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By Brian C. Maynard

"Blast design is becoming more and more important as industrial limitations change in regard to economical and physical restraints. Certainly there are ways to alter the nature of the blast by using different explosives, various hole sizes and modifying the timing and charging details. However, it is not possible to alter the fabric of the rock mass. Therefore, it is necessary to learn more about the rock mass and its role in the blast design, and the resulting fragmentation. The major determinant in the degree of fragmentation, or lack of it, is proposed to be the inherent fragmentation of the in situ rock mass. A practical method of quantifying the discontinuities existing in the rock mass is presented and discussed. Likewise, the effects of inherent fragmentation on the resulting muckpile are reviewed. Finally, a fragmentation model combining the calculated inherent fragmentation and the Kuzram model is shown using a sample blast.IntroductionIn blasting, discontinuity characteristics (Fig. 1) control the method by which the rock mass will behave. Research carried out by Piteau (1970) showed a number of characteristics important in engineering design and, as proposed, in blasting processess. These included:• the nature of their occurrence (i.e. sets or isolated);• orientation and position in space;• continuity; and• intensity"

Jan 1, 1990

By J. R. Shouldice

"IntroductionREEFS of Silurian age are recognized in southwestern Ontario, both in outcrop and from subsurface information. This paper deals with the so-called 'pinnacle' reefs which are known only in the subsurface. For the purpose of this paper, the pinnacle reefs are arbitrarily defined as those structures having a height of over 250 feet and a length of less than two miles. This definition eliminates numerous mounds and other broader, more subdued, structures of less certain origin, found in subsurface beds.The term 'pinnacle reef' is perhaps unfortunate, but it is in common usage in Ontario and is used elsewhere for different types of reefs. A new name is justified by the unusual environment and structure of the Ontario reefs, but it is unlikely that any other term would gain acceptance. Rather than propose a new term which would be ignored or result in further confusion and misuse, the name 'pinnacle', as defined above, is used in this paper.Pinnacle reefs have been found over a fairly large part of southwestern Ontario. The known reefs of this type parallel the southeast edge of lake Huron and •follow the strike of the structure contours which circle the Michigan basin (see Figure 1). In total, twenty-five such reefs have been discovered in southwestern Ontario."

Jan 1, 1955

By D. M. Bastidas

The reduction of copper sulfide and copper oxides originated during artificial tarnishing of copper was studied using potentiodynamic potential/current density experiments. Six copper surface treatments were considered: mechanical polishing; indoor exposure for 7 days; chemical etching in 1.6 M nitric acid; chemical etching and heating at 160°C; and chemical etching and dipping in a 9x10-4 M or 0.9 M potassium sulfide (1(25) solution at 70°C. Cuprite (Cu20) and chalcocite (Cu2S) were the main compounds formed. A linear relationship with the square root of the scan rate (v) was obtained by plotting the potentiodynamic potential/current density for the tarnish dissolution processes. A relationship between potential and current density cathodic peaks was not obtained, according to Müller's model, showing a proportionality factor with the dimensions of a resistance.

Jan 1, 2007

By T. Takahashi, K. Oyamada, Y. Miyata, T. Isoo

The carbonation reaction of steelmaking slag has been known for many years. However, the size of blocks manufactured from this by-product material has been limited due to the difficulty of achieving a uniform reaction throughout the block. Using newly developed conditions, large porous slag blocks (1.0 x 1.0 x 0.5 m) were produced by car¬bonation of steelmaking slag with the optimum amount of water and supplying CO2 deep into slag powder compacted in molds. The development of these blocks has great poten-tial to solve the problem of slag utilization, for example, by recycling slag in large car¬bonated blocks for artificial fish reefs and seaweed cultivation beds. This paper de¬scribes the carbonation reaction, the new process for producing large slag blocks, and the utilization of blocks in past and recent years.

Jan 1, 2004

By Alastair J. Sinclair, Asger Bentzen

Abstract - A simple linear model for interpreting duplicate analytical data for a range of values is described. The conceptual model can be quantified using a reduced major axis model rather than the inappropriate traditional least squares approach. The reduced major axis parameters (slope, intercept) and associated errors provide a quantitative basis for: (1) defining bias, and (2) comparing results within laboratories, between laboratories and between sampling/analytical methods. Application of the linear model must be preceded by extraction of obvious outliers or small groups of values that have an inordinately large impact on values of the statistical parameters defining the model. In addition, consideration must be directed to the presence of more than one population of sampling error, as in the case of multiple styles of mineralization being sampled.

