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By Randy Settgast, Daniel Moos, Hyunil Jo, Ghazal Izadi, Christine Baba

"Analyses of production logs of multiply fractured horizontal wells in unconventional plays show that only a small percent (~30%) of perforation clusters contribute to production. We present in this paper one possible approach to mitigating this problem, based on use of a fully 3-D numerical model of fracture propagation through a heterogeneous medium, by studying the influence both of spacing and of perforation friction on the initiation and propagation of simultaneous hydraulic fractures from a horizontal wellbore. The results indicate that while limited-entry perforating can help to equalize the lengths of fractures simultaneously growing from multiple clusters, it cannot equalize their widths. Both fracture width and fracture length can be equilibrated by combining non-even cluster spacing with limited-entry perforating. This has obvious benefits as it allows equalized placement of proppant across the entire series of perforation clusters, resulting in similar fracture widths and conductivities which enhances the likelihood that all clusters will contribute equally to production.INTRODUCTIONThere is substantial evidence from production logs and other information that during the hydraulic stimulation of horizontal wells, not all perforation clusters within a given stage will produce. One possible cause is the interaction between the hydraulic fractures emanating from each perforation cluster. Typically fractures created at the outer perforation clusters create “stress shadows”, i.e. increases in compressive stress in the minimum principal stress direction, which limit the growth of fractures growing from interior clusters; this is confirmed by modelling [1, 2, 3]. An example of this can be seen in Figure 1 which shows the final configuration of simultaneously propagating fractures from multiple, evenly spaced clusters when there is no perforation friction. The inner fractures are substantially shorter, reproducing the results by Bunger and Peirce [3]. The inner fractures also have substantially smaller widths.One approach to equalize the growth of simultaneously propagating fractures from a horizontal wellbore is by using limited-entry perforating as a method to equilibrate the flow rates into each of the different perforation clusters. Perforation friction is caused by the finite diameter of the entry points into the formation, and leads to a pressure drop across each perforation which is proportional to the flow rate squared. Fractures that take more fluid have a higher fluid velocity through the perforations than fractures receiving less fluid. This causes a larger pressure drop between the wellbore and more rapidly growing fractures, compared to the same pressure drop between the wellbore and the fractures that grow more slowly. Because pressure within the wellbore is approximately the same at each entry point, the larger pressure drop leads to less pressure being delivered to rapidly growing fractures, thereby decreasing their ability to propagate and reducing the amount of fluid they are able to receive. Because the mass rate of injection into the wellbore is constant, this forces more fluid into the fractures that were propagating more slowly, increasing their growth rate. It also increases the pressure required to drive fluid injection. The balance of these effects makes the system largely self-regulating and delivers more balanced fracture growth. While this effect is well known, it is often neglected in current numerical models."

Jan 1, 2015

By D. Royston

In SAG mills fed with a variety of ore types, hard packing between the shell lifters can come and go depending on rock type and rock size distribution and the presence of a binder. Packing can appear in all sizes of SAG mills, and can be tenacious. High ball impact forces (depending on ball size) in larger mills may compact and encourage packing. Packing can have a negative impact on milling performance and a change in shell liner design may be required to remove it. However shell liner design changes need to be managed with care to ensure liner reliability. In smaller mills control of packing can extend shell plate wear-life and may help to maintain milling performance in fixed-speed mills through the liner wear-cycle.

Jan 1, 2012

By Y. Kusuda

Since 1981, the Annaka refinery has recovered zinc from zinc leach residues by the Waelz Process. The important considerations of this process are the prevention of the growth of coating accretions in the Waelz kiln and the improvement of the zinc volatilization rate. In this paper, simulation predictions and the results of the industrial operation regarding the prevention of coating accretions in the Waelz kiln and the improvement of the zinc volatilization rate at the Annaka refinery are reported and compared.

