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By Albert W. Scragg

"THE ADMINISTRATION DEPARTMENT consists of six sections, all with their own supervisors, reporting to the superintendent of administration. Although each of these sections is uniquely separate, they all work together, in one department, to provide very necessary services.1. Accounting 2. Purchasing 3. Warehousing 4. Data Processing 5. Inventory Control6. Office ServicesThis department, which now numbers 108 people, had its birth in an office over a hardware store in downtown Timmins in 1964. Initially, only basic accounting and purchasing functions were performed and these, of course, were on a very small scale. The growth of the administration department is a function of the growth of the company."

Jan 1, 1974

By Z. S. Abisheva

The Zhezkazgan copper sulfide ore deposit in Kazakhstan contains both rhenium and the rare osmium isotope "osmium-187" (187Os) in the high isotopic purity of 99.4 ± 0.2%. This isotope is believed to have originated as a result of the disintegration of one of the rhenium isotopes, according to the reaction: 187Re75 ?> 1870576 + B- + v~ (where B is a 13-particle, v~ is a 3-disintegration antineutrino). The distribution of osmium and rhenium in metallurgical byproducts produced during the recovery of copper from these ores has been studied and process flowsheets for the processing of rhenium and osmium-containing byproducts have been developed.

Jan 1, 2007

By Javier Ramirez

"Recent R&D pilot plant testing was done to validate a full industrial scale system for recovering residual magnetite from the tails of an iron ore concentration plant. The recovery system is based on an autogenous heavy media separator treating a tailings slurry at 0.45% solids by weight. A 3,100 m3/h capacity concentrator was installed based on the testing findings. Excellent metallurgical results have been observed in two years of continuous operation. This experience is the basis for the proposal of a novel process consisting of the preconcentration of base metals ores; the idea being to obtain a heavy bulk concentrate of the polymetallic minerals and discarding in one step the light gangue mineral components. The bulk concentrate then proceeds to conventional froth flotation. The reduced volumetric flow of the bulk concentrate allows a reduction in the size of the subsequent flotation circuit. A prerequisite for the heavy media separation is a fine size grinding of the ore and a correspondingly high degree of liberation of the mineral species to be recovered. A process scheme is also presented in which the gravity concentrator works in conjunction with a companion tailings thickener for process water recovery. The underflow from this thickener, having paste consistency, can be sent to a tailings dam or mixed with Portland cement for mine backfill. The process water in the system is managed at an estimated recovery in excess of 98%. Additional R&D work using this novel approach is being considered by a large iron ore concentrator for removal of liberated silica from the final concentrate; and for upgrading 3.5 million tons of a marginal hematite reserve owned by the mining company.INTRODUCTIONGravity preconcentration (static and dynamic) of sulphides prior to froth flotation has been and is being practiced at various concentrator plants (Asarco´s Young Mill: heavy media cone; Mount Isa: DSM cyclone; Afton Mines: Denver jigs; Tsumeb Mine: Reichert cone) (Burt, 1984). The idea behind installing preconcentration equipment is to reduce the volume of feed processed on flotation, thus requiring smaller flotation plants although other advantages may be of importance, such as obtaining richer concentrates due to higher grade feed, better process water and energy management, and reduced flotation reagent consumption.The SedconTM solid/liquid separator is a versatile process unit patented in Mexico (MX/u/2007/000305). As a gravity device, it may be classified as an autogenous heavy media dynamic concentrator. Figure 1 depicts the Sedcon (Sedimentador de conos) separator. The four main components are as follows: the feedwell for efficient mixing of the pulp with dilution water and flocculant (and coagulant for water clarification); the inner cones (passive elements for solid/liquid separation); the discharge underflow cone; and the scraper mechanism. The standard discharge cone is a 60° inclined cone for general applications. For paste tailings thickening applications, a deep cone with a 69° inclined cone is used."

Jan 1, 2016

By Shae K. Kim

The aim of this study is to manufacture magnesium alloys with alkaline earth metal oxides (BeO, CaO, MgO or SrO) additions with the objectives of (1) ensuring safety during processing and applications by raising the ignition temperature and reducing oxidation, (2) protecting the environment by reducing or eliminating use of protective gases, (3) maintaining or improving elevated temperature properties with lower amount of Ca or Sr or rare earth metals when compared with conventionally developed high-temperature magnesium alloys, (4) developing cleaner strip casting and continuous casting processes without hot tearing and (5) obtaining all of these objectives without sacrificing mechanical properties or increasing the cost of magnesium alloys.