Jan 1, 1998

By M. Özer, F. Boylu, G. Önal

In this study, the fine coal waste subjected to the experiments is taken from the waste stockpile of Soma Coal Plant. The possibilities of its evaluation and the production of clean coal were investigated. For this purpose, Reichert Coal Spiral and Shaking Table are used. The minus 1 mm coal waste includes 60.43% ash and 50% minus 38 micron material by weight. The microscopic observations of the screen fractions were shown that the clay minerals are in fine sizes and the coarser size fractions contain silica and carbonate minerals as ash forming materials. The tests were conducted after desliming. The commercial grade clean coal product containing 29-35% ash with a calorific value of 3800-4200 kcal/kg (15.91-17.58 MJ/kg) was obtained by gravity methods.

Jan 1, 2004

By F. R. Ploeger, J. H. Crocket

"IntroductionRocks in the Kirkland Lake district form part of the Timiskaming Group, a south-facing homoclinal sequence of wackes, conglomerate, trachytic flows and pyroclastic rocks and syenitic intrusive rocks. Hewitt (1963) indicates that the thickest section, about 5 km, of the Timiskaming Group rocks is attained in Lebel Township. Several writers (Thomson, 1948; Hewitt, 1963; Hyde, 1978; Jensen, 1978; and Downes, 1979) have observed that the Timiskaming Group unconformably overlies the Keewatin volcanics, particularly along the northern contact. Recent work by Downes (1979) in McGarry and McVittie townships to the east of Kirkland Lake has shown that much of what had formerly been classified as Timiskaming actually belongs to an older group of rocks, the Larder Lake Group (Jensen 1978).General GeologyA series of fluviatile, braided-stream sedimentary rocks (Hyde, 1978) form the oldest of the three major rock suites at Kirkland Lake. Conglomerates constitute a large proportion of these sedimentary rocks and typically contain a large percentage of a variety of locally derived alkalic rock clasts as well as the distinctive red jasper iron-formation pebbles (Fig. 1a). The associated wacke units can be massive to finely bedded and are interbedded with the conglomerate. They also contain a large alkalic tuffaceous component.Interbedded with these sedimentary rocks are alkalic extrusive rocks, including tuffs, agglomerates, breccias and flows, which represent episodes of fissure and explosive crater eruption (Cooke and Moorhouse, 1969). The tuffs, although dominantly alkalic in composition, are commonly reworked and contain sedimentary features such as graded bedding, scouring and crossbedding (Fig. 1 b). The trachytic flows are massive to porphyritic and outcrop mainly east of Kirkland Lake in the adjoining townships. Altered leucitic porphyritic flows, locally referred to as red and green spotted trachytes, commonly occur."

Jan 1, 1982

By A. R. MacPherson

"This paper considers four aspects of autogenous grinding. Part 1 discusses statements on power efficiency of autogenous grinding compared to conventional crushing and grinding systems. It also demonstrates how high-power efficiency can be obtained from autogenous grinding systems. Part 2 considers a simple method of testing ores to determine the type of autogenous plant which can treat these ores on a commercial basis. A comparison of testing for simple small plants vs large plants or complex ores is included. Part 3 considers important aspects which have to be considered in proper design of an autogenous grinding system. Part 4 discusses problem ores and how they can be treated in an autogenous system. INTRODUCTIONAfter about 35 years of using autogenous grinding plants in the mining industry, it is perhaps time to review where we are with this, by now, relatively old development. Autogenous grinding in this paper means grinding run-of-mine ore by fully autogenous means or by using a ball charge to assist the grinding (semi-autogenous). Also, autogenous grinding can be eitherby dry or wet.The use of autogenous grinding in the fifties was making its slow start, and it was not until the sixties that more of the mining industry would consider its use . By the seventies, most builders of new plants would have considered autogenous grinding, whether they used it or not, in the final design.In the eighties, most large plants use autogenous mills and to reduce over-all operating costs, many older conventional plants are now looking and actually retrofitting these old plants with autogenous grinding mills.It is evident that many misconceptions concerning autogenous grinding are still current. Some come from improperly designed plants which result from poor test work. There are many considerations in the proper design of autogenous plants. Some ores have been found to give problems even in a well designed plant. These ore types are beginning to be classified and recognition in the test stage allows steps to be taken in the design so that these ores can be efficiently handled in autogenous grinding plants.Therefore, this paper will address the following aspects of autogenous grinding:1. Misconceptions regarding autogenous grinding.2. Testing of ores to ensure a well designed commercial plant.3. Important considerations in mill design.4. Difficult ores, their recognition and types of design to handle such ores."