Jan 1, 2006

By Russell McIntosh

"The Madsen mine is in the southeastern part of Baird township, in Red Lake area, Ontario. It lies about 6 miles southwest of the town of Red Lake, with which it is connected by an all-weather road.The Madsen Red Lake Gold Mines Company was formed in March, 1935, to take over the holdings of the Falcon Gold and Jomac Gold syndicates. During 1935 an4 the early part of 1936 No. 1 shaft was sunk and drifts driven on four levels, all on a narrow quartz vein in a granite dyke.In July, 1936, the Austin zone was discovered about half a mile north of No. 1 shaft by Austin McVeigh, a prospector employed by the Company. Diamond drilling showed that the zone included an orebody worth development, and in 1937 No. 2 shaft was sunk, three levels opened up and sufficient ore outlined to justify the installation of a mill. Milling commenced in August, 1938, at the rate of 300 tons a day, which was later increased to 400 tons a day.The total production from 1938 to 1946 was 1,116,307 tons from which gold and silver having a value of $9,949,010 were recovered. The gold produced ranged from a minimum of 0.1910 oz. a ton in 1939 to a maximum of 0.2827 oz. in 1944. The average grade in 1946 was 0.2345 oz. to the ton."

Jan 1, 1954

By G. E. Wood

Steep Rock Resources Inc. owns a calcite quarry property at Tatlock, Ontario, and a calcite processing plant at Perth, Ontario. The Tatlock marble deposit forms part of an extensive series of carbonate rocks of the Grenville Geological Province in the Precambrian Shield of southeastern Ontario. The deposit is very unusual, if not unique, in the Grenville area in its combination of characteristics of large size, whiteness, high calcium content, low magnesium and silica contents, and scarcity of accessory minerals. A major expansion of the fine grind products capacity of the plant was undertaken in 1982 and came on stream in 1983. The expansion provides important operating benefits at the plant: greater flexibility as to the product mix and reduced dependence on the single grinding mill previously in place. The expanded facility consists of prima,y and secondary crushers, a rotary drye,~ a screenhouse producing a range of screen separator grade products, an airswept Raymond Mill, and a pebble mill with integrated air classifiers, product storage bins, bulk, semi-bulk, and bagged product shipping capabilities, road and rail access, and a substantial product warehouse. The expansion was designed to be compatible with a move into ultrafine calcite production, and is capable of supplying the anticipated sales growth within its market area during the next 5 years. Products are exceptionally white, with good chemistry, low abrasion, and consistent quality. Markets range, according to product particle size, from pre-cast concrete aggregate to fillers for coatings, plastic pipe, and compounds.

Jan 1, 1984

By V. A. Leão, M. L. M. Rodrigues, L. C. Sicupira, I. C. B. Rodrigues, T. C. Veloso

Brazilian sulphide ores can contain a significant content of chloride and fluoride, which are harmful to bacteria and thus bioleaching. This work summarizes a four-year research investigation on the effect of fluoride on both bacterial growth and sulphide bioleaching, supported by studies carried out with secondary copper ores. Firstly, the influence of fluoride on the kinetics of ferrous iron bio-oxidation with Sulfobacillus thermosulfidooxidans was addressed. Values as low as 10.0 mg/L F- fully inhibited bacterial growth, although fluoride toxicity could be overcome by the presence of aluminium, which reduced the concentration of hydrofluoric acid through the formation of aluminium-fluoride complexes. This required at least a 2:1 aluminium/fluoride molar ratio, which ensured bacterial growth rate values similar to that observed in the absence of fluoride ions. Subsequently, both batch and column bioleaching with mesofiles (30 ºC), moderate thermofile (50 ºC) or hyperthermophiles (67.5 ºC) of two secondary copper ore samples were analyzed with focus on the relevant effects of fluoride-containing minerals on the bioleaching of such sulphide ores.

Jan 1, 2014

By K. G. Wheeland, K. G. Byberg

The occurrence of a secondary, dust-fuelled explosion following blasting of sulphide ores has been reported in mines in many countries, including canada, the USA, Australia and South Africa. However there has been little effort to document the events and develop effective control technology. Following a detailed investigation of an incident at the Geco Di vision of Noranda Minerals Inc. , the company held a conference of interested parties in October 1986 to review the state-of-the-art and to agree on action. '!his paper outlines the causes and effects of such explosions, the key conference points and conclusions, and subsequent information-exchange and teclmology-developrnent activities.