Jan 1, 2006

By Alexander Smith

"The three principal known mineral deposits of the Taku River area lie in the Tulsequah synclinorium. The axis of this north-south trending structure is along Tulsequah River valley; about 6 miles east of the eastern contact of the Coast Range batholith.The one proven mine of the area, the Polaris-Taku, is on the west side of the valley. It is a gold property, the gold occurring in fine needles of arsenopyrite disseminated in carbonatized volcanics. The mine was originally called the Whitewater, and the adjacent area the Whitewater gold belt. During the years 1937 to 1942 gold having a value of $3,284,000 was produced from 313,500 tons of ore milled."

Jan 1, 1954

By RAYMOND C. HARTVIKSEN

The Drumbo Mine is located near Highway 401 between Woodstock and Kitchener in southwest Ontario. The tabular flat-lying gypsum bed is between 1.5 to 2.4 m thick and is situated near the base of the Salina Formation, about 116 m below surface. The mine is owned and operated by Westroc Industries Limited. The 3.8 m diameter shaft was drilled using a Hughes CSD 820 drilling rig and a liner sinking technique new to the North American continent. The shaft was completed in the fall of 1977, and remaining facilities were finished in the fall of 1978. Gypsum production started in December 1978, employing the conventional room-and-pillar method of mining.

Jan 1, 1984

By V. C. Pandolfelli, S. F. Santos, L. A. Rodrigues

Under conditions of stable crack propagation at room temperature, the elastic energy stored in ceramic materials is converted mainly to surface energy. However, at high temperatures, creep may also occur in such materials, in which case it will present a ductile behavior. This paper discusses the brittle-ductile transition of a refractory material. Stable crack propagation and creep tests were carried out under a three-point bending device. A commercial ceramic containing 63 wt-% of SiO2 and 31 wt-% of Al2O3 was used as testing material. The results revealed that the change in behavior from brittle to ductile was caused by softening of a vitreous phase present in the material's microstructure.

Jan 1, 2004

By J. H. Baek, S. Alexandrovskii, D. W. Lee, B. K. Kim

Nano-phase titanium carbide was synthesized by Mg-thermal reduction process using a novel route of Mg-thermal reduction. The processes are based on I) feeding of TiC14+CxC14 x = 1, 2 ) solution into liquid magnesium, 2) Mg-reduction of metal chlorides, 3) TiC formation by the reaction of released Ti and C atoms, and 4) vacuum separation of residual liquid phases of Mg and MgCl2. In this study, the process for titanium carbide production with composition close to stoichiometry and the minimum content of impurities was optimized with the various process parameters such as concentration of initial solution, its feeding rate and reaction temperature, as well as a kinetic study.

Jan 1, 2004

By L. V. Chugaev

In the course of the hydrothermal refining of copper-nickel products containing covellite, oxidation of Fe2+ ions by the CuS?Cu2+ pair takes place, and iron is precipitated as hematite. Lower copper concentrations in the solution and higher solution acidity lead to the partial oxidation of sulphide sulphur, whereupon hematite is reduced by covellite causing iron to go back in solution. It is demonstrated that in the process of hydrothermal treatment of the covellite-containing solid product in pure water covellite oxidises millerite to polydymite (Ni3S4). Formation of polydymite during the process of refining seems to be due to millerite oxidation both by covellite and the CuS?Cu2+ pair.

Jan 1, 2007

Cambior has been involved in the Guiana Shield since 1990, first in Guyana and then in Suriname starting in 1994. This paper presents the history of Omai Gold Mines Limited in Guyana, where commercial production started in 1993 after an investment of US $150 million. In 1995, the mine was expanded in order to increase the milling capacity to 21,000 tonnes per day. After ten years of production, approximately 3 million ounces of gold have been produced. Building on this experience, Cambior became involved in Suriname with the Rosebel Project. A US $95 million pre-production program started in the fourth quarter of 2002, and the mine should be in commercial production early in 2004.

