from the floes by hand squeezing (Schemer et al., 1985). The clays investigated were sodium, potassium, magnesium, calcium, and aluminum exchanged montmorillonite and attapulgite. Nine commercially available (Superfloc) polyacrylamides were compared with PEO at two polymer concentrations. Results are summarized in Table 1. The solids content of the dewatered clays ranged between 24% and 33% and was highest for PEO-treated material. These results and the data in Table 1 indicate that PEO is superior to polyacrylamide in terms of polymer dosage required. Superflocs 16 through 128, like PEO, are nonionic and should give similar results to those for PEO if the flocculation mechanism is the same for both type polymers. Superflocs 204 through 214 are anionic with increasing anionic character from 204 to 214. Generally, the anionic polymers gave the best results for the polyacrylamides tested, but in terms of dosage they were not as good as PEO. Correlation between flocculation and dewaterability of waste slurries The overall mechanism for mechanically induced clay dewatering is not completely known, but certain observations can be made. For instance, when a polymer is adsorbed on a clay such as montmorillonite, the polymer desorbs interlayer water. Polymer adsorption is driven by favorable entropy changes associated with this water desorption. It is also known that the -CH2-CH2- links of the PEO chain are sufficiently hydrophobic to lead to physical adsorption of the polymer (Theng, 1979). For montmorillonite slurries, the sheet-like fundamental particles, called tactoids, consist of a small, variable number of aluminosilicate layers together with interlayer water and exchange ions. The flocculation process consists of adsorption of polymer on the tactoid. Loops and tails of polymer that extend into solution then adsorb on another tactoid, forming a bridge. Mechanical action, induced by hand squeezing or in a trammel, joins the bridged tactoids face-to-face and edge-to-edge to form regions of high density. Similar orientation effects are observed for the needle-like attapulgite crystals (Schemer et al., 1985). Proposed flocculation model Generally, statements concerning flocculation and dewaterability apply to both PEO and the polyacrylamides. However, PEO has additional interaction with the clay material when compared with polyacrylamides. PEO is a polymer with repeating -CH2-CH2-O- groups and interacts with montmorillonite through a water bridge whose strength is greatly influenced by the exchange ion. To obtain insight into this interaction, a series of experiments were conducted in which different ion exchange forms of montmorillonite and attapulgite clays

Jan 1, 1987

By D. W. Tedder

Several bauxite feeds and residue sands and muds, produced by Bayer plants in the US and over-seas, were fractionated using dry and wet magnetic separators. The magnetic sand fractions typically contained about 50 to 60 wt % Fe2O3 and the bulk of the radioactivity in the sands. The muds are more difficult to process, but some fractionation is possible using a combination of classification and magnetic separation techniques. Among the mud samples, higher radiation levels are often associated with the less magnetic fractions. Bauxite is more easily fractionated using dry magnetic separation. Much of the radioactivity in bauxite appears to concentrate in the sand and mud residuals.

Jan 1, 1987

By James A. Strosnider

INTRODUCTION The Metro Rail Project is approximately a 20-mile initial portion of Southern California's planned 150-mile transit network and will provide transit service to the dense population and employment centers within the Los Angeles regional core. The Southern California Rapid Transit District (SCRTD) has defined, as the first segment, a 4.4-mile five station rail line, which extends from the yard and shop area near Union Station to the Wilshire/Alvarado Station. Design packages are completed; utilities are currently being relocated; demolition is underway; early construction contracts have been awarded; and construction has started. This paper will describe the current status of the Metro Rail design and construction, after first briefly reviewing its history, objectives, and main components. PROJECT HISTORY The California State Legislature created the SCRTD in 1964 with a legislative mandate to design, construct, and operate a rapid transit system within the Los Angeles County area. To obtain the monies required to support this program, in June, 1974, Proposition 5 was passed by a solid majority, allowing a portion of state gasoline taxes to be used for rapid transit development. This measure provided a local source of funds for SCRTD to begin its rail rapid transit development program in Los Angeles.