May 11, 1988

By José L. Carvalho

"Time-dependent swelling deformation of several shaley rock formations in Ontario is a wellknown phenomenon. In shales and mudstones with a higher salt concentration in the pore fluid than the ambient fluid, the outward gradient generates an osmotic pressure which acts as the driving force for swelling. The swelling phenomenon appears to be related to ion exchange between the rock porewater and the surrounding water.The swelling potential is expressed as the percent swelling strain that occurs per log cycle of time, in either the vertical (perpendicular to bedding) or horizontal (parallel to bedding) directions. In addition, the swelling potential is also noted to be stress dependent. In practice, therefore, the conditions required for swelling are (i) the accessibility to water, and (ii) an outward salt concentration gradient from pore fluid of the rock to the ambient fluid. The relief of in-situ rock stress during excavation serves an initiating mechanism (Lo and Micic, 2010).INTRODUCTIONTime-dependent swelling deformation of several shaley rock formations in Ontario is a well-known phenomenon. In shales and mudstones with a higher salt concentration in the pore fluid than the ambient fluid, the outward gradient generates an osmotic pressure which acts as the driving force for swelling. Swelling is also controlled by the inter-particle bonding; if the bond strength exceeds the osmotic pressure, swelling will not occur, and vice-versa. The bond strength can be reflected by the calcite content which forms cementation bond between rock particles."

Jan 1, 2015

By Guoxiang Chi

The Cornwallis Fold Belt in the Canadian Arctic Archipelago contains numerous Mississippi Valley-type (MVT) Zn- Pb occurrences and the world-class Polaris deposit. The occurrences are mainly hosted by the dolostone in the Thumb Mountain Formation which spreads over 25000 km2. Success in exploration requires further understanding of the genesis of these occurrences and an assessment of their parentage with the giant Polaris deposit. Syn-sulfide dolomites in regional occurrences share C-O-Sr isotopic characteristics similar with Polaris dolomites, indicating warm basinal brines enriched in 87Sr. The dolomites and sphalerites contain fluid inclusions with ice-melting temperature between ?45° and ?25°C, which is significantly lower than for most MVT districts in the world (?30° and ?10°C). These characteristics indicate that all the Cornwallis occurrences were produced by fluids of the same sources and/or aquifers. The deposit size was largely controlled by the rate and duration of the metal-carrying fluid flow, and by the availability of reduced sulfur at the site of mineralization.

May 1, 2001

By H. Vermette, J. Demers, R. Leclerc, P. Bergeron, P. Hudon, A. Lessard

The Arvida Smelter marked its 80th anniversary in 2006. Arvida currently operates 6 potrooms equipped with prebaked side-feeding pots producing 160 000t of aluminum per year, requiring the supply of 300 000t of alumina per year. In the past, to ensure reliable alumina supplies to the pots, especially in winter, a safety stock of alumina was kept inside the plant. The improved reliability of shipping on the Saguenay River has cut the need for such a stock. However, the stoppage of 8 Soderbergtechnology potrooms, starting in the 1980s up to 2003, generated alumina from the cleaning of pot pits, totaling 18000t and leading to the building-up of a significant alumina stock again. Concerns over working conditions, effect on potroom operations, and dust emissions prevented Arvida from tackling effectively this impressive alumina stock. Yet the increasing cost of alumina has created a strong motivation to use the stored alumina. In 2004 Arvida launched a project to recycle the stored alumina. This 4-year project aimed at clearing the alumina stock without affecting the operation of the smelter. It involved changing work organization, improving equipment and controlling the effect of the recycled alumina on the smelting process and working conditions.

Jan 1, 2006

By Jacques Nantel

"The molybdenite property of Brynnor Mines Limited, Boss Mountain Division (wholly-owned subsidiary of Noranda Mines Limited), is situated approximately 360 miles northeast of Vancouver on the east slope of Takom-kane mountain in British Columbia's Cariboo District. Orebodies at the deposit fall into two categories; quartz breccia, and veins and stringers. The development of the breccia ore zone was started in June, 1964. The bulk of the ore is being mined from the stringer ore zone. The ore-body has been divided into 100-foot stopes and pillars. A sub-level blasthole method is used and the broken ore is handled in drawpoints and scram drifts. The development, drilling, blasting and handling of the ore are reviewed. The future pillar recovery operation is also analysed. The paper is also concerned with a scheduled shaft sinking program."