May 1, 2003

By L. Avramovic, B. Han, R. Jonovic, Z. Stevanovic, K. Haga, S. Dimitrijevic, A. Shibayama, L. Godirilwe, Y. Takasaki

Pyrite (FeS2) and chalcopyrite (CuFeS2) which could not be recovered, are present in mine tailings discharged from Bor copper mine. About 0.3% of copper (Cu) is contained in these tailings, therefore it can be considered as a useful copper resource. At the same time, pyrite is known to promote acid mine drainage, therefore it is necessary to detoxify the tailings. An efficient method has been proposed to recover copper and reduce the environmental impacts of tailings by a combined hydrometallurgical process of high pressure leaching (HPL), solvent extraction (SX) and electrowinning (EW) process. HPL process yielded high copper leaching rate (>95%) when water (H2O) was used as a leaching media. On the other hand, pyrite contained in the tailings was converted to iron oxide by high pressure leaching. Stability evaluation of the residue obtained from high pressure leaching, confirmed almost no elution of metal ions. The percentage of copper extracted and stripped from the Cu-loaded organic phase reached 97.4%. Moreover, it was confirmed that a low iron concentration in the electrolyte of copper electrowinning, resulted in the improvement of current efficiency of copper electrodeposition. INTRODUCTION Mine tailings are a by-product obtained from the flotation process and there are billions of tons of already existing tailings all over the world. Moreover, several billion tons of additional copper tailings will inevitably be produced in the coming years (Onuaguluchi & Eren, 2012). With the declining average copper ore grade, alternative sources of copper are highly sought, mine tailings have a comparable copper grade to that of low-grade ores (0.2–0.3%) therefore, it can be said that copper mine tailings present a very important source of secondary raw material for copper production (Antonijevi´c et. al., 2008). Consequently, it is necessary to confirm the possibility of the valuable metals (such as copper) recovery from mine tailing in which copper content is about 0.2–0.3%. Our group investigates the flotation and high pressure leaching processes for recovering of copper from mine tailings. Previous work on related samples include copper and nickel flotation tailings from Botswana, and a low–grade copper ore sample from Chile. Impurities, which are associated metals in mine tailing such as iron (Fe) and aluminum (Al) co-dissolve into the solution during the HPL treatment process. Therefore, separation of copper from impurities is necessary for selective extraction of copper from mine tailings and upgrading the copper concentration in the leachate to enable further purifying of Cu by electrowinning. Thus, it is important to investigate the possibility of applying solvent extraction for concentration of copper from leachate solutions of mine tailings (Onuaguluchi & Eren, 2012; Antonijevi´c et. al., 2008). In this study, LIX-84I was used as an extractant of copper from the leachate of high pressure leaching of mine tailing. As a fundamental solvent extraction investigation, the extraction behavior of copper was studied using a simulated solution of the leachate from the high-pressure oxidative leaching of mine tailing. The effects of; solution pH, extraction time, extractant concentration and phase ratio on copper extraction and sulfuric acid (H2SO4) concentration on stripping were investigated.

Jan 1, 2019

By L. Nutter, J. Clancy

"Barite is used extensively by the oil and gas well-drilling industry as a weighting agent. It is particularly well suited for drilling mud because of its qualities; it is non-abrasive, heavy, virtually inert chemically, easy to handle and inexpensive compared to other available heavy materials. Increased deep well drilling in Western Canada, and especially in the Arctic regions, could dramatically affect the demand for barite through this decade. Known deposits in northeast British Columbia are possible sources of incremental barite supplies, should the situation develop.IntroductionThe purpose of this report is to examine the opportunities for expanding barite production in British Columbia. Of primary interest will be the relationship between the projected future levels of production and consumption of barite in Western Canada and the extent to which increased domestic production could replace the need for imports in filling any expected supply shortages.After a brief overview of the nature and uses of barite and some of the relevant features of the barite supply industry, the discussion will turn to the supply gap in the Canadian market and the possibilities for import substitution.OverviewBarite is an industrial mineral which is used in large quantities by the oil and gas well-drilling industry. It is often an important component of drilling mud, a fluid circulated continuously in the well during the drilling process to lubricate and cool the drilling apparatus and to contain the high oil and gas pressures found at depth. Barite (BaSO4) is particularly well suited as a weighting agent for drilling mud because it is a heavy (specific gravity to 4.5) inert mineral which is inexpensive in relation to other materials having a high specific gravity. In the on-site use of drilling mud, ground barite is combined with numerous other solid ingredients and chemicals in the form of a slurry. Other advantages of barite include cleanliness, ease in handling and its non-abrasive character (hardness of 3-3.5)."