Jan 1, 1987

By Ruston A. Ford

This paper reviews the development of the David Bell Mine, from early exploration, through discovery, construction, start-up, underground development, and production. Details are provided regarding the mine development, the mechanized cut and fill stope production, the proposed long-hole stoping with delayed backfilling mining method for the lower levels and the cyanide leach carbon-in- pulp concentrating process. The mine development remains on schedule and under budget with results very much as predicted in the feasibility study.

Jan 1, 1987

By Ishikawa K, Kikuchi T, Tokairin Y

Roadheader, developed from coal cutting machines, is generally classified as a tunnel excavation machine for soft rocks in respect to excavation mechanism, machine structure, weight, engine output and so on. In recent tunnel works, however, there is an increasing demand for changing from blasting to mechanical excavation by roadheaders to avoid environmental problems such as noise and vibration. But there exist various difficulties in excavation of harder rocks by roadheaders. In order to explore the possibilities of roadheader excavation, we performed field and laboratory experiments. In the field experiment, roadheader model S-125 (Mitui Miike Machinery Co.,Ltd.) was tested for various rocks of wide range of hardness, and excavation capacity and wear of picks were measured. In the laboratory test, cutting performance of the picks was tested by our cutter testing machine. This report describes thr: of these experiments and discussions :n possibility of applying boom-type tunnelling machines to hard rock excavation based on these experimental data.

Jan 1, 1987

By D. H. Batchelor

Efficient modern-day mining operations are turning increasingly to technology to combat rising operating costs in an adverse economic climate for the industry. Computerised truck dispatching is one such technological advance that has enhanced the efficiency of the mining operation at Palabora. The economic incentives, basic operation and general system benefits of Palabora's computerised truck dispatching system are considered.

Jan 1, 1987

By L. A. Haas

The Bureau of Mines, in cooperation with three Minnesota agencies (Department of Natural Resources, Geological Survey, and the Iron Range Resources and Rehabilitation Board), investigated the potential of using glacial lake clay from Minnesota, as well as other areas, as a binder for iron ore pellets. The best clay-characterizing procedures for predicting binder effectiveness were the cation exchange capacity (CEC) using the methylene blue method and the plate water absorption test (PWAT). The best clay binder was found in the Red River Valley. However, compared to a typical western bentonite at the 0.5-pct-addition level, addition of about 2 pct Minnesota clay was required to obtain comparable unfired (green) pellet strengths. Soda ash addition only slightly improved the binding properties of Minnesota clay, but considerable improvement was obtained by the addition of a small quantity of water absorbing organic compounds. For example, with a mixture of 0.5 pct Minnesota clay or paint rock and 0.1 pct pregelatinized starch, the unfired and fired physical pellet properties were about the same as with 0.5 pct of typical western bentonite. The reduction rate at the 40-pct reduction level and the percentage of plus 6.3-mm particles from the reduction disintegration index test were also about the same.

Jan 1, 1987

Mr. Bradford said: - On assuming this chair, which has been oc- cupied by so many gentlemen of conspicuous ability, my first words must be an expression of the gratitude I feel for the honour you have done me in electing me to be your President for this year. When considering the subject matter of this address to you to- night, quite frankly may it be stated that for a long time I was on the horns of a very great dilemma, for while I could discourse on the modern political trend in relation to our industries at great length, it appeared to me that this was not the place for such a discussion.

Jan 1, 1987

A powerful, interactive metallurgical process simulator for use on micro- computers has been developed in the Department of Metallurgy and Materials Engineering at the University of the Witwatersrand. MICROSIM presently allows simulation of all ore-dressing flowsheets and a selection of hydrometallurgical unit operations, and is extendable to all such processes. MICROSIM is written in Pascal. This modern language provides very versatile data structures which can be effectively used to solve the major problem in generalised simulation programs, namely storage and transmission of data relating to liquid and solid phases. Dynamic memory allocation allows optimal utilisation of computer storage space. The simulator utilises very efficient precalculation algorithms that determine the tear streams for optimal sequential modulator calculation convergence. Microcomputer graphics simplifies flowsheet specification, and form-filling data capture with supplied default values eliminate most common input errors.

Jan 1, 1987