Jan 1, 1970

By John Lund

INTRODUCTION GOLD-BEARING placers of Alaska and the Yukon Territories are buried under a layer of permanently frozen alluvial overburden, or 'muck', which varies in depth from twenty to one hundred feet. The placers, and the decomposed bedrock layers upon which they are deposited, are also permanently frozen. During the summer, surface muck which is exposed to the sun will thaw, but only to a depth of a few feet. To reach a valuable deposit, the frozen overburden must be either penetrated with shafts, or stripped from the deposit entirely. In either case, before the placer can be mined, it must be thawed. At modern dredging operations, the frozen muck is stripped from the placer by powerful jets of water from hydraulic giants. The placer, and several feet of decomposed bed-rock, are then thawed by forcing water through narrow pipes which have been driven into the deposit. Other methods of thawing frozen placers were used extensively during the early years of the Klondike 'gold rush', but experimentation later proved that creek water at its natural summer temperature was a more effective and economical thawing medium than any other which had been used. EVOLUTION OF COLD WATER THAWING Early prospectors of the far north reached placers by digging shafts through the frozen muck. They then thawed the placer sand and gravel by building wood fires at the bottom of the shafts.

Jan 1, 1951

By R. B. Fermor

"The tyndalloscope is used in Europe for dust-hazard assessments in both coal and metal mines. Dust-hazard conditions can be directly evaluated by the tyndalloscope in many underground working situations, once the basic standard table or tables have been prepared from representative mine-rock samples.The tyndalloscope is excellent, in many cases, for diagnostic dust sampling during a working shift, because individual readings can be taken to within three-minute intervals. The limitations of the tyndalloscope are also discussed.The author suggests that a combination of both the tyndalloscope and gravimetric sampling methods would be an ideal match for most mine dust-hazard assessments."

Jan 1, 1970

By C. E. White

The depletion of higher grade mineral reserves will accelerate the trend toward production from progressively larger and lower grade deposits. The discovery of adequate reserves of leaner ores will require the development of improved exploration techniques with a greater depth range. The principal challenges to the Canadian mining industry are to find the mineral resources required to meet fast growing world demand and to develop mining methods and equipment to ensure production costs which will strengthen our position in export markets in the face of in-creasing world competition. The challenges cannot be met without intensive efforts to attract more technical men to the industry and to improve their training.

Jan 1, 1967

By J. M. B. Scarborough

This paper deals with measures taken to maintain effective operation of heavy-duty equipment in open-pit mining. at Pine Point, N.W.T., during periods of extreme cold weather. The points covered include equipment modifications designed to improve cold-weather performance, effective lubrication of machinery that is vulnerable to extreme cold and operating procedures designed to prevent equipment damage.

Jan 1, 1966

By M. Fafard, F. Chevarin, D. Ziegler, H. Alamdari, M Kavand

"Carbon anodes, used in the Hall-Heroult process, are consumed by the electrochemical reaction to produce metallic aluminum. It is also consumed by parasitic reactions with air and CO2. The carbon anode is made of petroleum coke with different particle sizes, butts (recycled anodes) and coal tar pitch. The mixture of fine particles (less than 150 µm) of coke together with the pitch material forms a matrix, binding the large coke particles together. It is generally thought that the binder matrix is more reactive than the other anode constituents. This conjecture was not clearly proved in the literature. The present study is focused on the CO2 reactivity of binder matrix and anode constituents at 960°C, both under chemical regime (100% of CO2) and under a concentration gradient (diffusion). The apparent reaction rates of these materials were measured. The role of the binder matrix in anode consumption and its disintegration (dusting phenomenon) was discussed.INTRODUCTIONThe metallic aluminum production is one of the most important industries in Canada. The Al metal is obtained by the Hall-Héroult process. The principle of this process is the electrochemical reduction of alumina in molten cryolite carried out by an electrical current between carbon anodes and cathode at 960°C (Equation 1). The carbon anode is typically composed of calcined petroleum coke (65 wt.%) and recycled anode (called also butt, 20 wt.%) with coal tar pitch (15 wt.%), playing the role of cement to ensure the cohesion of the anode block."