Jan 1, 1982

By A. L. Rutledge, R. S. Nichols

"Waste dump development at the Fording River Operation s in British Columbia began in 1971. In 1981, several unique as well as unplanned situations provided an opportunity to study water flows through waste dumps.The key to the drainage is naturally segregated rock sizes .created by end dumping from the crest of a pile. The largest size material accumulates at the toe. Flow rates along the base of the studied dumps varied from 2,800 to 13,500 m3/day or 0.032 to 0. 156 m3/s (1.2-5.5 cfs}. Sediment concentrations in the water ranged from 1 to 1,800 mg/I.This paper describes water flows through dumps of varied lithology and maturity. The results suggest that neither long-term water flow nor contained sediments in small streams are jeopardized when crossed by end-dumped fills.IntroductionThe Fording River Operations are located in southeastern British Columbia approximately 115 km north of the United State s and 10 km west of Alberta, within the medial range of the Rocky Mountains. All production is carried out at elevations ranging between 1,600 and 2,200 m above sea level.The property is within a continental climatic zone, with temperature extremes of - 40°C in January to +35°C in July. The average annual precipitation of 335 mm of rainfall and 390 cm of snowfall feeds the numerous seasonal, small drainage courses along the Fording River valley.Since start-up in 1971, 149 million bank cubic met res of waste from truck-shovel and dragline mining have been placed in numerous dumps or ""spoils"". The dumps were developed to the point that several unique situations could be studied. During the peak run-off period of May-June 1981, water flow studies were performed on dumps of varied lithology and maturity. This paper describes the results of the study."

Jan 1, 1982

By S. E. Malouf, W. Thorpe

"The Chibougamau Explorers property comprises 35 claims or 1,726 acres in La Dauversiere and Rohault Townships along the west shore of Norhart Lake. The property is serviced by a twelve-mile all-weather high-way leaving the main St. Felicien-Chibougamau highway at mileage 121. This road junction will be a railway siding on the C.N.R. St. Felicien-Chibougamau branch line in early 1957. The property lies 30 miles due south from the town of Chibougamau. The mine-sponsored Chibougamau Explorers town has a population of 250 with 28 residences and a well equipped recreation centre.The original showing was found by Rider Storn, a prospector financed by Val d'Or interests during the 1950 field season. This showing did not stand up to detailed prospecting but it did lead to the discovery of the main zone by A. Oakley during the following winter.The company was incorporated in I 950 under the presidency of E. Ayrhart. Financing following the initial drilling involved an increase of capitalization from 3 to 5 million shares and the advent of financing and management control by Anacon Lead Mines Limited.Exploration and development to Jan. I, 1956, has included 42,331 feet of surface diamond drilling; 31,363 feet of underground drilling; a 3-compartment shaft to 1,245 feet, with 8 levels at 150-foot intervals; and I 1,054 feet of drifts, crosscuts, and raises. Ore reserves to the 900-foot level, proven and partly developed, total 546,725 tons averaging 0·30 ounces gold and 0·93 per cent copper. A mill with capacity of 500 to 750 tons will be installed by January 1956.GeologyThe Chibougamau Explorers property lies along the belt of Keewatin volcanics striking through Bachelor Lake, Opawica Lake, Doda Lake, Coapatina, Norhart Lake, and Rohault Lake, where it is in close proximity to the paragneisses of the Grenville series. The boundary of the paragneisses, a gradational contact, lies within a mile of the Chibougamau Explorers shaft collar."

Jan 1, 1949

By P. Ramirez

"To achieve an optimal metallurgical performance in the flotation process the bubble diameter should be between 0.5 and 2.5 mm. To control bubble size, frothers are added, reducing bubble size and conferring bubble stability against coalescence. However, the bubble generation mechanism determines predominantly the bubble size distribution produced. In mechanical flotation cells, bubbles are produced by the shear stress generated by a rotating blade on a gas stream. This mechanism produces a log normal bubble size distribution. In contrast, in column flotation, jetting gas injectors are commonly used in Chile and the bubble size distribution is bimodal with small and large bubbles. Bubbles larger than 2.5 mm mean a loss in surface area, while bubbles smaller than 0.5 mm move with the pulp stream and therefore collide less frequently with particles. In this paper, a new device based on a jetting sparger and a deflector disc (impinging jetting) is evaluated as an alternative sparger for column flotation.The new device was tested in a rectangular acrylic cell 1 m × 0.5 m × 3 m. High-speed cinematography was used to compare bubble generation with jetting and impinging jetting at different gas velocity in the nozzle (5–50 m/s). From the image analysis, it was observed that the deflector induces a shear stress, in analogy to a rotating blade but in this case the shear results from a high velocity gas hitting a static surface. The device was evaluated in a 0.5 m diameter 3 m high column. The McGill bubble viewer technique was used to compare the bubble size generated by jetting and impinging jetting. It was found that the Sauter mean bubble diameter reduced from 7.4 mm to 2.8 mm, when the jetting sparger was modified with the deflector. In the case of the impinging jetting sparger, 70% of the bubbles were in the effective range for flotation, while for the jetting sparger, only 10% were in the effective range."