Jan 1, 1989

By T. R. Yu, D. B. Counter

"In an effort to increase productivity, the use of fly ash as a binder for consolidated backfill was studied. From laboratory and underground tests f or its cementitious properties and environmental effects, it was found that a portion of Portland cement could be replaced by the same amount of type ""C"" fly ash to produce an acceptable consolidated rockfill product for use at Kidd Creek.The environmental concerns in terms of dust control and emanation of radon gas were unfounded from measurements. The dust count was comparable to the use of Portland cement only, or with ground blast furnace slag, and the radiation readings were low, averaging one-seventh the regulation level.Since May 1984, a total of over 100 000tonnes of fly ash has been consumed as a binder blended with Portland cement, producing over four million tonnes of consolidated rockfill. To date, the fill in the stopes has performed very satisfactorily, while yielding considerable cost savings.IntroductionThe Kidd Creek minesite, located 27 km north of the city centre of Timmins, Ontario, produces 4.5 million tonnes of base metal sulphide ore annually. The mining method for both No. I and No .2 mines is mainly sub-level blasthole stoping with delayed backfilling.No. 1 mine was developed with a shaft to a depth of 930 m in 1973 to recover the ore between the floor of the open pit at the 216 m horizon, and the 792 m horizon. Stopes are normally 18 m wide, 22 m to 65 m long, with heights varying from 90 m to 135 m. Vertical rib pillars between stopes are typically 24 m wide and sill pillars are 30 m thick.Pillar recovery is implemented after the consolidated rockfill placed in the mined stopes has cured for a period of at least three months. This allows a maximum recovery of the ore with a minimum of dilution, while also maintaining safe working conditions.No. 2 mine was developed from a second shaft, sunk to a depth of 1530 m in 1978, for the recovery of ore beneath the No. I mine. Sub-level stoping in No .2 mine is similar to No.1 mine in methodology, yet differs in sequencing, as no rib pillars are left."

Jan 1, 1988

By A. Ghahreman

Activated carbon is proven to be able to catalyze arsenic oxidation in aqueous solution under acidic conditions. A commercially available granular coconut shell based activated carbon (AC) has been evaluated for catalysis of arsenic oxidation in this study. The rapid small-scale column test (RSSCT) has been developed to simulate and predict the performance of a carbon-based arsenic treatment system in a pilot scale reactor. Effects of residence time, aeration rate, and initial arsenic concentration in the influent solution on the AC catalysis of arsenic oxidation under dynamic and continuous conditions were studied by manipulating these parameters during RSSCTs. The effectiveness of the AC on arsenic oxidation was examined over the course of constant diffusivity based RSSCT operation. Residence time and initial arsenite concentration are proven to be the most effective impacting parameters on the arsenic oxidation process. For the 218 min residence time, the highest steady-state arsenic oxidation efficiency achieved was 98% with 1 g/L As(III) being treated at pH=1 under 0.05 L/min oxygen aeration. In a long-running RSSCT, the oxidation efficiency did not seem to deteriorate over a course of 666 hours operation, corresponding to 13986 mL total influent throughput volume. INTRODUCTION Arsenic is toxic to both animals and plants and inorganic arsenicals are proven carcinogens in humans. The increased extraction of low grade and complex mineral resources has introduced high ratios of arsenic into metallurgical processes. Discharge of arsenic by acid mine drainage resulting from mining activities has added intensive pressure on the need for proper treatment (Lawrence & Higgs, 1999). Since trivalent arsenite is more toxic and has lower affinity to solid surfaces for adsorption, many treatment systems initiate with an oxidation step to convert arsenite to arsenate and reach the ultimate immobilization of arsenic by the following precipitation of arsenate (Nazari, Radzinski, & Ghahreman, 2016). Scorodite precipitation has been studied extensively as a means of arsenic immobilization due to its high stability and negligible potential of releasing arsenic (Filippou & Demopoulos, 1997). As a stable ferric arsenate mineral, crystalline scorodite can contain up to 30 wt% arsenic (Paktunc, Dutrizac, & Gertsman, 2008). Arsenic must be in its pentavalent oxidation state in order for scorodite to be precipitated via oxidizing ferrous ions (Clancy, Hayes, & Raskin, 2013).