Jan 1, 2016

By W. B. Xie

The hardening behaviour and microstructure evolution of Cu-30Ni-30Mn alloys aged at 350 °C has been investigated utilizing optical microscope, scanning electron microscope, transmission electron microscopy and Vickers hardness tester. The results show that the discontinuous precipitation of NiMn phase results in a remarkably hardening effect in Cu-30Ni-30Mn alloy during aging at 350 °C. The maximum hardness (~494HV) is attained in the sample after aged for 48 h. The NiMn precipitates are ordered and have a face-centered tetragonal structure. The coherent orientation relationship between the NiMn precipitates and Cu matrix is (220)Matrix // (220)P, [1-1-2]Matrix // [1-1-2]P. In addition, there is a linear relationship between hardness and volume fraction of the discontinuous precipitation, which indicates that the hardness increment of Cu-Ni-Mn alloys aged at 350 °C is attributed to the microstructure characteristics of discontinuous precipitation. The high strength of discontinuous precipitation colony is caused by the formation of nanoscale NiMn precipitates with a lamellar structure in discontinuous precipitation. INTRODUCTION Cu-Ni-Mn alloys are attractive candidates for oil drilling, aerospace and energy applications due to their high elasticity, high strength and excellent corrosion resistance (Sun et al., 2009; Liu, Yang, Xia, Jiang, & Gui, 2016). The high strength of the Cu-Ni-Mn alloys is mainly attributed to the precipitation of NiMn phase (Shapiro, Tyler, & Lanam, 1974; Xie et al., 2015). The uniformly dispersed nanoprecipitates formed by continuous precipitation can impede dislocation movement, and thereby lead to a significant improvement in strength of traditional precipitation-strengthened alloys. However, it is reported that there are two precipitation types observed in Cu-Ni-Mn alloys, namely, continuous precipitation and discontinuous precipitation (Shapiro et al., 1974). The discontinuous cellular colony with a lamellar structure nucleates at grain boundaries, and progressively grows inward the grain on the process of discontinuous precipitation (Ng, Bettles, & Muddle, 2011). It is found that the discontinuous precipitation can occur in many Cu-based alloys, such as Cu-Ni- Mn alloy (Shapiro et al., 1974), Cu-Be alloy (Monzen, Hasegawa, & Watanabe, 2010) and Cu-Ni-Sn alloy (Zhao, & Notis, 1998). Many studies consider that the discontinuous precipitation results in a detrimental effect on hardness and strength, and the discontinuous precipitation occurring during aging treatment should be suppressed (Markandeya, Nagarjuna, & Sarma, 2004; Semboshi, Sato, Iwase, & Takasugi, 2016). The mechanical properties can also be improved by discontinuous precipitation in AZ91 magnesium alloy (Tamura, Kida, Suzuki, & Soda, 2009) and AM30 magnesium alloy (Saikawa et al., 2012). Jun (2017) found that the reduced interlamellar spacing of precipitate fibers in discontinuous cellular colony leads to a significant increase in hardness. Indeed, the strengthening contribution of discontinuous precipitation is similar to that of continuous precipitation in Cu-20Ni-20Mn alloy. Discontinuous precipitation of NiMn phase can provide a significant strengthening effect in Cu-Ni-Mn alloys.

Jan 1, 2019

By Michel Dagbert, Mohammed Harfi

"Abstract - The Draa Sfar polymetallic deposit, at about 16 km NW of Marrakech in Morocco, is a massive sulfide zone at the contact between an underlying volcanic and an overlying clastics sequence. The mineralized body is a flat lens with schistosity and "boudinage," tilted to the west and with a strong dip to the east. The lens extends over a strike length of about 2 km and from surface to a depth of about 1 km, with thickness varying from 1 m to almost 30 m. It has been intersected by about one hundred surface drill holes and, in its south part, by about thirty underground fan holes from two exploration levels at depths of 300 m and 400 m. On these two levels, the massive sulfide zone has been channel sampled over a cumulative length of about 0.7 km. Results from drill and channel samples are used to estimate the resources of the orebody according to several methods: sections, polygons around intercepts on a longitudinal plan, grids on the same longitudinal plan with various distance weighting methods including kriging and, finally, a 3D grid with the same range of interpolators. A comparison of the various estimates delineates the important factors in deriving resources for this type of deposit. Those factors are mostly geological and related to the interpretation of the geometry of the two limiting surfaces of the zone. For the 3D gridding, the authors have devised a new and original method that constrains the interpolation of blocks from samples to a geometry of limiting surfaces. The resulting model shows internal grade variations that parallel fluctuations of zone thickness and orientation without having to re-orientate the search window in each block. Résumé - Le gisement polymétallique de Draa Sfar, situé à environ 16 km au NW de Marrakech est un horizon de sulfure massif au contact d’une formation volcano-sédimentaire de base et d’une formation détritique sur-jacente. Le corps minéralisé se présente sous forme d’une méga-lentille aplatie, schistosée, boudinée et déversée vers l’ouest avec un fort pendage vers l’est s’étendant sur une longueur de 2 km et une profondeur de près de 1 km avec une épaisseur variant de moins d’un mètre à près de 30 m. Il a été reconnu par plus d’une centaine de sondages de surface et, dans sa partie sud, par une trentaine de trous souterrains en éventail à partir de deux niveaux à des profondeurs respectives de 300 m et 400 m. Sur ces mêmes niveaux, des traçages ont permis de rainurer le minerai sur une longueur cumulée de 0.7 km. Les données de sondage et de rainurage ont servi à estimer les ressources du gisement selon plusieurs méthodes : sections, polygones sur longitudinale, grille sur longitudinale avec différentes pondérations en fonction des distances incluant le krigeage et enfin grille tridimensionnelle avec le même éventail de pondérateurs. La comparaison des estimés obtenus permet de mettre en évidence les facteurs importants dans l’estimation des ressources de ce type de gisement. Ces facteurs sont essentiellement géologiques et relatifs à l’interprétation de la géométrie des limites des corps minéralisés. Pour l’estimation sur grille tridimensionnelle, on a mis au point une technique originale qui calque l’interpolation des blocs à partir des échantillons sur cette géométrie des surfaces de contact. Le modèle résultant montre des variations internes de teneurs qui épousent les fluctuations d’épaisseur et d’orientation de la zone sans qu’il soit nécessaire de ré-orienter les fenêtres de recherche dans chaque bloc."