Jan 1, 2016

By M. E. Stutt, R. H. Rehder

"The mining industry is taking advantage of the increased performance resulting from the use of variable speed A C drives for large motors. This technology provides increased efficiency under the variable speed and torque requirements of such drives as mine hoists, conveyors, and air moving equipment. The technology does introduce voltage spikes on the voltage wave form that stress the insulation system to a greater degree than would occur with a constant voltage source. These voltage spikes must be considered in the design of the insulation system used for these motors.BackgroundHistorically the insulation systems for large AC motors were designed to withstand with reasonable life the voltage stresses of a 60 Hz constant sinusoidal voltage. One of the design tests is a voltage endurance test that requires the application of a 60 Hz voltage from conductor to ground equal to four to five times normal and establishing a time to failure. These higher than normal voltages accelerate the normal aging process by causing extensive partial discharge activity (corona) within the insulation system and the time to failure is a relative indication of insulation life.In addition to the voltage endurance test at 60 Hz, the individual coils are subjected to a surge voltage test to establish the withstand capability of the turn to turn insulation under switching surge conditions. The surge voltage is a fast rise time, 0.2 microsecond to crest value, voltage spike that can be caused by a circuit breaker or contactor closing operation. These voltage spikes can have a crest value of greater than 3.5 times the normal line to ground crest voltage of the normal 60 Hz power supply. The standard withstand test value is thus 3.5 times normal line to ground voltage. Because the voltage surges or spikes occur mainly during start and stop switching conditions, voltage endurance under these conditions has not been a major factor in insulation system design."

Jan 1, 1995

By Z. D. Hora

Brick shales and refractory clays are mined at Sumas Mountain near Abbotsford. Sholes and stoneware clays elsewhere in the province have not been developed. THE SUMAS MOUNTAIN deposit near Abbotsford, 80 km east of Vancouver, has been in continuous production since 1905. The deposit is exposed in a small outlier and comprises a sequence of alternating beds of clay and sand. Beds are of Eocene age. Within the 400 m thick ness of sediments are seven distinctive conglomerate members, some up to 20 m thick, interbedded with fine grained sediments including claystones and siltstone , or "shales". Shale is quarried to produce a variety of bricks, sewer pipes and similar products; it is also used for cement. Several different shale beds have been mined over the years and exhibit a variety of fired colours ranging from buff-pink grey to deep red; pyrometric cone equivalents (PCE) range from 3 to 20. A layer of fireclay 3 to 4 m thick that occurs at the base of the sequence has pinkish white to light buff fired colour and PCE of 30 to 33. It is used as a 266 primary component to produce refractory bricks. The shale is quarried and processed by Clayburn Industries Limited of Abbotsford. Another similar but smaller outlier of the same geological formation is known from Blue Mountain, about 20 km northwest of Mission. Other ceramic clays in British Columbia are reported from Quesnel (7 m bed of white stoneware clay, PCE 17 to 19), Giscome Rapids (25 km north of Prince George, 10 m bed of stoneware clay to PCE 31) and anaimo-Comox area (buff to red firing "shales", PCE 8 to 10-1 12) . From 1959 to 1974 Cretaceous shale from Saturna Island in the Strait of Georgia was used to produce lightweight aggregate. Similar deposits of expanding shale are known from the vicinity of Duncan on Vancouver Island.