Jan 1, 2019

By R. Pot

"IntroductionTHE PURPOSE of this paper is to discuss briefly the main logging and testing devices presently at our disposal, to point out some of their limitations, and to suggest possible improvements of the techniques.Some of the more important devices .are those that are used in:(1) Coring(2) Formation testing(3) Electric well logging(4) Radioactive well logging(5) Measuring of bottom hole pressures(6) Sampling of reservoir fluidsThe first four of these procedures are concerned with the well while it is in the process of drilling. The last two are carried out as soon as possible after a well has been brought into production and .at intervals during its life. My remarks will be concerned mostly with certain aspects of formation testing. The reservoir engineer is dependent on the information derived from these operations in order to obtain a clear picture of the conditions in a reservoir and to enable him to assess and forecast its future behaviour.Since any calculation is no better than the data on which it is based, not enough emphasis can be placed on the necessity for the testing and logging equipment to be of the highest quality and for the analysis of the results obtained to be thorough."

Jan 1, 1952

By W. B. Evans, D. P. Taylor

"ANFO has two major disadvantages as an explosive low density and no water resistance. ANFO can be blended with more dense, water-resistant explosives to form ""Heavy ANFO"". The use of emulsion or slurry explosives as a matrix is an attempt to correct deficiencies on the basic ANFO while maintaining cost effectiveness.This paper will deal with four main topics.1. Product description, general properties, strengths and weaknesses.2. Technology of ""Heavy ANFO"" , the emulsion matrix concept and the range of products.3. Relative performance and economics in various rock types.4: Current status in Canada and worldwide, and the expectations for future use.IntroductionANFO has been in use for roughly three decades and remains the explosive of choice where conditions are suitable. ANFO has not become the universal explosive - despite its undoubted superiority in cost effectiveness - because it has serious flaws as an explosive. The most serious of these flaws are the low density and absence of water resistance in ANFO. Low density implies a low concentration of explosive energy in a borehole. The amount of energy available can be increased by. adding an energetic material, generally aluminum, or by drilling more holes. Both solutions add considerably to the over-all costs. The absence of water resistance in ANFO is inherent and can only be overcome by changing the fundamental nature of the product. The history of research in the explosives industry since the advent of ANFO is mainly the story of the various attempts to overcome one or both of ANFO's shortcomings.Many technologies and products have been developed to compete against ANFO, among them slurries, emulsion s and the so-called Dense ANFOs (ANFO with an extra nitroalkane liquid sensitizer). None of them was cost-competitive with ANFO so their market penetration has been limited to wet holes or specialized applications. The exception to this result is Heavy ANFO. The aim here was to have the best of both worlds, the high density and water resistance of emulsions or slurries plus the low cost of ANFO. The concept is very simple. ANFO is about 50 % air, roughly 30% in the prills and 700,10 between the prills . The air in the prills provides the necessary sensitivity but the air between them is waste volume. If one fills this volume with a high density, waterproof product, the resultant mix will be denser and more water resistant than ANFO and with very little added cost. This basic concept was invented by B. Clay in the 1970s and is covered by Canadian Patent No. 1 115 959. The water resistance and/or density of the mix can be tailored by changing the emulsion level. Because Heavy ANFO is relatively inexpensive while providing good in-hole densities and water resistance, it can compete successfully against all other bulk products. It competes against ANFO and Al / ANFO by allowing pattern expansion and reducing over-all costs while it competes against emulsions and slurries on price."