Jan 1, 2002

By Gaston Gingras

"IntroductionL'entretien de l'equipement minier dans les mines à ciel ouvert est une activité qui est aussi vieille que I'existence des mines et qui a progressé au cours des années pour suivre l'évolution des techniques d'exploitation. Lors de la mise en usage de s premières pelles à la va peur, celles-ci étaient généralement entretenues par I ‘équipe de quatre hommes qui était responsable de son opération. Pour les travaux plus compliqués ils utilisaient les services de machinistes qui eux savaient comment réparer Ie moteur à vapeur et couler des coussinets de ""babbit"". Les premières pelles diesel étaient entretenues de la même façon mais pour les réparations au moteur, on devait recourir au représentant du manufacturier qui était Ie seul à avoir les compétences nécessaires.Ce n'est vraiment qu ‘après la deuxième guerre mondiale que I ‘usage de l'équipement mobile s'est répandu dans les mines à ciel ouvert pour débuter les extractions selon les méthodes que I'on connaît aujourd'hui.L'entretien de l'équipement minier de façon organisée à débute avec I ‘usage de ces machines dans nos mines. Ces machines étaient un peu primitives, petites et pas très dispendieuses a I'achat. Même si la disponibilité était basse, elles fournissaient quand même un rendement qui en ces temps était acceptable. L’organisation de I ‘entretien de cet équipèrent était assez primitif et n'occupait qu'une place secondaire aux yeux de la direction de la mine."

Jan 1, 1988

By J. C. Allan

THE purpose of this paper is to outline the pogress made in the development o the gravity separation method o ore dressing known as Sink-and-Float, which, in the opinion of the writers, has now reached a stage justifying the claim that this new method marks a highly important advance in the technique . The essential feature of the newest development of this process is the extremely accurate separation achieved. This is responsible for higher extraction in the sink-and-float unit on coarse sizes and, in consequence, for substantially higher overall recoveries. Whilst this is the most remarkable feature of the new process, it has further important contributions to make to ore dressing under the following heads: (1) The introduction of the sink-and-float separator as a buffer helps to iron-out irregularities in the mill feed. By supplying a concentrate of constant grade to the flotation section, the process also indirectly improves overall recovery. (2) The addition of a sink-and-float unit to an existing mill results in substantial increase in capacity at low per ton capital cost. (3) Where the plant can be installed underground for the pre-treatment of low-grade ores, there is a saving in hoisting costs, and excellent 'fill' is provided near the point of use. ( 4) Low-grade mixed oxide-sulphide copper ores may be pre-concentrated, thereby producing a flotation feed sufficiently rich to render the oxide residue from such flotation economic for subsequent treatment by leaching or other methods. (5) Application of the process eliminates hard gangue constituents which cause high grinding costs, or gangue constituents which adversely affect flotation. The plant is compact and easily controlled. No highly skilled operators or expensive reagents are required, and the labour and power per ton are low. The separator is extremely flexible, working equally efficiently on any throughput up to its maximum capacity.

Jan 1, 1940