Jan 1, 1984

By C. C. Allen, H. H. North

"The Young-Davidson mine is in the southeastern part of Powell township, in the district of Matachewan. It is 32 miles southwest of Kirkland Lake, 48 miles southeast of Timmins, and 25 miles by road Northwest of Elk Lake. The Young-Davidson and its neighbour, the Matachewan Consolidated mine, are the two present producing properties in the district. The Matachewan area is the southwestern extension of the Kirkland Lake belt or 'break'. The Young-Davidson mine since coming into production in 1934 has been operated by Hollinger Consolidated Gold Mines, Limited. ""Desultory prospecting(1) has been carried on in the Matachewan area from time to time since the discovery in 1906 of silver in James township at Elk Lake, and some gold has been found in the southeastern part of Alma township and in the central part of Cairo township. The first real interest in the area, however, was started by Jake Davidson's discovery in 1916 of gold on Davidson creek, on what is now part of the Young-Davidson property, and by Sam Otisse's discovery shortly afterwards on claims a short distance to the east, now part of the Matachewan Consolidated property. In subsequent years both of these properties were investigated by various companies; the Young-Davidson chiefly by the Porcupine Gold fields Development and Finance Company, Limited, and the Matachewan Canadian by the Colorado-Ontario Development Company, Limited, which in 1919 was reorganized under the name of Matachewan Gold Mines, Limited. Work was discontinued as the ore was considered too low in grade to be mined"". However, in 1933 Hollinger Consolidated Gold Mines, Limited, undertook to bring the property into production and this became a reality in 1934.The total production to the end of year 1945 was 319,185.59 oz. gold and 73,541.94 oz. silver from 3,228,845 tons of ore. This represents an average grade of $3.67, including exchange and premiums."

Jan 1, 1954

By Richard C. Williams, Herman Pieterse, Ken Thomas, K. S. Fraser, Ron H. Colquhoun

"The Banick Goldstrike Mines Inc. (Goldstrike) operation is located in Eureka County in north-central Nevada on the Carlin geological trend. Gold in the sulphide mill feed, occurs primarily as submicroscopic inclusions or possibly solid solution in a pyrite and marcasite matrix. Sulphide mill feed is pretreated in a pressure oxidation plant allowing gold recoveries of 90 per cent and greater to be achieved. Anticipated 1994 gold production for the sulphide gold facility is approximately 1,500,000 ounces.In January 1989 American Banick Resources Corporation (Banick) announced the US$365 million Betze Development Plan for the Goldstrike property. The Betze plan was based on a three (3) staged expansion of the original 4,500 STPD oxide gold plant. This expansion would involve addition of ore and gold processing capacity and the total conversion of all ore handling facilities to treating Betze sulphide ores.Phase 1 of the Betze Development Plan involved the construction of a pressure oxidation circuit, including a single autoclave and supporting ancillary services. The pressure oxidation circuit was commissioned in February 1990. Currently a throughput of 2,000 STPD is being achieved.Phase II of the Betze Development Plan, commissioned throughout April and May 1992, included the expansion of grinding, leaching, and gold recovery facilities enabling the treatment of combined oxide, and sulphide ore. Pressure oxidation capacity was increased by the addition of two (2) autoclave circuits each treating 2,600 STPD of sulphide ore and other required ancillary services. By June 1992, the Phase II gold facility had achieved a combined throughput of 15,000 STPD of oxide and sulphide ore.Phase Ill, the final stage of the Betze Development Plan, was successfully commissioned in February and March 1993. This final stage of development increased the design throughput of the pressure oxidation plant to 15,000 STPD by the addition of three (3) autoclave circuits with combined capacity of 7,800 STPD."

Jan 1, 1994

By R. J. McLeod

"Grinding at Giant Yellowknife is done in two stages. The first stage consists of two ball mills in closed circuit will: mechanical classifiers, the classifier overflow goes to flotation. The tailings from this flotation circuit are separated into slime and sand portions, the slimes go to an additional flotation circuit while the sand portion goes to the secondary grinding mills.Milltronic automatic sound control units were installed on each of the two primary ball mills and put into operation September 3, 1966. After about two months adjustments to the control units the operators were taken off the grinding circuit on November 1, 1966. The operators duties were taken over by the automatic control units while miscellaneous work was taken over by the helpers in the mill. The labour saving by the installation is approximately $2250.00 per month.After a short period of operation it was apparent there was a slight change in grind. The screen analysis of the primary classifier overflows for the period May to August 1966 averaged 62.23% minus 200 mesh while for the period September to December 1966 averaged 62.0% minus 200 mesh. This is a slight coarsening of the grind. The change in the primary grind has manifested itself also in the screen analysis of the final grind. Before automation the final grind was 80% minus 200 mesh, while after automation it was 7 5% minus 200 mesh. A change of grind was also noted in the flotation concentrates. Before automation the screen analysis of the concentrates was 35% plus 200 mesh and 50% minus 3 25 mesh. A ft er automation it was 35% plus 200 mesh and 47 .5% minus 325 mesh. In other words the grind got coarser or perhaps we should say there was less overgrinding. Another significant change took place in the assays of the slime and sand portion of the primary flotation tailings. It was usual under manual control for the slime portion to assay higher in gold than the sand portion. The reverse is now true."

Jan 1, 1967