Jan 1, 1987

By R. E. Whitehead

"The earliest gold-mining operations in Ontario included the Cordova, Deloro, and Sophia mines north of Lake Ontario (see for example, Miller and Knight, 1914). The Cordova deposit, worked intermittently between 1891 and 1940, is reported to have yielded 22 774 oz of gold from 127 670 tons of ore averaging 0.19 oz/ton Au (Gordon et al., 1979). The property remained inactive for many years. In 1988, Gunnar Gold Inc. and Mill City Gold Inc. conducted a drilling program along the main Cordova vein. The present study is based on core from three drill holes through the Cordova gabbro (Fig. 1) and the carbonate alteration zones enveloping the quartz-carbonate veins. The relatively narrow width of the alteration zone and the availability of continuous sections of core provided an opportunity to conduct a compact mineralogical-chemical study of carbonate alteration and its effect on the redistribution of rare earth elements (REEs). Although the Cordova deposit is not of great economic importance, this study has revealed a number of interesting features which are interpreted as resulting from processes that may be applicable to gold-bearing quartz vein deposits elsewhere.The Cordova gabbro is layered in places, varying from fine-to coarse-grained and in color from light gray (feldspathic) to dark gray-green (amphibolitic). However, layering within the section of the gabbro considered here and which hosts the Cordova gold deposit is mainly textural rather than compositional. Samples of unaltered gabbro selected for analyses were medium- to coarse-grained; amphibolitic and anorthositic phases were avoided as being less representative of the general chemical composition of the gabbro.The Cordova intrusion has undergone regional metamorphism and consists dominantly of actinolite and saussuritized plagioclase with smaller amounts of granular clinozoisite and flaky chlorite; minor quartz, ilmenite, titanite, apatite, and calcite are typically present. Some actinolite grains have irregular rims of pleochroic green hornblende that is optically continuous with the actinolite. Both chlorite and clinozoisite occur in two modes. Chlorite occurs as an alteration product of actinolite and as separate grains in the groundmass. Clinozoisite and albite occur together as regional metamorphic alteration products of original plagioclase crystals and as discrete grains in the matrix.The main gold-bearing quartz-carbonate occurrence occupies an easterly trending, steeply southward-dipping carbonatized shear zone up to 15 m wide and 700 m long. The gold occurs principally in irregular lenses and veins of quartz-carbonate up to a foot thick occupying the lower part of the schistose shear zone within the gabbro. This zone consists of chlorite, biotite, and carbonate and is flanked on both sides by chlorite-carbonate schist lacking biotite. The chlorite-carbonate schist in turn grades into regionally metamorphosed actinolite-bearing undeformed gabbro.The dominant sulfide within the quartz-carbonate lenses and in the surrounding schist is pyrite which occurs mainly as small cubes (1 mm to 2 mm) generally making up less than 10% of the rock. Rare blebs of chalcopyrite are present. Magnetite is common throughout the schist."

Jan 1, 2001

By C. F. Harris

Following the initial development of the zinc-lead blast furnace, efforts have been directed both at increasing the scope of the process and increasing the cash return. The paper reviews the process developments which enable the process to smelt efficiently a range of material which encompasses high-grade zinc sulphide concentrates. mixed concentrates, Waelz oxide, zinc ashes and other materials blended to give a furnace feed ranging from 25 to 65% zinc and from 1 to 25% lead, with a copper-lead ratio exceeding 1 to 8. The paper also reviews the process developments which have enabled the capacity of a furnace and condenser system of standard size to be boosted from 30,000 to 80,000 tonnes/annum. The benefits achieved are used as a justification for continuation of the development of the zinc-lead blast furnace. Predictions are made of the benefits expected from further developments.

Jan 1, 1979

By Y. Hanada

Electrorefining at higher current density is desirable due to the increase in productivity attained without expanding the plant size. However, increasing the current density in common commercial practice causes problems such as anode passivation, dendritic deposition, cathode impurities and energy consumption. In general, agitation of the electrolyte is effective in suppressing these problems. To apply the agitation to commercial practice effectively, the method of agitation is important. One possible method is agitation by gas injection. In this study, fluid motion characteristics with gas injection between electrodes were investigated using a water model. Flow patterns were observed and fluid velocity was measured using a particle tracking method. It was found that the time-averaged velocity near the electrode walls was of the order of 0.1 m/s in the conditions. The flow was highly turbulent. The turbulent component of velocity was the same order as the time-averaged velocity. The mass transfer coefficient between the wall and fluid doubled when the effect of turbulent intensity was taken into account. The effects of gas injection on the electrolysis behaviour at high current density were discussed in terms of the mass transfer. It is suggested that gas injection could suppress the problems at high current density.

Jan 1, 2007

By A. A. Rogozhin, E. G. Likhnikevich, S. I. Anufrieva, A. V. Kurkov

The Beloziminskoe deposit in Siberia is a large, potentially productive deposit of rare metals contained in ochreous apatite pyrochlore ores formed by weathering of a carbonatite. The ores are composed of pyrochlore, columbitized pyrochlore, monazite, apatite, magnetite, ferric and manganese hydroxide, titanic iron ore, zircon, hydromica, quartz, feldspar, and carbonates. A gravity-flotation enrichment flowsheet with application of cationic and anionic collectors has been developed. This flowsheet allows for obtaining a pyrochlore concentrate containing 44.3% Nb2O5 and 1.89% P2O5 with recovery of 55.83% Nb2O5 as well as an apatite concentrate containing 39.2% P2O5 and 1.05% TR2O3 with recovery of 62% P2O5 and 43.23% TR2O3 from ores containing 0.92% Nb2O5, 16.9% P2O5 and 0.6% TR2O3. Rare-earth concentrate containing 40% TR2O3 with recovery of approximately 10% TR2O3 was obtained at the same time. Major losses of valuable elements are related to slimes, which make up more than 50% of the ground ore. The niobium concentrate does not meet the phosphorus and radionuclide concentrations needed for the production of ferro-niobium. Acid leaching and sulfatization provided a high level of phosphorous and radionuclide removal. Conditions include hydrochloric acid pre-leaching at 75- 80°C with an 18% HCl solution for four hours and low-temperature sulfatization of acid-leached concentrate at 160-180°C for one hour followed by water leaching of the residue. The apatite concentrate could potentially be processed using nitric acid leaching. This technology is based on decomposition of apatite concentrate with 55-57% strength nitric acid with transfer of rare-earth metals into solution in the form of ammonium phosphate. This technology recovers a rare-earth concentrate containing 95% TR2O3 with extraction of 86%, and highly concentrated polynutrient fertilizer (ammophos) with phosphorus extraction of 95%. The completed research shows how complex multicomponent ores of residual soil may be processed for the extraction of niobium, phosphorus, and rare-earth products.

Jan 1, 2016

By Alireza Sarafi, Alijan Aftabi

"A hydrocyclic system used for mineral separation at the laboratory scale results in the separation of more than 90% of micas. The system functions only by water and might offer advantages where other methods of mica separation are not available. INTRODUCTIONVarious methods for the separation of micas, wollastonite, and garnet, e.g., screening, flotation, magnetic separation, and heavy liquids, are well known (e.g., Spence, 1929; Bates,I960; Gillson et al., 1960; Benjamin, 1971; Connor and Kolhnar, 1991; Collings and Andrews, 1991). However, where these methods are not available, the separation of micas by a hydrocyclic system developed by Sarafi and Aftabi (1991) may prove to be economic. This note is a brief description of the hydrocyclic system. Minerals and MethodFor testing the recovery of mica and other minerals from different rocks (garnet-mica schist, skarn, and pegmatite), standard minerals were tested first, and then rock samples. Pure mineral standards were prepared from coarse-grained samples of pegmatite, mica schist and skarn; the grain size of the minerals separated was more than I cm. The Hydrocyclic System and Mineral SeparationThe hydrocyclic system is shown schematically in Figure 1. In the first step in mineral separation, mineral and rock samples were crushed, milled, and then sieved to minus 250 plus 125 microns. Approximately 10 gm to 25 gm of the sample were inserted in decanter Dt • The motor pwnps, M1 and M2, were then turned on and the water valve rl was opened. At this time, water was flowing turbulently (30 em3/sec. to 50 em3/sec.) and minerals were separated according to their crystallographic nature, density and!or habit. The fInal separation was done by exit valves r2, r3 and r4, while the motor pwnps were still operating. After each experiment, the rt , r2' r3 and r4 valves were closed and the motor pumps were turned off. Following this, minerals in each decanter and the mter were collected, dried and weighed. The whole time of the experiment was optimized to be about 10 minutes, but varied from 3 to 15 minutes for micas and garnets. respectively."

Jan 1, 1994

By Euler M. De Souza

"This paper presents a study developed to assess the potential use of salt tailings as backfill to control surface subsidence and as a mine bulkhead used to isolate areas of potential brine inflows. A series of index tests, centrifuge model tests and quasi-static creep consolidation tests were performed to evaluate the creep and consolidation properties of salt backfl1l and to evaluate the effect of brine inflow and brine infiltration on backfill behaviour. The centrifuge models were specifically designed to study the mechanical behaviour of salt backfill under the influence of brine inflow and long-term creep. Test results indicated that salt tailings could be applied underground as a bulkhead to seal off areas of potential inflow with the additional advantage of controlling room closure and local back instability. It is hoped that this study will assist mine planners to develop contingency plans to control brine inflow occurrences. IntroductionThe use of salt tailings as backfill is a technique that would assist in the control of potential brine inflows and surface subsidence, and would have a very positive impact on the long term adverse environmental effects associated with surface salt tailings disposal. A centrifuge testing program was designed to evaluate the behaviour of salt tailings as backfill; the effectiveness of salt backfill as a bulkhead used to isolate areas of potential brine inflow and the potential use of salt backfill to control surface subsidence. The testing program was also used to evaluate the creep-consolidation properties of salt backfill and to evaluate the effect of brine inflow and brine infiltration on backfill behaviour. This paper presents the results of the experimental centrifuge testing program and a comparison of results with models tested under I g using an electrohydraulic servo-controlled loading frame (MTS) and a creep consolidation cell. Applicability of the results to practical underground soft rock mining is also discussed.The centrifuge model tests indicated that salt tailings could be applied underground as bulkheads to seal off areas of potential inflow with the additional advantage of controlling room closure and local back instability. Because the applied stresses (1.2 MPa) and fill consolidation were relatively low, the centrifuge simulated bulkhead did not retain all of the inflow brine. At typical field stresses it is expected that the fill would be able to seal off panels with brine inflows. Further testing at higher stresses are suggested to determine the consolidation and stress levels at which the fill would completely retain any potential brine inflow head and positively act as mine bulkhead."

Jan 1, 1994

By T. L. Tanton

"The New Helen mine is 12 miles east of Michipicoten harbour on lake Superior. It is 2 miles east of Wawa station, on the Algoma Central railway, with which it is connected by a spur line railway and a highway.The mine was discovered by Ben Boyer in 1898 during the gold rush near Wawa lake, Ontario. The original discovery was of solid hematite ore extending to a height of 100 feet on a hill rising abruptly on the east side of Boyer lake. The property was acquired by the Algoma Steel Corporation and mining was commenced in 1899. The first iron ore was shipped in 1900. The mine was operated until 1918 when the hematite became exhausted at a depth of 800 feet below Boyer Lake level.Drilling at the Helen mine, after 1910, revealed a large body of siderite both below and to the east of the hematite. By 1913, the body was known to be about 200 feet wide, 3,000 feet long, and at least 2,200 feet deep. In this there was estimated to be 100,000,000 tons of proved and probable siderite ore. An adit was driven into this body in 1917, and in 1918 work was suspended. In 1937 the Algoma Steel Corporation proceeded with the development of the New Helen mine by open-cut mining, and the beneficiation of the ore by sintering. Production commenced in 1939 and has since been maintained at the rate of approximately 500,000 tons a year.From 1900 to 1918, inclusive, the total production from the Helen mine was 2,823,369 tons of hematite ore and 51,930 tons of pyrite. From 1939 to the end of 1945 the total production from the New Helen mine was 3,921,455 gross tons of siderite ore.GEOLOGYThe Helen property is underlain by rocks of Precambrian age. For general description, and a statement on the structure of the iron deposits, the map-units are those shown in Fig. 1.The oldest rocks occur in a complex that lies north and south of an east-west trending zone, 1 ½ miles long and ¼ mile wide, in which the iron deposits occur. That part of the complex lying south of the iron deposits includes small masses of altered conglomerate and slate, and greenstones and pyroclastics. Other fairly abundant rocks are sericitic, chloritic, ottrelitic, and carbonatized schists of doubtful origin, and almost massive metamorphic rocks in which a development of carbonate, ottrelite, quartz, and other minerals has obscured a pre-existing schistose structure. Felsite and quartz porphyry are· prominently exposed south of the iron deposits."

Jan 1, 1954

By Z. -E. Nakagawa, O. Yamamoto

After the formation of a concentration gradient of SiC within C-C composite, either zircon or mullite thin films were coated on the surface by sol-gel process. Oxidation resistance tests of as-prepared composites with a couple consisting of a ceramic thin film and a SiC-gradient were then carried out in air at the temperature range from 600 to 1600°C. By the coating of zircon with a thickness of 1.5 µm, a pronounced oxidation resistance was observed; the mass loss by oxidation was almost negligible at 1000°C and one hundredth of original composite at 1400°C. In the case of the coating of mullite with a thickness of 1.0 pm, the marked improvement in oxidation resistance over the whole temperature range examined, from 600 to 1600°C, was found with the combination of a SiC-gradient and a mullite thin film

Jan 1, 2004